Honors & Awards


  • NIH Director's New Innovator Award, NIH (2009)
  • Burroughs Wellcome Fund Investigators in Pathogenesis of Infectious Disease Award, Burroughs Wellcome Fund (2011)
  • NIH Director's Pioneer Award, NIH (2017)
  • AGA Research Mentor Award, American Gastroenterological Association (2023)

Professional Education


  • BS, UC Davis, Biochemistry (1996)
  • PhD, UC San Diego, Biomedical Sciences (2003)

Current Research and Scholarly Interests


The goals of the Sonnenburg Lab research program are to (i) elucidate the basic mechanisms that underlie dynamics within the gut microbiota and (ii) devise and implement strategies to prevent and treat disease in humans via the gut microbiota. We investigate the principles that govern gut microbial community function and interaction with the host using experimental systems ranging from gnotobiotic mice to humans. We pursue molecular mechanisms of host-microbial interaction using an array of technologies including gnotobiotic and conventional mouse models, quantitative imaging, molecular genetics and synthetic biology, and a metabolomics pipeline focused on defining microbiota-dependent metabolites. The synergy of these diverse techniques provides insight into the dynamics of a microbial ecosystem in response to cues ranging from nutrition to pathogen-induced inflammation. Studies of microbiomes diverse human cohorts, ranging from indigenous populations in Africa, Asia, and South America to dietary intervention trials in cohorts of US residents, have provided great insight into microbiome dynamics and fuel a pipeline of reverse translational studies.

Clinical Trials


  • Contrasting Ketogenic and Mediterranean Diets in Individuals With Type 2 Diabetes and Prediabetes: The Keto-Med Trial Not Recruiting

    The objective of this study is to compare two metabolically distinct diets, WFKD vs Med-Plus, in order to examine the potential benefits, and unintended consequences, of going beyond a focus on maximally avoiding added sugars and refined grains, to also avoiding legumes, fruits, and whole grains.

    Stanford is currently not accepting patients for this trial. For more information, please contact Jennifer Robinson, PhD, 650-736-8577.

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  • The RAMP Study - Rejuvenation of the Aging Microbiota With Prebiotics Not Recruiting

    An individual's immune and metabolic status is coupled to consumed carbohydrates. Complex carbohydrates that are not digested by human enzymes may influence host biology by impacting microbiota composition and function, or act in a yet-unknown microbiota-independent manner. Prebiotics offer a promising safe route to influence host health, possibly via the microbiota. However, it remains largely unknown to what extent immune function and metabolism can be modulated by prebiotics.

    Stanford is currently not accepting patients for this trial. For more information, please contact Jennifer Robinson, PhD, 650-736-8577.

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  • Twins Nutrition Study (TwiNS): Vegan vs. Omnivore Not Recruiting

    This study is designed to investigate the health impact of a vegan diet compared to a usual, omnivorous diet. The investigators plan to study these diets in twins, where one twin follows a vegan diet and the other twin follows an omnivorous diet, thus the investigators control for genetic differences that might impact the effect of the diet.

    Stanford is currently not accepting patients for this trial. For more information, please contact Tayler Hennings, MPH, 650-723-8114.

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2024-25 Courses


Stanford Advisees


Graduate and Fellowship Programs


All Publications


  • Ultra-deep sequencing of Hadza hunter-gatherers recovers vanishing gut microbes. Cell Carter, M. M., Olm, M. R., Merrill, B. D., Dahan, D., Tripathi, S., Spencer, S. P., Yu, F. B., Jain, S., Neff, N., Jha, A. R., Sonnenburg, E. D., Sonnenburg, J. L. 2023

    Abstract

    The gut microbiome modulates immune and metabolic health. Human microbiome data are biased toward industrialized populations, limiting our understanding of non-industrialized microbiomes. Here, we performed ultra-deep metagenomic sequencing on 351 fecal samples from the Hadza hunter-gatherers of Tanzania and comparative populations in Nepal and California. We recovered 91,662 genomes of bacteria, archaea, bacteriophages, and eukaryotes, 44% of which are absent from existing unified datasets. We identified 124 gut-resident species vanishing in industrialized populations and highlighted distinct aspects of the Hadza gut microbiome related to in situ replication rates, signatures of selection, and strain sharing. Industrialized gut microbes were found to be enriched in genes associated with oxidative stress, possibly a result of microbiome adaptation to inflammatory processes. This unparalleled view of the Hadza gut microbiome provides a valuable resource, expands our understanding of microbes capable of colonizing the human gut, and clarifies the extensive perturbation induced by the industrialized lifestyle.

    View details for DOI 10.1016/j.cell.2023.05.046

    View details for PubMedID 37348505

  • Robust variation in infant gut microbiome assembly across a spectrum of lifestyles. Science (New York, N.Y.) Olm, M. R., Dahan, D., Carter, M. M., Merrill, B. D., Yu, F. B., Jain, S., Meng, X., Tripathi, S., Wastyk, H., Neff, N., Holmes, S., Sonnenburg, E. D., Jha, A. R., Sonnenburg, J. L. 2022; 376 (6598): 1220-1223

    Abstract

    Infant microbiome assembly has been intensely studied in infants from industrialized nations, but little is known about this process in nonindustrialized populations. We deeply sequenced infant stool samples from the Hadza hunter-gatherers of Tanzania and analyzed them in a global meta-analysis. Infant microbiomes develop along lifestyle-associated trajectories, with more than 20% of genomes detected in the Hadza infant gut representing novel species. Industrialized infants-even those who are breastfed-have microbiomes characterized by a paucity of Bifidobacterium infantis and gene cassettes involved in human milk utilization. Strains within lifestyle-associated taxonomic groups are shared between mother-infant dyads, consistent with early life inheritance of lifestyle-shaped microbiomes. The population-specific differences in infant microbiome composition and function underscore the importance of studying microbiomes from people outside of wealthy, industrialized nations.

    View details for DOI 10.1126/science.abj2972

    View details for PubMedID 35679413

  • Impact of a 7-day homogeneous diet on interpersonal variation in human gut microbiomes and metabolomes. Cell host & microbe Guthrie, L., Spencer, S. P., Perelman, D., Van Treuren, W., Han, S., Yu, F. B., Sonnenburg, E. D., Fischbach, M. A., Meyer, T. W., Sonnenburg, J. L. 2022

    Abstract

    Gut microbiota metabolism of dietary compounds generates a vast array of microbiome-dependent metabolites (MDMs), which are highly variable between individuals. The uremic MDMs (uMDMs) phenylacetylglutamine (PAG), p-cresol sulfate (PCS), and indoxyl sulfate (IS) accumulate during renal failure and are associated with poor outcomes. Targeted dietary interventions may reduce toxic MDM generation; however, it is unclear if inter-individual differences in diet or gut microbiome dominantly contribute to MDM variance. Here, we use a 7-day homogeneous average American diet to standardize dietary precursor availability in 21 healthy individuals. During dietary homogeneity, the coefficient of variation in PAG, PCS, and IS (primary outcome) did not decrease, nor did inter-individual variation in most identified metabolites; other microbiome metrics showed no or modest responses to the intervention. Host identity and age are dominant contributors to variability in MDMs. These results highlight the potential need to pair dietary modification with microbial therapies to control MDM profiles.

    View details for DOI 10.1016/j.chom.2022.05.003

    View details for PubMedID 35643079

  • C. difficile exploits a host metabolite produced during toxin-mediated disease. Nature Pruss, K. M., Sonnenburg, J. L. 2021

    Abstract

    Several enteric pathogens can gain specific metabolic advantages over other members of the microbiota by inducing host pathology and inflammation. The pathogen Clostridium difficile is responsible for a toxin-mediated colitis that causes 450,000 infections and 15,000 deaths in the United States each year1; however, the molecular mechanisms by which C. difficile benefits from this pathology remain unclear. To understand how the metabolism of C. difficile adapts to the inflammatory conditions that its toxins induce, here we use RNA sequencing to define, in a mouse model, the metabolic states of wild-type C. difficile and of an isogenic mutant that lacks toxins. By combining bacterial and mouse genetics, we demonstrate that C. difficile uses sorbitol derived from both diet and host. Host-derived sorbitol is produced by the enzyme aldose reductase, which is expressed by diverse immune cells and is upregulated during inflammation-including during toxin-mediated disease induced by C. difficile. This work highlights a mechanism by which C. difficile can use a host-derived nutrient that is generated during toxin-induced disease by an enzyme that has not previously been associated with infection.

    View details for DOI 10.1038/s41586-021-03502-6

    View details for PubMedID 33911281

  • Gut-microbiota-targeted diets modulate human immune status. Cell Wastyk, H. C., Fragiadakis, G. K., Perelman, D., Dahan, D., Merrill, B. D., Yu, F. B., Topf, M., Gonzalez, C. G., Van Treuren, W., Han, S., Robinson, J. L., Elias, J. E., Sonnenburg, E. D., Gardner, C. D., Sonnenburg, J. L. 2021

    Abstract

    Diet modulates the gut microbiome, which in turn can impact the immune system. Here, we determined how two microbiota-targeted dietary interventions, plant-based fiber and fermented foods, influence the human microbiome and immune system in healthy adults. Using a 17-week randomized, prospective study (n = 18/arm) combined with -omics measurements of microbiome and host, including extensive immune profiling, we found diet-specific effects. The high-fiber diet increased microbiome-encoded glycan-degrading carbohydrate active enzymes (CAZymes) despite stable microbial community diversity. Although cytokine response score (primary outcome) was unchanged, three distinct immunological trajectories in high-fiber consumers corresponded to baseline microbiota diversity. Alternatively, the high-fermented-food diet steadily increased microbiota diversity and decreased inflammatory markers. The data highlight how coupling dietary interventions to deep and longitudinal immune and microbiome profiling can provide individualized and population-wide insight. Fermented foods may be valuable in countering the decreased microbiome diversity and increased inflammation pervasive in industrialized society.

    View details for DOI 10.1016/j.cell.2021.06.019

    View details for PubMedID 34256014

  • A metabolomics pipeline for the mechanistic interrogation of the gut microbiome. Nature Han, S., Van Treuren, W., Fischer, C. R., Merrill, B. D., DeFelice, B. C., Sanchez, J. M., Higginbottom, S. K., Guthrie, L., Fall, L. A., Dodd, D., Fischbach, M. A., Sonnenburg, J. L. 2021; 595 (7867): 415-420

    Abstract

    Gut microorganisms modulate host phenotypes and are associated with numerous health effects in humans, ranging from host responses to cancer immunotherapy to metabolic disease and obesity. However, difficulty in accurate and high-throughput functional analysis of human gut microorganisms has hindered efforts to define mechanistic connections between individual microbial strains and host phenotypes. One key way in which the gut microbiome influences host physiology is through the production of small molecules1-3, yet progress in elucidating this chemical interplay has been hindered by limited tools calibrated to detect the products of anaerobic biochemistry in the gut. Here we construct a microbiome-focused, integrated mass-spectrometry pipeline to accelerate the identification of microbiota-dependent metabolites in diverse sample types. We report the metabolic profiles of 178 gut microorganism strains using our library of 833 metabolites. Using this metabolomics resource, we establish deviations in the relationships between phylogeny and metabolism, use machine learning to discover a previously undescribed type of metabolism in Bacteroides, and reveal candidate biochemical pathways using comparative genomics. Microbiota-dependent metabolites can be detected in diverse biological fluids from gnotobiotic and conventionally colonized mice and traced back to the corresponding metabolomic profiles of cultured bacteria. Collectively, our microbiome-focused metabolomics pipeline and interactive metabolomics profile explorer are a powerful tool for characterizing microorganisms and interactions between microorganisms and their host.

    View details for DOI 10.1038/s41586-021-03707-9

    View details for PubMedID 34262212

  • Vulnerability of the industrialized microbiota. Science (New York, N.Y.) Sonnenburg, J. L., Sonnenburg, E. D. 2019; 366 (6464)

    Abstract

    The human body is an ecosystem that is home to a complex array of microbes known as the microbiome or microbiota. This ecosystem plays an important role in human health, but as a result of recent lifestyle changes occurring around the planet, whole populations are seeing a major shift in their gut microbiota. Measures meant to kill or limit exposure to pathogenic microbes, such as antibiotics and sanitation, combined with other factors such as processed food, have had unintended consequences for the human microbial ecosystem, including changes that may be difficult to reverse. Microbiota alteration and the accompanying loss of certain functional attributes might result in the microbial communities of people living in industrialized societies being suboptimal for human health. As macroecologists, conservationists, and climate scientists race to document, understand, predict, and delay global changes in our wider environment, microbiota scientists may benefit by using analogous approaches to study and protect our intimate microbial ecosystems.

    View details for DOI 10.1126/science.aaw9255

    View details for PubMedID 31649168

  • Transient Osmotic Perturbation Causes Long-Term Alteration to the Gut Microbiota. Cell Tropini, C., Moss, E. L., Merrill, B. D., Ng, K. M., Higginbottom, S. K., Casavant, E. P., Gonzalez, C. G., Fremin, B., Bouley, D. M., Elias, J. E., Bhatt, A. S., Huang, K. C., Sonnenburg, J. L. 2018; 173 (7): 1742

    Abstract

    Osmotic diarrhea is a prevalent condition in humans caused by food intolerance, malabsorption, and widespread laxative use. Here, we assess the resilience of the gut ecosystem to osmotic perturbation at multiple length and timescales using mice as model hosts. Osmotic stress caused reproducible extinction of highly abundant taxa and expansion of less prevalent members in human and mouse microbiotas. Quantitative imaging revealed decimation of the mucus barrier during osmotic perturbation, followed by recovery. The immune system exhibited temporary changes in cytokine levels and a lasting IgG response against commensal bacteria. Increased osmolality prevented growth of commensal strains invitro, revealing one mechanism contributing to extinction. Environmental availability of microbiota members mitigated extinction events, demonstrating how species reintroduction can affect community resilience. Our findings (1) demonstrate that even mild osmotic diarrhea can cause lasting changes to the microbiota and host and (2) lay the foundation for interventions that increase system-wide resilience.

    View details for PubMedID 29906449

  • An exclusive metabolic niche enables strain engraftment in the gut microbiota NATURE Shepherd, E., DeLoache, W. C., Pruss, K. M., Whitaker, W. R., Sonnenburg, J. L. 2018; 557 (7705): 434-+

    Abstract

    The dense microbial ecosystem in the gut is intimately connected to numerous facets of human biology, and manipulation of the gut microbiota has broad implications for human health. In the absence of profound perturbation, the bacterial strains that reside within an individual are mostly stable over time 1 . By contrast, the fate of exogenous commensal and probiotic strains applied to an established microbiota is variable, generally unpredictable and greatly influenced by the background microbiota2,3. Therefore, analysis of the factors that govern strain engraftment and abundance is of critical importance to the emerging field of microbiome reprogramming. Here we generate an exclusive metabolic niche in mice via administration of a marine polysaccharide, porphyran, and an exogenous Bacteroides strain harbouring a rare gene cluster for porphyran utilization. Privileged nutrient access enables reliable engraftment of the exogenous strain at predictable abundances in mice harbouring diverse communities of gut microbes. This targeted dietary support is sufficient to overcome priority exclusion by an isogenic strain 4 , and enables strain replacement. We demonstrate transfer of the 60-kb porphyran utilization locus into a naive strain of Bacteroides, and show finely tuned control of strain abundance in the mouse gut across multiple orders of magnitude by varying porphyran dosage. Finally, we show that this system enables the introduction of a new strain into the colonic crypt ecosystem. These data highlight the influence of nutrient availability in shaping microbiota membership, expand the ability to perform a broad spectrum of investigations in the context of a complex microbiota, and have implications for cell-based therapeutic strategies in the gut.

    View details for PubMedID 29743671

  • Gut microbiome transition across a lifestyle gradient in Himalaya. PLoS biology Jha, A. R., Davenport, E. R., Gautam, Y. n., Bhandari, D. n., Tandukar, S. n., Ng, K. M., Fragiadakis, G. K., Holmes, S. n., Gautam, G. P., Leach, J. n., Sherchand, J. B., Bustamante, C. D., Sonnenburg, J. L. 2018; 16 (11): e2005396

    Abstract

    The composition of the gut microbiome in industrialized populations differs from those living traditional lifestyles. However, it has been difficult to separate the contributions of human genetic and geographic factors from lifestyle. Whether shifts away from the foraging lifestyle that characterize much of humanity's past influence the gut microbiome, and to what degree, remains unclear. Here, we characterize the stool bacterial composition of four Himalayan populations to investigate how the gut community changes in response to shifts in traditional human lifestyles. These groups led seminomadic hunting-gathering lifestyles until transitioning to varying levels of agricultural dependence upon farming. The Tharu began farming 250-300 years ago, the Raute and Raji transitioned 30-40 years ago, and the Chepang retain many aspects of a foraging lifestyle. We assess the contributions of dietary and environmental factors on their gut-associated microbes and find that differences in the lifestyles of Himalayan foragers and farmers are strongly correlated with microbial community variation. Furthermore, the gut microbiomes of all four traditional Himalayan populations are distinct from that of the Americans, indicating that industrialization may further exacerbate differences in the gut community. The Chepang foragers harbor an elevated abundance of taxa associated with foragers around the world. Conversely, the gut microbiomes of the populations that have transitioned to farming are more similar to those of Americans, with agricultural dependence and several associated lifestyle and environmental factors correlating with the extent of microbiome divergence from the foraging population. The gut microbiomes of Raute and Raji reveal an intermediate state between the Chepang and Tharu, indicating that divergence from a stereotypical foraging microbiome can occur within a single generation. Our results also show that environmental factors such as drinking water source and solid cooking fuel are significantly associated with the gut microbiome. Despite the pronounced differences in gut bacterial composition across populations, we found little differences in alpha diversity across lifestyles. These findings in genetically similar populations living in the same geographical region establish the key role of lifestyle in determining human gut microbiome composition and point to the next challenging steps of determining how large-scale gut microbiome reconfiguration impacts human biology.

    View details for PubMedID 30439937

  • Tunable Expression Tools Enable Single-Cell Strain Distinction in the Gut Microbiome CELL Whitaker, W. R., Shepherd, E. S., Sonnenburg, J. L. 2017; 169 (3): 538-?

    Abstract

    Applying synthetic biology to engineer gut-resident microbes provides new avenues to investigate microbe-host interactions, perform diagnostics, and deliver therapeutics. Here, we describe a platform for engineering Bacteroides, the most abundant genus in the Western microbiota, which includes a process for high-throughput strain modification. We have identified a novel phage promoter and translational tuning strategy and achieved an unprecedented level of expression that enables imaging of fluorescent-protein-expressing Bacteroides stably colonizing the mouse gut. A detailed characterization of the phage promoter has provided a set of constitutive promoters that span over four logs of strength without detectable fitness burden within the gut over 14 days. These promoters function predictably over a 1,000,000-fold expression range in phylogenetically diverse Bacteroides species. With these promoters, unique fluorescent signatures were encoded to allow differentiation of six species within the gut. Fluorescent protein-based differentiation of isogenic strains revealed that priority of gut colonization determines colonic crypt occupancy.

    View details for DOI 10.1016/j.cell.2017.03.041

    View details for Web of Science ID 000399560600016

    View details for PubMedID 28431251

  • A gut bacterial pathway metabolizes aromatic amino acids into nine circulating metabolites. Nature Dodd, D. n., Spitzer, M. H., Van Treuren, W. n., Merrill, B. D., Hryckowian, A. J., Higginbottom, S. K., Le, A. n., Cowan, T. M., Nolan, G. P., Fischbach, M. A., Sonnenburg, J. L. 2017; 551 (7682): 648–52

    Abstract

    The human gut microbiota produces dozens of metabolites that accumulate in the bloodstream, where they can have systemic effects on the host. Although these small molecules commonly reach concentrations similar to those achieved by pharmaceutical agents, remarkably little is known about the microbial metabolic pathways that produce them. Here we use a combination of genetics and metabolic profiling to characterize a pathway from the gut symbiont Clostridium sporogenes that generates aromatic amino acid metabolites. Our results reveal that this pathway produces twelve compounds, nine of which are known to accumulate in host serum. All three aromatic amino acids (tryptophan, phenylalanine and tyrosine) serve as substrates for the pathway, and it involves branching and alternative reductases for specific intermediates. By genetically manipulating C. sporogenes, we modulate serum levels of these metabolites in gnotobiotic mice, and show that in turn this affects intestinal permeability and systemic immunity. This work has the potential to provide the basis of a systematic effort to engineer the molecular output of the gut bacterial community.

    View details for PubMedID 29168502

  • Seasonal cycling in the gut microbiome of the Hadza hunter-gatherers of Tanzania. Science (New York, N.Y.) Smits, S. A., Leach, J. n., Sonnenburg, E. D., Gonzalez, C. G., Lichtman, J. S., Reid, G. n., Knight, R. n., Manjurano, A. n., Changalucha, J. n., Elias, J. E., Dominguez-Bello, M. G., Sonnenburg, J. L. 2017; 357 (6353): 802–6

    Abstract

    Although humans have cospeciated with their gut-resident microbes, it is difficult to infer features of our ancestral microbiome. Here, we examine the microbiome profile of 350 stool samples collected longitudinally for more than a year from the Hadza hunter-gatherers of Tanzania. The data reveal annual cyclic reconfiguration of the microbiome, in which some taxa become undetectable only to reappear in a subsequent season. Comparison of the Hadza data set with data collected from 18 populations in 16 countries with varying lifestyles reveals that gut community membership corresponds to modernization: Notably, the taxa within the Hadza that are the most seasonally volatile similarly differentiate industrialized and traditional populations. These data indicate that some dynamic lineages of microbes have decreased in prevalence and abundance in modernized populations.

    View details for PubMedID 28839072

  • Diet-microbiota interactions as moderators of human metabolism NATURE Sonnenburg, J. L., Backhed, F. 2016; 535 (7610): 56-64

    Abstract

    It is widely accepted that obesity and associated metabolic diseases, including type 2 diabetes, are intimately linked to diet. However, the gut microbiota has also become a focus for research at the intersection of diet and metabolic health. Mechanisms that link the gut microbiota with obesity are coming to light through a powerful combination of translation-focused animal models and studies in humans. A body of knowledge is accumulating that points to the gut microbiota as a mediator of dietary impact on the host metabolic status. Efforts are focusing on the establishment of causal relationships in people and the prospect of therapeutic interventions such as personalized nutrition.

    View details for DOI 10.1038/nature18846

    View details for Web of Science ID 000379015600028

    View details for PubMedID 27383980

  • Diet-induced extinctions in the gut microbiota compound over generations. Nature Sonnenburg, E. D., Smits, S. A., Tikhonov, M., Higginbottom, S. K., Wingreen, N. S., Sonnenburg, J. L. 2016; 529 (7585): 212-215

    Abstract

    The gut is home to trillions of microorganisms that have fundamental roles in many aspects of human biology, including immune function and metabolism. The reduced diversity of the gut microbiota in Western populations compared to that in populations living traditional lifestyles presents the question of which factors have driven microbiota change during modernization. Microbiota-accessible carbohydrates (MACs) found in dietary fibre have a crucial involvement in shaping this microbial ecosystem, and are notably reduced in the Western diet (high in fat and simple carbohydrates, low in fibre) compared with a more traditional diet. Here we show that changes in the microbiota of mice consuming a low-MAC diet and harbouring a human microbiota are largely reversible within a single generation. However, over several generations, a low-MAC diet results in a progressive loss of diversity, which is not recoverable after the reintroduction of dietary MACs. To restore the microbiota to its original state requires the administration of missing taxa in combination with dietary MAC consumption. Our data illustrate that taxa driven to low abundance when dietary MACs are scarce are inefficiently transferred to the next generation, and are at increased risk of becoming extinct within an isolated population. As more diseases are linked to the Western microbiota and the microbiota is targeted therapeutically, microbiota reprogramming may need to involve strategies that incorporate dietary MACs as well as taxa not currently present in the Western gut.

    View details for DOI 10.1038/nature16504

    View details for PubMedID 26762459

  • Quantitative Imaging of Gut Microbiota Spatial Organization CELL HOST & MICROBE Earle, K. A., Billings, G., Sigal, M., Lichtman, J. S., Hansson, G. C., Elias, J. E., Amieva, M. R., Huang, K. C., Sonnenburg, J. L. 2015; 18 (4): 478-488

    Abstract

    Genomic technologies have significantly advanced our understanding of the composition and diversity of host-associated microbial populations. However, their spatial organization and functional interactions relative to the host have been more challenging to study. Here we present a pipeline for the assessment of intestinal microbiota localization within immunofluorescence images of fixed gut cross-sections that includes a flexible software package, BacSpace, for high-throughput quantification of microbial organization. Applying this pipeline to gnotobiotic and human microbiota-colonized mice, we demonstrate that elimination of microbiota-accessible carbohydrates (MACs) from the diet results in thinner mucus in the distal colon, increased proximity of microbes to the epithelium, and heightened expression of the inflammatory marker REG3β. Measurements of microbe-microbe proximity reveal that a MAC-deficient diet alters monophyletic spatial clustering. Furthermore, we quantify the invasion of Helicobacter pylori into the glands of the mouse stomach relative to host mitotic progenitor cells, illustrating the generalizability of this approach.

    View details for DOI 10.1016/j.chom.2015.09.002

    View details for Web of Science ID 000365111600016

    View details for PubMedID 26439864

  • Starving our Microbial Self: The Deleterious Consequences of a Diet Deficient in Microbiota-Accessible Carbohydrates CELL METABOLISM Sonnenburg, E. D., Sonnenburg, J. L. 2014; 20 (5): 779-786
  • Microbiota-liberated host sugars facilitate post-antibiotic expansion of enteric pathogens NATURE Ng, K. M., Ferreyra, J. A., Higginbottom, S. K., Lynch, J. B., Kashyap, P. C., Gopinath, S., Naidu, N., Choudhury, B., Weimer, B. C., Monack, D. M., Sonnenburg, J. L. 2013; 502 (7469): 96-?

    Abstract

    The human intestine, colonized by a dense community of resident microbes, is a frequent target of bacterial pathogens. Undisturbed, this intestinal microbiota provides protection from bacterial infections. Conversely, disruption of the microbiota with oral antibiotics often precedes the emergence of several enteric pathogens. How pathogens capitalize upon the failure of microbiota-afforded protection is largely unknown. Here we show that two antibiotic-associated pathogens, Salmonella enterica serovar Typhimurium (S. typhimurium) and Clostridium difficile, use a common strategy of catabolizing microbiota-liberated mucosal carbohydrates during their expansion within the gut. S. typhimurium accesses fucose and sialic acid within the lumen of the gut in a microbiota-dependent manner, and genetic ablation of the respective catabolic pathways reduces its competitiveness in vivo. Similarly, C. difficile expansion is aided by microbiota-induced elevation of sialic acid levels in vivo. Colonization of gnotobiotic mice with a sialidase-deficient mutant of Bacteroides thetaiotaomicron, a model gut symbiont, reduces free sialic acid levels resulting in C. difficile downregulating its sialic acid catabolic pathway and exhibiting impaired expansion. These effects are reversed by exogenous dietary administration of free sialic acid. Furthermore, antibiotic treatment of conventional mice induces a spike in free sialic acid and mutants of both Salmonella and C. difficile that are unable to catabolize sialic acid exhibit impaired expansion. These data show that antibiotic-induced disruption of the resident microbiota and subsequent alteration in mucosal carbohydrate availability are exploited by these two distantly related enteric pathogens in a similar manner. This insight suggests new therapeutic approaches for preventing diseases caused by antibiotic-associated pathogens.

    View details for DOI 10.1038/nature12503

    View details for Web of Science ID 000325106000038

    View details for PubMedID 23995682

  • Specificity of Polysaccharide Use in Intestinal Bacteroides Species Determines Diet-Induced Microbiota Alterations CELL Sonnenburg, E. D., Zheng, H., Joglekar, P., Higginbottom, S. K., Firbank, S. J., Bolam, D. N., Sonnenburg, J. L. 2010; 141 (7): 1241-U256

    Abstract

    The intestinal microbiota impacts many facets of human health and is associated with human diseases. Diet impacts microbiota composition, yet mechanisms that link dietary changes to microbiota alterations remain ill-defined. Here we elucidate the basis of Bacteroides proliferation in response to fructans, a class of fructose-based dietary polysaccharides. Structural and genetic analysis disclosed a fructose-binding, hybrid two-component signaling sensor that controls the fructan utilization locus in Bacteroides thetaiotaomicron. Gene content of this locus differs among Bacteroides species and dictates the specificity and breadth of utilizable fructans. BT1760, an extracellular beta2-6 endo-fructanase, distinguishes B. thetaiotaomicron genetically and functionally, and enables the use of the beta2-6-linked fructan levan. The genetic and functional differences between Bacteroides species are predictive of in vivo competitiveness in the presence of dietary fructans. Gene sequences that distinguish species' metabolic capacity serve as potential biomarkers in microbiomic datasets to enable rational manipulation of the microbiota via diet.

    View details for DOI 10.1016/j.cell.2010.05.005

    View details for Web of Science ID 000279148100020

    View details for PubMedID 20603004

    View details for PubMedCentralID PMC2900928

  • Unveiling the epigenetic impact of vegan vs. omnivorous diets on aging: insights from the Twins Nutrition Study (TwiNS). BMC medicine Dwaraka, V. B., Aronica, L., Carreras-Gallo, N., Robinson, J. L., Hennings, T., Carter, M. M., Corley, M. J., Lin, A., Turner, L., Smith, R., Mendez, T. L., Went, H., Ebel, E. R., Sonnenburg, E. D., Sonnenburg, J. L., Gardner, C. D. 2024; 22 (1): 301

    Abstract

    Geroscience focuses on interventions to mitigate molecular changes associated with aging. Lifestyle modifications, medications, and social factors influence the aging process, yet the complex molecular mechanisms require an in-depth exploration of the epigenetic landscape. The specific epigenetic clock and predictor effects of a vegan diet, compared to an omnivorous diet, remain underexplored despite potential impacts on aging-related outcomes.This study examined the impact of an entirely plant-based or healthy omnivorous diet over 8 weeks on blood DNA methylation in paired twins. Various measures of epigenetic age acceleration (PC GrimAge, PC PhenoAge, DunedinPACE) were assessed, along with system-specific effects (Inflammation, Heart, Hormone, Liver, and Metabolic). Methylation surrogates of clinical, metabolite, and protein markers were analyzed to observe diet-specific shifts.Distinct responses were observed, with the vegan cohort exhibiting significant decreases in overall epigenetic age acceleration, aligning with anti-aging effects of plant-based diets. Diet-specific shifts were noted in the analysis of methylation surrogates, demonstrating the influence of diet on complex trait prediction through DNA methylation markers. An epigenome-wide analysis revealed differentially methylated loci specific to each diet, providing insights into the affected pathways.This study suggests that a short-term vegan diet is associated with epigenetic age benefits and reduced calorie intake. The use of epigenetic biomarker proxies (EBPs) highlights their potential for assessing dietary impacts and facilitating personalized nutrition strategies for healthy aging. Future research should explore the long-term effects of vegan diets on epigenetic health and overall well-being, considering the importance of proper nutrient supplementation.Clinicaltrials.gov identifier: NCT05297825.

    View details for DOI 10.1186/s12916-024-03513-w

    View details for PubMedID 39069614

    View details for PubMedCentralID 4306469

  • High-throughput identification of gut microbiome-dependent metabolites. Nature protocols Han, S., Guiberson, E. R., Li, Y., Sonnenburg, J. L. 2024

    Abstract

    A significant hurdle that has limited progress in microbiome science has been identifying and studying the diverse set of metabolites produced by gut microbes. Gut microbial metabolism produces thousands of difficult-to-identify metabolites, which present a challenge to study their roles in host biology. In recent years, mass spectrometry-based metabolomics has become one of the core technologies for identifying small metabolites. However, metabolomics expertise, ranging from sample preparation to instrument use and data analysis, is often lacking in academic labs. Most targeted metabolomics methods provide high levels of sensitivity and quantification, while they are limited to a panel of predefined molecules that may not be informative to microbiome-focused studies. Here we have developed a gut microbe-focused and wide-spectrum metabolomic protocol using liquid chromatography-mass spectrometry and bioinformatic analysis. This protocol enables users to carry out experiments from sample collection to data analysis, only requiring access to a liquid chromatography-mass spectrometry instrument, which is often available at local core facilities. By applying this protocol to samples containing human gut microbial metabolites, spanning from culture supernatant to human biospecimens, our approach enables high-confidence identification of >800 metabolites that can serve as candidate mediators of microbe-host interactions. We expect this protocol will lower the barrier to tracking gut bacterial metabolism in vitro and in mammalian hosts, propelling hypothesis-driven mechanistic studies and accelerating our understanding of the gut microbiome at the chemical level.

    View details for DOI 10.1038/s41596-024-00980-6

    View details for PubMedID 38740909

    View details for PubMedCentralID 5541232

  • Our extended microbiome: The human-relevant metabolites and biology of fermented foods. Cell metabolism Caffrey, E. B., Sonnenburg, J. L., Devkota, S. 2024; 36 (4): 684-701

    Abstract

    One of the key modes of microbial metabolism occurring in the gut microbiome is fermentation. This energy-yielding process transforms common macromolecules like polysaccharides and amino acids into a wide variety of chemicals, many of which are relevant to microbe-microbe and microbe-host interactions. Analogous transformations occur during the production of fermented foods, resulting in an abundance of bioactive metabolites. In foods, the products of fermentation can influence food safety and preservation, nutrient availability, and palatability and, once consumed, may impact immune and metabolic status, disease expression, and severity. Human signaling pathways perceive and respond to many of the currently known fermented food metabolites, though expansive chemical novelty remains to be defined. Here we discuss several aspects of fermented food-associated microbes and metabolites, including a condensed history, current understanding of their interactions with hosts and host-resident microbes, connections with commercial probiotics, and opportunities for future research on human health and disease and food sustainability.

    View details for DOI 10.1016/j.cmet.2024.03.007

    View details for PubMedID 38569469

  • Bacteroides fragilis toxin expression enables lamina propria niche acquisition in the developing mouse gut. Nature microbiology Hill, C. A., Casterline, B. W., Valguarnera, E., Hecht, A. L., Shepherd, E. S., Sonnenburg, J. L., Bubeck Wardenburg, J. 2024

    Abstract

    Bacterial toxins are well-studied virulence factors; however, recent studies have revealed their importance in bacterial niche adaptation. Enterotoxigenic Bacteroides fragilis (ETBF) expresses B. fragilis toxin (BFT) that we hypothesized may contribute to both colonic epithelial injury and niche acquisition. We developed a vertical transmission model for ETBF in mice that showed that BFT enabled ETBF to access a lamina propria (LP) niche during colonic microbiome development that was inaccessible to non-toxigenic B. fragilis. LP entry by ETBF required BFT metalloprotease activity, and showed temporal restriction to the pre-weaning period, dependent on goblet-cell-associated passages. In situ single-cell analysis showed bft expression at the apical epithelial surface and within the LP. BFT expression increased goblet cell number and goblet-cell-associated passage formation. These findings define a paradigm by which bacterial toxin expression specifies developmental niche acquisition, suggesting that a selective advantage conferred by a toxin may impact long-term host health.

    View details for DOI 10.1038/s41564-023-01559-9

    View details for PubMedID 38168616

    View details for PubMedCentralID 5156933

  • Randomly barcoded transposon mutant libraries for gut commensals I: Strategies for efficient library construction. Cell reports Tripathi, S., Voogdt, C. G., Bassler, S. O., Anderson, M., Huang, P. H., Sakenova, N., Capraz, T., Jain, S., Koumoutsi, A., Bravo, A. M., Trotter, V., Zimmerman, M., Sonnenburg, J. L., Buie, C., Typas, A., Deutschbauer, A. M., Shiver, A. L., Huang, K. C. 2023; 43 (1): 113517

    Abstract

    Randomly barcoded transposon mutant libraries are powerful tools for studying gene function and organization, assessing gene essentiality and pathways, discovering potential therapeutic targets, and understanding the physiology of gut bacteria and their interactions with the host. However, construction of high-quality libraries with uniform representation can be challenging. In this review, we survey various strategies for barcoded library construction, including transposition systems, methods of transposon delivery, optimal library size, and transconjugant selection schemes. We discuss the advantages and limitations of each approach, as well as factors to consider when selecting a strategy. In addition, we highlight experimental and computational advances in arraying condensed libraries from mutant pools. We focus on examples of successful library construction in gut bacteria and their application to gene function studies and drug discovery. Given the need for understanding gene function and organization in gut bacteria, we provide a comprehensive guide for researchers to construct randomly barcoded transposon mutant libraries.

    View details for DOI 10.1016/j.celrep.2023.113517

    View details for PubMedID 38142397

  • Randomly barcoded transposon mutant libraries for gut commensals II: Applying libraries for functional genetics. Cell reports Voogdt, C. G., Tripathi, S., Bassler, S. O., McKeithen-Mead, S. A., Guiberson, E. R., Koumoutsi, A., Bravo, A. M., Buie, C., Zimmermann, M., Sonnenburg, J. L., Typas, A., Deutschbauer, A. M., Shiver, A. L., Huang, K. C. 2023; 43 (1): 113519

    Abstract

    The critical role of the intestinal microbiota in human health and disease is well recognized. Nevertheless, there are still large gaps in our understanding of the functions and mechanisms encoded in the genomes of most members of the gut microbiota. Genome-scale libraries of transposon mutants are a powerful tool to help us address this gap. Recent advances in barcoded transposon mutagenesis have dramatically lowered the cost of mutant fitness determination in hundreds of in vitro and in vivo experimental conditions. In an accompanying review, we discuss recent advances and caveats for the construction of pooled and arrayed barcoded transposon mutant libraries in human gut commensals. In this review, we discuss how these libraries can be used across a wide range of applications, the technical aspects involved, and expectations for such screens.

    View details for DOI 10.1016/j.celrep.2023.113519

    View details for PubMedID 38142398

  • Metabolic diversity in commensal protists regulates intestinal immunity and trans-kingdom competition. Cell Gerrick, E. R., Zlitni, S., West, P. T., Carter, M. M., Mechler, C. M., Olm, M. R., Caffrey, E. B., Li, J. A., Higginbottom, S. K., Severyn, C. J., Kracke, F., Spormann, A. M., Sonnenburg, J. L., Bhatt, A. S., Howitt, M. R. 2023

    Abstract

    The microbiota influences intestinal health and physiology, yet the contributions of commensal protists to the gut environment have been largely overlooked. Here, we discover human- and rodent-associated parabasalid protists, revealing substantial diversity and prevalence in nonindustrialized human populations. Genomic and metabolomic analyses of murine parabasalids from the genus Tritrichomonas revealed species-level differences in excretion of the metabolite succinate, which results in distinct small intestinal immune responses. Metabolic differences between Tritrichomonas species also determine their ecological niche within the microbiota. By manipulating dietary fibers and developing in vitro protist culture, we show that different Tritrichomonas species prefer dietary polysaccharides or mucus glycans. These polysaccharide preferences drive trans-kingdom competition with specific commensal bacteria, which affects intestinal immunity in a diet-dependent manner. Our findings reveal unappreciated diversity in commensal parabasalids, elucidate differences in commensal protist metabolism, and suggest how dietary interventions could regulate their impact on gut health.

    View details for DOI 10.1016/j.cell.2023.11.018

    View details for PubMedID 38096822

  • Hadza Prevotella require diet-derived microbiota-accessible carbohydrates to persist in mice. Cell reports Gellman, R. H., Olm, M. R., Terrapon, N., Enam, F., Higginbottom, S. K., Sonnenburg, J. L., Sonnenburg, E. D. 2023; 42 (11)

    Abstract

    Industrialization has transformed the gut microbiota, reducing the prevalence of Prevotella relative to Bacteroides. Here, we isolate Bacteroides and Prevotella strains from the microbiota of Hadza hunter-gatherers in Tanzania, a population with high levels of Prevotella. We demonstrate that plant-derived microbiota-accessible carbohydrates (MACs) are required for persistence of Prevotella copri but not Bacteroides thetaiotaomicron in vivo. Differences in carbohydrate metabolism gene content, expression, and in vitro growth reveal that Hadza Prevotella strains specialize in degrading plant carbohydrates, while Hadza Bacteroides isolates use both plant and host-derived carbohydrates, a difference mirrored in Bacteroides from non-Hadza populations. When competing directly, P. copri requires plant-derived MACs to maintain colonization in the presence of B. thetaiotaomicron, as a no-MAC diet eliminates P. copri colonization. Prevotella's reliance on plant-derived MACs and Bacteroides' ability to use host mucus carbohydrates could explain the reduced prevalence of Prevotella in populations consuming a low-MAC, industrialized diet.

    View details for DOI 10.1016/j.celrep.2023.113233

    View details for PubMedID 38510311

    View details for PubMedCentralID PMC10954246

  • Hadza<i> Prevotella</i> require diet-derived microbiota-accessible carbohydrates to persist in mice CELL REPORTS Gellman, R. H., Olm, M. R., Terrapon, N., Enam, F., Higginbottom, S. K., Sonnenburg, J. L., Sonnenburg, E. D. 2023; 42 (11)
  • Metagenomic Immunoglobulin Sequencing (MIG-Seq) Exposes Patterns of IgA Antibody Binding in the Healthy Human Gut Microbiome. bioRxiv : the preprint server for biology Olm, M. R., Spencer, S. P., Silva, E. L., Sonnenburg, J. L. 2023

    Abstract

    IgA, the most highly produced human antibody, is continually secreted into the gut to shape the intestinal microbiota. Methodological limitations have critically hindered defining which microbial strains are targeted by IgA and why. Here, we develop a new technique, Metagenomic Immunoglobulin Sequencing (MIG-Seq), and use it to determine IgA coating levels for thousands of gut microbiome strains in healthy humans. We find that microbes associated with both health and disease have higher levels of coating, and that microbial genes are highly predictive of IgA binding levels, with mucus degradation genes especially correlated with high binding. We find a significant reduction in replication rates among microbes bound by IgA, and demonstrate that IgA binding is more correlated with host immune status than traditional microbial abundance measures. This study introduces a powerful technique for assessing strain-level IgA binding in human stool, paving the way for deeper understanding of IgA-based host microbe interactions.

    View details for DOI 10.1101/2023.11.21.568153

    View details for PubMedID 38045399

  • Cardiometabolic Effects of Omnivorous vs Vegan Diets in Identical Twins: A Randomized Clinical Trial. JAMA network open Landry, M. J., Ward, C. P., Cunanan, K. M., Durand, L. R., Perelman, D., Robinson, J. L., Hennings, T., Koh, L., Dant, C., Zeitlin, A., Ebel, E. R., Sonnenburg, E. D., Sonnenburg, J. L., Gardner, C. D. 2023; 6 (11): e2344457

    Abstract

    Increasing evidence suggests that, compared with an omnivorous diet, a vegan diet confers potential cardiovascular benefits from improved diet quality (ie, higher consumption of vegetables, legumes, fruits, whole grains, nuts, and seeds).To compare the effects of a healthy vegan vs healthy omnivorous diet on cardiometabolic measures during an 8-week intervention.This single-center, population-based randomized clinical trial of 22 pairs of twins (N = 44) randomized participants to a vegan or omnivorous diet (1 twin per diet). Participant enrollment began March 28, 2022, and continued through May 5, 2022. The date of final follow-up data collection was July 20, 2022. This 8-week, open-label, parallel, dietary randomized clinical trial compared the health impact of a vegan diet vs an omnivorous diet in identical twins. Primary analysis included all available data.Twin pairs were randomized to follow a healthy vegan diet or a healthy omnivorous diet for 8 weeks. Diet-specific meals were provided via a meal delivery service from baseline through week 4, and from weeks 5 to 8 participants prepared their own diet-appropriate meals and snacks.The primary outcome was difference in low-density lipoprotein cholesterol concentration from baseline to end point (week 8). Secondary outcome measures were changes in cardiometabolic factors (plasma lipids, glucose, and insulin levels and serum trimethylamine N-oxide level), plasma vitamin B12 level, and body weight. Exploratory measures were adherence to study diets, ease or difficulty in following the diets, participant energy levels, and sense of well-being.A total of 22 pairs (N = 44) of twins (34 [77.3%] female; mean [SD] age, 39.6 [12.7] years; mean [SD] body mass index, 25.9 [4.7]) were enrolled in the study. After 8 weeks, compared with twins randomized to an omnivorous diet, the twins randomized to the vegan diet experienced significant mean (SD) decreases in low-density lipoprotein cholesterol concentration (-13.9 [5.8] mg/dL; 95% CI, -25.3 to -2.4 mg/dL), fasting insulin level (-2.9 [1.3] μIU/mL; 95% CI, -5.3 to -0.4 μIU/mL), and body weight (-1.9 [0.7] kg; 95% CI, -3.3 to -0.6 kg).In this randomized clinical trial of the cardiometabolic effects of omnivorous vs vegan diets in identical twins, the healthy vegan diet led to improved cardiometabolic outcomes compared with a healthy omnivorous diet. Clinicians can consider this dietary approach as a healthy alternative for their patients.ClinicalTrials.gov Identifier: NCT05297825.

    View details for DOI 10.1001/jamanetworkopen.2023.44457

    View details for PubMedID 38032644

  • Host-microbe co-metabolism via MCAD generates circulating metabolites including hippuric acid. Nature communications Pruss, K. M., Chen, H., Liu, Y., Van Treuren, W., Higginbottom, S. K., Jarman, J. B., Fischer, C. R., Mak, J., Wong, B., Cowan, T. M., Fischbach, M. A., Sonnenburg, J. L., Dodd, D. 2023; 14 (1): 512

    Abstract

    The human gut microbiota produces dozens of small molecules that circulate in blood, accumulate to comparable levels as pharmaceutical drugs, and influence host physiology. Despite the importance of these metabolites to human health and disease, the origin of most microbially-produced molecules and their fate in the host remains largely unknown. Here, we uncover a host-microbe co-metabolic pathway for generation of hippuric acid, one of the most abundant organic acids in mammalian urine. Combining stable isotope tracing with bacterial and host genetics, we demonstrate reduction of phenylalanine to phenylpropionic acid by gut bacteria; the host re-oxidizes phenylpropionic acid involving medium-chain acyl-CoA dehydrogenase (MCAD). Generation of germ-free male and female MCAD-/- mice enabled gnotobiotic colonization combined with untargeted metabolomics to identify additional microbial metabolites processed by MCAD in host circulation. Our findings uncover a host-microbe pathway for the abundant, non-toxic phenylalanine metabolite hippurate and identify β-oxidation via MCAD as a novel mechanism by which mammals metabolize microbiota-derived metabolites.

    View details for DOI 10.1038/s41467-023-36138-3

    View details for PubMedID 36720857

  • Butyrate Differentiates Permissiveness to Clostridioides difficile Infection and Influences Growth of Diverse C. difficile Isolates. Infection and immunity Pensinger, D. A., Fisher, A. T., Dobrila, H. A., Van Treuren, W., Gardner, J. O., Higginbottom, S. K., Carter, M. M., Schumann, B., Bertozzi, C. R., Anikst, V., Martin, C., Robilotti, E. V., Chow, J. M., Buck, R. H., Tompkins, L. S., Sonnenburg, J. L., Hryckowian, A. J. 2023: e0057022

    Abstract

    A disrupted "dysbiotic" gut microbiome engenders susceptibility to the diarrheal pathogen Clostridioides difficile by impacting the metabolic milieu of the gut. Diet, in particular the microbiota-accessible carbohydrates (MACs) found in dietary fiber, is one of the most powerful ways to affect the composition and metabolic output of the gut microbiome. As such, diet is a powerful tool for understanding the biology of C. difficile and for developing alternative approaches for coping with this pathogen. One prominent class of metabolites produced by the gut microbiome is short-chain fatty acids (SCFAs), the major metabolic end products of MAC metabolism. SCFAs are known to decrease the fitness of C. difficile in vitro, and high intestinal SCFA concentrations are associated with reduced fitness of C. difficile in animal models of C. difficile infection (CDI). Here, we use controlled dietary conditions (8 diets that differ only by MAC composition) to show that C. difficile fitness is most consistently impacted by butyrate, rather than the other two prominent SCFAs (acetate and propionate), during murine model CDI. We similarly show that butyrate concentrations are lower in fecal samples from humans with CDI than in those from healthy controls. Finally, we demonstrate that butyrate impacts growth in diverse C. difficile isolates. These findings provide a foundation for future work which will dissect how butyrate directly impacts C. difficile fitness and will lead to the development of diverse approaches distinct from antibiotics or fecal transplant, such as dietary interventions, for mitigating CDI in at-risk human populations. IMPORTANCE Clostridioides difficile is a leading cause of infectious diarrhea in humans, and it imposes a tremendous burden on the health care system. Current treatments for C. difficile infection (CDI) include antibiotics and fecal microbiota transplant, which contribute to recurrent CDIs and face major regulatory hurdles, respectively. Therefore, there is an ongoing need to develop new ways to cope with CDI. Notably, a disrupted "dysbiotic" gut microbiota is the primary risk factor for CDI, but we incompletely understand how a healthy microbiota resists CDI. Here, we show that a specific molecule produced by the gut microbiota, butyrate, is negatively associated with C. difficile burdens in humans and in a mouse model of CDI and that butyrate impedes the growth of diverse C. difficile strains in pure culture. These findings help to build a foundation for designing alternative, possibly diet-based, strategies for mitigating CDI in humans.

    View details for DOI 10.1128/iai.00570-22

    View details for PubMedID 36692308

  • A Limited Effect of Chronic Renal Insufficiency on the Colon Microbiome. Journal of the American Society of Nephrology : JASN Guthrie, L., Sonnenburg, J. L., Fischbach, M. A., Meyer, T. W. 2023

    View details for DOI 10.1681/ASN.0000000000000064

    View details for PubMedID 36753629

  • A Microbiome-targeting Fiber-enriched Nutritional Formula is Well Tolerated and Improves Quality of Life and Hemoglobin A1c in Type 2 Diabetes: A Double-Blind, Randomized, Placebo-Controlled Trial. Diabetes, obesity & metabolism Frias, J. P., Lee, M. L., Carter, M. M., Ebel, E. R., Lai, R., Rikse, L., Washington, M. E., Sonneburg, J. L., Damman, C. J. 2023

    Abstract

    AIMS: To investigate a prebiotic fiber-enriched nutritional formula on health-related quality of life and metabolic control in type 2 diabetes.MATERIALS AND METHODS: This was a 12-week, double-blind, placebo-controlled study with an unblinded dietary advice only comparator arm. Participants were randomized 2:1:1 to a prebiotic fiber-enriched nutritional formula (Active), a placebo fiber-absent nutritional formula (Placebo), or non-blinded dietary advice alone (Diet). Primary endpoint was change in core Type 2 Diabetes Distress Assessment System (cT2-DDAS) at week 12. HbA1c change was a key secondary endpoint.RESULTS: 192 participants were randomized. Mean age was 54.3years, HbA1c 7.8%, and BMI 35.9 kg/m2 . At week 12, cT2-DDAS reduced significantly in Active versus Placebo (-0.4, p=0.03), and HbA1c was reduced significantly in Active vs Placebo (-0.64%, p=0.01). Gut microbiome sequencing revealed that the relative abundance of two species of butyrate-producing bacteria (Roseburia faecis and Anaerostipes hadrus) increased significantly in Active vs Placebo.CONCLUSIONS: A microbiome-targeting nutritional formula significantly improved cT2-DDAS and HbA1c, suggesting the potential for prebiotic fiber as a complement to lifestyle and/or pharmaceutical interventions for managing type 2 diabetes. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/dom.14967

    View details for PubMedID 36594522

  • Randomized controlled trial demonstrates response to a probiotic intervention for metabolic syndrome that may correspond to diet. Gut microbes Wastyk, H. C., Perelman, D., Topf, M., Fragiadakis, G. K., Robinson, J. L., Sonnenburg, J. L., Gardner, C. D., Sonnenburg, E. D. 2023; 15 (1): 2178794

    Abstract

    An individual's immune and metabolic status is coupled to their microbiome. Probiotics offer a promising, safe route to influence host health, possibly via the microbiome. Here, we report an 18-week, randomized prospective study that explores the effects of a probiotic vs. placebo supplement on 39 adults with elevated parameters of metabolic syndrome. We performed longitudinal sampling of stool and blood to profile the human microbiome and immune system. While we did not see changes in metabolic syndrome markers in response to the probiotic across the entire cohort, there were significant improvements in triglycerides and diastolic blood pressure in a subset of probiotic arm participants. Conversely, the non-responders had increased blood glucose and insulin levels over time. The responders had a distinct microbiome profile at the end of the intervention relative to the non-responders and placebo arm. Importantly, diet was a key differentiating factor between responders and non-responders. Our results show participant-specific effects of a probiotic supplement on improving parameters of metabolic syndrome and suggest that dietary factors may enhance stability and efficacy of the supplement.

    View details for DOI 10.1080/19490976.2023.2178794

    View details for PubMedID 36803658

  • Gut Microbiome Redox Sensors With Ultrasonic Wake-Up and Galvanic Coupling Wireless Links IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING Baltsavias, S., Van Treuren, W., Sawaby, A., Baker, S. W., Sonnenburg, J. L., Arbabian, A. 2023; 70 (1): 76-87

    Abstract

    Tools to measure in vivo redox activity of the gut microbiome and its influence on host health are lacking. In this paper, we present the design of new in vivo gut oxidation-reduction potential (ORP) sensors for rodents, to study host-microbe and microbe-environment interactions throughout the gut. These are the first in vivo sensors to combine ultrasonic wake-up and galvanic coupling telemetry, allowing for sensor miniaturization, experiment flexibility, and robust wireless measurements in live rodents. A novel study of in situ ORP along the intestine reveals biogeographical redox features that the ORP sensors can uniquely access in future gut microbiome studies.

    View details for DOI 10.1109/TBME.2022.3184972

    View details for Web of Science ID 000936179400008

    View details for PubMedID 35727787

    View details for PubMedCentralID PMC9911315

  • Design, construction, and invivo augmentation of a complex gut microbiome. Cell Cheng, A. G., Ho, P., Aranda-Diaz, A., Jain, S., Yu, F. B., Meng, X., Wang, M., Iakiviak, M., Nagashima, K., Zhao, A., Murugkar, P., Patil, A., Atabakhsh, K., Weakley, A., Yan, J., Brumbaugh, A. R., Higginbottom, S., Dimas, A., Shiver, A. L., Deutschbauer, A., Neff, N., Sonnenburg, J. L., Huang, K. C., Fischbach, M. A. 2022

    Abstract

    Efforts to model the human gut microbiome in mice have led to important insights into the mechanisms of host-microbe interactions. However, the model communities studied to date have been defined or complex, but not both, limiting their utility. Here, we construct and characterize invitro a defined community of 104 bacterial species composed of the most common taxa from the human gut microbiota (hCom1). We then used an iterative experimental process to fill open niches: germ-free mice were colonized with hCom1 and then challenged with a human fecal sample. We identified new species that engrafted following fecal challenge and added them to hCom1, yielding hCom2. In gnotobiotic mice, hCom2 exhibited increased stability to fecal challenge and robust colonization resistance against pathogenic Escherichia coli. Mice colonized by either hCom2 or a human fecal community are phenotypically similar, suggesting that this consortium will enable a mechanistic interrogation of species and genes on microbiome-associated phenotypes.

    View details for DOI 10.1016/j.cell.2022.08.003

    View details for PubMedID 36070752

  • The Tabula Sapiens: A multiple-organ, single-cell transcriptomic atlas of humans. Science (New York, N.Y.) Jones, R. C., Karkanias, J., Krasnow, M. A., Pisco, A. O., Quake, S. R., Salzman, J., Yosef, N., Bulthaup, B., Brown, P., Harper, W., Hemenez, M., Ponnusamy, R., Salehi, A., Sanagavarapu, B. A., Spallino, E., Aaron, K. A., Concepcion, W., Gardner, J. M., Kelly, B., Neidlinger, N., Wang, Z., Crasta, S., Kolluru, S., Morri, M., Pisco, A. O., Tan, S. Y., Travaglini, K. J., Xu, C., Alcántara-Hernández, M., Almanzar, N., Antony, J., Beyersdorf, B., Burhan, D., Calcuttawala, K., Carter, M. M., Chan, C. K., Chang, C. A., Chang, S., Colville, A., Crasta, S., Culver, R. N., Cvijović, I., D'Amato, G., Ezran, C., Galdos, F. X., Gillich, A., Goodyer, W. R., Hang, Y., Hayashi, A., Houshdaran, S., Huang, X., Irwin, J. C., Jang, S., Juanico, J. V., Kershner, A. M., Kim, S., Kiss, B., Kolluru, S., Kong, W., Kumar, M. E., Kuo, A. H., Leylek, R., Li, B., Loeb, G. B., Lu, W. J., Mantri, S., Markovic, M., McAlpine, P. L., de Morree, A., Morri, M., Mrouj, K., Mukherjee, S., Muser, T., Neuhöfer, P., Nguyen, T. D., Perez, K., Phansalkar, R., Pisco, A. O., Puluca, N., Qi, Z., Rao, P., Raquer-McKay, H., Schaum, N., Scott, B., Seddighzadeh, B., Segal, J., Sen, S., Sikandar, S., Spencer, S. P., Steffes, L. C., Subramaniam, V. R., Swarup, A., Swift, M., Travaglini, K. J., Van Treuren, W., Trimm, E., Veizades, S., Vijayakumar, S., Vo, K. C., Vorperian, S. K., Wang, W., Weinstein, H. N., Winkler, J., Wu, T. T., Xie, J., Yung, A. R., Zhang, Y., Detweiler, A. M., Mekonen, H., Neff, N. F., Sit, R. V., Tan, M., Yan, J., Bean, G. R., Charu, V., Forgó, E., Martin, B. A., Ozawa, M. G., Silva, O., Tan, S. Y., Toland, A., Vemuri, V. N., Afik, S., Awayan, K., Botvinnik, O. B., Byrne, A., Chen, M., Dehghannasiri, R., Detweiler, A. M., Gayoso, A., Granados, A. A., Li, Q., Mahmoudabadi, G., McGeever, A., de Morree, A., Olivieri, J. E., Park, M., Pisco, A. O., Ravikumar, N., Salzman, J., Stanley, G., Swift, M., Tan, M., Tan, W., Tarashansky, A. J., Vanheusden, R., Vorperian, S. K., Wang, P., Wang, S., Xing, G., Xu, C., Yosef, N., Alcántara-Hernández, M., Antony, J., Chan, C. K., Chang, C. A., Colville, A., Crasta, S., Culver, R., Dethlefsen, L., Ezran, C., Gillich, A., Hang, Y., Ho, P. Y., Irwin, J. C., Jang, S., Kershner, A. M., Kong, W., Kumar, M. E., Kuo, A. H., Leylek, R., Liu, S., Loeb, G. B., Lu, W. J., Maltzman, J. S., Metzger, R. J., de Morree, A., Neuhöfer, P., Perez, K., Phansalkar, R., Qi, Z., Rao, P., Raquer-McKay, H., Sasagawa, K., Scott, B., Sinha, R., Song, H., Spencer, S. P., Swarup, A., Swift, M., Travaglini, K. J., Trimm, E., Veizades, S., Vijayakumar, S., Wang, B., Wang, W., Winkler, J., Xie, J., Yung, A. R., Artandi, S. E., Beachy, P. A., Clarke, M. F., Giudice, L. C., Huang, F. W., Huang, K. C., Idoyaga, J., Kim, S. K., Krasnow, M., Kuo, C. S., Nguyen, P., Quake, S. R., Rando, T. A., Red-Horse, K., Reiter, J., Relman, D. A., Sonnenburg, J. L., Wang, B., Wu, A., Wu, S. M., Wyss-Coray, T. 2022; 376 (6594): eabl4896

    Abstract

    Molecular characterization of cell types using single-cell transcriptome sequencing is revolutionizing cell biology and enabling new insights into the physiology of human organs. We created a human reference atlas comprising nearly 500,000 cells from 24 different tissues and organs, many from the same donor. This atlas enabled molecular characterization of more than 400 cell types, their distribution across tissues, and tissue-specific variation in gene expression. Using multiple tissues from a single donor enabled identification of the clonal distribution of T cells between tissues, identification of the tissue-specific mutation rate in B cells, and analysis of the cell cycle state and proliferative potential of shared cell types across tissues. Cell type-specific RNA splicing was discovered and analyzed across tissues within an individual.

    View details for DOI 10.1126/science.abl4896

    View details for PubMedID 35549404

  • Global, distinctive, and personal changes in molecular and microbial profiles by specific fibers in humans. Cell host & microbe Lancaster, S. M., Lee-McMullen, B., Abbott, C. W., Quijada, J. V., Hornburg, D., Park, H., Perelman, D., Peterson, D. J., Tang, M., Robinson, A., Ahadi, S., Contrepois, K., Hung, C., Ashland, M., McLaughlin, T., Boonyanit, A., Horning, A., Sonnenburg, J. L., Snyder, M. P. 2022

    Abstract

    Dietary fibers act through the microbiome to improve cardiovascular health and prevent metabolic disorders and cancer. To understand the health benefits of dietary fiber supplementation, we investigated two popular purified fibers, arabinoxylan (AX) and long-chain inulin (LCI), and a mixture of five fibers. We present multiomic signatures of metabolomics, lipidomics, proteomics, metagenomics, a cytokine panel, and clinical measurements on healthy and insulin-resistant participants. Each fiber is associated with fiber-dependent biochemical and microbial responses. AX consumption associates with a significant reduction in LDL and an increase in bile acids, contributing to its observed cholesterol reduction. LCI is associated with an increase in Bifidobacterium. However, at the highest LCI dose, there is increased inflammation and elevation in the liver enzyme alanine aminotransferase. This study yields insights into the effects of fiber supplementation and the mechanisms behind fiber-induced cholesterol reduction, and it shows effects of individual, purified fibers on the microbiome.

    View details for DOI 10.1016/j.chom.2022.03.036

    View details for PubMedID 35483363

  • Oxidative ornithine metabolism supports non-inflammatory C.difficile colonization. Nature metabolism Pruss, K. M., Enam, F., Battaglioli, E., DeFeo, M., Diaz, O. R., Higginbottom, S. K., Fischer, C. R., Hryckowian, A. J., Van Treuren, W., Dodd, D., Kashyap, P., Sonnenburg, J. L. 1800

    Abstract

    The enteric pathogen Clostridioidesdifficile (Cd) is responsible for a toxin-mediated infection that causes more than 200,000 recorded hospitalizations and 13,000 deaths in the United States every year1. However, Cd can colonize the gut in the absence of disease symptoms. Prevalence of asymptomatic colonization by toxigenic Cd in healthy populations is high; asymptomatic carriers are at increased risk of infection compared to noncolonized individuals and may be a reservoir for transmission of Cd infection2,3. Elucidating the molecular mechanisms by which Cd persists in the absence of disease is necessary for understanding pathogenesis and developing refined therapeutic strategies. Here, we show with gut microbiome metatranscriptomic analysis that mice recalcitrant to Cd infection and inflammation exhibit increased community-wide expression of arginine and ornithine metabolic pathways. To query Cd metabolism specifically, we leverage RNA sequencing in gnotobiotic mice infected with two wild-type strains (630 and R20291) and isogenic toxin-deficient mutants of these strains to differentiate inflammation-dependent versus -independent transcriptional states. A single operon encoding oxidative ornithine degradation is consistently upregulated across non-toxigenic Cd strains. Combining untargeted and targeted metabolomics with bacterial and host genetics, we demonstrate that both diet- and host-derived sources of ornithine provide a competitive advantage to Cd, suggesting a mechanism for Cd persistence within a non-inflammatory, healthy gut.

    View details for DOI 10.1038/s42255-021-00506-4

    View details for PubMedID 34992297

  • Establishment and characterization of stable, diverse, fecal-derived in vitro microbial communities that model the intestinal microbiota. Cell host & microbe Aranda-Díaz, A., Ng, K. M., Thomsen, T., Real-Ramírez, I., Dahan, D., Dittmar, S., Gonzalez, C. G., Chavez, T., Vasquez, K. S., Nguyen, T. H., Yu, F. B., Higginbottom, S. K., Neff, N. F., Elias, J. E., Sonnenburg, J. L., Huang, K. C. 2022

    Abstract

    Efforts to probe the role of the gut microbiota in disease would benefit from a system in which patient-derived bacterial communities can be studied at scale. We addressed this by validating a strategy to propagate phylogenetically complex, diverse, stable, and highly reproducible stool-derived communities in vitro. We generated hundreds of in vitro communities cultured from diverse stool samples in various media; certain media generally preserved inoculum composition, and inocula from different subjects yielded source-specific community compositions. Upon colonization of germ-free mice, community composition was maintained, and the host proteome resembled the host from which the community was derived. Treatment with ciprofloxacin in vivo increased susceptibility to Salmonella invasion in vitro, and the in vitro response to ciprofloxacin was predictive of compositional changes observed in vivo, including the resilience and sensitivity of each Bacteroides species. These findings demonstrate that stool-derived in vitro communities can serve as a powerful system for microbiota research.

    View details for DOI 10.1016/j.chom.2021.12.008

    View details for PubMedID 35051349

  • Reporting guidelines for human microbiome research: the STORMS checklist. Nature medicine Mirzayi, C., Renson, A., Genomic Standards Consortium, Massive Analysis and Quality Control Society, Zohra, F., Elsafoury, S., Geistlinger, L., Kasselman, L. J., Eckenrode, K., van de Wijgert, J., Loughman, A., Marques, F. Z., MacIntyre, D. A., Arumugam, M., Azhar, R., Beghini, F., Bergstrom, K., Bhatt, A., Bisanz, J. E., Braun, J., Bravo, H. C., Buck, G. A., Bushman, F., Casero, D., Clarke, G., Collado, M. C., Cotter, P. D., Cryan, J. F., Demmer, R. T., Devkota, S., Elinav, E., Escobar, J. S., Fettweis, J., Finn, R. D., Fodor, A. A., Forslund, S., Franke, A., Furlanello, C., Gilbert, J., Grice, E., Haibe-Kains, B., Handley, S., Herd, P., Holmes, S., Jacobs, J. P., Karstens, L., Knight, R., Knights, D., Koren, O., Kwon, D. S., Langille, M., Lindsay, B., McGovern, D., McHardy, A. C., McWeeney, S., Mueller, N. T., Nezi, L., Olm, M., Palm, N., Pasolli, E., Raes, J., Redinbo, M. R., Ruhlemann, M., Balfour Sartor, R., Schloss, P. D., Schriml, L., Segal, E., Shardell, M., Sharpton, T., Smirnova, E., Sokol, H., Sonnenburg, J. L., Srinivasan, S., Thingholm, L. B., Turnbaugh, P. J., Upadhyay, V., Walls, R. L., Wilmes, P., Yamada, T., Zeller, G., Zhang, M., Zhao, N., Zhao, L., Bao, W., Culhane, A., Devanarayan, V., Dopazo, J., Fan, X., Fischer, M., Jones, W., Kusko, R., Mason, C. E., Mercer, T. R., Sansone, S., Scherer, A., Shi, L., Thakkar, S., Tong, W., Wolfinger, R., Hunter, C., Segata, N., Huttenhower, C., Dowd, J. B., Jones, H. E., Waldron, L., Furlanello, C., Sansone, S. 2021

    Abstract

    The particularly interdisciplinary nature of human microbiome research makes the organization and reporting of results spanning epidemiology, biology, bioinformatics, translational medicine and statistics a challenge. Commonly used reporting guidelines for observational or genetic epidemiology studies lack key features specific to microbiome studies. Therefore, a multidisciplinary group of microbiome epidemiology researchers adapted guidelines for observational and genetic studies to culture-independent human microbiome studies, and also developed new reporting elements for laboratory, bioinformatics and statistical analyses tailored to microbiome studies. The resulting tool, called 'Strengthening The Organization and Reporting of Microbiome Studies' (STORMS), is composed of a 17-item checklist organized into six sections that correspond to the typical sections of a scientific publication, presented as an editable table for inclusion in supplementary materials. The STORMS checklist provides guidance for concise and complete reporting of microbiome studies that will facilitate manuscript preparation, peer review, and reader comprehension of publications and comparative analysis of published results.

    View details for DOI 10.1038/s41591-021-01552-x

    View details for PubMedID 34789871

  • Quantifying rapid bacterial evolution and transmission within the mouse intestine. Cell host & microbe Vasquez, K. S., Willis, L., Cira, N. J., Ng, K. M., Pedro, M. F., Aranda-Diaz, A., Rajendram, M., Yu, F. B., Higginbottom, S. K., Neff, N., Sherlock, G., Xavier, K. B., Quake, S. R., Sonnenburg, J. L., Good, B. H., Huang, K. C. 2021

    Abstract

    Due to limitations on high-resolution strain tracking, selection dynamics during gut microbiota colonization and transmission between hosts remain mostly mysterious. Here, we introduced hundreds of barcoded Escherichiacoli strains into germ-free mice and quantified strain-level dynamics and metagenomic changes. Mutations in genes involved in motility and metabolite utilization are reproducibly selected within days. Even with rapid selection, coprophagy enforced similar barcode distributions across co-housed mice. Whole-genome sequencing of hundreds of isolates revealed linked alleles that demonstrate between-host transmission. A population-genetics model predicts substantial fitness advantages for certain mutants and that migration accounted for 10% of the resident microbiota each day. Treatment with ciprofloxacin suggests interplay between selection and transmission. While initial colonization was mostly uniform, in two mice a bottleneck reduced diversity and selected for ciprofloxacin resistance in the absence of drug. These findings highlight the interplay between environmental transmission and rapid, deterministic selection during evolution of the intestinal microbiota.

    View details for DOI 10.1016/j.chom.2021.08.003

    View details for PubMedID 34473943

  • Ancient human faeces and gut microbes of the past NATURE Olm, M. R., Sonnenburg, J. L. 2021

    View details for DOI 10.1038/d41586-021-01266-7

    View details for Web of Science ID 000651662300001

    View details for PubMedID 34007025

  • Bacterially Derived Tryptamine Increases Mucus Release by Activating a Host Receptor in a Mouse Model of Inflammatory Bowel Disease. iScience Bhattarai, Y., Jie, S., Linden, D. R., Ghatak, S., Mars, R. A., Williams, B. B., Pu, M., Sonnenburg, J. L., Fischbach, M. A., Farrugia, G., Sha, L., Kashyap, P. C. 2020; 23 (12): 101798

    Abstract

    Recent studies emphasize the role of microbial metabolites in regulating gastrointestinal (GI) physiology through activation of host receptors, highlighting the potential for inter-kingdom signaling in treating GI disorders. In this study, we show that tryptamine, a tryptophan-derived bacterial metabolite, stimulates mucus release from goblet cells via activation of G-protein-coupled receptor (GPCR) 5-HT4R. Germ-free mice colonized with engineered Bacteroides thetaiotaomicron optimized to produce tryptamine (Trp D+) exhibit decreased weight loss and increased mucus release following dextran sodium sulfate treatment when compared with mice colonized with control B.thetaiotaomicron (Trp D-). Additional beneficial effects in preventing barrier disruption and lower disease activity index were seen only in female mice, highlighting sex-specific effects of the bacterial metabolite. This study demonstrates potential for the precise modulation of mucus release by microbially produced 5-HT4 GPCR agonist as a therapeutic strategy to treat inflammatory conditions of the GI tract.

    View details for DOI 10.1016/j.isci.2020.101798

    View details for PubMedID 33299969

  • When Gut Microbiota Creep into Fat, the Fat Creeps Back. Cell Spencer, S. P., Sonnenburg, J. L. 2020; 183 (3): 589–91

    Abstract

    Ha and colleagues describe a previously unappreciated diversity of microbes in the mesenteric adipose tissue (MAT) surrounding the GI tract. Viable bacteria that are mislocalized from the gut microbiota and metabolically adapted to the MAT contribute to the "creeping fat" of Crohn's disease.

    View details for DOI 10.1016/j.cell.2020.10.008

    View details for PubMedID 33125887

  • Mucin-derived O-glycans supplemented to diet mitigate diverse microbiota perturbations. The ISME journal Pruss, K. M., Marcobal, A., Southwick, A. M., Dahan, D., Smits, S. A., Ferreyra, J. A., Higginbottom, S. K., Sonnenburg, E. D., Kashyap, P. C., Choudhury, B., Bode, L., Sonnenburg, J. L. 2020

    Abstract

    Microbiota-accessible carbohydrates (MACs) are powerful modulators of microbiota composition and function. These substrates are often derived from diet, such as complex polysaccharides from plants or human milk oligosaccharides (HMOs) during breastfeeding. Host-derived mucus glycans on gut-secreted mucin proteins serve as a continuous endogenous source of MACs for resident microbes; here we investigate the potential role of purified, orally administered mucus glycans in maintaining a healthy microbial community. In this study, we liberated and purified O-linked glycans from porcine gastric mucin and assessed their efficacy in shaping the recovery of a perturbed microbiota in a mouse model. We found that porcine mucin glycans (PMGs) and HMOs enrich for taxonomically similar resident microbes. We demonstrate that PMGs aid recovery of the microbiota after antibiotic treatment, suppress Clostridium difficile abundance, delay the onset of diet-induced obesity, and increase the relative abundance of resident Akkermansia muciniphila. In silico analysis revealed that genes associated with mucus utilization are abundant and diverse in prevalent gut commensals and rare in enteric pathogens, consistent with these glycan-degrading capabilities being selected for during host development and throughout the evolution of the host-microbe relationship. Importantly, we identify mucus glycans as a novel class of prebiotic compounds that can be used to mitigate perturbations to the microbiota and provide benefits to host physiology.

    View details for DOI 10.1038/s41396-020-00798-6

    View details for PubMedID 33087860

  • Bifidobacterium alters the gut microbiota and modulates the functional metabolism of T regulatory cells in the context of immune checkpoint blockade. Proceedings of the National Academy of Sciences of the United States of America Sun, S., Luo, L., Liang, W., Yin, Q., Guo, J., Rush, A. M., Lv, Z., Liang, Q., Fischbach, M. A., Sonnenburg, J. L., Dodd, D., Davis, M. M., Wang, F. 2020

    Abstract

    Immune checkpoint-blocking antibodies that attenuate immune tolerance have been used to effectively treat cancer, but they can also trigger severe immune-related adverse events. Previously, we found that Bifidobacterium could mitigate intestinal immunopathology in the context of CTLA-4 blockade in mice. Here we examined the mechanism underlying this process. We found that Bifidobacterium altered the composition of the gut microbiota systematically in a regulatory T cell (Treg)-dependent manner. Moreover, this altered commensal community enhanced both the mitochondrial fitness and the IL-10-mediated suppressive functions of intestinal Tregs, contributing to the amelioration of colitis during immune checkpoint blockade.

    View details for DOI 10.1073/pnas.1921223117

    View details for PubMedID 33077598

  • High-Throughput Stool Metaproteomics: Method and Application to Human Specimens. mSystems Gonzalez, C. G., Wastyk, H. C., Topf, M., Gardner, C. D., Sonnenburg, J. L., Elias, J. E. 2020; 5 (3)

    Abstract

    Stool-based proteomics is capable of significantly augmenting our understanding of host-gut microbe interactions. However, compared to competing technologies, such as metagenomics and 16S rRNA sequencing, it is underutilized due to its low throughput and the negative impact sample contaminants can have on highly sensitive mass spectrometry equipment. Here, we present a new stool proteomic processing pipeline that addresses these shortcomings in a highly reproducible and quantitative manner. Using this method, 290 samples from a dietary intervention study were processed in approximately 1.5weeks, largely done by a single researcher. These data indicated a subtle but distinct monotonic increase in the number of significantly altered proteins between study participants on fiber- or fermented food-enriched diets. Lastly, we were able to classify study participants based on their diet-altered proteomic profiles and demonstrated that classification accuracies of up to 89% could be achieved by increasing the number of subjects considered. Taken together, this study represents the first high-throughput proteomic method for processing stool samples in a technically reproducible manner and has the potential to elevate stool-based proteomics as an essential tool for profiling host-gut microbiome interactions in a clinical setting.IMPORTANCE Widely available technologies based on DNA sequencing have been used to describe the kinds of microbes that might correlate with health and disease. However, mechanistic insights might be best achieved through careful study of the dynamic proteins at the interface between the foods we eat, our microbes, and ourselves. Mass spectrometry-based proteomics has the potential to revolutionize our understanding of this complex system, but its application to clinical studies has been hampered by low-throughput and laborious experimentation pipelines. In response, we developed SHT-Pro, the first high-throughput pipeline designed to rapidly handle large stool sample sets. With it, a single researcher can process over one hundred stool samples per week for mass spectrometry analysis, conservatively approximately 10* to 100* faster than previous methods, depending on whether isobaric labeling is used or not. Since SHT-Pro is fairly simple to implement using commercially available reagents, it should be easily adaptable to large-scale clinical studies.

    View details for DOI 10.1128/mSystems.00200-20

    View details for PubMedID 32606025

  • Phase-variable capsular polysaccharides and lipoproteins modify bacteriophage susceptibility in Bacteroides thetaiotaomicron. Nature microbiology Porter, N. T., Hryckowian, A. J., Merrill, B. D., Fuentes, J. J., Gardner, J. O., Glowacki, R. W., Singh, S., Crawford, R. D., Snitkin, E. S., Sonnenburg, J. L., Martens, E. C. 2020

    Abstract

    A variety of cell surface structures dictate interactions between bacteria and their environment, including their viruses (bacteriophages). Members of the human gut Bacteroidetes characteristically produce several phase-variable capsular polysaccharides (CPSs), but their contributions to bacteriophage interactions are unknown. To begin to understand how CPSs have an impact on Bacteroides-phage interactions, we isolated 71 Bacteroides thetaiotaomicron-infecting bacteriophages from two locations in the United States. Using B. thetaiotaomicron strains that express defined subsets of CPSs, we show that CPSs dictate host tropism for these phages and that expression of non-permissive CPS variants is selected under phage predation, enabling survival. In the absence of CPSs, B. thetaiotaomicron escapes bacteriophage predation by altering expression of eight distinct phase-variable lipoproteins. When constitutively expressed, one of these lipoproteins promotes resistance to multiple bacteriophages. Our results reveal important roles for Bacteroides CPSs and other cell surface structures that allow these bacteria to persist under bacteriophage predation, and hold important implications for using bacteriophages therapeutically to target gut symbionts.

    View details for DOI 10.1038/s41564-020-0746-5

    View details for PubMedID 32601452

  • The Clinical Drug Ebselen Attenuates Inflammation and Promotes Microbiome Recovery in Mice after Antibiotic Treatment for CDI. Cell reports medicine Garland, M., Hryckowian, A. J., Tholen, M., Bender, K. O., Van Treuren, W. W., Loscher, S., Sonnenburg, J. L., Bogyo, M. 2020; 1 (1)

    Abstract

    Clostridium difficile infection (CDI) is an enteric bacterial disease that is increasing in prevalence worldwide. C. difficile capitalizes on gut inflammation and microbiome dysbiosis to establish infection, with symptoms ranging from watery diarrhea to toxic megacolon. We reported that the safe-in-human clinical drug ebselen (ClinicalTrials.gov: NCT03013400, NCT01452607, NCT00762671, and NCT02603081) has biochemical, cell-based, and in vivo efficacy against the toxins of C. difficile. Here, we show that ebselen treatment reduces recurrence rates and decreases colitis in a hamster model of relapsing CDI. Furthermore, ebselen treatment does not alter microbiome diversity and promotes recovery back to that of healthy controls after antibiotic-induced dysbiosis in healthy and C. difficile-infected mice. This increased microbiome recovery upon ebselen treatment correlates with a decrease in host-derived inflammatory markers, suggesting that the anti-inflammatory properties of ebselen, combined with its anti-toxin function, help to mitigate the major clinical challenges of CDI, including recurrence, microbial dysbiosis, and colitis.

    View details for DOI 10.1016/j.xcrm.2020.100005

    View details for PubMedID 32483557

  • Long-term dietary intervention reveals resilience of the gut microbiota despite changes in diet and weight. The American journal of clinical nutrition Fragiadakis, G. K., Wastyk, H. C., Robinson, J. L., Sonnenburg, E. D., Sonnenburg, J. L., Gardner, C. D. 2020

    Abstract

    BACKGROUND: With the rising rates of obesity and associated metabolic disorders, there is a growing need for effective long-term weight-loss strategies, coupled with an understanding of how they interface with human physiology. Interest is growing in the potential role of gut microbes as they pertain to responses to different weight-loss diets; however, the ways that diet, the gut microbiota, and long-term weight loss influence one another is not well understood.OBJECTIVES: Our primary objective was to determine if baseline microbiota composition or diversity was associated with weight-loss success. A secondary objective was to track the longitudinal associations of changes to lower-carbohydrate or lower-fat diets and concomitant weight loss with the composition and diversity of the gut microbiota.METHODS: We used 16S ribosomal RNA gene amplicon sequencing to profile microbiota composition over a 12-mo period in 49 participants as part of a larger randomized dietary intervention study of participants consuming either a healthy low-carbohydrate or a healthy low-fat diet.RESULTS: While baseline microbiota composition was not predictive of weight loss, each diet resulted in substantial changes in the microbiota 3-mo after the start of the intervention; some of these changes were diet specific (14 taxonomic changes specific to the healthy low-carbohydrate diet, 12 taxonomic changes specific to the healthy low-fat diet) and others tracked with weight loss (7 taxonomic changes in both diets). After these initial shifts, the microbiota returned near its original baseline state for the remainder of the intervention, despite participants maintaining their diet and weight loss for the entire study.CONCLUSIONS: These results suggest a resilience to perturbation of the microbiota's starting profile. When considering the established contribution of obesity-associated microbiotas to weight gain in animal models, microbiota resilience may need to be overcome for long-term alterations to human physiology. This trial was registered at clinicaltrials.gov as NCT01826591.

    View details for DOI 10.1093/ajcn/nqaa046

    View details for PubMedID 32186326

  • A Metabolic Pathway for Activation of Dietary Glucosinolates by a Human Gut Symbiont. Cell Liou, C. S., Sirk, S. J., Diaz, C. A., Klein, A. P., Fischer, C. R., Higginbottom, S. K., Erez, A., Donia, M. S., Sonnenburg, J. L., Sattely, E. S. 2020; 180 (4): 717

    Abstract

    Consumption of glucosinolates, pro-drug-like metabolites abundant in Brassica vegetables, has been associated with decreased risk of certain cancers. Gut microbiota have the ability to metabolize glucosinolates, generating chemopreventive isothiocyanates. Here, we identify a genetic and biochemical basis for activation of glucosinolates to isothiocyanates by Bacteroides thetaiotaomicron, a prominent gut commensal species. Using a genome-wide transposon insertion screen, we identified an operon required for glucosinolate metabolism in B.thetaiotaomicron. Expression of BT2159-BT2156 in a non-metabolizing relative, Bacteroides fragilis, resulted in gain of glucosinolate metabolism. We show that isothiocyanate formation requires the action of BT2158 and either BT2156 or BT2157 invitro. Monocolonization of mice with mutant BtDelta2157 showed reduced isothiocyanate production in the gastrointestinal tract. These data provide insight into the mechanisms by which a common gut bacterium processes an important dietary nutrient.

    View details for DOI 10.1016/j.cell.2020.01.023

    View details for PubMedID 32084341

  • Dysbiosis-Induced Secondary Bile Acid Deficiency Promotes Intestinal Inflammation. Cell host & microbe Sinha, S. R., Haileselassie, Y., Nguyen, L. P., Tropini, C., Wang, M., Becker, L. S., Sim, D., Jarr, K., Spear, E. T., Singh, G., Namkoong, H., Bittinger, K., Fischbach, M. A., Sonnenburg, J. L., Habtezion, A. 2020

    Abstract

    Secondary bile acids (SBAs) are derived from primary bile acids (PBAs) in a process reliant on biosynthetic capabilities possessed by few microbes. To evaluate the role of BAs in intestinal inflammation, we performed metabolomic, microbiome, metagenomic, and transcriptomic profiling of stool from ileal pouches (surgically created resevoirs) in colectomy-treated patients with ulcerative colitis (UC) versus controls (familial adenomatous polyposis [FAP]). We show that relative to FAP, UC pouches have reduced levels of lithocholic acid and deoxycholic acid (normally the most abundant gut SBAs), genes required to convert PBAs to SBAs, and Ruminococcaceae (one of few taxa known to include SBA-producing bacteria). In three murine colitis models, SBA supplementation reduces intestinal inflammation. This anti-inflammatory effect is in part dependent on the TGR5 bile acid receptor. These data suggest that dysbiosis induces SBA deficiency in inflammatory-prone UC patients, which promotes a pro-inflammatory state within the intestine that may be treated by SBA restoration.

    View details for DOI 10.1016/j.chom.2020.01.021

    View details for PubMedID 32101703

  • Klebsiella michiganensis transmission enhances resistance to Enterobacteriaceae gut invasion by nutrition competition. Nature microbiology Oliveira, R. A., Ng, K. M., Correia, M. B., Cabral, V., Shi, H., Sonnenburg, J. L., Huang, K. C., Xavier, K. B. 2020

    Abstract

    Intestinal microbiotas contain beneficial microorganisms that protect against pathogen colonization; treatment with antibiotics disrupts the microbiota and compromises colonization resistance. Here, we determine the impact of exchanging microorganisms between hosts on resilience to the colonization of invaders after antibiotic-induced dysbiosis. We assess the functional consequences of dysbiosis using a mouse model of colonization resistance against Escherichia coli. Antibiotics caused stochastic loss of members of the microbiota, but the microbiotas of co-housed mice remained more similar to each other compared with the microbiotas among singly housed animals. Strikingly, co-housed mice maintained colonization resistance after treatment with antibiotics, whereas most singly housed mice were susceptible to E. coli. The ability to retain or share the commensal Klebsiella michiganensis, a member of the Enterobacteriaceae family, was sufficient for colonization resistance after treatment with antibiotics. K. michiganensis generally outcompeted E. coli in vitro, but in vivo administration of galactitol-a nutrient that supports the growth of only E. coli-to bi-colonized gnotobiotic mice abolished the colonization-resistance capacity of K. michiganensis against E. coli, supporting the idea that nutrient competition is the primary interaction mechanism. K. michiganensis also hampered colonization of the pathogen Salmonella, prolonging host survival. Our results address functional consequences of the stochastic effects of microbiota perturbations, whereby microbial transmission through host interactions can facilitate reacquisition of beneficial commensals, minimizing the negative impact of antibiotics.

    View details for DOI 10.1038/s41564-019-0658-4

    View details for PubMedID 31959968

  • A single-cell transcriptomic atlas characterizes ageing tissues in the mouse. Nature 2020

    Abstract

    Ageing is characterized by a progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death1. Despite rapid advances over recent years, many of the molecular and cellular processes that underlie the progressive loss of healthy physiology are poorly understood2. To gain a better insight into these processes, here we generate a single-cell transcriptomic atlas across the lifespan of Mus musculus that includes data from 23 tissues and organs. We found cell-specific changes occurring across multiple cell types and organs, as well as age-related changes in the cellular composition of different organs. Using single-cell transcriptomic data, we assessed cell-type-specific manifestations of different hallmarks of ageing-such as senescence3, genomic instability4 and changes in the immune system2. This transcriptomic atlas-which we denote Tabula Muris Senis, or 'Mouse Ageing Cell Atlas'-provides molecular information about how the most important hallmarks of ageing are reflected in a broad range of tissues and cell types.

    View details for DOI 10.1038/s41586-020-2496-1

    View details for PubMedID 32669714

  • Proximal colon-derived O-glycosylated mucus encapsulates and modulates the microbiota. Science (New York, N.Y.) Bergstrom, K. n., Shan, X. n., Casero, D. n., Batushansky, A. n., Lagishetty, V. n., Jacobs, J. P., Hoover, C. n., Kondo, Y. n., Shao, B. n., Gao, L. n., Zandberg, W. n., Noyovitz, B. n., McDaniel, J. M., Gibson, D. L., Pakpour, S. n., Kazemian, N. n., McGee, S. n., Houchen, C. W., Rao, C. V., Griffin, T. M., Sonnenburg, J. L., McEver, R. P., Braun, J. n., Xia, L. n. 2020; 370 (6515): 467–72

    Abstract

    Colon mucus segregates the intestinal microbiota from host tissues, but how it organizes to function throughout the colon is unclear. In mice, we found that colon mucus consists of two distinct O-glycosylated entities of Muc2: a major form produced by the proximal colon, which encapsulates the fecal material including the microbiota, and a minor form derived from the distal colon, which adheres to the major form. The microbiota directs its own encapsulation by inducing Muc2 production from proximal colon goblet cells. In turn, O-glycans on proximal colon-derived Muc2 modulate the structure and function of the microbiota as well as transcription in the colon mucosa. Our work shows how proximal colon control of mucin production is an important element in the regulation of host-microbiota symbiosis.

    View details for DOI 10.1126/science.aay7367

    View details for PubMedID 33093110

  • Bacteroides thetaiotaomicron-Infecting Bacteriophage Isolates Inform Sequence-Based Host Range Predictions. Cell host & microbe Hryckowian, A. J., Merrill, B. D., Porter, N. T., Van Treuren, W. n., Nelson, E. J., Garlena, R. A., Russell, D. A., Martens, E. C., Sonnenburg, J. L. 2020

    Abstract

    Our emerging view of the gut microbiome largely focuses on bacteria, while less is known about other microbial components, such as bacteriophages (phages). Though phages are abundant in the gut, very few phages have been isolated from this ecosystem. Here, we report the genomes of 27 phages from the United States and Bangladesh that infect the prevalent human gut bacterium Bacteroides thetaiotaomicron. These phages are mostly distinct from previously sequenced phages with the exception of two, which are crAss-like phages. We compare these isolates to existing human gut metagenomes, revealing similarities to previously inferred phages and additional unexplored phage diversity. Finally, we use host tropisms of these phages to identify alleles of phage structural genes associated with infectivity. This work provides a detailed view of the gut's "viral dark matter" and a framework for future efforts to further integrate isolation- and sequencing-focused efforts to understand gut-resident phages.

    View details for DOI 10.1016/j.chom.2020.06.011

    View details for PubMedID 32652063

  • Ageing hallmarks exhibit organ-specific temporal signatures. Nature Schaum, N. n., Lehallier, B. n., Hahn, O. n., Pálovics, R. n., Hosseinzadeh, S. n., Lee, S. E., Sit, R. n., Lee, D. P., Losada, P. M., Zardeneta, M. E., Fehlmann, T. n., Webber, J. T., McGeever, A. n., Calcuttawala, K. n., Zhang, H. n., Berdnik, D. n., Mathur, V. n., Tan, W. n., Zee, A. n., Tan, M. n., Pisco, A. O., Karkanias, J. n., Neff, N. F., Keller, A. n., Darmanis, S. n., Quake, S. R., Wyss-Coray, T. n. 2020

    Abstract

    Ageing is the single greatest cause of disease and death worldwide, and understanding the associated processes could vastly improve quality of life. Although major categories of ageing damage have been identified-such as altered intercellular communication, loss of proteostasis and eroded mitochondrial function1-these deleterious processes interact with extraordinary complexity within and between organs, and a comprehensive, whole-organism analysis of ageing dynamics has been lacking. Here we performed bulk RNA sequencing of 17 organs and plasma proteomics at 10 ages across the lifespan of Mus musculus, and integrated these findings with data from the accompanying Tabula Muris Senis2-or 'Mouse Ageing Cell Atlas'-which follows on from the original Tabula Muris3. We reveal linear and nonlinear shifts in gene expression during ageing, with the associated genes clustered in consistent trajectory groups with coherent biological functions-including extracellular matrix regulation, unfolded protein binding, mitochondrial function, and inflammatory and immune response. Notably, these gene sets show similar expression across tissues, differing only in the amplitude and the age of onset of expression. Widespread activation of immune cells is especially pronounced, and is first detectable in white adipose depots during middle age. Single-cell RNA sequencing confirms the accumulation of T cells and B cells in adipose tissue-including plasma cells that express immunoglobulin J-which also accrue concurrently across diverse organs. Finally, we show how gene expression shifts in distinct tissues are highly correlated with corresponding protein levels in plasma, thus potentially contributing to the ageing of the systemic circulation. Together, these data demonstrate a similar yet asynchronous inter- and intra-organ progression of ageing, providing a foundation from which to track systemic sources of declining health at old age.

    View details for DOI 10.1038/s41586-020-2499-y

    View details for PubMedID 32669715

  • Longitudinal Multi-omics Reveals Subset-Specific Mechanisms Underlying Irritable Bowel Syndrome. Cell Mars, R. A., Yang, Y. n., Ward, T. n., Houtti, M. n., Priya, S. n., Lekatz, H. R., Tang, X. n., Sun, Z. n., Kalari, K. R., Korem, T. n., Bhattarai, Y. n., Zheng, T. n., Bar, N. n., Frost, G. n., Johnson, A. J., van Treuren, W. n., Han, S. n., Ordog, T. n., Grover, M. n., Sonnenburg, J. n., D'Amato, M. n., Camilleri, M. n., Elinav, E. n., Segal, E. n., Blekhman, R. n., Farrugia, G. n., Swann, J. R., Knights, D. n., Kashyap, P. C. 2020

    Abstract

    The gut microbiome has been implicated in multiple human chronic gastrointestinal (GI) disorders. Determining its mechanistic role in disease has been difficult due to apparent disconnects between animal and human studies and lack of an integrated multi-omics view of disease-specific physiological changes. We integrated longitudinal multi-omics data from the gut microbiome, metabolome, host epigenome, and transcriptome in the context of irritable bowel syndrome (IBS) host physiology. We identified IBS subtype-specific and symptom-related variation in microbial composition and function. A subset of identified changes in microbial metabolites correspond to host physiological mechanisms that are relevant to IBS. By integrating multiple data layers, we identified purine metabolism as a novel host-microbial metabolic pathway in IBS with translational potential. Our study highlights the importance of longitudinal sampling and integrating complementary multi-omics data to identify functional mechanisms that can serve as therapeutic targets in a comprehensive treatment strategy for chronic GI diseases. VIDEO ABSTRACT.

    View details for DOI 10.1016/j.cell.2020.08.007

    View details for PubMedID 32916129

  • A randomized crossover trial on the effect of plant-based compared with animal-based meat on trimethylamine-N-oxide and cardiovascular disease risk factors in generally healthy adults: Study With Appetizing Plantfood-Meat Eating Alternative Trial (SWAP-MEAT). The American journal of clinical nutrition Crimarco, A. n., Springfield, S. n., Petlura, C. n., Streaty, T. n., Cunanan, K. n., Lee, J. n., Fielding-Singh, P. n., Carter, M. M., Topf, M. A., Wastyk, H. C., Sonnenburg, E. D., Sonnenburg, J. L., Gardner, C. D. 2020

    Abstract

    Despite the rising popularity of plant-based alternative meats, there is limited evidence of the health effects of these products.We aimed to compare the effect of consuming plant-based alternative meat (Plant) as opposed to animal meat (Animal) on health factors. The primary outcome was fasting serum trimethylamine-N-oxide (TMAO). Secondary outcomes included fasting insulin-like growth factor 1, lipids, glucose, insulin, blood pressure, and weight.SWAP-MEAT (The Study With Appetizing Plantfood-Meat Eating Alternatives Trial) was a single-site, randomized crossover trial with no washout period. Participants received Plant and Animal products, dietary counseling, lab assessments, microbiome assessments (16S), and anthropometric measurements. Participants were instructed to consume ≥2 servings/d of Plant compared with Animal for 8 wk each, while keeping all other foods and beverages as similar as possible between the 2 phases.The 36 participants who provided complete data for both crossover phases included 67% women, were 69% Caucasian, had a mean ± SD age 50 ± 14 y, and BMI 28 ± 5 kg/m2. Mean ± SD servings per day were not different by intervention sequence: 2.5 ± 0.6 compared with 2.6 ± 0.7 for Plant and Animal, respectively (P = 0.76). Mean ± SEM TMAO concentrations were significantly lower overall for Plant (2.7 ± 0.3) than for Animal (4.7 ± 0.9) (P = 0.012), but a significant order effect was observed (P = 0.023). TMAO concentrations were significantly lower for Plant among the n = 18 who received Plant second (2.9 ± 0.4 compared with 6.4 ± 1.5, Plant compared with Animal, P = 0.007), but not for the n = 18 who received Plant first (2.5 ± 0.4 compared with 3.0 ± 0.6, Plant compared with Animal, P = 0.23). Exploratory analyses of the microbiome failed to reveal possible responder compared with nonresponder factors. Mean ± SEM LDL-cholesterol concentrations (109.9 ± 4.5 compared with 120.7 ± 4.5 mg/dL, P = 0.002) and weight (78.7 ± 3.0 compared with 79.6 ± 3.0 kg, P < 0.001) were lower during the Plant phase.Among generally healthy adults, contrasting Plant with Animal intake, while keeping all other dietary components similar, the Plant products improved several cardiovascular disease risk factors, including TMAO; there were no adverse effects on risk factors from the Plant products.This trial was registered at clinicaltrials.gov as NCT03718988.

    View details for DOI 10.1093/ajcn/nqaa203

    View details for PubMedID 32780794

  • Depletion of microbiome-derived molecules in the host using Clostridium genetics. Science (New York, N.Y.) Guo, C., Allen, B. M., Hiam, K. J., Dodd, D., Van Treuren, W., Higginbottom, S., Nagashima, K., Fischer, C. R., Sonnenburg, J. L., Spitzer, M. H., Fischbach, M. A. 2019; 366 (6471)

    Abstract

    The gut microbiota produce hundreds of molecules that are present at high concentrations in the host circulation. Unraveling the contribution of each molecule to host biology remains difficult. We developed a system for constructing clean deletions in Clostridium spp., the source of many molecules from the gut microbiome. By applying this method to the model commensal organism Clostridium sporogenes, we knocked out genes for 10 C. sporogenes-derived molecules that accumulate in host tissues. In mice colonized by a C. sporogenes for which the production of branched short-chain fatty acids was knocked out, we discovered that these microbial products have immunoglobulin A-modulatory activity.

    View details for DOI 10.1126/science.aav1282

    View details for PubMedID 31831639

  • Intestinal IgA Regulates Expression of a Fructan Polysaccharide Utilization Locus in Colonizing Gut Commensal Bacteroides thetaiotaomicron. mBio Joglekar, P., Ding, H., Canales-Herrerias, P., Pasricha, P. J., Sonnenburg, J. L., Peterson, D. A. 2019; 10 (6)

    Abstract

    Gut-derived immunoglobulin A (IgA) is the most abundant antibody secreted in the gut that shapes gut microbiota composition and functionality. However, most of the microbial antigens targeted by gut IgA remain unknown, and the functional effects of IgA targeting these antigens are currently understudied. This study provides a framework for identifying and characterizing gut microbiota antigens targeted by gut IgA. We developed a small intestinal ex vivo culture assay to harvest lamina propria IgA from gnotobiotic mice, with the aim of identifying antigenic targets in a model human gut commensal, Bacteroides thetaiotaomicron VPI-5482. Colonization by B. thetaiotaomicron induced a microbe-specific IgA response that was reactive against diverse antigens, including capsular polysaccharides, lipopolysaccharides, and proteins. IgA against microbial protein antigens targeted membrane and secreted proteins with diverse functionalities, including an IgA specific against proteins of the polysaccharide utilization locus (PUL) that are necessary for utilization of fructan, which is an important dietary polysaccharide. Further analyses demonstrated that the presence of dietary fructan increased the production of fructan PUL-specific IgA, which then downregulated the expression of fructan PUL in B. thetaiotaomicron, both in vivo and in vitro Since the expression of fructan PUL has been associated with the ability of B. thetaiotaomicron to colonize the gut in the presence of dietary fructans, our work suggests a novel role for gut IgA in regulating microbial colonization by modulating their metabolism.IMPORTANCE Given the significant impact that gut microbes have on our health, it is essential to identify key host and environmental factors that shape this diverse community. While many studies have highlighted the impact of diet on gut microbiota, little is known about how the host regulates this critical diet-microbiota interaction. In our present study, we discovered that gut IgA targeted a protein complex involved in the utilization of an important dietary polysaccharide: fructan. While the presence of dietary fructans was previously thought to allow unrestricted growth of fructan-utilizing bacteria, our work shows that gut IgA, by targeting proteins responsible for fructan utilization, provides the host with tools that can restrict the microbial utilization of such polysaccharides, thereby controlling their growth.

    View details for DOI 10.1128/mBio.02324-19

    View details for PubMedID 31690674

  • Pursuing Human-Relevant Gut Microbiota-Immune Interactions. Immunity Spencer, S. P., Fragiadakis, G. K., Sonnenburg, J. L. 2019; 51 (2): 225–39

    Abstract

    The gut microbiota is a complex and plastic network of diverse organisms intricately connected with human physiology. Recent advances in profiling approaches of both the microbiota and the immune system now enable a deeper exploration of immunity-microbiota connections. An important next step is to elucidate a human-relevant "map" of microbial-immune wiring while focusing on animal studies to probe a prioritized subset of interactions. Here, we provide an overview of this field's current status and discuss two approaches for establishing priorities for detailed investigation: (1) longitudinal intervention studies in humans probing the dynamics of both the microbiota and the immune system and (2) the study of traditional populations to assess lost features of human microbial identity whose absence may be contributing to the rise of immunological disorders. These human-centered approaches offer a judicious path forward to understand the impact of the microbiota in immune development and function.

    View details for DOI 10.1016/j.immuni.2019.08.002

    View details for PubMedID 31433970

  • The ancestral and industrialized gut microbiota and implications for human health NATURE REVIEWS MICROBIOLOGY Sonnenburg, E. D., Sonnenburg, J. L. 2019; 17 (6): 383–90
  • The ancestral and industrialized gut microbiota and implications for human health. Nature reviews. Microbiology Sonnenburg, E. D., Sonnenburg, J. L. 2019; 17 (6): 383–90

    Abstract

    Human-associated microbial communities have adapted to environmental pressures. Doses of antibiotics select for a community with increased antibiotic resistance, inflammation is accompanied by expansion of community members equipped to flourish in the presence of immune effectors and Western diets shift the microbiota away from fibre degraders in favour of species that thrive on mucus. Recent data suggest that the microbiota of industrialized societies differs substantially from the recent ancestral microbiota of humans. Rapid modernization, including medical practices and dietary changes, is causing progressive deterioration of the microbiota, and we hypothesize that this may contribute to various diseases prevalent in industrialized societies. In this Opinion article, we explore whether individuals in the industrialized world may be harbouring a microbial community that, while compatible with our environment, is now incompatible with our human biology.

    View details for PubMedID 31089293

  • Role for Diet in Normal Gut Barrier Function: Developing Guidance within the Framework of Food Labeling Regulations. American journal of physiology. Gastrointestinal and liver physiology Camilleri, M., Lyle, B. J., Madsen, K. L., Sonnenburg, J. L., Verbeke, K., Wu, G. D. 2019

    Abstract

    A reduction in intestinal barrier function is currently believed to play an important role in pathogenesis of many diseases, as it facilitates passage of injurious factors such as lipopolysaccharide, peptidoglycan, whole bacteria and other toxins to traverse the barrier to damage the intestine or enter the portal circulation. Currently available evidence in animal models and in vitro systems has shown that certain dietary interventions can be used to reinforce the intestinal barrier to prevent the development of disease. The relevance of these studies to human health is unknown. Herein, we define the components of the intestinal barrier, review available modalities to assess its structure and function in humans, and review the available evidence in model systems or perturbations in humans that diet can be used to fortify intestinal barrier function. Acknowledging the technical challenges and the current gaps in knowledge, we provide a conceptual framework by which evidence could be developed to support the notion that diet can reinforce human intestinal barrier function to restore normal function and potentially reduce the risk for disease. Such evidence would provide information on the development of healthier diets and serve to provide a framework by which federal agencies such as the FDA can evaluate evidence linking diet with normal human structure/function claims focused on reducing risk of disease in the general public.

    View details for DOI 10.1152/ajpgi.00063.2019

    View details for PubMedID 31125257

  • Small intestinal microbial dysbiosis underlies symptoms associated with functional gastrointestinal disorders NATURE COMMUNICATIONS Saffouri, G. B., Shields-Cutler, R. R., Chen, J., Yang, Y., Lekatz, H. R., Hale, V. L., Cho, J. M., Battaglioli, E. J., Bhattarai, Y., Thompson, K. J., Kalari, K. K., Behera, G., Berry, J. C., Peters, S. A., Patel, R., Schuetz, A. N., Faith, J. J., Camilleri, M., Sonnenburg, J. L., Farrugia, G., Swann, J. R., Grover, M., Knights, D., Kashyap, P. C. 2019; 10
  • Western diet regulates immune status and the response to LPS-driven sepsis independent of diet-associated microbiome PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Napier, B. A., Andres-Terre, M., Massis, L. M., Hryckowian, A. J., Higginbottom, S. K., Cumnock, K., Casey, K. M., Haileselassie, B., Lugo, K. A., Schneider, D. S., Sonnenburg, J. L., Monack, D. M. 2019; 116 (9): 3688–94
  • Western diet regulates immune status and the response to LPS-driven sepsis independent of diet-associated microbiome. Proceedings of the National Academy of Sciences of the United States of America Napier, B. A., Andres-Terre, M., Massis, L. M., Hryckowian, A. J., Higginbottom, S. K., Cumnock, K., Casey, K. M., Haileselassie, B., Lugo, K. A., Schneider, D. S., Sonnenburg, J. L., Monack, D. M. 2019; 116 (9): 3688–94

    Abstract

    Sepsis is a deleterious immune response to infection that leads to organ failure and is the 11th most common cause of death worldwide. Despite plaguing humanity for thousands of years, the host factors that regulate this immunological response and subsequent sepsis severity and outcome are not fully understood. Here we describe how the Western diet (WD), a diet high in fat and sucrose and low in fiber, found rampant in industrialized countries, leads to worse disease and poorer outcomes in an LPS-driven sepsis model in WD-fed mice compared with mice fed standard fiber-rich chow (SC). We find that WD-fed mice have higher baseline inflammation (metaflammation) and signs of sepsis-associated immunoparalysis compared with SC-fed mice. WD mice also have an increased frequency of neutrophils, some with an "aged" phenotype, in the blood during sepsis compared with SC mice. Importantly, we found that the WD-dependent increase in sepsis severity and higher mortality is independent of the microbiome, suggesting that the diet may be directly regulating the innate immune system through an unknown mechanism. Strikingly, we could predict LPS-driven sepsis outcome by tracking specific WD-dependent disease factors (e.g., hypothermia and frequency of neutrophils in the blood) during disease progression and recovery. We conclude that the WD is reprogramming the basal immune status and acute response to LPS-driven sepsis and that this correlates with alternative disease paths that lead to more severe disease and poorer outcomes.

    View details for PubMedID 30808756

  • Small intestinal microbial dysbiosis underlies symptoms associated with functional gastrointestinal disorders. Nature communications Saffouri, G. B., Shields-Cutler, R. R., Chen, J. n., Yang, Y. n., Lekatz, H. R., Hale, V. L., Cho, J. M., Battaglioli, E. J., Bhattarai, Y. n., Thompson, K. J., Kalari, K. K., Behera, G. n., Berry, J. C., Peters, S. A., Patel, R. n., Schuetz, A. N., Faith, J. J., Camilleri, M. n., Sonnenburg, J. L., Farrugia, G. n., Swann, J. R., Grover, M. n., Knights, D. n., Kashyap, P. C. 2019; 10 (1): 2012

    Abstract

    Small intestinal bacterial overgrowth (SIBO) has been implicated in symptoms associated with functional gastrointestinal disorders (FGIDs), though mechanisms remain poorly defined and treatment involves non-specific antibiotics. Here we show that SIBO based on duodenal aspirate culture reflects an overgrowth of anaerobes, does not correspond with patient symptoms, and may be a result of dietary preferences. Small intestinal microbial composition, on the other hand, is significantly altered in symptomatic patients and does not correspond with aspirate culture results. In a pilot interventional study we found that switching from a high fiber diet to a low fiber, high simple sugar diet triggered FGID-related symptoms and decreased small intestinal microbial diversity while increasing small intestinal permeability. Our findings demonstrate that characterizing small intestinal microbiomes in patients with gastrointestinal symptoms may allow a more targeted antibacterial or a diet-based approach to treatment.

    View details for PubMedID 31043597

  • Recovery of the Gut Microbiota after Antibiotics Depends on Host Diet, Community Context, and Environmental Reservoirs. Cell host & microbe Ng, K. M., Aranda-Díaz, A. n., Tropini, C. n., Frankel, M. R., Van Treuren, W. n., O'Laughlin, C. T., Merrill, B. D., Yu, F. B., Pruss, K. M., Oliveira, R. A., Higginbottom, S. K., Neff, N. F., Fischbach, M. A., Xavier, K. B., Sonnenburg, J. L., Huang, K. C. 2019; 26 (5): 650–65.e4

    Abstract

    Antibiotics alter microbiota composition and increase infection susceptibility. However, the generalizable effects of antibiotics on and the contribution of environmental variables to gut commensals remain unclear. To address this, we tracked microbiota dynamics with high temporal and taxonomic resolution during antibiotic treatment in a controlled murine system by isolating variables such as diet, treatment history, and housing co-inhabitants. Human microbiotas were remarkably resilient and recovered during antibiotic treatment, with transient dominance of resistant Bacteroides and taxa-asymmetric diversity reduction. In certain cases, in vitro sensitivities were not predictive of in vivo responses, underscoring the significance of host and community context. A fiber-deficient diet exacerbated microbiota collapse and delayed recovery. Species replacement through cross housing after ciprofloxacin treatment established resilience to a second treatment. Single housing drastically disrupted recovery, highlighting the importance of environmental reservoirs. Our findings highlight deterministic microbiota adaptations to perturbations and the translational potential for modulating diet, sanitation, and microbiota composition during antibiotics.

    View details for DOI 10.1016/j.chom.2019.10.011

    View details for PubMedID 31726029

  • In Vivo Wireless Sensors for Gut Microbiome Redox Monitoring. IEEE transactions on bio-medical engineering Baltsavias, S. n., Van Treuren, W. n., Weber, M. n., Charthad, J. n., Baker, S. n., Sonnenburg, J. L., Arbabian, A. n. 2019

    Abstract

    A perturbed gut microbiome has recently been linked with multiple disease processes, yet researchers currently lack tools that can provide in vivo, quantitative, and real-time insight into these processes and associated host-microbe interactions. We propose an in vivo wireless implant for monitoring gastrointestinal tract redox states using oxidation-reduction potentials (ORP). The implant is powered and conveniently interrogated via ultrasonic waves. We engineer the sensor electronics, electrodes, and encapsulation materials for robustness in vivo, and integrate them into an implant that endures autoclave sterilization and measures ORP for 12 days implanted in the cecum of a live rat. The presented implant platform paves the way for long-term experimental testing of biological hypotheses, offering new opportunities for understanding gut redox pathophysiology mechanisms, and facilitating translation to disease diagnosis and treatment applications.

    View details for DOI 10.1109/TBME.2019.2948575

    View details for PubMedID 31634824

  • Links between environment, diet, and the hunter-gatherer microbiome GUT MICROBES Fragiadakis, G. K., Smits, S. A., Sonnenburg, E. D., Van Treuren, W., Reid, G., Knight, R., Manjurano, A., Changalucha, J., Dominguez-Bello, M., Leach, J., Sonnenburg, J. L. 2019; 10 (2): 216–27
  • Considerations for best practices in studies of fiber or other dietary components and the intestinal microbiome AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM Klurfeld, D. M., Davis, C. D., Karp, R. W., Allen-Vercoe, E., Chang, E. B., Chassaing, B., Fahey, G. C., Hamaker, B. R., Holscher, H. D., Lampe, J. W., Marette, A., Martens, E., O'Keefe, S. J., Rose, D. J., Saarela, M., Schneeman, B. O., Slavin, J. L., Sonnenburg, J. L., Swanson, K. S., Wu, G. D., Lynch, C. J. 2018; 315 (6): E1087–E1097

    Abstract

    A two-day workshop organized by NIH and USDA included 16 presentations focused on the role of diet in alterations of the human gastrointestinal microbiome, primarily that of the colon. Although thousands of projects have been funded by United States federal funding agencies to study the intestinal microbiome of humans and a variety of animal models, only a minority address dietary effects and a small subset are described in sufficient detail to allow reproduction of a study. While there are standards being developed for many aspects of microbiome studies such as sample collection, nucleic acid extraction, data handling, etc., none have been proposed for the dietary component. It is important to the research enterprise to foster both rigor in design and reproducibility of published studies. Speakers addressed the influence of the structure of fermentable carbohydrate on the microbiota, the variables to consider in design of studies using animals, in vitro models, and human subjects. For all types of studies, strengths and weaknesses of various designs were highlighted and for human studies, comparisons between controlled feeding and observational designs were discussed. In the absence of clearly superior dietary approaches for specific research questions, the main recommendation is to describe dietary ingredients and treatments in as much detail as possible to allow reproduction by other scientists.

    View details for PubMedID 30130151

  • A Microbiota Assimilation. Cell metabolism Sonnenburg, J., Sonnenburg, E. 2018; 28 (5): 675–77

    Abstract

    While the gut microbiota's malleability makes it highly responsive to our environment, it also renders it susceptible to rapid selection by factors associated with an industrialized lifestyle. Recently, in Cell, Vangay etal. (2018) have tracked and revealed rapid and profound changes in the gut community of immigrants to one that resembles long-term residents of the U.S.

    View details for PubMedID 30403987

  • Clostridioides difficile uses amino acids associated with gut microbial dysbiosis in a subset of patients with diarrhea. Science translational medicine Battaglioli, E. J., Hale, V. L., Chen, J., Jeraldo, P., Ruiz-Mojica, C., Schmidt, B. A., Rekdal, V. M., Till, L. M., Huq, L., Smits, S. A., Moor, W. J., Jones-Hall, Y., Smyrk, T., Khanna, S., Pardi, D. S., Grover, M., Patel, R., Chia, N., Nelson, H., Sonnenburg, J. L., Farrugia, G., Kashyap, P. C. 2018; 10 (464)

    Abstract

    The gut microbiota plays a critical role in pathogen defense. Studies using antibiotic-treated mice reveal mechanisms that increase susceptibility to Clostridioides difficile infection (CDI), but risk factors associated with CDI in humans extend beyond antibiotic use. Here, we studied the dysbiotic gut microbiota of a subset of patients with diarrhea and modeled the gut microbiota of these patients by fecal transplantation into germ-free mice. When challenged with C. difficile, the germ-free mice transplanted with fecal samples from patients with dysbiotic microbial communities showed increased gut amino acid concentrations and greater susceptibility to CDI. A C. difficile mutant that was unable to use proline as an energy source was unable to robustly infect germ-free mice transplanted with a dysbiotic or healthy human gut microbiota. Prophylactic dietary intervention using a low-proline or low-protein diet in germ-free mice colonized by a dysbiotic human gut microbiota resulted in decreased expansion of wild-type C. difficile after challenge, suggesting that amino acid availability might be important for CDI. Furthermore, a prophylactic fecal microbiota transplant in mice with dysbiosis reduced proline availability and protected the mice from CDI. Last, we identified clinical risk factors that could potentially predict gut microbial dysbiosis and thus greater susceptibility to CDI in a retrospective cohort of patients with diarrhea. Identifying at-risk individuals and reducing their susceptibility to CDI through gut microbiota-targeted therapies could be a new approach to preventing C. difficile infection in susceptible patients.

    View details for PubMedID 30355801

  • Links between environment, diet, and the hunter-gatherer microbiome. Gut microbes Fragiadakis, G. K., Smits, S. A., Sonnenburg, E. D., Van Treuren, W., Reid, G., Knight, R., Manjurano, A., Changalucha, J., Dominguez-Bello, M. G., Leach, J., Sonnenburg, J. L. 2018: 1–12

    Abstract

    The study of traditional populations provides a view of human-associated microbes unperturbed by industrialization, as well as a window into the microbiota that co-evolved with humans. Here we discuss our recent work characterizing the microbiota from the Hadza hunter-gatherers of Tanzania. We found seasonal shifts in bacterial taxa, diversity, and carbohydrate utilization by the microbiota. When compared to the microbiota composition from other populations around the world, the Hadza microbiota shares bacterial families with other traditional societies that are rare or absent from microbiotas of industrialized nations. We present additional observations from the Hadza microbiota and their lifestyle and environment, including microbes detected on hands, water, and animal sources, how the microbiota varies with sex and age, and the short-term effects of introducing agricultural products into the diet. In the context of our previously published findings and of these additional observations, we discuss a path forward for future work.

    View details for PubMedID 30118385

  • A Gut Commensal-Produced Metabolite Mediates Colonization Resistance to Salmonella Infection. Cell host & microbe Jacobson, A., Lam, L., Rajendram, M., Tamburini, F., Honeycutt, J., Pham, T., Van Treuren, W., Pruss, K., Stabler, S. R., Lugo, K., Bouley, D. M., Vilches-Moure, J. G., Smith, M., Sonnenburg, J. L., Bhatt, A. S., Huang, K. C., Monack, D. 2018

    Abstract

    The intestinal microbiota provides colonization resistance against pathogens, limiting pathogen expansion and transmission. These microbiota-mediated mechanisms were previously identified by observing loss of colonization resistance after antibiotic treatment or dietary changes, which severely disrupt microbiota communities. We identify a microbiota-mediated mechanism of colonization resistance against Salmonella enterica serovar Typhimurium (S. Typhimurium) by comparing high-complexity commensal communities with different levels of colonization resistance. Using inbred mouse strains with different infection dynamics and S. Typhimurium intestinal burdens, we demonstrate that Bacteroides species mediate colonization resistance against S. Typhimurium by producing the short-chain fatty acid propionate. Propionate directly inhibits pathogen growth invitro by disrupting intracellular pH homeostasis, and chemically increasing intestinal propionate levels protects mice from S.Typhimurium. In addition, administering susceptible mice Bacteroides, but not a propionate-production mutant, confers resistance to S. Typhimurium. This work provides mechanistic understanding into the role of individualized microbial communities in host-to-host variability of pathogen transmission.

    View details for PubMedID 30057174

  • Gut Microbiota-Produced Tryptamine Activates an Epithelial G-Protein-Coupled Receptor to Increase Colonic Secretion CELL HOST & MICROBE Bhattarai, Y., Williams, B. B., Battaglioli, E. J., Whitaker, W. R., Till, L., Grover, M., Linden, D. R., Akiba, Y., Kandimalla, K. K., Zachos, N. C., Kaunitz, J. D., Sonnenburg, J. L., Fischbach, M. A., Farrugia, G., Kashyap, P. C. 2018; 23 (6): 775-+

    Abstract

    Tryptamine, a tryptophan-derived monoamine similar to 5-hydroxytryptamine (5-HT), is produced by gut bacteria and is abundant in human and rodent feces. However, the physiologic effect of tryptamine in the gastrointestinal (GI) tract remains unknown. Here, we show that the biological effects of tryptamine are mediated through the 5-HT4 receptor (5-HT4R), a G-protein-coupled receptor (GPCR) uniquely expressed in the colonic epithelium. Tryptamine increases both ionic flux across the colonic epithelium and fluid secretion in colonoids from germ-free (GF) and humanized (ex-GF colonized with human stool) mice, consistent with increased intestinal secretion. The secretory effect of tryptamine is dependent on 5-HT4R activation and is blocked by 5-HT4R antagonist and absent in 5-HT4R-/- mice. GF mice colonized by Bacteroides thetaiotaomicron engineered to produce tryptamine exhibit accelerated GI transit. Our study demonstrates an aspect of host physiology under control of a bacterial metabolite that can be exploited as a therapeutic modality. VIDEO ABSTRACT.

    View details for PubMedID 29902441

    View details for PubMedCentralID PMC6055526

  • Genetic Variation of the SusC/SusD Homologs from a Polysaccharide Utilization Locus Underlies Divergent Fructan Specificities and Functional Adaptation in Bacteroides thetaiotaomicron Strains. mSphere Joglekar, P., Sonnenburg, E. D., Higginbottom, S. K., Earle, K. A., Morland, C., Shapiro-Ward, S., Bolam, D. N., Sonnenburg, J. L. 2018; 3 (3)

    Abstract

    Genomic differences between gut-resident bacterial strains likely underlie significant interindividual variation in microbiome function. Traditional methods of determining community composition, such as 16S rRNA gene amplicon sequencing, fail to capture this functional diversity. Metagenomic approaches are a significant step forward in identifying strain-level sequence variants; however, given the current paucity of biochemical information, they too are limited to mainly low-resolution and incomplete functional predictions. Using genomic, biochemical, and molecular approaches, we identified differences in the fructan utilization profiles of two closely related Bacteroides thetaiotaomicron strains. B.thetaiotaomicron 8736 (Bt-8736) contains a fructan polysaccharide utilization locus (PUL) with a divergent susC/susD homolog gene pair that enables it to utilize inulin, differentiating this strain from other characterized Bt strains. Transfer of the distinct pair of susC/susD genes from Bt-8736 into the noninulin using type strain B.thetaiotaomicronVPI-5482 resulted in inulin use by the recipient strain, Bt(8736-2). The presence of the divergent susC/susD gene pair alone enabled the hybrid Bt(8736-2) strain to outcompete the wild-type strain in vivo in mice fed an inulin diet. Further, we discovered that the susC/susD homolog gene pair facilitated import of inulin into the periplasm without surface predigestion by an endo-acting enzyme, possibly due to the short average chain length of inulin compared to many other polysaccharides. Our data builds upon recent reports of dietary polysaccharide utilization mechanisms found in members of the Bacteroides genus and demonstrates how the acquisition of two genes can alter the functionality and success of a strain within the gut.IMPORTANCE Dietary polysaccharides play a dominant role in shaping the composition and functionality of our gut microbiota. Dietary interventions using these microbiota-accessible carbohydrates (MACs) serve as a promising tool for manipulating the gut microbial community. However, our current gap in knowledge regarding microbial metabolic pathways that are involved in the degradation of these MACs has made the design of rational interventions difficult. The issue is further complicated by the diversity of pathways observed for the utilization of similar MACs, even in closely related microbial strains. Our current work focuses on divergent fructan utilization pathways in two closely related B.thetaiotaomicron strains and provides an integrated approach to characterize the molecular basis for strain-level functional differences.

    View details for PubMedID 29794055

  • Microbiota-accessible carbohydrates suppress Clostridium difficile infection in a murine model. Nature microbiology Hryckowian, A. J., Van Treuren, W. n., Smits, S. A., Davis, N. M., Gardner, J. O., Bouley, D. M., Sonnenburg, J. L. 2018

    Abstract

    Clostridium difficile is an opportunistic diarrhoeal pathogen, and C. difficile infection (CDI) represents a major health care concern, causing an estimated 15,000 deaths per year in the United States alone 1 . Several enteric pathogens, including C. difficile, leverage inflammation and the accompanying microbial dysbiosis to thrive in the distal gut 2 . Although diet is among the most powerful available tools for affecting the health of humans and their relationship with their microbiota, investigation into the effects of diet on CDI has been limited. Here, we show in mice that the consumption of microbiota-accessible carbohydrates (MACs) found in dietary plant polysaccharides has a significant effect on CDI. Specifically, using a model of antibiotic-induced CDI that typically resolves within 12 days of infection, we demonstrate that MAC-deficient diets perpetuate CDI. We show that C. difficile burdens are suppressed through the addition of either a diet containing a complex mixture of MACs or a simplified diet containing inulin as the sole MAC source. We show that switches between these dietary conditions are coincident with changes to microbiota membership, its metabolic output and C. difficile-mediated inflammation. Together, our data demonstrate the outgrowth of MAC-utilizing taxa and the associated end products of MAC metabolism, namely, the short-chain fatty acids acetate, propionate and butyrate, are associated with decreased C. difficile fitness despite increased C. difficile toxin expression in the gut. Our findings, when placed into the context of the known fibre deficiencies of a human Western diet, provide rationale for pursuing MAC-centric dietary strategies as an alternate line of investigation for mitigating CDI.

    View details for PubMedID 29686297

  • Single-cell transcriptomics of 20 mouse organs creates a Tabula Muris. Nature 2018; 562 (7727): 367–72

    Abstract

    Here we present a compendium of single-cell transcriptomic data from the model organism Mus musculus that comprises more than 100,000 cells from 20 organs and tissues. These data represent a new resource for cell biology, reveal gene expression in poorly characterized cell populations and enable the direct and controlled comparison of gene expression in cell types that are shared between tissues, such as T lymphocytes and endothelial cells from different anatomical locations. Two distinct technical approaches were used for most organs: one approach, microfluidic droplet-based 3'-end counting, enabled the survey of thousands of cells at relatively low coverage, whereas the other, full-length transcript analysis based on fluorescence-activated cell sorting, enabled the characterization of cell types with high sensitivity and coverage. The cumulative data provide the foundation for an atlas of transcriptomic cell biology.

    View details for DOI 10.1038/s41586-018-0590-4

    View details for PubMedID 30283141

  • Dynamic Light Scattering Microrheology Reveals Multiscale Viscoelasticity of Polymer Gels and Precious Biological Materials ACS CENTRAL SCIENCE Krajina, B. A., Tropini, C., Zhu, A., DiGiacomo, P., Sonnenburg, J. L., Heilshorn, S. C., Spakowitz, A. J. 2017; 3 (12): 1294–1303

    Abstract

    The development of experimental techniques capable of probing the viscoelasticity of soft materials over a broad range of time scales is essential to uncovering the physics that governs their behavior. In this work, we develop a microrheology technique that requires only 12 μL of sample and is capable of resolving dynamic behavior ranging in time scales from 10-6 to 10 s. Our approach, based on dynamic light scattering in the single-scattering limit, enables the study of polymer gels and other soft materials over a vastly larger hierarchy of time scales than macrorheology measurements. Our technique captures the viscoelastic modulus of polymer hydrogels with a broad range of stiffnesses from 10 to 104 Pa. We harness these capabilities to capture hierarchical molecular relaxations in DNA and to study the rheology of precious biological materials that are impractical for macrorheology measurements, including decellularized extracellular matrices and intestinal mucus. The use of a commercially available benchtop setup that is already available to a variety of soft matter researchers renders microrheology measurements accessible to a broader range of users than existing techniques, with the potential to reveal the physics that underlies complex polymer hydrogels and biological materials.

    View details for PubMedID 29296670

    View details for PubMedCentralID PMC5746858

  • The Gut Microbiome: Connecting Spatial Organization to Function CELL HOST & MICROBE Tropini, C., Earle, K. A., Huang, K. C., Sonnenburg, J. L. 2017; 21 (4): 433-442

    Abstract

    The first rudimentary evidence that the human body harbors a microbiota hinted at the complexity of host-associated microbial ecosystems. Now, almost 400 years later, a renaissance in the study of microbiota spatial organization, driven by coincident revolutions in imaging and sequencing technologies, is revealing functional relationships between biogeography and health, particularly in the vertebrate gut. In this Review, we present our current understanding of principles governing the localization of intestinal bacteria, and spatial relationships between bacteria and their hosts. We further discuss important emerging directions that will enable progressing from the inherently descriptive nature of localization and -omics technologies to provide functional, quantitative, and mechanistic insight into this complex ecosystem.

    View details for DOI 10.1016/j.chom.2017.03.010

    View details for Web of Science ID 000398896100005

    View details for PubMedID 28407481

  • Commensal Microbes and Hair Follicle Morphogenesis Coordinately Drive Treg Migration into Neonatal Skin CELL HOST & MICROBE Scharschmidt, T. C., Vasquez, K. S., Pauli, M. L., Leitner, E. G., Chu, K., Truong, H., Lowe, M. M., Rodriguez, R. S., Ali, N., Laszik, Z. G., Sonnenburg, J. L., Millar, S. E., Rosenblum, M. D. 2017; 21 (4): 467-?

    Abstract

    Regulatory T cells (Tregs) are required to establish immune tolerance to commensal microbes. Tregs accumulate abruptly in the skin during a defined window of postnatal tissue development. However, the mechanisms mediating Treg migration to neonatal skin are unknown. Here we show that hair follicle (HF) development facilitates the accumulation of Tregs in neonatal skin and that upon skin entry these cells localize to HFs, a primary reservoir for skin commensals. Further, germ-free neonates had reduced skin Tregs indicating that commensal microbes augment Treg accumulation. We identified Ccl20 as a HF-derived, microbiota-dependent chemokine and found its receptor, Ccr6, to be preferentially expressed by Tregs in neonatal skin. The Ccl20-Ccr6 pathway mediated Treg migration in vitro and in vivo. Thus, HF morphogenesis, commensal microbe colonization, and local chemokine production work in concert to recruit Tregs into neonatal skin, thereby establishing this tissue Treg niche early in life.

    View details for DOI 10.1016/j.chom.2017.03.001

    View details for PubMedID 28343820

  • The emerging metabolic view of Clostridium difficile pathogenesis. Current opinion in microbiology Hryckowian, A. J., Pruss, K. M., Sonnenburg, J. L. 2016; 35: 42-47

    Abstract

    It is widely accepted that Clostridium difficile exploits dysbiosis and leverages inflammation to thrive in the gut environment, where it can asymptomatically colonize humans or cause a toxin-mediated disease ranging in severity from frequent watery diarrhea to pseudomembranous colitis or toxic megacolon. Here, we synthesize recent findings from the gut microbiota and enteric pathogenesis fields to inform the next steps toward a better understanding of C. difficile infection (CDI). In this review, we present a model in which the lifestyle of C. difficile is dictated by the metabolic state of the distal gut ecosystem. Contributions by C. difficile (specifically the production and action of the large glycosylating toxins TcdA and TcdB), the microbiota, and the host dictate whether the gut environment is supportive to the pathogen. Mechanistic, metabolic pathway-focused approaches encompassing the roles of all of these players are helping to elucidate the molecular ecology of the distal gut underlying a diseased or healthy ecosystem. A new generation of therapeutic strategies that are more targeted (and palatable) than fecal microbiota transplants or broad-spectrum antibiotics will be fueled by insight into the interspecies (host-microbe and microbe-microbe) interactions that differentiate healthy from pathogen-infested microbiotas.

    View details for DOI 10.1016/j.mib.2016.11.006

    View details for PubMedID 27997854

  • Modulation of a Circulating Uremic Solute via Rational Genetic Manipulation of the Gut Microbiota CELL HOST & MICROBE Devlin, A. S., Marcobal, A., Dodd, D., Nayfach, S., Plummer, N., Meyer, T., Pollard, K. S., Sonnenburg, J. L., Fischbach, M. A. 2016; 20 (6): 709-715

    Abstract

    Renal disease is growing in prevalence and has striking co-morbidities with metabolic and cardiovascular disease. Indoxyl sulfate (IS) is a toxin that accumulates in plasma when kidney function declines and contributes to the progression of chronic kidney disease. IS derives exclusively from the gut microbiota. Bacterial tryptophanases convert tryptophan to indole, which is absorbed and modified by the host to produce IS. Here, we identify a widely distributed family of tryptophanases in the gut commensal Bacteroides and find that deleting this gene eliminates the production of indole in vitro. By altering the status or abundance of the Bacteroides tryptophanase, we can modulate IS levels in gnotobiotic mice and in the background of a conventional murine gut community. Our results demonstrate that it is possible to control host IS levels by targeting the microbiota and suggest a possible strategy for treating renal disease.

    View details for DOI 10.1016/j.chom.2016.10.021

    View details for Web of Science ID 000392843500008

    View details for PubMedID 27916477

    View details for PubMedCentralID PMC5159218

  • Correlated gene expression encoding serotonin (5-HT) receptor 4 and 5-HT transporter in proximal colonic segments of mice across different colonization states and sexes. Neurogastroenterology and motility Reigstad, C. S., Linden, D. R., Szurszewski, J. H., Sonnenburg, J. L., Farrugia, G., Kashyap, P. C. 2016; 28 (9): 1443-1448

    Abstract

    The production and handling of serotonin (5-HT) is an important determinant of colonic motility and has been reported to be altered in gastrointestinal (GI) disorders such as irritable bowel syndrome (IBS). Recent studies suggest that the intestinal microbiota and sex of the host can influence expression of genes involved in 5-HT biosynthesis and signaling. While expression of genes in serotonergic pathways has been shown to be variable, it remains unclear whether genes within this pathway are coregulated. As a first step in that direction, we investigated potential correlations in relative mRNA expression of serotonergic genes, in the proximal colon isolated from male and female mice in different states of microbial association: germ-free (GF), humanized (ex-germ-free colonized with human gut microbiota, HM), and conventionally raised (CR) mice. Among the 10 pairwise comparisons conducted between five serotonergic transcripts, Tph1, Chga, Maoa, Slc6a4, and Htr4, we found a strong, positive correlation between colonic expression of Slc6a4 and Htr4 across different colonization states and sexes. We also identified a positive correlation between the expression of Tph1 and Chga; however, there were no correlations observed between any other tested pair of 5-HT-related transcripts. These data suggest that correlated expression of Slc6a4 and Htr4 likely involves coregulation of genes located on different chromosomes which modulate serotonergic activity in the gut. Further work will need to be done to understand the pathways and cell types responsible for this correlated expression, given the important role of 5-HT in gastrointestinal physiology.

    View details for DOI 10.1111/nmo.12840

    View details for PubMedID 27072889

    View details for PubMedCentralID PMC5008845

  • Individualized Responses of Gut Microbiota to Dietary Intervention Modeled in Humanized Mice. mSystems Smits, S. A., Marcobal, A., Higginbottom, S., Sonnenburg, J. L., Kashyap, P. C. 2016; 1 (5)

    Abstract

    Diet plays an important role in shaping the structure and function of the gut microbiota. The microbes and microbial products in turn can influence various aspects of host physiology. One promising route to affect host function and restore health is by altering the gut microbiome using dietary intervention. The individuality of the microbiome may pose a significant challenge, so we sought to determine how different microbiotas respond to the same dietary intervention in a controlled setting. We modeled gut microbiotas from three healthy donors in germfree mice and defined compositional and functional alteration following a change in dietary microbiota-accessible carbohydrates (MACs). The three gut communities exhibited responses that differed markedly in magnitude and in the composition of microbiota-derived metabolites. Adjustments in community membership did not correspond to the magnitude of changes in the microbial metabolites, highlighting potential challenges in predicting functional responses from compositional data and the need to assess multiple microbiota parameters following dietary interventions. IMPORTANCE Dietary modification has long been used empirically to modify symptoms in inflammatory bowel disease, irritable bowel syndrome, and a diverse group of diseases with gastrointestinal symptoms. There is both anecdotal and scientific evidence to suggest that individuals respond quite differently to similar dietary changes, and the highly individualized nature of the gut microbiota makes it a prime candidate for these differences. To overcome the typical confounding factors of human dietary interventions, here we employ ex-germfree mice colonized by microbiotas of three different humans to test how different microbiotas respond to a defined change in carbohydrate content of diet by measuring changes in microbiota composition and function using marker gene-based next-generation sequencing and metabolomics. Our findings suggest that the same diet has very different effects on each microbiota's membership and function, which may in turn explain interindividual differences in response to a dietary ingredient.

    View details for PubMedID 27822551

  • Host-Microbiota Interactions in the Pathogenesis of Antibiotic-Associated Diseases CELL REPORTS Lichtman, J. S., Ferreyra, J. A., Ng, K. M., Smits, S. A., Sonnenburg, J. L., Elias, J. E. 2016; 14 (5): 1049-1061

    Abstract

    Improved understanding of the interplay between host and microbes stands to illuminate new avenues for disease diagnosis, treatment, and prevention. Here, we provide a high-resolution view of the dynamics between host and gut microbiota during antibiotic-induced intestinal microbiota depletion, opportunistic Salmonella typhimurium and Clostridium difficile pathogenesis, and recovery from these perturbed states in a mouse model. Host-centric proteome and microbial community profiles provide a nuanced longitudinal view, revealing the interdependence between host and microbiota in evolving dysbioses. Time- and condition-specific molecular and microbial signatures are evident and clearly distinguished from pathogen-independent inflammatory fingerprints. Our data reveal that mice recovering from antibiotic treatment or C. difficile infection retain lingering signatures of inflammation, despite compositional normalization of the microbiota, and host responses could be rapidly and durably relieved through fecal transplant. These experiments demonstrate insights that emerge from the combination of these orthogonal, untargeted approaches to the gastrointestinal ecosystem.

    View details for DOI 10.1016/j.celrep.2016.01.009

    View details for Web of Science ID 000369616100009

    View details for PubMedID 26832403

  • Nutrition: A personal forecast. Nature Sonnenburg, E. D., Sonnenburg, J. L. 2015; 528 (7583): 484-486

    View details for DOI 10.1038/528484a

    View details for PubMedID 26701049

  • Your gut microbiome, deconstructed. Nature biotechnology Dodd, D., Tropini, C., Sonnenburg, J. L. 2015; 33 (12): 1238-1240

    View details for DOI 10.1038/nbt.3431

    View details for PubMedID 26650010

  • A small-molecule antivirulence agent for treating Clostridium difficile infection. Science translational medicine Bender, K. O., Garland, M., Ferreyra, J. A., Hryckowian, A. J., Child, M. A., Puri, A. W., Solow-Cordero, D. E., Higginbottom, S. K., Segal, E., Banaei, N., Shen, A., Sonnenburg, J. L., Bogyo, M. 2015; 7 (306): 306ra148-?

    Abstract

    Clostridium difficile infection (CDI) is a worldwide health threat that is typically triggered by the use of broad-spectrum antibiotics, which disrupt the natural gut microbiota and allow this Gram-positive anaerobic pathogen to thrive. The increased incidence and severity of disease coupled with decreased response, high recurrence rates, and emergence of multiple antibiotic-resistant strains have created an urgent need for new therapies. We describe pharmacological targeting of the cysteine protease domain (CPD) within the C. difficile major virulence factor toxin B (TcdB). Through a targeted screen with an activity-based probe for this protease domain, we identified a number of potent CPD inhibitors, including one bioactive compound, ebselen, which is currently in human clinical trials for a clinically unrelated indication. This drug showed activity against both major virulence factors, TcdA and TcdB, in biochemical and cell-based studies. Treatment in a mouse model of CDI that closely resembles the human infection confirmed a therapeutic benefit in the form of reduced disease pathology in host tissues that correlated with inhibition of the release of the toxic glucosyltransferase domain (GTD). Our results show that this non-antibiotic drug can modulate the pathology of disease and therefore could potentially be developed as a therapeutic for the treatment of CDI.

    View details for DOI 10.1126/scitranslmed.aac9103

    View details for PubMedID 26400909

  • A small-molecule antivirulence agent for treating Clostridium difficile infection SCIENCE TRANSLATIONAL MEDICINE Bender, K. O., Garland, M., Ferreyra, J. A., Hryckowian, A. J., Child, M. A., Puri, A. W., Solow-Cordero, D. E., Higginbottom, S. K., Segal, E., Banaei, N., Shen, A., Sonnenburg, J. L., Bogyo, M. 2015; 7 (306)

    Abstract

    Clostridium difficile infection (CDI) is a worldwide health threat that is typically triggered by the use of broad-spectrum antibiotics, which disrupt the natural gut microbiota and allow this Gram-positive anaerobic pathogen to thrive. The increased incidence and severity of disease coupled with decreased response, high recurrence rates, and emergence of multiple antibiotic-resistant strains have created an urgent need for new therapies. We describe pharmacological targeting of the cysteine protease domain (CPD) within the C. difficile major virulence factor toxin B (TcdB). Through a targeted screen with an activity-based probe for this protease domain, we identified a number of potent CPD inhibitors, including one bioactive compound, ebselen, which is currently in human clinical trials for a clinically unrelated indication. This drug showed activity against both major virulence factors, TcdA and TcdB, in biochemical and cell-based studies. Treatment in a mouse model of CDI that closely resembles the human infection confirmed a therapeutic benefit in the form of reduced disease pathology in host tissues that correlated with inhibition of the release of the toxic glucosyltransferase domain (GTD). Our results show that this non-antibiotic drug can modulate the pathology of disease and therefore could potentially be developed as a therapeutic for the treatment of CDI.

    View details for DOI 10.1126/scitranslmed.aac9103

    View details for Web of Science ID 000365232600002

    View details for PubMedID 26400909

  • Monitoring host responses to the gut microbiota ISME JOURNAL Lichtman, J. S., Sonnenburg, J. L., Elias, J. E. 2015; 9 (9): 1908-1915

    Abstract

    The gastrointestinal (GI) ecosystem is increasingly understood to be a fundamental component of health, and has been identified as a new focal point for diagnosing, correcting and preventing countless disorders. Shotgun DNA sequencing has emerged as the dominant technology for determining the genetic and microbial composition of the gut microbiota. This technology has linked microbiota dysbioses to numerous GI diseases including inflammatory bowel disease, obesity and allergy, and to non-GI diseases like autism and depression. The importance of establishing causality in the deterioration of the host-microbiota relationship is well appreciated; however, discovery of candidate molecules and pathways that underlie mechanisms remains a major challenge. Targeted approaches, transcriptional assays, cytokine panels and imaging analyses, applied to animals, have yielded important insight into host responses to the microbiota. However, non-invasive, hypothesis-independent means of measuring host responses in humans are necessary to keep pace with similarly unbiased sequencing efforts that monitor microbes. Mass spectrometry-based proteomics has served this purpose in many other fields, but stool proteins exist in such diversity and dynamic range as to overwhelm conventional proteomics technologies. Focused analysis of host protein secretion into the gut lumen and monitoring proteome-level dynamics in stool provides a tractable route toward non-invasively evaluating dietary, microbial, surgical or pharmacological intervention efficacies. This review is intended to guide GI biologists and clinicians through the methods currently used to elucidate host responses in the gut, with a specific focus on mass spectrometry-based shotgun proteomics applied to the study of host protein dynamics within the GI ecosystem.The ISME Journal advance online publication, 9 June 2015; doi:10.1038/ismej.2015.93.

    View details for DOI 10.1038/ismej.2015.93

    View details for Web of Science ID 000360019500002

  • Metabolome progression during early gut microbial colonization of gnotobiotic mice SCIENTIFIC REPORTS Marcobal, A., Yusufaly, T., Higginbottom, S., Snyder, M., Sonnenburg, J. L., Mias, G. I. 2015; 5

    Abstract

    The microbiome has been implicated directly in host health, especially host metabolic processes and development of immune responses. These are particularly important in infants where the gut first begins being colonized, and such processes may be modeled in mice. In this investigation we follow longitudinally the urine metabolome of ex-germ-free mice, which are colonized with two bacterial species, Bacteroides thetaiotaomicron and Bifidobacterium longum. High-throughput mass spectrometry profiling of urine samples revealed dynamic changes in the metabolome makeup, associated with the gut bacterial colonization, enabled by our adaptation of non-linear time-series analysis to urine metabolomics data. Results demonstrate both gradual and punctuated changes in metabolite production and that early colonization events profoundly impact the nature of small molecules circulating in the host. The identified small molecules are implicated in amino acid and carbohydrate metabolic processes, and offer insights into the dynamic changes occurring during the colonization process, using high-throughput longitudinal methodology.

    View details for DOI 10.1038/srep11589

    View details for Web of Science ID 000357041700001

    View details for PubMedID 26118551

    View details for PubMedCentralID PMC4484351

  • Gut microbes promote colonic serotonin production through an effect of short-chain fatty acids on enterochromaffin cells. FASEB journal Reigstad, C. S., Salmonson, C. E., Rainey, J. F., Szurszewski, J. H., Linden, D. R., Sonnenburg, J. L., Farrugia, G., Kashyap, P. C. 2015; 29 (4): 1395-1403

    Abstract

    Gut microbiota alterations have been described in several diseases with altered gastrointestinal (GI) motility, and awareness is increasing regarding the role of the gut microbiome in modulating GI function. Serotonin [5-hydroxytryptamine (5-HT)] is a key regulator of GI motility and secretion. To determine the relationship among gut microbes, colonic contractility, and host serotonergic gene expression, we evaluated mice that were germ-free (GF) or humanized (HM; ex-GF colonized with human gut microbiota). 5-HT reduced contractile duration in both GF and HM colons. Microbiota from HM and conventionally raised (CR) mice significantly increased colonic mRNAs Tph1 [(tryptophan hydroxylase) 1, rate limiting for mucosal 5-HT synthesis; P < 0.01] and chromogranin A (neuroendocrine secretion; P < 0.01), with no effect on monoamine oxidase A (serotonin catabolism), serotonin receptor 5-HT4, or mouse serotonin transporter. HM and CR mice also had increased colonic Tph1 protein (P < 0.05) and 5-HT concentrations (GF, 17 ± 3 ng/mg; HM, 25 ± 2 ng/mg; and CR, 35 ± 3 ng/mg; P < 0.05). Enterochromaffin (EC) cell numbers (cells producing 5-HT) were unchanged. Short-chain fatty acids (SCFAs) promoted TPH1 transcription in BON cells (human EC cell model). Thus, gut microbiota acting through SCFAs are important determinants of enteric 5-HT production and homeostasis.-Reigstad, C. S., Salmonson, C. E., Rainey, III, J. F., Szurszewski, J. H., Linden, D. R., Sonnenburg, J. L., Farrugia, G., Kashyap, P. C. Gut microbes promote colonic serotonin production through an effect of short-chain fatty acids on enterochromaffin cells.

    View details for DOI 10.1096/fj.14-259598

    View details for PubMedID 25550456

  • Microbiome engineering. Nature Sonnenburg, J. L. 2015; 518 (7540): S10-?

    View details for DOI 10.1038/518S10a

    View details for PubMedID 25715274

  • Metabolome progression during early gut microbial colonization of gnotobiotic mice. Scientific reports Marcobal, A., Yusufaly, T., Higginbottom, S., Snyder, M., Sonnenburg, J. L., Mias, G. I. 2015; 5: 11589-?

    Abstract

    The microbiome has been implicated directly in host health, especially host metabolic processes and development of immune responses. These are particularly important in infants where the gut first begins being colonized, and such processes may be modeled in mice. In this investigation we follow longitudinally the urine metabolome of ex-germ-free mice, which are colonized with two bacterial species, Bacteroides thetaiotaomicron and Bifidobacterium longum. High-throughput mass spectrometry profiling of urine samples revealed dynamic changes in the metabolome makeup, associated with the gut bacterial colonization, enabled by our adaptation of non-linear time-series analysis to urine metabolomics data. Results demonstrate both gradual and punctuated changes in metabolite production and that early colonization events profoundly impact the nature of small molecules circulating in the host. The identified small molecules are implicated in amino acid and carbohydrate metabolic processes, and offer insights into the dynamic changes occurring during the colonization process, using high-throughput longitudinal methodology.

    View details for DOI 10.1038/srep11589

    View details for PubMedID 26118551

    View details for PubMedCentralID PMC4484351

  • Gut Microbiota-Produced Succinate Promotes C-difficile Infection after Antibiotic Treatment or Motility Disturbance CELL HOST & MICROBE Ferreyra, J. A., Wu, K. J., Hryckowian, A. J., Bouley, D. M., Weimer, B. C., Sonnenburg, J. L. 2014; 16 (6): 770-777

    Abstract

    Clostridium difficile is a leading cause of antibiotic-associated diarrhea. The mechanisms underlying C. difficile expansion after microbiota disturbance are just emerging. We assessed the gene expression profile of C. difficile within the intestine of gnotobiotic mice to identify genes regulated in response to either dietary or microbiota compositional changes. In the presence of the gut symbiont Bacteroides thetaiotaomicron, C. difficile induces a pathway that metabolizes the microbiota fermentation end-product succinate to butyrate. The low concentration of succinate present in the microbiota of conventional mice is transiently elevated upon antibiotic treatment or chemically induced intestinal motility disturbance, and C. difficile exploits this succinate spike to expand in the perturbed intestine. A C. difficile mutant compromised in succinate utilization is at a competitive disadvantage during these perturbations. Understanding the metabolic mechanisms involved in microbiota-C. difficile interactions may help to identify approaches for the treatment and prevention of C. difficile-associated diseases.

    View details for DOI 10.1016/j.chom.2014.11.003

    View details for Web of Science ID 000346211100010

    View details for PubMedID 25498344

  • Editorial Overview: Insights into Molecular Mechanisms of Microbiota JOURNAL OF MOLECULAR BIOLOGY Martens, E. C., Sonnenburg, J. L., Reiman, D. A. 2014; 426 (23): 3827–29

    View details for PubMedID 25218944

  • Reprograming of gut microbiome energy metabolism by the FUT2 Crohn's disease risk polymorphism ISME JOURNAL Tong, M., McHardy, I., Ruegger, P., Goudarzi, M., Kashyap, P. C., Haritunians, T., Li, X., Graeber, T. G., Schwager, E., Huttenhower, C., Fornace, A. J., Sonnenburg, J. L., McGovern, D. P., Borneman, J., Braun, J. 2014; 8 (11): 2193-2206

    Abstract

    Fucosyltransferase 2 (FUT2) is an enzyme that is responsible for the synthesis of the H antigen in body fluids and on the intestinal mucosa. The H antigen is an oligosaccharide moiety that acts as both an attachment site and carbon source for intestinal bacteria. Non-secretors, who are homozygous for the loss-of-function alleles of FUT2 gene (sese), have increased susceptibility to Crohn's disease (CD). To characterize the effect of FUT2 polymorphism on the mucosal ecosystem, we profiled the microbiome, meta-proteome and meta-metabolome of 75 endoscopic lavage samples from the cecum and sigmoid of 39 healthy subjects (12 SeSe, 18 Sese and 9 sese). Imputed metagenomic analysis revealed perturbations of energy metabolism in the microbiome of non-secretor and heterozygote individuals, notably the enrichment of carbohydrate and lipid metabolism, cofactor and vitamin metabolism and glycan biosynthesis and metabolism-related pathways, and the depletion of amino-acid biosynthesis and metabolism. Similar changes were observed in mice bearing the FUT2(-/-) genotype. Metabolomic analysis of human specimens revealed concordant as well as novel changes in the levels of several metabolites. Human metaproteomic analysis indicated that these functional changes were accompanied by sub-clinical levels of inflammation in the local intestinal mucosa. Therefore, the colonic microbiota of non-secretors is altered at both the compositional and functional levels, affecting the host mucosal state and potentially explaining the association of FUT2 genotype and CD susceptibility.

    View details for DOI 10.1038/ismej.2014.64

    View details for Web of Science ID 000344454000004

  • The Enteric Two-Step: nutritional strategies of bacterial pathogens within the gut CELLULAR MICROBIOLOGY Ferreyra, J. A., Ng, K. M., Sonnenburg, J. L. 2014; 16 (7): 993-1003

    Abstract

    The gut microbiota is a dense and diverse microbial community governed by dynamic microbe-microbe and microbe-host interactions, the status of which influences whether enteric pathogens can cause disease. Here we review recent insights into the key roles that nutrients play in bacterial pathogen exploitation of the gut microbial ecosystem. We synthesize recent findings to support a five-stage model describing the transition between a healthy microbiota and one dominated by a pathogen and disease. Within this five-stage model, two stages are critical to the pathogen: (i) an initial expansion phase that must occur in the absence of pathogen-induced inflammation, followed by (ii) pathogen-promoting physiological changes such as inflammation and diarrhoea. We discuss how this emerging paradigm of pathogen life within the lumen of the gut is giving rise to novel therapeutic strategies.

    View details for DOI 10.1111/cmi.12300

    View details for Web of Science ID 000337667600002

  • The Enteric Two-Step: nutritional strategies of bacterial pathogens within the gut. Cellular microbiology Ferreyra, J. A., Ng, K. M., Sonnenburg, J. L. 2014

    Abstract

    The gut microbiota is a dense and diverse microbial community governed by dynamic microbe-microbe and microbe-host interactions, the status of which influences whether enteric pathogens can cause disease. Here we review recent insights into the key roles that nutrients play in bacterial pathogen exploitation of the gut microbial ecosystem. We synthesize recent findings to support a five-stage model describing the transition between a healthy microbiota and one dominated by a pathogen and disease. Within this five-stage model, two stages are critical to the pathogen: (i) an initial expansion phase that must occur in the absence of pathogen-induced inflammation, followed by (ii) pathogen-promoting physiological changes such as inflammation and diarrhoea. We discuss how this emerging paradigm of pathogen life within the lumen of the gut is giving rise to novel therapeutic strategies.

    View details for DOI 10.1111/cmi.12300

    View details for PubMedID 24720567

  • Rapid evolution of binding specificities and expression patterns of inhibitory CD33-related Siglecs in primates FASEB JOURNAL Padler-Karavani, V., Hurtado-Ziola, N., Chang, Y., Sonnenburg, J. L., Ronaghy, A., Yu, H., Verhagen, A., Nizet, V., Chen, X., Varki, N., Varki, A., Angata, T. 2014; 28 (3): 1280-1293

    Abstract

    Siglecs are sialic acid-binding Ig-like lectins that recognize sialoglycans via amino-terminal V-set domains. CD33-related Siglecs (CD33rSiglecs) on innate immune cells recognize endogenous sialoglycans as "self-associated molecular patterns" (SAMPs), dampening immune responses via cytosolic immunoreceptor tyrosine-based inhibition motifs that recruit tyrosine phosphatases. However, sialic acid-expressing pathogens subvert this mechanism through molecular mimicry. Meanwhile, endogenous host SAMPs must continually evolve to evade other pathogens that exploit sialic acids as invasion targets. We hypothesized that these opposing selection forces have accelerated CD33rSiglec evolution. We address this by comparative analysis of major CD33rSiglec (Siglec-3, Siglec-5, and Siglec-9) orthologs in humans, chimpanzees, and baboons. Recombinant soluble molecules displaying ligand-binding domains show marked quantitative and qualitative interspecies differences in interactions with strains of the sialylated pathogen, group B Streptococcus, and with sialoglycans presented as gangliosides or in the form of sialoglycan microarrays, including variations such as N-glycolyl and O-acetyl groups. Primate Siglecs also show quantitative and qualitative intra- and interspecies variations in expression patterns on leukocytes, both in circulation and in tissues. Taken together our data explain why the CD33rSiglec-encoding gene cluster is undergoing rapid evolution via multiple mechanisms, driven by the need to maintain self-recognition by innate immune cells, while escaping 2 distinct mechanisms of pathogen subversion.

    View details for DOI 10.1096/fj.13-241497

    View details for Web of Science ID 000335324800021

    View details for PubMedID 24308974

  • Gut microbes take their vitamins. Cell host & microbe Sonnenburg, E. D., Sonnenburg, J. L. 2014; 15 (1): 5-6

    Abstract

    The dense microbial ecosystem within the gut is connected through a complex web of metabolic interactions. In this issue of Cell Host & Microbe, Degnan et al. (2014) establish the importance of different vitamin B12 transporters that help a Bacteroides species acquire vitamins from the environment to maintain a competitive edge.

    View details for DOI 10.1016/j.chom.2013.12.011

    View details for PubMedID 24439893

  • Host-centric Proteomics of Stool: A Novel Strategy Focused on intestinal Responses to the Gut Microbiota. Molecular & cellular proteomics Lichtman, J. S., Marcobal, A., Sonnenburg, J. L., Elias, J. E. 2013; 12 (11): 3310-3318

    Abstract

    The diverse community of microbes that inhabits the human bowel is vitally important to human health. Host-expressed proteins are essential for maintaining this mutualistic relationship and serve as reporters on the status of host-microbiota interaction. Therefore, unbiased and sensitive methods focused on host proteome characterization are needed. Herein we describe a novel method for applying shotgun proteomics to the analysis of feces, focusing on the secreted host proteome. We have conducted the most complete analysis of the extracellular mouse gut proteome to date by employing a gnotobiotic mouse model. Using mice colonized with defined microbial communities of increasing complexity or a complete human microbiota ('humanized'), we show that the complexity of the host stool proteome mirrors the complexity of microbiota composition. We further show that host responses exhibit signatures specific to the different colonization states. We demonstrate feasibility of this approach in human stool samples and provide evidence for a "core" stool proteome as well as personalized host response features. Our method provides a new avenue for noninvasive monitoring of host-microbiota interaction dynamics via host-produced proteins in stool.

    View details for DOI 10.1074/mcp.M113.029967

    View details for PubMedID 23982161

    View details for PubMedCentralID PMC3820941

  • Genetically dictated change in host mucus carbohydrate landscape exerts a diet-dependent effect on the gut microbiota PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Kashyap, P. C., Marcobal, A., Ursell, L. K., Smits, S. A., Sonnenburg, E. D., Costello, E. K., Higginbottom, S. K., Domino, S. E., Holmes, S. P., Relman, D. A., Knight, R., Gordon, J. I., Sonnenburg, J. L. 2013; 110 (42): 17059-17064

    Abstract

    We investigate how host mucus glycan composition interacts with dietary carbohydrate content to influence the composition and expressed functions of a human gut community. The humanized gnotobiotic mice mimic humans with a nonsecretor phenotype due to knockout of their α1-2 fucosyltransferase (Fut2) gene. The fecal microbiota of Fut2(-) mice that lack fucosylated host glycans show decreased alpha diversity relative to Fut2(+) mice and exhibit significant differences in community composition. A glucose-rich plant polysaccharide-deficient (PD) diet exerted a strong effect on the microbiota membership but eliminated the effect of Fut2 genotype. Additionally fecal metabolites predicted host genotype in mice on a polysaccharide-rich standard diet but not on a PD diet. A more detailed mechanistic analysis of these interactions involved colonization of gnotobiotic Fut2(+) and Fut2(-) mice with Bacteroides thetaiotaomicron, a prominent member of the human gut microbiota known to adaptively forage host mucosal glycans when dietary polysaccharides are absent. Within Fut2(-) mice, the B. thetaiotaomicron fucose catabolic pathway was markedly down-regulated, whereas BT4241-4247, an operon responsive to terminal β-galactose, the precursor that accumulates in the Fut2(-) mice, was significantly up-regulated. These changes in B. thetaiotaomicron gene expression were only evident in mice fed a PD diet, wherein B. thetaiotaomicron relies on host mucus consumption. Furthermore, up-regulation of the BT4241-4247 operon was also seen in humanized Fut2(-) mice. Together, these data demonstrate that differences in host genotype that affect the carbohydrate landscape of the distal gut interact with diet to alter the composition and function of resident microbes in a diet-dependent manner.

    View details for DOI 10.1073/pnas.1306070110

    View details for Web of Science ID 000325634200076

    View details for PubMedID 24062455

    View details for PubMedCentralID PMC3800993

  • Microbiota-liberated host sugars facilitate post-antibiotic expansion of enteric pathogens. Nature Ng, K. M., Ferreyra, J. A., Higginbottom, S. K., Lynch, J. B., Kashyap, P. C., Gopinath, S., Naidu, N., Choudhury, B., Weimer, B. C., Monack, D. M., Sonnenburg, J. L. 2013; 502 (7469): 96-99

    Abstract

    The human intestine, colonized by a dense community of resident microbes, is a frequent target of bacterial pathogens. Undisturbed, this intestinal microbiota provides protection from bacterial infections. Conversely, disruption of the microbiota with oral antibiotics often precedes the emergence of several enteric pathogens. How pathogens capitalize upon the failure of microbiota-afforded protection is largely unknown. Here we show that two antibiotic-associated pathogens, Salmonella enterica serovar Typhimurium (S. typhimurium) and Clostridium difficile, use a common strategy of catabolizing microbiota-liberated mucosal carbohydrates during their expansion within the gut. S. typhimurium accesses fucose and sialic acid within the lumen of the gut in a microbiota-dependent manner, and genetic ablation of the respective catabolic pathways reduces its competitiveness in vivo. Similarly, C. difficile expansion is aided by microbiota-induced elevation of sialic acid levels in vivo. Colonization of gnotobiotic mice with a sialidase-deficient mutant of Bacteroides thetaiotaomicron, a model gut symbiont, reduces free sialic acid levels resulting in C. difficile downregulating its sialic acid catabolic pathway and exhibiting impaired expansion. These effects are reversed by exogenous dietary administration of free sialic acid. Furthermore, antibiotic treatment of conventional mice induces a spike in free sialic acid and mutants of both Salmonella and C. difficile that are unable to catabolize sialic acid exhibit impaired expansion. These data show that antibiotic-induced disruption of the resident microbiota and subsequent alteration in mucosal carbohydrate availability are exploited by these two distantly related enteric pathogens in a similar manner. This insight suggests new therapeutic approaches for preventing diseases caused by antibiotic-associated pathogens.

    View details for DOI 10.1038/nature12503

    View details for PubMedID 23995682

  • A metabolomic view of how the human gut microbiota impacts the host metabolome using humanized and gnotobiotic mice. ISME journal Marcobal, A., Kashyap, P. C., Nelson, T. A., Aronov, P. A., Donia, M. S., Spormann, A., Fischbach, M. A., Sonnenburg, J. L. 2013; 7 (10): 1933-1943

    Abstract

    Defining the functional status of host-associated microbial ecosystems has proven challenging owing to the vast number of predicted genes within the microbiome and relatively poor understanding of community dynamics and community-host interaction. Metabolomic approaches, in which a large number of small molecule metabolites can be defined in a biological sample, offer a promising avenue to 'fingerprint' microbiota functional status. Here, we examined the effects of the human gut microbiota on the fecal and urinary metabolome of a humanized (HUM) mouse using an optimized ultra performance liquid chromatography-mass spectrometry-based method. Differences between HUM and conventional mouse urine and fecal metabolomic profiles support host-specific aspects of the microbiota's metabolomic contribution, consistent with distinct microbial compositions. Comparison of microbiota composition and metabolome of mice humanized with different human donors revealed that the vast majority of metabolomic features observed in donor samples are produced in the corresponding HUM mice, and individual-specific features suggest 'personalized' aspects of functionality can be reconstituted in mice. Feeding the mice a defined, custom diet resulted in modification of the metabolite signatures, illustrating that host diet provides an avenue for altering gut microbiota functionality, which in turn can be monitored via metabolomics. Using a defined model microbiota consisting of one or two species, we show that simplified communities can drive major changes in the host metabolomic profile. Our results demonstrate that metabolomics constitutes a powerful avenue for functional characterization of the intestinal microbiota and its interaction with the host.The ISME Journal advance online publication, 6 June 2013; doi:10.1038/ismej.2013.89.

    View details for DOI 10.1038/ismej.2013.89

    View details for PubMedID 23739052

  • A refined palate: bacterial consumption of host glycans in the gut. Glycobiology Marcobal, A., Southwick, A. M., Earle, K. A., Sonnenburg, J. L. 2013; 23 (9): 1038-1046

    Abstract

    The human intestine houses a dense microbial ecosystem in which the struggle for nutrients creates a continual and dynamic selective force. Host-produced mucus glycans provide a ubiquitous source of carbon and energy for microbial species. Not surprisingly, many gut resident bacteria have become highly adapted to efficiently consume numerous distinct structures present in host glycans. We propose that sophistication in mucus consumption is a trait most likely to be found in gut residents that have co-evolved with hosts, microbes that have adapted to the complexity associated with the host glycan landscape.

    View details for DOI 10.1093/glycob/cwt040

    View details for PubMedID 23720460

  • A refined palate: Bacterial consumption of host glycans in the gut GLYCOBIOLOGY Marcobal, A., Southwick, A. M., Earle, K. A., Sonnenburg, J. L. 2013; 23 (9): 1038-?

    View details for DOI 10.1093/glycob/cwt040

    View details for Web of Science ID 000322340200001

    View details for PubMedID 23720460

  • Production of alpha-Galactosylceramide by a Prominent Member of the Human Gut Microbiota PLOS BIOLOGY Brown, L. C., Penaranda, C., Kashyap, P. C., Williams, B. B., Clardy, J., Kronenberg, M., Sonnenburg, J. L., Comstock, L. E., Bluestone, J. A., Fischbach, M. A. 2013; 11 (7)

    Abstract

    While the human gut microbiota are suspected to produce diffusible small molecules that modulate host signaling pathways, few of these molecules have been identified. Species of Bacteroides and their relatives, which often comprise >50% of the gut community, are unusual among bacteria in that their membrane is rich in sphingolipids, a class of signaling molecules that play a key role in inducing apoptosis and modulating the host immune response. Although known for more than three decades, the full repertoire of Bacteroides sphingolipids has not been defined. Here, we use a combination of genetics and chemistry to identify the sphingolipids produced by Bacteroides fragilis NCTC 9343. We constructed a deletion mutant of BF2461, a putative serine palmitoyltransferase whose yeast homolog catalyzes the committed step in sphingolipid biosynthesis. We show that the Δ2461 mutant is sphingolipid deficient, enabling us to purify and solve the structures of three alkaline-stable lipids present in the wild-type strain but absent from the mutant. The first compound was the known sphingolipid ceramide phosphorylethanolamine, and the second was its corresponding dihydroceramide base. Unexpectedly, the third compound was the glycosphingolipid α-galactosylceramide (α-GalCer(Bf)), which is structurally related to a sponge-derived sphingolipid (α-GalCer, KRN7000) that is the prototypical agonist of CD1d-restricted natural killer T (iNKT) cells. We demonstrate that α-GalCer(Bf) has similar immunological properties to KRN7000: it binds to CD1d and activates both mouse and human iNKT cells both in vitro and in vivo. Thus, our study reveals BF2461 as the first known member of the Bacteroides sphingolipid pathway, and it indicates that the committed steps of the Bacteroides and eukaryotic sphingolipid pathways are identical. Moreover, our data suggest that some Bacteroides sphingolipids might influence host immune homeostasis.

    View details for DOI 10.1371/journal.pbio.1001610

    View details for Web of Science ID 000322592700014

    View details for PubMedCentralID PMC3712910

  • Production of a-galactosylceramide by a prominent member of the human gut microbiota. PLoS biology Wieland Brown, L. C., Penaranda, C., Kashyap, P. C., Williams, B. B., Clardy, J., Kronenberg, M., Sonnenburg, J. L., Comstock, L. E., Bluestone, J. A., Fischbach, M. A. 2013; 11 (7)

    Abstract

    While the human gut microbiota are suspected to produce diffusible small molecules that modulate host signaling pathways, few of these molecules have been identified. Species of Bacteroides and their relatives, which often comprise >50% of the gut community, are unusual among bacteria in that their membrane is rich in sphingolipids, a class of signaling molecules that play a key role in inducing apoptosis and modulating the host immune response. Although known for more than three decades, the full repertoire of Bacteroides sphingolipids has not been defined. Here, we use a combination of genetics and chemistry to identify the sphingolipids produced by Bacteroides fragilis NCTC 9343. We constructed a deletion mutant of BF2461, a putative serine palmitoyltransferase whose yeast homolog catalyzes the committed step in sphingolipid biosynthesis. We show that the Δ2461 mutant is sphingolipid deficient, enabling us to purify and solve the structures of three alkaline-stable lipids present in the wild-type strain but absent from the mutant. The first compound was the known sphingolipid ceramide phosphorylethanolamine, and the second was its corresponding dihydroceramide base. Unexpectedly, the third compound was the glycosphingolipid α-galactosylceramide (α-GalCer(Bf)), which is structurally related to a sponge-derived sphingolipid (α-GalCer, KRN7000) that is the prototypical agonist of CD1d-restricted natural killer T (iNKT) cells. We demonstrate that α-GalCer(Bf) has similar immunological properties to KRN7000: it binds to CD1d and activates both mouse and human iNKT cells both in vitro and in vivo. Thus, our study reveals BF2461 as the first known member of the Bacteroides sphingolipid pathway, and it indicates that the committed steps of the Bacteroides and eukaryotic sphingolipid pathways are identical. Moreover, our data suggest that some Bacteroides sphingolipids might influence host immune homeostasis.

    View details for DOI 10.1371/journal.pbio.1001610

    View details for PubMedID 23874157

  • Integrative analysis of the microbiome and metabolome of the human intestinal mucosal surface reveals exquisite inter-relationships. Microbiome McHardy, I. H., Goudarzi, M., Tong, M., Ruegger, P. M., Schwager, E., Weger, J. R., Graeber, T. G., Sonnenburg, J. L., Horvath, S., Huttenhower, C., McGovern, D. P., Fornace, A. J., Borneman, J., Braun, J. 2013; 1 (1): 17-?

    Abstract

    Consistent compositional shifts in the gut microbiota are observed in IBD and other chronic intestinal disorders and may contribute to pathogenesis. The identities of microbial biomolecular mechanisms and metabolic products responsible for disease phenotypes remain to be determined, as do the means by which such microbial functions may be therapeutically modified.The composition of the microbiota and metabolites in gut microbiome samples in 47 subjects were determined. Samples were obtained by endoscopic mucosal lavage from the cecum and sigmoid colon regions, and each sample was sequenced using the 16S rRNA gene V4 region (Illumina-HiSeq 2000 platform) and assessed by UPLC mass spectroscopy. Spearman correlations were used to identify widespread, statistically significant microbial-metabolite relationships. Metagenomes for identified microbial OTUs were imputed using PICRUSt, and KEGG metabolic pathway modules for imputed genes were assigned using HUMAnN. The resulting metabolic pathway abundances were mostly concordant with metabolite data. Analysis of the metabolome-driven distribution of OTU phylogeny and function revealed clusters of clades that were both metabolically and metagenomically similar.The results suggest that microbes are syntropic with mucosal metabolome composition and therefore may be the source of and/or dependent upon gut epithelial metabolites. The consistent relationship between inferred metagenomic function and assayed metabolites suggests that metagenomic composition is predictive to a reasonable degree of microbial community metabolite pools. The finding that certain metabolites strongly correlate with microbial community structure raises the possibility of targeting metabolites for monitoring and/or therapeutically manipulating microbial community function in IBD and other chronic diseases.

    View details for DOI 10.1186/2049-2618-1-17

    View details for PubMedID 24450808

  • Complex Interactions Among Diet, Gastrointestinal Transit, and Gut Microbiota in Humanized Mice GASTROENTEROLOGY Kashyap, P. C., Marcobal, A., Ursell, L. K., Larauche, M., Duboc, H., Earle, K. A., Sonnenburg, E. D., Ferreyra, J. A., Higginbottom, S. K., Million, M., Tache, Y., Pasricha, P. J., Knight, R., Farrugia, G., Sonnenburg, J. L. 2013; 144 (5): 967-977

    Abstract

    Diet has major effects on the intestinal microbiota, but the exact mechanisms that alter complex microbial communities have been difficult to elucidate. In addition to the direct influence that diet exerts on microbes, changes in microbiota composition and function can alter host functions such as gastrointestinal (GI) transit time, which in turn can further affect the microbiota.We investigated the relationships among diet, GI motility, and the intestinal microbiota using mice that are germ-free (GF) or humanized (ex-GF mice colonized with human fecal microbiota).Analysis of gut motility revealed that humanized mice fed a standard polysaccharide-rich diet had faster GI transit and increased colonic contractility compared with GF mice. Humanized mice with faster transit due to administration of polyethylene glycol or a nonfermentable cellulose-based diet had similar changes in gut microbiota composition, indicating that diet can modify GI transit, which then affects the composition of the microbial community. However, altered transit in mice fed a diet of fermentable fructooligosaccharide indicates that diet can change gut microbial function, which can affect GI transit.Based on studies in humanized mice, diet can affect GI transit through microbiota-dependent or microbiota-independent pathways, depending on the type of dietary change. The effect of the microbiota on transit largely depends on the amount and type (fermentable vs nonfermentable) of polysaccharides present in the diet. These results have implications for disorders that affect GI transit and gut microbial communities, including irritable bowel syndrome and inflammatory bowel disease.

    View details for DOI 10.1053/j.gastro.2013.01.047

    View details for Web of Science ID 000317813900026

    View details for PubMedID 23380084

  • Integrative analysis of the microbiome and metabolome of the human intestinal mucosal surface reveals exquisite inter-relationships MICROBIOME McHardy, I. H., Goudarzi, M., Tong, M., Ruegger, P. M., Schwager, E., Weger, J. R., Graeber, T. G., Sonnenburg, J. L., Horvath, S., Huttenhower, C., McGovern, D. P., Fornace, A. J., Borneman, J., Braun, J. 2013; 1
  • Molecular Analysis of Model Gut Microbiotas by Imaging Mass Spectrometry and Nanodesorption Electrospray Ionization Reveals Dietary Metabolite Transformations ANALYTICAL CHEMISTRY Rath, C. M., Alexandrov, T., Higginbottom, S. K., Song, J., Milla, M. E., Fischbach, M. A., Sonnenburg, J. L., Dorrestein, P. C. 2012; 84 (21): 9259-9267

    Abstract

    The communities constituting our microbiotas are emerging as mediators of the health-disease continuum. However, deciphering the functional impact of microbial communities on host pathophysiology represents a formidable challenge, due to the heterogeneous distribution of chemical and microbial species within the gastrointestinal (GI) tract. Herein, we apply imaging mass spectrometry (IMS) to localize metabolites from the interaction between the host and colonizing microbiota. This approach complements other molecular imaging methodologies in that analytes need not be known a priori, offering the possibility of untargeted analysis. Localized molecules within the GI tract were then identified in situ by surface sampling with nanodesorption electrospray ionization Fourier transform ion cyclotron resonance-mass spectrometry (nanoDESI FTICR-MS). Products from diverse structural classes were identified including cholesterol-derived lipids, glycans, and polar metabolites. Specific chemical transformations performed by the microbiota were validated with bacteria in culture. This study illustrates how untargeted spatial characterization of metabolites can be applied to the molecular dissection of complex biology in situ.

    View details for DOI 10.1021/ac302039u

    View details for Web of Science ID 000310664600055

    View details for PubMedID 23009651

    View details for PubMedCentralID PMC3711173

  • Prioritization of a plant polysaccharide over a mucus carbohydrate is enforced by a Bacteroides hybrid two-component system MOLECULAR MICROBIOLOGY Lynch, J. B., Sonnenburg, J. L. 2012; 85 (3): 478-491

    Abstract

    Bacteroides is a dominant genus within the intestinal microbiota of healthy humans. Key adaptations of the Bacteroides to the dynamic intestinal ecosystem include a diverse repertoire of genes involved in sensing and processing numerous diet- and host-derived polysaccharides. One such adaptation is the carbohydrate-sensing hybrid two-component system (HTCS) family of signalling sensors, which has been widely expanded within the Bacteroides. Using Bacteroides thetaiotaomicron as a model, we have created a chimeric HTCS consisting of the well-characterized sensing domain of one HTCS, BT1754, and the regulatory domain of another HTCS, BT0366, to explore the regulatory capabilities of these molecules. We found that the BT0366 regulatory region directly binds to and mediates induction of the adjacent polysaccharide utilization locus (PUL) using whole-genome transcriptional profiling after inducing signalling through our chimeric protein. We also found that BT0366 activation simultaneously leads to repression of distal PULs involved in mucus carbohydrate consumption. These results suggest a novel mechanism by which an HTCS enforces a nutrient hierarchy within the Bacteroides via induction and repression of multiple PULs. Thus, hybrid two-component systems provide a mechanism for prioritizing consumption of carbohydrates through simultaneous binding and regulation of multiple polysaccharide utilization loci.

    View details for DOI 10.1111/j.1365-2958.2012.08123.x

    View details for Web of Science ID 000306685300007

    View details for PubMedID 22686399

    View details for PubMedCentralID PMC3404733

  • Bacteroides in the Infant Gut Consume Milk Oligosaccharides via Mucus-Utilization Pathways CELL HOST & MICROBE Marcobal, A., Barboza, M., Sonnenburg, E. D., Pudlo, N., Martens, E. C., Desai, P., Lebrilla, C. B., Weimer, B. C., Mills, D. A., German, J. B., Sonnenburg, J. L. 2011; 10 (5): 507-514

    Abstract

    Newborns are colonized with an intestinal microbiota shortly after birth, but the factors governing the retention and abundance of specific microbial lineages are unknown. Nursing infants consume human milk oligosaccharides (HMOs) that pass undigested to the distal gut, where they may be digested by microbes. We determined that the prominent neonate gut residents, Bacteroides thetaiotaomicron and Bacteroides fragilis, induce the same genes during HMO consumption that are used to harvest host mucus glycans, which are structurally similar to HMOs. Lacto-N-neotetraose, a specific HMO component, selects for HMO-adapted species such as Bifidobacterium infantis, which cannot use mucus, and provides a selective advantage to B. infantis in vivo when biassociated with B. thetaiotaomicron in the gnotobiotic mouse gut. This indicates that the complex oligosaccharide mixture within HMOs attracts both mutualistic mucus-adapted species and HMO-adapted bifidobacteria to the infant intestine that likely facilitate both milk and future solid food digestion.

    View details for DOI 10.1016/j.chom.2011.10.007

    View details for Web of Science ID 000297495100010

    View details for PubMedID 22036470

    View details for PubMedCentralID PMC3227561

  • Eating For Two: How Metabolism Establishes lnterspecies Interactions in the Gut CELL HOST & MICROBE Fischbach, M. A., Sonnenburg, J. L. 2011; 10 (4): 336-347

    Abstract

    In bacterial communities, "tight economic times" are the norm. Of the many challenges bacteria face in making a living, perhaps none are more important than generating energy, maintaining redox balance, and acquiring carbon and nitrogen to synthesize primary metabolites. The ability of bacteria to meet these challenges depends heavily on the rest of their community. Indeed, the most fundamental way in which bacteria communicate is by importing the substrates for metabolism and exporting metabolic end products. As an illustration of this principle, we will travel down a carbohydrate catabolic pathway common to many species of Bacteroides, highlighting the interspecies interactions established (often inevitably) at its key steps. We also discuss the metabolic considerations in maintaining the stability of host-associated microbial communities.

    View details for DOI 10.1016/j.chom.2011.10.002

    View details for Web of Science ID 000296600700009

    View details for PubMedID 22018234

    View details for PubMedCentralID PMC3225337

  • Community Health Care: Therapeutic Opportunities in the Human Microbiome SCIENCE TRANSLATIONAL MEDICINE Sonnenburg, J. L., Fischbach, M. A. 2011; 3 (78)

    Abstract

    We are never alone. Humans coexist with diverse microbial species that live within and upon us--our so-called microbiota. It is now clear that this microbial community is essentially another organ that plays a fundamental role in human physiology and disease. Basic and translational research efforts have begun to focus on deciphering mechanisms of microbiome function--and learning how to manipulate it to benefit human health. In this Perspective, we discuss therapeutic opportunities in the human microbiome.

    View details for DOI 10.1126/scitranslmed.3001626

    View details for Web of Science ID 000292976400002

    View details for PubMedID 21490274

    View details for PubMedCentralID PMC3287364

  • Mechanistic insight into polysaccharide use within the intestinal microbiota. Gut microbes Bolam, D. N., Sonnenburg, J. L. 2011; 2 (2): 86-90

    Abstract

    It is becoming increasingly clear that diet is one of the major factors that drives the function and composition of the intestinal microbiota. The diet of humans is highly diverse when considering different populations or even a single individual over a relatively short period of time. However, we are just beginning to understand the mechanisms that connect dietary change to intestinal microbiota dynamics. The community of microbes within our distal digestive tract influences numerous aspects of our biology, and aberrant shifts in its composition appear to be associated with several diseases. It is, therefore, necessary to understand how our behaviour and environmental factors, such as changes in diet, impact our intestinal residents. Here we look to recent work to highlight some of the major questions on the horizon for understanding the key role that the Bacteroidetes play in the commerce of dietary polysaccharides within the intestine. 

    View details for PubMedID 21637023

  • PhyloChip microarray analysis reveals altered gastrointestinal microbial communities in a rat model of colonic hypersensitivity NEUROGASTROENTEROLOGY AND MOTILITY Nelson, T. A., Holmes, S., ALEKSEYENKO, A. V., Shenoy, M., DeSantis, T., Wu, C. H., Andersen, G. L., Winston, J., Sonnenburg, J., Pasricha, P. J., Spormann, A. 2011; 23 (2)

    Abstract

    Irritable bowel syndrome (IBS) is a chronic, episodic gastrointestinal disorder that is prevalent in a significant fraction of western human populations; and changes in the microbiota of the large bowel have been implicated in the pathology of the disease.Using a novel comprehensive, high-density DNA microarray (PhyloChip) we performed a phylogenetic analysis of the microbial community of the large bowel in a rat model in which intracolonic acetic acid in neonates was used to induce long lasting colonic hypersensitivity and decreased stool water content and frequency, representing the equivalent of human constipation-predominant IBS.Our results revealed a significantly increased compositional difference in the microbial communities in rats with neonatal irritation as compared with controls. Even more striking was the dramatic change in the ratio of Firmicutes relative to Bacteroidetes, where neonatally irritated rats were enriched more with Bacteroidetes and also contained a different composition of species within this phylum. Our study also revealed differences at the level of bacterial families and species.The PhyloChip is a useful and convenient method to study enteric microflora. Further, this rat model system may be a useful experimental platform to study the causes and consequences of changes in microbial community composition associated with IBS.

    View details for DOI 10.1111/j.1365-2982.2010.01637.x

    View details for Web of Science ID 000286211600017

    View details for PubMedID 21129126

    View details for PubMedCentralID PMC3353725

  • The intestinal microbiota and viral susceptibility FRONTIERS IN MICROBIOLOGY Pfeiffer, J. K., Sonnenburg, J. L. 2011; 2
  • MICROBIOLOGY Genetic pot luck NATURE Sonnenburg, J. L. 2010; 464 (7290): 837-838

    View details for DOI 10.1038/464837a

    View details for Web of Science ID 000276397300021

    View details for PubMedID 20376136

  • Genomic and metabolic studies of the impact of probiotics on a model gut symbiont and host PLOS BIOLOGY Sonnenburg, J. L., Chen, C. T., Gordon, J. I. 2006; 4 (12): 2213-2226

    Abstract

    Probiotics are deliberately ingested preparations of live bacterial species that confer health benefits on the host. Many of these species are associated with the fermentation of dairy products. Despite their increasing use, the molecular details of the impact of various probiotic preparations on resident members of the gut microbiota and the host are generally lacking. To address this issue, we colonized germ-free mice with Bacteroides thetaiotaomicron, a prominent component of the adult human gut microbiota, and Bifidobacterium longum, a minor member but a commonly used probiotic. Simultaneous whole genome transcriptional profiling of both bacterial species in their gut habitat and of the intestinal epithelium, combined with mass-spectrometric analysis of habitat-associated carbohydrates, revealed that the presence of B. longum elicits an expansion in the diversity of polysaccharides targeted for degradation by B. thetaiotaomicron (e.g., mannose- and xylose-containing glycans), and induces host genes involved in innate immunity. Although the overall transcriptome expressed by B. thetaiotaomicron when it encounters B. longum in the cecum is dependent upon the genetic background of the mouse (as assessed by a mixed analysis of variance [ANOVA] model of co-colonization experiments performed in NMRI and C57BL/6J animals), B. thetaiotaomicron's expanded capacity to utilize polysaccharides occurs independently of host genotype, and is also observed with a fermented dairy product-associated strain, Lactobacillus casei. This gnotobiotic mouse model provides a controlled case study of how a resident symbiont and a probiotic species adapt their substrate utilization in response to one another, and illustrates both the generality and specificity of the relationship between a host, a component of its microbiota, and intentionally consumed microbial species.

    View details for DOI 10.1371/journal.pbio.0040413

    View details for Web of Science ID 000242789100005

    View details for PubMedID 17132046

  • A hybrid two-component system protein of a prominent human gut symbiont couples glycan sensing in vivo to carbohydrate metabolism PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Sonnenburg, E. D., Sonnenburg, J. L., Manchester, J. K., Hansen, E. E., Chiang, H. C., Gordon, J. I. 2006; 103 (23): 8834-8839

    Abstract

    Bacteroides thetaiotaomicron is a prominent member of our normal adult intestinal microbial community and a useful model for studying the foundations of human-bacterial mutualism in our densely populated distal gut microbiota. A central question is how members of this microbiota sense nutrients and implement an appropriate metabolic response. B. thetaiotaomicron contains a large number of glycoside hydrolases not represented in our own proteome, plus a markedly expanded collection of hybrid two-component system (HTCS) proteins that incorporate all domains found in classical two-component environmental sensors into one polypeptide. To understand the role of HTCS in nutrient sensing, we used B. thetaiotaomicron GeneChips to characterize their expression in gnotobiotic mice consuming polysaccharide-rich or -deficient diets. One HTCS, BT3172, was selected for further analysis because it is induced in vivo by polysaccharides, and its absence reduces B. thetaiotaomicron fitness in polysaccharide-rich diet-fed mice. Functional genomic and biochemical analyses of WT and BT3172-deficient strains in vivo and in vitro disclosed that alpha-mannosides induce BT3172 expression, which in turn induces expression of secreted alpha-mannosidases. Yeast two-hybrid screens revealed that the cytoplasmic portion of BT3172's sensor domain serves as a scaffold for recruiting glucose-6-phosphate isomerase and dehydrogenase. These interactions are a unique feature of BT3172 and specific for the cytoplasmic face of its sensor domain. Loss of BT3172 reduces glycolytic pathway activity in vitro and in vivo. Thus, this HTCS functions as a metabolic reaction center, coupling nutrient sensing to dynamic regulation of monosaccharide metabolism. An expanded repertoire of HTCS proteins with diversified sensor domains may be one reason for B. thetaiotaomicron's success in our intestinal ecosystem.

    View details for DOI 10.1073/pnas.0603249103

    View details for Web of Science ID 000238278400046

    View details for PubMedID 16735464

  • Operon prediction without a training set BIOINFORMATICS Westover, B. P., Buhler, J. D., Sonnenburg, J. L., Gordon, J. I. 2005; 21 (7): 880-888

    Abstract

    Annotation of operons in a bacterial genome is an important step in determining an organism's transcriptional regulatory program. While extensive studies of operon structure have been carried out in a few species such as Escherichia coli, fewer resources exist to inform operon prediction in newly sequenced genomes. In particular, many extant operon finders require a large body of training examples to learn the properties of operons in the target organism. For newly sequenced genomes, such examples are generally not available; moreover, a model of operons trained on one species may not reflect the properties of other, distantly related organisms. We encountered these issues in the course of predicting operons in the genome of Bacteroides thetaiotaomicron (B.theta), a common anaerobe that is a prominent component of the normal adult human intestinal microbial community.We describe an operon predictor designed to work without extensive training data. We rely on a small set of a priori assumptions about the properties of the genome being annotated that permit estimation of the probability that two adjacent genes lie in a common operon. Predictions integrate several sources of information, including intergenic distance, common functional annotation and a novel formulation of conserved gene order. We validate our predictor both on the known operons of E.coli and on the genome of B.theta, using expression data to evaluate our predictions in the latter.

    View details for DOI 10.1093/bioinformatics/bti123

    View details for Web of Science ID 000227977800007

    View details for PubMedID 15539453

  • Glycan foraging in vivo by an intestine-adapted bacterial symbiont SCIENCE Sonnenburg, J. L., Xu, J., Leip, D. D., Chen, C. H., Westover, B. P., Weatherford, J., Buhler, J. D., Gordon, J. I. 2005; 307 (5717): 1955-1959

    Abstract

    Germ-free mice were maintained on polysaccharide-rich or simple-sugar diets and colonized for 10 days with an organism also found in human guts, Bacteroides thetaiotaomicron, followed by whole-genome transcriptional profiling of bacteria and mass spectrometry of cecal glycans. We found that these bacteria assembled on food particles and mucus, selectively induced outer-membrane polysaccharide-binding proteins and glycoside hydrolases, prioritized the consumption of liberated hexose sugars, and revealed a capacity to turn to host mucus glycans when polysaccharides were absent from the diet. This flexible foraging behavior should contribute to ecosystem stability and functional diversity.

    View details for DOI 10.1126/science.1109051

    View details for Web of Science ID 000227957300055

    View details for PubMedID 15790854

  • Getting a grip on things: how do communities of bacterial symbionts become established in our intestine? NATURE IMMUNOLOGY Sonnenburg, J. L., Angenent, L. T., Gordon, J. I. 2004; 5 (6): 569-573

    Abstract

    The gut contains our largest collection of resident microorganisms. One obvious question is how microbial communities establish and maintain themselves within a perfused intestine. The answers, which may come in part from observations made by environmental engineers and glycobiologists, have important implications for immunologists who wish to understand how indigenous microbial communities are accommodated. Here we propose that the mucus gel layer overlying the intestinal epithelium is a key contributor to the structural and functional stability of this microbiota and its tolerance by the host.

    View details for DOI 10.1038/ni1079

    View details for Web of Science ID 000221664000014

    View details for PubMedID 15164016

  • A uniquely human consequence of domain-specific functional adaptation in a sialic acid-binding receptor GLYCOBIOLOGY Sonnenburg, J. L., Altheide, T. K., Varki, A. 2004; 14 (4): 339-346

    Abstract

    Most mammalian cell surfaces display two major sialic acids (Sias), N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). Humans lack Neu5Gc due to a mutation in CMP-Neu5Ac hydroxylase, which occurred after evolutionary divergence from great apes. We describe an apparent consequence of human Neu5Gc loss: domain-specific functional adaptation of Siglec-9, a member of the family of sialic acid-binding receptors of innate immune cells designated the CD33-related Siglecs (CD33rSiglecs). Binding studies on recombinant human Siglec-9 show recognition of both Neu5Ac and Neu5Gc. In striking contrast, chimpanzee and gorilla Siglec-9 strongly prefer binding Neu5Gc. Simultaneous probing of multiple endogenous CD33rSiglecs on circulating blood cells of human, chimp, or gorilla suggests that the binding differences observed for Siglec-9 are representative of multiple CD33rSiglecs. We conclude that Neu5Ac-binding ability of at least some human CD33rSiglecs is a derived state selected for following loss of Neu5Gc in the hominid lineage. These data also indicate that endogenous Sias (rather than surface Sias of bacterial pathogens) are the functional ligands of CD33rSiglecs and suggest that the endogenous Sia landscape is the major factor directing evolution of CD33rSiglec binding specificity. Exon-1-encoded Sia-recognizing domains of human and ape Siglec-9 share only approximately 93-95% amino acid identity. In contrast, the immediately adjacent intron and exon 2 have the approximately 98-100% identity typically observed among these species. Together, our findings suggest ongoing adaptive evolution specific to the Sia-binding domain, possibly of an episodic nature. Such domain-specific divergences should also be considered in upcoming comparisons of human and chimpanzee genomes.

    View details for DOI 10.1093/glycob/cwh039

    View details for Web of Science ID 000220896000006

    View details for PubMedID 14693915

  • Characterization of the acid stability of glycosidically linked neuraminic acid - Use in detecting de-N-acetyl-gangliosides in human melanoma JOURNAL OF BIOLOGICAL CHEMISTRY Sonnenburg, J. L., van Halbeek, H., Varki, A. 2002; 277 (20): 17502-17510

    Abstract

    The glycosidic linkage of sialic acids is much more sensitive to acid hydrolysis than those of other monosaccharides in vertebrates. The commonest sialic acids in nature are neuraminic acid (Neu)-based and are typically N-acylated at the C5 position. Unsubstituted Neu is thought to occur on native gangliosides of certain tumors and cell lines, and synthetic de-N-acetyl-gangliosides have potent biological properties in vitro. However, claims for their natural existence are based upon monoclonal antibodies and pulse-chase experiments, and there have been no reports of their chemical detection. Here we report that one of these antibodies shows nonspecific cross-reactivity with a polypeptide epitope, further emphasizing the need for definitive chemical proof of unsubstituted Neu on naturally occurring gangliosides. While pursuing this, we found that alpha2-3-linked Neu on chemically de-N-acetylated G(M3) ganglioside resists acid hydrolysis under conditions where the N-acetylated form is completely labile. To ascertain the generality of this finding, we investigated the stability of glycosidically linked alpha- and beta-methyl glycosides of Neu. Using NMR spectroscopy to monitor glycosidic linkage hydrolysis, we find that only 47% of Neualpha2Me is hydrolyzed after 3 h in 10 mm HCl at 80 degrees C, whereas Neu5Acalpha2Me is 95% hydrolyzed after 20 min under the same conditions. Notably, Neubeta2Me is hydrolyzed even slower than Neualpha2Me, indicating that acid resistance is a general property of glycosidically linked Neu. Taking advantage of this, we modified classical purification techniques for de-N-acetyl-ganglioside isolation using acid to first eliminate conventional gangliosides. We also introduce a phospholipase-based approach to remove contaminating phospholipids that previously hindered efforts to study de-N-acetyl-gangliosides. The partially purified sample can then be N-propionylated, allowing acid release and mass spectrometric detection of any originally existing Neu as Neu5Pr. These advances allowed us to detect covalently bound Neu in lipid extracts of a human melanoma tumor, providing the first chemical proof for naturally occurring de-N-acetyl-gangliosides.

    View details for DOI 10.1074/jbc.M110867200

    View details for Web of Science ID 000175685100016

    View details for PubMedID 11884388

  • Effects of sialic acid substitutions on recognition by Sambucus nigra agglutinin and Maackia amurensis hemagglutinin ANALYTICAL BIOCHEMISTRY Brinkman-Van der Linden, E. C., Sonnenburg, J. L., Varki, A. 2002; 303 (1): 98-104

    View details for DOI 10.1006/abio.2001.5539

    View details for Web of Science ID 000174784500013

    View details for PubMedID 11906157

  • De-N-acetyl-gangliosides in humans: Unusual subcellular distribution of a novel tumor antigen CANCER RESEARCH Chammas, R., Sonnenburg, J. L., Watson, N. E., Tai, T., Farquhar, M. G., Varki, N. M., Varki, A. 1999; 59 (6): 1337-1346

    Abstract

    The disialoganglioside GD3 is a major antigen in human melanomas that can undergo 9-O-acetylation of the outer sialic acid (giving 9-OAc-GD3). Monoclonal antibody SGR37 detects a different modification of the GD3, de-N-acetylation of the 5-N-acetyl group (giving de-N-Ac-GD3). We found that conventional immunohistochemistry of the SGR37 antigen is limited by a reduction in reactivity upon fixation with aldehydes (which presumably react with the free amino group) or with organic reagents (which can extract glycolipids). We optimized conditions for detection of this antigen in unfixed frozen tissue sections and studied its distribution in human tissues and tumors. It is expressed at low levels in a few blood vessels, infiltrating mononuclear cells in the skin and colon, and at moderate levels in skin melanocytes. In contrast, the antigen accumulates at high levels in many melanomas and in some lymphomas but not in carcinomas. In positive melanomas, expression is sometimes more intense and widespread than that of GD3. Both 9-O-acetylation and de-N-acetylation of GD3 seem to occur after its initial biosynthesis. Isotype-matched antibodies against GD3, 9-O-acetyl-GD3 and de-N-acetyl-GD3 were used to compare their subcellular localization and trafficking. 9-O-acetyl-GD3 colocalizes with GD3 predominantly on the cell surface and partly in lysosomal compartments. In contrast, de-N-acetyl-GD3 has a diffuse intracellular location. Adsorptive endocytosis of antibodies indicates that whereas GD3 remains predominantly on the cell surface, de-N-acetyl-GD3 is efficiently internalized into a compartment that is distinct from lysosomes. Rounding up of melanoma cells occurring during growth in culture is associated with relocation of the internal pool of de-N-acetyl-GD3 to the cell surface. Thus, a minor modification of the polar head group of a tumor-associated glycosphingolipid can markedly affect the subcellular localization and trafficking of the whole molecule. The high levels of the SGR37 antigen in melanomas and lymphomas, its selective endocytosis from the cell surface, and its relocation to the cell surface of rounded up cells suggest potential uses in diagnostic or therapeutic approaches to these diseases.

    View details for Web of Science ID 000079125200028

    View details for PubMedID 10096568

  • Resolution of subunit interactions and cytoplasmic subcomplexes of the yeast vacuolar proton-translocating ATPase JOURNAL OF BIOLOGICAL CHEMISTRY Tomashek, J. J., Sonnenburg, J. L., Artimovich, J. M., Klionsky, D. J. 1996; 271 (17): 10397-10404

    Abstract

    The vacuolar proton-translocating ATPase is the principal energization mechanism that enables the yeast vacuole to perform most of its physiological functions. We have undertaken an examination of subunit-subunit interactions and assembly states of this enzyme. Yeast two-hybrid data indicate that Vma1p and Vma2p interact with each other and that Vma4p interacts with itself. Three-hybrid data indicate that the Vma4p self-interaction is stabilized by both Vma1p and Vma2p. Native gel electrophoresis reveals numerous partial complexes not previously described. In addition to a large stable cytoplasmic complex seen in wild-type, Deltavma3 and Deltavma5 strains, we see partial complexes in the Deltavma4 and Deltavma7 strains. All larger complexes are lost in the Deltavma1, Deltavma2, and Deltavma8 strains. We designate the large complex seen in wild-type cells containing at least subunits Vma1p, Vma2p, Vma4p, Vma7p, and Vma8p as the definitive V1 complex.

    View details for Web of Science ID A1996UG25700085

    View details for PubMedID 8626613