Jonas Cremer is an Assistant Professor in Biology. He is interested in the physiology and growth of prokaryotes. Jonas studied physics and biophysics in Munich. He was a postdoctoral research at the University of California, San Diego. Before joining Stanford, he was an Assistant Professor at the University of Groningen. His current research considers various scales of prokaryotic life (from the coordination of fundamental processes within cells to the collective behavior of cells in specific ecological settings), with a focus on gut bacteria and the model organism Escherichia coli.
Honors & Awards
Research Fellowship, German National Academy of Sciences Leopoldina (2011)
Boards, Advisory Committees, Professional Organizations
Member, German Physical Society (2009 - Present)
Member, American Physical Society (2012 - Present)
Member, American Society for Microbiology (2016 - Present)
Master, Ludwig-Maximilians University, Physics and biophysics (2007)
PhD, Ludwig-Maximilians University, Physics (2011)
Chemotaxis as a navigation strategy to boost range expansion
2019; 575 (7784): 658-+
Bacterial chemotaxis, the directed movement of cells along gradients of chemoattractants, is among the best-characterized subjects in molecular biology1-10, but much less is known about its physiological roles11. It is commonly seen as a starvation response when nutrients run out, or as an escape response from harmful situations12-16. Here we identify an alternative role of chemotaxis by systematically examining the spatiotemporal dynamics of Escherichia coli in soft agar12,17,18. Chemotaxis in nutrient-replete conditions promotes the expansion of bacterial populations into unoccupied territories well before nutrients run out in the current environment. Low levels of chemoattractants act as aroma-like cues in this process, establishing the direction and enhancing the speed of population movement along the self-generated attractant gradients. This process of navigated range expansion spreads faster and yields larger population gains than unguided expansion following the canonical Fisher-Kolmogorov dynamics19,20 and is therefore a general strategy to promote population growth in spatially extended, nutrient-replete environments.
View details for DOI 10.1038/s41586-019-1733-y
View details for Web of Science ID 000500036800058
View details for PubMedID 31695195
View details for PubMedCentralID PMC6883170
An evolutionarily stable strategy to colonize spatially extended habitats
2019; 575 (7784): 664-+
The ability of a species to colonize newly available habitats is crucial to its overall fitness1-3. In general, motility and fast expansion are expected to be beneficial for colonization and hence for the fitness of an organism4-7. Here we apply an evolution protocol to investigate phenotypical requirements for colonizing habitats of different sizes during range expansion by chemotaxing bacteria8. Contrary to the intuitive expectation that faster is better, we show that there is an optimal expansion speed for a given habitat size. Our analysis showed that this effect arises from interactions among pioneering cells at the front of the expanding population, and revealed a simple, evolutionarily stable strategy for colonizing a habitat of a specific size: to expand at a speed given by the product of the growth rate and the habitat size. These results illustrate stability-to-invasion as a powerful principle for the selection of phenotypes in complex ecological processes.
View details for DOI 10.1038/s41586-019-1734-x
View details for Web of Science ID 000500036800059
View details for PubMedID 31695198
View details for PubMedCentralID PMC6883132
Cooperation in Microbial Populations: Theory and Experimental Model Systems
JOURNAL OF MOLECULAR BIOLOGY
2019; 431 (23): 4599–4644
Cooperative behavior, the costly provision of benefits to others, is common across all domains of life. This review article discusses cooperative behavior in the microbial world, mediated by the exchange of extracellular products called public goods. We focus on model species for which the production of a public good and the related growth disadvantage for the producing cells are well described. To unveil the biological and ecological factors promoting the emergence and stability of cooperative traits we take an interdisciplinary perspective and review insights gained from both mathematical models and well-controlled experimental model systems. Ecologically, we include crucial aspects of the microbial life cycle into our analysis and particularly consider population structures where ensembles of local communities (subpopulations) continuously emerge, grow, and disappear again. Biologically, we explicitly consider the synthesis and regulation of public good production. The discussion of the theoretical approaches includes general evolutionary concepts, population dynamics, and evolutionary game theory. As a specific but generic biological example, we consider populations of Pseudomonas putida and its regulation and use of pyoverdines, iron scavenging molecules, as public goods. The review closes with an overview on cooperation in spatially extended systems and also provides a critical assessment of the insights gained from the experimental and theoretical studies discussed. Current challenges and important new research opportunities are discussed, including the biochemical regulation of public goods, more realistic ecological scenarios resembling native environments, cell-to-cell signaling, and multispecies communities.
View details for DOI 10.1016/j.jmb.2019.09.023
View details for Web of Science ID 000506721800007
View details for PubMedID 31634468
Spatiotemporal establishment of dense bacterial colonies growing on hard agar
The physical interactions of growing bacterial cells with each other and with their surroundings significantly affect the structure and dynamics of biofilms. Here a 3D agent-based model is formulated to describe the establishment of simple bacterial colonies expanding by the physical force of their growth. With a single set of parameters, the model captures key dynamical features of colony growth by non-motile, non EPS-producing E. coli cells on hard agar. The model, supported by experiment on colony growth in different types and concentrations of nutrients, suggests that radial colony expansion is not limited by nutrients as commonly believed, but by mechanical forces. Nutrient penetration instead governs vertical colony growth, through thin layers of vertically oriented cells lifting up their ancestors from the bottom. Overall, the model provides a versatile platform to investigate the influences of metabolic and environmental factors on the growth and morphology of bacterial colonies.
View details for DOI 10.7554/eLife.41093
View details for Web of Science ID 000460929900001
View details for PubMedID 30855227
View details for PubMedCentralID PMC6411370
Bacterial growth, flow, and mixing shape human gut microbiota density and composition
2018; 9 (6): 559–66
The human gut microbiota is highly dynamic, and host physiology and diet exert major influences on its composition. In our recent study, we integrated new quantitative measurements on bacterial growth physiology with a reanalysis of published data on human physiology to build a comprehensive modeling framework. This can generate predictions of how changes in different host factors influence microbiota composition. For instance, hydrodynamic forces in the colon, along with colonic water absorption that manifests as transit time, exert a major impact on microbiota density and composition. This can be mechanistically explained by their effect on colonic pH which directly affects microbiota competition for food. In this addendum, we describe the underlying analysis in more detail. In particular, we discuss the mixing dynamics of luminal content by wall contractions and its implications for bacterial growth and density, as well as the broader implications of our insights for the field of gut microbiota research.
View details for DOI 10.1080/19490976.2018.1448741
View details for Web of Science ID 000456896600008
View details for PubMedID 29533125
View details for PubMedCentralID PMC6287699
Effect of water flow and chemical environment on microbiota growth and composition in the human colon
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2017; 114 (25): 6438–43
The human gut harbors a dynamic microbial community whose composition bears great importance for the health of the host. Here, we investigate how colonic physiology impacts bacterial growth, which ultimately dictates microbiota composition. Combining measurements of bacterial physiology with analysis of published data on human physiology into a quantitative, comprehensive modeling framework, we show how water flow in the colon, in concert with other physiological factors, determine the abundances of the major bacterial phyla. Mechanistically, our model shows that local pH values in the lumen, which differentially affect the growth of different bacteria, drive changes in microbiota composition. It identifies key factors influencing the delicate regulation of colonic pH, including epithelial water absorption, nutrient inflow, and luminal buffering capacity, and generates testable predictions on their effects. Our findings show that a predictive and mechanistic understanding of microbial ecology in the gut is possible. Such predictive understanding is needed for the rational design of intervention strategies to actively control the microbiota.
View details for DOI 10.1073/pnas.1619598114
View details for Web of Science ID 000403687300021
View details for PubMedID 28588144
View details for PubMedCentralID PMC5488924
Effect of flow and peristaltic mixing on bacterial growth in a gut-like channel
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2016; 113 (41): 11414–19
The ecology of microbes in the gut has been shown to play important roles in the health of the host. To better understand microbial growth and population dynamics in the proximal colon, the primary region of bacterial growth in the gut, we built and applied a fluidic channel that we call the "minigut." This is a channel with an array of membrane valves along its length, which allows mimicking active contractions of the colonic wall. Repeated contraction is shown to be crucial in maintaining a steady-state bacterial population in the device despite strong flow along the channel that would otherwise cause bacterial washout. Depending on the flow rate and the frequency of contractions, the bacterial density profile exhibits varying spatial dependencies. For a synthetic cross-feeding community, the species abundance ratio is also strongly affected by mixing and flow along the length of the device. Complex mixing dynamics due to contractions is described well by an effective diffusion term. Bacterial dynamics is captured by a simple reaction-diffusion model without adjustable parameters. Our results suggest that flow and mixing play a major role in shaping the microbiota of the colon.
View details for DOI 10.1073/pnas.1601306113
View details for Web of Science ID 000384886900047
View details for PubMedID 27681630
View details for PubMedCentralID PMC5068270
The emergence of cooperation from a single mutant during microbial life cycles
JOURNAL OF THE ROYAL SOCIETY INTERFACE
2015; 12 (108): 20150171
Cooperative behaviour is widespread in nature, even though cooperating individuals always run the risk of being exploited by free-riders. Population structure effectively promotes cooperation given that a threshold in the level of cooperation was already reached. However, the question how cooperation can emerge from a single mutant, which cannot rely on a benefit provided by other cooperators, is still puzzling. Here, we investigate this question for a well-defined but generic situation based on typical life cycles of microbial populations where individuals regularly form new colonies followed by growth phases. We analyse two evolutionary mechanisms favouring cooperative behaviour and study their strength depending on the inoculation size and the length of a life cycle. In particular, we find that population bottlenecks followed by exponential growth phases strongly increase the survival and fixation probabilities of a single cooperator in a free-riding population.
View details for DOI 10.1098/rsif.2015.0171
View details for Web of Science ID 000358824600024
View details for PubMedID 26063816
View details for PubMedCentralID PMC4528582
Mobility, fitness collection, and the breakdown of cooperation
PHYSICAL REVIEW E
2013; 87 (4): 042711
The spatial arrangement of individuals is thought to overcome the dilemma of cooperation: When cooperators engage in clusters, they might share the benefit of cooperation while being more protected against noncooperating individuals, who benefit from cooperation but save the cost of cooperation. This is paradigmatically shown by the spatial prisoner's dilemma model. Here, we study this model in one and two spatial dimensions, but explicitly take into account that in biological setups, fitness collection and selection are separated processes occurring mostly on vastly different time scales. This separation is particularly important to understand the impact of mobility on the evolution of cooperation. We find that even small diffusive mobility strongly restricts cooperation since it enables noncooperative individuals to invade cooperative clusters. Thus, in most biological scenarios, where the mobility of competing individuals is an irrefutable fact, the spatial prisoner's dilemma alone cannot explain stable cooperation, but additional mechanisms are necessary for spatial structure to promote the evolution of cooperation. The breakdown of cooperation is analyzed in detail. We confirm the existence of a phase transition, here controlled by mobility and costs, which distinguishes between purely cooperative and noncooperative absorbing states. While in one dimension the model is in the class of the voter model, it belongs to the directed percolation universality class in two dimensions.
View details for DOI 10.1103/PhysRevE.87.042711
View details for Web of Science ID 000317596600011
View details for PubMedID 23679453
Growth dynamics and the evolution of cooperation in microbial populations
2012; 2: 281
Microbes providing public goods are widespread in nature despite running the risk of being exploited by free-riders. However, the precise ecological factors supporting cooperation are still puzzling. Following recent experiments, we consider the role of population growth and the repetitive fragmentation of populations into new colonies mimicking simple microbial life-cycles. Individual-based modeling reveals that demographic fluctuations, which lead to a large variance in the composition of colonies, promote cooperation. Biased by population dynamics these fluctuations result in two qualitatively distinct regimes of robust cooperation under repetitive fragmentation into groups. First, if the level of cooperation exceeds a threshold, cooperators will take over the whole population. Second, cooperators can also emerge from a single mutant leading to a robust coexistence between cooperators and free-riders. We find frequency and size of population bottlenecks, and growth dynamics to be the major ecological factors determining the regimes and thereby the evolutionary pathway towards cooperation.
View details for DOI 10.1038/srep00281
View details for Web of Science ID 000300586700002
View details for PubMedID 22355791
View details for PubMedCentralID PMC3282947
Evolutionary and population dynamics: A coupled approach
PHYSICAL REVIEW E
2011; 84 (5): 051921
We study the interplay of population growth and evolutionary dynamics using a stochastic model based on birth and death events. In contrast to the common assumption of an independent population size, evolution can be strongly affected by population dynamics in general. Especially for fast reproducing microbes which are subject to selection, both types of dynamics are often closely intertwined. We illustrate this by considering different growth scenarios. Depending on whether microbes die or stop to reproduce (dormancy), qualitatively different behaviors emerge. For cooperating bacteria, a permanent increase of costly cooperation can occur. Even if not permanent, cooperation can still increase transiently due to demographic fluctuations. We validate our analysis via stochastic simulations and analytic calculations. In particular, we derive a condition for an increase in the level of cooperation.
View details for DOI 10.1103/PhysRevE.84.051921
View details for Web of Science ID 000297469000017
View details for PubMedID 22181458
Evolutionary Game Theory in Growing Populations
PHYSICAL REVIEW LETTERS
2010; 105 (17): 178101
Existing theoretical models of evolution focus on the relative fitness advantages of different mutants in a population while the dynamic behavior of the population size is mostly left unconsidered. We present here a generic stochastic model which combines the growth dynamics of the population and its internal evolution. Our model thereby accounts for the fact that both evolutionary and growth dynamics are based on individual reproduction events and hence are highly coupled and stochastic in nature. We exemplify our approach by studying the dilemma of cooperation in growing populations and show that genuinely stochastic events can ease the dilemma by leading to a transient but robust increase in cooperation.
View details for DOI 10.1103/PhysRevLett.105.178101
View details for Web of Science ID 000283054700018
View details for PubMedID 21231082
Entropy Production of Cyclic Population Dynamics
PHYSICAL REVIEW LETTERS
2010; 104 (21): 218102
Entropy serves as a central observable in equilibrium thermodynamics. However, many biological and ecological systems operate far from thermal equilibrium. Here we show that entropy production can characterize the behavior of such nonequilibrium systems. To this end we calculate the entropy production for a population model that displays nonequilibrium behavior resulting from cyclic competition. At a critical point the dynamics exhibits a transition from large, limit-cycle-like oscillations to small, erratic oscillations. We show that the entropy production peaks very close to the critical point and tends to zero upon deviating from it. We further provide analytical methods for computing the entropy production which agree excellently with numerical simulations.
View details for DOI 10.1103/PhysRevLett.104.218102
View details for Web of Science ID 000278150100063
View details for PubMedID 20867139
- The edge of neutral evolution in social dilemmas NEW JOURNAL OF PHYSICS 2009; 11
- Anomalous finite-size effects in the Battle of the Sexes EUROPEAN PHYSICAL JOURNAL B 2008; 63 (3): 373–80