Bio


Dr. Alexandra Polasko is a postdoctoral fellow at Stanford University School of Medicine in the Department of Urology in Dr. James Brooks's lab. She received her M.S. and Ph.D. from UCLA in Civil and Environmental Engineering in Dr. Shaily Mahendra's lab and bachelors from UC Berkeley. Before coming to Stanford, she was a postdoctoral fellow at UCLA in the School of Dentistry, Oral Biology Division under Dr. Hung Ton-That where she studied the role motility plays as a virulence factor in oral pathogens. Currently, Dr. Polasko's research focuses on elucidating the mechanisms that drive benign prostate hyperplasia, which is the abnormal growth of the prostate and affects nearly 80% of men over eighty and can result in impaired urine storage and voiding as well as renal failure. She is a co-inventor on two patents and received UCLA's prestigious Distinguished Teaching Award for Teaching Assistants (2021).

Honors & Awards


  • K12 NIH Career Development Award, National Institute of Health (2024-2026)
  • Dean's Postdoctoral Fellowship, Stanford School of Medicine (2024)
  • 1st Place Poster Presentation: Techniques, Models & Measures, Collaborating for the Advancement of Interdisciplinary Research in Benign Urology-CAIRIBU Conference (2023)
  • Institutional Research and Academic Career Development 3-Year Award Postdoctoral Fellow Recipient, University of California Los Angeles | Center for the Integration of Research, Teaching, & Learning (2022)
  • School of Dentistry Research Day Oral Presentation Competition, 1st Place, University of California, Los Angeles (2022)
  • NIH T90 Dentist-Scientist and Oral Health-Researcher Training Fellowship, University of California, Los Angeles (2021)
  • Distinguished Teaching Award for Teaching Assistants, University of California, Los Angeles (2021)
  • Eugene V. Cota Robles 4-Year Graduate Fellowship, University of California (2015-2020)
  • SILQ Industry-Sponsored Research Fellowship, SILQ Technologies (2019, 2020)
  • Center for the Advancement of Teaching Classroom Mini-Grant, University of California, Los Angeles (2019)
  • American Water Works Association Drinking Water National Scholarship, American Water Works Association (2019)
  • Emerging Contaminants Conference Poster Presentation Award, 1st Place, Emerging Contaminants Summit (2018)
  • Distinguished Master's Thesis Award (Engineering), University of California, Los Angeles (2017)
  • Campus Wide Research Pitch Competition (GradSlam), 3rd Place, University of California, Los Angeles (2017)
  • American Society of Microbiology Agar Art Finalist, "Don't Cry Over Spilt Bacteria", American Society of Microbiology (2017)
  • Brown and Caldwell Women in Leadership Fellowship, Brown and Caldwell Consulting (2016)
  • New England Biolabs National Passion in Science Award, New England Biolabs (2016)
  • National Science Foundation Graduate Research Fellowship, Honorable Mention, National Science Foundation (NSF) (2016)
  • Malcom R. Stacey Research Fellowship, University of California, Los Angeles (2015)
  • Charlene Conrad Liebau Prize for Undergraduate Research, Honorable Mention, University of California, Berkeley (2015)
  • Len Assante National Groundwater Research Fellowship, University of California, Berkeley (2015)
  • Stockholm Junior Water Prize, Arizona State Winner, Water Environment Federation (2011)

Professional Education


  • Doctor of Philosophy, University of California Los Angeles (2021)
  • Master of Science, University of California Los Angeles (2017)
  • Postdoctoral Fellow, University of California, Los Angeles, Oral Biology, Dentistry (2022)
  • Ph.D., University of California, Los Angeles, Civil and Environmental Engineering (2021)
  • M.S., University of California, Los Angeles, Civil Engineering (2017)
  • B.S., University of California, Berkeley, Environmental Science (2015)

Stanford Advisors


Community and International Work


  • Stanford Undergraduate Pre-Renal Mentorship Program, Stanford University

    Topic

    Urological Research

    Populations Served

    Undergraduates

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    No

  • Nanovation Youth Program

    Partnering Organization(s)

    UCLA

    Location

    California

    Ongoing Project

    No

    Opportunities for Student Involvement

    No

  • CNSI Nanoscience Education Outreach

    Partnering Organization(s)

    UCLA

    Populations Served

    Highschool and middle school teachers

    Ongoing Project

    No

    Opportunities for Student Involvement

    No

Patents


  • 1.Shaily Mahendra and Alexandra L. Polasko. "United States Patent 62/590,030 Anaerobic-Aerobic Bioremediation of Contaminated Water", The Regents of the University of California, Nov 26, 2020
  • 2.Richard B. Kaner, Dayong Chen, Brian T. McVerry, Ethan Rao, and Alexandra L. Polasko. "United States Patent 10,729822 Biofouling Resistant Coatings and Methods of Making and Using The Same", The Regents of the University of California, Hydrophilix, Aug 24, 2020

Lab Affiliations


Graduate and Fellowship Programs


  • Urogynecology (Fellowship Program)

All Publications


  • Enhanced in situ bioremediation of chlorinated ethenes: from in situ microcosms to full-scale application BIOREMEDIATION JOURNAL Polasko, A. L., Ponticello, W., Mahendra, S., LaPat-Polasko, L. 2024
  • Evaluation of historical data on persistent organic pollutants and heavy metals in Lake Baikal: Implications for accumulation in marine environments. Environmental research Polasko, A. L., Koutnik, V. S., Tsai, K., Alkidim, S., Borthakur, A., Mohanty, S., Mahendra, S. 2024; 252 (Pt 3): 119035

    Abstract

    Lake Baikal, the largest freshwater lake by volume, provides drinking water and aquatic food supplies to over 2.5 million people. However, the lake has been contaminated with recalcitrant pollutants released from surrounding industrial complexes, agriculture, and natural lands, thereby increasing the risk of their bioaccumulation in fish and seals. Yet, a collective analysis of historical concentration data and their bioaccumulation potential as well as what factors drive their accumulation in fish or seals remains largely unknown. We analyzed concentration data from 42 studies collected between 1985 and 2019 in water, sediment, fish, and seals of Lake Baikal. Heavy metals had the highest concentrations in water and biota followed closely by polycyclic aromatic hydrocarbons (PAHs) and organochlorines. Among organochlorines, polychlorinated biphenyls (PCBs) showed the highest levels in water, surpassing hexachlorocyclohexane (HCH) concentrations, particularly after normalizing to solubility. While naphthalene and phenanthrene exhibited the highest average concentrations among polycyclic aromatic hydrocarbons (PAHs), their relative concentrations significantly decreased upon solubility normalization. The analysis confirmed that bioconcentration and biomagnification of organochlorine pesticides, PCBs, PAHs, and heavy metals depend primarily on source strength to drive their concentration in water and secondarily on their chemical characteristics as evidenced by the higher concentrations of low-solubility PCBs and high molecular weight PAHs in water and sediment. The differential biomagnification patterns of Cu, Hg, and Zn compared to Pb are attributed to their distinct sources and bioavailability, with Cu, Hg, and Zn showing more pronounced biomagnification due to prolonged industrial release, in contrast to the declining Pb levels. Dibenzo-p-dioxins were detected in sediment and seals, but not in water or fish compartments. These data highlight the importance of addressing even low concentrations of organic and inorganic pollutants and the need for more consistent and frequent monitoring to ensure the future usability of this and other similar essential natural resources.

    View details for DOI 10.1016/j.envres.2024.119035

    View details for PubMedID 38685302

  • AZGP1 deficiency promotes angiogenesis in prostate cancer. Journal of translational medicine Wen, R. M., Qiu, Z., Marti, G. E., Peterson, E. E., Marques, F. J., Bermudez, A., Wei, Y., Nolley, R., Lam, N., Polasko, A. L., Chiu, C. L., Zhang, D., Cho, S., Karageorgos, G. M., McDonough, E., Chadwick, C., Ginty, F., Jung, K. J., Machiraju, R., Mallick, P., Crowley, L., Pollack, J. R., Zhao, H., Pitteri, S. J., Brooks, J. D. 2024; 22 (1): 383

    Abstract

    Loss of AZGP1 expression is a biomarker associated with progression to castration resistance, development of metastasis, and poor disease-specific survival in prostate cancer. However, high expression of AZGP1 cells in prostate cancer has been reported to increase proliferation and invasion. The exact role of AZGP1 in prostate cancer progression remains elusive.AZGP1 knockout and overexpressing prostate cancer cells were generated using a lentiviral system. The effects of AZGP1 under- or over-expression in prostate cancer cells were evaluated by in vitro cell proliferation, migration, and invasion assays. Heterozygous AZGP1± mice were obtained from European Mouse Mutant Archive (EMMA), and prostate tissues from homozygous knockout male mice were collected at 2, 6 and 10 months for histological analysis. In vivo xenografts generated from AZGP1 under- or over-expressing prostate cancer cells were used to determine the role of AZGP1 in prostate cancer tumor growth, and subsequent proteomics analysis was conducted to elucidate the mechanisms of AZGP1 action in prostate cancer progression. AZGP1 expression and microvessel density were measured in human prostate cancer samples on a tissue microarray of 215 independent patient samples.Neither the knockout nor overexpression of AZGP1 exhibited significant effects on prostate cancer cell proliferation, clonal growth, migration, or invasion in vitro. The prostates of AZGP1-/- mice initially appeared to have grossly normal morphology; however, we observed fibrosis in the periglandular stroma and higher blood vessel density in the mouse prostate by 6 months. In PC3 and DU145 mouse xenografts, over-expression of AZGP1 did not affect tumor growth. Instead, these tumors displayed decreased microvessel density compared to xenografts derived from PC3 and DU145 control cells, suggesting that AZGP1 functions to inhibit angiogenesis in prostate cancer. Proteomics profiling further indicated that, compared to control xenografts, AZGP1 overexpressing PC3 xenografts are enriched with angiogenesis pathway proteins, including YWHAZ, EPHA2, SERPINE1, and PDCD6, MMP9, GPX1, HSPB1, COL18A1, RNH1, and ANXA1. In vitro functional studies show that AZGP1 inhibits human umbilical vein endothelial cell proliferation, migration, tubular formation and branching. Additionally, tumor microarray analysis shows that AZGP1 expression is negatively correlated with blood vessel density in human prostate cancer tissues.AZGP1 is a negative regulator of angiogenesis, such that loss of AZGP1 promotes angiogenesis in prostate cancer. AZGP1 likely exerts heterotypical effects on cells in the tumor microenvironment, such as stromal and endothelial cells. This study sheds light on the anti-angiogenic characteristics of AZGP1 in the prostate and provides a rationale to target AZGP1 to inhibit prostate cancer progression.

    View details for DOI 10.1186/s12967-024-05183-x

    View details for PubMedID 38659028

    View details for PubMedCentralID 321763

  • Original Proteomics analysis of urine and catheter-associated biofilms in spinal cord injury patients AMERICAN JOURNAL OF CLINICAL AND EXPERIMENTAL UROLOGY Garcia-Marques, F. J., Zakrasek, E., Bermudez, A., Polasko, A. L., Liu, S., Stoyanova, T., Brooks, J., Lavelle, J., Pitteri, S. J. 2023; 11 (3): 206-219
  • A Readily Scalable, Clinically Demonstrated, Antibiofouling Zwitterionic Surface Treatment for Implantable Medical Devices ADVANCED MATERIALS McVerry, B., Polasko, A., Rao, E., Haghniaz, R., Chen, D., He, N., Ramos, P., Hayashi, J., Curson, P., Wu, C., Bandaru, P., Anderson, M., Bui, B., Sayegh, A., Mahendra, S., Di Carlo, D., Kreydin, E., Khademhosseini, A., Sheikhi, A., Kaner, R. B. 2022; 34 (20): e2200254

    Abstract

    Unlike growth on tissue, microbes can grow freely on implantable devices with minimal immune system intervention and often form resilient biofilms that continuously pump out pathogenic cells. The efficacy of antibiotics used to treat infection is declining due to increased rates of pathogenic resistance. A simple, one-step zwitterionic surface modification is developed to significantly reduce protein and microbial adhesion to synthetic materials and demonstrate the successful modification of several clinically relevant materials, including recalcitrant materials such as elastomeric polydimethylsiloxane. The treated surfaces exhibit robust adhesion resistance against proteins and microorganisms in both static and flow conditions. Furthermore, the surface treatment prevents the adhesion of mammalian fibroblast cells while displaying no cytotoxicity. To demonstrate the clinical efficacy of the novel technology in the real-world, a surface-treated, commercial silicone foley catheter is developed that is cleared for use by the U.S. Food and Drug Administration (K192034). 16 long-term catheterized patients received surface-treated catheters and completed a Patient Global Impression of Improvement (PGI-I) questionnaire. 10 out of 16 patients described their urinary tract condition post implantation as "much better" or "very much better" and 72% (n = 13) of patients desire to continue using the surface-treated catheter over conventional latex or silicone catheters.

    View details for DOI 10.1002/adma.202200254

    View details for Web of Science ID 000781050900001

    View details for PubMedID 35315553

    View details for PubMedCentralID PMC9153982

  • Profiling microbial community structures and functions in bioremediation strategies for treating 1,4-dioxane-contaminated groundwater JOURNAL OF HAZARDOUS MATERIALS Miao, Y., Heintz, M. B., Bell, C. H., Johnson, N. W., Polasko, A., Favero, D., Mahendra, S. 2021; 408: 124457

    Abstract

    Microbial community compositions and functional profiles were analyzed in microcosms established using aquifer materials from a former automobile factory site, where 1,4-dioxane was identified as the primary contaminant of concern. Propane or oxygen biostimulation resulted in limited 1,4-dioxane degradation, which was markedly enhanced with the addition of nutrients, resulting in abundant Mycobacterium and Methyloversatilis taxa and high expressions of propane monooxygenase gene, prmA. In bioaugmented treatments, Pseudonocardia dioxanivorans CB1190 or Rhodococcus ruber ENV425 strains dominated immediately after augmentation and degraded 1,4-dioxane rapidly which was consistent with increased representation of xenobiotic and lipid metabolism-related functions. Although the bioaugmented microbes decreased due to insufficient growth substrates and microbial competition, they did continue to degrade 1,4-dioxane, presumably by indigenous propanotrophic and heterotrophic bacteria, inducing similar community structures across bioaugmentation conditions. In various treatments, functional redundancy acted as buffer capacity to ensure a stable microbiome, drove the restoration of the structure and microbial functions to original levels, and induced the decoupling between basic metabolic functions and taxonomy. The results of this study provided valuable information for design and decision-making for ex-situ bioreactors and in-situ bioremediation applications. A metagenomics-based understanding of the treatment process will enable efficient and accurate adjustments when encountering unexpected issues in bioremediation.

    View details for DOI 10.1016/j.jhazmat.2020.124457

    View details for Web of Science ID 000620383200005

    View details for PubMedID 33189472

  • Vinyl chloride and 1,4-dioxane metabolism by Pseudonocardia dioxanivorans CB1190 Journal of Hazardous Materials Letters Polasko, A. L., Miao, Y., Kwok, I., Park, J. O., Mahendra, S. 2021; 2 (100039)
  • A multipronged approach for accurate in vitro quantification of catheter-associated biofilms Journal of Hazardous Materials Letters Polasko, A. L., Ramos, P., Kaner, R. B., Mahendra, S. 2021; 2 (10032)
  • A Mixed Microbial Community for the Biodegradation of Chlorinated Ethenes and 1,4-Dioxane ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS Polasko, A., Zulli, A., Gedalanga, P. B., Pornwongthong, P., Mahendra, S. 2019; 6 (1): 49-54
  • Co-contaminant effects on 1,4-dioxane biodegradation in packed soil column flow-through systems ENVIRONMENTAL POLLUTION Zhao, L., Lu, X., Polasko, A., Johnson, N. W., Miao, Y., Yang, Z., Mahendra, S., Gu, B. 2018; 243: 573-581

    Abstract

    Biodegradation of 1,4-dioxane was examined in packed quartz and soil column flow-through systems. The inhibitory effects of co-contaminants, specifically trichloroethene (TCE), 1,1-dichloroethene (1,1-DCE), and copper (Cu2+) ions, were investigated in the columns either with or without bioaugmentation with a 1,4-dioxane degrading bacterium Pseudonocardia dioxanivorans CB1190. Results indicate that CB1190 cells readily grew and colonized in the columns, leading to significant degradation of 1,4-dioxane under oxic conditions. Degradation of 1,4-dioxane was also observed in the native soil (without bioaugmentation), which had been previously subjected to enhanced reductive dechlorination treatment for co-contaminants TCE and 1,1-DCE. Bioaugmentation of the soil with CB1190 resulted in nearly complete degradation at influent concentrations of 3-10 mg L-1 1,4-dioxane and a residence reaction time of 40-80 h, but the presence of co-contaminants, 1,1-DCE and Cu2+ ions (up to 10 mg L-1), partially inhibited 1,4-dioxane degradation in the untreated and bioaugmented soil columns. However, the inhibitory effects were much less severe in the column flow-through systems than those previously observed in planktonic cultures, which showed near complete inhibition at the same co-contaminant concentrations. These observations demonstrate a low susceptibility of soil microbes to the toxicity of 1,1-DCE and Cu2+ in packed soil flow-through systems, and thus have important implications for predicting biodegradation potential and developing sustainable, cost-effective technologies for in situ remediation of 1,4-dioxane contaminated soils and groundwater.

    View details for DOI 10.1016/j.envpol.2018.09.018

    View details for Web of Science ID 000449891800062

    View details for PubMedID 30216889

  • Development of bioreactors for comparative study of natural attenuation, biostimulation, and bioaugmentation of petroleum-hydrocarbon contaminated soil JOURNAL OF HAZARDOUS MATERIALS Safdari, M., Kariminia, H., Rahmati, M., Fazlollahi, F., Polasko, A., Mahendra, S., Wilding, W., Fletcher, T. H. 2018; 342: 270-278

    Abstract

    Bioremediation of soil and groundwater sites contaminated by petroleum hydrocarbons is known as a technically viable, cost-effective, and environmentally sustainable technology. The purpose of this study is to investigate laboratory-scale bioremediation of petroleum-hydrocarbon contaminated soil through development of eight bioreactors, two bioreactors for each bioremediation mode. The modes were: (1) natural attenuation (NA); (2) biostimulation (BS) with oxygen and nutrients; (3) bioaugmentation (BA) with hydrocarbon degrading isolates; (4) a combination of biostimulation and bioaugmentation (BS-BA). Total petroleum hydrocarbons (TPH) mass balance over the bioreactors showed about 2% of initial 20,000mgkg-soil-1 TPH was removed by advection due to synthetic groundwater which was flowing through the soil, and the rest of decrease in TPH was caused by biodegradation. The BS-BA mode showed the highest TPH biodegradation percentage (89.7±0.3%) compared to the NA (51.4±0.6%), BS (81.9±0.3%) and BA (62.9±0.5%) modes. Furthermore, an increase in microbial population was another evidence of TPH biodegradation by microorganism. Reaction rate data from each bioremediation mode were fitted with a first-order reaction rate model. The Monod kinetic constants including maximum specific growth rate of microorganisms (μmax) and substrate concentration at half-velocity constant (Ks) were estimated for each bioremediation modes.

    View details for DOI 10.1016/j.jhazmat.2017.08.044

    View details for Web of Science ID 000414880800029

    View details for PubMedID 28843796

  • Effects of Sulfate Reduction on Trichloroethene Dechlorination by Dehalococcoides-Containing Microbial Communities APPLIED AND ENVIRONMENTAL MICROBIOLOGY Mao, X., Polasko, A., Alvarez-Cohen, L. 2017; 83 (8)

    Abstract

    In order to elucidate interactions between sulfate reduction and dechlorination, we systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia, and enrichments containing Dehalococcoides sp. Sulfate (up to 5 mM) did not inhibit the growth or metabolism of pure cultures of the dechlorinator Dehalococcoides mccartyi 195, the sulfate reducer Desulfovibrio vulgaris Hildenborough, or the syntroph Syntrophomonas wolfei In contrast, sulfide at 5 mM exhibited inhibitory effects on growth of the sulfate reducer and the syntroph, as well as on both dechlorination and growth rates of D. mccartyi Transcriptomic analysis of D. mccartyi 195 revealed that genes encoding ATP synthase, biosynthesis, and Hym hydrogenase were downregulated during sulfide inhibition, whereas genes encoding metal-containing enzymes involved in energy metabolism were upregulated even though the activity of those enzymes (hydrogenases) was inhibited. When the electron acceptor (trichloroethene) was limiting and an electron donor (lactate) was provided in excess to cocultures and enrichments, high sulfate concentrations (5 mM) inhibited reductive dechlorination due to the toxicity of generated sulfide. The initial cell ratio of sulfate reducers to D. mccartyi (1:3, 1:1, or 3:1) did not affect the dechlorination performance in the presence of sulfate (2 and 5 mM). In contrast, under electron donor limitation, dechlorination was not affected by sulfate amendments due to low sulfide production, demonstrating that D. mccartyi can function effectively in anaerobic microbial communities containing moderate sulfate concentrations (5 mM), likely due to its ability to outcompete other hydrogen-consuming bacteria and archaea.IMPORTANCE Sulfate is common in subsurface environments and has been reported as a cocontaminant with chlorinated solvents at various concentrations. Inconsistent results for the effects of sulfate inhibition on the performance of dechlorination enrichment cultures have been reported in the literature. These inconsistent findings make it difficult to understand potential mechanisms of sulfate inhibition and complicate the interpretation of bioremediation field data. In order to elucidate interactions between sulfate reduction and reductive dechlorination, this study systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia, and enrichments containing Dehalococcoides sp. This study provides a more fundamental understanding of the competition mechanisms between reductive dechlorination by Dehalococcoides mccartyi and sulfate reduction during the bioremediation process. It also provides insights on the significance of sulfate concentrations on reductive dechlorination under electron donor/acceptor-limiting conditions during in situ bioremediation applications. For example, at a trichloroethene-contaminated site with a high sulfate concentration, proper slow-releasing electron donors can be selected to generate an electron donor-limiting environment that favors reductive dechlorination and minimizes the sulfide inhibition effect.

    View details for DOI 10.1128/AEM.03384-16

    View details for Web of Science ID 000398771200018

    View details for PubMedID 28159790

    View details for PubMedCentralID PMC5377507

  • Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei APPLIED AND ENVIRONMENTAL MICROBIOLOGY Mao, X., Stenuit, B., Polasko, A., Alvarez-Cohen, L. 2015; 81 (6): 2015-2024

    Abstract

    Dehalococcoides mccartyi 195 (strain 195) and Syntrophomonas wolfei were grown in a sustainable syntrophic coculture using butyrate as an electron donor and carbon source and trichloroethene (TCE) as an electron acceptor. The maximum dechlorination rate (9.9 ± 0.1 μmol day(-1)) and cell yield [(1.1 ± 0.3) × 10(8) cells μmol(-1) Cl(-)] of strain 195 maintained in coculture were, respectively, 2.6 and 1.6 times higher than those measured in the pure culture. The strain 195 cell concentration was about 16 times higher than that of S. wolfei in the coculture. Aqueous H2 concentrations ranged from 24 to 180 nM during dechlorination and increased to 350 ± 20 nM when TCE was depleted, resulting in cessation of butyrate fermentation by S. wolfei with a theoretical Gibbs free energy of -13.7 ± 0.2 kJ mol(-1). Carbon monoxide in the coculture was around 0.06 μmol per bottle, which was lower than that observed for strain 195 in isolation. The minimum H2 threshold value for TCE dechlorination by strain 195 in the coculture was 0.6 ± 0.1 nM. Cell aggregates during syntrophic growth were observed by scanning electron microscopy. The interspecies distances to achieve H2 fluxes required to support the measured dechlorination rates were predicted using Fick's law and demonstrated the need for aggregation. Filamentous appendages and extracellular polymeric substance (EPS)-like structures were present in the intercellular spaces. The transcriptome of strain 195 during exponential growth in the coculture indicated increased ATP-binding cassette transporter activities compared to the pure culture, while the membrane-bound energy metabolism related genes were expressed at stable levels.

    View details for DOI 10.1128/AEM.03464-14

    View details for Web of Science ID 000350554800016

    View details for PubMedID 25576615

    View details for PubMedCentralID PMC4345365

  • Using electron balances and molecular techniques to assess trichoroethene-induced shifts to a dechlorinating microbial community BIOTECHNOLOGY AND BIOENGINEERING Ziv-El, M., Popat, S. C., Parameswaran, P., Kang, D., Polasko, A., Halden, R. U., Rittmann, B. E., Krajmalnik-Brown, R. 2012; 109 (9): 2230-2239

    Abstract

    This study demonstrated the utility in correlating performance and community structure of a trichloroethene (TCE)-dechlorinating microbial consortium; specifically dechlorinators, fermenters, homoacetogens, and methanogens. Two complementary approaches were applied: predicting trends in the microbial community structure based on an electron balance analysis and experimentally assessing the community structure via pyrosequencing and quantitative polymerase chain reaction (qPCR). Fill-and-draw reactors inoculated with the DehaloR^2 consortium were operated at five TCE-pulsing rates between 14 and 168 µmol/10-day-SRT, amended with TCE every 2 days to give peak concentrations between 0.047 and 0.56 mM (6-74 ppm) and supplied lactate and methanol as sources of e(-) donor and carbon. The complementary approaches demonstrated the same trends: increasing abundance of Dehalococcoides and Geobacter and decreasing abundance of Firmicutes with increasing TCE pulsing rate, except for the highest pulsing rate. Based on qPCR, the abundance of Geobacter and Dehalococcoides decreased for the highest TCE pulsing rate, and pyrosequencing showed this same trend for the latter. This deviation suggested decoupling of Dehalococcoides growth from dechlorination. At pseudo steady-state, methanogenesis was minimal for all TCE pulsing rates. Pyrosequencing and qPCR showed suppression of the homoacetogenic genera Acetobacterium at the two highest pulsing rates, and it was corroborated by a decreased production of acetate from lactate fermentation and increased propionate production. Suppression of Acetobacterium, which can provide growth factors to Dehalococcoides, may have contributed to the decoupling for the highest TCE-pulsing rate.

    View details for DOI 10.1002/bit.24504

    View details for Web of Science ID 000306759500007

    View details for PubMedID 22447387