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CHARACTERIZING THE MICROBIAL COMMUNITY IN SABRE MICROCOSM STUDIES (ABSTRACT ONLY)
Citation:
DWORATZEK, S., J. ROBERTS, R. F. HERRMANN, T. DAHLING, C. M. ACHESON, D. W. MAJOR, M. HARKNESS, A. FISHER, R. ROYER, M. LEE, E. E. MACK, AND J. PAYNE. CHARACTERIZING THE MICROBIAL COMMUNITY IN SABRE MICROCOSM STUDIES (ABSTRACT ONLY). In Proceedings, Fifth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, CA, May 22 - 25, 2006. Battelle Press, Columbus, OH, B-39, ISBN1574771574, (2006).
Impact/Purpose:
To inform the public.
Description:
The SABRE (Source Area BioREmediation) project will evaluate accelerated anaerobic bioremediation of chlorinated solvents in areas of high concentration, such as DNAPL source areas. In preparation for a field scale pilot test, laboratory microcosm and column studies were conducted to design the system and obtain modeling information. System design questions evaluated in a microcosm study included: selecting an electron donor; evaluating the necessity or advantages of bioaugmentation; evaluating the necessity or advantages of nitrogen, phosphorous, and micronutrient amendment; and evaluating the effect of trichloroethylene (TCE) concentration. Column studies were used to estimate kinetic rate constants, transport parameters, and stoichiometric constants for pilot test design as well as methods to introduce electron donors and other amendments. In both studies, performance was assessed based on the chemical concentrations of TCE and dechlorination products. In addition, the microbial community was characterized using four techniques: quantitative polymerase chain reaction (PCR) enumeration of Dehalococcoides organisms (DHC); semi-quantitative PCR of vinyl chloride reductase (VCR); denaturing gel electrophoresis (DGGE) of the microbial community, and phopholipid fatty acid analysis (PLFA). DHC was tracked as these microbes are capable of complete reductive dechlorination of TCE to ethene. The VCR test provides information on expression of a specific DHC gene and can be used to evaluate the activity of indigenous and bioaugmented DHC. Since the technique was applied in a semi-quantitative fashion, samples can be ranked based on VCR response. Microbial diversity was assessed by DGGE and PLFA. DGGE measures the genetic diversity of a population based on the 16S rRNA gene. In some cases, taxonomic identifications are possible. PLFA was used to describe the size and structure of the microbial community based on the phospholipids present in cell membranes. DGGE and PLFA provide complimentary information on microbial diversity. DGGE uses genetics as a basis while PLFA uses cell membrane components. In combination, these four molecular techniques provide a robust understanding of the microbial community. The microcosm study evaluated six electron donors, bioaugmentation, nutrient amendment, and TCE concentration effect. Statistical techniques such as analysis of variance (ANOVA) were used to evaluate the chemical data. PLFA was used to evaluate all microcosms. Total biomass measurements by PLFA were compared by ANOVA. PLFA community structure was compared using hierarchical cluster analysis. DHC, VCR and DGGE were analyzed for microcosms with statistically superior treatments and to evaluate bioaugmentaion. Results from microbial characterization were compared to chemical results to obtain a more thorough understanding of the microcosm study. The column study was analyzed in a similar manner.
URLs/Downloads:
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