title: Bacterial community analysis of shallow groundwater undergoing sequential anaerobic and aerobic chloroethene biotransformation.
abstract: At Department of Energy Site 300, beneficial hydrocarbon cocontaminants and favorable subsurface conditions facilitate sequential reductive dechlorination of trichloroethene (TCE) and rapid oxidation of the resultant cis-dichloroethene (cis-DCE) upon periodic oxygen influx. We assessed the geochemistry and microbial community of groundwater from across the site. Removal of cis-DCE was shown to coincide with oxygen influx in hydrocarbon-containing groundwater near the source area. Principal component analysis of contaminants and inorganic compounds showed that monitoring wells could be differentiated based upon concentrations of TCE, cis-DCE, and nitrate. Structurally similar communities were detected in groundwater from wells containing cis-DCE, high TCE, and low nitrate levels. Bacteria identified by sequencing 16S rRNA genes belonged to seven phylogenetic groups, including Alpha-, Beta-, Gamma- and Deltaproteobacteria, Nitrospira, Firmicutes and Cytophaga-Flexibacter-Bacteroidetes (CFB). Whereas members of the Burkholderiales and CFB group were abundant in all wells (10(4)-10(9) 16S rRNA gene copies L(-1)), quantitative PCR showed that Alphaproteobacteria were elevated (>10(6) L(-1)) only in wells containing hydrocarbon cocontaminants. The study shows that bacterial community structure is related to groundwater geochemistry and that Alphaproteobacteria are enriched in locales where cis-DCE removal occurs.
authors: Department of Environmental Health Sciences, Center for Water and Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, USA.
authors: Todd R
authors: TR
authors: Miller
authors: Mark P
authors: MP
authors: Franklin
authors: Rolf U
authors: RU
authors: Halden
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002140:California; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004000:Dichloroethylenes / Q000737:chemistry / Q000378:metabolism; D017753:Ecosystem; D004586:Electrophoresis; D005618:Fresh Water / Q000382:microbiology*; D008401:Gas Chromatography-Mass Spectrometry; D005843:Geography; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D025341:Principal Component Analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014241:Trichloroethylene / Q000737:chemistry / Q000378:metabolism; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D004000:Dichloroethylenes; D006843:Hydrocarbons, Chlorinated; D009566:Nitrates; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D014241:Trichloroethylene; D010100:Oxygen