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.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Aerobiosis
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Anaerobiosis
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Bacteria / classification
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Bacteria / genetics
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Bacteria / metabolism*
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Biodegradation, Environmental
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California
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DNA, Bacterial / chemistry
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DNA, Bacterial / genetics
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Dichloroethylenes / chemistry
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Dichloroethylenes / metabolism
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Ecosystem
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Electrophoresis
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Fresh Water / microbiology*
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Gas Chromatography-Mass Spectrometry
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Geography
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Hydrocarbons, Chlorinated / chemistry
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Hydrocarbons, Chlorinated / metabolism*
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Molecular Sequence Data
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Nitrates / chemistry
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Nitrates / metabolism
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Oxygen / chemistry
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Oxygen / metabolism
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Phylogeny
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Polymerase Chain Reaction
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Principal Component Analysis
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RNA, Ribosomal, 16S / genetics
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Sequence Analysis, DNA
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Trichloroethylene / chemistry
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Trichloroethylene / metabolism
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Water Microbiology*
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Water Pollutants, Chemical / chemistry
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Water Pollutants, Chemical / metabolism
Substances
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DNA, Bacterial
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Dichloroethylenes
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Hydrocarbons, Chlorinated
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Nitrates
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RNA, Ribosomal, 16S
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Water Pollutants, Chemical
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Trichloroethylene
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Oxygen
Associated data
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GENBANK/DQ336570
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GENBANK/DQ336571
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GENBANK/DQ336572
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GENBANK/DQ336573
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GENBANK/DQ336574
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GENBANK/DQ336575
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GENBANK/DQ336576
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GENBANK/DQ336577
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GENBANK/DQ336578
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GENBANK/DQ336579
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GENBANK/DQ336581
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GENBANK/DQ336582
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GENBANK/DQ336586
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GENBANK/DQ336587
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GENBANK/DQ336588
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GENBANK/DQ336590
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GENBANK/DQ336591
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GENBANK/DQ336592
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GENBANK/DQ336593
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GENBANK/DQ336594
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GENBANK/DQ336600
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GENBANK/DQ336601
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GENBANK/DQ336602
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GENBANK/DQ336603
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GENBANK/DQ336604
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GENBANK/DQ336605
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GENBANK/DQ336606