title: Dynamics of microbial community composition and function during in situ bioremediation of a uranium-contaminated aquifer.
abstract: A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter(-1)). Microbial communities from three monitoring wells were examined during active U(VI) reduction and maintenance phases with GeoChip, a high-density, comprehensive functional gene array. The overall microbial community structure exhibited a considerable shift over the remediation phases examined. GeoChip-based analysis revealed that Fe(III)-reducing bacterial (FeRB), nitrate-reducing bacterial (NRB), and sulfate-reducing bacterial (SRB) functional populations reached their highest levels during the active U(VI) reduction phase (days 137 to 370), in which denitrification and Fe(III) and sulfate reduction occurred sequentially. A gradual decrease in these functional populations occurred when reduction reactions stabilized, suggesting that these functional populations could play an important role in both active U(VI) reduction and maintenance of the stability of reduced U(IV). These results suggest that addition of electron donors stimulated the microbial community to create biogeochemical conditions favorable to U(VI) reduction and prevent the reduced U(IV) from reoxidation and that functional FeRB, SRB, and NRB populations within this system played key roles in this process.
authors.affiliation: University of Oklahoma, 101 David L. Boren Blvd., SRTC 2022, Norman, OK 73019, USA.
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.forename: Liyou
authors.initials: L
authors.lastname: Wu
authors.forename: Wei-Min
authors.initials: WM
authors.lastname: Wu
authors.forename: Zhijian
authors.initials: Z
authors.lastname: Huang
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Gentry
authors.forename: Ye
authors.initials: Y
authors.lastname: Deng
authors.forename: Jack
authors.initials: J
authors.lastname: Carley
authors.forename: Sue
authors.initials: S
authors.lastname: Carroll
authors.forename: Zhili
authors.initials: Z
authors.lastname: He
authors.forename: Baohua
authors.initials: B
authors.lastname: Gu
authors.forename: Jian
authors.initials: J
authors.lastname: Luo
authors.forename: Craig S
authors.initials: CS
authors.lastname: Criddle
authors.forename: David B
authors.initials: DB
authors.lastname: Watson
authors.forename: Philip M
authors.initials: PM
authors.lastname: Jardine
authors.forename: Terence L
authors.initials: TL
authors.lastname: Marsh
authors.forename: James M
authors.initials: JM
authors.lastname: Tiedje
authors.forename: Terry C
authors.initials: TC
authors.lastname: Hazen
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000254:growth & development* / Q000378:metabolism; D001673:Biodegradation, Environmental; D044822:Biodiversity; D000431:Ethanol / Q000378:metabolism; D005290:Ferric Compounds / Q000378:metabolism; D046228:Microarray Analysis; D009566:Nitrates / Q000378:metabolism; D012988:Soil Microbiology; D012990:Soil Pollutants, Radioactive / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism; D014481:United States; D014501:Uranium / Q000378:metabolism*
chemical_list: D005290:Ferric Compounds; D009566:Nitrates; D012990:Soil Pollutants, Radioactive; D013431:Sulfates; D000431:Ethanol; D014501:Uranium