title: A Slow-Release Substrate Stimulates Groundwater Microbial Communities for Long-Term in Situ Cr(VI) Reduction.
abstract: Cr(VI) is a widespread environmental contaminant that is highly toxic and soluble. Previous work indicated that a one-time amendment of polylactate hydrogen-release compound (HRC) reduced groundwater Cr(VI) concentrations for >3.5 years at a contaminated aquifer; however, microbial communities responsible for Cr(VI) reduction are poorly understood. In this study, we hypothesized that HRC amendment would significantly change the composition and structure of groundwater microbial communities, and that the abundance of key functional genes involved in HRC degradation and electron acceptor reduction would increase long-term in response to this slowly degrading, complex substrate. To test these hypotheses, groundwater microbial communities were monitored after HRC amendment for >1 year using a comprehensive functional gene microarray. The results showed that the overall functional composition and structure of groundwater microbial communities underwent sequential shifts after HRC amendment. Particularly, the abundance of functional genes involved in acetate oxidation, denitrification, dissimilatory nitrate reduction, metal reduction, and sulfate reduction significantly increased. The overall community dynamics was significantly correlated with changes in groundwater concentrations of microbial biomass, acetate, NO3-, Cr(VI), Fe(II) and SO4(2-). Our results suggest that HRC amendment primarily stimulated key functional processes associated with HRC degradation and reduction of multiple electron acceptors in the aquifer toward long-term Cr(VI) reduction.
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Zhili
authors.initials: Z
authors.lastname: He
authors.affiliation: Earth Science Division, Lawrence Berkeley National Laboratory , Berkeley, California 94270, United States.
authors.forename: Romy
authors.initials: R
authors.lastname: Chakraborty
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma , Norman, Oklahoma 73019, United States.|CAS Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma , Norman, Oklahoma 73019, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Curtis
authors.affiliation: Center for Biofilm Engineering, Montana State University , Bozeman, Montana 59717, United States.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Fields
authors.affiliation: Department of Civil and Environmental Engineering, The University of Tennessee , Knoxville, Tennessee 37996, United States.|Biosciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831-6342, United States.
authors.forename: Terry C
authors.initials: TC
authors.lastname: Hazen
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Arkin
authors.affiliation: Institute for Environmental Genomics, and Department of Microbiology and Plant Biology, University of Oklahoma , Norman, Oklahoma 73019, United States.|Earth Science Division, Lawrence Berkeley National Laboratory , Berkeley, California 94270, United States.|State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D002857:Chromium / Q000378:metabolism*; D060587:Groundwater / Q000737:chemistry / Q000382:microbiology*; D006859:Hydrogen / Q000378:metabolism; D019344:Lactic Acid / Q000737:chemistry*; D059013:Microbial Consortia / Q000235:genetics / Q000502:physiology*; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D013431:Sulfates / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D009566:Nitrates; D011091:Polyesters; D011108:Polymers; D013431:Sulfates; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D019344:Lactic Acid; C033616:poly(lactide); D006859:Hydrogen