title: Bioreduction of vanadium (V) in groundwater by autohydrogentrophic bacteria: Mechanisms and microorganisms.
abstract: As one of the transition metals, vanadium (V) (V(V)) in trace amounts represents an essential element for normal cell growth, but becomes toxic when its concentration is above 1mg/L. V(V) can alter cellular differentiation, gene expression, and other biochemical and metabolic phenomena. A feasible method to detoxify V(V) is to reduce it to V(IV), which precipitates and can be readily removed from the water. The bioreduction of V(V) in a contaminated groundwater was investigated using autohydrogentrophic bacteria and hydrogen gas as the electron donor. Compared with the previous organic donors, H2 shows the advantages as an ideal electron donor, including nontoxicity and less production of excess biomass. V(V) was 95.5% removed by biochemical reduction when autohydrogentrophic bacteria and hydrogen were both present, and the reduced V(IV) precipitated, leading to total-V removal. Reduction kinetics could be described by a first-order model and were sensitive to pH and temperature, with the optimum ranges of pH7.5-8.0 and 35-40°C, respectively. Phylogenetic analysis by clone library showed that the dominant species in the experiments with V(V) bioreduction belonged to the β-Proteobacteria. Previously known V(V)-reducing species were absent, suggesting that V(V) reduction was carried out by novel species. Their selective enrichment during V(V) bioreduction suggests that Rhodocyclus, a denitrifying bacterium, and Clostridium, a fermenter known to carry out metal reduction, were responsible for V(V) bioreduction.
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, ChinaE-mail: xiaoyinxus@gmail.com; Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, 1001 S. McAllister Ave., Tempe, AZ 85287, USA. Electronic address: xiaoyinxus@gmail.com.
authors: Xiaoyin
authors: X
authors: Xu
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, ChinaE-mail: xiaoyinxus@gmail.com. Electronic address: siqingxia@gmail.com.
authors: Siqing
authors: S
authors: Xia
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, ChinaE-mail: xiaoyinxus@gmail.com.
authors: Lijie
authors: L
authors: Zhou
authors: State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, ChinaE-mail: xiaoyinxus@gmail.com; Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: zhiqiang@tongji.edu.cn.
authors: Zhiqiang
authors: Z
authors: Zhang
authors: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, 1001 S. McAllister Ave., Tempe, AZ 85287, USA.
authors: Bruce E
authors: BE
authors: Rittmann
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D060587:Groundwater / Q000032:analysis* / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D064307:Microbiota; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013696:Temperature; D014639:Vanadium / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D014639:Vanadium
keywords: Bioreduction; Clostridium; Hydrogen; Rhodocyclus; Vanadium