title: Cr(VI) reduction coupled with anaerobic oxidation of methane in a laboratory reactor.
abstract: The process of anaerobic oxidation of methane (AOM) is globally important because of its contribution to the carbon cycle in the environment. Besides, microorganisms play important roles in the environmental fate of chromium. However, there have been no studies to date on the interaction between methane and chromium in batch reactor systems. In this study, biological Cr(VI) reduction was investigated using methane as the sole electron donor. Isotopic (13)CH4 in the batch experiments and long-term performance in the reactor demonstrated that Cr(VI) reduction is coupled with methane oxidation. High-throughput sequencing of the 16S rRNA genes demonstrated that the microbial community had changed substantially after Cr(VI) reduction. The populations of ANME-2d archaea were enhanced, and they became the only predominant AOM-related microbe. Interestingly, other bacteria with significant increases in abundance were not reported as having the ability to reduce Cr(VI). According to these results, two mechanisms were proposed: 1) Cr(VI) is reduced by ANME-2d alone; 2) Cr(VI) is reduced by unknown Cr(VI)-reducing microbes coupled with ANME-2d. This study revealed the potential relationship between Cr(VI) reduction and CH4 oxidation, and extended our knowledge of the relationship between the AOM process and biogeochemical cycles.
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
authors.forename: Yong-Ze
authors.initials: YZ
authors.lastname: Lu
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Fu
authors.affiliation: Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ding
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
authors.forename: Zhao-Wei
authors.initials: ZW
authors.lastname: Ding
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: CAS Key Laboratory for Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China, Hefei 230026, China; Advanced Laboratory for Environmental Research and Technology, USTC-CityU, Suzhou 215123, China. Electronic address: rzeng@ustc.edu.cn.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Zeng
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000235:genetics; D001419:Bacteria / Q000235:genetics; D008697:Methane; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics*
chemical_list: D012336:RNA, Ribosomal, 16S; D008697:Methane
keywords: ANME-2d archaea; Anaerobic oxidation of methane; Biogeochemical cycles; Chromium reduction; Coupling process; Microbial analysis