title: Evidence for nitrite-dependent anaerobic methane oxidation as a previously overlooked microbial methane sink in wetlands.
abstract: The process of nitrite-dependent anaerobic methane oxidation (n-damo) was recently discovered and shown to be mediated by "Candidatus Methylomirabilis oxyfera" (M. oxyfera). Here, evidence for n-damo in three different freshwater wetlands located in southeastern China was obtained using stable isotope measurements, quantitative PCR assays, and 16S rRNA and particulate methane monooxygenase gene clone library analyses. Stable isotope experiments confirmed the occurrence of n-damo in the examined wetlands, and the potential n-damo rates ranged from 0.31 to 5.43 nmol CO2 per gram of dry soil per day at different depths of soil cores. A combined analysis of 16S rRNA and particulate methane monooxygenase genes demonstrated that M. oxyfera-like bacteria were mainly present in the deep soil with a maximum abundance of 3.2 × 10(7) gene copies per gram of dry soil. It is estimated that ∼0.51 g of CH4 m(-2) per year could be linked to the n-damo process in the examined wetlands based on the measured potential n-damo rates. This study presents previously unidentified confirmation that the n-damo process is a previously overlooked microbial methane sink in wetlands, and n-damo has the potential to be a globally important methane sink due to increasing nitrogen pollution.
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors.forename: Bao-lan
authors.initials: BL
authors.lastname: Hu
authors.forename: Li-dong
authors.initials: LD
authors.lastname: Shen
authors.forename: Xu
authors.initials: X
authors.lastname: Lian
authors.forename: Qun
authors.initials: Q
authors.lastname: Zhu
authors.forename: Shuai
authors.initials: S
authors.lastname: Liu
authors.forename: Qian
authors.initials: Q
authors.lastname: Huang
authors.forename: Zhan-fei
authors.initials: ZF
authors.lastname: He
authors.forename: Sha
authors.initials: S
authors.lastname: Geng
authors.forename: Dong-qing
authors.initials: DQ
authors.lastname: Cheng
authors.forename: Li-ping
authors.initials: LP
authors.lastname: Lou
authors.forename: Xiang-yang
authors.initials: XY
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.forename: Yun-feng
authors.initials: YF
authors.lastname: He
mesh_terms: D000693:Anaerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D008697:Methane / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D053833:Wetlands
chemical_list: D012336:RNA, Ribosomal, 16S; D008697:Methane
keywords: activity; methane cycle; overlooked methane sink