title: Anaerobic Oxidation of Methane Coupled to Nitrite Reduction by Halophilic Marine NC10 Bacteria.
abstract: Anaerobic oxidation of methane (AOM) coupled to nitrite reduction is a novel AOM process that is mediated by denitrifying methanotrophs. To date, enrichments of these denitrifying methanotrophs have been confined to freshwater systems; however, the recent findings of 16S rRNA and pmoA gene sequences in marine sediments suggest a possible occurrence of AOM coupled to nitrite reduction in marine systems. In this research, a marine denitrifying methanotrophic culture was obtained after 20 months of enrichment. Activity testing and quantitative PCR (qPCR) analysis were then conducted and showed that the methane oxidation activity and the number of NC10 bacteria increased correlatively during the enrichment period. 16S rRNA gene sequencing indicated that only bacteria in group A of the NC10 phylum were enriched and responsible for the resulting methane oxidation activity, although a diverse community of NC10 bacteria was harbored in the inoculum. Fluorescence in situ hybridization showed that NC10 bacteria were dominant in the enrichment culture after 20 months. The effect of salinity on the marine denitrifying methanotrophic culture was investigated, and the apparent optimal salinity was 20.5‰, which suggested that halophilic bacterial AOM coupled to nitrite reduction was obtained. Moreover, the apparent substrate affinity coefficients of the halophilic denitrifying methanotrophs were determined to be 9.8 ± 2.2 μM for methane and 8.7 ± 1.5 μM for nitrite.
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Zhanfei
authors.initials: Z
authors.lastname: He
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Geng
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Cai
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Yawei
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Lou
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou, China blhu@zju.edu.cn.
authors.forename: Baolan
authors.initials: B
authors.lastname: Hu
mesh_terms: D000693:Anaerobiosis; D059001:Aquatic Organisms / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D016000:Cluster Analysis; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D019015:Geologic Sediments / Q000382:microbiology; D008697:Methane / Q000378:metabolism*; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000378:metabolism
chemical_list: D004275:DNA, Ribosomal; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride; D008697:Methane