title: Deep-sea methane seep sediments in the Okhotsk Sea sustain diverse and abundant anammox bacteria.
abstract: Marginal sea methane seep sediments sustain highly productive chemosynthetic ecosystems and are hotspots of intense biogeochemical cycling. Rich methane supply stimulates rapid microbial consumption of oxygen; these systems are thus usually hypoxic to anoxic. This and reported evidence for resident nitrogen fixation suggest the presence of an anaerobic ammonium-oxidizing (anammox) bacterial community in methane seep sediments. To test this hypothesis, we employed detection of genes encoding 16S rRNA gene and hydrazine dehydrogenase (hzo) to investigate the structure, abundance and distribution of the anammox bacterial community in the methane seep sediments of the Okhotsk Sea. Diverse complements of Candidatus Scalindua-related 16S rRNA and hzo gene sequences were obtained. Most of the deep-sea sites harbored abundant hzo genes with copy numbers as high as 10(7)  g(-1) sediment. In general, anammox bacterial signatures were significantly more abundant in the deep-water sediments. Sediment porewater NO3-, NOx- (i.e. NO3- + NO2-), NOx-/NH4+ and sediment silt content correlated with in situ distribution patterns of anammox bacterial marker genes, likely because they determine anammox substrate availability and sediment geochemistry, respectively. The abundance and distribution of anammox bacterial gene markers indicate a potentially significant contribution of anammox bacteria to the marine N cycle in the deep-sea methane seep sediments.
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen, China; Department of Ocean Science and Engineering, Zhejiang University, Hangzhou, China; State Key Laboratory of Heavy Oil Processing, Key Laboratory of Bioengineering and Biotechnology in Universities of Shandong, Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, China.
authors.forename: Sudong
authors.initials: S
authors.lastname: Shao
authors.forename: Xiwu
authors.initials: X
authors.lastname: Luan
authors.forename: Hongyue
authors.initials: H
authors.lastname: Dang
authors.forename: Haixia
authors.initials: H
authors.lastname: Zhou
authors.forename: Yakun
authors.initials: Y
authors.lastname: Zhao
authors.forename: Haitao
authors.initials: H
authors.lastname: Liu
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lingqing
authors.initials: L
authors.lastname: Dai
authors.forename: Ying
authors.initials: Y
authors.lastname: Ye
authors.forename: Martin G
authors.initials: MG
authors.lastname: Klotz
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis; D001419:Bacteria / Q000145:classification* / Q000235:genetics; D001483:Base Sequence; D044822:Biodiversity; D005798:Genes, Bacterial; D020459:Genes, rRNA; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D008697:Methane; D008969:Molecular Sequence Data; D009566:Nitrates / Q000032:analysis; D009573:Nitrites / Q000032:analysis; D009792:Oceans and Seas; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014871:Water Microbiology
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; D008697:Methane
keywords: Candidatus Scalindua; Okhotsk Sea; anammox; cold seep; hydrazine oxidoreductase gene hzo; methane hydrate