title: Potential for biogeochemical cycling of sulfur, iron and carbon within massive sulfide deposits below the seafloor.
abstract: Seafloor massive sulfides are a potential energy source for the support of chemosynthetic ecosystems in dark, deep-sea environments; however, little is known about microbial communities in these ecosystems, especially below the seafloor. In the present study, we performed culture-independent molecular analyses of sub-seafloor sulfide samples collected in the Southern Mariana Trough by drilling. The depth for the samples ranged from 0.52 m to 2.67 m below the seafloor. A combination of 16S rRNA and functional gene analyses suggested the presence of chemoautotrophs, sulfur-oxidizers, sulfate-reducers, iron-oxidizers and iron-reducers. In addition, mineralogical and thermodynamic analyses are consistent with chemosynthetic microbial communities sustained by sulfide minerals below the seafloor. Although distinct bacterial community compositions were found among the sub-seafloor sulfide samples and hydrothermally inactive sulfide chimneys on the seafloor collected from various areas, we also found common bacterial members at species level including the sulfur-oxidizers and sulfate-reducers, suggesting that the common members are widely distributed within massive sulfide deposits on and below the seafloor and play a key role in the ecosystem function.
authors.affiliation: Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan; Japan Collection of Microorganisms, RIKEN BioResource Center, 3-1-1 Koyadai, Tsukuba, Ibaraki, 305-0074, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kato
authors.forename: Kei
authors.initials: K
authors.lastname: Ikehata
authors.forename: Takazo
authors.initials: T
authors.lastname: Shibuya
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Urabe
authors.forename: Moriya
authors.initials: M
authors.lastname: Ohkuma
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamagishi
mesh_terms: D001105:Archaea / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D002244:Carbon / Q000737:chemistry*; D017753:Ecosystem; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry / Q000382:microbiology*; D007501:Iron / Q000737:chemistry*; D064307:Microbiota / Q000235:genetics* / Q000502:physiology; D009792:Oceans and Seas; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013440:Sulfides / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry*
chemical_list: D012336:RNA, Ribosomal, 16S; D013440:Sulfides; D013455:Sulfur; D002244:Carbon; D007501:Iron