title: Abundance of Zetaproteobacteria within crustal fluids in back-arc hydrothermal fields of the Southern Mariana Trough.
abstract: To extend knowledge of subseafloor microbial communities within the oceanic crust, the abundance, diversity and composition of microbial communities in crustal fluids at back-arc hydrothermal fields of the Southern Mariana Trough (SMT) were investigated using culture-independent molecular techniques based on 16S rRNA gene sequences. Seafloor drilling was carried out at two hydrothermal fields, on- and off-ridge of the back-arc spreading centre of the SMT. 16S rRNA gene clone libraries for bacterial and archaeal communities were constructed from the fluid samples collected from the boreholes. Phylotypes related to Thiomicrospira in the Gammaproteobacteria (putative sulfide-oxidizers) and Mariprofundus in the Zetaproteobacteria (putative iron-oxidizers) were recovered from the fluid samples. A number of unique archaeal phylotypes were also recovered. Fluorescence in situ hybridization (FISH) analysis indicated the presence of active bacterial and archaeal populations in the fluids. The Zetaproteobacteria accounted for up to 32% of the total prokaryotic cell number as shown by FISH analysis using a specific probe designed in this study. Our results lead to the hypothesis that the Zetaproteobacteria play a role in iron oxidation within the oceanic crust.
authors.affiliation: Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kato
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yanagawa
authors.forename: Michinari
authors.initials: M
authors.lastname: Sunamura
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takano
authors.forename: Jun-ichiro
authors.initials: J
authors.lastname: Ishibashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kakegawa
authors.forename: Motoo
authors.initials: M
authors.lastname: Utsumi
authors.forename: Toshiro
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Toki
authors.forename: Takuroh
authors.initials: T
authors.lastname: Noguchi
authors.forename: Kensei
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Arimichi
authors.initials: A
authors.lastname: Moroi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kimura
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kawarabayasi
authors.forename: Katsumi
authors.initials: K
authors.lastname: Marumo
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Urabe
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamagishi
mesh_terms: D001483:Base Sequence; D017753:Ecosystem; D019015:Geologic Sediments / Q000382:microbiology*; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010140:Pacific Ocean; D010802:Phylogeny; D020560:Proteobacteria / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S; D012623:Seawater / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S; D007501:Iron