title: Ecophysiology of Zetaproteobacteria Associated with Shallow Hydrothermal Iron-Oxyhydroxide Deposits in Nagahama Bay of Satsuma Iwo-Jima, Japan.
abstract: Previous studies of microbial communities in deep-sea hydrothermal ferric deposits have demonstrated that members of Zetaproteobacteria play significant ecological roles in biogeochemical iron-cycling. However, the ecophysiological characteristics and interaction between other microbial members in the habitat still remain largely unknown. In this study, we investigated microbial communities in a core sample obtained from shallow hydrothermal iron-oxyhydroxide deposits at Nagahama Bay of Satsuma Iwo-Jima, Japan. Scanning electron microscopic observation showed numerous helical stalk structures, suggesting the occurrence of iron-oxidizing bacteria. Analysis of 16S rRNA gene sequences indicated the co-occurrence of iron-oxidizing Zetaproteobacteria and iron-reducing bacteria such as the genera Deferrisoma and Desulfobulbus with strong correlations on the sequence abundance. CARD-FISH indicated that the numbers of Zetaproteobacteria were not always consistent to the frequency of stalk structures. In the stalk-abundant layers with relatively small numbers of Zetaproteobacteria cells, accumulation of polyphosphate was observed inside Zetaproteobacteria cells, whereas no polyphosphate grains were observed in the topmost layers with fewer stalks and abundant Zetaproteobacteria cells. These results suggest that Zetaproteobacteria store intracellular polyphosphates during active iron oxidation that contributes to the mineralogical growth and biogeochemical iron cycling.
authors.affiliation: Japan Agency for Marine-Earth Science Technology, Kochi Institute for Core Sample ResearchNankoku, Japan; Japan Agency for Marine-Earth Science Technology, Research and Development Center for Submarine ResourcesNankoku, Japan.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Hoshino
authors.affiliation: Department Earth and Planetary Sciences, Kyushu University Fukuoka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kuratomi
authors.affiliation: Japan Agency for Marine-Earth Science Technology, Kochi Institute for Core Sample ResearchNankoku, Japan; Japan Agency for Marine-Earth Science Technology, Research and Development Center for Submarine ResourcesNankoku, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Morono
authors.affiliation: Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology Tsukuba, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hori
authors.affiliation: Mishimamura Village Kagoshima, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Oiwane
authors.affiliation: Department Earth and Planetary Sciences, Kyushu University Fukuoka, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Kiyokawa
authors.affiliation: Japan Agency for Marine-Earth Science Technology, Kochi Institute for Core Sample ResearchNankoku, Japan; Japan Agency for Marine-Earth Science Technology, Research and Development Center for Submarine ResourcesNankoku, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Inagaki
keywords: MiSeq Illumina; fluorescence in situ hybridization (FISH); iron cycle; iron-oxidizing bacteria; network analysis; polyphosphates granules; shallow hydrothermal vents; zetaproteobacteria