title: Comparative Analysis of Microbial Communities in Iron-Dominated Flocculent Mats in Deep-Sea Hydrothermal Environments.
abstract: It has been suggested that iron is one of the most important energy sources for photosynthesis-independent microbial ecosystems in the ocean crust. Iron-metabolizing chemolithoautotrophs play a key role as primary producers, but little is known about their distribution and diversity and their ecological role as submarine iron-metabolizing chemolithotrophs, particularly the iron oxidizers. In this study, we investigated the microbial communities in several iron-dominated flocculent mats found in deep-sea hydrothermal fields in the Mariana Volcanic Arc and Trough and the Okinawa Trough by culture-independent molecular techniques and X-ray mineralogical analyses. The abundance and composition of the 16S rRNA gene phylotypes demonstrated the ubiquity of zetaproteobacterial phylotypes in iron-dominated mat communities affected by hydrothermal fluid input. Electron microscopy with energy-dispersive X-ray microanalysis and X-ray absorption fine structure (XAFS) analysis revealed the chemical and mineralogical signatures of biogenic Fe-(oxy)hydroxide species and the potential contribution of Zetaproteobacteria to the in situ generation. These results suggest that putative iron-oxidizing chemolithoautotrophs play a significant ecological role in producing iron-dominated flocculent mats and that they are important for iron and carbon cycles in deep-sea low-temperature hydrothermal environments.
  
  
  
  We report novel aspects of microbiology from iron-dominated flocculent mats in various deep-sea environments. In this study, we examined the relationship between Zetaproteobacteria and iron oxides across several hydrothermally influenced sites in the deep sea. We analyzed iron-dominated mats using culture-independent molecular techniques and X-ray mineralogical analyses. The scanning electron microscopy-energy-dispersive X-ray spectroscopy SEM-EDS analysis and X-ray absorption fine structure (XAFS) analysis revealed chemical and mineralogical signatures of biogenic Fe-(oxy)hydroxide species as well as the potential contribution of the zetaproteobacterial population to the in situ production. These key findings provide important information for understanding the mechanisms of both geomicrobiological iron cycling and the formation of iron-dominated mats in deep-sea hydrothermal fields.
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan Department of Applied Chemistry, Faculty of Engineering, Kanagawa Institute of Technology, Atsugi, Kanagawa, Japan makita@jamstec.go.jp.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Makita
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Sakiko
authors.initials: S
authors.lastname: Kikuchi
authors.affiliation: Institute for Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitsunobu
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takaki
authors.affiliation: Department of Earth Sciences, Okayama University, Okayama, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Yamanaka
authors.affiliation: Department of Chemistry, Biology, and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Toki
authors.affiliation: Center for Advanced Marine Core Research, Kochi University, Nankoku, Japan.
authors.forename: Takuroh
authors.initials: T
authors.lastname: Noguchi
authors.affiliation: Department of System Innovation, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Abe
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Hirai
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Section 1 Geochemical Oceanography, Office of Marine Research Department of Marine Science, Marine Works Japan Ltd., Yokosuka, Japan.
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Uematsu
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Miyazaki
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Nunoura
authors.affiliation: Department of Earth Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Japan Agency for Marine-Earth Science & Technology (JAMSTEC), Yokosuka, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takai
mesh_terms: D005290:Ferric Compounds / Q000378:metabolism*; D060086:Hydrothermal Vents / Q000382:microbiology*; D007501:Iron / Q000378:metabolism*; D064307:Microbiota; D010084:Oxidation-Reduction; D010140:Pacific Ocean; D020560:Proteobacteria / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017423:Sequence Analysis, RNA; D056928:X-Ray Absorption Spectroscopy
chemical_list: D005290:Ferric Compounds; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; C000499:ferric oxide; D007501:Iron