Variability in microbial community and venting chemistry in a sediment-hosted backarc hydrothermal system: Impacts of subseafloor phase-separation

Satoshi Nakagawa, Ken Takai, Fumio Inagaki, Hitoshi Chiba, Jun Ichiro Ishibashi, Satoshi Kataoka, Hisako Hirayama, Takuro Nunoura, Koki Horikoshi, Yoshihiko Sako

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126 Citations (Scopus)


Phase-separation and -segregation (boiling/distillation of subseafloor hydrothermal fluids) represent the primary mechanisms causing intra-field variations in vent fluid compositions. To determine whether this geochemical process affects the formation of microbial communities, we examined the microbial communities at three different vent sites located within a few tens meters of one another. In addition to chimney structures, colonization devices capturing subseafloor communities entrained by the vent fluids were studied, using culture-dependent and -independent methods. Microbiological analyses demonstrated the occurrence of distinctive microbial communities in each of the hydrothermal niches. Within a chimney structure, there was a transition from a mixed community of mesophiles and thermophiles in the exterior parts to thermophiles in the interior. Beside the transition within a chimney structure, intra-field variations in microbial communities in vent fluids were apparent. Geochemical analysis demonstrated that different vent fluids have distinctive end-member compositions as a consequence of subseafloor phase-separation and -segregation, which were designated gas-depleted, normal and gas-enriched fluids. In comparison to gas-depleted and normal fluids, gas-enriched fluids harbored more abundant chemolithoautotrophs with gaseous component-dependent energy metabolism, such as hydrogenotrophic methanogenesis. Subseafloor phase-separation and -segregation may play a key role in supplying energy and carbon sources to vent-associated chemolithoautotrophs and subvent microbial communities.

Original languageEnglish
Pages (from-to)141-155
Number of pages15
JournalFEMS microbiology ecology
Issue number1
Publication statusPublished - Sep 1 2005



  • Backarc hydrothermal system
  • Chemolithoautotroph
  • Culturability
  • Epsilonproteobacteria
  • Methanogen
  • Phase-separation

ASJC Scopus subject areas

  • Microbiology
  • Ecology
  • Applied Microbiology and Biotechnology

Cite this

Nakagawa, S., Takai, K., Inagaki, F., Chiba, H., Ishibashi, J. I., Kataoka, S., Hirayama, H., Nunoura, T., Horikoshi, K., & Sako, Y. (2005). Variability in microbial community and venting chemistry in a sediment-hosted backarc hydrothermal system: Impacts of subseafloor phase-separation. FEMS microbiology ecology, 54(1), 141-155.