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Geomicrobiology Group

Deep marine subsurface environment is the least unexplored biosphere on Earth. Recent studies of sediment core samples revealed that the deep subseafloor biosphere harbors remarkable number of microbial life, most of which are phylogenetically distinct from previously cultured microbes, hence their growth characteristics as well as the ecological roles remain largely unknown. One of the challenges is to comprehend the Geosphere-Biosphere interaction. The population and activity of subseafloor life depends mainly on the supply of bio-available nutrient and energy substrates from the overlying surface world (i.e., land and ocean) and/or the underlying lithosphere (i.e., earth's crust and mantle). Hence, the fluid flow regimes and geophysical conditions must play significant roles for the nutrient and energy transportation, affecting the probability of the habitable zone and ecosystem. The physical and chemical constraints represent the adaptation and evolution of subseafloor life during the earth's history. In the Geomicrobiology Group, we study the extent of the deep subseafloor biosphere using a newly developed cell detection and enumeration system. Using molecular ecological techniques as well as isotopic analyses, we also study the diversity and metabolic functioning of yet-to-be-identified, diverse subseafloor life living in the deep subseafloor sediments under the various oceanographic and geologic settings.

A scanning electron micrograph shows three spherical, very small cell-like structures in marine subsurface sediments collected by Chikyu off Japan. The phylogenetic affiliation as well as growth and metabolic characteristics of the subseafloor life are largely unknown.


Group Leader
Fumio Inagaki
Deputy Group Leader
Yuki Morono
Senior Scientist
Tatsuhiko Hoshino
Senior Scientist
Akira Ijiri
Postdoctoral Researcher
Yoko Ohtomo
Postdoctoral Researcher
Go-ichiro Uramoto


  • Morono, Y., Inagaki, F. (2010) Automatic slide-loader fluorescent microscope for discriminative enumeration of subseafloor life, Scientific Drilling, in press.
  • Stainsbu, B.O., Thorseth, I.H., Nakagawa, S., Inagaki, F., Lever, M.A., Engelen, B., Øveås, L., Pedersen, R.B.(2010) Archaeoglobus sulfaticallidus. sp.nopv., a novel thermophilic and facultative lithoautotrophic sulfate-reducer isolated from black rust exposed to hot ridge flank crustal fluids. Int. J. Syst. Envol. Microbiol. in press.
  • Hoshino, T., Schramm. A. (2010) Detection of Denitrification Genes by in situ Rolling Circle Amplification-Fluorescence in situ Hybridization ( in situ RCA-FISH) to link Metabolic Potential with Identity inside Bacterial Cells, Environ. Microbiol. in press.
  • Yanagawa, K., Sunamura, M., Lever, M.A., Morono, Y., Hiruta, A., Matsumoto, R., Urabe, T., Inagaki, F.(2010) Niche separation of anaerobic methanotrophs (ANME-1 and -2)?in methane seep-sediments in the eastern Japan Sea off Joetsu, Geomicrobiol. J., in press.
  • Lever, M., Heuer, V., Morono, Y., Masui, N., Schmidt, F., Alperin, M., Inagaki, F., Hinrichs, K.-U., Teske, A.(2010) Acetogenesis in deep subseafloor sediments of the Juan de Fuca Ridge Flank: a synthesis in the eastern Japan Sea off Joetsu, Geomicrobiol. J., in press.
  • Inagaki F. (2010) Deep subseafloor microbial communities. In : Encyclopedia of life Sciences, John Wiley & Sons, Ltd., Chichester, doi:10.1002/9780470015902.a0021894..


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