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Suzuki Y, Yamashita S, Kouduka M, Ao Y, Mukai H, Mitsunobu S, Kagi H, D'Hondt S, Inagaki F, Morono Y, Hoshino T, Tomioka N, Ito M. Deep microbial proliferation at the basalt interface in 33.5-104 million-year-old oceanic crust. Commun Biol 2020; 3:136. [PMID: 32242062 PMCID: PMC7118141 DOI: 10.1038/s42003-020-0860-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 02/27/2020] [Indexed: 11/09/2022] Open
Abstract
The upper oceanic crust is mainly composed of basaltic lava that constitutes one of the largest habitable zones on Earth. However, the nature of deep microbial life in oceanic crust remains poorly understood, especially where old cold basaltic rock interacts with seawater beneath sediment. Here we show that microbial cells are densely concentrated in Fe-rich smectite on fracture surfaces and veins in 33.5- and 104-million-year-old (Ma) subseafloor basaltic rock. The Fe-rich smectite is locally enriched in organic carbon. Nanoscale solid characterizations reveal the organic carbon to be microbial cells within the Fe-rich smectite, with cell densities locally exceeding 1010 cells/cm3. Dominance of heterotrophic bacteria indicated by analyses of DNA sequences and lipids supports the importance of organic matter as carbon and energy sources in subseafloor basalt. Given the prominence of basaltic lava on Earth and Mars, microbial life could be habitable where subsurface basaltic rocks interact with liquid water.
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Affiliation(s)
- Yohey Suzuki
- Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Seiya Yamashita
- Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Mariko Kouduka
- Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yutaro Ao
- Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Hiroki Mukai
- Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Mantle Drilling Promotion Office, Institue for Marine-Earth Exploration and Engineering, JAMSTEC, Showa-machi 3173-25, Kanazawa-ku, Yokohama, 236-0001, Japan
| | - Satoshi Mitsunobu
- Department of Environmental Conservation, Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime, 790-8566, Japan
| | - Hiroyuki Kagi
- Geochemical Research Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan
| | - Steven D'Hondt
- Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI, 02882, USA
| | - Fumio Inagaki
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe B200, Nankoku, Kochi, 783-8502, Japan.,Mantle Drilling Promotion Office, Institue for Marine-Earth Exploration and Engineering, JAMSTEC, Showa-machi 3173-25, Kanazawa-ku, Yokohama, 236-0001, Japan
| | - Yuki Morono
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe B200, Nankoku, Kochi, 783-8502, Japan
| | - Tatsuhiko Hoshino
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe B200, Nankoku, Kochi, 783-8502, Japan
| | - Naotaka Tomioka
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe B200, Nankoku, Kochi, 783-8502, Japan
| | - Motoo Ito
- Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Monobe B200, Nankoku, Kochi, 783-8502, Japan
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