DATE2025.10.01 #Press Releases
Discovery of a Hydrogen-Dependent Subsurface Biosphere Beneath the Itoigawa–Shizuoka Tectonic Line
-Exploring Water–Rock–Microbe Interactions Driven by Hydrogen at a Plate Boundary-
Summary
Dr. Yoshinori Takano, Director of the Research Center for Bioscience and Geoscience at the Japan Agency for Marine-Earth Science and Technology (JAMSTEC; President: Hiroyuki Yamato), together with Mr. Hiroki Nishimura (then graduate student, now at RIKEN) and Prof. Yoshio Takahashi of the Department of Earth and Planetary Science, School of Science, The University of Tokyo (President: Teruo Fujii), as well as Assistant Prof. Atsushi Urai of the Faculty of Science, Shinshu University (President: Soichiro Nakamura), and Prof. Yusuke Yokoyama of the Atmosphere and Ocean Research Institute, The University of Tokyo, conducted joint research on groundwater samples collected from the Suwa Basin in Nagano Prefecture. Through geochemical and microbiological analyses, they clarified the composition and distribution of subsurface microbial ecosystems and revealed the material cycles extending from 10 to 1,000 meters underground.
The Suwa Basin lies on the Itoigawa–Shizuoka Tectonic Line, known as the boundary between the North American Plate and the Eurasian Plate, and is famous for its numerous hot springs. Our previous studies on Lake Suwa showed that methane emitted from the lake bottom originates from deep microbial processes, and that this methane serves as a significant carbon source for the lake ecosystem (reported June 15, 2022). These findings strongly suggested the presence of subsurface microbial ecosystems sustained by methane production and/or methane oxidation in the deep subsurface of the Suwa Basin. However, the diversity of microbial communities in the subsurface and the mechanisms of material cycling that constrain them had remained largely unexplored.
In this study, we carried out a comprehensive analysis of microbial communities in groundwater and hot spring water from the Suwa Basin. We found that sedimentary layers rich in organic matter are dominated by methane-oxidizing bacteria, while hot spring waters from deep basement rock layers (up to ~1,000 m depth) associated with heat sources are dominated by hydrogenotrophic bacteria and archaea that gain energy by oxidizing hydrogen. In addition, by using chemical tracers to characterize water circulation, including radiocarbon isotope analyses, we clarified the spatiotemporal flow processes of meteoric water and groundwater in the Suwa Basin. These findings are expected to significantly advance our understanding of the interactions between hydrogen supplied by fault activity at plate boundaries and microbial ecosystems in the subsurface environment.
This research is part of a collaborative study between JAMSTEC and Shinshu University. The results were published on October 1 (JST) in the scientific journal Progress in Earth and Planetary Science, issued by the Japan Geoscience Union (JpGU).
Figure：(A) Location of the Suwa Basin (square), the Itoigawa–Shizuoka Tectonic Line (ISTL), and the Median Tectonic Line (MTL). (B) Detailed map of the Suwa Basin. (Adapted from maps issued by the Geospatial Information Authority of Japan)
Links
Japan Agency for Marine-Earth Science and Technology（JAMSTEC）, Shinshu University, Atmosphere and Ocean Research Institute, The University of Tokyo
Journals
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Journal name Progress in Earth and Planetary ScienceTitle of paper