Strain Z1-71^T breaks down glucose to produce hydrogen and formate (a low-molecular-weight organic compound). Methanogenic strain T10^T produces methane using either hydrogen and carbon dioxide or formate. Methane production was observed only when the two strains were cultured together, suggesting that similar transfers of hydrogen and formate may also occur underground at Horonobe.

The deep subsurface is home to a diverse range of microorganisms, many of which remain unknown. Because it is difficult to collect samples and cultivate microorganisms in deep subsurface environments where oxygen is scarce, how these microorganisms live and what substances they produce remain poorly understood.

At the Horonobe Underground Research Center, we took advantage of the underground research facility, which allows deep groundwater to be sampled, to investigate microorganisms in collaboration with the Horonobe Research Institute for the Subsurface Environment and Hiroshima University. In addition to culture experiments, we analyzed the genes needed to identify the microorganisms and their complete genetic information (genomes). This led to the discovery of Gaoshiqia hydrogeniformans strain Z1-71^T, a novel microorganism that produces hydrogen and formate.

This microorganism breaks down glucose to produce hydrogen and formate. When strain Z1-71^T was cultured together with methanogenic strain T10^T, isolated from the same geological formation, strain T10^T used the hydrogen and formate produced by strain Z1-71^T to generate biomethane (methane produced through microbial activity). Under the conditions used in this study, methane was not detected when the two strains were cultured separately, showing that the transfer of hydrogen and formate from strain Z1-71^T to strain T10^T led to methane production (Fig. 1).

These findings advance our understanding of the microorganisms responsible for the production and consumption of hydrogen, formate, and methane, and may be useful, for example, in evaluating how reducing conditions recover after the closure of underground facilities for geological disposal.

Furthermore, underground research facilities can be used to explore previously unknown microbial resources, potentially leading to technologies that harness microbial activity to produce energy resources efficiently.

This study was conducted in collaboration with the Honorobe Research Institute for the Subsurface Environment (H-RISE) and Hiroshima University.

Paper URL: https://doi.org/10.1099/ijsem.0.006802

Press Releas: 北海道・道北の陸域深部地下環境から水素を発生する新種の微生物を発見 (Gaoshiqia hydrogeniformans Z1-71^T株の発見) (in Japanese)

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