2026-07-29 ミシガン大学
A study led by University of Michigan researchers found that organic-rich rocks and water deep below ground teem with life: they are packed with fungi and other tiny organisms. Image credit: John Megahan, University of Michigan
＜関連情報＞
- https://news.umich.edu/rock-eating-fungi-flourish-deep-below-our-feet/
- https://academic.oup.com/ismej/advance-article/doi/10.1093/ismejo/wrag184/8744037
地下深部の有機物に富んだ頁岩は、豊富で多様な、そして新しい菌類を育んでいる Deep subsurface organic-rich shale supports abundant, diverse, and novel fungi
Quinn S Moon,Elliott P Barnhart,Matthew S Varonka,Elizabeth J Tomaszewski,Michelle Orozco-Quime,Thomas Desrosiers,Ivan Paciorka,Michael Carley,James Schramski,Bradley S Stevenson,…
The ISME Journal Published: 29 July 2026
DOI:https://doi.org/10.1093/ismejo/wrag184
Abstract
As Earth’s principal reservoir of organic carbon and microbial biomass, the deep subsurface hosts microorganisms capable of mobilizing this once-sequestered carbon. Contrary to standard assumptions of eukaryotic scarcity, this study documents abundant fungal communities, ranging from 4.2 × 103 to 6.8 × 103 fungal cells mL−1, across a methane-producing organic-rich shale 247–556 meters below the surface. Although fungal:bacterial cell ratios ranged from 1:7028 to 1:713, application of biomass conversion factors developed for oceanic systems yielded a median fungal:bacterial biomass ratio of 1:4.7. 16S rRNA gene amplicons revealed bacterial and archaeal communities mirroring those found in well-characterized extremophilic, carbon-degrading environments, while sequencing of 18S rRNA gene and ITS rRNA spacer amplicons collectively identified a eukaryotic hotspot with 689 fungal OTUs across six phyla. The dominant fungal classes, Agaricomycetes and Dothideomycetes, are well-established degraders of recalcitrant carbon compounds at the surface, suggesting they may similarly contribute to organic matter degradation and ecosystem maintenance in the subsurface. Cultivation and isolation efforts yielded 205 fungal strains, including 13 candidate novel taxa, underscoring the deep subsurface as an underexplored eukaryotic habitat. Stable carbon isotopes indicate methane is predominantly generated via microbial conversion of the fossil carbon, while water isotopes suggest in situ geochemical conditions have been relatively stable since the Late Pleistocene, with subglacial recharge as a plausible mechanism for microbial introduction. Collectively, these findings suggest that fungi are underrecognized contributors to organic matter transformation and functional diversity in the deep biosphere, revealing a critical gap in our understanding of deep subsurface ecosystem processes.
