2026-06-03 ノースウェスタン大学
＜関連情報＞
- https://news.northwestern.edu/stories/2026/06/organized-microbial-workforces-keep-earths-underground-biosphere-running
- https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2025JG009515
深部鉱山微生物観測所（DeMMO）における4年間にわたる、不均質な陸上深部生物圏の微生物生態学 Microbial Ecology of the Heterogeneous Terrestrial Deep Biosphere Over 4 years in the Deep Mine Microbial Observatory (DeMMO)
Magdalena R. Osburn, Caitlin P. Casar, Bradley S. Stevenson, Matthew Selensky, Brittany Kruger, Lily M. Momper, Theodore M. Flynn, Jan P. Amend
Journal of Geophysical Research: Biogeosciences Published: 03 June 2026
DOI:https://doi.org/10.1029/2025JG009515
Abstract
The deep continental subsurface hosts a large, diverse, and poorly characterized microbiome. The geochemistry and microbiology of deep subsurface sites are closely linked and influenced by geological, hydrological, and anthropogenic factors. The Deep Mine Microbial Observatory (DeMMO; Lead, SD) was established in 2015 to provide stable portals into this biome across depth. Fracture fluid geochemistry here varies by borehole, but remains consistent over time (Osburn et al., 2019, https://doi.org/10.3389/feart.2019.00196). Here we report on planktonic microbial populations at DeMMO over 4 years as viewed by 16S rRNA gene sequencing. We contextualize this dataset with network analysis and metagenomics (Momper et al., 2023, https://doi.org/10.1111/1462-2920.16543). We find that DeMMO is home to diverse microorganisms whose membership varies strongly by site but is coherent over time. Network analysis and edge betweenness clustering confirms this regionality and reveals eight large groups that are ubiquitous across sites and prevalent in >85% of samples, although individual taxa are far less cosmopolitan, with no single amplicon sequence variant occurring ubiquitously. Site-specific networks reveal the co-occurrence of diverse, prevalent taxa, constituting site-level core microbiomes. These core microbiomes are enriched in uncultivated lineages with diverse metabolic potential based on metagenomic information, many of which are positively correlated with increasing alpha diversity. Taxa with high temporal variability derive from a subset of phyla, particularly the Gammaproteobacteria, Ignavibacterota, Firmicutes, and Nitrospirota and are enriched in functional potential for cycling nitrogen, sulfur, and metal species. This compilation represents a major step forward in understanding the geomicrobiology of a unique deep subsurface site over years in a geochemical context.
Plain Language Summary
The microorganisms that live deep underground make up 20% of life on Earth yet are poorly understood due to their relative inaccessibility. Taking advantage of mine infrastructure, we collected microorganisms from fluids from 250 to 1,500 m underground over the course of 4 years. We found that the microorganisms in these waters were different in each site but mostly consistent with time. As each site was different, we found no ubiquitous organisms or communities that define a generalizable subsurface core microbiome. Instead, each site had its own core community. Comparing site-level core communities reveals many functionally or genetically similar organisms, many of which have the genes to convert CO2 into organic carbon, suggesting a key ecosystem role for these organisms. Some microorganisms do change in relative abundance through time and often have the necessary genes to cycle nitrogen, sulfur, and metals. By viewing microbiology in the context of geochemistry and genetic potential, we can begin to understand how the subsurface serves as a habitat for the rich diversity of life that resides there.
