A metagenomic view of novel microbial and metabolic diversity found within the deep terrestrial biosphere at DeMMO: A microbial observatory in South Dakota, USA.

The deep terrestrial subsurface is a large and diverse microbial habitat and vast repository of biomass. However, in relation to its size and physical heterogeneity we have limited understanding of taxonomic and metabolic diversity in this realm. Here we present a detailed metagenomic analysis of samples from the Deep Mine Microbial Observatory (DeMMO) spanning depths from the surface to 1.

Rock-Hosted Subsurface Biofilms: Mineral Selectivity Drives Hotspots for Intraterrestrial Life.

The continental deep subsurface is likely the largest reservoir of biofilm-based microbial biomass on Earth, but the role of mineral selectivity in regulating its distribution and diversity is unclear. Minerals can produce hotspots for intraterrestrial life by locally enhancing biofilm biomass. Metabolic transformations of minerals by subsurface biofilms may occur widely with the potential to significantly impact subsurface biogeochemical cycles.

Electrochemical evidence for in situ microbial activity at the Deep Mine Microbial Observatory (DeMMO), South Dakota, USA.

The subsurface is Earth's largest reservoir of biomass. Micro-organisms are the dominant lifeforms in this habitat, but the nature of their in situ activities remains largely unresolved. At the Deep Mine Microbial Observatory (DeMMO) located in the Sanford Underground Research Facility (SURF) in Lead, South Dakota (USA), we performed in situ electrochemical incubations designed to assess the potential for deep groundwater microbial communities to utilize extracellular electron transfer to support microbial respiration.

Mineral-hosted biofilm communities in the continental deep subsurface, Deep Mine Microbial Observatory, SD, USA.

Deep subsurface biofilms are estimated to host the majority of prokaryotic life on Earth, yet fundamental aspects of their ecology remain unknown. An inherent difficulty in studying subsurface biofilms is that of sample acquisition. While samples from marine and terrestrial deep subsurface fluids have revealed abundant and diverse microbial life, limited work has described the corresponding biofilms on rock fracture and pore space surfaces.

Biofilm formation and potential for iron cycling in serpentinization-influenced groundwater of the Zambales and Coast Range ophiolites.

Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by probing the relevance of samples acquired at the surface to in situ, subsurface ecosystems, and the nature of microbe-mineral associations in the subsurface.