The Rock-Hosted Biosphere

Our understanding of Earth's rock-hosted subsurface biosphere has advanced over the past two decades through collection and analysis fluids rocks from aquifers within continental oceanic crust. Improvements in cell extraction, sorting, DNA sequencing, techniques for detecting distributions activity have revealed how combination lithology, permeability, fluid mixing processes controls diversity heterogeneous distribution microbial communities fractured rock systems. However, functions most organisms, rates their growth, remain largely unknown. To mechanistically understand what physiochemical hydrological factors control biosphere, future studies are needed to characterize physiology microorganisms adapted mineral-associated growth under energy- nutrient-limited conditions. Experiments should be designed detect synergistic interactions between microorganisms, minerals, at highly variable turnover rates. ▪ The is controlled by variations porosity, chemical disequilibrium. Several imaging can sensitively biosphere. poorly known.