Deep Microbial Life in Granitic Aquifer

Deep granitic aquifer is one of the largest, but least-understood, microbial habitats. This is mainly because it is technically challenging to undisturb microbial habitats in deep rock fractures without drilling contamination from the surface biosphere. To avoid the contamination, underground drillings were conducted for deep granitic basements at the Mizunami underground research laboratory in Japan and at the Grimsel test site in Switzerland. Groundwater samples collected from the underground boreholes were subjected to pyrosequencing to obtain a comprehensive view of biodiversity and to reveal indigenous microbial populations by specifying closely related microorganisms commonly detected from the geographically and geochemically distinct granitic aquifers.