HOT SUBTERRANEAN BIOSPHERE IN A CONTINENTAL OIL-RESERVOIR

THE presence of high concentrations of hyperthermophilic archaea in Al askan oil fields has been attributed to viable hyperthermophiles in lo w concentrations in the injected sea water, but the existence of an in digenous community within the reservoir was ruled out(1). Here we pres ent evidence for the existence of indigenous thermophilic bacteria and hyperthermophilic archaea from a continental petroleum reservoir abou t 1,670 m below the surface. The thermophilic isolates were repeatedly obtained from different wells and thrived in media similar to conditi ons in the wells, suggesting that these isolates are members of a deep indigenous thermophilic community. The unexpected presence of marine hyperthermophilic archaea in a deep continental environment extends th e known ecological habitat of this group of organisms, and their unusu al coexistence with terrestrial bacteria suggests that thermophiles ma y be widespread deep in the crust of the earth.