Thermococcus sibiricus is a hyperthermophilic anaerobic archaeon isolated from a well of the never flooded oil-bearing Jurassic horizon of Samotlor (Western Siberia) high-temperature oil reservoir. Representatives of the Order Thermococcales are widely distributed in terrestrial and marine hydrothermal areas, as well as in deep subsurface oil reservoirs. These are coccoid organisms with a fermentative metabolism that grow on peptide, polysaccharids or sugar at the optimal temperature 80-85°C. Recently obtained genomic data, confirmed by physiological experiments revealed that T.sibiricus posesses novel, unusual for other Thermococcus species metabolic features. Indeed, in addition to proteinaceous compounds known previously to be present in oil reservoirs at limiting amounts, T.sibiricus capable of using for its growth cellulose, agarose, triacylglycerids, as well as alcanes. This data indicate the ability of T,sibiricus to metabolize the buried organic matter from the original oceanic sediments and explain its survival and proliferation over geologic time in this habitat.
