Thermococcus sibiricus MM 739

Thermococcus sibiricus (strain MM 739 / DSM 12597) is a hyperthermophilic anaerobic archaeon isolated from a well of the never flooded oil-bearing Jurassic horizon of a high-temperature oil reservoir. T. sibiricus indicate the ability to metabolize the buried organic matter from the original oceanic sediment. Its numerous hydrolytic enzymes (e.g., cellulolytic enzymes, agarase, laminarinase, and lipases) and metabolic pathways, support the proposal of the indigenous origin of T. sibiricus in the oil reservoir, and explain its survival over geologic time and its proliferation in this habitat. Indeed, in addition to proteinaceous compounds known previously to be present in oil reservoirs at limiting concentrations, its growth is stimulated by cellulose, agarose, and triacylglycerides, as well as by alkanes. Two polysaccharide degradation loci are probably acquired by T. sibiricus from thermophilic bacteria following lateral gene transfer events. The first, a "saccharolytic gene island" absent in the genomes of other members of the order Thermococcales, contains the complete set of genes responsible for the hydrolysis of cellulose and beta-linked polysaccharides. The second harbors genes for maltose and trehalose degradation. Moreover, T. sibiricus probably possesses a new mechanism of n-alkane degradation, since its growth is stimulated by hexadecane and no enzymes of currently known pathways are encoded. Not reported so far for hyperthermophilic archaea is the lipolytic growth of T. sibiricus on triacylglycerides. This growth is apparently enabled by the function of an extracellular true lipase(s) encoded by the genome. (Adaptated from PMID:19447963). (HAMAP: THESM)