Sulfate-reducing bacteria in formation waters of the pressure maintenance system of Ust-Tegussky oil deposit

An analysis of Ust-Tegussky oil-field formation waters is conducted, the cultures of sulfate-reducing bacteria (SRB) are isolated from these waters, and their taxonomic status is determined. The formation waters used for the maintenance of intrasheeted pressure on the Ust-Tegussky field are characterized by moderate mineralization (23.2 g/L) and contain sulfate (8.4 mg/L). The sulfate-reducing enrichment culture was isolated from the studied waters and contained three bacterial strains by results of TGGE. Fragments of 16S rRNA genes of strains Y1 and Y2 are genetically close to Desulfovibrio alaskensis and D. psychrotolerans with a similarity of 99.0 and 95.0%, respectively. Strain Y2 is isolated in pure culture and partially characterized. A phylogenetic analysis of almost a full sequence of 16S rRNA gene of strain Y2 has shown that, out of all known species, it is closest to the strain type of D. psychrotolerans isolated from the saline lake and the similarity of 96.5% suggests a description of a new species. It is shown that the new SRB are inhabitants of the formation waters arriving with extracted oil.