[Physiological and phylogenetic diversity of thermophilic spore-forming hydrocarbon-oxidizing bacteria from oil fields].

The distribution and population density of aerobic hydrocarbon-oxidizing bacteria in the high-temperature oil fields of Western Siberia, Kazakhstan, and China were studied. Seven strains of aerobic thermophilic spore-forming bacteria were isolated from the oil fields and studied by microbiological and molecular biological methods. Based on the 16S rRNA gene sequences, phenotypic characteristics, and the results of DNA-DNA hybridization, the taxonomic affiliation of the isolates was tentatively established. The strains were assigned to the first and fifth subgroups of the genus Bacillus on the phylogenetic branch of the gram-positive bacteria. Strains B and 421 were classified as B. licheniformis. Strains X and U, located between B. stearothermophilus and B. thermocatenulatus on the phylogenetic tree, and strains K, Sam, and 34, related but not identical to B. thermodenitrificans and B. thermoleovorans, undoubtedly represent two new species. Phylogenetically and metabolically related representatives of thermophilic bacilli were found to occur in geographically distant oil fields.