Phenotypic and Genomic Characterization of a Sulfate-Reducing Bacterium Pseudodesulfovibrio methanolicus sp. nov. Isolated from a Petroleum Reservoir in Russia

The search for the microorganisms responsible for sulfide formation and corrosion of steel equipment in the oil fields of Tatarstan (Russia) resulted in the isolation of a new halotolerant strictly anaerobic sulfate-reducing bacterium, strain 5S69^T. The cells were motile curved Gram-negative rods. Optimal growth was observed in the presence of 2.0-4.0% (<i>w</i>/<i>v</i>) NaCl, at pH 6.5, and at 23-28 °C under sulfate-reducing conditions. The isolate was capable of chemoorganotrophic growth with sulfate and other sulfoxides as electron acceptors, resulting in sulfide formation; and of pyruvate fermentation resulting in formation of H₂ and acetate. The strain utilized lactate, pyruvate, ethanol, methanol, fumarate, and fructose, as well as H₂/CO₂/acetate for sulfate reduction. The genome size of the type strain 5S69^T was 4.16 Mb with a G + C content of 63.0 mol%. On the basis of unique physiological properties and results of the 16S rRNA gene-based phylogenetic analysis, phylogenomic analysis of the 120 conserved single copy proteins and genomic indexes (ANI, AAI, and dDDH), assigning the type strain 5S69^T ((VKM B-3653^T = KCTC 25499^T) to a new species within the genus <i>Pseudodesulfovibrio</i>, is suggested, with the proposed name <i>Pseudodesulfovibrio methanolicus</i> sp. nov. Genome analysis of the new isolate showed several genes involved in sulfate reduction and its sulfide-producing potential in oil fields with high saline formation water.