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

Simple Summary: Corrosion of steel equipment during oil production, transportation, and refining is a big global issue, leading to significant economic losses. The main agents of microbially influenced corrosion (MIC) of steel equipment are sulfate-reducing bacteria (SRB) and archaea (SRA), which reduce sulfate present in the reservoir water to form sulfide. Timely detection of sulfidogens in formations is necessary for the development of measures to suppress their growth. Existing 16S rRNA gene-based molecular methods for the detection of sulfidogens make it possible to identify them in their natural habitat, and the methods based on metagenomic analysis of components of the microbial community make it possible to predict their potential functional activity. However, selection of biocides or other methods for suppressing the growth of sulfidogens requires confirmation of their effectiveness on enrichment and/or pure cultures. In order to establish a collection of sulfidogens inhabiting the oil reservoirs of Tatarstan (Russia), a number of strains of sulfate-reducing bacteria were isolated. This study describes the 5S69T strain, which, based on the physiological and biochemical characteristics and genomic analysis, has been assigned to a new species, Pseudodesulfovibrio methanolicus sp. nov. The strain is able to grow at high salinity, at reservoir temperature, and on media with alcohols or H2/CO2 in the presence of acetate, which indicates its adaptation to environmental conditions and potential in sulfide production in the oil reservoir. 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 5S69T. The cells were motile curved Gram-negative rods. Optimal growth was observed in the presence of 2.0–4.0% (w/v) 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 5S69T 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 5S69T ((VKM B-3653T = KCTC 25499T) to a new species within the genus Pseudodesulfovibrio, is suggested, with the proposed name Pseudodesulfovibrio methanolicus 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. [ABSTRACT FROM AUTHOR]