Pseudodesulfovibrio thermohalotolerans sp. nov., a novel obligately anaerobic, halotolerant, thermotolerant, and sulfate-reducing bacterium isolated from a western offshore hydrocarbon reservoir in India

Objective

Characterization and documentation of strain MCM B-1480^T, a novel sulfate-reducing bacterium isolated from produced water of India's western offshore hydrocarbon reservoir.

Method

Strain MCM B-1480^T was unequivocally identified using a polyphasic approach routinely followed in bacterial systematics. The morphological and biochemical characterization of strain MCM B-1480^T was carried out using standard microbiological techniques.

Results

MCM B-1480^T was a Gram-stain-negative, motile, non-spore-forming, curved-rod-shaped bacterium. MCM B-1480^T could grow at temperatures between 20 and 60 °C (optimum 37 °C), pH 6–8 (optimum 7), and required 1–6% NaCl (optimum 3%) for growth. Strain MCM B-1480^T was reducing sulfate to produce hydrogen sulfide during growth. This strain used lactate and pyruvate as prominent electron donors, whereas sulfate, sulfite, thiosulfate, and nitrate served as electron acceptors. MCM B-1480^T shared maximum 16S rRNA gene sequence homology of 98.65% with the members of the genus Pseudodesulfovibrio. The G + C content of the 3.87 Mb MCM B-1480^T genome was 60.39%. Digital DDH (27.7%) and average nucleotide identity (ANI 84%) with the closest phylogenetic affiliate (less than 70% and 95%, respectively) reaffirmed its distinctiveness. The major cellular fatty acids components, namely iso-C_15:0, anteiso-C_15:0, C_16:0, and anteiso-C_17:0, differentiated strain MCM B-1480^T from other species of Pseudodesulfovibrio. Genome annotation revealed the presence of genes encoding dissimilatory sulfate reduction and nitrate reduction in strain MCM B-1480^T.

Conclusion

The polyphasic studies, including SSU rRNA gene sequencing, average nucleotide identity, Digital DNA-DNA hybridization, cell wall fatty acids analysis, etc., identified strain MCM B-1480^T as a novel taxon and Pseudodesulfovibrio thermohalotolerans sp. nov. was proposed (= JCM 39269^T = MCC 4711^T).