Pseudodesulfovibrio alkaliphilus, sp. nov., an alkaliphilic sulfate-reducing bacterium isolated from a terrestrial...

The diversity of anaerobic microorganisms in terrestrial mud volcanoes is largely unexplored. Here we report the isolation of a novel sulfate-reducing alkaliphilic bacterium (strain F-1^T) from a terrestrial mud volcano located at the Taman peninsula, Russia. Cells of strain F-1^T were Gram-negative motile vibrios with a single polar flagellum; 2.0-4.0 µm in length and 0.5 µm in diameter. The temperature range for growth was 6-37 °C, with an optimum at 24 °C. The pH range for growth was 7.0-10.5, with an optimum at pH 9.5. Strain F-1^T utilized lactate, pyruvate, and molecular hydrogen as electron donors and sulfate, sulfite, thiosulfate, elemental sulfur, fumarate or arsenate as electron acceptors. In the presence of sulfate, the end products of lactate oxidation were acetate, H₂S and CO_2. Lactate and pyruvate could also be fermented. The major product of lactate fermentation was acetate. The main cellular fatty acids were anteiso-C_15:0, C_16:0, C_18:0, and iso-C_17:1ω8. Phylogenetic analysis revealed that strain F-1^T was most closely related to Pseudodesulfovibrio aespoeensis (98.05% similarity). The total size of the genome of the novel isolate was 3.23 Mb and the genomic DNA G + C content was 61.93 mol%. The genome contained all genes essential for dissimilatory sulfate reduction. We propose to assign strain F-1^T to the genus Pseudodesulfovibrio, as a new species, Pseudodesulfovibrio alkaliphilus sp. nov. The type strain is F-1^T (= KCTC 15918^T = VKM B-3405^T).