Paradesulfovibrio onnuriensis gen. nov., sp. nov., a chemolithoautotrophic sulfate-reducing bacterium isolated from the Onnuri vent field of the Indian Ocean and reclassification of Desulfovibrio senegalensis as Paradesulfovibrio senegalensis comb. nov.

An anaerobic, rod-shaped, mesophilic, chemolithoautotrophic, sulfate-reducing bacterial strain IOR2 was isolated from a newly found deep-sea hydrothermal vent (OVF, Onnuri Vent Field) area in the central Indian Ocean ridge (11°24'88″ S 66°25'42″ E, 2021 m water depth). The 16S rRNA gene sequence analysis revealed that the strain IOR2 was most closely related to Desulfovibrio senegalensis BLaC1 (96.7%). However, it showed low similarity with the members of the family Desulfovibrionaceae, such as Desulfovibrio tunisiensis RB22 (94.0%), D. brasiliensis LVform1 (93.9%), D. halophilus DSM 5663 (93.7%), and Pseudodesulfovibrio aespoeensis Aspo-2 (93.2%). The strain IOR2 could grow at 23-42°C (optimum 37°C), pH 5.0-8.0 (optimum pH 7.0) and with 0.5-6.5% (optimum 3.0%) NaCl. The strain could use lactate, pyruvate, H, and glycerol as electron donors and sulfate, thiosulfate, and sulfite as electron acceptors. The major fatty acids of the strain IOR2 were iso-C, iso-C, ante-iso-C, and summed feature 9 (C methyl/iso-Cω9c). Both the strains IOR2 and BLaC1 could grow with CO and H as the sole sources of carbon and energy, respectively. Genomic evidence for the Wood-Ljungdahl pathway in both the strains reflects chemolithoautotrophic growth. The DNA G + C content of the strain IOR2 and BLaC1 was 58.1-60.5 mol%. Based on the results of the phylogenetic and physiologic studies, Paradesulfovibrio onnuriensis gen. nov., sp. nov. with the type strain IOR2 (= KCTC 15845 = MCCC 1K04559) was proposed to be a member of the family Desulfovibrionaceae. We have also proposed the reclassification of D. senegalensis as Paradesulfovibrio senegalensis comb. nov.