gen. nov., sp. nov., isolated from deep sea hydrothermal sulfide in the northwest Indian Ocean, and proposal to reclassify as comb. nov.

A novel Gram-stain-negative, non-motile, strictly aerobic, rod-shaped bacterium was isolated from deep-sea hydrothermal sulfide in the northwest Indian Ocean Ridge and designated as strain IOP_32. Strain IOP_32 could grow at 4-40 °C (optimum, 37 °C), pH 5-9 (optimum, pH 7-8) and salinity of 0-12 % NaCl (w/v; optimum, 2-3 %). The 16S rRNA gene sequence of strain IOP_32 is most similar to EM7, RA3-3-1, KMM 6029 and S9_10 with 95.5-95.3 % similarity. The phylogenomic analysis indicated that strain IOP_32 forms a distinct lineage with Th78 within the family . The average nucleotide identity, average amino acid identity and percentage of conserved protein values between strain IOP_32 and the type strains of close genera were 72.3-78.5 %, 67.4-76.9 % and 56.3-61.6 %, respectively. The major cellular fatty acid was anteiso-C. The respiratory quinone was MK-6. The polar lipids were mainly composed of phosphatidylethanolamine, an unidentified aminophospholipid and five unidentified polar lipids. Strain IOP_32 is significantly different from related genera, which is reflected by the wide adaptability to temperature and salinity levels, the composition of phospholipids and fatty acids, and the results of phylogenetic analyses. The phenotypic properties and phylogenetic data suggest that the lineage represents a novel genus and species within the family , for which the name gen. sp. nov. is proposed, with the type strain IOP_32 (=MCCC 1A14017 =KCTC 62660 ). We also propose the reclassification of as comb. nov. (Th78=DSM 26285=JCM 18634=KCTC 32142).