Salegentibacter profundi sp. nov. and Salegentibacter haimaensis sp. nov., isolated from deep-sea cold seep sediments of the South China Sea

Two Gram-stain-negative, rod-shaped, facultatively anaerobic bacterial strains, designated F14 T and HM20 T , were isolated from deep-sea cold seep sediments in the South China Sea. Strain F14 T grew at 4–40 ℃, pH 6.0–9.0 and in the presence of 0.5–10.0% (w/v) NaCl, while strain HM20 T grew at 20–40 °C, pH 6.0–9.5 and with 0.5–8.0% (w/v) NaCl. Strains F14 T and HM20 T showed the highest sequence similarity with Salegentibacter flavus DSM 17794 T (97.8%) and Salegentibacter sediminis K5023 T (97.1%), respectively. Phylogenomic analysis based on core genome sequences supported their placement within the genus Salegentibacter . Average nucleotide identity and digital DNA–DNA hybridization values between the two novel strains and their closest phylogenetic relatives were below the species delineation thresholds of 95% and 70%, respectively. Chemotaxonomic analyses showed that the major cellular fatty acids were iso-C ₁₅:₀ , anteiso-C ₁₅:₀ and iso-C ₁₇:₀ 3-OH. The sole respiratory quinone detected was menaquinone-6, and the major polar lipid was phosphatidylethanolamine. The genomic DNA G+C contents of strains F14 T and HM20 T were 39.6% and 40.7%, respectively. In contrast to previously recognized species of the genus, both novel strains were able to grow under facultatively anaerobic conditions, which may be associated with environmental conditions in deep-sea cold seep sediments. Based on phenotypic, chemotaxonomic and genotypic results, strains F14 T and HM20 T represent two novel species of the genus Salegentibacter , for which the names Salegentibacter profundi and Salegentibacter haimaensis are proposed with the type strains F14 T (=GDMCC 1.6178 T =KCTC 102508 T ) and HM20 T (=GDMCC 1.6269 T =KCTC 102509 T ), respectively.