Halomonas sedimenti sp. nov., a Halotolerant Bacterium Isolated from Deep-Sea Sediment of the Southwest Indian Ocean

A Gram-staining-negative, aerobic, flagellated, motile, rod-shaped, halophilic bacterium QX-2 T was isolated from the deep-sea sediment of the Southwest Indian Ocean at a depth of 2699 m. Growth of the QX-2 T bacteria was observed at 4–50 °C (optimum 30 °C), pH 5.0–12.0 (optimum pH 6.0) and 0%–30% NaCl (w/v) [optimum 4% (w/v)]. 16S rRNA gene sequencing revealed that strain QX-2 T has the closest relationship with Halomonas titanicae DSM 22872 T (98.2%). Phylogeny analysis classified the strain QX-2 T into the genus Halomonas . The average nucleotide identity and DNA–DNA hybridization values between strain QX-2 T and related type strains were lower than the currently accepted new species definition standards. Principal fatty acids (> 10%) determined were C 16:0 (12.41%), C 12:0 -3OH (25.15%), summed feature 3 (C 16:1 ω 7 c and/or C 16:1 ω 6 c , 11.55%) and summed feature 8 (C 18:1 ω 7 c and/or C 18:1 ω 6 c , 16.06%). Identified polar lipids in strain QX-2 T were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified phospholipid, unidentified aminophospholipid and five unidentified lipids (L1–L5). The main respiratory quinone was Q-9. The content of DNA G+C was determined to be 54.34 mol%. The results of phylogenetic analysis, phenotypic analysis and chemotaxonomic studies showed that strain QX-2 T represents a novel species within the genus Halomonas , for which the name Halomonas sedimenti sp. nov. is proposed, with the type strain QX-2 T (MCCC 1A17876 T = KCTC 82199 T ).