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 was isolated from the deep-sea sediment of the Southwest Indian Ocean at a depth of 2699 m. Growth of the QX-2 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 has the closest relationship with Halomonas titanicae DSM 22872 (98.2%). Phylogeny analysis classified the strain QX-2 into the genus Halomonas. The average nucleotide identity and DNA-DNA hybridization values between strain QX-2 and related type strains were lower than the currently accepted new species definition standards. Principal fatty acids (> 10%) determined were C (12.41%), C-3OH (25.15%), summed feature 3 (C ω7c and/or C ω6c, 11.55%) and summed feature 8 (C ω7c and/or C ω6c, 16.06%). Identified polar lipids in strain QX-2 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 represents a novel species within the genus Halomonas, for which the name Halomonas sedimenti sp. nov. is proposed, with the type strain QX-2 (MCCC 1A17876 = KCTC 82199).