A Gram-negative, moderately halophilic bacterium, designated as strain Y3S6T, was isolated from a surface seawater sample collected from Dongangyoeng cave, Udo-myeon, Jeju-si, Jeju-do, Repulic of Korea. Cells of strain Y3S6T were aerobic, rod-shaped, non-sporulated, yellow, catalase- negative, oxidase-negative and motile with one polar flagellum. Growth of strain Y3S6T occurred at 15-40 °C (optimum: 25-30 °C), at pH 6.0-9.0 (optimum: pH 7.0) and in the presence of 0-13% NaCl (optimum: 1-6 %, w/v). The novel strain was able to produce carotenoids. Its chemotaxonomic and morphological characteristics were consistent with those of members of the genus Halomonas. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain Y3S6T formed a clade with Halomonas pellis L5T (98.97 %) and Halomonas saliphila LCB169T(98.90%). The average nucleotide identity and digital DNA-DNA hybridization values of strain Y3S6T with the most closely related strains for which whole genomes are publicly available were 82.3-85.2% and 62.8-66.1 %, respectively. The major fatty acids in strain Y3S6T were C16 : 0, C19 : 0 cyclo ω8c and summed feature 8 (composed of C18 : 1 ω7c and/or C18 : 1 ω6c), and the predominant quinone was Q-9. Its polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phosphoglycolipid, one unidentified phosphoaminoglycolipid and one unidentified phospholipid. The genomic DNA G+C content based on the draft genome sequence was 64.2 mol%. The results of physiological and biochemical tests and 16S rRNA sequence analysis clearly revealed that strain Y3S6T represents a novel species in the genus Halomonas, for which the name Halomonas antri sp. nov. has been proposed. The type strain is Y3S6T (=KACC 21536T=NBRC 114315=TBRC 15164T).
Keywords: Halomonadaceae; Halomonas antri; carotenoid; moderately halophile; moderately halophilic bacteria; seawater.