Oceanisphaera ostreae sp. nov., isolated from seawater of an oyster farm, and emended description of the genus Oceanisphaera Romanenko et al. 2003

A Gram-stain-negative, motile, non-spore-forming and short rod- or rod-shaped bacterial strain, T-w6T, was isolated from seawater of an oyster farm in the South Sea, Korea. Strain T-w6T grew optimally at 25 °C and in the presence of 2 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain T-w6T joined the cluster comprising Oceanisphaera species with a bootstrap resampling value of 90.8 %, and this cluster joined the clade comprising members of the genera Oceanimonas and Zobellella with a bootstrap resampling value of 100 %. Strain T-w6T exhibited 16S rRNA gene sequence similarity of 95.9 and 96.6 % to the type strains of Oceanisphaera litoralis and Oceanisphaera donghaensis, respectively. Strain T-w6T and the type strains of Oceanisphaera litoralis and Oceanisphaera donghaensis had Q-8 as the predominant ubiquinone and iso-C15 : 0 2-OH and/or C16 : 1ω7c, C18 : 1ω7c and C16 : 0 as the major fatty acids. The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain T-w6T was 56.6 mol%. Mean DNA–DNA relatedness of strain T-w6T with Oceanisphaera litoralis DSM 15406T and Oceanisphaera donghaensis KCTC 12522T was 13 and 10 %, respectively. Phenotypic properties of strain T-w6T demonstrated that this strain could be distinguished from the other Oceanisphaera species. On the basis of the data presented, strain T-w6T is considered to represent a novel species of the genus Oceanisphaera, for which the name Oceanisphaera ostreae sp. nov. is proposed; the type strain is T-w6T ( = KCTC 23422T = CCUG 60525T). An emended description of the genus Oceanisphaera is also presented.