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-w6(T), was isolated from seawater of an oyster farm in the South Sea, Korea. Strain T-w6(T) 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-w6(T) 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-w6(T) 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-w6(T) and the type strains of Oceanisphaera litoralis and Oceanisphaera donghaensis had Q-8 as the predominant ubiquinone and iso-C(15:0) 2-OH and/or C(16:1)ω7c, C(18:1)ω7c and C(16:0) as the major fatty acids. The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain T-w6(T) was 56.6 mol%. Mean DNA-DNA relatedness of strain T-w6(T) with Oceanisphaera litoralis DSM 15406(T) and Oceanisphaera donghaensis KCTC 12522(T) was 13 and 10%, respectively. Phenotypic properties of strain T-w6(T) demonstrated that this strain could be distinguished from the other Oceanisphaera species. On the basis of the data presented, strain T-w6(T) 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-w6(T) (=KCTC 23422(T) =CCUG 60525(T)). An emended description of the genus Oceanisphaera is also presented.