Oceanisphaera sediminis sp. nov., isolated from marine sediment

Two strains, designated TW92(T) and TW93, were isolated from marine sediment collected from the south coast of Korea. Cells of both strains were Gram-staining-negative, coccus-shaped, aerobic, motile and catalase- and oxidase-positive. Strain TW92(T) grew optimally in the presence of 2 % (w/v) NaCl (range 1-5%) while strain TW93 grew optimally in the presence of 1% (w/v) NaCl (range 0-12%), and both strains had an optimal growth temperature of 30 °C (range 4-37 °C). Strains TW92(T) and TW93 had the same optimum pH (pH 7), but differed in their ability to grow at pH 10. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strains TW92(T) and TW93 were most closely related to Oceanisphaera donghaensis BL1(T), with 98.8% and 98.7% similarity, respectively. Pairwise similarity between the 16S rRNA gene sequences of strains TW92(T) and TW93 was 99.9%. The major fatty acids of both strains were summed features 3 (comprising C(16:1)ω7c/iso-C(15) 2-OH), C(16:0) and C(18:1)ω7c. Both strains possessed the ubiquinone Q-8 as the predominant respiratory quinone and phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol as the polar lipids. The genomic DNA G+C contents of strains TW92(T) and TW93 were 58.5 and 59.6 mol%, respectively. Genomic relatedness values based on DNA-DNA hybridization of strains TW92(T) and TW93 with related species were below 47% and 31%, respectively. DNA-DNA hybridization values between strains TW92(T) and TW93 were above 85%. On the basis of a taxonomic study using polyphasic analysis, it is proposed that the two isolates represent a novel species, Oceanisphaera sediminis sp. nov., with strain TW92(T) (=KACC 15117(T)=JCM 17329(T)) as the type strain and strain TW93 (=KACC 15118=JCM 17330) as an additional strain.