Oceanicola antarcticus sp. nov. and Oceanicola flagellatus sp. nov., moderately halophilic bacteria isolated from seawater

Two Gram-stain-negative, aerobic, moderately halophilic, rod-shaped bacteria (strains Ar-45 and DY470) were isolated from seawater collected from the Southern Ocean and the Pacific Ocean, respectively. Growth of strain Ar-45 was observed with between 0.5 and 10.0% (w/v) NaCl (optimally with 0.5–3.0%) and between pH 5.5 and 9.5. Strain DY470 grew in the presence of 0.5–7.5% (w/v) NaCl (optimally with 2.0%) and at pH 5.5–8.5. Chemotaxonomic analysis showed Q-10 as the respiratory quinone for both strains. The major fatty acids (.5%) of strain Ar-45 were C, C cyclo ɷ8c and Cɷ7c, while those of strain DY470 were Cɷ7c, C and 11-methyl Cɷ7c. The DNA G+C contents of the two strains were 62.0 and 61.8 mol%, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains Ar-45 and DY470 were related most closely to the genus Oceanicola, with sequence similarities of 97.4–94.0 and 97.7–94.7%, respectively. The DNA–DNA hybridization value between strain Ar-45 and Oceanicola marinus LMG 23705 was 22.0%. Levels of DNA-DNA relatedness between strain DY470 and Oceanicola nitratireducens LMG 24663 and Oceanicola batsensis DSM 15984 were 32.5 and 26.1%, respectively. Based on phylogenetic, chemotaxonomic and phenotypic data, strains Ar-45 and DY470 are considered to represent two novel species of the genus Oceanicola, for which the names Oceanicola antarcticus (type strain Ar-45=CGMCC 1.12662=LMG 27868) and Oceanicola flagellatus (type strain DY470=CGMCC 1.12664=LMG 27871) are proposed.