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

Abstract

Two Gram-stain-negative, aerobic, moderately halophilic, rod-shaped bacteria (strains Ar-45T and DY470T) were isolated from seawater collected from the Southern Ocean and the Pacific Ocean, respectively. Growth of strain Ar-45T 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 DY470T 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-45T were C16 : 0, C19 : 0 cyclo ω8c and C18 : 1ω7c, while those of strain DY470T were C18 : 1ω7c, C16 : 0 and 11-methyl C18 : 1ω7c. 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-45T and DY470T 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-45T and Oceanicola marinus LMG 23705T was 22.0 %. Levels of DNA–DNA relatedness between strain DY470T and Oceanicola nitratireducens LMG 24663T and Oceanicola batsensis DSM 15984T were 32.5 and 26.1 %, respectively. Based on phylogenetic, chemotaxonomic and phenotypic data, strains Ar-45T and DY470T are considered to represent two novel species of the genus Oceanicola , for which the names Oceanicola antarcticus (type strain Ar-45T = CGMCC 1.12662T = LMG 27868T) and Oceanicola flagellatus (type strain DY470T = CGMCC 1.12664T = LMG 27871T) are proposed.