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-45(T) and DY470(T)) were isolated from seawater collected from the Southern Ocean and the Pacific Ocean, respectively. Growth of strain Ar-45(T) 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(T) 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(T) were C16 : 0, C19 : 0 cyclo ω8c and C18 : 1ω7c, while those of strain DY470(T) 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-45(T) and DY470(T) 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(T) and Oceanicola marinus LMG 23705(T) was 22.0 %. Levels of DNA-DNA relatedness between strain DY470(T) and Oceanicola nitratireducens LMG 24663(T) and Oceanicola batsensis DSM 15984(T) were 32.5 and 26.1 %, respectively. Based on phylogenetic, chemotaxonomic and phenotypic data, strains Ar-45(T) and DY470(T) are considered to represent two novel species of the genus Oceanicola, for which the names Oceanicola antarcticus (type strain Ar-45(T) = CGMCC 1.12662(T) = LMG 27868(T)) and Oceanicola flagellatus (type strain DY470(T) = CGMCC 1.12664(T) = LMG 27871(T)) are proposed.