Octadecabacter ascidiaceicola sp. nov., isolated from a sea squirt (Halocynthia roretzi)

A Gram-stain-negative, non-spore-forming, non-flagellated and coccoid, ovoid or rod-shaped bacterial strain, RA1-3T, was isolated from a sea squirt (Halocynthia roretzi) collected from the South Sea, South Korea, and subjected to a taxonomic study using a polyphasic approach. Strain RA1-3T grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0 % (w/v) NaCl. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences revealed that strain RA1-3T clustered with the type strains of three species of the genus Octadecabacter, showing 97.54-98.41 % 16S rRNA gene sequence similarity. Sequence similarities to other recognized species were less than 96.97 %. Strain RA1-3T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The major polar lipids of strain RA1-3T were phosphatidylcholine, phosphatidylglycerol, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain RA1-3T was 56 mol% and DNA-DNA relatedness values with the type strains of Octadecabacter temperatus, Octadecabacter antarcticus and Octadecabacter arcticus were 13-24 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain RA1-3T is separated from other recognized species of the genus Octadecabacter. On the basis of the data presented, strain RA1-3T is considered to represent a novel species of the genus Octadecabacter, for which the name Octadecabacter ascidiaceicola sp. nov. is proposed. The type strain is RA1-3T ( = KCTC 42605T = CECT 8868T).