Ruegeria meonggei sp. nov., an alphaproteobacterium isolated from ascidian Halocynthia roretzi

A Gram-negative, strictly aerobic, non-flagellated and rod-shaped bacterial strain, designated MA-E2-3T, was isolated from an ascidian (Halocynthia roretzi) collected from the South Sea, South Korea. Strain MA-E2-3T was found to grow optimally at 30 °C, at pH 7.0–8.0 and in the presence of 2.0–3.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain MA-E2-3T fell within the clade comprising Ruegeria species, clustering consistently with the type strain of Ruegeria halocynthiae, with which it exhibited 98.2 % sequence similarity. Sequence similarities to the type strains of the other recognized Ruegeria species were 94.7–97.7 %. Strain MA-E2-3T was found to contain Q-10 as the predominant ubiquinone and C18:1ω7c as the predominant fatty acid. The major polar lipids of strain MA-E2-3T were identified as phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain MA-E2-3T was determined to be 58.0 mol%. Mean DNA–DNA relatedness values between strain MA-E2-3T and the type strains of four phylogenetically closely related Ruegeria species were in the range of 13–23 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain MA-E2-3T is separated from other Ruegeria species. On the basis of the data presented, strain MA-E2-3T (=KCTC 32450T = CECT 8411T) represents a novel species of the genus Ruegeria, for which the name Ruegeria meonggei sp. nov. is proposed.