Thalassobius aquaeponti sp. nov., an alphaproteobacterium isolated from seawater.

Abstract

A Gram-stain-negative, aerobic, non-motile and rod-shaped or ovoid bacterial strain, GJSW-22(T), which was isolated from seawater at Geoje island in South Korea, was characterized taxonomically. Strain GJSW-22(T) was observed to grow optimally at 30 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. In the neighbour-joining phylogenetic tree based on 16S rRNA gene sequences, strain GJSW-22(T) grouped with the type strains of Thalassobius species, forming a stable cluster with the type strain of Thalassobius aestuarii (bootstrap value of 83.2 %). Strain GJSW-22(T) exhibited the highest 16S rRNA gene sequence similarity value (98.0 %) to the type strain of T. aestuarii. It exhibited 16S rRNA gene sequence similarity values of 95.6-96.1 % to the type strains of the other Thalassobius species. Strain GJSW-22(T) was found to contain Q-10 as the predominant ubiquinone and C18:1 ω7c and 11-methyl C18:1 ω7c as the major fatty acids. The major polar lipids of strain GJSW-22(T) were identified as phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid. The DNA G + C content of strain GJSW-22(T) is 60.3 mol % and its mean DNA-DNA relatedness value with the type strain of T. aestuarii was 23 %. Differential phenotypic properties, together with the phylogenetic and chemotaxonomic data, confirmed that strain GJSW-22(T) is distinct from other Thalassobius species. On the basis of the data presented, strain GJSW-22(T) is considered to represent a novel species of the genus Thalassobius, for which the name Thalassobius aquaeponti sp. nov. is proposed. The type strain is GJSW-22(T) (=KCTC 42115(T) = NBRC 110378(T)).