Pelagibacterium lentulum sp. nov., a marine bacterium from the culture broth of Picochlorum sp. 122.

A Gram-stain-negative, motile, non-spore-forming, rod-shaped bacterium, designated strain B2T, was isolated from the culture broth of a marine microalga, Picochlorum sp. 122. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain B2T forms a robust cluster with members of the genus Pelagibacterium, and shares the highest sequence similarity of 96.80 % with Pelagibacterium halotolerans CGMCC 1.7692T. Optimal growth of strain B2T was observed at 33 °C, at pH 8 and in the presence of 1 % (w/v) NaCl. The predominant ubiquinone of strain B2T was Q-10, and the G+C content of the genomic DNA was 58.6 mol%. The major fatty acid profile comprised C18 : 1ω7c/ω6c, C19 : 0 cyclo ω8c and C16 : 0. The major polar lipids of strain B2T were diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids and seven unidentified lipids. Comprehensive analyses based on a polyphasic characterization of strain B2T indicated that it represents a novel species of the genus Pelagibacterium, for which the name Pelagibacterium lentulum sp. nov. is proposed. The type strain is B2T (=MCCC 1K03218T=CGMCC 1.15896T=KCTC 52551T).