Phenotypic and Genomic Characterization of a New Species Belonging to the SAR116 Clade in the Class Alphaproteobacteria

초록

Although the SAR116 clade is one of the most predominant group in marine bacterioplankton assemblages, only two isolates, strains “Puniceispirillum marinum” IMCC1322 and HIMB100, have been isolated so far. Strains IMCC1322 and HIMB100 were isolated from the sea surface of the East Sea and Hawaii, respectively, and harbored proteorhodopsin (PR) and DMSP demethylase. In the present study, we report the isolation and genome properties of strain IMCCG8-E1T isolated from the Yellow Sea using dilution-to-extinction. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain IMCCG8-E1T belonged to the OCS28 subclade of the SAR116 clade and shared 97.0 % similarity with strain IMCC1322. The completed genome sequence of strain IMCCG8-E1T was 2.7 Mbp in size with 49.3% of G+C content. The IMCCG8-E1T genome was predicted to have 2591 protein-coding genes including PR, DMSP demethylase, urease, and sulfur oxidation. Strain IMCCG8-E1T contained summed feature 3 (C16:1 ω7c/C16:1 ω6c) and 8 (C18:1ω7c), and C16:0 as the major fatty acids and ubiquinone-10 as the major respiratory quinone. The major polar lipids detected in the strain were phosphatidylethanolamine and phosphatidylglycerol. On the basis of phylogenetic and phenotypic characteristics, it was suggested that strain IMCCG8-E1T represents a novel species of the genus “Puniceispirillum”, for which the name Puniceispirillum seosanensis sp. nov. is proposed. [Supported by a grant from the MOF (No. 20180430)]