Rhodobacter flagellatus sp. nov., a thermophilic bacterium isolated from a hot spring

A thermophilic bacterium, designated SYSU G03088^T, was isolated from Moincer hot spring, Tibet, PR China. Polyphasic taxonomic analyses and whole-genome sequencing were used to determine the taxonomic position and genomic profiles of the strain. Phylogenetic analysis using 16S rRNA gene sequence indicated that SYSU G03088^T showed highest sequence similarity to Rhodobacter blasticus CGMCC 1.3365^T (96.0 % sequence identity). The strain could be differentiated from most recognized species of the genus Rhodobacter by its slightly purple colony colour, distinct phenotypic characters and low ANI values. Cells were Gram-staining negative, and oval-to-rod shaped. Poly-β-hydroxybutyrate and vesicular intracytoplasmic membrane structures were formed inside cells. Growth occurred optimally at 45 °C and pH 7.0. Ubiquinone 10 was the only respiratory quinone. The major fatty acids (>10 %) were C_18 : 0, C_18 : 1ω7c 11-methyl and summed feature 8 (C_18 : 1ω7c and/or C_18 : 1ω6c). The detected polar lipids of SYSU G03088^T included diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmethylethanolamine. The DNA G+C content of SYSU G03088^T was 67.7 % (genome). On the basis of the differences in the phenotypic characteristics and phylogenetic analyses, SYSU G03088^T is considered to represent a novel species of the genus Rhodobacter, for which the name Rhodobacter flagellatus sp. nov. is proposed. The type strain is SYSU G03088^T (=CGMCC 1.16876^T=KCTC 72354^T).