Rhodobacter ruber sp. nov., isolated from a freshwater pond

Abstract Strain CCP-1T, isolated from a freshwater pond in Taiwan, is characterized using a polyphasic taxonomy approach. Cells of strain CCP-1T are Gram-stain-negative, aerobic, non-motile, rod-shaped and form dark red colored colonies. Growth occurs at 20–40 oC, at pH 6.5-9 and with 0-0.5% NaCl. Strain CCP-1T contains bacteriochlorophyll a, and shows optimum growth under anaerobic condition by photoheterotrophy, but not by photoautotrophy. 16S rRNA gene sequence similarity indicates that strain CCP-1T is closely related to species within the genus Rhodobacter (93.9–96.2% sequence similarity), Haematobacter (96.3%) and Xinfangfangia (95.5–96.2%). Phylogenetic analyses based on 16S rRNA gene sequences and based on up-to-date bacterial core gene set (92 protein clusters) reveal that strain CCP-1T is affiliated with species in the genus Rhodobacter. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization identity between strain CCP-1T and Rhodobacter species are 71.3–76.3%, 70.4–77.9% and 21.4–23.2%, respectively, supporting that strain CCP-1T is a novel species of the genus Rhodobacter. The DNA G + C content is 66.2%. The predominant fatty acid is C18:1ω7c and the major isoprenoid quinone is Q-10. The polar lipids have phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two uncharacterized aminophospholipids and two uncharacterized phospholipids. On the basis of phenotypic and genotypic properties and phylogenetic inference, strain CCP-1T should represent a novel species of the genus Rhodobacter, for which the name Rhodobacter ruber sp. nov. is proposed. The type strain is CCP-1T (= BCRC 81189T = LMG 31335T).