Pseudorhodobacter sinensis sp nov and Pseudorhodobacter aquaticus sp nov., isolated from crater lakes

Three Gram-stain negative, aerobic, non-motile, rod-shaped bacterial strains, Y1R2-4(T), Y3R2-3 and DC2N1-10(T), isolated from two crater lakes of the Daxinganling Mountains, northern China, were studied to determine their taxonomic position. They grew at 4-30 degrees C (optimally at 20-25 degrees C), at pH 6.0-7.5 (optimally at pH 7.0) and in the presence of 0-0.5% (w/v) NaCl. On the basis of 16S rRNA gene sequence analysis, these strains showed 95.3-96.6% similarity to members of the genus Pseudorhodobacter, including Pseudorhodobacter ferrugineus DSM 5888(T), Pseudorhodobacter wandonensis WT-MW11(T), Pseudorhodobacter antarcticus ZS3-33(T) and Pseudorhodobacter aquimaris HDW-19(T). All strains contained Q-10 as the predominant ubiquinone and C-18:1 omega 7c as the major fatty acid. The main polar lipids for strains Y1R2-4(T) and Y3R2-3 were phosphatidylglycerol, phosphatidylcholine, one unidentified aminophospholipid, one unidentified aminolipid, three unidentified phospholipids and two unidentified lipids, and those for strain DC2N1-10(T) were phosphatidylglycerol, phosphatidylcholine, one unidentified aminophospholipid, one unidentified aminolipid, one unidentified phospholipid and several unidentified lipids. The DNA G+C contents of strains Y1R2-4(T), Y3R2-3 and DC2N1-10(T) were 61.9, 61.0 and 60.0 mol%, respectively. In addition, strain Y1R2-4(T) shared less than 50% DNA-DNA relatedness to strain DC2N1-10(T). Based on these differences in genetic, physiological and chemotaxonomic properties, strains Y1R2-4(T), Y3R2-3 and DC2N1-10(T) were considered to represent two novel species of the genus Pseudorhodobacter, for which the names Pseudorhodobacter sinensis sp. nov. (type strain Y1R2-4(T) = CGMCC1.14435(T) = KCTC 52039(T)) and Pseudorhodobacter aquaticus sp. nov. (type strain DC2N110(T) = CGMCC1.14433(T) = KCTC 52040(T)) are proposed.