Paenirhodobacter enshiensis gen. nov., sp nov., a non-photosynthetic bacterium isolated from soil, and emended descriptions of the genera Rhodobacter and Haematobacter

A Gram-reaction-negative, facultatively anaerobic, non-motile, rod-shaped, non-photosynthetic bacterial strain, DW2-9(T), was isolated from soil. The highest 16S rRNA gene sequence similarities were found to Rhodobacter capsulatus ATCC 1119(T) (97.1%), Rhodobacter viridis JA737(T) (96.4%), Rhodobacter mans JA276(T) (96.2%), Rhodobacter veldkampii ATCC 35703(T) (96.0%), Haematobacter massiliensis CCUG 479681 (96.0 %), Haematobacter missouriensis CCUG 52307(T) (95.9%) and Rhodobacter aestuaril JA296(T) (95.7%). The genomic DNA G+C content was 67.2 mol% and the major respiratory quinone was ubiquinone 10 (Q-10). The major cellular fatty acids (>5%) were C-16:1 omega 7c, C-16:0, C-19:0 cyclo omega 8c and summed feature 3 (one or more of iso-C-15:0 2-OH, C-16:1 omega 6C and C-16:1 omega 7c). However, unlike species of the genus Rhodobacter, strain DW2-9(T) neither formed internal photosynthetic membranes nor produced photosynthetic pigments. DNA-DNA hybridization between strain DW2-9(T) and R. capsulatus JCM 21090(T) showed a relatedness of 33%. Strain DW2-9(T) contained phosphatidylethanolamine, phosphatidylglycerol and an unknown aminophospholipid as major polar lipids, which differed from those of species of the genera Rhodobacter and Haematobacter. In addition to the differences in phylogenetic position and polar lipid types, strain DW2-9(T) could be distinguished from species of the genus Haematobacter by the cultivation conditions. On the basis of our polyphasic taxonomic analysis, strain DW2-9(T) is considered to represent a novel genus and species, for which the name Paenirhodobacter enshiensis gen. nov., sp. nov. is proposed. The type strain of Paenirhodobacter enshiensis is DW2-9(T) (=CCTCC AB 2011145(T)=KCTC 15169(T)). Emended descriptions of the genera Rhodobacter and Haematobacter are also proposed.