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

Abstract

A Gram-reaction-negative, facultatively anaerobic, non-motile, rod-shaped, non-photosynthetic bacterial strain, DW2-9T, was isolated from soil. The highest 16S rRNA gene sequence similarities were found to Rhodobacter capsulatus ATCC 11166T (97.1 %), Rhodobacter viridis JA737T (96.4 %), Rhodobacter maris JA276T (96.2 %), Rhodobacter veldkampii ATCC 35703T (96.0 %), Haematobacter massiliensis CCUG 47968T (96.0 %), Haematobacter missouriensis CCUG 52307T (95.9 %) and Rhodobacter aestuarii JA296T (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 C18 : 1ω7c, C16 : 0, C19 : 0 cyclo ω8c and summed feature 3 (one or more of iso-C15 : 0 2-OH, C16 : 1ω6c and C16 : 1ω7c). However, unlike species of the genus Rhodobacter , strain DW2-9T neither formed internal photosynthetic membranes nor produced photosynthetic pigments. DNA–DNA hybridization between strain DW2-9T and R. capsulatus JCM 21090T showed a relatedness of 33 %. Strain DW2-9T 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 DW2-9T could be distinguished from species of the genus Haematobacter by the cultivation conditions. On the basis of our polyphasic taxonomic analysis, strain DW2-9T 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 DW2-9T ( = CCTCC AB 2011145T = KCTC 15169T). Emended descriptions of the genera Rhodobacter and Haematobacter are also proposed.