Taonella mepensis gen. nov., sp nov., a member of the family Rhodospirillaceae isolated from activated sludge

A novel Gram-negative, non-spore-forming, rod-shaped strain, H1(T), was isolated from activated sludge by micromanipulation. No close relatives among cultured bacterial isolates were found; phylogenetic analysis based on 16S rRNA gene sequences revealed that strain H1(T) forms a deep single branch in the family Rhodospirillaceae. Cells of strain H1(T) were slightly curved to straight rods (1.2-1.4x1.5-1.7 mu m) and motile by a single polar flagellum. Strain H1(T) was able to grow in the presence of 0-4% NaCl and grew optimally at 37 degrees C and pH 6.0-7.0. Chemotaxonomic analysis revealed that strain H1(T) possessed Q-10 as the predominant ubiquinone and C-18:1 omega 7c, C-16:0 and C-19:0 Gyclo omega 8c as the major fatty acids. The DNA G+C content of strain H1(T) was 65.1 mol%. Comparative analysis of 16S rRNA gene sequences, and phenotypic and chemotaxonomic data, indicate that strain H1(T) should represent a novel genus and species of the family Rhodospirillaceae. The name Taonella mepensis gen. nov., sp. nov. is proposed. The type strain of Taonella mepensis is H1(T) (=CICC 10529(T) =CCTCC AB 2012861(T) =KACC 16940(T)).