Description of Rhodobacter azollae sp. nov. and Rhodobacter lacus sp. nov.

Abstract

Three strains (JA826T, JA912T and JA913), which were yellowish brown colour, rod to oval shaped, Gram-stain-negative, motile, phototrophic bacteria with a vesicular architecture of intracytoplasmic membranes, were isolated from different pond samples. The DNA G+C content of the three strains was between 64.6 and 65.5 mol%. The highest 16S rRNA gene sequence similarity of all three strains was with the type strains of the genus Rhodobacter sensu stricto in the family Rhodobacteraceae. Strain JA826T had highest sequence similarity with Rhodobacter maris JA276T (98.5 %), Rhodobacter viridis JA737T (97.5 %) and other members of the genus Rhodobacter (<97 %). Strain JA912T had highest sequence similarity with Rhodobacter viridis JA737T (99.6 %), Rhodobacter sediminis N1T (99.3 %), Rhodobacter capsulatus ATCC 11166T (98.8 %) and less than 97 % similarity with other members of the genus Rhodobacter. The 16S rRNA gene sequence similarity between strains JA826T and JA912T was 96.9 %. DNA-DNA hybridization showed that strains JA826T and JA912T (values among themselves and between the type strains of nearest members <44 %) did not belong to any of the nearest species of the genus Rhodobacter. However, strains JA912T and JA913 were closely related (DNA-DNA hybridization value >90 %). The genomic distinction was also supported by differences in phenotypic and chemotaxonomic characteristics in order to propose strains JA826T (=KCTC 15478T=LMG 28758T) and JA912T (=KCTC 15475T=LMG 28748T) as new species in the genus Rhodobacter sensu stricto with the names Rhodobacter lacus and Rhodobacter azollae, respectively.