Rhodobacter johrii sp. nov., an endospore-producing cryptic species isolated from semi-arid tropical soils

An oval to rod-shaped, phototrophic, purple non-sulfur bacterium, strain JA192(T), was isolated from an enrichment culture of a pasteurized rhizosphere soil sample from a field cultivated with jowar (sorghum) collected from Godumakunta village near Hyderabad, India. Strain JA192(T) is Gram-negative, motile and produces endospores. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that the strain JA192T is closely related to Rhodobacter sphaeroides 2.4.1(T) (99.9% sequence similarity), Rba. megalophilus JA194(T) (99.8%) and Rba. azotolormans KA25(T) (98.1%) and clusters with other species of the genus Rhodobacter of the family Rhodobacteraceae. However, DNA DNA hybridization with Rba. sphaeroides DSM 158(T), Rba. megalophilus JA194(T) and Rba. azotoformans JCM 9340(T) showed relatedness of only 38 57% with respect to strain JA192(T). On the basis of 16S rRNA gene sequence analysis, DNA-DNA hybridization data and morphological, physiological and chemotaxonomic characters, strain JA192(T) represents a novel species of the genus Rhodobacter, for which the name Rhodobacter johrii sp. nov. is proposed. The type strain is JA192(T) (=DSM 18678(T) =JCM 14543(T) =MTCC 8172(T)).