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

Abstract

An oval to rod-shaped, phototrophic, purple non-sulfur bacterium, strain JA192T, 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 JA192T 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 2.4.1T (99.9 % sequence similarity), Rba. megalophilus JA194T (99.8 %) and Rba. azotoformans KA25T (98.1 %) and clusters with other species of the genus Rhodobacter of the family Rhodobacteraceae. However, DNA–DNA hybridization with Rba. sphaeroides DSM 158T, Rba. megalophilus JA194T and Rba. azotoformans JCM 9340T showed relatedness of only 38–57 % with respect to strain JA192T. On the basis of 16S rRNA gene sequence analysis, DNA–DNA hybridization data and morphological, physiological and chemotaxonomic characters, strain JA192T represents a novel species of the genus Rhodobacter, for which the name Rhodobacter johrii sp. nov. is proposed. The type strain is JA192T (=DSM 18678T =JCM 14543T =MTCC 8172T).