Rhodobacter alkalitolerans sp. nov., isolated from an alkaline brown pond.

An alkali-tolerant, Gram-stain-negative, motile, rod-to-oval-shaped, yellowish brown-colored, phototrophic bacterium, designated as strain JA916, was isolated from an alkaline brown pond in Gujarat, India. The DNA G + C content of the strain JA916 was 65.1 mol%. Strain JA916 grew well at pH 10. Respiratory quinone was Q-10 and major fatty acid was Cω7c/Cω6c, with significant quantities of C2OH observed. Strain JA916 shared the highest 16S rRNA gene sequence similarity with the type strains of Rhodobacter johrii (98.4%), followed by Rhodobacter megalophilus (98.3%), Rhodobacter sphaeroides (98.3%), Rhodobacter azotoformans (97.9%) and other members of the genus Rhodobacter (< 97%). 16S rRNA gene-based phylogenetic tree shows that strain JA916 formed a distinct sub-clade with Rhodobacter johrii, Rhodobacter megalophilus, Rhodobacter sphaeroides and Rhodobacter azotoformans. Further, rpoB-based phylogenetic analysis showed lower similarity with closely related species (≤ 93.0%) of the genus Rhodobacter, which suggests that JA916 is a novel species of the genus Rhodobacter. DNA-DNA hybridization values between strain JA916 and related type strains were less than 40%. Phenotypic, chemotaxonomical and phylogenetic differences showed that strain JA916 was distinct from other species of the genus Rhodobacter, suggesting strain JA916 represents a new species of the genus for which the name Rhodobacter alkalitolerans sp. nov. is proposed. Type strain is JA916 (= KCTC 15473 = LMG 28749).