Diversity of anoxygenic phototrophic purple bacteria from India

The photosynthetic purple bacteria are typical anoxygenic photosynthetic bacteria and one of the suitable microorganisms showing various biotechnological applications. In this study, we made an attempt to report the diversity of purple bacteria from various habitats of India. Among the phototrophic purple bacteria, purple non-sulfur group (PNSB) were dominated in various geographical locations. Most of the strains are isolated from water sample, soil mat, sand and an estuarine soil associated with xerophytes plant. The phototrophically grown cultures had shown distinct variation in color varying from yellow-brown, green, brown-red, to pink. Whole cell absorption spectrum of cultures revealed the presence of BCHL-a and carotenoid pigments. From the present study, total thirty isolates were isolated from enrichments and purified. Among them, fourteen isolates are tentatively identified based on their colour, microscopic observation and colony morphology are belonged to the genera, Rhodobacter, Rhodopseudomonas, Marichromatium and Allochromatium. Sixteen isolates were isolated, purified and identified through 16S rRNA gene sequencing analysis and affiliated to the genera, Rhodobacter, Rhodovulum, Rhopseudomonas, Rhodobium, Rhodospirillum, Afifella, Marichromatium and Allochromatium. Rhodobacter and Rhodovulum are frequently isolated among PNSB. Marichromatium and Allochromatium were the only genera belonging to purple sulfur bacteria were isolated. Phylogenetic analysis based on 16S rRNA gene sequence showed all the strains to cluster to their nearest phylogenetic neighbours and are diverse among themselves.