Phylogenetic diversity of sulfate-reducing bacteria of sediments of Chilika Lake, India, determined through analysis of the dissimilatory sulfite reductase (dsr AB) gene.

In this study, the sulfate-reducing bacteria, (SRB) were identified and reported for the first time through analysis of functional gene dsrAB, from the DNA of sediment samples collected from 10 sites of the Chilika lake. The finding illustrates Forty six Operational Taxonomic Units (OTUs), identified from the DGGE which were obtained from the 10 sediment samples. Of these, 34 OTUs exhibited around 78-96% sequence similarity and 12 OTUs showed 97 to 100% sequence similarity to the dsrAB gene of reported type strains of SRB. The sequence information obtained revealed the presence and distribution of diverse types of SRB which include phylotypes related to Desulfovibrio, Desulfonatronovibrio, Desulfomicrobium, Desulfobotulous and Desulfobacca. Upon comparison of dsrAB gene sequences of SRB obtained through this study with those collected from the GenBank, and through the dendrogram constructed, it was observed that except 13 OTUs that clustered closely with the reported type strains, all other 36 OTUs clustered distantly and had no representative member of SRB. This indicated the presence of phylogenetically diverse groups of SRB inhabiting the lake Chilika.