Comparative analysis of genome of Edwardsiella tarda by BOX-PCR and PCR-ribotyping

The Genus Edwardsiella comprises of bacteria differing strongly in their biochemical characteristics, physiological features, natural habitat and pathogenic properties. The most common species of the genus is Edwardsiella tarda, recovered from a variety of environmental and animal sources. In this study 51 isolates including one reference strain obtained from freshwater culture systems were analyzed for their genomic diversity by BOX-PCR and PCR-ribotyping. By comparison of fingerprint of different isolates 27 and 32 genotypes were obtained by PCR-ribotyping and BOX-PCR respectively. Cluster analysis of genetic profile obtained by BOX-PCR and ribotyping clearly showed 9 and 8 clusters respectively. Some correlation between BOX-PCR and ribotyping was observed. Several clusters delineated on the basis of source of isolation in the dendrogram by BOX-PCR with 70% cut off value had corresponding clusters in the ribotyping with 50% cut off value. Some of the genotypes were found to be habitat specific. However, there was mixing and dispersal of most of the genotypes obtained from water, sediment and fish samples. Of both the techniques, BOX-PCR was found to be more discriminating than ribotyping.