rep-PCR fingerptinting as a tool for the analysis of genomic diversity in Escherichia coli strains isolated from an aqueous/freshwater environment.

The rep-PCR fingerprinting method, with the support of ERIC and REP primers, was used to analyse the genomic diversity of 93 E. coli strains isolated from lake water samples drawn at two different depths. The applied UPGMA for DNA analysis did not reveale any genomic similarities between the 48 E. coli strains derived from the subsurface-zone water and the 43 of the bottom-zone water. The considerable genomic diversity of the E. coli of the surface zone was expressed as a dendrogram in the form of 8 similarity groups comprising strains isolated from samples drawn over one month. The bottom-zone strains, which display a lesser degree of genomic diversity (5 similarity groups), showed distinct common features in their DNA fingerprints. In the similarity dendrogram for the bottom-zone, strains derived in different months of sampling were segregated into the same similarity groups. Applying REP primers in rep-PCR generates more complex fingerprints increasing the discriminatory power of the analysis, whereas the ERIC primer generates less complex fingerprint patterns, and is thus clearer to interpret.