Comparative analysis of denaturing gradient gel electrophoresis and temporal temperature gradient gel electrophoresis in separating Escherichia coli uidA amplicons differing in single base substitutions

A set of Escherichia coli freshwater isolates was chosen to compare the effectiveness of denaturing gradient gel electrophoresis (DGGE) vs temporal temperature gradient gel electrophoresis (TTGE) for separating homologous amplicons from the respective uidA region differing in one to seven single base substitutions. Both methods revealed congruent results but DGGE showed a five to eight times higher spatial separation of the uidA amplicons as compared with TTGE, although the experiments were performed at comparable denaturing gradients. In contrast to TTGE, DGGE displayed clear and focused bands. The results strongly indicated a significantly higher discrimination efficiency of the spatial chemical denaturing gradient as compared with the temporal temperature denaturing gradient for separating the uidA amplicons. Denaturing gradient gel electrophoresis proved to be highly efficient in the differentiation of E. coli uidA sequence types.