Strain-specific differentiation of environmental Escherichia coli isolatesvia denaturing gradient gel electrophoresis (DGGE) analysis of the 16S-23Sintergenic spacer region

Denaturing gradient gel electrophoresis (DGGE) was applied to the 16S-23S r RNA intergenic spacer region (ISR) as a means to evaluate strain level diff erences in Escherichia coli. The ISRs of 81 environmental E. coli isolates obtained from bovine, poultry, and human sources yielded a total of 41 uniq ue DGGE banding patterns, with identical patterns and common bands within e ach source and no overlapping patterns among sources. An additional 51 isol ates from two nearby streams yielded 45 unique banding patterns with no ove rlap between sites. However, two of the isolates from the streams had ident ical banding patterns to those from two of the source isolates, resulting i n a total of 84 unique DGGE banding patterns out of 132 isolates identified in this study. These results revealed high diversity among environmental E . coli isolates, which made it difficult to unambiguously ascribe strains f ound in water samples to specific host organisms. (C) 2001 Published by Els evier Science B.V. on behalf of the Federation of European Microbiological Societies.