Modified pulsed-field gel electrophoresis method for DNA degradation-sensitive Salmonella enterica and Escherichia coli strains

A number of S. enterica and E. coli strains appeared sensitive to a rapid DNA degradation during the course of PFGE pattern analysis. This kind of DNA degradation could not be stopped by intensive treatment with proteinase K, formalin treatment, or other modifications of the protocol for the isolation of intact chromosomal DNA. However, the application of 100 muM thiourea into the running buffer gave rise to clear-cut PFGE patterns and in turn to an overall typeability.