Poly(GTG)5-associated profiles of Salmonella and Shigella genomic DNA

DNA hybridization with oligonucleotide probes is a powerful technique to study population genetics and structures. The use of probes which recognize ubiquitously interspersed DNA sequences has a distinct advantage over other techniques (e.g. the analysis of patterns of restriction fragment length polymorphism) in that many independent loci can be detected simultaneously. In this communication, we investigated the use of a trinucleotide repetitive DNA oligonucleotide, poly(GTG)5, in Southern blot analysis of Salmonella serotypes and Shigella species. The strains in this study were isolated over several years from widely disparate geographic locations and can therefore be considered to represent the structure of part of the natural populations of these organisms. In most of the Salmonella serotypes, the poly(GTG)5-associated profile (GTG profile) phenotypes appeared to be clonally stable; in cases where only one isolate of a serotype was tested, the GTG profile was distinct from the others. On the other hand, when GTG profile analysis was applied to Shigella strains, each of the 12 isolates, belonging to the four Shigella species, produced a unique pattern phenotype of both the chromosome and plasmid DNA.