Phylogenetic analysis of Salmonella serovars based on 16S rRNA gene sequences

Abstract

We determined the complete 16S rRNA gene sequences from 15 Salmonella species through direct sequencing of PCR-amplified gene products using universal primers. Percentage similarity of sequences between Salmonella spp was very high (97.4 to 99.2%). Base subtitutions occurred throughout the gene with two apparent ‘hotspots’, one of which corresponded to the V6 variable region. We have also detected a Salmonella-specific region that can be used in the design of a species-specific gene found in S. waycross and S. matopeni, respectively, thus concurring with the known high mutational frequencies existing among pathogenic salmonellae. The Salmonella serovars appear to belong to a single species that can be divided into four subclusters which do not concur with the Kaufmann-White or Le Minor classification schemes. S. bovismorbificans was found to be most diverse among the 15 serovars studied. It is hoped that the complete sequence analysis of this gene will improve our understanding of phylogenetic relationships and taxonomic classification of these serovars.