Molecular Phylogeny of the Salmonellae: Relationships among Salmonella Species and Subspecies Determined from Four Housekeeping Genes and Evidence of Lateral Gene Transfer Events

Abstract

ABSTRACT The salmonellae are a diverse group of bacteria within the family Enterobacteriaceae that includes two species, Salmonella enterica and Salmonella bongori . In order to characterize the phylogenetic relationships of the species and subspecies of Salmonella , we analyzed four housekeeping genes, gapA, phoP, mdh and recA , comprising 3,459 bp of nucleotide sequence data for each isolate sequenced. Sixty-one isolates representing the most common serotypes of the seven subspecies of Salmonella enterica and six isolates of Salmonella bongori were included in this study. We present a robust phylogeny of the Salmonella species and subspecies that clearly defines the lineages comprising diphasic and monophasic subspecies. Evidence of intersubspecies lateral gene transfer of the housekeeping gene recA , which has not previously been reported, was obtained.