One notable feature of Salmonella is its DNA base composition, which consists of 50-52 mol% guanine (G) and cytosine (C). This range is closely aligned with the G+C content of other genera in the family Enterobacteriaceae, such as Escherichia, Shigella, and Citrobacter. These genera share a common evolutionary ancestry, which is reflected in their DNA sequences. The similarity in G+C content between these bacteria highlights a genetic closeness that is not only suggestive of their evolutionary relationships but also significant in their physiological traits, such as resistance to environmental stresses and antimicrobial agents.
Further supporting the genetic relationship among these organisms is the DNA sequence homology. The bacteria within the genus Salmonella share highly conserved DNA sequences with one another, reinforcing their close genetic ties. However, when we look beyond Salmonella, the genera most closely related in terms of DNA sequences are Escherichia, Shigella, and Citrobacter. This shared genetic material can result in overlapping pathogenic traits, such as the ability to cause gastrointestinal infections in humans, seen in both Salmonella and Shigella.
These relationships have been corroborated by techniques such as numerical taxonomy, which uses quantitative data to classify organisms based on phenotypic traits, and 16S ribosomal RNA (rRNA) analysis, a method widely employed in phylogenetics to determine evolutionary relationships. The latter has confirmed that Salmonella, Escherichia, Shigella, and Citrobacter cluster closely together, underscoring the significance of both phenotypic and genotypic data in understanding bacterial taxonomy and evolution.
Genetic and Phenotypic Relationships of Salmonella within the Enterobacteriaceae Family
