The efficacy of partial 16S rRNA gene sequencing for precise determination of phylogenetic relatedness among Salmonellae

Abstract

More than 2,600 Salmonella enterica serovars have been described based on the expression of the somatic and flagellar antigens. For epidemiological tracing, the use of Salmonellae serotyping is inefficient because strains within the same serovar could be distantly genetically related. Due to the 16S rRNA gene is a highly conserved DNA sequence in the bacterial genome, it can be used to fingerprint and trace Salmonellae sources during epidemics. This study was designed to explore the efficacy of the partial 16S rRNA gene sequencing for molecular characterization and phylogenetic relatedness determination of Salmonellae isolates. The three Salmonella isolates used in this study were isolated from infected humans, camels, and poultry, and then tested serologically, microbiologically, and biochemically. These strains were initially designated as Salmonella strains S-117, S-118, and S-119. The partial 16S rRNA gene sequences of the three Salmonella isolates were conducted and compared them to sequences of representative organisms belonging to Enterobacteriaceae using the alignment editor ae2. The study revealed that the isolates S-117, S-118, and S-119 share similar 16S rRNA gene sequences and G + C content, indicating their presence in a tight phylogenetic cluster. The three isolates also have a 100% partial 16S rRNA gene sequence similarity with S. Typhi ATCC 19430T. Phylogenetic analysis indicated that the three Salmonella isolates are related to the species S. Dublin. These results indicate that partial 16S rRNA gene sequencing is adequate for the Salmonellae characterization and phylogenetic relatedness determination. Therefore, the study demonstrates the value of coupling partial 16S rRNA gene sequencing utility with conventional serological, microbiological, and biochemical modalities as effective tools for the epidemiological tracing of Salmonella to the species level.