Abstract: The single nucleotide polymorphisms (SNPs) in different serotypes of 7 specific targets for Salmonella detection were analyzed based on the whole genome sequences of 28 Salmonella strains (14 serotypes) published on NCBI. The results showed that S9 and S69 had more SNPs than any other target, making them a potential tool for Salmonella serotyping. Subsequently, the distinct nucleotide mutation sites of the two candidate molecular serotyping targets in different serotypes of Salmonella were analyzed. As a result, various combinations of the mutation sites were obtained for rapid molecular serotyping of 14 Salmonella serotypes, and the results showed that identical mutation sites existed in the same serovar, while different mutation sites were found in diverse serovars. Finally, 21 suspected Salmonella isolates were obtained by the national standard method from 192 food samples collected from supermarkets and open-air markets in Shanghai. The results of molecular serotyping by targets S9 and S69 were 100% consistent with the results of the traditional slide agglutination test; the Salmonella isolates were assigned to 4 different serovars, 10 strains of Salmonella Enteritidis, 7 strains of Salmonella Typhimurium, 2 strains of Salmonella Gallinarum and 2 strains of Salmonella Newport. The results of genome sequence analysis and strain serotyping showed that the combination of Salmonella-specific targets S9 and S69 had the potential for molecular serotyping of Salmonella, which is expected to be a time-saving and cheaper alternative to the traditional slide agglutination test and can provide a new idea for the application of PCR technology in Salmonella molecular serotyping.

Key words: Salmonella, molecular serotyping, Salmonella-specific targets, food samples, serum identification