Development of a rapid detection method for real-time fluorescent quantitative PCR of Salmonella spp. and Salmonella Enteritidis in ready-to-eat fruits and vegetables

Two real-time quantitative PCR detection systems that contained DNA Green saturated fluorescent dye for detection of Salmonella Enteritidis and Ly Green saturated fluorescent dye for detection of Salmonella spp. were constructed. Furthermore, the specificity of the amplification system increased with the addition of graphene quantum dots. The R2 values of the standard curves were 0.999 (S. Enteritidis) and 0.998 (Salmonella spp.), respectively. The sensitivities of the two amplification systems were evaluated based on three aspects: genomic DNA (1.36 fg/mu L, 1.36 fg/mu L); bacterial cell without enrichment (2.49 CFU/mL, 2.49 CFU/mL); plasmid containing Gene ID:1828390769 (11.6 copies/mu L) and plasmid containing Gene ID:3335471 (1.08 copies/mu L). Detection results of fruits and vegetables artificially contaminated with Salmonella showed that the traditional culture method exhibits a lower detection rate than the molecular detection method, and the culture time of the Selective Luria-Bertani broth (SLB) was short. The detection rate was increased compared with that of the Buffered Peptone Water-Selenite Cystine broth (BPW-SC). The two detection systems exhibit high sensitivity and specificity and are suitable for detecting Salmonella in ready-to-eat fruits and vegetables.

Automated summary

Two real-time quantitative PCR detection systems were developed for detecting Salmonella Enteritidis and Salmonella spp. using DNA Green and Ly Green saturated fluorescent dyes. The specificity of the systems was improved by adding graphene quantum dots, with high R2 values for standard curves and evaluations of sensitivity for different aspects.