Development of loop-mediate isothermal amplification assay for Salmonella detection in food

It is important to detect Salmonella in food or food materials in order to assure the food safety. A rapid sensitive loop-mediated isothermal amplification (LAMP) method assay for the food-borne pathogen Salmonella detection was developed. A set of primers were designed according to the nucleotide sequence of the target invA gene in Salmonella, 7 strains of Salmonella and 4 non-Salmonella bacteria were detected by LAMP, and meanwhile the mode of artificially contaminated food was constructed to evaluate the sensitivity of LAMP assay and bacterial cell counting method. The results showed that all the 7 Salmonella bacterial strains had specific amplification, but the 4 non-Salmonella bacterial strains submitted negative reactions. Sensitivity of LAMP assay for pure cell culture of Salmonella was 336 mL-1. However, an 8.25 g-1 detection limit was obtained for Salmonella artificially contaminated food following a bacterial culture enrichment process, while there was no amplification from the negative control. In conclusion, the LAMP assay developed in the present study is a specific, sensitive, simple and convenient method for the rapid detection of Salmonella in contaminated foods.