Abstract: A selective enrichment broth, SEL based real time PCR assay was established after treating a sublethal injured Salmonella cells by heat-shock. The results showed that 1－2 CFU of injured Salmonella cells in 5 mL SEL could be fully recovered and enriched to the level of 109 CFU/mL after a 20 h enrichment step even without the nonselective recovery process. The amplification efficiency of real time PCR was 95.41% and the detection limit was 4 CFU/reaction for Salmonella genomic DNA. The detection limit in artificially contaminated food sample was 3 CFU/10 g ground beef, and showed a high coincidence to the detection result by traditional culture-based assay. The overall recovery, selective enrichment and detection procedure of thermal injured Salmonella could be accomplished in 24 h, which showed a high potential of application in the effective detection of Salmonella in food.

Key words: thermal injury, Salmonella, selective enrichment, real time polymerase chain reaction (PCR), detection