Rapid Detection of Salmonella in Food Samples by Real-time PCR

Objective To establish a rapid,sensitive and specific Salmonella detection method with real-time PCR. Methods Based on Salmonella fim Y gene,a pair of primers and a probe were designed.DNA extracted from Salmonella strain was used as template.Magnesium concentration,primer/probe concentration were optimized.Specificity,sensitivity and stability analyses were performed by Salmonella and 10 associated bacteria strains.The constructed real-time PCR method was primarily used for detection of Salmonella in food samples.Results The best Mg~(2+)concentration was 3 mmol/L.Primer concentration and probe concentration were 0.8μmol/L and 1.0μmol/L,respectively.Test showed that the probe was highly conservative and specific.The results of all 10 bacteria strains were negative except for strains of Salmonella.The detection limit of the method was 33 cfu/ml of pure cultures of Salmonella.Stability test showed that co-efficient variables were all less than 5% in 4 different samples.Primary application showed that real-time PCR method was more sensitive,easier and faster than conventional culture method for detection of Salmonella in food.Conclusion Real-time PCR method was easy to handle,rapid and of high sensi- tivity and specificity.It meets the need of development of food microorganism examination,and is valuble to be further extended.