Rapid Detection of Viable Salmonella spp. in Frozen Meat Products Using Sodium Deoxycholate, Propidium Monoazide, and Real-time Quantitative PCR
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Abstract:
In order to realize rapid detection of viable Salmonella spp. in frozen meat products, a novel sodium deoxycholate-propidium monoazide-quantitative polymerase chain reaction (SD-PMA-qPCR) method was established using PMA and SD to eliminate interference from dead and injured cells. The reaction conditions were optimized, and an artificially infected sample was tested. The results showed that the optimal SD concentration was 0.1% and the optimal incubation time was 20 min. The numbers of bacterial survivors were compared using plate count, qPCR, PMA-qPCR, and SD-PMA-qPCR assays after the cell suspensions were cryogenically frozen at -20℃ for 3~4 d. The results showed that the numbers of viable Salmonella spp. obtained from qPCR and PMA-qPCR were similar and significantly higher than that from the plate count method. The result from SD-PMA-qPCR was close to that from the plate count method, indicating that a combination of PMA and SD could effectively eliminate the impact of dead and injured bacteria. The artificial infection test results showed that the detection limit of Salmonella spp. was 102 CFU/g, and the presence of 106 CFU/g Escherichia coli O157:H7 did not affect the measurement results. The SD-PMA-qPCR method developed in this study has good specificity and high sensitivity. It is expected to be used as a new method for the rapid detection of viable Salmonella spp. in frozen meat products, and has good research value and application prospects.
