Culture-independent quantification of Salmonellae in food by molecular beacon based real-time PCR

The present study has explored the culture-independent quantification of Salmonellae in selected food items by targeting invA gene using molecular beacon (MB) based real-time PCR assay. The assay could detect ten Genome Equivalents/PCR (GE/PCR) of reference strain S. typhimurium MTCC 98. The assay could detect Salmonellae in selected food samples (vegetables, street foods, fruit juices) collected from Gwalior city. Coriander poses the highest concentration of Salmonellae (1.058x107±211734 CFU/25g) in vegetables followed by panipuri (6.73x106±309502 CFU/100 ml) in street food samples and Pineapple juice (8.15x103±293 CFU/100 ml). Egg being the potential reservoir of Salmonellae was also contaminated (5.2x103±136 CFU/25 g). The present assay is culture independent without pre-enrichment of samples. The quantification of Salmonella spp. in food samples can be completed in 4-6 h by the assay developed in the present study, in comparison to culture based method which requires 2 to 3 days.