Development of IMBs-qPCR method for detection of foodborne Salmonella

Rapid and accurate detection of pathogenic microorganism is critical for food safety. Salmonella is one of the common causes of food poisoning. In the present work, polyclonal antibody against the recombinant PagN protein was prepared, and coupled with carboxylated magnetic beads to form immunomagnetic beads (IMBs) for capturing Salmonella, which was then combined with qPCR technology which used the specific primers of invA gene to accurately quantify the number of colonies, thus establishing the IMBs-qPCR method for detection of Salmonella. 0.2 mg IMBs could specifically concentrate Salmonella, with the stable capturing efficiency of 80%, corresponding to the concentrations of 102 - 105 CFU/mL. The minimum detection limit concentration was 101 CFU/mL. The method was applied for detection and enumeration of Salmonella in pork and milk samples, and the capture efficiency of 77.38 and 80.92% were obtained. In summary, the IMBs-qPCR method established herein could effectively detect Salmonella with good specificity and sensitivity. The whole detection time was less than 9 h, which laid a foundation for development of a rapid detection kit for foodborne pathogens.