Comparison between digital PCR and real-time PCR in detection of Salmonella typhimurium in milk

As a kind of zero-tolerance foodborne pathogens, Salmonella typhimurium poses a great threat to quality of food products and public health. Hence, rapid and efficient approaches to identify Salmonella typhimurium are urgently needed. Combined with PCR and fluorescence technique, real-time PCR (qPCR) and digital PCR (ddPCR) are regarded as suitable tools for detecting foodborne pathogens. To compare the effect between qPCR and ddPCR in detecting Salmonella typhimurium, a series of nucleic acid, pure strain culture and spiking milk samples were applied and the resistance to inhibitors referred in this article as well. Compared with qPCR, ddPCR exhibited more sensitive (10(-4) ng/mu l or 10(2) cfu/ml) and less pre-culturing time (saving 2 h). Moreover, ddPCR had stronger resistance to inhibitors than qPCR, yet absolute quantification hardly performed when target's concentration over 1 ng/mu l or 10(6) cfu/ml. This study provides an alternative strategy in detecting foodborne Salmonella typhimurium.