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Conventional methods of detecting food-borne pathogens in food are cumbersome and time-consuming. To study a rapid detecting method, investigate the usefulness of a filtration for the concentrate bacteria from raw milk and to establish an accuracy and sensitive multiplex PCR for simultaneous detection of five food-borne pathogens in raw milk. The assay can be completed in about 7 h and the limit of detection of all five food-borne pathogens for multiplex PCR was as low as 102 CFU/ml of raw-milk. This study, which increases the accuracy and sensitivity, improves traditional methods and can be applied to the food microorganism detection.

Listeria monocytogenes is a food-borne pathogen which can cause zoonosis. A detection method based on real time reverse-transcription PCR amplification of mRNA was established in the study. This method can overcome false-positive result caused by amplification of nonviable L.monocytogenes. Sensitivity and specificity of the method were studied, as well as artificially contaminated dairy products by L.monocytogenes, dairy products from market and L.monocytogenes biofilm. For contaminated milk, detection sensitivity was 17CFU/ml after 6h enrichment. Detection limit in biofilm was 2×10 2 CFU/cm 2 after 7h enrichment. The results indicate that the method can satisfy detection of L.monocytogenes in dairy products and biofilm. Key words-real time RT-PCR; Listeria monocytogenes; biofilm