The viable but non-culturable (VBNC) state, a unique state in which a number of bacteria respond to adverse circumstances, was first discovered in 1982. Unfortunately, it has been reported that many foodborne pathogens can be induced to enter the VBNC state by the limiting environmental conditions during food processing and preservation, such as extreme temperatures, drying, irradiation, pulsed electric field, and high pressure stress, as well as the addition of preservatives and disinfectants. After entering the VBNC state, foodborne pathogens will introduce a serious crisis to food safety and public health because they cannot be detected using conventional plate counting techniques. This review provides an overview of the various features of the VBNC state, including the biological characteristics, induction and resuscitation factors, formation and resuscitation mechanisms, detection methods, and relationship to food safety.

O157:H7, , and are food-borne pathogens that cause serious gastrointestinal illness and frequent food safety accidents. This study aimed to develop a practical multiplex polymerase chain reaction (mPCR) technique for the simultaneous detection of these food-borne pathogens in culture broth and artificial food matrix. Pathogen-specific DNA sequences in the E,, and A genes were used as targets to design primers for the identification of O157:H7, , and respectively. As expected, the method produced species-specific bands of amplified products without any contaminating non-specific bands. The highest species specificity was established with primer concentrations of 0.1, 0.2, and 0.4 μM for O157:H7,, and , correspondingly. The detection sensitivity of this assay was 10 CFU/mL in culture broth, and the limit of detection was consistent with singleplex PCR in the food sample. The mPCR assay proposed here is an easy and convenient detection method, which will be valuable for microbial epidemiology and food safety investigations.

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The aim of this study was to evaluate the applicability of the conventional PCR detection method combined with propidium monoazide (PMA) treatment for the detection of viable but non-culturable (VBNC) state O157:H7 in ground beef meatballs. Under low temperature, O157:H7 cells were induced into the VBNC state in ground beef meatballs at - 20 °C after 152 days. The optimal PMA concentration of 5 µg/mL was obtained in beef meatball samples, which could completely inhibit the DNA amplification on dead cells (10 cells/mL) but with no inhibition on viable cells. The established PMA-PCR assay revealed that the VBNC counts exceeded 10 CFU/mL in artificial contamination beef samples, which could be used for semi-quantitative detection of VBNC cells in beef meatball samples. This study indicated that the PMA-PCR assay might be a potential method for detection of VBNC state . O157:H7 cells in food products.

Staphylococcus aureus is a gram-positive, coccus-shaped facultative anaerobe and a member of the Staphylococcaceae family. In recent years, alimentary toxicosis caused by S. aureus is a very serious problem worldwide, which constitutes a great threat to public health. In this review, we tried to summarize the conventional methods and newly developed rapid detection techniques of S. aureus (traditional detection method, biochemical detection, immunology method, molecular biology, and biosensor method) for their principles, advantages, disadvantages, and applications. Furthermore, the future perspectives of S. aureus detection methods were forecasted at last.