Detection of Viable but Nonculturable Microbial Cells in Chicken Mince

Abstract

The relevance of the study and the presence of gaps in the relevant knowledge on the topic. Potential existence of hazardous viable but nonculturable (VBNC) cells of pathogenic microorganisms in foodstuffs that can be formed under the influence of various factors, their detection and determination of conditions for formation of VBNC cells of various contaminant bacteria are relevant for preventing contamination of meats.Methods. In the study, a search was conducted for VBNC cells in chicken mince in real time and during experimental infection of it by Staphylococcus aureus 209P. In order to detect VBNC cells in chicken mince, total number of microbes, number of bacterial colonies (CFU), and the portion of living (dead) cells were determined in 1g of the product using a commercial set of fluorescent dyes. A second study was carried out after 5 h of incubation of tested samples at room temperature.Results and discussion. In samples of minced meat on the 4th day after production, more than 99% of all detected living cells were VBNC. After 5-hour incubation of the sample, the number of CFU/g increased by 22.5 times, but the portion of VBNC cells remained higher than 99% of viable bacteria. During artificial infection of the same batch of mince with S. aureus in broth culture at the stage of logarithmic growth, the amount of VBNC cells for 0 hours was 97.3%. After 5 hours their number increased to 99.99%. Probably, in the introduced culture of Staphylococcus at the stage of active reproduction, formation of VBNC bacteria did not occur, which initially reduced their number in the sample. After 5-h incubation, transition of bacteria to VBNC state was accelerated, possibly due to unfavorable conditions for the cell population (changes in trophic substrate, temperature, pH, etc.).Conclusions. Experimental data confirm presence of VBNC bacteria in chicken products that don’t grow on traditional nutrient media, and showing a false negative result in traditional microbiological expertise. Because of the biohazard of such dormant cells, it is advisable to provide regulated testing of foodstuffs for presence of VBNC cells.