Evaluation of the effects of probiotic strains of nisin producing Lactococcus lactis on reducing the number of microbial pathogens

The aim of this study was to evaluate the effect of bacteriocin-nisin-producing strains of standard pathogenic strains in culture medium and raw chicken meat at 12°C. The number of bacteria studied in the control and experiment groups was measured on days 0, 3, 5 and 7 after inoculation. Protein and pH levels in meat were examined on days 0, 3, 5, 5 and 7 after inoculation and the presence of nisin gene in probiotics were evaluated. The data showed that Lactococcus lactis had significant inhibitory effects (p≤0.05) on the pathogens studied in liquid BHI and chicken meat. The pH of chicken meat inoculated with Lactococcus lactis increased significantly (p<0.05) during 7 days of storage at 12°C, from 5.9 ± 0.1 on day 0 to 6.9± 0.2 on 7th day. The average amount of protein in chicken meat inoculated with Lactococcus lactis at 12°C decreased from 17.93 ± 1.05 on day 0 to 14.23±1.25 on 7th day and this reduction in protein was statistically significant (p<0.05). Regarding to the prevalence of probiotic foods and the emergence of positive potential of this type of food products, the present study showed that lactococcal producing nisin can maintain the freshness of chicken and reduce its spoilage by decreasing population of pathogenic bacteria.