Inhibitory effect of some probiotic strains and essential oils on the growth of some foodborne pathogens

Abstract

Background: Bacillus cereus and Yersinia enterocolitica are implicated in foodborne diseases (FBD) which have major effects on human health, therefore it is considered as universal public-health disorders. Essential oils and essential oils Nano emulsions have a sufficient antibacterial performance against a variety of bacteria especially multi-drug resistant bacteria. Probiotics showed several health benefits via moderating the GIT microbiota and their metabolites. Aim: The study was designed for evaluating the biocontrol ability of cinnamon essential oil Nano emulsion and probiotics as natural antibacterial additives and reveal their bactericidal mechanism. Methods: 250 random samples (50 raw milk, 50 rice pudding, 50 kariesh cheese, 50 yoghurt and 50 ice cream) were purchased separately from different areas in Mansoura city, Egypt and exposed to bacteriological analysis. Results: Bacillus cereus was found with the highest mean value of 66x107 ± 1.3x108 CFU/g in raw milk and the lowest mean value of 28x107 ± 2.6x107 CFU/g in kariesh cheese while Yersinia enterocolitica were found in 64% of the total inspected samples with the highest incidence (84%) in yoghurt. The toxinogenic potential of the tested pathogens have been evaluated by multiplex PCR pointing nhe A and ces genes for Bacillus cereus isolates while targeting in Y. enterocolitica 16s rRNA, and YST gene. Different concentrations (0.17%, 0.25%, 0.5%, 0.8%, 1%, 1.5%, and 2%) of cinnamon oil Nano emulsion were employed in this study. CEO (Cinnamon essential oil) Nano emulsion had the highest reduction rate at a concentration of 1.5% in case of Bacillus cereus and 2% in case of Y. enterocolitica. Among different types of probiotics, the best one which showed inhibitory potential against Bacillus cereus and Y. enterocolitica was L. plantarum. Conclusion: L. plantarum and CEO Nano emulsion at a concentration of 2% have the highest reduction rate against Y. enterocolitica while, L. plantarum and CEO Nano emulsion at a concentration of 1.5% have the best antibacterial effect against Bacillus cereus. In conclusion, more attention is required for both safety and quality in dairy products through application of natural additives as essential oils and probiotics.