Combined antimicrobial effect of bacteriocins of LAB isolated from a traditional brine table olives and essential oils against foodborne pathogens

The study aimed to determine the antimicrobial activity of bacteriocinogenic lactic acid bacteria isolated from olive brine and three essential oils (Thyme, Rosemary and Oregano Eos) alone and in combination against the Gram-positive L. monocytogenes and the Gram-negative E. coli O157: H7. The antimicrobial activity was determined by evaluation of minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the tested antimicrobial agents. The evaluation demonstrates that the two CFSs of lactic strains and the purified bacteriocins inhibit the growth of both L. monocytogenes and E. coli. The results showed that thyme EO is most effective followed by rosemary and Oregano Eos. Thus, all combination executed against L. monocytogenes using the checkerboard technique showed an additive effect unless the CFSs of LAB in combination with Thyme EO which showed no interactive effect. Whereas the combination against E. coli, only two bacteriocins in combination with Thyme EO and ELBC02 bacteriocin in combination with Rosemary EO that showed an additive effect. The results obtained in these studies coupled with the right knowledge opens the way to the combination as a new field of application whose goal is confined to conservation and the safety of food.