Combined antimicrobial effect of essential oils and bacteriocins against foodborne pathogens and food spoilage bacteria
Mélanie Turgis, Khanh Dang Vu, Claude Dupon Monique Lacroix
INRS-Institut Armand-Frappier, Research Laboratories in Sciences Applied to Food, 531, Boulevard des Prairies, Laval, Québec, Canada, H7V 1B7.
This study was achieved in order to determine the antimicrobial potential of six essential oils (EOs) (Origanum vulgare, Cinnamomum cassia, Brassica hirta, Thymus vulgaris, Satureja montagna, and Cymbopogon nardus) and four bacteriocins (nisin, pediocin, and two bacteriocins produced from our isolated Enterococcus faecium MT 104 and MT 162) against five pathogenic bacteria and two spoilage bacteria. The synergistic effect of combined antimicrobial agents on pathogenic bacteria was also evaluated. The antimicrobial activity was determined by evaluation of minimum inhibitory concentration (MIC) of the tested antimicrobial agents. Each agent was tested against seven bacterial foodborne pathogens (Bacillus cereus, Escherichia coli, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus) and food spoilage (Lactobacillus sakei and Pseudomonas putida) in 96-well microplate. The checkerboard technique was used to evaluate the possible synergistic effects between antimicrobial agents against each bacterium. The MIC value of 500 ppm was obtained when C. cassia and O. vulgare EOs were tested against B. cereus, E. coli O157:H7, and L. sakei and when B. hirta EO was tested against P. putida and S. aureus. The combination of nisin with O. vulgare EO induced a synergistic effect against L. monocytogenes whereas the combination of nisin with T. vulgaris EO caused a synergistic effect against S. typhimurium. Pediocin caused a synergistic effect against E. coli O157: H7 when combined with the S. montagna EO. The combinations of EOs and bacteriocins can act synergistically or additionally to eliminate important foodborne pathogens and spoilage bacteria. This study demonstrated the potential of using different combinations of natural antimicrobial compounds to control foodborne pathogens effectively.