Determination of Antimicrobial Effects of Nisin and Mentha spicata Essential Oil against Escherichia coli O157:H7 Under Various Conditions (pH, Temperature and NaCl Concentration)

Background: plant essential oils and nisin have been known as antimicrobial agents that could be used to control food-borne pathogenic bacteria such as escherichia coli o157:h7. the aim of this study was to evaluate the antimicrobial efficacies of nisin and mentha spicata essential oil (eo) both separately and in combination, against escherichia coli o157:h7 at different temperatures (4, 9 and 14°c), ph (5, 6 and 7) and nacl concentrations (0, 1, 2 and 4%). methods: the chemical components of eo were analysed by gc-ms. the minimum inhibitory concentrations (mic) of nisin and eo were assessed using a broth micro-dilution method. for combinations of the antimicrobials, the differences in population assay were used to determinate their effects. results: the dominant active components of eo were carvone (78.76%) and limonene (11.50%). the eo mic value was 40?l/ml, but nisin did not inhibit the growth of e.coli o157:h7. the susceptibility of e.coli o157:h7 to nisin and eo was found to enhance with increasing incubation temperature, ph and nacl concentration. conclusion: our findings demonstrate that a combination of nisin and mentha spicata essential oil might be a potential source of preservative for the control of e.coli o157:h7 in the food industry.