Melissa officinalis is a medicinal plant with high antimicrobial properties. The present study was performed to evaluate the antimicrobial effects of Melissa officinalis essential oil on food-borne bacteria. Melissa officinalis aerial parts were prepared and after approval by experts used to prepare essential oils. The diameter of the growth inhibition zone of Listeria monocytogenes, Salmonella typhimurium, Escherichia coli and Staphylococcus aureus was assessed using disk diffusion and compared with antibiotics. The minimum inhibitory concentration (MIC) and the minimum bacterial concentration (MBC) of Melissa officinalis essential oil were evaluated on the target bacteria. Citronellal (14.4%) and Caryophyllene oxide (11%) were the most important compounds identified in Melissa officinalis essential oil. The diameter of the growth inhibition zone of the bacteria against Melissa officinalis essential oil ranged from 3.93±0.42 to 15.23±1.17 mm. Application of 4 mg/ml concentration of Melissa officinalis essential oil caused the largest diameter of the growth inhibition zone of Staphylococcus aureus (14.70±0.27 mm), Escherichia coli (10.33±0.29 mm) and Salmonella typhimurium (10.18±0.52 mm). The antimicrobial effects of Melissa officinalis essential oil were dose-dependent (P <0.05). The lowest and highest levels of MIC and MBC of Melissa officinalis essential oil were obtained for Staphylococcus aureus (1.25 and 2.5, respectively) and Salmonella typhimurium (10 and 20, respectively). The diameter of the growth inhibition zone of bacteria treated with Melissa officinalis essential oil was higher than that of many antibiotics, but lower than that of vancomycin. Melissa officinalis essential oil can be used as a substance with antimicrobial properties, especially in food films.
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