Determination of Antibacterial Mode of Action of Allium sativum Essential Oil against Foodborne Pathogens Using Membrane Permeability and Surface Characteristic Parameters

This study investigates the antibacterial mechanism of action of Allium sativum rhizome essential oil (ASEO) against foodborne pathogens. The ASEO was obtained by hydrodistillation of A.sativum rhizome using a microwave-assisted extraction technique. The ASEO (1,000g/disk) showed potential antibacterial effect as diameters of inhibition zones against the tested foodborne pathogens including American Type Culture Collection (ATCC) strains Bacillus cereusATCC 13061, Escherichia coliATCC 43889, Listeria monocytogenesATCC 7644, Salmonella Typhimurium ATCC 43174 and Staphylococcus aureusATCC 12600, which were found in the range of 11.0 +/- 0.124.0 +/- 0.1mm. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of ASEO against the tested bacteria were found in the range of 62.5500g/mL. At the MIC concentration, ASEO had potential inhibitory effect on the cell viability of the tested bacteria. In addition, the scanning electron microscopy analysis showed the inhibitory effect of ASEO as confirmed by the considerable morphological alterations on the cell walls of B.cereusATCC 13061 and E.coliATCC 43889. Moreover, the ASEO revealed its mode of action on membrane integrity as confirmed by the release of extracellular adenosine 5-triphosphate, 260-nm absorbing materials and potassium ions efflux against tested pathogens. These findings suggest that ASEO showed its effect on membrane permeability and surface characteristics. Practical Applications Foodborne pathogens are the leading causes of illness in the developed countries. These pathogens are responsible for millions of cases of infectious diseases each year, costing billions of dollars in medical care. New foodborne pathogens and foodborne diseases are likely to emerge driven by factors such as pathogen evolution, changes in food manufacturing practices, and changes to the human host status. Fuelled by these concerns, research on biologically active natural compounds to control the foodborne pathogens has escalated to unprecedented levels in recent years. Plant-based antimicrobials such as essential oils have been found to suppress the growth of foodborne pathogens in various in vitro and in vivo models. These findings clearly indicate that essential oil derived from the rhizome of A.sativum confers its mode of action on membrane integrity, hence, could be used as an affective candidate to control the growth of certain important foodborne pathogens in practical applications.