Antibacterial Activity of Plants Essential Oils Against Some Epidemiologi- cally Relevant Food-Borne Pathogens

The antibacterial activity of essential oils hydrodistilled from local anise, coriander, cumin, marjoram, rosemary and thyme were screened against a group of food-borne pathogens comprising Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Escherichia coli O157:H7, Salmonella Typhimurium and Bacillus cereus. All the tested bacterial strains displayed varying degrees of susceptibility towards the examined oils. Nevertheless Gram-positive bacterial strains were more sensitive than Gram-negative organisms. Furthermore, the antimicrobial activities of the extracted essential oils were found to be related to their major components as identified by Gas chromatography-Mass spectroscopy. Essential oils containing phenolic or aldehydic terpenoids as major constituents were the most active (thyme and cumin oils), followed by those containing alcoholic terpenoids (marjoram and coriander oils). Meanwhile, essential oils containing ketonic terpenoids as major components were moderately active (rosemary oil) and those containing phenolic ethers exhibited relatively weak activity (anise oil). In food industries, the tested essential oils can be used as natural antimicrobial agents in the light of shift away from artificial agents and the move towards natural alternatives.