The Mechanism of Bactericidal Action of Oregano and Clove Essential Oils and of Their Phenolic Major Components on<i>Escherichia coli</i>and<i>Bacillus subtilis</i>

Abstract The mechanism of the antimicrobial action of orégano (Origanum compactum) and clove essential oils was studied simultaneously with two phenolic components, namely thymol and eugenol. Escherichia coli and Bacillus subtilis were used as Gram negative and Gram positive bacterial models, respectively. The oils as well as their major components were capable of inducing cell lysis. Bacteria lysis was shown by the release of substances absorbing at 260 nm. For E. coli, the results were similar to those obtained with polymyxin B. Scanning electronic microscope observations revealed that both cell wall and membrane of the treated bacteria were significantly damaged.