Dilutions used for MIC determination were in Mueller Hinton Broth (MHB, Oxoid), concentrations were different for each EO and bacterial species; 0.5% DMSO was added. The addition of DMSO, an aprotic organic solvent belonging to the category of sulfoxides, had the purpose of facilitating the solubilization of EOs in the culture media. All EOs were stored at 4 C in darkness before use and utilized before the expiration date. EO dilutions were prepared just before the experiments.