Thymus vulgaris L. essential oils from Emilia Romagna Apennines (Italy): phytochemical composition and antimicrobial activity on food-borne pathogens

Between Modena and Bologna Apennines (Italy), several agricultural farms have recently been dedicated to the cultivation of autochthonous aromatic plants as primary cultivation or to complement other crops. In this study, the chemical composition of Thymus vulgaris L. essential oils (EOs) from this region was evaluated by means of gas-chromatographic analysis. Three different mulching techniques, in particular, soil coverage with grass, mulch with plastic film and with straw were investigated. The results highlighted that mulching techniques influenced the composition of the analysed EOs. All the EOs exerted good antimicrobial activity against clinical and food strains of the pathogen Listeria monocytogenes, with differences related to the composition. The EO obtained from plants covered with grass showed the best results, having MIC ≤ 2.5 µL/mL, and being able to inhibit also antibiotic-resistant strains, thus confirming that soil coverage with grass influences the composition and also the biological activity of Thymus vulgaris EO.