Essential Oil of Common Thyme as a Natural Antimicrobial Food Additive

Antimicrobial activities of thyme essential oil against selected microorganisms, including Fusarium sp., Armillaria mellea, Bacillus cereus, Staphylococcus aureus, Buttiauxella sp., Klebsiella pneumoniae, Escherichia coli K-12, AmpC-producing E. coli Z, ESBL-producing E. coli strain of KM clonal group ST131, and E. coli 1138 were evaluated. The antimicrobial efficacy of thyme essential oil was determined using agar well diffusion assays. The growth of all tested bacteria was inhibited at thyme essential oil fractions higher than 1 %, while a fraction of 10 % was needed to inhibit the growth of fungi. We demonstrate that thyme essential oil has a promising activity against food spoilage bacteria, and also against multiresistant AmpC-producing and ESBL-producing bacterial strains isolated from food, which have recently been recognised as public health concerns. On the basis of our data, the thyme essential oil has a potential for use as a growth inhibitor of multidrug-resistant bacteria, and food spoilage and pathogenic bacteria and fungi, to replace commonly used semi-synthetic antimicrobial products.