Essential Oil of Common Thyme as a Natural Antimicrobial Food Additive

Sabina Anžlovar¹, Dea Baričevič², Jerneja Ambrožič Avguštin¹ and Jasna Dolenc Koce^1*

¹Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana, Slovenia
²Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia

Article history:
Received: October 9, 2013
Accepted: April 4, 2014

Key words:
Thymus vulgaris, essential oil, antibacterial activity, multidrug-resistant bacteria, antifungal activity, food additive

Summary:
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.

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