Antibacterial activity of thyme and rosemary essential oil against Enterococci isolated from meat

Abstract

Traditionally enterococci are considered as part of the lactic acid bacteria. This group of bacteria contaminating mostly food of animal origin and some of them can be resistant to antibiotic. The consumers prefer safe foods free of synthetic additives and therefore interest for natural preservatives is increasing in recent years. The aim of this work was to determine antibacterial activity of essential oil from thyme and rosemary against enterococci. Strains of enterococci were isolated from poultry and pork. The isolates of enterococci were identified as E. faecalis and E. mundtii and their sensitivity to chosen antibiotic (ampicillin, erythromycin, gentamicin, tetracycline and vancomycin) was determined. Enterococci were experimentally inoculated in nutrient broth at concentration 3 - 4 log cfu.ml-1. The influence of thyme and rosemary essential oil at different concentrations and at different temperatures (6 °C and 25 °C) against enterococci was tested. As more effective has proved thyme oil, which reliably inhibited both strains at concentration of 0.05 % at 6 and 25 °C. Rosemary oil at the highest tested concentrations (of 1 %, respectively 1.5 %) only reduced the number of tested strains of enterococci. The higher antibacterial activity of essential oils was determined at 25 °C.