## Materials and Methods
### Microbiological Assays  
Broth macrodilution assays were performed to determine the Minimal Inhibitory Concentration (MIC) and the Minimal Bactericidal Concentration (MBC) for the essential oils according to the CLI protocol [36] with minor modifications as previously described [35]. Two-fold serial dilutions of each oil were prepared in Mueller-Hinton broth (MHB, Oxoid Ltd., Basingstoke, UK), with a concentration range of 4% (_v/v_) to 0.016% (_v/v_). Tween 20 (Thermo Fisher Scientific, Waltham, MA, USA) was used as a solubilizer at a concentration of 0.5% (_v/v_). Bacterial inoculum measured by DEN-1 densitometer (Grant Ltd., Cambridgeshire, UK) at a turbidity of 0.5 McFarland (1-1.5 \(\times\) 10\({}^{8}\) cfu/mL), was transferred into MHB to obtain a bacterial count of 5 \(\times\) 10\({}^{5}\) cfu/mL. After a 24 h incubation at 37 \({}^{\circ}\)C aerobically, an appropriate amount of 10 \(\mu\)L was plated onto Mueller-Hinton agar (MHA, Oxoid Ltd., Basingstoke, UK) and incubated under the aforementioned conditions. Viable counts method was used for determination of MIC and MBC values. The MIC is defined as the lowest concentration of an antimicrobial agent that prevents visible growth of a microorganism in an agar or broth dilution susceptibility test. The MBC is identified by determining the lowest concentration of antibacterial agent that reduces the viability of the initial bacterial inoculum by a pre-determined reduction such as \(\geq\)99.9% [37; 38; 39].  
Time-kill kinetics were performed by exposing the tested microorganisms to the two-fold serial concentrations of each essential oil, ranging from 0.063% to 4% (_v/v_) and assessed by viable counts procedure [39]. At 0, 1, 3, 6, 8, 12, 24 and 48 h of the dilutions' incubation, 10-\(\mu\)L amount of each tube was plated onto duplicate plates of MHA and after 24 h of incubation at 37 \({}^{\circ}\)C, plates were checked for  
\begin{table}
\begin{tabular}{c c} \hline \hline  & **GC-17A Gas Chromatograph with GCMS-QP5000** \\ \hline \multirow{2}{*}{**Column:**} & DB-5-MS, 30 \(\times\) 0.32 mm, 0.25 \(\upmu\)m, containing 5\% \\  & phenyl-methylpolysiloxane \\  & 55 \({}^{\circ}\)C, 5 \({}^{\circ}\)C/min to 200 \({}^{\circ}\)C, 1 \({}^{\circ}\)C/min to 210 (2 min), 20 \({}^{\circ}\)C/min to \\ \multirow{2}{*}{**Oven:**} & 270 \({}^{\circ}\)C (3 min) \\  & 240 \({}^{\circ}\)C (splites mode) \\  & 240 \({}^{\circ}\)C \\ \multirow{2}{*}{**Injector:**} & 290 \({}^{\circ}\)C \\  & Scan range: & _m/z_ 50–450 (full scan 70 eV) \\  & Carrier gas: & Helium 1.5 mL/min \\ \hline \multicolumn{3}{c}{**Major Identified Components**} \\ \hline \multicolumn{3}{c}{**Basil oil**} & estragole \\ \hline \multicolumn{3}{c}{**Chamomile blue oil**} & bisabololololol and trans-b-farnesene \\ \hline \multicolumn{3}{c}{**Origanum oil**} & carvacrol and thymol \\ \hline \multicolumn{3}{c}{**Tea tree oil**} & terpinen-4-ol and p-cymene \\ \hline \multicolumn{3}{c}{**Thyme oil**} & thymol, p-cymene, and linalool \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chromatographic conditions and major identified components of the studied essential oils.  
visible bacterial growth. Experiments were performed in triplicate and viable counts (cfu/mL) plotted in logarithmic phase in relation to time.