## 3 Results and Discussion
### Antimicrobial Activities of the Essential Oils  
The qualitative evaluation of the inhibitory effect expressed against different microbial strains was performed by measuring the diameter of the inhibition zone, after incubation of the strains in favorable conditions (Figures 3-6). Analyzing the diameter values of the inhibition zones (Table 5), it can be observed an increased efficiency of thyme essential oil (CI), which showed the highest values for all tested microbial species, followed by sage and fennel essential oil (FEN), which inhibited the multiplication of species both Gram-positive and Gram-negative bacteria, but did not inhibit the multiplication of yeast species. Figure 3: The aspect of the inhibition zones expressed by the Gram-positive strain _Staphylococcus aureus_ ATCC 25923 in the presence of tested EO at 1/10 dilution in DMSO; FEN (fennel EO); SV (sage EO); EUC (eucalyptus EO); CI (thyme EO); PIN (pine EO). Figure 4: The aspect of the inhibition zones expressed by the Gram-negative strains _Pseudomonas aeruginosa_ ATCC 27853 in the presence of tested EO at 1/10 dilution in DMSO; FEN (fennel EO); SV (sage EO); EUC (eucalyptus EO); CI (thyme EO); PIN (pine EO). Figure 5: The aspect of the inhibition zones expressed by the Gram-negative strains _Escherichia coli_ ATCC 25922 in the presence of tested EO at 1/10 dilution in DMSO; FEN (fennel EO); SV (sage EO); EUC (eucalyptus EO); CI (thyme EO); PIN (pine EO). Figure 6: The aspect of the inhibition zones expressed by the yeast strain _Candida albicans_ ATCC 10231 in the presence of tested EO at 1/10 dilution in DMSO; FEN (fennel EO); SV (sage EO); EUC (eucalyptus EO); CI (thyme EO); PIN (pine EO). Although some studies show that essential oils have a more pronounced antimicrobial effect on Gram-positive strains, as opposed to Gram-negative ones, this is not always the case. Some studies show a higher antimicrobial activity of thyme essential oil on _Escherichia coli_ strain compared to the Gram-positive strains tested [97]. The most sensitive strain was the standard strain _Escherichia coli_ ATCC 25922, which showed sensitivity to all the EO tested, with the largest values of the diameters of the inhibition zones. Also, following a study conducted by Semeniuc and contributors [98], in which the antimicrobial activity of thyme oil on the _Escherichia coli_ strain ATCC 25922 was tested by determining the diameters of the inhibition zones, it was observed that the thyme oil has a strong antimicrobial effect on this strain, obtaining a diameter of the inhibition zone of 36-41 mm. Thyme essential oil (CI) has also been shown to inhibit the growth of the _Candida albicans_ microbial strain due to its high carvacrol content in its structure, an aspect also highlighted by Tampieri et al. [99]. Other studies in which the antimicrobial activity of thyme essential oil was tested by the spot inoculation method showed that it has a strong antimicrobial effect on the tested strains, obtaining growth inhibition zones with diameters of 26-54 mm. Thyme EO has also been shown to produce a larger growth inhibition zone than those produced by chloramphenicol, suggesting that thyme EO has a stronger antimicrobial effect than chloramphenicol [81]. _Quantitative evaluation of the antimicrobial effect._ The results of tests performed in a liquid medium confirm the high sensitivity of the standard strain _Escherichia coli_ ATCC25922 to the action of all essential oils, the lowest values of minimum inhibitory concentration (MIC) being recorded for wage (0.156%) and thyme essential oil (0.626%) as is shown in Table 6 and Figure 7.  
The antimicrobial effect of thyme essential oil has been shown in other studies. For example, thyme oil has been shown to inhibit the growth of _Staphylococcus aureus_ and _Escherichia coli_ strains at concentrations of 0.125% [81].