## 3 Results
### In vitro Antibacterial and Antifungal Effects
#### 3.3.2 Disc Volatilization Method  
The _in vitro_ antifungal and antibacterial effects of EGEO were assessed according to the absence or the presence of inhibition zones. The DIZ resulting from the exposure to EGEO vapors is shown in Tables 3 and 4. The DIZ due to the same quantity of EGEO was larger for yeast than for mycelial species (Figure 1A,B). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**DIZ (mm) a**} \\ \hline  & \multicolumn{3}{c}{**Disc Diffusion Technique**} & \multicolumn{3}{c}{**Disc Vapor Technique**} \\ \hline
**Bacterial Strains** & \multicolumn{3}{c}{**Volume of EGEO (\(\mu\)L) per Disc**} & \multicolumn{3}{c}{**Positive Control b**} \\ \hline Gram-negative bacteria & 20 & 40 & 60 & 20 & 40 & 60 & AMC & E & C \\ \hline _Pseudomonas aeruginosa_ & - & - & - & - & - & - & 16 & 14 \\ _Enterobacter sakazaki_ & 12 & 15 & 25 & - & 85 & 85 & - & 19 & 27 \\ _Klebsiella ornithinolytica_ & - & 10 & 19 & - & - & - & - & 22 & 12 \\ _Escherichia coli_ & 11 & 19 & 34 & - & - & 36 & 12 & 19 & 7 \\ \hline Gram-positive bacteria & & & & & & & & & \\ \hline _Bacillus cereus_ & 15 & 35 & 50 & 24 & 40 & 59 & 25 & 35 & 24 \\ _Staphylococcus aureus_ & 18 & 48 & 85 & 41 & 85 & 85 & 26 & R & 16 \\ \hline \hline \end{tabular}  
* Diameter of inhibition zone (mm) comprising a disc diameter of 9 mm; b Amoxicillin-clavulanic acid (AMC, 20/10 \(\mu\)g), erythromycinycin (E, 15 \(\mu\)g) and chloramphenicol (C, 30 \(\mu\)g) were tested as a positive control for microbial species. EGEO: _Eucalyptus globulus_ essential oil. (-) No activity.  
\end{table} 
Table 3: Susceptibility of bacterial strains to _Eucalyptus globulus_ essential oil and to classic antibiotics (positive controls). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**DIZ (mm) a**} \\ \hline \multicolumn{6}{c}{**Disc Diffusion Assay**} & \multicolumn{6}{c}{**Disc Volatilization Assay**} \\ \hline
**Fungal Strains** & \multicolumn{6}{c}{**Quantity of EGEO (\(\mu\)L) per Disc**} & \multicolumn{6}{c}{**Hex b**} \\ \hline Yeasts & 20 & 40 & 60 & 20 & 40 & 60 & 40 \\ \hline _Candida albicans_ ATCC & - & 11 & 40 & - & - & - & 30 \\ _Candida albicans_ (Ca1) & 10 & 25 & 27 & - & - & 53 & 85 \\ _Candida albicans_ (Ca2) & 14 & 19 & 24 & 85 & 85 & 85 & 13 \\ _Candida paralysis_ & 12 & 17 & 20 & 85 & 85 & 85 & 30 \\ _Saccharomyces cerevisiae_ & 11 & 37 & 49 & - & - & 59 & - \\ _Trichospor_ sp. & 16 & 34 & 39 & 21 & 85 & 85 & 42 \\ \hline \multicolumn{6}{c}{**Molds**} \\ \hline _Aspergillus niger_ (An1) & 12 & 21 & 29 & - & - & - & - \\ _Aspergillus niger_ (An2) & - & 10 & 15 & - & - & - & - \\ _Aspergillus fumigatus_ & - & - & - & - & - & - & - \\ _Aspergillus flavus_ & - & - & - & - & - & - & - \\ _Aspergillus brasiliensis_ & - & - & 14 & - & 43 & 85 & 14 \\ ATCC & - & - & 14 & - & 43 & 85 & 14 \\ \hline \end{tabular}  
* Diameter of inhibition zone (mm) including a disc diameter of 9 mm; b Antiseptic solution (Horamidine 0.1%) used as a positive control for fungal strains. EGEO: _Eucalyptus globulus_ essential oil; (-) No inhibitory effect; ATCC: American Type Culture Collection.  
\end{table} 
Table 4: Susceptibility of fungal strains to _Eucalyptus globulus_ essential oil and antiseptic solution. Figure 1: _In vitro_ inhibitory activity of _Eucalyptus globulus_ essential oil against bacterial and fungal species: Disc diffusion (**A**) versus vapor diffusion (**B**) methods using three different quantities of EO (20, 40 and 60 \(\mu\)L/disc). Red arrows are the diameter of the inhibitory zone (DIZ). As detected in the previous analyses using EGEO in the liquid phase, the DIZ due to EGEO vapors augmented with an increasing amount of the EGEO and followed a similar tendency with respect to the different microbial species. Nevertheless, in comparison with the liquid phase, the EGEO vapors resulted in considerably superior DIZ in all the yeast strains tested, except _Candida albicans_ ATCC.