# Endophytic Yeasts for the Biocontrol of _Phycetema vagabunda_ in Apples
## 3 Results
### Chemical Characterization of Volatile Organic Compounds  
The VOCs produced by yeast strains EPL4.5 and EPL29.5 on the mediums AJA and YPD were analyzed by GC-MS (Figure 4). The VOCs present in just AJA or YPD medium without any yeast were not considered to be produced by _V. victoriae_ EPL4.5 and EPL29.5. A total of 10 compounds were detected, including 5 alcohols, 2 ketones, and 3 hydrocarbons.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Yeast Strain**} & \multicolumn{2}{c}{**Colony Forming Unit Inhibition (\%)**} & \multicolumn{2}{c}{**Mycelial Growth Inhibition (\%)**} \\ \cline{2-5}  & **YPD** & **AJA** & **YPD** & **AJA** \\ \hline EPL4.5 & 54.84 \(\pm\) 27.4 & 10.38 \(\pm\) 21.9 & 69.14 \(\pm\) 3.6 * & 42.1 \(\pm\) 7.4 \\ \hline EPL29.5 & 50.63 \(\pm\) 7.6 & 19.44 \(\pm\) 7.3 & 66.10 \(\pm\) 12.1 & 43.62 \(\pm\) 2.4 \\ \hline \hline \end{tabular} Data expressed as mean \(\pm\) standard error. Asterisks denote a significant difference among treatments for the same yeast strain (EPL4.5 dF = 3, \(p\) = 0.046; EPL29.5 dF = 3, \(p\) = 0.0997), according to Student’s \(t\)-test.  
\end{table}
Table 2: Effect of VOCs produced by _Vishniacozyma victoriae_ yeast strains EPL4.5 and EPL29.5 in Yeast Peptone Dextrose Agar (YPD) and apple juice agar (AJA) mediums on colony-forming unit and mycelial growth of _Phylcetema vagabunda_ at 20 \({}^{\circ}\)C.  
Figure 3: Inhibition of _Phylcetema vagabunda_ growth by _Vishniacozyma victoriae_ strains EPL4.5 and EPL29.5 antifungal volatile compounds activity on double Petri dish. Pathogen colony-forming unit and mycelial growth were inhibited in the presence of the yeast compared to the control.  
Figure 4: Gas Chromatography-Mass Spectrometry traces (total ion chromatograms) of VOCs collected in SPME. (**a**) _Vishniacozyma victoriae_ EPL4.5 on AJA medium, (**b**) _Vishniacozyma victoriae_ EPL4.5 on YPD medium, (**c**) _Vishniacozyma victoriae_ EPL29.5 on AJA medium, (**d**) _Vishniacozyma victoriae_ EPL29.5 on YPD medium. Peak top numbers refer to compounds listed in Table 3.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Peak Number** & **RT(min)** & **Possible Compound** & **Molecular Formula** & \(m\)/\(z\) & \multicolumn{3}{c}{**Relative Abundance (\%)**} \\  & & & & **EPL4.5** & \multicolumn{3}{c}{**EPL29.5**} \\  & & & & **AJA** & **YPD** & **AJA** & **YPD** \\ \hline
10 & 5.95 & Cyclotrisiloxane, & & & & & \\  & & hexamethyl- \# & & & & & \\
11 & 7.32 & 1-Hexanol & & & & & \\
12 & 7.99 & 2-Heptanone & & & & & \\
13 & 14.51 & 2-Nonanone & & & & & \\
14 & 16.45 & Cyclopentaniloxane, & & & & & \\  & decamethyl \# & & & & & \\
15 & 20.35 & Cyclohexalkane, & & & & & \\  & & dodecamethyl \# & & & & & \\ \hline \hline \end{tabular} Not detected is referred to as N.D. # Putative compounds from the column and fiber.  
\end{table}
Table 3: _Cont._On the YPD medium, the most abundant compound was 1-Butanol; the abundance relative area (RA) of this compound was 46.34% and 38.7% for strains EPL4.5 and EPL29.5, respectively. The rest of the components produced by the strain EPL4.5 on YPD medium mainly corresponded to 1-Butanol, 3-methyl and Disulfide, dimethyl representing an RA of 8.18% and 2.47%. The EPL29.5 strain on YPD medium produced mainly corresponded to 1-Butanol, 3-methyl; 1-Butanol, 2-methyl-, (S)- and 1-Propanol, 2-methyl with an RA between 17.63% and 1.97% (Table 3).  
The most abundant compound produced by both yeast strains on the AJA medium was 1-Butanol, 2-methyl-, (S)-; the abundance relative area (RA) of this compound was 19.6% and 13.27% for strains EPL4.5 and EPL29.5, respectively. The rest of the components produced by the strain EPL4.5 on AJA medium mainly corresponded to 1-Butanol; 1-Hexanol and 1-Butanol, 3-methyl with a RA between 3.98% and 1.94%. The EPL29.5 strain on AJA medium produced were 1-Butanol; 1-Hexanol; 1-Propanol, 2-methyl; 2-Nonanone, and 2-Heptanone with a RA between 5.25% and 1.65% (Table 3).