## 2 Results
### Effect of Plasma Water on the Lipolytic Activity of the Y. lipolytica Yeast  
The extracellular lipolytic activity of the microorganism is crucial to the efficiency of the biosynthesis of GDL, a peach-aroma cyclic ester, and other volatile metabolites. The substrate in the synthesis of the above-mentioned lactose is ricinoleic acid, which constitutes about 90% of castor oil triglycerides [31], which are used in biotransformation media. The first step of biosynthesis is the hydrolysis of triglycerides catalyzed by lipases. Figure 3 shows data on the extracellular lipolytic activity of _Yarrowia_ yeast grown on plasma water media (dashed lines). The results indicated that the highest lipolytic activity at the level of approx. 0.322 \(\pm\) 0.013 U/mL was found in the medium based on Nantes plasma water with an increased singlet oxygen content. The maximum activity in the medium was observed on the third day of cultivation. A similar time of maximum activity was also noted for the PWTA medium, but this was approximately 1.7 times lower (approx. 0.189 \(\pm\) 0.016 U/mL). The lipolytic activity curves determined for the PWTN medium and the control medium were slightly different. In both cases, the maximum activity occurred between 24 and 48 h of cultivation, which was not captured due to measurements taken from 48 h onwards. It is worth emphasizing that in the media based on plasma water, extracellular lipolytic activity was detected for a much longer period of culture than in the control medium. For cultures carried out in media based on plasma water enriched with singlet oxygen (Nantes PW) as well as PWTA medium, lipolytic activity was maintained throughout the culture period (192 h), while for the control medium, the lipase activity completely disappeared after 96 h, and no active lipases were detected. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{5}{c}{**Type of Medium**} \\ \cline{2-5}  & **Control Medium** & **PWTN** & **PWTA** & **Nantes PW** \\ \hline \(\mu_{\text{max}}\) (h\({}^{-1}\)) & 0.056 \({}^{\text{a}}\) & 0.088 \({}^{\text{b}}\) & 0.062 \({}^{\text{a}}\) & 0.136 \({}^{\text{c}}\) \\ \(X_{\text{max}}\) (g of dried mass/10\({}^{8}\) cells) & 1.41 \({}^{\text{a}}\) & 1.74 \({}^{\text{b}}\) & 1.60 \({}^{\text{b}}\) & 2.29 \({}^{\text{c}}\) \\ \(YX_{\text{max}}\)/S (g\({}_{\text{d,w.}}\)/g) & 0.066 \({}^{\text{a}}\) & 0.105 \({}^{\text{c}}\) & 0.087 \({}^{\text{b}}\) & 0.163 \({}^{\text{d}}\) \\ \hline \hline \end{tabular} Mean values followed by the same letter are not significantly different according to HSD Tukey (\(p\leq 0.05\)).  
\end{table} 
Table 1: The maximum specific growth rate (\(\mu_{\text{max}}\)), maximum biomass concentration (\(X_{\text{max}}\), g/L/10\({}^{8}\) cells) and the level of yield of biomass from the substrate (\(Y_{\text{max}}\)/S, g.dw./g) of _Y. lipolytica_ cultivated in medium based on low-pressure glow plasma water saturated with air, nitrogen or molecular oxygen (Nantes PW). Kinetic parameters were calculated according to [PERSON] et al. [29] and [PERSON] et al. [30]. The spectrophotometrically determined extracellular lipolytic activity of _Y. lipolytica_ yeast in culture media was verified by determining the acid value in media (Figure 4). In each of the analyzed media, the parameter was high on the second day of culture and on the last day of the experiment. In the control medium, the acid value was approximately 125.7 \(\pm\) 1.2 mg KOH/g on the 48 th hour of culture and approximately 131.2 \(\pm\) 5.3 mg KOH/g on the 8 th day of culture (192 h). In the plasma water-based media, the acid value was statistically significantly higher, from 8 to 32 mg KOH/g (at 48 h of culture) and from 20 to 46 mg KOH/g oil (on 8 th day of culture). The determined acid value can be partly correlated with the activity of extracellular lipases, which carry out the hydrolysis of castor oil triacylglycerlycerols.