## 3 Results
### Substrate Specificity of Y. lipolytica Extracellular Lipases in Crude and Purified Lipase Solutions  
The subsequent part of the current work was devoted to the examination of the substrate specificity of _Y. lipolytica_ extracellular lipases. In this case, firstly, four plant oils (olive, rice, corn, and peanut) were analyzed for their total fatty acid composition in oils and fatty acid composition in triacylglycerols at the _sn_-2 position (Table 3). All the oils had a high content of unsaturated fatty acids in the triacylglycerol molecules. The highest oleic acid content (C18:1) was found in olive oil (72.9%), a lower content in peanut oil (59.3%) and rice oil (41.9%), and the lowest content in corn oil (24.4%) (Table 3). The highest content of linoleic acid (C18:2) was also determined; therein, the highest amounts of this compound were detected in corn oil (58.5%) and rice oil (35.9%). It is worth emphasizing that the sum of the oleic and linoleic acid contents in all four plant oils varied, from 78% for rice oil and 83% for corn oil. Other fatty acids were present in small amounts of less than 2%. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Plant Oil**} & \multirow{2}{*}{\begin{tabular}{c} **Position of Fatty Acid** \\ **in Triacylglycerlycerols** \\ \end{tabular} } & \multicolumn{6}{c}{**Fatty Acid Content (\%)**} & \multicolumn{6}{c}{**Sum of Saturated Fatty**} & \multirow{2}{*}{\
\begin{tabular}{c} **Acid Value** \\ **(mg KOH/g)** \\ \end{tabular} } \\ \cline{3-11}  & & **sn-1**,2,3 & 0.45 & 0.1 & 72.9 & 9.4 & 0.6 & 1.4 & - & 0.1 & 14.4 & & 0.66 \\ \cline{2-11}  & _sn-2_ & 2.41 & - & 72.37 & 11.50 & 4.96 & - & - & - & & & \\ \cline{2-11}  & _sn-1_,2,3 & 0.15 & - & 41.7 & 35.9 & 1.7 & 0.6 & 0.1 & 0.65 & 15.1 & & & \\ \cline{2-11}  & _sn-2_ & 1.42 & - & 52.78 & 26.23 & 6.23 & - & - & - & & & \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Corn oil \\ \end{tabular} } & _sn-1_,2,3 & - & 0.1 & 24.4 & 58.6 & 0.55 & 0.8 & 0.15 & - & 15.0 & & & \\ \cline{2-11}  & _sn-2_ & 2.05 & - & 29.18 & 64.46 & 0.75 & - & - & - & & & \\ \cline{2-11}  & _sn-1_,2,3 & 0.15 & 0.1 & 59.3 & 19.5 & 0.1 & 1.2 & - & 0.1 & 8.9 & & \\ \cline{2-11}  & _sn-2_ & 1.15 & - & 63.89 & 23.76 & 0.80 & - & - & - & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Fatty acid composition in plant oils (%, all positions in triacylglycerols _sn_-1,2,3), fatty acid composition in _sn_-2 position of triacylglycerols in plant oils (abbreviations: C16:1—palmitoleic acid, C17:1—heptadecenoic acid, C18:1—oleic acid, C18:2—linoleic acid, C18:3—linoleic acid, C20:1—eicosenoic acid, C22:1—erucic acid, C24:1—nervonic acid) and acid values of the studied plant oils. Figure 2: Pareto charts indicating significantly important factors influencing the extracellular hydrolytic activity of **(a)** Y: _Ijolyfic_ ATCC 9812; **(b)** Y: _Ijolyfic_ WT294; **(c)** Y: _Ijolyfic_ ATCC 19842; and **(d)** Y: _Ijolyfic_ KKP 379. Abbreviations: L—linear effect, Q—quadratic effect, IL wz 2L—the interaction of the effects. Figure 3: Response surfaces with second-degree polynomial models for the extracellular hydrolytic activity of (**a**) \(Y\). Hydrolytic ATCC 90812; (**b**) \(Y\). Hydrolytic W29; (**c**) \(Y\). Hydrolytic ATCC 18942; and (**d**) \(Y\). Hydrolytic KKP 390, cultured in YTO medium. Bullet points represent experimental points included in the design. Considering the regioselectivity of the enzyme, oils were analyzed in this study, and were characterized as similarly rich in oleic and linoleic acids at the _sn_-2 triacylglycerolglycerol position as in the _sn_-1,3 position (Table 3). The highest oleic acid content was observed in olive oil, and the highest linoleic acid content in corn oil. The fatty acid residues were distributed proportionally in the molecules of triacylglycerols, so this factor had no significant effect on the level of synthesis of the lipases.