## 3 Results
### Biomass Characteristics of the Oleaginous Yeast Y. lipolytica
\begin{table}
\begin{tabular}{l c c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**Unit**} & \multicolumn{5}{c}{**Water Used for the Culture Medium**} \\ \cline{3-6}  & & **Distilled Water** & \multicolumn{1}{c}{**Top Water (U)—65 h**} & \multicolumn{1}{c}{**Top Water (U)—20 h**} \\ \hline Initial concentration of carbon source & \(\mathrm{g/dm^{3}}\) & 75 & 125 & 75 & 50 \\ Time & \(\mathrm{h}\) & 43 & 65 & 43 & 65 & 20 \\ Duration of lag phase & \(\mathrm{h}\) & 11.1 & & 11.4 & 11.7 \\ \(\mathrm{[t_{lag}]}\) & \(\mathrm{h}\) & 9.21 & 24.89 & 8.17 & 22.33 & 16.44 \\ Biomass yield & \(\mathrm{g_{d.m.}/dm^{3}}\) & (\(\pm\)0.76) & (\(\pm\)0.94) & (\(\pm\)0.73) & (\(\pm\)4.56) & (\(\pm\)1.57) \\ Maximum concentration of & \(\mathrm{g/dm^{3}}\) & 2.39 & 7.47 & 2.20 & 7.37 & 6.41 \\ lipids produced & \(\mathrm{g/dm^{3}}\) & 2.39 & 7.47 & 2.20 & 7.37 & 6.41 \\ \(\mathrm{[I_{max}]}\) & & & & & & \\ Conversion yield of biomass per & \(\mathrm{g_{d.m.}/g}\) & 0.12 & 0.2 & 0.11 & 0.3 & 0.33 \\ \(\mathrm{[Y_{X/S}]}\) & & & & & & \\ Conversion yield of storage lipids per & \(\mathrm{g/g_{d.m.}}\) & 0.26 & 0.30 & 0.27 & 0.33 & 0.39 \\ \(\mathrm{[Y_{L/X}]}\) & & & & & & \\ Conversion yield of storage lipids per & \(\mathrm{g/g}\) & 0.03 & 0.06 & 0.03 & 0.1 & 0.13 \\ \(\mathrm{[Y_{L/S}]}\) & & & & & & \\ Volumetric rate of storage & \(\mathrm{g/dm^{3}/h}\) & 0.06 & 0.11 & 0.05 & 0.11 & 0.32 \\ \(\mathrm{[q_{ls}]}\) & & & & & & \\ Specific rate of storage & \(\mathrm{lipid}\) production & \(\mathrm{g/g_{d.m.}/h}\) & 0.006 & 0.005 & 0.006 & 0.005 & 0.02 \\ \(\mathrm{[q_{l}]}\) & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Kinetic parameters of storage lipid biosynthesis, cell lipid, protein, and other cell constituents content in a batch bioreactor culture of _Y. lipolytica_, depending on the type of water used in the culture medium and the biomass sampling time (_p_ < 0.05). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Water Used for the Culture Medium**} & \multirow{2}{*}{**Time**} & \multirow{2}{*}{**Protein Content**} & \multirow{2}{*}{**Lipid Content**} & \multicolumn{2}{c}{**Content of Other Cell**} \\  & & **[\% DM]** & **[\% DM]** & **Constituents * \\ \hline Distilled water & 65 & 24.16(\(\pm\)1.50) a & 39.43 (\(\pm\)2.22) a & 36.41 \\ Tap water (U) & 65 & 27.03(\(\pm\)1.75) a & 48.95 (\(\pm\)2.90) b & 24.02 \\ Tap water (U) & 20 & 25.49 (\(\pm\)1.67) a & 50.53 (\(\pm\)2.16) b & 23.98 \\ \hline \hline \end{tabular}  
* U—tap water collected at the right bank of the Vistula River in Warsaw; DM—dry matter. a,b—non-homogeneous groups. *—result representing the difference between the biomass weight and the determined protein and fat content.  
\end{table} 
Table 3: The contents of individual components in the dry biomass of _Y. lipolytica_ yeast cultured in batch and fed-batch cultures. The standard deviation is given in brackets (_p_ < 0.05). In addition to the composition and efficiency of biomass, the economic viability of its production on an industrial scale is also of significant importance. Techno-economic studies estimate that the cost of single-cell protein (SCP) from _Y. lipolytica_ can range from 1.0 to 4.2 USD/kg, depending on scale, substrate, and process configuration [45,46]. Still, volumetric productivity of yeast lipids remains low (<100 g/L), requiring large-scale processing for industrial viability [47]. Although engineered _Y. lipolytica_ strains have achieved up to 1.2 g/L/h in glucose-based media [48], the economic feasibility of heterotrophic processes is still uncertain [45]. Techno-economic analyses estimate microbial oil production costs at $1.7-$5.9/kg, which remain significantly higher than those of plant oils ($0.5-$1.9/kg). The short generation time of yeast cultures, the long history of their use, and the valu