## Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \(Gly_{0}\) & & **Time** & \(Gly_{0}\) & \(r_{\rm Gly}\) & \(X\) & **M1** & **Ery** & **Ara** & \(Pol\) & \(Y_{\rm Poly}\) \\ (g/L) & & (h) & (g/L) & (g/L) & (g/L) & (g/L) & (g/L) & (g/L) & (g/L) & (g/L) \\ \hline \(\approx\)70 & a, b, c & 134 & \(65.0\pm 4.5\) & 0.54 & 16.1 \(\pm\) 1.5 & \(9.2\pm 1.4\) & \(7.3\pm 1.2\) & \(4.1\pm 0.7\) & \(20.6\pm 3.3\) & 0.32 \\  & d & 183 & \(65.6\pm 3.9\) & & \(22.4\pm 2.0\) & \(6.1\pm 0.8\) & \(3.1\pm 0.6\) & \(1.9\pm 0.4\) & \(11.1\pm 1.8\) & 0.17 \\ \hline \(\approx\)100 & a, b, c, d & 183 & \(95.4\pm 7.1\) & 0.52 & \(15.0\pm 1.9\) & \(13.8\pm 2.2\) & \(17.1\pm 2.5\) & \(7.3\pm 1.2\) & \(38.2\pm 5.9\) & 0.40 \\ \hline \(\approx\)120 & a, b, c, d & 250 & \(109.2\pm 9.0\) & 0.45 & \(13.5\pm 2.1\) & \(15.7\pm 2.4\) & \(20.6\pm 2.8\) & \(7.1\pm 1.1\) & \(43.4\pm 6.3\) & 0.40 \\ \hline \(\approx\)150 & a, b, c, d & 280 & \(120.5\pm 12.8\) & 0.37 & \(11.1\pm 1.8\) & \(13.1\pm 2.0\) & \(24.1\pm 4.0\) & \(14.1\pm 2.1\) & \(51.3\pm 8.1\) & 0.43 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Quantitative data of cultures of _Yarroxia lipolytica_ LMBF Y-46 on glycerol-based media in which various initial glycerol concentrations (\(Gly_{0}\)) were added with nitrogen being added to the medium as ammonium sulfate (2.0 g/L) and yeast extract (3.0 g/L). Culture conditions: growth in 250 mL conical flasks (at 180 rpm, initial pH = \(6.0\pm 0.1\), pH ranging between 4.4 and 6.1, incubation temperature \(T=28\pm 1\)\({}^{\circ}\)C). Culture details when the maximum concentration of mannitol (Ml, g/L) (a), erythittol (Ery, g/L) (b), arabitol (Ara, g/L) (c) and yeast dry cell biomass (\(X\), g/L) (d) was achieved. \(Pol\) is the sum of polyols (in g/L) at the given fermentation times. Each experimental point presented is the mean value of two independent determinations. high \(Gly_{0}\) concentration media, glycerol was not fully consumed (see Table 1). Nevertheless, by taking into consideration that in high \(Gly_{0}\) concentration media in which glycerol had not been completely assimilated (Table 1) glycerol uptake was always constant, it is strongly possible that further incubation would decrease the content of glycerol even more and increase the _Pol_ biosynthesis in these cultures. _Y. lipolytica_ LMBF Y-46 growth on glycerol in shake flasks with various \(Gly_{0}\) concentrations into the medium was performed under full aerobic conditions; DOT was measured mainly at the phase in which polyols were secreted into the medium, and irrespective of the \(Gly_{0}\) quantities added into the medium, DOT values ranged between 20% and 50% \(\forall\)/\(\forall\). On the other hand, the more the \(Gly_{0}\) quantity into the medium increased, the more _Pol_ concentration increased (Table 1), in accordance with results indicated for other wild-type _Y. lipolytica_ strains [18; 21; 22]. Furthermore, in the experiment with the somehow lower \(Gly_{0}\) concentration added into the medium (\(Gly_{0}\approx 70\) g/L), when the glycerol concentration from the medium was exhausted, polyols re-consumption and new yeast cell biomass occurred (Table 1). Re-consumption of extra-cellular and previously synthesized polyols in favor of the biosynthesis of new cell material (or potentially the production of other metabolites, like citric acid) has been observed in batch cultures performed by various wild-type _Y. lipolytica_ strains [20; 21; 22; 35; 38]. Moreover, as stated, when higher \(Gly_{0}\) concentrations were employed, in absolute values (_viz._ g/L), enhanced production of polyols occurred. It can be hypothesized that in the trials with high \(Gly_{0}\) concentrations, either the increment of carbon excess or the increased osmotic pressure into the medium due to high \(Gly_{0}\) quantities [2; 4; 10; 13] enhanced _Pol_ production in _Y. lipolytica_ LMBF Y-46.