## Results and Discussion
On the other hand, the total conversion yield of the sum of polyols (_Pol_, g/L) produced per unit of glycerol consumed (\(Y_{PolGly}\), g/g), originated from linear regression of all of the experiments points of _Pol_ produced \(f\) (glycerol consumed) for the batch-flask runs at \(Gly_{0}\approx 100\), 120 and 150 g/L, seemed to be constant and \(\approx\)0.43 g/g (Figure 2). In the above-mentioned figure, the results concerning the production of polyols in the trial in which \(Gly_{0}\approx 70\) g/L were not incorporated, since in the latter case notably lower total polyols quantities, accompanied by remarkably depleted yield \(Y_{Pol/Gly}\) values and higher yeast dry biomass quantities compared with the experiments where \(Gly_{0}\approx 100\), 120 and 150 g/L, were recorded (see Table 1). Moreover, as in the previously mentioned flask cultures (\"effect of different glycerol sources under  
Figure 2: Total polyols (_Pol_, g/L) produced vs. glycerol consumed (g/L) in shake-flask experiments during growth on pure glycerol by _Yarrovia lipolytica_ LMBF Y-46, at elevated initial glycerol concentrations (\(Gly_{0}\approx 100\), 120 and 150 g/L) under nitrogen-limited conditions. Culture conditions: growth on 250 mL conical flasks at 180 \(\pm\) 5 rpm, initial pH = 6.0 \(\pm\) 0.1, pH ranging between 4.5 and 6.1, incubation temperature \(T=28\pm 1\)\({}^{\circ}\)C. Each experimental point is the mean value of two independent determinations (SE \(\leq 18\%\)). nitrogen limitation\"), in this second set of experiments (_Gly\({}_{0}\)_\(\approx\) 70, 100, 120 and 150 g/L) ammonium nitrogen was depleted from the medium at \(t\)\(\approx\) 50-55 h after inoculation; in the second set of trials, the initial NH4\({}^{+}\) concentration was \(\approx\) 550 mg/L, while NH4\({}^{+}\) concentration at \(t\)\(\approx\) 50-55 h after inoculation became \(\approx\)25 \(\pm\) 10 mg/L, andtherefore, nitrogen limitation, accompanied by polyols secretion was noted. In the early stages of the cultivation (\(t\)\(\leq\) 50 h after inoculation), thus, no polyols biosynthesis was observed. Nevertheless, and despite the fact that at the early culture steps glycerol did not contribute to polyols production, the representation of _Pol_ produced \(f\) (glycerol consumed) and the linear regression performed for the batch-flask runs carried out makes sense, as most of the experimental points were found after nitrogen depletion where glycerol assimilation mostly contributed to the synthesis of polyols, whereas the correlation coefficient of the regression (\(t^{2}\) = 0.91) is quite satisfactory (Figure 2). The metrics of polyols produced by yeasts cultivated on glycerol-based media and belonging to _Yarrowia_ and _Candida_ clades, and their comparisons with the current investigation, are presented in Table 2.  
With the exception of a scarce number of reports [50; 52; 54], the yield \(Y_{Pol/Gly}\) has rarely been \(>\)0.60 g/g and in most cases it ranged between 0.40 and 0.55 g/g, in accordance with the results of the current submission. The majority of the studies dealing with the production of polyols by _Y. lipolytica_ strains, has been carried out with the use of mutant (i.e., acetate negative ones) or genetically engineered strains, that have been reported to produce, in many cases, relatively or even much higher _Pol_ quantities compared to the present study (see Table 2). On the other hand, strain LMBF Y-46 is wild-type novel yeast isolate, originated from fish-origin products [17], that has not been previously studied in detail,  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Strain** & **Ery** & **Mil** & **Ara** & _Pol_ & **Y\({}_{Poly}\)** & **Cultivation Type** & **Reference** \\  & **(g/L)** & **(g/L)** & **(g/L)** & **(g/g)** & & & \\ \hline
1.22 \({}^{k}\) & 93.5 & 34.0 & - & 127.5 & 0.43 & Fed-batch reactor & [PERSON] et al. [46] \\ Wratislavia 1.31 \({}^{*}\) & 132.0 & 23.0 & - & 155.0 & 0.52 & Fed-batch reactor & [PERSON] et al.