## 3 Results
### Polysaccharides by P. laurentii NRRL Y-2536  
As mentioned above, in both the trials on the semi-defined lactose-based medium and the second CW, _P. laurentii_ NRRL Y-2536 presented, even since the relatively early growth stages, the production of a \"sticky\" and \"gummy\" aggregate, that contained the yeast biomass produced and an extra-cellular \"capsule\", presumably composed of polysaccharides. It was indeed difficult to separate the biomass, and the whole (viz. biomass and polysaccharide) was isolated after decantation performed by anhydrous acetone (Figure 2). It was also difficult to perform kinetics, and only lactose evolution was followed daily. When lactose was consumed, the \"sticky\" aggregate was recovered, dry weight determi  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Strain**} & **Time** & **S\({}_{\text{cons}}\)** & **X** & **L** & **Y\({}_{\text{X/S}}\)** & **Y\({}_{\text{L/S}}\)** & **K\({}_{\text{L/X}}\)** & **P\({}_{\text{L}}\)** & **FAN\({}_{\text{cons}}\)** & **Protein\({}_{\text{cons}}\)** \\  & **(h)** & **(g/L)** & **(g/L)** & **(g/L)** & **(g/g)** & **(g/g)** & **(g/L/h)** & **(mg/L)** & **(g/L)** \\ \hline _C. curvatus_ ATCC 20509 & 74 & 59.0 \(\pm\) 0.8 & 22.4 \(\pm\) 1.2 & 3.4 \(\pm\) 0.2 & 0.38 & 0.06 & 0.15 & 0.045 & 31.6 \(\pm\) 3.3 & 0.29 \(\pm\) 0.08 \\ \hline _C. curvatus_ NRRL Y-1511 & 218 & 59.0 \(\pm\) 2.0 & 20.6 \(\pm\) 1.1 & 3.2 \(\pm\) 0.1 & 0.35 & 0.05 & 0.16 & 0.015 & 36.0 \(\pm\) 2.8 & 0.47 \(\pm\) 0.10 \\ \hline _D. hansenii_ ACA-DC 5079 & 170 & 18.1 \(\pm\) 1.9 & 8.3 \(\pm\) 0.6 & 1.2 \(\pm\) 0.2 & 0.40 & 0.02 & 0.15 & 0.007 & 41.1 \(\pm\) 4.5 & 0.56 \(\pm\) 0.08 \\ \hline _P. laurentii_ NRRL Y-2536 & 119 & 58.0 \(\pm\) 2.2 & 22.0 \(\pm\) 1.5 * & 1.2 \(\pm\) 0.3 & 0.38 & 0.02 & 0.06 & 0.010 & 32.1 \(\pm\) 4.0 & 0.13 \(\pm\) 0.05 \\ \hline _P. laurentii_ NRRL YB-3594 & 101 & 55.7 \(\pm\) 2.3 & 14.7 \(\pm\) 1.4 & 1.0 \(\pm\) 0.2 & 0.26 & 0.02 & 0.07 & 0.010 & 33.3 \(\pm\) 2.9 & 0.09 \(\pm\) 0.02 \\ \hline \hline \end{tabular}
*: Dry weight of both cells and EPS.  
\end{table}
Table 4: Quantitative data originated by kinetics of five microorganisms, cultivated in the complex substrate, treated second cheese whey, with initial lactose (S0) c. 60 g/L. Culture conditions as in Section 2; standard error for most experimental points was \(\leq\)17%.  
nation (comprising both the microbial mass and the exopolysaccharides) was performed, and the whole aggregate was subjected to hydrolysis and quantification of polysaccharides on glucose equivalents. Indeed, in both trials (semi-defined lactose-based medium and second CW), total polysaccharides (exoploysaccharides and potentially intra-cellular polysaccharides) were quantified resulting in a quantity of 40-45% \(w/w\) on dry aggregate basis. Analysis of individual sugars, comprising these polysaccharides, revealed that the majority of these polysaccharides was composed of glucose (75-80% \(w/w\) of total polysaccharides) followed by galactose/mannose mixture (25-20% \(w/w\)), providing evidence that the extra-cellular (and potentially intra-cellular to some extent) polysaccharides were mainly composed of glycans and to lesser extent mannans and galactans. Further analysis and study on this point is currently performed by our research team.