## 3 Results and Discussion
### Fermentation Kinetics
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & & \(\mu\) & **Residual** & **Residual** & **Ethanol** & **Y\({}_{PJS}\)** \\  & & (**h\({}^{-1}\))** & **Fructose (g/L)** & **Glucose (g/L)** & **Content (g/L)** & **(g/g)** \\ \hline \multirow{3}{*}{Monoculture} & Sc & 0.59 \(\pm\) 0.14 a & 0.00 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 b & 35.70 \(\pm\) 0.67 b & 0.357 \(\pm\) 0.007 b \\  & Td & 0.34 \(\pm\) 0.05 a & 0.00 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 b & 35.77 \(\pm\) 0.58 b & 0.358 \(\pm\) 0.006 b \\  & Zb & 0.26 \(\pm\) 0.09 a & 6.74 \(\pm\) 0.43 a & 4.19 \(\pm\) 0.36 a & 25.42 \(\pm\) 1.56 c & 0.285 \(\pm\) 0.018 c \\ \hline Co-culture & Sc & 0.59 \(\pm\) 0.01 a & & & & \\ Sc/Td & Td & 0.57 \(\pm\) 0.02 a & 0.00 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 b & 38.98 \(\pm\) 2.30 ab & 0.39 \(\pm\) 0.023 ab \\ \hline Co-culture & Sc & 0.39 \(\pm\) 0.02 a & 0.00 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 b & 39.97 \(\pm\) 0.67 ab & 0.40 \(\pm\) 0.007 ab \\ \hline Co-culture & Td & 0.48 \(\pm\) 0.02 a & 0.00 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 b & 43.03 \(\pm\) 3.43 a & 0.43 \(\pm\) 0.034 a \\ \hline T\(\rightarrow\) & Sc & 0.56 \(\pm\) 0.08 a & & & & \\ Co-culture & Td & 0.58 \(\pm\) 0.03 a & 0.00 \(\pm\) 0.00 b & 0.00 \(\pm\) 0.00 b & 37.42 \(\pm\) 3.7 b & 0.374 \(\pm\) 0.037 b \\ \hline \end{tabular}  
* The data are average of triplicates \(\pm\) standard deviation. Different letters indicate significant differences (\(p<0.05\)) among values in the same column. Sc: _S. cerevisiae_, Td: _T. delbrueckii_; Zb: _Z. bailii_. _Y\({}_{PJS}\): yield of ethanol produced relative to the sugars consumed.  
\end{table} 
Table 1: Fermentation parameters of mono- and co-cultures in YPDA medium. Figure 2: Growth kinetics of co-cultures in YPDA medium. Viable cells of _S. cerevisiae_ (\(\bullet\)) and _T. delbrueckii_ (\(\square\)) during the Sc/Td co-culture (**A**). Viable cells of _S. cerevisiae_ (\(\bullet\)) and _Z. bailii_ (\(\triangle\)) during the Sc/Zb co-culture (**B**). Viable cells of _T. delbrueckii_ (\(\blacksquare\)) and _Z. bailii_ (\(\triangle\)) during the Td/Zb co-culture (**C**). Viable cells of _S. cerevisiae_ (\(\bullet\)), _T. delbrueckii_ (\(\blacksquare\)), and _Z. bailii_ (\(\triangle\)) during the ternary co-culture (**D**). The data is shown as an average of three fermentations. Vertical bars represent standard deviations. This table also shows that the _T. delbrueckii_ and _S. cerevisiae_ monocultures produced similar amounts of ethanol, and the _Z. bailii_ monoculture produced the lowest amount. Conversely, the Td/Zb co-culture produced more ethanol among all the fermentations. Moreover, it is noticeable that co-cultures showed higher ethanol production than the monocultures. Similar observations can be made regarding the _Y\({}_{P/S}\)_ values; _S. cerevisiae_ and _T. delbrueckii_ monocultures had identical yields, while all co-cultures had higher yields than monocultures. Altogether, these results show that, in the nutritionally rich YPD medium, _S. cerevisiae_ causes a slight inhibition of _T. delbrueckii_, which manifests itself mainly in a slight loss of viability after concluding the exponential growth phase. However, _Z. bailii_ shows no signs of being inhibited by _S. cerevisiae_ in this medium. The growth kinetics of the co-cultures developed in the M2 medium are shown in Figure 3. As in Figure 2, the graphs in Figure 3 present the biomass production expressed in logarithmic growth cycles. All graphs in this figure show less abundant growth than in the YPD medium, but this can be explained by the fact that the M2 medium is nutritionally limited compared with the YPD medium. Figure 3A shows that _S. cerevisiae_ and _T. delbrueckii_ grew well during the first nine hours of incubation. Subsequently, a marked loss of viability of _T. delbrueckii_ was evident. On the other hand, the Sc/Zb co-culture in the M2 medium (Figure 3B) was carried out in a similar way to that in the YPD medium. The two yeasts developed well, reaching the stationary phase after nine hours of incubation. Figure 3C shows that _Z.