## 3 Results and Discussion
### Validation of the iRV781 Model
#### 3.2.2 Growth Parameters in Batch Culture  
Experimental data obtained elsewhere [65] from synthetic minimal media batch cultures with glucose as carbon source were used to validate the model quantitatively. The model was simulated in environmental conditions that simulate the medium used in [PERSON] et al., 2011. The glucose uptake flux was fixed to qGlucose = 7.56 mmol g\({}^{-1}\) dry weight h\({}^{-1}\) as per such work, and the remaining nutrients flux were left unconstrained, as the model in this condition is glucose-limited. Once again, the model proved to be robust as the experimentally observed growth rate is similar to that predicted by the model (Table 4). Additionally, the formation of glycerol, acetic acid, and ethanol as by-products was not predicted to occur, which is in agreement with the experimental data, except for ethanol, that appears to be produced in trace amounts. _C. albicans_, as a crabtree-negative yeast [66], under aerobic conditions does not produce significant concentrations of ethanol. Nonetheless, the model predicts ethanol production under low-oxygen conditions (qOxygen \(<\) 7.56 mmol g\({}^{-1}\) dry weight h\({}^{-1}\)). _C. albicans_ is unable to grow in anaerobic conditions in minimal media. However, _C. albicans_ colonization is known to spread into anaerobic niches of the gastrointestinal tract or in the inner sections of biofilms where the oxygen availability is scarce or null. [PERSON] et al., 2004 reported a defined anaerobic growth medium for studying _Candida albicans_. In this medium (GPP) oleic acid and nicotinic acid were added as required growth factors for anaerobic growth [67]. Interestingly, _S. cerevisiae_ under anaerbiosis also requires growth factors, such as ergosterol and Tween 80, a source of oleic acid, if growing in a defined medium (SMM), it should be noticed that SMM medium also contains nicotinic acid in its composition despite not being a required growth factor in anaerobic conditions [68]. Cultivation was simulated in the absence of oxygen in GPP medium and GPP medium supplemented with oleic acid and nicotinic acid, to assess if this model can predict growth in anaerobic conditions. Our model predicts the growth only in media supplemented with specific anaerobic growth factors. For the simulation, the glucose uptake flux was set to qGlucose = 6.58 mmol g\({}^{-1}\) dry weight h\({}^{-1}\), to compare the growth parameters with the reported values for _S. cerevisiae_. Indeed, for the same anaerobic conditions, the specific growth rate of the model and the ethanol production are similar to data reported for _S. cerevisiae_[68], though the model does not predict the production of glycerol in such conditions (Table 5). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Specific Growth** & \multicolumn{4}{c}{**q (mmol g\({}^{-1}\) dry weight h\({}^{-1}\))**} \\ \cline{3-6}  & **Rate (h\({}^{-1}\))** & **Glucose** & **Ethanol** & **Glycerol** & **Acctic Acid** \\ \hline In silico C. _ablicans_ & 0.53 & 7.56 & 0 & 0 & 0 \\ In vivo _C. albicans_[60] & 0.51 & 7.56 & 0.38 & 0 & 0 \\ In vivo _S. cerevisiae_[60] & 0.38 & 13.26 & 21.87 & 1.98 & \textless{}0.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Growth parameters of iRV781 and comparison with in vivo values for _C. albicans_ and _S. cerevisiae_. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Condition**} & **Specific Growth** & \multicolumn{3}{c}{**q (mmol g\({}^{-1}\) dry weight h\({}^{-1}\))**} \\ \cline{2-5}  & **Rate (h\({}^{-1}\))** & **Glucose** & **Ethanol** & **Glycerol** \\ \hline In silico GPP & 0 & 0 & 0 & 0 \\ In silico GPPsup. & 0.08 & 6.58 & 10.80 & 0 \\ In silico DMM & 0 & 0 & 0 & 0 \\ In silico DMMsup. & 0.08 & 6.58 & 10.80 & 0 \\ _S. cerevisiae_ DMM [68] & 0.10 & 6.58 & 9.47 & 1.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Anaerobic growth assessment of iRV781 model in defined media with or without anaerobic supplements. DMM [68] (defined minimal medium); DMMsup.