## 3 Results and Discussion
### Validation of the iRV781 Model  
#### Carbon and Nitrogen Source Utilization  
Based on the literature, phenotypic growth data were collected from different sources. Data related to _C. albicans_ strains, other than the reference SC5314 strain, was also considered in the analysis to increase the number of carbon and nitrogen sources tested. In a first simulation, this model correctly predicted the usability of 92% of the 39 tested carbon sources. According to data available on Royal Netherlands Academy of Arts and Sciences \begin{table}
\begin{tabular}{c c c c} \hline
**Metabolite** & **g/gDCW** & **Metabolite** & **g/gDCW** \\ \hline \multicolumn{4}{c}{**Protein components**} & **Lipids** \\ L-Valine & 0.02001 & Lanosterol & 0.00166 \\ L-Tyrosine & 0.02153 & Squalene & 0.00088 \\ L-Tryptophan & 0.00671 & Ergosterol & 0.00247 \\ L-Threonine & 0.02311 & Phosphatidylserine & 0.00299 \\ L-Serine & 0.02908 & Phosphatidylinositol & 0.00417 \\ L-Proline & 0.01616 & Phosphatidylcholine & 0.00681 \\ L-Phenylalanine & 0.02407 & Phosphatidylethanolamine & 0.00542 \\ L-Methionine & 0.00869 & Cardiolipin & 0.00201 \\ L-Lysine & 0.03535 & Phosphatidic acid & 0.00271 \\ L-Leucine & 0.03874 & Phosphatidylglycerol & 0.00174 \\ L-Isoleucine & 0.02992 & Tetradecanoic acid & 0.00003 \\ L-Histidine & 0.01067 & Hexadecanoic acid & 0.00073 \\ L-Glutamate & 0.03084 & Palmitoleic acid & 0.00022 \\ L-Cysteine & 0.00410 & Octadecanoic acid & 0.00035 \\ L-Aspartate & 0.02508 & Oleic acid & 0.00163 \\ L-Asparagine & 0.02841 & Linoleate & 0.00054 \\ L-Arginine & 0.02203 & Linoleate & 0.00008 \\ L-Alanine & 0.01334 & Triacylglycerglycerol & 0.00573 \\ Glycine & 0.01077 & Monocylglycerol & 0.00620 \\ L-Glutamine & 0.02158 & Diacylglycerol & 0.00087 \\  & & Sterol esters & 0.01177 \\ \hline \multicolumn{4}{c}{**Carbohydrates**} & **Soluble Pool** \\ \cline{2-4} \multicolumn{1}{c}{Chitin} & 0.01368 & **Soluble Pool** \\ \cline{2-4} \multicolumn{1}{c}{Mannan} & 0.14669 & Thiamine & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{\(\beta\) (1.3)-Glucan} & 0.23962 & Ubiquinone-6 & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{**Deoxyribonucleotides**} & NAD+ & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{dTTP} & 0.02072 & FMN & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{dGTP} & 0.01266 & FAD & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{dCTP} & 0.01118 & CoA & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{dATP} & 0.02114 & Biotin & 0.00290 \\ \multicolumn{1}{c}{} & \multicolumn{1}{c}{Pyridoxal phosphate} & 0.00290 \\ \hline \multicolumn{4}{c}{**Ribonucleotides**} & 5-Methyltetrahydrorofolate & 0.00290 \\ \cline{2-4} \multicolumn{1}{c}{UTP} & 0.00603 & \\ \cline{2-4} \multicolumn{1}{c}{GTP} & 0.00714 & \\ \cline{2-4} \multicolumn{1}{c}{CTP} & 0.00561 & \\ \cline{2-4} \multicolumn{1}{c}{ATP} & 0.00714 & \\ \hline \end{tabular}
\end{table} 
Table 2: Biomass Composition used in the model iRV781. More detailed information is found in File S1. (CBS-KNAW) Fungal Biodiversity Centre webpage [60], the _C. albicans CBS562_ strain seems not to be able to use cellobiose or D-ribose as sole carbon sources, contrary to the model's prediction. Therefore, the utilization of cellobiose and D-ribose by _C. albicans_ SC5314 was evaluated experimentally to assess whether the prediction failure could result from a different metabolic capacity exhibited by the reference strain. The results confirmed the model's prediction regarding the utilization of cellobiose and D-ribose (Figure 3), suggesting that the reference _C. albicans_ strain has higher metabolic capabilities, when compared to other strains. The model's prediction failed only for mannitol that, according to the model, cannot be used as sole carbon source by _C. albicans_, contradicting experimental evidence gathered for the _C. albicans_ SC5314 strain [61, 62] (Figure 3). It was not possible to identify the source of this problem in the built model. Nonetheless, the model is able to correctly predict the usability of 97% of the tested substrates.