The first draft model based on homology to template models contained gaps due to incorrect annotation in the template models and lacked reactions in parts of metabolism that were unique to P. chrysogenum (Figure 8 ). Therefore, another draft model was generated from KEGG using the RAVEN Toolbox. An E-value <1e-50 was used as cut off in the gene assignment. This model was used for filling gaps in the draft network and for suggesting metabolic pathways that were not included based on the template models. No reactions were included based solely on presence in the KEGG model, and gene assignments were only included after careful manual validation against the NCBI RefSeq database.
Gaps in the draft metabolic network were identified using the gap finding capabilities of the RAVEN Toolbox (Figure 8 ). The initial network was rather disconnected and biomass production from glucose was not possible. Firstly, the software was used to identify which metabolites had to be connected in order to produce biomass. This resulted in the addition of some spontaneous reactions from the template models. The second step was to ensure that as many metabolites as possible could be produced. When non-connected metabolites were identified, the KEGG model was queried for candidate reactions which could connect that metabolite. A targeted literature search was then conducted to find evidence for the presence of such a reaction. In only few cases this resulted in the addition of transport reactions based solely on connectivity issues (<2%, see Figure 5 ). The final step was to use the RAVEN Toolbox to identify reactions that could not carry a flux during growth on any of the available carbon sources. There are, however, sets of reactions that are included in the model even though they cannot currently carry a flux. One such example is the synthesis and loading of tRNA, which is included to allow for possible future extension of the model to cover protein synthesis.
Gaps in the draft metabolic network were identified using the gap finding capabilities of the RAVEN Toolbox (
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