Difference between revisions of "Team:Tartu TUIT/Model"

As our project idea is to split functions between two yeast strains so as to reduce metabolic burden, it’s only logical to model two different compartments, referred to in the above graph as strainA and strainB. Unfortunately, due to time constraints, we weren’t successful in fully modelling the whole glycolysis and TCA (tricarboxylic acid) cycle pathways, here each illustrated as only one reaction. For this reason, our result may not be as accurate as we’d like it to be. Most of the enzyme kinetic constants were taken from the BRENDA website.

First we simulated a batch mode of cultivation without air supply (Figure 1) and, even though our model does not seems to comply with reality (arginine concentration reaching 0 mol/L), we could infer that: (1) by feeding glutamate (arginine precursor) would not only increase the availability of arginine itself, but also possibly increase the 2-oxoglutarate for the ethylene production; (2) provide a constant air supply as oxygen levels drops over time; and (3) as apparently the glucose and fructose do not reach high concentrations (are readily consumed by strain A) and as Saccharomyces cerevisiae is a Crabtree positive organism, which could hinder ethanol production. Therefore, we decided to base our model on a fed-batch or chemostat bioreactor cultivation, providing constant supplies of glutamate, oxygen, and sucrose (Figure 2).

After doing so, our ethylene production was markedly improved (Figure 2). Connecting this result to our lab work we have concluded that ethylene yield would be increased by using chemostat bioreactor cultivation.