چكيده به لاتين
Microalgae can grow phototrophically, heterotrophically and mixotrophically due to their metabolic flexibility. As detailed understanding of their metabolism plays a major role in optimizing the production efficiency of microalgal products, we attempted to computationally investigate their intracellular metabolic flux distribution under various metabolisms. FBA (Flux Balance Analysis), a constraint-based modelling method, was used to simulate the growth of microalgae using three metabolisms: heterotrophic, photoautotrophic and mixotrophic. Modelling was performed based on a genomic scale metabolic network consisting of 843 genes, 1770 metabolites and 2294 reactions distributed among five intracellular compartments and the extracellular space. Growth rate for mixotrophy (0.041 mmol/gDWh) was more than that for heterotrophy (0.0168 mmol/gDWh), photoautotrophy (0.0247 mmol/gDWh) and photoheterotrophy (0.0379 mmol /gDWh). To minimize the sum of intracellular fluxes, pFBA (Parsimonious Enzyme Usage FBA) was used and the flux distribution was investigated and compared with that of FBA. Since microalgae naturally grow under circadian cycle, algal growth and production of storage materials (starch and lipid) were firstly investigated under light condition and subsequently consumption of storage materials under dark condition was studied. Under dark conditions, starch was a better source of energy than lipid. The growth rate on starch under dark condition was 0.0037 mmol/gDWh, which was 1.6 times greater than the growth rate on lipid (0.0022 mmol/gDWh).
