In Silico Predictions for Fucoxanthin Production by the Diatom Phaeodactylum Tricornutum.

Diatoms and brown seaweeds are the main producers of fucoxanthin, an oxy-carotenoid with important biological functions related to its antioxidative properties. The diatom Phaeodactylum tricornutum appears in this scenario as a good source for fucoxanthin production. Its whole genome sequence was published in 2008, and some genome-scale metabolic models are currently available. This work intends to make use of the two most recent genome-scale metabolic models published to predict ways to increase fucoxanthin production, using constraint-based modeling and flux balance analysis. One of the models was completed with 31 downstream reactions of the methylerythritol 4-phosphate plastidic (MEP) pathway. Simulations and optimizations were performed regarding inorganic carbon and nitrogen sources in the two models and comparisons were made between them. Biomass growth was predicted to increase in all sources tested, i.e., CO2, HCO3-, NO3- and urea. However, the best results were obtained by combining CO2 plus HCO3- regarding inorganic carbon, and for urea as a nitrogen source, in both models tested. As a result of optimizations for fucoxanthin production, many of the knockout reactions brought on are involved in the metabolism of pyruvate, glutamine/glutamate and nitrogen assimilation.