(316c) Next Generation Solution to Current Energy Problems: Algae to Biodiesel. A Kinetic Metabolic Model

The sustainable production of energy from renewable sources to a degree comparable with the world consumption of petroleum stands as one of the greatest challenges of the 21st century. Algae-derived biofuels will inevitably play a major role in this challenge. Algae-derived biofuel is carbon-neutral as algae are net consumers of CO2, can be produced in non-arable land with much higher yields per area than traditional energy crops and the end product can be distributed through the existing infrastructure for fossil fuels. In our work we created a kinetic metabolic model encompassing 14 pathways for Chlamydomonas reinhardtii, 239 reactions and 183 compounds. A total of 347 enzymatic kinetic constants (Km) as well as 227 turnover numbers (kcat) were determined by using the BRENDA database for enzyme properties. The values for each constant were obtained from multiple organisms and ranged between 0.00052 to 76.9 for Km and between 0.05 to 17179 for Kcat. The model successfully predicts a number of previously published observations of algae metabolism, including the up regulation of Acetyl-Coa Carboxylase which was first documented in the US Aquatic Species Program. Gene expression was modulated by setting the corresponding enzyme concentration to a set of arbitrary values. The effect of up or down-regulation can be analyzed by, respectively, increasing or decreasing this parameter for the enzyme of interest. Our results have shown that UP regulating three individual enzymes in the Glycerolipid metabolism pathway while providing the cell with additional Acetyl-Coa production originates an increase of 48% in the production of tryacylglycerols (TAGS) when compared with the standard case (TAGS are an important molecule that can readily be derived into biodiesel product).