Novel insight of carotenoid and lipid biosynthesis and their roles in storage carbon metabolism in Chlamydomonas reinhardtii.

Revenues of carotenoid and lipid biosynthesis under excess light and nitrogen starvation were firstly analyzed for the increased biomass value through carbon metabolism analysis. The results suggested excess light and nitrogen starvation resulted in carbon partitioning among protein, starch, lipid and carotenoid. Nitrogen starvation promoted more cellular lipid content than excess light, while excess light promoted carotenoid and polyunsaturated fatty acid accumulation. In the molecular level, the stresses redirected carbon skeletons into the central metabolite of pyruvate and oriented into starch and lipid as the primary and secondary carbon storage, respectively. Economic estimation revealed nitrogen starvation potentially increased 14.76 × 10-6 and 72.11 × 10-6 $/g revenues of biofuel production at per batch and cell weight scales, respectively. Excess light could increase 63.90 × 10-6 and 19.21 × 10-6 $/g at per cell weight scale of lipid and carotenoid, respectively. In combination with metabolism analysis, conversion procedure of process-compatible products was divided into four phases.