Studies on the formation and localization of primary and secondary carotenoids in the green alga Botryococcus braunii, including the regreening process

Abstract The total carotenoid content during growth of the green alga Botryococcus braunii race B was related to culture volume, biomass dry weight, lipid-depleted biomass and N-content of lipid-depleted biomass. The relative abundance of individual carotenoids in (i) total colonies, (ii) cells and (iii) the external cell wall matrix interconnecting the cells, was determined in the exponential, intermediate and stationary phase of growth. The carotenoid synthesis during the regreening process revealed that the synthesis of ketocarotenoids is correlated with nitrogen deficiency. It is inferred that echinenone and canthaxanthin are synthesized by the cells in the intermediate and stationary phase of growth and transferred to the matrix. A biosynthetic scheme is proposed, demonstrating the effect of nitrogen deficiency.