Two-step cultivation for production of astaxanthin in Chlorella zofingiensis using a patented energy-free rotating floating photobioreactor (RFP).

In the present study, high light and nitrogen starvation with glucose-fed to the culture was found efficient to induce astaxanthin accumulation in Chlorella zofingiensis. Therefore, a two-step cultivation strategy including high biomass yield fermentation and outdoor induction with an energy-free RFP was conducted. During the fermentation, the highest cell density of 98.4gL-1 and astaxanthin yield of 73.3mgL-1 were achieved, which were higher than those so far reported in C. zofingiensis. During the outdoor induction, astaxanthin content was further increased by 1.5-fold leading to the highest astaxanthin productivity of 5.26mgL-1 day-1 under an optimal dilution of 5-fold. Our work thus provided an effective two-step cultivation strategy for production of astaxanthin by C. zofingiensis.