Insight into the regulation mechanism of light spectra on astaxanthin biosynthesis in mixotrophic Chromochloris zofingiensis

This study studied the effects of white light (WL), blue light (BL), and yellow-green light (YGL) on astaxanthin production in mixotrophically grown Chromochloris zofingiensis. The biomass yield achieved under BL was higher than that obtained under WL and YGL, respectively. Remarkably, compared with WL and YGL, the RuBisCO activity under BL was reduced, suggesting that the light wavelength could influence the RuBisCO activity. The results showed that BL was more suitable for astaxanthin accumulation than WL and YGL. When C. zofingiensis was grown under BL, the total yields of astaxanthin reached 0.2844 g·L⁻¹ in 12 days, of which the biomass yield was 204.5 g·L⁻¹ and astaxanthin content was 0.139 % of DW. The metabolomic study revealed that the central carbon metabolism and astaxanthin biosynthesis were enhanced, supporting fast cell growth and high astaxanthin contents under BL. Moreover, BL could enhance astaxanthin production by increasing the PSY, LCYb, CHYb, and BKT gene expression. This study provides effective strategies to facilitate astaxanthin production in C. zofingiensis.