The concurrent production of lipid and lutein in Chlorella vulgaris triggered by light coupling nitrogen tactics

Co-production of multiple products was praised as potential scheme in expanding low-cost applications of microalgal biomass. This work explored concurrent accumulation of lipid/lutein in Chlorella vulgaris triggered by high-light (HL), moderate-light (ML) or low-light (LL) coupling nitrogen-depletion (ND), nitrogen-limitation (NL), and nitrogen-repletion (NR) tactics. Amongst all combination cases, ML-NR achieved superior growth with 1.08 g/L/d biomass and 0.72 d-1 specific growth rate, HL-NR induced the highest lutein (5.39 mg/g) while LL-ND was inclined to lipid biosynthesis (51.8%). Only HL-NL maximized concurrent accumulation of lipid/lutein with optimal productivities were 0.32 g/L/d and 4.74 mg/L/d, representing 1.06- to 2.47- and 1.02- to 15.55-fold more than other coupling tactics. HL-NL also boosted saturated (C16:0 and C18:0) and monounsaturated fatty acid (C18:1) which were commendable for high-quality biodiesel-making. Further, HL-NL manipulation caused eclectic expressions of crucial genes responsible for lutein (e.g., psy, pds, and lcye) and lipid (e.g., me, acc, kas, sad, and fad) biosynthesis in comparison with HL-NR and LL-ND consequently balanced metabolic flow into lutein/lipid pathway to promote maximal co-production of lipid/lutein. The findings were expected to be available in other algae system for co-production of multiple compounds and guiding metabolic modifications to further improve biosynthesis of alga-based fine chemicals. •Light coupling nitrogen was developed for concurrent accumulation of lipid/lutein.•HL-NL maximized concurrent accumulation of lipid/lutein in Chlorella vulgaris.•HL-NL boosted proportions of commendable saturated and monounsaturated fatty acids.•HL-NL compromised the levels of crucial genes in lipid/lutein pathway.•HL-NL balanced carbon flow into lutein/lipid to maximize coproduction of lipid/lutein.