Maximizing microalgal lutein through light patterning and nutrient shifts in photobioreactors

BACKGROUND: Lutein, a valuable xanthophyll from Chlorella sorokiniana, is vital for ocular and metabolic health. However, lutein degradation under high light or suboptimal nutrient hampers productivity during the growth phase. RESULTS: This study optimized lutein yield via light modulation (4k–14k lux), intermittent high-intensity (patterned) exposure, and nutrient refinement. Light–dark cycling (18:6, 8k lux) improved the lutein to 65.48 mg L⁻¹ and increased biomass to 6.12 g L⁻¹. A patterned 14k lux photobioreactor yielded 69.14 mg L⁻¹ and 7.01 g L⁻¹ biomass. Temperature modulation (35 °C) and urea as a nitrogen source under a one-stage bioprocess further increased lutein to 72.45 and 82.60 mg L⁻¹ and biomass to 6.0–8.0 g L⁻¹. A two-stage process combining 10k lux light and macro- and micronutrient enrichment achieved a maximum lutein yield of 86.40 mg L⁻¹ with 8.31 g L⁻¹ biomass. Compared with the control (62.1 mg L⁻¹ lutein; 6.75 g L⁻¹ biomass), the optimized two-stage strategy enhanced lutein production by ~39.1%, while biomass increased by 23.1%, indicating a proportionally higher pigment-to-biomass productivity ratio. CONCLUSION: From an economic perspective, the integrated strategy in a two-stage process can reduce costs by 28–32% of lutein, owing to improved nutrient utilization, enhanced energy efficiency in light modulation, and shorter cultivation time. The process thus demonstrates a favorable productivity-to-cost ratio, strengthening the economic feasibility of microalgal lutein production. Integrated light–nutrient strategies effectively enhance lutein production while minimizing degradation. This sustainable approach supports SDG 3 (health), SDG 9 (innovation), and SDG 13 (climate action), paving the way for a scalable microalgae lutein bioprocess.