Optimizing tomato waste hydrolysate for enhanced fucoxanthin biosynthesis in mixotrophic cultivation of Isochrysis galbana.

Vegetable waste, rich in bioactive compounds, offers a promising resource for producing value-added products. This study explored the use of tomato waste, containing glucose (40 mg/g), lycopene (95.12 μg/g), and β-carotene (24.31 μg/g), for cultivating fucoxanthin-rich Isochrysis galbana. Water-soluble lycopene (2.0 μg/mL) and β-carotene (0.4 μg/mL) effectively upregulated key carotenoid synthesis genes and boosted cell growth and fucoxanthin production (3.64 and 3.60 pg/cell, respectively) within 10 days in a mixotrophic culture. Optimized tomato waste hydrolysate achieved a high cell density of 1.21 × 10 cells/mL, 2.13 g/L biomass, and 21.02 mg/g fucoxanthin. This study highlights the potential of combining tomato waste with microalgae for a novel and innovative approach towards waste management and resource utilization.