Reutilization of food industrial waste for lutein production with heterotrophic microalgae Chlorella sorokiniana MB-1-M12

Background: Lutein is a xanthophyll carotenoid commonly found in photosynthetic organisms, such as microalgae and plants. It serves as a photosynthetic accessory pigment and possesses antioxidant properties. Lutein is recognized for its prophylactic use in preventing Age-Related Macular Degeneration (AMD) and is widely employed in health supplements. The demand for lutein is steadily increasing. This study utilized Chlorella sorokiniana MB-1-M12 for heterotrophic growth and lutein production, employing molasses as a model of food industrial waste as an alternative carbon source. Methods: Molasses was hydrolyzed using acids, and the optimal hydrolysis conditions were determined by varying the types and concentrations of the acids. The resulting hydrolysate, which contains reducing sugars, was then recovered and used to support the heterotrophic growth of C. sorokiniana MB-1-M12 for lutein production. Significant Findings: The best efficiency in molasses hydrolysis was achieved using 0.15 M sulfuric acid, resulting in a maximum sugar recovery of 0.721 gs of reducing sugar per gram of molasses. When the molasses hydrolysate reached a sugar concentration of 10 g/L, it yielded a biomass of 2.57 g/L and a lutein content of 2.1 mg/g. These findings indicate that molasses can effectively serve as a substitute for glucose as a carbon source, although it cannot provide all the essential micronutrients required for biomass growth. Consequently, the addition of nutrients in BG-11 medium became necessary. This study successfully demonstrates the upcycling of waste resources, such as molasses, into a high-value product like lutein, all achieved in a cost-effective and resource-efficient manner.