Nutritional and Amino Acid Composition of Scenedesmus sp. Cultivated Under Various Light Intensities

Microalgae like Scenedesmus sp. are promising alternatives for sustainable food and animal feed due to their high protein content and adaptability to different light intensities. Optimal light enhances growth and nutrient accumulation, while excessive light can reduce productivity. This study investigates the effects of different light intensities (100-300 µmol m⁻² s⁻¹) on the growth performance and nutritional composition of Scenedesmus sp., aiming to improve microalgae production efficiency and contribute to commercial standards for sustainable protein sources. Results show that dry biomass concentration (0.975 g L^-1) and cell count (2.96) peaked at a light intensity of 200 μmol m^-2 s^-1 (P < 0.0001), while dry biomass decreased at 300 μmol m⁻² s⁻¹. Scenedesmus sp. grown at 200 and 300 µmol m^-2 s^-1 had higher carbohydrate contents (50.1% and 54%, P < 0.001), while the highest lipid content (42.3%) was observed at 100 µmol m^-2 s^-1. The highest crude protein was recorded at 200 µmol m^-2 s^-1 (15.6%, P < 0.0001). Regarding amino acid composition, leucine was the most abundant essential amino acid (1.20 mg/100 mg dry weight), while glutamic acid was the most abundant non-essential amino acid (1.73 mg/100 mg). For color characteristics, biomass produced at 300 µmol m^-2 s^-1 exhibited a darker color, with the lowest L* value (21.66), and a more yellowish hue compared to 200 µmol m^-2 s^-1. These findings highlight the importance of optimizing light conditions to enhance Scenedesmus sp. productivity for sustainable animal feed applications. This study indicates that the productivity of Scenedesmus sp. could be enhanced for biomass and protein production by maintaining an optimal light regime. By maximizing biomass yield and nutrient composition, this study supports the development of microalgae-based protein sources that can serve as a viable alternative to conventional feed ingredients, contributing to more sustainable and efficient feed production systems.