Impact of blue and red light on lipid accumulation in <italic>Chlorella vulgaris</italic> and <italic>Scenedesmus acutus</italic>.

Microalgae can synthesize lipids under controlled settings, making them a viable option as biofuel feedstocks. However, optimizing culture parameters, such as light quality, to maximize lipid yields and achieve commercial viability remains challenging. This study examined the effects of blue and red light on the fatty acid profiles and lipid synthesis in two species with high biotechnological potential for biofuel production: <italic>Chlorella vulgaris</italic> and <italic>Scenedesmus acutus</italic>. When grown under blue, red, and white light, these microalgae exhibited unique metabolic responses in terms of biomass increase, lipid content, and fatty acid composition. The expression levels of genes associated with lipid biosynthesis, including glycerol-3-phosphate acyltransferase (GPAT), β-ketoacyl-ACP synthase (KAS), Biotin carboxyl carrier protein-related gene (BCR), Stearoyl-ACP desaturase (SAD), 3-ketoacyl-ACP reductase (KAR), and Beta-carboxyltransferase 1 (BCX1) were analyzed. Blue light significantly increased lipid accumulation in both species, which was correlated with the overexpression of the GPAT and KAS genes. The generation of high-quality biofuel requires polyunsaturated and monounsaturated fatty acids, especially oleic acid (C18:1) and palmitic acid (C16:0), which increased significantly after genetic activation. The increase in oleic acid levels under blue light in <italic>C. vulgaris</italic>, along with the simultaneous increase in oleic and linoleic acids (C18:2) in <italic>S. acutus</italic>, demonstrates these metabolic adaptations by the microalgae to optimize lipid synthesis under different light conditions. This study examines how blue and red light affects the growth, lipid accumulation, and gene expression of biofuel-potential microalgae <italic>C. vulgaris and S. acutus</italic>. We want to optimize light quality for microalgae biofuel precursor generation by evaluating photobiological reactions under regulated light settings. Previously, light quality has been shown to affect photosynthetic efficiency and metabolic pathways, but this study examines gene-level responses to lipid production under blue and red light. The findings show how tailored light conditions can improve lipid biosynthesis gene expression, which directly affects biodiesel fatty acid profiles. [ABSTRACT FROM AUTHOR]