Effects of irradiance of red and blue:red LEDs on Scenedesmus obliquus M2-1 optimization of biomass and high added-value compounds

Abstract

Microalgae have shown a great potential as a source of bioactive compounds, such lipidic compounds as fatty acids and carotenoids, with recognized benefit for human health. Their synthesis is directly affected by culturing conditions, but, as photosynthetic organisms, microalgae are greatly influenced by light, particularly light quality and irradiance, responsible for growth regulation and activation of biochemical pathways. Therefore, the aim of this work was to maximize biomass and high added-value compound productivity by Scenedesmus obliquus M2-1, using different light irradiances of two previously selected light sources for the production of antioxidant compounds: monochromatic red light (R) and a mixture of 40% of blue and 60% of red light (BR). Four irradiances (50, 100, 150, and 200 μmolphotons m−2 s−1) were accordingly evaluated for both light sources, upon productivity of biomass, fatty acids, carotenoids, and total antioxidant compounds. Changes in light quality and irradiance influenced these aforementioned productivities. Optimal condition for biomass productivity was 150 μmolphotons m−2 s−1, regardless light quality, for both sources. On the other hand, when the production targets carotenoids, polyunsaturated fatty acids, and/or total antioxidant capacity, the optimal condition was found to be at 200 μmolphotons m−2 s−1 under BR light.