Maximizing high-value biomass in Scenedesmus and Chlorella: Exploring light-driven macromolecular storage for nutraceutical and feed applications

The stringent safety requirements for using microalgal biomass in the pharmaceutical, food, and feed industries demand increased scientific research to identify optimal cultivation conditions under axenic environments. To achieve high biomass yields and macromolecular productivity, various cultivation parameters must be systematically evaluated. In particular, the strain-specific responses to these conditions underscore the importance of understanding how inorganic carbon supply and light irradiation influence biomass proliferation and macromolecular accumulation. To gain deeper insight into microalgae productivity, Scenedesmus sp. and Chlorella sp. were cultivated under axenic condition with a 2 % CO₂ supply. The effects of different light wavelengths (red, green and blue) and light intensities (ranging from 80 μE to 200 μE) were investigated. The highest biomass production for Scenedesmus sp. was observed under red, green, and blue light at an intensity of 200 μE, yielding 0.78 ± 0.12 gL^-1, 0.94 ± 0.07 g L⁻¹, and 1.00 ± 0.10 g L⁻¹, respectively. Red, green, and blue light at 150 μE intensity increased lipid storage to 25.32 ± 1.50 %, 39.36 ± 1.81 %, and 33.91 ± 19.87 %, respectively. In contrast, the biomass of Chlorella remained stable under 100 μE of red, green, and blue light, producing 0.65 ± 0.04 g L⁻¹, 0.66 ± 0.09 g L⁻¹, and 0.66 ± 0.07 g L⁻¹, respectively. Increasing light intensity did not significantly affect lipid storage, which remained at 6.87 %. Protein content was consistent in both microalgae strains across all experimental conditions, exceeding 15 %. Lipid characterization revealed a high concentration of oleic, palmitic, stearic, and vaccenic acids, highlighting the potential for integrating these microalgae strains into the pharmaceutical, nutraceutical and feed industries.