Optimized production and enrichment of α-linolenic acid by Scenedesmus sp. HSJ296

The essential fatty acid α-linolenic acid is vital for human physiology and health. The green alga Scenedesmus sp. HSJ296 can accumulate large amounts of α-linolenic acid. In this work, we optimized the fermentation of Scenedesmus sp. HSJ296 in a 50-L fermenter , resulting in a biomass productivity of 3.12 ± 0.45 g L −1 d −1 . We then extracted lipids from the biomass by supercritical fluid CO 2 extraction with 95% ethanol as entrainer , achieving a lipid extraction rate as high as 73.47 ± 4.28%. After decolorization and enrichment by lipase hydrolysis , and low-temperature solvent crystallization, the content of unsaturated fatty acids in the lipid fraction from the biomass was enriched up to 92.5 ± 1.2%, with α-linolenic acid accounting for 62.6 ± 0.9%. The saturated fatty acids mainly consist of palmitic acid (C16:0, 3.1 ± 0.1%) and stearic acid (C18:0, 0.9 ± 0.1%). The remaining saturated fatty acid fraction, with relatively higher saturated fatty acid content, can be used as raw material for biodiesel production. Overall, we established an optimized α-linolenic acid production process that provides an important theoretical and technical basis for microalgae-based production of high-value lipids. • A systematic operation procedure for Scenedesmus -based α-linolenic acid production • An optimized cultivation mode for Scenedesmus sp. HSJ296 was established. • An efficient procedure for α-linolenic acid enrichment was established. • A feasible reference for the industrialization of microalgal lipids production • This work helps to promote the development of microalgal edible oil.