Exploration of Microalgae Biorefinery by Optimizing Sequential Extraction of Major Metabolites from Scenedesmus obliquus

The effects of six different sequential extractions of proteins, lipids, and carbohydrates on their yields and subsequent biomass recoveries was investigated. The maximum yields of lipids, proteins, and carbohydrates were 26.50 +/- 1.32%, 28.14 +/- 1.97%, and 16.40 +/- 0.43%, respectively, in primary extraction of biomass. Compared to the primary extractions, lipid yields were significantly lowered by 20-22% in secondary extractions. The maximum loss of proteins in secondary (post lipid extraction) and tertiary extractions was 34.79% and 56%, respectively. The most significant loss (3844.5%) in carbohydrates was recorded after tertiary extractions. Among all of the extraction sequences, the sequence of proteins lipids carbohydrates extracted algae (PLCEA) showed optimum recovery of individual metabolite. For this extraction sequence, the yields of proteins, lipids, and carbohydrates were found to be 28.14%, 22%, and 10.17%, respectively. It was also characterized by the highest residual biomass available for second (80%) and third (61%) steps of extraction. Finally, the cumulative yields of these metabolites were converted into net value gains. The extraction sequence PLCEA could result in 66.5% net value gain overcoming the cost of biomass generation.