Neochloris oleoabundans biorefinery: Integration of cell disruption and purification steps using aqueous biphasic systems-based in surface-active ionic liquids

Abstract

In this work, an approach to integrate the downstream processing of bioactive compounds present in the microalgae cells by combining the use of tensioactive compounds and aqueous biphasic systems (ABS) is proposed. For this purpose, several aqueous solutions using solvents with and without tensioactive nature were investigated on their capacity to disrupt the microalgae cells as well as to extract the different classes of biomolecules, namely pigments (chlorophylls a and b, and lutein), proteins and carbohydrates. Cationic tensioactive compounds were selected due to their high ability to simultaneously extract the different classes of compounds present in the Neochloris oleoabundans biomass. To fractionate pigments, proteins and carbohydrates extracted from the microalgae, ABS formed by polyethylene glycol (PEG 8000) and sodium polyacrylate (NaPA 8000) were used, with the solvent selected to disrupt the cells acting as electrolyte. This allowed to tune the biomolecule’s partition reaching a selective fractionation. This approach provided the simultaneous extraction of different biomolecules (pigments, protein and carbohydrates) from the cells and, the subsequent origin of two fractions, one rich in proteins (extraction efficiencies of 100%) and carbohydrates (extraction efficiency of 80%) and the second concentrated in pigments (e.g. lutein, extraction efficiency of 98%). The further isolation of the biomolecules from the ABS forming solvents is proposed aiming at the development of an integrated downstream process, including the cell disruption/compounds extraction, the fractionation, and the isolation of the biomolecules.