Efficient Fractionation of Lipids in a Multiproduct Microalgal Biorefinery by Polymers and Ionic Liquid-Based Aqueous Two-Phase Systems

Abstract

For a multiproduct microalgal biorefinery, most of the cell components should be extracted and fractionated. This work investigates the fractionation of lipids from other microalgal components (pigments, proteins, carbohydrates) using polymers and IL solutions in aqueous two-phase systems (ATPS). The microalgal lipids poorly migrated to the aqueous phases of ATPS and were recovered (97% of the total fatty acids) in a third phase (interphase) formed between the top and bottom phases. Studies with canola oil and purified phospholipids suggest that the high amount of oil, phospholipids, and other natural emulsifiers present in the microalgae mixed with the high amount of water in the ATPS form an emulsion which is difficult to fractionate. However, a solution of polypropylene glycol 400 (25% w/w) displaced 73% of lipids in an immiscible layer which was easy to recover. When combining this approach with a subsequent ATPS, most of the microalgae biomolecules (lipids, proteins, pigments, carbohydrates) could be fractionated in a three-step mild separation concept.

Optimal Design of Aqueous Two-Phase Systems for Biomolecule Partitioning

“…As most polymers are biodegradable, have low toxicity, and are relatively inexpensive, polymer-based ATPS have been widely studied. Some of them have been successfully used as non-denaturing and benign separation media to recover various biomolecules (e.g., proteins, amino acids, and nucleic acids) with high recovery percentages while preserving their activity. − The recovery is based on the selective partitioning of the target biomolecules between the two aqueous phases . Basically, the partition performance is dependent on the parameters that are related to the system properties.…”

Liquid–Liquid Extraction of Some Biomolecules in the ATPS {Ethyl Lactate (1) + Sodium Potassium Tartrate (2) + Water (3)} at 298.15 K and 0.1 MPa

“…Aqueous two-phase systems (ATPS), or aqueous biphasic systems (ABS), have been gaining relevance in the extraction of biomolecules such as proteins, – vitamins, – and lipids. – These ternary systems are constituted by water-soluble components, which become immiscible by the action of a salting out agent (such as a salt or a polymer), which is preferentially solvated by water. The classical combinations of components for ATPS include {polymer + salt + water}, {polymer + polymer + water}, and {solvent + salt + water}, but the most useful for the extraction of biomolecules is {solvent + organic salt + water} since this alternative allows for an easier separation of biomolecules from the solvents.…”