Enzyme-assisted solvent extraction method for total lipid analysis of algal biomass

Abstract: Traditional solvent extraction methods, Folch et al. (1957) and Bligh and Dyer (1959), have been widely used for lipid extraction from fish and other tissues. Challenges can arise when extracting lipids from algae and other micro-organisms due to their complex cell walls and membranes of various compositions. The standard methods do not always efficiently extract lipids from such diverse cells, which results in an incomplete understanding of their lipid profiles. With increasing commercial interest in algal oil, there is a need for a method that extracts a complete lipid profile. Chemical hydrolysis has been attempted by many researchers for the purpose of achieving complete breakdown of cell structures bound to lipids; however, it results in the loss of critical information with regards to lipid class.

In our research, an efficient, enzyme-assisted lipid extraction method is introduced. Specifically, a proteolytic hydrolysis was preformed directly on the fermentation broth of different algal strains. This was followed by a solvent extraction combined with polytron blending. Centrifugation was preformed to separate the two phases and the organic layer was extracted. The solvent extraction was repeated on the biomass/aqueous phase. The two extracts were combined, and the solvent evaporated. The lipid extract was analyzed by GC-FID to get a total recovery in FAMEs mg/g. Lipid recovery was calculated by referring to the total lipid content achieved with the one-step acid hydrolysis/transesterification method on the dried algal biomass. Recoveries of different algal strains were between 90.6 - 99.9%, which represented an increase in percent recovery of 10 - 50% compared to Folch and B&D methods with the same strains.