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Aqueous enzymatic extraction of oil and protein from microalgae: Enzyme screening and assay optimization

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2015 ASABE Annual International Meeting  152190194.(doi:10.13031/aim.20152190194)
Authors:   Chelsea Keiana Dixon, Laura Soto Sierra, Lisa R Wilken
Keywords:   Algae, enzyme, biomass, oil, protein, extraction

Abstract. Economic and life cycle assessment studies of microalgae as a biofuel feedstock have shown that inefficient oil extraction and recovery limit the commercialization of microalgal-derived biofuels. Current extraction methods are either disadvantageous due to the costs associated with the energy-intensive drying processes and mechanical pressing or are environmentally unfriendly due to the use of solvents. Furthermore, other valuable compounds, such as proteins, may be degraded during extraction. The use of aqueous enzymatic extraction (AEE), a non-solvent and environmentally friendly oil and protein recovery method, provides an opportunity to design an integrated process for fractionation to reduce costs of bioenergy production. A study was conducted to evaluate the feasibility of utilizing AEE for oil and protein recovery on the freshwater microalgae, Chlamydomonas reinhardtii after 48 h of oil induction via nitrogen deficient growth conditions. In order to lyse the cells, concentrated biomass was treated with a combination of proteases and a glycoside hydrolase. Cell degradation was visualized using a non-ionic detergent and nucleic acid stain and observed with light and fluorescence microscopy. Cell wall degradation was evident after one hour incubation and was dependent of dosage and treatment conditions, such as pH, temperature, and degree of mixing. Results indicate that enzymes can successfully degrade the cell wall and facilitate native protein and oil extraction from microalgae, providing an alternative to traditional methods of protein and oil extraction.

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