Partial enzymatic cell wall disruption of Oocystis sp. for simultaneous cultivation and extraction

Abstract

A green extraction process is proposed to reduce energy and petroleum solvent’s consumption while maintaining environmental safety and quality that allows multiple product recovery. The goal of the study was to generate a highly permeable cell, through the use of crude fungal enzymes, that could permit simultaneous cultivation and extraction. A novel pretreatment method is developed which combines partial enzymatic digestion of cell walls of microalgae, while maintaining their viability, thus enabling further product recovery from the same biomass and has not been reported in literature yet. Partial digestion of the cell wall was accomplished through regulation of the contact time of crude enzymes with the microalgal cells leading to a highly permeable cell that is viable and actively growing. Experimentally this was achieved through controlling the time of incubation of microalgal cells with the crude enzymes. The effects of enzymatic treatment using crude fungal enzymes from Trichoderma reesei (cellulase 10.98 ± 0.17 U/ml and amylase 20.28 ± 0.13 U/ml) were investigated on the structural properties of marine microalga Oocystis sp. Results showed over 2-fold increase in protein efflux; 41% increase in released sugars and 24% decrease in cell count after 1 h of enzyme treatment at 33% (v/v) enzyme concentration. Controlled hydrolysis of algal cells could be achieved through optimizing the contact time (1 h) of enzymes with microalgal cells which retained their viability. This was validated through FTIR, SEM, XRD and Flow Cytometric analysis. The carotenoid content increased by approximately 9% and lipid content rose by nearly 6.2%.