Abstract

?-glucosidase from Trichoderma reesei was immobilized on synthetic superparamagnetic magnetite (Fe 3O 4) nanoparticles with a mean diameter of 10 nm and were used to supplement cellulase in the enzymatic hydrolysis of three substrates: wheat straw pretreated by steam explosion, Eucalyptus globulus pretreated by hydrothermolysis and pulp from hydrothermolysis followed by an alkaline extraction. The hydrolysis yields for each pretreated material, using immobilized ?-glucosidase and free cellulase, were 76.1%, 83.6% and 75.6%, respectively and resulted in an improved hydrolysis yields compared with only cellulase. These yields were at most 10% lower than yields reached with free enzymes. The immobilized ?-glucosidase was magnetically recovered and reused twice. The differences in the hydrolysis yields were not significant (p>0.05) in the case of steam exploded wheat straw and pulp from hydrothermolysis and alkaline extraction. The immobilization of enzymes provides an opportunity to reduce the costs of enzymes in the bioethanol production process.