β -Glucosidase immobilisation on synthetic superparamagnetic magnetite nanoparticles and their application in saccharification of wheat straw and Eucalyptus globulus pulps.

β-Glucosidase fromTrichoderma reeseiwas immobilised on synthetic superparamagnetic magnetite (Fe3O4) 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 globuluspretreated by hydrothermolysis andE. globuluspretreated by hydrothermolysis followed by alkaline extraction. The hydrolysis yields for each pretreated material, using immobilisedβ-glucosidase (I-βG) 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 (I-βG) was magnetically recovered and successfully reused twice. The differences in the hydrolysis yields were not significant (p > 0.05) in the case of steam-exploded wheat straw andE. globuluspretreated by hydrothermolysis followed by alkaline extraction. The immobilisation of enzymes provides an opportunity to reduce the costs of enzymes in the bioethanol production process. [ABSTRACT FROM AUTHOR]