Authors: R. Valenzuela, J.F. Castro, M.C. Parra, J. Baeza, J. Free
Affilation: Biotechnology Center, University of Concepcion, Chile
Pages: 665 - 668
Keywords: magnetite nanoparticles, superparamagnetism, Beta-glucosidase, immobilization, saccharification
Beta-glucosidase from T. reesei was successfully immobilized on synthetic superparamagnetic magnetite (Fe3O4) nanoparticles with a mean diameter of 10 nm, silanized and amino-functionalized with 3-aminopropyltriethoxysilane (3-APTS). When silanized and coated the saturation magnetization decreased from 72 emu g-1 to 55.9 emu g-1 without losing their superparamagnetic features. The concentration of enzyme immobilized on 1.0 g of silanized magnetite and funtionalized with glutaraldehyde was 0.10 g L-1; the activity retention after immobilization was 98% and the enzyme was stable for at least 45 days. The immobilized beta-glucosidase was used to supplement cellulase in the enzymatic hydrolysis of three substrates: wheat straw pretreated by steam explosion (WS-SE), E. globulus pretreated by hydrothermolysis (EG-H) and pulp from hydrothermolysis followed by alkaline extraction (EG-HA). The hydrolysis yields for every pretreated material, using immobilized beta-glucosidase and free cellulase, were 76.1%, 83.6% and 75.6%, respectively, obtaining higher hydrolysis yields compared to those obtained only with cellulase. These yields were 10% lower than the yields reached with cellulase supplemented with free beta-glucosidase. The immobilized beta-glucosidase was magnetically recovered and reused twice. The differences in the hydrolysis yields were not significant (p>0.05) for WS-SE and EG-HA.