Immobilization of β-glucosidase on a magnetic nanoparticle improves thermostability: application in cellobiose hydrolysis.

The objective of the present work was to develop a thermostable beta-glucosidase through immobilization on a nanoscale carrier for potential application in biofuel production. beta-Glucosidase (BGL) from Aspergillus niger was immobilized to functionalized magnetic nanoparticles by covalent binding. Immobilized nanoparticles showed 93% immobilization binding. Immobilized and free BGL were characterized using Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Free and immobilized enzyme exhibited different pH-optima at pH 4.0 and 6.0, respectively, but had the same temperature optima at 60 degrees C. Michaelis constant (K-M) was 3.5 and 4.3 mM for free and immobilized BGL. Thermal stability of the immobilized enzyme was enhanced at 70 degrees C. The immobilized nanoparticleenzyme conjugate retained more than 50% enzyme activity up to the 16th cycle. Maximum glucose synthesis from cellobiose hydrolysis by immobilized BGL was achieved at 16 h. (C) 2013 Elsevier Ltd. All rights reserved.