Magnetically recyclable catalytic nanoparticles grafted with Bacillus subtilis β-glucosidase for efficient cellobiose hydrolysis

Abstract This study reports covalent immobilization of β-glucosidase (BGL) from Bacillus subtilis PS on magnetically recyclable iron nanoparticles for enhancing robustness, facile recovery and reuse of enzyme. Immobilized BGL iron nanoparticles (BGL-INPs) were characterized by various biophysical techniques viz. TEM, DLS, FTIR and CD spectroscopy. The efficiency and yield of immobilization were 89.78 and 84.80%, respectively. After immobilization, optimum pH remained 6.0 whereas optimum temperature upraised to 70 °C whereas apparent Km and Vmax shifted from 0.819 mM to 0.941 mM and 54.46 to 57.67 μmole/min/mg, respectively. Immobilization conferred lower activation energy and improved pH and thermal stabilities. The BGL-INPs retained 85% activity up to 10th cycle of reuse and hydrolyzed more than 90% of cellobiose to glucose within 30 min. Conclusively, improved pH, thermal stability and excellent reusability over free enzyme make BGL-INPs a promising candidate for sustainable bioethanol production and other industrial applications.