Cross-Linking with Polyethylenimine Confers Better Functional Characteristics to an Immobilized β-glucosidase from Exiguobacterium antarcticum B7

• Main Authors: Ricardo Rodrigues de Melo, Robson Carlos Alnoch, Amanda Silva de Sousa, Hélia Harumi Sato, Roberto Ruller, Cesar Mateo
• Format: Article
• Language: English
• Published: MDPI AG 2019-03-01
• Series: Catalysts
• Subjects: β-glucosidase immobilization; tetrameric enzyme; glutaraldehyde; polyethylenimine; pH-stability; cellobiose hydrolysis
• Online Access: http://www.mdpi.com/2073-4344/9/3/223

β-glucosidases are ubiquitous, well-characterized and biologically important enzymes with considerable uses in industrial sectors. Here, a tetrameric β-glucosidase from Exiguobacterium antarcticum B7 (EaBglA) was immobilized on different activated agarose supports followed by post-immobilization with poly-functional macromolecules. The best result was obtained by the immobilization of EaBglA on metal glutaraldehyde-activated agarose support following cross-linking with polyethylenimine. Interestingly, the immobilized EaBglA was 46-fold more stable than its free form and showed optimum pH in the acidic region, with high catalytic activity in the pH range from 3 to 9, while the free EaBglA showed catalytic activity in a narrow pH range (>80% at pH 6.0–8.0) and optimum pH at 7.0. EaBglA had the optimum temperature changed from 30 °C to 50 °C with the immobilization step. The immobilized EaBglA showed an expressive adaptation to pH and it was tolerant to ethanol and glucose, indicating suitable properties involving the saccharification process. Even after 9 cycles of reuse, the immobilized β-glucosidase retained about 100% of its initial activity, demonstrating great operational stability. Hence, the current study describes an efficient strategy to increase the functional characteristics of a tetrameric β-glucosidase for future use in the bioethanol production.