Exploring novel ultrafine Eri silk bioscaffold for enzyme stabilisation in cellobiose hydrolysis

• Published in: Bioresource technology 2013-10, Vol.145, p.302-306
• Main Authors: Verma, Madan L., Rajkhowa, Rangam, Wang, Xungai, Barrow, Colin J., Puri, Munish
• Format: Article
• Language: English
• Subjects: Adsorption; Aspergillus niger - enzymology; beta-Glucosidase - metabolism; Biofuel; Biofuel production; Biofuels; Biological and medical sciences; Biotechnology; Biotechnology - methods; Cellobiose - metabolism; Energy; Enzyme Stability - physiology; Enzymes, Immobilized - metabolism; Fundamental and applied biological sciences. Psychology; Hot Temperature; Hydrogen-Ion Concentration; Hydrolysis; Immobilisation; Industrial applications and implications. Economical aspects; Lignocellulose; Nanobiotechnology; Nanotechnology - methods; Particle Size; Silk - chemistry; β-Gucosidase
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2013.01.065

► Ultrafine Eri silk particles (size 5μm) were prepared in short milling time without pre-treatment. ► Environment friendly Eri silk scaffold is used for immobilisation of β-glucosidase. ► Eri-silk bioscaffold protects the enzyme by increasing its rigidity and stability. ► Immobilised enzyme retained more than 50% of initial activity for up to eight cycles. The suitability of optimised ultrafine Eri silk microparticles as novel enzyme supports was studied for potential application in biofuel production. β-glucosidase (BGL) from Aspergillus niger was immobilised on Eri silk fibrion particles via an adsorption method resulting in a 62% immobilisation yield. Soluble and immobilised enzymes exhibited pH-optima at pH 4.0 and 5.0, respectively with optimum activity at 60°C. The Michaelis constant (KM) was 0.16 and 0.27mM for soluble and immobilised BGL respectively. The immobilisation support has a protective effect on the enzyme by increasing rigidity; this is reflected by an increase in stability under thermal denaturation at 70°C. Immobilised enzyme retained more than 50% of initial activity for up to eight cycles. Maximum cellobiose hydrolysis by immobilised BGL was achieved at 20h. Crystalline ultrafine Eri silk particles were found to be a promising viable, environmentally sound and stable matrix for binding BGL for cellobiose hydrolysis.