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

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 (K(M)) was 0.16 and 0.27 mM 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 20 h. Crystalline ultrafine Eri silk particles were found to be a promising viable, environmentally sound and stable matrix for binding BGL for cellobiose hydrolysis.