Construction and characterization of a nanostructured biocatalyst consisting of immobilized lipase on aminopropyl-functionalized montmorillonite

Abstract

Clay minerals provide an excellent platform for enzyme immobilization, which can improve enzyme activity and stability for industrial applications. In this study, lipase from Aspergillus oryzae was immobilized on 3-aminopropyltriethoxysilane (APTES) amphiphilic functionalized montmorillonite (Mt) support via 1-(3-Dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride (EDC) spacer. The APTES-Mt and APTES-Mt based nanostructured biocatalyst (lipase-Mt) were characterized by XRD, FT-IR, TEM, SEM and contact angle analysis. Optimal immobilization conditions were determined considering parameters of EDC concentration, initial lipase concentration, pH, and reaction time. The results indicated that lipase-Mt activity was 40.65 U/mg, which was nearly 4-fold higher than that of free lipase under optimal conditions. The Michaelis-Menten constant (Km) were found as 0.357 mM and 3.406 mM for free and lipase-Mt, respectively. The maximum reaction rate (Vmax) for the free and lipase-Mt were calculated as 63.69 mM/(L·min) and 312.5 mM/(L·min), respectively. Further, the interfacial activation by amphiphilic surface of APTES-Mt and enlarged catalytic interface contributed to the improved activity and storage stability of lipase-Mt. Thus, this work demonstrate an economically viable method for constructing nanostructured biocatalyst for industrial applications based on covalent immobilization of enzyme onto clay minerals.