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

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 ( K m ) were found as 0.357 mM and 3.406 mM for free and lipase-Mt, respectively. The maximum reaction rate ( V max ) 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.