Rapid and high-density covalent immobilization of Rhizomucor miehei lipase using a multi component reaction: application in biodiesel production

Abstract

Aldehyde-functionalized silica and silica nanoparticles (SBA-15) were prepared as a matrix system for enzyme immobilization. Immobilization of Rhizomucor miehei lipase (RML) on these supports was performed via a multicomponent reaction under extremely mild conditions (25 °C, pH 7). Investigation on the mechanism of this reaction confirmed the Ugi four-component immobilization approach. The loading capacity of the supports and specific activity of the immobilized derivatives were interestingly improved. The results revealed very rapid immobilization of 10 and 60 mg of RML on 1 g of aldehyde-functionalized silica and SBA-15 after 10 and 30 minutes, respectively. Leaching experiments were performed by incubation of the immobilized derivatives in 1 M NaCl solution. The lack of the free lipase in the solution confirmed the covalent nature of the linkage. The thermal stability and co-solvent stability of the derivatives in the presence of three polar organic solvents (1-propanol, 2-propanol and dioxane) were greatly improved compared to the soluble enzyme. Both the derivatives were also used to catalyze the transesterification of colza oil with methanol to produce fatty acid methyl esters (FAMEs). In the case of RML immobilized on SBA-15 (SBA-RML), the presence of 40% of tert-butanol (v/v) as solvent in the reaction medium largely improved the conversion yield.