Covalent Immobilization of Lipase in Residual Yerba Mate Stick (Ilex paraguariensis A. St.-Hil.)

Abstract

The objective of this study was to immobilize Eversa® Transform 2.0 lipase on residual yerba mate stick. The stick went through an alkaline pre-treatment and different activation treatments (APTS/glutaraldehyde and sodium metaperiodate). Immobilization was performed using hexane solvent and ammonium nitrate buffer. Support characterization, esterification activity, immobilized enzyme characterization, and operational stability were performed. Characterization by SEM demonstrated that the activation treatments were efficient. The immobilization of lipase on APTS/glutaraldehyde activated support showed a yield of 225.52 % and metaperiodate 162.76 %, using hexane as solvent. Good operational stability of the immobilized lipase was observed both in support activated with APTS / glutaraldehyde (8 recycles) and in support activated with metaperiodate (5 recycles), maintaining the activity of 65.62% and 52.00% in concern to the activity initial, respectively. The optimal reaction temperature was 40 ºC for the free and immobilized enzyme. Km and Vmáx values were 16.55 μmol.g-1 and 5555.56 μmol.g-1.min-1 for free enzyme; 33.52 μmol.g-1 and 4761.9 μmol.g-1.min-1 for immobilized enzyme, respectively. The parameters of thermal inactivation confirmed a better thermostability of the lipase in free form.