Chitosan functionalized with EDTA as a new support for enzyme immobilization and its application on enzymatic resolution of (R,S)-1-phenylethanol

Abstract

This research demonstrates the immobilization of lipases from Burkholderia cepacia (BCL), Candida rugosa (CRL), and Aspergillus niger (ANL) on chitosan functionalized with EDTA (CHT-EDTA) as support, and its employment as a biocatalyst. The adsorption capacity of lipase onto the CHT-EDTA surface was observed to increase with contact time and an optimal pH value (pH 6,5). Enzymatic activity and stability of lipases before and after conjugation to the support were evaluated in different conditions (pH, temperature, and organic solvents) and then compared with those of the free one. Conformational changes were investigated using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and thermogravimetric analysis (TGA). The results revealed that 112 mg/g for BCL/CHT-EDTA was the most significant amount of adsorbed lipase. The immobilized enzymes demonstrated enzymatic activity of 1.539 U/g for BCL/CHT-EDTA, followed by CRL/ and ANL/CHT-EDTA with 1.409 and 1.063 U/g, respectively. BCL/CHT-EDTA was then chosen to study the resolution of R,S-1-phenylethanol, achieving 99.9 % of ${\mathrm{ee}}_P$, 82 % of ${\mathrm{ee}}_S$, and 45 % of conversion (E > 200).