Geranyl acetate synthesis catalyzed by Thermomyces lanuginosus lipase immobilized on electrospun polyacrylonitrile nanofiber membrane

Abstract

Isolated Thermomyces lanuginosus lipase (TLL) was immobilized by different protocols on the polyacrylonitrile nanofibers membrane. The conditions for immobilization of TLL were optimized by investigating effect of protein concentration, time and temperature on the extent of immobilization. The effect of immobilization on the catalytic activity and stability of lipase was studied thoroughly. The immobilized TLL was used as biocatalyst for geranyl acetate synthesis with geraniol and vinyl acetate as substrates and their performance was compared with free enzyme. The TLL immobilized by physical adsorption shows higher transesterification and hydrolytic activities than that of covalently linked or native TLL. There was 32 and 9 fold increase in transesterification activity of TLL immobilized by adsorption and covalent bonding, while hydrolytic activity increases only by 3.6 and 1.8 fold respectively. The optimum conditions for immobilization in both the cases were immobilization time 90–150min, temperature 45°C and protein concentration of 2mg/ml. The percentage conversion of ester was more than 90% and 66% in case of physically adsorbed and covalently bonded enzyme respectively as compared to native one. However, covalently immobilized TLL shows higher operational stability than native and physically adsorbed TLL.