Covalent immobilization of cellulase in application of biotransformation of ginsenoside Rb1

Cellulase was immobilized on the surface of carrageenan beads activated by using polyethyleneimine and glutaraldehyde, then immobilized cellulase was used to transform ginsenoside Rb 1 . In this work, we studied the functionalization of carrageenan with amine terminal functional group for the covalent immobilization of cellulase. The process of immobilization was performed by amination process on the surface of the carrageenan gel beads with polyethylenimine followed by activation with glutaraldehyde to finally immobilize the enzyme. Different factors affecting the amination and activation processes were studied and their effects on the catalytic activity of the immobilized cellulase were followed, then Fourier transform infrared spectroscopy and scanning electron microscopy were applied to verify the process. Furthermore, the optimum conditions of transformation of ginsenoside Rb 1 were also studied and showed better stability for the immobilized enzyme. The best results were obtained using carrageenan as support and covalent binding method, which consisted of amination process (0.5% PEI (pH 8))) for 3   h and 3% GA in activation process for 3   h. These experiments gave optimum reaction condition of temperature at 60°   C and pH 5.0. Enzyme after immobilization exhibited high activity with broader pH and temperature range. Full conversion and kinetic parameters K m and V max for them were also studied. The K m of immobilized enzyme, 3.64   mM, is lower than free one, 4.82   mM; and the V max of immobilized enzyme, 0.04   mM, is lower than free one, 0.06   mM. Results detected also show after using for 5 consecutive times, the immobilized enzyme can retain 60% of its initial activity.