Stabilization of phytase on multi-walled carbon nanotubes via covalent immobilization

This chapter provides one of the covalent methods to immobilize phytase, the most important feed enzyme, on Multi-walled carbon nanotube in order to improve enzyme characteristics. Various techniques such as scanning electron microscopy, FTIR and CD spectroscopy, along with zeta potential measurement were performed to confirm immobilization. Catalytic activity measurement of phytase was explained in details and enzyme loading efficiency was measured. The results indicated a 38% decrease in enzyme activity after immobilization which could because of structural changes or wrong enzyme orientation after immobilization. Also, optimum temperature and pH of free and immobilized enzyme were performed. The remaining activity of free and immobilized enzymes was also investigated after treating with higher temperatures using in the pelleting process. Immobilized phytase showed 10-fold resistance against 90°C temperature in comparison with free phytase. Finally, the effect of NaCl on the catalytic activity of free and immobilized phytase was examined and showed interesting results. We found that the catalytic activity of immobilized could increase by about 80% in the presence of 0.2M NaCl.