Immobilization of Chaetomium erraticum dextranase on carbon nanotubes

In this study, Chaetomium erraticum dextranase (CED) enzyme was immobilized onto c-MWCNT using adsorption method. Optimization of the immobilization conditions such as the pH and molarity of the immobilization buffer, the amount of c-MWCNT and the time of immobilization resulted in 100% immobilization yield and 114.15% activity yield. Characterization of free and immobilized CED has also been studied. After immobilization, the optimum pH of the CED shifted from 5.0 to 6.0, while the optimum temperature (55 °C) did not change. Kinetic constants were also determined for free and immobilized CED using the Lineweaver-Burk plot. The Km values of free and immobilized CED were 56.18 g/L and 65.36 g/L, respectively, and Vmax values were 523.56 μg reductive sugar/ L.min. and 595.24 μg reductive sugar/L.min. On the other hand, there was no reduction in the initial activity of the immobilized CED after 20 consecutive uses and 30 days of storage at optimal storage conditions. Finally, 17.15% and 17.53% of the dextran, in 10% dextran solution (pH 6.0), were converted to reduced sugars (IMOs and Glucose) using free and immobilized CED respectively, in 12 hours. As a result, the immobilized CED obtained in this study can be used in the industrial production of IMOs and in the hydrolysis of dextran.