Immobilization of Chaetomium erraticum dextranase enzyme on multi-walled carbon nanotubes functionalized with amino group by adsorption method

In this thesis study, Chaetomium erraticum dextranase (CED) was immobilized onto amino-functionalized multi-walled carbon nanotubes (MWCNT-NH2) using the adsorption method. The immobilization buffer's pH and concentration, the amount of MWCNT-NH2, and the immobilization duration were optimized to achieve 100% immobilization efficiency and 137.5% activity yield. The characterization of immobilized CED (ICED) and free CED (FCED) was performed. After immobilization, the optimum pH value of CED expanded from 5.0 to the range of 5.0-6.0 ranges, while the optimum temperature (55°C) remained unchanged. Additionally, the kinetic constants for FCED and ICED were determined using the Lineweaver-Burk plot. When dextran substrate was used, the Km values for FCED and ICED were calculated as 325.7 g/L and 211.9 g/L, respectively, while the Vmax values were 2785.5 µmol/ml.min and 6211.2 µmol/ml.min, respectively. No significant decrease in initial activity was observed for ICED after 20 consecutive uses and 20 days of storage under optimal conditions. As a result, the ICED obtained from this thesis study can be used effectively in the hydrolysis of dextran and IMO production from dextran applications in the food industry.