Covalent immobilization of Aspergillus niger amyloglucosidase (ANAG) with ethylenediamine-functionalized and glutaraldehyde-activated active carbon (EFGAAC) obtained from sesame seed shell

Abstract

This study was aimed the covalently immobilization of Aspergillus niger amyloglucosidase (ANAG) onto activated carbon (AC) obtained from sesame seed shell. AC was firstly functionalized with ethylenediamine, and after then activated with glutaraldehyde. 99.80% immobilization yield and 99.83% activity yield were obtained as the result of optimization of immobilization conditions (pH and molarity of immobilization buffer, AC amount, and reaction time). The optimum pH (5.5) and the optimum temperature range (55–60 °C) for ANAG were not affected by immobilization. After immobilization, Vmax value decreased from 1464.1 μmol D-glucose/L.min to 1342.3 μmol D-glucose/L.min, while Km value decreased from 116.3 g maltodextrin/L to 109.9 g maltodextrin/L. The immobilized enzyme retained 99.30% and 98.30% of its initial activity, respectively after twenty repeated uses and after twenty days of storage in 5 mL sodium phosphate buffer (0.1 M, pH 5.5) at +4 °C in a refrigerator. Finally, glucose syrup was produced from maltodextrin solution having 1% (w/v) concentration by using the immobilized ANAG. Maltodextrin was completely converted to glucose after four hours. Consequently, it can be said that the immobilized ANAG obtained in this study can be used in the industrial production of glucose syrup.