Effect of glutaraldehyde addition on the stability of the α-amylase from Bacillus subtilis ITBCCB148

Abstract α-Amylase is widely used in industry because of its ability to hydrolyze starch to glucose. Limited enzyme activity in extreme pH and temperature makes it necessary to increase enzyme stability. The purpose of this study was to improve the stability of the α-amylase from the bacteria Bacillus subtilis ITBCCB148 by chemical modification using glutaraldehyde (GA). The results showed that modified enzymes using glutaraldehyde 0.01; 0.03 and 0.05% have an optimum pH of 5.5; optimum temperature of 55°C; KM of 4.74; 5.03 and 3.87 mg/mL substrate; the Vmax of 285.71; 270.27 and 212.77 μmol mL−1 min−1; ki of 0.0183; 0.0111 and 0.0160 min−1; half-life (t1/2) 37.87; 62.43 and 43.31 minutes; ΔGi 102.656; 104.047 and 103.038 kJ mol−1, respectively. Chemical modification of the α-amylase from B. subtilis ITBCCB148 using glutaraldehyde can increase thermal stability by 1.6-2.7 times which can be seen from a decrease in the value of ki, an increase in half-life and ΔGi.