Effect of Gamma Irradiation on Aspergillus tamarii FNCC 6151 to enhance Alpha-Amylase and Glucoamylase Production

Molds can carry out amylase production, but the production of the enzyme is affected by a carbon catabolite repression system, thus reducing amylase production. This study aimed to increase amylase production in Aspergillus tamarii FNCC 6151 with irradiation by gamma rays. Spore suspensions were irradiated at 100, 200, 300, 400 and 500 Gy and the survival of the spores was determined. The spore suspension irradiated at 400 Gy was diluted and grown on medium plates containing starch as a carbon source and 2% glucose as a repressor. After staining with iodine, colonies showing clear zones around them were purified and grown in liquid media for four days and their alpha-amylase and glucoamylase activities were analyzed. The mutant Mut1 showed a clear zone. This mutant produced 1.127 U/mL of alpha-amylase and 0.011 U/mL of glucoamylase. Meanwhile, the parental strain produced 0.68 U/mL of alpha-amylase and 0.079 U/mL of glucoamylase. The random mutagenesis using gamma-ray into A. tamarii FNCC 6151 increased alpha-amylase and glucoamylase production by 1.8- and 1.4-fold respectively.