Abstract:

α-Glucosidase is the key enzyme involved in the production of isomaltoligosaccharides which are widely applied
in the food, medicine, health care and feed industries. A mutant Aspergillus strain named ANY-4, with high α-glucosidase
activity and good genetic stability, was obtained from Aspergillus niger J2 via microwave-induced mutation. Its enzymatic
activity was 305 U/mL, which was 38.6 % higher than that of Aspergillus niger J2. To produce α-glucosidase with a high
yield, single factor experiments and orthogonal array design methods were performed to determine the optimal fermentation
conditions as follows: corn starch 80 g/L, corn steep liquor powder 40 g/L, initial pH 4.5, fermentation medium volume
50 mL in 500 mL flasks, inoculum quantity 3% (V/V), 36 ℃, 240 r/min and fermentation for 40 h. Under these conditions,
the α-glucosidase activity was 427 U/mL, which was increased by 40% as compared to that obtained before optimization.

Key words: α-glucosidase, microwave mutagenesis, Aspergillus niger, optimization