Overproduction of an α-Amylase/Glucoamylase Fusion Protein in Aspergillus oryzae Using a High Expression Vector

alpha -Amylase (AAase) [EC 3.2.1.1, alpha -1,4-glucan-4-glucanohydrolase] and glucoamylase (GAase) [EC 3.2.1.3, alpha -1,4; 1,6-glucan glucohydrolase] are widely used in industrial applications, e.g., for the production of glucose and various alcoholic beverages. In many cases, these enzymes are used in combination to obtain glucose from raw starches. Therefore a bifunctional enzyme having both AAase and GAase activities may be useful because it could eliminate the process and period of saccharification, and reduce overall consumption of the amylases. In this report we describe the construction of the expression vector and overproduction of the AAase/GAase fusion protein using the resultant expression vector in A. oryzae.