Pullulanase-Amylase Complex Enzyme from Bacillus subtilis

Abstract

A novel pullulanase-amylase complex enzyme, which hydrolyzes pullulan into maltotriose as well as starch into maltose and maltotriose as the main products, was found in the culture filtrate of a strain of Bacillus subtilis newly isolated from soil. The enzyme was purified to almost complete homogeneity by means of calcium phosphate gel adsorption, DEAE-Sepharose column chromatography and Bio-gel A-1.5m filtration. The optimum pH of the pullulanase activity was observed at around 7.0 to 7.5, with a discernible shoulder around pH 5.0. While the optimum pH of the amylase activity was 6 ~ 7. The optimum temperatures of the pullulanase and amylase activities were about 60°C and about 50°C, respectively. The molecular weight was estimated to be about 450,000 by the gel filtration method. The enzyme could be used for the production of glucose from starch with glucoamylase and the production of a new type of syrup containing a relatively high amount of maltotriose, 50 ~ 55%, from starch.