Maltotetraose-producing Amylase from Bacillus sp. MG-4

A maltotetraose-producing amylase that hydrolyzes starch in maltotetraose units was first found in the culture filtrate of a strain of Bacillus circulans MG-4 newly isolated from soil. The enzyme was partially purified by ammonium sulfate fractionation, DEAE-Sepharose column chromatography, and Bio-Gel A-0.5 column chromatography. The basic enzymatic properties and saccharification conditions of starch for the use of this enzyme were examined with this partially purified enzyme. Its optimum pH and temperature were around 7.5 and around 50°C, respectively. The enzyme was protected from heat in the presence of calcium ion. This enzyme produced maltotetraose in a yield more than 60% from liquefied starch. A typical sugar composition of hydrolysis products from liquefied starch was about G, 1.5%, G2 8.2%, G3 10.9%, G4 64.9%, G5 0.0%, G6 1.0%, G7 1.2%, G8 1.3%, G9 1.0%, and G10 ~ 11.0%.