Purification and characterization of &#946-glucosidase from newly isolated Aspergillus sp. MT-0204

Aspergillus sp. MT-0204, a novel strain for producing β-glucosidase, was isolated from soil in this study. The β-glucosidase can hydrolyze glycosides and increase free isoflavones in soy products isoflavones. By examining physiological, biochemical characteristics and comparing its ITS rDNA gene sequence, it was identified as Aspergillus niger, and named A. niger MT-0204. The A. niger β- glucosidase was purified in four steps. Some characteristics of purified β-glucosidase were also studied. The β-glucosidase activity could be assayed at the pH ranging from 3.5 to 10.0, and its maximum activity was obtained between pH 5.0 and 5.5. The enzyme was sensitive to heat, decreasing slowly between 60 and 80°C, and significantly at 85°C. The enzyme activity was activated by K+, Ca2+,Fe2+, Mg2+ and Mn2+, while strongly inhibited by Ag+ and Hg+, and slightly inhibited by Cu2+, Zn2+, Ba2+, Ni+, EDTA-Na2 and fumarate