Purification and characterization of tannin acyl hydrolase from Aspergillus niger ATCC 16620

Abstract

Tannin acyl hydrolase produced extracellularly by the fungal strain Aspergillus niger ATTC 16620 in solid state fermentation was purified from the cell free culture broth by ammonium sulphate fractionation followed by DEAE-Sephadex A-50 chromatography. SDS-PAGE analysis indicated that the enzyme protein molecular mass was 168 kDa. Enzyme activity was stable up to the temperature of 40 degrees C and the enzyme activity was optimal at pH=6. Tannase activity was maximal at 0.01 M concentration of the substrate. The addition of metal ions like Zn2+, Mn2+, Cu2+, Ca2+, Mg2+, Fe2+ inhibited the enzyme activity. Only K+ ions enhanced tannase activity, and an activity of 4.31 U/mL was reported here. Enzyme activity was maximal after 15-20 min of incubation time, with an activity of 3.9 U/mL. K-m was found to be 1.03 mM and V-max=4.25 mu mol/min. Since the enzyme is active over a wide range of pH and temperature it could find potential use in the food-processing industry.