Abstract

The production of tannases by Aspergillus tamarii was evaluated in submerged cultures using tannic acid and gallic acid as substrates. Two tannases, designated as TAH I and TAH II were produced in gallic acid submerged cultures. TAH I, responsible for 70% of the total tannase activity was purified to apparent electrophoretic homogeneity with 18.35% yield. The enzyme is a homodimeric protein with molecular mass of 180 kDa and 40.5% of its weight corresponds to carbohydrates. TAH I exhibited optimal activity at 30°C and pH 5.5 and was stable over a large pH range (3.0 to 9.0) and at temperatures up to 40°C. With methyl gallate as substrate, the enzyme presented a K_M of 0.77 mM and a V_max of 682.8 U/mg proteins. The enzyme was inhibited by metal ions but showed relative resistance to organic solvents and surfactants. Since the enzyme is active over a wide range of pH and temperature, it is potentially useful in food and pharmaceutical industries.

Key words: Aspergillus tamarii, enzyme purification, submerged culture, tannase.