Purification and Characterization of Extra cellular Tannin Acyl Hydrolase from Aspergillus heteromorphus MTCC 8818

A tannase (E.C. 3.1.1.20) producing fungal strain was isolated from soil and identified as Aspergillus heteromorphus MTCC 8818. Maximum tannase production was achieved on Czapek Dox minimal medium containing 1% tannic acid at a pH of 4.5 and 30℃ after 48 h incubation. The crude enzyme was purified by ammonium sulfate precipitation and ion exchange chromatography. Diethylaminoethyl-cellu lose column chromatography led to an overall purification of 39.74-fold with a yield of 19.29%. Optimum temperature and pH for tannase activity were 50℃ and 5.5 respectively. Metal ions such as Ca²+, Fe²+, Cu¹+, and Cu²+ increased tannase activity, whereas Hg²+, Na¹+, K¹+, Zn²+, Ag¹+, Mg²+, and Cd²+ acted as enzyme inhibitors. Various organic solvents such as isopropanol, isoamyl alcohol, benzene, methanol, ethanol, toluene, and glycerol also inhibited enzyme activity. Among the surfactants and chelators studied, Tween 20, Tween 80, Triton X-100, EDTA, and 1, 10-o-phenanthrolein inhibited tannase activity, whereas sodium lauryl sulfate enhanced tannase activity at 1% (w/v).