Hyperproduction of Tannin Acylhydrolase in Submerged Fermentation from Aspergillus fumigatus

Abstract

Tannin acyl hydrolase (E.C.3.1.1.20) is commonly referred as tannase, hydrolyses ester and depside bonds of hydrolysable tannins to produce gallic acid, glucose and galloyl esters. Tannase finds application in many industrial sectors which includes pharmaceutical, food, chemical and beverages industry. The enzyme has potential uses in the treatment of tannery effluents and pre-treatment of tannin containing animal feed. Aspergillus fumigaus-10561 produced maximum extracellular tannase activity (0.430 U/ml) grown in medium supplemented with 0.05 % each of K2 HPO4, KH2 PO4 , MgSO4 , 0.3 % NH4 NO3, and 0.5 % tannic acid as substrate inducer at 40°C, pH 7.0 for 48 h. Maximum tannase activity was reached in 50 mM citrate buffer (pH 5.5) with substrate concentration of 100 mM methyl gallate at 35°C in 5 min. All the metal ions inhibited the enzyme activity, but maximum inhibition (45 %) was recorded in presence of β-mercaptoethanol. The thermal stability of this enzyme was studied and the enzyme was found to be fairly stable at 50°C up to 120 min. On performing the time course of enzyme reaction at different temperatures, maximum product yield was detected at 35°C after 40 minutes of reaction. Only 7 % loss of activity was observed on storage at 4°C, whereas at room temperature 66.50 % residual activity was retained when stored for 26 days. The present study showed that the fungal strain Aspergillus fumigatus-10561 has high potential for industrial production of tannase.