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Production of tannese by Aspergillus niger

Öztürk, Alev Deniz
In this study, a filamentous fungus, Aspergillus niger was evaluated in terms of extracellular tannase production. The effect of tannic acid, glucose and nitrogen sources on tannase and biomass productions was investigated and their concentrations were optimized. The highest enzyme activity was recorded as 316 U/ml in the optimized medium containing 8% Tannic acid, 1% Glucose, 0.4% (NH4)2HPO4, 0.1% K2HPO4, 0.1% MgSO4.7H2O, 0.01% ZnSO4.7H2O, 0.0005% NaCl in a shake-flask bioreactor at 35oC and 175 rpm. The bioreaction profile including tannic acid, gallic acid, pyrogallol, glucose concentrations, pH, biomass and extracellular tannase production were determined under the optimized conditions. The maximum extracellular tannase activity (316 U/ml) was observed on the 4th day of cultivation. However, biomass continued to increase up to the 9th day of fermentation. Increase in biomass concentration during the first two days and after the 7th day was high. The microorganism used tannic acid and glucose during the first two days by considering the sharp decrease in tannic acid and glucose concentrations. The increase in biomass concentration after the 7th day was directly proportional to the decrease in pyrogallol concentration in this period of time. The pH of the cultivation medium decreased from 5.5 to 2.3 owing to the assimilation of glucose and the production of gallic acid. Keywords: Tannase, Aspergillus niger, Enzyme production, Cultivation profile, Tannic acid.