The optimization of Aspergillus sp. GM4 tannase production under submerged fermentation

Abstract

Tannase is a hydrolytic enzyme that is involved in the biodegradation of tannins and it has biotechnological po- tential in the pharmaceutical, chemical, food and beverage industries. Microorganisms, especially filamentous fungi, are important tannase producers. The aims of this work were to find a potential tannase producer and to improve the cultivation conditions. Three Aspergillus species (A. japonicus 246A, A. tamarii 3 and Aspergillus sp. GM4) were investigated in different culture media (Adams, Czapeck, Khanna, M5 and Vogel) and inducers (1% and 2% tannic acid; 1% green tea; 1% methyl gallate; 1% gallic acid). Aspergillus sp. GM4 and Adams medium were selected. The tannase production by Aspergillus sp. GM4 in Adams medium was induced in the presence of 2% (w/v) tannic acid and gallic acid as carbon sources, while green tea was not able to induce tannase produc- tion. The Plackett-Burman screening design was performed with the variables MgSO 4 , KH 2 PO 4 , yeast extract, tannic acid, agitation rate and salt solution. The variables MgSO 4 and agitation rate were selected for the opti- mization of tannase production using a Central Composite Rotatable Design. Under optimized conditions, a 2.66-fold increase in the enzyme production was observed with small modifications in the medium composition.