Abstract: Tannase plays an important role in the food and fine chemical industries. The breeding and screening of a strain with high tannase activity are desired. A tannase-producing strain, DNM1-39, was isolated from resources rich in tannin. The activity of tannase in solid state medium after fermentation by the strain was 1.58 U/g. The strain was identified as Aspergillus through morphologic observation. A mutant strain named as UD-6 was obtained from DNM1-39 mutagenization with ultraviolet irradiation alone, DES treatment alone and both of them. The tannase activity produced by UD-6 was 2.80 U/g. The tannase-producing ability of UD-6 remained the same after continuous passages and displayed excellent genetic stability.

Key words: tannase, tannin, gallic acid, screening, mutagenesis