Background: Tannase can be obtained from the various sources for example tannin rich plants; however microbial sources are preferred for industrial production. In microbial sources, the Aspergillus and Penicillium genus and lactic acid bacteria mostly produce tannase. However, it has been identified that this enzyme is produced by many fungi and bacteria, but researches are continuing to find new species. Objectives: The aim of this study was to isolate a tannase-producing fungi from moldy tea leaves and to study some properties of its enzyme. Materials and Methods:The present study was done via two steps. At first, industrially important tannaseproducing fungi were isolated from moldy tea leaves using the simple agar plate method followed by the screening of organisms capable of producing tannase using the enrichment culture technique in modified Czapek Dox's agar. Finally, tannase obtained from the best isolate was partially purified and characterized. Results: Tannase produced by Penicillium sp. EZ-ZH190 isolated from moldy tea leaves was partially purified and characterized. Maximum enzyme production (4.33 U.mL -1 ) was recorded after 96 hours of incubation at 30 °C in submerged culture (100 rpm) utilizing 1 % (w/v) tannic acid as a sole carbon source. This tannase exhibited optimum activity at 35 °C and at pH of 5.5, and showed nearly 50 % of its maximal activity at 50 °C. In the present study, tannase from Penicillium sp. EZ-ZH190 had KM and Vmax values of 1.24 mM and 17.09 U.mL -1 , respectively, and showed more than 50 % stability at salt (NaCl) concentration of 1 M for 24 hours. Conclusions: Tannase productivity of Penicillium sp. EZ-ZH190 (0.045 U.mL -1 .h -1 ) is comparable with the maximum tannase productivity in the reported literatures, and the biochemical characteristics showed by Penicillium sp. EZ-ZH190 tannase are considered favorable for tannin biodegradation in the industry. So, we concluded that Penicillium sp. EZ-ZH190 is a good strain for use in the efficient production of tannase.

In the search for an efficient producer of tannase, Penicillium sp. EZ-ZH190 was subjected to mutagenesis using heat treatment and strain EZ-ZH290 was isolated. The maximum tannase in this mutant strain was 4.32 U/mL with an incubation period of 84 h as compared to wild strain EZ-ZH190 where the incubation period was 96 h with a maximum enzyme activity of 4.33 U/mL. Also, the Penicillium sp. EZ-ZH290 tannase had a maximum activity at 40 °C and pH 5.5. Then, the spores of strain EZ-ZH290 were subjected to γ irradiation mutagenesis and strain EZ-ZH390 was isolated. Strain EZ-ZH390 exhibited higher tannase activity (7.66 U/mL) than the parent strain EZ-ZH290. It was also found that Penicillium sp. EZ-ZH390 tannase had an optimum activity at 35 °C and a broad pH profile with an optimum at pH 5.5. The tannase pH stability of Penicillium sp. EZ-ZH390 and its maximum production of tannase followed the same trend for five generations confirming the occurrence of stable mutant. This paper is shown that γ irradiation can mutate the Penicillium sp. leading to increase the tannase production.