Optimization Of Fermentation Conditions Of Strain MP-24 For Tannase Production And Biotransformation Of Tea Polyphenols

Tannin acyl hydrolase (E.C.3.11.20) commonly referred to as tannase, and can catalyze the hydrolysis of ester and hydrolyse to gallic acid and glucose. Tannin enzyme has been widely used in food, feed, pharmaceutical, beverage, brewing industry and chemical industry, etc. In this paper, based on the morphology and fungal ITS analysis, a fungal strain MP-24 which produced tannase was preliminary identified. The solid-state fermentation culture medium formula and fermentation condition were optimized. And the tannase was used to biotransform the tea polyphenols and tea infusion. By using the method of HPLC and LC-MS analysis, the converted products and the antioxidant activity of the products were determined.After morphological observation and molecular evaluation analysis, the fungal strain MP-24 was identified as penicillium sp. Maximum tannase production was obtained when SSF was carried out at 28?, pH 6.057, liquid-to-solid ratio (v/w) 1.8, inoculum size 2.0 mL, tea leave 4.5 g, gallotannic acid 0.5 g,1.070%(w/v) ammonium chloride as nitrogen source,2.048% magnesium sulphate and 5%(w/v) lactose as additional ion sources. Under optimum conditions, tannase activity reached 30.37 U/g dry substrate (U/gds) after 96 h of fermentation. The tannase activity under optimum conditions was 2.91 times as higher as that under initial culture conditions. Purified tannase had significant effects on tea infusion conversion. And it can significantly increase tea infusion clarity. The crude and purification of tannase biotransformated tea and tea polyphenol, then detection by HPLC and LC-MS and test its antioxidant activity. The results also showed that after biotransformated by tannase, tea infusion and tea polyphenol's antioxidant activity increased. This study identified a strain MP-24 isolated from dark tea, optimize the solid culture medium and culture conditions, has been clear about the MP-24 tannase from the transformation effect of tea polyphenols have certain and the clarity that can improve the tea and antioxidant activity. The results of this study provided the tannase production and application of the theory basis and reference.