从黑茶中分离和筛选产单宁酶菌株

茶叶中富含单宁化合物。从分离自黑茶的真菌菌株中，筛选高产单宁酶的菌株；进而分离纯化单宁酶，分析单宁酶对茶汤的转溶效果。从不同产地的3个黑茶样品中，共分离获得44个真菌分离物；经初步鉴定，这些真菌分离物以曲霉属（Aspergillus）、青霉属（Penicillium）和散囊菌属（Eurotium）的真菌居多。以单宁酸为底物的鉴别培养基初筛表明，其中26个真菌分离物在鉴别平板上产生透明圈，显示单宁水解酶活性；通过固体发酵复筛，筛选到1株产单宁酶活性较高的菌株，初步鉴定为青霉属（Penicillium）菌株,命名为青霉MP-24菌株。青霉MP-24可以以茶叶、茶梗和麸皮等农副产品作为原料固体发酵产生单宁酶。以麸皮为原料的发酵产物经过硫酸铵分级沉淀、DEAE阴离子交换层析和葡聚糖G-150凝胶层析等分离纯化步骤，得到分子量为70 kDa的单一蛋白质条带，单宁酶活力达到603.68 U/mg。纯化获得的单宁酶对茶汤有良好的转溶效果。研究结果表明，在黑茶相关微生物中含有丰富的产单宁酶菌株，是工业酶制剂的重要资源。

Isolation & Screening of Tannase Producing Strains from Chinese Dark Tea

Tea leaves are rich in tannin compounds. The present study was to screen tannase high-producing strains from fungi isolated from Chinese dark tea and proceed to isolate and purify the tannase, analyze the trans-soluble effect of tannase on tea broth. A total of 44 fungal strains were isolated from 3 kinds of Chinese dark tea samples. Most of them were initially identified as members of Aspergillus, Penicillium and Eurotium. Twenty-six isolated fungal strains showed tannic acid hydrolysis activity by producing transparent circle on identification agar plate, which indicated tannase producing potential, by using agar plate tests. A fungal strain MP-24 with fairly high tannase activity after re screening on solid state fermentation was screened, it was initially identified as a strain of Penicillium, and named as Penicillium MP-24 strain. It could produce tannase by solid fermentation using tea leaf, tea stem, wheat bran and other agricultural and side line products as raw materials. Fermented product using wheat bran as raw material obtained a single protein band of 70 kDa in molecular weight, after precipitated in grades with ammonium sulfate, DEAE-cellulose anion exchange chromatography and Sephadex G-150 chromatography and other isolation and purification measures, and the tannase activity was as high as 603.68 U/mg. The purified tannase had a good trans-soluble effect on tea broth. The results of the study suggested that microbes related to Chinese dark tea are rich in tannin producing strains; it is an important resource of industrial tannase preparation.