黑茶曲霉属和散囊菌属真菌产胞外水解酶能力的比较分析

Comparative Analysis of the Ability of Aspergillus and Europium in Dark Tea to Produce Extracellular Hydrolases

【目的】曲霉属和散囊菌属真菌是黑茶渥堆中的优势微生物,对形成黑茶风味、品质和生理功能起关键作用。但在茶叶发酵过程中这些真菌水解酶的差异尚不清楚。【方法】采用鉴别培养基平板检测和酶活性检测相结合,分析曲霉属和散囊菌属不同菌株在合成培养基上和茶叶发酵条件下胞外水解酶活性的差异。【结果】鉴别培养基平板检测结果显示:供试的9个菌株均不同程度呈现纤维素酶、木聚糖酶和单宁酶活性,7个菌株显示淀粉酶活性,2个菌株显示果胶酶活性,1个菌株显示蛋白酶活性。同一菌株可以同时分泌多种胞外水解酶,多个菌株也可以表现同一水解酶的活性,不同菌株产生胞外水解酶能力存在显著差异。在茶叶发酵过程中,黑曲霉菌株PE-3水解大分子碳水化合物酶活性显著高于冠突散囊菌菌株PE-1。其中,淀粉酶活力达到33.81 U/mL。而菌株PE-1的单宁酶和蛋白酶活性则显著高于菌株PE-3。其中,单宁酶活力达到132.09 U/mL。【结论】在茶叶发酵过程中,曲霉属和散囊菌属的菌株可能具有对不同茶叶成分的选择性,水解酶的协同作用影响菌株对茶叶成分的利用效率。

【Objective】Aspergillus and Eurotium are the dominant microorganisms in the pile fermentation of Chinese dark tea, and play a key role in the formation of different flavors, qualities and physiological functions of dark tea. However, the differences in these fungal hydrolases during tea fermentation are still unclear.【Method】The difference of extracellular hydrolase activity between different strains of Aspergillus and Eurotium in the synthetic medium and tea fermentation conditions was analyzed by combining differential medium plate assay and enzyme activity assay.【Result】 The results of differential medium plate assay showed that: Nine strains tested showed cellulose, xylanase and tannase activities to different extent;seven strains showed amylase activity, two strains showed pectinase activity, and one strain showed protease activity. The same strain could secrete a variety of extracellular hydrolases at the same time, and multiple strains could also show the activity of the same hydrolase. The ability of different strains to produce extracellular hydrolase was significantly different. During the fermentation of tea , the enzymatic activity of Aspergillus niger strain PE-3 hydrolyzed macromolecular carbohydrates was significantly higher than that of Eurotium cristatus strain PE-1,with the amylase activity of strain PE-3 at 33.81 U/mL. While the tannase and protease activities of strain PE-1 were significantly higher than those of strain PE-3,with the tannase activity at 132.09 U/mL.【Conclusion】 During the fermentation of tea, the strains of Aspergillus and Eurotium might have selectivity for different tea components, and the synergistic effect of hydrolases had an impact on the utilization efficiency of the tea components.