College of Longrun Pu-erh Tea, Yunnan Agricultural University, Kunming, Yunnan 650201, China.
State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036 Anhui, China.
Food Chem. 2021 Jan 1;334:127560. doi: 10.1016/j.foodchem.2020.127560. Epub 2020 Jul 17.
Post-fermented Pu-erh tea (PFPT) is a microbially-fermented tea with distinct sensory qualities and multiple health benefits. Aspergillus are the dominant fungi in the fermentation and the main contributors to the characteristics of PFPT, so their underlying functions warrant detailed study. Here, tea leaves were fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus, and resulting samples (designated as Asn, Ast and Asf, respectively) were analyzed by proteomic and metabolomic methods. Changes to the composition of flavonoids, glycerophospholipids, organo-oxygen compounds and fatty acids resulting from Aspergillus fermentation were observed. Carbohydrate-active enzymes, e.g., endoglucanases and cellulases, for degradation of cellulose, starch, lignin, pectin, xylan and xyloglucan were identified. Glycoside hydrolase, glycosyltransferases, tannase, laccases, vanillyl-alcohol oxidases and benzoquinone reductase were identified and hypothesized to catalyze hydrolysis, oxidation, polymerization and degradation of phenolic compounds. Together, functions of Aspergillius were demonstrated as production of enzymes to change concentrations and compositions of metabolites in tea leaves.
后发酵普洱茶（PFPT）是一种微生物发酵茶，具有独特的感官品质和多种健康益处。曲霉菌是发酵过程中的优势真菌，也是 PFPT 特征的主要贡献者，因此它们的潜在功能值得详细研究。在这里，茶叶分别被黑曲霉、米曲霉和烟曲霉发酵，得到的样品（分别命名为 Asn、Ast 和 Asf）分别通过蛋白质组学和代谢组学方法进行分析。观察到曲霉菌发酵导致类黄酮、甘油磷脂、有机氧化合物和脂肪酸组成的变化。鉴定出用于降解纤维素、淀粉、木质素、果胶、木聚糖和木葡聚糖的碳水化合物活性酶，如内切葡聚糖酶和纤维素酶。鉴定出糖苷水解酶、糖基转移酶、单宁酶、漆酶、香草醇氧化酶和苯醌还原酶，并假设它们催化酚类化合物的水解、氧化、聚合和降解。总之，曲霉菌的功能被证明是产生酶来改变茶叶中代谢物的浓度和组成。
