单宁是植物应对生物和非生物胁迫响应的多酚类化合物，在皮革鞣制和粘合剂制造等方面都有相关应用，且在药物开发和营养保健品行业有应用前景。单宁的分子量影响其生物活性，高分子的单宁生物活性低、经济价值小，因此需要通过降解高分子单宁获得生物活性更高、经济价值更大的低聚单宁或单体。酶降解是降解单宁的有效途径。 木榄树皮的单宁含量高达35%，叶片总单宁含量高于15%。本研究从木榄树皮2个组织块和成熟叶片4个组织块中分离得内生真菌36株，筛选出35株耐水解单宁真菌，其中32株能分解单宁酸。选用树皮来源的可分解单宁酸的真菌进行了鉴定，分别为Diaporthe eugeniae，Diaporthe sp.，Phomopsis sp. C5和Phomopsis sp. 156AH/T。Diaporthe属和Phomopsis属真菌是新发现的单宁酶生产者。

本研究使用了保玉心的分光光度计法进行胞外单宁酶活力的测定，发现这12株真菌产出的单宁酶活性较高。在未经优化的情况下，P1AA所产单宁酶的酶活力达69.10 U/mL，具有优化的潜力。未来可以对其单宁酶的大小、酶活性质、产物组成等方面进一步研究。 另外，本研究发现从木榄分离得的内生真菌均耐缩合单宁，可能产生缩合单宁降解相关的酶，值得进一步研究。

Tannins are polyphenols that are used by plants in response to biotic and abiotic stresses. They have relevant applications in leather tanning and adhesive manufacturing. Polymer tannins have low biological activity and low economic value, so we need to degrad polymer tannins. Enzymatic degradation is an effective way to degrade tannins. In this study, 36 strains of endophytic fungi were isolated from B. gymnorhiza bark and mature leaves. Thirty-five strains of hydrolysable tannin-resistant fungi were screened, of which 32 were able to decompose tannins. The bark-derived fungi that could decompose tannic acid were selected for identification, including Diaporthe eugeniae, Diaporthe sp., Phomopsis sp. C5 and Phomopsis sp. 156AH/T. Fungi of Diaporthe and Phomopsis are newly discovered tannase producers. These 12 fungal strains produced high tannase activity. The enzyme activity of tannase produced by P1AA reached 69.10 U/mL。 Further investigation is warranted to ascertain the tannase size, nature of enzyme activity, and product composition. Furthermore, this study revealed that all endophytic fungi isolated from B. gymnorhiza exhibited resistance to condensed tannins and might produce enzymes related to condensed tannin degradation.