Jian Xiaoyun, Zhang Jinwei
Key Laboratory for Leather Chemistry and Engineering of the Education Ministry, Sichuan University, 610065 Chengdu, China.
College of Biomass Science and Engineering, Sichuan University, 610065 Chengdu, China.
ACS Omega. 2022 Feb 9;7(7):5809-5816. doi: 10.1021/acsomega.1c05768. eCollection 2022 Feb 22.
Chemical degradation is widely used for producing lower-molecular-weight tannin compounds and tannin disposal, but it has negative effects on the environment, such as causing secondary pollution and consuming energy. For overcoming these disadvantages, a cleaner and sustainable degradation and disposal method for condensed tannins was developed through biodegradation. In this study, bayberry tannin solution, one kind of condensed tannin, was biodegraded by sp. at first; then, gel permeation chromatography and high-performance liquid chromatography were used for separating the biodegraded and original tannins to analyze the differences in components; finally, the changes in the tannin structure after biodegradation were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nuclear magnetic resonance. The results showed that the high-molecular-weight components decreased while the low-molecular-weight components increased when bayberry was subjected to sp. biodegradation; furthermore, the molecular weight of the biodegraded bayberry tannin decreased from 3371 to 2658 Da. Meanwhile, the structure of bayberry tannin polyflavonoids, especially A ring and C ring together with the galloyl group, was destroyed and some small fragments were generated during biodegradation. These structural changes resulted in the increase of low-molecular-weight phenols but the decrease of polyflavonoids after bayberry biodegradation. These would be the pieces of evidence showing that sp. consumed simple phenols as nourishment for growth and converted polyflavonoids into low-molecular-weight substances at the same time. To sum up, biodegradation can be used in every field where condensed tannins should be degraded or removed for a cleaner and ecofriendly routine.
化学降解被广泛用于生产低分子量单宁化合物和处理单宁，但它对环境有负面影响，如造成二次污染和消耗能源。为克服这些缺点，通过生物降解开发了一种更清洁、可持续的缩合单宁降解和处理方法。在本研究中，首先用 菌对杨梅单宁溶液（一种缩合单宁）进行生物降解；然后，使用凝胶渗透色谱和高效液相色谱分离生物降解后的单宁和原始单宁，以分析成分差异；最后，通过基质辅助激光解吸/电离飞行时间质谱和核磁共振对生物降解后单宁结构的变化进行表征。结果表明，杨梅经 菌生物降解后，高分子量成分减少，低分子量成分增加；此外，生物降解后的杨梅单宁分子量从3371 Da降至2658 Da。同时，杨梅单宁多黄酮的结构，尤其是A环和C环以及没食子酰基，在生物降解过程中被破坏，并产生了一些小片段。这些结构变化导致杨梅生物降解后低分子量酚类增加，但多黄酮减少。这些将是 菌以简单酚类为生长营养并同时将多黄酮转化为低分子量物质的证据。综上所述，生物降解可用于缩合单宁需要降解或去除的各个领域，以实现更清洁、环保的流程。
