茶叶厌氧发酵中咖啡碱的降解途径研究

Degradation pathway of caffeine in tea anaerobic fermentation

目的探究茶叶厌氧发酵过程中咖啡碱的降解途径。方法本研究利用高效液相色谱仪检测茶叶厌氧发酵过程中咖啡碱含量的变化,结合对发酵中代谢组和微生物群落结构的分析,获得厌氧发酵过程中咖啡碱的降解产物以及作用咖啡碱降解的微生物群。结果经18 d发酵后,茶叶中咖啡碱含量由37.05 mg/g显著下降至5.91mg/g,腺嘌呤、次黄嘌呤、黄嘌呤、依他茶碱和羟基腺嘌呤含量显著上升,同时,92个细菌属和16个真菌属的丰度显著上升。以上结果表明咖啡碱的降解途径主要通过脱甲基化反应生成黄嘌呤,该反应的中间产物—茶碱,可能与三乙胺生成依他茶碱;细菌中芽孢杆菌(Bacillus)和赖氏菌(Leifsonia)等以及真菌赛博德林酵母菌(Cyberlindnera)、突脐蠕胞菌(Exserohilum)等可能是降解咖啡碱的关键微生物。结论厌氧发酵可以显著降低茶叶咖啡碱的含量,本研究结果可为低咖啡碱茶产品的研制提供参考。

Objective To investigate the the degradation pathway of caffeine during anaerobic fermentation of tea.Methods High performance liquid chromatography was used to detect the changes of caffeine during tea anaerobic fermentation.The metabolic and microbial community structures during fermentation were also analyzed to explore the degradation products of caffeine and the microbial communities that contribute to caffeine degradation.Results After 18 days of fermentation,the caffeine content in tea leaves decreased significantly from 37.05 mg/g to 5.91 mg/g,and the content of adenine,hypoxanthine,xanthine,etafylline and hydroxyadenine increased significantly.Meanwhile,the abundance of 92 bacterial genera and 16 fungal genera increased significantly.These results indicated that the degradation pathway of caffeine was mainly through demethylation to produce xanthine;theophylline,the intermediate product of the demethylation reaction,might form etafylline with triethylamine.Moreover,Bacillus,Leifsonia in bacteria and Cyberlindnera,Exserohilum in fungi might be the key microbiota for caffeine degradation.Conclusion The content of caffeine in tea can be significantly reduced by anaerobic fermentation,which will provide a reference for the development of low caffeine tea products.