土壤细菌Paracoccus sp. D72与Devosia sp. D73协同降解呕吐毒素的机制研究

Deoxynivalenol (DON) is a notorious mycotoxin in grains and causes severe safety risks to human health. Biodegradation is an efficient measure to deal with DON contamination. In previous studies, we found a cooperative effect in the biodegradation of DON by two soil bacteria, Paracoccus sp. D72 and Devosia sp. D73. When DON was treated with combined strains, the degradation rate was eight times higher compared with those catalyzed by either single strain. We hypothesized there was either co-catalytic or cascade-catalytic effect in the synergistic biodegradation. By combined use of metabolomic methods, we plan to figure out the chemical pathways in DON degradation and explore the characteristics in synergistic biodegradation. Then, we intend to find out the corresponding enzymes by searching the whole genomes of these two strains and in vitro catalysis. Finally, the synergistic mechanisms will by revealed by measuring the enzymatic kinetic parameters and comprehensive analysis of the degradation routes of each enzyme. The result of this study will provide solid evidence for the mycotoxin biodegradation and technical aid for controlling DON contamination.

呕吐毒素是我国小麦等谷物中污染最为严重的真菌毒素，生物降解具有很好的解毒作用，但到目前为止呕吐毒素的降解菌资源非常有限，研究其降解机制具有重要意义。申请人在前期研究中分离获得两株对呕吐毒素具有协同降解作用的细菌Paracoccus sp. D72与Devosia sp. D73，当两株细菌协同作用时其降解效率为单一菌株的8倍以上，推测其协同机制包括降解酶的协同催化或级联催化效应。针对这一假设，本项目拟采用代谢组学手段检测菌株单独降解及协同降解过程中毒素降解产物，探寻降解化学过程的差异；结合菌株基因组或蛋白谱信息寻找可能的降解酶，通过基因敲除与外源表达方式验证酶功能；利用降解酶对呕吐毒素进行联合降解实验，根据降解酶动力学特征确证其协同作用类型。预期研究结果将从化学、基因及酶学角度阐明菌株对呕吐毒素的协同降解机制，为真菌毒素的协同降解机制研究和毒素污染防控治理提供理论依据，并具广泛的应用前景。

呕吐毒素是我国小麦等谷物中污染最为严重的真菌毒素，开发高效便捷的毒素脱毒方法并探讨脱毒机制对于保障我国谷物及其制品的食品安全意义重大。本项目在执行过程中考察了两株土壤微生物Paracoccus sp. D72与Devosia sp. D73协同降解DON的作用机制，解析了降解过程化学途径；筛选并获得了负责DON降解的相关降解酶；并最终阐明了两株菌株对DON降解的协同作用机制。项目严格按照管理规定和经费预算实施，完成了全部研究内容和相关指标，以第一作者或通讯作者发布项目标注论文7篇，其中SCI论文6篇，申请国家发明专利2件，培养硕士研究生2名。