多级联合筛选及表观遗传修饰策略下海洋真菌新颖抗青枯菌产物研究

海洋独特的水体环境赋予了栖息其中的海洋真菌能够产生结构新颖、活性多样的次级代谢产物，已成为抗细菌生物农药研发的新热点。青枯病是由青枯雷尔氏菌引起的一类十分严重的细菌性植物土传病害，目前尚无有效的防治药剂，亟需研发新型抗青枯病农药。我们在前期工作中筛选获得了一株海洋真菌Fusarium equiseti D39，其发酵粗提物具有显著的抗青枯菌活性，且次级代谢产物结构类型新颖。本项目拟在已有的工作基础上，采用bioassay-LCMS-NMR多级联合筛选及表观遗传修饰策略，提高活性新化合物的发现概率和效率。对目标菌株进行表观遗传修饰和发酵优化，运用多级联合筛选策略确定最优发酵条件；进而开展新颖抗菌活性化合物的分离鉴定和活性测定；对活性化合物进行结构修饰并系统分析构效关系；最后，初步探讨活性化合物的抗菌作用机制。本项工作可为新颖高效低毒抗青枯病农药的发现提供基础资料。

Marine fungi have been a hotspot for study of new antibacterial biopesticides, as they can produce secondary metabolites with novel structures and potential bioactivities endowed by the unique marine environment. Bacterial wilt is an important soil-borne disease on plants caused by Ralstonia solanacearum, and it is desiderate to develop new type of antibacterial pesticides toward bacterial wilt, as there are no very effective agents to control the disease. In our previous work, a marine-derived fungal strain, Fusarium equiseti D39, attracted our attention because the extract of the fungal culture showed obvious antibacterial activity against R. solanacearum, and the structures of the secondary metabolites were novel. In this research proposal, based on the exiting work, bioassay-LCMS-NMR multistage-combinatorial screening and epigenetic modification will be applied to improve the discovery probability and efficiency of the antibacterial new compounds. Epigenetic modification and fermentation optimization should be performed on the target strain, and multistage-combinatorial screening should be used to choose the optimal fermentation conditions with the selected modification agent. The secondary metabolites will be isolated and identified from the fermentation broth, and be evaluated for their antibacterial activity. The bioactive compounds will be modified by chemical methods in order to discuss their structure-activity relationships. The antibacterial mechanisms of bioactive compounds will be preliminary investigated at last. The above research will provide basic material for the discovery of new antibacterial pesticides toward bacterial wilt with high efficiency and low toxicity.