基于种间相互作用增加海藻内生真菌次级代谢化学多样性及其抗海洋弧菌活性研究

Marine alga-derived fungi formed a mutually beneficial symbiosis relationship with their hosts due to long-term co-evolution, which also led to a special secondary metabolic mechanism of those fungi. It is of significance to study the secondary metabolites of marine symbiotic fungi for developing antibiotics with novel structure and new therapeutic mechanism. Utilizing fungal intermicrobial interaction, such as antagonism and competition, we could activate the silent biosynthetic pathway of secondary metabolism, thus regulating the secondary metabolism of marine fungi. It was found in preliminary research that alga-derived fungi Trichoderma atroviride EN-543 and Aspergillus wentii EN-48 could produce structurally abundant and biologically active secondary metabolites, which are worthy to be further investigated. Genome analysis showed that, in these two stains of fungi, there are many silent secondary metabolism gene clusters, which can't express in conventional cultivation. Further screening research showed that co-culture have a marked impact on the secondary metabolism of both fungi and their bioactivities. Based on previous studies, this project focuses on marine fungi EN-543 and EN-48, aims to use co-culture elicitation strategy for activating potential silent metabolic pathways in marine fungi. With chemical diversity of secondary metabolites and anti-aquatic pathogenic microbial activities being taken as evaluation indexes, we intend to explore new bioactive molecules with potential value in application, providing the material basis for the development of characteristic marine drugs. Meanwhile, by analyzing the effects of co-culture elicitation on multi-omics and so on, we would attempt to speculate the metabolic modulation mechanism and preliminarily discuss the fungal intermicrobial interaction.

长期的协同进化使得海藻内生真菌与其宿主之间形成了互惠互利的共生关系，获得了独特的代谢机制，其次级代谢产物的研究对开发具有新结构和新作用机理的抗生素有着重要意义。利用真菌间拮抗和竞争等相互作用，可以激活其沉默生物合成途径，实现对其次级代谢的调控。我们在前期研究发现，海藻内生真菌深绿木霉EN-543和温特曲霉EN-48代谢产物丰富、生物活性显著，有深入研究价值。基因组分析表明这两株菌中还有许多常规培养时未表达的次级代谢沉默基因簇。进一步筛选发现，共培养能够对这两株真菌的次级代谢产物及其抗海洋弧菌活性产生显著影响。本项目拟在此基础上通过共培养诱导策略，深入挖掘两株真菌的生物合成潜力，以次级代谢化学多样性和抗海洋弧菌活性为评价指标，发现具有潜在应用价值的新结构活性分子，为特色海洋天然产物的开发提供物质基础，结合组学分析等手段探讨共培养对真菌次级代谢调控机制，初步阐明海藻内生真菌之间的相互作用关系。

在海洋环境中，海洋真菌与其他海洋生物普遍存在共生现象。越来越多的证据显示，许多从海洋生物中发现的次级代谢产物的真正生产者是其共生真菌。长期的协同进化使得海藻内生真菌与其宿主之间形成了互惠互利的共生关系，获得了独特的代谢机制，其次级代谢产物的研究对开发具有新结构和新作用机理的抗生素有着重要意义。这些海洋真菌是新的海洋生物活性物质的重要来源，在医药等领域已日益凸现其广阔的应用前景。本项目利用海藻内生真菌单培养和共培养发酵优化策略，激活次级代谢产物生物合成的沉默基因，从单培养和共培养发酵产物中共分离鉴定化合物33个，包括倍半萜类、二萜类、降二萜类等，其中新化合物10个。从温特曲霉中发现了一系列在酸性条件下发生互变异构的差向异构体，并分析解释其在酸诱导条件下的互变异构机理。此外，建立了甲基化衍生法，用于鉴定温特曲霉蒽醌类、氧杂蒽酮类特征代谢产物。对分离获得的化合物进行抗水产病害菌活性测试，其中化合物c1、c2、17、23表现出显著的抑制水产病害菌抑制活性。通过本项目的实施，充分挖掘了海藻内生真菌深绿木霉和温特曲霉新颖天然产物的生物合成潜力，发现了具有潜在应用前景的新结构抗菌活性天然产物，为发展新型水产病害菌抗生素提供了物质基础。