Nematode-trapping fungi are natural antagonists of nematodes. These predatory fungi are capable of switching their lifestyle from a saprophytic to predatory stage in the presence of nematodes by developing specialized trapping devices to capture and consume nematodes. The biochemical mechanisms of such predator–prey interaction have become increasingly studied given the potential application of nematode-trapping fungi as biocontrol agents, but the involved fungal metabolites remain underexplored. Here, we report a comprehensive liquid–chromatography mass spectrometry (LC–MS) metabolomics study on one hundred wild isolates of nematode-trapping fungi in three different species, Arthrobotrys oligospora, Arthrobotrys thaumasia, and Arthrobotrys musiformis. Molecular networking analysis revealed that the fungi were capable of producing thousands of metabolites, and such chemical diversity of metabolites was notably increased as the fungi switched lifestyle to the predatory stage. Structural annotations by tandem mass spectrometry revealed that those fungal metabolites belonged to various structural families, such as peptide, siderophore, fatty alcohol, and fatty acid amide, and their production exhibited species specificity. Several small peptides (<1.5 kDa) produced by A. musiformis in the predatory stage were found, with their partial amino acid sequences resolved by the tandem mass spectra. Four fungal metabolites (desferriferrichrome, linoleyl alcohol, nonadecanamide, and citicoline) that were significantly enriched in the predatory stage were identified and validated by chemical standards, and their bioactivities against nematode prey were assessed. The availability of the metabolomics datasets will facilitate comparative studies on the metabolites of nematode-trapping fungi in the future.

中文翻译：

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捕食线虫的真菌在食肉动物与猎物相互作用期间产生多种代谢产物

捕获线虫的真菌是线虫的天然拮抗剂。这些捕食性真菌能够通过开发专门的诱捕装置来捕获和食用线虫，从而在存在线虫的情况下将其生活方式从腐生性转变为捕食性。考虑到捕食线虫的真菌作为生物防治剂的潜在应用，这种捕食者与猎物之间相互作用的生化机制已得到越来越多的研究，但所涉及的真菌代谢物仍未得到充分研究。在这里，我们报道了一种综合液相色谱质谱（LC-MS）代谢组学研究，研究了三种不同物种，节肢动物 寡头孢菌，奇异型关节炎动物和多形节肢动物中捕获线虫的一百种野生菌株。。分子网络分析表明，真菌能够产生数千种代谢产物，并且随着真菌将生活方式转变为掠夺性阶段，代谢产物的这种化学多样性显着增加。串联质谱的结构注释表明，那些真菌代谢产物属于各种结构家族，例如肽，铁载体，脂肪醇和脂肪酸酰胺，并且它们的产生表现出物种特异性。通过产生几个小肽（<1.5 kDa的）A. musiformis在捕食阶段被发现，其部分氨基酸序列通过串联质谱解析。通过化学标准品鉴定并验证了在捕食阶段显着富集的四种真菌代谢物（去铁基铬，亚油醇，壬二酰胺和胞二磷胆碱），并评估了它们对线虫猎物的生物活性。代谢组学数据集的可用性将有助于将来对捕杀线虫真菌的代谢物进行比较研究。