Exploring natural products from nematode-associated fungi of the order Pleosporales

Presentation by Natalia Andrea Llanos Lopez, Janette Miled, Marc Stadler, Mark Njogu Kimani, Samad Ashrafi, Wolfgang Maier. Abstract The rapid global spread of drug-resistant pathogens, including bacteria, fungi, and nematodes,has become a significant problem that requires study from multiple perspectives. Newstrategies are needed to control diseases that negatively impact health and food crops. Naturalproducts from fungi have been proposed as alternatives to help mitigate the spread ofinfectious diseases. Among them, secondary metabolites from nematode-associated fungihave received little attention and remain largely unexplored. To evaluate the antimicrobial andnematicidal activities of secondary metabolites produced by fungi associated with nematodecysts of wheat and sugar beet (Heterodera spp.), 20 previously isolated fungal strains from theorder Pleosporales were studied in different culture media. Three strains of Polydomuskarssenii, two strains from the genus Murispora, and four strains from an unknown genus wereselected for further purification of the secondary metabolites. The extracts were analyzedthrough liquid chromatography-mass spectrometry (LC-MS) and UV detection at 210 nm. Afterfermentation of the fungal strains, the resulting extracts were fractionated primarily bypreparative reversed-phase high-performance liquid chromatography (RP-HPLC). Sixty-fivecompounds were isolated and tested for nematicidal and antimicrobial activities. Among theisolated compounds were cyclodepsipeptides, tetramic acids, sesquiterpenoids,anthraquinones, macrolides, and glycerolipids. This research led to the identification ofpromising molecules that could serve as biocontrol agents against nematodes and microbesaffecting human health and agriculture.