High Trap Formation and Low Metabolite Production by Disruption of the Polyketide Synthase Gene Involved in the Biosynthesis of Arthrosporols from Nematode-Trapping Fungus Arthrobotrys oligospora.

A group of morphology regulatory arthrosporol metabolites have been recently characterized from carnivorous fungus Arthrobotrys oligospora that can develop trapping networks to capture their prey. A combination of genetic manipulation and chemical analyses was applied to characterize the function of one polyketide synthase (PKS) gene AOL_s00215g283 in A. oligospora, which was putatively involved in the production of 6-methylsalicylic acid. High-performance liquid chromatography analysis showed that the disruption of the PKS gene not only led to the total loss of the arthrosporol A but also resulted in significant reduction in the production of secondary metabolites in the cultural broth of the mutant ΔAOL_s00215g283 strain. Interestingly, the mutant strain displayed significant increases in the trap formation and the nematicidal activity by 10 and 2 times, respectively, higher than the wild-type strain. These findings revealed a pathogenicity-related biosynthetic gene of this agriculturally important biological agent and have implications for establishment of efficient fungal biocontrol agents.