Combining OSMAC, Metabolomic and Genomic Methods on Termite Symbiotic Fungi for the Production and Annotation of Halogenated Azaphilones and Ilicicolins

Abstract

We mined a collection of termite mutualistic strains from French Guiana to explore metabolites of symbiotic microorganisms. Molecular networks reconstructed from a metabolomic analysis using LC-ESI-MS/MS methodology led us to identify two families of chlorinated polyketides, i.e. azaphilones from Penicillium sclerotiorum and ilicolins from Neonectria discophora. To define the biosynthetic pathways related to these two types of scaffolds, we used a whole genome sequencing approach followed by hybrid assembly from short and long reads. We found two biosynthetic gene clusters including two FAD-dependent halogenases. To exploit the enzymatic promiscuity of the two identified FAD halogenases, we sought to biosynthesize novel halogenated metabolites. An OSMAC strategy was used and resulted in the production of brominated analogs of ilicicolins and azaphilones as well as iodinated analogs of azaphilones.