Trichoderma brevicompactum complex: Rich source of novel and recurrent plant-protective polypeptide antibiotics (peptaibiotics)

Three strains of Trichoderma brevicompactum and another four that are closely related to that species (Trichoderma cf. brevicompactum) were analyzed for the formation of polypeptide antibiotics (peptaibiotics) by LC/ESI-MS(n). These isolates were selected because of an antagonistic potential against Eutypa dieback and Esca disease of grapevine and have not yet been investigated for the production of peptide antibiotics. Fully grown cultures on potato dextrose agar were extracted with CH2Cl2/MeOH, and this extract was subjected to SPE using C18 cartridges. The methanolic eluates were analyzed by LC/ESI-MS(n). All strains were found to produce membrane-active alamethicins F30. In addition to that, novel peptaibiotics were detected, namely, 14 12-residue trichocryptins B, 12 11-residue trichocryptins A, 19 11-residue trichobrevins A and B, 6 10-residue trichoferins, and 17 8-residue trichocompactins. These compounds may partially be responsible for the plant-protective action of the producers. Chemotaxonomic considerations also indicated the necessity to introduce another new species that is closely related to T. brevicompactum.