Peptaibiomics: Screening for polypeptide antibiotics (peptaibiotics) from plant-protective Trichoderma species

Abstract

Eight strains of Trichoderma species (T. strigosum, T. erinaceus, T. pubescens, T. stromaticum, and T. spirale as well as T. cf. strigosum, T. cf. pubescens) were selected because of their antagonistic potential against Eutypa dieback and Esca which are fungal diseases of grapevine trunks. These isolates were screened for the production of a group of polypeptide antibiotics named peptaibiotics, including its subgroups peptaibols and lipopeptaibols. Fully-grown fungal cultures on potato-dextrose agar were extracted with CH 2Cl 2/MeOH, and these extracts were subjected to SPE using C 18 cartridges. The methanolic eluates were analyzed by on-line LC/ESI-MS n coupling - a method which is referred to as 'peptaibiomics'. New seven-, ten-, and eleven-residue lipopeptaibols, with N-terminal alkanoyl, and C-terminal leucinol or isoleucinol residues were found and named lipostrigocins and lipopubescins. Furthermore, new 18-residue peptaibols named trichostromaticins and 19-residue peptaibols named trichostrigocins were discovered. One peptaibiotic carrying a free C-terminal valine (or isovaline) named trichocompactin XII was also sequenced. These results corroborate the hypothesis that peptaibiotics might contribute to the plant-protective action of their fungal producers. The data also point out that comparison of peptaibiotic sequences is of limited relevance in order to establish chemotaxonomic relationships among species of the genus Trichoderma. © 2006 Verlag Helvetica Chimica Acta AG, Zürich.