PUB - Publikationen an der Universität Bielefeld

Surface sterilisation of plant material from various host species and tissue types, collected from different habitats, with subsequent cultivation of the arising fungal mycelia as axenic cultures resulted in the isolation of 55 fungal endophytes. The strains were identified via nrITS-DNA (ITS-barcoding). A broad taxonomical distribution within these strains was ob- served with a focus on ascomycotous fungi and an emphasis on members of the Sordari- omycetes und Dothideomycetes classes. Some of the cultivated fungal strains showed low sequence identity to the reference species in the databases. Therefore they were recognized as potential new or underexplored species.
Antibacterial and cytotoxic activities were observed in crude extracts of ethyl acetate after cultivation through solid-state-fermentation on rice. Due to phylogenetic considerations and bioactive properties five strains, were chosen for a detailed mycochemical investigation, _Pur- pureocillium lilacinum_ (T26B), _Xylaria cubensis_ (TS7), _Daldinia_ sp. (SG1), Didymosphaeriaceae sp. (SG8c, cf. _Tremateia_ sp.), _Biscogniauxia_ sp. (SG25).
These mycochemical investigation of endophytic fungal crude extracts resulted in the isola- tion, identification and characterisation of nine new, previously undescribed and 55 already literature known compounds. The new described molecules were comprised of three dep- sidones (Tremateiasidon A - C), one depside (Tremateiasid A), one pyranocoumarin (Trema- teiajulin A) with an unusual molecular scaffold, one monosulfated diketopiperazine ( 3_S_-Norgliovictin), one quinone (Tremaquin A) und one isochromane (Tremachroman), as well as a butenolide (Lilacinolid A). Some of the new molecules show strong antibacterial activity, comparable or exceeding the potency of the reference drug (Gentamicin). The previ- ously published metabolites, some of which were ascertained in their respective fungal spe- cies or genera for the first time, represent different compound classes (depsidones, isocou- marines, cytochalasines, linear, non-ribosomal peptides, cyclic depsipeptides, butenolides, lipids, etc.), which underlined the biosynthetic potential of endophytic fungi. In addition, vari- ous fractions and pure isolated compounds showed bioactive properties. These mycochemi- cal investigations were able to prove that endophytic fungi are a good source for new and bioactive natural products.