A combined chemical and biological approach towards generating fungal herbicide analogs
Cornexistin is an interesting natural product, belonging to the family of nonadrides – compounds comprising a nine carbon ring and maleic anhydride moiety. It is a potent herbicide produced bythe fungal species Paecilomyces variotii. However, this secondary metabolite of polyketide origin is produced by the native strain at a very low titre and the detailed mechanism of its biosynthesis remains unclear.
The main objectives of the project are: to intensify the production of cornexistin by genetic modifications of the producing strain and to isolate other nonadride and cornexistin-related compounds with enhanced herbicidal properties. The main techniques employed are analytical and preparative LC-MS and NMR for structure elucidation of isolated metabolites. The P. variotii-related species, Byssochlamys fulva, is studied in the project in parallel, as it is producing byssochlamic acid – a structurally similar nonadride.