ACCUMULATION OF TRICHOTHECENES IN LIQUID CULTURES OF A FUSARIUM SPOROTRICHIOIDES MUTANT LACKING A FUNCTIONAL TRICHOTHECENE C-15 HYDROXYLASE

A mutant strain of Fusarium sporotrichioides NRRL 3299 produced by dis ruption of Tri11, a gene encoding a cytochrome P-450 monooxygenase, wa s shown to be altered in its ability to biosynthesize T-2 toxin. This mutant strain produced four trichothecenes that were not observed in c ultures of the parent strain. The compounds were identified as isotric hodermin, 8-hydroxyisotrichodermin, 8-hydroxyisotrichodermol, and 3,4, 8-trihydroxytricothecene on the basis of their nuclear magnetic resona nce and mass spectra. This is the first report of these 8-hydroxytrich othecenes as metabolites of F. sporotrichioides. The accumulation of i sotrichodermin and the results of whole-cell feeding experiments with a Tri11(-) strain confirm that oxygenation of C-15 is blocked.