Microbial Transformation of Trichothecene Mycotoxins by Deoxynivalenol-producing Strains of Fusarium graminearum

Abstract

Deoxynivalenol-producing strains of Fusarium graminearum metabolized deoxynivalenol (DON) and such acetylated derivatives as 3-acetyldeoxynivalenol (3-Ac-DON), 15-acetyldeoxynivalenol (15-Ac-DON) and 3, 15-diacetyldeoxynivalenol (3, 15-Ac-DON) in rice cultures. Intact mycelia of the one type could deacetylate 3, 15-Ac-DON and 15-Ac-DON at the C-15 position to give 3-Ac-DON and DON, respectively, whereas those of the other type converted 3, 15-Ac-DON and 3-Ac-DON into 15-Ac-DON and DON, respectively. The similar results were obtained by using cell-free extracts of each type of F, graminearum. Mycelial enzymes involved in these deacetylations were considered to have different properties with respect to optimum pH, pH-stability and substrate specificity. Based upon these facts, it is proposed that DON-producing strains of F. graminearum could be classified into two types according to the trichothecene-deacetylating enzymes present in their mycelia.