Abstract
Zearalenone is a mycotoxin with estrogenic effects on mammals that is produced by several species of Fusarium. We found that zearalenone and its derivatives inhibit the growth of filamentous fungi on solid media at concentrations of < or =10 microg/ml. The fungitoxic effect declined in the order zearalenone > alpha-zearalenol > beta-zearalenol. The mycoparasitic fungus Gliocladium roseum produces a zearalenone-specific lactonase which catalyzes the hydrolysis of zearalenone, followed by a spontaneous decarboxylation. The growth of G. roseum was not inhibited by zearalenone, and the lactonase may protect G. roseum from the toxic effects of this mycotoxin. We inactivated zes2, the gene encoding zearalenone lactonase in G. roseum, by inserting a hygromycin resistance cassette into the coding sequence of the gene by means of Agrobacterium tumefaciens-mediated genetic transformation. The zes2 disruption mutants could not hydrolyze the lactone bond of zearalenone and were more sensitive to zearalenone. These data are consistent with a hypothesis that resorcylic acid lactones exemplified by zearalenone act to reduce growth competition by preventing competing fungi from colonizing substrates occupied by zearalenone producers and suggest that they may play a role in fungal defense against mycoparasites.
Highlights
IntroductionZearalenone [6-(10-hydroxy-6-oxo-trans-1-undecenyil)-resorcylic acid lactone] is a mycotoxin produced by several species of Fusarium, most notably Fusarium graminearum and Fusarium culmorum
Zearalenone is a mycotoxin with estrogenic effects on mammals that is produced by several species of Fusarium
Zearalenone [6-(10-hydroxy-6-oxo-trans-1-undecenyil)-resorcylic acid lactone] is a mycotoxin produced by several species of Fusarium, most notably Fusarium graminearum and Fusarium culmorum
Summary
Zearalenone [6-(10-hydroxy-6-oxo-trans-1-undecenyil)-resorcylic acid lactone] is a mycotoxin produced by several species of Fusarium, most notably Fusarium graminearum and Fusarium culmorum. There are no published laboratory data demonstrating the hydrolysis of zearalenone by Mycofix Plus or by its active component, and such activity was not detected by us [21]. The recently discovered yeast species Trichosporon mycotoxinivorans [27] degrades zearalenone and is expected to provide future versions of Mycofix Plus with genuine zearalenone-hydrolyzing activity. Another fungus with proven zearalenone-degrading activity is Gliocladium roseum [8], and a zearalenone lactonase gene has been cloned from this mycoparasite by two research groups We suggest a biological function for zearalenone production and an ecological role for this fungal metabolite in a nonagricultural setting
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