Production of zearalenone in vitro and in corn grains stored under modified atmospheres

Abstract The production of zearalenone by an isolate of Fusarium equiseti was studied in chemically defined medium and in corn grains stored under modified atmospheres. An increase in the concentrations of sucrose or xylose in Czapek's medium resulted in increased toxin production, while no toxin was produced when lactose was present in the medium. Methionine (10 −2 and 10 −3 M) and cystine (10 −3 M) added to Czapek's medium inhibited zearalenone production. When amino acids or nitrogen salts were added as the sole nitrogen source, only alanine, tryptophan and NH 4 Cl totally inhibited zearalenone production. Zearalenone production was inhibited almost completely in high-moisture corn grains (27%) kept under atmospheres enriched with high CO 2 levels (60%, 40% or 20%) with either 20% or 5% O 2 . However, a lower amount of CO 2 was needed to inhibit fungal development and toxin formation when a reduced O 2 level was applied.