Effect of Cycling Temperatures on the Production of Deoxynivalenol and Zearalenone by Fusarium graminearum NRRL 5883†

Abstract

The effects of three regimens of cycling incubation temperatures and incubation at constant 25°C on the growth of Fusarium graminearum NRRL 5883 and production of deoxynivalenol (DON) and zearalenone (ZEN) on rice were compared. The effects of low-temperature stress were also studied by incubating rice cultures at a constant 15°C for 4 weeks following incubation at constant 25°C for 2 weeks. Both incubation temperature and time significantly (P ≤ 0.05) affected growth of F. graminearum NRRL 5883 and production of DON and ZEN. The highest amount of free ergosterol (640 μg/g culture material) that was used as a measure of fungal growth was found in cultures incubated at temperatures cycling between 15 and 30°C during a 6-week period. The highest amounts of DON (1,679 μg/g culture material) and ZEN (603 μg/g culture material) were produced in cultures incubated at a constant 25°C for 2 weeks prior to incubation at a constant 15°C for an additional 4 weeks. Under cycling incubation temperatures, maximum amounts of DON (850 μg/g culture material) and ZEN (98 μg/g culture material) were produced in cultures incubated at temperatures cycling between 15 and 30°C for 6 weeks. Overall, there was no correlation between mold growth and production of either DON or ZEN. However, DON production and ZEN production were correlated.