Deoxynivalenol, acetyl deoxynivalenol, and zearalenone formation by Canadian isolates of Fusarium graminearum on solid substrates

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Abstract
Three isolates of F. graminearum (DAOM 180377, 180378 and 180379) were screened for their ability to produce mycotoxins on the solid substrates corn and rice. They all produced deoxynivalenol and zearalenone on corn. On rice, only DAOM 180378 and 180379 produced significant amounts of these mycotoxins, with levels of deoxynivalenol being much higher than those of zearalenone. The effects of the initial moisture content before autoclaving, incubation temperature and time were studied with isolate DAOM 180378. At 19.5.degree. C the main product was zearalenone; at 27.degree. C, deoxynivalenol and zearalenone were formed. Higher incubation temperatures (28.degree. C) favored deoxynivalenol formation, the maximum amount being 515 ppm (515 .mu.g/g) formed after 24 days at an initial moisture content of 40%. The maximum level of zearalenone produced at the same temperature was 399 ppm, but an an initial moisture content of 35%. Other factors, such as pH, O2 and CO2 concentrations and size of the culture flask also appeared to affect the production of mycotoxins.