Four out of nine North American Fusarium graminearum isolates produced deoxynivalenol (DON) and 15-monoacetyl deoxynivalenol (15-ADON) when grown in stationary cultures of modified Fries medium supplemented with 4% corn steep liquor. Strains R-6576, Van Wert A-l and Stuckey produced primarily DON after 20 d of incubation at 28°C. In these strains, low levels of 15-ADON accumulated after 5 d but then declined over time. Disappearance of 15-ADON and subsequent appearance of DON coincided with both a rapid rise of pH above 8.0 and onset of the stationary phase. DON levels peaked after the exhaustion of carbohydrate (day 20) and then began to decline. In contrast to these three strains, strain NRRL 5883 produced primarily 15-ADON during an extended growth phase (day 10) and only small amounts of DON during late stationary phase (day 25). NRRL 5883 exhibited a slow rise in pH relative to the other three strains and utilized only 75% of the available carbohydrate during the 25-d period. Qualitative and quantitative production of DON and 15-ADON in liquid culture was dependent on the strain of F. graminearum.
1Department of Food Science and Human Nutrition.
2Department of Botany and Plant Pathology.