Mycotoxin production in wheat grains by different Aspergilli in relation to different relative humidities and storage periods

Four different Aspergilli (Aspergillus oryzae, A. parasiticus, A. terreus and A. versicolor ) were grown on wheat grains under different degrees of relative humidity 14, 50, 74, 80 and 90%. Samples of wheat grains were taken monthly for a period of six months and examined for mycotoxin production. A. oryzae was found to produce aflatoxins B 1 , B 2 , zearalenone, DON and T‐2 toxins under elevated degrees of humidity and prolonged periods of storage. A. parasiticus produced aflatoxins B 1 , G 1 , NIV, DON and T‐2 toxins in high concentrations during a period of not more than three months storage at 14% relative humidity; at an increased level of relative humidity of 74% ochratoxin A, zearalenone and sterigmatocystin were also produced at high levels. The isolate was drastic in toxin production. A. terreus produced toxins at 14% relative humidity (aflatoxin G 2 and DON) at levels much higher than any other prevalent degrees of humidity. A. versicolor is highly sensitive to relative humidity and grain moisture content. It produced aflatoxins B 1 , G 1 , NIV and DON at a relative humidity of 50% and another toxins (aflatoxin G 2 , ochratoxins A, B and zearalenone) at 74%. The microorganism can be considered a trichothecene producer under suitable relative humidity.