SYNTHESIS OF AFLATOXINS AND THEIR PRECURSORS IN FEEDS CONTAMINATED WITH TOXINOGENIC MOLD CULTURES

To assess the ability for toxin production (sterigmatocystin (STC), O- methylsterigmatocystin (OMSTC), aflatoxin B-1 (AFB(1)) of Aspergillus versicolor and A. parasiticus species on 3 different types of stockfee d for dairy cattle, the strains were precultivated on Czapek's medium and malt wort agar. From the above mentioned toxins, AFB(1) was produc ed by either species on either medium. STC was not produced by A. para siticus grown on malt wort agar, and OMSTC was only produced by A. par asiticus on both media. The stockfeed samples were each inoculated wit h 1 mi of spore suspension and incubated at 35 degrees C at about 97-9 9% relative humidity and analyzed for toxins after 1-2 weeks. The toxi n production depends on the type of precultivation and feed. STC was p referably produced by A. versicolor on mixed feed samples, whereas OMS TC and AFB(1) were produced in high amounts on wheat grain by both spe cies, merely regardless the precultivation.