Mycoflora aflatoxigenic species and mycotoxins in freshly harvested corn (Zea mays L): A preliminary study

Grain mycoflora, occurrence of aflatoxigenic species and presence of mycotoxins (aflatoxins B-1, B-2, G(1) and G(2,,) zearalenone and ochratoxin A) were evaluated in samples of freshly harvested corn collected at different locations in the State of Sao Paulo, Brazil, during 1992. Invasion of grains by the potentially mycotoxigenic genera Fusarium and Penicillium was rather high. The genus Aspergillus was also isolated but at a lower frequency compared with the other two genera. The Aspergillus species detected were: A. versicolor, A. flavus, A. niger, A. alutaceus, A. wentii, Eurotium chevalieri, Eurotium rubrum, Eurotium amstelodami and Eurotium repens. Eight Penicillium species were recovered, namely: P.variabile, P. funiculosum, P. citrinum, P. pinophilum, P. brevicompactum, P. canescens, P. raistrikii and P. spinulosum. Four of the seventeen A. flavus isolates were found to be either B1 or B1, and B2 aflatoxin producers. Despite the presence of potentially toxigenic fungi, zearalenone ( produced by Fusarium spp.), aflatoxin (produced by A. glavus/A. parasiticus) acid ochratoxin A (produced by Aspergillus spp. and Penicillium spp.) were not detected in the grain samples. The occurrence of non-toxigenic strains, unfavorable field and environmental conditions, interactions between fungal species and resistant varieties of corn are some of the factors that, alone or in combination, may explain the absence of mycotoxins in corn harvested during 1992 in the State of Sao Paulo.