Factors related to aflatoxin biosynthesis.

Lipoperoxidation was previously found by us to play a key role In inducing aflatoxin biosynthesis. 'In vitro', the production of aflatoxins is strongly enhanced by the addition of hydroperoxides, epoxides, UV-peroxidated sterols and halomethanes, which induce Lipoperoxidation within the f'ungi . 'In VIVO', on varzous oily and starchy seeds, we found that the biosynthesis of aflatoxins was directly related to the peroxide number of the oil content of the seeds. Since it has been shown that lipoperoxidation is affected by the presence of antioxidants and free radical scavengers in the environment, this investigation was undertaken to examine the effect of some common antioxidants at different concentrations on aflatoxin production induced by the addition of carbon tetrachloride in cultures of Aspergillus parasiticus. Butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), cysteamine and sodium thiosulfate (TIO) significantly inhibited the aflatoxin output, but cysteine, reduced glutathione, vitarmin C and vitamin E greatly enhanced mycotoxin production induced by carbon tetrachloride. Studies with mutant strains of Aspergillus parasiticus and A. flavus demonstrated that the phenomenon of lipoperoxidation affects not only the aflatoxin biosynthesis but also concerns their precursors. Norsolorinic acid, averufin, averantin, versicolorin A and sterigmatocystin. In addition, the biosynthesis of these congeners is inhibited by the addition of BHA, BHT, TIO and cysteamine to culture media.