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Abstract: The filamentous fungi Aspergillus parasiticus and Aspergillus flavus synthesize aflatoxins when they grow on a variety of susceptible food and feed crops. These mycotoxins are among the most carcinogenic naturally occurring compounds known and they pose significant health risks to humans and animals. We previously demonstrated that ethylene and CO2 act alone and together to reduce aflatoxin synthesis by A. parasiticus grown on laboratory media. To demonstrate the potential efficacy of treatment of stored seeds and grains with these gases, we tested ethylene and CO2 for ability to inhibit aflatoxin accumulation on Georgia Green peanuts stored for up to 5 days. We demonstrated an inverse relationship between A. parasiticus spore inoculum size and the level of toxin accumulation. We showed that ethylene inhibits aflatoxin synthesis in a dose-dependent manner on peanuts; CO2 also inhibits aflatoxin synthesis over a narrow dose range. Treatments had no discernable effect on mold growth. These observations support further exploration of this technology to reduce aflatoxin contamination of susceptible crops in the field and during storage. [Copyright &y& Elsevier]

Ethylene, a biologically active natural compound, inhibited aflatoxin accumulation by Aspergillus parasiticus on a solid growth medium in a dose-dependent manner at concentrations of 0.1 to 150 ppm. The activity of the nor-1 promoter (an early aflatoxin gene) was reduced to nondetectable levels by similar quantities of ethylene, suggesting that the inhibitory effect on toxin synthesis occurred, at least in part, at the level of transcription. The inhibitory effect of ethylene on aflatoxin accumulation was also observed when A. parasiticus was grown on raw peanuts. Under similar growth conditions and doses, ethylene strongly inhibited development of asci and ascospores in Aspergillus nidulans, with no detectable effect on Hülle cell formation, conidiation, or sterigmatocystin accumulation. During early growth, A. parasiticus and A. nidulans produced ethylene with approximately twofold higher quantities measured in continuous light than in the dark. 1-Methylcyclopropene (an inhibitor of ethylene receptors in plants), light, CO2, temperature, and growth medium composition altered the effect of ethylene on A. nidulans and A. parasiticus. These observations are consistent with the existence of an ethylene sensor molecule that mediates the function of an ethylene-responsive signaling pathway(s) in Aspergillus. [ABSTRACT FROM AUTHOR]