Fungi that produce mycotoxins: Conditions and occurrence

The occurrence of mycotoxins, in agricultural commodities is a worldwide problem with almost all commodities being potentially susceptible to contamination under the proper conditions. The genera of fungi most implicated are Aspergillus, Penicillium and Fusarium, although the potential for toxin production varies considerably within any given species.Conditions that affect toxin production include fungal strain variation, genetic susceptibility of the host plant or commodity, moisture content, commodity composition, temperature, aeration, microbial population and stress factors. There is undoubtedly interaction between these factors so that laboratory studies involving limited variables can only, at best, approximate field conditions.Natural contamination with mycotoxins has been reported for most of the major agricultural commodities in the world including corn, wheat, rice, millet, barley, oats, sorghum, peanuts, beans, copra, some fruits and nuts and various forages; strangely, soybeans do not appear to be involved to any major extent. The major mycotoxins on commodities reported to date include aflatoxin, the trichothecenes, ochratoxin, citrinin, zearalenone, sporidesmins and some tremorgens. However, laboratory studies have shown that the fungi are capable of producing hundreds of toxic chemicals, most of which are not included in routine analyses. In addition, since toxin effects are often insidious and may go undetected, the true dimensions of the mycotoxin problem are unknown.