[Investigation and evaluation of fumonisin contamination of native and imported cereals]

Do fumonisin mycotoxins occur in wheat?

The fumonisin mycotoxins are mainly produced by the fungi Fusarium verticillioides and Fusarium proliferatum, which are both field pathogens of maize. The natural occurrence of fumonisins has been verified in maize and a large range of maize-based products in many countries of the world. However, occasional reports have emerged of fumonisins being detected in wheat, despite the main producing fungi not being pathogens of this cereal. An investigation was conducted into a recent report of the natural occurrence of fumonisins in the 2003/2004 South African wheat crop at levels up to 1.7 mg/kg, as determined by immunoaffinity column cleanup and direct fluorometric measurement. An AOAC International high-performance liquid chromatographic (HPLC) method for the determination of fumonisins in maize was modified and validated for the determination of fumonisins in spiked wheat samples. HPLC analysis of the wheat samples previously found to be positive for fumonisins revealed no detectable (<5 microg/kg) fumonisins in the 30 samples analyzed. These results, which lay doubt on previous reports of fumonisins in wheat, emphasize the fact that screening methods, especially if used outside their range or matrix of applicability, can produce false positive results despite the use of immunoaffinity cleanup. Such results should be validated and confirmed with a more definitive technique.

Fumonisin-producing strains of Fusarium: a review of their ecophysiology

This review focuses on the fumonisin-producing Fusarium species and the ecophysiology of these species. The effects of environmental biotic and abiotic factors on germination, growth, and fumonisin B1 production by Fusarium verticillioides and Fusarium proliferatum have been investigated under laboratory, field, and storage conditions. An understanding of the factors involved in production of fumonisins is the first step in preventing accumulation of these toxins.