MATTHIAS DONNER, SEBASTIAN KIEWNICK, RICHARD A. SIKORA
University of Bonn, Institute for Plant Diseases, Phytopathology and Nematology in Soil Ecosystems, Germany
Aflatoxins are toxic compounds produced by the fungus Aspergillus flavus which infects corn. It thrives in warm and humid areas of tropical Africa where corn is grown and stored. Aflatoxins are mutagenic, carcinogenic, teratogenic and acutely toxic to animals and humans. It is known to cause liver cancer. Their chronic and long-term effects on humans exposed to low doses over time are not well understood.
Earlier studies by researchers from IITA and the University of Leeds showed a strong association between blood aflatoxin levels and stunted growth in young West African children. Stored grain in the studied areas often had much higher levels of aflatoxin than the currently accepted safe limit of 20 ppb. As a result, 99% of the children examined in these areas had aflatoxin in their blood.
A new research project, funded by the German Development Agency (BMZ), will exploit an innovative biological control strategy called ``Competitive Exclusion'' to minimise the contamination of crops by aflatoxin. The goal is to introduce and establish an atoxigenic strain that does not produce any toxins in order to replace the strains of Aspergillus flavus that cause contamination of the food basket with aflatoxin. Potentially atoxigenic strains of Aspergillus flavus have been isolated in various regions of West Africa. The atoxigenic nature of these isolates is presently being investigated at the Institute for Plant Diseases, University of Bonn. The capability to produce aflatoxin in liquid fermentation will be evaluated by using TLC. In addition, vegetative compatibility group (VCG) testing has been initiated with these isolates to determine relative natural dominance, competitive displacement, survival, dispersal and safety issues.
Keywords: Aflatoxin, Aspergillus flavus, atoxigenic