ECOLOGICAL BASIS FOR AFLATOXIN REDUCTION THROUGH CROP MANAGEMENT AND BIOLOGICAL CONTROL
Location: Food and Feed Safety Research
Title: BIOCOMPETITIVE EXCLUSION OF AFLATOXIN PRODUCING FUNGI
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: July 31, 2006
Publication Date: October 1, 2006
Citation: Cotty, P.J., Mellon, J.E. 2006. Biocompetitive Exclusion of Aflatoxin Producing Fungi. In: Barug, D., Bhatnagar, D., van der Kamp, J. W., van Osenbruggen, W. A., Visonti, A., editors. The Mycotoxin Factbook. Wageningen, The Netherlands: Wageningen Academic Publishers. p. 179-192.
Interpretive Summary: Aflatoxins are toxic fungal metabolites that can inhibit human development, cause cancer and even induce death. The most important cause of aflatoxin contamination is the fungal species Aspergillus flavus. Some strains of A. flavus produce no aflatoxins and are called atoxigenic. Atoxigenic strains are being developed as biological agents for limiting aflatoxin contamination. Several types of management strategies are being developed based on atoxigenic strains. One of these utilizes atoxigenic strains to make relatively long-term changes to fungal communities in agricultural areas, and in so doing, reduce the vulnerability of all crops grown in that area to aflatoxin contamination. This type of biological control offers researchers and growers the potential to reduce the burden of aflatoxin contamination on the sustainability of agricultural enterprise in several regions of the United States.
Aflatoxins are highly toxic cancer causing Aspergillus metabolites that cause immune-system suppression, growth retardation, cancer and death in both humans and domestic animals. Aflatoxin-producing species have considerable intraspecific variability, and the species that causes most aflatoxin contamination of crops, Aspergillus flavus, varies widely in aflatoxin production with some strains producing no aflatoxins. Biocontrol strategies for reducing aflatoxin contamination have been developed that utilize strains of A. flavus that do not produce aflatoxins to competitively exclude aflatoxin producers. In commercial practice, these atoxigenic strains are applied during crop development on a fungal food source that fuels initial reproduction and dispersal of the biocontrol agent. Although applications alter the composition of A. flavus communities associated with crops and, as a result, reduce crop aflatoxin content, both crop infection by A. flavus and the quantity of A. flavus on the crop at harvest are no different in treated and untreated crops. Long-term influences of atoxigenic strain treatments have led to efforts to develop area-wide aflatoxin management programs. It is within such programs that the greatest potential for atoxigenic strain use may reside. However, for optimal benefits, improved methods for utilizing atoxigenic strains must be envisioned and developed. It is likely these will include methods that simultaneously utilize multiple strains.