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The fate of aflatoxins associated with contaminated crops in soil
L. R. L. ARONE (1), R. Jaime (2), R. Ranajit Bandyopadhyay (3), P. J. Cotty (4). (1) University of Arizona, Tucson, AZ, U.S.A.; (2) School of Plant Sciences, University of Arizona, Tucson, AZ, U.S.A.; (3) International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria; (4) Agricultural Research Service, USDA / School of Plant

Aflatoxins are potent mycotoxins that contaminate foods and feeds worldwide causing immune system suppression, stunting, cancer, and death in humans and domestic animals.  Frequently, crops with severe aflatoxin contamination are incorporated into soil because such crops have no available markets. The current study was undertaken to establish the extent to which the process of plowing contaminated crops under influences both the long-term residence of aflatoxin-producers in agricultural soils and the rate of aflatoxin degradation. Improved understanding of the speed of degradation of aflatoxin contaminated crops may facilitate aflatoxin management.  Elucidation of influences of soil incorporation on long-term survival of aflatoxin producers may clarify the value of agronomic practices for aflatoxin management and provide practices to optimize biocontrol with atoxigenic strains of <i>Aspergillus flavus</i>. Naturally contaminated cottonseed meal containing over 50 mg/kg aflatoxin B1 was sandwiched between layers of soil from an Arizona cotton field and incubated for 14 days at 15°C.  Both aflatoxins and <i>A. flavus</i> propagules were influenced by incubation with soil while the overall quantity of bacteria and fungi in the soil increased.  The results suggest that the practice of incorporation of contaminated crops into agricultural soils can be manipulated to optimize long-term aflatoxin management.

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