Management of Pre-Harvest Aflatoxin Contamination of Cottonseed Using Beneficial Bacteria

The overall goal of our study is to find effective and environmentally sound methods to reduce pre -harvest aflatoxin contamination of cottonseed in Arizona. The specific objectives are: 1) to screen a large number of bacteria for their ability to destroy the aflatoxin producing fungus, Aspeigillus flavus; 2) to test the efficacy and consistency of the recovered antagonistic bacterial isolates to reduce aflatoxin contamination of cottonseed in field trials; 3) to study the survival and competitiveness of the antagonists on cotton plants under prevailing field conditions; 4) to find innovative procedures to enhance survivability and competitiveness of the antagonists on cotton plants; and 5) to test the potential of the bacterial antagonists to reduce the population of A. flavus in field soils. Over 800 bacterial isolates, recovered from cotton field soils, cotton leaves, stems, and immature as well as opened bolls, were tested for ability to inhibit the growth of A. flavus on cottonseed. Six isolates partially or totally inhibited the fungus. All of these effective isolates prevented the fungus fioin infecting simulated pink bollworm exit holes in immature bolls in the field