Biological Control of Aflatoxin ContaminationPage 2 Currently, the most promising and safest research approach is through biological control. Afla-guard was developed utilizing the proven concept of “competitive exclusion” in which spores of a benign strain of Aspergillus flavus are formulated into an inoculum and seeded into soils around the growing peanut plant. By colonizing the peanut pod zone, the mold provides a biological shield against toxigenic fungi.5 Advantages of biocontrol include minimal disturbance of the ecosystem, positive consumer perception, no gene technology or food safety regulations, and the potential for readily transferable technology to other countries.6 The Process The competitive fungus is bound to a small grain, which serves as (1) a carrier, to get the fungus to the field, and (2) a substrate, for the fungus to grow and multiply on. The carrier is applied with equipment normally used for granular applications, and it comes to rest on the soil surface around the peanut plants. The fungus then begins to grow and produces a multitude of spores on the surface of the carrier. The spores spread into the soil where the fungus is in position to compete with the strains capable of producing aflatoxin.7 Field Test Results Studies over several years in the National Peanut Research Laboratory environmental control plot facility have shown consistent aflatoxin reductions in the range of 70-90%. Peanuts in field tests that were exposed to natural drought conditions in 1997 and 1999 also had aflatoxin reductions averaging about 90% when treated with the competitive fungus.8
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