How Aflasafe Works
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- 22 February 2017
aflasafe™ (see video) was developed by IITA in collaboration with Agriculture Research Service of the United States Department of Agriculture, University of Bonn and University of Ibadan. We evaluated more than 4200 strains of Aspergillus species from naturally infected maize cobs collected from farmers’ fields and stores in Nigeria. After 6 years of meticulous and painstaking research using several microbiology, plant pathology, molecular biology and toxicology methods, 12 safe and effective atoxigenic strains were identified out of which 4 were further tested for 6 years in experiment stations and farmers’ fields in Nigeria.
The aflasafe™ strains cannot produce aflatoxins since they have inherent defects in one or more of the 26 genes in the aflatoxin biosynthetic pathway. They also cannot become toxigenic since the selected atoxigenic strains belong to genetic groups that posses only atoxigenic strains. Hence, genetic exchange between members of the same atoxigenic genetic group cannot transform atoxigenic strains to toxigenic ones. Members of two different genetic groups cannot exchange DNA.
The biocompetitive product aflasafe™ contains a mixture of four atoxigenic strains of A. flavus of Nigerian origin. These atoxigenic strains are allowed to internally colonize sorghum grains for a brief period and dried. aflasafe™ externally looks like cooked sorghum grain, and internally contains very small amount (a few nanograms) of the four atoxigenic strains.
aflasafe™ is tossed on field soil by hand 2-3 weeks prior to flowering of crop @ 10-20 kg per hectare. Within 2-3 days after application of aflasafe, the atoxigenic strains sporulate on the sorghum grains which act as their food source. The atoxigenic strains continue to produce spores for up to three weeks on sorghum grain carrier after field application. The atoxigenic strains colonize the organic matter and other plant residues in the soil in place of the toxin producing strains. Spores of the atoxigenic strains are then naturally blown by air and moved by insects from soil surface to maize cobs displacing the toxin producing strains.
Application of aflasafe does not increase the total amount of Aspergillus in the environment but shifts the strain profile from toxigenic to atoxigenic strains of aflasafe. A single application is effective for several years and in several crops. Protection by aflasafe carries over from field to store thus protecting maize/groundnut along the entire value chain (from field to fork).