Submitted to: Biocontrol Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/27/2011
Publication Date: 7/10/2011
Citation: Horn, B.W., Dorner, J.W. 2011. Evaluation of different genotypes of nontoxigenic Aspergillus flavus for their ability to reduce aflatoxin contamination in peanuts. Biocontrol Science and Technology. 21(7):865-876. Interpretive Summary: Aflatoxins produced by the mold Aspergillus flavus are potent carcinogens and account for large monetary losses worldwide in peanuts, maize and cottonseed. Biological control in which a nontoxic strain of A. flavus is applied to crops at high concentrations effectively reduces aflatoxins through competition with native aflatoxin-producing strains. Results from a peanut seed assay in this research suggest that several nontoxic strains are more effective at reducing aflatoxins in peanuts than the currently used biocontrol strain.
Technical Abstract: Aflatoxins produced by the fungus Aspergillus flavus are potent carcinogens and account for large monetary losses worldwide in peanuts, maize and cottonseed. Biological control in which a nontoxigenic strain of A. flavus is applied to crops at high concentrations effectively reduces aflatoxins through competition with native aflatoxigenic populations. In this study, eight nontoxigenic strains of A. flavus belonging to different vegetative compatibility groups and differing in deletion patterns within the aflatoxin gene cluster were evaluated for their ability to reduce aflatoxin B1 when paired with eight aflatoxigenic strains on individual peanut seeds. Inoculation of wounded viable peanut seeds with conidia demonstrated that nontoxigenic strains differed in their ability to reduce aflatoxin B1. Reductions in aflatoxin B1 often exceeded expected reductions based on a 50:50 mixture of the two A. flavus strains, although one nontoxigenic strain significantly increased aflatoxin B1 when paired with an aflatoxigenic strain. Therefore, nontoxigenicity alone is insufficient for selecting a biocontrol agent and it is also necessary to test the effectiveness of a nontoxigenic strain against a variety of aflatoxigenic strains.