AGRICULTURAL PRACTICES, ECOLOGICAL AND VARIETAL EFFECTS ON AFLATOXINS AND OTHER MYCOTOXINS IN CORN
Location: Biological Control of Pests Research Unit
Title: Comparison of major biocontrol strains of non-aflatoxigenic Aspergillus flavus for the reduction of aflatoxins and cyclopiazonic acid in maize
Submitted to: Journal of Food Additives & Contaminants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 24, 2010
Publication Date: February 11, 2011
Citation: Abbas, H.K., Zablotowicz, R.M., Horn, B.W., Phillips, N.A., Johnson, B.J., Jin, X., Abel, C.A. 2011. Comparison of major biocontrol strains of non-aflatoxigenic Aspergillus flavus for the reduction of aflatoxins and cyclopiazonic acid in maize. Journal of Food Additives & Contaminants. 28:198-208.
Interpretive Summary: Aflatoxins and Cyclopiazonic acid (CPA) are toxic compounds produced by the mold Aspergillus flavus. They have major impact on and are a concern in food safety in corn and other crops such as peanuts, cotton and tree nuts. There is no good method to control this problem. The ARS has developed three strains of Aspergillus that do not produce aflatoxins. All of the strains reduce aflatoxins in corn, although one of them produces another dangerous toxic material called CPA. The other two cultures, K49 and Alfa-guard reduce aflatoxins and CPA in corn by competitive displacement, dramatically. The use of non-toxin producing strains of Aspergillus flavus to completitively displace toxin producing strains of the fungus could be very helpful in controlling aflatoxins and CPA in corn.
Biological control of toxigenic Aspergillus flavus in maize through competitive displacement by non-aflatoxigenic strains was evaluated in a series of field studies. Four sets of experiments were conducted between 2007 to 2009 to assess the competitiveness of non-aflatoxigenic strains when challenged against toxigenic strains using a pin-bar inoculation technique. In three sets of experiments, the non-aflatoxigenic strain K49 effectively displaced toxigenic strains at various concentrations or combinations. The fourth study compared the relative competitiveness of three non-aflatoxigenic strains (K49, NRRL 21882 from afla-guard®, and AF36) when challenged on maize against two aflatoxin- and cyclopiazonic acid (CPA)-producing strains (K54 and F3W4). These studies indicate that both K49 and NRRL 21882 are superior to AF36 in reducing aflatoxin contamination. Neither K49 nor NRRL 21882 produce CPA and, when challenged with K54 and F3W4, CPA and aflatoxins were greatly reduced. However, AF36 produces CPA and consequently high levels of CPA accumulate when maize is inoculated with AF36 alone or in combination with K54 or F3W4. These results indicate that K49 may be equally effective as NRRL 21882 in reducing both aflatoxins and CPA in maize.