ARS | Publication request: Reduction of aflatoxins, cyclopiazonic acid and fumonisins in corn by biocontrol strains of non-aflatoxigenic Aspergillus flavus

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 17, 2011
Publication Date: June 1, 2011
Citation: Abbas, H.K., Horn, B.W., Weaver, M.A., Jin, X., Abel, C.A., Shier, W. Reduction of aflatoxins, cyclopiazonic acid and fumonisins in corn by biocontrol strains of non-aflatoxigenic Aspergillus flavus. American Phytopathological Society Abstracts. No. 6., P. S1. 2011.

Technical Abstract: A series of field studies in corn (maize) evaluated the ability of non-aflatoxigenic biocontrol strains of Aspergillus flavus to reduce, through competitive exclusion, production in kernels of aflatoxins and cyclopiazonic acid (CPA) by A. flavus and fumonisins by Fusarium verticillioides. The ability of non-aflatoxigenic strains to prevent aflatoxin production by subsequent challenge with toxigenic A. flavus strains was assessed using a pin-bar inoculation technique in four experiments conducted between 2007 and 2010. The non-aflatoxigenic strain K49 effectively prevented toxin production at various inoculation levels in 3 experiments. Strain K49 also was evaluated alongside the widely used biocontrol strains NRRL 21882 (Afla-Guard®) and AF36 for prevention of aflatoxin and CPA production by strains K54 and F3W4. K49 and NRRL 21882 were superior to AF36 in reducing total aflatoxin contamination. Neither K49 nor NRRL 21882 produced CPA, and they reduced CPA and aflatoxin production in a subsequent challenge with F3W4 and K54 by 84-97 % and 83-98%, respectively. In contrast, AF36 inoculation and subsequent challenge with F3W4 reduced aflatoxins by 20% and 93% with K54, but showed no CPA reduction with F3W4 and only 62% CPA reduction with K54. Because AF36 produces CPA, high levels of CPA accumulated when corn was inoculated with AF36 alone. Pin-bar wounding only and pin-bar inoculation with F. verticillioides NS-2 resulted in fumonisin contamination levels of 300 and 1300 ppm, respectively. However, inoculation with K49 alone or a mixture of K49 and NS-2 reduced fumonisin contamination to 13 ppm and 1.3 ppm, respectively. Reduction of fumonisin by AF36 and NRRL 21882 inoculation will be discussed. These results indicate that K49 and NRRL 21882 are effective in reducing aflatoxins, CPA and fumonisins in corn.