Biological control of aflatoxin production in corn using non-aflatoxigenic Aspergillus flavus administered as a bioplastic-based seed coating

Authors: ACCINELLI, CESARE - University Of Bologna; Abbas, Hamed; Little, Nathan; Kotowicz, Jeremy; SHIER, W - University Of Minnesota

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2018
Publication Date: 2/6/2018
Publication URL: http://handle.nal.usda.gov/10113/5896377
Citation: Accinelli, C., Abbas, H.K., Little, N., Kotowicz, J.K., Shier, W.T. 2018. Biological control of aflatoxin production in corn using non-aflatoxigenic Aspergillus flavus administered as a bioplastic-based seed coating. Crop Protection Journal. 107:87-92. https://doi:10.1016/j.cropro.2018.02.004.

Interpretive Summary: Mold called Aspergillus flavus produces aflatoxins which is a cancer causing chemical that contaminates corn. This is a major food safety concern. Isolates of an A. flavus that do not produce aflatoxins are used to control this cancer causing toxin. This study was used to determine the efficacy of application method of the novel technology, which includes a granule application, sprayable application, and most recently, a seed coating application or treatment. This study showed the coating application provided protection from agricultural pests, including lowering the level of aflatoxin and plant diseases. This study provides a valuable advance and cost effective in formulation technology for biological control of A. flavus strains and other pathogens that should prove useful for researchers and for biotechnology companies that market biological control products.

Technical Abstract: Since its first introduction in the early 1990s, tremendous progress has been made in the application of biocontrol techniques for reducing aflatoxin contamination in corn. In almost three decades, the basic concept has remained centered on massive application of propagules of non-aflatoxigenic A. flavus strains to corn fields; however, different delivery systems and formulations have been proposed. In the present study, the possibility of applying biocontrol propagules directly to corn seeds was explored. More specifically, seeds were film-coated using a bioplastic formulation containing two conventional pesticides and spores of a non-aflatoxigenic A. flavus isolates for protecting the crop during early growth stages and for reducing aflatoxin contamination risk. Application of the bioplastic film-coating did not affect percent of germination and seedling growth. In addition, incorporation of two commonly used seed treatment pesticides, the insecticide imidacloprid and the fungicide metalaxyl-M, and spores of the biocontrol A. flavus NRRL 30797 isolate into the bioplastic coat also had no effect on these biological parameters. The coat remained adherent to the seed surface thus also reducing seed dust release. When the fully-protected seeds were planted in corn fields located in different geographical areas, a decrease of the percent of recoverable aflatoxin-producer soil isolates was observed. This resulted in a significantly lower aflatoxin contamination of corn kernels. More specifically, experiments conducted in 2016 in a field located in Northern Italy showed a reduction of aflatoxin contamination from 7.1 ng g-1 to 2.1 ng g-1. Comparable results were observed from experiments conducted in the Mississippi Delta in 2015 and 2016, in two sites with different levels of soil A. flavus propagules. Across the two years, in the site where aflatoxin levels did not exceed 33.4 ng g-1, the reduction was of 44.8 and 75.4%, respectively. At another site, aflatoxin contamination levels of 74.4 ng g-1 in 2015 and 95.0 ng g-1 in 2016 were observed. Planting the fully-protected seed resulted in a 79.7 and 88.2% percent reduction in aflatoxin levels, respectively. Results from the present study open the potential for a novel technical approach for reducing the risk of aflatoxin contamination in corn by using a reduced dose of propagules of biocontrol isolates. Additional field research is needed to standardize this film-coating across different geographic regions.