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Improvement of Biological Control Fungi for Reduction of Aflatoxin Contamination


1. Understand the phylogenetics of aflatoxin production through an examination of the population dynamics of aflatoxigenic and atoxigenic Aspergillus (A.) species in mixed cultures. Determine the potential for restoration of toxigenicity in toxigenic strains of A. flavus and development of toxicity in other species or genera which contain partial aflatoxin gene clusters.

2. Identify A. flavus pathogenicity factors required during invasion of oilseed crops and link these factors to aflatoxin contamination. Identify the critical enzymes that will allow the formulation of viable biological control strategies for a given crop situation.

More Info:
Aflatoxins (AFs) are polyketide-derived, toxic and carcinogenic secondary metabolites produced mainly by Aspergillus (A.) flavus on cotton, corn, peanuts, and tree nuts. One of the main strategies for prevention of AF contamination in these crops involves introducing a non-aflatoxigenic competitor Aspergillus to the soil of the plants during the growing season. Recent work revealed that A. flavus has a complicated evolutionary history that includes a history of recombination. It is the purpose of this proposal to better understand A. flavus population dynamics in agricultural environments in order to more safely use biocontrol as a strategy to reduce crop contamination with AFs. To do this we will develop new competitor strains with improved properties for tracking their dispersal after introduction onto crops and with improved ability to over-winter in order to decrease the need for annual reapplication. Optimal candidates should be unable to produce the neurotoxin, cyclopiazonic acid, without altering their competitive ability. The potential for restoration of both AF- and CPA-producing ability of the atoxigenic strain in the laboratory or the field will be assessed. We will determine if the ability to produce hydrolases by the biocontrol strain is important for its competitive ability. With these studies, we expect to be able to either develop new biocontrol strains or improve the design of currently used biocontrol strains to reduce preharvest AF contamination. We also expect to provide additional insight into the evolution of diversity within A. flavus.
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Bhatnagar, Deepak
Cary, Jeffrey
Chang, Perng
Cotty, Peter
Ehrlich, Kenneth
Mellon, Jay
Moore, Geromy
Project Reports:
Published Journal Articles USDA ARS (NP 108):
Growth inhibitory effects of gossypol and related compounds on fungal cotton root pathogens
Mellon JE, Dowd MK, Beltz SB, Moore GG.
Lett Appl Microbiol. 2014 Aug;59(2):161-8.
Comparison of expression of secondary metabolite biosynthesis cluster genes in Aspergillus flavus, A. parasiticus, and A. oryzae
Ehrlich KC, Mack BM.
Toxins (Basel). 2014 Jun 23;6(6):1916-28.
Non-aflatoxigenic Aspergillus flavus to prevent aflatoxin contamination in crops: advantages and limitations
Ehrlich KC.
Front Microbiol. 2014 Feb 10;5:50.
Effects of temperature and medium composition on inhibitory activities of gossypol-related compounds against aflatoxigenic fungi
Mellon JE, Dowd MK, Beltz SB.
J Appl Microbiol. 2013 Jul;115(1):179-86.
Fragmentation of an aflatoxin-like gene cluster in a forest pathogen
Bradshaw RE, Slot JC, Moore GG, Chettri P, de Wit PJ, Ehrlich KC, Ganley AR, Olson MA, Rokas A, Carbone I, Cox MP.
New Phytol. 2013 Apr;198(2):525-35.
Dothistromin genes at multiple separate loci are regulated by AflR
Chettri P, Ehrlich K, Cary JW, Collemare J, Cox MP, Griffiths SA, Olson MA, De Wit PJ, Bradshaw RE.
Fungal Genet Biol. 2013 Feb;51:12-20.
Association with AflR in endosomes reveals new functions for AflJ in aflatoxin biosynthesis
Ehrlich KC, Mack BM, Wei Q, Li P, Roze LV, Dazzo F, Cary JW, Bhatnagar D, Linz JE.
Toxins (Basel). 2012 Dec;4(12):1582-600.
Relationships between in vivo and in vitro aflatoxin production: reliable prediction of fungal ability to contaminate maize with aflatoxins
Probst C, Cotty PJ.
Fungal Biol. 2012 Apr;116(4):503-10.
Non-Journal Publications:
Genetic diversity and population structure of Aspergillus flavus in the southern USA - (Abstract Only)
Grubisha, L.C., Cotty, P.J. 2011. Genetic diversity and population structure of Aspergillus flavus in the southern USA[abstract]. Mycological Society of America. 62(3):21.
Genomics of Aspergillus flavus mycotoxin production - (Book / Chapter)
Payne, G.A., Georgianna, D.R., Yu, J., Ehrlich, K., Brian, G.O., Bhatnagar, D. 2011. Genomics of Aspergillus flavus mycotoxin production. In: Fratamico, P., Liu, Y., Kathariou, S., editors. Genomes of Foodborne and Waterborne Pathogens. Washington, DC: ASM Press. pp 259-270.
Food Safety Categories:
Sanitation and Pathogen Control
Government Policy and Regulations
Pathogen Biology
Farm-to-Table Categories:
On-farm food production