Submitted to: Food and Nutrition Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2011
Publication Date: 7/22/2011
Citation: Ehrlich, K., Wei, Q., Brown, R.L., Bhatnagar, D. 2011. Inverse correlation of ability to produce aflatoxin and aspergillus colonization of maize seed. Food and Nutrition Sciences. 2:486-489. Interpretive Summary: Prevention of contamination of susceptible crops with the carcinogenic and highly toxic mold toxin, aflatoxin, is the main objective of the research in SRRC’s Food and Feed Safety program. A biocontrol strategy is being tested that involves introducing a non-aflatoxigenic strain of the mold Aspergillus flavus onto the crops to prevent contamination with aflatoxin-producing isolates naturally present in the soil. Why this strategy works is poorly understood. There is some data suggesting that the non-aflatoxigenic isolates must by present in such high numbers so as to overwhelm the natural populations. Other researchers have presented convincing data that mixed culture of the toxin-producing strain with the non-toxin-producing strain is enough to prevent aflatoxin production. We now show that non-aflatoxigenic A. flavus are able to out-compete toxin-producing isolates in colonizing the seed and thereby prevents aflatoxin production, even if later, toxin-producing isolates are able to colonize as well.
Technical Abstract: Seeds of aflatoxin-resistant and aflatoxin susceptible maize lines were inoculated with conidia of aflatoxin-producing Aspergillus flavus or A. parasiticus isolates or isogenic non-producing mutants. Conidial yields recovered from resistant maize seed after seven days were significantly lower for aflatoxin-producing A. flavus and A. parasiticus strains than for isogenic mutants incapable of aflatoxin production. This result helps to explain why, in currently used biocontrol strategies for aflatoxin elimination, non-aflatoxigenic isolates out-compete aflatoxin-producing isolates for invasion of the seed.