Submitted to: Book Chapter
Publication Type: Book / chapter
Publication Acceptance Date: 12/15/2004
Publication Date: 2/1/2006
Citation: Chen, Z.-Y., Rajasekaran, K., Brown, R.L., Bhatnagar, D., Cleveland, T.E. 2006. Removal of aflatoxin from food and feed crops. In: Jaiwal, P.K., Singh, R.P., editors. Plant Genetic Engineering, Metabolic Engineering and Molecular Farming II. Houston, TX: Studium Press LLC. 8:73-110. Interpretive Summary:
Technical Abstract: Aflatoxins are secondary metabolites of Aspergillus flavus and A. parasiticus, which contaminate a variety of important agricultural products, such as corn, cottonseeds, peanut, and tree nuts, both in the field and after harvest, and are extremely carcinogenic when ingested by animals and humans. The wide occurrence of aflatoxin contamination in food and feed and the subsequent serious health and economic impact are well recognized internationally. So far, over 50 countries have established or proposed regulations on the permissible level of aflatoxins in food and feed. Current strategies employ both pre-harvest and post-harvest measures to reduce the risk of aflatoxin contamination in food and feed. Post-harvest measures, such as adequate storage, detection, and decontamination or disposal, as well as the governmental regulations and continuous monitoring of potential contamination during processing and marketing of agricultural commodities, have proved to be crucial and indispensable in ensuring food and feed safety; however, these measures do not address the issue fundamentally. Therefore, the current research focus has shifted from post-harvest control to a more preventive approach employing various pre-harvest control measures in the past decades. Pre-harvest control includes good cultural practices, insect control, biocontrol of fungal infection using atoxigenic strains of A. flavus or other antagonistic bacteria or fungi, identification of resistant varieties, and enhancement of host plant resistance through molecular breeding. These measures are the results of recent research progress on the ecology and epidemiology of aflatoxin producing fungi, molecular mechanisms governing aflatoxin biosynthesis, and different resistant mechanisms the host plants evolved to fend off the fungal infection and aflatoxin production. Enhancing host resistance is the most widely explored strategy for eliminating aflatoxin contamination by A. flavus. The characterization of genes of the aflatoxin biosynthetic pathway and understanding the biochemical function and genetic regulation of aflatoxin biosynthesis can provide us with potential targets for disruption using candidate genes encoding antifungal or other resistance-associated proteins. Successful inhibition of aflatoxin elaboration may require not only the action of antifungal compounds, but also compounds that block biosynthesis of toxins as well.