ARS | Publication request: Gene Profiling for Studying the Mechanism of Aflatoxin Biosynthesis in Aspergillus flavus and A. parasiticus

Submitted to: Journal of Food Additives & Contaminants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 8, 2007
Publication Date: October 1, 2007
Citation: Yu, J., Ronning, C.M., Wilkinson, J.R., Campbell, B.C., Payne, G.A., Bhatnagar, D., Cleveland, T.E., Nierman, W.C. 2007. Gene profiling for studying the mechanism of aflatoxin biosynthesis in Aspergillus flavus and A. parasiticus. Journal of Food Additives & Contaminants. 24(10):1035-1042.

Interpretive Summary: Aflatoxins are the most potent cancer-inducing agent produced by the fungal molds, Aspergillus flavus and A. parasiticus. These aflatoxins are extremely toxic to both humans and animals. They contaminate agricultural commodities. Due to health and food safety concern, the mechanism of aflatoxin formation and prevention of aflatoxin contamination have been investigated in great detail. Aspergillus flavus expressed sequenced tags (EST's), gene chip technologies and whole genome sequencing strategies have been pursued. We reported here the results of our preliminary genomics efforts in understanding the mechanism of aflatoxin formation for devising strategies to reduce or eliminate aflatoxin contamination of food and feed.

Technical Abstract: Aflatoxins are toxic and carcinogenic polyketide metabolites produced by certain fungal species, including Aspergillus flavus and A. parasiticus. Because many internal and external factors, such as nutrition and environment affect aflatoxin biosynthesis, we have analyzed the transcriptome of A. flavus using Expressed Sequence Tags (EST's) from a normalized cDNA expression library constructed from mycelia harvested under variable conditions. A total of 7,218 unique EST's were identified from 26,110 sequenced cDNA clones. Functional classifications were assigned to these EST's, and genes potentially involved in the aflatoxin contamination process were identified. A genomic DNA amplicon microarray has been constructed at The Institute for Genomic Research (TIGR) based on this EST sequence information. To identify potential regulatory networks controlling aflatoxin contamination in food and feeds, gene expression profiles in aflatoxin-supportive media vs. non-aflatoxin-supportive media were evaluated in A. flavus and A. parasiticus. Genes consistently expressed in several aflatoxin-supportive media are reported.