Submitted to: Revista Iberoamericana De Micologia
Publication Type: Review Article
Publication Acceptance Date: October 1, 2002
Publication Date: December 30, 2002
Citation: Yu, J., Bhatnagar, D., Ehrlich, K. 2002. Aflatoxin biosynthesis. Revista Iberoamericana De Micologia. 19:191-200. Interpretive Summary: Aflatoxins are natural secondary metabolites produced by several species of fungi. These toxins contaminate our food and feed supplies in many crops such as corn, cotton, rice, wheat etc. Better understanding the biochemical pathway and the mechanism of mycotoxin formation will provide necessary information for devising strategies to reduce mycotoxin contamination in food and feed. It will bring significant economic benefit to the farmers in the Southern states of the U.S. where corn, cotton, and peanuts are the major crops.
Technical Abstract: Aflatoxins are toxic and extremely carcinogenic natural secondary metabolites produced primarily by the fungi Aspergillus flavus and A. parasiticus. The biosynthesis of aflatoxins is a complex process involving multi-enzymatic reactions. Genetic studies of the molecular mechanism of aflatoxin B1 biosynthesis have identified an aflatoxin pathway gene cluster of 70 kilobase pairs in length consisting of at least the 24 identified structural genes including a positive regulatory gene as transcription activator. The structural genes encode cytochrome P450 monooxygenases, dehydrogenases, oxidases, methyltransferases, a polyketide synthase, and two unique fatty acid synthases. The aflatoxin biosynthesis and its genetic regulation are discussed in this review. The current knowledge of the relationship between fungal development and secondary metabolism is also summarized.