Molecular Biology of Aflatoxin Biosynthesis in Aspergillus flavus (9601575)

Aflatoxins are highly toxic and carcinogenic in a variety of animal species and are suspected carcinogens in humans. These natural chemicals are common contaminants of important crops like corn, cotton, peanuts and tree nuts. The long range goals of this research program are to understand the regulation of aflatoxin production in food and to develop novel approaches for eliminating this contamination. Aflatoxins are produced by a complex biochemical pathway. One of the intermediates in this pathway is sterigmatocystin which is also a potent carcinogenic produced by many fungi. Only the filamentous fungi Aspergillus flavus and Aspergillus parasiticus convert sterigmatocystin to aflatoxin. We have discovered a strain of A. flavus with a deletion of the genes required for aflatoxin biosynthesis. This strain has no background expression of the aflatoxin biosynthetic genes, and is useful to answer questions about the regulation of aflatoxin biosynthesis. This work focuses on characterizing two new genes involved in aflatoxin biosynthesis. One gene is in the early part of the pathway and the other is responsible for the last step in the conversion of sterigmatocystin to aflatoxin. Because aflatoxin production is unique to only a few species, this study will lead to new information about these species and the closely related species A. sojae and A. oryzae, which are important to the food industry.