Abstract
Aflatoxins are highly toxic and carcinogenic substances mainly produced by Aspergillus f lavus and Aspergillus parasiticus. Contamination of agricultural commodities with aflatoxins is a very serious problem all over the world. Aflatoxin biosynthesis has been extensively studied, and now it is known that at least 18 enzyme steps are involved in the pathway from acetyl CoA to aflatoxins. Many genes encoding the enzymes and the transcription factors have been isolated, and those functions have been studied. In the genomes of A. parasiticus and A. flavus, at least 25 genes related to aflatoxin biosynthesis make a 70-kb gene cluster. We have investigated many enzyme reactions involved in aflatoxin biosynthesis by using cell-free systems. Our biochemical studies showed the aflatoxin biosynthetic pathway has many unique characters as a secondary metabolism.
