Genetic and Molecular Analysis of Aflatoxin Biosynthesis

The aflatoxin biosynthetic pathway represents one of the est studied pathways of fungal secondary metabolism. Its lucidation is the result of over 30 years of study by cientists in many disciplines. For recent reviews on the hemistry of the pathway see articles by Bhatnagar et al. 1992) Minto and Townsend (1997), and Woloshuk and rieto (1997). Concern over the toxicity and carcinogenicty of aflatoxin has been the prime force driving research in his area. Aflatoxin B1 (AFB1) is the most potent naturally ccurring carcinogen known (Squire, 1989), and epidemioogical data implicate aflatoxin as a component of liver ancer in humans in certain parts of the world (Hall and ild, 1994). Although aflatoxins are not extremely toxic, onsumption of aflatoxin contaminated food by animals can ead to decreased weight gain, hemorrhaging, and suppression f the immune system (Miller and Wilson, 1994). Aflatoxins are produced by four species of Aspergillus: . flavus, A. parasiticus, A. nomius, and A. tamarii (Payne, 998; Kurtzman et al., 1986; Goto et al., 1996). From an gricultural standpoint, the two most significant fungi are