Mycotoxins are low-molecular weight, nonproteinaceous, organic secondary metabolites produced by fungi from amino acids, shikimic acid, or malyonyl CoA. These compounds are toxic, mutagenic, teratogenic, and carcinogenic to animals and humans (Bennett 1987; Bhatnagar et al. 2002; Eaton and Groopman 1994; Hall and Wild 1994; Squire 1989). Over 300 mycotoxins have been identified, but only those implicated in mycotoxicoses involving humans have been studied in detail with respect to the biochemistry and genetics of their biosynthesis. Research on the natural occurrence, identification and characterization, biosynthesis and genetic regulatory control of mycotoxins, as well as prevention and control of mycotoxin contamination of food and feed gained momentum after the incidence of "Turkey-X" disease in 1960 when 10,000 turkeys died due to aflatoxin contamination in the peanut-meal feed. Due to the risk of mycotoxin contamination of foods and feed on human health and livestock productivity (Brown et al. 1998; Eaton and Groopman 1994), regulations have been established in over 50 countries for acceptable levels of mycotoxins in commodities for commerce or food and feed for human and animal consumption (Bhatnagar et al. 2002; Sharma and Salunkhe 1991). Within the last decade, significant progress toward the understanding of several mycotoxins in the world has been made. In this chapter, the genetics and biochemistry of only the most economically significant mycotoxins, aflatoxins, sterigmatocystin (ST), trichothecenes, and fumo-nisins, are summarized and discussed. For other mycotoxins such as alternaria toxins AAL toxins, AK-toxin, ochratoxins, citrinin, cyclopiazonic acid (CPA), patulin, paxilline, zearalenone, ergot alkaloids and related toxins, and other neurotropic mycotoxins, kindly refer to the most recent comprehensive reviews on this subject (Bhatnagar et al. 1988; 2002).
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