Control of Biosynthesis of Aflatoxin in Strains of Aspergillus Flav us

Aflatoxins are toxic, carcinogenic chemicals produced by the fungal species, Aspergillus flavus and A. parasiticus. These fungi can infect crops before and after harvest and produce aflatoxins, thereby contaminating foods and feeds and threatening both human and animal health (Goldblatt, 1970; Jelinek et al., 1989). The first report of the toxicity of aflatoxins appeared nearly thirty years ago in Great Britain (Blount, 1961) when the cause of the extensively publicized turkey "X" disease was traced to contaminated peanut meal from Brazil. The disease caused the deaths of over 120,000 turkeys and other poultry and led to a huge research effort to investigate aflatoxin contamination of foods and feeds in the USA and other countries. Aflatoxin was first detected in cottonseed and cottonseed meal about 25 years ago and, since then, Agricultural Research Service scientists at the Southern Regional Research Center have investigated methods to control aflatoxin contamination of food and feed commodities. Initial research by scientists at the Center centered on the development of analytical techniques to quantify aflatoxins and on the development of methods to detoxify contaminated products (Goldblatt, 1970; Park et al., 1988; Pons and Goldblatt, 1965). In the 1980's, scientists in our research Unit began research on Arizona-grown cottonseed to develop an understanding of the environmental and ecological factors that control the synthesis of aflatoxin in agricultural commodities. Research efforts centered on prevention of aflatoxin contamination before harvest to prevent the initial association of aflatoxin with crop tissues; this strategy was designed to alleviate the need to either discard contaminated crops or subject the crops to costly detoxification procedures. The research was carried out in Arizona cotton fields having some of the highest endemic levels of aflatoxin known. The knowledge generated by this research eventually led to the formulation by project scientists of certain recommended cultural practices, which if used by growers would reduce preharvest aflatoxin contamination in Arizona cottonseed (Cotty, 1989a). Briefly, these recommendations included: 1) prevention of insect damage of cotton bolls during certain defined periods in the growing season (boll