High aflatoxin production on a chemically defined medium.

Aspergillus parasiticus ATCC 15517 produced 28 to 30 mg of aflatoxin per 100 ml of a medium containing sucrose, asparagine, and salts in stationary and shaken cultures. In the absence of asparagine in the medium, the toxin yields fell drastically, and the thin-layer chromatograms of the chloroform extracts of the cultures indicated the total absence of aflatoxin G(1) and the presence of new intense blue and green fluorescent bands having R(F) values lower than aflatoxins. Initial pH was critical and had to be around 4.5 for good growth and high toxin production on this medium. Optimum concentrations of KH(2)PO(4) and MgSO(4).7H(2)O in the medium were much lower than those normally used in fungal growth media.