Production of aflatoxin on wheat and oats: measurement with a recording densitometer.

A method has been developed for the production of aflatoxin by growing Aspergillus flavus NRRL 3145 on solid substrate wheat. Optimal yields of 900 mug of aflatoxin G(1) and 900 mug of aflatoxin B(1) per g of substrate were obtained in 4 to 5 days at 28 C. A study of aflatoxin production on hulls and groats of oats and on whole oats by A. flavus strains NRRL 2999, NRRL 3000, and NRRL 3145 revealed that aflatoxin was produced on all three substrates, although production was very slight on hulls. Strain NRRL 3145 grown on solid substrate groats produced the largest amounts of aflatoxin: 580 mug of B(1) and 450 mug of G(1) per g of substrate. A densitometric method for reading thin-layer chromatographic plates is described; this is more objective and more accurate than the visual methods previously used for the determination of all four aflatoxins.