Production of sterigmatocystin by some species of the genus Aspergillus and its toxicity to chicken embryos.

Sterigmatocystin was produced by 59% of Aspergillus flavus cultures and by 16% of A. parasiticus cultures. All sterigmatocystin-producing cultures of the A. flavus group also simultaneously produced aflatoxin or O-methylsterigmatocystin. Sterigmatocystin was produced by A. chevalieri, A. ruber, and A. amstelodami, species not previously reported to produce the compound. In 5-day-old chicken embryos, the no-effect level of toxicity of sterigmatocystin was between 1 and 2 mug/egg; the mean lethal dose was 5 to 7 mug; and 90 to 100% of the embryos were killed with 10 mug. Teratogenic effects and weight reduction were generally associated with nonlethal doses.