The bioassay of aflatoxins and related substances with Bacillus megaterium spores and chick embryos

The “paper disc plate” method of antibiotic assay usingBacillus megaterium spores was tested for the assay of aflatoxins and related compounds. Significant inhibitions were obtained in the range of 1–4 µg/disc for aflatoxin B₁ and 4–8 µg/disc for aflatoxin G₁. Dicumarol was the most active of the compounds tested and inhibited at 0.1–1.0 µg/disc. Compounds were also tested using nine-day-old chick embryos. It was found that embryos incubated in egg cartons were much more sensitive to toxins than eggs incubated on cotton padding or in a commercial egg incubator. The LD₁₀₀ of aflatoxin B₁ to carton-incubated embryos was 0.01 µg, while to embryos from the commercial incubator the LD₁₀₀ was >5.0 µg. The results of the two bioassay procedures did not correlate completely with each other.