14C-Labeled aflatoxin B1 prepared with yeastlike cultures of Aspergillus parasiticus

A simple method was developed to produce 14C-labeled aflatoxin B1 by using the yeastlike phase of Aspergillus parasiticus NRRL 2999. Yeastlike cultures resulted from absence of manganese in a synthetic medium. Sodium acetate-1-14C had a 0.22% average incorporation; sodium acetate-1,2-14C, 0.70%. The average yield of labeled B1 was 10 mg/500 ml medium with an average specific activity of either 63.3 mCi/mole (C-1 label) or 194.3 mCi/mole (C-1, 2 label).