Effect of selected inhibitors on growth, pigmentation, and aflatoxin production by Aspergillus parasiticus.

We have treated a wild type strain of Aspergillus parasiticus with several known aflatoxin inhibitors in hopes of finding specific metabolic blocks in the aflatoxin biosynthetic pathway. In defined medium, benzoic acid (2 and 3 mg/ml), cinnamon (1 mg/ml), and sodium acetate (5 mg/ml) were fungitoxic. Benzoic acid (0.5 and 1 mg/ml), chlorox (5 microliters/ml), and dimethyl sulfoxide (5 microliters/ml) did not affect dry weight or mycelial pigmentation. Sodium benzoate (1, 2, 4 and 8 mg/ml) added after 2 days growth inhibited aflatoxin production in two defined media. We were unable to confirm previously published reports that an uncharacterized yellow pigment accumulates with benzoate-inhibition of aflatoxin biosynthesis.