Effect of Other Toxigenic Mold Species on Aflatoxin Production by Aspergillus flavus in Sterile Broth Shake Culture

Abstract

The effect of Aspergillus ochraceus, A. versicolor, Penicillium citrinum, P. cyclopium and P. urticae on production of aflatoxin by A. flavus when grown together with A. flavus in rotary shake culture was investigated. The two aspergilli had no apparent effect on aflatoxin production, whereas all three Penicillium species substantially lowered aflatoxin production. The toxins that these penicillia produced when growing in pure culture were not found when the penicillia were grown with A. flavus. However, these toxins had no effect on aflatoxin production added to the growth media, nor did the three molds metabolize aflatoxin. When A. flavus was grown in both filter- and autoclave-sterilized filtrates of these three species, no aflatoxins were produced, although A. flavus grew well. These results suggest that although A. ochraceus and A. versicolor have no apparent effect on aflatoxin production, P. citrinum, P. cyclopium and P. urticae produce heat-stable, nonfilterable metabolite(s) which inhibit(s) aflatoxin production by actively growing A. flavus.