Aflatoxin-producing potential of Aspergillus flavus strains isolated from Spanish poultry feeds.

A total of 126 fungal strains belonging to the Aspergillus flavus group isolated from commercial poultry mixed feeds were studied. One hundred and twenty-five were identified as A. flavus and one as A. parasiticus. Forty nine strains (39%) produced aflatoxins on a crushed moist wheat medium (28 degrees C/10 days), whereas only sixteen (13%) showed specific fluorescence on Aflatoxin-Producing Ability Medium. In both media, mainly aflatoxins B1 and B2 were detected, the average concentration of aflatoxins being 4 294 +/- 1 083 micrograms/kg in crushed moist wheat medium, and 877 +/- 257 micrograms/kg in Aflatoxin-Producing Ability Medium.