Aflatoxin-producing Strains ofAspergillus flavusIsolated from Feeds in Norway

Abstract

Abstract The aflatoxigenic ability of 300 strains of Aspergillus flavus (Link) was examined employing thin layer chromatography (TLC) of plugs of cultures on agar media incubated for two weeks. The strains were isolated from 185 samples of various feeds and grains used in Norway. They were cultivated on yeast extract sucrose agar (YES) and a synthetic low salts agar medium containing 30 mM formic acid (SLA). The cultures on SLA were examined directly under UV-light (366 nm) for the occurrence of blue fluorescence. Aflatoxigenic strains were demonstrated in 81 samples and comprised in all 115 of the 300 strains examined. Twenty per cent of the 197 strains cultivated on SLA showed blue fluorescence under UV-light. Eighty-seven per cent of these fluorescent strains were aflatoxigenic as compared with 36% of the non-fluorescent strains. The present investigation indicates that aflatoxigenic strains occur frequently in populations of A. flavus demonstrated in various feeds and grains in Norway. It was conclude...