[Comparison of three methods for screening aflatoxin-producing strains].

By using rice medium microcolumn method, aflatoxin-producing ability medium dish method (APA method), A and M medium thin-layer chromato scanner method (AM method), seventy-six strains of Aspergillus flavus from the foodstuffs in Zhejiang province were screened for aflatoxin-producing strains, and which were confirmed with thin-layer chromatography method. Using the above three methods, aflatoxin-producing strains rates were detected respectively in 11.8%, 9.2% and 18.4%. Twenty aflatoxigenic strains were determined positive by all three methods (26.3%). All three methods showed false negatives. The AM method and APA method both showed false positives. The causes of false negatives and positives were discussed and the accord-rate of AM method with other methods was the highest as compared with that of microcolumn or APA method. False negative rate was the highest with APA method and next in order was that of microcolumn method. False positives appeared in both APA method and AM method. The causes of false negative and positive were discussed. It was suggested that AM method be safe, simple, and reliable method screening for aflatoxigenic strains be it improved in some aspects.