Collaborative study of the effectiveness of the screening test on APA medium for aflatoxin producing aspergilli.

In 252 strains or Aspergillus flavus the ability of producing a blue fluorescenting substance in the APA medium (Hara et al., Appl. Microbiol. 27 (1974) 118) and the ability to produce aflatoxin B1 (AF) on Karlsbad biscuits have been investigated. In 92% of strains the three working places agreed in the characteristics of the observed properties of strains, but 20 (8,0%) strains producing AF on biscuits were evaluated on APA as negative. In 3 strains of 13 the working places B and C, which determined the AF production on buscuits, did not agree in their results. The authors discussed about the causes, but came to the conclusion that the screening method for the searching of AF producing of A. flavus by aid of the APA medium can be suitable at the investigation of big amounts of strains in routine laboratories, even when there exists a risk that some producers will be overlooked.