Beschreibung:
<jats:title>Abstract</jats:title><jats:p>From 43 auxotrophic mutants <jats:italic>A. niger</jats:italic> found earlier 21 forced heterocaryons were obtained. All were examined with respect to total amylolytic activity by the method of test‐tube microculture, whereas 12 of them (with the highest indices of this activity) were also tested with regard to glucoamylase synthesis. In most cases the amylase activity of hererocaryons was much higher than that of their component strains of lower and frequently of a higher activity. A distinct increase of this activity was also shown by heterocaryons formed from auxotrophs, originating from them in relation to prototrophic parent cultures with a weak amylase activity. However, none of the heterocaryons equalled the level of amylase synthesis, reached by a highly active prototroph <jats:italic>A. niger</jats:italic> C in this respect.</jats:p>