[Effect of the composition of the medium and the conditions of Aspergillus foetidus cultivation on the biosynthesis of glucoamylase].

The optimal conditions for biosynthesis of exocellular glucoamylase were found in the course of submerged cultivation of Aspergillus foetidus ATCC 14916: pH 4.5 at the beginning of cultivation, cultivation for four days, a temperature of 30 degrees C, and an aeration in the fermenter of 1.5 volumes of the air per 1 volume of the medium with a stirring of 280 rpm. The material can be inoculated either as spores (1 X 10(7) spores per 100 ml of the medium) or a material germinated from spores (5% by volume). The composition of the medium was improved by using waste products of the agricultural industry (wheat and rice bran, yellow maize, etc.). The maximum biosynthesis of glucoamylase under the optimum conditions of cultivation was observed on crushed yellow maize (10--15%): up to 6.8--8.0 units of GIA (g of glucose per hour) per 1 ml of the cultural filtrate which was 3.4--4.0 times higher than on the original medium and 5--10 times higher than for Endomycopsis bispora, Endomycopsis sp. 20--9, Aspergillus niger and other cultures producing glucoamylase.