[Isolation and purification of glucoamylase from the submerged culture of Aspergillus foetidus ATCC 14916].

Isolation and purification of glucoamylase from Aspergillus foetidus ATCC 14916 were examined. Ethanol and ammonium sulphate proved to be the best precipitants. With their use the yield of glucoamylase was 99.0 and 92.3%, respectively. Treatment of the culture liquid with 0.5% CaCl2 and activated charcoal clarified the filtrate noticeably and left glucoamylase activity unchanged. During submerged cultivation the gungus synthesized no glucosyl transferase. A method to inactivate alpha-amylase through acidification of the reaction mixture to bring pH to 2.5 and incubation for 15 min at 60 degrees C was developed. Glyoamylase was partially purified from ballast proteins by means of (NH4)2SO4 at 19% of total saturation. Glucoamylase was obtained at 79% saturation. The infrared spectrum was recorded in the fraction obtained by (NH4)2SO4 precipitation at 39, 53, 66, 72 and 79% saturation. In all the cases the spectra were identical. This is another proof of purity of the resultant preparation.