| 摘要 |
The invention relates to a process for preparing glucoamylases by biosynthesis, using a selected strain of Aspergillus awamori, said process consisting in cultivating the microorganism in submerged state and in discontinuous system, in a nutritive medium containing corn meal 2...3 g%, soya meal 1...2 g%, corn extract 2...4 g% with 48...50% s.u. and additional mineral salts K2HPO4 0.1...0.5 g% and (NH4)2SO4 0.1...0.5 g%, then obtaining the enzyme preparation by filtering the native enzyme solution through the Nutsche filter with pearlite layer on oil bed, afterwards concentrating the resulting liquid phase in vacuum at temperatures ranging between 35 and 40°C, in order to prevent the thermal inactivation, the adequate parameters for the development of the bioprocess being the temperature of 28...31°C, the initial aeration of 0.1...0.3 l/l min rising slowly during fermentation to 0.4...0.6 l/l min, the stirring of 200...300 rpm, the pH resulting after the medium sterilization of 4.7...5.2, the native enzyme solutions being stabilized by adding CaCl2 0.1 g%.
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