Optimization of phytase production by Aspergillus japonicus Saito URM 5633 using cassava bast as substrate in solid state fermentation

摘要

Production of phytase by Aspergillus japonicus URM 5633 was investigated by solid state fermentation (SSF) using cassava bast as substrate. The effects of temperature, pH and initial moisture on phytase production were studied using a full factorial design 23. The maximum phytase activity was 174 U/g dry substrate. The optimum conditions for phytase production were pH 6.5 and 40% initial moisture at 26°C with 96 h of fermentation. A factorial design 22 was created to optimise phytase production, where the initial moisture and temperature were the variables studied. The parameters for phytase production were fixed at 30% initial moisture, 30°C and pH 5.5, and the maximum activity obtained was 183.1 U/g dry substrate. The effects of glucose concentration, nitrogen source type and nitrogen source concentration in phytase production was studied using the 23 factorial design. Nitrogen source concentration was significant for phytase activity and had a negative effect, indicating that smaller values increased enzyme activity. The optimum activity for phytase occurred at pH 3.6 and at an apparent optimum temperature of 60°C. Phytase was stable in the pH range of 2.4-3.0 at 30-70°C. The enzymatic activity increased significantly in the presence of FeSO4.