Production of Glucoamylase by Aspergillus Niger under Solid State Fermentation

In this study, Glucoamylase production by Aspergillus niger was investigated under solid state fermentation using low cost by-products of agricultural processes as substrate. Highest enzyme production was observed when a combination of wheat bran (WB) and corn flour (CF) was used as compared to WB+ rice bran, WB+ rice flour and WB alone. Several compositions of corn flours were experimented. The best combination of WB in addition of 10% corn flour resulted maximum enzyme activities. Study of the fermentations in flasks revealed 373.3 IU/gds and 41.4 g/l for the enzyme activity and protein concentration respectively under conditions of 30 1C, pH 4.7 and time 96 h. Optimum conditions provided by flask experiments were applied to produce the enzyme in a fermenter. A tray type sterilized fermenter was designed (7-lit volume, 2 trays of 450x230x35 mm, and 2 l/min aeration). The fermentations were performed under aseptic conditions and resulted in enzyme activity and protein concentration of 400 IU/gds, 33.3 mg/gds respectively (under 30 2C, pH=4.5 ~ 4.7, aeration 2 l/min, 90% relative humidity and time 72 h). The adequate amounts of enzyme activity, protein concentration and CO2 evolution revealed the efficiency of the bioreactor in comparison with flasks.