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± 1°c,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± 2°c,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.