THE PRODUCTION OF GLUCOAMYLASE BY ASPERGILLUS NIGER UNDER SOLID STATE CONDITIONS (RESEARCH NOTE)

Abstract

In this study, Glucoamylase production by Aspergillus Niger was investigated under solid state conditions with 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. Different additions of (CF) were tested and WB+ 10% CF showed to be the best combination. 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 301oC, pH4.7 and time 96 h. Optimum conditions provided by flask experiments were applied to produce the enzyme in a fermenter. A tray type sterilizable 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 302oC, 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.