Optimization of Cultural Conditions for the Production of Alpha Amylase by Aspergillus Niger (btm-26) in Solid State Fermentation

The present study deals with the isolation, screening and selection of native fungal strain for the alpha amylase production. Forty fungal strains were isolated from different soil samples. These strains were initially screened qualitatively on starch agar medium and quantitative screening was carried out in solid state fermentation. A strain of Aspergillus niger showing maximum production (432 ± 0.9 U/ml/min) of enzyme was selected and assigned the code BTM-26. The yield on various agricultural products, namely, coconut oil cake (COC), rice bran (RB), vegetable wastes or banana peel and wheat bran (WB) was compared. Wheat bran proved to be the best substrate for alpha amylase production. The effect of incubation temperature, initial pH, and inoculum size was investigated for the enzyme production. The maximum enzyme production was obtained at 30°C, pH 5, and inoculum size of 1 ml. The rate of fermentation was also studied and the highest yield of enzyme was obtained after 72 h of inoculation. Addition of 1.5% lactose as carbon source and 0.2% (NH4)2SO4 and 0.3% yeast extract as inorganic and organic nitrogen sources respectively gave enzyme production 990 ± 0.81 U/ml/min which reflects about 1.87 fold increase in alpha amylase production as compared to the medium containing wheat bran alone as substrate.