Application of a statistical design to the optimization of parameters and culture medium for α-amylase production by Aspergillus oryzae CBS 819.72 grown on gruel (wheat grinding by-product)

The production optimization of α-amylase (E.C.3.2.1.1) from Aspergillus oryzae CBS 819.72 fungus, using a by-product of wheat grinding (gruel) as sole carbon source, was performed with statistical methodology based on three experimental designs. The optimisation of temperature, agitation and inoculum size was attempted using a Box–Behnken design under the response surface methodology. The screening of nineteen nutrients for their influence on α-amylase production was achieved using a Plackett–Burman design. KH2PO4, urea, glycerol, (NH4)2SO4, CoCl2, casein hydrolysate, soybean meal hydrolysate, MgSO4 were selected based on their positive influence on enzyme formation. The optimized nutrients concentration was obtained using a Taguchi experimental design and the analysis of the data predicts a theoretical increase in the α-amylase expression of 73.2% (from 40.1 to 151.1 U/ml). These conditions were validated experimentally and revealed an enhanced α-amylase yield of 72.7%.