Phytase production by Penicillium purpurogenum GE1 isolated from soil around bean
root nodules was investigated by solid state fermentation (SSF) using mixed substrates consisted
of corn cob and corn bran. The SSF conditions were optimized by using one-variable–at-a-time
strategy. The optimum conditions for phytase production were at 27 C, pH 8 and 66% moisture
content. The study of different carbon and nitrogen sources revealed that glucose and peptone registered
the highest enzyme productivity (92 ±5.6 U/g ds, 125 ± 4.9 U/g ds). Among different surfactants,
maximum phytase productivity was observed with Tween 80 at 0.001 concentrations
(170± 4.2 U/g ds). A Box–Behnken design was employed to investigate the optimization of the
most significant variables affecting the enzyme production. Maximal phytase production was
detected after the addition of (g/5 g ds): 0.75 glucose, 0.375 peptone and 0, 01 tween 80. This result
represented an improvement in phytase production of 2.6 folds when compared to that previously
obtained using the basal medium under the same cultivation conditions. The generated model was
found to be very adequate for phytase production (90% accuracy) as the experimental value was
444± 3.5 U/g ds compared to 401 U/g ds for the predicted value. In brief, the production of phytase
using corn cob and corn bran is a novel and cheap way for the production of this important
enzyme and opens a new way for researchers to discover and explore this arena.