Abstract
When the variables (inoculum size, methanol and yeast extract) identified to affect phytase production by Bacillus subtilis US417 using Plackett-Burman design were optimized by RSM, a high enzyme production of 112 U/g of wheat bran was attained. Overall, a 5-fold improvement in phytase production was achieved. In SSF, on the other hand, a 4-fold enhancement in enzyme titer was attained (85 U/g of wheat bran). Based on these findings, phytase productivity was higher in SF [2.3 U/(g x h)] than in SSF [1.2 U/(g x h)].