Corn flour is chosen as the best carbon source and the best nitrogen source is soybean meal,using Bacillus subtilis as the neutral protease producer.Phosphate increases the protease production.When Na_2HPO_4 and KH₂PO_4 were not added in the medium,Ca~2+ and Mg~2+ at the given concentration cause inhibition on protease production.Ca~2+ and Mg~2+ at 1 mmol/L result in 12% and 8% increase in the enzyme production,respectively,with the addition of Na_2HPO_4 and KH₂PO_4 in the medium;however,higher concentration of Ca~2+ and Mg~2+ have an inhibitory effect on the enzyme production.Feeding of corn flour(10g/L) and soybean meal(7.5g/L) at 11,18,24 h results in 96% increase in protease yield and 112% increase in protease productivity when compared to the values obtained for batch culture.