Effects of cellulase loading and substrate concentration on the enzymatic hydrolysis of corn stover

Corn stover, which was pretreated with an integrated wet-milling and alkali pretreatment method, was enzymatically hydrolyzed by a commercial cellulatic complex under conditions of a cellulase loading in the range of 1.5 ～30 FPU/g and a substrate concentration in the range of 10 ～40 g/L. The effects of cellulase loading and substrate concentration on reducing-sugar yield and hydrolysis reaction rate were investigated, and the mechanism of inhibiting hydrolysis reaction by lignin was discussed. A regression equation of reducing-sugar yield and cellulase loading, substrate concentration was obtained using the response surface methodology. It was shown that at a larger cellulase loading, reaction rate had a larger increase with increasing of substrate concentration. Adsorption of cellulase on lignin caused the inactivation of cellulase, which resulted in the reduction of hydrolysis reaction rate and reducing-sugar yield.