Effect of Lignin and Hemicellulose on Enzymatic Hydrolysis of Cellulose from Rice Straw

In this manuscript,the enzymatic hydrolysis of rice straw in three different forms: original(untreated),pretreated by dilute acid,and pretreated by a sequence of dilute acid and dilute alkali,were studied.The hydrolysis was carried out in an enzyme/substrate ratio of 20 FPU/g,8%(w/v) substrate concentration,45 ℃ for 72 h.The digestibility results suggested that the cellulose hydrolysis was greatly affected by the presence of hemicellulose and/or lignin in the rice straw.The cellulose conversion ratio 43.4% from dilute acid-treated rice straw was 2.6 times higher than that 16.8% from untreated rice straw,whereas from dilute acid and alkali rice straw such value was higher 3.6 times(60.6%).This result was probably due to the fact that the strong modification in the material structure caused by the hemicellulose and lignin removal from the rice straw.As a consequence,the cellulose fibers were separated being more susceptible to the enzymatic attack.It was concluded that the lower the hemicellulose and lignin in the rice straw,the higher efficiency of cellulose hydrolysis could be achieved at.