Furthermore, the silica layer prevents the accessibility ofmicroorganisms to carbohydrates inside the straw (Agbagla-Dohnani et al., 2003). Thus, removing the silica from rice straw canbe a proper strategy for increasing the accessible cellulose surfacearea to hydrolytic enzymes in the hydrolysis process. In this study,the effect of sodium carbonate pretreatment on the structure andsilica content of rice straw and its consequence on hydrolysis andfermentation steps were studied.