Effect of alkaline pretreatment on enzymatic hydrolysis of rice straw.

Mild alkaline pretreatment and enzymatic hydrolysis of rice straw were performed.The Scanning Electron Microscopic(SEM) analysis of untreated and treated rice straw was performed.The effects of the pretreatment conditions on the content and lose ratio of hemicellulose,cellulose,lignin were studied.Alkaline pretreatment was evaluated for conversion of rice straw hemicellulose and cellulose to reducing sugars.The results showed that alkaline pretreatment dropped the content of lignin but increased that of cellulose and the cellulose surface area available to cellulose and accelerated the enzymatic saccharification of pretreated rice straw.The maximum yield of reducing sugars from rice straw by alkaline pretreatment(2%NaOH,w/v;60 ℃;ratio of solid-liquid,1﹕12,w/v;24 h) and enzymatic saccharification(45 ℃,pH5.0,120 h) using 31.2 mg enzyme preparation per g of substrate was 790.3 mg per g of rice straw.The ratio of enzymatic saccharification was 81.01%.SEM showed that the porosity increased and the mechanical tissue of rice straw was exposed,thus the effective specific surface area available to enzymatic hydrolysis of rice straw increased and the ratio of enzymatic saccharification accelerated.