ENZYMATIC HYDROLYSIS OF RYE STRAW AND BERMUDAGRASS USING CELLULASES SUPPLEMENTED WITH â-GLUCOSIDASE

Enzymatic hydrolysis of acid-pretreated rye straw and Bermudagrass, lignocellulosic agricultural residuescommonly found in the southeastern U.S., has been investigated for bioconversion of the lignocellulosic materials intoreducing sugars. Cellulases supplemented with .-glucosidase were used as the biocatalysts for the bioconversion. The effectsof the cellulase and .-glucosidase loadings on the bioconversion efficiency were studied for both rye straw andBermudagrass. Increase of cellulase loading from 5 to 15 FPU (filter paper unit)/g biomass enhanced glucose production.Supplementation of .-glucosidase effectively improved the glucose production rate and cellulose conversion efficiency.Significant cellubiose was observed as an intermediate in the conversion process without the addition of .-glucosidase. When.-glucosidase was added to 25 CBU (cellobiase unit)/g biomass or higher in the enzymatic hydrolysis, there was no cellobioseaccumulation in the hydrolyzates. A cellulose conversion efficiency of 45% was achieved for pretreated Bermudagrass. Ryestraw was more resistant to enzymatic hydrolysis, with a conversion efficiency of 38%.