Enzymatic Hydrolysis of Rice Straw: Process Optimization

Abstract

Rice straw consists of cellulose, hemicellulose and lignin. Cellulose is the most abundant component that present in the rice straw. Through enzymatic hydrolysis of cellulose, fermentable sugars are produced in the present of cellulases. In this study, untreated rice straw that is abundance in Malaysia was used as feedstock for exoglucanase production and enzymatic hydrolysis. Under solid substrate fermentation, exoglucanase was produced by locally isolated Aspergillus niger using untreated rice straw as sole carbon source. Subsequently, the untreated rice straw was hydrolyzed by the extracted exoglucanase, which obtained from solid substrate fermentation (SSF) to optimize the production of fermentable sugar based on three different factors, i.e. initial pH, substrate concentration, and enzyme concentration. An exoglucanase with a maximum activity of 46.45 FPU/g of rice straw was obtained from SSF produced by locally isolated A. niger. The optimum parameters obtained for the hydrolysis were at pH 6.0, 12% (w/v) of substrate concentration and with enzyme activity of 10 U/g of rice straw. The fermentable sugar concentration obtained with these parameters was 3.62 g/L.