Fermentation of rice straw raw material to bioethanol using consortium enzyme

Rice straw is one of the abundant lignocellulosic agricultural by-product in Indonesia. Rice straw has several characteristics that make it a potential raw material for bioenergy production such as ethanol. It contain high cellulose and hemicelluloses that can be hydrolyzed into fermentable sugars. This study aimed to hydrolyze rice straw cellulose and hemicellulose using xylanase, cellulose, and xylose isomerase enzymes. 2% H2SO4 was used in pretreatment before the rice straw hydrolyzed with consortium enzymes. Concentrations of rice straw substrate was made to 5%, 10%, 15%, and 20% (w/v) and also made 1:1, 1:2, and 1:3 volume ratio between substrate and enzymes. The results showed that the highest rate of bioethanol obtained from 10% (w/v) rice straw substrate and enzyme activity in consortium was 0.279 U/mL (xylanase), 0.329 U/mL (cellulase), and 0.024 U/mL (xylose isomerase). The hydrolyzate was fermented by Saccharomyces cerevisiae BJ1824 and produce 8.81x10−2 %(v/v) ethanol measured by Gas Chromatography (GC).