No abstract

Effect of commercial cellulose enzymes was investigated by batch enzymatic hydrolysis at 15.0% (w/v) solid. It was found that the best commercial cellulose enzyme was Cellic ® CTec comparing to Accellerase 1000 TM and Accelerase 1500 TM . The Cellic ® CTec gave the highest reducing sugar concentration and rice straw conversion. Moreover, when the hydrolysate obtained from hydrolysis using Cellic ® CTec was fermented by Saccharomyces cerevisiae TISTR 5596, it would give the highest ethanol. In this study, the Cellic ® CTec was used for fed-batch prehydrolysis prior to ethanol production by simultaneous saccharification and fermentation (SSF) way at 20% (w/v) solid loading. It could produce 35.76 g/L or 4.6% (v/v) of ethanol concentration and 83.67 L/ton dry matter (DM) of yield.

Fuel ethanol production from lignocellulosic biomass requires a relatively high initial sugar concentration in hydrolysate. Raising the substrate and enzyme concentration in the batch hydrolysis will normally help to heighten sugar concentration. In this study, dilute sulfuric acid pretreatment was used for chemical pretreatment of rice straw. The effect of rice straw and commercial cellulase (Accelerase 1000 TM) loading were investigated. It was found that an increase in rice straw from 7.5 to 15.0 g/100 mL H 2 SO 4 raised the reducing sugar concentration from 27.70 ± 1.72 to 58.42 ± 1.23 g/L. At the high level of rice straw up to 20.0 g/100 mL H 2 SO 4 gave a slight increase in reducing sugar of 66.17 ± 0.00 g/L. On the contrary, the rice straw conversion decreased from 343.27 ± 1.29 to 286.22 ± 2.39 mg/g DS (Dry residue substrate) and holocellulose conversion slightly decreased from 47.02 ± 0.18 to 39.21 ± 0.33% (w/w) when the rice straw increased from 15.0 to 20.0 g/100 mL H 2 SO 4. The reducing sugar concentration increased from 52.98 ± 0.73 g/L to 64.61 ± 0.53 g/L and rice straw conversion changed from 293.44 ± 5.12 to 414.16 ± 0.19 mg/g DS, when the use of Accellerase 1000 TM increased from 10 to 45 FPU/g DS. It also found that the large amount of Accelerase 1000 TM loading (50 and 55 FPU/g DS) did not improve the reducing sugar and rice straw conversion.