초록
<P><B>Abstract</B></P> <P>To investigate the effect of delignification on enzymatic saccharification and ethanol fermentation of sugarcane bagasse (SCB), NaClO, NaOH, and Na<SUB>2</SUB>CO<SUB>3</SUB> were used to prepare SCB with different lignin contents. We found that a lignin content of approximately 11% was sufficient for enzymatic saccharification and fermentation. Based on this result, an economical delignification pretreatment method using a combination of acid and alkali (CAA) was applied. Lignin content of 11.7% was obtained after CAA pretreatment with 0.5% w/v H<SUB>2</SUB>SO<SUB>4</SUB> at 140 °C for 10 min and 1.0% w/v NaOH at 90 °C for 60 min. Presaccharification-simultaneous saccharification and fermentation (P-SSF) of the CAA-pretreated SCB resulted in an ethanol concentration of 43.8 g/L and an ethanol yield of 81.7%, with an enzyme loading of 15 FPU/g–CAA-pretreated SCB. Enzyme activities (filter paper, carboxymethyl cellulase, and <I>β</I>-glucosidase activities) were determined in liquid phase during P-SSF, indicating that the residual cellulase activity could be further used. Thus, fed-batch P-SSF was carried out, and an ethanol concentration of 43.1 g/L and an ethanol yield of 80.4% were obtained with an enzyme loading of 10 FPU/g–CAA-pretreated SCB. Fed-batch P-SSF was found to be effective to reduce enzyme loading.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SCB containing lignin of about 11% allows efficient conversion of SCB to ethanol. </LI> <LI> CAA pretreatment delignified SCB to lignin content of 11.7%. </LI> <LI> Ethanol concentration of 43.8 g/L was obtained after P-SSF of CAA-pretreated SCB. </LI> <LI> Fed-batch P-SSF reduced enzyme loading without affecting fermentation performance. </LI> </UL> </P>