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Corn stover is the most abundant agricultural residue in China and a valuable reservoir for bioethanol production. In this study, we proposed a process for producing bioethanol from corn stover; the pretreatment prior to presaccharification, followed by simultaneous saccharification and fermentation (SSF) by using a flocculating Saccharomyces cerevisiae strain, was optimized. Pretreatment with acid–alkali combination (1% H2SO4, 150°C, 10 min, followed by 1% NaOH, 80°C, 60 min) resulted in efficient lignin removal and excellent recovery of xylose and glucose. A glucose recovery efficiency of 92.3% was obtained by enzymatic saccharification, when the pretreated solid load was 15%. SSF was carried out at 35°C for 36 hr after presaccharification at 50°C for 24 hr, and an ethanol yield of 88.2% was achieved at a solid load of 15% and an enzyme dosage of 15 FPU/g pretreated corn stover. [ABSTRACT FROM AUTHOR]

To investigate the effect of delignification on enzymatic saccharification and ethanol fermentation of sugarcane bagasse (SCB), NaClO, NaOH, and Na 2 CO 3 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 2 SO 4 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 β -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. [ABSTRACT FROM AUTHOR]