초록
<P><B>Abstract</B></P> <P>To improve butanol fermentation efficiencies, semi-hydrolysate with low enzyme loading using H<SUB>2</SUB>SO<SUB>4</SUB> pretreated rice straw was designed, which preferably produced cellobiose with xylose (instead of glucose). Fermentation of semi-hydrolysates avoided carbon catabolite repression (CCR) and produced higher butanol yield to enzyme loading (0.0290 g U<SUP>−1</SUP>), a newly proposed parameter, than the conventional glucose-oriented hydrolysate (0.00197 g U<SUP>−1</SUP>). Further, overall butanol productivity was improved from 0.0628 g L<SUP>−1</SUP> h<SUP>−1</SUP> to 0.265 g L<SUP>−1</SUP> h<SUP>−1</SUP> during fermentation of undetoxified semi-hydrolysate by using high cell density. A novel simultaneously repeated hydrolysis and fermentation (SRHF) was constructed by recycling of enzymes and cells, which further improved butanol yield to enzyme loading by 183% and overall butanol productivity by 6.04%. Thus, semi-hydrolysate with SRHF is a smartly designed biomass for efficient butanol fermentation of lignocellulosic materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new strategy of semi-hydrolysis was proposed. </LI> <LI> Using semi-hydrolysate reduced enzyme loading and avoided CCR. </LI> <LI> New indexes: butanol yield to enzyme loading and overall butanol productivity. </LI> <LI> Simultaneously repeated hydrolysis and fermentation (SRHF) was designed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>