초록
<P><B>Abstract</B></P> <P>Production of cellulosic biofuels has drawn increasing attention. However, currently no microorganism can produce biofuels, particularly butanol, directly from cellulosic biomass efficiently. Here we engineered a cellulolytic bacterium, <I>Clostridium cellulovorans</I>, for <I>n</I>-butanol and ethanol production directly from cellulose by introducing an aldehyde/alcohol dehydrogenase (<I>adhE2</I>), which converts butyryl-CoA to <I>n</I>-butanol and acetyl-CoA to ethanol. The engineered strain was able to produce 1.42g/L <I>n</I>-butanol and 1.60g/L ethanol directly from cellulose. Moreover, the addition of methyl viologen as an artificial electron carrier shifted the metabolic flux from acid production to alcohol production, resulting in a high biofuel yield of 0.39g/g from cellulose, comparable to ethanol yield from corn dextrose by yeast fermentation. This study is the first metabolic engineering of <I>C. cellulovorans</I> for <I>n</I>-butanol and ethanol production directly from cellulose with significant titers and yields, providing a promising consolidated bioprocessing (CBP) platform for biofuel production from cellulosic biomass.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Engineering cellulolytic <I>C. cellulovorans</I> for <I>n</I>-butanol production from cellulose. </LI> <LI> Fermentation with artificial electron carriers to shift acid to alcohol production. </LI> <LI> Produced <I>n</I>-butanol and ethanol at a titer >3 g/L and yield >0.39 g/g from cellulose. </LI> <LI> Can be used to produce biofuel from cellulosic biomass in a consolidated bioprocess. </LI> </UL> </P>