초록
<P><B>Abstract</B></P> <P> <I>Clostridium saccharoperbutylacetonicum</I> N1-4 is well known as a hyper-butanol producing strain. However, little information is available concerning its butanol production mechanism and the development of more robust strains. In this study, key biosynthetic genes (either endogenous or exogenous) including the <I>sol</I> operon (<I>bld</I>-<I>ctfA</I>-<I>ctfB</I>-<I>adc</I>), <I>adhE1</I>, <I>adhE1<SUP>D485G</SUP> </I>, <I>thl</I>, <I>thlA1<SUP>V5A</SUP> </I>, <I>thlA<SUP>V5A</SUP> </I> and the expression cassette EC (<I>thl</I>-<I>hbd-crt-bcd</I>) were overexpressed in <I>C. saccharoperbutylacetonicum</I> N1-4 to evaluate their potential in enhancement of butanol production. The overexpression of <I>sol</I> operon increased ethanol production by 400%. The overexpression of <I>adhE1</I> and <I>adhE<SUP>D485</SUP> <SUP>G</SUP> </I> resulted in a 5.6- and 4.9-fold higher ethanol production, respectively, producing final acetone-butanol-ethanol (ABE) titers (30.6 and 30.1gL<SUP>−1</SUP>) of among the highest as ever reported for solventogenic clostridia. The most significant increase of butanol production (by 13.7%) and selectivity (73.7%) was achieved by the overexpression of EC. These results provides a solid foundation and essential references for the further development of more robust strains.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Overexpression of <I>sol</I> operon enhanced acid re-assimilation and ethanol titer. </LI> <LI> Overexpression of <I>adhE</I> increased ethanol and total ABE titer dramatically. </LI> <LI> Overexpression of <I>thl</I> decreased ethanol and increased butanol production slightly. </LI> <LI> Overexpression of cassette EC improved butanol titer and selectivity. </LI> </UL> </P>