초록
<P><B>Abstract</B></P> <P>The acidogenic <I>Clostridium tyrobutyricum</I> has recently been metabolically engineered to produce n-butanol. The objective of this study was to obtain a comprehensive understanding as to how butanol production was regulated in <I>C. tyrobutyricum</I> to guide the engineering of next-generation strains. We performed a comparative proteomics analysis, covering 78.1% of open reading frames and 95% of core enzymes, using wild type, ACKKO mutant (Δ<I>ack</I>) producing 37.30g/L of butyrate and ACKKO-<I>adhE2</I> mutant (Δ<I>ack</I>-<I>adhE2</I>) producing 16.68g/L of butanol. In ACKKO-<I>adhE2</I>, the expression of most glycolytic enzymes was decreased, the thiolase (<I>thl</I>), acetyl-CoA acetyltransferase (<I>ato</I>), 3-hydroxybutyryl-CoA dehydrogenase (<I>hbd</I>) and crotonase (<I>crt</I>) that convert acetyl-CoA to butyryl-CoA were increased, and the heterologous bifunctional acetaldehyde/alcohol dehydrogenase (<I>adhE2</I>) catalyzing butanol formation was highly expressed. The apparent imbalance of energy and redox was observed due to the downregulation of acids production and the addition of butanol synthesis pathway, which also resulted in increased expression of chaperone proteins and glycerol-3-phosphate dehydrogenase (<I>glpA</I>) and the silence of sporulation transcription factor Spo0A (<I>spo0A</I>) as the cellular responses to butanol production. This study revealed the mechanism of carbon redistribution, and limiting factors and rational metabolic cell and process engineering strategies to achieve high butanol production in <I>C. tyrobutyricum</I>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A complete proteomics profiling of C. tyrobutyricum with 78.1% coverage was established. </LI> <LI> Integrated carbon redirections led to high butanol production by engineered strain. </LI> <LI> Redistributed redox could limit butanol production. </LI> <LI> Cellular responses to butanol production were identified. </LI> </UL> </P>