초록
<P>For the efficient production of target metabolites from carbohydrates, syngas, or H<SUB>2</SUB>-CO<SUB>2</SUB> by genetically engineered <I>Moorella thermoacetica</I>, the control of acetate production (a main metabolite of <I>M. thermoacetica</I>) is desired. Although propanediol utilization protein (PduL) was predicted to be a phosphotransacetylase (PTA) involved in acetate production in <I>M. thermoacetica</I>, this has not been confirmed. Our findings described herein directly demonstrate that two putative PduL proteins, encoded by Moth_0864 (<I>pduL1</I>) and Moth_1181 (<I>pduL2</I>), are involved in acetate formation as PTAs. To disrupt these genes, we replaced each gene with a lactate dehydrogenase gene from <I>Thermoanaerobacter pseudethanolicus</I> ATCC 33223 (<I>T-ldh</I>). The acetate production from fructose as the sole carbon source by the <I>pduL1</I> deletion mutant was not deficient, whereas the disruption of <I>pduL2</I> significantly decreased the acetate yield to approximately one-third that of the wild-type strain. The double-deletion (both <I>pduL</I> genes) mutant did not produce acetate but produced only lactate as the end product from fructose. These results suggest that both <I>pduL</I> genes are associated with acetate formation via acetyl-coenzyme A (acetyl-CoA) and that their disruption enables a shift in the homoacetic pathway to the genetically synthesized homolactic pathway via pyruvate.</P><P><B>IMPORTANCE</B> This is the first report, to our knowledge, on the experimental identification of PTA genes in <I>M. thermoacetica</I> and the shift of the native homoacetic pathway to the genetically synthesized homolactic pathway by their disruption on a sugar platform.</P>