초록
<P><B>Background</B></P><P>While most resources in biofuels were directed towards implementing bioethanol programs, 1-propanol has recently received attention as a promising alternative biofuel. Nevertheless, no microorganism has been identified as a natural 1-propanol producer. In this study, we manipulated a novel metabolic pathway for the synthesis of 1-propanol in the genetically tractable bacterium <I>Escherichia coli</I>.</P><P><B>Results</B></P><P><I>E. coli</I> strains capable of producing heterologous 1-propanol were engineered by extending the dissimilation of succinate via propionyl-CoA. This was accomplished by expressing a selection of key genes, i.e. (1) three native genes in the sleeping beauty mutase (Sbm) operon, i.e. <I>sbm</I>-<I>ygfD</I>-<I>ygfG</I> from <I>E. coli</I>, (2) the genes encoding bifunctional aldehyde/alcohol dehydrogenases (ADHs) from several microbial sources, and (3) the <I>sucCD</I> gene encoding succinyl-CoA synthetase from <I>E. coli</I>. Using the developed whole-cell biocatalyst under anaerobic conditions, production titers up to 150 mg/L of 1-propanol were obtained. In addition, several genetic and chemical effects on the production of 1-propanol were investigated, indicating that certain host-gene deletions could abolish 1-propanol production as well as that the expression of a putative protein kinase (encoded by <I>ygfD/argK</I>) was crucial for 1-propanol biosynthesis.</P><P><B>Conclusions</B></P><P>The study has provided a novel route for 1-propanol production in <I>E. coli</I>, which is subjected to further improvement by identifying limiting conversion steps, shifting major carbon flux to the productive pathway, and optimizing gene expression and culture conditions.</P>