초록
<P><B>Background</B></P><P>Production of the versatile bulk chemical 1,2-propanediol and the potential biofuel 1-propanol is still dependent on petroleum, but some approaches to establish bio-based production from renewable feed stocks and to avoid toxic intermediates have been described. The biotechnological workhorse <I>Corynebacterium glutamicum</I> has also been shown to be able to overproduce 1,2-propanediol by metabolic engineering. Additionally, <I>C. glutamicum</I> has previously been engineered for production of the biofuels ethanol and isobutanol but not for 1-propanol.</P><P><B>Results</B></P><P>In this study, the improved production of 1,2-propanediol by <I>C. glutamicum</I> is presented. The product yield of a <I>C. glutamicum</I> strain expressing the heterologous genes <I>gldA</I> and <I>mgsA</I> from <I>Escherichia coli</I> that encode methylglyoxal synthase gene and glycerol dehydrogenase, respectively, was improved by additional expression of alcohol dehydrogenase gene <I>yqhD</I> from <I>E. coli</I> leading to a yield of 0.131 mol/mol glucose. Deletion of the endogenous genes <I>hdpA</I> and <I>ldh</I> encoding dihydroxyacetone phosphate phosphatase and lactate dehydrogenase, respectively, prevented formation of glycerol and lactate as by-products and improved the yield to 0.343 mol/mol glucose. To construct a 1-propanol producer, the operon <I>ppdABC</I> from <I>Klebsiella oxytoca</I> encoding diol dehydratase was expressed in the improved 1,2-propanediol producing strain ending up with 12 mM 1-propanol and up to 60 mM unconverted 1,2-propanediol. Thus, B<SUB>12</SUB>-dependent diol dehydratase activity may be limiting 1-propanol production.</P><P><B>Conclusions</B></P><P>Production of 1,2-propanediol by <I>C. glutamicum</I> was improved by metabolic engineering targeting endogenous enzymes. Furthermore, to the best of our knowledge, production of 1-propanol by recombinant <I>C. glutamicum</I> was demonstrated for the first time.</P>