초록
<P><B>Abstract</B></P> <P>In this study, Rubisco-based engineered <I>Escherichia coli</I>, containing two heterologous enzymes of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoribulokinase (PrkA), has been shown to be capable of the <I>in situ</I> recycling of carbon dioxide (CO<SUB>2</SUB>) during glycolysis. Two alternative approaches have been proposed to further enhance the carbon flow from glycolysis to a Rubisco-based pathway through the non-oxidative pentose phosphate pathway (NOPPP). The first is achieved by elevating the expression of transketolase I (TktA) and the second by blocking the native oxidation–decarboxylation reaction of <I>E. coli</I> by deleting the <I>zwf</I> gene from the chromosome (designated as JB/pTA and MZB, respectively). Decreases in the CO<SUB>2</SUB> yield and the CO<SUB>2</SUB> evolution per unit mole of ethanol production by at least 81% and 40% are observed. It is demonstrated in this study that the production of one mole of ethanol using <I>E. coli</I> strain MZB, the upper limit of CO<SUB>2</SUB> emission is 0.052mol.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Carbon flux is directed to the Rubisco-based engineered pathway during glycolysis. </LI> <LI> Non-oxidative pentose phosphate pathway (NOPPP) is essential for CO<SUB>2</SUB> recycling. </LI> <LI> The enhancement of the NOPPP can be achieved by elevated expression of TktA. </LI> <LI> Alternative method is to eliminate the competition of the OPPP by deleting <I>zwf</I> gene. </LI> <LI> The respective decreases in the CO<SUB>2</SUB> yield and CO<SUB>2</SUB>/ethanol are at-least 81% and 40%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>