초록
<P><B>Abstract</B></P> <P>Succinate is an important commodity chemical currently used in the food, pharmaceutical, and polymer industries. It can also be chemically converted into other major industrial chemicals such as 1,4-butanediol, butadiene, and tetrahydrofuran. Here we metabolically engineered a model cyanobacterium <I>Synechococcus elongatus</I> PCC 7942 to photosynthetically produce succinate. We expressed the genes encoding for α-ketoglutarate decarboxylase and succinate semialdehyde dehydrogenase in <I>S. elongatus</I> PCC 7942, resulting in a strain capable of producing 120mg/L of succinate. However, this recombinant strain exhibited severe growth retardation upon induction of the genes encoding for the succinate producing pathway, potentially due to the depletion of α-ketoglutarate. To replenish α-ketoglutarate, we expressed the genes encoding for phosphoenolpyruvate carboxylase and citrate synthase from <I>Corynebacterium glutamicum</I> into the succinate producing strain. The resulting strain successfully restored the growth phenotype and produced succinate with a titer of 430mg/L in 8 days. These results demonstrated the possibility of photoautotrophic succinate production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heterologous α-ketoglutarate decarboxylase and succinate semialdehyde dehydrogenase were expressed in <I>S. elongatus</I> PCC 7942. </LI> <LI> Expression of PEP carboxylase rescued growth retardation caused by introduction of succinate production pathway. </LI> <LI> Succinate secretion increased with pH of culture medium. </LI> <LI> 430mg/L of succinate was produced under photosynthetic conditions. </LI> </UL> </P>