초록
Lactate is an important industrial material with numerous potential applications, and its production from carbon dioxide is very attractive. d-Lactate is an essential monomer for production of thermostable polylactide. The photoautotrophic prokaryote cyanobacterium Synechocystis sp. PCC 6803 represents a promising host for biosynthesis of d-lactate from CO<SUB>2</SUB> as it only contains d-lactate dehydrogenase. The production of d-lactate from CO<SUB>2</SUB> by an engineered strain of Synechocystis sp. PCC 6803 with overexpressing d-lactate dehydrogenase and a soluble transhydrogenase has been reported recently. Here, we report an alternative engineering strategy to produce d-lactate from CO<SUB>2</SUB>. This strategy involves blocking two competitive pathways, the native poly-3-hydroxybutyrate and acetate pathways from the acetyl-CoA node, and introducing a more efficient d-lactate dehydrogenase into Synechocystis sp. PCC 6803. The engineered strain of Synechocystis sp. PCC 6803 was capable of producing 1.06g/L of d-lactate from CO<SUB>2</SUB>. This alternative strategy for the production of optically pure d-lactate could also be used to produce other acetyl-CoA-derived chemicals from CO<SUB>2</SUB> by using engineered cyanobacteria.