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The effect of CO2 in enhancing photosynthetic cofactor recycling for alcohol dehydrogenase mediated chiral synthesis in cyanobacteria
- Sengupta, Annesha, Sunder, Avinash Vellore, Sohoni, Sujata V., Wangikar, Pramod P.
- Journal of biotechnology 2019 v.289 pp. 1-6
- Lactobacillus kefiri, NADP (coenzyme), Synechococcus sp. PCC 7942, acetophenones, alcohol dehydrogenase, biocatalysts, biotransformation, carbon dioxide, carbon dioxide enrichment, glucose, nicotinamide, photosynthesis, stereoselective synthesis
- The light harvesting photosystem in cyanobacteria offers a potential pathway for the regeneration of the nicotinamide cofactor NADPH, thereby facilitating the application of cyanobacteria as excellent whole cell biocatalysts in oxidoreductase-mediated biotransformation. The use of cyanobacterial metabolism for cofactor recycling improves the atom economy of the process compared to the commonly employed enzyme-coupled cofactor recycling using enzymes such as glucose dehydrogenase. Here we report the asymmetric conversion of acetophenone to chiral 1-phenylethanol by recombinant Synechococcus elongatus PCC 7942 whole cell biocatalyst that expresses the NADPH dependent L. kefir alcohol dehydrogenase. Besides light, it was observed that carbon dioxide levels play a critical role in improving the bioconversion efficiency possibly due to the enhanced growth rate and improved cofactor availability at elevated CO2 levels. Complete reduction of acetophenone to optically pure (R)-1-phenylethanol at 99% enantiomeric excess was achieved within 6 h with a relatively low cell density of 0.66 g/l by coupling optimum light and CO2 levels and without the need for a co-substrate.