Engineering Cyanobacteria with Enhanced Growth in Simulated Flue Gases for High-Yield Bioethanol Production

Abstract Flue gases emitted from industrial plants mainly contribute to global CO2 emissions. Sequestrations of CO2 from the flue gas could reduce the impact of CO2 on global warming. In this study, recombinant cyanobacterial strains with enhanced photosynthetic activity, cell growth, and ethanol production were generated by co-overexpressing ictB, ecaA, and groESL, along with a heterologous ethanol synthesis pathway (pdc-adhII genes from Zymomonas mobilis) in S. elongatus PCC7942. The engineered S. elongatus PCC7942 exhibited a significant improvement in cell growth and ethanol production under a simulated flue gas consisted of 25% CO2, 80-90 ppm SO2, 90-100 ppm NO. The present work represents the first attempt of direct photoconversion of CO2 from flue gases to ethanol via expression of ictB, ecaA, groESL, and pdc-adhII in S. elongatus. The transgenic cyanobacterium becomes useful for sequestrations of CO2 directly from flue gases with the simultaneous production of bioethanol.