Researchers from the Qingdao Institute of Bioenergy and Bioprocess Technology (China), applied a consolidated bioprocessing strategy to integrate photosynthetic biomass production and microbial conversion producing ethanol together into the photosynthetic bacterium, Synechocystis sp. PCC6803. The resulting organism can directly convert carbon dioxide to ethanol in one single biological system.
A Synechocystis sp. PCC6803 mutant strain with significantly higher ethanol-producing efficiency (5.50 g L−1, 212 mg L−1 day−1) compared to previous research was constructed by genetically introducing pyruvate decarboxylase from Zymomonas mobilis and overexpressing endogenous alcohol dehydrogenase through homologous recombination at two different sites of the chromosome, and disrupting the biosynthetic pathway of poly-β-hydroxybutyrate.
In total, nine alcohol dehydrogenases from different cyanobacterial strains were cloned and expressed in E. coli to test ethanol-producing efficiency. The effects of different culturing conditions including tap water, metal ions, and anoxic aeration on ethanol production were evaluated.—Gao et al.
Zhengxu Gao, Hui Zhao, Zhimin Li, Xiaoming Tan and Xuefeng Lu (2012) Photosynthetic production of ethanol from carbon dioxide in genetically engineered cyanobacteria. Energy Environ. Sci., 5, 9857-9865 doi: 10.1039/C2EE22675H