Metabolic Engineering in Synechocystis PCC 6803 for the Production of Butanol

Fossil fuel limitations have been a world wide problem from both energy resource perspective and global peace perspective. The consequence of this is an urgent demand of new sustainable energy resources. 1-butanol is a potential fuel substitute because of its high energy density, less explosive, low vapour pressure and high flash point. In addition to these advantages, 1-butanol can be blended into gasoline in any ratio, and no specific engine is required. As a photosynthetic microorganism, which lives on light, CO₂ and water, cyanobacteria can be used as an ideal platform to convert CO₂ into carbon based valuable compounds. Some pioneer study has been done by introducing various of enzymes from different organisms into Synechococcus elongatus PCC 7942 and Synechocystis PCC 6803 for the production of 1-butanol and isobutanol. In this study, for improving the productivity of butanol, selected exogenous and endogenous genes encoding enzymes which can constitute a metabolic pathway able to catalyze Synechocystis intermediate metabolites to 1-butanol, are expressed on the genome of wild type cells. A series of integrative vectors, which can generate stable chromosomal recombinations are used in order to introduce synthetic pathways and knock out competing pathways at the same time. Carbon and cofactor flux in the engineered strains will be examined as well as the comparison of final product titers.