A synthetic biology approach to improving cyanobacterial chemical production

Chemical production in photosynthetic organisms is a nascent technology, with great promise for renewable energy, specifically for capture of CO₂ to replace dwindling fossil carbon supply. Photosynthetic organisms have the ability to directly fix carbon dioxide eliminating the need for fermentable sugar feedstocks. While genetic engineering tools are readily available for model organisms such as Escherichia coli and Saccharomyces cerevisiae, this is not the case for cyanobacteria. We have previously engineered production of the chemical feedstock 2,3-butanediol (23BD) from the model cyanobacterium Synechococcus elongatus PCC 7942. In an effort to further enhance chemical production in cyanobacteria we are exploring the optimization of 23BD production by varying ribosomal binding site and promoter strength, operon organization, and gene expression at the transcriptional and translational level. The resulting engineered strains exhibited enhanced total carbon fixation and 23BD production, representing a significant step toward optimized carbon capture. We concurrently observed an increase in oxygen evolution correlating to high carbon redirection away from metabolism, indicating the possibility for increase in photosynthetic efficiency overall.