Synthetic biology approach to rewire carbon metabolism for efficient photoautotrophic chemical production

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Climate change has spurred efforts to reduce net carbon dioxide (CO2) emissions. To address this issue, photosynthetic microorganisms will be engineered to recycle CO2 to produce biofuels or high-value chemicals. Undergraduate and graduate students will participate in this project. They will gain perspective on connections between biochemistry, microbiology, and bioengineering. The project results will be integrated with science and engineering education at the high school and college levels. Mentoring will be extended to high school students, including those from underrepresented groups. This will provide them with the opportunity to perform research in an academic setting. This project will evaluate a strategy to improve CO2 fixation that involves rewiring carbon metabolism in cyanobacteria. Cyanobacteria can directly convert solar energy and CO2 to biofuels and bioproducts. Engineered cyanobacteria can produce a variety of compounds, but the productivities are too low to be commercially appealing. Also, current large-scale photosynthetic production schemes rely on natural sunlight for energy, thereby limiting production to daylight hours. The proposed production system is designed to overcome these limitations. It has been shown previously that improvement of RuBisCO, the CO2 fixation enzyme, is very challenging. Thus, this project will develop an alternative strategy to improve carbon fixation by increasing intracellular levels of the substrate for RuBisCO and directing carbon flux towards chemical production. The strategies developed will also serve as tools for probing and understanding phototrophic behavior and metabolism. This approach addresses many of the issues raised concerning the commercial feasibility of cyanobacterial chemical production. The proposed engineering cyanobacteria to build chemicals from CO2 has the potential to result in more efficient, economical, and controllable production systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.