(574a) Development of a Novel Bioprocess for CO2 Conversion to Biochemicals Using Synthetic Designed Proteins and Non-Growing Cells

We are developing a new bioprocess for the production of biofuels from CO₂ using renewable energy. Autotrophic organisms frequently grow slowly, rely on the Calvin cycle for carbon fixation, and can be challenging to engineer for high yields and productivities. We are working to address these challenges by replacing the Calvin cycle with artificial photosynthetic proteins and designed metabolic pathways that will operate in non-growing bacteria cells suspended in photobioreactors. Renewable electricity will be used to power LEDs that specifically energize the artificial photosynthetic pathway in the stationary cells. This will allow for the efficient conversion of CO₂ to biofuels and biochemicals such as glycerol.

We have developed a novel designed light harvesting complex that can split water and regenerate the ubiquitous biological cofactor NADH. At the same time, we have developed a synthetic metabolic pathway that utilizes NADH to reduce CO₂ to formaldehyde and then the formaldehyde is ligated to create glycerol using another designed enzyme (formolase). Once installed in E. coli, the pathways will allow for light-powered NAD(H) regeneration which will power CO₂ reduction to glycerol that is independent of the cellular metabolism. Thus the system will be operated in photobioreactors which will specifically energize the designed photosynthetic pathway in cells that are not growing.

The most recent results of this promising new platform will be presented, including performance metrics for the newly designed photoprotein, pathway fluxes through the carbon fixation pathway, and protein engineering results on key enzymes in the carbon fixation pathway.