Synthetic Design of Photosynthetic Hydrocarbon Production Systems

Photosynthetic hydrocarbon production represents one of the most direct and efficient route for ‘drop-in’ biofuels. Hydrocarbon, especially some terpene hydrocarbons, have superior thermochemical and thermophysical properties toward broad  fuel applications. Despite the potential, most of the current hydrocarbon biofuel platforms are based on heterotrophic microorganisms, which has much lower carbon and energy efficiency as compared to ethanol production. With the recent DOE EERE and DOE ARPA supports, we have developed several disruptive platforms for photosynthetic hydrocarbon production in higher plants, green algae and cyanobacteria. For higher plants, we have successfully coupled the photorespiration production rechanneling, carbon concentrating mechanisms with terpenoid hydrocarbon biosynthesis to significantly increase the yield to the record-level of 3% of dry biomass. The further integration of synthetically designed carbon storage organelle will increase the terpenoid hydrocarbon accumulation toward improved economics and sustainability for fuel production. In both cyanobacteria and green algae, we successfully engineered volatile-based terpene production system to enable simplified fuel collection. For all platforms, multiple genes and functional modules were designed and implemented for the engineering. Overall, our research has employed the latest synthetic biology techniques to enable the direct hydrocarbon production from photosynthetic systems at appreciable levels. The research laid down the foundation for an alternative approach for hydrocarbon biofuel production with much better carbon and energy efficiency as compared to the current platforms.