The nation’s reliance on fossil-based fuels creates problems for the environment and our national security. The production of a renewable source of motor fuels is required. We have designed a production pathway for synthesizing IBT biofuel from CO2, H2, and O2 using the genetically tractable and metabolically versatile bacte­rium, R. eutropha. The majority of the genes required for this pathway are already present in R. eutropha. Metabolic engineering strategies are being implemented to establish a semisynthetic pathway to produce IBT from CO2, H2, and O2. This IBT production pathway has the potential to affect two high-priority environmental con­cerns, capture of CO2 and production of an alternative nonfossil-based fuel.

Acknowledgments We thank John W. Quimby for critical review of this manuscript. D. S. is supported by the following foundations: Nijmeegs Universiteitsfonds (SNUF), Fundatie van de Vrijvrouwe van Renswoude te’s-Gravenhage, and Dr. Hendrik Muller’s Vaderlandsch Fonds. Other authors are supported, fully or in part, by the Advanced Research Projects Agency-Energy (ARPA-E) Electrofuels project. We wish to thank the ARPA-E directors and staff for their support.