While solar bioenergy is potentially an abundant and environmentally benign energy source, natural photosynthesis is relatively inefficient owing to slow steps in the conversion of carbon dioxide into biomass. This project seeks to increase energy capture by photosynthesis by diverting energy away from the normal slow steps to potentially more efficient processes. The first major goal of the project is to demonstrate that energy, in the form of electrical current produced by photosynthetic organisms, can be transmitted from a photosynthetic, energy capturing cell to an energy-storing "factory cell" via biological nanowires (biowires). The second major goal of the proposed work is to show that the factory cell can be engineered to use energy to produce useful fuel compounds.

Broader Impacts: This project will create the foundation for new directions in bioenergy research, with potential for dramatic increases in the efficiency of solar energy capture and storage, while training the next generation of scientists and engineers needed to compete in emerging areas of bioenergy and biotechnology. The project will demonstrate that energy can be transferred directly between cells as bio-electricity. Furthermore, the biowire to be developed will serve as a future generic connector for electrically connecting distinct cell types to create novel, functional biofilms. The photosynthetic components constructed in this project will serve as prototypes to establish a new design paradigm. In addition to these benefits, the project will 1) provide valuable resources to catalyze other important research projects, 2) train undergraduate and graduate students and postdoctoral fellows in areas of technology relevant to critical national needs, 3) establish productive international collaborations, and 4) disseminate information relevant to basic and applied research and development in energy and biotechnology.

Project Report

Intellectual Impact Metabolic engineers can insert foreign genes in microorganisms, thereby causing them to produce valuable compounds, including pharmaceuticals and fuels. Production yields, however, vary greatly among species. Escherichia coli is easy to use, but is not necessarily the best species for the production of every product. One original goal of this project was to engineer a strain of Shewanella oneidensis that consumed electrons and produced high yields of liquid fuel. Several other species (Methylococcus capsulatus, Ralstonia eutropha) can survive on electrons as a sole source of reducing power, so tools and techniques for the transformation of these candidate species was devised. This approach expands the scope of the Plug and Play project and diversifies the risk. Broader Impacts This project offers a significant return on investment to taxpayers. Genetic tools that were developed for the modification of a self-mobilizing plasmid within living bacterial cells makes it easy to introduce DNA into a wide range of other. Synthetic biologists could use this approach to overcome their almost exclusive reliance upon Escherichia coli. The Plug and Play project offers exceptional interdisciplinary training to young scientists. The post-doctoral fellow and technicians who were trained during this project will continue to enhance the productivity and competitiveness of the U.S. economy, and that of the U.K., for many years to come.

National Science Foundation (NSF)
Emerging Frontiers (EF)
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Gregory W. Warr
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Emory University
United States
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