Overview: Global human energy consumption is expected to increase from 14.9 terawatts (TW) to 23.4 TW by 2030. Although there is more than sufficient solar energy to meet this demand, efficient means to concentrate this diffuse energy and store it as fuels have not yet been developed. Photosynthesis, the biological process for reduction of carbon dioxide to fuels using solar energy, is, under most natural conditions, limited not by light but by the rate of carbon reduction. The long term goal of this research is to improve the efficiency of photosynthesis. The major aim of this project is to demonstrate the ability to divert energy from the ordinary linear electron flow of photosynthesis to alternative, fuelproducing sinks in a regulatable fashion when native carbon fixation pathways are saturated. The strategy to be implemented is to engineer an intercellular, plug-and-play platform (PNP) that will move electrons and/or reduced chemical shuttles from modified photosynthetic source cells to independently engineered fuel production modules, thus redistributing excess photosynthetically captured energy to productive pathways where it can be stored. Three different means to transfer energy between species will be developed: (1) optimization of natural extracellular electron transfer pathways via electrochemically guided metabolic engineering, (2) construction of artificial bionanowires, and (3) implementation of a soluble chemical redox shuttle. To develop these pathways, a wide variety of synthetic and analytic techniques will be employed including synthetic biological, electrochemical, molecular biological, physiological, spectroscopic, and photochemical. Intellectual Merit: The realization of this project will require radical manipulation of the fundamental biology of photosynthesis and development of novel synthetic biological, chemical and analytical techniques. The project is organized around four specific aims. (1) To characterize components of and control flux through the natural extracellular electron transfer pathway of the model cyanobacterium Synechocystsis sp. PCC6803. (2) To construct artificial systems to abstract reducing equivalents from Photosytem 1 that compete with natural electron acceptors only under light saturated conditions. (3) To develop artificial means to move reducing equivalents outside of the cytoplasm. (4) To produce artificial fuel production modules that require only reducing equivalents and carbon dioxide as inputs. Success in any one of these areas will have consequential scientific intellectual impact. First, tunable tools for controlling single and multiple gene expression in cyanobacteria will be developed that can be employed by researchers addressing any number of research questions. Second, knowledge of the existing electron transfer pathways of Synechocystis will be significantly augmented. Third, new physicochemical tools for probing microbial physiology will be established. Fourth, artificial, protein-based, biocompatible conductive nanowires will be constructed. These portable wires will offer both a platform for studying extracellular electron transfer mechanisms and an opportunity to confer the ability to transfer electrons outside of the cell to novel microbes. Fifth, we will develop posttranscriptionally regulated means to control electron flow between different intracellular pathways. Sixth, novel chemical and biological fuel producing strategies will be implemented in fully portable modular units. Broader Impacts: The broader impacts of this project are fourfold. First, the scientific goal of this program is to re-invent the machinery of photosynthesis for enhanced efficiency. This would allow substantial increases in mankinds capacity to produce fuels, profoundly improving both global energy and food security. Second, this project will provide research training opportunities for in excess of 14 trainees at the post-doctoral, graduate and undergraduate levels including both women and underrepresented minorities. Third, this international and interdisciplinary project will build bridges between the US and UK scientific communities in a range of critical scientific areas including synthetical biology, photosynthetic physiology, catalysis, and metabolic regulation. These are diverse scientific subdisciplines that typcially do not work together. Fourth, the researchers of this project will engage and inform both the public and other investigators through such activities as peer reviewed publications, public science lectures, blogs, websites, and popular science articles.
|Effective start/end date||6/1/14 → 5/31/19|
- NSF: Directorate for Biological Sciences (BIO): $465,247.00