Team:Reading/Description

Project Description

We aim to produce a biological photovoltaic (BPV) using the cyanobacterium Synechocystis sp. PCC 6803 (hereafter referred to as Synechocystis). This year, we are taking on the project of the 2014 Reading team, and we plan to build on the successes of their project, by increasing the efficiency of the BPV, and also to improve the concept and the practical use of the fuel cell.

Background

Solar energy is the largest source of energy available to mankind, with ~120,000 terawatts hitting the planet’s surface each year1. Worldwide, this immense natural resource is tapped via the use of photovoltaic cells in solar panels. In recent years, the emerging field of synthetic biology has produced the biological photovoltaic, a solar fuel cell, which harnesses the process of photosynthesis in living organisms to produce electricity.


The maximum potential efficiency of photosynthesis as an energy capturing process is ~ 11%2, which is at the lower end of efficiency of the conventional photovoltaic fuel cell. However there are many advantages to the use of BPV’s. The process of photosynthesis removes carbon dioxide from the atmosphere, so the BPV acts as a carbon sink. Also, the components of a BPV are very cheap, making the devices easily affordable and effective for developing communities with low energy demands, as well as being simple to maintain.


We have chosen to continue to build a BPV using Synechocystis PCC 6803. There a several advantages to this cyanobacterium. As a photolithoautotroph, Synechocystis requires water, sunlight, carbon dioxide, and essential minerals, making it simple and easy to culture and grow in a fuel cell. Cyanobacteria also obtain energy from sunlight at efficiencies of 3-9%, which is higher than most green plants3. A major advantage of using our chosen species of Synechocystis is that a full genome sequence is available for this organsim4, and it is far easier to genetically modify than, for example, an algal cell. Synechocystis is also known to be spontaneously transformable, and is commonly used to produce mutant cyanobacteria for studies5.

Our Aims

We plan to improve many aspects of the project from last year’s team, taking the concept further.

  • Increase the number of electrons available to the electrodes by targeting the photosynthetic electron transport chain in Synechocystis.
  • Increase the transfer of electrons to the electrodes by inducing hyperpilation in the bacterium.
  • Improve the fuel cell design to increase efficiency, whilst keeping costs down, and keeping the cell simple and easy to maintain.
  • Produce effective biosafety measures to prevent our modified bacteria escaping, or having a damaging effect on humans or the environment.
  • Make sure our design complies with UK and EU regulations and is viable in the long term.


References
  1. Blankenship, R. E. et al, Comparing Photosynthetic and Photovoltaic Efficiencies and Recognizing the Potential for Improvement. Science 332, 805-809 (2011).
  2. Brenner, M. P. Engineering Microorganisms for Energy Production. (U.S. Department of Energy, 2006).
  3. Ducat, D. C., Way, J. C., Silver, P. A., Engineering cyanobacteria to generate high-value products. Trends in Biotechnology 29, 95-103 (2011).
  4. Kaneko, T. et al. Sequence Analysis of the Genome of the Unicellular Cyanobacterium Synechocystis sp. Strain PCC6803. II. Sequence Determination of the Entire Genome and Assignment of Potential Protein-coding Regions. DNA Res. 3, 109–136 (1996).
  5. Shen G, Boussiba S and Vermaas WFJ (1993) Synechocystis sp. PCC 6803 strains lacking photosystem I and phycobilisome function. Plant Cell 5: 1853–1863.

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