Team:CLSB-UK
BioPhotovoltaics
Project Summary
Synechocystis sp. PCC6803 is a model cyanobacterium that is often used in biophotovoltaic cells - these produce electricity in the form of electrons evolved from the bacterium when photolysis of water takes place. This all sounds great, but the downside is that the efficiency of the process is low - electrons are produced when water is split, but only a tiny fraction of them end up leaving the cell. Some success has been had in increasing efficiency of BPV cells by adding an external mediator but this approach is not sustainable in the long term should we want to run a BPV cell for an extended period of time. Additionally Synechocystis grows extremely slowly, meaning that transformations take a long time and can make the overall process of working with this bacterium difficult from a synthetic biology perspective.
This is where our vision comes in. We plan to amplify expression of the CmpA gene in Synechocystis, a gene that codes for a bicarbonate ion(HCO3-) membrane transporter protein. Increased uptake of bicarbonate ions has been linked to higher growth rates so we think that this would be a good place to start to make any additional work easier. After this, we intend to add two parts: BBa_K1172303 which produces riboflavin, and BBa_K1172501 which is a porin(channel protein across the cell membrane), with the goal of increasing the number of electrons evolved from the cell, and as such making potential BPV cells more efficient with this bacterium. We would also utilise a promoter from the registry to maximise expression of these parts, but we’re unsure which to use as of yet.. The difficulty lies in transformation of Synechocystis; it is picky as to which plasmids we can use, and any work would have to be done with replicative plasmids, as this organism is hexaploid - integrating anything into the genome proper would lie outside of our time constraints.
Our project is very applicable to global issues of sustainability and energy - BPV cells are a promising solution to provide cheap, sustainable power, but not much exists yet outside of proof-of-concept and research examples. We hope to aid the development of this exciting technology by carrying out these changes to Synechocystis. Additionally making this bacterium easier to work with from a synthetic biology point of view would help out any future teams or labs hoping to work in this area, in concordance with the community spirit of the IGEM competition.
