Wiring bacterial cells to electrodes

In this PhD project you will develop a technological platform that can interface living cells directly to electrodes via their cell membrane such that you can electrochemically interact with the quinone pool in their membranes. With this technology you will be able to monitor, as well as experimentally control, the quinone redox state, which is a major 'hub' in the electron-transport chain that is part of the bacterial bioenergetics. Such an interface would not only allow us to study bioenergetics in living cells, it would also pave the way to harness bioenergy in biofuel cell applications.
The objectives are:
1) To optimise conditions under which spheroplasts of Gram-negative and Gram-positive bacteria can bind to electrode surfaces without compromising the integrity of the cytoplasmic membrane.
2) To establish to which extend these spheroplasts are still metabolically active and are in this limited sense of the work, alive.
You will use well-established biochemical methods to remove the cell-wall and prepare spheroplasts. Then, the electrode surfaces will be specifically modified such that they are optimised for spheroplast binding. The stability of the surface-immobilised spheroplast will be tested by using an E. coli strain that expresses a green-fluorescent protein (GFP) and monitoring the fluorescence of the adsorbed spheroplast using epi-fluorescent microscopy. If the stability of the spheroplast is compromised, the cytoplasm will leak away from the surface, resulting in a reduction of the fluorescence.
You will establish to which degree the bacteria are metabolically active while immobilised on the surface. For instance, the succinate-menaquinone oxidoreductase (SQR) activity of B. subtilis can be monitored. It has been shown that for the native function (succinate oxidation by menaquinone reduction) additional energy of the proton motive force (pmf) is required. Thus, if succinate oxidation is observed, the spheroplasts are able to create a pmf of sufficient magnitude. If only fumarate reduction (the reverse reaction) is observed, the enzymes in immobilised spheroplasts are still active, but the spheroplast cannot form a physiologically relevant pmf.

For more information, please contact Lars Jeuken: +44 (0)113 343 3829 or [Email Address Removed]
To apply, please go to: https://studentservices.leeds.ac.uk/pls/banprod/bwskalog_uol.P_DispLoginNon