Coherent electron transport in energy generation processes by electrogenic microorganisms
We seek applications from enthusiastic, self-motivated students for a funded PhD studentship within the Leverhulme Quantum Biology Doctoral Training Centre (QB-DTC) at the University of Surrey. This project aims to study the mechanisms used by electroactive microorganisms to transfer electrons to an external solid acceptor such as an electrode. If the electrode is connected via an external circuit to a cathode, an electric current (of the order of mW/m2 of anode) is produced. There is an ongoing discussion about the true nature of the mechanisms involved, either electron hopping or electron tunnelling. We propose using semiconductors as opposed to metals to study these systems, as the potential gradient which can be produced on their surface will allow selective growth of microorganisms with different redox potentials, and the consequent improved transfer of electrons from the microorganism to the electrical system. We will explore in detail the electron transport mechanisms between redox enzymes and electrodes, in an attempt to elucidate whether this is a classical conductive transport or if it involves quantum tunnelling. For more information visit the QB-DTC website.
Start date1 July 2021
Funding sourceThe Leverhulme Quantum Biology Doctoral Training Centre at the University of Surrey
Funding will provide an annual stipend approximately £15,000 and full-time tuition fees at the “Home/EU” rate up to 3 years. Although worldwide applicants are welcome to apply, only UK/EU fees are available. Applicants outside UK/EU will need to find the additional funds.
Several mechanisms have been proposed for external electron transfer by bacteria to electrodes. In this project, you will pursue the following lines of research connecting electrogenic bacteria and quantum effects:
- Explore in detail the electron transport mechanisms between membrane cytochromes and electrodes. Is this a classical conductive transport, is it ion transport, or does it involve quantum tunnelling along a series of Fe-S clusters?
- So far, bio-electricity has been produced using metallic (or carbon) electrodes as the interface between the microbial electro-generation and the electric load. You will examine here how using a semiconductor as the electrode influences the microbial metabolism and therefore electron transfer.
- Semiconductors are characterised by the energy-band gaps for electrons, implying that electrons in them can exist only on discrete potential / energy levels (as opposed to metals or carbon). Therefore, the electron donation process from microorganism is constrained by these potential bands. Consequently, microorganisms cannot change the energy-level at which they are donating electrons continuously, but only in discrete steps. How does this influence the metabolism of a microbial species with respect to its electrogenicity?
Quantum effects allow potential gradients along the surface of an electrode: electrogenic microbes with a preferred donation voltage would group better in the region where this potential exists along the gradient on the electrode surface. This potential gradient will allow for a completely new and efficient way to analyse the electrogenic behaviour in a multi-species community by differentiating the electric habitat along the gradient, while all the species still share a common biochemical habitat. This would allow for new communities to evolve that perhaps can metabolise organic substrates more efficiently: each species could donate electrons to the electrode at their preferred potential while still allowing exchange of partially oxidised organic compounds between them.
Related linksThe Leverhulme Quantum Biology Doctoral Training Centre The Systems Microbiology group The Power Electronics and Semiconductor Devices group
Applicants are expected to hold a first or upper-second class degree in a relevant discipline, such as microbiology, (bio)chemistry, or physics, with interest in quantum biology. Background in (bio)electrochemistry or enzymology (acquired through previous UG research or an MSc qualification) would be advantageous.
IELTS requirements: 6.5 or above (or equivalent) with 6 in each individual category.