Light-driven reductive transformations by Shewanellaceae

Rowe, Sam (2017) Light-driven reductive transformations by Shewanellaceae. Doctoral thesis, University of East Anglia.

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The use of finite fossil reserves within the energy and petrochemicals industries has harmful environmental impacts due to the release of CO2 into the Earth’s atmosphere. Consequently, new technologies that harness renewable forms of energy, such as solar energy, are required for the sustainable production of valuable chemicals including fuels. Taking inspiration from plants and photosynthetic micro-organisms, artificial systems are being developed for solar-chemicals production by combining light-harvesting photosensitisers, such as molecular dyes and semiconducting nanoparticles, with electrocatalysts such as purified enzymes and whole-cell bacteria. In particular, whole-cell bacteria have emerged as effective electrocatalysts because they provide opportunities to develop self-regenerating systems that can facilitate multiple chemical transformations.
The work presented in this thesis aimed to develop a cell-based approach to solar-chemicals production where a single micro-organism can act as a multi-faceted electrocatalyst without the requirement for costly and time-consuming enzyme purification. The approach was developed with the non-photosynthetic bacterium Shewanella oneidensis MR-1, a model micro-organism for extracellular electron transfer. The system uses methyl viologen as an electron shuttle to transfer photo-energised electrons from water-compatible photosensitisers to bacterial enzymes for H2-evolution and the reduction of fumarate, pyruvate and CO2 to succinate, lactate and formate, respectively. Preliminary experiments were also carried out to investigate the possibility of using new-generation carbon dot photosensitisers for light-driven H2-evolution in the absence of an exogenous electron shuttle. The work was performed in a step-wise manner involving an assessment of the determinants of each system using a range of analytical techniques and the findings form a basis for sustainable cell-based photocatalysis with other species of bacteria or genetically-modified Shewanella strains.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Jackie Webb
Date Deposited: 14 May 2018 08:09
Last Modified: 28 Feb 2021 01:38


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