Cyanobacterial Biofilms for Photoelectrochemistry

Cyanobacteria are versatile photosynthetic prokaryotes whose metabolism is based on the extraction of electrons from water coupled to the reduction of CO2 to produce sugars. They are capable of direct electron export/import from their environment and therefore they have remarkable potential as a versatile component of systems for light-powered bioelectrochemistry.

This project will address one of the key practical considerations in the development of such systems: how to assemble stable biofilms of cyanobacterial cells for bioelectrochemistry. Many cyanobacteria can adhere to surfaces using a combination of fibrous protein appendages called Type IV pili (T4P) and a sticky matrix of extracellular polymeric substances (EPS, which is mainly polysaccharide slime). We will use two model cyanobacteria: the unicellular Synechocystis sp PCC6803 and the filamentous, nitrogen-fixing Anabaena (Nostoc) sp PCC7120. By genetic manipulation of both the T4P and EPS production we will tailor cells for biofilm formation on different surfaces in order to enable bioelectrochemical applications. The supports for the biofilms will be prepared by using electrospinning, a versatile technique that enables a fine control of the surface and structural characteristics by adjusting the processing parameters. This will give the student a wide variety of scenarios to explore what conditions and properties of the substrate are the optimal for the deposition and growth of the biofilm.

This will be followed for electrochemical characterisation of the biofilm studying different relevant reactions under light irradiation, including CO2 reduction and H2 generation. The supervision team combines Prof Mullineaux's expertise in cyanobacterial molecular biology, photosynthesis and adhesion with Dr Sobrido's expertise on the synthesis and processing of sustainable materials for energy conversion and storage applications.