Project Outline

The global economy has an unsustainable dependence on fossil raw material and concerns about environmental sustainability are becoming more acute. Biotechnological processes using microorganisms as cell factories to produce valuable compounds from renewable biomass are an attractive alternative, and an increasing number of platform and high-value chemicals are being produced at industrial scale using this strategy. However, many microbial processes are not implemented at industrial level because the product yield is poorer and more expensive than achieved by chemical synthesis.

It is well-established that microbes show stress responses during bioprocessing and one reason for poor product output from cell factories is production conditions that are ultimately toxic to the cells, often at the level of the cell membrane. Examples of stresses that are demonstrably membrane-centric are solvents, e.g. butanol production by Clostridia and ethanol production by yeast, and weak acids such a lactic acid produced by bacteria. This project will seek to alter the cell membrane of industrial microbes to increase tolerance to stresses during bioprocessing.

Building on our recent findings in yeast and bacteria, the approach will use a powerful combination of in vitro assays, microbial cell culture, and ‘omics technologies to identify the molecular targets e.g. lipids and transporters. Genetic engineering to create strains will be followed by strain characterisation to determine if the desired membrane alterations have been achieved and if tolerance to a particular stress (or stresses) has been increased. Iterative design-build cycles will be undertaken as appropriate to further improve the strains.

This project would suit applicants with an interest in biophysics and biochemistry of the cell membrane and/or in microbial fermentations and industrial application of fundamental science.

References

Lairón-Peris, M., Castiglioni, G.L., Routledge, S.J., Alonso-del-Real, J., Linney, J.A., Pitt, A.R., Melcr, J., Goddard. A.D., Barrio, E. and Querol, A (2021) Adaptive response to wine selective pressures shapes the genome of a Saccharomyces interspecies hybrid. Microbial Genomics. 7 (8), 000628.

Mukhopadhyay, A., Tolerance engineering in bacteria for the production of advanced biofuels and chemicals. Trends in Microbiology, 2015. 23(8), 498-508.

Santoscoy, M. C., & Jarboe, L. R. (2019). Streamlined assessment of membrane permeability and its application to membrane engineering of Escherichia coli for octanoic acid tolerance. Journal of industrial Microbiology and Biotechnology, 46(6), 843-853.

Techniques

• Biophysical techniques e.g. generation of model lipid bilayers and characterisation of them.
• Proteomic and lipidomic analysis e.g. SDS-PAGE, thin layer chromatography and mass spectrometry.
• Protein expression and purification.
• Molecular biology e.g. PCR, cloning, genome engineering.
• Strain growth and characterisation e.g. membrane biophysics assays, western blotting and fermentation.