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  Reducing chaos and improving yield: an innovative approach to maximising the efficiency of biofuel production

   Doctoral College

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  Prof D Timson, Dr Marcus Dymond  No more applications being accepted  Funded PhD Project (European/UK Students Only)

About the Project

Biofuels make an important contribution to the energy economy of the UK and other countries. They are perceived as lower carbon alternatives to fossil fuels and are likely to make an increasing contribution as reserves of those fossil fuels diminish. They are typically produced by allowing microbes to ferment biological material (often agricultural “waste”) to alcohols such as ethanol or butanol which can then be blended with petrol or other fossil fuels. These fermentations are limited in that once a maximum level of alcohol is reached (typically 15-20%(v/v) for ethanol) the microbial cells become highly stressed, cease production and often die. This alcohol-induced stress results from general destabilisation of cellular processes and systems. A key part of this generalised inhibition is the “chaotropic” effect of the alcohols at these concentrations. Chaotropic agents are those which tend to denature, unfold and disassemble biomolecules through the disruption of non-covalent interactions.

If the chaotropic effects of alcohols could be reduced then alcoholic fermentations would be more efficient and utilise less energy to produce the same volume of product. Indeed, the very low temperatures used in the fermentation of Japanese sake result in ethanol yields of over 20%(v/v); however this is achieved at the expense of considerably longer fermentation times, which would not be viable for the large-scale industrial production of ethanol. It has been known for several decades that “compatible solutes” such as glycerol can partially overcome chaotropic effects. Their effects are, however, complex: very high concentrations of glycerol can themselves be chaotropic and purification of ethanol from glycerol can be time and energy consuming.

The student will spearhead a new programme of research at Brighton investigating strategies for mitigation of the chaotropic limitations of microbial fermentations. S/he will pursue three main themes:

1. Chemical mitigation of chaotropicity: Although it is well-documented that compatible solutes such as glycerol can help microbes survive in stressful conditions, their effect on ethanol yields has not been fully explored. The student will undertake a quantitative study of the effect of glycerol supplementation on ethanol yield. S/he will develop a standard culture protocol for yeast strains under conditions which favour ethanol production. In parallel s/he will develop a simple and robust quantitative assay for the amount of ethanol produced based either on chromatographic methods or chemical analysis. This will enable him/her to monitor ethanol production as a function of culture conditions. S/he will also test other compatible solutes and, since chaotropicity can induce free radical production, free radical quenchers.

2. Evolution of new chao-tolerant strains: The short generation time of microbes means that it is often possible to drive evolutionary change through the application of strong selective pressures. The student will attempt to generate yeast strains which are most tolerant of generic chaotropic agents. S/he will also attempt to understand what biochemical and genetic changes underlie this greater tolerance of chaotropes.

3. Engineering of increased robustness to chaotropicity: Cells respond to chaotropic stresses by increasing the ratio of saturated:unsaturated fatty acids in their membranes. We will search the Saccharomyces Genome Database for genes associated with alterations in this ratio. The student will then engineer strains in which genes promoting increases in the ratio are upregulated and/or those promoting decreases are down-regulated or deleted. These strains will be tested for ethanol tolerance and their performance in ethanol production assessed.

Entry requirements
Academic entry requirements
Applicants should have a minimum of a 2:1 undergraduate degree and desirably hold or expect to achieve excellent grades in a masters degree, in a relevant subject from a UK university or comparable qualifications from another recognised university.
Applicants are also required to submit a research proposal of no more than 1,000 words.

English language entry requirements
Applicants whose first language is not English, must have successfully completed a Secure English language Test (SELT) in the last two years. Applicants who have obtained or are studying for a UK degree may apply without a SELT. However, the university may request a SELT is taken as part of any award made.

English language IELTS requirements are 6.5 overall, 6.0 for writing, and none below 5.5.
If you have an English language qualification other than IELTS, please contact us to see if you are eligible to apply for a studentship.

Funding Notes

This studentship is funded as part of the DTA Energy network programme for three years, subject to satisfactory progress.

For UK/EU students the studentship consists of full UK/EU tuition fees, as well as a Doctoral Stipend matching UK Research Council National Minimum (£14,553p.a. for 2017/18, updated each year). A travel bursary is also available for participation in training events related to the DTA Energy network programme.To start October 2017.

The value of the studentship will be raised to take into account any rise in annual tuition fees.

DEADLINE FOR APPLICATIONS: 17:30 (UK time) 21st June 2017