Role of redox potential on the metabolism of Clostridium strains

Renewable biomass can be converted by fermentation into molecules of interest such as butanol and isopropranol. These two solvents are widely used industrially and as chemical building blocks. The associated fermentation process using Clostridium bacteria has low yield and productivity. Several limitations indeed reduce these performances: toxicity of butanol, phenomenon of “acid crash” and instability of the ratio between the different solvents. While the influence of parameters such as temperature and pH on the efficiency of fermentation is well known, many phenomena remain uncontrolled. 
The redox potential study is therefore an interesting option for a better understanding of the metabolism of solvent-forming bacteria. It represents the activity of electrons and has a predominant role in the metabolism of microorganisms. 
The objective of this thesis is to better understand the oxidation-reduction reaction mechanisms involved or even governing these fermentation reactions. To answer this, the influence of fermentation parameters on the redox state of solventogenic Clostridium cells will therefore be studied. 
Different conditions will be tested and analyzed such as the design of fermentation, the electrofermentation or the composition of the culture medium. Quantifications of key co-factors and enzymatic activities, and an omic study will allow the assessment of the redox state of cells. 
Finally this thesis should lead to the acquisition of essential data for understanding the influence of the redox potential on Clostridium metabolism. In addition, this work will improve the control and efficiency of the fermentation process in terms of productivity, yield and/or selectivity. The candidate must have an engineer or master  degree in biotechnology and microbiology.

Keywords: fermentation, Clostridium, redox potential

• Academic supervisor    Dr BEN CHAABANE Fadhel, IFP Energies Nouvelles, Dr BOUCHEZ Théodore, INRAE
• Doctoral School    ABIES, http://www2.agroparistech.fr/abies/
• IFPEN supervisor    Dr VELLY Hélène, Département Biotechnologie, helene.velly@ifpen.fr
• PhD location    IFP Energies nouvelles, Rueil-Malmaison, France
• Duration and start date    3 years, starting in fourth quarter 2021
• Employer    IFP Energies Nouvelles, Rueil-Malmaison, France
• Academic requirements    University Master degree in biotechnology or microbiology
• Language requirements    Fluency in French or English, willingness to learn French