Reducing CO2 emissions during chemical production through the Synthetic Biology of complex microbial communities

One of the greatest challenges facing society is the future sustainable production of chemicals and fuels from non-petrochemical resources while at the same time reducing greenhouse gas emissions. The use of abundant and renewable lignocellulosic materials, that can be physically pretreated to yield both cellulosic and C5 fractions as feed stocks to make chemicals and fuels can be highly valuable if the process is efficient and minimises CO2 production.

This studentship will be linked to a recently funded BBSRC project that is part of the European EraCoBiotech programme between the Universities of Nottingham, Toulouse, Munich and Girona. The aim is to engineer synthetic microbial consortium to produce to a value added product, n-butanol, that can be used both as a platform chemical or a biofuel.

Nottingham is responsible for the engineering of Clostridium carboxidivorans, n-butanol producing acetogen. Model acetogens, such as Clostridium autoethanogenum (chassis of the company LanzaTech), only make the C2 products acetate and ethanol. C. carboxidivorans (chassis of Synata Bio) on the other hand, also makes butyrate, butanol and hexanol, more valuable C4 and C6 chemicals. Hexanol, for instance, is a higher carbon alcohol with a higher energy content than ethanol. It has potential for use as an aviation fuel and as a transportation fuel when blended with kerosene and diesel. It is also used in the pharmaceutical and cosmetic perfumes industry, textile industry, in detergents, in pesticides, agent in the leather and as a fishing industry, among others.
The global hexanol market size was estimated at over USD 1.1 billion in 2016 and will exhibit growth of more than 4% up to 2024.

Until now, gene transfer into this C. carboxidivorans had never been demonstrated, precluding effective metabolic engineering strategies. Scientists at the BBSRC/EPSRC Synthetic Biology Research Centre (SBRC) at Nottingham have now overcome this impediment. In this project you will, therefore, work with our European partners in the optimisation of the key steps required for effective genome editing in C. carboxidivorans, including CRISPR/Cas9, CRISPRi, TARGET-AID and transposon-based TraDIS technology. Once in place you will use these developments to enhance hexanol production using CRISPR technologies to eliminate competing reactions (such as those leading to acetate, butyrate and lactate) as well as optimising expression of native genes. Mutants affected in competing pathways will be subjected to phenotypic characterisation and omics analyses (at the University of Toulouse), and results used to improve an SBRC Genome Scale Model. The final strain may be incorporated into the envisaged synthetic community to make hexanol.

The student will become fully integrated into the European project, attending the six monthly project meetings to be held in rotation at the 4 Universities, in Germany (Munich), France (Toulouse) and Spain (Girona). Time limited secondments to partner Universities may also be possible.

Ultimately, the developments made will lead to new, sustainable industrial processes that could make a real contribution to reducing CO2 emissions.