Consolidation, Integration and Critical Mass Building – Optimising membrane function in the Clostridial ABE process

Dr Alan Goddard (Aston University)
Green Biologics


“This project was a great opportunity to bring together various CBMNet-funded projects to form a multidisciplinary collaboration and generate some exciting data to be used for future funding applications”

Dr Alan Goddard, Aston University

The Challenge

Solventogenic Clostridia are used by Green Biologics Ltd. in the commercial production of n-butanol by fermentation of sugar-containing feedstocks via the acetone-butanol-ethanol (ABE) process. n-butanol is an important commodity chemical and its biological production decreases Green House Gas emissions compared to petrochemical routes. The cost of n-butanol extraction during fermentation is high, but could be significantly decreased if higher concentrations could be achieved during fermentation. However, n-butanol over ~2% is toxic to Clostridia and even low concentrations slow metabolism.

Previous research (supported by CBMNet funding) has demonstrated that this toxicity is at least in part due to damage to the Clostridial cell membrane. However, the Clostridial membrane remains poorly understood and it is necessary to better characterise this membrane to understand how to mitigate toxicity.

The Research

Dr Alan Goddard is a Lecturer at Aston University. The research in his laboratory focuses mainly on the lipid membrane that surrounds biological cells and the integral proteins residing within this. Green Biologics makes renewable specialty chemicals and formulated products that are used by manufacturers in the fast moving consumer goods and industrial product sectors to make high performing products from renewable sources. Dr Goddard and collaborators Prof Gavin Thomas (University of York), Dr Rob Fagan (University of Sheffield) and Dr Peter Chivers (Durham University) applied for a Proof-of-Concept award with Green Biologics. This project aimed to gain further insight into the effect of n-butanol on membrane structure and function to ultimately generate resistant Clostridial strains.

The Result

Significant progress has been made towards the aims of this project: generation of a Clostridial knockout library to screen for strains that have enhanced resistance to n-butanol; characterisation of carbohydrate transporters within the cell membrane to improve utilisation of different feedstocks; and investigation of the effects of n-butanol on metal homeostasis. A number of researchers from the host laboratories have gained experience in new techniques as well as benefiting from undertaking inter-sectoral collaborations. This project has developed a number of interactions between the partners which will be explored both informally and through future funding applications.

The Future

Newly isolated mutant strains are available that can be characterised to assess their ability to use different feedstocks more efficiently. Preliminary characterisation of membrane protein stability is ongoing using SMALP and/or bicelles with a view to examining the effect of lipid composition on membrane protein stability in response to n-butanol. All of the collaborations will continue through informal routes using existing researchers in the PI’s laboratories. Dr Goddard and Green Biologics are currently applying for further funding to continue their collaboration and, upon completion of the outstanding areas of this collaboration, will explore the possibility of further funding through routes such as BBSRC and Innovate UK.

“This project has enabled us to consolidate partnerships with academics across various specialisms. The results are applicable to overcoming challenges in an industrial setting in particular tolerance of microbes to inhibitors. CBMNet funding opportunities and networking events have been instrumental in driving this research forwards”

Dr Liz Jenkinson, Green Biologics