Thora Arnardottir shortlisted for the Arts foundation Future Award – Biodesign
January 20, 2023
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March 23, 2023
The Carbon Recycling Network is one of 6 Networks in Industrial Biotechnology & Bioenergy funded by the BBSRC (BBSRC-NIBB) to encourage the growth of Industrial Biotechnology in the UK.
The Carbon Recycling Network will promote those aspects of carbon recycling that support the re-use and exploitation of single carbon (C1) greenhouse gases, CO, CO2 and CH4. The focus is on gas fermentation, primarily using chemoautotrophs for conversion of these waste gases to value-added products
Team members: Rajesh Reddy Bommareddy, Katalin Kovacs (University of Nottingham)
Collaborators: Johnson Matthey and Ingenza LTD
Time period project covered: 6 months (1 April 2022-30 September 2022)
To tackle climate change, the UK government has passed a law in June 2019 that will require all GHGs emissions produced nationally to be brought to net-zero by 2050, including the target of 78% reduction of carbon emissions by 2035. This means that any CO2 emissions will need to be balanced out by removing the same amount of GHGs from the atmosphere. At the same time, chemicals which are currently produced from fossil fuel feedstocks will need to be made by new, sustainable methods. Using GHGs, represents a techno economically feasible feedstock. However, the flammability concerns of H2 and O2 mixtures puts constraints on O2 concentrations in gas fermentations. Lower O2 concentrations means higher mass transfer requirements are necessary for a viable fermentation process. This is a known problem in a typical industrial aerobic fermentation and the problem is only bigger in aerobic gas fermentation where O2 concentration is constrained. An alternative process design is pivotal for an economically feasible process within the capital cost context of industrial gas fermentation.
In this project, we aim to solve this issue by combining bioreactor design strategy with metabolic engineering.
H2 and O2 are separated in a microbial fuel cell-based strategy, where the anode acts as an intermediary electron acceptor exploiting the CO2 fixation by a chemolithoautotroph, Cupriavidus metallidurans. A valuable chemical, 2,3-butanediol, was the case study product produced by this bacterium using CO2 as the sole carbon source, thus demonstrating a safe and efficient process. Moreover, immobilized cultures, i.e., C. metallidurans biofilm formation on the anode surface, offers greater flexibility in intensifying the process.
After successful demonstration of the novel reactor set up, the volumetric productivities of 2,3-butanediol were tested, however, due to the difficulty of inactivating the competing PHB synthesis pathway this was lower when compared to engineered C. necator strains. We found that that eliminating the PHB pathway is crucial for producing 2,3-BDO in the C. metallidurans CH34 strain.
Despite this setback, we successfully demonstrated that 2,3-BDO can be produced under the proposed conditions, and we anticipate this novel concept creates an efficient, safe, techno economically feasible process utilizing CO2, H2 and O2 gas mixtures, aligning and addressing UN sustainable goals such as industrial decarbonization and climate action.
H2 and O2 are separated in a microbial fuel cell-based strategy, where the anode acts as an intermediary electron acceptor exploiting the CO2 fixation by a chemolithoautotroph, Cupriavidus metallidurans. A valuable chemical, 2,3-butanediol, was the case study product produced by this bacterium using CO2 as the sole carbon source, thus demonstrating a safe and efficient process. Moreover, immobilized cultures, i.e., C. metallidurans biofilm formation on the anode surface, offers greater flexibility in intensifying the process.
After successful demonstration of the novel reactor set up, the volumetric productivities of 2,3-butanediol were tested, however, due to the difficulty of inactivating the competing PHB synthesis pathway this was lower when compared to engineered C. necator strains. We found that that eliminating the PHB pathway is crucial for producing 2,3-BDO in the C. metallidurans CH34 strain.
Despite this setback, we successfully demonstrated that 2,3-BDO can be produced under the proposed conditions, and we anticipate this novel concept creates an efficient, safe, techno economically feasible process utilizing CO2, H2 and O2 gas mixtures, aligning and addressing UN sustainable goals such as industrial decarbonization and climate action.
