System metabolic engineering for advanced methane fermentation

Growing concerns over finite fossil resources and environmental problems have encouraged the development of sustainable processes for fuels produced from renewable resources. One of the resolutions is to rely on the ability of microorganisms to synthesis fuels and chemicals.

Fermentation of C1 gases from waste streams is an effective method offering numerous advantages. Methane fermenting bacteria can metabolize C1 gases as the only source of carbon and energy into valuable fuels and chemicals, and the products from fermentation can also be used as microbial fodder.

Thus, the project is to impose the constraints to a genome-scale metabolic model, so as to understand the metabolism of anaerobic methanotrophic archaea (ANME2d) to improve methane uptake rate. System metabolic engineering will be the key methodology applied in the project, which incorporates the techniques of systems biology, synthetic biology. Specifically, we will use thermodynamic metabolic flux analysis, and high throughput analytics to achieve a better understanding of the metabolism which operates at the thermodynamic edge of feasibility.

Systems metabolic engineering is a modern toolbox, which solves the roadblocks of low conversion rate in large bioreactors under traditional metabolic engineering process. The methodology employs integrated rational metabolic engineering techniques to upgrade the design ability of industrial microorganisms, including the strain development, investment decision, process scale-up and quality assurance. Developing industrial microbial strains by systems metabolic engineering is the first step for C1 gases fermentation.

The strategies include:

• the selection of optimal host strain
• metabolic pathway reconstruction
• optimise metabolic fluxes and culture conditions, and
• metabolic network system-wide manipulation.

During the bioprocess, we can evaluate the production performance at the molecular level and maximize the productivity and yield through the iterative construction of the strains and critical parameters. For system-wide manipulation of the metabolic network, multi-omics analysis and in silico metabolic simulations are two widely used approaches for strain improvement.

Significance of the project

C1 gas fermentation is a flexible platform for producing low-carbon fuels and chemicals from waste streams and low-cost feedstocks. Traditionally, Fischer-Tropsch process (FTP) has long been part of natural gas/coal/biomass conversion to synthetic fuels and lubrication oils, however, the technology has some drawbacks and is very capital intensive. Gas fermentation offers feedstock versatility and the economy of scale over traditional FTP processes.

Furthermore, gas fermenting microbes present an exciting alternative that is compatible with gas stream sizes and can produce a range of valuable fuels and chemicals. Waste gas fermentation not only produces viable fuels and chemicals but also avoids competition with food production as well as reduces carbon release.

The project of improving C1 gases fermentation through systems metabolic engineering creates great interest and significant prospect, to understand the mechanisms of ANME2d energy conservation with the aim of improving our understanding of anaerobic methane methanotrophy.

Funding

• FL170100086

Project Outcomes

The key purpose of this project is to:

• Advance understanding of anaerobic/micro-aerobic methane fermentation and gain insight into the pathway and the chemistry within the network.
• Develop insight for potential metabolic engineering to advance understanding of gas to liquid for advanced chemical production.
• Build a draft genome scale model.
• Obtain metabolomics and proteomics data and use the genome scale model to integrate ‘omics data.