Redirecting the carbon flux by implementing energy-conserving modules in Methanothermobacter thermautotrophicus to capture carbon dioxide

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Renewable energy sources are well-established parts of the electricity mix for many countries. However, an imbalance between production and consumption makes storing surplus renewable electric power necessary. Hydrogen (H2) can be generated through the electrolysis of water with renewable energy. Using H2 to produce methane gas (CH4) from carbon dioxide (CO2) in a power-to-gas process with biomethanation has already become a solution to overcome the costly direct storage of H2. Pure cultures of thermophilic methanogenic archaea, such as Methanothermobacter thermautotrophicus, are applied to convert CO2 and H2 into CH4 with high process stability and production rates. The resulting renewable natural gas contains >97% CH4. With only little additional conditioning, this gas can be introduced into the existing natural gas grid, with vast storage capacity and great distribution possibilities. My lab has developed a genetic system for M. thermautotrophicus, which can now be utilized to harness the full potential of this biotechnology by investigating and optimizing the microbial physiology of the biocatalyst and broadening the product spectrum in a power-to-chemicals approach. Based on the available genetic system, we will develop additional tools, for example, to produce tagged enzyme variants in M. thermautotrophicus. This will allow us to study the biochemistry of highly relevant enzymes for methanogenesis. For this purpose, we will collaborate with partners in the US and Australia. The genetic tools, in combination with steady-state fermentation and systems biology data, will be exploited to optimize the metabolism of M. thermautotrophicus to produce acetoin as a proof-of-concept product. For example, acetoin is of economic value as a flavor enhancer, cosmetics ingredient, and precursor to further platform chemicals such as 2,3-butanediol. My lab has also developed a genome-scale metabolic model, which provides the platform to test hypotheses in silico before wet lab experiments. We have used the model to simulate metabolic changes that could lead to higher flux toward acetoin, which will be tested in this proposal. With this, we will demonstrate that M. thermautotrophicus can be utilized as a rigid microbial chassis to produce other biotechnologically relevant products in a power-to-chemicals platform.