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Published on: September 6, 2024
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Deconstructing Methanosarcina acetivorans into an acetogenic archaeon
Christian Schöne1, Anja Poehlein2, Nico Jehmlich3
1Institute of Microbiology, Technische Universität Dresden, 01062 Dresden, Germany.
Summary
Researchers converted a methanogen into an acetogen, showing that methanogenic archaea can use the reductive acetyl-CoA pathway for energy conservation without producing methane. This study reveals greater metabolic flexibility in archaea and supports the evolution of methanogenesis.
Area of Science:
- Microbiology
- Biochemistry
- Metabolic Engineering
Background:
- The reductive acetyl-CoA pathway is crucial for autotrophic energy conservation and carbon fixation in methanogenic archaea.
- Methanogenesis, the biogenic formation of methane, is a key process in the global carbon cycle and essential for methanogen growth.
- All known methanogenic archaea rely on methanogenesis for energy and utilize the reductive acetyl-CoA pathway for carbon fixation.
Purpose of the Study:
- To investigate if methanogenic archaea can conserve energy via acetogenesis instead of methanogenesis.
- To explore the metabolic flexibility of methanogenic archaea by altering their core metabolic pathways.
- To provide experimental evidence for the evolutionary link between methanogenesis and the reductive acetyl-CoA pathway.
Main Methods:
- Targeted genetic disruption of the methanogenic pathway in *Methanosarcina acetivorans*.
- Employing adaptive evolution to select for strains capable of acetogenesis.
- Measuring carbon flux through metabolic pathways to assess energy conservation and carbon fixation.
Main Results:
- A modified strain of *Methanosarcina acetivorans* was generated that sustained growth via carbon monoxide-dependent acetogenesis, completely dispensing with methanogenesis for energy conservation.
- A minimal flux through the methane-producing reaction (less than 0.2%) remained essential, suggesting its metabolites are used for anabolic purposes in methanogens.
- The study demonstrates the metabolic plasticity of methanogenic archaea, challenging previous assumptions about their obligate reliance on methanogenesis.
Conclusions:
- Methanogens possess greater metabolic flexibility than previously understood, capable of utilizing the reductive acetyl-CoA pathway for energy conservation through acetogenesis.
- The ability to convert a methanogen into an acetogen supports the hypothesis that methanogenesis may have evolved from the reductive acetyl-CoA pathway.
- This research opens new avenues for understanding microbial metabolism and the evolution of early life on Earth.
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