The Wood-Ljungdahl pathway is a key mechanism for CO₂ fixation in acetogens, which are obligately anaerobic bacteria that use this pathway for energy conservation and acetyl-CoA synthesis. This pathway involves the stepwise incorporation of one-carbon units to form acetate. The pathway was first identified through studies on the bacterium *M. thermoacetica*, which was later shown to fix CO₂ via a novel pathway. Key components of the pathway include corrinoids, tetrahydrofolate, and cobalamin, which are essential for the transfer of one-carbon units. The pathway has been elucidated through a series of biochemical, biophysical, and bioinorganic studies, revealing the roles of various enzymes and cofactors in the process. The pathway is also used by methanogens and sulfate-reducing bacteria, highlighting its importance in carbon cycling. The pathway's ability to fix CO₂ and generate energy through the reduction of CO₂ to acetate makes it a crucial component of the carbon cycle. The discovery of the Wood-Ljungdahl pathway has provided insights into the evolution of life and the metabolic diversity of acetogens. The pathway involves a series of enzymatic reactions that convert CO₂ into acetyl-CoA, with the involvement of various cofactors and metal centers. The pathway's complexity and the roles of its components have been extensively studied, leading to a deeper understanding of the biochemical mechanisms involved in CO₂ fixation.The Wood-Ljungdahl pathway is a key mechanism for CO₂ fixation in acetogens, which are obligately anaerobic bacteria that use this pathway for energy conservation and acetyl-CoA synthesis. This pathway involves the stepwise incorporation of one-carbon units to form acetate. The pathway was first identified through studies on the bacterium *M. thermoacetica*, which was later shown to fix CO₂ via a novel pathway. Key components of the pathway include corrinoids, tetrahydrofolate, and cobalamin, which are essential for the transfer of one-carbon units. The pathway has been elucidated through a series of biochemical, biophysical, and bioinorganic studies, revealing the roles of various enzymes and cofactors in the process. The pathway is also used by methanogens and sulfate-reducing bacteria, highlighting its importance in carbon cycling. The pathway's ability to fix CO₂ and generate energy through the reduction of CO₂ to acetate makes it a crucial component of the carbon cycle. The discovery of the Wood-Ljungdahl pathway has provided insights into the evolution of life and the metabolic diversity of acetogens. The pathway involves a series of enzymatic reactions that convert CO₂ into acetyl-CoA, with the involvement of various cofactors and metal centers. The pathway's complexity and the roles of its components have been extensively studied, leading to a deeper understanding of the biochemical mechanisms involved in CO₂ fixation.