Acetobacterium

Acetobacterium is a genus of obligately anaerobic, Gram-positive bacteria within the phylum Firmicutes. Members of this genus are known as acetogenic or homoacetogenic bacteria, meaning they predominantly convert carbon dioxide into acetate as their main end product. The best-studied species is Acetobacterium woodii, and the genus comprises several related species that share a similar metabolic pattern.

Metabolism and physiology play a central role in Acetobacterium biology. These bacteria fix CO2 via the Wood-Ljungdahl pathway, using electrons derived from hydrogen or other substrates to reduce CO2 to acetyl-CoA and then to acetate. This pathway provides a means of autotrophic growth, allowing these organisms to thrive in strictly anaerobic environments. Many Acetobacterium species are capable of growing on inorganic electron donors such as H2 and can also utilize a range of organic substrates, producing acetate as a major product. They are typically rod-shaped and non-spore-forming, adapted to low-oxygen conditions.

Ecologically, Acetobacterium species are found in diverse anaerobic habitats, including freshwater and marine sediments, wetlands, soils, and anaerobic digesters. They contribute to carbon cycling by transforming CO2 into organic acids and participate in microbial consortia where hydrogen, formate, or other electron donors are available.

Taxonomically, the genus is placed within the Firmicutes, commonly associated with Clostridiales. The defining feature across the genus is acetogenesis via the Wood-Ljungdahl pathway, which underpins their role in autotrophic processes and potential biotechnological applications.