Acetogenesis is a process through which acetate is produced by prokaryote microorganisms either by the reduction of CO or by the reduction of organic acids, rather than by the oxidative breakdown of carbohydrates or ethanol, as with acetic acid bacteria.
The different bacterial species capable of acetogenesis are collectively termed acetogens. Reduction of CO to acetate by anaerobic bacteria occurs via the Wood–Ljungdahl pathway and requires an electron source (e.g., H, CO, formate, etc.). Some acetogens can synthesize acetate autotrophically from carbon dioxide and hydrogen gas. Reduction of organic acids to acetate by anaerobic bacteria occurs via fermentation.