acidogene

Acidogene is a term used in microbiology and environmental biotechnology to denote organisms or processes that produce acid under anaerobic conditions. In practice, acidogenic bacteria are the fermentative microorganisms responsible for the acidogenesis phase of anaerobic digestion, where complex organic substrates are converted into simpler, acidic products.

During acidogenesis, hydrolyzed and fermented substrates such as carbohydrates, proteins, and lipids are transformed into short-chain volatile fatty acids (VFAs), alcohols, hydrogen, and carbon dioxide. The specific VFAs commonly produced include acetic, propionic, and butyric acids, along with other organic acids and reduced compounds. The activity of acidogenic communities is influenced by factors such as temperature, pH, substrate composition, and loading rates.

Acidogenesis is distinct from subsequent stages in anaerobic digestion. Acetogenesis converts VFAs and alcohols into acetate, hydrogen, and carbon dioxide, while methanogenesis produces methane from acetate and hydrogen plus carbon dioxide. The balance among these stages affects the stability and efficiency of biogas production in anaerobic digesters.

Ecologically, acidogens are important in natural anaerobic environments (such as sediments and ruminant guts) and engineered systems (such as wastewater treatment anaerobic reactors and biogas plants). Management considerations include preventing excessive acidification, which can lower pH and inhibit methanogens, and optimizing conditions to maintain a productive transition from acidogenesis to downstream processes.

See also: acidogenic bacteria, anaerobic digestion, volatile fatty acids, methanogenesis.