Acetobutyl Fermentation

decomposition of carbohydrates occurring without available oxygen (anaerobi-cally), which results in the formation of butyl alcohol, acetone, acetic and butyric acids, carbon dioxide gas, and hydrogen. Acetobutyl fermentation is brought about by the motile, spore-forming, anaerobic bacteria Clostridium acetobutylicum, which ferment glucose, maltose, saccharose, and dextrin and hydrolyze starch. Acetobutyl fermentation occurs in two phases: (1) intensive propagation of bacteria, formation of acetic and butyric acids; acidification of the medium to pH 3.5–4.0 and accumulation of proteolytic enzymes; (2) autolysis of bacteria, decrease in acetic acid and butyric acid content and accumulation of acetone and butyl alcohol. Before chemical synthesis of acetone and butyl alcohol was known, acetobutyl fermentation was the only industrial method for obtaining these substances from corn, rye, potatoes, or molasses.