Studies on the acetone-butyl alcohol fermentation

Abstract

The fermentation of carbohydrate by this organism upon maize meal produces a normal fermentation, CO2, H2, acetic and butyric acids, ethyl and butyl alcohols and acetone. On 2% yeast water the yields of alcohols and acetone (solvents) are low (acid fermentation). Certain additions to the yeast water medium convert the fermentation to a normal one; these can be extracted from liver, maize, and yeast but have not been isolated. Cells grown on a basal medium + liver extract give good growth and solvent production but when spun off and washed are inactive. A suspending fluid was found in which centrifuged cells retain their activity whereby the course of the fermentation of glucose and pyruvic acid has been studied. The character of the fermentation depends on the age of the culture from which the cells have been harvested. Those obtained in the early stages of the fermentation produce no solvents in subsequent fermentations. Only if harvested after the appearance of acetone in the parent culture are cells obtained which contain the full complement of enzymes necessary to give a normal fermentation.