The activation of the butanol-acetone fermentation of carbohydrates by Clostridium acetobutylicum (Weizmann)

Abstract

For a normal butanol-acetone fermentation of carbohydrates in synthetic media the presence of at least 2 compounds is essential: asparagine and a low molecular substance (termed activator) of still unknown constitution. Only in the presence of these 2 compounds (which are separately inactive) does the fermentation proceed with the same velocity and give the same yield as the butanol-acetone fermentation of a 2.5% maize mash. Highly complex proteins such as peptone, zein or prolamine are not necessary constituents of the media. The findings of Rettger and Weinstein, who claim that zein contains the bulk of the activating constituent present in maize, was not confirmed. The "activator" occurs in green plants and seeds, especially in the bran of the seed; yeast is a rich source of it, and active solns. have been prepared therefrom by autolysis and dialysis. Asparagin acts as a specific N carrier; it could not be replaced by simple amino acids such as glycine, alanine or B alanine. Lactoflavine and cozymase, singly or in combination, with and without additional asparagine, are without influence on the fermentation. Owing to its stability towards heat, dil. acid and alkali and its indifference towards the substrate of the fermentation the activator has been classified as co-enzyme. It is probably an auxiliary substance for the enzyme system of the bacteria, facilitating especially the H transfer either from the substate or from the enzyme to butyric[long dash]or possibly B hydroxybutyric acid.