Xxxvi. the Production of Acetaldehyde during the Anaerobic Fermentation of Glucose by Bacillus Coli Communis

Acetaldehyde has long been known as a product of alcoholic fermentation by yeast [see Roeser, 1893]. It has likewise been found to be formed by the leaves of higher plants when their metabolism is restricted to anaerobic conditions [Kostytschew, 1913]. In view of this wide distribution, it was to be expected that acetaldehyde would be a product of bacterial fermentation. This is the case. The quantity of acetaldehyde found by Roeser in various wine musts after a fermentation lasting from five to fifteen days, varied from 20-200 milligrams per litre of the fermented fluid. In the case of B. coli communiis acting on glucose, one litre of fluid containing originally 15 grams of the sugar yielded in 15 days when half the sugar had been fermented 2-34 mg. of acetaldehyde, while, at the same time, 1-375 gr,ams of alcohol had been produced. Siince in the case of the true alcoholic fermentation quoted above, the quantity of alcohol formed was certainly twenty times that produced in the experiment with B. coli communis, it will be seen that the ratio of acetaldehyde to alcohol is of the same order in the two cases. It is not at present settled, in the case of yeast fermentation, whether acetaldehyde is a primary product or whether it results from the oxidation of preformed alcohol, the following result is therefore significant in showing that the production of acetaldehyde by B. coli communis is related to the formation of alcohol, carbon dioxide, and acetic acid, rather than to the other products. The experiment consisted in comparing the production of acetaldehyde from normal B. coli communis (Escherich) with that from a strain derived from the normal organism by selection with sodium chloracetate [see Penfold, 1911, and Harden and Penfold, 1912]. This derived strain had completely