The Propionic Acid Bacteria on the Mechanism of Glucose Dissimilation* by H. G. Wood

The fundamental investigations of Virtanen (1923, 1925), Virtanen and Karstrom (1931), and van Niel (1928) on the mechanism of glucose dissimilation by the propionic acid bacteria have led to the proposal that glucose after preliminary phosphorylation is converted into 2 molecules of the C) type. Virtanen upon theoretical considerations concludes that lactic acid is an intermediate product of the fermentation. This investigator also accepts a secondary splitting of the glucose into Cd and CZ compounds. This step does not involve phosphorylation. Van Niel, however, proposes that 1 molecule of methylglyoxal, formed by the sugar cleavage, is oxidized through pyruvic acid to acetic acid and COZ, while 2 molecules of methylglyoxal are reduced to propionic acid. Neither the lactic acid nor methylglyoxal was demonstrated in fermentations by these investigators. Foote, Fred, and Peterson (1930), however, have reported the production of lactic acid from glucose by one culture of a considerable number studied. Although no marked disagreement has arisen concerning the mechanism of the formation of propionic acid, acetic acid, and CO*, there is little agreement as to the method of formation of the succinic acid which is produced in the propionic acid fermentation. Virtanen first noted the production of succinic acid in glucose fermentations and suggested that it was formed by a 2and 4carbon cleavage of the glucose molecule to succinic acid and acetaldehyde. On the other hand van Niel believes that the