A glucose-6-phosphate dehydrogenase in Leuconostoc mesenteroides.

Glucose fermentation by Leuconostoc me8enteroides has been shown to proceed via a mechanism which differs from the classical Embden-Meyerhof glycolytic scheme. DeMoss, Bard, and Gunsalus (1951) found no evidence in cell-free extracts of this organism for the key enzyme aldolae but showed that cellular suspensions ferment glucose to equimolar quantities of ethanol, C02, and lactate as obligatory products. The diphosphopyridine nucleotide linked dehydrogenases for D-3-phosphoglyceraldehyde, D(-) lactic acid, and ethanol were demonstrated, indicating some resemblance of the Leuconostoc mechanism to the classical glycolytic scheme. Fermentation of glucose-1-C'4 by cellular suspensions was reported by Gibbs and DeMoss (1951) and Gunsalus and Gibbs (1952) to yield C14 exclusively in C02 at six times the specific activity of the glucose fermented, whereas glucose-3,4-C04 yielded carboxyl labeled lactate, carbinol labeled ethanol, and unlabeled C02. These results support the data obtained with enzyme extracts and, in addition, demonstrate that both C02 and ethanol must arise by a previously undescribed fermentative pathway(s). The observation of a glucose-6-phosphate dehydrogenase in extracts of L. menteroide8, reported in preliminary form by DeMoss, Gunsalus, and Bard (1951), suggested the operation of an anaerobic counterpart of the oxidative hexosemonophosphate pathway via phosphogluconic acid as the fermentative mechanism involved. Such an oxidative system, previously recognized only in aerobic organisms and studied by Warburg and Christian (1932), Lipmann (1936), and Dickens (1938), has been described recently in detail by Horecker and co-workers