THE MECHANISM OF THE HETEROLACTIC FERMENTATION: A NEW ROUTE OF ETHANOL FORMATION

Abstract

Growth expts. and fermentation balances with the heterofermentative coccus, Leuconostoc mesenteroides, strain 39, indicate a lower energy yield per mole of glucose fermented than in the homofermentative lactic acid bacteria. Fermentation balances with cell suspensions indicate the fermentation of glucose to 1 mole each of lactate, ethanol, and CO2. No evidence for departure from this ratio of products has been observed. Diphosphopyridine nucleotide-linked dehydrogenases for ethanol, lactate, 2,3-butyleneglycol, and 3-phosphoglyceraldehyde were demonstrated in cell-free extracts. Acetate, acetaldehyde, acetoin, and dihydroxyacetone stimulate the rate of fermentation by cell suspensions. Aldolase and isomerase do not appear to be present in this organism. A departure from the Embden-Meyerhof scheme and the presence of a new glycolytic mechanism in these organisms are indicated.