Product labeling of glucose-1-C14 fermentation by homofermentative and heterofermentative lactic acid bacteria.

Lactobacillus casei, a homofermentative lactic acid bacterium, was shown by Gibbs et al. (1950) to ferment glucose-i-C4 to products labeled as predicted for the classical EmbdenMeyerhof glycolytic scheme, whereas Leuconostoc mesenteroides strain 39, a heterofermentative lactic acid coccus, gave product labeling incompatible with an Embden-Meyerhof pathway and was interpreted as indicative of the occurrence of an anaerobic hexosemonophosphate pathway (Gunsalus and Gibbs, 1952). When glucose-i-C"4 was fermented by the homofermentative organism, about 97 per cent of the tracer appeared in the methyl carbon of lactic acid. In contrast, the heterofermentative organism gave unlabeled lactic acid, with carbon atom 1 (aldehyde carbon) of the glucose giving rise exclusively to carbon dioxide. Although the fermentation of glucose-3,4-C4 by Leuconostoc mesent4roides yielded further evidence of the nature of the heterofermentative pathway, as had previous enzymatic data (DeMoss et al., 1951), the fermentation of glucose-1-C4 was sufficient to differentiate the Embden-Meyerhof from the heterolactic pathway. The purpose of the present study was to determine whether other homofermentative and heterofermentative lactic acid bacteria widely used in metabolic studies possess the fermentation patterns outlined with Lactobacillus casei and Leuconostoc mesenteroides.