Multiple Electrophoretic Forms of Transaldolase and 6-Phosphogluconic Dehydrogenase and Their Relationships to the Taxonomy and Ecology of the Bifidobacteria

Abstract

The electrophoretic patterns of the transaldolases and 6-phosphogluconate dehydrogenases (6PGD) of 1,206 strains, each belonging to one of 24 named species of the genus Bifidobacterium, were determined by means of starch-gel electrophoresis. All of these strains were previously assigned to species on the basis of their deoxyribonucleic acid homology relationships and were selected so as to include all known phenotypes and habitats. Fourteen electrophoretic forms of transaldolase and 19 of nicotinamide adenine dinucleotide phosphate-dependent 6PGD were identified and numbered. Each strain displayed one band for each enzyme. Glucose-grown cells of the B. pullorum strains and of most of the B. dentium strains were devoid of detectable levels of 6PGD. The zymograms of more than 60% of the strains studied were species specific. Nearly half of the other strains had significant overlapping of transaldolase and 6PGD patterns, and they were assigned therefore to species on the basis of an additional marker, 3-phosphoglyceraldehyde dehydrogenase production, the results of which are not reported here in detail. Of the species studied, B. asteroides exhibited the greatest variability in electrophoretic types of both transaldolase and 6PGD. Correlations between electrophoretic data, deoxyribonucleic acid homology relationships between the species, and ecology are discussed.