Glutamate Dehydrogenase and 2-Oxoglutarate Reductase Electrophoretic Patterns and Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization among Human Oral Isolates of Fusobacterium nucleatum

Abstract

The electrophoretic mobilities of glutamate dehydrogenase and 2-oxoglutarate reductase were compared for three reference strains and 30 human, oral isolates of Fusobacterium nucleatum. Both enzymes allowed the same strains to be grouped into three electrophoretic clusters, designated groups Fn-1, Fn-2, and Fn-3. Group Fn-1 contained the type strain of F. nucleatum, strain ATCC 25586, and nine clinical isolates. Group Fn-2 comprised 20 strains and appeared to contain the strains of F. nucleatum that are isolated most commonly from oral cavities. Strain NCTC 10953 (formerly “Fusobacterium polymorphum”) was a member of this cluster. Strains of group Fn-3 were rarely isolated; this group contained three isolates and reference strain NCTC 11362, which was listed previously as “Fusobacterium fusiforme.” The deoxyribonucleic acid (DNA) base compositions of all strains were between 25 and 27 mol% guanine plus cytosine. Under optimal conditions of DNA-DNA hybridization, all of the strains exhibited high levels of DNA homology (73 to 99%) to the three reference DNA probes belonging to groups Fn-1, Fn-2, and Fn-3. However, under stringent DNA hybridization conditions there was evidence of more genetic homogeneity within each group.