INVESTIGATIONS OF THE TAXONOMY AND SYSTEMATICS OF FUSOBACTERIUM-NUCLEATUM USING ALLOZYME ELECTROPHORESIS

Fusobacterium nucleatum forms part of the resident microbiota in both oral and extraoral sites in humans and animals. It is also involved in infections in such sites. Despite the genetic heterogeneity within th e species, it has been divided into five subspecies, the validities of which have been questioned. In the present study, 44 F. nucleatum iso lates were examined at 21 enzyme loci by using the allozyme electropho retic technique to establish an accurate genetic framework for taxonom ic purposes. Three distinct genetic clusters were identified; one clus ter consisted exclusively of extraoral isolates, another cluster consi sted predominantly of human oral isolates, and the third cluster consi sted of a single human oral isolate. Our results highlight the urgent need for extensive biochemical, immunological, and epidemiological stu dies to accurately define the systematics of the genus Fusobacterium b ased on the frame work derived in this study by using 21 independent g enetic characteristics.