Recognition of Fusobacterium nucleatum subgroups Fn-1, Fn-2 and Fn-3 by ribosomal RNA gene restriction patterns.

DNA from representative strains of Fusobacterium nucleatum subgroups Fn-1, Fn-2 and Fn-3 was digested with restriction enzymes EcoRI and TaqI and the electrophoretically separated fragments hybridized with a 32P-16S rRNA gene probe from E. coli. The rRNA gene restriction patterns from DNA digested with either enzyme allowed the clustering of strains into the three subgroups. However, TaqI digested DNA yielded a wider distribution of taxonomically useful bands (ca 0.65 +/- 14.3 kbp) and the pattern produced was characteristic of each subgroup. The present method is a simple and reliable means of identifying the three subgroups of F. nucleatum and provides a useful method for further studies of the heterogeneity of F. nucleatum.