Characterization of novel human oral isolates and cloned 16S rDNA sequences that fall in the family Coriobacteriaceae: description of Olsenella gen. nov., reclassification of of Lactobacillus uli as Olsenella uli comb. nov and description of Olsenella profusa sp nov.

The diversity of organisms present in the subgingival pockets of patients w ith periodontitis and acute necrotizing ulcerative gingivitis (ANUG) were e xamined previously. The 16S rRNA genes of subgingival plaque bacteria were amplified using PCR with a universal forward primer and a spirochaete-selec tive reverse primer. The amplified DNA was cloned into Escherichia coli. In one subject with ANUG, 70 clones were sequenced. Seventy-five per cent of the clones were spirochaetal, as expected. Twelve of the remaining clones f ell into two clusters that represent novel phylotypes in the family Corioba cteriaceae. The first novel phylotype was most closely related to Atopobium rimae (98% similarity). The phylotype probably represents a novel Atopobiu m species, but will not be named until cultivable strains are obtained. The second novel phylotype was only 91% similar to described Atopobium species and 84% similar to Coriobacterium glomerans. The 16S rRNA sequences of the type strain of Lactobacillus uli and a strain representing the Moores' Eub acterium group D52 were determined as part of on ongoing sequence analysis of oral bacteria. The sequence for L. uli was more than 99.8% similar to se quences for the second clone phylotype. it therefore appears that the secon d clone phylotype and L. uli represent the same species. The sequence for t he Eubacterium D52 strain was 95.6% similar to that of L. uli. The G+C cont ent of the DNA of L. uli and Eubacterium D52 is 63-64 mol%. These organisms are thus distinct from the neighbouring genus Atopobium, which has a DNA G +C content of 35-46 mol%. A new genus, Olsenella gen. nov., is proposed for these two species on the basis of phenotypic characteristics and 16S rRNA sequence analysis to include Olsenella uli comb. nov. and Olsenella profusa sp. nov.