Eubacterium yurii subsp. yurii sp. nov. and Eubacterium yurii subsp. margaretiae subsp. nov.: Test Tube Brush Bacteria from Subgingival Dental Plaque

Abstract

Eighteen strains of anaerobic gram-positive rods exhibiting an unusual three-dimensional cellular arrangement resembling test tube brushes (TTB) were recovered from subgingival dental plaque samples of randomly selected periodontitis patients. The isolates were obtained from subgingival sites exhibiting bone loss of .gtoreq. 20% and pocket depth of .gtoreq. 4 mm. Based upon biochemical profiles, these organisms belong to the family Propionibacteriaceae and are somewhat similar biochemically to some species of Eubacterium, notably Eubacterium saburreum. Relatedness between TTB bacteria and E. saburreum was assessed by deoxyribonucleic acid base composition and deoxyribonucleic acid renaturation rates. Moles percent guanine plus cytosine were 32 and 33, respectively. Hybridization studies showed 32% relatedness between E. saburreum and TTB bacteria, indicating that they are related but distinct species. We therefore propose a new species, Eubacterium yurii. Strains of this species characteristically form three-dimensional brushlike aggregates mediated by an amorphous, extracellular material E. yurii is divided into two subspecies that exhibited 53% homology: E. yurii subsp. yurii, which is phosphatase positive, and E. yurii subsp. margaretiae, which is phosphatase negative.