Summary auto-generated
Researchers isolated and characterized a novel Treponema species, designated Treponema medium, from subgingival dental plaque of a periodontal disease patient. The organism was obtained from a 52-year-old male using guinea pig inoculation followed by repeated well-plate isolation. Strain G7201T measures 5-16 micrometers long and 0.2-0.3 micrometers wide, with five to seven periplasmic flagella and intracytoplasmic tubules characteristic of the Treponema genus. Biochemically, T. medium ferments multiple sugars including glucose, fructose, and maltose, producing acetic acid and butyric acid as major fatty acid products. The organism has a DNA G+C content of 51 mol%, which is similar to T. socranskii but differs from other oral treponemes. DNA-DNA hybridization showed less than 30% homology with all tested Treponema species, including T. denticola, T. vincentii, and T. pallidum. 16S rRNA gene sequence analysis placed the new strain in a distinct phylogenetic position, diverging at the species level from previously described treponemes. The unique protein profiles on SDS-PAGE gels and distinctive immunological reactions with anti-44-kDa serum further differentiated T. medium from established species. These comprehensive morphological, biochemical, genetic, and immunological analyses collectively supported establishment of T. medium as a new species.
Key findings
- Treponema medium is a novel anaerobic spirochete isolated from human subgingival plaque with 51 mol% G+C content and five to seven periplasmic flagella
- DNA-DNA hybridization showed less than 30% homology with all established Treponema species, confirming species-level distinction
- 16S rRNA phylogenetic analysis placed T. medium in a distinct cluster, diverging at the species level from T. denticola, T. phagedenis, and T. pallidum
- T. medium is saccharolytic, fermenting 11 different sugars and producing ammonia, hydrogen sulfate, and volatile fatty acids (primarily acetic and butyric acid)
- Unique protein profiles and anti-44-kDa serum-specific immunological reactions differentiated T. medium from other known oral treponemes
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Abstract
A new Treponema species, for which we propose the name Treponema medium, was isolated from subgingival plaque from an adult with periodontal disease. The morphological characteristics, differential biochemical characteristics, and protein profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels of this organism are described. The guanine-plus-cytosine content of the DNA of T. medium is 51 mol%. The levels of DNA-DNA relatedness of the new species to other Treponema species, including Treponema denticola, Treponema vincentii, Treponema socranskii, Treponema pallidum, and Treponema phagedenis, are less than 30%. A phylogenetic analysis based on 16S rRNA sequences distinguished the new Treponema strain from strains belonging to previously described Treponema species. The type strain of T. medium is strain G7201.