Treponema parvum sp nov., a small, glucuronic or galacturonic acid-dependent oral spirochaete from lesions of human periodontitis and acute necrotizing ulcerative gingivitis

Small oral spirochaetes with a strict dependence on either glucuronic acid (GluA) or galacturonic acid (GalA) were isolated from European patients wit h periodontitis and from Chinese patients with either gingivitis or acute n ecrotizing ulcerative gingivitis (ANUG). Thirteen such isolates were simila r phenotypically to Treponema pectinovorum ATCC 33768(T) and this classific ation was confirmed by 16S rRNA sequencing. However, four isolates differed from T. pectinovorum by their small cell size, by a prominent beta -glucur onidase activity, by a distinct protein and antigen profile, by an inabilit y to grow on pectin as sole source of carbohydrate and by a markedly enhanc ed growth rate when supplied with a second carbohydrate (L-arabinose, D-gal actose, D-glucose, D-fructose, D-mannitol, D-mannose, pectin, D-ribose or D -xylose) in addition to the essential GluA/GalA. By 16S rRNA sequencing the se four isolates clustered in the recently described phylotype 'Smibert-2'. T. pectinovorum (14 strains) and 'Smibert-2' (four isolates with beta -glu curonidase activity) could each be subdivided into two serotypes based on i mmunoblot reactivity with two mAbs. Representatives of the two groups, incl uding T. pectinovorum ATCC 33768T, showed a 1:2:1-type periplasmic flagella r arrangement. 'Smibert-2' is described as a novel species, Treponema parvu m sp, nov., with isolate OMZ 833(T) (= ATCC 700770(T)) proposed as the type strain and OMZ 842 (= ATCC 700773) as reference strain for a second seroty pe.