Treponema succinifaciens sp. nov., an anaerobic spirochete from the swine intestine

The morphology, the general physiological characteristics, and the energy-yielding metabolism of an obligately anaerobic spirochete isolated from the colon of a swine were studied. Electron microscopy showed that the helical spirochetal cells possessed an outer sheath, a protoplasmic cylinder, and 4 periplasmic fibrils in a 2-4-2 arrangement. The spirochete grew in an atmosphere of N₂ in prereduced media containing a carbohydrate, NaHCO₃, rumen fluid, yeast extract, peptone, l-cysteine, and inorganic salts. The spirochete fermented carbohydrates and required substrate amounts of CO₂ (HCO₃^-) for growth. Amino acids were not fermented. Major fermentation products of cells growing with glucose as the substrate and in the presence of CO₂ were acetate, formate, succinate, and lactate. Small amounts of 2,3-butanediol, pyruvate, and acetoin were also formed. Determinations of enzymatic activities in cell extracts, and of radioactivity in products formed by growing cells from [1-¹⁴C]glucose, indicated that this sugar was dissimilated to pyruvate via the Embden-Meyerhof pathway. The spirochetes used a coliform-type clastic reaction to metabolize pyruvate. Determinations of radioactivity in products formed from [¹⁴C]NaHCO₃ indicated that CO₂ was assimilated and used in succinate production. The guanine+cytosine content of the DNA was 36 mol%. This study indicates that this intestinal spirochete represents a new species of Treponema. It is proposed that the new species be named Treponema succinifaciens.Abbreviations cpm counts per minute - DTT dithiothreitol - EM Embden-Meyerhof - GC guanine plus cytosine - IgG immunoglobulin G - PC protoplasmic cylinder - PF periplasmic fibrils (axial fibrils) - OS outer sheath