The nutrition of treponeme strain PR-7 isolated from the intestinal tract of a pig with swine dysentery was studied. The organism fermented arabinose, xylose, maltose, cellobiose, glucose, galactose, mannose, lactose, pectin, and starch. The end products of fermentation of glucose were major amounts of succinic acid, moderate amounts of acetic and formic acid, and a trace of lactic acid and ethanol.Strain PR-7 required glutamate, aspartate, proline, leucine, methionine, arginine, valine, alanine, serine, lysine, glycine, threonine, isoleucine, phenylalanine, tyrosine, histidine, tryptophan, glutamine, asparagine, and spermine. The organism also required nicotinamide, folic acid, pyridoxal, thiamine, riboflavin, pantothenate, choline, α-lipoic acid, and biotin. The fatty acids isobutyrate, n-valerate, acetate, and pyruvate were needed as well as ammonium sulfate. A fermentable energy source such as glucose was necessary for growth, as well as carbon dioxide. Heme was also required and the organism was stimulated by vitamin B12, ascorbic acid, ornithine, and para-aminobenzoic acid. Heme could be replaced by catalase, myoglobin, and peroxidase.Ten other treponemes that were isolated from the intestines of normal pigs as well as from pigs with swine dysentery and had phenotypic characteristics similar to strain PR-7 grew in the defined medium.