Fatty Acid Requirements of the Kazan 5 and Reiter Strains of Treponema pallidum.

The fatty acid requirements of two avirulent treponemes were investigated by using a "lipid-poor" albumin-thioglycolate medium. The Kazan 5 and the Reiter stains of Treponema pallidum required a pair of fatty acids for growth. One member of the pair was saturated and the other was unsaturated. The saturated fatty acids could contain either an odd or even number of carbon atoms, but a chain length of at least 14 carbon atoms was necessary. Unsaturated fatty acids with one, two, or three double bonds were satisfactory if they contained 15 or more carbon atoms. The pair of fatty acids could be replaced with a single 18-carbon monounsaturated fatty acid if it was in the trans configuration rather than the naturally occurring cis form.