Abstract

Certain reducing agents containing sulfhydryl groups are important to the in-vitro survival of Treponema pallidum. Discrepancies occur, however, concerning the agents and the concentrations that are optimal. To clarify some of this confusion, sulfhydryl oxidation was determined using procedures and experimental conditions commonly used for T pallidum. Sulfhydryl oxidation varied according to the type of culture medium, the size of the culture vessels, the volume of the culture medium, and the gaseous environment within the culture vessels, as well as the method of extracting treponmes from infected testicular tissue. Dithiothreotol maintained highly reduced conditions by reducing disulfide groups to sulfhydryl groups. Lastly, the organisms influenced the sulfhydryl concentration by either direct oxidation or specific uptake. The sulfhydryl content was sharply decreased in the presence of viable preparations of T pallidum compared with heated preparations or membrane filtrates of viable preparations.