Purification of bacteria
To purify the elementary bodies of Chlamydophila abortus Everson et al  used a density barrier of 18% (w/v) Nycodenz® containing 0.13 M NaCl, 3 mM KCl, 0.3 mM CaNa2EDTA, 5 mM Tris-HCl, pH 7.2.
It was prepared from Nycoprep™ 1.15 (an isoosmotic solution of 27.6% Nycodenz® containing 3mM KCl, 0.3 mM CaNa2-EDTA, 5 mM Tris-HCl, pH 7.4, ρ = 1.15 g/ml). This is no longer commercially available so all solutions must be made from Nycodenz® powder as described below. The CaNa2-EDTA in the Nycoprep™ 1.15 was present only to increase solution stability during autoclaving and may not be necessary for the separation.
It may either be omitted or replaced by Na2-
EDTA. The Tris, in the example below, has been replaced by the more cell-friendly buffer Tricine. It is
highly probable that Nycodenz® can be replaced by iodixanol, but this has not been verified