Figure 6. Auramine-O (green) and Nile Red staining of Mtb cells in Percoll gradient fractions of Mtb culture after 18 day in multiple-stress.

Density gradient fractionation was performed as described in figure 5. Changes in acid-fast property, lipid accumulation and elongated cells with cording were observed. Nile Red staining Mtb cells concentrated in higher fraction numbers at lighter density. No cells were detected in fractions 1, 2 and only a few were detected in fraction 3. Fr, fraction; fraction numbers ascending from the bottom of the tube to the top. Bar = 5 µM.