FIG. 6.

Effect of CCM pH on C. burnetii metabolic activity. The pH for optimal C. burnetii metabolism in CCM was determined by incubating bacteria for 3 h in CCM adjusted to different pH values in the presence of [³⁵S]Cys-Met. Radiolabel incorporation was measured by scintillation counting. C. burnetii incorporation of [³⁵S]Cys-Met is expressed as the increase relative to the incorporation of organisms incubated in CCM (pH 7.0) (negative control). Asterisks indicate statistically significant (P < 0.05) differences between the indicated samples. The broken line represents the level of radiolabel incorporation in CCM (pH 7.0) normalized to 1.