Figure 4
Relative respiration rates of Arthrobacter sp. Rue61a and A . aurescens TC1 in response to Pb2+. Arthrobacter sp. Rue61a (A) and A. aurescens TC1 (B) were cultivated in LB medium in the presence and absence of 10 μM Pb(NO3)2. Cells were resuspended in 10 mM MES buffer, pH 6.5, and respiration rates of cells pre-grown in the presence of Pb(NO3)2 (empty squares) and of cells grown in the absence of Pb2+ (filled squares) were measured at different concentrations of Pb(NO3)2. The relative respiration rate is the ratio of the ΔO2 after and prior to Pb(NO3)2 injection. Data represent mean values ±SD (standard deviations) from three independent experiments. The continuous lines represent fits of a dose–response equation to the data of the LB-grown cells.