FIG. 3.

Effect of substrate concentration on uptake of (R)-dichlorprop (A), (S)-dichlorprop (B), and 2,4-D (C) by S. herbicidovorans MH grown on (R)-dichlorprop (A), (S)-dichlorprop (B), and succinate and 2,4-D (C). The initial uptake rates (15 s to 2 min) are plotted versus the external concentration of the substrate in the assay (0.7 to 450 μM). Analysis of the data gave K_t values of 108, 93, and 117 μM and V_max values of 19, 10, and 21 nmol min⁻¹ mg of protein⁻¹ for (R)- and (S)-dichlorprop and 2,4-D, respectively. Error bars represent relative standard deviations (15%) (see Materials and Methods).