FIG. 4.

(A) Time course of mercury uptake by resting cultures harboring various plasmids. Resting cultures were resuspended in LB medium containing 5 μM Hg²⁺ and were incubated for 20 min. Cells were harvested at various times, and the supernatant was removed by centrifugation for 30 s. (B) Hg²⁺ bioaccumulation capacity of JM109 cells (0.265 mg [dry weight]) harboring either pLO20 or pCLTP/pMC20. Bioaccumulation of Hg²⁺ was measured at various concentrations after 1 h of incubation. (C) Effect of cadmium on bioaccumulation of Hg²⁺. JM109 cells harboring either pLO20 or pCLTP/pMC20 were incubated with 5 nmol of Hg²⁺ and various concentrations of Cd²⁺. The amount of Hg²⁺ accumulated by cells after 1 h was determined.