FIG. 3.

Active efflux of doxorubicin (A) and rhodamine 6G (B) from E. coli KAM3 cells harboring no plasmid, pUCA, or pQE30emrKY. Energy-starved cells of E. coli KAM3, KAM3/pUCA, and KAM3/pQE30emrKY cells were loaded with doxorubicin (A) or rhodamine 6G (B). The fluorescence of the compounds was continuously monitored with a Hitachi model F-2000 fluorescence spectrophotometer. Doxorubicin transport was measured with excitation at 478 nm and emission at 591 nm. Rhodamine 6G transport was measured with excitation at 529 nm and emission at 553 nm.