Figure 3

Accumulation of ethidium bromide in E. coli KAM3 cells harbouring pBAD202 and pBAD/ orf2. E. coli KAM3 cells containing the cloning vector pBAD202 and the recombinant plasmid pBAD/orf2 were grown in LB medium at 37°C and treated as described in Methods. Ethidium bromide was added to cell suspensions carrying pBAD202 (◆) or pBAD/orf2 (□), at a final concentration of 20 μM whereas the efflux inhibitor CCCP was added 9 min after the addition of ethidium bromide at a final concentration of 30 μM. The experimental error bars showed standard deviations of triplicate determinations.