FIG. 2.

Accumulation of norfloxacin in E. coli cells expressing or not expressing the NorMI protein of B. melitensis. E. coli AG100A harboring a vector expressing NorMI (pUC19-NorMI) (▴) or harboring pUC19 alone (○) was grown in Luria-Bertani broth. Norfloxacin was added to the cell suspensions at a final concentration of 100 μM. After 15 min, CCCP was added to the suspensions at a final concentration of 100 μM. Samples were removed at the indicated times, and the concentration of norfloxacin extracted from the cells was quantified by spectrofluorimetry.