Effects of energy metabolism on the release of bound proflavine from sensitive and resistant Escherichia coli.

Proflavine inhibited the aerobic and anaerobic utilization of glucose by sensitive but not by resistant Escherichia coli. In resistant cells that had bound proflavine, glucose utilization was accompanied by release of the dye. After glucose was used up, the cells could again take up proflavine. If the amount of proflavine bound to sensitive cells was too low to inhibit glucose utilization, adding glucose to these cells caused them to release the dye. With higher proflavine concentrations, inhibitory to glucose utilization, the dye remained cell bound. Thus, metabolic energy causes the release of proflavine by both sensitive and resistant cells. In the former, energy production is inhibited by proflavine, and thus the dye prevents its own release. Chloramphenicol did not interfere with metabolically induced release of proflavine from resistant cells. Cyanide inhibited the glycerol-induced loss of proflavine, but not the glucose-induced loss. Azide and carbonyl cyanide m-chlorophenylhydrazone could prevent proflavine release without inhibiting glucose utilization.