Effect of acriflavine on the plasma membrane of Escherichia coli K12.

Plasma membranes of acriflavine-sensitive mutant (acrA) and acriflavine-resistant (acrA+, wild-type and true revertant) Escherichia coli K12 strains treated with acriflavine were observed under the electron microscope by means of the freeze-fracture technique. The plasma membrane of the acrA mutant exhibited a complex lamellar structure at the end of the cell when treated with 20 micrograms acriflavine ml-1. However, the membrane of the acrA+ cells also gave the lamellar complex when treated with a very high concentration of acriflavine (100 micrograms ml-1). The size of the intramembranous particles was not affected by the acriflavine treatments.