Alteration of membrane permeability in Bacillus subtilis by clofoctol

When Bacillus subtilis was treated with a bacteriostatic concentration of clofoctol [2-(2,4-dichlorobenzyl)-4-(tetramethyl-1,1,3,3-butyl)phenol], UV-absorbing material was released. Electron micrographs showed evidence of physical alteration of the bacterial envelope. The uptake of [14C]glutamate was strongly inhibited by clofoctol, and preloaded glutamate was found to leak from the bacteria. Clofoctol caused an immediate and dramatic decrease in the amount of intracellular ATP. This was neither the consequence of the stimulation of an ATPase, nor of the inhibition of bacterial respiration. Both the proton gradient and the potential gradient across the cytoplasmic membrane collapsed and this inhibition of energy metabolism was sufficient to account for the inhibition of growth by clofoctol. At the same bacteriostatic concentration complete permeabilization of the bacteria occurred.