Ion permeability induced by bacteriocins of Lactobacillus acidophilus M247on artificial lipid membranes

Bacteriocins produced by lactic acid bacteria are known to induce ion perme ability on the cytoplasmic membranes of several competing bacteria. The act ivity of a bacteriocin produced by Lactobacillus acidophilus M247 was studi ed on artificial lipid membranes made using the technique of Montal-Mueller . Bacteriocin was added to the KCI solution bathing one side of black lipid membrane (BLM). By applying external voltages of different polarity, incre ases in the membrane conductance were observed and channels with elementary conductance of about 68-70 pS were detected. The log-log plot of macroscop ic conductance versus bacteriocin concentration was linear with a slope of 1 for the purest samples, indicating that one molecule of active bacterioci n is involved in the channel formation. (C) 1999 Elsevier Science S.A. All rights reserved.