MODE OF ACTION OF PEDIOCIN ACH FROM PEDIOCOCCUS-ACIDILACTICI-H ON SENSITIVE BACTERIAL STRAINS

The peptide, pediocin AcH, from Pediococcus acidilactici H binds to the cell surface of Lactobacillus plantarum NCDO 955, its resistant mutant and several other sensitive and resistant Gram-positive bacteria but not to Gram-negative bacteria. Sensitive cells, following treatment with pediocin AcH, lost intracellular K+ ions, u.v.-absorbing materials, became more permeable to ONPG and, in some strains, lysed. Binding of pediocin AcH was maximum at pH 6.0. Anions of several salts inhibited binding of pediocin AcH but this was overcome by increased concentrations of pediocin AcH. Treatment of sensitive cells with 1 % SDS, 4 mol/l guanidine-HCl, several organic solvents and enzymes did not reduce subsequent binding of pediocin AcH. Partially purified cell wall from a sensitive strain was also able to bind pediocin AcH. However, treatment of the cell walls to remove lipoteichoic acid prevented binding. These molecules might, therefore, be one of the binding sites of pediocin AcH.