Mode of inhibitory action of a bacteriocin produced by Streptococcus mutans C3603.

The basis for the lethal activity of a bacteriocin produced by Streptococcus mutans C3603 (serotype c) was studied. Bacteriocin C3603 was found to adsorb to cells of representative strains of the seven serotypes of S. mutans. S. mutans BHT (serotype b) was used to study the adsorption and the lethal properties of bacteriocin C3603. The adsorption of bacteriocin to cells of S. mutans BHT was inhibited by treatment of cells with protease and beta-glucosidase and by such ligands as poly-L-lysine, poly-L-arginine, L-aspartic acid, L-glutamic acid, glutathione, oxidized glutathione, poly-L-aspartic acid, and poly-L-glutamic acid. The adsorption to cells was also inhibited by oligosaccharides and glucosamine. Mixtures of anionic and cationic amino acids or polyamino acids did not greatly enhance or antagonize the inhibition of adsorption of bacteriocin C3603 to cells. Sodium hydroxide extracts of cell walls and cell wall-membranes contained carbohydrates and proteins; however, only proteins were found to bind to bacteriocin or to a bacteriocin affinity column. The sodium hydroxide extracts contained about 35 protein bands as determined by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis. Bacteriocin C3603 was found to immediately inhibit the synthesis of proteins, DNA, and RNA of cells and to slowly release DNA from cells of S. mutans BHT.