The production of bacteriocin-like substances by the oral bacterium Streptococcus salivarius

Inhibitory substances produced by six strains of Streptococcus salivarius were isolated and partially characterized. The six prototype producer strains were selected initially on the basis of their differing spectra of inhibitory activity when tested against a set of nine standard indicator strains. Optimal production conditions were defined for each producer strain and inhibitor-containing extracts were obtained for characterization studies. All of the inhibitors appeared to be proteinaceous substances of molecular weight greater than 3500. When tested against a Streptococcus pyogenes indicator strain, one of the inhibitors was bactericidal, but the other five appeared to be bacteriostatic. Some differences between the inhibitors were observed with respect to heat and enzyme sensitivities.