Production of a bacteriocine-like substance by group-A streptococci of M-type 4 and T-pattern 4

A unique and characteristic bacteriocine-like inhibitor elaborated by M-type 4, T-pattern 4, group-A streptococci was isolated and partially purified. This inhibitor was found to be produced optimally in Todd-Hewitt broth; after extraction and concentration, was shown to be protein in nature, and to have a m.w. of c. 8000. It was extremely heat stable and acid tolerant, but was quickly inactivated in alkaline conditions. It could be demonstrated in cell-bound form, but 99.5% was found in culture supernates. It was specifically adsorbed by viable sensitive cells, and its mode of action was bacteristatic.