CHARACTERIZATION OF A BACTERIOCIN PRODUCED BY STREPTOCOCCUS-THERMOPHILUS ST134

A pi-I-dependent adsorption/desorption technique was used to screen St reptococcus thermophilus strains for the production of bacteriocins. A gar-diffusion tests with S. thermophilus strains as targets identified 13 out of 41 strains as producers of antibacterial activity, Thermoph ilin A, the bacteriocin-like substance present in the culture supernat ant of S. thermophilus ST134 was purified to homogeneity by ammonium s ulfate precipitation and ion-exchange chromatography, followed by ultr afiltration. Thermophilin A is a relatively heat-stable and apparently glycosylated bacteriocin with a bactericidal mode of action against s ensitive cells.