Characterization of a Bacteriocin from Staphylococcus aureus Strain 462

Abstract

Staphylococcus aureus 462 is one of three bacteriocin-producing strains selected for study from 200 isolates of staphylococci of animal origin. These bacteriocins are specific in their activity, inhibiting the growth of certain strains of S. aureus and other gram-positive species, but not gram-negative organisms. Staphylococcin 462 was not found in significant concentrations in the supernatant fluid of broth cultures, nor was it released into the suspending liquid when the cells were mechanically disrupted. However, extraction of the cells with 7 M urea resulted in the liberation of much of the activity. The material was purified by gel permeation chromatography by using Sephadex G-200 and by preparative electrophoresis on polyacrylamide gels in the presence of sodium dodecyl sulfate. Chemical analysis showed that the material consisted of roughly 90% protein and 3% lipid. The molecular weight of sodium dodecyl sulfate-dissociated staphylococcin 462 was calculated to be about 9,000.