Isolation and partial characterization of Bac201: A plasmid-associated bacteriocin-like inhibitory substance from Staphylococcus aureus AB201.

Staphylococcus aureus AB201, a clinical isolate from wound pus, produced a bacteriocin-like inhibitory substance termed as Bac201 that exhibited a bro ad-spectrum activity against both grampositive as well as gram-negative bac teria. Among gram-negative bacteria it was active against Neisseria meningi tidis and Acinetobacter calcoaceticus both being gram-negative cocci. Inhib ition due to the effect of organic acids, hydrogen peroxide, or bacteriopha ges was excluded. This inhibitory substance could not be induced or eluted. It was partially purified to 80% saturation by ammonium sulfate precipitat ion resulting in maximum specific activity of 829 AU/mg (25-fold increase). Proteolytic enzymes rapidly inactivated the antagonistic activity of the p artially purified material, whereas glycolytic and lipolytic enzymes had no effect. It remained stable in the presence of mild organic solvents. It co uld be stored at -20 degrees C without loss of activity, stable at 60 degre es C and 80 degrees C for 30 min, 100 degrees C for 20 min and autoclaving temperature (121 degrees C for 15 min), and exhibited activity within a wid e range of pH (2.5 - 10). Bac201 had an estimated M-r of 41kDa, as indicate d by activity detection after SDS-PAGE. Temperature-mediated (44 degrees C) plasmid curing studies suggested linkage of bacteriocin production to a 4. 8 MDa plasmid. The Bac201 was bactericidal rather than bacteriolytic.