Production, purification and some properties of Bac201, a bacteriocin-like inhibitory substance produced byStaphylococcus aureus AB201

Abstract

Staphylococcus aureus AB201, a clinical isolate from wound pus, produced a bacteriocin‐like inhibitory substance termed as Bac201, that was inhibitory to Streptococcus agalactiae, Enterococcus faecalis, Acinetobacter calcoaceticus, Neisseria meningitidis and a number of staphylococcal species. It was purified to homogeneity by ammonium sulfate precipitation, gel filtration (BioSil‐SEC‐125), and reversed‐phase high performance liquid chromatography (Vydac C4). The native Bac201 was sized at approximately 170‐kDa as determined by GF HPLC. Fraction‐I (native Bac201), having antibacterial activity was also examined by transmission electron microscopy and appeared as globular structure showing resemblance with phage‐like objects. The purification of Bac201 resulted in 466‐fold increase in specific activity and recovery of 0.94% of total antibacterial activity. The purified Bac201 migrated as single band on SDS‐PAGE with an estimated molecular mass of about 41‐kDa. Bac201 was sensitive to proteolytic enzymes, resistant to heat and organic solvents, and active over a wide range of pH (2.5–10). The amino acid composition revealed a general resemblance with other reported high molecular mass bacteriocins and predominance of glycine (39%), proline (13%) and alanine (8%) residues. Further results showed that Bac201 has a bactericidal effect on sensitive cells which is not produced by either cell lysis or apparent loss of membrane permeability.