RESUMO
Staphylococcus aureus, a recognized human and animal pathogen is capable of producing various exoproteins, a process mediated by the mechanism of quorum sensing. This organism is screened in processed foods, and can produce food poisons. S. aureus is known for its ability to produce antimicrobial substances (bacteriocins) active against Listeria monocytogenes is the major pathogen in contamination of processed food and responsible of listeriosis. The aim of this research was to detect, purify and characterize partially an antimicrobial substance produced by S. aureus strain active against L. monocytogenes. In this investigation 46 S. aureus strains isolated from processed foods were studied. Activity was determined against L. monocytogenes by agar diffusion techniques. The partial purification and and characterization of antimicrobial substance was realized by molecular exclusion chromatography and polyacrylamide gel electrophoresis under denaturing and nondenaturing condictions. The antimicrobial substance that showed a molecular weight of 3.5 kDa approximately was resistant to different temperatures and wide pHs range. The antimicrobial substance could be classified as bacteriocins type II, subclass IIa. Future studies could be contributed to the possible use of the antimicrobial substance as food biopreservant.