Purification and characterization of a novel bacteriocin produced by Enterococcus faecalis CG-9 from human saliva

Abstract

Strain CG-9, isolated from human saliva and identified as Enterococcus faecalis, produced a component that inhibits the growth of Gram-positive and Gram-negative bacteria. The active peptide from the cell-free supernatant of Enterococcus faecalis CG-9 was purified in three steps: (1) precipitation with 70% saturated ammonium sulfate: (2) cation-exchange chromatography, (3) gel filter chromatography. The purified bacteriocin exhibited a wide range of antimicrobial activity against many food-borne spoilage and Pathogenic bacteria such as Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, as well as some yeast. The bacteriocin was heat stable, pH resistant and protease sensitive. Ethylenediaminetetraacetic acid, sodium dodecyl sulfate, Tween 80 and 6% sodium chloride did not decrease the activity. The characterization, antimicrobial spectrum and molecular mass of this bacteriocin suggested that it was a novel bacteriocin with potential research and application value in food industry.