Antimicrobial activity of a 14-residue synthetic peptide against foodborne microorganisms.

A chemically synthesized short-chain peptide composed of six leucine and eight lysine (6K8L) residues was demonstrated to be biocidal against several foodborne organisms including Escherichia coli O157:H7, Listeria monocytogenes, Pseudomonas fluorescens, and Kluyveromyces marxianus suspended in phosphate buffer at concentrations of 5 to 50 microg/ml. All strains were reduced by 3 log10 CFU/ml within 10 min at peptide concentrations of <10 microg/ml. The peptide reduced by 3 log10 CFU/ml E. coli O157:H7 counts in apple juice and was active over the pH range of 3.5 to 7. Peptide concentrations of 100 microg/ml inhibited the aerobic and anaerobic microorganisms present in meat exudate liquid. However, the peptide was not effective against E. coli O157:H7 in skim milk at concentrations up to 100 microg/ml.