Bactericidal Kinetics of 3 Lactoferricins Against Staphylococcus aureus and Escherichia coli

Abstract

Bovine lactoferricin is an antimicrobial, cationic peptide generated upon gastric pepsin cleavage of bovine lactoferrin. We investigated the bactericidal effects of native lactoferricin [Lfcin B(17-41)], a shortened derivative [Lfcin B(17-31)] and the all-D-amino acid counterpart of Lfcin B(17-31) against Escherichia coli and Staphylococcus aureus. The results revealed different activities for the peptides against Gram-positive and -negative bacteria. D-Lfcin B(17-31) was the most efficient peptide against E. coli. The same peptide showed improved activity against S. aureus, D-Lfcin B(17?31) showed a significant better efficacy when compared to the L-form, but not when compared to Lfcin B(17?41). There was no correlation between the bactericidal concentrations and the time needed to achieve maximum effect. This indicates the importance of structural differences between the peptides and/or bacteria and implies that the simple thesis of 1 antibacterial target is not valid for lactoferricin.