Antibacterial activity of Lactoferrin and Lactoferricin against oral Streptococci

Lactoferrin (Lf) is an iron-binding glycoprotein which exhibits antibacterial activity against a broad range of Gram-negative and Gram-positive bacteria. The mechanisms of this property are complex and involve iron sequestration as well as direct interaction with bacteria. Lactoferricin (LFcin), a Lf-derived peptide released by pepsin digestion of lactoferrin, is a more potent antibacterial compound than the native protein. In this study the antibacterial capacity of iron–free Lf, either human or bovine, and bovine Lfcin against the growth of some oral streptococci was investigated. Both human and bovine Lf, and bovine Lfcin were found to exert bacteriostatic effects which were dependent on their concentration and the streptococcal species tested. Even within species, strains exhibited different susceptibilities to the action of Lfs and Lfcin. The most sensitive streptococcal species were S. parasanguinis, S. gordoni and S. plurianimalium. Bovine Lfcin was also bactericidal against S. plurianimalium strain 5.1 at 9mg/ml. These findings are encouraging for the use of Lf/Lfcin as compounds with antimicrobial activity against oral streptococci.