Enhanced antimicrobial activity of lactoferrin by binding to the bacterial surface.

In order to elucidate the mechanisms involved in the antibacterial activity of lactoferrin, quantitative determinations of siderophore production and lactoferrin adsorption on various bacterial species were performed. The binding of lactoferrin took place both on Gram-positive and Gram-negative species and occurred with bacterial cells grown in stress or in excess of iron. The different degrees of sensitivity to lactoferrin observed could not be directly related to the type and amount of siderophores produced. However, it was possible to find a correlation between the capacity of some strains to bind lactoferrin and their sensitivity to this protein. These data suggest that the binding of lactoferrin on the cell surface can result in an antibacterial activity additional to iron witholding.