RELATIONSHIP BETWEEN ANTIBACTERIAL ACTIVITY AND CELL-SURFACE BINDING OF LACTOFERRIN IN SPECIES OF GENUS MICROCOCCUS

Human lactoferrin was bactericidal in vitro for Micrococcus luteus but not for other Micrococcus species (M. radiophilus, M. roseus and M. v arians). A correlation between the binding of lactoferrin to the bacte rial surface and the antimicrobial action was observed. Viability assa ys showed that ferric, but not ferrous, salts prevented binding and co nsequently M. luteus was not killed. The unsaturated form of lactoferr in showed a greater affinity than that of the iron-saturated molecule for lipomannan, a lipoglycan present on the cell wall of M. luteus, su pporting the role for lipomannan as one of the possible binding sites of lactoferrin on M. luteus.