Forms of lactoferrin: their antibacterial effect on enterotoxigenic Escherichia coli.
The antibacterial effects of various forms of lactoferrin on enterotoxigenic strains of Escherichia coli were tested in vitro using a microassay for bacterial growth. Native and apo-lactoferrin exhibited variable activity against 19 strains, whereas holo-lactoferrin had no effect. At a concentration of .2 mg/ml of apo-lactoferrin, strains could be distinguished as either sensitive or resistant to inhibition. Zinc-saturated lactoferrin was as inhibitory as apo-lactoferrin when sensitive and resistant strains were tested over the concentration range .04 to 1.0 mg/ml of lactoferrin. A bactericidal effect was observed for native, apo-, and Zn-saturated lactoferrin against some sensitive strains. The antibacterial activity of apo-lactoferrin depended on bacterial inoculum size and was not enhanced by the addition of lysozyme. Addition of holo-lactoferrin or cytochrome c diminished the antibacterial effect of apo-lactoferrin, whereas addition of BSA had no effect. Resistance to inhibition by lactoferrin was not related to the production of bacterial siderophores.
Dionysius
D A
DA
International Food Institute of Queensland, Queensland Department of Primary Industries, Hamilton, Australia.
Grieve
P A
PA
Milne
J M
JM
D000818:Animals; D001059:Apoproteins / Q000494:pharmacology; D002417:Cattle; D004768:Enterotoxins / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D007700:Kinetics; D007781:Lactoferrin / Q000494:pharmacology*; D009113:Muramidase / Q000494:pharmacology
D001059:Apoproteins; D004768:Enterotoxins; C039223:apolactoferrin; D009113:Muramidase; D007781:Lactoferrin