Identification of lactoferrin-binding proteins in bovine mastitis-causing Streptococcus uberis

All strains of Streptococcus uberis evaluated bound to lactoferrin (Lf) in milk as detected by polyacrylamide gel electrophoresis and Western blotting . A biotin-avidin-based microplate binding assay and ELISA also revealed th at these bacterial strains bound to purified Lf. Binding of bacteria to Lf was not inhibited by mannose and galactose, indicating that glycosidic doma ins of the Lf molecule were not involved in binding. Lf binding was also un affected by bovine transferrin. Western blot analysis demonstrated that the re were at least two bacterial proteins involved in Lf-binding. Lf binding by S. uberis could enable this bacterium to acquire iron necessary for its growth. (C) 1999 Federation of European Microbiological Societies. Publishe d by Elsevier Science B.V. All rights reserved.