Surface protein of a Streptococcus agalactiae isolate

Abstract

A Streptococcus agalactiae isolate of bovine origin was cultured in broth; log-phase cells were washed and radioiodinated and subsequently extracted at low pH in the presence of a nonionic detergent. A protein antigen was purified from concentrated extract by ultracentrifugation, gel filtration, and ion-exchange chromatography. The molecular weight of the protein was estimated at 31,800. The agglutinogenic character of the protein indicated its localization at the cell surface.