Purification and characterization of Streptococcus adjacens (nutritionally variant Streptococcus serotype II) group antigen

Abstract

Nutritionally variant streptococci (NVS) possess amphiphiles which are serologically distinct from lipoteichoic acid and which serve as group-specific antigens for NVS. The objective of this study was to purify and characterize the NVS serotype II (Streptococcus adjacens) amphiphile. Amphiphile was isolated from stationary-phase culture supernatants of NVS strain 81 (NVS serotype II). Phenol-water extracts of culture supernatants were subjected to hydrophobic interaction chromatography and gel filtration chromatography. A homogeneous preparation of amphiphile (22 mg; 8.5 x 10(6) hemagglutination units) was recovered, and its approximate molecular size (23,000 to 24,000 Da) and chemical composition were determined. Purified S. adjacens amphiphile contained phosphorus, ribitol, galactose, galactosamine, alanine, and fatty acids in molar ratios of 1.00:0.88:1.39:1.10:0.08:0.24. Since ribitol, galactose, and galactosamine were the primary carbohydrate components, the amphiphile may exist as a polyribitol phosphate with galactose and galactosamine substituents. Preliminary structural analysis demonstrated the presence of phosphodiester bonds within the amphiphile structure. Finally, the amphiphile serves as the S. adjacens group antigen.