Structural investigation of rhamnose-rich polysaccharides from Streptococcus dysgalactiae bovine mastitis isolate.

Different rhamnose-rich polysaccharides (RRP) were identified in the cell envelope of the Gram-positive bovine mastitis isolate Streptococcus dysgalactiae 2023. Structural investigations of the 1D and 2D nuclear magnetic resonance experiments as well as chemical analyses identified as main components l-Rha and d-GalNAc. Two main RRP were characterized, namely 1 being composed of the repeating unit {→3)-α-l-Rhap-(1→2)-[α-d-GalpNAc-(1→3)-β-d-GalpNAc-(1→3)-]α-l-Rhap-(1} and 2 possessing the repeat [→2)-α-l-Rhap-(1→3)-α-l-Rhap-(1→].