Structure of an exocellular polysaccharide produced by Streptococcus thermophilus

✍ Scribed by Thierry Doco; Jean-Michel Wieruszeski; Bernard Fournet; Didier Carcano; Patricia Ramos; Alain Loones

• Book ID: 102994805
• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 576 KB
• Volume: 198
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(90)84301-a

✦ Synopsis

Streptococcus thermophilus strains grown on skimmed milk produced a viscosifying, exocellular, and water-soluble polysaccharide which contains D-glucose, D-galactose, and N-acetyl-D-galactosamine in the ratio of 1:2:1. Methylation analysis identified the glycosidic linkages in the tetrasaccharidic repeating-unit, and Smith degradation and nitrous deamination after N-deacetylation gave the sequence of monosaccharides in the repeating-unit. The anomeric configurations of the sugar residues were determined by oxidation of the peracetylated polysaccharide with chromium trioxide and by 1H- and 13C-n.m.r. spectroscopy. The following structure was assigned to the repeating unit of the polysaccharide,----3)-beta-D-Galp-(1----3)-[alpha-D-Galp-(1----6)]-beta- D- Glcp-(1----3)-alpha-D-GalpNAc-(1----.