Structural analysis of the exopolysaccharide produced by Streptococcus thermophilus S

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Abstract The use of lactic acid bacteria in fermentation of milk results in favorable physical and rheological properties due to in situ exopolysaccharide (EPS) production. The EPS from S. thermophilus ST1 produces highly viscous aqueous solutions and its structure has been investigated by NMR spectroscopy. Notably, all aspects of the elucidation of its primary structure including component analysis and absolute configuration of the constituent monosaccharides were carried out by NMR spectroscopy. An array of techniques was utilized including, inter alia, PANSY and NOESY-HSQC TILT experiments. The EPS is composed of hexasaccharide repeating units with the following structure: â?? 3)[α-d-Glcp-(1 â?? 4)]-β-d-Galp-(1 â?? 4)-β-d-Glcp-(1 â?? 4)[β-d-Galf-(1 â?? 6)]-β-d-Glcp-(1 â?? 6)-β-d-Glcp-(1 â??, in which the residues in square brackets are terminal groups substituting backbone sugar residues that consequently are branch-points in the repeating unit of the polymer. Thus, the EPS consists of a backbone of four sugar residues with two terminal sugar residues making up two side-chains of the repeating unit. The molecular mass of the polymer was determined using translational diffusion experiments which resulted in Mw = 62 kDa, corresponding to 64 repeating units in the EPS.

• Content Type Journal Article
• DOI 10.1007/s10858-010-9413-0
• Authors
  • Elin Säwén, Arrhenius Laboratory, Stockholm University Department of Organic Chemistry 106 91 Stockholm Sweden
  • Eine Huttunen, University of Helsinki Department of Food Technology 00014 Helsinki Finland
  • Xue Zhang, University of Helsinki Department of Food Technology 00014 Helsinki Finland
  • Zhennai Yang, Northeast Agricultural Research Center of China Center of Agro-food Technology 130124 Changchun Jilin Peopleâ??s Republic of China
  • Göran Widmalm, Arrhenius Laboratory, Stockholm University Department of Organic Chemistry 106 91 Stockholm Sweden

• • Journal Journal of Biomolecular NMR
  • Online ISSN 1573-5001
  • Print ISSN 0925-2738
  • Journal Volume Volume 47
  • Journal Issue Volume 47, Number 2

Source: Journal of Biomolecular NMR