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The exopolysaccharide produced byStreptococcus thermo-philus8S in reconstituted skimmed milk is a heteropolysac-charide containing D-galactose, D-glucose, D-ribose, and N-acetyl-D-galactosamine in a molar ratio of 2:1:1:1. Furthermore, the polysaccharide contains one equivalent of a novel open chain nononic acid constituent, 3,9-dideoxy-D-threo-D-altro-nononic acid, ether-linked viaC-2 toC-6 of an additionalD-glucose per repeating unit. | Eur. J. Biochem. 269 5590-5598 2002 FEBS 2002 doi 10.1046 j.1432-1033.2002.03266.x Characterization of the exopolysaccharide produced by Streptococcus thermophilus 8S containing an open chain nononic acid Elisabeth J. Faber Daan J. van Haaster Johannis P. Kamerling and Johannes F. G. Vliegenthart Bijvoet Center Department of Bio-Organic Chemistry Section of Glycoscience and Biocatalysis Utrecht University Utrecht the Netherlands The exopolysaccharide produced by Streptococcus thermophilus 8S in reconstituted skimmed milk is a heteropolysaccharide containing D-galactose D-glucose D-ribose and N-acetyl-D-galactosamine in a molar ratio of 2 1 1 1. analyses of the oligosaccharide obtained from the polysaccharide by de-N-acetylation followed by deamination and reduction demonstrated the hepta saccharide repeating unit to be - 4 -a-D-Gal 7- l- 2 -p-D-Rib - l- 4 -p-D-Gal - l- 4 -P-D-Glcp- 1 7 -Sug- l- 4 -P-D-GalpNAc- l- Furthermore the polysaccharide contains one equivalent of a novel open chain nononic acid constituent 3 9-dideoxy-D-threo-D-altro-nononic acid ether-linked via C-2 to C-6 of an additional D-glucose per repeating unit. Methylation analysis and 1D 2D NMR studies 1H and 13C performed on the native polysaccharide and mass spectrometric and NMR in which Sug is 6-O- 3 9 -dideoxy-D-threo-D-altro-nononic acid-2 -yl -a-D-glucopyranose. Keywords exopolysaccharide lactic acid bacteria nononic acid Streptococcus thermophilus structural analysis. Microbial exopolysaccharides EPSs are employed in the food industry as viscosifying stabilizing emulsifying and gelling agents 1 . The texturizing properties of EPSs in fermented dairy products 2 in combination with the GRAS generally recognized as safe status of EPS-produ-cing lactic acid bacteria make these EPSs of interest for the food industry. To understand the relationship between the structure of EPSs and their physical properties structural studies have been performed on EPSs produced by various species of the .
