This paper reports isolation, structural characterization and some physico-chemical properties in aqueous solution of the exopolysaccharide (EPS) produced by Streptococcus thermophilus strain SFi20. The yield of the purified EPS was found to be reproducible and close to the average value of 143 mg/l. The chemical structure, previously suggested, has been confirmed on the basis of NMR data. Viscometric, chiro-optical and rheological measurements have been carried out with the aim of characterizing the conformational state of the polysaccharide in aqueous solution. All the data reported indicate that the EPS does not undergo a cooperative conformational transition under the investigated experimental conditions. Furthermore, the viscosity data and the viscoelastic behaviour suggest that the polymer is rather flexible and adopts a random coil conformation in aqueous solution

characterization, Streptococcus thermophilus, exopolysaccharide, isolation

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,2	Ac	174.500	22.381
3,3	aDGalpN	94.735	48.617	77.618	65.426	71.131	61.349
3	bDGalp	103.767	70.108	77.618	68.823	75.532	61.311
6	aDGalp	98.558	68.679	69.958	69.579	70.917	61.205
	bDGlcp	103.395	72.915	85.070	68.615	74.350	66.640


1H NMR data:
missing...

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@H]1[C@@H](O)[C@@H](CO)O[C@H](O[C@H]2[C@@H](O)[C@@H](CO)O[C@@H](O[C@@H]3[C@@H](O)[C@H]([*])O[C@H](CO[C@H]4O[C@H](CO)[C@H](O)[C@H](O)[C@H]4O)[C@H]3O)[C@@H]2O)[C@@H]1NC(C)=O

689.617 g/mol (C₂₆H₄₃R₂NO₂₀, R = next and previous repeats, not counted in mol weight)