title: Exopolysaccharides from Rhizobium meliloti YE-2 grown under different osmolarity conditions: viscoelastic properties.
abstract: The exopolysaccharides fro Rhizobium meliloti YE-2 extracted 10 days after the inoculum from culture broths and having different osmolarity values (0, 0.2, 0.4, and 0.6 M) have been investigated by means of oscillatory and steady-shear measurements on 1% solutions in 0.1M NaCl. The micro-organism produces a mixture of a galactoglucan and a succinoglycan. At low osmolarity (0 and 0.2M), the main fraction consists of galactoglucan and the viscoelastic properties of the mixture are typical of an entanglement system. At 0.4 and 0.6M, the proportion of the succinoglycan increases and the viscoelastic properties change abruptly to those typical of a "weak gel" system. Different conformations are adopted by the two exopolysaccharides in solution.
authors.affiliation: International Centre for Pure and Applied Chemistry, Area di Ricerca, Trieste, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Navarini
authors.forename: A
authors.initials: A
authors.lastname: Cesàro
authors.forename: S B
authors.initials: SB
authors.lastname: Ross-Murphy
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D004548:Elasticity; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification; D016962:Sinorhizobium meliloti / Q000254:growth & development*; D014783:Viscosity
chemical_list: D011135:Polysaccharides, Bacterial