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Solution properties of viilian, the exopolysaccharide from Lactococcus lactis subsp. cremoris SBT 0495
Author(s) -
Higashimura M.,
MulderBosman B. W.,
Reich R.,
Iwasaki T.,
Robijn G. W.
Publication year - 2000
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(200008)54:2<143::aid-bip7>3.0.co;2-q
Subject(s) - chemistry , molar mass , radius of gyration , intrinsic viscosity , persistence length , viscometer , ionic strength , viscosity , multiangle light scattering , polyelectrolyte , random coil , analytical chemistry (journal) , polymer , size exclusion chromatography , hydrodynamic radius , chromatography , gyration , aqueous solution , light scattering , thermodynamics , scattering , crystallography , organic chemistry , circular dichroism , physics , enzyme , optics , copolymer , geometry , mathematics
The exopolysaccharide (EPS) “viilian” was isolated from a large‐batch fermentation of Lactococcus lactis subsp. cremoris SBT 0495. After applying a newly developed purification procedure, pure viilian with a weight‐averaged molar mass of 2.64 × 10 3 kg/mol was obtained in a yield of 0.6 g/L culture broth. The native EPS, as well as lower molar mass fractions obtained by sonication of the native polymer, were studied by capillary viscometry and size‐exclusion chromatography (SEC) coupled to multiangle laser light scattering detection (MALLS). From the viscosity data at various ionic strengths, we extracted a Mark–Houwink–Kuhn–Sakurada exponent a = 0.79, and a Smidsrød B value of 0.03. By application of the Hearst, Bohdanecký, and Odijk models for stiff polymer coils, in connection to the experimental viscosity data, we established the characteristic ratio to be C ∞ = 44 and the intrinsic persistence length q 0 = 11.5 nm. The rms radii of gyration predicted from each of the models were in good agreement with the experimental radii (e.g., 〈 S 2 〉 1/2 w= 162 nm for native viilian in 0.2 M NaNO 3 ), as determined by SEC‐MALLS. In addition, the Odijk model predicts correct ionic strength‐linear charge density dependence of the rms radius of gyration. From the combined viscosity and SEC‐MALLS experiments we concluded that, in dilute aqueous solutions, viilian behaves as an intermediately stiff, random coil polyelectrolyte system.© 2000 John Wiley & Sons, Inc. Biopoly 54: 143–158, 2000