Physicochemical characterization of an acetan variant secreted by Acetobacter xylinum strain CR1/4

• Published in: International journal of biological macromolecules Vol. 16; no. 6; pp. 324 - 330
• Main Authors: Ridout, M.J., Brownsey, G.J., Morris, V.J., Cairns, P.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.1994
• Subjects: Acetobacter xylinum; Calorimetry, Differential Scanning; Carbohydrate Conformation; Carbohydrate Sequence; Chemical Phenomena; Chemistry, Physical; CR1/4; Drug Synergism; Galactans; Gluconacetobacter xylinus - chemistry; Gluconacetobacter xylinus - genetics; Gluconacetobacter xylinus - physiology; Light; Mannans; Molecular Sequence Data; Plant Gums; Polysaccharides; Polysaccharides, Bacterial - chemistry; Polysaccharides, Bacterial - physiology; Scattering, Radiation; Solutions; Viscosity; Water; X-Ray Diffraction; polysaccharides; CR1/4; Acetobacter xylinum
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/0141-8130(94)90064-7

Chemical mutagenesis has been used to produce mutants of Acetobacter xylinum NRRL B42 that are cellulose-negative and that produce variants of the acetan structure deficient in the side-chain sugar residues. The product of A. xylinum strain CR1/4 has been shown to possess a tetrasaccharide repeat unit with the side chain terminating in glucuronic acid. X-ray diffraction studies of oriented fibres suggest that the polysaccharide CR1/4 forms a fivefold helix with a pitch of 4.8 nm. Light-scattering studies on CR1/4 solutions suggest a molecular weight of 1.2 × 10 6 with radii of gyration values of 86 nm (aqueous solution) and 67 nm (0.1 m NaCl solution). The magnitude of the measured radii of gyration and the shape of the Holtzer plots suggest that CR1/4 can be described as a stiff coil. Preliminary differential scanning calorimetry data show melting behaviour consistent with order-disorder transitions of a charged helical structure. Rheological studies have revealed new synergistic interactions of CR1/4 with locus bean gum. Comparative studies of acetan and CR1/4 show that decreasing the length of the side chain enhances the solution viscosity.