Physicochemical properties of ‘Exogel’ exocellular β(1–4)- d-glucuronan from Rhizobium meliloti strain M5N1 C.S. (NCIMB 40472)

Abstract

The Rhizobium meliloti mutant strain M5N1 C.S. (NCIMB 40472) produces a polyuronic acid as β(1 → 4)- d-glucuronan with molecular weight between 1·5 × 10 5 and 3 × 10 5. With a p K o of about 3 and L p ⋍ 110 A ̊ , this polyelectrolyte is comparable with alginates and pectins. In solution, acetyl content and high external salt concentrations favour aggregation. At high concentrations the polysaccharide forms thermoreversible or thermally stable gels according to the nature of the counterion, the polymer concentration and the ionic strength.