Structural characterization and rheological properties of an extracellular glucuronan produced by a Rhizobium meliloti M5N1 mutant strain.

The mutant strain M5N1 C.S. (NCIMB 40472) of Rhizobium meliloti M5N1 is able to produce during fermentation a partially acetylated extracellular (1-->4)-beta-D-glucuronan. At low concentration (1 g.l-1), in the presence of monovalent cations, this new glucuronate behaves as a thickening agent, whereas at higher concentration a thermoreversible gel is obtained. With such divalent cations as Ca2+, a thermally stable gel can be formed.