EXOPOLYSACCHARIDE PRODUCTION BY THE RHIZOBIUM-MELILOTI M5N1 CS STRAIN- LOCATION AND QUANTITATION OF THE SITES OF O-ACETYLATION

The mutant strain M5N1 CS of Rhizobium meliloti is able to produce, in a Rhizobium complete medium supplemented with fructose or sucrose (1% w/v), a partially acetylated homopolymer of glucuronic acid. During b atch cultivation, the polysaccharide production is observed while the pH of the medium decreases slightly. The nature of the carbon source a nd the control of pH have no effect on the degree of acetylation of th e polymer produced in the flasks. About 40% of glucuronic residues of the polymer are monoacelylated at C-3 or at C-2, C-3 substitution is a bout twice that of C-2 and remains constant during the fermentation.