EFFECTS OF SALTS ON PRODUCTION AND ON O-ACETYLATION OF GLUCURONAN EXCRETED BY THE RHIZOBIUM-MELILOTI M5N1CS STRAIN

Acetylation determined by H-1-nuclear magnetic resonance spectroscopy and production of the glucuronan excreted by the Rhizobium meliloti M5 N1CS strain during cultivation in RCS medium with and without added ma gnesium salts have been studied. These salts induce an increase in the degree of substitution and the molar ratio of 2,3-di-O-acetyl residue s. A decrease in production is observed after 75 h of fermentation as the magnesium salt concentration increases. The presence of manganese and sodium salts in the culture induces inhibition of exopolysaccharid e (EPS) production. However, the structure of the EPS is similar to th at of the EPS produced by standard fermentation, without modification in the degree of substitution.