Production of a glucoglucuronan by a rhizobia strain infecting alfalfa. Structure of the repeating unit

Abstract

The Rhizobium sp. T1 strain, which induces nodule formation on alfalfa and clover roots, produces, during growth, an extracellular polysaccharide composed of d-glucose and d-glucuronic acid noted glucoglucuronan. During the bacterial growth, the pH of the medium decreases slightly. The control of pH in the growth medium slightly reduces the glucoglucuronan production. Under the conditions tested in the present work, the weight-average molecular weight of the polymers produced with or without pH control are similar: Mw ≈2×10 6; the repeating unit determined by chemical and NMR analyses corresponds to the disaccharide: →3)-β- d-Glc pA-(1→4)-β- d-Glc p-(1→.