STRUCTURE OF STEWARTAN, THE CAPSULAR EXOPOLYSACCHARIDE FROM THE CORN PATHOGEN ERWINIA-STEWARTII

Stewartan, the acidic exopolysaccharide of Erwinia stewartii, was puri fied from agar grown cells. To facilitate its structural analysis, che mical and enzymatic depolymerizations were carried out using hydrofluo ric acid and E. amylovora phage phi-Ea1h, respectively. Structural cha racterization of the resulting oligosaccharides was performed by a com bination of mass spectrometric and one- and two-dimensional (1D/2D) NM R spectroscopic techniques. A branched repeating unit with seven monos accharide residues, all in their pyranose forms, was found: [GRAPHICS] (C) 1996 Elsevier Science Ltd.