Extracellular polysaccharide of Erwinia chrysanthemi A350 and ribotyping of Erwinia chrysanthemi spp.

Erwinia chrysanthemi spp, are Gram-negative bacterial phytopathogens causin g soft rots in a number of plants. The structure of the extracellular polys accharide (EPS) produced by the E. chrysanthemi strain A350, which is a lac Z(-) mutant of the wild type strain 3937, pathogenic to Saintpaulia, has be en determined using a combination of chemical and physical techniques inclu ding methylation analysis, low-pressure gel-filtration and anion-exchange c hromatography, high-pH anion-exchange chromatography, partial acid hydrolys is, mass spectrometry and 1- and 2D NMR spectroscopy. In contrast to the st ructures of the EPS reported for other strains of E. chrysanthemi, the EPS from strain A350 contains D-GalA, together with r-Rhap and D-Galp in a 1:4: 1 ratio. Evidence is presented for the following hexasaccharide repeat unit : [GRAPHICS] All the Erwinia chrysanthemi spp. studied to date have been analyzed by rib otyping and collated into families, which are consistent with the related s tructures of their EPS. (C) 2000 Elsevier Science Ltd. All rights reserved.