Extracellular polysaccharide of Erwinia chrysanthemi Ech6.

Many strains of Erwinia chrysanthemi, which are Gram-negative bacterial phytopathogens, produce copious amounts of extracellular polysaccharides. The extracellular polysaccharide from E. chrysanthemi pv. zeae strain SR 260, a phytopathogen of corn, is a branched-chain glucomannorhamnan of proven structure (Gray et al., Carbohydr. Res. 1993, 245, 271-287). The extracellular polysaccharide from E. chrysanthemi Ech6 is different, containing no rhamnose or mannose. It is composed of L-fucose, D-galactose, D-glucose and D-glucuronic acid in the ratio 2:2:1:1. The structure of the polysaccharide is as follows: [sequence: see text]