EXTRACELLULAR POLYSACCHARIDE OF ERWINIA-CHRYSANTHEMI ECH6

Many strains of Erwinia chrysanthemi, which are Gram-negative bacteria l phytopathogens, produce copious amounts of extracellular polysacchar ides. The extracellular polysaccharide from E. chrysanthemi pv. zeae s train SR 260, a phytopathogen of corn, is a branched-chain glucomannor hamnan of proven structure (Gray et al, Carbohydr. Res. 1993, 245, 271 -287). The extracellular polysaccharide from E. chrysanthemi Ech6 is d ifferent, containing no rhamnose or mannose. It is composed of L-fucos e, D-galactose, D-glucose and D-glucuronic acid in the ratio 2:2:1:1. The structure of the polysaccharide is as follows: --> 4)-alpha-L-Fucp -(1 --> 3)-beta-D-Glcp-(1 --> 4)-alpha-L-Fucp-(1 --> 3 up arrow 1 alph a-D-Galp-(1 --> 4)-alpha-D-GlcpA-(1 --> 3)-alpha\-D-Gal 6 4 \\ C \\ HO OC CH3.