Fibre-diffraction studies of the extracellular polysaccharide from Pseudomonas elodea

X-ray fibre diffraction techniques have been used to probe the structure of the microbial polysaccharide from Pseudomonas clodca (gellan gum). The polymer adopts a threefold helical structure with an axial repeat of 0.94 nm. The polymer form weak elastic thermoreversible gels and on deacetylation forms rigid brittle gels. Deacetylation has been shown to enhance crystallinity. Equatorial reflections index onto a trigonal unit cell (a=b=1.64 nm.