Studies on a Viscous, Gel-Forming Exopolysaccharide from Sphingomonas paucimobilis GS1

A new strain, Sphingomonas paucimobilis GS1, accumulated 6.5 g of a highly viscous exopolysaccharide per liter, using sucrose as a substrate. The anionic heteropolysaccharide contained the following, in grams per gram: glucose, 0.7; galacturonic acid, 0.11; glucuronic acid, 0.07; and acetate, 0.12. The viscosity of the exopolysaccharide (4.0 g/liter; 4,200 cP) was 5.5 times that of xanthan gum and was stable over a wide pH and temperature range as well as in the presence of NaCl. Deacetylated polymer produced a clear, agarlike, thermoreversible gel in the presence of cations. The gel strength of the modified polymer was four times that of agar and could withstand autoclaving.