STRUCTURE AND PHYSICAL-PROPERTIES OF THE EXTRACELLULAR POLYSACCHARIDEPS-P4 PRODUCED BY SPHINGOMONAS-PAUCIMOBILIS P4 (DSM 6418)

A new strain, Sphingomonas paucimobilis P4 (DSM 6418), was found durin g a screening programme for exopolysaccharide-producing bacteria. The highly viscous fermentation broth yields a polysaccharide (up to 10 kg /m(3)), named PS-P4, and shows thixotropic flow behaviour. In the pres ence of phosphate ions, PS-P4 forms aqueous gels after heating and coo ling at alkaline pH. After isolation and purification of the exopolysa ccharide, structural analysis by 1D and 2D H-1 NMR spectroscopy and ma ss spectrometry was performed. The deacylated exopolysaccharide has th e following repeating trisaccharide structure: -->4)-beta-D-Glcp-(1 -- > 4)-alpha-L-Rhap-(1 --> 3)-beta-D-Glcp(1 -->. Additionally, the prese nce of ester-bound acetic acid, D-glyceric acid, and (R)3-hydroxybutyr ic acid in the native polysaccharide was demonstrated.