THE IN-VITRO BIOSYNTHESIS OF THE EXOPOLYSACCHARIDE PRODUCED BY RHIZOBIUM-LEGUMINOSARUM BV TRIFOLII, STRAIN-NA-30

Rhizobium leguminosarum by. trifolii, strain NA 30 nodulates both red (Trifolium pratense) and white (ir: repens) clover and produces an aci dic exopolysaccharide (EPS) containing glucose, galactose, glucuronic acid, acetate and ketalpyruvate residues in a 5:1:2:1:2 molar ratio. T he in vitro synthesis of this EPS as well as the characterization of f ive structurally related lipid linked oligosaccharides is described em ploying EDTA treated cells as enzyme preparation and C-14-labelled UDP -Glc, UDP-GlcA, Acetyl CoA and phosphoenol pyruvate (PEP) and doubly l abelled P-32 UDP-C-14-Glc as precursors. The lipidic derivatives, extr acted with chloroform, methanol, water (1:2:0,3) had the properties ex pected for prenyl-diphospho-sugars, as judged by the pattern of labell ing, DEAE cellulose column chromatography, catalytic reduction and aci d lability, etc. The sugar moieties of these phosphoprenyl derivatives were identified as the acetylated octasaccharide repeating unit, its mono- and di-ketalpyruvate derivatives and two trisaccharides, one of them acetylated, on the basis of specific labelling, gel filtration, p aper electrophoresis and chromatography, TLC, permethylation, etc. In vitro polymer synthesis was greatly increased when electroporated cell s were substituted for EDTA treated cells as enzyme system.