Isolation and characterization of an extracellular glucan produced by Leuconostoc garlicum PR

White and highly viscous extracellular polysaccharide composed of d-glucose residues has been isolated from culture medium of Leuconostoc garlicum PR by acetone precipitation followed by dialysis and freeze-drying. The crude biopolymer was recovered in the yield of 50 g/L of rich culture medium and showed an apparent molecular mass over 2 × 107. Chemical and spectroscopic studies revealed almost linear character of the bacterial biopolymer composed of α-1,6-linked d-glucopyranosyl backbone carrying a low content of branched points at C-2, C-3 and C-4. Moreover, a low content (∼2%) of α-1,4-linked d-glucopyranosyl residues has been determined in the extracellular biopolymer.