The exopolysaccharide of Lactobacillus delbrückii subsp. bulgaricus rr, isolated from skimmed milk, is a heteropolymer of D-galactopyranosyl, D-glucopyranosyl, and L-rhamnopyranosyl residues in the molar ratio 5:1:1. The structure was established by linkage analysis and 1D and 2D NMR spectroscopy of the native polysaccharide, in combination with characterisation of oligosaccharide fragments, obtained by Smith degradation and partial acid hydrolysis, using methylation analysis, EIMS, and 1D and 2D 1H NMR spectroscopy. The polysaccharide has a branched heptasaccharide repeating unit with the following structure: -->2)-[beta-D-Galp-(1-->3)]-alpha-D-Galp-(1-->3)- beta-D-Glcp-(1-->3)-[beta-D-Galp-(1-->4)]-beta-D-Galp-(1-->4)-[alpha-L- Rhap-(1-->3)]-alpha-D-Galp-(1-->.

The structure of the exopolysaccharide of Lactococcus lactis subsp. cremoris

Coccoliths of Emiliania huxleyi (Lohmann) Hay and Mohler, a unicellular calcifying alga, consist of calcite closely associated with an acidic, Ca2+‐binding polysaccharide. This polysaccharide is thought to play a regulatory role in coccolith synthesis by interfering with CaCO3 crystallization. Here we show that the polysaccharides from three different strains, A 92, L and 92 D, all inhibit the precipitation of CaCO3 in vitro to the same extent. The monosaccharide compositions of the A 92 and L polysaccharide are similar. The 92 D material, however, deviates from the other two: it contains significantly lower amounts of methylated sugars and ribose, and elevated levels of rhamnose and galactose. It also contains antigenic determinants not detected in the A 92 and L polysaccharides. In contrast to the latter two macromolecules the 92 D polysaccharide migrates as two bands upon polyacrylamide gel electrophoresis, possibly resulting from complexing with small amounts of protein. The coccolith polysaccharide from L cells, cultured at an elevated growth rate, also migrates as two bands. This phenomenon is due to an increase in molecular size distribution. The results suggest that certain properties of the molecule may be subject to variation without interfering with its function.

Coccoliths of Emiliania huxleyi (Lohmann) Hay and Mohler, a unicellular calcifying alga, consist of calcite closely associated with an acidic, Ca2+‐binding polysaccharide. This polysaccharide is thought to play a regulatory role in coccolith synthesis by interfering with CaCO3 crystallization. Here we show that the polysaccharides from three different strains, A 92, L and 92 D, all inhibit the precipitation of CaCO3 in vitro to the same extent. The monosaccharide compositions of the A 92 and L polysaccharide are similar. The 92 D material, however, deviates from the other two: it contains significantly lower amounts of methylated sugars and ribose, and elevated levels of rhamnose and galactose. It also contains antigenic determinants not detected in the A 92 and L polysaccharides. In contrast to the latter two macromolecules the 92 D polysaccharide migrates as two bands upon polyacrylamide gel electrophoresis, possibly resulting from complexing with small amounts of protein. The coccolith polysaccharide from L cells, cultured at an elevated growth rate, also migrates as two bands. This phenomenon is due to an increase in molecular size distribution. The results suggest that certain properties of the molecule may be subject to variation without interfering with its function.

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