Structural Studies on an Extracellular Polysaccharide Produced by a Bacterium Klebsiella sp. Isolated from River Water

Klebsiella sp. isolated from the water of the Sumida River produced an extracellular polysaccharide named BS-1. A preliminary study on the structure of BS-1 was performed. Methylation analyses suggested that the polysaccharide was a (1,3)-galactan having a (1,2)-linked glucuronic acid and a (1,4)-linked galactose as side chains. Identification of the methylated sugars was confirmed by GC mass spectrometry. The presence of these two branched sugar residues was also confirmed by periodate oxidation and subsequent Smith degradation. super(1)H and super(13)C NMR spectroscopy not only supported these structural features but also indicated that two of the component sugar residues were alpha -linked and the three other residues were beta -linked. These results indicate that BS-1 is a new type of (1,3)-linked galactan.