Structural studies of an extracellular polysaccharide, S-53, elaborated by a Klebsiella species

✍ Scribed by Per-Erik Jansson; Bengt Lindberg; Göran Widmalm

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 166 KB
• Volume: 182
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(88)84102-8

✦ Synopsis

During the search for bacteria of potential industrial application, a polysaccharide, S-53, was prepared from a soil bacterium, ATCC No. 31488, identified as a Klebsiella pneumoniae species'. The polysaccharide had a composition of l&19% of uranic acid, 4.8% of pyruvate, and 7% of 0-acetyl, the remainder being glucose and fucose in the ratio 51:49. It was noted that this composition is similar to that reported for the Klebsiefla type 1 capsular polysaccharide (Kl) which, however, does not contain 0-acetyl groups2. We now report structural studies of S-53. The 13C-and rH-n.m.r. spectra of S-53 were complex, but the latter contained, infer alia, signals for methyl groups of fucosyl residues at 6 1.26 (1 H), of pyruvic acid acetals at 6 1.58 (0.9 H), and of 0-acetyl groups at 6 2.12 and 2.17 ( -3:1, 1 H). The complexity of the spectra may be due to the non-stoichiometric amount of pyruvic acid and the fact that the 0-acetyl groups occupy different positions.

The spectra of 0-deacetylated S-53 were much simpler and the major peaks were superimposable on those of Kl. The pyruvic acid acetals in the 0-deacetylated S-53 were hydrolysed under mild conditions, typical for such acetals when tinked to vicinal trans-positions, as in K12. The polysaccharide thus prepared gave 18 well resolved signals in the I%-n.m.r.

spectrum. S-53 and Kl are therefore both composed of the trisaccharide repeating-unit 12, the only difference being that the former contains 0acetyl groups. The results of methylation analysis and specific degradations of S-53 confirmed this conclusion. These experiments were similar to those performed' in the investigation of Kl, and will not be reported in detail here.