Methylobacterium sp. isolated from a Finnish paper machine produces highly pyruvated galactan exopolysaccharide.

R.P. Verhoef, P. de Waard, H.A. Schols, M. Siika-aho, A.G.J. Voragen

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45 Citations (Scopus)


The slime-forming bacterium Methylobacterium sp. was isolated from a Finnish paper machine and its exopolysaccharide (EPS) was produced on laboratory scale. Sugar compositional analysis revealed a 100% galactan (EPS). However, FT-IR showed a very strong peak at 1611 cm-1 showing the presence of pyruvate. Analysis of the pyruvate content revealed that, based on the sugar composition, the EPS consists of a trisaccharide repeating unit consisting of -galactopyranose and [4,6-O-(1-carboxyethylidene)]- -galactopyranose with a molar ratio of 1:2, respectively. Both linkage analysis and 2D homo- and heteronuclear 1H and 13C NMR spectroscopy revealed the following repeating unit: ¿3)-[4,6-O-(1-carboxyethylidene)]-a- -Galp-(1¿3)[4,6-O-(1-carboxyethylidene)]-a- -Galp-(1¿3)-a- -Galp-(1¿. By enrichment cultures from various ground and compost heap samples a polysaccharide-degrading culture was obtained that produced an endo acting enzyme able to degrade the EPS described. The enzyme hydrolysed the EPS to a large extent, releasing oligomers that mainly consisted out of two repeating units.
Original languageEnglish
Pages (from-to)1851-1859
JournalCarbohydrate Research : an international journal
Issue number18
Publication statusPublished - 2003


  • polysaccharides
  • bacteria
  • acid
  • chromatography
  • configuration
  • slimes
  • strain


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