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

Rene Verhoef, Pieter de Waard, Henk A. Schols, Matti Siika-aho, Alphons G.J. Voragen (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

25 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 d-galactopyranose and [4,6-O-(1-carboxyethylidene)]-d-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)]-α-d-Galp-(1→3)[4,6-O-(1-carboxyethylidene)]-α-d-Galp-(1→3)-α-d-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
Number of pages9
JournalCarbohydrate Research
Issue number18
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed


  • Methylobacterium sp.
  • EPS
  • Pulp and paper industry
  • Pink slime
  • Enzymes
  • Galactan
  • Pyruvate
  • NMR

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