Structural elucidation of a novel exopolysaccharide produced by a mucoid clinical isolate of Burkholderia cepacia

Abstract

The structure of the exopolysaccharide (EPS) produced by a clinical isolate of Burkholderia cepacia isolated from a patient with fibrocystic lung disease has been investigated. By means of methylation analyses, carboxyl reduction, partial depolymerization by fuming HCl and chemical degradations such as Smith degradation, lithium‐ethylenediamine degradation and β‐elimination, supported by GC/MS and NMR spectroscopic analyses, the repeat unit of the EPS has been identified and was shown to correspond to the acidic branched heptasaccharide with the following structure: This partially acetylated acidic polymer, distinguished by the presence of the less usual d‐isomer of rhamnose and of a trisubstituted glucuronic acid residue, could represent the main EPS produced by this bacterial species.