Structural determination of the O-chain polysaccharide from the lipopolysaccharide of the haloalkaliphilic Halomonas pantelleriensis bacterium

The structural determination of the O-chain repeating unit of the lipopolysaccharide from the haloalkaliphilic Halomonas pantelleriensis bacterium is described. The structure of the repeating unit was suggested on the basis of chemical analysis and NMR and NIS data. The 4-O-[(S)-1-carboxyethyl]-D-GlcA residue has been found for the first time in a lipopoly-saccharide, being previously only found in capsular polysaccharides. A comparison of the O-chain structures of Halo-monas magadiensis and H. pantelleriensis is also reported. The results show that both bacteria present lipopolysaccharides containing a high number of carboxylate groups whose salification might determine a protective buffer effect on bacterium against extreme life conditions. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006.