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Structural studies have been carried out on the 0-specific polysaccharide, the core oligosaccharide, and the lipid A from the lipopolysaccharide of Pseudomonas maltophilia NCTC 10257. By means of 13C nuclear magnetic resonance spectroscopy, a tetrasaccharide repeating-unit for the 0-specific polymer has been confirmed. However, the data suggest that the L-rhamnopyranosyl residue at the branching point has the c1 configuration rather than as proposed previously [Neal, D. J. and Wilkinson, S. G. (1979) Carhohydr. Res. 69, 191 -2011. The core oligosaccharide contains residues of D-glucose, D-mannose phosphate, D-galactosamine (not N-acetylated), D-galacturonic acid, and a 3-deoxyoctulosonic acid (but no aldoheptose). A partial structure for the oligosaccharide is proposed. Lipid A is based on phosphorylated glucosamine residues, with N-fatty acyl and 0-fatty acyl substituents. The major fatty acids are 9-methyldecanoic acid, 2-hydroxy-9-methyldecanoic acid, 3-hydroxy-9-methyldecanoic acid (each ester-linked), 3-hydroxydodecanoic acid, and 3-hydroxy-I I-methyldodecanoic acid (both mainly amide-linked). The results of this study provide further evidence for a relationship Although a detailed description of Pseudomonas maltophilia was published only in 1961 [l], the organism has attracted increasingly numerous and diverse investigations. Phenotypic characterisation [l -51 has shown that the spccies is rather remote from other pseudomonads, and a relationship with Xanthomonas species has been suggested by the determination of ribosomal RNA homologies [6] and by the immunological comparison of glutamine synthetases [7]. In addition to its taxonomic interest [8], P. maltophilia also commands attention from clinical microbiologists [9] because of its activity as an opportunist pathogen. Other properties which have recently been discovered include the binding of human gonadotropin [lo], the production of an extracellular ribonuclease [l I], the possession of alginolytic activity [I 21, and accumulation in the rhizosphere of cruciferous plants [I 31. Our own involvement with P. maltophilia stems from the observation [14] that the organism does not exhibit the sensitivity to EDTA that characterises Pseudomonas aeruginosa, the type species of the genus Pseudomonas.In previous studies [15, 161 of the type strain of P. maltophilia (NCTC 10257) we have carried out general analyses of the cell envelope and determined the composition of its lipopolysaccharide component. A structure for the repeatingunit of the presumptive 0-specific side-chain of the lipopolysaccharide has also been proposed. In the present paper we describe the 13C nuclear magnetic resonance spectrum of the presumptive side-chain, and the results of structural studies of the core and lipid-A regions of the lipopolysaccharide. between P. maltophilia and some Xanthomonas species. MATERIALS AND METHODS Isolation and Fractionation of LipopolysaccharideMethods used for the batch culture of Pseudomonus maltophilia NCTC 10257, the preparation of cell envelopes, the ext...

3-O-Methyl-L-xylose was isolated from whole cells of Pseudomonas maltophilia N.C.T.C. 10257. The sugar is a component of lipopolysaccharide from which a polysaccharide also containing L-rhamnose and L-xylose was released by mild acid hydrolysis. 3-O-Methyl-L-xylose was absent from five other strains of Ps. maltophilia and one strain of Pseudomonas geniculata.