3-hydroxytetradecanoic Acid Research Articles

The chemical composition of the lipopolyacarideof Pseudomonas aeruginosa.

1. Lipopolysaccharide was isolated from both cell walls and acetone-dried whole cells of Pseudomonas aeruginosa (N.C.T.C. 1999). 2. Closely similar products are obtained, although that from whole cells cannot be completely freed from small amounts (2-7%) of residual nucleic acids. 3. The lipid moiety (23-33%) has a similar amino sugar backbone to that of lipids of enterobacterial lipopolysaccharides, but contains different hydroxy acids (2- and 3-hydroxydodecanoic acid and 3-hydroxydecanoic acid). 3-Hydroxytetradecanoic acid is absent, and 3-hydroxydodecanoic acid is the main N-acylating acid. No clear evidence permitting a distinction between the possibilities that phosphodiester or glycosidic linkages exist between the glucosamine residues was obtained. 4. Identifiable sugars (glucose, rhamnose, 3-deoxy-2-octulonic acid and heptose) account for less than 20% of the lipopolysaccharide, and alanine, galactosamine and fucosamine are apparently components of the polysaccharide moiety. 5. The polysaccharide moiety is unusual in that it is not readily obtained from the lipopolysaccharide by treatment with dilute acetic acid, which does, however, solubilize much of the phosphorus of the lipopolysaccharide. 6. The ;polysaccharide' fraction (approx. 21%) obtained by treatment with dilute acetic acid contains only a small proportion of the total polysaccharide components, and in one case only 45% of the fraction was accountable for in terms of identifiable components. 7. Evidence suggests that unidentified nitrogenous components are concentrated in the residual material after removal of both the lipid and the ;polysaccharide' fraction from the lipopolysaccharide.

CONSTITUTION OF AN EXTRACELLULAR ACIDIC GLUCOMANNAN FROM SERRATIA MARCESCENS

An acidic glucomannan isolated from culture filtrate of Serratia marcescens contained D-glucose and D-mannose (3.5:1), D-glucuronic acid (5.5%), and "bound" fatty acids (7.4%). The polysaccharide, on examination by moving boundary electrophoresis and by sedimentation in the ultracentrifuge, was homogeneous. Degree of polymerization was estimated to be ca. 20 by vapor pressure osmometry. Isolation of nigerose (3-O-α-D-glucopyranosyl-D-glucopyranose) established the glycosidic linkage between the D-glucose units as α (1 → 3). Methylation and periodate oxidation data showed that the D-glucose and D-mannose units were joined by (1 → 3) linkages in a straight chain structure terminated at the non-reducing end by a unit of D-glucuronic acid which was attached to C3 of a D-mannose residue. The reducing end of the molecule was terminated by a D-glucose unit. The fatty acids, consisting mainly of hydroxymyristic acid and myristic acid, were attached to the molecule mainly by ester linkages.

Capsular polysaccharides of Serratia marcescens.

Four polysaccharides were isolated from the capsular layer of Serratia marcescens cells grown on a sucrose medium. In composition, electrophoretic behavior, and sedimentation in the ultracentrifuge, all were shown to be markedly different. Analytical data indicated that the polysaccharides were an acidic glucomannan (I), a rhamnoglucan (II), a glucoheptan (III), and a rhamnoheptoglucan (IV). In I, in addition to the main acidic component D-glucuronic acid, a small amount of guluronic acid was also identified. A relatively high protein or peptide content in the purified polysaccharides suggested that it was firmly bound to the carbohydrate structure; "bound" lipid consisting mainly of hydroxymyristic acid was also a part of the structure. Methylation studies established the main glycosidic linkages in I, II, and III. The capsular polysaccharides had properties similar to those of polysaccharides isolated from a culture filtrate of S. marcescens in an earlier study, and a possible relationship between these two groups of polysaccharides is discussed.