Cell Walls, Lipids, and Lipopolysaccharides of Pseudomonas Species

Abstract

Cell walls from two EDTA-sensitive and three EDTA-resistant pseudomonads grown in nutrient broth have been analysed. Each wall had a composition broadly characteristic of gramnegative bacteria, although the walls of Pseudomonas pavonacea and P. syncyanea were relatively rich in glycosaminopeptide and loosely-bound lipid, respectively. Phosphatidylglycerol was the only phospholipid common to all species, although phosphatidylethanolamine was absent only from P. diminuta. The latter species contained the distinctive range of glycolipids and a phosphoglucolipid identified previously in cells grown on nutrient agar. However, the glycolipids and an ornithine-containing lipid present in some other species (notably P. rubescens) when grown on nutrient agar were not detected. Except in P. rubescens, the major fatty acids in loosely-bound lipids were CIS, C16:l. and c18:1 acids: in P. rubescens, the major components were CIS, iso-Cl5, and C17:1 acids. Cyclopropane acids occurred in the lipids from P. stutzeri.Components of the lipopolysaccharides were identified and determined. The lipid A fractions contained fatty acids, phosphorus, and (except for P. diminuta) glucosamine. The fatty acids included both hydroxy and non-hydroxy acids. Apart from 2-hydroxydodecanoic acid (present in P. syncyanea), all the hydroxy acids were b-hydroxy acids, and 3-hydroxydodecanoic acid predominated in all species except P. rubescens. Odd-numbered hydroxy acids were minor components in P. diminuta and P. pavonacea and major components (CIS acids) in P. rubescens.The non-hydroxy acids consisted of saturated acids (C12 to C14) and orb-unsaturated acids (dehydration products from the b-hydroxy acids).Unusual features of the polysaccharide fractions from the lipopolysaccharides included the occurrence of non-phosphorylated heptose residues (P. diminuta), the presence of phosphorylated glucose residues and of aspartic acid ( P . pavonacea), the probable absence of 2-keto-3-deoxyoctonic acid and the presence of acid-labile galactose residues (P. rubescens), the virtual absence of glucose ( P . stutzeri), and the presence of alanine ( P . syncyanea). Amino sugars (glucosamine, galactosamine, and quinovosamine) occurred in the polysaccharides from P. stutzeri and P. syncyanea only. Following chromatography of the partly degraded polysaccharides on Sephadex, the distribution of components between possible side chain and core regions of the polysaccharides could be determined. The possible sigdcance of the results for the sensitivity of the organisms to EDTA and for their taxonomy is discussed.Although the cell walls and lipopolysaccharides of gram-negative bacteria have been studied extensively (see [1,2] for recent reviews), relatively little work has been done with pseudomonads other than Pseudomonas aeruginosa. Partly because of its outstanding resistance to many antibacterial agents, this organism has become a pathogen of some importance. It is perhaps surprising, therefore, that the

Cell Envelope Components of Strains Belonging to the Genus Thermus

“…The carbohydrate of whole LPS (9.7 to 27.7 Yo, w/w) was within the range for Pseudomonas species (9.6 to 42.5 yo, w/w; Wilkinson, Galbraith & Lightfoot, 1973). Reducing sugars were present at 2.0 to 3.2% (w/w).…”

“…The absence of glucosamine and phosphorus is an unusual, but not unknown, feature of the LPS lipid moiety. Rhodopseudomonas viridis and R. palustris lipids contain 2,3-diamino-2,3-dideoxyhexose instead of glucosamine and that of the former organism is phosphate-free (Weckesser et a/., 1974), while glucosamine was not detected in the LPS lipid moiety of Pseudomonas diminuta (Wilkinson et a/., 1973) or Thermoplasma acidophilum (Mayberry-Carson et al, 1974). However, polar material may not be extracted into the chloroform layer, but remain part of the insoluble interface between the two phases.…”

“…During acetic acid hydrolysis of strain B LPS, a precipitate formed and hydrolysis was stopped after 1.5 h (Wilkinson et al, 1973), but little lipid was extracted. When the aqueous phase was hydrolysed again under the same conditions, the lipid yield doubled, but further hydrolysis gave no more lipid.…”

“…LPS (50 mg) was cleaved into lipid and polysaccharide (PS) moieties by hydrolysis in 1 % acetic acid (5 ml) at 100 "C for 3 h. Chloroform-soluble and water-soluble products were separated as described by Wilkinson, Galbraith & Lightfoot (1973). Qualitative analysis of PS.…”

Studies of Lipopolysaccharides from Pseudomonas aeruginosa

“…Lipids were extracted from freeze-dried cell walls [21] and the yields and phosphorus contents were determined. Phospholipids were studied briefly by thin-layer chromatography on silica gel G (Merck) with chloroform -methanol -water (65 : 25 : 4, by vol.…”