Studies on the Cell Walls of Pseudomonas Species Resistant to Ethylenediaminetetra-acetic Acid

Abstract

S U M M A R YCell walls were prepared from various species of the genus Pseudomonas which are resistant to ethylenediaminetetra-acetic acid (EDTA). The cell walls were analysed and comparisons made with the walls of EDTA-sensitive pseudomonads. The walls had none of the structural features which appeared to characterize EDTA-sensitive pseudomonads. Lipopolysaccharide was not extracted from the walls of resistant organisms by EDTA at pH 9-2. The wall of P . iodinum contained almost no lipid or protein but consisted mainly of glycosaminopeptide and material which resembled a teichoic acid. It is proposed that this organism be removed from the genus Pseudomonas. The walls of P. diminuta, P. maltophilia, P. pavonacea and P. rubescens had compositions broadly characteristic of Gram-negative bacteria. The four species are not obviously related. Glycolipids were present in the walls of P. diminuta, P. maltophilia and P. rubescens. An ornithine-containing lipid was isolated from P. rubescens and partly characterized. A small amount of this lipid was also present in P. maltophilia. The wall of P. maltophilia was distinctive in its wide range of monosaccharide components, including an unidentified neutral sugar of high mobility on paper chromatograms. INTRODUCTIONEthylenediaminetetra-acetic acid (EDTA) has a toxic effect on Pseudomonas aeruginosa (MacGregor & Elliker, 1958; Gray & Wilkinson, 1965a;Eagon & Carson, 1965;Wilkinson, 1967), apparently the result of a lytic action by it on the cell wall of the organism (Gray & Wilkinson, 1965a, b ;Eagon & Carson, 1965). A correlation has been found between bactericidal activity and chelate stability constants for polyaminocarboxylic acids related to EDTA, which indicated that chelation was involved in the toxic action of these compounds (Gray & Wilkinson, 19654. The structural importance of multivalent metal cations in the wall of P. aeruginosa has been confirmed (Eagon & Carson, 1965;Asbell & Eagon, 1966a, b). Treatmh of the bacteria with EDTA caused these cations to become soluble (Eagon & Carson, 1965) and also of the lipopolysaccharide component of the cell wall (Gray & Wilkinson, 1965 b). Although EDTA has been found to extract lipopolysaccharide from Escherichia coli, the bacteria remained viable under the conditions used (Leive, 1965). Except when used in conjunction with organic cations (Wolin, 1966;Goldschmidt & Wyss, 1967;Voss, 1967), EDTA does not seem to be highly toxic for Gram-negative bacteria other than pseudomonads (Gray & Wilkinson, 1965 a;Wilkinson, 1967). This hypersensitivity to EDTA might prove to be a useful characteristic in the taxonomy of the pseudomonads (Shively & Hartsell, 1964;Wilkinson, 1967 S . G. W I L K I N S O NIn a survey of various pseudomonads (Wilkinson, 1967), only strains of the following species were found to be resistant to EDTA: Pseudomonas diminuta, P. geniculata, P. iodinum, P. maltophilia, P. pavonacea, P. rubescens. The inclusion of these organisms in the genus Pseudomonas has been considered doubtful by other workers who used di...

Lipid Composition and Chemotaxonomy of Pseudomonas putrefaciens (Alteromonas putrefaciens)

“…Organisms that produce an ornithine amide lipid similar or identical to that in P. putrefaciens include Th io buc illus t hiooxidans, Rhodopseudomonas sp haeroides, Desulfo vib r io gigas and Gluconobacter cerinus. Strains of several 'true' pseudomonads produce an ornithine amide lipid and a hexuronosyldiacylglycerol when grown on nutrient agar (Wilkinson, 1970). Acyl phosphatidylglycerol is a minor lipid component in strains of Salmonella typhimurium, Esc.liericlzia coli, an Acinetobacter species and the marine bacterium Pseudomonas BAL-3 1 (Makula et al, 1978).…”

The Relationship between the O-antigenic Lipopolysaccharides and Serological Specificity in Strains of Pseudomonas aeruginosa of different O-serotypes

“…1972). Other species of pseudomonads have been reported to contain fucose and ribose in their lipopolysaccharides or walls (Wilkinson, 1968;1970).…”

“…Only two unusual amino sugars, quinovosamine (Suzuki, Suzuki & Fukasawa, 1970) and fucosamine (Suzuki, 1969, Fensom & Gray, 1969 have been reported to occur in isolated lipopolysaccharides of P. aeruginosa, although unidentified components (Fensom & Gray 1969;Fensom & Meadow, 1970) have been reported. Unusual amino sugars have been found in other species of Pseudomonas; these 316 I. R. CHESTER, P. M. MEADOW AND T. L. PITT include quinovosamine, fucosamine, ~-amino-~,6-dideoxyglucose and 3-amino-3,6-dideoxy-D-galactose (Wilkinson, 1970 ;1972 ;Wilkinson & Carby, I 971). Lipopolysaccharide isolated from a strain of Pseudomonas aeruginosa belonging to serogroup 6 has been found to contain valine ( S .…”

“…Walls were purified and treated with 45 yo aqueous phenol (Westphal & Jann, 1965). The resulting aqueous phases were centrifuged to remove contaminating peptidoglycan, dialysed and freeze-dried (Key, Gray & Wilkinson, 1970).…”

Evidence for the Presence of a New Class of Teichoic Acid in the Cell Wall of Bacterium NCTC 9742

“…The atypical resistance of ' P. iodinum ' NCTC 9742 led us to examine the composition of isolated cell walls (Wilkinson, 1968). In the virtual absence of lipid and protein, in the high content of peptidoglycan (43% in walls from one batch of cells grown on nutrient agar) and in peptidoglycan composition (components and their molar ratios were: glutamic acid, 1 ; alanine, 2; 2,6-diaminopimelic acid, 1 ; glucosamine, 1 ; muramic acid, l), the walls were similar to those of many other Gram-positive bacteria.…”