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The chemical composition of the lipopolyacarideof Pseudomonas aeruginosa.

ABSTRACT: 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.

SUBMITTER: Fensom AH

PROVIDER: S-EPMC1184843 | biostudies-other | 1969 Sep

REPOSITORIES: biostudies-other

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Project description:Epidemic strains of Pseudomonas aeruginosa are highly virulent opportunistic pathogens with increased transmissibility and enhanced antimicrobial resistance. Understanding the cellular mechanisms behind this heightened virulence and resistance is critical. Peptidoglycan (PG) is an integral component of P. aeruginosa cells that is essential to its survival and a target for antimicrobials. Here, we examined the global PG composition of two P. aeruginosa epidemic strains, LESB58 and LESlike1, and compared them to the common laboratory strains PAO1 and PA14. We also examined changes in PG composition when the strains were cultured under nutrient conditions that resembled cystic fibrosis lung infections. We identified 448 unique muropeptides and provide the first evidence for stem peptides modified with O-methylation, meso-diaminopimelic acid (mDAP) deamination, and novel substitutions of mDAP residues within P. aeruginosa PG. Our results also present the first evidence for both d,l- and l,d-endopeptidase activity on the PG sacculus of a Gram-negative organism. The PG composition of the epidemic strains varied significantly when grown under conditions resembling cystic fibrosis (CF) lung infections, showing increases in O-methylated stem peptides and decreases in l,d-endopeptidase activity as well as an increased abundance of de-N-acetylated sugars and l,d-transpeptidase activity, which are related to bacterial virulence and antibiotic resistance, respectively. We also identified strain-specific changes where LESlike1 increased the addition of unique amino acids to the terminus of the stem peptide and LESB58 increased amidase activity. Overall, this study demonstrates that P. aeruginosa PG composition is primarily influenced by nutrient conditions that mimic the CF lung; however, inherent strain-to-strain differences also exist. IMPORTANCE Using peptidoglycomics to examine the global composition of the peptidoglycan (PG) allows insights into the enzymatic activity that functions on this important biopolymer. Changes within the PG structure have implications for numerous physiological processes, including virulence and antimicrobial resistance. The identification of highly unique PG modifications illustrates the complexity of this biopolymer in Pseudomonas aeruginosa. Analyzing the PG composition of clinical P. aeruginosa epidemic strains provides insights into the increased virulence and antimicrobial resistance of these difficult-to-eradicate infections.

Project description:Opportunistic pathogens can linger on surfaces in hospital and building plumbing environments, leading to infections in at-risk populations. Furthermore, biofilm-associated bacteria are protected from removal and inactivation protocols such as disinfection. Bacteriophages show promise as tools to treat antibiotic-resistant infections. As such, phages may also be useful in environmental applications to prevent newly acquired infections. In the current study, the potential of synergies between bacteriophage and chemical disinfection against the opportunistic pathogen Pseudomonas aeruginosa was assessed under various conditions. Specifically, surface-associated P. aeruginosa was treated with various concentrations of phages (P1 or JG004), chemical disinfectants (sodium hypochlorite or benzalkonium chloride), or combined sequential treatments under three distinct attachment models (spot inoculations, dry biofilms, and wet biofilms). Phages were very effective at removing bacteria in spot inoculations (>3.2 log10 removal) and wet biofilms (up to 2.6 log10 removal), while phages prevented the regrowth of dry biofilms in the application time. In addition, phage treatment followed by chemical disinfection inactivated P. aeruginosa cells under wet biofilm conditions better than either treatment alone. This effect was hindered when chemical disinfection was applied first, followed by phage treatment, suggesting that the additive benefits of combination treatments are lost when phage is applied last. Furthermore, we confirm previous evidence of greater phage tolerance to benzalkonium chloride than to sodium hypochlorite, informing choices for combination phage-disinfectant approaches. Overall, this paper further supports the potential of using combination phage and chemical disinfectant treatments to improve the inactivation of surface-associated P. aeruginosa. IMPORTANCE Phages are already utilized in the health care industry to treat antibiotic-resistant infections, such as those on implant-associated biofilms and in compassionate-care cases. Phage treatment could also be a promising new tool to control pathogens in the built environment, preventing infections from occurring. This study shows that phages can be combined effectively with chemical disinfectants to improve the removal of wet biofilms and bacteria spotted onto surfaces while preventing regrowth in dry biofilms. This has the potential to improve pathogen containment within the built environment and drinking water infrastructure to prevent infections by opportunistic pathogens.

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The chemical composition of the lipopolyacarideof Pseudomonas aeruginosa.

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