Role of polysaccharides in Pseudomonas aeruginosa biofilm development. Curr Opin Microbiol

Department of Microbiology and Immunology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1064, United States.
Current Opinion in Microbiology (Impact Factor: 5.9). 01/2008; 10(6):644-8. DOI: 10.1016/j.mib.2007.09.010
Source: PubMed


During the past decade, there has been a renewed interest in using Pseudomonas aeruginosa as a model system for biofilm development and pathogenesis. Since the biofilm matrix represents a crucial interface between the bacterium and the host or its environment, considerable effort has been expended to acquire a more complete understanding of the matrix composition. Here, we focus on recent developments regarding the roles of alginate, Psl, and Pel polysaccharides in the biofilm matrix.

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    • "One of the defining features of the biofilm is the presence of a self-produced extra-cellular matrix. This matrix not only provides the scaffold for adhesion to surfaces and cohesion between cells, but also protects the cells from stresses such as desiccation, oxidizing agents and host immune defenses (DeVault et al., 1990; Ophir and Gutnick, 1994; Pier et al., 2001; O'Toole, 2003; Parsek and Singh, 2003; Friedman and Kolter, 2004; Jackson et al., 2004; Ryder et al., 2007). The matrix can additionally sequester valuable enzymes and nutrients, cellto-cell communication signals and fosters the exchange of genetic material (Stoodley et al., 2002). "
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    ABSTRACT: Pseudomonas aeruginosa PAO1 produces three polysaccharides, alginate, Psl, and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl, and Pel during biofilm formation of P. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of P. aeruginosa, Pseudomonas protegens, and Klebsiella pneumoniae. Loss of the Psl polysaccharide had the biggest impact on the integration of P. aeruginosa in the mixed species biofilms, where the percent composition of the psl mutant was significantly lower (0.06%) than its wild-type (WT) parent (2.44%). In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in P. aeruginosa representing 8.4 and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of P. aeruginosa and K. pneumoniae were not affected by loss of alginate, Pel, or Psl, while the mucoid P. aeruginosa strain achieved a greater biomass than its parent strain. When P. aeruginosa was grown with P. protegens, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the WT PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35-40% of P. aeruginosa, which was significantly higher than the WT (5-20%). Loss of the Psl polysaccharide significantly reduced the percentage composition of P. aeruginosa in dual species biofilms with P. protegens (<1%). Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such communities.
    Full-text · Article · Sep 2015 · Frontiers in Microbiology
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    • "These surface-associated microbial communities of cells are embedded into a matrix of extracellular polymeric substances (Donlan and Costerton, 2002; Allesen-Holm et al., 2006; Ma et al., 2009). In P. aeruginosa, the matrix contains an array of components such as extracellular DNA (Allesen-Holm et al., 2006; Ma et al., 2009), proteinaceous adhesins, vesicles and exopolysaccharides (EPS; Ryder et al., 2007; Gooderham and Hancock, 2009; Mikkelsen et al., 2011). In several non-mucoid strains, such as the PAO1 strain, Psl and Pel are two key EPS that maintain biofilm structure (Friedman and Kolter, 2004a; Ma et al., 2006; Colvin et al., 2012). "
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    ABSTRACT: OprF is the major outer membrane porin in bacteria belonging to the Pseudomonas genus. In previous studies, we have shown that OprF is required for full virulence expression of the opportunistic pathogen Pseudomonas aeruginosa. Here, we describe molecular insights on the nature of this relationship and report that the absence of OprF leads to increased biofilm formation and production of the Pel exopolysaccharide. Accordingly, the level of c-di-GMP, a key second messenger in biofilm control, is elevated in an oprF mutant. By decreasing c-di-GMP levels in this mutant, both biofilm formation and pel gene expression phenotypes were restored to wild-type levels. We further investigated the impact on two small RNAs, which are associated with the biofilm lifestyle, and found that expression of rsmZ but not of rsmY was increased in the oprF mutant and this occurs in a c-di-GMP-dependent manner. Finally, the extracytoplasmic function (ECF) sigma factors AlgU and SigX displayed higher activity levels in the oprF mutant. Two genes of the SigX regulon involved in c-di-GMP metabolism, PA1181 and adcA (PA4843), were up-regulated in the oprF mutant, partly explaining the increased c-di-GMP level. We hypothesized that the absence of OprF leads to a cell envelope stress that activates SigX and results in a c-di-GMP elevated level due to higher expression of adcA and PA1181. The c-di-GMP level can in turn stimulate Pel synthesis via increased rsmZ sRNA levels and pel mRNA, thus affecting Pel-dependent phenotypes such as cell aggregation and biofilm formation. This work highlights the connection between OprF and c-di-GMP regulatory networks, likely via SigX (ECF), on the regulation of biofilm phenotypes.
    Full-text · Article · Jun 2015 · Frontiers in Microbiology
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    • "Alginate is found as the major component of polysaccharides of the biofilm matrix produced by mucoid P. aeruginosa, controlled by alg genes [6] [32]. Non-mucoid P. aeruginosa make use of two loci pel and/or psl [6] [18] [34]. The pel locus contains seven genes (pel A–G) responsible for the production of glucose rich compounds involved in pellicle formation, whereas psl locus consists of 15 genes (psl A–O) involved in the production of polysaccharides enriched in glucose, mannose, rhamnose, and galactose [6] [18]. "
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    ABSTRACT: Indigenous Cr(VI) reducing bacterial strains Pseudomonas aeruginosa Rb-1 and Ochrobactrum intermedium Rb-2 were evaluated for EPS production under Cr(VI) challenged and free conditions. Strain Rb-2 was more efficient in total EPS production (13.63 mg g(-1) ) than Rb-1 (4.15 mg g(-1) ) under Cr(VI) stress. Thick covering of capsular material around the cells of both bacterial strains was detected by electron microscopy. Transmission electron micrographs showed the appearance of pilli like structures under chromium stress by two bacteria suggested the possible involvement of this in exchange of hereditary material to increase their chances of survival under stress conditions. FTIR study showed involvement of sulphonate and hydroxyl groups in the binding with Cr(VI) ions. Solid-state (13) C NMR spectra revealed that EPS produced by both strains exhibited structural similarity with the glucan. The partial psl gene sequences of Rb-1 and Rb-2 showed homology with psl gene of Pseudomonas aeruginosa PAO1 and capsular polysaccharide biosynthesis protein of various strains of Pseudomonas. This is the first report on the identification of psl gene from Ochrobacterum in NCBI GenBank database up to our knowledge. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Full-text · Article · Apr 2015 · Journal of Basic Microbiology
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