Biofilm : mise en place et organisation d’une communauté bactérienne

Filloux, Alain; Vallet-Gély, Isabelle

doi:10.1051/medsci/200319177

Cited by 43 publications

(13 citation statements)

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“…It is a cause of life-threatening lung infections in individuals with cystic fibrosis (CF), which are impossible to eradicate due to the biofilm lifestyle, adopted by this microorganism [1], [2].…”

Section: Introductionmentioning

confidence: 99%

Chemical Analysis of Cellular and Extracellular Carbohydrates of a Biofilm-Forming Strain Pseudomonas aeruginosa PA14

et al. 2010

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Background Pseudomonas aeruginosa is a Gram-negative bacterium and an opportunistic pathogen, which causes persisting life-threatening infections in cystic fibrosis (CF) patients. Biofilm mode of growth facilitates its survival in a variety of environments. Most P. aeruginosa isolates, including the non-mucoid laboratory strain PA14, are able to form a thick pellicle, which results in a surface-associated biofilm at the air-liquid (A–L) interface in standing liquid cultures. Exopolysaccharides (EPS) are considered as key components in the formation of this biofilm pellicle. In the non-mucoid P. aeruginosa strain PA14, the “scaffolding” polysaccharides of the biofilm matrix, and the molecules responsible for the structural integrity of rigid A–L biofilm have not been identified. Moreover, the role of LPS in this process is unclear, and the chemical structure of the LPS O-antigen of PA14 has not yet been elucidated.Principal FindingsIn the present work we carried out a systematic analysis of cellular and extracellular (EC) carbohydrates of P. aeruginosa PA14. We also elucidated the chemical structure of the LPS O-antigen by chemical methods and 2-D NMR spectroscopy. Our results showed that it is composed of linear trisaccharide repeating units, identical to those described for P. aeruginosa Lanýi type O:2a,c (Lanýi-Bergman O-serogroup 10a, 10c; IATS serotype 19) and having the following structure: -4)-α-L-GalNAcA-(1–3)-α-D-QuiNAc-(1–3)- α-L-Rha-(1-. Furthermore, an EC O-antigen polysaccharide (EC O-PS) and the glycerol-phosphorylated cyclic β-(1,3)-glucans were identified in the culture supernatant of PA14, grown statically in minimal medium. Finally, the extracellular matrix of the thick biofilm formed at the A-L interface contained, in addition to eDNA, important quantities (at least ∼20% of dry weight) of LPS-like material.ConclusionsWe characterized the chemical structure of the LPS O-antigen and showed that the O-antigen polysaccharide is an abundant extracellular carbohydrate of PA14. We present evidence that LPS-like material is found as a component of a biofilm matrix of P. aeruginosa.

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Section: Introductionmentioning

confidence: 99%

Chemical Analysis of Cellular and Extracellular Carbohydrates of a Biofilm-Forming Strain Pseudomonas aeruginosa PA14

et al. 2010

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“…À ce stade, l'incorporation de bactéries d'espèces différentes ou d'autres microorganismes mène à la formation de biofilms polymicrobiens ou mixtes [2,9]. Le biofilm mature peut connaître une phase de dispersion, libérant des bactéries isolées ou des fragments de biofilms qui pourront, à leur tour, enclencher la formation d'un biofilm sur une autre surface (Figure 1) [2,10,11].…”

Section: Un Haut Lieu De Sociomicrobiologie Et D'échangesunclassified

Infections associées aux biofilms

Lebeaux

Ghigo

2012

Med Sci (Paris)

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> Les biofilms sont des communautés de microorganismes en contact avec une surface. Bien que bénéfiques dans la plupart des environnements, les biofilms bactériens se développant sur des implants ou lors d'infections chroniques constituent des réservoirs de pathogènes à l'origine de nombreuses infections nosocomiales. Malgré la mise en oeuvre de mesures préventives, les biofilms sont difficiles à éradiquer en raison de leur tolé-rance caractéristique à des doses élevées d'antibiotiques. Cette revue présente les progrès récents de la recherche sur la formation, les fonctions originales et le contrôle de ces communautés, qui permettent à présent d'envisager de nouvelles stratégies dirigées contre les biofilms. < Le biofilm : un mode de vie original En dépit de la diversité des situations écologiques, industrielles ou médicales concernées par la formation des biofilms, toutes ces entités biologiques partagent des caractéristiques communes.Un développement dynamique L'adhérence initiale d'une bactérie sur une surface est d'abord conditionnée par ses propriétés physicochimiques (hydrophobie et charge électrostatique). Elle fait ensuite intervenir des macromolécules de l'enveloppe bactérienne -souvent appelées adhésines -qui interagissent de manière spécifique ou non avec les surfaces (Figure 1) [3,7]. Des polysaccharides entrant dans la composition de la matrice extracellulaire assurent également une cohésion mécanique entre les bactéries et contribuent au passage de la « vie libre » à la « vie fixée » [8]. Une petite molécule diffusible, le di-guanosine monophosphate cyclique (di-GMPc), constitue un second messager central régulant la transition entre la vie planctonique et l'établissement d'un biofilm (Figure 2). Sa concentration intracellulaire est influencée par de nombreux stimulus environnementaux et régule l'expression de gènes impliqués dans la formation de biofilm (production de polysaccharides de la matrice) ou bien impliqués dans le phénotype mobile (production de flagelle) [3]. Après leur adhérence au substrat, qui peut survenir dans les secondes qui suivent le contact avec une surface, les bactéries s'agrègent, se

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“…Adherence, the specific attachment of microorganisms to epithelial cells (Figs 4–6), is an initial step in the pathogenesis of epithelial tissue infection. Biofilm formation and the production of capsular polysaccharide slime can also be important steps in this process and may be controlled by quorum sensing activity related to cell density 25,26 . Bacterial adherence involves different types of lectins (adhesins), depending on bacterial strain and host cell.…”

Section: Sugars In Cell Signalling and Host–microbial Interactionmentioning

confidence: 99%

Role of sugars in surface microbe–host interactions and immune reaction modulation

Lloyd

Viac

Werling

et al. 2007

Veterinary Dermatology

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Sugars in the form of monosaccharides, oligosaccharides, polysaccharides and glycoconjugates (glycoproteins, glycolipids) are vital components of infecting microbes and host cells, and are involved in cell signalling associated with modulation of inflammation in all integumental structures. Indeed, sugars are the molecules most commonly involved in cell recognition and communication. In skin, they are essential to epidermal development and homeostasis. They play important roles in microbial adherence, colonization and biofilm formation, and in virulence. Two groups of pathogen recognition receptors, C-type lectins (CTL) and their receptors (CTLR), and the Toll-like receptors enable the host to recognize pathogen-associated molecular patterns (PAMPs), which are mainly glycolipids. The CTLs can recognize a wide variety of bacteria, fungi and parasites and are important in phagocytosis and endocytosis. TLRs are expressed on the surfaces of a variety of cells, including keratinocytes, dendritic cells, monocytes and macrophages; they play a major role in innate immunity. Interaction of TLRs with PAMPs initiates a cascade of events leading to production of reactive oxygen intermediates, cytokines and chemokines, and promotes inflammation. Exogenous sugars can block carbohydrate receptors and competitively displace bacteria from attachment to cells, including keratinocytes. Thus sugars may provide valuable adjunctive anti-inflammatory and/or antimicrobial treatment. A promising approach is the use of a panel of carbohydrate derivatives with anti-adhesive efficacy against bacteria frequently involved in diseases affecting skin and other epithelia. More complete characterization of sugar receptors and their ligands will provide further keys to use of carbohydrates in immunomodulation and infection control in skin.

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Biofilm : mise en place et organisation d’une communauté bactérienne

Cited by 43 publications

References 29 publications

Chemical Analysis of Cellular and Extracellular Carbohydrates of a Biofilm-Forming Strain Pseudomonas aeruginosa PA14

Chemical Analysis of Cellular and Extracellular Carbohydrates of a Biofilm-Forming Strain Pseudomonas aeruginosa PA14

Infections associées aux biofilms

Role of sugars in surface microbe–host interactions and immune reaction modulation

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