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Biofilm matrix

About: Biofilm matrix is a research topic. Over the lifetime, 1589 publications have been published within this topic receiving 110140 citations.


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TL;DR: This is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence.
Abstract: Ralstonia solanacearum is a soil-borne vascular pathogen that colonizes plant xylem vessels, a flowing, low-nutrient habitat where biofilms could be adaptive. Ralstonia solanacearum forms biofilm in vitro, but it was not known if the pathogen benefits from biofilms during infection. Scanning electron microscopy revealed that during tomato infection, R. solanacearum forms biofilm-like masses in xylem vessels. These aggregates contain bacteria embedded in a matrix including chromatin-like fibres commonly observed in other bacterial biofilms. Chemical and enzymatic assays demonstrated that the bacterium releases extracellular DNA in culture and that DNA is an integral component of the biofilm matrix. An R. solanacearum mutant lacking the pathogen's two extracellular nucleases (exDNases) formed non-spreading colonies and abnormally thick biofilms in vitro. The biofilms formed by the exDNase mutant in planta contained more and thicker fibres. This mutant was also reduced in virulence on tomato plants and did not spread in tomato stems as well as the wild-type strain, suggesting that these exDNases facilitate biofilm maturation and bacterial dispersal. To our knowledge, this is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence.

39 citations

Journal ArticleDOI
TL;DR: The data suggest that nitroxoline induces anticancer activity through AMPK-dependent inhibition of mTOR-p70S6K signaling pathway and cyclin D1-Rb-Cdc25A axis, leading to G1 arrest of cell cycle and apoptosis.
Abstract: Nitroxoline is an antibiotic by chelating Zn2+ and Fe2+ from biofilm matrix. In this study, nitroxoline induced G1 arrest of cell cycle and subsequent apoptosis in prostate cancer cells through ion chelating-independent pathway. It decreased protein levels of cyclin D1, Cdc25A and phosphorylated Rb, but activated AMP-activated protein kinase (AMPK), a cellular energy sensor and signal transducer, leading to inhibition of downstream mTOR-p70S6K signaling. Knockdown of AMPKα significantly rescued nitroxoline-induced inhibition of cyclin D1-Rb-Cdc25A axis indicating AMPK-dependent mechanism. However, cytoprotective autophagy was simultaneously evoked by nitroxoline. Comet assay and Western blot analysis demonstrated DNA damaging effect and activation of Chk2 other than Chk1 to nitroxoline action. Instead of serving as a DNA repair transducer, nitroxoline-mediated Chk2 activation was identified to function as a pro-apoptotic inducer. In conclusion, the data suggest that nitroxoline induces anticancer activity through AMPK-dependent inhibition of mTOR-p70S6K signaling pathway and cyclin D1-Rb-Cdc25A axis, leading to G1 arrest of cell cycle and apoptosis. AMPK-dependent activation of Chk2, at least partly, contributes to apoptosis. The data suggest the potential role of nitroxoline for therapeutic development against prostate cancers.

39 citations

Journal ArticleDOI
Lei Lei1, Yingming Yang1, Mengying Mao1, Hong Li1, Meng Li1, Yan Yang1, Jia-Xin Yin1, Tao Hu1 
TL;DR: The results suggest that vicX gene modulates the structural characteristics of exopolysaccharide associated with cariogenicity, which may be explored as a potential target that contributes to dental caries management.
Abstract: The cariogenic pathogen Streptococcus mutans effectively utilizes dietary sucrose for the synthesis of exopolysaccharide, which act as a scaffold for its biofilm, thus contributing to its pathogenicity, environmental stress tolerance, and antimicrobial resistance. The two-component system VicRK of S. mutans regulates a group of virulence genes that are associated with biofilm matrix synthesis. Knockout of vicX affects biofilm formation, oxidative stress tolerance, and transformation of S. mutans. However, little is known regarding the vicX-modulated structural characteristics of the exopolysaccharides underlying the biofilm formation and the phenotypes of the vicX mutants. Here, we identified the role of vicX in the structural characteristics of the exopolysaccharide matrix and biofilm physiology. The vicX mutant (SmuvicX) biofilms seemingly exhibited "desertification" with architecturally impaired exopolysaccharide-enmeshed cell clusters, compared with the UA159 strain (S. mutans wild type strain). Concomitantly, SmuvicX showed a decrease in water-insoluble glucan (WIG) synthesis and in WIG/water-soluble glucan (WSG) ratio. Gel permeation chromatography (GPC) showed that the WIG isolated from the SmuvicX biofilms had a much lower molecular weight compared with the UA159 strain indicating differences in polysaccharide chain lengths. A monosaccharide composition analysis demonstrated the importance of the vicX gene in the glucose metabolism. We performed metabolite profiling via (1)H nuclear magnetic resonance spectroscopy, which showed that several chemical shifts were absent in both WSG and WIG of SmuvicX biofilms compared with the UA159 strain. Thus, the modulation of structural characteristics of exopolysaccharide by vicX provides new insights into the interaction between the exopolysaccharide structure, gene functions, and cariogenicity. Our results suggest that vicX gene modulates the structural characteristics of exopolysaccharide associated with cariogenicity, which may be explored as a potential target that contributes to dental caries management. Furthermore, the methods used to purify the EPS of S. mutans biofilms and to analyze multiple aspects of its structure (GPC, gas chromatography-mass spectrometry, and (1)H nuclear magnetic resonance spectroscopy) may be useful approaches to determine the roles of other virulence genes for dental caries prevention.

39 citations

Journal ArticleDOI
TL;DR: In this paper, the polysaccharide fraction present in the extracted polymeric matrix of a biofilm by differential precipitation of the protein content was obtained by pH adjustment and by addition of trichloroacetic acid (TCA).
Abstract: The objective was to obtain the polysaccharide fraction present in the extracted polymeric matrix of a biofilm by differential precipitation of the protein content. This was tried by pH adjustment and by addition of trichloroacetic acid (TCA). The best yield of protein precipitation was with 20% (w/v) TCA, with more than 97% of the protein removed and without affecting the amount of polysaccharides in solution.

39 citations

Journal ArticleDOI
01 Oct 2004-Biofilms
TL;DR: Individual-based modelling of biofilms structure dynamics is used here to unify observations from the operation of biofilm reactors by simulating biofilm growth under variable detachment forces and mass transport regimens for a growth-limiting substrate.
Abstract: In spite of the large range of morphologies observed for biofilms, there is strong experimental and theoretical evidence that the complex nature of biofilm structure dynamics is primarily a consequence of the effect of environmental conditions on biofilm development. It has been observed from the operation of industrial and laboratory-scale biofilm reactors that the structure of biofilms results from a balance of the detachment forces and the regimen of transport of a growth-limiting substrate. The overall performance of biofilm reactors is intrinsically dependent on biofilm morphology. The spatial distribution of the diverse dissolved and particulate components through the biofilm matrix and the shape of its external surface influence the rates of the occurring bioconversions, and structure also influences the stability of the biofilm in terms of resistance to mechanical stress. Individual-based modelling (IbM) of biofilms structure dynamics is used here to unify observations from the operation of biofilm reactors by simulating biofilm growth under variable detachment forces and mass transport regimens for a growth-limiting substrate. The IbM is a bottom-up approach, where the global system behaviour is derived from the local interactions of multiple elements acting independently. Transport and reaction of a solute species, local microbial growth rates and the effect of external detachment forces applied to the biofilm are modelled using differential approaches. Simulations carried out in two-dimensional space using this model illustrate a range of biofilm morphologies that emerge from different reactor operation parameters, reproducing trends observed experimentally. Comparison of multi-dimensional modelling results with those obtained using one-dimensional approaches enforces the need to use multidimensional modelling to predict properties that derive from the spatial biofilm structure.

39 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20224
2021138
2020189
2019157
2018121
2017113