Roles for flagellar stators in biofilm formation by Pseudomonas aeruginosa

Toutain, Christine M.; Caizza, Nicky C.; Zegans, Michael E.; O’Toole, George A.

doi:10.1016/j.resmic.2007.04.001

Cited by 118 publications

(102 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…4 A and B) of wild type and mutant strains harboring defects in genes required for biofilm formation on smooth surfaces. In standard assays with glucose-based medium, flagellar-mediated swimming motility leads to increased residence times of cells near surfaces (36), and flagella also enhance attachment to surfaces (21,22,37). However, we find that a nonmotile flagellar mutant (ΔflgK) forms streamers with a similar T to wild type, even though it has a significantly larger τ (Fig.…”

Section: Resultsmentioning

confidence: 75%

Biofilm streamers cause catastrophic disruption of flow with consequences for environmental and medical systems

Drescher

Shen

Bassler

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

305

396

View full text Add to dashboard Cite

Biofilms are antibiotic-resistant, sessile bacterial communities that occupy most moist surfaces on Earth and cause chronic and medical device-associated infections. Despite their importance, basic information about biofilm dynamics in common ecological environments is lacking. Here, we demonstrate that flow through soil-like porous materials, industrial filters, and medical stents dramatically modifies the morphology of Pseudomonas aeruginosa biofilms to form 3D streamers, which, over time, bridge the spaces between obstacles and corners in nonuniform environments. We discovered that accumulation of surface-attached biofilm has little effect on flow through such environments, whereas biofilm streamers cause sudden and rapid clogging. We demonstrate that flow-induced shedding of extracellular matrix from surface-attached biofilms generates a sievelike network that captures cells and other biomass, which add to the existing network, causing exponentially fast clogging independent of growth. These results suggest that biofilm streamers are ubiquitous in nature and strongly affect flow through porous materials in environmental, industrial, and medical systems.bioclogging | biofouling | porous media I n the laboratory, bacteria are usually grown as planktonic cells in shaken suspensions, which differs dramatically from the natural environments of most microbes. In their natural habitats, bacteria often live in biofilms (1-3), which are tightly packed, surface-associated assemblies of bacteria that are bound together by extracellular polymeric substances (4, 5). Although biofilms are desirable in waste-water treatment (6), biofilms primarily cause undesirable effects such as chronic infections or clogging of industrial flow systems (1-3). Cells in biofilms display many behavioral differences from planktonic cells, such as a 1,000-fold increase in tolerance to antibiotics (7,8), an altered transcriptome (9-11), and spatially heterogeneous metabolic activity (12, 13). Some of these physiological peculiarities of biofilm-dwelling cells may be due to strong gradients of nutrients and metabolites, which also affect biofilm morphology and composition (14, 15). However, little is known about how physical aspects of the environment affect biofilm dynamics.The opportunistic pathogen Pseudomonas aeruginosa has become a model organism for biofilm studies largely because it forms biofilms in diverse habitats, including soil, rivers, sewage, and medical devices in humans (1, 2, 16). Two features are common to all of these environments: First, the presence of rough surfaces, which at the microscopic level reduce to surfaces with many corners, and second, a pressure-driven flow. The standard assay for growing biofilms in the laboratory abstracts from these realistic environments by typically using a smooth surface as a substrate, and either no flow or a pump to force nutritious medium across the biofilm at a constant flow rate (17-19). These standard assays have enabled the identification of several genes involved in biofilm develo...

show abstract

Section: Resultsmentioning

confidence: 75%

Biofilm streamers cause catastrophic disruption of flow with consequences for environmental and medical systems

Drescher

Shen

Bassler

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

305

396

View full text Add to dashboard Cite

show abstract

“…Evidence for this was provided by several research laboratories (92,155,156,163) and is exemplified by findings of Van Dellen et al (160) demonstrating that while V. cholerae O139 flagellar mutants show reduced attachment, they eventually form a robust monolayer biofilm. In contrast, monolayer formation was severely impaired in the absence of the flagellar motor.…”

Section: The First Contactmentioning

confidence: 90%

“…During this phase, bacteria can be rapidly spinning, vibrating, or moving across the substrate surface. Spinning is an indication of flagellar attachment to the substrate (140,155), with the bacterium rotating around its axis. In addition to Brownian motion, some bacterial cells in contact with the surface exhibit a jerky type of motion called twitching motility, which requires pili.…”

Section: The First Contactmentioning

confidence: 99%

“…While both the MotAB and MotCD stators play a role in initial polar attachment to the surface (reversible attachment), MotAB also participates in the downstream irreversible attachment, with inactivation of motAB, but not motCD, significantly increasing the percentage of cells transitioning to the irreversible attachment stage, as indicated by cells attached along their axis to the surface (155). Both MotAB and MotCD affected the flagellum reversal rate, which is significantly increased upon deletion of the flagellar stators, resulting in increased surface movement (155). Similar observations were made in Listeria monocytogenes by comparing the wild type with flagellum-lacking and paralyzed-flagellum mutants (92).…”

Section: The First Contactmentioning

confidence: 99%

See 1 more Smart Citation

Sticky Situations: Key Components That Control Bacterial Surface Attachment

Petrova

Sauer

2012

Journal of Bacteriology

319

251

View full text Add to dashboard Cite

show abstract

“…In pathogenic bacteria, flagella are usually considered as virulence factors (Josenhans & Suerbaum, 2002), and they play crucial roles in adhesion, colonization and biofilm formation of many bacteria such as Pseudomonas aeruginosa (Toutain et al, 2007), Escherichia coli (Pratt & Kolter, 1998), Vibrio cholerae (Gardel & Mekalanos, 1996) and Salmonella typhimurium (Ciacci-Woolwine et al, 1998). Flagellar gene regulation and assembly have been extensively characterized in E. coli and S. enterica serovar Typhimurium (Aldridge & Hughes, 2002).…”

Section: Introductionmentioning

confidence: 99%

Positive regulation of flhDC expression by OmpR in Yersinia pseudotuberculosis

Wang

Ding

et al. 2009

Microbiology

View full text Add to dashboard Cite

OmpR has been demonstrated to negatively regulate the expression of the flagellar master operon flhDC in a wide variety of bacterial species. Here we report the positive regulation of flhDC expression by OmpR in Yersinia pseudotuberculosis. A s 70 -dependent promoter was identified by primer extension analysis and an active region with two conserved OmpR-binding sites around the flhDC promoter was confirmed. To confirm the regulation of flhDC expression by OmpR, flhDC as well as the downstream flagellar genes fliA, flgD, flgA, flgM, fliC and flaA were fused to lacZ, and decreased expression of all these genes in an ompR mutant (DompR) was detected. Furthermore, DompR was defective in bacterial motility and flagella synthesis. This defect was due to the low level of expression of flhDC in DompR since overproduction of FlhDC in DompR restored bacterial motility. The importance of two conserved OmpR-binding sites around the flhDC promoter region in the regulation of flhDC expression by OmpR was demonstrated by the fact that mutation of either one or both sites significantly decreased the promoter activity in the wild-type but not in DompR. The binding of OmpR to these two sites was also demonstrated by DNA mobility shift assay. The possible mechanism underlying this positive regulation in Y. pseudotuberculosis is discussed. To our knowledge, this is the first report to demonstrate that OmpR positively regulates flhDC expression. INTRODUCTIONFlagella, the unique structure for motility, represent an important advantage for bacteria in moving towards favourable conditions or in avoiding detrimental environments. In pathogenic bacteria, flagella are usually considered as virulence factors (Josenhans & Suerbaum, 2002), and they play crucial roles in adhesion, colonization and biofilm formation of many bacteria such as Pseudomonas aeruginosa (Toutain et al., 2007), Escherichia coli (Pratt & Kolter, 1998), Vibrio cholerae (Gardel & Mekalanos, 1996) and Salmonella typhimurium (Ciacci-Woolwine et al., 1998). Flagellar gene regulation and assembly have been extensively characterized in E. coli and S. enterica serovar Typhimurium (Aldridge & Hughes, 2002). Over 60 genes, which are arranged into three classes (class I, class II and class III), are coordinately regulated and expressed in a transcriptional hierarchy (Chilcott & Hughes, 2000;Kanehisa et al., 2004;Kutsukake et al., 1990). Transcription of the downstream flagellar genes is dependent on a high expression level of some upstream genes. At the top of this hierarchy is the master operon composed of the genes flhD and flhC. FlhD and FlhC together form a heterohexameric transcriptional activator that binds to the class II operons (Wang et al., 2006). Due to the key role of flhDC in flagella synthesis, the regulation of its expression has been studied at both the transcriptional and post-transcriptional levels (Soutourina & Bertin, 2003). Many regulatory proteins, such as H-NS (Bertin et al., 1994;Soutourina et al., 1999), cAMP-CAP complex (catabolite gene activator protei...

show abstract

Roles for flagellar stators in biofilm formation by Pseudomonas aeruginosa

Cited by 118 publications

References 27 publications

Biofilm streamers cause catastrophic disruption of flow with consequences for environmental and medical systems

Biofilm streamers cause catastrophic disruption of flow with consequences for environmental and medical systems

Sticky Situations: Key Components That Control Bacterial Surface Attachment

Positive regulation of flhDC expression by OmpR in Yersinia pseudotuberculosis

Contact Info

Product

Resources

About