scholarly journals Flow environment and matrix structure interact to determine spatial competition inPseudomonas aeruginosabiofilms

2016 ◽  
Author(s):  
Carey D. Nadell ◽  
Deirdre Ricaurte ◽  
Jing Yan ◽  
Knut Drescher ◽  
Bonnie L. Bassler
Keyword(s):  
Spatial Competition ◽  
Flow Speed ◽  
Hydrodynamic Flow ◽  
Natural Environments ◽  
Wild Type ◽  
Flow Conditions ◽  
Matrix Organization ◽  
Matrix Production ◽  
Spatial Architecture ◽  
Simple Flow

AbstractBacteria often live in biofilms, which are microbial communities surrounded by a secreted extracellular matrix. Here, we demonstrate that hydrodynamic flow and matrix organization interact to shape competitive dynamics inPseudomonas aeruginosabiofilms. Irrespective of initial frequency, in competition with matrix mutants, wild type cells always increase in relative abundance in straight-tunnel microfluidic devices under simple flow regimes. By contrast, in microenvironments with complex, irregular flow profiles - which are common in natural environments - wild type matrix-producing and isogenic non-producing strains can coexist. This result stems from local obstruction of flow by wild-type matrix producers, which generates regions of near-zero flow speed that allow matrix mutants to locally accumulate. Our findings connect the evolutionary stability of matrix production with the hydrodynamics and spatial structure of the surrounding environment, providing a potential explanation for the variation in biofilm matrix secretion observed among bacteria in natural environments.Impact StatementThe feedback between hydrodynamic flow conditions and biofilm spatial architecture drives competition inP. aeruginosabiofilms, and can explain the variation in biofilm production observed among bacteria in natural environments.

scholarly journals Flow environment and matrix structure interact to determine spatial competition in Pseudomonas aeruginosa biofilms

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Carey D Nadell ◽  
Deirdre Ricaurte ◽  
Jing Yan ◽  
Knut Drescher ◽  
Bonnie L Bassler
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Spatial Competition ◽  
Evolutionary Stability ◽  
Competitive Dynamics ◽  
Natural Environments ◽  
Wild Type ◽  
Surrounding Environment ◽  
Matrix Organization ◽  
Matrix Production ◽  
Simple Flow

Bacteria often live in biofilms, which are microbial communities surrounded by a secreted extracellular matrix. Here, we demonstrate that hydrodynamic flow and matrix organization interact to shape competitive dynamics in Pseudomonas aeruginosa biofilms. Irrespective of initial frequency, in competition with matrix mutants, wild-type cells always increase in relative abundance in planar microfluidic devices under simple flow regimes. By contrast, in microenvironments with complex, irregular flow profiles – which are common in natural environments – wild-type matrix-producing and isogenic non-producing strains can coexist. This result stems from local obstruction of flow by wild-type matrix producers, which generates regions of near-zero shear that allow matrix mutants to locally accumulate. Our findings connect the evolutionary stability of matrix production with the hydrodynamics and spatial structure of the surrounding environment, providing a potential explanation for the variation in biofilm matrix secretion observed among bacteria in natural environments.

Hydrodynamic flow conditions through permeable walls

1992 ◽  
Vol 2 (8) ◽  
pp. 1565-1569
Author(s):  
S. Vollmar ◽  
J. A. M. S. Duarte
Keyword(s):  
Hydrodynamic Flow ◽  
Flow Conditions ◽  
Permeable Walls

Electrochemical Kinetic of a Low Carbon Steel in Seawater at Different Flow Speed

2015 ◽  
Vol 1766 ◽  
pp. 73-80
Author(s):  
A. Carmona ◽  
R. Orozco-Cruz ◽  
E. Mejía-Sánchez ◽  
A. Contreras ◽  
R. Galván-Martínez
Keyword(s):  
Turbulent Flow ◽  
Rotation Speed ◽  
Electrochemical Impedance ◽  
Static Condition ◽  
Flow Speed ◽  
Localized Corrosion ◽  
Low Carbon ◽  
Flow Conditions ◽  
Static Conditions ◽  
Turbulent Flow Conditions

ABSTRACTAn electrochemical impedance spectroscopy (EIS) corrosion study of API X70 steel was carried out in synthetic seawater with different rotation speeds using a rotating cylinder electrode (RCE) to control the hydrodynamic conditions at room temperature, atmospheric pressure and 24 h of exposure time. A superficial analysis through a scanning electron microscope (SEM) was used to analyze the corrosion type. The rotation speed used was 0 rpm (static condition), 1000, 3000 and 5000 rpm (turbulent flow). The results show that the turbulent flow conditions affect directly the corrosion rate (CR) of the steel, because all values of the CR under turbulent flow conditions are higher than the CR values at static conditions. In addition, it is important to point out that at turbulent flow conditions, the CR increased as the rotation speed also increased. The morphology of the corrosion in all experiments was localized corrosion.

Cell Adhesion Under Hydrodynamic Flow Conditions

1995 ◽  
Vol 15 (1) ◽  
Author(s):  
Priya K. Gopalan ◽  
David A. Jones ◽  
Larry V. McIntire ◽  
C. Wayne Smith
Keyword(s):  
Cell Adhesion ◽  
Hydrodynamic Flow ◽  
Flow Conditions

scholarly journals Biofilm formation by group A Streptococcus: a role for the streptococcal regulator of virulence (Srv) and streptococcal cysteine protease (SpeB)

Microbiology ◽  
2009 ◽  
Vol 155 (1) ◽  
pp. 46-52 ◽  
Author(s):  
Christopher D. Doern ◽  
Amity L. Roberts ◽  
Wenzhou Hong ◽  
Jessica Nelson ◽  
Slawomir Lukomski ◽  
...  
Keyword(s):  
Cysteine Protease ◽  
Biofilm Formation ◽  
Group A Streptococcus ◽  
Immunoblot Analysis ◽  
Wild Type ◽  
Flow Conditions ◽  
Group A ◽  
Streptococcus A ◽  
Insight Into ◽  
Western Immunoblot Analysis

Recently, biofilms have become a topic of interest in the study of the human pathogen group A Streptococcus (GAS). In this study, we sought to learn more about the make-up of these structures and gain insight into biofilm regulation. Enzymic studies indicated that biofilm formation by GAS strain MGAS5005 required an extracellular protein and DNA component(s). Previous results indicated that inactivation of the transcriptional regulator Srv in MGAS5005 resulted in a significant decrease in virulence. Here, inactivation of Srv also resulted in a significant decrease in biofilm formation under both static and flow conditions. Given that production of the extracellular cysteine protease SpeB is increased in the srv mutant, we tested the hypothesis that increased levels of active SpeB may be responsible for the reduction in biofilm formation. Western immunoblot analysis indicated that SpeB was absent from MGAS5005 biofilms. Complementation of MGAS5005Δsrv restored the biofilm phenotype and eliminated the overproduction of active SpeB. Inhibition of SpeB with E64 also restored the MGAS5005Δsrv biofilm to wild-type levels.

scholarly journals Formation of Kinneyia via shear-induced instabilities in microbial mats

2013 ◽  
Vol 371 (2004) ◽  
pp. 20120362 ◽  
Author(s):  
Katherine Thomas ◽  
Stephan Herminghaus ◽  
Hubertus Porada ◽  
Lucas Goehring
Keyword(s):  
Microbial Mats ◽  
Flow Speed ◽  
Glass Beads ◽  
Flowing Water ◽  
Flow Conditions ◽  
Theoretical Predictions ◽  
Laboratory Analogue ◽  
Littoral Habitats ◽  
Over Time ◽  
Ripple Pattern

Kinneyia are a class of microbially mediated sedimentary fossils. Characterized by clearly defined ripple structures, Kinneyia are generally found in areas that were formally littoral habitats and covered by microbial mats. To date, there has been no conclusive explanation of the processes involved in the formation of these fossils. Microbial mats behave like viscoelastic fluids. We propose that the key mechanism involved in the formation of Kinneyia is a Kelvin–Helmholtz-type instability induced in a viscoelastic film under flowing water. A ripple corrugation is spontaneously induced in the film and grows in amplitude over time. Theoretical predictions show that the ripple instability has a wavelength proportional to the thickness of the film. Experiments carried out using viscoelastic films confirm this prediction. The ripple pattern that forms has a wavelength roughly three times the thickness of the film. This behaviour is independent of the viscosity of the film and the flow conditions. Laboratory-analogue Kinneyia were formed via the sedimentation of glass beads, which preferentially deposit in the troughs of the ripples. Well-ordered patterns form, with both honeycomb-like and parallel ridges being observed, depending on the flow speed. These patterns correspond well with those found in Kinneyia, with similar morphologies, wavelengths and amplitudes being observed.

scholarly journals Quorum Sensing Influences Burkholderia thailandensis Biofilm Development and Matrix Production

2016 ◽  
Vol 198 (19) ◽  
pp. 2643-2650 ◽  
Author(s):  
Boo Shan Tseng ◽  
Charlotte D. Majerczyk ◽  
Daniel Passos da Silva ◽  
Josephine R. Chandler ◽  
E. Peter Greenberg ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Matrix Material ◽  
Close Relative ◽  
Wild Type ◽  
Flow Conditions ◽  
Burkholderia Thailandensis ◽  
Content Type ◽  
Biofilm Development

ABSTRACTMembers of the genusBurkholderiaare known to be adept at biofilm formation, which presumably assists in the survival of these organisms in the environment and the host. Biofilm formation has been linked to quorum sensing (QS) in several bacterial species. In this study, we characterizedBurkholderia thailandensisbiofilm development under flow conditions and sought to determine whether QS contributes to this process.B. thailandensisbiofilm formation exhibited an unusual pattern: the cells formed small aggregates and then proceeded to produce mature biofilms characterized by “dome” structures filled with biofilm matrix material. We showed that this process was dependent on QS.B. thailandensishas three acyl-homoserine lactone (AHL) QS systems (QS-1, QS-2, and QS-3). An AHL-negative strain produced biofilms consisting of cell aggregates but lacking the matrix-filled dome structures. This phenotype was rescued via exogenous addition of the three AHL signals. Of the threeB. thailandensisQS systems, we show that QS-1 is required for proper biofilm development, since abtaR1mutant, which is defective in QS-1 regulation, forms biofilms without these dome structures. Furthermore, our data show that the wild-type biofilm biomass, as well as the material inside the domes, stains with a fucose-binding lectin. ThebtaR1mutant biofilms, however, are negative for fucose staining. This suggests that the QS-1 system regulates the production of a fucose-containing exopolysaccharide in wild-type biofilms. Finally, we present data showing that QS ability during biofilm development produces a biofilm that is resistant to dispersion under stress conditions.IMPORTANCEThe saprophyteBurkholderia thailandensisis a close relative of the pathogenic bacteriumBurkholderia pseudomallei, the causative agent of melioidosis, which is contracted from its environmental reservoir. Since most bacteria in the environment reside in biofilms,B. thailandensisis an ideal model organism for investigating questions inBurkholderiaphysiology. In this study, we characterizedB. thailandensisbiofilm development and sought to determine if quorum sensing (QS) contributes to this process. Our work shows thatB. thailandensisproduces biofilms with unusual dome structures under flow conditions. Our findings suggest that these dome structures are filled with a QS-regulated, fucose-containing exopolysaccharide that may be involved in the resilience ofB. thailandensisbiofilms against changes in the nutritional environment.

An experimental investigation of microplastic transport in fluvial systems

2020 ◽  
Author(s):  
Jan-Pascal Boos ◽  
Benjamin-Silas Gilfedder ◽  
Hassan Elagami ◽  
Sven Frei
Keyword(s):  
Porous Media ◽  
Channel Flow ◽  
Open Channel ◽  
Treatment Plant ◽  
Open Channel Flow ◽  
Agricultural Runoff ◽  
Hydrodynamic Flow ◽  
Waste Water Treatment Plant ◽  
Flow Conditions ◽  
Fluvial Systems

<p>Although a major part of marine microplastic (MP) pollution originates from rivers and streams, the mechanistic behavior of MP in fluvial systems is only poorly understood. MP enter fluvial systems from e.g. waste water treatment plant (WWTP) effluents, sewer overflows during heavy rain events, agricultural runoff, aerial input/atmospheric fallout, road runoff or via fragmentation of plastic litter. As part of this project we want to investigate the hydrodynamic transport mechanisms that control the behavior and re-distribution of MP in open channel flow and the streambed sediments. Hydrodynamic conditions in open channel flow are represented in an experimental flume environment.  Different porous media materials (e.g. aqua beads, glass beads and sand) are used in the flume experiments to shape typical bed form structures such as riffle-pool sequences, ripples and dunes. The aim of this experimental setup is to create hydrodynamic flow conditions such as hydraulic jumps, low and high flow velocity environments for which the transport and sedimentation behavior of MP can be investigated under realistic conditions. Hydrodynamic flow conditions in the flume are characterized using a Laser-Doppler-Anemometry (LDA) and Particle Image Velocimetry (PIV). Detection and tracking of fluorescent MP-particles in open channel flow and in porous media will be achieved with a fluorescence-camera-system.</p>

scholarly journals Adherence Properties of Staphylococcus aureus under Static and Flow Conditions: Roles of agrand sar Loci, Platelets, and Plasma Ligands

2001 ◽  
Vol 69 (7) ◽  
pp. 4473-4478 ◽  
Author(s):  
Boris Shenkman ◽  
Ethan Rubinstein ◽  
Ambrose L. Cheung ◽  
Grigory E. Brill ◽  
Rima Dardik ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Platelet Rich Plasma ◽  
Scintillation Counter ◽  
Static Condition ◽  
Image Analysis System ◽  
Wild Type ◽  
Flow Conditions ◽  
Induce Platelet Aggregation ◽  
Tissue Culture Polystyrene ◽  
Analysis System

ABSTRACT Global regulatory genes in Staphylococcus aureus, including agr and sar, are known to regulate the expression of multiple virulence factors, including cell wall adhesins. In the present study, the adherence of S. aureusRN6390 (wild type), RN6911 (agr), ALC136 (sar), and ALC135 (agr sar) to immobilized fibrinogen, fibronectin, von Willebrand factor (vWF), extracellular matrix (ECM), and human endothelial cells (EC) EAhy.926 was studied. Bacteria grown to postexponential phase were subjected to light oscillation (static condition) or to shear stress at 200 s−1 (flow condition) on tissue culture polystyrene plates coated with either protein ligands, ECM, or EC. Adherence of nonlabeled bacteria to immobilized ligands was measured by an image analysis system, while adherence of [3H]thymidine-labeled S. aureus to ECM and EC was measured by a β-scintillation counter. The results showed increased adherence of agr and agr sar mutants to immobilized fibrinogen and higher potential of these mutants to induce platelet aggregation in suspension, decreased adherence ofsar and agr sar mutants to immobilized fibronectin and vWF as well as to ECM and EC, increased adherence of both S. aureus wild type and sar mutant to EC treated with platelet-rich plasma (PRP) compared to platelet-poor plasma (PPP) and to EC treated with PPP compared to the control, and increased adherence of S. aureus wild type to EC coated with PRP in which platelets were activated with phorbol 12-myristate 13-acetate compared to intact PRP. This finding paralleled the increased adherence to EC of activated compared to intact platelets. It is suggested that platelet-mediated S. aureus adherence to EC depends on platelet activation and the number of adherent platelets and available receptors on the platelet membrane. In conclusion, theagr locus downregulates S. aureus adherence to fibrinogen, while the sar locus upregulates S. aureus adherence to fibronectin, vWF, ECM, and EC. The effect of both agr and sar on S. aureusadherence properties develops primarily under flow conditions, which suggests different adhesion mechanisms in static and flow conditions.

A simple flow-metering device for use in flood irrigation experiments

1964 ◽  
Vol 4 (12) ◽  
pp. 49
Author(s):  
RI Baxter
Keyword(s):  
Head Loss ◽  
Surface Irrigation ◽  
Flow Conditions ◽  
Flood Irrigation ◽  
Simple Version ◽  
Flow Metering ◽  
Irrigation Channels ◽  
Adequate Accuracy ◽  
Simple Flow

A flow-metering device has been developed for the measurement of rate of flow of water for flows up to one cubic foot per second from surface irrigation channels on to flood-irrigated land with a head difference less than six inches. Approach flow conditions do not affect the relation between rate of flow and head loss across the meter within the degree of accuracy required. A simple version of this meter is cheap to construct and gives adequate accuracy.

Sign in / Sign up

Export Citation Format

Share Document