scholarly journals Effects of PslG on the Surface Movement of Pseudomonas aeruginosa

2018 ◽  
Vol 84 (13) ◽  
Author(s):  
Jingchao Zhang ◽  
Jing He ◽  
Chunhui Zhai ◽  
Luyan Z. Ma ◽  
Lichuan Gu ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Single Cell ◽  
Human Society ◽  
Bacterial Cells ◽  
Content Type ◽  
Surface Movement ◽  
Bacterial Surface ◽  
Biofilm Control ◽  
Preferred Direction ◽  
Biofilm Development

ABSTRACT PslG attracted a lot of attention recently due to its great potential abilities in inhibiting biofilms of Pseudomonas aeruginosa . However, how PslG affects biofilm development still remains largely unexplored. Here, we focused on the surface motility of bacterial cells, which is critical for biofilm development. We studied the effects of PslG on bacterial surface movement in early biofilm development at a single-cell resolution by using a high-throughput bacterial tracking technique. The results showed that compared with no exogenous PslG addition, when PslG was added to the medium, bacterial surface movement was significantly (4 to 5 times) faster and proceeded in a more random way with no clear preferred direction. A further study revealed that the fraction of walking mode increased when PslG was added, which then resulted in an elevated average speed. The differences of motility due to PslG addition led to a clear distinction in patterns of bacterial surface movement and retarded microcolony formation greatly. Our results provide insight into developing new PslG-based biofilm control techniques. IMPORTANCE Biofilms of Pseudomonas aeruginosa are a major cause for hospital-acquired infections. They are notoriously difficult to eradicate and pose serious health hazards to human society. So, finding new ways to control biofilms is urgently needed. Recent work on PslG showed that PslG might be a good candidate for inhibiting/disassembling biofilms of Pseudomonas aeruginosa through Psl-based regulation. However, to fully explore PslG functions in biofilm control, a better understanding of PslG-Psl interactions is needed. Toward this end, we examined the effects of PslG on the surface movement of Pseudomonas aeruginosa in this work. The significance of our work is in greatly enhancing our understanding of the inhibiting mechanism of PslG on biofilms by providing a detailed picture of bacterial surface movement at a single-cell level, which will allow a full understanding of PslG abilities in biofilm control and thus present potential applications in biomedical fields.

scholarly journals Pf Filamentous Phage Requires UvrD for Replication in Pseudomonas aeruginosa

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Eriel Martínez ◽  
Javier Campos-Gómez
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Dna Repair ◽  
Dna Helicase ◽  
Filamentous Phage ◽  
Rolling Circle Replication ◽  
Content Type ◽  
Rolling Circle ◽  
Initiator Protein ◽  
Biofilm Development ◽  
Filamentous Phages

ABSTRACT Biofilm development is a key component of the ability of Pseudomonas aeruginosa to evade host immune defenses and resist multiple drugs. Induction of the filamentous phage Pf, which usually is lysogenized in clinical and environmental isolates of P. aeruginosa, plays an important role in biofilm assembly, maturation, and dispersal. Despite the clinical relevance of Pf, the molecular biology of this phage is largely unknown. In this study, we found that rolling circle replication of Pf depends on UvrD, a DNA helicase normally involved in DNA repair. We also identified the initiator protein of Pf and found that it shares structural similarity with that of Vibrio cholerae phages CTXφ and VGJφ, which also use UvrD for replication. Our results reveal that, in addition to DNA repair, UvrD plays an essential role in rolling circle replication of filamentous phages among diverse bacteria genera, adding a new, previously unrecognized function of this accessory helicase. Pf is a lysogenic filamentous phage that promotes biofilm development in Pseudomonas aeruginosa. Pf replicates by a rolling circle replication system which depends on a phage-encoded initiator protein and host factors usually involved in chromosome replication. Rep, an accessory replicative DNA helicase, is crucial for replication of filamentous phages in Escherichia coli. In contrast, here we show that, instead of depending on Rep, Pf replication depends on UvrD, an accessory helicase implicated in DNA repair. In this study, we also identified the initiator protein of Pf and found that it shares similarities with that of Vibrio phages CTXφ and VGJφ, which also depend on UvrD for replication. A structural comparative analysis of the initiator proteins of most known filamentous phages described thus far suggested that UvrD, known as a nonreplicative helicase, is involved in rolling circle replication of filamentous phages in diverse bacteria genera. This report consolidates knowledge on the new role of UvrD in filamentous phage replication, a function previously thought to be exclusive of Rep helicase. IMPORTANCE Biofilm development is a key component of the ability of Pseudomonas aeruginosa to evade host immune defenses and resist multiple drugs. Induction of the filamentous phage Pf, which usually is lysogenized in clinical and environmental isolates of P. aeruginosa, plays an important role in biofilm assembly, maturation, and dispersal. Despite the clinical relevance of Pf, the molecular biology of this phage is largely unknown. In this study, we found that rolling circle replication of Pf depends on UvrD, a DNA helicase normally involved in DNA repair. We also identified the initiator protein of Pf and found that it shares structural similarity with that of Vibrio cholerae phages CTXφ and VGJφ, which also use UvrD for replication. Our results reveal that, in addition to DNA repair, UvrD plays an essential role in rolling circle replication of filamentous phages among diverse bacteria genera, adding a new, previously unrecognized function of this accessory helicase.

scholarly journals Light-Mediated Decreases in Cyclic di-GMP Levels Inhibit Structure Formation in Pseudomonas aeruginosa Biofilms

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Lisa Juliane Kahl ◽  
Alexa Price-Whelan ◽  
Lars E. P. Dietrich
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Infections ◽  
Prolonged Exposure ◽  
Light Exposure ◽  
Research Attention ◽  
Content Type ◽  
Dependent Inhibition ◽  
Matrix Production ◽  
Biofilm Development ◽  
The Impact

ABSTRACT Light is known to trigger regulatory responses in diverse organisms, including slime molds, animals, plants, and phototrophic bacteria. However, light-dependent processes in nonphototrophic bacteria, and those of pathogens in particular, have received comparatively little research attention. In this study, we examined the impact of light on multicellular development in Pseudomonas aeruginosa, a leading cause of biofilm-based bacterial infections. We grew P. aeruginosa strain PA14 in a colony morphology assay and found that growth under prolonged exposure to low-intensity blue light inhibited biofilm matrix production and thereby the formation of vertical biofilm structures (i.e., “wrinkles”). Light-dependent inhibition of biofilm wrinkling was correlated with low levels of cyclic di-GMP (c-di-GMP), consistent with the role of this signal in stimulating matrix production. A screen of enzymes with the potential to catalyze c-di-GMP synthesis or degradation identified c-di-GMP phosphodiesterases that contribute to light-dependent inhibition of biofilm wrinkling. One of these, RmcA, was previously characterized by our group for its role in mediating the effect of redox-active P. aeruginosa metabolites called phenazines on biofilm wrinkle formation. Our results suggest that an RmcA sensory domain that is predicted to bind a flavin cofactor is involved in light-dependent inhibition of wrinkling. Together, these findings indicate that P. aeruginosa integrates information about light exposure and redox state in its regulation of biofilm development. IMPORTANCE Light exposure tunes circadian rhythms, which modulate the immune response and affect susceptibility to infection in plants and animals. Though molecular responses to light are defined for model plant and animal hosts, analogous pathways that function in bacterial pathogens are understudied. We examined the response to light exposure in biofilms (matrix-encased multicellular assemblages) of the nonphotosynthetic bacterium Pseudomonas aeruginosa. We found that light at intensities that are not harmful to human cells inhibited biofilm maturation via effects on cellular signals. Because biofilm formation is a critical factor in many types of P. aeruginosa infections, including burn wound infections that may be exposed to light, these effects could be relevant for pathogenicity.

scholarly journals The physical boundaries of public goods cooperation between surface-attached bacterial cells

2017 ◽  
Vol 284 (1858) ◽  
pp. 20170631 ◽  
Author(s):  
Michael Weigert ◽  
Rolf Kümmerli
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Soft Tissue ◽  
Fluorescence Microscopy ◽  
Social Interactions ◽  
Single Cell ◽  
Social Consequences ◽  
Social Effects ◽  
Bacterial Cells ◽  
Soft Tissue Infections ◽  
Natural Conditions

Bacteria secrete a variety of compounds important for nutrient scavenging, competition mediation and infection establishment. While there is a general consensus that secreted compounds can be shared and therefore have social consequences for the bacterial collective, we know little about the physical limits of such bacterial social interactions. Here, we address this issue by studying the sharing of iron-scavenging siderophores between surface-attached microcolonies of the bacterium Pseudomonas aeruginosa . Using single-cell fluorescence microscopy, we show that siderophores, secreted by producers, quickly reach non-producers within a range of 100 µm, and significantly boost their fitness. Producers in turn respond to variation in sharing efficiency by adjusting their pyoverdine investment levels. These social effects wane with larger cell-to-cell distances and on hard surfaces. Thus, our findings reveal the boundaries of compound sharing, and show that sharing is particularly relevant between nearby yet physically separated bacteria on soft surfaces, matching realistic natural conditions such as those encountered in soft tissue infections.

scholarly journals Lysine Trimethylation of EF-Tu Mimics Platelet-Activating Factor To Initiate Pseudomonas aeruginosa Pneumonia

mBio ◽  
2013 ◽  
Vol 4 (3) ◽  
Author(s):  
Mariette Barbier ◽  
Joshua P. Owings ◽  
Inmaculada Martínez-Ramos ◽  
F. Heath Damron ◽  
Rosa Gomila ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Platelet Activating Factor ◽  
Elongation Factor ◽  
Multidrug Resistant ◽  
Bacterial Attachment ◽  
Point Of View ◽  
Elongation Factor Tu ◽  
Human Pathogens ◽  
Content Type ◽  
Bacterial Surface

ABSTRACTPseudomonas aeruginosais a ubiquitous microorganism and the most common Gram-negative bacterium associated with nosocomial pneumonia, which is a leading cause of mortality among critically ill patients. Although many virulence factors have been identified in this pathogen, little is known about the bacterial components required to initiate infection in the host. Here, we identified a unique trimethyl lysine posttranslational modification of elongation factor Tu as a previously unrecognized bacterial ligand involved in early host colonization byP. aeruginosa. This modification is carried out by a novel methyltransferase, here named elongation factor Tu-modifying enzyme, resulting in a motif that is a structural mimic of the phosphorylcholine present in platelet-activating factor. This novel motif mediates bacterial attachment to airway respiratory cells through platelet-activating factor receptor and is a major virulence factor, expression of which is a prerequisite to pneumonia in a murine model of respiratory infection.IMPORTANCEPhosphorylcholine is an interesting molecule from the microbiological and immunological point of view. It is a crucial epitope for the virulence of many important human pathogens, modulates the host immune response, and is involved in a wide number of processes ranging from allergy to inflammation. Our current work identifies a novel bacterial surface epitope structurally and functionally similar to phosphorylcholine. This novel epitope is crucial for initial colonization of the respiratory tract byPseudomonas aeruginosaand for development of pneumonia. This opens up new targets for the development of novel drugs to preventP. aeruginosapneumonia, which is particularly important given the frequent emergence of multidrug-resistant strains.

scholarly journals Modeling Bacterial Population Growth from Stochastic Single-Cell Dynamics

2014 ◽  
Vol 80 (17) ◽  
pp. 5241-5253 ◽  
Author(s):  
Antonio A. Alonso ◽  
Ignacio Molina ◽  
Constantinos Theodoropoulos
Keyword(s):  
Differential Equation ◽  
Population Growth ◽  
Single Cell ◽  
Bacterial Cells ◽  
Estimation Of Parameters ◽  
Deterministic Models ◽  
Cell Dynamics ◽  
Bacterial Populations ◽  
Content Type ◽  
Number Of Individuals

ABSTRACTA few bacterial cells may be sufficient to produce a food-borne illness outbreak, provided that they are capable of adapting and proliferating on a food matrix. This is why any quantitative health risk assessment policy must incorporate methods to accurately predict the growth of bacterial populations from a small number of pathogens. In this aim, mathematical models have become a powerful tool. Unfortunately, at low cell concentrations, standard deterministic models fail to predict the fate of the population, essentially because the heterogeneity between individuals becomes relevant. In this work, a stochastic differential equation (SDE) model is proposed to describe variability within single-cell growth and division and to simulate population growth from a given initial number of individuals. We provide evidence of the model ability to explain the observed distributions of times to division, including the lag time produced by the adaptation to the environment, by comparing model predictions with experiments from the literature forEscherichia coli,Listeria innocua, andSalmonella enterica. The model is shown to accurately predict experimental growth population dynamics for both small and large microbial populations. The use of stochastic models for the estimation of parameters to successfully fit experimental data is a particularly challenging problem. For instance, if Monte Carlo methods are employed to model the required distributions of times to division, the parameter estimation problem can become numerically intractable. We overcame this limitation by converting the stochastic description to a partial differential equation (backward Kolmogorov) instead, which relates to the distribution of division times. Contrary to previous stochastic formulations based on random parameters, the present model is capable of explaining the variability observed in populations that result from the growth of a small number of initial cells as well as the lack of it compared to populations initiated by a larger number of individuals, where the random effects become negligible.

scholarly journals The physical boundaries of public goods cooperation between surface-attached bacterial cells

2017 ◽  
Author(s):  
Michael Weigert ◽  
Rolf Kümmerli
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Soft Tissue ◽  
Social Interactions ◽  
Single Cell ◽  
Fluorescent Microscopy ◽  
Social Consequences ◽  
Social Effects ◽  
Bacterial Cells ◽  
Soft Tissue Infections ◽  
Natural Conditions

AbstractBacteria secrete a variety of compounds important for nutrient scavenging, competition mediation and infection establishment. While there is a general consensus that secreted compounds can be shared and therefore have social consequences for the bacterial collective, we know little about the physical limits of such bacterial social interactions. Here, we address this issue by studying the sharing of iron-scavenging siderophores between surface-attached microcolonies of the bacterium Pseudomonas aeruginosa. Using single-cell fluorescent microscopy, we show that siderophores, secreted by producers, quickly reach non-producers within a range of 100 μm, and significantly boost their fitness. Producers in turn respond to variation in sharing efficiency by adjusting their pyoverdine investment levels. These social effects wane with larger cell-to-cell distances and on hard surfaces. Thus, our findings reveal the boundaries of compound sharing, and show that sharing is particularly relevant between nearby yet physically separated bacteria on soft surfaces, matching realistic natural conditions such as those encountered in soft tissue infections.

scholarly journals Pseudomonas aeruginosa ExsA Regulates a Metalloprotease, ImpA, That Inhibits Phagocytosis of Macrophages

2019 ◽  
Vol 87 (12) ◽  
Author(s):  
Zhenyang Tian ◽  
Sen Cheng ◽  
Bin Xia ◽  
Yongxin Jin ◽  
Fang Bai ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Critical Role ◽  
Surface Protein ◽  
Host Cells ◽  
Bacterial Cells ◽  
Mobility Shift ◽  
Content Type ◽  
Direct Binding ◽  
Mobility Shift Assay ◽  
Opportunistic Pathogenic

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogenic bacterium whose type III secretion system (T3SS) plays a critical role in acute infections. Translocation of the T3SS effectors into host cells induces cytotoxicity. In addition, the T3SS promotes the intracellular growth of P. aeruginosa during host infections. The T3SS regulon genes are regulated by an AraC-type regulator, ExsA. In this study, we found that an extracellular metalloprotease encoded by impA (PA0572) is under the regulation of ExsA. An ExsA consensus binding sequence was identified upstream of the impA gene, and direct binding of the site by ExsA was demonstrated via an electrophoretic mobility shift assay. We further demonstrate that secreted ImpA cleaves the macrophage surface protein CD44, which inhibits the phagocytosis of the bacterial cells by macrophages. Combined, our results reveal a novel ExsA-regulated virulence factor that cooperatively inhibits the functions of macrophages with the T3SS.

scholarly journals Social Cooperativity of Bacteria during Reversible Surface Attachment in Young Biofilms: a Quantitative Comparison of Pseudomonas aeruginosa PA14 and PAO1

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Calvin K. Lee ◽  
Jérémy Vachier ◽  
Jaime de Anda ◽  
Kun Zhao ◽  
Amy E. Baker ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stochastic Model ◽  
Bacterial Biofilm ◽  
Population Increase ◽  
Pivotal Phase ◽  
Surface Attachment ◽  
Content Type ◽  
Cellular Behavior ◽  
Bacterial Surface ◽  
Surface Sensing

ABSTRACT What are bacteria doing during “reversible attachment,” the period of transient surface attachment when they initially engage a surface, besides attaching themselves to the surface? Can an attaching cell help any other cell attach? If so, does it help all cells or employ a more selective strategy to help either nearby cells (spatial neighbors) or its progeny (temporal neighbors)? Using community tracking methods at the single-cell resolution, we suggest answers to these questions based on how reversible attachment progresses during surface sensing for Pseudomonas aeruginosa strains PAO1 and PA14. Although PAO1 and PA14 exhibit similar trends of surface cell population increase, they show unanticipated differences when cells are considered at the lineage level and interpreted using the quantitative framework of an exactly solvable stochastic model. Reversible attachment comprises two regimes of behavior, processive and nonprocessive, corresponding to whether cells of the lineage stay on the surface long enough to divide, or not, before detaching. Stark differences between PAO1 and PA14 in the processive regime of reversible attachment suggest the existence of two surface colonization strategies. PAO1 lineages commit quickly to a surface compared to PA14 lineages, with early c-di-GMP-mediated exopolysaccharide (EPS) production that can facilitate the attachment of neighbors. PA14 lineages modulate their motility via cyclic AMP (cAMP) and retain memory of the surface so that their progeny are primed for improved subsequent surface attachment. Based on the findings of previous studies, we propose that the differences between PAO1 and PA14 are potentially rooted in downstream differences between Wsp-based and Pil-Chp-based surface-sensing systems, respectively. IMPORTANCE The initial pivotal phase of bacterial biofilm formation known as reversible attachment, where cells undergo a period of transient surface attachment, is at once universal and poorly understood. What is more, although we know that reversible attachment culminates ultimately in irreversible attachment, it is not clear how reversible attachment progresses phenotypically, as bacterial surface-sensing circuits fundamentally alter cellular behavior. We analyze diverse observed bacterial behavior one family at a time (defined as a full lineage of cells related to one another by division) using a unifying stochastic model and show that our findings lead to insights on the time evolution of reversible attachment and the social cooperative dimension of surface attachment in PAO1 and PA14 strains.

Comparison of performances of flexible sensors on foil and paper for efficient bacterial concentration measurement

Sensor Review ◽  
2020 ◽  
Vol 40 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Tijana Kojic ◽  
Milan Radovanovic ◽  
Goran M. Stojanovic ◽  
Bojana Pivas ◽  
Deana Medic ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Resonant Frequency ◽  
Bacterial Cell ◽  
Physiological Saline ◽  
Bacterial Count ◽  
Cell Counting ◽  
Bacterial Cells ◽  
Content Type ◽  
Flexible Sensors

Purpose The purpose of this study was to develop flexible sensors for detection of different concentrations of bacteria, such as Pseudomonas aeruginosa and Staphylococcus aureus, in saline. Design/methodology/approach The sensors were fabricated using ink-jet printing technology and they consist of a pair of silver interdigitated electrodes printed on mechanically flexible substrates – foil and paper. In house measurement setup for testing and characterization of sensors has been developed. Structural, electrical and mechanical properties of flexible sensors have been determined and compared. Findings The characteristics of sensor – the resonant frequency as a function of different concentrations of each bacteria – are presented. The obtained results demonstrate different resonant frequencies for each dilution of Pseudomonas aeruginosa and Staphylococcus aureus in physiological saline. Research limitations/implications Both sensors showed accurate measurements of bacterial count, which can be achieved with detection of resonant frequency, and this is reflective of the number of bacterial cells within a sample. Practical implications The findings suggest that the newly developed method based on measuring resonant frequency corresponds well with bacterial cell count, thus establishing a new proof-of-concept that such method can have significant applications in bacterial cell counting that are economic and easily maintained. Social implications Fast, cost-effective, accurate and non-invasive method for detection of different bacteria from saline was developed. Originality/value For the first time, comparison between performances of flexible sensors on foil and paper for bacteria detection is demonstrated. Almost linear dependence between shift of resonant frequency of developed sensors and concentration of bacteria has been obtained.

scholarly journals A Single-Cell Genome for Thiovulum sp.

2012 ◽  
Vol 78 (24) ◽  
pp. 8555-8563 ◽  
Author(s):  
Ian P. G. Marshall ◽  
Paul C. Blainey ◽  
Alfred M. Spormann ◽  
Stephen R. Quake
Keyword(s):  
Single Cell ◽  
Multiple Displacement Amplification ◽  
Bacterial Cells ◽  
Content Type ◽  
Swimming Motility ◽  
Elkhorn Slough ◽  
Naturally Occurring ◽  
Wide Range ◽  
Cell Genome ◽  
Single Cell Genome

ABSTRACTWe determined a significant fraction of the genome sequence of a representative ofThiovulum, the uncultivated genus of colorless sulfurEpsilonproteobacteria, by analyzing the genome sequences of four individual cells collected from phototrophic mats from Elkhorn Slough, California. These cells were isolated utilizing a microfluidic laser-tweezing system, and their genomes were amplified by multiple-displacement amplification prior to sequencing.Thiovulumis a gradient bacterium found at oxic-anoxic marine interfaces and noted for its distinctive morphology and rapid swimming motility. The genomic sequences of the four individual cells were assembled into a composite genome consisting of 221 contigs covering 2.083 Mb including 2,162 genes. This single-cell genome represents a genomic view of the physiological capabilities of isolatedThiovulumcells.Thiovulumis the second-fastest bacterium ever observed, swimming at 615 μm/s, and this genome shows that this rapid swimming motility is a result of a standard flagellar machinery that has been extensively characterized in other bacteria. This suggests that standard flagella are capable of propelling bacterial cells at speeds much faster than typically thought. Analysis of the genome suggests that naturally occurringThiovulumpopulations are more diverse than previously recognized and that studies performed in the past probably address a wide range of unrecognized genotypic and phenotypic diversities ofThiovulum. The genome presented in this article provides a basis for future isolation-independent studies ofThiovulum, where single-cell and metagenomic tools can be used to differentiate between differentThiovulumgenotypes.

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