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Brazilian Journal of Microbiology :... Mar 2021Due to the severity of infections caused by P. aeruginosa and the limitations in treatment, it is necessary to find new therapeutic alternatives. Thus, the use of silver... (Review)
Review
Due to the severity of infections caused by P. aeruginosa and the limitations in treatment, it is necessary to find new therapeutic alternatives. Thus, the use of silver nanoparticles (AgNPs) is a viable alternative because of their potential actions in the combat of microorganisms, showing efficacy against Gram-positive and Gram-negative bacteria, including multidrug-resistant microorganisms (MDR). In this sense, the aim of this work was to conduct a literature review related to the antibacterial and antibiofilm activity of AgNPs against antibiotic-sensitive and multidrug-resistant Pseudomonas aeruginosa strains. The AgNPs are promising for future applications, which may match the clinical need for effective antibiotic therapy. The size of AgNPs is a crucial element to determine the therapeutic activity of nanoparticles, since smaller particles present a larger surface area of contact with the microorganism, affecting their vital functioning. AgNPs adhere to the cytoplasmic membrane and cell wall of microorganisms, causing disruption, penetrating the cell, interacting with cellular structures and biomolecules, and inducing the generation of reactive oxygen species and free radicals. Studies describe the antimicrobial activity of AgNPs at minimum inhibitory concentration (MIC) between 1 and 200 μg/mL against susceptible and MDR P. aeruginosa strains. These studies have also shown antibiofilm activity through disruption of biofilm structure, and oxidative stress, inhibiting biofilm growth at concentrations between 1 and 600 μg/mL of AgNPs. This study evidences the advance of AgNPs as an antibacterial and antibiofilm agent against Pseudomonas aeruginosa strains, demonstrating to be an extremely promising approach to the development of new antimicrobial systems.
Topics: Anti-Bacterial Agents; Biofilms; Drug Resistance, Multiple, Bacterial; Humans; Metal Nanoparticles; Microbial Sensitivity Tests; Pseudomonas aeruginosa; Silver
PubMed: 33231865
DOI: 10.1007/s42770-020-00406-x -
The Journal of General and Applied... Dec 2023The Pseudomonas aeruginosa strain, PAO1, has three putative γ-glutamyltranspeptidase (GGT) genes: ggtI, ggtII, and ggtIII. In this study, the expression of each of...
The Pseudomonas aeruginosa strain, PAO1, has three putative γ-glutamyltranspeptidase (GGT) genes: ggtI, ggtII, and ggtIII. In this study, the expression of each of these genes in P. aeruginosa PAO1 was analyzed, and the properties of the corresponding GGT proteins were investigated. This is the first report on biochemical characterization of GGT paralogs from Pseudomonas species. The crude extracts prepared from P. aeruginosa PAO1 exhibited hydrolysis and transpeptidation activities of 17.3 and 65.0 mU/mg, respectively, and the transcription of each gene to mRNA was confirmed by RT-PCR. All genes were cloned, and the expression plasmids constructed were introduced into an Escherichia coli expression system. Enzyme activity of the expressed protein of ggtI (PaGGTI) was not detected in the system, while the enzyme activities of the expressed proteins derived from ggtII and ggtIII (PaGGTII and PaGGTIII, respectively) were detected. However, the enzyme activity of PaGGTII was very low and easily decreased. PaGGTII with C-terminal his-tag (PaGGTII25aa) showed increased activity and stability, and the purified enzyme consisted of a large subunit of 40 kDa and a small subunit of 28 kDa. PaGGTIII consisted of a large subunit of 37 kDa and a small subunit of 24 kDa. The maximum hydrolysis and transpeptidation activities of PaGGTII25aa were obtained at 40ºC-50ºC, and the maximum hydrolysis and transpeptidation activities of PaGGTIII were obtained at 50ºC-60ºC. These enzymes retained approximately 80% of their hydrolysis and transpeptidation activities after incubation at 50ºC for 10 min, reflecting good stability. Both PaGGTII25aa and PaGGTIII showed higher activities of hydrolysis and transpeptidation in the alkali range than in the acidic range. However, they were highly stable at a wide pH range (5-10.5).
Topics: Humans; Pseudomonas aeruginosa; Pseudomonas; Pseudomonas Infections; Escherichia coli
PubMed: 36653156
DOI: 10.2323/jgam.2023.01.001 -
ACS Infectious Diseases Nov 2020Biofilms are one of the most challenging obstacles in bacterial infections. By providing protection against immune responses and antibiotic therapies, biofilms enable...
Biofilms are one of the most challenging obstacles in bacterial infections. By providing protection against immune responses and antibiotic therapies, biofilms enable chronic colonization and the development of antibiotic resistance. As previous clinical observations and studies have shown, traditional antibiotic therapy alone cannot effectively treat and eliminate biofilm forming infections due to the protection conferred by the biofilm. A new strategy specifically targeting biofilms must be developed. Here, we specifically target and bind to the PAO1 biofilm and elucidate the molecular mechanism behind the interaction between a glycan targeted polymer and biofilm using a continuous flow biofilm model. The incubation of biofilms with fluorescent glycan targeted polymers demonstrated strong and persistent interactions with the mannose-containing polymer even after 24 h of continuous flow. To evaluate the role of major biofilm proteins LecB and CdrA, loss of function experiments with knockout variants established the dual involvement of both proteins in mannose targeted polymer retention. These results identify a persistent and specific targeting strategy to the biofilm, emphasizing its potential value as a delivery strategy and encouraging further exploration of biofilm targeted delivery.
Topics: Bacterial Proteins; Biofilms; Mannose; Polymers; Pseudomonas aeruginosa
PubMed: 33074651
DOI: 10.1021/acsinfecdis.0c00407 -
Intensive Care Medicine Feb 2020
Topics: Drug Resistance, Bacterial; Drug Resistance, Multiple; Humans; Pseudomonas aeruginosa
PubMed: 31960069
DOI: 10.1007/s00134-019-05905-6 -
Cell Reports. Medicine Jun 2022Chronic wounds infected by Pseudomonas aeruginosa (Pa) are characterized by disease progression and increased mortality. We reveal Pf, a bacteriophage produced by Pa...
Chronic wounds infected by Pseudomonas aeruginosa (Pa) are characterized by disease progression and increased mortality. We reveal Pf, a bacteriophage produced by Pa that delays healing of chronically infected wounds in human subjects and animal models of disease. Interestingly, impairment of wound closure by Pf is independent of its effects on Pa pathogenesis. Rather, Pf impedes keratinocyte migration, which is essential for wound healing, through direct inhibition of CXCL1 signaling. In support of these findings, a prospective cohort study of 36 human patients with chronic Pa wound infections reveals that wounds infected with Pf-positive strains of Pa are more likely to progress in size compared with wounds infected with Pf-negative strains. Together, these data implicate Pf phage in the delayed wound healing associated with Pa infection through direct manipulation of mammalian cells. These findings suggest Pf may have potential as a biomarker and therapeutic target in chronic wounds.
Topics: Animals; Biofilms; Humans; Inovirus; Mammals; Prospective Studies; Pseudomonas; Pseudomonas Infections; Pseudomonas aeruginosa; Wound Healing; Wound Infection
PubMed: 35732145
DOI: 10.1016/j.xcrm.2022.100656 -
Journal of Medical Microbiology Jul 2020
Topics: Animals; Anti-Bacterial Agents; Computational Biology; Drug Resistance, Bacterial; Host-Pathogen Interactions; Humans; Pseudomonas; Pseudomonas Infections; Signal Transduction
PubMed: 32490791
DOI: 10.1099/jmm.0.001208 -
Microbial Biotechnology Jan 2020Over the past few decades, considerable interest has been shown in developing nano- and microcarriers with biocompatible and biodegradable materials for medical and...
Over the past few decades, considerable interest has been shown in developing nano- and microcarriers with biocompatible and biodegradable materials for medical and biotechnological applications. Microencapsulation is a technology capable of enhancing the survival rate of bacteria, providing stability in harsh environments. In the present paper, we developed a technology to encapsulate microorganisms within polyhydroxyalkanoate (PHA)-based microcapsules (MPs), employing a modified double emulsion solvent evaporation technique, with Pseudomonas putida KT2440 as a biotechnological model strain. The resulting MPs display a spherical morphology and an average particle size of 10 μm. The stability of the MPs was monitored under different conditions of storage and stress. The MPs remained stable for at least 24 days stored at 4°C in a water suspension. They exhibited greater tolerance to stress conditions; encapsulated cells remained viable for 2 h in alkaline solution and after 24 h of H O exposure at 10 and 20 mM. Results suggested the potential of MPs as a microcontainer of bacterial cells, even for biotechnological applications requiring high alkaline conditions and oxidative stress. We validated the potential applicability of the PHA-based microencapsulation method in other microorganisms by encapsulating the predatory bacterium Bdellovibrio bacteriovorus.
Topics: Polyhydroxyalkanoates; Pseudomonas putida
PubMed: 31714682
DOI: 10.1111/1751-7915.13492 -
Cell Reports. Medicine Oct 2023Nearly one-half of patients with cystic fibrosis (CF) carry the homozygous F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene but...
Nearly one-half of patients with cystic fibrosis (CF) carry the homozygous F508del mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene but exhibit variable lung function phenotypes. How adaptive immunity influences their lung function remains unclear, particularly the serological antibody responses to antigens from mucoid Pseudomonas in sera from patients with CF with varying lung function. Sera from patients with CF with reduced lung function show higher anti-outer membrane protein I (OprI) immunoglobulin G1 (IgG1) titers and greater antibody-mediated complement deposition. Induction of anti-OprI antibody isotypes with complement activity enhances lung inflammation in preclinical mouse models. This enhanced inflammation is absent in immunized Rag2 mice and is transferrable to unimmunized mice through sera. In a CF cohort undergoing treatment with elexacaftor-tezacaftor-ivacaftor, the declination in anti-OprI IgG1 titers is associated with lung function improvement and reduced hospitalizations. These findings suggest that antibody responses to specific Pseudomonas aeruginosa (PA) antigens worsen lung function in patients with CF.
Topics: Humans; Animals; Mice; Cystic Fibrosis; Pseudomonas; Pseudomonas aeruginosa; Lung; Immunoglobulin G
PubMed: 37852181
DOI: 10.1016/j.xcrm.2023.101210 -
Journal of Bacteriology Oct 2022Cells in microbial communities on surfaces live and divide in close proximity, which greatly enhances the potential for social interactions. Spatiogenetic structures are...
Cells in microbial communities on surfaces live and divide in close proximity, which greatly enhances the potential for social interactions. Spatiogenetic structures are manifested through competitive and cooperative interactions among the same and different genotypes within a shared space, and extracellular secretions appear to function dynamically at the forefront. A previous experimental evolution study utilizing Pseudomonas fluorescens Pf0-1 colonies demonstrated that diverse mutations in the gene were repeatedly and exclusively selected through the formation of a dominant spatial structure. RsmE's primary molecular function is translation repression, and its homologs regulate various social and virulence phenotypes. Pseudomonas spp. possess multiple paralogs of Rsm proteins, and RsmA, RsmE, and RsmI are the most prevalent. Here, we demonstrate that the production of a mucoid polymer and a biosurfactant are exclusively regulated through RsmE, contradicting the generalized notion of functional redundancy among the Rsm paralogs. Furthermore, we identified the biosurfactant as the cyclic lipopeptide gacamide A. Competition and microscopy analyses showed that the mucoid polymer is solely responsible for creating a space of low cellular density, which is shared exclusively by the same genotype. Gacamide A and other RsmE-regulated products appear to establish a physical boundary that prevents the encroachment of the competing genotype into the newly created space. Although cyclic lipopeptides and other biosurfactants are best known for their antimicrobial properties and reducing surface tension to promote the spreading of cells on various surfaces, they also appear to help define spatial structure formation within a dense community. In densely populated colonies of the bacterium Pseudomonas fluorescens Pf0-1, diverse mutations in the gene are naturally selected by solving the problem of overcrowding. Here, we show that RsmE-regulated secretions function together to create and protect space of low cell density. A biosurfactant generally promotes the spreading of bacterial cells on abiotic surfaces; however, it appears to function atypically within a crowded population by physically defining genotypic boundaries. Another significant finding is that these secretions are not regulated by RsmE's paralogs that share high sequence similarity. The experimental pipeline described in this study is highly tractable and should facilitate future studies to explore additional RsmE-regulated products and address why RsmE is functionally unique from its paralogs.
Topics: Pseudomonas fluorescens; Gene Expression Regulation, Bacterial; Bacterial Proteins; Pseudomonas; Peptides, Cyclic; Lipopeptides; Polymers
PubMed: 36165622
DOI: 10.1128/jb.00285-22 -
Corner Flows Induced by Surfactant-Producing Bacteria Bacillus subtilis and Pseudomonas fluorescens.Microbiology Spectrum Oct 2022A mechanistic understanding of bacterial spreading in soil, which has both air and water in angular pore spaces, is critical to control pathogenic contamination of soil...
A mechanistic understanding of bacterial spreading in soil, which has both air and water in angular pore spaces, is critical to control pathogenic contamination of soil and to design bioremediation projects. A recent study (J. Q. Yang, J. E. Sanfilippo, N. Abbasi, Z. Gitai, et al., Proc Natl Acad Sci U S A 118:e2111060118, 2021, https://doi.org/10.1073/pnas.2111060118) shows that Pseudomonas aeruginosa can self-generate flows along sharp corners by producing rhamnolipids, a type of biosurfactants that change the hydrophobicity of solid surfaces. We hypothesize that other types of biosurfactants and biosurfactant-producing bacteria can also generate corner flows. Here, we first demonstrate that rhamnolipids and surfactin, biosurfactants with different chemical structures, can generate corner flows. We identify the critical concentrations of these two biosurfactants to generate corner flow. Second, we demonstrate that two common soil bacteria, Pseudomonas fluorescens and Bacillus subtilis (which produce rhamnolipids and surfactin, respectively), can generate corner flows along sharp corners at the speed of several millimeters per hour. We further show that a surfactin-deficient mutant of B. subtilis cannot generate corner flow. Third, we show that, similar to the finding for P. aeruginosa, the critical corner angle for P. fluorescens and B. subtilis to generate corner flows can be predicted from classic corner flow theories. Finally, we show that the height of corner flows is limited by the roundness of corners. Our results suggest that biosurfactant-induced corner flows are prevalent in soil and should be considered in the modeling and prediction of bacterial spreading in soil. The critical biosurfactant concentrations we identify and the mathematical models we propose will provide a theoretical foundation for future predictions of bacterial spreading in soil. The spread of bacteria in soil is critical in soil biogeochemical cycles, soil and groundwater contamination, and the efficiency of soil-based bioremediation projects. However, the mechanistic understanding of bacterial spreading in soil remains incomplete due to a lack of direct observations. Here, we simulate confined spaces of hydrocarbon-covered soil using a transparent material with similar hydrophobicity and visualize the spread of two common soil bacteria, Pseudomonas fluorescens and Bacillus subtilis. We show that both bacteria can generate corner flows at the velocity of several millimeters per hour by producing biosurfactants, soap-like chemicals. We provide quantitative equations to predict the critical corner angle for bacterial corner flow and the maximum distance of the corner spreading. We anticipate that bacterial corner flow is prevalent because biosurfactant-producing bacteria and angular pores are common in soil. Our results will help improve predictions of bacterial spreading in soil and facilitate the design of soil-related bioremediation projects.
Topics: Bacillus subtilis; Surface-Active Agents; Pseudomonas fluorescens; Soaps; Soil Microbiology; Pseudomonas aeruginosa; Soil; Water
PubMed: 36214703
DOI: 10.1128/spectrum.03233-22