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Sample records for aeruginosa pseudomonas fluorescens

  1. Cyanide production by Pseudomonas fluorescens and Pseudomonas aeruginosa.

    PubMed Central

    Askeland, R A; Morrison, S M

    1983-01-01

    Of 200 water isolates screened, five strains of Pseudomonas fluorescens and one strain of Pseudomonas aeruginosa were cyanogenic. Maximum cyanogenesis by two strains of P. fluorescens in a defined growth medium occurred at 25 to 30 degrees C over a pH range of 6.6 to 8.9. Cyanide production per cell was optimum at 300 mM phosphate. A linear relationship was observed between cyanogenesis and the log of iron concentration over a range of 3 to 300 microM. The maximum rate of cyanide production occurred during the transition from exponential to stationary growth phase. Radioactive tracer experiments with [1-14C]glycine and [2-14C]glycine demonstrated that the cyanide carbon originates from the number 2 carbon of glycine for both P. fluorescens and P. aeruginosa. Cyanide production was not observed in raw industrial wastewater or in sterile wastewater inoculated with pure cultures of cyanogenic Pseudomonas strains. Cyanide was produced when wastewater was amended by the addition of components of the defined growth medium. PMID:6410989

  2. Cyanide production by Pseudomonas fluorescens and Pseudomonas aeruginosa.

    PubMed

    Askeland, R A; Morrison, S M

    1983-06-01

    Of 200 water isolates screened, five strains of Pseudomonas fluorescens and one strain of Pseudomonas aeruginosa were cyanogenic. Maximum cyanogenesis by two strains of P. fluorescens in a defined growth medium occurred at 25 to 30 degrees C over a pH range of 6.6 to 8.9. Cyanide production per cell was optimum at 300 mM phosphate. A linear relationship was observed between cyanogenesis and the log of iron concentration over a range of 3 to 300 microM. The maximum rate of cyanide production occurred during the transition from exponential to stationary growth phase. Radioactive tracer experiments with [1-14C]glycine and [2-14C]glycine demonstrated that the cyanide carbon originates from the number 2 carbon of glycine for both P. fluorescens and P. aeruginosa. Cyanide production was not observed in raw industrial wastewater or in sterile wastewater inoculated with pure cultures of cyanogenic Pseudomonas strains. Cyanide was produced when wastewater was amended by the addition of components of the defined growth medium.

  3. The evolutionary stability of cytochrome c-551 in Pseudomonas aeruginosa and Pseudomonas fluorescens biotype C

    PubMed Central

    Ambler, R. P.

    1974-01-01

    Cytochrome c-551 was prepared from nine different strains of Pseudomonas aeruginosa and six of Pseudomonas fluorescens biotype C, and their amino acid sequences were compared with the sequences previously determined for the cytochromes of type strains of each species. The standard of sequence examination was such that all single amino acid substitutions, delections or insertions ought to have been detected. Balanced double changes in sites in the same part of the sequence might have escaped detection. The standard of some of the quantitative amino acid analyses was not as high as would be required for the investigation of completely unknown sequences. Eight of the Ps. aeruginosa sequences could not be distinguished from the type sequence, whereas the ninth had a single amino acid substitution. The sequences from Ps. fluorescens biotype C were more varied, differing in from zero to four substitutions from the type sequence, with the most diverse sequences differing in seven positions. The results for Ps. aeruginosa are interpreted as evidence that neutral mutations are not responsible for much molecular evolution. The superficially paradoxical differences in the results for the two species are discussed. PMID:4362497

  4. Systematic investigations on the biodegradation and viscosity reduction of long chain hydrocarbons using Pseudomonas aeruginosa and Pseudomonas fluorescens.

    PubMed

    Sakthipriya, N; Doble, Mukesh; Sangwai, Jitendra S

    2016-03-01

    The use of microorganisms has been researched extensively for possible applications related to hydrocarbon degradation in the petroleum industry. However, attempts to improve the effect of microorganisms on the viscosity of hydrocarbons, which find potential use in the development of robust models for biodegradation, have been rarely documented. This study investigates the degradation of long chain hydrocarbons, such as hexadecane and eicosane using Pseudomonas fluorescens PMMD3 (P. fluorescens) and Pseudomonas aeruginosa CPCL (P. aeruginosa). P. aeruginosa used here is isolated from petroleum contaminated sediments and the P. fluorescens is from the coastal area, and both have hydrocarbon degrading genes. The degradation of hydrocarbons is studied using carbon profiling and reduction in viscosity pre- and post-degradation of hydrocarbons. The carbon profiling has been obtained using gas chromatography-mass spectroscopy (GC-MS), and Fourier transform infrared spectrometer (FTIR) results. GC-MS results have indicated an improved biodegradation of hydrocarbons by 77-93% in one day. The yield coefficients of biomass (YX/S) for P. aeruginosa and P. fluorescens using hexadecane as a carbon source are 1.35 and 0.81 g g(-1), and the corresponding values with eicosane are 0.84 and 0.88 g g(-1). The viscosity of hexadecane is reduced by the order of 53 and 47%, while that of eicosane was reduced by 53 and 65%, using P. aeruginosa and P. fluorescens, respectively. This study also presents information on the activity of enzymes responsible for the hydrocarbon degradation. Pseudomonas species have shown their use in potential applications for bioremediation, oil-spill treatment, and flow assurance. We believe that this study will also provide stringent tests for possible model development for the bioremediation of long chain paraffins suitable for oilfield applications.

  5. Survival and Plant Growth Promotion of Detergent-Adapted Pseudomonas fluorescens ANP15 and Pseudomonas aeruginosa 7NSK2.

    PubMed

    Devliegher, W; Arif, M; Verstraete, W

    1995-11-01

    Four detergents were tested as selective C sources for the plant growth-promoting rhizobacteria Pseudomonas aeruginosa 7NSK2 and Pseudomonas fluorescens ANP15. CO-720 (Igepal CO-720) or DOS (dioctyl sulfosuccinate), applied at 0.2% to the soil, increased the number of detergent-adapted, inoculated strains by almost 1.5 log units after 25 days, accounting for virtually the entire increase in total bacteria. The same dose of Tween 80 or N-laurylsarcosine, on the other hand, increased the indigenous populations by almost 2.5 log units, with only minor increases in the number of detergent-adapted inoculated strains. When CO-720 or DOS was initially supplied, the number of detergent-adapted 7NSK2 organisms was about 2 log units higher after 3 months of incubation than for the detergent-unadapted strain. This better survival resulted in a significantly higher root colonization of maize in a pot experiment with soil inoculation, with a significantly (P <= 0.05) higher shoot dry weight (18 to 33%). In a first field experiment with rhizosphere inoculation of 1-month-old maize plants, no effects on the height of two maize cultivars could be observed 1 month after inoculation. In a second field experiment, leaf and stem dry weights of yellow mustard and grass dry weight were increased in the treatments with seed and soil inoculation of the detergent-adapted 7NSK2 in combination with CO-720 application by, respectively, 7 to 8%, 19 to 23%, and 20 to 31%, although only the increases in grass dry weight were statistically significant at P <= 0.1. To some extent, 7NSK2 and DOS application also positively affected the mineral content of yellow mustard.

  6. Survival and Plant Growth Promotion of Detergent-Adapted Pseudomonas fluorescens ANP15 and Pseudomonas aeruginosa 7NSK2

    PubMed Central

    Devliegher, W.; Arif, M.; Verstraete, W.

    1995-01-01

    Four detergents were tested as selective C sources for the plant growth-promoting rhizobacteria Pseudomonas aeruginosa 7NSK2 and Pseudomonas fluorescens ANP15. CO-720 (Igepal CO-720) or DOS (dioctyl sulfosuccinate), applied at 0.2% to the soil, increased the number of detergent-adapted, inoculated strains by almost 1.5 log units after 25 days, accounting for virtually the entire increase in total bacteria. The same dose of Tween 80 or N-laurylsarcosine, on the other hand, increased the indigenous populations by almost 2.5 log units, with only minor increases in the number of detergent-adapted inoculated strains. When CO-720 or DOS was initially supplied, the number of detergent-adapted 7NSK2 organisms was about 2 log units higher after 3 months of incubation than for the detergent-unadapted strain. This better survival resulted in a significantly higher root colonization of maize in a pot experiment with soil inoculation, with a significantly (P <= 0.05) higher shoot dry weight (18 to 33%). In a first field experiment with rhizosphere inoculation of 1-month-old maize plants, no effects on the height of two maize cultivars could be observed 1 month after inoculation. In a second field experiment, leaf and stem dry weights of yellow mustard and grass dry weight were increased in the treatments with seed and soil inoculation of the detergent-adapted 7NSK2 in combination with CO-720 application by, respectively, 7 to 8%, 19 to 23%, and 20 to 31%, although only the increases in grass dry weight were statistically significant at P <= 0.1. To some extent, 7NSK2 and DOS application also positively affected the mineral content of yellow mustard. PMID:16535159

  7. Inner-membrane transporters for the siderophores pyochelin in Pseudomonas aeruginosa and enantio-pyochelin in Pseudomonas fluorescens display different enantioselectivities.

    PubMed

    Reimmann, Cornelia

    2012-05-01

    Iron uptake and transcriptional regulation by the enantiomeric siderophores pyochelin (Pch) and enantio-pyochelin (EPch) of Pseudomonas aeruginosa and Pseudomonas fluorescens, respectively, are stereospecific processes. The iron-loaded forms of Pch (ferriPch) and of EPch (ferriEPch) are recognized stereospecifically (i) at the outer membrane by the siderophore receptors FptA in P. aeruginosa and FetA in P. fluorescens and (ii) in the cytoplasm by the two AraC-type regulators PchR, which are activated by their cognate siderophore. Here, stereospecific siderophore recognition is shown to occur at the inner membrane also. In P. aeruginosa, translocation of ferriPch across the inner membrane is carried out by the single-subunit siderophore transporter FptX. In contrast, the uptake of ferriEPch into the cytoplasm of P. fluorescens was found to involve a classical periplasmic binding protein-dependent ABC transporter (FetCDE), which is encoded by the fetABCDEF operon. Expression of a translational fetA-gfp fusion was repressed by ferric ions, and activated by the cognate siderophore bound to PchR, thus resembling the analogous regulation of the P. aeruginosa ferriPch transport operon fptABCX. The inner-membrane transporters FetCDE and FptX were expressed in combination with either of the two siderophore receptors FetA and FptA in a siderophore-negative P. aeruginosa mutant deleted for the fptABCX operon. Growth tests conducted under iron limitation with ferriPch or ferriEPch as the iron source revealed that FptX was able to transport ferriPch as well as ferriEPch, whereas FetCDE specifically transported ferriEPch. Thus, stereospecific siderophore recognition occurs at the inner membrane by the FetCDE transporter.

  8. Expression of Fap amyloids in Pseudomonas aeruginosa, P. fluorescens, and P. putida results in aggregation and increased biofilm formation

    PubMed Central

    Dueholm, Morten S; Søndergaard, Mads T; Nilsson, Martin; Christiansen, Gunna; Stensballe, Allan; Overgaard, Michael T; Givskov, Michael; Tolker-Nielsen, Tim; Otzen, Daniel E; Nielsen, Per H

    2013-01-01

    The fap operon, encoding functional amyloids in Pseudomonas (Fap), is present in most pseudomonads, but so far the expression and importance for biofilm formation has only been investigated for P. fluorescens strain UK4. In this study, we demonstrate the capacity of P. aeruginosa PAO1, P. fluorescens Pf-5, and P. putida F1 to express Fap fibrils, and investigated the effect of Fap expression on aggregation and biofilm formation. The fap operon in all three Pseudomonas species conferred the ability to express Fap fibrils as shown using a recombinant approach. This Fap overexpression consistently resulted in highly aggregative phenotypes and in increased biofilm formation. Detailed biophysical investigations of purified fibrils confirmed FapC as the main fibril monomer and supported the role of FapB as a minor, nucleating constituent as also indicated by bioinformatic analysis. Bioinformatics analysis suggested FapF and FapD as a potential β-barrel membrane pore and protease, respectively. Manipulation of the fap operon showed that FapA affects monomer composition of the final amyloid fibril, and that FapB is an amyloid protein, probably a nucleator for FapC polymerization. Our study highlights the fap operon as a molecular machine for functional amyloid formation. PMID:23504942

  9. Influence of a Putative ECF Sigma Factor on Expression of the Major Outer Membrane Protein, OprF, in Pseudomonas aeruginosa and Pseudomonas fluorescens

    PubMed Central

    Brinkman, Fiona S. L.; Schoofs, Geert; Hancock, Robert E. W.; De Mot, René

    1999-01-01

    The gene encoding OprF, a major outer membrane protein in Pseudomonas species (formerly known as type 1 pseudomonads), was thought to be constitutively transcribed from a single sigma 70 promoter immediately upstream of the gene. We now report the identification of a novel putative ECF (extracytoplasmic function) sigma factor gene, sigX, located immediately upstream of oprF in both Pseudomonas aeruginosa PAO1 and Pseudomonas fluorescens OE 28.3 and show that disruption of this gene significantly reduces OprF expression. In P. aeruginosa, Northern analysis demonstrated that this reduction was a result of an effect on transcription of monocistronic oprF combined with a polar effect due to termination of a transcript containing sigX and oprF. Comparison of sigX-disrupted and wild-type cell transcripts by primer extension indicated that monocistronic transcription of oprF occurs from two overlapping promoters, one that is SigX-dependent and resembles ECF sigma factor promoters in its minus-35 region and another promoter that is independent of SigX and is analogous to the sigma 70-type promoter previously reported. Complementation of the P. aeruginosa sigX-disrupted mutant with plasmid-encoded OprF did not resolve the phenotypes associated with this mutant, which included a markedly reduced logarithmic-phase growth rate in rich medium (compared to that in minimal medium), further reduction of the growth rate in a low-osmolarity environment, secretion of an unidentified pigment, and increased sensitivity to the antibiotic imipenem. This indicates that SigX is involved in the regulation of other genes in P. aeruginosa. Disruption of the sigX gene in P. fluorescens also had an effect on the logarithmic-phase growth rate in rich medium. A conserved sigX gene was also identified in a Pseudomonas syringae isolate and six P. aeruginosa clinical isolates. Collectively, these data indicate that an ECF sigma factor plays a role in the regulation and expression of OprF and also

  10. 40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS; exemptions from the requirement of a tolerance... Tolerances § 180.1114 Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas...

  11. The Pseudomonas aeruginosa diguanylate cyclase GcbA, a homolog of P. fluorescens GcbA, promotes initial attachment to surfaces, but not biofilm formation, via regulation of motility.

    PubMed

    Petrova, Olga E; Cherny, Kathryn E; Sauer, Karin

    2014-08-01

    Cyclic di-GMP is a conserved signaling molecule regulating the transitions between motile and sessile modes of growth in a variety of bacterial species. Recent evidence suggests that Pseudomonas species harbor separate intracellular pools of c-di-GMP to control different phenotypic outputs associated with motility, attachment, and biofilm formation, with multiple diguanylate cyclases (DGCs) playing distinct roles in these processes, yet little is known about the potential conservation of functional DGCs across Pseudomonas species. In the present study, we demonstrate that the P. aeruginosa homolog of the P. fluorescens DGC GcbA involved in promoting biofilm formation via regulation of swimming motility likewise synthesizes c-di-GMP to regulate surface attachment via modulation of motility, however, without affecting subsequent biofilm formation. P. aeruginosa GcbA was found to regulate flagellum-driven motility by suppressing flagellar reversal rates in a manner independent of viscosity, surface hardness, and polysaccharide production. P. fluorescens GcbA was found to be functional in P. aeruginosa and was capable of restoring phenotypes associated with inactivation of gcbA in P. aeruginosa to wild-type levels. Motility and attachment of a gcbA mutant strain could be restored to wild-type levels via overexpression of the small regulatory RNA RsmZ. Furthermore, epistasis analysis revealed that while both contribute to the regulation of initial surface attachment and flagellum-driven motility, GcbA and the phosphodiesterase DipA act within different signaling networks to regulate these processes. Our findings expand the complexity of c-di-GMP signaling in the regulation of the motile-sessile switch by providing yet another potential link to the Gac/Rsm network and suggesting that distinct c-di-GMP-modulating signaling pathways can regulate a single phenotypic output.

  12. Adhesion of Pseudomonas fluorescens onto nanophase materials

    NASA Astrophysics Data System (ADS)

    Webster, Thomas J.; Tong, Zonghua; Liu, Jin; Banks, M. Katherine

    2005-07-01

    Nanobiotechnology is a growing area of research, primarily due to the potentially numerous applications of new synthetic nanomaterials in engineering/science. Although various definitions have been given for the word 'nanomaterials' by many different experts, the commonly accepted one refers to nanomaterials as those materials which possess grains, particles, fibres, or other constituent components that have one dimension specifically less than 100 nm. In biological applications, most of the research to date has focused on the interactions between mammalian cells and synthetic nanophase surfaces for the creation of better tissue engineering materials. Although mammalian cells have shown a definite positive response to nanophase materials, information on bacterial interactions with nanophase materials remains elusive. For this reason, this study was designed to assess the adhesion of Pseudomonas fluorescens on nanophase compared to conventional grain size alumina substrates. Results provide the first evidence of increased adhesion of Pseudomonas fluorescens on alumina with nanometre compared to conventional grain sizes. To understand more about the process, polymer (specifically, poly-lactic-co-glycolic acid or PLGA) casts were made of the conventional and nanostructured alumina surfaces. Results showed similar increased Pseudomonas fluorescens capture on PLGA casts of nanostructured compared to conventional alumina as on the alumina itself. For these reasons, a key material property shown to enhance bacterial adhesion was elucidated in this study for both polymers and ceramics: nanostructured surface features.

  13. Microbiology, Genomics, and Clinical Significance of the Pseudomonas fluorescens Species Complex, an Unappreciated Colonizer of Humans

    PubMed Central

    Scales, Brittan S.; Dickson, Robert P.; LiPuma, John J.

    2014-01-01

    SUMMARY Pseudomonas fluorescens is not generally considered a bacterial pathogen in humans; however, multiple culture-based and culture-independent studies have identified it at low levels in the indigenous microbiota of various body sites. With recent advances in comparative genomics, many isolates originally identified as the “species” P. fluorescens are now being reclassified as novel Pseudomonas species within the P. fluorescens “species complex.” Although most widely studied for its role in the soil and the rhizosphere, P. fluorescens possesses a number of functional traits that provide it with the capability to grow and thrive in mammalian hosts. While significantly less virulent than P. aeruginosa, P. fluorescens can cause bacteremia in humans, with most reported cases being attributable either to transfusion of contaminated blood products or to use of contaminated equipment associated with intravenous infusions. Although not suspected of being an etiologic agent of pulmonary disease, there are a number of reports identifying it in respiratory samples. There is also an intriguing association between P. fluorescens and human disease, in that approximately 50% of Crohn's disease patients develop serum antibodies to P. fluorescens. Altogether, these reports are beginning to highlight a far more common, intriguing, and potentially complex association between humans and P. fluorescens during health and disease. PMID:25278578

  14. Chronic Pseudomonas aeruginosa cervical osteomyelitis

    PubMed Central

    Meher, Sujeet Kumar; Jain, Harsh; Tripathy, Laxmi Narayan; Basu, Sunandan

    2016-01-01

    Pseudomonas aeruginosa is a rare cause of osteomyelitis of the cervical spine and is usually seen in the background of intravenous drug use and immunocompromised state. Very few cases of osteomyelitis of the cervical spine caused by pseudomonas aeruginosa have been reported in otherwise healthy patients. This is a case presentation of a young female, who in the absence of known risk factors for cervical osteomyelitis presented with progressively worsening neurological signs and symptoms. PMID:27891039

  15. Genomic Analysis of Secondary Metabolite Production by Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens is a diverse bacterial species known for its ubiquity in natural habitats and its production of secondary metabolites. The high degree of ecological and metabolic diversity represented in P. fluorescens is reflected in the genomic diversity displayed among strains. Certain st...

  16. Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM223

    PubMed Central

    Roquigny, Roxane; Arseneault, Tanya; Gadkar, Vijay J.; Novinscak, Amy

    2015-01-01

    Pseudomonas fluorescens LBUM223 is a plant growth-promoting rhizobacterium (PGPR) with biocontrol activity against various plant pathogens. It produces the antimicrobial metabolite phenazine-1-carboxylic acid, which is involved in the biocontrol of Streptomyces scabies, the causal agent of common scab of potato. Here, we report the complete genome sequence of P. fluorescens LBUM223. PMID:25953163

  17. Nitrite inhibition of denitrification by Pseudomonas fluorescens

    SciTech Connect

    Almeida, J.S.; Julio, S.M.; Reis, M.A.M. |

    1995-05-05

    Using a pure culture of Pseudomonas fluorescens as a model system nitrite inhibition of denitrification was studied. A mineral media with acetate and nitrate as sole electron donor and acceptor, respectively, was used. Results obtained in continuous stirred-tank reactors (CSTR) operated at pH values between 6.6 and 7.8 showed that growth inhibition depended only on the nitrite undissociated fraction concentration (nitrous acid). A mathematical model to describe this dependence is put forward. The maximum nitrous acid concentration compatible with cell growth and denitrification activity was found to be 66 {mu}g N/L. Denitrification activity was partially associated with growth, as described by the Luedeking-Piret equation. However, when the freshly inoculated reactor was operated discontinuously, nitrite accumulation caused growth uncoupling from denitrification activity. The authors suggest that these results can be interpreted considering that (a) nitrous acid acts as a proton uncoupler; and (b) cultures continuously exposed to nitrous acid prevent the uncoupling effect but not the growth inhibition. Examination of the growth dependence on nitrite concentration at pH 7.0 showed that adapted cultures (growth on CSTR) are less sensitive to nitrous acid inhibition than the ones cultivated in batch.

  18. Effect of temperature on Pseudomonas fluorescens chemotaxis.

    PubMed

    Lynch, W H

    1980-07-01

    The effects of temperature and attractants on chemotaxis in psychrotrophic Pseudomonas fluorescens were examined using the Adler capillary assay technique. Several organic acids, amino acids, and uronic acids were shown to be attractants, whereas glucose and its oxidation products, gluconate and 2-ketogluconate, elicited no detectable response. Chemotaxis toward many attractants was dependent on prior growth of the microorganism with these compounds. However, the organic acids, malate and succinate, caused strong chemotactic responses regardless of the carbon source used for growth of the bacteria. The temperature at which the cells were grown (30 or 5 degrees C) had no significant detectable effect on chemotaxis to the above attractants. The temperature at which the cells were assayed appeared to affect the rate but the extent of the chemotactic response, nor the concentration response curves. The ratios of the rate of accumulation of cells to the attractant malate were approximately 2, 4, and 1 at 30, 17, and 5 degrees C, respectively. Strong chemotactic responses were observed with cells assayed at temperatures approaching 0 degree C and appeared to be functional over a broad temperature range of 3 to 35 degrees C.

  19. [Pneumonia due to Pseudomonas aeruginosa].

    PubMed

    Vallés, Jordi; Mariscal, Dolors

    2005-12-01

    Pseudomonas aeruginosa is one of the leading causes of Gram-negative nosocomial pneumonia. It is the most common cause of ventilator-associated pneumonia and carries the highest mortality among hospital-acquired infections. P. aeruginosa produces a large number of toxins and surface components that make it especially virulent compared with other microorganisms. These include pili, flagella, membrane bound lipopolysaccharide, and secreted products such as exotoxins A, S and U, elastase, alkaline protease, cytotoxins and phospholipases. The most common mechanism of infection in mechanically ventilated patients is through aspiration of upper respiratory tract secretions previously colonized in the process of routine nursing care or via contaminated hands of hospital personnel. Intravenous therapy with an antipseudomonal regimen should be started immediately when P. aeruginosa pneumonia is suspected or confirmed. Empiric therapy with drugs active against P. aeruginosa should be started, especially in patients who have received previous antibiotics or present late-onset pneumonia.

  20. Pseudomonas fluorescens' view of the periodic table.

    PubMed

    Workentine, Matthew L; Harrison, Joe J; Stenroos, Pernilla U; Ceri, Howard; Turner, Raymond J

    2008-01-01

    Growth in a biofilm modulates microbial metal susceptibility, sometimes increasing the ability of microorganisms to withstand toxic metal species by several orders of magnitude. In this study, a high-throughput metal toxicity screen was initiated with the aim of correlating biological toxicity data in planktonic and biofilm cells to the physiochemical properties of metal ions. To this end, Pseudomonas fluorescens ATCC 13525 was grown in the Calgary Biofilm Device (CBD) and biofilms and planktonic cells of this microorganism were exposed to gradient arrays of different metal ions. These arrays included 44 different metals with representative compounds that spanned every group of the periodic table (except for the halogens and noble gases). The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum biofilm eradication concentration (MBEC) values were obtained after exposing the biofilms to metal ions for 4 h. Using these values, metal ion toxicity was correlated to the following ion-specific physicochemical parameters: standard reduction-oxidation potential, electronegativity, the solubility product of the corresponding metal-sulfide complex, the Pearson softness index, electron density and the covalent index. When the ions were grouped according to outer shell electron structure, we found that heavy metal ions gave the strongest correlations to these parameters and were more toxic on average than the other classes of the ions. Correlations were different for biofilms than for planktonic cells, indicating that chemical mechanisms of metal ion toxicity differ between the two modes of growth. We suggest that biofilms can specifically counter the toxic effects of certain physicochemical parameters, which may contribute to the increased ability of biofilms to withstand metal toxicity.

  1. Natriuretic peptides modify Pseudomonas fluorescens cytotoxicity by regulating cyclic nucleotides and modifying LPS structure

    PubMed Central

    Veron, Wilfried; Orange, Nicole; Feuilloley, Marc GJ; Lesouhaitier, Olivier

    2008-01-01

    Background Nervous tissues express various communication molecules including natriuretic peptides, i.e. Brain Natriuretic Peptide (BNP) and C-type Natriuretic Peptide (CNP). These molecules share structural similarities with cyclic antibacterial peptides. CNP and to a lesser extent BNP can modify the cytotoxicity of the opportunistic pathogen Pseudomonas aeruginosa. The psychrotrophic environmental species Pseudomonas fluorescens also binds to and kills neurons and glial cells, cell types that both produce natriuretic peptides. In the present study, we investigated the sensitivity of Pseudomonas fluorescens to natriuretic peptides and evaluated the distribution and variability of putative natriuretic peptide-dependent sensor systems in the Pseudomonas genus. Results Neither BNP nor CNP modified P. fluorescens MF37 growth or cultivability. However, pre-treatment of P. fluorescens MF37 with BNP or CNP provoked a decrease of the apoptotic effect of the bacterium on glial cells and an increase of its necrotic activity. By homology with eukaryotes, where natriuretic peptides act through receptors coupled to cyclases, we observed that cell-permeable stable analogues of cyclic AMP (dbcAMP) and cyclic GMP (8BcGMP) mimicked the effect of BNP and CNP on bacteria. Intra-bacterial concentrations of cAMP and cGMP were measured to study the involvement of bacterial cyclases in the regulation of P. fluorescens cytotoxicity by BNP or CNP. BNP provoked an increase (+49%) of the cAMP concentration in P. fluorescens, and CNP increased the intra-bacterial concentrations of cGMP (+136%). The effect of BNP and CNP on the virulence of P. fluorescens was independent of the potential of the bacteria to bind to glial cells. Conversely, LPS extracted from MF37 pre-treated with dbcAMP showed a higher necrotic activity than the LPS from untreated or 8BcGMP-pre-treated bacteria. Capillary electrophoresis analysis suggests that these different effects of the LPS may be due, at least in part, to

  2. Phosphate taxis in Pseudomonas aeruginosa.

    PubMed

    Kato, J; Ito, A; Nikata, T; Ohtake, H

    1992-08-01

    Pseudomonas aeruginosa was shown to be attracted to phosphate. The chemotactic response was induced by phosphate starvation. The specificity of chemoreceptors for phosphate was high so that no other tested phosphorus compounds elicited a chemotactic response as strong as that elicited by phosphate. Competition experiments showed that the chemoreceptors for phosphate appeared to be different from those for the common amino acids. Mutants constitutive for alkaline phosphatase showed the chemotactic response to phosphate regardless of whether the cells were starved for phosphate.

  3. 76 FR 52871 - Pseudomonas fluorescens Strain CL145A; Exemption From the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-24

    ... fluorescens Strain CL145A Pseudomonas fluorescens is ubiquitous in soil and water and is commonly associated... ubiquitous inhabitant of soil and water and is found on the surface and roots of a variety of plant types..., Pseudomonas fluorescens is considered ubiquitous in soil and water and is commonly associated with...

  4. Siderotyping of fluorescent pseudomonads: characterization of pyoverdines of Pseudomonas fluorescens and Pseudomonas putida strains from Antarctica.

    PubMed

    Meyer, J M; Stintzi, A; Coulanges, V; Shivaji, S; Voss, J A; Taraz, K; Budzikiewicz, H

    1998-11-01

    Five independent fluorescent pseudomonad isolates originating from Antarctica were analysed for their pyoverdine systems. A pyoverdine-related siderotyping, which involved pyoverdine-induced growth stimulation, pyoverdine-mediated iron uptake, pyoverdine analysis by electrophoresis and isoelectric focusing, revealed three different pyoverdine-related siderotypes among the five isolates. One siderotype, including Pseudomonas fluorescens 1W and P. fluorescens 10CW, was identical to that of P. fluorescens ATCC 13525. Two other strains, P. fluorescens 9AW and Pseudomonas putida 9BW, showed identical pyoverdine-related behaviour to each other, whereas the fifth strain, P. fluorescens 51W, had unique features compared to the other strains or to a set of 12 fluorescent Pseudomonas strains used as comparison material. Elucidation of the structure of the pyoverdines produced by the Antarctic strains supported the accuracy of the siderotyping methodology by confirming that pyoverdines from strains 1W and 10CW had the same structures as the P. fluorescens ATCC 13525 pyoverdine, whereas the 9AW and 9BW pyoverdines are probably identical with the pyoverdine of P. fluorescens strain 244. Pyoverdine from strain 51W appeared to be a novel pyoverdine since its structure was different from all previously established pyoverdine structures. Together with the conclusion that the Antarctic Pseudomonas strains have no special features at the level of their pyoverdines and pyoverdine-mediated iron metabolism compared to worldwide strains, the present work demonstrates that siderotyping provides a rapid means of screening for novel pyoverdines.

  5. Pseudomonas aeruginosa: breaking down barriers.

    PubMed

    Berube, Bryan J; Rangel, Stephanie M; Hauser, Alan R

    2016-02-01

    Many bacterial pathogens have evolved ingenious ways to escape from the lung during pneumonia to cause bacteremia. Unfortunately, the clinical consequences of this spread to the bloodstream are frequently dire. It is therefore important to understand the molecular mechanisms used by pathogens to breach the lung barrier. We have recently shown that Pseudomonas aeruginosa, one of the leading causes of hospital-acquired pneumonia, utilizes the type III secretion system effector ExoS to intoxicate pulmonary epithelial cells. Injection of these cells leads to localized disruption of the pulmonary-vascular barrier and dissemination of P. aeruginosa to the bloodstream. We put these data in the context of previous studies to provide a holistic model of P. aeruginosa dissemination from the lung. Finally, we compare P. aeruginosa dissemination to that of other bacteria to highlight the complexity of bacterial pneumonia. Although respiratory pathogens use distinct and intricate strategies to escape from the lungs, a thorough understanding of these processes can lay the foundation for new therapeutic approaches for bacterial pneumonia.

  6. Carbenicillin resistance of Pseudomonas aeruginosa.

    PubMed Central

    Rodríguez-Tebar, A; Rojo, F; Dámaso, D; Vázquez, D

    1982-01-01

    Four strains of Pseudomonas aeruginosa obtained from clinical isolates which are carbenicillin resistant were studied to find the cause(s) of resistance to this beta-lactam antibiotic. The electrophoresis patterns of the four strains (PH20610, PH20815, PH4011, and PH4301) were found to be different from those of a wild-type strain, P. aeruginosa NCTC 10662, and appeared to lack penicillin-binding protein 2. Affinity of other penicillin-binding proteins from strains PH20610 and PH20815 for carbenicillin seemed to be normal or slightly diminished. Electrophoretic patterns of penicillin-binding proteins from strains PH4011 and PH4301 had more profound differences, since the affinities of their penicillin-binding proteins 1a, 1b, and 4 for carbenicillin were decreased by nearly two orders of magnitude relative to the preparations from the wild-type strain. Kinetic studies on binding of carbenicillin to penicillin-binding proteins both in isolated membrane preparations and in intact cells revealed that carbenicillin penetration into resistant cells was a much slower process than in susceptible cells, suggesting that the outer envelope structures serve as an efficient barrier against carbenicillin entry into our P. aeruginosa strains from clinical isolates. PMID:6821456

  7. F'-plasmid transfer from Escherichia coli to Pseudomonas fluorescens.

    PubMed Central

    Mergeay, M; Gerits, J

    1978-01-01

    Various F' plasmids of Escherichia coli K-12 could be transferred into mutants of the soil strain 6.2, classified herein as a Pseudomonas fluorescens biotype IV. This strain was previously found to receive Flac plasmid (N. Datta and R.W. Hedges, J. Gen Microbiol. 70:453-460, 1972). ilv, leu, met, arg, and his auxotrophs were complemented by plasmids carrying isofunctional genes; trp mutants were not complemented or were very poorly complemented. The frequency of transfer was 10(-5). Subsequent transfer into other P. fluorescens recipients was of the same order of magnitude. Some transconjugants were unable to act as donors, and these did not lose the received information if subcultured on nonselective media. Use of F' plasmids helped to discriminate metabolic blocks in P. fluorescens. In particular, metA, metB, and argH mutants were so distinguished. In addition, F131 plasmid carrying the his operon and a supD mutation could partially relieve the auxotrophy of thr, ilv, and metA13 mutants, suggesting functional expression of E. coli tRNA in P. fluorescens. In P. fluorescens metA Rifr mutants carrying the F110 plasmid, which carried the E. coli metA gene and the E. coli rifs allele, sensitivity to rifampin was found to be dominant at least temporarily over resistance. This suggests interaction of E. coli and P. fluorescens subunits of RNA polymerase. his mutations were also complemented by composite P plasmids containing the his-nif region of Klebsiella pneumoniae (plasmids FN68 and RP41). nif expression could be detected by acetylene reduction in some his+ transconjugants. The frequency of transfer of these P plasmids was 5 X 10(-4). PMID:97267

  8. Engineering Pseudomonas fluorescens for Biodegradation of 2,4-Dinitrotoluene†

    PubMed Central

    Monti, Mariela R.; Smania, Andrea M.; Fabro, Georgina; Alvarez, María E.; Argaraña, Carlos E.

    2005-01-01

    Using the genes encoding the 2,4-dinitrotoluene degradation pathway enzymes, the nonpathogenic psychrotolerant rhizobacterium Pseudomonas fluorescens ATCC 17400 was genetically modified for degradation of this priority pollutant. First, a recombinant strain designated MP was constructed by conjugative transfer from Burkholderia sp. strain DNT of the pJS1 megaplasmid, which contains the dnt genes for 2,4-dinitrotoluene degradation. This strain was able to grow on 2,4-dinitrotoluene as the sole source of carbon, nitrogen, and energy at levels equivalent to those of Burkholderia sp. strain DNT. Nevertheless, loss of the 2,4-dinitrotoluene degradative phenotype was observed for strains carrying pJS1. The introduction of dnt genes into the P.fluorescens ATCC 17400 chromosome, using a suicide chromosomal integration Tn5-based delivery plasmid system, generated a degrading strain that was stable for a long time, which was designated RE. This strain was able to use 2,4-dinitrotoluene as a sole nitrogen source and to completely degrade this compound as a cosubstrate. Furthermore, P. fluorescens RE, but not Burkholderia sp. strain DNT, was capable of degrading 2,4-dinitrotoluene at temperatures as low as 10°C. Finally, the presence of P. fluorescens RE in soils containing levels of 2,4-dinitrotoluene lethal to plants significantly decreased the toxic effects of this nitro compound on Arabidopsis thaliana growth. Using synthetic medium culture, P. fluorescens RE was found to be nontoxic for A.thaliana and Nicotiana tabacum, whereas under these conditions Burkholderia sp. strain DNT inhibited A.thaliana seed germination and was lethal to plants. These features reinforce the advantageous environmental robustness of P. fluorescens RE compared with Burkholderia sp. strain DNT. PMID:16332883

  9. Lethality and Developmental Delay of Drosophila melanogaster Following Ingestion of Selected Pseudomonas fluorescens Strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens secretes antimicrobial compounds that promote plant health and provide protection from pathogens. We used a non-invasive feeding assay to study the toxicity of P. fluorescens strains Pf0-1, SBW25, and Pf-5 to Drosophila melanogaster. The three strains of P. fluorescens varie...

  10. Pseudomonas aeruginosa Population Structure Revisited

    PubMed Central

    Pirnay, Jean-Paul; Bilocq, Florence; Pot, Bruno; Cornelis, Pierre; Zizi, Martin; Van Eldere, Johan; Deschaght, Pieter; Vaneechoutte, Mario; Jennes, Serge; Pitt, Tyrone; De Vos, Daniel

    2009-01-01

    At present there are strong indications that Pseudomonas aeruginosa exhibits an epidemic population structure; clinical isolates are indistinguishable from environmental isolates, and they do not exhibit a specific (disease) habitat selection. However, some important issues, such as the worldwide emergence of highly transmissible P. aeruginosa clones among cystic fibrosis (CF) patients and the spread and persistence of multidrug resistant (MDR) strains in hospital wards with high antibiotic pressure, remain contentious. To further investigate the population structure of P. aeruginosa, eight parameters were analyzed and combined for 328 unrelated isolates, collected over the last 125 years from 69 localities in 30 countries on five continents, from diverse clinical (human and animal) and environmental habitats. The analysed parameters were: i) O serotype, ii) Fluorescent Amplified-Fragment Length Polymorphism (FALFP) pattern, nucleotide sequences of outer membrane protein genes, iii) oprI, iv) oprL, v) oprD, vi) pyoverdine receptor gene profile (fpvA type and fpvB prevalence), and prevalence of vii) exoenzyme genes exoS and exoU and viii) group I pilin glycosyltransferase gene tfpO. These traits were combined and analysed using biological data analysis software and visualized in the form of a minimum spanning tree (MST). We revealed a network of relationships between all analyzed parameters and non-congruence between experiments. At the same time we observed several conserved clones, characterized by an almost identical data set. These observations confirm the nonclonal epidemic population structure of P. aeruginosa, a superficially clonal structure with frequent recombinations, in which occasionally highly successful epidemic clones arise. One of these clones is the renown and widespread MDR serotype O12 clone. On the other hand, we found no evidence for a widespread CF transmissible clone. All but one of the 43 analysed CF strains belonged to a ubiquitous P

  11. Antibiotic Conditioned Growth Medium of Pseudomonas Aeruginosa

    ERIC Educational Resources Information Center

    Benathen, Isaiah A.; Cazeau, Barbara; Joseph, Njeri

    2004-01-01

    A simple method to study the consequences of bacterial antibiosis after interspecific competition between microorganisms is presented. Common microorganisms are used as the test organisms and Pseudomonas aeruginosa are used as the source of the inhibitor agents.

  12. Colonizing ability of Pseudomonas fluorescens 2112, among collections of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens spp. in pea rhizosphere.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens 2112, isolated in Korea as an indigenous antagonistic bacteria, can produce 2,4-diacetylphloroglucinol (2,4-DAPG) and the siderophore pyoveridin2112 for the control of Phytophthora blight of red-pepper. P. fluorescens 2112 was classified into a new genotype C among the 17 gen...

  13. Characterization of a phage-like pyocin from the plant growth-promoting rhizobacterium Pseudomonas fluorescens SF4c.

    PubMed

    Fischer, Sonia; Godino, Agustina; Quesada, José Miguel; Cordero, Paula; Jofré, Edgardo; Mori, Gladys; Espinosa-Urgel, Manuel

    2012-06-01

    R-type and F-type pyocins are high-molecular-mass bacteriocins produced by Pseudomonas aeruginosa that resemble bacteriophage tails. They contain no head structures and no DNA, and are used as defence systems. In this report, we show that Pseudomonas fluorescens SF4c, a strain isolated from the wheat rhizosphere, produces a high-molecular-mass bacteriocin which inhibits the growth of closely related bacteria. A mutant deficient in production of this antimicrobial compound was obtained by transposon mutagenesis. Sequence analysis revealed that the transposon had disrupted a gene that we have named ptm, since it is homologous to that encoding phage tape-measure protein in P. fluorescens Pf0-1, a gene belonging to a prophage similar to phage-like pyocin from P. aeruginosa PAO1. In addition, we have identified genes from the SF4c pyocin cluster that encode a lytic system and regulatory genes. We constructed a non-polar ptm mutant of P. fluorescens SF4c. Heterologous complementation of this mutation restored the production of bacteriocin. Real-time PCR was used to analyse the expression of pyocin under different stress conditions. Bacteriocin was upregulated by mitomycin C, UV light and hydrogen peroxide, and was downregulated by saline stress. This report constitutes, to our knowledge, the first genetic characterization of a phage tail-like bacteriocin in a rhizosphere Pseudomonas strain.

  14. 40 CFR 180.1200 - Pseudomonas fluorescens strain PRA-25; temporary exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Pseudomonas fluorescens strain PRA-25... RESIDUES IN FOOD Exemptions From Tolerances § 180.1200 Pseudomonas fluorescens strain PRA-25; temporary... established for residues of the microbial pesticide, pseudomonas fluorescens strain PRA-25 when used on...

  15. Factors Affecting Zebra Mussel Kill by the Bacterium Pseudomonas fluorescens

    SciTech Connect

    Daniel P. Molloy

    2004-02-24

    The specific purpose of this research project was to identify factors that affect zebra mussel kill by the bacterium Pseudomonas fluorescens. Test results obtained during this three-year project identified the following key variables as affecting mussel kill: treatment concentration, treatment duration, mussel siphoning activity, dissolved oxygen concentration, water temperature, and naturally suspended particle load. Using this latter information, the project culminated in a series of pipe tests which achieved high mussel kill inside power plants under once-through conditions using service water in artificial pipes.

  16. Combined inoculation of Pseudomonas fluorescens and Trichoderma harzianum for enhancing plant growth of vanilla (Vanilla planifolia).

    PubMed

    Sandheep, A R; Asok, A K; Jisha, M S

    2013-06-15

    This study was conducted to evaluate the plant growth promoting efficiency of combined inoculation of rhizobacteria on Vanilla plants. Based on the in vitro performance of indigenous Trichoderma spp. and Pseudomonas spp., four effective antagonists were selected and screened under greenhouse experiment for their growth enhancement potential. The maximum percentage of growth enhancement were observed in the combination of Trichoderma harzianum with Pseudomonas fluorescens treatment followed by Pseudomonas fluorescens, Trichoderma harzianum, Pseudomonas putida and Trichoderma virens, respectively in decreasing order. Combined inoculation of Trichoderma harzianum and Pseudomonas fluorescens registered the maximum length of vine (82.88 cm), highest number of leaves (26.67/plant), recorded the highest fresh weight of shoots (61.54 g plant(-1)), fresh weight of roots (4.46 g plant(-1)) and dry weight of shoot (4.56 g plant(-1)) where as the highest dry weight of roots (2.0806 g plant(-1)) were achieved with treatments of Pseudomonas fluorescens. Among the inoculated strains, combined inoculation of Trichoderma harzianum and Pseudomonas fluorescens recorded the maximum nitrogen uptake (61.28 mg plant(-1)) followed by the combined inoculation of Trichoderma harzianum (std) and Pseudomonas fluorescens (std) (55.03 mg plant(-1)) and the highest phosphorus uptake (38.80 mg plant(-1)) was recorded in dual inoculation of Trichoderma harzianum and Pseudomonas fluorescens.

  17. Foam Separation of Pseudomonas fluorescens and Bacillus subtilis var. niger

    PubMed Central

    Grieves, R. B.; Wang, S. L.

    1967-01-01

    An experimental investigation established the effect of the presence of inorganic salts on the foam separation of Pseudomonas fluorescens and of Bacillus subtilis var. niger (B. globigii) from aqueous suspension by use of a cationic surfactant. For P. fluorescens, 5.0 μeq/ml of NaCl, KCl, Na2SO4, K2SO4, CaCl2, CaSO4, MgCl2, or MgSO4 produced increases in the cell concentration in the residual suspension (not carried into the foam) from 2.9 × 105 up to 1.6 × 106 to 2.8 × 107 cells per milliliter (initial suspensions contain from 3.3 × 107 to 4.8 × 107 cells per milliliter). The exceptional influence of magnesium was overcome by bringing the cells into contact first with the surfactant and then the salt. For B. subtilis, the presence of 5.0 μeq/ml of any of the eight salts increased the residual cell concentration by one order of magnitude from 1.2 × 104 to about 4.0 × 105 cells per milliliter. This occurred regardless of the sequence of contact as long as the surfactant contact period was sufficient. The presence of salts increased collapsed foam volumes with P. fluorescens and decreased collapsed foam volumes with B. subtilis. PMID:4961933

  18. Genomic and Genetic Diversity within the Pseudomonas fluorescens Complex

    PubMed Central

    Garrido-Sanz, Daniel; Meier-Kolthoff, Jan P.; Göker, Markus; Martín, Marta; Rivilla, Rafael; Redondo-Nieto, Miguel

    2016-01-01

    The Pseudomonas fluorescens complex includes Pseudomonas strains that have been taxonomically assigned to more than fifty different species, many of which have been described as plant growth-promoting rhizobacteria (PGPR) with potential applications in biocontrol and biofertilization. So far the phylogeny of this complex has been analyzed according to phenotypic traits, 16S rDNA, MLSA and inferred by whole-genome analysis. However, since most of the type strains have not been fully sequenced and new species are frequently described, correlation between taxonomy and phylogenomic analysis is missing. In recent years, the genomes of a large number of strains have been sequenced, showing important genomic heterogeneity and providing information suitable for genomic studies that are important to understand the genomic and genetic diversity shown by strains of this complex. Based on MLSA and several whole-genome sequence-based analyses of 93 sequenced strains, we have divided the P. fluorescens complex into eight phylogenomic groups that agree with previous works based on type strains. Digital DDH (dDDH) identified 69 species and 75 subspecies within the 93 genomes. The eight groups corresponded to clustering with a threshold of 31.8% dDDH, in full agreement with our MLSA. The Average Nucleotide Identity (ANI) approach showed inconsistencies regarding the assignment to species and to the eight groups. The small core genome of 1,334 CDSs and the large pan-genome of 30,848 CDSs, show the large diversity and genetic heterogeneity of the P. fluorescens complex. However, a low number of strains were enough to explain most of the CDSs diversity at core and strain-specific genomic fractions. Finally, the identification and analysis of group-specific genome and the screening for distinctive characters revealed a phylogenomic distribution of traits among the groups that provided insights into biocontrol and bioremediation applications as well as their role as PGPR. PMID:26915094

  19. Small RNA-dependent expression of secondary metabolism is controlled by Krebs cycle function in Pseudomonas fluorescens.

    PubMed

    Takeuchi, Kasumi; Kiefer, Patrick; Reimmann, Cornelia; Keel, Christoph; Dubuis, Christophe; Rolli, Joëlle; Vorholt, Julia A; Haas, Dieter

    2009-12-11

    Pseudomonas fluorescens CHA0, an antagonist of phytopathogenic fungi in the rhizosphere of crop plants, elaborates and excretes several secondary metabolites with antibiotic properties. Their synthesis depends on three small RNAs (RsmX, RsmY, and RsmZ), whose expression is positively controlled by the GacS-GacA two-component system at high cell population densities. To find regulatory links between primary and secondary metabolism in P. fluorescens and in the related species Pseudomonas aeruginosa, we searched for null mutations that affected central carbon metabolism as well as the expression of rsmY-gfp and rsmZ-gfp reporter constructs but without slowing down the growth rate in rich media. Mutation in the pycAB genes (for pyruvate carboxylase) led to down-regulation of rsmXYZ and secondary metabolism, whereas mutation in fumA (for a fumarase isoenzyme) resulted in up-regulation of the three small RNAs and secondary metabolism in the absence of detectable nutrient limitation. These effects required the GacS sensor kinase but not the accessory sensors RetS and LadS. An analysis of intracellular metabolites in P. fluorescens revealed a strong positive correlation between small RNA expression and the pools of 2-oxoglutarate, succinate, and fumarate. We conclude that Krebs cycle intermediates (already known to control GacA-dependent virulence factors in P. aeruginosa) exert a critical trigger function in secondary metabolism via the expression of GacA-dependent small RNAs.

  20. The Pseudomonas aeruginosa oxyvinylglycine L-2-amino-4-methoxy-trans-3-butenoic acid inhibits growth of Erwinia amylovora and acts as a weak seed germination-arrest factor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid (AMB) is demonstrated to share biological activities with 4-formylaminooxyvinylglycine, a related molecule produced by Pseudomonas fluorescens WH6. We found that culture filtrates of a P. aeruginosa strain overproduc...

  1. High pressure inactivation of Pseudomonas in black truffle - comparison with Pseudomonas fluorescens in tryptone soya broth

    NASA Astrophysics Data System (ADS)

    Ballestra, Patricia; Verret, Catherine; Cruz, Christian; Largeteau, Alain; Demazeau, Gerard; El Moueffak, Abdelhamid

    2010-03-01

    Pseudomonas is one of the most common genera in black Perigord truffle. Its inactivation by high pressure (100-500 MPa/10 min) applied on truffles at sub-zero or low temperatures was studied and compared with those of Pseudomonas fluorescens in tryptone soya broth. Pressurization of truffles at 300 MPa/4 °C reduced the bacterial count of Pseudomonas by 5.3 log cycles. Higher pressures of 400 or 500 MPa, at 4 °C or 20 °C, allowed us to slightly increase the level of destruction to the value of ca. 6.5 log cycles but did not permit us to completely inactivate Pseudomonas. The results showed a residual charge of about 10 CFU/g. Pressure-shift freezing of truffles, which consists in applying a pressure of 200 MPa/-18 °C for 10 min and then quickly releasing this pressure to induce freezing, reduced the population of Pseudomonas by 3.3 log cycles. The level of inactivation was higher than those obtained with conventional freezing. Endogenous Pseudomonas in truffle was shown to be more resistant to high pressure treatments than P. fluorescens used for inoculation of broths.

  2. Boolean Models of Biosurfactants Production in Pseudomonas fluorescens

    PubMed Central

    Richard, Adrien; Rossignol, Gaelle; Comet, Jean-Paul; Bernot, Gilles; Guespin-Michel, Jannine; Merieau, Annabelle

    2012-01-01

    Cyclolipopeptides (CLPs) are biosurfactants produced by numerous Pseudomonas fluorescens strains. CLP production is known to be regulated at least by the GacA/GacS two-component pathway, but the full regulatory network is yet largely unknown. In the clinical strain MFN1032, CLP production is abolished by a mutation in the phospholipase C gene () and not restored by complementation. Their production is also subject to phenotypic variation. We used a modelling approach with Boolean networks, which takes into account all these observations concerning CLP production without any assumption on the topology of the considered network. Intensive computation yielded numerous models that satisfy these properties. All models minimizing the number of components point to a bistability in CLP production, which requires the presence of a yet unknown key self-inducible regulator. Furthermore, all suggest that a set of yet unexplained phenotypic variants might also be due to this epigenetic switch. The simplest of these Boolean networks was used to propose a biological regulatory network for CLP production. This modelling approach has allowed a possible regulation to be unravelled and an unusual behaviour of CLP production in P. fluorescens to be explained. PMID:22303435

  3. The Accessory Genome of Pseudomonas aeruginosa

    PubMed Central

    Kung, Vanderlene L.; Ozer, Egon A.; Hauser, Alan R.

    2010-01-01

    Summary: Pseudomonas aeruginosa strains exhibit significant variability in pathogenicity and ecological flexibility. Such interstrain differences reflect the dynamic nature of the P. aeruginosa genome, which is composed of a relatively invariable “core genome” and a highly variable “accessory genome.” Here we review the major classes of genetic elements comprising the P. aeruginosa accessory genome and highlight emerging themes in the acquisition and functional importance of these elements. Although the precise phenotypes endowed by the majority of the P. aeruginosa accessory genome have yet to be determined, rapid progress is being made, and a clearer understanding of the role of the P. aeruginosa accessory genome in ecology and infection is emerging. PMID:21119020

  4. Genomics-Guided Discovery of Traits Contributing to Interactions of Pseudomonas fluorescens with Other Organisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens is a diverse bacterial species known for its ubiquity in natural habitats and the production of structurally diverse, bioactive secondary metabolites. The high degree of ecological and metabolic diversity represented in P. fluorescens is reflected in the genomic diversity di...

  5. Three Strains of Pseudomonas fluorescens Exhibit Differential Toxicity Against Drosophila melanogaster

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three strains of Pseudomonas fluorescens were tested for toxicity to Drosophila melanogaster in an insect feeding assay. Insect eggs were placed on the surface of a non-nutritive agar plate supplemented with a food source that was non-inoculated or inoculated with P. fluorescens Pf0-1, SBW25, or Pf-...

  6. Genome Sequence of the Banana Plant Growth-Promoting Rhizobacterium Pseudomonas fluorescens PS006

    PubMed Central

    Gamez, Rocío M.; Rodríguez, Fernando; Ramírez, Sandra; Gómez, Yolanda; Agarwala, Richa; Landsman, David

    2016-01-01

    Pseudomonas fluorescens is a well-known plant growth-promoting rhizobacterium (PGPR). We report here the first whole-genome sequence of PGPR P. fluorescens evaluated in Colombian banana plants. The genome sequences contains genes involved in plant growth and defense, including bacteriocins, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, and genes that provide resistance to toxic compounds. PMID:27151797

  7. Pseudomonas fluorescens SBW25 produces furanomycin, a non-proteinogenic amino acid with selective antimicrobial properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens is an opportunistic, plant-associated ' –proteobacterium that occurs throughout terrestrial ecosystems and is commonly isolated from the surface of plant roots and leaves. Strains of P. fluorescens are physiologically and ecologically diverse, and genomic data from multiple s...

  8. Effect of retS gene on antibiotics production in Pseudomonas fluorescens FD6.

    PubMed

    Zhang, Qingxia; Xiao, Qi; Xu, Jingyou; Tong, Yunhui; Wen, Jia; Chen, Xijun; Wei, Lihui

    2015-11-01

    A hybrid sensor kinase termed RetS (regulator of exopolysaccharide and Type III secretion) controls expression of numerous genes in Pseudomonas aeruginosa. To investigate the function of RetS in P. fluorescens FD6, the retS gene was disrupted. Genetic inactivation of retS resulted in enhanced production of 2, 4-diacetylphloroglucinol, pyrrolnitrin, and pyoluteorin. The retS mutant also exhibited significant increase in phlA-lacZ, prnA-lacZ, and pltA-lacZ transcription levels, influencing expression levels of the small regulatory RNAs RsmX and RsmZ. In the gacSretS double mutant, all the phenotypic changes caused by the retS deletion were reversed to the level of gacS single mutant. Furthermore, the retS mutation drastically elevated biofilm formation and improved the colonization ability of strain FD6 on wheat rhizospheres. Based on these results, we proposed that RetS negatively controlled the production of antibiotics through the Gac/Rsm pathway in P. fluorescens FD6.

  9. Identification of Pseudomonas fluorescens Chemotaxis Sensory Proteins for Malate, Succinate, and Fumarate, and Their Involvement in Root Colonization

    PubMed Central

    Oku, Shota; Komatsu, Ayaka; Nakashimada, Yutaka; Tajima, Takahisa; Kato, Junichi

    2014-01-01

    Pseudomonas fluorescens Pf0-1 exhibited chemotactic responses to l-malate, succinate, and fumarate. We constructed a plasmid library of 37 methyl-accepting chemotaxis protein (MCP) genes of P. fluorescens Pf0-1. To identify a MCP for l-malate, the plasmid library was screened using the PA2652 mutant of Pseudomonas aeruginosa PAO1, a mutant defective in chemotaxis to l-malate. The introduction of Pfl01_0728 and Pfl01_3768 genes restored the ability of the PA2652 mutant to respond to l-malate. The Pfl01_0728 and Pfl01_3768 double mutant of P. fluorescens Pf0-1 showed no response to l-malate or succinate, while the Pfl01_0728 single mutant did not respond to fumarate. These results indicated that Pfl01_0728 and Pfl01_3768 were the major MCPs for l-malate and succinate, and Pfl01_0728 was also a major MCP for fumarate. The Pfl01_0728 and Pfl01_3768 double mutant unexpectedly exhibited stronger responses toward the tomato root exudate and amino acids such as proline, asparagine, methionine, and phenylalanine than those of the wild-type strain. The ctaA, ctaB, ctaC (genes of the major MCPs for amino acids), Pfl01_0728, and Pfl01_3768 quintuple mutant of P. fluorescens Pf0-1 was less competitive than the ctaA ctaB ctaC triple mutant in competitive root colonization, suggesting that chemotaxis to l-malate, succinate, and/or fumarate was involved in tomato root colonization by P. fluorescens Pf0-1. PMID:25491753

  10. Occurrence of Pseudomonas aeruginosa in Kuwait soil.

    PubMed

    Al-Saleh, Esmaeil; Akbar, Abrar

    2015-02-01

    Environmentally ubiquitous bacteria such as Pseudomonas aeruginosa evolved mechanisms to adapt and prevail under diverse conditions. In the current investigation, strains of P. aeruginosa demonstrating high rates of crude oil utilization and tolerance to high concentrations of heavy metals were found in both crude oil-contaminated and uncontaminated sites in Kuwait, and were dominant in the contaminated sites. The incidence of P. aeruginosa in tested soils implies the definitive pattern of crude oil contamination in the selection of the bacterial population in petroleum-contaminated sites in Kuwait. Surprisingly, the unculturable P. aeruginosa in different soil samples showed significant high similarity coefficients based on 16S-RFLP analyses, implying that the unculturable fraction of existing bacterial population in environmental samples is more stable and, hence, reliable for phylogenetic studies compared to the culturable bacteria.

  11. Osmoregulation in Pseudomonas aeruginosa under hyperosmotic shock.

    PubMed

    Velasco, R; Burgoa, R; Flores, E; Hernández, E; Villa, A; Vaca, S

    1995-01-01

    Pseudomonas aeruginosa PAO1 strain was found to be able to tolerate 700 mM NaCl. 0.5 mM of the osmoprotectant betaine restablished the growth of this strain in 1200 mM NaCl. Intracellular K+ and glutamate concentrations of P. aeruginosa PAO1 after an hyperosmotic shock (400 mM NaCl) showed a permanent increase. Adition of betaine (0.5 mM) to the medium with NaCl had an inhibitory effect on the intracellular accumulation of glutamate. The results indicate that P. aeruginosa PAO1 resists high NaCl concentrations, K+ accumulation and glutamate synthesis probably being the first mechanisms involved in adaptation to osmotic stress. Also is is demonstrated that betaine modulates intracellular glutamate levels in osmotically stressed P. aeruginosa PAO1.

  12. Survival of rifampin-resistant mutants of Pseudomonas fluorescens and Pseudomonas putida in soil systems.

    PubMed Central

    Compeau, G; Al-Achi, B J; Platsouka, E; Levy, S B

    1988-01-01

    The fate of spontaneous chromosomal rifampin-resistant (Rifr) mutants of Pseudomonas putida and Pseudomonas fluorescens in sterile and live organic soil from which they were isolated was studied. In sterile native-soil assays, a Rifr mutant of P. putida showed no decrease in competitive fitness when compared with the wild-type parent. However, mutants of P. fluorescens were of two general categories. Group 1 showed no difference from the wild type in terms of growth rate, competitive fitness, and membrane protein composition. Group 2 showed a slower growth rate in both minimal and enriched media and an altered membrane protein profile. These mutants also demonstrated decreased competitive fitness compared with the wild-type strain. In live soil, the Rifr P. putida strain persisted throughout the 38-day test period with a decay rate of 0.7 log10 CFU/g of soil per 10 days. A group 1 Rifr P. fluorescens mutant maintained its inoculated titer for 7 to 10 days and then decayed at a rate of 0.2 to 0.4 log10 CFU/g of soil per 10 days. A group 2 Rifr P. fluorescens mutant remained at its titer for 1 to 5 days before decaying at a two- to threefold-faster rate. These findings indicate that rifampin resistance may not be an innocuous mutation in some pseudomonads and that marked strains should be compared with wild-type parents before being used as monitors of parental strain survival. Colonization of sterile soil with either the wild-type or mutant strain precluded normal colonization of the second added strain.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:3144244

  13. Pseudomonas aeruginosa Dose-Response and Bathing Water Infection

    EPA Science Inventory

    Pseudomonas aeruginosa is the most commonly identified opportunistic pathogen associated with pool acquired bather disease. To better understand why this microorganism poses this protracted problem we recently appraised P. aeruginosa pool risk management. Much is known about the ...

  14. Siderophore cooperation of the bacterium Pseudomonas fluorescens in soil.

    PubMed

    Luján, Adela M; Gómez, Pedro; Buckling, Angus

    2015-02-01

    While social interactions play an important role for the evolution of bacterial siderophore production in vitro, the extent to which siderophore production is a social trait in natural populations is less clear. Here, we demonstrate that siderophores act as public goods in a natural physical environment of Pseudomonas fluorescens: soil-based compost. We show that monocultures of siderophore producers grow better than non-producers in soil, but non-producers can exploit others' siderophores, as shown by non-producers' ability to invade populations of producers when rare. Despite this rare advantage, non-producers were unable to outcompete producers, suggesting that producers and non-producers may stably coexist in soil. Such coexistence is predicted to arise from the spatial structure associated with soil, and this is supported by increased fitness of non-producers when grown in a shaken soil-water mix. Our results suggest that both producers and non-producers should be observed in soil, as has been observed in marine environments and in clinical populations.

  15. The effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on model bacterial strains and isolates from industrial wastewater.

    PubMed

    Vasileva-Tonkova, Evgenia; Sotirova, Anna; Galabova, Danka

    2011-02-01

    In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant, depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain Bacillus subtilis 168. The growth and protein release of model Gram (-) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium. Rhamnolipid biosurfactant at the used concentrations supported the growth of some slow growing on hexadecane bacterial isolates, members of the microbial community. Changes in cell surface hydrophobicity and permeability of some Gram (+) and Gram (-) isolates in the presence of rhamnolipid biosurfactant were followed in experiments in vitro. It was found that bacterial cells treated with biosurfactant became more or less hydrophobic than untreated cells depending on individual characteristics and abilities of the strains. For all treated strains, an increase in the amount of released protein was observed with increasing the amount of biosurfactant, probably due to increased cell permeability as a result of changes in the organization of cell surface structures. The results obtained could contribute to clarify the relationships between members of the microbial community as well as suggest the efficiency of surface properties of rhamnolipid biosurfactant from Pseudomonas fluorescens making it potentially applicable in bioremediation of hydrocarbon-polluted environments.

  16. [Development and relations of Fusarium culmorum and Pseudomonas fluorescens in soil].

    PubMed

    Strunnikova, O K; Shakhnazarova, V Iu; Vishnevskaia, N A; Chebotar', V K; Tikhonovich, I A

    2007-01-01

    The development of Fusarium culmorum and Pseudomonas fluorescens in soil, and the relations between them, were studied using membrane filters containing the fungus, the bacterium, or both microorganisms; the filters were incubated in soil. F. culmorum was identified by indirect immunofluorescence: the GUS-labeled strain was used to visualize P. fluorescens. It was found that F. culmorum introduced in soil can develop as a saprotroph, with the formation of mycelium, macroconidia, and a small amount of chlamydospores. Introduction of glucose and cellulose resulted in increased density of the F. culmorum mycelium and macroconidia. P. fluorescens suppressed development of F. culmorum mycelium in soil but stimulated formation of fungal chlamydospores. Decreased mycelial density in the presence of P. fluorescens was more pronounced in unsupplemented soil and less pronounced when glucose or cellulose was intiodaced. F. culmorum had no significant effect on P. fluorescens growth in soil.

  17. Developing an international Pseudomonas aeruginosa reference panel.

    PubMed

    De Soyza, Anthony; Hall, Amanda J; Mahenthiralingam, Eshwar; Drevinek, Pavel; Kaca, Wieslaw; Drulis-Kawa, Zuzanna; Stoitsova, Stoyanka R; Toth, Veronika; Coenye, Tom; Zlosnik, James E A; Burns, Jane L; Sá-Correia, Isabel; De Vos, Daniel; Pirnay, Jean-Paul; Kidd, Timothy J; Reid, David; Manos, Jim; Klockgether, Jens; Wiehlmann, Lutz; Tümmler, Burkhard; McClean, Siobhán; Winstanley, Craig

    2013-12-01

    Pseudomonas aeruginosa is a major opportunistic pathogen in cystic fibrosis (CF) patients and causes a wide range of infections among other susceptible populations. Its inherent resistance to many antimicrobials also makes it difficult to treat infections with this pathogen. Recent evidence has highlighted the diversity of this species, yet despite this, the majority of studies on virulence and pathogenesis focus on a small number of strains. There is a pressing need for a P. aeruginosa reference panel to harmonize and coordinate the collective efforts of the P. aeruginosa research community. We have collated a panel of 43 P. aeruginosa strains that reflects the organism's diversity. In addition to the commonly studied clones, this panel includes transmissible strains, sequential CF isolates, strains with specific virulence characteristics, and strains that represent serotype, genotype or geographic diversity. This focussed panel of P. aeruginosa isolates will help accelerate and consolidate the discovery of virulence determinants, improve our understanding of the pathogenesis of infections caused by this pathogen, and provide the community with a valuable resource for the testing of novel therapeutic agents.

  18. Type III Secretion System and Virulence Markers Highlight Similarities and Differences between Human- and Plant-Associated Pseudomonads Related to Pseudomonas fluorescens and P. putida

    PubMed Central

    Mazurier, Sylvie; Merieau, Annabelle; Bergeau, Dorian; Decoin, Victorien; Sperandio, Daniel; Crépin, Alexandre; Barbey, Corinne; Jeannot, Katy; Vicré-Gibouin, Maïté; Plésiat, Patrick

    2015-01-01

    Pseudomonas fluorescens is commonly considered a saprophytic rhizobacterium devoid of pathogenic potential. Nevertheless, the recurrent isolation of strains from clinical human cases could indicate the emergence of novel strains originating from the rhizosphere reservoir, which could be particularly resistant to the immune system and clinical treatment. The importance of type three secretion systems (T3SSs) in the related Pseudomonas aeruginosa nosocomial species and the occurrence of this secretion system in plant-associated P. fluorescens raise the question of whether clinical isolates may also harbor T3SSs. In this study, isolates associated with clinical infections and identified in hospitals as belonging to P. fluorescens were compared with fluorescent pseudomonads harboring T3SSs isolated from plants. Bacterial isolates were tested for (i) their genetic relationships based on their 16S rRNA phylogeny, (ii) the presence of T3SS genes by PCR, and (iii) their infectious potential on animals and plants under environmental or physiological temperature conditions. Two groups of bacteria were delineated among the clinical isolates. The first group encompassed thermotolerant (41°C) isolates from patients suffering from blood infections; these isolates were finally found to not belong to P. fluorescens but were closely related and harbored highly conserved T3SS genes belonging to the Ysc-T3SS family, like the T3SSs from P. aeruginosa. The second group encompassed isolates from patients suffering from cystic fibrosis; these isolates belonged to P. fluorescens and harbored T3SS genes belonging to the Hrp1-T3SS family found commonly in plant-associated P. fluorescens. PMID:25636837

  19. Anaerobic growth and cyanide synthesis of Pseudomonas aeruginosa depend on anr, a regulatory gene homologous with fnr of Escherichia coli.

    PubMed

    Zimmermann, A; Reimmann, C; Galimand, M; Haas, D

    1991-06-01

    Anaerobic growth of Pseudomonas aeruginosa on nitrate or arginine requires the anr gene, which codes for a positive control element (ANR) capable of functionally complementing an fnr mutation in Escherichia coli. The anr gene was sequenced; it showed 51% identity with the fnr gene at the amino acid sequence level. Four cysteine residues known to be essential in the FNR protein are conserved in ANR. The anr gene product (deduced Mr 27,129) was visualized by the maxicell method and migrated like a 32 kDa protein in gel electrophoresis under denaturing conditions. An anr mutant of P. aeruginosa constructed by gene replacement was defective in nitrate respiration, arginine deiminase activity, and hydrogen cyanide biosynthesis, underscoring the diverse metabolic functions of ANR during oxygen limitation. Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas syringae, and Pseudomonas mendocina all had a functional analogue of ANR, indicating that similar anaerobic control mechanisms exist in these bacteria.

  20. Pseudomonas Aeruginosa: Resistance to the Max

    PubMed Central

    Poole, Keith

    2011-01-01

    Pseudomonas aeruginosa is intrinsically resistant to a variety of antimicrobials and can develop resistance during anti-pseudomonal chemotherapy both of which compromise treatment of infections caused by this organism. Resistance to multiple classes of antimicrobials (multidrug resistance) in particular is increasingly common in P. aeruginosa, with a number of reports of pan-resistant isolates treatable with a single agent, colistin. Acquired resistance in this organism is multifactorial and attributable to chromosomal mutations and the acquisition of resistance genes via horizontal gene transfer. Mutational changes impacting resistance include upregulation of multidrug efflux systems to promote antimicrobial expulsion, derepression of ampC, AmpC alterations that expand the enzyme's substrate specificity (i.e., extended-spectrum AmpC), alterations to outer membrane permeability to limit antimicrobial entry and alterations to antimicrobial targets. Acquired mechanisms contributing to resistance in P. aeruginosa include β-lactamases, notably the extended-spectrum β-lactamases and the carbapenemases that hydrolyze most β-lactams, aminoglycoside-modifying enzymes, and 16S rRNA methylases that provide high-level pan-aminoglycoside resistance. The organism's propensity to grow in vivo as antimicrobial-tolerant biofilms and the occurrence of hypermutator strains that yield antimicrobial resistant mutants at higher frequency also compromise anti-pseudomonal chemotherapy. With limited therapeutic options and increasing resistance will the untreatable P. aeruginosa infection soon be upon us? PMID:21747788

  1. Spaceflight Effects on Virulence of Pseudomonas Aeruginosa

    NASA Astrophysics Data System (ADS)

    Broadway, S.; Goins, T.; Crandell, C.; Richards, C.; Patel, M.; Pyle, B.

    2008-06-01

    Pseudomonas aeruginosa is an opportunistic pathogen found in the environment. It is known to infect the immunocompromised. The organism has about 25 virulence genes that play different roles in disease processes. Several exotoxin proteins may be produced, including ExoA, ExoS, ExoT and ExoY, and other virulence factors. In spaceflight, possible increased expression of P. aeruginosa virulence proteins could increase health risks for spaceflight crews who experience decreased immunity. Cultures of P. aeruginosa strains PA01 and PA103 grown on orbit on Shuttle Endeavour flight STS-123 vs. static ground controls were used for analysis. The production of ETA was quantitated using an ELISA procedure. Results showed that while flight cultures of PA103 produced slightly more ETA than corresponding ground controls, the opposite was found for PA01. While it appears that spaceflight has little effect on ETA, stimulation of other virulence factors could cause increased virulence of this organism in space flight. Similar increased virulence in spaceflight has been observed for other bacteria. This is important because astronauts may be more susceptible to opportunistic pathogens including P. aeruginosa.

  2. Pseudomonas aeruginosa ventilator-associated pneumonia management.

    PubMed

    Ramírez-Estrada, Sergio; Borgatta, Bárbara; Rello, Jordi

    2016-01-01

    Ventilator-associated pneumonia is the most common infection in intensive care unit patients associated with high morbidity rates and elevated economic costs; Pseudomonas aeruginosa is one of the most frequent bacteria linked with this entity, with a high attributable mortality despite adequate treatment that is increased in the presence of multiresistant strains, a situation that is becoming more common in intensive care units. In this manuscript, we review the current management of ventilator-associated pneumonia due to P. aeruginosa, the most recent antipseudomonal agents, and new adjunctive therapies that are shifting the way we treat these infections. We support early initiation of broad-spectrum antipseudomonal antibiotics in present, followed by culture-guided monotherapy de-escalation when susceptibilities are available. Future management should be directed at blocking virulence; the role of alternative strategies such as new antibiotics, nebulized treatments, and vaccines is promising.

  3. Pseudomonas aeruginosa ventilator-associated pneumonia management

    PubMed Central

    Ramírez-Estrada, Sergio; Borgatta, Bárbara; Rello, Jordi

    2016-01-01

    Ventilator-associated pneumonia is the most common infection in intensive care unit patients associated with high morbidity rates and elevated economic costs; Pseudomonas aeruginosa is one of the most frequent bacteria linked with this entity, with a high attributable mortality despite adequate treatment that is increased in the presence of multiresistant strains, a situation that is becoming more common in intensive care units. In this manuscript, we review the current management of ventilator-associated pneumonia due to P. aeruginosa, the most recent antipseudomonal agents, and new adjunctive therapies that are shifting the way we treat these infections. We support early initiation of broad-spectrum antipseudomonal antibiotics in present, followed by culture-guided monotherapy de-escalation when susceptibilities are available. Future management should be directed at blocking virulence; the role of alternative strategies such as new antibiotics, nebulized treatments, and vaccines is promising. PMID:26855594

  4. Risk assessment of Pseudomonas aeruginosa in water.

    PubMed

    Mena, Kristina D; Gerba, Charles P

    2009-01-01

    from ingesting P. aeruginosa in drinking water is low. The risk is slightly higher if the subject is taking an antibiotic resisted by P. aeruginosa. The fact that individuals on ampicillin are more susceptible to Pseudomonas gastrointestinal infection probably results from suppression of normal intestinal flora, which would allow Pseudomonas to colonize. The process of estimating risk was significantly constrained because of the absence of specific (quantitative) occurrence data for Pseudomonas. Sensitivity analysis shows that the greatest source of variability/uncertainty in the risk assessment is from the density distribution in the exposure rather than the dose-response or water consumption distributions. In summary, two routes appear to carry the greatest health risks from contacting water contaminated with P. aeruginosa (1) skin exposure in hot tubs and (2) lung exposure from inhaling aerosols.

  5. Oxidation of 1-Tetradecene by Pseudomonas aeruginosa

    PubMed Central

    Markovetz, A. J.; Klug, M. J.; Forney, F. W.

    1967-01-01

    Pseudomonas aeruginosa strain Sol 20 was grown on 1-tetradecene as sole carbon source, and a vinyl-unsaturated 14-carbon monocarboxylic acid, 13-tetradecenoic acid, was identified from culture fluid. This acid was not produced when n-tetradecane served as substrate for growth. Oxidation of the methyl group represents one method of attack on the 1-alkene by this organism. Tentative identification of 2-tetradecanol indicates that an attack on the double bond is also occurring. α, ω-Dienes would not support growth. PMID:4962057

  6. A Type VI Secretion System Is Involved in Pseudomonas fluorescens Bacterial Competition

    PubMed Central

    Decoin, Victorien; Barbey, Corinne; Bergeau, Dorian; Latour, Xavier; Feuilloley, Marc G. J.; Orange, Nicole; Merieau, Annabelle

    2014-01-01

    Protein secretion systems are crucial mediators of bacterial interactions with other organisms. Among them, the type VI secretion system (T6SS) is widespread in Gram-negative bacteria and appears to inject toxins into competitor bacteria and/or eukaryotic cells. Major human pathogens, such as Vibrio cholerae, Burkholderia and Pseudomonas aeruginosa, express T6SSs. Bacteria prevent self-intoxication by their own T6SS toxins by producing immunity proteins, which interact with the cognate toxins. We describe here an environmental P. fluorescens strain, MFE01, displaying an uncommon oversecretion of Hcp (hemolysin-coregulated protein) and VgrG (valine-glycine repeat protein G) into the culture medium. These proteins are characteristic components of a functional T6SS. The aim of this study was to attribute a role to this energy-consuming overexpression of the T6SS. The genome of MFE01 contains at least two hcp genes (hcp1 and hcp2), suggesting that there may be two putative T6SS clusters. Phenotypic studies have shown that MFE01 is avirulent against various eukaryotic cell models (amebas, plant or animal cell models), but has antibacterial activity against a wide range of competitor bacteria, including rhizobacteria and clinical bacteria. Depending on the prey cell, mutagenesis of the hcp2 gene in MFE01 abolishes or reduces this antibacterial killing activity. Moreover, the introduction of T6SS immunity proteins from S. marcescens, which is not killed by MFE01, protects E. coli against MFE01 killing. These findings suggest that the protein encoded by hcp2 is involved in the killing activity of MFE01 mediated by effectors of the T6SS targeting the peptidoglycan of Gram-negative bacteria. Our results indicate that MFE01 can protect potato tubers against Pectobacterium atrosepticum, which causes tuber soft rot. Pseudomonas fluorescens is often described as a major PGPR (plant growth-promoting rhizobacterium), and our results suggest that there may be a connection between

  7. A type VI secretion system is involved in Pseudomonas fluorescens bacterial competition.

    PubMed

    Decoin, Victorien; Barbey, Corinne; Bergeau, Dorian; Latour, Xavier; Feuilloley, Marc G J; Orange, Nicole; Merieau, Annabelle

    2014-01-01

    Protein secretion systems are crucial mediators of bacterial interactions with other organisms. Among them, the type VI secretion system (T6SS) is widespread in Gram-negative bacteria and appears to inject toxins into competitor bacteria and/or eukaryotic cells. Major human pathogens, such as Vibrio cholerae, Burkholderia and Pseudomonas aeruginosa, express T6SSs. Bacteria prevent self-intoxication by their own T6SS toxins by producing immunity proteins, which interact with the cognate toxins. We describe here an environmental P. fluorescens strain, MFE01, displaying an uncommon oversecretion of Hcp (hemolysin-coregulated protein) and VgrG (valine-glycine repeat protein G) into the culture medium. These proteins are characteristic components of a functional T6SS. The aim of this study was to attribute a role to this energy-consuming overexpression of the T6SS. The genome of MFE01 contains at least two hcp genes (hcp1 and hcp2), suggesting that there may be two putative T6SS clusters. Phenotypic studies have shown that MFE01 is avirulent against various eukaryotic cell models (amebas, plant or animal cell models), but has antibacterial activity against a wide range of competitor bacteria, including rhizobacteria and clinical bacteria. Depending on the prey cell, mutagenesis of the hcp2 gene in MFE01 abolishes or reduces this antibacterial killing activity. Moreover, the introduction of T6SS immunity proteins from S. marcescens, which is not killed by MFE01, protects E. coli against MFE01 killing. These findings suggest that the protein encoded by hcp2 is involved in the killing activity of MFE01 mediated by effectors of the T6SS targeting the peptidoglycan of Gram-negative bacteria. Our results indicate that MFE01 can protect potato tubers against Pectobacterium atrosepticum, which causes tuber soft rot. Pseudomonas fluorescens is often described as a major PGPR (plant growth-promoting rhizobacterium), and our results suggest that there may be a connection between

  8. Biotransformation of myrcene by Pseudomonas aeruginosa

    PubMed Central

    2011-01-01

    Background Dihydrolinalool and terpineol are sources of fragrances that provide a unique volatile terpenoid alcohol of low toxicity and thus are widely used in the perfumery industry, in folk medicine, and in aromatherapy. They are important chemical constituents of the essential oil of many plants. Previous studies have concerned the biotransformation of limonene by Pseudomonas putida. The objective of this research was to study biotransformation of myrcene by Pseudomonas aeruginosa. The culture preparation was done using such variables as different microbial methods and incubation periods to obtain maximum cells of P. aeruginosa for myrcene biotransformation. Results It was found that myrcene was converted to dihydrolinalool and 2,6-dimethyloctane in high percentages. The biotransformation products were identified by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet (UV) analysis, gas chromatography (GC), and gas chromatography-mass spectroscopy (GC-MS). Comparison of the different incubation times showed that 3 days was more effective, the major products being 2,6-dimethyloctane (90.0%) and α-terpineol (7.7%) and comprising 97.7%. In contrast, the main compounds derived for an incubation time of 1.5 days were dihydrolinalool (79.5%) and 2,6-dimethyloctane (9.3%), with a total yield of 88.8%. PMID:21609445

  9. Switching Catalysis from Hydrolysis to Perhydrolysis in Pseudomonas fluorescens Esterase

    SciTech Connect

    Yin, D.; Bernhardt, P; Morley, K; Jiang, Y; Cheeseman, J; Purpero, V; Schrag, J; Kazlauskas, R

    2010-01-01

    Many serine hydrolases catalyze perhydrolysis, the reversible formation of peracids from carboxylic acids and hydrogen peroxide. Recently, we showed that a single amino acid substitution in the alcohol binding pocket, L29P, in Pseudomonas fluorescens (SIK WI) aryl esterase (PFE) increased the specificity constant of PFE for peracetic acid formation >100-fold [Bernhardt et al. (2005) Angew. Chem., Int. Ed. 44, 2742]. In this paper, we extend this work to address the three following questions. First, what is the molecular basis of the increase in perhydrolysis activity? We previously proposed that the L29P substitution creates a hydrogen bond between the enzyme and hydrogen peroxide in the transition state. Here we report two X-ray structures of L29P PFE that support this proposal. Both structures show a main chain carbonyl oxygen closer to the active site serine as expected. One structure further shows acetate in the active site in an orientation consistent with reaction by an acyl-enzyme mechanism. We also detected an acyl-enzyme intermediate in the hydrolysis of {var_epsilon}-caprolactone by mass spectrometry. Second, can we further increase perhydrolysis activity? We discovered that the reverse reaction, hydrolysis of peracetic acid to acetic acid and hydrogen peroxide, occurs at nearly the diffusion limited rate. Since the reverse reaction cannot increase further, neither can the forward reaction. Consistent with this prediction, two variants with additional amino acid substitutions showed 2-fold higher k{sub cat}, but K{sub m} also increased so the specificity constant, k{sub cat}/K{sub m}, remained similar. Third, how does the L29P substitution change the esterase activity? Ester hydrolysis decreased for most esters (75-fold for ethyl acetate) but not for methyl esters. In contrast, L29P PFE catalyzed hydrolysis of {var_epsilon}-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the

  10. Phosphorylcholine Phosphatase: A Peculiar Enzyme of Pseudomonas aeruginosa

    PubMed Central

    Domenech, Carlos Eduardo; Otero, Lisandro Horacio; Beassoni, Paola Rita; Lisa, Angela Teresita

    2011-01-01

    Pseudomonas aeruginosa synthesizes phosphorylcholine phosphatase (PchP) when grown on choline, betaine, dimethylglycine or carnitine. In the presence of Mg2+ or Zn2+, PchP catalyzes the hydrolysis of p-nitrophenylphosphate (p-NPP) or phosphorylcholine (Pcho). The regulation of pchP gene expression is under the control of GbdR and NtrC; dimethylglycine is likely the metabolite directly involved in the induction of PchP. Therefore, the regulation of choline metabolism and consequently PchP synthesis may reflect an adaptive response of P. aeruginosa to environmental conditions. Bioinformatic and biochemistry studies shown that PchP contains two sites for alkylammonium compounds (AACs): one in the catalytic site near the metal ion-phosphoester pocket, and another in an inhibitory site responsible for the binding of the alkylammonium moiety. Both sites could be close to each other and interact through the residues 42E, 43E and 82YYY84. Zn2+ is better activator than Mg2+ at pH 5.0 and it is more effective at alleviating the inhibition produced by the entry of Pcho or different AACs in the inhibitory site. We postulate that Zn2+ induces at pH 5.0 a conformational change in the active center that is communicated to the inhibitory site, producing a compact or closed structure. However, at pH 7.4, this effect is not observed because to the hydrolysis of the [Zn2+L2−1L20(H2O)2] complex, which causes a change from octahedral to tetrahedral in the metal coordination geometry. This enzyme is also present in P. fluorescens, P. putida, P. syringae, and other organisms. We have recently crystallized PchP and solved its structure. PMID:21915373

  11. Complete Genome Sequences of Pseudomonas fluorescens Bacteriophages Isolated from Freshwater Samples in Omaha, Nebraska

    PubMed Central

    Lu, Guoqing; Luhr, Jamie; Stoecklein, Andrew; Warner, Paige

    2017-01-01

    ABSTRACT The complete genome sequences of four Pseudomonas fluorescens bacteriophages, UNO-SLW1 to UNO-SLW4, isolated from freshwater samples, are 39,092 to 39,215 bp long. The genomes are highly similar (identity, >0.995) but dissimilar from that of Pseudomonas phage Pf-10 (the closest relative, 0.685 to 0.686 identity), with 48 to 49 protein-coding genes and 66 regulatory sites predicted. PMID:28336602

  12. Analysis of the type III secretion system from Pseudomonas fluorescens Q8r1-96

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have shown that near-identical strains of Pseudomonas fluorescens colonize the roots of wheat at levels that differ markedly, ranging from simple commensalism to a more sophisticated relationship better described as a mutualistic symbiosis. In many biological systems, such interactions are mediat...

  13. Protozoan-induced regulation of cycliclipopeptide biosythesis is an effective predation defense mechanism for Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The grazing activity of protozoa significantly impacts the dynamics, diversification and evolution of bacterial communities in soil ecosystems. The feeding preference of protozoa is related to their inability to ingest or digest specific bacteria. Pseudomonas fluorescens strains SBW25 and SS101 used...

  14. Improved High-Quality Draft Genome Sequence of Pseudomonas fluorescens KENGFT3

    PubMed Central

    Town, Jennifer; Cui, Nina; Audy, Patrice; Boyetchko, Sue

    2016-01-01

    Pseudomonas sp. strain KENGFT3 inhibits the growth of Phytophthora infestans and is a potentially useful biopesticide for plant diseases, including potato late blight. We sequenced the 6.2-Mbp genome of this strain and assembled it into a single scaffold with 9 contigs. KENGFT3 is related to previously sequenced strains of P. fluorescens. PMID:27231365

  15. Cloning, sequence, and properties of the soluble pyridine nucleotide transhydrogenase of Pseudomonas fluorescens.

    PubMed Central

    French, C E; Boonstra, B; Bufton, K A; Bruce, N C

    1997-01-01

    The gene encoding the soluble pyridine nucleotide transhydrogenase (STH) of Pseudomonas fluorescens was cloned and expressed in Escherichia coli. STH is related to the flavoprotein disulfide oxidoreductases but lacks one of the conserved redox-active cysteine residues. The gene is highly similar to an E. coli gene of unknown function. PMID:9098078

  16. Draft genome sequence of the phenazine-producing Pseudomonas fluorescens strain 2-79

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens strain 2-79, a natural isolate of the rhizosphere of wheat (Triticum aestivum L.), possesses antagonistic potential toward several fungal pathogens. We report the draft genome sequence of strain 2-79, which comprises 5,674 protein-coding sequences....

  17. Effects of media on recovery of Escherichia coli 0157:H7 and Pseudomonas fluorescens from spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of post-harvest contamination of leafy greens by Escherichia coli O157:H7 is important for food safety. Efficient recovery and enumeration of E. coli O157:H7 and the biocontrol microbe Pseudomonas fluorescens (non-pectolytic and non-plant pathogenic) from produce is crucial for assessment of...

  18. Effects of media on recovery of Escherichia coli 0157:H7 and Pseudomonas fluorescens from spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control the post-harvest contamination of leafy greens by Escherichia coli O157:H7 is important for food safety. Efficient recovery and enumeration of E. coli O157:H7 and the biocontrol microbe Pseudomonas fluorescens from produce is crucial for assessment of biocontrol efficacy. Sensitive and effec...

  19. Microarray Analysis of Pseudomonas fluorescens Pf-5 Grown on Seed Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biological control agent Pseudomonas fluorescens Pf-5 suppresses seedling emergence diseases caused by soilborne fungi and Oomycetes. Genes expressed by a biological control agent on seed surfaces determine the outcome of its interaction with target pathogens in the spermosphere, the soil surrou...

  20. Genome sequence of the mycorrhizal helper bacterium Pseudomonas fluorescens BBc6R8

    SciTech Connect

    Deveau, Aurelie; Grob, Harald; Morin, Emmanuelle; Karpinets, Tatiana V; Utturkar, Sagar M; Mehnaz, Samina; Kurz, Sven; Martin, Francis; Frey-Klett, Pascale; Labbe, Jessy L

    2014-01-01

    We report the draft genome sequence of the mycorrhiza helper bacterium Pseudomonas fluorescens strain BBc6R8 . Several traits which could be involved in the mycorrhiza helper ability of the bacterial strain such as multiple secretion systems, auxin metabolism and phosphate mobilization were evidenced in the genome.

  1. TonB Dependent Receptors of Pseudomonas fluorescens Pf-5: Roles in Siderophore and Iron Uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    TonB-dependent receptors (TBDRs) are outer membrane proteins with essential roles in iron uptake by Gram-negative bacteria. The biological control strain Pseudomonas fluorescens Pf-5 has 45 predicted TBDRs in its genome, which far exceeds the number of TBDRs in most published bacterial proteomes. Ei...

  2. TonB-Dependent outer-membrane proteins and siderophore utilization in Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soil bacterium Pseudomonas fluorescens Pf-5 produces two siderophores, a pyoverdine and enantio-pyochelin, and its proteome includes 45 TonB-dependent outer-membrane proteins, which commonly function in uptake of siderophores and other substrates from the environment. The 45 proteins share the ...

  3. TonB-Dependent Receptors of Pseudomonas fluorescens Pf-5 and Siderophore Uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    TonB-dependent receptors (TBDRs) are outer membrane proteins with essential roles in iron uptake by Gram-negative bacteria. The biological control strain Pseudomonas fluorescens Pf-5 has 45 predicted TBDRs in its genome, which far exceeds the number of TBDRs in most published bacterial proteomes. ...

  4. TonB Dependent Receptors of Pseudomonas fluorescens Pf-5 and Siderophore Uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    TonB-dependent receptors (TBDRs) are outer membrane proteins with essential roles in iron uptake by Gram-negative bacteria. The biological control strain Pseudomonas fluorescens Pf-5 has 45 predicted TBDRs in its genome, which far exceeds the number of TBDRs in most published bacterial proteomes. B...

  5. Microarray Analysis and Mutagenesis of the Biological Control Agent Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biological control agent Pseudomonas fluorescens Pf-5 suppresses seedling emergence diseases caused by soilborne fungi and Oomycetes. Pf-5 produces at least ten secondary metabolites. These include hydrogen cyanide, pyrrolnitrin, pyoluteorin and 2,4-diacetylphloroglucinol, which have known funct...

  6. Development and Testing of Secondary Metabolism Mutants of Pseudomonas fluorescens PF-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens Pf-5, a biological control agent of soil-borne plant diseases, produces at least ten secondary metabolites. Several of these metabolites, including hydrogen cyanide, pyrrolnitrin, pyoluteorin and 2,4-diacetylphloroglucinol have well-characterized roles in biological control. ...

  7. Draft Genome Sequence of Three Endophyte Strains of Pseudomonas fluorescens Isolated from Miscanthus giganteus

    PubMed Central

    Moreira, António S.; Lloyd, Andrew; Lally, Richard D.; Galbally, Paul T.; Ryan, David

    2016-01-01

    We report here the draft genome sequence of three Pseudomonas fluorescens strains (L111, L228, and L321) isolated from Miscanthus giganteus. The draft genome analyses uncovered a group of genes involved in the biosynthesis of secondary metabolites and for plant growth promotion. PMID:27738024

  8. Cryptic transposable phages of Pseudomonas aeruginosa

    SciTech Connect

    Krylov, V.N.; Mit`kina, L.N.; Pleteneva, E.A.; Aleshin, V.V.

    1995-11-01

    Frequencies of nucleotide sequences homologous to phage transposons (PT) of two species, D3112 and B3, were assessed in genomes of natural Pseudomonas aeruginosa strains by the dot-blot hybridization method. These strains were incapable of liberating viable phages on a lawn of the PA01 standard indicator strain of P. aeruginosa. It was shown that the homologies detected belong to two groups, high and intermediate, with respect to homology level. Homology patterns were classified as high when they provided signals comparable to those for hybridization in a positive control; patterns were classified as intermediate when the hybridization level was higher than the background level, but lower than in the positive control. Homologous PT sequences were designated as cryptic PT. Intact cryptic PT prophages were shown to exist in genomes of particular natural strains manifesting a higher level of hybridization. However, the growth of these phages was limited by the restriction system of strain PA01. It is possible to isolate strains maintaining the growth of some cryptic PT. These strains differed from P. aeruginosa with respect to the specificity of the restriction and modification system. Nevertheless, in most cases, the attempt to identify a novel host capable of maintaining growth of a cryptic PT failed. Natural strains often carry cryptic PT related to both known PT species, D3112 and B3. The frequency of cryptic PT is extremely high, reaching 30% in strains with a high level of homology only and up to 50% in all strains exhibiting homology. This high PT frequency is assumed to be associated with the considerable variation of P. aeruginosa. 15 refs., 1 fig., 2 tabs.

  9. Contribution of the Pseudomonas fluorescens MFE01 Type VI Secretion System to Biofilm Formation

    PubMed Central

    Gallique, Mathias; Decoin, Victorien; Barbey, Corinne; Rosay, Thibaut; Feuilloley, Marc G. J.; Orange, Nicole

    2017-01-01

    Type VI secretion systems (T6SSs) are widespread in Gram-negative bacteria, including Pseudomonas. These macromolecular machineries inject toxins directly into prokaryotic or eukaryotic prey cells. Hcp proteins are structural components of the extracellular part of this machinery. We recently reported that MFE01, an avirulent strain of Pseudomonas fluorescens, possesses at least two hcp genes, hcp1 and hcp2, encoding proteins playing important roles in interbacterial interactions. Indeed, P. fluorescens MFE01 can immobilise and kill diverse bacteria of various origins through the action of the Hcp1 or Hcp2 proteins of the T6SS. We show here that another Hcp protein, Hcp3, is involved in killing prey cells during co-culture on solid medium. Even after the mutation of hcp1, hcp2, or hcp3, MFE01 impaired biofilm formation by MFP05, a P. fluorescens strain isolated from human skin. These mutations did not reduce P. fluorescens MFE01 biofilm formation, but the three Hcp proteins were required for the completion of biofilm maturation. Moreover, a mutant with a disruption of one of the unique core component genes, MFE01ΔtssC, was unable to produce its own biofilm or inhibit MFP05 biofilm formation. Finally, MFE01 did not produce detectable N-acyl-homoserine lactones for quorum sensing, a phenomenon reported for many other P. fluorescens strains. Our results suggest a role for the T6SS in communication between bacterial cells, in this strain, under biofilm conditions. PMID:28114423

  10. Effect of GABA, a Bacterial Metabolite, on Pseudomonas fluorescens Surface Properties and Cytotoxicity

    PubMed Central

    Dagorn, Audrey; Chapalain, Annelise; Mijouin, Lily; Hillion, Mélanie; Duclairoir-Poc, Cécile; Chevalier, Sylvie; Taupin, Laure; Orange, Nicole; Feuilloley, Marc G. J.

    2013-01-01

    Different bacterial species and, particularly Pseudomonas fluorescens, can produce gamma-aminobutyric acid (GABA) and express GABA-binding proteins. In this study, we investigated the effect of GABA on the virulence and biofilm formation activity of different strains of P. fluorescens. Exposure of a psychotropic strain of P. fluorescens (MF37) to GABA (10−5 M) increased its necrotic-like activity on eukaryotic (glial) cells, but reduced its apoptotic effect. Conversely, muscimol and bicuculline, the selective agonist and antagonist of eukaryote GABAA receptors, respectively, were ineffective. P. fluorescens MF37 did not produce biosurfactants, and its caseinase, esterase, amylase, hemolytic activity or pyoverdine productions were unchanged. In contrast, the effect of GABA was associated to rearrangements of the lipopolysaccharide (LPS) structure, particularly in the lipid A region. The surface hydrophobicity of MF37 was marginally modified, and GABA reduced its biofilm formation activity on PVC, but not on glass, although the initial adhesion was increased. Five other P. fluorescens strains were studied, and only one, MFP05, a strain isolated from human skin, showed structural differences of biofilm maturation after exposure to GABA. These results reveal that GABA can regulate the LPS structure and cytotoxicity of P. fluorescens, but that this property is specific to some strains. PMID:23743829

  11. Thermal mitigation of Pseudomonas aeruginosa biofilms

    PubMed Central

    O’Toole, Ann; Ricker, Erica B.; Nuxoll, Eric

    2015-01-01

    Bacterial biofilms infect 2 – 4 % of medical devices upon implantation, resulting in multiple surgeries and increased recovery time due to the very great increase in antibiotic resistance in the biofilm phenotype. This work investigates the feasibility of thermal mitigation of biofilms at physiologically accessible temperatures. Pseudomonas aeruginosa biofilms were cultured to high bacterial density (1.7 × 109 CFU cm−2) and subjected to thermal shocks ranging from 50 °C to 80 °C for durations of 1 to 30 min. The decrease in viable bacteria was closely correlated with an Arrhenius temperature dependence and Weibull-style time dependence, demonstrating up to six orders of magnitude reduction in bacterial load. The bacterial load for films with more conventional initial bacterial densities dropped below quantifiable levels, indicating thermal mitigation as a viable approach to biofilm control. PMID:26371591

  12. Quantification of 2,4-diacetylphloroglucinol producing Pseudomonas fluorescens in the plant rhizosphere by real-time PCR.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A real-time PCR SYBR green assay was developed to quantify populations of 2, 4-DAPG-producing (phlD+) Pseudomonas fluorescens in soil and the rhizosphere. Primers were designed to specifically amplify the phlD gene from four different genotypes (A, B, D, and I) of phlD+ P. fluorescens and PCR condit...

  13. Purification of extracellular lipase from Pseudomonas aeruginosa.

    PubMed Central

    Stuer, W; Jaeger, K E; Winkler, U K

    1986-01-01

    Lipase (triacylglycerol acylhydrolase, EC 3.1.1.3) was excreted by Pseudomonas aeruginosa PAC1R during the late logarithmic growth phase. Characterization of cell-free culture supernatants by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of significant amounts of lipopolysaccharide, part of which seemed to be tightly bound to lipase. After concentration of culture supernatants by ultrafiltration, lipase-lipopolysaccharide complexes were dissociated by treatment with EDTA-Tris buffer and subsequent sonication in the presence of the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. The solubilized lipase was purified by isoelectric focusing in an agarose gel containing the same detergent; the lipase activity appeared in a single peak corresponding to a distinct band in the silver-stained gel. The isoelectric point was 5.8. Analysis of purified lipase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and scanning revealed an apparent molecular weight of 29,000 and a specific activity of 760 mu kat/mg of protein. Estimations based on these data showed that a single P. aeruginosa cell excreted about 200 molecules of lipase, each having a molecular activity of 2.2 X 10(4) per s. Images PMID:3096967

  14. Sequencing and functional analysis of styrene catabolism genes from Pseudomonas fluorescens ST.

    PubMed Central

    Beltrametti, F; Marconi, A M; Bestetti, G; Colombo, C; Galli, E; Ruzzi, M; Zennaro, E

    1997-01-01

    The nucleotide sequence of the 4,377-bp chromosomal region of Pseudomonas fluorescens ST that codes for the oxidation of styrene to phenylacetic acid was determined. Four open reading frames, named styA, styB, styC, and styD, were identified in this region. Sequence analysis and biotransformation assays, performed with batch and continuous cultures, allowed us to identify the functions of the sequenced genes. styA and styB encode a styrene monooxygenase responsible for the transformation of styrene to epoxystyrene; styC codes for the second enzyme of the pathway, an epoxystyrene isomerase that converts epoxystyrene to phenylacetaldehyde; and the styD gene produces a phenylacetaldehyde dehydrogenase that oxidizes phenylacetaldehyde to phenylacetic acid. StyA, 415-amino-acids long, was found to be weakly homologous to p-hydroxybenzoate hydroxylase from both P. fluorescens and P. aeruginosa and to salicylate hydroxylase from P. putida, suggesting that it might be a flavin adenine dinucleotide-binding monooxygenase. StyB was found to be partially homologous to the carboxyterminal part of the 2,4-dichlorophenol-6-monooxygenase encoded by plasmid pJP4, while the styC product did not share significant homology with any known proteins. The fourth open reading frame, styD, could encode a protein of 502 amino acids and was strongly homologous to several eukaryotic and prokaryotic aldehyde dehydrogenases. The order of the genes corresponds to that of the catabolic steps. The previously suggested presence of the gene for epoxystyrene reductase, which directly converts epoxystyrene to 2-phenylethanol (A.M. Marconi, F. Beltrametti, G. Bestetti, F. Solinas, M. Ruzzi, E. Galli, and E. Zennaro, Appl. Environ. Microbiol. 61:121-127, 1996), has not been confirmed by sequencing and by biotransformation assays performed in continuous cultures. A copy of the insertion sequence ISI162, belonging to the IS21-like family of elements, was identified immediately downstream of the styrene

  15. Social cheating in Pseudomonas aeruginosa quorum sensing.

    PubMed

    Sandoz, Kelsi M; Mitzimberg, Shelby M; Schuster, Martin

    2007-10-02

    In a process termed quorum sensing, bacteria use diffusible chemical signals to coordinate cell density-dependent gene expression. In the human pathogen Pseudomonas aeruginosa, quorum sensing controls hundreds of genes, many of which encode extracellular virulence factors. Quorum sensing is required for P. aeruginosa virulence in animal models. Curiously, quorum sensing-deficient variants, most of which carry a mutation in the gene encoding the central quorum sensing regulator lasR, are frequently isolated from acute and chronic infections. The mechanism for their emergence is not known. Here we provide experimental evidence suggesting that these lasR mutants are social cheaters that cease production of quorum-controlled factors and take advantage of their production by the group. We detected an emerging subpopulation of lasR mutants after approximately 100 generations of in vitro evolution of the P. aeruginosa wild-type strain under culture conditions that require quorum sensing for growth. Under such conditions, quorum sensing appears to impose a metabolic burden on the proliferating bacterial cell, because quorum-controlled genes not normally induced until cessation of growth were highly expressed early in growth, and a defined lasR mutant showed a growth advantage when cocultured with the parent strain. The emergence of quorum-sensing-deficient variants in certain environments is therefore an indicator of high quorum sensing activity of the bacterial population as a whole. It does not necessarily indicate that quorum sensing is insignificant, as has previously been suggested. Thus, novel antivirulence strategies aimed at disrupting bacterial communication may be particularly effective in such clinical settings.

  16. Isolation of oxidase-negative Pseudomonas aeruginosa from sputum culture.

    PubMed

    Hampton, K D; Wasilauskas, B L

    1979-05-01

    Two isolates of Pseudomonas aeruginosa lacking characteristic indophenol oxidase were recovered from a sputum specimen. A discussion of the characteristic biochemical tests and antibiograms along with a possible explanation for this phenomenon is presented.

  17. Lack of AHL-based quorum sensing in Pseudomonas fluorescens isolated from milk.

    PubMed

    Martins, Maurilio L; Pinto, Uelinton M; Riedel, Kathrin; Vanetti, Maria C D; Mantovani, Hilário C; de Araújo, Elza F

    2014-01-01

    Numerous bacteria coordinate gene expression in response to small signalling molecules in many cases known as acylhomoserine lactones (AHLs), which accumulate as a function of cell density in a process known as quorum sensing. This work aimed to determine if phenotypes that are important to define microbial activity in foods such as biofilm formation, swarming motility and proteolytic activity of two Pseudomonas fluorescens strains, isolated from refrigerated raw milk, are influenced by AHL molecules. The tested P. fluorescens strains did not produce AHL molecules in none of the evaluated media. We found that biofilm formation was dependent on the culture media, but it was not influenced by AHLs. Our results indicate that biofilm formation, swarming motility and proteolytic activity of the tested P. fluorescens strains are not regulated by acyl-homoserine lactones. It is likely that AHL-dependent quorum sensing system is absent from these strains.

  18. Atmospheric-pressure air microplasma jets in aqueous media for the inactivation of Pseudomonas fluorescens cells

    SciTech Connect

    Zhang, Xianhui; Yang, Si-ze; Liu, Dongping; Song, Ying; Sun, Yue

    2013-05-15

    The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

  19. First report of NDM-1-producing Pseudomonas aeruginosa in Egypt.

    PubMed

    Zafer, Mai Mahmoud; Amin, Mady; El Mahallawy, Hadir; Ashour, Mohammed Seif El-Din; Al Agamy, Mohamed

    2014-12-01

    This work reports the occurrence of New Delhi metallo-beta-lactamase 1 (NDM-1) in metallo-beta-lactamase-producing Pseudomonas aeruginosa in Egypt for the first time, and the presence of more than one blaMBL gene in carbapenem-resistant P. aeruginosa.

  20. Pseudomonas 2007 Meeting Review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas is an important genus of bacteria. Pseudomonas aeruginosa is the third most common nosocomial pathogen in our society, associated with chronic and eventually fatal lung disease in cystic fibrosis patients, while Pseudomonas syringae species are prominent plant pathogens. The fluorescen...

  1. The Regulatory Network of Pseudomonas aeruginosa

    PubMed Central

    2011-01-01

    Background Pseudomonas aeruginosa is an important bacterial model due to its metabolic and pathogenic abilities, which allow it to interact and colonize a wide range of hosts, including plants and animals. In this work we compile and analyze the structure and organization of an experimentally supported regulatory network in this bacterium. Results The regulatory network consists of 690 genes and 1020 regulatory interactions between their products (12% of total genes: 54% sigma and 16% of transcription factors). This complex interplay makes the third largest regulatory network of those reported in bacteria. The entire network is enriched for activating interactions and, peculiarly, self-activation seems to occur more prominent for transcription factors (TFs), which contrasts with other biological networks where self-repression is dominant. The network contains a giant component of 650 genes organized into 11 hierarchies, encompassing important biological processes, such as, biofilms formation, production of exopolysaccharide alginate and several virulence factors, and of the so-called quorum sensing regulons. Conclusions The study of gene regulation in P. aeruginosa is biased towards pathogenesis and virulence processes, all of which are interconnected. The network shows power-law distribution -input degree -, and we identified the top ten global regulators, six two-element cycles, the longest paths have ten steps, six biological modules and the main motifs containing three and four elements. We think this work can provide insights for the design of further studies to cover the many gaps in knowledge of this important bacterial model, and for the design of systems strategies to combat this bacterium. PMID:22587778

  2. Ambroxol interferes with Pseudomonas aeruginosa quorum sensing.

    PubMed

    Lu, Qi; Yu, Jialin; Yang, Xiqiang; Wang, Jiarong; Wang, Lijia; Lin, Yayin; Lin, Lihua

    2010-09-01

    The mucolytic agent ambroxol has been reported to interfere with the formation of Pseudomonas aeruginosa-derived biofilms in addition to reducing alginate production by undefined mechanisms. Since quorum sensing is a key regulator of virulence and biofilm formation, we examined the effects of ambroxol on P. aeruginosa PAO1 wild-type bacterial clearance rates, adhesion profiles and biofilm formation compared with the quorum sensing-deficient, double-mutant strains DeltalasR DeltarhlR and DeltalasI DeltarhlI. Data presented in this report demonstrated that ambroxol treatment reduced survival rates of the double-mutant strains compared with the wild-type strain in a dose-dependent manner even though the double-mutants had increased adhesion in the presence of ambroxol compared with the wild-type strain. The PAO1 wild-type strain produced a significantly thicker biofilm (21.64+/-0.57 microm) compared with the biofilms produced by the DeltalasR DeltarhlR (7.36+/-0.2 microm) and DeltalasI DeltarhlI (6.62+/-0.31 microm) isolates. Ambroxol treatment reduced biofilm thickness, increased areal porosity, and decreased the average diffusion distance and textual entropy of wild-type and double-mutant strains. However, compared with the double-mutant strains, the changes observed for the wild-type strain were more clearly defined. Finally, ambroxol exhibited significant antagonistic quorum-sensing properties, suggesting that it could be adapted for use clinically in the treatment of cystic fibrosis and to reduce biofilm formation and in the colonisation of indwelling devices.

  3. Pseudomonas aeruginosa Type III Secretory Toxin ExoU and Its Predicted Homologs

    PubMed Central

    Sawa, Teiji; Hamaoka, Saeko; Kinoshita, Mao; Kainuma, Atsushi; Naito, Yoshifumi; Akiyama, Koichi; Kato, Hideya

    2016-01-01

    Pseudomonas aeruginosa ExoU, a type III secretory toxin and major virulence factor with patatin-like phospholipase activity, is responsible for acute lung injury and sepsis in immunocompromised patients. Through use of a recently updated bacterial genome database, protein sequences predicted to be homologous to Ps. aeruginosa ExoU were identified in 17 other Pseudomonas species (Ps. fluorescens, Ps. lundensis, Ps. weihenstephanensis, Ps. marginalis, Ps. rhodesiae, Ps. synxantha, Ps. libanensis, Ps. extremaustralis, Ps. veronii, Ps. simiae, Ps. trivialis, Ps. tolaasii, Ps. orientalis, Ps. taetrolens, Ps. syringae, Ps. viridiflava, and Ps. cannabina) and 8 Gram-negative bacteria from three other genera (Photorhabdus, Aeromonas, and Paludibacterium). In the alignment of the predicted primary amino acid sequences used for the phylogenetic analyses, both highly conserved and nonconserved parts of the toxin were discovered among the various species. Further comparative studies of the predicted ExoU homologs should provide us with more detailed information about the unique characteristics of the Ps. aeruginosa ExoU toxin. PMID:27792159

  4. Secretion of phospholipase C by Pseudomonas aeruginosa.

    PubMed Central

    Stinson, M W; Hayden, C

    1979-01-01

    The conditions necessary for the secretion of phospholipase C (phosphatidylcholine cholinephosphohydrolase) by Pseudomonas aeruginosa were studied. Enzyme secretion by washed cell suspensions required a carbon source and ammonium, potassium, and calcium ions. The calcium requirement could be substituted by magnesium and strontium but not by copper, manganese, cobalt, or zinc. During growth in liquid medium, cells secreted phospholipase C during late logarithmic and early stationary phases. Secretion was repressed by the addition of inorganic phosphate but not by organic phosphates, glucose, or sodium succinate. Studies with tetracycline indicated that de novo protein synthesis was necessary for the secretion of phospholipase C and that the exoenzyme was not released from a preformed periplasmic pool. Similarly, extraction of actively secreting cells with 0.2 M MgCl2 at pH 8.4 solubilized large quantities of the periplasmic enzyme alkaline phosphatase but insignificant amounts of phospholipase C. Bacteria continued to secrete enzyme for nearly 45 min after the addition of inorganic phosphate or rifampin. Images PMID:114487

  5. Comprehensive transposon mutant library of Pseudomonas aeruginosa

    PubMed Central

    Jacobs, Michael A.; Alwood, Ashley; Thaipisuttikul, Iyarit; Spencer, David; Haugen, Eric; Ernst, Stephen; Will, Oliver; Kaul, Rajinder; Raymond, Christopher; Levy, Ruth; Chun-Rong, Liu; Guenthner, Donald; Bovee, Donald; Olson, Maynard V.; Manoil, Colin

    2003-01-01

    We have developed technologies for creating saturating libraries of sequence-defined transposon insertion mutants in which each strain is maintained. Phenotypic analysis of such libraries should provide a virtually complete identification of nonessential genes required for any process for which a suitable screen can be devised. The approach was applied to Pseudomonas aeruginosa, an opportunistic pathogen with a 6.3-Mbp genome. The library that was generated consists of 30,100 sequence-defined mutants, corresponding to an average of five insertions per gene. About 12% of the predicted genes of this organism lacked insertions; many of these genes are likely to be essential for growth on rich media. Based on statistical analyses and bioinformatic comparison to known essential genes in E. coli, we estimate that the actual number of essential genes is 300-400. Screening the collection for strains defective in two defined multigenic processes (twitching motility and prototrophic growth) identified mutants corresponding to nearly all genes expected from earlier studies. Thus, phenotypic analysis of the collection may produce essentially complete lists of genes required for diverse biological activities. The transposons used to generate the mutant collection have added features that should facilitate downstream studies of gene expression, protein localization, epistasis, and chromosome engineering. PMID:14617778

  6. Comprehensive transposon mutant library of Pseudomonas aeruginosa.

    PubMed

    Jacobs, Michael A; Alwood, Ashley; Thaipisuttikul, Iyarit; Spencer, David; Haugen, Eric; Ernst, Stephen; Will, Oliver; Kaul, Rajinder; Raymond, Christopher; Levy, Ruth; Chun-Rong, Liu; Guenthner, Donald; Bovee, Donald; Olson, Maynard V; Manoil, Colin

    2003-11-25

    We have developed technologies for creating saturating libraries of sequence-defined transposon insertion mutants in which each strain is maintained. Phenotypic analysis of such libraries should provide a virtually complete identification of nonessential genes required for any process for which a suitable screen can be devised. The approach was applied to Pseudomonas aeruginosa, an opportunistic pathogen with a 6.3-Mbp genome. The library that was generated consists of 30,100 sequence-defined mutants, corresponding to an average of five insertions per gene. About 12% of the predicted genes of this organism lacked insertions; many of these genes are likely to be essential for growth on rich media. Based on statistical analyses and bioinformatic comparison to known essential genes in E. coli, we estimate that the actual number of essential genes is 300-400. Screening the collection for strains defective in two defined multigenic processes (twitching motility and prototrophic growth) identified mutants corresponding to nearly all genes expected from earlier studies. Thus, phenotypic analysis of the collection may produce essentially complete lists of genes required for diverse biological activities. The transposons used to generate the mutant collection have added features that should facilitate downstream studies of gene expression, protein localization, epistasis, and chromosome engineering.

  7. Regulation of Pseudomonas quinolone signal synthesis in Pseudomonas aeruginosa.

    PubMed

    Wade, Dana S; Calfee, M Worth; Rocha, Edson R; Ling, Elizabeth A; Engstrom, Elana; Coleman, James P; Pesci, Everett C

    2005-07-01

    Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic lung infections in cystic fibrosis patients and is a major source of nosocomial infections. This bacterium controls many virulence factors by using two quorum-sensing systems, las and rhl. The las system is composed of the LasR regulator protein and its cell-to-cell signal, N-(3-oxododecanoyl) homoserine lactone, and the rhl system is composed of RhlR and the signal N-butyryl homoserine lactone. A third intercellular signal, the Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4-quinolone), also regulates numerous virulence factors. PQS synthesis requires the expression of multiple operons, one of which is pqsABCDE. Previous experiments showed that the transcription of this operon, and therefore PQS production, is negatively regulated by the rhl quorum-sensing system and positively regulated by the las quorum-sensing system and PqsR (also known as MvfR), a LysR-type transcriptional regulator protein. With the use of DNA mobility shift assays and beta-galactosidase reporter fusions, we have studied the regulation of pqsR and its relationship to pqsA, lasR, and rhlR. We show that PqsR binds the promoter of pqsA and that this binding increases dramatically in the presence of PQS, implying that PQS acts as a coinducer for PqsR. We have also mapped the transcriptional start site for pqsR and found that the transcription of pqsR is positively regulated by lasR and negatively regulated by rhlR. These results suggest that a regulatory chain occurs where pqsR is under the control of LasR and RhlR and where PqsR in turn controls pqsABCDE, which is required for the production of PQS.

  8. Comparative effect of methioninyl adenylate on the growth of Salmonella typhimurium and Pseudomonas aeruginosa.

    PubMed

    Enouf, J; Laurence, F; Farrugia, G; Blanchard, P; Robert-Gero, M

    1976-10-11

    The bacteriostatic effect of methioninyl adenylate(MAMP)--a specific inhibitor of the enzyme methionyl-tRNA synthetase--was investigated on Salmonella typhimurium and Pseudomonas aeruginosa. 0.1 mM of this molecule added to the culture, inhibits the growth of S. typhimurium. The inhibition is specifically reversible by 0.1 mM L-methionine. In the same conditions even 1-2 mM MAMP has a very slight effect on the growth rate of P. aeruginosa and only during the first two generations. The same observation was made with the two other members of the fluorescens group P.fluorescens and P.putida. The growth rate of P. testosteroni with 1 mM MAMP in the medium is similar to the growth rate of P. aeruginosa but the other member of the acidovorans group P. acidovorans is much more affected by the smae concentration of the inhibitor. --P. multivorans is inhibited by MAMP like P. acidovorans but with a somewhat higher yield at the end of the culture. --MAMP has no effect on P. alcaligenes. The possible reasons for the weak bacteriostatic effect of MAMP on P. aeruginosa were investigated. It was established that the inhibitor enters the cells and is not used as a carbon and energy source. The intracellular methionine concentration in S. typhimurium and in P. aeruginosa is about the same and does not increase when bacteria are cultivated with MAMP. The MTS of the two microorganisms is inhibited by MAMP in vitro to about the same extent. Furthermore the tRNAmet from P. aeruginosa are fully acylated after 3 to 4 generations with this compound. Nevertheless MAMP elicits higher MTS activity in P. aeruginosa and in P. acidovorans after 1 h of incubation. The most striking difference between S. typhimurium and P. aeruginosa is that the intra and extracellular level of 5'phosphodiesterase which degrades MAMP is 10-20 fold higher in the second than in the first species.

  9. Resistance to pefloxacin in Pseudomonas aeruginosa.

    PubMed Central

    Michea-Hamzehpour, M; Lucain, C; Pechere, J C

    1991-01-01

    Mechanisms of resistance to pefloxacin were investigated in four isogenic Pseudomonas aeruginosa strains: S (parent isolate; MIC, 2 micrograms/ml), PT1 and PT2 (posttherapy isolates obtained in animals; MICs, 32 and 128 micrograms/ml, respectively), and PT2-r (posttherapy isolate obtained after six in vitro subpassages of PT2; MIC, 32 micrograms/ml). [2-3H]adenine incorporation (indirect evidence of DNA gyrase activity) in EDTA-permeabilized cells was less affected by pefloxacin in PT2 and PT2-r (50% inhibitory concentration, 0.27 and 0.26 microgram/ml, respectively) than it was in S and PT1 (50% inhibitory concentration, 0.04 and 0.05 microgram/ml, respectively). Reduced [14C]pefloxacin labeling of intact cells in strains PT1 and PT2 correlated with more susceptibility to EDTA and the presence of more calcium (P less than 0.05) and phosphorus in the outer membrane fractions. Outer membrane protein analysis showed reduced expression of protein D2 (47 kDa) in strains PT1 and PT2. Other proteins were apparently similar in all strains. The addition of calcium chloride (2 mM) to the sodium dodecyl sulfate-solubilized samples of outer membrane proteins, before heating and Western blotting, probed with monoclonal antibody anti-OmpF showed electrophoretic mobility changes of OmpF in strains PT1 and PT2 which were not seen in strain S. Calcium-induced changes were reversed with ethyleneglycoltetraacetate. Decreased [14C]pefloxacin labeling was further correlated with an altered lipopolysaccharide pattern and increased 3-deoxy-D-mannooctulosonic acid concentration (P less than 0.01). These findings suggested that resistance to pefloxacin is associated with altered DNA gyrase in strain PT2-r, with altered permeability in PT1, and with both mechanisms in PT2. The decreased expression of protein D2 and the higher calcium and lipopolysaccharide contents of the outer membrane could be responsible for the permeability deficiency in P. aeruginosa. Images PMID:1645509

  10. Inactivation of Pseudomonas fluorescens in skim milk by combinations of pulsed electric fields and organic acids.

    PubMed

    Fernández-Molina, Juan J; Altunakar, Bilge; Bermúdez-Aguirre, Daniela; Swanson, Barry G; Barbosa-Cánovas, Gustavo V

    2005-06-01

    Pseudomonas fluorescens suspended in skim milk was inactivated by application of pulsed electric fields (PEF) either alone or in combination with acetic or propionic acid. The initial concentration of microorganisms ranged from 10(5) to 10(6) CFU/ml. Addition of acetic acid and propionic acid to skim milk inactivated 0.24 and 0.48 log CFU/ml P. fluorescens, respectively. Sets of 10, 20, and 30 pulses were applied to the skim milk using exponentially decaying pulses with pulse lengths of 2 micros and pulse frequencies of 3 Hz. Treatment temperature was maintained between 16 and 20 degrees C. In the absence of organic acids, PEF treatment of skim milk at field intensities of 31 and 38 kV/cm reduced P. fluorescens populations by 1.0 to 1.8 and by 1.2 to 1.9 log CFU/ml, respectively. Additions of acetic and propionic acid to the skim milk in a pH range of 5.0 to 5.3 and PEF treatment at 31, 33, and 34 kV/cm, and 36, 37, and 38 kV/cm reduced the population of P. fluorescens by 1.4 and 1.8 log CFU/ml, respectively. No synergistic effect resulted from the combination of PEF with acetic or propionic acid.

  11. Pseudomonas aeruginosa essentials: an update on investigation of essential genes.

    PubMed

    Juhas, Mario

    2015-11-01

    Pseudomonas aeruginosa is the leading cause of nosocomial infections, particularly in immunocompromised, cancer, burn and cystic fibrosis patients. Development of novel antimicrobials against P. aeruginosa is therefore of the highest importance. Although the first reports on P. aeruginosa essential genes date back to the early 2000s, a number of more sensitive genomic approaches have been used recently to better define essential genes in this organism. These analyses highlight the evolution of the definition of an 'essential' gene from the traditional to the context-dependent. Essential genes, particularly those indispensable under the clinically relevant conditions, are considered to be promising targets of novel antibiotics against P. aeruginosa. This review provides an update on the investigation of P. aeruginosa essential genes. Special focus is on recently identified P. aeruginosa essential genes and their exploitation for the development of antimicrobials.

  12. Glycerol metabolism promotes biofilm formation by Pseudomonas aeruginosa.

    PubMed

    Scoffield, Jessica; Silo-Suh, Laura

    2016-08-01

    Pseudomonas aeruginosa causes persistent infections in the airways of cystic fibrosis (CF) patients. Airway sputum contains various host-derived nutrients that can be utilized by P. aeruginosa, including phosphotidylcholine, a major component of host cell membranes. Phosphotidylcholine can be degraded by P. aeruginosa to glycerol and fatty acids to increase the availability of glycerol in the CF lung. In this study, we explored the role that glycerol metabolism plays in biofilm formation by P. aeruginosa. We report that glycerol metabolism promotes biofilm formation by both a chronic CF isolate (FRD1) and a wound isolate (PAO1) of P. aeruginosa. Moreover, loss of the GlpR regulator, which represses the expression of genes involved in glycerol metabolism, enhances biofilm formation in FRD1 through the upregulation of Pel polysaccharide. Taken together, our results suggest that glycerol metabolism may be a key factor that contributes to P. aeruginosa persistence by promoting biofilm formation.

  13. Biochemical characterization of a Pseudomonas fluorescens strain isolated from a benzalkonium chloride solution.

    PubMed

    Nagai, K; Ohta, S; Zenda, H; Matsumoto, H; Makino, M

    1996-06-01

    A bacterium isolated as the contaminant of a batch of commercial benzalkonium chloride (BAC) solution (10% (w/v)) stored in a loosely capped bottle in the Department of Pharmacy Shinshu University Hospital was identified as Pseudomonas fluorescens belonging to biotype G of Stanier, et al. The strain was highly resistant to BAC, and the lowest concentration of BAC that inhibited visible growth of the strain as measured on nutrient agar plates was > or = 5000 micrograms/ml. BAC is a typical quaternary ammonium detergent. Thus we examined the tolerable growth concentration of various strains on surfactants. We were able to confirm growth of P. fluorescens of BAC resistance strain (PFRB) in 5% concentration, but the other strains were not able to grow in 0.1% concentration. We investigated the relationship between biotype and resistance to BAC. PFRB and three clinical isolated strains were found to be the same biotype G. However, no apparent correlation was found between the same biotypes and minimum inhibitory concentration (MIC) of disinfectant or growth permissible concentration on surfactants. The strain was unable to decompose BAC, as no growth occurred in the minimum medium containing BAC as the sole source of carbon, nitrogen or both. Our finding caused us to realize that P. fluorescens might also be a contaminant of disinfectants, as we have seen in Pseudomonas cepacia.

  14. Structure of a putative BenF-like porin from Pseudomonas fluorescens Pf-5 at 2.6 A resolution

    SciTech Connect

    Sampathkumar, P.; Swaminathan, S.; Lu, F.; Zhao, X.; Li, Z.; Gilmore, J.; Bain, K.; Rutter, M. E.; Gheyi, T.; Schwinn, D.; Bonanno, J. B.; Pieper, U.; Fajardo, J. E.; Fiser, A.; Almo, S. C.; Chance, M. R.; Baker, D.; Atwell, S.; Thompson, D. A.; Emtage, J. S.; Wasserman, S. R.; Sali, A.; Sauder, J. M.; Burley, S. K.

    2010-11-01

    Gram-negative bacteria typically overcome poor permeability of outer membranes through general porins like OmpF and OmpC, which form water-filled transmembrane pores permitting diffusion of hydrophilic molecules with no particular selectivity. Many bacteria lacking such general porins use substrate-specific porins to overcome growth-limiting conditions and facilitate selective transport of metabolites. Exclusive reliance on substrate-specific porins yields lower membrane permeability to small molecules (<600 Da) versus that seen for Escherichia coli. In Pseudomonads, transit of most small molecules across the cell membrane is thought to be mediated by substrate-specific channels of the OprD superfamily. This property explains, at least in part, the high incidence of Pseudomonas aeruginosa antibiotic resistance. High-throughput DNA sequencing of the P. aeruginosa chromosome revealed the presence of 19 genes encoding structurally related, substrate-specific porins (with 30-45% pairwise amino acid sequence identity) that mediate transmembrane passage of small, water-soluble compounds. The OprD superfamily encompasses the eponymous OprD subfamily, which includes 9 P. aeruginosa proteins that convey basic amino acids and carbapenem antibiotics, and the OpdK subfamily, which includes 11 P. aeruginosa proteins that convey aromatic acids and other small aromatic compounds. Genome sequencing of other gram-negative bacteria has revealed additional members of the OprD and OpdK subfamilies in various organisms, including other pseudomonads. Among the many bacteria in which OprD superfamily members have been identified are P. putida, P. fluorescens Pf-5, P. syringae, and Azotobacter vinelandii, all of which share closely related genes that encode the so-called BenF-like porins. In P. putida, benF is part of an operon involved in benzoate catabolism regulated by benR. Within this operon, benK, benE, and benF genes have been suggested to contribute toward either influx or efflux

  15. Subtilase SprP exerts pleiotropic effects in Pseudomonas aeruginosa

    PubMed Central

    Pelzer, Alexander; Polen, Tino; Funken, Horst; Rosenau, Frank; Wilhelm, Susanne; Bott, Michael; Jaeger, Karl-Erich

    2014-01-01

    The open reading frame PA1242 in the genome of Pseudomonas aeruginosa PAO1 encodes a putative protease belonging to the peptidase S8 family of subtilases. The respective enzyme termed SprP consists of an N-terminal signal peptide and a so-called S8 domain linked by a domain of unknown function (DUF). Presumably, this DUF domain defines a discrete class of Pseudomonas proteins as homologous domains can be identified almost exclusively in proteins of the genus Pseudomonas. The sprP gene was expressed in Escherichia coli and proteolytic activity was demonstrated. A P. aeruginosa ΔsprP mutant was constructed and its gene expression pattern compared to the wild-type strain by genome microarray analysis revealing altered expression levels of 218 genes. Apparently, SprP is involved in regulation of a variety of different cellular processes in P. aeruginosa including pyoverdine synthesis, denitrification, the formation of cell aggregates, and of biofilms. PMID:24376018

  16. Subtilase SprP exerts pleiotropic effects in Pseudomonas aeruginosa.

    PubMed

    Pelzer, Alexander; Polen, Tino; Funken, Horst; Rosenau, Frank; Wilhelm, Susanne; Bott, Michael; Jaeger, Karl-Erich

    2014-02-01

    The open reading frame PA1242 in the genome of Pseudomonas aeruginosa PAO1 encodes a putative protease belonging to the peptidase S8 family of subtilases. The respective enzyme termed SprP consists of an N-terminal signal peptide and a so-called S8 domain linked by a domain of unknown function (DUF). Presumably, this DUF domain defines a discrete class of Pseudomonas proteins as homologous domains can be identified almost exclusively in proteins of the genus Pseudomonas. The sprP gene was expressed in Escherichia coli and proteolytic activity was demonstrated. A P. aeruginosa ∆sprP mutant was constructed and its gene expression pattern compared to the wild-type strain by genome microarray analysis revealing altered expression levels of 218 genes. Apparently, SprP is involved in regulation of a variety of different cellular processes in P. aeruginosa including pyoverdine synthesis, denitrification, the formation of cell aggregates, and of biofilms.

  17. Genetic Control of Plant Root Colonization by the Biocontrol agent, Pseudomonas fluorescens

    SciTech Connect

    Cole, Benjamin J.; Fletcher, Meghan; Waters, Jordan; Wetmore, Kelly; Blow, Matthew J.; Deutschbauer, Adam M.; Dangl, Jeffry L.; Visel, Axel

    2015-03-19

    Plant growth promoting rhizobacteria (PGPR) are a critical component of plant root ecosystems. PGPR promote plant growth by solubilizing inaccessible minerals, suppressing pathogenic microorganisms in the soil, and directly stimulating growth through hormone synthesis. Pseudomonas fluorescens is a well-established PGPR isolated from wheat roots that can also colonize the root system of the model plant, Arabidopsis thaliana. We have created barcoded transposon insertion mutant libraries suitable for genome-wide transposon-mediated mutagenesis followed by sequencing (TnSeq). These libraries consist of over 105 independent insertions, collectively providing loss-of-function mutants for nearly all genes in the P.fluorescens genome. Each insertion mutant can be unambiguously identified by a randomized 20 nucleotide sequence (barcode) engineered into the transposon sequence. We used these libraries in a gnotobiotic assay to examine the colonization ability of P.fluorescens on A.thaliana roots. Taking advantage of the ability to distinguish individual colonization events using barcode sequences, we assessed the timing and microbial concentration dependence of colonization of the rhizoplane niche. These data provide direct insight into the dynamics of plant root colonization in an in vivo system and define baseline parameters for the systematic identification of the bacterial genes and molecular pathways using TnSeq assays. Having determined parameters that facilitate potential colonization of roots by thousands of independent insertion mutants in a single assay, we are currently establishing a genome-wide functional map of genes required for root colonization in P.fluorescens. Importantly, the approach developed and optimized here for P.fluorescens>A.thaliana colonization will be applicable to a wide range of plant-microbe interactions, including biofuel feedstock plants and microbes known or hypothesized to impact on biofuel-relevant traits including biomass productivity

  18. Anionic fluoroquinolones as antibacterials against biofilm-producing Pseudomonas aeruginosa.

    PubMed

    Long, Timothy E; Keding, Lexie C; Lewis, Demetria D; Anstead, Michael I; Withers, T Ryan; Yu, Hongwei D

    2016-02-15

    Pseudomonas aeruginosa is a common biofilm-forming bacterial pathogen implicated in diseases of the lungs. The extracellular polymeric substances (EPS) of respiratory Pseudomonas biofilms are largely comprised of anionic molecules such as rhamnolipids and alginate that promote a mucoid phenotype. In this Letter, we examine the ability of negatively-charged fluoroquinolones to transverse the EPS and inhibit the growth of mucoid P. aeruginosa. Anionic fluoroquinolones were further compared with standard antibiotics via a novel microdiffusion assay to evaluate drug penetration through pseudomonal alginate and respiratory mucus from a patient with cystic fibrosis.

  19. Mechanism of resistance to benzalkonium chloride by Pseudomonas aeruginosa.

    PubMed

    Sakagami, Y; Yokoyama, H; Nishimura, H; Ose, Y; Tashima, T

    1989-08-01

    The mechanisms of resistance of Pseudomonas aeruginosa to benzalkonium chloride (BC) were studied. The effluence of cell components was observed in susceptible P. aeruginosa by electron microscopy, but resistant P. aeruginosa seemed to be undamaged. No marked changes in cell surface potential between Escherichia coli NIHJC-2 and a spheroplast strain were found. The contents of phospholipids (PL) and fatty and neutral lipids (FNL) in the cell walls of resistant P. aeruginosa were higher than those in the cell walls of susceptible P. aeruginosa. The amounts of BC adsorbed to PL and FNL of cell walls of BC-resistant P. aeruginosa were lower than those for BC-susceptible P. aeruginosa. Fifteen species of cellular fatty acids were identified by capillary gas chromatography and gas chromatography-mass spectrometry. The ability of BC to permeate the cell wall was reduced because of the increase in cellular fatty acids. These results suggested that the resistance of P. aeruginosa to BC is mainly a result of increased in the contents of PL and FNL. In resistant P. aeruginosa, the decrease in the amount of BC adsorbed is likely to be the result of increases in the contents of PL and FNL.

  20. Mechanism of resistance to benzalkonium chloride by Pseudomonas aeruginosa.

    PubMed Central

    Sakagami, Y; Yokoyama, H; Nishimura, H; Ose, Y; Tashima, T

    1989-01-01

    The mechanisms of resistance of Pseudomonas aeruginosa to benzalkonium chloride (BC) were studied. The effluence of cell components was observed in susceptible P. aeruginosa by electron microscopy, but resistant P. aeruginosa seemed to be undamaged. No marked changes in cell surface potential between Escherichia coli NIHJC-2 and a spheroplast strain were found. The contents of phospholipids (PL) and fatty and neutral lipids (FNL) in the cell walls of resistant P. aeruginosa were higher than those in the cell walls of susceptible P. aeruginosa. The amounts of BC adsorbed to PL and FNL of cell walls of BC-resistant P. aeruginosa were lower than those for BC-susceptible P. aeruginosa. Fifteen species of cellular fatty acids were identified by capillary gas chromatography and gas chromatography-mass spectrometry. The ability of BC to permeate the cell wall was reduced because of the increase in cellular fatty acids. These results suggested that the resistance of P. aeruginosa to BC is mainly a result of increased in the contents of PL and FNL. In resistant P. aeruginosa, the decrease in the amount of BC adsorbed is likely to be the result of increases in the contents of PL and FNL. Images PMID:2506813

  1. Novel Lectin-Like Bacteriocins of Biocontrol Strain Pseudomonas fluorescens Pf-5

    PubMed Central

    Parret, Annabel H. A.; Temmerman, Koen; De Mot, René

    2005-01-01

    Bacteriocin LlpA, produced by Pseudomonas sp. strain BW11M1, is a peculiar antibacterial protein due to its homology to mannose-binding lectins mostly found in monocots (A. H. A. Parret, G. Schoofs, P. Proost, and R. De Mot, J. Bacteriol. 185:897-908, 2003). Biocontrol strain Pseudomonas fluorescens Pf-5 contains two llpA-like genes, named llpA1Pf-5 and llpA2Pf-5. Recombinant Escherichia coli cells expressing llpA1Pf-5 or llpA2Pf-5 acquired bacteriocin activity and secreted a 31-kDa protein cross-reacting with LlpABW11M1 antibodies. Antibacterial activity of the recombinant proteins was evidenced by gel overlay assays. Analysis of the antimicrobial spectrum indicated that LlpA1Pf-5 and LlpA2Pf-5 are able to inhibit P. fluorescens strains, as well as the related mushroom pathogen Pseudomonas tolaasii. LlpA-type bacteriocins are characterized by a domain structure consisting of tandem monocot mannose-binding lectin (MMBL) domains. Molecular phylogeny of these MMBL domains suggests that the individual MMBL domains within an LlpA protein have evolved separately toward a specific, as yet unknown, function or, alternatively, were acquired from different ancestral sources. Our observations are consistent with earlier observations, which hinted that MMBL-like bacteriocins represent a new family of antibacterial proteins, probably with a novel mode of action. PMID:16151105

  2. Cyclic Di-GMP-Regulated Periplasmic Proteolysis of a Pseudomonas aeruginosa Type Vb Secretion System Substrate

    PubMed Central

    Cooley, Richard B.; Smith, T. Jarrod; Leung, Wilfred; Tierney, Valerie; Borlee, Bradley R.; O'Toole, George A.

    2015-01-01

    ABSTRACT We previously identified a second-messenger-regulated signaling system in the environmental bacterium Pseudomonas fluorescens which controls biofilm formation in response to levels of environmental inorganic phosphate. This system contains the transmembrane cyclic di-GMP (c-di-GMP) receptor LapD and the periplasmic protease LapG. LapD regulates LapG and controls the ability of this protease to process a large cell surface adhesin protein, LapA. While LapDG orthologs can be identified in diverse bacteria, predictions of LapG substrates are sparse. Notably, the opportunistic pathogen Pseudomonas aeruginosa harbors LapDG orthologs, but neither the substrate of LapG nor any associated secretion machinery has been identified to date. Here, we identified P. aeruginosa CdrA, a protein known to mediate cell-cell aggregation and biofilm maturation, as a substrate of LapG. We also demonstrated LapDG to be a minimal system sufficient to control CdrA localization in response to changes in the intracellular concentration of c-di-GMP. Our work establishes this biofilm signaling node as a regulator of a type Vb secretion system substrate in a clinically important pathogen. IMPORTANCE Here, the biological relevance of a conserved yet orphan signaling system in the opportunistic pathogen Pseudomonas aeruginosa is revealed. In particular, we identified the adhesin CdrA, the cargo of a two-partner secretion system, as a substrate of a periplasmic protease whose activity is controlled by intracellular c-di-GMP levels and a corresponding transmembrane receptor via an inside-out signaling mechanism. The data indicate a posttranslational control mechanism of CdrA via c-di-GMP, in addition to its established transcriptional regulation via the same second messenger. PMID:26100041

  3. Analysis of cumene (isopropylbenzene) degradation genes from Pseudomonas fluorescens IP01.

    PubMed

    Habe, H; Kasuga, K; Nojiri, H; Yamane, H; Omori, T

    1996-12-01

    We obtained the DNA fragments encoding 2-hydroxy-6-oxo-7-methylocta-2,4-dienoic acid (HOMODA) hydrolase in the cumene (isopropylbenzene) degrader Pseudomonas fluorescens strain IP01 via PCR using two synthesized oligonucleotides corresponding to the conserved regions within known meta-cleavage compound hydrolases. Following colony hybridization using the amplified DNA as a probe, a 4.5-kb HindIII fragment was isolated from P. fluorescens IP01. After determining the nucleotide sequence of this fragment, three open reading frames (ORF11 [cumH], ORF12 [cumD], and ORF13) were identified. The deduced amino acid sequence of ORF12 showed homology with meta-cleavage compound hydrolases encoded by the tod, dmp, xyl, and bph operons. Although the product of ORF12 was found to exhibit HOMODA and 2-hydroxy-6-oxohepta-2,4-dienoic acid (HOHDA) hydrolase activities, it did not exhibit 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) hydrolase activity. The deduced amino acid sequence of ORF11 showed 40.4% homology with the sequence of todX in Pseudomonas putida F1 (Y. Wang, M. Ralings, D. T. Gibson, D. Labbé, H. Bergeron, R. Brousseau, and P. C. K. Lau, Mol. Gen. Genet. 246:570-579, 1995). The nucleotide sequence of ORF13 and its flanking region showed strong homology (91.0%) with IS52 from Pseudomonas savastanoi (Y. Yamada, P.-D. Lee, and T. Kosuge, Proc. Natl. Acad. Sci. USA 83:8263-8267, 1982). By characterization of cumH and cumD, the entire cum gene cluster from the cumene-degrader P. fluorescens IP01 (cumA1A2A3A4BCEGFHD) has been identified.

  4. Draft Genome Sequence of Pseudomonas fluorescens LMG 5329, a White Line-Inducing Principle-Producing Bioindicator for the Mushroom Pathogen Pseudomonas tolaasii

    PubMed Central

    Rokni-Zadeh, Hassan; Zarrineh, Peyman

    2013-01-01

    Pseudomonas tolaasii, the causative agent of Agaricus bisporus brown blotch disease, can be identified by the white line reaction, occurring upon confrontation of the tolaasin-producing mushroom pathogen with “Pseudomonas reactans,” producing the lipopeptide white line-inducing principle (WLIP). The draft genome sequence of the WLIP-producing indicator Pseudomonas fluorescens strain LMG 5329 is reported here. PMID:23887909

  5. Biodegradation of didecyldimethylammonium chloride by Pseudomonas fluorescens TN4 isolated from activated sludge.

    PubMed

    Nishihara, T; Okamoto, T; Nishiyama, N

    2000-04-01

    Bacteria that degrade didecyldimethylammonium chloride (DDAC) were isolated from activated sludge from a municipal sewage treatment plant by enrichment culture with DDAC as a sole carbon source. One of the isolates, Pseudomonas fluorescens TN4, degraded DDAC to produce decyldimethylamine and subsequently, dimethylamine, as the intermediates. The TN4 strain also assimilated the other quaternary ammonium compounds (QACs), alkyltrimethyl- and alkylbenzyldimethyl-ammonium salts, but not alkylpyridinium salts. TN4 was highly resistant to these QACs and degraded them by an N-dealkylation process. These data mean that there are some QAC-resistant and QAC-degrading bacteria such as TN4 in the environment.

  6. Mechanism of chromium detoxification in Pseudomonas fluorescens is dependent on iron

    SciTech Connect

    Appanna, V.D.; Huang, J.; St. Pierre, M.

    1996-12-01

    Biotechnology may provide an efficient and environmentally friendly route to the management of industrial wastes. Microbes in particular, owing to their ability to proliferate in most ecological niches, can be engineered for the immobilization of metal pollutants. The utilization of chromium in steel production, wood preservation, leather tanning, paints and pigments has led to a sharp increase of this metal in the environment where it occurs primarily in trivalent or hexavalent forms. In trace amounts chromium is considered an essential nutrient for numerous organisms; in elevated concentrations it is toxic and mutagenic. This study investigated the interaction of Chromium (III) on the soil bacterium Pseudomonas fluorescens. 17 refs., 3 figs.

  7. Effect of extra aeration on extracellular enzyme activities and ATP concentration of dairy Pseudomonas fluorescens.

    PubMed

    Jaspe, A; Palacios, P; Fernández, L; Sanjosé, C

    2000-03-01

    The effect of forced aeration on extracellular enzyme synthesis during batch growth of a Pseudomonas fluorescens strain of dairy origin on pyruvate mineral salts medium at 7 degrees C was studied. Measurement of oxygen tension, electron micrographs to estimate cell volume, luciferase determination of ATP and plate counts were performed in the course of incubation. Cells from the stationary phase of growth had lower energy status (in terms of intracellular ATP concentration) in the cultures receiving surplus aeration. Those cells produced three times more extracellular proteinase and lipase than control cells. Onset time for production of both enzymes coincided with a sharp fall of intracellular ATP levels.

  8. Impact of a Recombinant Biocontrol Bacterium, Pseudomonas fluorescens pc78, on Microbial Community in Tomato Rhizosphere

    PubMed Central

    Kong, Hyun Gi; Kim, Nam Hee; Lee, Seung Yeup; Lee, Seon-Woo

    2016-01-01

    Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer. PMID:27147933

  9. Metabolic functions of Pseudomonas fluorescens strains from Populus deltoides depend on rhizosphere or endosphere isolation compartment

    PubMed Central

    Timm, Collin M.; Campbell, Alisha G.; Utturkar, Sagar M.; Jun, Se-Ran; Parales, Rebecca E.; Tan, Watumesa A.; Robeson, Michael S.; Lu, Tse-Yuan S.; Jawdy, Sara; Brown, Steven D.; Ussery, David W.; Schadt, Christopher W.; Tuskan, Gerald A.; Doktycz, Mitchel J.; Weston, David J.; Pelletier, Dale A.

    2015-01-01

    The bacterial microbiota of plants is diverse, with 1000s of operational taxonomic units (OTUs) associated with any individual plant. In this work, we used phenotypic analysis, comparative genomics, and metabolic models to investigate the differences between 19 sequenced Pseudomonas fluorescens strains. These isolates represent a single OTU and were collected from the rhizosphere and endosphere of Populus deltoides. While no traits were exclusive to either endosphere or rhizosphere P. fluorescens isolates, multiple pathways relevant for plant-bacterial interactions are enriched in endosphere isolate genomes. Further, growth phenotypes such as phosphate solubilization, protease activity, denitrification and root growth promotion are biased toward endosphere isolates. Endosphere isolates have significantly more metabolic pathways for plant signaling compounds and an increased metabolic range that includes utilization of energy rich nucleotides and sugars, consistent with endosphere colonization. Rhizosphere P. fluorescens have fewer pathways representative of plant-bacterial interactions but show metabolic bias toward chemical substrates often found in root exudates. This work reveals the diverse functions that may contribute to colonization of the endosphere by bacteria and are enriched among closely related isolates. PMID:26528266

  10. Early gene expression in Pseudomonas fluorescens exposed to a polymetallic solution.

    PubMed

    Gómez-Sagasti, María T; Becerril, José M; Epelde, Lur; Alkorta, Itziar; Garbisu, Carlos

    2015-02-01

    The molecular response of Pseudomonas fluorescens cells exposed to a mixture of heavy metals remains largely unknown. Here, we studied the temporal changes in the early gene expression of P. fluorescens cells exposed to three doses of a polymetallic solution over two exposure times, through the application of a customized cDNA microarray. At the lowest metal dose (MD/4), we observed a repression of the Hsp70 chaperone system, MATE and MFS transporters, TonB membrane transporter and histidine kinases, together with an overexpression of metal transport (ChaC, CopC), chemotaxis and glutamine synthetase genes. At the intermediate metal dose (MD), several amino acid transporters, a response regulator (CheY), a TonB-dependent receptor and the mutT DNA repair gene were repressed; by contrast, an overexpression of genes associated with the antioxidative stress system and the transport of chelates and sulfur was observed. Finally, at the highest metal dose (4MD), a repression of genes encoding metal ion transporters, drug resistance and alginate biosynthesis was found, together with an overexpression of genes encoding antioxidative proteins, membrane transporters, ribosomal proteins, chaperones and proteases. It was concluded that P. fluorescens cells showed, over exposure time, a highly complex molecular response when exposed to a polymetallic solution, involving mechanisms related with chemotaxis, signal transmission, membrane transport, cellular redox state, and the regulation of transcription and ribosomal activity.

  11. Metabolic functions of Pseudomonas fluorescens strains from Populus deltoides depend on rhizosphere or endosphere isolation compartment

    SciTech Connect

    Timm, Collin M.; Campbell, Alicia G.; Utturkar, Sagar M.; Jun, Se Ran; Parales, Rebecca E.; Tan, Mesa; Robeson, Michael S.; Lu, Tse-Yuan S.; Jawdy, Sara; Schadt, Christopher Warren; Doktycz, Mitchel John; Weston, David; Pelletier, Dale A.

    2015-10-14

    The bacterial microbiota of plants is diverse, with ~1000s of operational taxonomic units (OTUs) associated with any individual plant. In this work we investigate how 19 sequenced Pseudomonas fluorescens strains representing a single OTU isolated from Populus deltoides rhizosphere and endosphere differ using phenotypic analysis, comparative genomics, and metabolic models. While no traits were exclusive to either endosphere or rhizosphere P. fluorescens isolates, multiple pathways relevant for bacterial-plant interactions are enriched in endosphere isolate genomes and growth phenotypes such as phosphate solubilization, protease activity, denitrification and root growth promotion are biased towards endosphere isolates. Endosphere isolates have more metabolic pathways for plant signaling compounds and an increased metabolic range that includes utilization of energy rich nucleotides and sugars, consistent with endosphere colonization. Rhizosphere P. fluorescens have fewer pathways important for bacterial-plant interactions but show metabolic bias towards chemical substrates often found in root exudates. This work reveals the diverse functions that may contribute to colonization of the endosphere by bacteria that are enriched in event he most closely related isolates.

  12. Tracking the blue: a MLST approach to characterise the Pseudomonas fluorescens group.

    PubMed

    Andreani, N A; Martino, M E; Fasolato, L; Carraro, L; Montemurro, F; Mioni, R; Bordin, P; Cardazzo, B

    2014-05-01

    The Pseudomonas fluorescens group comprises several closely related species that are involved in food contamination and spoilage. Specifically, the interest in P. fluorescens as a spoiler of dairy products increased after the cases of "blue mozzarella" that occurred in Italy in 2010. A Multilocus Sequence Typing (MLST) scheme was developed and applied to characterise 136 isolates (reference strains and food borne isolates) at strain level, to reveal the genetic relationships among them and to disclose any possible genetic clustering of phenotypic markers involved in food spoilage (protease, lipase, lecithinase activities and pigmented or fluorescent molecule production). The production of dark blue diffusible pigment was evaluated on several bacterial culture media and directly on mozzarella cheese. The MLST scheme provided precise genotyping at the strain level, and the population analyses of the concatenated sequences allowed major taxa to be defined. This approach was revealed to be suitable for tracking the strains according to their origin, such as dairy plants or food matrices. The genetic analysis revealed the presence of a connection between the blue pigment production and a specific phylogenetic cluster. The development of the online database specific to the P. fluorescens group (http://pubmlst.org/pfluorescens) will facilitate the application of the scheme and the sharing of the data.

  13. Metabolic functions of Pseudomonas fluorescens strains from Populus deltoides depend on rhizosphere or endosphere isolation compartment

    DOE PAGES

    Timm, Collin M.; Campbell, Alicia G.; Utturkar, Sagar M.; ...

    2015-10-14

    The bacterial microbiota of plants is diverse, with ~1000s of operational taxonomic units (OTUs) associated with any individual plant. In this work we investigate how 19 sequenced Pseudomonas fluorescens strains representing a single OTU isolated from Populus deltoides rhizosphere and endosphere differ using phenotypic analysis, comparative genomics, and metabolic models. While no traits were exclusive to either endosphere or rhizosphere P. fluorescens isolates, multiple pathways relevant for bacterial-plant interactions are enriched in endosphere isolate genomes and growth phenotypes such as phosphate solubilization, protease activity, denitrification and root growth promotion are biased towards endosphere isolates. Endosphere isolates have more metabolic pathwaysmore » for plant signaling compounds and an increased metabolic range that includes utilization of energy rich nucleotides and sugars, consistent with endosphere colonization. Rhizosphere P. fluorescens have fewer pathways important for bacterial-plant interactions but show metabolic bias towards chemical substrates often found in root exudates. This work reveals the diverse functions that may contribute to colonization of the endosphere by bacteria that are enriched in event he most closely related isolates.« less

  14. Pseudomonas Aeruginosa Endocarditis in Acute Myeloid Leukemia: A Rare Complication

    PubMed Central

    J, Barshay; A, Nemets; A, Ducach; G, Lugassy

    2008-01-01

    Infectious endocarditis is a rarely encountered complication among leukemia patient during induction therapy. We describe a young patient who developed prolonged high fever after aggressive chemotherapy for Acute Myeloid Leukemia. Pseudomonas Aeruginosa endocarditis was found to be the etiology for the febrile state. Our purpose is to emphasize the need for an early diagnosis of this rare, albeit treatable complication. PMID:23675106

  15. Pseudomonas aeruginosa sepsis in stem cell transplantation patients.

    PubMed

    Fanci, Rosa; Pecile, Patrizia; Casalone, Enrico; Mengoni, Alessio; Tamburini, Elena; Guidi, Stefano; Cecconi, Daniela; Bosi, Alberto; Nicoletti, Pierluigi; Mastromei, Giorgio

    2006-07-01

    We report the epidemiological investigation of an outbreak of Pseudomonas aeruginosa infection in 6 patients who shared, during different periods, the same 2 rooms of a bone marrow transplantation unit. Phenotypic and molecular analysis of isolates from patients and from the environment strongly suggested a single, environmental source of infection.

  16. Production of mucoid exopolysaccharide during development of Pseudomonas aeruginosa biofilms.

    PubMed Central

    Hoyle, B D; Williams, L J; Costerton, J W

    1993-01-01

    Production of mucoid exopolysaccharide by planktonic, chemostat-derived, and adherent Pseudomonas aeruginosa 579 bacteria was separately monitored for 7 days by using a lacZ-algD promoter-reporter gene and assays of total carbohydrate and metabolic activity. Mucoid exopolysaccharide production was transiently elevated following adherence but declined to planktonic levels by day 7. PMID:8423105

  17. A genomic and transcriptomic approach to investigate the blue pigment phenotype in Pseudomonas fluorescens.

    PubMed

    Andreani, Nadia Andrea; Carraro, Lisa; Martino, Maria Elena; Fondi, Marco; Fasolato, Luca; Miotto, Giovanni; Magro, Massimiliano; Vianello, Fabio; Cardazzo, Barbara

    2015-11-20

    Pseudomonas fluorescens is a well-known food spoiler, able to cause serious economic losses in the food industry due to its ability to produce many extracellular, and often thermostable, compounds. The most outstanding spoilage events involving P. fluorescens were blue discoloration of several food stuffs, mainly dairy products. The bacteria involved in such high-profile cases have been identified as belonging to a clearly distinct phylogenetic cluster of the P. fluorescens group. Although the blue pigment has recently been investigated in several studies, the biosynthetic pathway leading to the pigment formation, as well as its chemical nature, remain challenging and unsolved points. In the present paper, genomic and transcriptomic data of 4 P. fluorescens strains (2 blue-pigmenting strains and 2 non-pigmenting strains) were analyzed to evaluate the presence and the expression of blue strain-specific genes. In particular, the pangenome analysis showed the presence in the blue-pigmenting strains of two copies of genes involved in the tryptophan biosynthesis pathway (including trpABCDF). The global expression profiling of blue-pigmenting strains versus non-pigmenting strains showed a general up-regulation of genes involved in iron uptake and a down-regulation of genes involved in primary metabolism. Chromogenic reaction of the blue-pigmenting bacterial cells with Kovac's reagent indicated an indole-derivative as the precursor of the blue pigment. Finally, solubility tests and MALDI-TOF mass spectrometry analysis of the isolated pigment suggested that its molecular structure is very probably a hydrophobic indigo analog.

  18. Pseudomonas fluorescens pirates both ferrioxamine and ferricoelichelin siderophores from Streptomyces ambofaciens.

    PubMed

    Galet, Justine; Deveau, Aurélie; Hôtel, Laurence; Frey-Klett, Pascale; Leblond, Pierre; Aigle, Bertrand

    2015-05-01

    Iron is essential in many biological processes. However, its bioavailability is reduced in aerobic environments, such as soil. To overcome this limitation, microorganisms have developed different strategies, such as iron chelation by siderophores. Some bacteria have even gained the ability to detect and utilize xenosiderophores, i.e., siderophores produced by other organisms. We illustrate an example of such an interaction between two soil bacteria, Pseudomonas fluorescens strain BBc6R8 and Streptomyces ambofaciens ATCC 23877, which produce the siderophores pyoverdine and enantiopyochelin and the siderophores desferrioxamines B and E and coelichelin, respectively. During pairwise cultures on iron-limiting agar medium, no induction of siderophore synthesis by P. fluorescens BBc6R8 was observed in the presence of S. ambofaciens ATCC 23877. Cocultures with a Streptomyces mutant strain that produced either coelichelin or desferrioxamines, as well as culture in a medium supplemented with desferrioxamine B, resulted in the absence of pyoverdine production; however, culture with a double mutant deficient in desferrioxamines and coelichelin production did not. This strongly suggests that P. fluorescens BBbc6R8 utilizes the ferrioxamines and ferricoelichelin produced by S. ambofaciens as xenosiderophores and therefore no longer activates the production of its own siderophores. A screening of a library of P. fluorescens BBc6R8 mutants highlighted the involvement of the TonB-dependent receptor FoxA in this process: the expression of foxA and genes involved in the regulation of its biosynthesis was induced in the presence of S. ambofaciens. In a competitive environment, such as soil, siderophore piracy could well be one of the driving forces that determine the outcome of microbial competition.

  19. Transcriptional and antagonistic responses of Pseudomonas fluorescens Pf0-1 to phylogenetically different bacterial competitors

    PubMed Central

    Garbeva, Paolina; Silby, Mark W; Raaijmakers, Jos M; Levy, Stuart B; Boer, Wietse de

    2011-01-01

    The ability of soil bacteria to successfully compete with a range of other microbial species is crucial for their growth and survival in the nutrient-limited soil environment. In the present work, we studied the behavior and transcriptional responses of soil-inhabiting Pseudomonas fluorescens strain Pf0-1 on nutrient-poor agar to confrontation with strains of three phylogenetically different bacterial genera, that is, Bacillus, Brevundimonas and Pedobacter. Competition for nutrients was apparent as all three bacterial genera had a negative effect on the density of P. fluorescens Pf0-1; this effect was most strong during the interaction with Bacillus. Microarray-based analyses indicated strong differences in the transcriptional responses of Pf0-1 to the different competitors. There was higher similarity in the gene expression response of P. fluorescens Pf0-1 to the Gram-negative bacteria as compared with the Gram-positive strain. The Gram-negative strains did also trigger the production of an unknown broad-spectrum antibiotic in Pf0-1. More detailed analysis indicated that expression of specific Pf0-1 genes involved in signal transduction and secondary metabolite production was strongly affected by the competitors' identity, suggesting that Pf0-1 can distinguish among different competitors and fine-tune its competitive strategies. The results presented here demonstrate that P. fluorescens Pf0-1 shows a species-specific transcriptional and metabolic response to bacterial competitors and provide new leads in the identification of specific cues in bacteria–bacteria interactions and of novel competitive strategies, antimicrobial traits and genes. PMID:21228890

  20. Antimicrobial action of essential oil vapours and negative air ions against Pseudomonas fluorescens.

    PubMed

    Tyagi, A K; Malik, A

    2010-10-15

    The aim of this study was to investigate the antibacterial activity of essential oil (in liquid as well as in vapour phase) and negative air ions (NAI) against Pseudomonas fluorescens. The combined effect of NAI with essential oil vapour was also investigated to determine kill time and morphological changes in bacterial cells. The MIC of Cymbopogon citratus (0.567 mg/ml), Mentha arvensis (0.567 mg/ml), Mentha piperita (1.125 mg/ml) and Eucalyptus globulus (2.25 mg/ml) was studied via the agar dilution method. To estimate the antibacterial activity of essential oils in the vapour phase, agar plates inoculated with P. fluorescens were incubated with various concentrations of each essential oil vapour and zone of inhibition was recorded. Further, in order to assess the kill time, P. fluorescens inoculated agar plates were exposed to selected bactericidal essential oil vapour and NAI, separately, in an air-tight chamber. A continuous decrease in bacterial count was observed over time. A significant enhancement in the bactericidal action was observed by exposure to the combination of essential oil vapour and NAI as compared to their individual action. Scanning electron microscopy was used to study the alteration in morphology of P. fluorescens cells after exposure to C. citratus oil vapour, NAI, and combination of C. citratus oil vapour and NAI. Maximum morphological deformation was found due to the combined effect of C. citratus oil vapour and NAI. This study demonstrates that the use of essential oils in the vapour phase is more advantageous than the liquid phase. Further the antibacterial effect of the essential oil vapours can be significantly enhanced by the addition of NAI. The work described here offers a novel and efficient approach for control of bacterial contamination that could be applied for food stabilization practices.

  1. Transition from reversible to irreversible attachment during biofilm formation by Pseudomonas fluorescens WCS365 requires an ABC transporter and a large secreted protein.

    PubMed

    Hinsa, Shannon M; Espinosa-Urgel, Manuel; Ramos, Juan L; O'Toole, George A

    2003-08-01

    We report the identification of an ATP-binding cassette (ABC) transporter and an associated large cell-surface protein that are required for biofilm formation by Pseudomonas fluorescens WCS365. The genes coding for these proteins are designated lap for large adhesion protein. The LapA protein, with a predicted molecular weight of approximately 900 kDa, is found to be loosely associated with the cell surface and present in the culture supernatant. The LapB, LapC and LapE proteins are predicted to be the cytoplasmic membrane-localized ATPase, membrane fusion protein and outer membrane protein component, respectively, of an ABC transporter. Consistent with this prediction, LapE, like other members of this family, is localized to the outer membrane. We propose that the lapEBC-encoded ABC transporter participates in the secretion of LapA, as strains with mutations in the lapEBC genes do not have detectable LapA associated with the cell surface or in the supernatant. The lap genes are conserved among environmental pseudomonads such as P. putida KT2440, P. fluorescens PfO1 and P. fluorescens WCS365, but are absent from pathogenic pseudomonads such as P. aeruginosa and P. syringae. The wild-type strain of P. fluorescens WCS365 and its lap mutant derivatives were assessed for their biofilm forming ability in static and flow systems. The lap mutant strains are impaired in an early step in biofilm formation and are unable to develop the mature biofilm structure seen for the wild-type bacterium. Time-lapse microscopy studies determined that the lap mutants are unable to progress from reversible (or transient) attachment to the irreversible attachment stage of biofilm development. The lap mutants were also found to be defective in attachment to quartz sand, an abiotic surface these organisms likely encounter in the environment.

  2. Study of the Population Dynamics of Listeria Monocytogenes and Pseudomonas Fluorescens in Buffalo Mozzarella by Means of Challenge Testing.

    PubMed

    Nava, Donatella; Capo, Salvatore; Caligiuri, Vincenzo; Giaccone, Valerio; Biondi, Loredana; Vaccaro, Gerardo Francesco; Guarino, Achille; Capuano, Federico

    2016-06-03

    Campania's buffalo mozzarella is a greatly appreciated cheese in Italy and worldwide. From a microbiological standpoint, it is a highly perishable food and potentially at risk of contamination by pathogens such as Listeria monocytogenes (L. monocytogenes). The present paper reports the results of a challenge test carried out to assess the population dynamics of L. monocytogenes, alone and in presence of Pseudomonas fluorescens (P. fluorescens), in buffalo mozzarella. For this purpose buffalo mozzarella samples were contaminated with L. monocytogenes alone or combined with P. fluorescens. In samples where L. monocytogenes was inoculated alone, the bacterial load remained unchanged. On the contrary, in samples contaminated with L. monocytogenes and P. fluorescens, the growth of L. monocytogenes increased.

  3. Study of the Population Dynamics of Listeria Monocytogenes and Pseudomonas Fluorescens in Buffalo Mozzarella by Means of Challenge Testing

    PubMed Central

    Nava, Donatella; Capo, Salvatore; Caligiuri, Vincenzo; Giaccone, Valerio; Biondi, Loredana; Vaccaro, Gerardo Francesco; Guarino, Achille; Capuano, Federico

    2016-01-01

    Campania’s buffalo mozzarella is a greatly appreciated cheese in Italy and worldwide. From a microbiological standpoint, it is a highly perishable food and potentially at risk of contamination by pathogens such as Listeria monocytogenes (L. monocytogenes). The present paper reports the results of a challenge test carried out to assess the population dynamics of L. monocytogenes, alone and in presence of Pseudomonas fluorescens (P. fluorescens), in buffalo mozzarella. For this purpose buffalo mozzarella samples were contaminated with L. monocytogenes alone or combined with P. fluorescens. In samples where L. monocytogenes was inoculated alone, the bacterial load remained unchanged. On the contrary, in samples contaminated with L. monocytogenes and P. fluorescens, the growth of L. monocytogenes increased. PMID:27853707

  4. Characterization of the biocontrol activity of pseudomonas fluorescens strain X reveals novel genes regulated by glucose.

    PubMed

    Kremmydas, Gerasimos F; Tampakaki, Anastasia P; Georgakopoulos, Dimitrios G

    2013-01-01

    Pseudomonas fluorescens strain X, a bacterial isolate from the rhizosphere of bean seedlings, has the ability to suppress damping-off caused by the oomycete Pythium ultimum. To determine the genes controlling the biocontrol activity of strain X, transposon mutagenesis, sequencing and complementation was performed. Results indicate that, biocontrol ability of this isolate is attributed to gcd gene encoding glucose dehydrogenase, genes encoding its co-enzyme pyrroloquinoline quinone (PQQ), and two genes (sup5 and sup6) which seem to be organized in a putative operon. This operon (named supX) consists of five genes, one of which encodes a non-ribosomal peptide synthase. A unique binding site for a GntR-type transcriptional factor is localized upstream of the supX putative operon. Synteny comparison of the genes in supX revealed that they are common in the genus Pseudomonas, but with a low degree of similarity. supX shows high similarity only to the mangotoxin operon of Ps. syringae pv. syringae UMAF0158. Quantitative real-time PCR analysis indicated that transcription of supX is strongly reduced in the gcd and PQQ-minus mutants of Ps. fluorescens strain X. On the contrary, transcription of supX in the wild type is enhanced by glucose and transcription levels that appear to be higher during the stationary phase. Gcd, which uses PQQ as a cofactor, catalyses the oxidation of glucose to gluconic acid, which controls the activity of the GntR family of transcriptional factors. The genes in the supX putative operon have not been implicated before in the biocontrol of plant pathogens by pseudomonads. They are involved in the biosynthesis of an antimicrobial compound by Ps. fluorescens strain X and their transcription is controlled by glucose, possibly through the activity of a GntR-type transcriptional factor binding upstream of this putative operon.

  5. Predictive modeling of Pseudomonas fluorescens growth under different temperature and pH values.

    PubMed

    Gonçalves, Letícia Dias Dos Anjos; Piccoli, Roberta Hilsdorf; Peres, Alexandre de Paula; Saúde, André Vital

    Meat is one of the most perishable foods owing to its nutrient availability, high water activity, and pH around 5.6. These properties are highly conducive for microbial growth. Fresh meat, when exposed to oxygen, is subjected to the action of aerobic psychrotrophic, proteolytic, and lipolytic spoilage microorganisms, such as Pseudomonas spp. The spoilage results in the appearance of slime and off-flavor in food. In order to predict the growth of Pseudomonas fluorescens in fresh meat at different pH values, stored under refrigeration, and temperature abuse, microbial mathematical modeling was applied. The primary Baranyi and Roberts and the modified Gompertz models were fitted to the experimental data to obtain the growth parameters. The Ratkowsky extended model was used to determine the effect of pH and temperature on the growth parameter μmax. The program DMFit 3.0 was used for model adjustment and fitting. The experimental data showed good fit for both the models tested, and the primary and secondary models based on the Baranyi and Roberts models showed better validation. Thus, these models can be applied to predict the growth of P. fluorescens under the conditions tested.

  6. The Genome of Pseudomonas fluorescens Strain R124 Demonstrates Phenotypic Adaptation to the Mineral Environment

    PubMed Central

    Barton, Michael D.; Petronio, Michael; Giarrizzo, Juan G.; Bowling, Bethany V.

    2013-01-01

    Microbial adaptation to environmental conditions is a complex process, including acquisition of positive traits through horizontal gene transfer or the modification of existing genes through duplication and/or mutation. In this study, we examined the adaptation of a Pseudomonas fluorescens isolate (R124) from the nutrient-limited mineral environment of a silica cave in comparison with P. fluorescens isolates from surface soil and the rhizosphere. Examination of metal homeostasis gene pathways demonstrated a high degree of conservation, suggesting that such systems remain functionally similar across chemical environments. The examination of genomic islands unique to our strain revealed the presence of genes involved in carbohydrate metabolism, aromatic carbon metabolism, and carbon turnover, confirmed through phenotypic assays, suggesting the acquisition of potentially novel mechanisms for energy metabolism in this strain. We also identified a twitching motility phenotype active at low-nutrient concentrations that may allow alternative exploratory mechanisms for this organism in a geochemical environment. Two sets of candidate twitching motility genes are present within the genome, one on the chromosome and one on a plasmid; however, a plasmid knockout identified the functional gene as being present on the chromosome. This work highlights the plasticity of the Pseudomonas genome, allowing the acquisition of novel nutrient-scavenging pathways across diverse geochemical environments while maintaining a core of functional stress response genes. PMID:23995634

  7. Phenotypic and metabolic profiling of colony morphology variants evolved from Pseudomonas fluorescens biofilms.

    PubMed

    Workentine, Matthew L; Harrison, Joe J; Weljie, Aalim M; Tran, Vy A; Stenroos, Pernilla U; Tremaroli, Valentina; Vogel, Hans J; Ceri, Howard; Turner, Raymond J

    2010-06-01

    Colony morphology variants isolated from natural and laboratory-grown biofilms represent subpopulations of biofilm cells that may be important for multiple aspects of the sessile lifestyle, from surface colonization to stress resistance. There are many genetic and environmental factors that determine the frequency at which colony morphology variants are recovered from biofilms. One of these factors involves an increased selection for variants in biofilms of Pseudomonas species bearing inactivating mutations in the global activator of cyanide biosynthesis/regulator of secondary metabolism (gac/rsm) signal transduction pathway. Here we characterize two distinct colony morphology variants isolated from biofilms of Pseudomonas fluorescens missing the gacS sensor kinase. These variants produced more biofilm cell mass, and in one case, this was likely due to overproduction of the exopolysaccharide cellulose. Nuclear magnetic resonance (NMR) metabolomics revealed distinct metabolic changes for each of the two phenotypic variants, and these changes involved amino acids and metabolites produced through glutathione biochemistry. Some of these metabolites are hypothesized to play a role in redox and metal homeostasis, and corresponding to this, we show that biofilm populations grown from each of these variants had a different ability to survive when exposed to toxic doses of metal ions. These data suggest that colony morphology variants that evolve during growth of P. fluorescens as a biofilm may have distinct metabolic capacities that contribute to their individual abilities to withstand environmental stress.

  8. Endophytic colonization of olive roots by the biocontrol strain Pseudomonas fluorescens PICF7.

    PubMed

    Prieto, Pilar; Mercado-Blanco, Jesús

    2008-05-01

    Confocal microscopy combined with three-dimensional olive root tissue sectioning was used to provide evidence of the endophytic behaviour of Pseudomonas fluorescens PICF7, an effective biocontrol strain against Verticillium wilt of olive. Two derivatives of the green fluorescent protein (GFP), the enhanced green and the red fluorescent proteins, have been used to visualize simultaneously two differently fluorescently tagged populations of P. fluorescens PICF7 within olive root tissues at the single cell level. The time-course of colonization events of olive roots cv. Arbequina by strain PICF7 and the localization of tagged bacteria within olive root tissues are described. First, bacteria rapidly colonized root surfaces and were predominantly found in the differentiation zone. Thereafter, microscopy observations showed that PICF7-tagged populations eventually disappeared from the root surface, and increasingly colonized inner root tissues. Localized and limited endophytic colonization by the introduced bacteria was observed over time. Fluorescent-tagged bacteria were always visualized in the intercellular spaces of the cortex region, and no colonization of the root xylem vessels was detected at any time. To the best of our knowledge, this is the first time this approach has been used to demonstrate endophytism of a biocontrol Pseudomonas spp. strain in a woody host such as olive using a nongnotobiotic system.

  9. Electrochemically monitoring the antibiotic susceptibility of Pseudomonas aeruginosa biofilms.

    PubMed

    Webster, Thaddaeus A; Sismaet, Hunter J; Chan, I-ping J; Goluch, Edgar D

    2015-11-07

    The condition of cells in Pseudomonas aeruginosa biofilms was monitored via the electrochemical detection of the electro-active virulence factor pyocyanin in a fabricated microfluidic growth chamber coupled with a disposable three electrode cell. Cells were exposed to 4, 16, and 100 mg L(-1) colistin sulfate after overnight growth. At the end of testing, the measured maximum peak current (and therefore pyocyanin concentration) was reduced by approximately 68% and 82% in P. aeruginosa exposed to 16 and 100 mg L(-1) colistin sulfate, respectively. Samples were removed from the microfluidic chamber, analyzed for viability using staining, and streaked onto culture plates to confirm that the P. aeruginosa cells were affected by the antibiotics. The correlation between electrical signal drop and the viability of P. aeruginosa cells after antibiotic exposure highlights the usefulness of this approach for future low cost antibiotic screening applications.

  10. Acquisition and Role of Molybdate in Pseudomonas aeruginosa

    PubMed Central

    Pederick, Victoria G.; Eijkelkamp, Bart A.; Ween, Miranda P.; Begg, Stephanie L.; Paton, James C.

    2014-01-01

    In microaerophilic or anaerobic environments, Pseudomonas aeruginosa utilizes nitrate reduction for energy production, a process dependent on the availability of the oxyanionic form of molybdenum, molybdate (MoO42−). Here, we show that molybdate acquisition in P. aeruginosa occurs via a high-affinity ATP-binding cassette permease (ModABC). ModA is a cluster D-III solute binding protein capable of interacting with molybdate or tungstate oxyanions. Deletion of the modA gene reduces cellular molybdate concentrations and results in inhibition of anaerobic growth and nitrate reduction. Further, we show that conditions that permit nitrate reduction also cause inhibition of biofilm formation and an alteration in fatty acid composition of P. aeruginosa. Collectively, these data highlight the importance of molybdate for anaerobic growth of P. aeruginosa and reveal novel consequences of nitrate reduction on biofilm formation and cell membrane composition. PMID:25172858

  11. Oxylipins produced by Pseudomonas aeruginosa promote biofilm formation and virulence

    PubMed Central

    Martínez, Eriel; Campos-Gómez, Javier

    2016-01-01

    The oxygenation of unsaturated fatty acids by dioxygenases occurs in all kingdoms of life and produces physiologically important lipids called oxylipins. The biological roles of oxylipins have been extensively studied in animals, plants, algae and fungi, but remain largely unidentified in prokaryotes. The bacterium Pseudomonas aeruginosa displays a diol synthase activity that transforms several monounsaturated fatty acids into mono- and di-hydroxylated derivatives. Here we show that oxylipins derived from this activity inhibit flagellum-driven motility and upregulate type IV pilus-dependent twitching motility of P. aeruginosa. Consequently, these oxylipins promote bacterial organization in microcolonies, increasing the ability of P. aeruginosa to form biofilms in vitro and in vivo (in Drosophila flies). We also demonstrate that oxylipins produced by P. aeruginosa promote virulence in Drosophila flies and lettuce. Our study thus uncovers a role for prokaryotic oxylipins in the physiology and pathogenicity of bacteria. PMID:27929111

  12. Acquisition and role of molybdate in Pseudomonas aeruginosa.

    PubMed

    Pederick, Victoria G; Eijkelkamp, Bart A; Ween, Miranda P; Begg, Stephanie L; Paton, James C; McDevitt, Christopher A

    2014-11-01

    In microaerophilic or anaerobic environments, Pseudomonas aeruginosa utilizes nitrate reduction for energy production, a process dependent on the availability of the oxyanionic form of molybdenum, molybdate (MoO4 (2-)). Here, we show that molybdate acquisition in P. aeruginosa occurs via a high-affinity ATP-binding cassette permease (ModABC). ModA is a cluster D-III solute binding protein capable of interacting with molybdate or tungstate oxyanions. Deletion of the modA gene reduces cellular molybdate concentrations and results in inhibition of anaerobic growth and nitrate reduction. Further, we show that conditions that permit nitrate reduction also cause inhibition of biofilm formation and an alteration in fatty acid composition of P. aeruginosa. Collectively, these data highlight the importance of molybdate for anaerobic growth of P. aeruginosa and reveal novel consequences of nitrate reduction on biofilm formation and cell membrane composition.

  13. Imported PER-1 producing Pseudomonas aeruginosa, PER-1 producing Acinetobacter baumanii and VIM-2-producing Pseudomonas aeruginosa strains in Hungary

    PubMed Central

    Szabó, Dora; Szentandrássy, Julia; Juhász, Zsuzsa; Katona, Katalin; Nagy, Károly; Rókusz, László

    2008-01-01

    Introduction Pseudomonas aeruginosa and Acinetobacter baumanii are important nosocomial pathogens with wide intrinsic resistance. However, due to the dissemination of the acquired resistance mechanisms, such as extended-spectrum beta-lactamase (ESBL) and metallo beta-lactamase (MBL) production, multidrug resistant strains have been isolated more often. Case presentation We report a case of a Hungarian tourist, who was initially hospitalized in Egypt and later transferred to Hungary. On the day of admission PER-1-producing P. aeruginosa, PER-1 producing A. baumannii, SHV-5-producing Klebsiella pneumoniae and VIM-2-producing P. aeruginosa isolates were subcultured from the patient's samples in Hungary. Comparing the pulsed-field gel electrophoresis (PFGE) patterns of the P. aeruginosa strains from the patient to the P. aeruginosa strains occurring in this hospital, we can state that the PER-1-producing P. aeruginosa and VIM-2-producing P. aeruginosa had external origin. Conclusion This is the first report of PER-1-producing P. aeruginosa,and PER-1-producing A. baumanii strains in Hungary. This case highlights the importance of spreading of the beta-lactamase-mediated resistance mechanisms between countries and continents, showing the importance of careful screening and the isolation of patients arriving from a different country. PMID:18513394

  14. Molecular epidemiology of Pseudomonas aeruginosa in an intensive care unit.

    PubMed Central

    Döring, G.; Hörz, M.; Ortelt, J.; Grupp, H.; Wolz, C.

    1993-01-01

    Genotyping was used to analyse Pseudomonas aeruginosa isolates from sink drains and 15 intubated patients as part of a 3-month prospective study of strain transmission in a medical-surgical intensive care unit. Ninety percent of all washbasin drains were persistently contaminated with several P. aeruginosa genotypes. In 60% (9/15) of the patients, P. aeruginosa colonization or infection was hospital-acquired: P. aeruginosa strains isolated from these patients were present in hospital sinks or in other patients before their admission. Since all patients were immobile, personnel were the probable route of transmission of P. aeruginosa in the hospital. The mechanism of strain transmission from sinks to hands during hand washing was investigated in a children's hospital. When P. aeruginosa was present at densities of > 10(5)/c.f.u. per ml in sink drains, hand washing resulted in hand contamination with P. aeruginosa via aerosol generation in the majority of experiments or P. aeruginosa was detected using an air sampler above the washing basin. High P. aeruginosa cfu were present at 4.30 h in the eight sinks (5.4 x 10(5)-7.0 x 10(10) c.f.u./ml), whereas at 13.00 h P. aeruginosa c.f.u. were significantly lower (3.1 x 10(2)-8.0 x 10(5) c.f.u./ml). These data reveal that the danger of bacterial contamination of hands during hand washing is highest in the morning. The identified transmission routes demand more effective hygienic measures in hospital settings particularly concerning personnel hands and sink drains. Images Fig. 1 PMID:8519308

  15. Subinhibitory bismuth-thiols reduce virulence of Pseudomonas aeruginosa.

    PubMed

    Wu, Chieh-Liang; Domenico, Philip; Hassett, Daniel J; Beveridge, Terry J; Hauser, Alan R; Kazzaz, Jeffrey A

    2002-06-01

    Pseudomonas aeruginosa is a common pathogen in mechanically ventilated patients and produces a wide array of virulence factors. Bismuth-thiols (BTs) are active in vitro against all bacterial lung pathogens, including P. aeruginosa. The objective of these studies was to examine the biochemical and morphologic effects of sublethal BT concentrations on P. aeruginosa and to evaluate virulence in cell culture. Bismuth-dimercaprol, at a fraction of the minimal inhibitory concentration, reduced alginate expression by 67% in P. aeruginosa, whereas subinhibitory bismuth-ethanedithiol (BisEDT) reduced alginate by 92% in P. syringae. BisEDT effects on lipopolysaccharide content and type III secreted cytoxins were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Subinhibitory BisEDT reduced cell-associated lipopolysaccharide, and inhibited processing of the secreted cytotoxic protein ExoU. BisEDT-induced outer membrane blebbing and aggregation of cytoplasmic material was noted in electron microscopy. Virulence of P. aeruginosa was assessed by adherence to epithelial cells and sensitivity to serum killing. BisEDT inhibited adherence of P. aeruginosa to 16HBE14o- cells by 28% and to a collagen matrix by 53%. BisEDT-treated bacteria were also 100-fold more sensitive to serum bactericidal activity. In summary, low BT concentrations affect P. aeruginosa in a variety of ways, the combination of which may help prevent or resolve respiratory tract infection.

  16. Dynorphin Activates Quorum Sensing Quinolone Signaling in Pseudomonas aeruginosa

    PubMed Central

    Zaborina, Olga; Lepine, Francois; Xiao, Gaoping; Valuckaite, Vesta; Chen, Yimei; Li, Terry; Ciancio, Mae; Zaborin, Alex; Petroff, Elaine; Turner, Jerrold R; Rahme, Laurence G; Chang, Eugene; Alverdy, John C

    2007-01-01

    There is now substantial evidence that compounds released during host stress directly activate the virulence of certain opportunistic pathogens. Here, we considered that endogenous opioids might function as such compounds, given that they are among the first signals to be released at multiple tissue sites during host stress. We tested the ability of various opioid compounds to enhance the virulence of Pseudomonas aeruginosa using pyocyanin production as a biological readout, and demonstrated enhanced virulence when P. aeruginosa was exposed to synthetic (U-50,488) and endogenous (dynorphin) κ-agonists. Using various mutants and reporter strains of P. aeruginosa, we identified involvement of key elements of the quorum sensing circuitry such as the global transcriptional regulator MvfR and the quorum sensing-related quinolone signaling molecules PQS, HHQ, and HQNO that respond to κ-opioids. The in vivo significance of κ-opioid signaling of P. aeruginosa was demonstrated in mice by showing that dynorphin is released from the intestinal mucosa following ischemia/reperfusion injury, activates quinolone signaling in P. aeruginosa, and enhances the virulence of P. aeruginosa against Lactobacillus spp. and Caenorhabditis elegans. Taken together, these data demonstrate that P. aeruginosa can intercept opioid compounds released during host stress and integrate them into core elements of quorum sensing circuitry leading to enhanced virulence. PMID:17367209

  17. Otopathogenic Pseudomonas aeruginosa Enters and Survives Inside Macrophages

    PubMed Central

    Mittal, Rahul; Lisi, Christopher V.; Kumari, Hansi; Grati, M’hamed; Blackwelder, Patricia; Yan, Denise; Jain, Chaitanya; Mathee, Kalai; Weckwerth, Paulo H.; Liu, Xue Z.

    2016-01-01

    Otitis media (OM) is a broad term describing a group of infectious and inflammatory disorders of the middle ear. Despite antibiotic therapy, acute OM can progress to chronic suppurative otitis media (CSOM) characterized by ear drum perforation and purulent discharge. Pseudomonas aeruginosa is the most common pathogen associated with CSOM. Although, macrophages play an important role in innate immune responses but their role in the pathogenesis of P. aeruginosa-induced CSOM is not known. The objective of this study is to examine the interaction of P. aeruginosa with primary macrophages. We observed that P. aeruginosa enters and multiplies inside human and mouse primary macrophages. This bacterial entry in macrophages requires both microtubule and actin dependent processes. Transmission electron microscopy demonstrated that P. aeruginosa was present in membrane bound vesicles inside macrophages. Interestingly, deletion of oprF expression in P. aeruginosa abrogates its ability to survive inside macrophages. Our results suggest that otopathogenic P. aeruginosa entry and survival inside macrophages is OprF-dependent. The survival of bacteria inside macrophages will lead to evasion of killing and this lack of pathogen clearance by phagocytes contributes to the persistence of infection in CSOM. Understanding host–pathogen interaction will provide novel avenues to design effective treatment modalities against OM. PMID:27917157

  18. Interactions between Neutrophils and Pseudomonas aeruginosa in Cystic Fibrosis

    PubMed Central

    Rada, Balázs

    2017-01-01

    Cystic fibrosis (CF) affects 70,000 patients worldwide. Morbidity and mortality in CF is largely caused by lung complications due to the triad of impaired mucociliary clearance, microbial infections and chronic inflammation. Cystic fibrosis airway inflammation is mediated by robust infiltration of polymorphonuclear neutrophil granulocytes (PMNs, neutrophils). Neutrophils are not capable of clearing lung infections and contribute to tissue damage by releasing their dangerous cargo. Pseudomonas aeruginosa is an opportunistic pathogen causing infections in immunocompromised individuals. P. aeruginosa is a main respiratory pathogen in CF infecting most patients. Although PMNs are key to attack and clear P. aeruginosa in immunocompetent individuals, PMNs fail to do so in CF. Understanding why neutrophils cannot clear P. aeruginosa in CF is essential to design novel therapies. This review provides an overview of the antimicrobial mechanisms by which PMNs attack and eliminate P. aeruginosa. It also summarizes current advances in our understanding of why PMNs are incapable of clearing P. aeruginosa and how this bacterium adapts to and resists PMN-mediated killing in the airways of CF patients chronically infected with P. aeruginosa. PMID:28282951

  19. Mast cells protect against Pseudomonas aeruginosa-induced lung injury.

    PubMed

    Junkins, Robert D; Carrigan, Svetlana O; Wu, Zhengli; Stadnyk, Andrew W; Cowley, Elizabeth; Issekutz, Thomas; Berman, Jason; Lin, Tong-Jun

    2014-08-01

    Pseudomonas aeruginosa, an opportunistic pathogen, is the leading cause of morbidity and mortality in immune-compromised individuals. Maintaining the integrity of the respiratory epithelium is critical for an effective host response to P. aeruginosa. Given the close spatial relationship between mast cells and the respiratory epithelium, and the importance of tightly regulated epithelial permeability during lung infections, we examined whether mast cells influence airway epithelial integrity during P. aeruginosa lung infection in a mouse model. We found that mast cell-deficient Kit(W-sh)/Kit(W-sh) mice displayed greatly increased epithelial permeability, bacterial dissemination, and neutrophil accumulation compared with wild-type animals after P. aeruginosa infection; these defects were corrected on reconstitution with mast cells. An in vitro Transwell co-culture model further demonstrated that a secreted mast cell factor decreased epithelial cell apoptosis and tumor necrosis factor production after P. aeruginosa infection. Together, our data demonstrate a previously unrecognized role for mast cells in the maintenance of epithelial integrity during P. aeruginosa infection, through a mechanism that likely involves prevention of epithelial apoptosis and tumor necrosis factor production. Our understanding of mechanisms of the host response to P. aeruginosa will open new avenues for the development of successful preventative and treatment strategies.

  20. Environmental Pseudomonads Inhibit Cystic Fibrosis Patient-Derived Pseudomonas aeruginosa.

    PubMed

    Chatterjee, Payel; Davis, Elizabeth; Yu, Fengan; James, Sarah; Wildschutte, Julia H; Wiegmann, Daniel D; Sherman, David H; McKay, Robert M; LiPuma, John J; Wildschutte, Hans

    2017-01-15

    Pseudomonas aeruginosa is an opportunistic pathogen which is evolving resistance to many currently used antibiotics. While much research has been devoted to the roles of pathogenic P. aeruginosa in cystic fibrosis (CF) patients, less is known of its ecological properties. P. aeruginosa dominates the lungs during chronic infection in CF patients, yet its abundance in some environments is less than that of other diverse groups of pseudomonads. Here, we sought to determine if clinical isolates of P. aeruginosa are vulnerable to environmental pseudomonads that dominate soil and water habitats in one-to-one competitions which may provide a source of inhibitory factors. We isolated a total of 330 pseudomonads from diverse habitats of soil and freshwater ecosystems and competed these strains against one another to determine their capacity for antagonistic activity. Over 900 individual inhibitory events were observed. Extending the analysis to P. aeruginosa isolates revealed that clinical isolates, including ones with increased alginate production, were susceptible to competition by multiple environmental strains. We performed transposon mutagenesis on one isolate and identified an ∼14.8-kb locus involved in antagonistic activity. Only two other environmental isolates were observed to carry the locus, suggesting the presence of additional unique compounds or interactions among other isolates involved in outcompeting P. aeruginosa This collection of strains represents a source of compounds that are active against multiple pathogenic strains. With the evolution of resistance of P. aeruginosa to currently used antibiotics, these environmental strains provide opportunities for novel compound discovery against drug-resistant clinical strains.

  1. Copper and quaternary ammonium cations exert synergistic bactericidal and antibiofilm activity against Pseudomonas aeruginosa.

    PubMed

    Harrison, Joe J; Turner, Raymond J; Joo, Daniel A; Stan, Michelle A; Chan, Catherine S; Allan, Nick D; Vrionis, Helen A; Olson, Merle E; Ceri, Howard

    2008-08-01

    Biofilms are slimy aggregates of microbes that are likely responsible for many chronic infections as well as for contamination of clinical and industrial environments. Pseudomonas aeruginosa is a prevalent hospital pathogen that is well known for its ability to form biofilms that are recalcitrant to many different antimicrobial treatments. We have devised a high-throughput method for testing combinations of antimicrobials for synergistic activity against biofilms, including those formed by P. aeruginosa. This approach was used to look for changes in biofilm susceptibility to various biocides when these agents were combined with metal ions. This process identified that Cu(2+) works synergistically with quaternary ammonium compounds (QACs; specifically benzalkonium chloride, cetalkonium chloride, cetylpyridinium chloride, myristalkonium chloride, and Polycide) to kill P. aeruginosa biofilms. In some cases, adding Cu(2+) to QACs resulted in a 128-fold decrease in the biofilm minimum bactericidal concentration compared to that for single-agent treatments. In combination, these agents retained broad-spectrum antimicrobial activity that also eradicated biofilms of Escherichia coli, Staphylococcus aureus, Salmonella enterica serovar Cholerasuis, and Pseudomonas fluorescens. To investigate the mechanism of action, isothermal titration calorimetry was used to show that Cu(2+) and QACs do not interact in aqueous solutions, suggesting that each agent exerts microbiological toxicity through independent biochemical routes. Additionally, Cu(2+) and QACs, both alone and in combination, reduced the activity of nitrate reductases, which are enzymes that are important for normal biofilm growth. Collectively, the results of this study indicate that Cu(2+) and QACs are effective combinations of antimicrobials that may be used to kill bacterial biofilms.

  2. LETHALITY OF PSEUDOMONAS FLUORESCENS STRAIN CLO145A TO THE 2 ZEBRA MUSSEL SPECIES PRESENT IN NORTH AMERICA

    SciTech Connect

    Daniel P. Molloy

    2001-10-28

    These experiments indicated that bacterial strain CL0145A of Pseudomonas fluorescens is equally lethal to the 2 zebra mussel species present in North America, Dreissena polymorpha and Dreissena bugensis. Thus, this bacterial strain should be equally effective at killing zebra mussels in power plant pipes, irrespective of which species is present.

  3. Complete Genome Sequence of Pseudomonas fluorescens LBUM636, a Strain with Biocontrol Capabilities against Late Blight of Potato

    PubMed Central

    Morrison, Christopher K.; Novinscak, Amy; Gadkar, Vijay J.; Joly, David L.

    2016-01-01

    Herein provided is the full-genome sequence of Pseudomonas fluorescens LBUM636. This strain is a plant growth-promoting rhizobacterium (PGPR) which produces phenazine-1-carboxylic acid, an antibiotic involved in the biocontrol of numerous plant pathogens, including late blight of potato caused by the plant pathogen Phytophthora infestans. PMID:27231373

  4. Quantification of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens strains in the plant rhizosphere by real-time PCR.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A real-time PCR SYBR green assay was developed to quantify populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing (phlD+) strains of Pseudomonas fluorescens in soil and the rhizosphere. Primers were designed and PCR conditions were optimized to specifically amplify the phlD gene from four di...

  5. Secondary metabolite production by Pseudomonas fluorescens strain Pf-5 confers protection against Naegleria americana in the wheat rhizosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacteria employ a variety of morphological and metabolic mechanisms to avoid protozoan predation. In Pseudomonas fluorescens strains SS101 and SBW25, cyclic lipopeptide (CLP) production served as a defense mechanism that limited predation by the amoeba-flagellate Naegleria americana, and secondary m...

  6. Draft Genome Sequence of the Polycyclic Aromatic Hydrocarbon-Degrading, Genetically Engineered Bioluminescent Bioreporter Pseudomonas fluorescens HK44 ▿

    PubMed Central

    Chauhan, Archana; Layton, Alice C.; Williams, Daniel E.; Smartt, Abby E.; Ripp, Steven; Karpinets, Tatiana V.; Brown, Steven D.; Sayler, Gary S.

    2011-01-01

    Pseudomonas fluorescens strain HK44 (DSM 6700) is a genetically engineered lux-based bioluminescent bioreporter. Here we report the draft genome sequence of strain HK44. Annotation of ∼6.1 Mb of sequence indicates that 30% of the traits are unique and distributed over five genomic islands, a prophage, and two plasmids. PMID:21742869

  7. Draft Genome Sequence of the Polycyclic Aromatic Hydrocarbon-Degrading, Genetically Engineered Bioluminescent Bioreporter Pseudomonas fluorescens HK44

    SciTech Connect

    Chauhan, Archana; Layton, Alice; Williams, Daniel W; Smart, Abby E.; Ripp, Steven Anthony; Karpinets, Tatiana V; Brown, Steven D; Sayler, Gary Steven

    2011-01-01

    Pseudomonas fluorescens strain HK44 (DSM 6700) is a genetically engineered lux-based bioluminescent bioreporter. Here we report the draft genome sequence of strain HK44. Annotation of {approx}6.1 Mb sequence indicates that 30% of the traits are unique and distributed over 5 genomic islands, a prophage and two plasmids.

  8. Assessment of DAPG-producing Pseudomonas fluorescens for management of Meloidogyne incognita and Fusarium oxysporum on watermelon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens isolates Clinto 1R, Wayne 1R and Wood 1R, which produce the antibiotic 2,4-diacetylphloroglucinol (DAPG), can suppress soilborne diseases and promote plant growth. Consequently, these beneficial bacterial isolates were tested on watermelon plants for suppression of Meloidogy...

  9. Characterization of Toxin Complex Gene Clusters and Insect Toxicity of Bacteria Representing Four Subgroups of Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ten strains representing four lineages of Pseudomonas (P. chlororaphis, P. corrugata, P. koreensis, and P. fluorescens subgroups) were evaluated for toxicity to the tobacco hornworm Manduca sexta and the fruit fly Drosophila melanogaster. The three strains within the P. chlororaphis subgroup exhibi...

  10. Influence of Pseudomonas Aeruginosa on Exacerbation in Patients with Bronchiectasis

    PubMed Central

    Chawla, Kiran; Vishwanath, Shashidhar; Manu, Mohan K; Lazer, Bernaitis

    2015-01-01

    Background: A majority of the studies done on the western population have shown that Pseudomonas aeruginosa causes many severe infections in patients with bronchiectasis as compared to other pathogens. There is scarcity of similar data from the Asian population. Materials and Methods: A prospective study was undertaken to identify the various pathogens isolated from the respiratory samples of 117 patients with bronchiectasis from south India and to compare the clinicomicrobiological profile of infections caused by P. aeruginosa and other respiratory pathogens. Results: The respiratory pathogens were isolated from 63 (53.8%) patients. P. aeruginosa was the most common isolate (46.0%) followed by Klebsiella pneumoniae (14.3%) and other pathogenic bacteria. Patients included in the P. aeruginosa group had a higher number of exacerbations (p: 0.008), greater number of hospital admissions (p: 0.007), a prolonged hospital stay (p: 0.03), and poor lung function, compared to the patients infected with the non-Pseudomonas group. Conclusion: It is necessary to investigate the etiology of respiratory tract infections among bronchiectasis patients followed by the prompt management of cases diagnosed with P. aeruginosa infections, so as to lower the morbidity and have a better prognosis. PMID:25722615

  11. Metabolic engineering of Pseudomonas fluorescens for the production of vanillin from ferulic acid.

    PubMed

    Di Gioia, Diana; Luziatelli, Francesca; Negroni, Andrea; Ficca, Anna Grazia; Fava, Fabio; Ruzzi, Maurizio

    2011-12-20

    Vanillin is one of the most important flavors in the food industry and there is great interest in its production through biotechnological processes starting from natural substrates such as ferulic acid. Among bacteria, recombinant Escherichia coli strains are the most efficient vanillin producers, whereas Pseudomonas spp. strains, although possessing a broader metabolic versatility, rapidly metabolize various phenolic compounds including vanillin. In order to develop a robust Pseudomonas strain that can produce vanillin in high yields and at high productivity, the vanillin dehydrogenase (vdh)-encoding gene of Pseudomonas fluorescens BF13 strain was inactivated via targeted mutagenesis. The results demonstrated that engineered derivatives of strain BF13 accumulate vanillin if inactivation of vdh is associated with concurrent expression of structural genes for feruloyl-CoA synthetase (fcs) and hydratase/aldolase (ech) from a low-copy plasmid. The conversion of ferulic acid to vanillin was enhanced by optimization of growth conditions, growth phase and parameters of the bioconversion process. The developed strain produced up to 8.41 mM vanillin, which is the highest final titer of vanillin produced by a Pseudomonas strain to date and opens new perspectives in the use of bacterial biocatalysts for biotechnological production of vanillin from agro-industrial wastes which contain ferulic acid.

  12. A case of Pseudomonas Aeruginosa commercial tattoo infection.

    PubMed

    Maloberti, A; Betelli, M; Perego, M R; Foresti, S; Scarabelli, G; Grassi, G

    2015-11-18

    Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium that can cause disease in immunocompromised patients but also burn wounds and other cutaneous infections. We report the case of a 31 years old woman with a P. Aeruginosa commercial tattoo infection treated with intravenous antibiotic therapy. Today tattooing is increasingly common and despite specific regulations many cases of tattoo site infection are reported in the literature. Principal actual tattoo infective epidemiology includes Streptococcus pyogenes, Staphylococcus aureus and mycosis infections and parenteral transmission of HIV, HBV and HCV but also recently published cases of Methicillin-Resistant Staphylococcus aureus and non tuberculous mycobacterium tattoo infection.

  13. Iron Depletion Enhances Production of Antimicrobials by Pseudomonas aeruginosa

    PubMed Central

    Nguyen, Angela T.; Jones, Jace W.; Ruge, Max A.; Kane, Maureen A.

    2015-01-01

    ABSTRACT Cystic fibrosis (CF) is a heritable disease characterized by chronic, polymicrobial lung infections. While Staphylococcus aureus is the dominant lung pathogen in young CF patients, Pseudomonas aeruginosa becomes predominant by adulthood. P. aeruginosa produces a variety of antimicrobials that likely contribute to this shift in microbial populations. In particular, secretion of 2-alkyl-4(1H)-quinolones (AQs) contributes to lysis of S. aureus in coculture, providing an iron source to P. aeruginosa both in vitro and in vivo. We previously showed that production of one such AQ, the Pseudomonas quinolone signal (PQS), is enhanced by iron depletion and that this induction is dependent upon the iron-responsive PrrF small RNAs (sRNAs). Here, we demonstrate that antimicrobial activity against S. aureus during coculture is also enhanced by iron depletion, and we provide evidence that multiple AQs contribute to this activity. Strikingly, a P. aeruginosa ΔprrF mutant, which produces very little PQS in monoculture, was capable of mediating iron-regulated growth suppression of S. aureus. We show that the presence of S. aureus suppresses the ΔprrF1,2 mutant's defect in iron-regulated PQS production, indicating that a PrrF-independent iron regulatory pathway mediates AQ production in coculture. We further demonstrate that iron-regulated antimicrobial production is conserved in multiple P. aeruginosa strains, including clinical isolates from CF patients. These results demonstrate that iron plays a central role in modulating interactions of P. aeruginosa with S. aureus. Moreover, our studies suggest that established iron regulatory pathways of these pathogens are significantly altered during polymicrobial infections. IMPORTANCE Chronic polymicrobial infections involving Pseudomonas aeruginosa and Staphylococcus aureus are a significant cause of morbidity and mortality, as the interplay between these two organisms exacerbates infection. This is in part due to enhanced

  14. Induced systemic resistance (ISR) in Arabidopsis thaliana against Pseudomonas syringae pv. tomato by 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens strains that produce the polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are among the most effective rhizobacteria that suppress root and crown rots, wilts and damping-off diseases of a variety of crops, and they play a key role in the natural suppressiveness of ...

  15. Mechanisms of phagocytosis and host clearance of Pseudomonas aeruginosa.

    PubMed

    Lovewell, Rustin R; Patankar, Yash R; Berwin, Brent

    2014-04-01

    Pseudomonas aeruginosa is an opportunistic bacterial pathogen responsible for a high incidence of acute and chronic pulmonary infection. These infections are particularly prevalent in patients with chronic obstructive pulmonary disease and cystic fibrosis: much of the morbidity and pathophysiology associated with these diseases is due to a hypersusceptibility to bacterial infection. Innate immunity, primarily through inflammatory cytokine production, cellular recruitment, and phagocytic clearance by neutrophils and macrophages, is the key to endogenous control of P. aeruginosa infection. In this review, we highlight recent advances toward understanding the innate immune response to P. aeruginosa, with a focus on the role of phagocytes in control of P. aeruginosa infection. Specifically, we summarize the cellular and molecular mechanisms of phagocytic recognition and uptake of P. aeruginosa, and how current animal models of P. aeruginosa infection reflect clinical observations in the context of phagocytic clearance of the bacteria. Several notable phenotypic changes to the bacteria are consistently observed during chronic pulmonary infections, including changes to mucoidy and flagellar motility, that likely enable or reflect their ability to persist. These traits are likewise examined in the context of how the bacteria avoid phagocytic clearance, inflammation, and sterilizing immunity.

  16. Tracking the immunopathological response to Pseudomonas aeruginosa during respiratory infections

    PubMed Central

    Cigana, Cristina; Lorè, Nicola Ivan; Riva, Camilla; De Fino, Ida; Spagnuolo, Lorenza; Sipione, Barbara; Rossi, Giacomo; Nonis, Alessandro; Cabrini, Giulio; Bragonzi, Alessandra

    2016-01-01

    Repeated cycles of infections, caused mainly by Pseudomonas aeruginosa, combined with a robust host immune response and tissue injury, determine the course and outcome of cystic fibrosis (CF) lung disease. As the disease progresses, P. aeruginosa adapts to the host modifying dramatically its phenotype; however, it remains unclear whether and how bacterial adaptive variants and their persistence influence the pathogenesis and disease development. Using in vitro and murine models of infection, we showed that P. aeruginosa CF-adaptive variants shaped the innate immune response favoring their persistence. Next, we refined a murine model of chronic pneumonia extending P. aeruginosa infection up to three months. In this model, including CFTR-deficient mice, we unveil that the P. aeruginosa persistence lead to CF hallmarks of airway remodelling and fibrosis, including epithelial hyperplasia and structure degeneration, goblet cell metaplasia, collagen deposition, elastin degradation and several additional markers of tissue damage. This murine model of P. aeruginosa chronic infection, reproducing CF lung pathology, will be instrumental to identify novel molecular targets and test newly tailored molecules inhibiting chronic inflammation and tissue damage processes in pre-clinical studies. PMID:26883959

  17. Mechanisms of phagocytosis and host clearance of Pseudomonas aeruginosa

    PubMed Central

    Lovewell, Rustin R.; Patankar, Yash R.

    2014-01-01

    Pseudomonas aeruginosa is an opportunistic bacterial pathogen responsible for a high incidence of acute and chronic pulmonary infection. These infections are particularly prevalent in patients with chronic obstructive pulmonary disease and cystic fibrosis: much of the morbidity and pathophysiology associated with these diseases is due to a hypersusceptibility to bacterial infection. Innate immunity, primarily through inflammatory cytokine production, cellular recruitment, and phagocytic clearance by neutrophils and macrophages, is the key to endogenous control of P. aeruginosa infection. In this review, we highlight recent advances toward understanding the innate immune response to P. aeruginosa, with a focus on the role of phagocytes in control of P. aeruginosa infection. Specifically, we summarize the cellular and molecular mechanisms of phagocytic recognition and uptake of P. aeruginosa, and how current animal models of P. aeruginosa infection reflect clinical observations in the context of phagocytic clearance of the bacteria. Several notable phenotypic changes to the bacteria are consistently observed during chronic pulmonary infections, including changes to mucoidy and flagellar motility, that likely enable or reflect their ability to persist. These traits are likewise examined in the context of how the bacteria avoid phagocytic clearance, inflammation, and sterilizing immunity. PMID:24464809

  18. COMPARATIVE TAXONOMY OF CRYSTALLOGENIC STRAINS OF PSEUDOMONAS AERUGINOSA AND PSEUDOMONAS CHLORORAPHIS

    PubMed Central

    Haynes, William C.; Rhodes, Lenora J.

    1962-01-01

    Haynes, William C. (Northern Utilization Research and Development Division, Peoria, Ill.) and Lenora J. Rhodes. Comparative taxonomy of crystallogenic strains of Pseudomonas aeruginosa and Pseudomonas chlororaphis. J. Bacteriol. 84:1080–1084. 1962.—Only 11 of 39 strains received in the Agricultural Research Service Culture Collection under the designation Pseudonomas chlororaphis proved to be authentic; 28 were typical, pyocyanogenic strains of P. aeruginosa. The reason for this disproportionately high rate of misidentification apparently arises from an erroneous belief that the ability to produce green and yellow crystals of chlororaphin and oxychlororaphin is confined to P. chlororaphis. The ability of many strains of P. aeruginosa to do likewise is not well known. Inasmuch as the characteristic is not unique to P. chlororaphis, other criteria are required to distinguish crystallogenic strains of these species. After a taxonomic comparison of 18 strains of P. chlororaphis and 47 crystallogenic strains of P. aeruginosa, it was determined that there are three main distinctions: (i) P. aeruginosa grows well at 42 C but fails to grow upon serial transfer at 5 C, whereas P. chlororaphis fails to grow at 42 C, but grows well at 5 C: (ii) most strains of P. aeruginosa produce pyocyanin, whereas P. chlororaphis strains do not; (iii) P. aeruginosa cells possess only one or two polar flagella, whereas P. chlororaphis usually has at least four, sometimes as many as eight, polar flagella. PMID:13963593

  19. Fast and specific detection of Pseudomonas Aeruginosa from other pseudomonas species by PCR

    PubMed Central

    Jami Al-Ahmadi, G.; Zahmatkesh Roodsari, R.

    2016-01-01

    Summary Pseudomonas aeruginosa is an important life-threatening nosocomial pathogen that plays a prominent role in wound infections of burned patients. We designed this study to identify the isolates of P. aeruginosa recovered from burned patients at the genus and species level through primers targeting oprI and oprL genes, and analyzed their antimicrobial resistance pattern. Over a 2-month period, wound samples were taken from burned patients and plated on MacConkey agar. All suspected colonies were primarily screened for P. aeruginosa by a combination of phenotypic tests. Molecular identifications of colonies were done using specific primers for oprI and oprL genes. Bacterial isolates were recovered from burn wound infections. Based on phenotypical identification tests, 138 (34%) P. aeruginosa isolates were identified; whereas by molecular techniques, just 128 P. aeruginosa yielded amplicon of oprL gene using species-specific primers, verifying the identity of P. aeruginosa; the others yielded amplicon of oprI gene using genus-specific primers, confirming the identity of fluorescent pseudomonads. This study indicates that molecular detection of P. aeruginosa in burn patients employing the OprL gene target is a useful technique for the early and precise detection of P. aeruginosa. PCR detection should be carried out as well as phenotypic testing for the best aggressive antibiotic treatment of P. aeruginosa strains at an earlier stage. It also has significant benefits on clinical outcomes. PMID:28289359

  20. Effect of temperature on the shift of Pseudomonas fluorescens from an environmental microorganism to a potential human pathogen.

    PubMed

    Donnarumma, G; Buommino, E; Fusco, A; Paoletti, I; Auricchio, L; Tufano, M A

    2010-01-01

    Pseudomonas fluorescens is a Gram-negative bacterium generally considered of scarce clinical significance. However, in the last few years, the isolation of P. fluorescens as the causative agent of nosocomial infections has rapidly increased. P. fluorescens is a psychrophile microorganism which grows at an optimal temperature of 25-30 degrees Celcius. In spite of this constraint, it has recently been reported that the human physiological temperature does not appear to be a barrier for this microorganism. In this study we examined the ability of P. fluorescens, grown at 28 degrees C or at 37 degrees C, to adhere to cultured human A549 pulmonary cells and to form biofilm. The ability of P. fluorescens to induce expression of proinflammatory cytokines, beta-defensin 2 and the intercellular adhesion molecule-1 was also investigated. Our results clearly indicate that inflammatory mediators are induced when the microorganism is grown at a lower temperature, while biofilm is formed only at 37 degrees C. The results presented are consistent with previous reports indicating P. fluorescens as an opportunistic pathogen and underscore the urgent need for further studies to better characterize the virulence of this microorganism.

  1. Membrane proteomes of Pseudomonas aeruginosa and Acinetobacter baumannii.

    PubMed

    Dé, E; Cosette, P; Coquet, L; Siroy, A; Alexandre, S; Duncan, A; Naudin, B; Rihouey, C; Schaumann, A; Junter, G A; Jouenne, T

    2011-12-01

    Acinetobacter baumannii and Pseudomonas aeruginosa are known for their intrinsic resistance to antibiotics. Between mechanisms involved in this resistance, diminished expression of outer membrane proteins and up-regulation of efflux pumps play an important role. The characterization of membrane proteins is consequently necessary because of their importance in the antibiotic resistance but also in virulence. This review presents proteomic investigations aiming to describe the protein content of the membranes of these two bacterial species.

  2. [Properties of a nitrite reductase inhibitor protein from Pseudomonas aeruginosa].

    PubMed

    Karapetian, A V; Nalbandian, R M

    1993-08-01

    The amino acid composition and major physico-chemical properties of the "nonblue" copper protein isolated earlier from Pseudomonas aeruginosa have been determined. It has been found that the azurin oxidase, cytochrome c551 oxidase and superoxide dismutase activities of the enzyme are inhibited by this protein. The inhibition seems to be due to the protein interaction with the electron-accepting center of nitrite reductase.

  3. Mobile genetic elements in the genome of the beneficial rhizobacterium Pseudomonas fluorescens Pf-5

    PubMed Central

    2009-01-01

    Background Pseudomonas fluorescens Pf-5 is a plant-associated bacterium that inhabits the rhizosphere of a wide variety of plant species and and produces secondary metabolites suppressive of fungal and oomycete plant pathogens. The Pf-5 genome is rich in features consistent with its commensal lifestyle, and its sequence has revealed attributes associated with the strain's ability to compete and survive in the dynamic and microbiologically complex rhizosphere habitat. In this study, we analyzed mobile genetic elements of the Pf-5 genome in an effort to identify determinants that might contribute to Pf-5's ability to adapt to changing environmental conditions and/or colonize new ecological niches. Results Sequence analyses revealed that the genome of Pf-5 is devoid of transposons and IS elements and that mobile genetic elements (MGEs) are represented by prophages and genomic islands that collectively span over 260 kb. The prophages include an F-pyocin-like prophage 01, a chimeric prophage 03, a lambdoid prophage 06, and decaying prophages 02, 04 and 05 with reduced size and/or complexity. The genomic islands are represented by a 115-kb integrative conjugative element (ICE) PFGI-1, which shares plasmid replication, recombination, and conjugative transfer genes with those from ICEs found in other Pseudomonas spp., and PFGI-2, which resembles a portion of pathogenicity islands in the genomes of the plant pathogens Pseudomonas syringae and P. viridiflava. Almost all of the MGEs in the Pf-5 genome are associated with phage-like integrase genes and are integrated into tRNA genes. Conclusion Comparative analyses reveal that MGEs found in Pf-5 are subject to extensive recombination and have evolved in part via exchange of genetic material with other Pseudomonas spp. having commensal or pathogenic relationships with plants and animals. Although prophages and genomic islands from Pf-5 exhibit similarity to MGEs found in other Pseudomonas spp., they also carry a number of

  4. Induced systemic resistance in Arabidopsis thaliana against Pseudomonas syringae pv. tomato by 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens.

    PubMed

    Weller, David M; Mavrodi, Dmitri V; van Pelt, Johan A; Pieterse, Corné M J; van Loon, Leendert C; Bakker, Peter A H M

    2012-04-01

    Pseudomonas fluorescens strains that produce the polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are among the most effective rhizobacteria that suppress root and crown rots, wilts, and damping-off diseases of a variety of crops, and they play a key role in the natural suppressiveness of some soils to certain soilborne pathogens. Root colonization by 2,4-DAPG-producing P. fluorescens strains Pf-5 (genotype A), Q2-87 (genotype B), Q8r1-96 (genotype D), and HT5-1 (genotype N) produced induced systemic resistance (ISR) in Arabidopsis thaliana accession Col-0 against bacterial speck caused by P. syringae pv. tomato. The ISR-eliciting activity of the four bacterial genotypes was similar, and all genotypes were equivalent in activity to the well-characterized strain P. fluorescens WCS417r. The 2,4-DAPG biosynthetic locus consists of the genes phlHGF and phlACBDE. phlD or phlBC mutants of Q2-87 (2,4-DAPG minus) were significantly reduced in ISR activity, and genetic complementation of the mutants restored ISR activity back to wild-type levels. A phlF regulatory mutant (overproducer of 2,4-DAPG) had ISR activity equivalent to the wild-type Q2-87. Introduction of DAPG into soil at concentrations of 10 to 250 μM 4 days before challenge inoculation induced resistance equivalent to or better than the bacteria. Strain Q2-87 induced resistance on transgenic NahG plants but not on npr1-1, jar1, and etr1 Arabidopsis mutants. These results indicate that the antibiotic 2,4-DAPG is a major determinant of ISR in 2,4-DAPG-producing P. fluorescens, that the genotype of the strain does not affect its ISR activity, and that the activity induced by these bacteria operates through the ethylene- and jasmonic acid-dependent signal transduction pathway.

  5. Sphingoid long chain bases prevent lung infection by Pseudomonas aeruginosa

    PubMed Central

    Pewzner-Jung, Yael; Tavakoli Tabazavareh, Shaghayegh; Grassmé, Heike; Becker, Katrin Anne; Japtok, Lukasz; Steinmann, Jörg; Joseph, Tammar; Lang, Stephan; Tuemmler, Burkhard; Schuchman, Edward H; Lentsch, Alex B; Kleuser, Burkhard; Edwards, Michael J; Futerman, Anthony H; Gulbins, Erich

    2014-01-01

    Cystic fibrosis patients and patients with chronic obstructive pulmonary disease, trauma, burn wound, or patients requiring ventilation are susceptible to severe pulmonary infection by Pseudomonas aeruginosa. Physiological innate defense mechanisms against this pathogen, and their alterations in lung diseases, are for the most part unknown. We now demonstrate a role for the sphingoid long chain base, sphingosine, in determining susceptibility to lung infection by P. aeruginosa. Tracheal and bronchial sphingosine levels were significantly reduced in tissues from cystic fibrosis patients and from cystic fibrosis mouse models due to reduced activity of acid ceramidase, which generates sphingosine from ceramide. Inhalation of mice with sphingosine, with a sphingosine analog, FTY720, or with acid ceramidase rescued susceptible mice from infection. Our data suggest that luminal sphingosine in tracheal and bronchial epithelial cells prevents pulmonary P. aeruginosa infection in normal individuals, paving the way for novel therapeutic paradigms based on inhalation of acid ceramidase or of sphingoid long chain bases in lung infection. PMID:25085879

  6. Pseudomonas aeruginosa biofilm, a programmed bacterial life for fitness.

    PubMed

    Lee, Keehoon; Yoon, Sang Sun

    2017-03-17

    Biofilm is a community of microbes that typically inhabits on surfaces and is encased in an extracellular matrix. Biofilms display very dissimilar characteristics to their planktonic counterparts. Biofilms are ubiquitous in the environments and influence our life tremendously in both positive and negative ways. Pseudomonas aeruginosa is a bacterium, known to produce robust biofilms. P. aeruginosa biofilms cause severe problems in immunocompromised patients including those with cystic fibrosis or wound infection. Moreover, the unique biofilm properties further complicates the eradication of the biofilm infection and leading to the development of chronic infections. In this review, we discuss a history of biofilm research and general characteristics of bacterial biofilms. Then, distinct features pertaining to each stage of P. aeruginosa biofilm development are highlighted. Furthermore, infections caused by biofilms of its own or in association with other bacterial species (i.e., multi-species biofilms) are discussed in detail.

  7. The Effect of Iron Limitation on the Transcriptome and Proteome of Pseudomonas fluorescens Pf-5

    PubMed Central

    Lim, Chee Kent; Hassan, Karl A.; Tetu, Sasha G.; Loper, Joyce E.; Paulsen, Ian T.

    2012-01-01

    One of the most important micronutrients for bacterial growth is iron, whose bioavailability in soil is limited. Consequently, rhizospheric bacteria such as Pseudomonas fluorescens employ a range of mechanisms to acquire or compete for iron. We investigated the transcriptomic and proteomic effects of iron limitation on P. fluorescens Pf-5 by employing microarray and iTRAQ techniques, respectively. Analysis of this data revealed that genes encoding functions related to iron homeostasis, including pyoverdine and enantio-pyochelin biosynthesis, a number of TonB-dependent receptor systems, as well as some inner-membrane transporters, were significantly up-regulated in response to iron limitation. Transcription of a ribosomal protein L36-encoding gene was also highly up-regulated during iron limitation. Certain genes or proteins involved in biosynthesis of secondary metabolites such as 2,4-diacetylphloroglucinol (DAPG), orfamide A and pyrrolnitrin, as well as a chitinase, were over-expressed under iron-limited conditions. In contrast, we observed that expression of genes involved in hydrogen cyanide production and flagellar biosynthesis were down-regulated in an iron-depleted culture medium. Phenotypic tests revealed that Pf-5 had reduced swarming motility on semi-solid agar in response to iron limitation. Comparison of the transcriptomic data with the proteomic data suggested that iron acquisition is regulated at both the transcriptional and post-transcriptional levels. PMID:22723948

  8. Effect of temperature on diauxic growth with glucose and organic acids in Pseudomonas fluorescens.

    PubMed

    Lynch, W H; Franklin, M

    1978-08-01

    Growth of Pseudomonas fluorescens in batch culture with glucose and organic acids resulted in typical diauxic responses at 30 degrees C but no detectable diauxic lag at 5 degrees C. At 30 degrees C, organic acids were preferentially utilized during the first growth phase. Glucose utilization was delayed until onset of the second growth phase. Systems involved in direct uptake and catabolism of glucose responded in a manner compatible with repression by malate and/or its metabolites and induction by glucose and/or its metabolites. The oxidative non-phosphorylated pathway, through gluconate and 2-ketogluconate (2-KG) as intermediates, was not induced during either growth phase. At 5 degrees C, growth with glucose and organic acids was biphasic but without diauxic lag. Organic acids were preferentially utilized during the first growth phase. Although carbon from glucose was not fully catabolized until onset of the second growth phase, glucose was oxidized to and accumulated extracellularly as gluconate and 2-KG during the first growth phase. No significant repression of glucose-catabolizing enzymes was observed during growth with organic acids in the presence of glucose. However, uptake activities for gluconate and 2-KG did not increase significantly until onset of the second growth phase. Thus, at low temperatures, psychotrophic P. fluorescens oxidized glucose to extracellular 2-KG, while growing on preferred carbon sources. The 2-KG was then catabolized after depletion of the organic acid.

  9. The effect of nitrogen and carbon sources on proteinase production by Pseudomonas fluorescens.

    PubMed

    Fairbairn, D J; Law, B A

    1987-02-01

    Some factors influencing the production of an extracellular proteinase by Pseudomonas fluorescens NCDO 2085 were studied. Proteinase production was optimal at 20 degrees C and pH 6.9 in static culture when calcium was included in the medium. Proteinase was not detectable in basal medium but could be induced by organic nitrogen compounds. The proteinase was produced in the exponential phase of growth on protein substrates but not until early stationary phase during growth on amino acids. The organism did not utilize lactose, the most abundant carbohydrate in milk. Citrate was readily utilized as an energy source but had a strong repressive effect on proteinase production. A medium containing sodium caseinate and pyruvate supported good growth and enzyme production. All the amino acids utilized as a sole carbon source, with the exception of serine, could induce proteinase production. Asparagine was the most effective amino acid inducer. Particular combinations of amino acids could induce or repress proteinase production. The regulation of proteinase production by Ps. fluorescens NCDO 2085 appears to be based on a balance between induction by low concentrations of low molecular weight degradation products and sensitivity to end product catabolite repression. The results suggest that the function of the proteinase is to ensure a supply of carbon rather than amino acids for protein synthesis.

  10. Three alginate lyases from marine bacterium Pseudomonas fluorescens HZJ216: purification and characterization.

    PubMed

    Li, Liyan; Jiang, Xiaolu; Guan, Huashi; Wang, Peng; Guo, Hong

    2011-06-01

    Three alginate lyases (A, B, and C) from an alginate-degrading marine bacterium strain HZJ216 isolated from brown seaweed in the Yellow Sea of China and identified preliminarily as Pseudomonas fluorescens are purified, and their biochemical properties are described. Molecular masses of the three enzymes are determined by SDS-PAGE to be 60.25, 36, and 23 kDa with isoelectric points of 4, 4.36, and 4.59, respectively. Investigations of these enzymes at different pH and temperatures show that they are most active at pH 7.0 and 35 °C. Alginate lyases A and B are stable in the pH range of 5.0-9.0, while alginate lyase C is stable in the pH range of 5.0-7.0. Among the metal ions tested, additions of Na(+), K(+), and Mg(2+) ions can enhance the enzyme activities while Fe(2+), Fe(3+), Ba(2+), and Zn(2+) ions show inhibitory effects. The substrate specificity results demonstrate that alginate lyase C has the specificity for G block while alginate lyases A and B have the activities for both M and G blocks. It is the first report about extracellular alginate lyases with high alginate-degrading activity from P. fluorescens.

  11. Cyanide production by Pseudomonas fluorescens helps suppress black root rot of tobacco under gnotobiotic conditions

    PubMed Central

    Voisard, Christophe; Keel, Christoph; Haas, Dieter; Dèfago, Geneviève

    1989-01-01

    Pseudomonas fluorescens CHA0 suppresses black root rot of tobacco, a disease caused by the fungus Thielaviopsis basicola. Strain CHA0 excretes several metabolites with antifungal properties. The importance of one such metabolite, hydrogen cyanide, was tested in a gnotobiotic system containing an artificial, iron-rich soil. A cyanidenegative (hcn) mutant, CHA5, constructed by a gene replacement technique, protected the tobacco plant less effectively than did the wild-type CHA0. Complementation of strain CHA5 by the cloned wild-type hcn+ genes restored the strain's ability to suppress disease. An artificial transposon carrying the hcn+ genes of strain CHA0 (Tnhcn) was constructed and inserted into the genome of another P.fluorescens strain, P3, which naturally does not produce cyanide and gives poor plant protection. The P3::Tnhcn derivative synthesized cyanide and exhibited an improved ability to suppress disease. All bacterial strains colonized the roots similarly and did not influence significantly the survival of T.basicola in soil. We conclude that bacterial cyanide is an important but not the only factor involved in suppression of black root rot. Images PMID:16453871

  12. Three Alginate Lyases from Marine Bacterium Pseudomonas fluorescens HZJ216: Purification and Characterization

    SciTech Connect

    Liyan, Li; Jiang, Xiaolu; Wang, Peng; Guan, Huashi; Guo, Hong

    2010-01-01

    Three alginate lyases (A, B, and C) from an alginate-degrading marine bacterium strain HZJ216 isolated from brown seaweed in the Yellow Sea of China and identified preliminarily as Pseudomonas fluorescens are purified, and their biochemical properties are described. Molecular masses of the three enzymes are determined by SDS-PAGE to be 60.25, 36, and 23 kDa with isoelectric points of 4, 4.36, and 4.59, respectively. Investigations of these enzymes at different pH and temperatures show that they are most active at pH 7.0 and 35 C. Alginate lyases A and B are stable in the pH range of 5.0 9.0, while alginate lyase C is stable in the pH range of 5.0 7.0. Among the metal ions tested, additions of Na+, K+, and Mg2+ ions can enhance the enzyme activities while Fe2+, Fe3+, Ba2+, and Zn2+ ions show inhibitory effects. The substrate specificity results demonstrate that alginate lyase C has the specificity for G block while alginate lyases A and B have the activities for both M and G blocks. It is the first report about extracellular alginate lyases with high alginate-degrading activity from P. fluorescens.

  13. Role of ptsP, orfT, and sss Recombinase Genes in Root Colonization by Pseudomonas fluorescens Q8r1-96▿

    PubMed Central

    Mavrodi, Olga V.; Mavrodi, Dmitri V.; Weller, David M.; Thomashow, Linda S.

    2006-01-01

    Pseudomonas fluorescens Q8r1-96 produces 2,4-diacetylphloroglucinol (2,4-DAPG), a polyketide antibiotic that suppresses a wide variety of soilborne fungal pathogens, including Gaeumannomyces graminis var. tritici, which causes take-all disease of wheat. Strain Q8r1-96 is representative of the D-genotype of 2,4-DAPG producers, which are exceptional because of their ability to aggressively colonize and maintain large populations on the roots of host plants, including wheat, pea, and sugar beet. In this study, three genes, an sss recombinase gene, ptsP, and orfT, which are important in the interaction of Pseudomonas spp. with various hosts, were investigated to determine their contributions to the unusual colonization properties of strain Q8r1-96. The sss recombinase and ptsP genes influence global processes, including phenotypic plasticity and organic nitrogen utilization, respectively. The orfT gene contributes to the pathogenicity of Pseudomonas aeruginosa in plants and animals and is conserved among saprophytic rhizosphere pseudomonads, but its function is unknown. Clones containing these genes were identified in a Q8r1-96 genomic library, sequenced, and used to construct gene replacement mutants of Q8r1-96. Mutants were characterized to determine their 2,4-DAPG production, motility, fluorescence, colony morphology, exoprotease and hydrogen cyanide (HCN) production, carbon and nitrogen utilization, and ability to colonize the rhizosphere of wheat grown in natural soil. The ptsP mutant was impaired in wheat root colonization, whereas mutants with mutations in the sss recombinase gene and orfT were not. However, all three mutants were less competitive than wild-type P. fluorescens Q8r1-96 in the wheat rhizosphere when they were introduced into the soil by paired inoculation with the parental strain. PMID:16936061

  14. Full Virulence of Pseudomonas aeruginosa Requires OprF▿

    PubMed Central

    Fito-Boncompte, Laurène; Chapalain, Annelise; Bouffartigues, Emeline; Chaker, Hichem; Lesouhaitier, Olivier; Gicquel, Gwendoline; Bazire, Alexis; Madi, Amar; Connil, Nathalie; Véron, Wilfried; Taupin, Laure; Toussaint, Bertrand; Cornelis, Pierre; Wei, Qing; Shioya, Koki; Déziel, Eric; Feuilloley, Marc G. J.; Orange, Nicole; Dufour, Alain; Chevalier, Sylvie

    2011-01-01

    OprF is a general outer membrane porin of Pseudomonas aeruginosa, a well-known human opportunistic pathogen associated with severe hospital-acquired sepsis and chronic lung infections of cystic fibrosis patients. A multiphenotypic approach, based on the comparative study of a wild-type strain of P. aeruginosa, its isogenic oprF mutant, and an oprF-complemented strain, showed that OprF is required for P. aeruginosa virulence. The absence of OprF results in impaired adhesion to animal cells, secretion of ExoT and ExoS toxins through the type III secretion system (T3SS), and production of the quorum-sensing-dependent virulence factors pyocyanin, elastase, lectin PA-1L, and exotoxin A. Accordingly, in the oprF mutant, production of the signal molecules N-(3-oxododecanoyl)-l-homoserine lactone and N-butanoyl-l-homoserine lactone was found to be reduced and delayed, respectively. Pseudomonas quinolone signal (PQS) production was decreased, while its precursor, 4-hydroxy-2-heptylquinoline (HHQ), accumulated in the cells. Taken together, these results show the involvement of OprF in P. aeruginosa virulence, at least partly through modulation of the quorum-sensing network. This is the first study showing a link between OprF, PQS synthesis, T3SS, and virulence factor production, providing novel insights into virulence expression. PMID:21189321

  15. Biodegradation of benzidine based azodyes Direct red and Direct blue by the immobilized cells of Pseudomonas fluorescens D41.

    PubMed

    Puvaneswari, N; Muthukrishnan, J; Gunasekaran, P

    2002-10-01

    Benzidine based azodyes are proven carcinogens, mutagens and have been linked to bladder cancer of human beings and laboratory animals. The textile and dyestuff manufacturing industry are the two major sources that released azodyes in their effluents. The dye, Direct blue contains two carcinogenic compounds namely benzidine (BZ), 4-amino biphenyl (4-ABP), while the dye Direct red has benzidine (BZ). Among 40 isolates of Pseudomonas fluorescens screened, one isolate designated as D41 was found to be capable of extensively degrading the dyes Direct blue and Direct red. Immobilized cells of P. fluorescens D41 efficiently degraded Direct red (82%) and Direct blue (71%) in the presence of glucose.

  16. Whole-Genome Sequence of Pseudomonas fluorescens EK007-RG4, a Promising Biocontrol Agent against a Broad Range of Bacteria, Including the Fire Blight Bacterium Erwinia amylovora

    PubMed Central

    Habibi, Roghayeh; Tarighi, Saeed; Behravan, Javad; Taheri, Parissa; Kjøller, Annelise Helene; Brejnrod, Asker; Madsen, Jonas Stenløkke

    2017-01-01

    ABSTRACT Here, we report the first draft whole-genome sequence of Pseudomonas fluorescens strain EK007-RG4, which was isolated from the phylloplane of a pear tree. P. fluorescens EK007-RG4 displays strong antagonism against Erwinia amylovora, the causal agent for fire blight disease, in addition to several other pathogenic and non-pathogenic bacteria. PMID:28360179

  17. Draft Genome Sequence of Pseudomonas fluorescens ML11A, an Endogenous Strain from Brook Charr with Antagonistic Properties against Aeromonas salmonicida subsp. salmonicida

    PubMed Central

    Charette, Steve J.; Derome, Nicolas

    2017-01-01

    ABSTRACT Pseudomonas fluorescens ML11A, isolated from brook charr, showed a strong in vitro inhibitory effect against Aeromonas salmonicida subsp. salmonicida, a bacterial fish pathogen. Its genome harbors gene clusters for siderophore and bacteriocin biosynthesis and shares 99% whole-genome identity with P. fluorescens A506, a biological control strain used in agriculture. PMID:28254983

  18. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level.

    PubMed

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein; Ertesvåg, Helga

    2015-12-11

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface.

  19. Physicochemical Properties of Biosurfactant Produced by Pseudomonas fluorescens Grown on Whey Tofu

    NASA Astrophysics Data System (ADS)

    Suryanti, V.; Handayani, D. S.; Marliyana, S. D.; Suratmi, S.

    2017-02-01

    The research aims to examine the physicochemical properties of biosurfactant produced by Pseudomonas fluorescens. Biosurfactant was produced in whey tofu media containing 8 g/L nutrient broth and 5 g/L NaCl which was fermented for 2 days at room temperature. Biosurfactant was identified as rhamnolipids which had critical micelle concentration (CMC) value of 638 mg/L and surface tension of 54 mN/m. The biosurfactant had water in oil (w/o) emulsion type. The biosurfactant was able to decrease the interfacial tension more than 40% for emulsion of water with hexane, pentane, benzene, lubricants or kerosene. The stable emulsions were reached up to 30 days with the E24 value of about 50% when paraffin, toluene, lubricants or palm oil was used as an immiscible compound. Commercial surfactants, such as Triton X-100 and Tween-80 were investigated to compare their emulsification activities and emulsion stabilities with the produced biosurfactant.

  20. Microbial transformations of ferulic acid by Saccharomyces cerevisiae and Pseudomonas fluorescens.

    PubMed Central

    Huang, Z; Dostal, L; Rosazza, J P

    1993-01-01

    Saccharomyces cerevisiae (dry baker's yeast) and Pseudomonas fluorescens were used to convert trans-ferulic acid into 4-hydroxy-3-methoxystyrene in 96 and 89% yields, respectively. The metabolites were isolated by solid-phase extraction and analyzed by thin-layer chromatography and high-performance liquid chromatography. The identities of the metabolites were determined by 1H- and 13C-nuclear magnetic resonance spectroscopy and by mass spectrometry. The mechanism of the decarboxylation of ferulic acid was investigated by measuring the degree and position of deuterium incorporated into the styrene derivative from D2O by mass spectrometry and by both proton and deuterium nuclear magnetic resonance spectroscopies. Resting cells of baker's yeast reduced ferulic acid to 4-hydroxy-3-methoxyphenylpropionic acid in 54% yield when incubations were under an argon atmosphere. PMID:8395165

  1. [Boot colonization of wheat by lux-AB genes marked Pseudomonas fluorescens Xl6L2].

    PubMed

    Wang, P; Hu, Z; Li, F

    2000-04-01

    Colonization density of Pseudomonas fluorescens Xl6L2 marked with luxAB genes in wheat rhizosphere in asepsis rhizobox-Calcareous chao soil microcosms reached the maximum(4.60 log cfu.g-1 root) 3 days after seeds coated with Pf.Xl6L2 sown, then declined to a relatively stable lower level(2.45 log cfu.g-1 root) in 0-2 cm root segment. Dynamics of colonization of Pf.Xl6L2 in wheat rhizosphere under field conditions was the same as in microcosms, Pf.Xl6L2 could move to the place of 10 cm of root from seeds under field conditions, distance of horizontal movement of Pf.Xl6L2 in field soil was not over 40 cm during 125 days of plant growth.

  2. Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level

    PubMed Central

    Maleki, Susan; Almaas, Eivind; Zotchev, Sergey; Valla, Svein

    2015-01-01

    Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface. PMID:26655760

  3. Antimicrobial Activity of Olive Mill Wastewater Extract Against Pseudomonas Fluorescens Isolated from Mozzarella Cheese

    PubMed Central

    Roila, Rossana; Branciari, Raffaella; Ortenzi, Roberta; Urbani, Stefania; Servili, Maurizio; Valiani, Andrea

    2016-01-01

    Olive mill wastewater polyphenol extract was tested for antimicrobial activity against 64 strains of Pseudomonas fluorescens responsible for mozzarella discolouration. The extract showed a minimum inhibitory concentration (MIC)50 value of 5 mg/mL and a MIC90 value of 7 mg/mL. The MBC50 and MBC90 values corresponded to 6 and 8 mg/mL, respectively. The MIC concentration (7 mg/mL) was demonstrated to have a bacteriostatic effect while maintaining the bacterial concentration on the levels of the inoculum for 48 hours. The 3/2 MIC concentration was responsible for four logs CFU/mL depletion in colony count after 24 h. As the extract concentration decreased from MIC value, no inhibitory effects were recorded. PMID:27800450

  4. Strain Diversity of Pseudomonas fluorescens Group with Potential Blue Pigment Phenotype Isolated from Dairy Products.

    PubMed

    Chierici, Margherita; Picozzi, Claudia; La Spina, Marisa Grazia; Orsi, Carla; Vigentini, Ileana; Zambrini, Vittorio; Foschino, Roberto

    2016-08-01

    The blue discoloration in Mozzarella cheese comes from bacterial spoilage due to contamination with Pseudomonas. Fourteen Pseudomonas fluorescens strains from international collections and 55 new isolates of dominant bacterial populations from spoiled fresh cheese samples were examined to assess genotypic and phenotypic strain diversity. Isolates were identified by 16S rRNA gene sequencing and tested for the production of the blue pigment at various temperatures on Mascarpone agar and in Mozzarella preserving fluid (the salty water in which the cheese is conserved, which becomes enriched by cheese minerals and peptides during storage). Pulsed-field gel electrophoresis analysis after treatment with the endonuclease SpeI separated the isolates into 42 genotypes at a similarity level of 80%. Based on the pulsotype clustering, 12 representative strains producing the blue discoloration were chosen for the multilocus sequence typing targeting the gyrB, glnS, ileS, nuoD, recA, rpoB, and rpoD genes. Four new sequence typing profiles were discovered, and the concatenated sequences of the investigated loci grouped the tested strains into the so-called ''blue branch'' of the P. fluorescens phylogenetic tree, confirming the linkage between pigment production and a specific genomic cluster. Growth temperature affected pigment production; the blue discoloration appeared at 4 and 14°C but not at 30°C. Similarly, the carbon source influenced the phenomenon; the blue phenotype was generated in the presence of glucose but not in the presence of galactose, sodium succinate, sodium citrate, or sodium lactate.

  5. Semi-scale production of PHAs from waste frying oil by Pseudomonas fluorescens S48.

    PubMed

    Gamal, Rawia F; Abdelhady, Hemmat M; Khodair, Taha A; El-Tayeb, Tarek S; Hassan, Enas A; Aboutaleb, Khadiga A

    2013-01-01

    The present study aimed at developing a strategy to improve the volumetric production of PHAs by Pseudomonas fluorescens S48 using waste frying oil (WFO) as the sole carbon source. For this purpose, several cultivations were set up to steadily improve nutrients supply to attain high cell density and high biopolymer productivity. The production of PHAs was examined in a 14 L bioreactor as one-stage batch, two-stage batch, and high-cell-density fed-batch cultures. The highest value of polymer content in one-stage bioreactor was obtained after 60 h (33.7%). Whereas, the two-stage batch culture increased the polymer content to 50.1% after 54 h. High-cell-density (0.64 g/L) at continuous feeding rate 0.55 mL/l/h of WFO recorded the highest polymer content after 54 h (55.34%). Semi-scale application (10 L working volume) increased the polymer content in one-stage batch, two-stage batch and high cell density fed-batch cultures by about 12.3%, 5.8% and 11.3%, respectively, as compared with that obtained in 2 L fermentation culture. Six different methods for biopolymer extraction were done to investigate their efficiency for optimum polymer recovery. The maximum efficiency of solvent recovery of PHA was attained by chloroform-hypochlorite dispersion extraction. Gas chromatography (GC) analysis of biopolymer produced by Pseudomonas fluorescens S48 indicated that it solely composed of 3-hydrobutyric acid (98.7%). A bioplastic film was prepared from the obtained PHB. The isolate studied shares the same identical sequence, which is nearly the complete 16S rRNA gene. The identity of this sequence to the closest pseudomonads strains is about 98-99%. It was probably closely related to support another meaningful parsiomony analysis and construction of a phylogenetic tree. The isolate is so close to Egyptian strain named EG 639838.

  6. Influence of earthworm activity on gene transfer from Pseudomonas fluorescens to indigenous soil bacteria.

    PubMed Central

    Daane, L L; Molina, J A; Berry, E C; Sadowsky, M J

    1996-01-01

    We have developed a model system to assess the influence of earthworm activity on the transfer of plasmid pJP4 from an inoculated donor bacterium, Pseudomonas fluorescens C5t (pJP4), to indigenous soil microorganisms. Three different earthworm species (Lumbricus terrestris, Lumbricus rubellus, and Aporrectodea trapezoides), each with unique burrowing, casting, and feeding behaviors, were evaluated. Soil columns were inoculated on the surface with 10(8) cells per g of soil of the donor bacterium, and after a 2-week incubation period, donor, transconjugant, and total bacteria were enumerated at 5-cm-depth intervals. Transconjugants were confirmed by use of colony hybridization with a mer gene probe. In situ gene transfer of plasmid pJP4 from P. fluorescens C5t to indigenous soil bacteria was detected in all inoculated microcosms. In the absence of earthworms, the depth of recovery was limited to the top 5 cm of the column, with approximately 10(3) transconjugants per g of soil. However, the total number of transconjugants recovered from soil was significantly greater in microcosms containing either L. rubellus or A. trapezoides, with levels reaching about 10(5) CFU/g of soil. In addition, earthworms distributed donor and transconjugant bacteria throughout the microcosm columns, with the depth of recovery dependent on the burrowing behavior of each earthworm species. Donor and transconjugant bacteria were also recovered from earthworm casts and inside developing cocoons. Transconjugant bacteria from the indigenous soil microflora were classified as belonging to Acidovorax spp., Acinetobacter spp., Agrobacterium spp., Pasteurella spp., Pseudomonas spp., and Xanthomonas spp. PMID:8593052

  7. A network biology approach to denitrification in Pseudomonas aeruginosa

    DOE PAGES

    Arat, Seda; Bullerjahn, George S.; Laubenbacher, Reinhard

    2015-02-23

    Pseudomonas aeruginosa is a metabolically flexible member of the Gammaproteobacteria. Under anaerobic conditions and the presence of nitrate, P. aeruginosa can perform (complete) denitrification, a respiratory process of dissimilatory nitrate reduction to nitrogen gas via nitrite (NO₂), nitric oxide (NO) and nitrous oxide (N₂O). This study focuses on understanding the influence of environmental conditions on bacterial denitrification performance, using a mathematical model of a metabolic network in P. aeruginosa. To our knowledge, this is the first mathematical model of denitrification for this bacterium. Analysis of the long-term behavior of the network under changing concentration levels of oxygen (O₂), nitrate (NO₃),more » and phosphate (PO₄) suggests that PO₄ concentration strongly affects denitrification performance. The model provides three predictions on denitrification activity of P. aeruginosa under various environmental conditions, and these predictions are either experimentally validated or supported by pertinent biological literature. One motivation for this study is to capture the effect of PO₄ on a denitrification metabolic network of P. aeruginosa in order to shed light on mechanisms for greenhouse gas N₂O accumulation during seasonal oxygen depletion in aquatic environments such as Lake Erie (Laurentian Great Lakes, USA). Simulating the microbial production of greenhouse gases in anaerobic aquatic systems such as Lake Erie allows a deeper understanding of the contributing environmental effects that will inform studies on, and remediation strategies for, other hypoxic sites worldwide.« less

  8. Pseudomonas aeruginosa Virulence and Therapy: Evolving Translational Strategies

    PubMed Central

    Veesenmeyer, Jeffrey L.; Lisboa, Thiago; Rello, Jordi

    2009-01-01

    Structured abstract Objective Although most reviews of Pseudomonas aeruginosa therapeutics focus on antibiotics currently in use or in the pipeline, we review evolving translational strategies aimed at using virulence factor antagonists as adjuvant therapies. Data Source Current literature regarding P. aeruginosa virulence determinants and approaches that target them, with an emphasis on type III secretion, quorum-sensing, biofilms, and flagella. Data Extraction and Synthesis P. aeruginosa remains one of the most important pathogens in nosocomial infections, with high associated morbidity and mortality. Its predilection to develop resistance to antibiotics and expression of multiple virulence factors contributes to the frequent ineffectiveness of current therapies. Among the many P. aeruginosa virulence determinants that impact infections, type III secretion, quorum sensing, biofilm formation, and flagella have been the focus of much recent investigation. Here we review how increased understanding of these important bacterial structures and processes has enabled the development of novel approaches to inhibit each. These promising translational strategies may lead to the development of adjuvant therapies capable of improving outcomes. Conclusions Adjuvant therapies directed against virulence factors have the potential to improve outcomes in P. aeruginosa infections. PMID:19325463

  9. [Resistance to antibiotics in Pseudomonas aeruginosa in Colombian hospitals].

    PubMed

    Villa, Lina M; Cortés, Jorge A; Leal, Aura L; Meneses, Andrés; Meléndez, Martha P

    2013-12-01

    Pseudomonas aeruginosa infections cause high morbidity and mortality. We performed a descriptive analysis of the rates of antibiotic resistance in isolates of P. aeruginosa in 33 hospitals enrolled in a surveillance network in Colombia. The study was conducted between January 2005 and December 2009 .9905 isolates of P. aeruginosa were identified, (4.9% of all strains). In intensive care units (ICU) P. aeruginosa showed an overall resistance to aztreonam, cefepime , ceftazidime, imipenem, meropenem , and piperacillin / tazobactam of 31.8% , 23.9% , 24.8%, 22.5%, 20.3% and 22.3%, respectively. Resistance rates increased for piperacillin/tazobactam, cefepime, and imipenem; remained unchanged for meropenem; and decreased for aminoglycosides, quinolones and ceftazidime. Resistance to one, two and three or more families of antibiotics was found in 17%, 12.5%, and 32.1%, respectively. In samples collected from the wards, the resistance rate was lower but usually over 10%. Antibiotic resistance in P. aeruginosa isolates in hospitalized patients and particularly in those admitted to ICUs in Colombia is high.

  10. Gold-functionalized magnetic nanoparticles restrict growth of Pseudomonas aeruginosa.

    PubMed

    Niemirowicz, Katarzyna; Swiecicka, Izabela; Wilczewska, Agnieszka Z; Misztalewska, Iwona; Kalska-Szostko, Beata; Bienias, Kamil; Bucki, Robert; Car, Halina

    2014-01-01

    Superparamagnetic iron oxide nanoparticles (SPIONs) and their derivatives (aminosilane and gold-coated) have been widely investigated in numerous medical applications, including their potential to act as antibacterial drug carriers that may penetrate into bacteria cells and biofilm mass. Pseudomonas aeruginosa is a frequent cause of infection in hospitalized patients, and significant numbers of currently isolated clinical strains are resistant to standard antibiotic therapy. Here we describe the impact of three types of SPIONs on the growth of P. aeruginosa during long-term bacterial culture. Their size, structure, and physicochemical properties were determined using transmission electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. We observed significant inhibition of P. aeruginosa growth in bacterial cultures continued over 96 hours in the presence of gold-functionalized nanoparticles (Fe₃O₄@Au). At the 48-hour time point, growth of P. aeruginosa, as assessed by the number of colonies grown from treated samples, showed the highest inhibition (decreased by 40%). These data provide strong evidence that Fe₃O₄@Au can dramatically reduce growth of P. aeruginosa and provide a platform for further study of the antibacterial activity of this nanomaterial.

  11. The Genomic Basis of Evolutionary Innovation in Pseudomonas aeruginosa

    PubMed Central

    Wagner, Andreas; MacLean, R. Craig

    2016-01-01

    Novel traits play a key role in evolution, but their origins remain poorly understood. Here we address this problem by using experimental evolution to study bacterial innovation in real time. We allowed 380 populations of Pseudomonas aeruginosa to adapt to 95 different carbon sources that challenged bacteria with either evolving novel metabolic traits or optimizing existing traits. Whole genome sequencing of more than 80 clones revealed profound differences in the genetic basis of innovation and optimization. Innovation was associated with the rapid acquisition of mutations in genes involved in transcription and metabolism. Mutations in pre-existing duplicate genes in the P. aeruginosa genome were common during innovation, but not optimization. These duplicate genes may have been acquired by P. aeruginosa due to either spontaneous gene amplification or horizontal gene transfer. High throughput phenotype assays revealed that novelty was associated with increased pleiotropic costs that are likely to constrain innovation. However, mutations in duplicate genes with close homologs in the P. aeruginosa genome were associated with low pleiotropic costs compared to mutations in duplicate genes with distant homologs in the P. aeruginosa genome, suggesting that functional redundancy between duplicates facilitates innovation by buffering pleiotropic costs. PMID:27149698

  12. The Genomic Basis of Evolutionary Innovation in Pseudomonas aeruginosa.

    PubMed

    Toll-Riera, Macarena; San Millan, Alvaro; Wagner, Andreas; MacLean, R Craig

    2016-05-01

    Novel traits play a key role in evolution, but their origins remain poorly understood. Here we address this problem by using experimental evolution to study bacterial innovation in real time. We allowed 380 populations of Pseudomonas aeruginosa to adapt to 95 different carbon sources that challenged bacteria with either evolving novel metabolic traits or optimizing existing traits. Whole genome sequencing of more than 80 clones revealed profound differences in the genetic basis of innovation and optimization. Innovation was associated with the rapid acquisition of mutations in genes involved in transcription and metabolism. Mutations in pre-existing duplicate genes in the P. aeruginosa genome were common during innovation, but not optimization. These duplicate genes may have been acquired by P. aeruginosa due to either spontaneous gene amplification or horizontal gene transfer. High throughput phenotype assays revealed that novelty was associated with increased pleiotropic costs that are likely to constrain innovation. However, mutations in duplicate genes with close homologs in the P. aeruginosa genome were associated with low pleiotropic costs compared to mutations in duplicate genes with distant homologs in the P. aeruginosa genome, suggesting that functional redundancy between duplicates facilitates innovation by buffering pleiotropic costs.

  13. Pseudomonas aeruginosa Lifestyle: A Paradigm for Adaptation, Survival, and Persistence

    PubMed Central

    Moradali, M. Fata; Ghods, Shirin; Rehm, Bernd H. A.

    2017-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen affecting immunocompromised patients. It is known as the leading cause of morbidity and mortality in cystic fibrosis (CF) patients and as one of the leading causes of nosocomial infections. Due to a range of mechanisms for adaptation, survival and resistance to multiple classes of antibiotics, infections by P. aeruginosa strains can be life-threatening and it is emerging worldwide as public health threat. This review highlights the diversity of mechanisms by which P. aeruginosa promotes its survival and persistence in various environments and particularly at different stages of pathogenesis. We will review the importance and complexity of regulatory networks and genotypic-phenotypic variations known as adaptive radiation by which P. aeruginosa adjusts physiological processes for adaptation and survival in response to environmental cues and stresses. Accordingly, we will review the central regulatory role of quorum sensing and signaling systems by nucleotide-based second messengers resulting in different lifestyles of P. aeruginosa. Furthermore, various regulatory proteins will be discussed which form a plethora of controlling systems acting at transcriptional level for timely expression of genes enabling rapid responses to external stimuli and unfavorable conditions. Antibiotic resistance is a natural trait for P. aeruginosa and multiple mechanisms underlying different forms of antibiotic resistance will be discussed here. The importance of each mechanism in conferring resistance to various antipseudomonal antibiotics and their prevalence in clinical strains will be described. The underlying principles for acquiring resistance leading pan-drug resistant strains will be summarized. A future outlook emphasizes the need for collaborative international multidisciplinary efforts to translate current knowledge into strategies to prevent and treat P. aeruginosa infections while reducing the rate of antibiotic resistance

  14. Why Does the Healthy Cornea Resist Pseudomonas aeruginosa Infection?

    PubMed Central

    Evans, David J.; Fleiszig, Suzanne M. J.

    2013-01-01

    Purpose To provide our perspective on why the cornea is resistant to infection based on our research results with Pseudomonas aeruginosa. Perspective We focus on our current understanding of the interplay between bacteria, tear fluid and the corneal epithelium that determine health as the usual outcome, and propose a theoretical model for how contact lens wear might change those interactions to enable susceptibility to P. aeruginosa infection. Methods Use of “null-infection” in vivo models, cultured human corneal epithelial cells, contact lens-wearing animal models, and bacterial genetics help to elucidate mechanisms by which P. aeruginosa survive at the ocular surface, adheres, and traverses multilayered corneal epithelia. These models also help elucidate the molecular mechanisms of corneal epithelial innate defense. Results and Discussion Tear fluid and the corneal epithelium combine to make a formidable defense against P. aeruginosa infection of the cornea. Part of that defense involves the expression of antimicrobials such as β-defensins, the cathelicidin LL-37, cytokeratin-derived antimicrobial peptides, and RNase7. Immunomodulators such as SP-D and ST2 also contribute. Innate defenses of the cornea depend in part on MyD88, a key adaptor protein of TLR and IL-1R signaling, but the basal lamina represents the final barrier to bacterial penetration. Overcoming these defenses involves P. aeruginosa adaptation, expression of the type three secretion system, proteases, and P. aeruginosa biofilm formation on contact lenses. Conclusion After more than two decades of research focused on understanding how contact lens wear predisposes to P. aeruginosa infection, our working hypothesis places blame for microbial keratitis on bacterial adaptation to ocular surface defenses, combined with changes to the biochemistry of the corneal surface caused by trapping bacteria and tear fluid against the cornea under the lens. PMID:23601656

  15. Evaluation of flagella and flagellin of Pseudomonas aeruginosa as vaccines.

    PubMed

    Campodónico, Victoria L; Llosa, Nicolás J; Grout, Martha; Döring, Gerd; Maira-Litrán, Tomás; Pier, Gerald B

    2010-02-01

    Pseudomonas aeruginosa is a serious pathogen in hospitalized, immunocompromised, and cystic fibrosis (CF) patients. P. aeruginosa is motile via a single polar flagellum made of polymerized flagellin proteins differentiated into two major serotypes: a and b. Antibodies to flagella delay onset of infection in CF patients, but whether immunity to polymeric flagella and that to monomeric flagellin are comparable has not been addressed, nor has the question of whether such antibodies might negatively impact Toll-like receptor 5 (TLR5) activation, an important component of innate immunity to P. aeruginosa. We compared immunization with flagella and that with flagellin for in vitro effects on motility, opsonic killing, and protective efficacy using a mouse pneumonia model. Antibodies to flagella were superior to antibodies to flagellin at inhibiting motility, promoting opsonic killing, and mediating protection against P. aeruginosa pneumonia in mice. Protection against the flagellar type strains PAK and PA01 was maximal, but it was only marginal against motile clinical isolates from flagellum-immunized CF patients who nonetheless became colonized with P. aeruginosa. Purified flagellin was a more potent activator of TLR5 than were flagella and also elicited higher TLR5-neutralizing antibodies than did immunization with flagella. Antibody to type a but not type b flagella or flagellin inhibited TLR5 activation by whole bacterial cells. Overall, intact flagella appear to be superior for generating immunity to P. aeruginosa, and flagellin monomers might induce antibodies capable of neutralizing innate immunity due to TLR5 activation, but solid immunity to P. aeruginosa based on flagellar antigens may require additional components beyond type a and type b proteins from prototype strains.

  16. Pseudomonas aeruginosa Lifestyle: A Paradigm for Adaptation, Survival, and Persistence.

    PubMed

    Moradali, M Fata; Ghods, Shirin; Rehm, Bernd H A

    2017-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen affecting immunocompromised patients. It is known as the leading cause of morbidity and mortality in cystic fibrosis (CF) patients and as one of the leading causes of nosocomial infections. Due to a range of mechanisms for adaptation, survival and resistance to multiple classes of antibiotics, infections by P. aeruginosa strains can be life-threatening and it is emerging worldwide as public health threat. This review highlights the diversity of mechanisms by which P. aeruginosa promotes its survival and persistence in various environments and particularly at different stages of pathogenesis. We will review the importance and complexity of regulatory networks and genotypic-phenotypic variations known as adaptive radiation by which P. aeruginosa adjusts physiological processes for adaptation and survival in response to environmental cues and stresses. Accordingly, we will review the central regulatory role of quorum sensing and signaling systems by nucleotide-based second messengers resulting in different lifestyles of P. aeruginosa. Furthermore, various regulatory proteins will be discussed which form a plethora of controlling systems acting at transcriptional level for timely expression of genes enabling rapid responses to external stimuli and unfavorable conditions. Antibiotic resistance is a natural trait for P. aeruginosa and multiple mechanisms underlying different forms of antibiotic resistance will be discussed here. The importance of each mechanism in conferring resistance to various antipseudomonal antibiotics and their prevalence in clinical strains will be described. The underlying principles for acquiring resistance leading pan-drug resistant strains will be summarized. A future outlook emphasizes the need for collaborative international multidisciplinary efforts to translate current knowledge into strategies to prevent and treat P. aeruginosa infections while reducing the rate of antibiotic resistance

  17. pA506, a Conjugative Plasmid of the Plant Epiphyte Pseudomonas fluorescens A506

    PubMed Central

    Stockwell, Virginia O.; Davis, Edward W.; Carey, Alyssa; Shaffer, Brenda T.; Mavrodi, Dmitri V.; Hassan, Karl A.; Hockett, Kevin; Thomashow, Linda S.; Paulsen, Ian T.

    2013-01-01

    Conjugative plasmids are known to facilitate the acquisition and dispersal of genes contributing to the fitness of Pseudomonas spp. Here, we report the characterization of pA506, the 57-kb conjugative plasmid of Pseudomonas fluorescens A506, a plant epiphyte used in the United States for the biological control of fire blight disease of pear and apple. Twenty-nine of the 67 open reading frames (ORFs) of pA506 have putative functions in conjugation, including a type IV secretion system related to that of MOBP6 family plasmids and a gene cluster for type IV pili. We demonstrate that pA506 is self-transmissible via conjugation between A506 and strains of Pseudomonas spp. or the Enterobacteriaceae. The origin of vegetative replication (oriV) of pA506 is typical of those in pPT23A family plasmids, which are present in many pathovars of Pseudomonas syringae, but pA506 lacks repA, a defining locus for pPT23A plasmids, and has a novel partitioning region. We selected a plasmid-cured derivative of A506 and compared it to the wild type to identify plasmid-encoded phenotypes. pA506 conferred UV resistance, presumably due to the plasmid-borne rulAB genes, but did not influence epiphytic fitness of A506 on pear or apple blossoms in the field. pA506 does not appear to confer resistance to antibiotics or other toxic elements. Based on the conjugative nature of pA506 and the large number of its genes that are shared with plasmids from diverse groups of environmental bacteria, the plasmid is likely to serve as a vehicle for genetic exchange between A506 and its coinhabitants on plant surfaces. PMID:23811504

  18. Environmental Pseudomonads Inhibit Cystic Fibrosis Patient-Derived Pseudomonas aeruginosa

    PubMed Central

    Chatterjee, Payel; Davis, Elizabeth; Yu, Fengan; James, Sarah; Wildschutte, Julia H.; Wiegmann, Daniel D.; Sherman, David H.; McKay, Robert M.; LiPuma, John J.

    2016-01-01

    ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen which is evolving resistance to many currently used antibiotics. While much research has been devoted to the roles of pathogenic P. aeruginosa in cystic fibrosis (CF) patients, less is known of its ecological properties. P. aeruginosa dominates the lungs during chronic infection in CF patients, yet its abundance in some environments is less than that of other diverse groups of pseudomonads. Here, we sought to determine if clinical isolates of P. aeruginosa are vulnerable to environmental pseudomonads that dominate soil and water habitats in one-to-one competitions which may provide a source of inhibitory factors. We isolated a total of 330 pseudomonads from diverse habitats of soil and freshwater ecosystems and competed these strains against one another to determine their capacity for antagonistic activity. Over 900 individual inhibitory events were observed. Extending the analysis to P. aeruginosa isolates revealed that clinical isolates, including ones with increased alginate production, were susceptible to competition by multiple environmental strains. We performed transposon mutagenesis on one isolate and identified an ∼14.8-kb locus involved in antagonistic activity. Only two other environmental isolates were observed to carry the locus, suggesting the presence of additional unique compounds or interactions among other isolates involved in outcompeting P. aeruginosa. This collection of strains represents a source of compounds that are active against multiple pathogenic strains. With the evolution of resistance of P. aeruginosa to currently used antibiotics, these environmental strains provide opportunities for novel compound discovery against drug-resistant clinical strains. IMPORTANCE We demonstrate that clinical CF-derived isolates of P. aeruginosa are susceptible to competition in the presence of environmental pseudomonads. We observed that many diverse environmental strains exhibited varied

  19. Classification of Isolates from the Pseudomonas fluorescens Complex into Phylogenomic Groups Based in Group-Specific Markers

    PubMed Central

    Garrido-Sanz, Daniel; Arrebola, Eva; Martínez-Granero, Francisco; García-Méndez, Sonia; Muriel, Candela; Blanco-Romero, Esther; Martín, Marta; Rivilla, Rafael; Redondo-Nieto, Miguel

    2017-01-01

    The Pseudomonas fluorescens complex of species includes plant-associated bacteria with potential biotechnological applications in agriculture and environmental protection. Many of these bacteria can promote plant growth by different means, including modification of plant hormonal balance and biocontrol. The P. fluorescens group is currently divided into eight major subgroups in which these properties and many other ecophysiological traits are phylogenetically distributed. Therefore, a rapid phylogroup assignment for a particular isolate could be useful to simplify the screening of putative inoculants. By using comparative genomics on 71 P. fluorescens genomes, we have identified nine markers which allow classification of any isolate into these eight subgroups, by a presence/absence PCR test. Nine primer pairs were developed for the amplification of these markers. The specificity and sensitivity of these primer pairs were assessed on 28 field isolates, environmental samples from soil and rhizosphere and tested by in silico PCR on 421 genomes. Phylogenomic analysis validated the results: the PCR-based system for classification of P. fluorescens isolates has a 98.34% of accuracy and it could be used as a rapid and simple assay to evaluate the potential of any P. fluorescens complex strain. PMID:28360897

  20. Volatile organic compounds produced by Pseudomonas fluorescens WR-1 restrict the growth and virulence traits of Ralstonia solanacearum.

    PubMed

    Raza, Waseem; Ling, Ning; Liu, Dongyang; Wei, Zhong; Huang, Qiwei; Shen, Qirong

    2016-11-01

    The volatile organic compounds (VOCs) produced by soil microbes have a significant role in the control of plant diseases and plant growth promotion. In this study, we examined the effect of VOCs produced by Pseudomonas fluorescens strain WR-1 on the growth and virulence traits of tomato wilt pathogen Ralstonia solanacearum. The VOCs produced by P. fluorescens WR-1 exhibited concentration dependent bacteriostatic effect on the growth of R. solanacearum on agar medium and in infested soil. The VOCs of P. fluorescens WR-1 also significantly inhibited the virulence traits of R. solanacearum. The proteomics analysis showed that the VOCs of P. fluorescens WR-1 downregulated cellular proteins of R. solanacearum related to the antioxidant activity, virulence, inclusion body proteins, carbohydrate and amino acid synthesis and metabolism, protein folding and translation, methylation and energy transfer, while the proteins involved in the ABC transporter system, detoxification of aldehydes and ketones, protein folding and translation were upregulated. This study revealed the significance of VOCs of P. fluorescens WR-1 to control the tomato wilt pathogen R. solanacearum. Investigation of the modes of action of biocontrol agents is important to better comprehend the interactions mediated by VOCs in nature to design better control strategies for plant pathogens.

  1. Adherence of Pseudomonas aeruginosa to contact lenses

    SciTech Connect

    Miller, M.J.

    1988-01-01

    The purpose of this research was to examined the interactions of P. aeruginosa with hydrogel contact lenses and other substrata, and characterize adherence to lenses under various physiological and physicochemical conditions. Isolates adhered to polystyrene, glass, and hydrogel lenses. With certain lens types, radiolabeled cells showed decreased adherence with increasing water content of the lenses, however, this correlation with not found for all lenses. Adherence to rigid gas permeable lenses was markedly greater than adherence to hydrogels. Best adherence occurred near pH 7 and at a sodium chloride concentration of 50 mM. Passive adhesion of heat-killed cells to hydrogels was lower than the adherence obtained of viable cells. Adherence to hydrogels was enhanced by mucin, lactoferrin, lysozyme, IgA, bovine serum albumin, and a mixture of these macromolecules. Adherence to coated and uncoated lenses was greater with a daily-wear hydrogel when compared with an extended-wear hydrogel of similar polymer composition. Greater adherence was attributed to a higher concentration of adsorbed macromolecules on the 45% water-content lens in comparison to the 55% water-content lens.

  2. INHIBITION OF VIRULENCE FACTORS OF PSEUDOMONAS AERUGINOSA BY DICLOFENAC SODIUM.

    PubMed

    Abbas, Hisham A

    2015-01-01

    Resistance of Pseudomonas aeruginosa to antibiotics is a major problem. Targeting virulence factors is an alternative option to avoid the emergence of resistance to antibiotics. The effect of sub-inhibitory concentration of diclofenac sodium on the production of virulence factors of P. aeruginosa was investigated. The virulence factors included protease, haemolysin, pyocyanin and pyoverdin, in addition to pathogenic behaviors such as swimming and twitching motilities and biofilm formation. Diclofenac sodium showed significant inhibition of virulence factors as compared to the control. Diclofenac sodium decreased twitching and swimming motilities by 29.27% and 45.36%, respectively. The percentage of inhibition of pyocyanin by diclofenac sodium was 42.32%. On the other hand, pyoverdin was inhibited to a lesser extent (36.72%). Diclofenac sodium reduced protease by 52.58% and biofilm formation by 58.37%. Moreover, haemolytic activity in the presence of diclofenac sodium was 15.64% as compared to the control (100% haemolytic activity). The inhibitory activities may be due to inhibition of quorum sensing that regulates the expression of virulence factors. This study suggests the potential for the use of diclofenac sodium as an anti-virulence agent in the treatment of Pseudomonas aeruginosa infections.

  3. Pseudomonas fluorescens LBUM223 Increases Potato Yield and Reduces Common Scab Symptoms in the Field.

    PubMed

    Arseneault, Tanya; Goyer, Claudia; Filion, Martin

    2015-10-01

    Common scab of potato, caused by pathogenic Streptomyces spp., is an important disease not efficiently controlled by current methods. We previously demonstrated that Pseudomonas fluorescens LBUM223 reduces common scab development under controlled conditions through phenazine-1-carboxylic (PCA) production, leading to reduced thaxtomin A production by the pathogen, a key pathogenicity and virulence factor. Here, we aimed at determining if LBUM223 is able to increase potato yield and control common scab under field conditions, while characterizing the biocontrol mechanisms involved. We investigated if a reduction in pathogen soil populations, activation of induced systemic resistance in potato, and/or changes in txtA gene expression, involved in thaxtomin A biosynthesis in pathogenic Streptomyces spp. were involved in common scab control by LBUM223. Common scab symptoms were significantly reduced and total tuber weight increased by 46% using biweekly applications of LBUM223. LBUM223 did not reduce pathogen soil populations, nor was potato systemic defense-related gene expression significantly altered between treatments. However, a significant down-regulation of txtA expression occurred in the geocaulosphere. This is the first demonstration that a Pseudomonas strain can directly alter the transcriptional activity of a key pathogenesis gene in a plant pathogen under field conditions, contributing to disease control.

  4. Crystal structure of the terminal oxygenase component of cumene dioxygenase from Pseudomonas fluorescens IP01.

    PubMed

    Dong, Xuesong; Fushinobu, Shinya; Fukuda, Eriko; Terada, Tohru; Nakamura, Shugo; Shimizu, Kentaro; Nojiri, Hideaki; Omori, Toshio; Shoun, Hirofumi; Wakagi, Takayoshi

    2005-04-01

    The crystal structure of the terminal component of the cumene dioxygenase multicomponent enzyme system of Pseudomonas fluorescens IP01 (CumDO) was determined at a resolution of 2.2 A by means of molecular replacement by using the crystal structure of the terminal oxygenase component of naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4 (NphDO). The ligation of the two catalytic centers of CumDO (i.e., the nonheme iron and Rieske [2Fe-2S] centers) and the bridging between them in neighboring catalytic subunits by hydrogen bonds through a single amino acid residue, Asp231, are similar to those of NphDO. An unidentified external ligand, possibly dioxygen, was bound at the active site nonheme iron. The entrance to the active site of CumDO is different from the entrance to the active site of NphDO, as the two loops forming the lid exhibit great deviation. On the basis of the complex structure of NphDO, a biphenyl substrate was modeled in the substrate-binding pocket of CumDO. The residues surrounding the modeled biphenyl molecule include residues that have already been shown to be important for its substrate specificity by a number of engineering studies of biphenyl dioxygenases.

  5. Host defense mechanisms against pneumonia due to Pseudomonas aeruginosa.

    PubMed

    Pennington, J E; Ehrie, M G; Hickey, W F

    1984-01-01

    Pneumonia due to Pseudomonas aeruginosa is associated with unusually high mortalities. Accordingly, efforts to define better the most important components of lung defenses against this infection are justified as a prelude to defining improved management strategies. In this report, a guinea pig model of experimental aspiration pseudomonas pneumonia was employed for studies of cellular and humoral mechanisms of pulmonary defense. Animals treated with cortisone acetate plus cyclophosphamide experienced decreased survival from pneumonia, and survival rates correlated directly with the degree of myelosuppression. Numbers of pulmonary macrophages and polymorphonuclear neutrophils were reduced in drug-treated animals before impairment of macrophage antibacterial function. Thus, a reduction in numbers of phagocytes alone was sufficient to markedly reduce lung defenses. In additional experiments, normal guinea pigs were vaccinated with a lipopolysaccharide pseudomonas vaccine. Improved survival from pneumonia correlated with high titers of type-specific, heat-stable opsonic antibody. It is concluded that adequate numbers of lung phagocytes, plus type-specific opsonic antibody, represent the ideal status for lung defense against P. aeruginosa infection.

  6. Monocyte Profiles in Critically Ill Patients With Pseudomonas Aeruginosa Sepsis

    ClinicalTrials.gov

    2017-02-02

    Pseudomonas Infections; Pseudomonas Septicemia; Pseudomonas; Pneumonia; Pseudomonal Bacteraemia; Pseudomonas Urinary Tract Infection; Pseudomonas Gastrointestinal Tract Infection; Sepsis; Sepsis, Severe; Critically Ill

  7. Dueling quorum sensing systems in Pseudomonas aeruginosa control the production of the Pseudomonas quinolone signal (PQS).

    PubMed

    McGrath, Stephen; Wade, Dana S; Pesci, Everett C

    2004-01-15

    The opportunistic human pathogen Pseudomonas aeruginosa regulates the production of numerous virulence factors via the action of two separate but coordinated quorum sensing systems, las and rhl. These systems control the transcription of genes in response to population density through the intercellular signals N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C(12)-HSL) and N-(butanoyl)-L-homoserine lactone (C(4)-HSL). A third P. aeruginosa signal, 2-heptyl-3-hydroxy-4-quinolone [Pseudomonas quinolone signal (PQS)], also plays a significant role in the transcription of multiple P. aeruginosa virulence genes. PQS is intertwined in the P. aeruginosa quorum sensing hierarchy with its production and bioactivity requiring the las and rhl quorum sensing systems, respectively. This report presents a preliminary transcriptional analysis of pqsA, the first gene of the recently discovered PQS biosynthetic gene cluster. We show that pqsA transcription required pqsR, a transcriptional activator protein encoded within the PQS biosynthetic gene cluster. It was also found that the transcription of pqsA and subsequent production of PQS was induced by the las quorum sensing system and repressed by the rhl quorum sensing system. In addition, PQS production was dependent on the ratio of 3-oxo-C(12)-HSL to C(4)-HSL, suggesting a regulatory balance between quorum sensing systems. These data are an important early step toward understanding the regulation of PQS synthesis and the role of PQS in P. aeruginosa intercellular signaling.

  8. Identification of Pythium carolinianum causing 'root rot' of cotton in Egypt and its possible biological control by Pseudomonas fluorescens.

    PubMed

    Abdelzaher, H M; Elnaghy, M A

    1998-01-01

    A severe root rot disease of cotton caused by Pythium carolinianum was diagnosed in a cotton field in Beni-Musa village, 20 km southwest of El-Minia city, Egypt, during the summer of 1996. This was the first reported isolation of this fungus in Egypt. In the light of the importance of the cotton industry in Egypt, research was initiated to develop a biocontrol agent against Pythium carolinianum. In vitro agar plate technique identified a Pseudomonas fluorescens strain that was highly antagonist to Pythium carolinianum. Subsequent plant growth experiments establish that substantial disease control could be obtained by applying Pseudomonas fluorescens to the soil. Optimal control was obtained by mixing the bacteria with the soil rather than by dipping the cotton roots in the bacterial suspension immediately before planting. Disease was more severe in autoclaved soil than in nonsterile soil.

  9. Inhibition of Pseudomonas aeruginosa biofilm formation on wound dressings

    PubMed Central

    Brandenburg, Kenneth S.; Calderon, Diego F.; Kierski, Patricia R.; Brown, Amanda L.; Shah, Nihar M.; Abbott, Nicholas L.; Schurr, Michael J.; Murphy, Christopher J.; McAnulty, Jonathan F.; Czuprynski, Charles J.

    2016-01-01

    Chronic non-healing skin wounds often contain bacterial biofilms that prevent normal wound healing and closure and present challenges to the use of conventional wound dressings. We investigated inhibition of Pseudomonas aeruginosa biofilm formation, a common pathogen of chronic skin wounds, on a commercially available biological wound dressing. Building upon prior reports, we examined whether the amino acid tryptophan would inhibit P. aeruginosa biofilm formation on the 3-dimensional surface of the biological dressing. Bacterial biomass and biofilm polysaccharides were quantified using crystal violet staining or an enzyme linked lectin, respectively. Bacterial cells and biofilm matrix adherent to the wound dressing were visualized through scanning electron microscopy. D-/L-tryptophan inhibited P. aeruginosa biofilm formation on the wound dressing in a dose dependent manner and was not directly cytotoxic to immortalized human keratinocytes although there was some reduction in cellular metabolism or enzymatic activity. More importantly, D-/L-tryptophan did not impair wound healing in a splinted skin wound murine model. Furthermore, wound closure was improved when D-/L-tryptophan treated wound dressing with P. aeruginosa biofilms were compared with untreated dressings. These findings indicate that tryptophan may prove useful for integration into wound dressings to inhibit biofilm formation and promote wound healing. PMID:26342168

  10. 7-fluoroindole as an antivirulence compound against Pseudomonas aeruginosa.

    PubMed

    Lee, Jin-Hyung; Kim, Yong-Guy; Cho, Moo Hwan; Kim, Jung-Ae; Lee, Jintae

    2012-04-01

    The emergence of antibiotic resistance has necessitated new therapeutic approaches for combating persistent bacterial infection. An alternative approach is regulation of bacterial virulence instead of growth suppression, which can readily lead to drug resistance. The virulence of the opportunistic human pathogen Pseudomonas aeruginosa depends on a large number of extracellular factors and biofilm formation. Thirty-one natural and synthetic indole derivatives were screened. 7-fluoroindole (7FI) was identified as a compound that inhibits biofilm formation and blood hemolysis without inhibiting the growth of planktonic P. aeruginosa cells. Moreover, 7FI markedly reduced the production of quorum-sensing (QS)-regulated virulence factors 2-heptyl-3-hydroxy-4(1H)-quinolone, pyocyanin, rhamnolipid, two siderophores, pyoverdine and pyochelin. 7FI clearly suppressed swarming motility, protease activity and the production of a polymeric matrix in P. aeruginosa. However, unlike natural indole compounds, synthetic 7FI did not increase antibiotic resistance. Therefore, 7FI is a potential candidate for use in an antivirulence approach against persistent P. aeruginosa infection.

  11. Identification, cloning, and expression of Pseudomonas aeruginosa phosphorylcholine phosphatase gene.

    PubMed

    Massimelli, María J; Beassoni, Paola R; Forrellad, Marina A; Barra, José L; Garrido, Mónica N; Domenech, Carlos E; Lisa, Angela T

    2005-05-01

    Pseudomonas aeruginosa phosphorylcholine phosphatase (PChP) is a periplasmic enzyme produced simultaneously with the hemolytic phospholipase C (PLc-H) when the bacteria are grown in the presence of choline, betaine, dimethylglycine or carnitine. Molecular analysis of the P. aeruginosa mutant JUF8-00, after Tn5-751 mutagenesis, revealed that the PA5292 gene in the P. aeruginosa PAO1 genome was responsible for the synthesis of PChP. The enzyme expressed in E. coli, rPChP-Ec, purified by a chitin-binding column (IMPACT-CN system, New England BioLabs) was homogeneous after SDS-PAGE analysis. PChP was also expressed in P. aeruginosa PAO1-LAC, rPChP-Pa. Both recombinant enzymes exhibited a molecular mass of approximately 40 kDa, as expected for the size of the PA5292 gene, and catalyzed the hydrolysis of phosphorylcholine, phosphorylethanolamine, and p-nitrophenylphosphate. The saturation curve of rPChP-Ec and rPChP-Pa by phosphorylcholine revealed that these recombinant enzymes, like the purified native PChP, also contained the high- and low-affinity sites for phosphorylcholine and that the enzyme activity was inhibited by high substrate concentration.

  12. Effects of azithromycin in Pseudomonas aeruginosa burn wound infection

    PubMed Central

    Nichols, DP; Caceres, S; Caverly, L; Fratelli, C; Kim, SH; Malcolm, KC; Poch, KR; Saavedra, M; Solomon, G; Taylor-Cousar, J; Moskowitz, SM; Nick, JA

    2013-01-01

    Background Cutaneous thermal injuries (i.e. burns) remain a common form of debilitating trauma and outcomes are often worsened by wound infection with environmental bacteria, chiefly Pseudomonas aeruginosa. Materials and Methods We tested the effects of early administration of a single dose of azithromycin, with or without subsequent anti-pseudomonal antibiotics, in a mouse model of standardized thermal injury infected with P. aeruginosa on both wound site and systemic infection. We also tested the antimicrobial effects of these antibiotics alone or combined in comparative biofilm and planktonic cultures in vitro. Results In our model, early azithromycin administration significantly reduced wound and systemic infection without altering wound site or circulating neutrophil activity. The antimicrobial effect of azithromycin was additive with ciprofloxacin but significantly reduced the antimicrobial effect of tobramycin. This pattern was reproduced in biofilm cultures and not observed in planktonic cultures of P. aeruginosa. Conclusion these data suggest that early administration of azithromycin following burn-related trauma and infection may reduce P. aeruginosa infection and potential interactions with other antibiotics should be considered when designing future studies. PMID:23478086

  13. Does Pseudomonas aeruginosa use intercellular signalling to build biofilm communities?

    PubMed

    Kirisits, Mary Jo; Parsek, Matthew R

    2006-12-01

    Pseudomonas aeruginosa is a Gram-negative bacterial species that causes several opportunistic human infections. This organism is also found in the environment, where it is renowned (like other Pseudomonads) for its ability to use a wide variety of compounds as carbon and energy sources. It is a model species for studying group-related behaviour in bacteria. Two types of group behaviour it engages in are intercellular signalling, or quorum sensing, and the formation of surface-associated communities called biofilms. Both quorum sensing and biofilm formation are important in the pathogenesis of P. aeruginosa infections. Quorum sensing regulates the expression of several secreted virulence factors and quorum sensing mutant strains are attenuated for virulence in animal models. Biofilms have been implicated in chronic infections. Two examples are the chronic lung infections afflicting people suffering from cystic fibrosis and colonization of indwelling medical devices. This review will discuss quorum sensing and biofilm formation and studies that link these two processes.

  14. Pseudomonas aeruginosa dose response and bathing water infection.

    PubMed

    Roser, D J; van den Akker, B; Boase, S; Haas, C N; Ashbolt, N J; Rice, S A

    2014-03-01

    Pseudomonas aeruginosa is the opportunistic pathogen mostly implicated in folliculitis and acute otitis externa in pools and hot tubs. Nevertheless, infection risks remain poorly quantified. This paper reviews disease aetiologies and bacterial skin colonization science to advance dose-response theory development. Three model forms are identified for predicting disease likelihood from pathogen density. Two are based on Furumoto & Mickey's exponential 'single-hit' model and predict infection likelihood and severity (lesions/m2), respectively. 'Third-generation', mechanistic, dose-response algorithm development is additionally scoped. The proposed formulation integrates dispersion, epidermal interaction, and follicle invasion. The review also details uncertainties needing consideration which pertain to water quality, outbreaks, exposure time, infection sites, biofilms, cerumen, environmental factors (e.g. skin saturation, hydrodynamics), and whether P. aeruginosa is endogenous or exogenous. The review's findings are used to propose a conceptual infection model and identify research priorities including pool dose-response modelling, epidermis ecology and infection likelihood-based hygiene management.

  15. Flagellation of Pseudomonas aeruginosa in newly divided cells

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Lee, Calvin; Anda, Jaime; Wong, Gerard

    2015-03-01

    For monotrichous bacteria, Pseudomonas aeruginosa, after cell division, one daughter cell inherits the old flagellum from its mother cell, and the other grows a new flagellum during or after cell division. It had been shown that the new flagellum grows at the distal pole of the dividing cell when the two daughter cells haven't completely separated. However, for those daughter cells who grow new flagella after division, it still remains unknown at which pole the new flagellum will grow. Here, by combining our newly developed bacteria family tree tracking techniques with genetic manipulation method, we showed that for the daughter cell who did not inherit the old flagellum, a new flagellum has about 90% chances to grow at the newly formed pole. We proposed a model for flagellation of P. aeruginosa.

  16. Transport of Aromatic Amino Acids by Pseudomonas aeruginosa

    PubMed Central

    Kay, W. W.; Gronlund, Audrey F.

    1971-01-01

    Kinetic studies of the transport of aromatic amino acids by Pseudomonas aeruginosa revealed the existence of two high-affinity transport systems which recognized the three aromatic amino acids. From competition data and studies on the exchange of preformed aromatic amino acid pools, the first transport system was found to be functional with phenylalanine, tyrosine, and tryptophan (in order of decreasing activity), whereas the second system was active with tryptophan, phenylalanine, and tyrosine. The two systems also transported a number of aromatic amino acid analogues but not other amino acids. Mutants defective in each of the two and in both transport systems were isolated and described. When the amino acids were added at low external concentrations to cells growing logarithmically in glucose minimal medium, the tryptophan pool very quickly became saturated. Under identical conditions, phenylalanine and tyrosine each accumulated in the intracellular pool of P. aeruginosa at a concentration which was 10 times greater than that of tryptophan. PMID:4994029

  17. Mass Spectrometry Analysis of Pseudomonas aeruginosa Treated With Azithromycin

    PubMed Central

    Phelan, Vanessa V.; Fang, Jinshu; Dorrestein, Pieter C.

    2015-01-01

    In microbiology, changes in specialized metabolite production (cell-to-cell signaling metabolites, virulence factors and natural products) are measured using phenotypic assays. However, advances in mass spectrometry based techniques including imaging mass spectrometry (IMS) now allow researchers to directly visualize the production of specialized metabolites from microbial colony biofilms. In this study, a combination of IMS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to visualize the effect of the macrolide antibiotic azithromycin (AZM) on colony biofilms of Pseudomonas aeruginosa. While previous research suggested that AZM may inhibit cell-to-cell signaling of P. aeruginosa and thereby reducing pathogenicity, we observed no clear decrease in specialized metabolite production. PMID:25801585

  18. Regulation of Pseudomonas aeruginosa Virulence by Distinct Iron Sources

    PubMed Central

    Reinhart, Alexandria A.; Oglesby-Sherrouse, Amanda G.

    2016-01-01

    Pseudomonas aeruginosa is a ubiquitous environmental bacterium and versatile opportunistic pathogen. Like most other organisms, P. aeruginosa requires iron for survival, yet iron rapidly reacts with oxygen and water to form stable ferric (FeIII) oxides and hydroxides, limiting its availability to living organisms. During infection, iron is also sequestered by the host innate immune system, further limiting its availability. P. aeruginosa’s capacity to cause disease in diverse host environments is due to its ability to scavenge iron from a variety of host iron sources. Work over the past two decades has further shown that different iron sources can affect the expression of distinct virulence traits. This review discusses how the individual components of P. aeruginosa’s iron regulatory network allow this opportunist to adapt to a multitude of host environments during infection. PMID:27983658

  19. Production and characterization of the slime polysaccharide of Pseudomonas aeruginosa.

    PubMed

    Evans, L R; Linker, A

    1973-11-01

    The slime polysaccharides produced by Pseudomonas aeruginosa isolated from a variety of human infections were investigated. Slime production in culture seemed optimal when adequate amounts of carbohydrate were present and under conditions of either high osmotic pressure or inadequate protein supply. The polysaccharides produced by the organisms were similar to each other, to the slime of Azotobacter vinelandii, and to seaweed alginic acids. They were composed of beta-1,4-linked d-mannuronic acid residues and variable amounts of its 5-epimer l-guluronic acid. All bacterial polymers contained o-acetyl groups which are absent in the alginates. The polysaccharides differed considerably in the ratio of mannuronic to guluronic acid content and in the number of o-acetyl groups. The particular composition of the slime was not found to be characteristic for the disease process from which the mucoid variants of P. aeruginosa were obtained.

  20. Alginate Overproduction Affects Pseudomonas aeruginosa Biofilm Structure and Function

    PubMed Central

    Hentzer, Morten; Teitzel, Gail M.; Balzer, Grant J.; Heydorn, Arne; Molin, Søren; Givskov, Michael; Parsek, Matthew R.

    2001-01-01

    During the course of chronic cystic fibrosis (CF) infections, Pseudomonas aeruginosa undergoes a conversion to a mucoid phenotype, which is characterized by overproduction of the exopolysaccharide alginate. Chronic P. aeruginosa infections involve surface-attached, highly antibiotic-resistant communities of microorganisms organized in biofilms. Although biofilm formation and the conversion to mucoidy are both important aspects of CF pathogenesis, the relationship between them is at the present unclear. In this study, we report that the overproduction of alginate affects biofilm development on an abiotic surface. Biofilms formed by an alginate-overproducing strain exhibit a highly structured architecture and are significantly more resistant to the antibiotic tobramycin than a biofilm formed by an isogenic nonmucoid strain. These results suggest that an important consequence of the conversion to mucoidy is an altered biofilm architecture that shows increasing resistance to antimicrobial treatments. PMID:11514525

  1. Mass Spectrometry Analysis of Pseudomonas aeruginosa Treated with Azithromycin

    NASA Astrophysics Data System (ADS)

    Phelan, Vanessa V.; Fang, Jinshu; Dorrestein, Pieter C.

    2015-06-01

    In microbiology, changes in specialized metabolite production (cell-to-cell signaling metabolites, virulence factors, and natural products) are measured using phenotypic assays. However, advances in mass spectrometry-based techniques including imaging mass spectrometry (IMS) now allow researchers to directly visualize the production of specialized metabolites from microbial colony biofilms. In this study, a combination of IMS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to visualize the effect of the macrolide antibiotic azithromycin (AZM) on colony biofilms of Pseudomonas aeruginosa. Although previous research suggested that AZM may inhibit cell-to-cell signaling of P. aeruginosa and thereby reduce pathogenicity, we observed no clear decrease in specialized metabolite production.

  2. [Water used for hemodialysis equipment: where is Pseudomonas aeruginosa?].

    PubMed

    Ducki, Sébastien; Francini, Nicolas; Blech, Marie-Françoise

    2005-05-01

    The water used in dilution of the dialysis solutions constitutes an essential element of the efficiency and the safety of this therapeutics. Water must be specifically treated, and some technical rules must be respected, such as disinfection of the equipment for water treatment, to guarantee a satisfying level for whole the installation. This article reports the investigations, which were led to find the spring of Pseudomonas aeruginosa which contamined in a recurring way the water feeding dialysis equipment. The observation of samples'chronology and an analysis of the sanitary pad suggested a contamination during disinfection. Sample of residual water from the pump used for the injection of Dialox identified this reservoir as origin of the contamination. To stop this contamination by P. aeruginosa, a pump maintenance revision and purges of the system were used.

  3. Airway epithelial control of Pseudomonas aeruginosa infection in cystic fibrosis

    PubMed Central

    Campόdonico, Victoria L; Gadjeva, Mihaela; Paradis-Bleau, Catherine; Uluer, Ahmet; Pier, Gerald B

    2013-01-01

    Defective expression or function of the cystic fibrosis transmembrane conductance regulator (CFTR) underlies the hypersusceptibility of cystic fibrosis (CF) patients to chronic airway infections, particularly with Pseudomonas aeruginosa. CFTR is involved in the specific recognition of P. aeruginosa, thereby contributing to effective innate immunity and proper hydration of the airway surface layer (ASL). In CF, the airway epithelium fails to initiate an appropriate innate immune response, allowing the microbe to bind to mucus plugs that are then not properly cleared because of the dehydrated ASL. Recent studies have identified numerous CFTR-dependent factors that are recruited to the epithelial plasma membrane in response to infection and that are needed for bacterial clearance, a process that is defective in CF patients hypersusceptible to infection with this organism. PMID:18262467

  4. Pseudomonas fluorescens NZI7 repels grazing by C. elegans, a natural predator.

    PubMed

    Burlinson, Peter; Studholme, David; Cambray-Young, Joanna; Heavens, Darren; Rathjen, John; Hodgkin, Jonathan; Preston, Gail M

    2013-06-01

    The bacteriovorous nematode Caenorhabditis elegans has been used to investigate many aspects of animal biology, including interactions with pathogenic bacteria. However, studies examining C. elegans interactions with bacteria isolated from environments in which it is found naturally are relatively scarce. C. elegans is frequently associated with cultivation of the edible mushroom Agaricus bisporus, and has been reported to increase the severity of bacterial blotch of mushrooms, a disease caused by bacteria from the Pseudomonas fluorescens complex. We observed that pseudomonads isolated from mushroom farms showed differential resistance to nematode predation. Under nutrient poor conditions, in which most pseudomonads were consumed, the mushroom pathogenic isolate P. fluorescens NZI7 was able to repel C. elegans without causing nematode death. A draft genome sequence of NZI7 showed it to be related to the biocontrol strain P. protegens Pf-5. To identify the genetic basis of nematode repellence in NZI7, we developed a grid-based screen for mutants that lacked the ability to repel C. elegans. The mutants isolated in this screen included strains with insertions in the global regulator GacS and in a previously undescribed GacS-regulated gene cluster, 'EDB' ('edible'). Our results suggest that the product of the EDB cluster is a poorly diffusible or cell-associated factor that acts together with other features of NZI7 to provide a novel mechanism to deter nematode grazing. As nematodes interact with NZI7 colonies before being repelled, the EDB factor may enable NZI7 to come into contact with and be disseminated by C. elegans without being subject to intensive predation.

  5. Application of Pseudomonas fluorescens to Blackberry under Field Conditions Improves Fruit Quality by Modifying Flavonoid Metabolism

    PubMed Central

    Garcia-Seco, Daniel; Zhang, Yang; Gutierrez-Mañero, Francisco J.; Martin, Cathie; Ramos-Solano, Beatriz

    2015-01-01

    Application of a plant growth promoting rhizobacterium (PGPR), Pseudomonas fluorescens N21.4, to roots of blackberries (Rubus sp.) is part of an optimised cultivation practice to improve yields and quality of fruit throughout the year in this important fruit crop. Blackberries are especially rich in flavonoids and therefore offer potential benefits for human health in prevention or amelioration of chronic diseases. However, the phenylpropanoid pathway and its regulation during ripening have not been studied in detail, in this species. PGPR may trigger flavonoid biosynthesis as part of an induced systemic response (ISR) given the important role of this pathway in plant defence, to cause increased levels of flavonoids in the fruit. We have identified structural genes encoding enzymes of the phenylpropanoid and flavonoid biosynthetic pathways catalysing the conversion of phenylalanine to the final products including flavonols, anthocyanins and catechins from blackberry, and regulatory genes likely involved in controlling the activity of pathway branches. We have also measured the major flavonols, anthocyanins and catechins at three stages during ripening. Our results demonstrate the coordinated expression of flavonoid biosynthetic genes with the accumulation of anthocyanins, catechins, and flavonols in developing fruits of blackberry. Elicitation of blackberry plants by treatment of roots with P.fluorescens N21.4, caused increased expression of some flavonoid biosynthetic genes and an accompanying increase in the concentration of selected flavonoids in fruits. Our data demonstrate the physiological mechanisms involved in the improvement of fruit quality by PGPR under field conditions, and highlight some of the genetic targets of elicitation by beneficial bacteria. PMID:26559418

  6. Physiology and behavior of Pseudomonas fluorescens single and dual strain biofilms under diverse hydrodynamics stresses.

    PubMed

    Simões, Manuel; Simões, Lúcia C; Vieira, Maria J

    2008-12-10

    Three selected Pseudomonas fluorescens strains (the type strain and two strains originally isolated from a dairy processing plant - D3-348 and D3-350) were used to form turbulent and laminar flow-generated biofilms under laboratorial conditions using flow cell reactors with stainless steel substrata. The D3-348 and D3-350 strains were also used to form dual biofilms. Biofilm phenotypic characteristics, such as respiratory activity, total and culturable cells, biomass, total and matrix proteins and polysaccharides were compared. Biofilm mechanical stability, as a major feature involved in biofilm persistence, was also assessed using a rotating device system. The results indicate that hydrodynamic conditions have a remarkable impact on biofilm phenotype. Turbulent biofilms were more active, had more mass per adhesion surface area, a higher number of total and culturable cells, a higher amount of total proteins per gram of biofilm, similar matrix proteins and identical (D3-348 and D3-350 single and dual biofilms) or smaller (type strain) total and matrix polysaccharides content than their laminar counterparts. Biofilms formed by the type strain revealed a considerable higher amount of total and culturable cells and a higher amount of total proteins (turbulent biofilms) and total and matrix polysaccharides per gram of biofilm than single and dual biofilms formed by the other strains. Mechanical stability assays disclosed that biofilms formed by both type and D3-348 strains had the highest resistance to removal when exposed to mechanical stress. Dual strain biofilms population analysis revealed an apparent co-existence, evidencing neutral interactions. The overall results provided useful information regarding a broad spectrum of P. fluorescens biofilm phenotypic parameters, which can contribute to control and model biofilm processes in food industry.

  7. Application of Pseudomonas fluorescens to Blackberry under Field Conditions Improves Fruit Quality by Modifying Flavonoid Metabolism.

    PubMed

    Garcia-Seco, Daniel; Zhang, Yang; Gutierrez-Mañero, Francisco J; Martin, Cathie; Ramos-Solano, Beatriz

    2015-01-01

    Application of a plant growth promoting rhizobacterium (PGPR), Pseudomonas fluorescens N21.4, to roots of blackberries (Rubus sp.) is part of an optimised cultivation practice to improve yields and quality of fruit throughout the year in this important fruit crop. Blackberries are especially rich in flavonoids and therefore offer potential benefits for human health in prevention or amelioration of chronic diseases. However, the phenylpropanoid pathway and its regulation during ripening have not been studied in detail, in this species. PGPR may trigger flavonoid biosynthesis as part of an induced systemic response (ISR) given the important role of this pathway in plant defence, to cause increased levels of flavonoids in the fruit. We have identified structural genes encoding enzymes of the phenylpropanoid and flavonoid biosynthetic pathways catalysing the conversion of phenylalanine to the final products including flavonols, anthocyanins and catechins from blackberry, and regulatory genes likely involved in controlling the activity of pathway branches. We have also measured the major flavonols, anthocyanins and catechins at three stages during ripening. Our results demonstrate the coordinated expression of flavonoid biosynthetic genes with the accumulation of anthocyanins, catechins, and flavonols in developing fruits of blackberry. Elicitation of blackberry plants by treatment of roots with P.fluorescens N21.4, caused increased expression of some flavonoid biosynthetic genes and an accompanying increase in the concentration of selected flavonoids in fruits. Our data demonstrate the physiological mechanisms involved in the improvement of fruit quality by PGPR under field conditions, and highlight some of the genetic targets of elicitation by beneficial bacteria.

  8. Pseudomonas fluorescens NZI7 repels grazing by C. elegans, a natural predator

    PubMed Central

    Burlinson, Peter; Studholme, David; Cambray-Young, Joanna; Heavens, Darren; Rathjen, John; Hodgkin, Jonathan; Preston, Gail M

    2013-01-01

    The bacteriovorous nematode Caenorhabditis elegans has been used to investigate many aspects of animal biology, including interactions with pathogenic bacteria. However, studies examining C. elegans interactions with bacteria isolated from environments in which it is found naturally are relatively scarce. C. elegans is frequently associated with cultivation of the edible mushroom Agaricus bisporus, and has been reported to increase the severity of bacterial blotch of mushrooms, a disease caused by bacteria from the Pseudomonas fluorescens complex. We observed that pseudomonads isolated from mushroom farms showed differential resistance to nematode predation. Under nutrient poor conditions, in which most pseudomonads were consumed, the mushroom pathogenic isolate P. fluorescens NZI7 was able to repel C. elegans without causing nematode death. A draft genome sequence of NZI7 showed it to be related to the biocontrol strain P. protegens Pf-5. To identify the genetic basis of nematode repellence in NZI7, we developed a grid-based screen for mutants that lacked the ability to repel C. elegans. The mutants isolated in this screen included strains with insertions in the global regulator GacS and in a previously undescribed GacS-regulated gene cluster, ‘EDB' (‘edible'). Our results suggest that the product of the EDB cluster is a poorly diffusible or cell-associated factor that acts together with other features of NZI7 to provide a novel mechanism to deter nematode grazing. As nematodes interact with NZI7 colonies before being repelled, the EDB factor may enable NZI7 to come into contact with and be disseminated by C. elegans without being subject to intensive predation. PMID:23426012

  9. Subunit structure of a class A aspartate transcarbamoylase from Pseudomonas fluorescens.

    PubMed Central

    Bergh, S T; Evans, D R

    1993-01-01

    The class A aspartate transcarbamoylase (ATCase, EC 2.1.3.2) from Pseudomonas fluorescens was purified to homogeneity with retention of full catalytic and regulatory functions. Careful determinations under conditions that minimized proteolysis showed that the molecule is a 1:1 stoichiometric complex of two polypeptide chains of 34 and 45 kDa. Pyridoxal phosphate is a competitive inhibitor of the enzyme (Ki = 1 microM). Reduction of the pyridoxal phosphate enzyme adduct with sodium boro[3H]hydride showed that the active site is located on the 34-kDa polypeptide. Affinity labeling with 5'-[p-(fluorosulfonyl)benzoyl]adenosine, an ATP analog, suggested that the regulatory site is also located on the 34-kDa species. While the function of the 45-kDa subunit is unknown, neither carbamoyl phosphate synthetase nor dihydroorotase activities are associated with the ATCase. The molecular mass of the enzyme was determined by gel filtration, sedimentation velocity, and electron microscopy to be 464 kDa. Thus the enzyme is composed of six copies of the 34-kDa polypeptide and six copies of the 45-kDa polypeptide. The molecule has a Stokes' ratio of 70.9 A and a frictional ratio of 1.37, suggesting a compact globular shape. We propose that the P. fluorescens ATCase is composed of two trimers of 34-kDa catalytic chains and is likely to be a D3 dodecamer with an arrangement of subunits analogous to that of the class B ATCase molecules. Images Fig. 2 Fig. 3 Fig. 5 PMID:8234318

  10. Structures and characteristics of novel siderophores from plant deleterious Pseudomonas fluorescens A225 and Pseudomonas putida ATCC 39167.

    PubMed

    Khalil-Rizvi, S; Toth, S I; van der Helm, D; Vidavsky, I; Gross, M L

    1997-04-08

    When Pseudomonas putida ATCC 39167 and plant-deleterious Pseudomonas fluorescens A225 were grown in an iron-deficient culture medium, they each produced two different novel yellow-green fluorescent pseudobactins: P39167-I, II and PA225-I, II. Pseudobactin P39167-I has a molecular formula of C46H65O23N13 and is monoanionic at neutral pH. P39167-II has the molecular formula of C46H63O22N13 and no charge at neutral pH. Pseudobactin PA225-I has a molecular formula of C46H65O24N13 and is monoanionic at neutral pH whereas pseudobactin PA225-II has the molecular formula of C46H63O23N13 and no charge at neutral pH. All four of the pseudobactins contain a dihydroxyquinoline-based chromophore. The amino acid sequence for the octapeptide in case of pseudobactins from P. putida ATCC 39167 is Chr-Ser(1)-Ala(1)-AcOHOrn-Gly-Ala(2)-OHAsp-Ser(2)-Thr. In case of pseudobactins from P. fluorescens A225, the octapeptide has the sequence Chr-Ser(1)-Ala-AcOHOrn-Gly-Ser(2)-OHAsp-Ser(3)-Thr. For all four pseudobactins (P39167-I, II and PA225-I, II), the serine(1) residue of the octapeptide is attached to the carboxylic acid group on the C-11 of the fluorescent quinoline via an amide bond. Additionally, for pseudobactin P39167-II and PA225-II, the hydroxyl group of the serine(1) residue is also attached to the carboxyl group of threonine residue at the carboxy terminus of the peptide via an ester bond, resulting in a cyclic depsipeptide in contrast to the linear peptide chain of P39167-I and PA225-I. For all four pseudobactins, a malamide group is attached to the C-3 of the quinoline derived chromophore. The three bidentate iron(III) chelating groups in all four pseudobactins consist of a 1,2-dihydroxy aromatic group of the fluorescent chromophore, a hydroxy acid group of beta-hydroxy aspartic acid, and a hydroxamate group from the acylated Ndelta-hydroxyornithine. The amino acid constituents of the pseudobactins P39167 I, II are the same as those in pseudobactin A214, whereas those in A225

  11. Role of microbial adhesion in phenanthrene biodegradation by Pseudomonas fluorescens LP6a

    NASA Astrophysics Data System (ADS)

    Abbasnezhad, Hassan

    Biodegradation of poorly water soluble hydrocarbons, such as n-alkanes and polycyclic aromatic hydrocarbons (PAHs) is often limited by the low availability of the pollutant to microbes. Adhesion of microorganisms to the oil-water interface can influence this availability. Our approach was to study a range of compounds and mechanisms to promote the adhesion of a hydrophilic PAH degrading bacterium, Pseudomonas fluorescens LP6a, to an oil-water interface and examine the effect on biodegradation of phenanthrene by the bacteria. The cationic surfactants cetylpyridinium chloride (CPC), poly-L-lysine and chlorhexidine gluconate (CHX) and the long chain alcohols 1-dodecanol, 2-dodecanol and farnesol increased the adhesion of P. fluorescens LP6a to n-hexadecane from ca. 30% to ca. 90% of suspended cells adhering. The alcohols also caused a dramatic change in the oil-water contact angle of the cell surface, increasing it from 24° to 104°, whereas the cationic compounds had little effect. In contrast, cationic compounds changed the electrophoretic mobility of the bacteria, reducing the mean zeta potential from --23 to --7 mV in 0.01M potassium phosphate buffer, but the alcohols had no effect on zeta potential. This results illustrate that alcohols acted through altering the cell surface hydrophobicity, whereas cationic surfactants changed the surface charge density. Phenanthrene was dissolved in heptamethylnonane and introduced to the aqueous growth medium, hence forming a two phase system. Introducing 1-dodecanol at concentrations of 217, 820 or 4100 mg/L resulted in comparable increases in phenanthrene biodegradation of about 30% after 120 h incubation with non-induced cultures. After 100 h of incubation with LP6a cultures induced with 2-aminobenzoate, 4.5% of the phenanthrene was mineralized by cultures versus more than 10% by the cultures containing initial 1-dodecanol or 2-dodecanol concentrations of 120 or 160 mg/L. The production and accumulation of metabolites in

  12. Pseudomonas aeruginosa exoenzyme S induces proliferation of human T lymphocytes.

    PubMed Central

    Mody, C H; Buser, D E; Syme, R M; Woods, D E

    1995-01-01

    Pseudomonas aeruginosa is a gram-negative bacterium that is responsible for devastating acute and chronic infections, which include bronchiectasis in cystic fibrosis, nosocomial pneumonia, and infection of burn wounds. Previous studies have demonstrated that these patients have impaired host responses, including cell-mediated immune responses, which are important in anti-Pseudomonas host defense. The P. aeruginosa exoproduct, exoenzyme S, has a number of characteristics which suggest that it might be important in cell-mediated immunity. To determine whether exoenzyme S activates lymphocytes to proliferate, peripheral blood mononuclear cells (PBMC) from normal volunteers were stimulated with purified exoenzyme S, and the lymphocyte response was assessed by measuring [3H]thymidine uptake and by counting the number of cells after various times in culture. Ninety-five percent of healthy adult donors had a lymphocyte response to exoenzyme S. The optimal lymphocyte response occurred on day 7, with 4 x 10(5) PBMC per microtiter well when cells were stimulated with 10 micrograms exoenzyme S per ml. [3H]thymidine uptake correlated with an increase in the number of mononuclear cells, indicating that proliferation occurred. In unseparated PBMC, T cells, and to a lesser extent B cells, proliferated. Purified T cells proliferated, while purified B cells proliferated only after the addition of irradiated T cells. Thus, T lymphocytes are necessary and sufficient for the proliferative response to exoenzyme S. We speculate that exoenzyme S from P. aeruginosa is important in T-lymphocyte-mediated host defense to P. aeruginosa. In strategies to enhance impaired cell-mediated immunity, exoenzyme S should be considered as a potential stimulant. PMID:7537248

  13. [Necrotizing fasciitis caused by pseudomonas aeruginosa (an obervation)].

    PubMed

    Abada, A; Benhmidoune, L; Tahiri, H; Essalim, K; Chakib, A; Elbelhadji, M; Rachid, R; Zaghloul, K; Amraoui, A

    2007-01-01

    Necrotizing fasciitis is an exceptional and severe form of subcutaneous gangrene which requires early diagnosis and emergency treatment. We report the case of a 24 year old woman presenting with necrotizing fasciitis after pansinusitis resistant to treatment. The germ detected was pseudomonas aeruginosa. The infection was controled with intensive care, antibiotics and surgical resection of necrotic tissues. The aim of this observation is to highlight the clinical characteristics of this disease, and to insist on the necessity to recognize the early symptoms and to start treatment as soon as possible.

  14. Phosphorylated tyrosine in the flagellum filament protein of Pseudomonas aeruginosa

    SciTech Connect

    Kelly-Wintenberg, K.; Anderson, T.; Montie, T.C. )

    1990-09-01

    Purified flagella from two strains of {sup 32}P-labeled Pseudomonas aeruginosa were shown to be phosphorylated. This was confirmed by autoradiography of flagellin protein in polyacrylamide gels. Thin-layer electrophoresis and autoradiography of flagellin partial hydrolysates indicated that phosphotyrosine was the major phosphorylated amino acid. High-pressure liquid chromatographic analysis confirmed the presence of phosphotyrosine in flagellum filament protein. Preliminary data indicated that less than one tyrosine per subunit was phosphorylated. No evidence was found for phosphorylation of serine or threonine. A function related to tyrosine phosphorylation has not been determined.

  15. Vaccines for Pseudomonas aeruginosa: A long and winding road

    PubMed Central

    Priebe, Gregory P.; Goldberg, Joanna B.

    2015-01-01

    Summary Despite the recognition of Pseudomonas aeruginosa is an opportunistic pathogen, no vaccine against this bacteria have come to market. This review describes the current state-of-the-art in vaccinology for this bacterium. This includes a discussion of those at risk for infection, the types of vaccines and the approaches for empirical and targeted antigen selection under development, as well as a perspective on where the field should go. In addition, the challenges in developing a vaccine for those individuals at risk are discussed. PMID:24575895

  16. The Approach to Pseudomonas aeruginosa in Cystic Fibrosis.

    PubMed

    Talwalkar, Jaideep S; Murray, Thomas S

    2016-03-01

    There is a high prevalence of Pseudomonas aeruginosa in patients with cystic fibrosis and clear epidemiologic links between chronic infection and morbidity and mortality exist. Prevention and early identification of infection are critical, and stand to improve with the advent of new vaccines and laboratory methods. Once the organism is identified, a variety of treatment options are available. Aggressive use of antipseudomonal antibiotics is the standard of care for acute pulmonary exacerbations in cystic fibrosis, and providers must take into account specific patient characteristics when making treatment decisions related to antibiotic selection, route and duration of administration, and site of care.

  17. Physico-chemical factors affect chloramphenicol efflux and EmhABC efflux pump expression in Pseudomonas fluorescens cLP6a.

    PubMed

    Adebusuyi, Abigail; Foght, Julia

    2013-01-01

    Protein synthesis inhibitors such as chloramphenicol and tetracycline may be inducers of efflux pumps such as MexY in Pseudomonas aeruginosa, complicating their use for the treatment of bacterial infections. We previously determined that chloramphenicol, a substrate of the EmhABC efflux pump in Pseudomonas fluorescens cLP6a, did not induce emhABC expression. In this study, we determined the effect of physico-chemical factors on chloramphenicol efflux by EmhABC, and the expression of emhABC. Efflux assays measuring accumulation of (14)C-chloramphenicol in cell pellets showed that chloramphenicol efflux is dependent on growth temperature, pH and concentration of Mg(2+). These physico-chemical factors modulated the efflux of chloramphenicol by 26 to >50%. All conditions tested that decreased the efflux of chloramphenicol unexpectedly induced transcription of emhABC efflux genes. EmhABC activity also effectively suppressed the deleterious effect of chloramphenicol on the cell membrane of strain cLP6a, which may explain why chloramphenicol is not an inducer of emhABC. Our results suggest that the detrimental effect of an antibiotic on cell membrane integrity and fatty acid composition may be the signal that induces emhABC expression, and that inducers of other bacterial efflux pumps may include environmental factors rather than their substrates per se.

  18. Zingerone silences quorum sensing and attenuates virulence of Pseudomonas aeruginosa.

    PubMed

    Kumar, Lokender; Chhibber, Sanjay; Kumar, Rajnish; Kumar, Manoj; Harjai, Kusum

    2015-04-01

    Quorum sensing in Pseudomonas aeruginosa plays an imperative role in virulence factor, biofilm formation and antimicrobial resistance. Blocking quorum sensing pathways are viewed as viable anti-virulent therapy in association with traditional antimicrobial therapy. Anti-quorum sensing dietary phytochemicals with may prove to be a safe and viable choice as anti-virulent drug candidates. Previously, our lab proved zingerone as potent anti-biofilm agent hence; further its anti-virulent and anti-quorum activities were evaluated. Zingerone, besides decreasing swimming, swarming and twitching phenotypes of P. aeruginosa PAO1, reduced biofilm forming capacity and production of virulence factors including rhamnolipid, elastase, protease, pyocyanin, cell free and cell bound hemolysin (p<0.001) indicating anti-virulent property attributing towards attenuation of virulence of P. aeruginosa. Further zingerone not only had marked effect on the production of quorum sensing signal molecules by clinical isolates of P. aeruginosa but also showed significant interference with the activation of QS reporter strains. To study the mechanism of blocking quorum sensing cascade, in silico analysis was carried out. Anti-QS activity was attributed to interference with the ligand receptor interaction of zingerone with QS receptors (TraR, LasR, RhlR and PqsR). Zingerone showed a good comparative docking score to respective autoinducer molecules which was even higher than that of vanillin, a proven anti-quorum sensing phytochemical. The results of the present study revealed the anti-quorum sensing activity of zingerone targeting ligand-receptor interaction, hence proposing zingerone as a suitable anti-virulent drug candidate against P. aeruginosa infections.

  19. Draft Genome Sequences of Pseudomonas aeruginosa Isolates from Wounded Military Personnel.

    PubMed

    Arivett, Brock A; Ream, Dave C; Fiester, Steven E; Kidane, Destaalem; Actis, Luis A

    2016-08-11

    Pseudomonas aeruginosa, a Gram-negative bacterium that causes severe hospital-acquired infections, is grouped as an ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogen because of its extensive drug resistance phenotypes and effects on human health worldwide. Five multidrug resistant P. aeruginosa strains isolated from wounded military personnel were sequenced and annotated in this work.

  20. Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis.

    PubMed

    Großkinsky, Dominik K; Tafner, Richard; Moreno, María V; Stenglein, Sebastian A; García de Salamone, Inés E; Nelson, Louise M; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

    2016-03-17

    Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience.

  1. Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis

    PubMed Central

    Großkinsky, Dominik K.; Tafner, Richard; Moreno, María V.; Stenglein, Sebastian A.; García de Salamone, Inés E.; Nelson, Louise M.; Novák, Ondřej; Strnad, Miroslav; van der Graaff, Eric; Roitsch, Thomas

    2016-01-01

    Plant beneficial microbes mediate biocontrol of diseases by interfering with pathogens or via strengthening the host. Although phytohormones, including cytokinins, are known to regulate plant development and physiology as well as plant immunity, their production by microorganisms has not been considered as a biocontrol mechanism. Here we identify the ability of Pseudomonas fluorescens G20-18 to efficiently control P. syringae infection in Arabidopsis, allowing maintenance of tissue integrity and ultimately biomass yield. Microbial cytokinin production was identified as a key determinant for this biocontrol effect on the hemibiotrophic bacterial pathogen. While cytokinin-deficient loss-of-function mutants of G20-18 exhibit impaired biocontrol, functional complementation with cytokinin biosynthetic genes restores cytokinin-mediated biocontrol, which is correlated with differential cytokinin levels in planta. Arabidopsis mutant analyses revealed the necessity of functional plant cytokinin perception and salicylic acid-dependent defence signalling for this biocontrol mechanism. These results demonstrate microbial cytokinin production as a novel microbe-based, hormone-mediated concept of biocontrol. This mechanism provides a basis to potentially develop novel, integrated plant protection strategies combining promotion of growth, a favourable physiological status and activation of fine-tuned direct defence and abiotic stress resilience. PMID:26984671

  2. Characterization of the hcnABC Gene Cluster Encoding Hydrogen Cyanide Synthase and Anaerobic Regulation by ANR in the Strictly Aerobic Biocontrol Agent Pseudomonas fluorescens CHA0

    PubMed Central

    Laville, Jacques; Blumer, Caroline; Von Schroetter, Christine; Gaia, Valeria; Défago, Geneviève; Keel, Christoph; Haas, Dieter

    1998-01-01

    The secondary metabolite hydrogen cyanide (HCN) is produced by Pseudomonas fluorescens from glycine, essentially under microaerophilic conditions. The genetic basis of HCN synthesis in P. fluorescens CHA0 was investigated. The contiguous structural genes hcnABC encoding HCN synthase were expressed from the T7 promoter in Escherichia coli, resulting in HCN production in this bacterium. Analysis of the nucleotide sequence of the hcnABC genes showed that each HCN synthase subunit was similar to known enzymes involved in hydrogen transfer, i.e., to formate dehydrogenase (for HcnA) or amino acid oxidases (for HcnB and HcnC). These similarities and the presence of flavin adenine dinucleotide- or NAD(P)-binding motifs in HcnB and HcnC suggest that HCN synthase may act as a dehydrogenase in the reaction leading from glycine to HCN and CO2. The hcnA promoter was mapped by primer extension; the −40 sequence (TTGGC … .ATCAA) resembled the consensus FNR (fumarate and nitrate reductase regulator) binding sequence (TTGAT … .ATCAA). The gene encoding the FNR-like protein ANR (anaerobic regulator) was cloned from P. fluorescens CHA0 and sequenced. ANR of strain CHA0 was most similar to ANR of P. aeruginosa and CydR of Azotobacter vinelandii. An anr mutant of P. fluorescens (CHA21) produced little HCN and was unable to express an hcnA-lacZ translational fusion, whereas in wild-type strain CHA0, microaerophilic conditions strongly favored the expression of the hcnA-lacZ fusion. Mutant CHA21 as well as an hcn deletion mutant were impaired in their capacity to suppress black root rot of tobacco, a disease caused by Thielaviopsis basicola, under gnotobiotic conditions. This effect was most pronounced in water-saturated artificial soil, where the anr mutant had lost about 30% of disease suppression ability, compared with wild-type strain CHA0. These results show that the anaerobic regulator ANR is required for cyanide synthesis in the strictly aerobic strain CHA0 and

  3. Characterization of the hcnABC gene cluster encoding hydrogen cyanide synthase and anaerobic regulation by ANR in the strictly aerobic biocontrol agent Pseudomonas fluorescens CHA0.

    PubMed

    Laville, J; Blumer, C; Von Schroetter, C; Gaia, V; Défago, G; Keel, C; Haas, D

    1998-06-01

    The secondary metabolite hydrogen cyanide (HCN) is produced by Pseudomonas fluorescens from glycine, essentially under microaerophilic conditions. The genetic basis of HCN synthesis in P. fluorescens CHA0 was investigated. The contiguous structural genes hcnABC encoding HCN synthase were expressed from the T7 promoter in Escherichia coli, resulting in HCN production in this bacterium. Analysis of the nucleotide sequence of the hcnABC genes showed that each HCN synthase subunit was similar to known enzymes involved in hydrogen transfer, i.e., to formate dehydrogenase (for HcnA) or amino acid oxidases (for HcnB and HcnC). These similarities and the presence of flavin adenine dinucleotide- or NAD(P)-binding motifs in HcnB and HcnC suggest that HCN synthase may act as a dehydrogenase in the reaction leading from glycine to HCN and CO2. The hcnA promoter was mapped by primer extension; the -40 sequence (TTGGC ... ATCAA) resembled the consensus FNR (fumarate and nitrate reductase regulator) binding sequence (TTGAT ... ATCAA). The gene encoding the FNR-like protein ANR (anaerobic regulator) was cloned from P. fluorescens CHA0 and sequenced. ANR of strain CHA0 was most similar to ANR of P. aeruginosa and CydR of Azotobacter vinelandii. An anr mutant of P. fluorescens (CHA21) produced little HCN and was unable to express an hcnA-lacZ translational fusion, whereas in wild-type strain CHA0, microaerophilic conditions strongly favored the expression of the hcnA-lacZ fusion. Mutant CHA21 as well as an hcn deletion mutant were impaired in their capacity to suppress black root rot of tobacco, a disease caused by Thielaviopsis basicola, under gnotobiotic conditions. This effect was most pronounced in water-saturated artificial soil, where the anr mutant had lost about 30% of disease suppression ability, compared with wild-type strain CHA0. These results show that the anaerobic regulator ANR is required for cyanide synthesis in the strictly aerobic strain CHA0 and suggest that ANR

  4. [Pseudomonas aeruginosa bacteriaemia: new clinical and therapeutic aspects ].

    PubMed

    Janbon, F; Despaux, E; Lepeu, G; Jonquet, O; Santoni, A; Balmayer, B; Bertrand, A

    1982-06-01

    Fifty one cases of Pseudomonas aeruginosa bacteriaemia observed during the last 12 years are reported. Thirty five patients were over fifty years old; 92 p. cent were admitted for several days and about 50 p. cent were in post-operative period. A previous antibiotherapy and an impaired status are promotive factors. The respiratory or peritoneal origins are the most frequent. All patients were feverish; 24 have had an infectious shock which was inaugural in 12 cases. Seven pneumonitis, 3 endocarditis, one pericarditis and 2 osteitis were observed. An ecthyma gangrenosum was noted in three patients. Mortality was 70 p. cent. Comparison between recovered and died patients improved bad prognosis of old age, post operative period, neoplasic, previous organica weakness and pulmonary or peritoneal origins. Used alone, colimycin has seemed to be more effective than aminosid antibiotics; but their association with betalactamins was better. An in vitro study of the susceptibility of 100 Pseudomonas aeruginosa strains has proved the interest of piperacillin and cefsulodin; azlocillin, cefoperazone and ceftriaxone are just less effective.

  5. Autolysis and autoaggregation in Pseudomonas aeruginosa colony morphology mutants.

    PubMed

    D'Argenio, David A; Calfee, M Worth; Rainey, Paul B; Pesci, Everett C

    2002-12-01

    Two distinctive colony morphologies were noted in a collection of Pseudomonas aeruginosa transposon insertion mutants. One set of mutants formed wrinkled colonies of autoaggregating cells. Suppressor analysis of a subset of these mutants showed that this was due to the action of the regulator WspR and linked this regulator (and the chemosensory pathway to which it belongs) to genes that encode a putative fimbrial adhesin required for biofilm formation. WspR homologs, related in part by a shared GGDEF domain, regulate cell surface factors, including aggregative fimbriae and exopolysaccharides, in diverse bacteria. The second set of distinctive insertion mutants formed colonies that lysed at their center. Strains with the most pronounced lysis overproduced the Pseudomonas quinolone signal (PQS), an extracellular signal that interacts with quorum sensing. Autolysis was suppressed by mutation of genes required for PQS biosynthesis, and in one suppressed mutant, autolysis was restored by addition of synthetic PQS. The mechanism of autolysis may involve activation of the endogenous prophage and phage-related pyocins in the genome of strain PAO1. The fact that PQS levels correlated with autolysis suggests a fine balance in natural populations of P. aeruginosa between survival of the many and persistence of the few.

  6. Bacteriophages for the treatment of Pseudomonas aeruginosa infections.

    PubMed

    Harper, D R; Enright, M C

    2011-07-01

    Bacteriophages were first identified in 1915 and were used as antimicrobial agents from 1919 onwards. Despite apparent successes and widespread application, early users did not understand the nature of these agents and their efficacy remained controversial. As a result, they were replaced in the west by chemical antibiotics once these became available. However, bacteriophages remained a common therapeutic approach in parts of Eastern Europe where they are still in use. Increasing levels of antibiotic-resistant bacterial infections are now driving demand for novel therapeutic approaches. In cases where antibiotic options are limited or nonexistent, the pressure for new agents is greatest. One of the most prominent areas of concern is multidrug-resistant Gram-negative bacteria. Pseudomonas aeruginosa is a prominent member of this class and is the cause of damaging infections that can be resistant to successful treatment with conventional antibiotics. At the same time, it exhibits a number of properties that make it a suitable target for bacteriophage-based approaches, including growth in biofilms that can hydrolyse following phage infection. Pseudomonas aeruginosa provides a striking example of an infection where clinical need and the availability of a practical therapy coincide.

  7. Dissecting the Machinery That Introduces Disulfide Bonds in Pseudomonas aeruginosa

    PubMed Central

    Arts, Isabelle S.; Ball, Geneviève; Leverrier, Pauline; Garvis, Steven; Nicolaes, Valérie; Vertommen, Didier; Ize, Bérengère; Tamu Dufe, Veronica; Messens, Joris; Voulhoux, Romé; Collet, Jean-François

    2013-01-01

    ABSTRACT Disulfide bond formation is required for the folding of many bacterial virulence factors. However, whereas the Escherichia coli disulfide bond-forming system is well characterized, not much is known on the pathways that oxidatively fold proteins in pathogenic bacteria. Here, we report the detailed unraveling of the pathway that introduces disulfide bonds in the periplasm of the human pathogen Pseudomonas aeruginosa. The genome of P. aeruginosa uniquely encodes two DsbA proteins (P. aeruginosa DsbA1 [PaDsbA1] and PaDsbA2) and two DsbB proteins (PaDsbB1 and PaDsbB2). We found that PaDsbA1, the primary donor of disulfide bonds to secreted proteins, is maintained oxidized in vivo by both PaDsbB1 and PaDsbB2. In vitro reconstitution of the pathway confirms that both PaDsbB1 and PaDsbB2 shuttle electrons from PaDsbA1 to membrane-bound quinones. Accordingly, deletion of both P. aeruginosa dsbB1 (PadsbB1) and PadsbB2 is required to prevent the folding of several P. aeruginosa virulence factors and to lead to a significant decrease in pathogenicity. Using a high-throughput proteomic approach, we also analyzed the impact of PadsbA1 deletion on the global periplasmic proteome of P. aeruginosa, which allowed us to identify more than 20 new potential substrates of this major oxidoreductase. Finally, we report the biochemical and structural characterization of PaDsbA2, a highly oxidizing oxidoreductase, which seems to be expressed under specific conditions. By fully dissecting the machinery that introduces disulfide bonds in P. aeruginosa, our work opens the way to the design of novel antibacterial molecules able to disarm this pathogen by preventing the proper assembly of its arsenal of virulence factors. PMID:24327342

  8. Heterogeneity of Pseudomonas aeruginosa in Brazilian Cystic Fibrosis Patients

    PubMed Central

    Silbert, Suzane; Barth, Afonso Luis; Sader, Hélio S.

    2001-01-01

    The aim of this study was to assess the diversity and genomic variability of Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients being treated at a university hospital in Brazil. Ninety-seven isolates of P. aeruginosa from 43 CF patients were characterized by macrorestriction analysis of chromosomal DNA by pulsed-field gel electrophoresis (PFGE) and tested for susceptibility to 20 antimicrobial agents by broth microdilution. It was possible to evaluate single isolates from 20 patients and multiple isolates (two to seven) from 23 patients collected during a 22-month period. Among all of the unrelated patients, we detected only one pair of patients sharing a common strain. Among the 77 isolates from 23 patients who had multiple isolates analyzed, we identified 37 major types by PFGE, and five different colonization patterns were recognized. The isolates were susceptible to several antimicrobial agents, although consecutive isolates from the same patient may display differences in their susceptibilities. Mucoid isolates were more resistant (P < 0.001) than nonmucoid isolates to five antibiotics. Our results indicate that CF patients remain colonized by more than one strain of P. aeruginosa for long periods of time. In addition, the finding of several different genotypes in the same patient suggests that the colonizing strain may occasionally be replaced. PMID:11682517

  9. Exploitation of syndecan-1 shedding by Pseudomonas aeruginosa enhances virulence.

    PubMed

    Park, P W; Pier, G B; Hinkes, M T; Bernfield, M

    2001-05-03

    Cell-surface heparan sulphate proteoglycans (HSPGs) are ubiquitous and abundant receptors/co-receptors of extracellular ligands, including many microbes. Their role in microbial infections is poorly defined, however, because no cell-surface HSPG has been clearly connected to the pathogenesis of a particular microbe. We have previously shown that Pseudomonas aeruginosa, through its virulence factor LasA, enhances the in vitro shedding of syndecan-1-the predominant cell-surface HSPG of epithelia. Here we show that shedding of syndecan-1 is also activated by P. aeruginosa in vivo, and that the resulting syndecan-1 ectodomains enhance bacterial virulence in newborn mice. Newborn mice deficient in syndecan-1 resist P. aeruginosa lung infection but become susceptible when given purified syndecan-1 ectodomains or heparin, but not when given ectodomain core protein, indicating that the ectodomain's heparan sulphate chains are the effectors. In wild-type newborn mice, inhibition of syndecan-1 shedding or inactivation of the shed ectodomain's heparan sulphate chains prevents lung infection. Our findings uncover a pathogenetic mechanism in which a host response to tissue injury-syndecan-1 shedding-is exploited to enhance microbial virulence apparently by modulating host defences.

  10. Human immune response to Pseudomonas aeruginosa mucoid exopolysaccharide (alginate) vaccine.

    PubMed Central

    Pier, G B; DesJardin, D; Grout, M; Garner, C; Bennett, S E; Pekoe, G; Fuller, S A; Thornton, M O; Harkonen, W S; Miller, H C

    1994-01-01

    Chronic lung infection with mucoid Pseudomonas aeruginosa is the major pathologic feature of cystic fibrosis. Previous studies suggested that a failure to produce opsonic antibody to the mucoid exopolysaccharide (MEP; also called alginate) capsule is associated with the maintenance of chronic bacterial infection. Provision of MEP-specific opsonic antibodies has therapeutic potential. To evaluate the ability of MEP to elicit opsonic antibodies, humans were immunized with two lots of MEP vaccine that differed principally in molecular size. Lot 2 had a larger average MEP polymer size. Both vaccines were well tolerated, but lot 1 was poorly immunogenic, inducing long-lived opsonic antibodies in only 2 of 28 vaccinates given doses of 10 to 150 micrograms. In contrast, at the optimal dose of 100 micrograms, lot 2 elicited long-lived opsonic antibodies in 80 to 90% of the vaccinates. The antibodies elicited by both lots enhanced deposition of C3 onto mucoid P. aeruginosa cells and mediated opsonic killing of heterologous mucoid strains expressing distinct MEP antigens. These results indicate that the polymers of MEP with the largest molecular sizes safely elicit opsonic antibodies in a sufficiently large proportion of vaccinates to permit studies of active and passive immunization of cystic fibrosis patients against infection with mucoid P. aeruginosa. PMID:8063415

  11. Characterization of colony morphology variants isolated from Pseudomonas aeruginosa biofilms.

    PubMed

    Kirisits, Mary Jo; Prost, Lynne; Starkey, Melissa; Parsek, Matthew R

    2005-08-01

    In this study, we report the isolation of small, rough, strongly cohesive colony morphology variants from aging Pseudomonas aeruginosa PAO1 biofilms. Similar to many of the P. aeruginosa colony morphology variants previously described in the literature, these variants autoaggregate in liquid culture and hyperadhere to solid surfaces. They also exhibit increased hydrophobicity and reduced motility compared to the wild-type parent strain. Despite the similarities in appearance of our colony morphology variant isolates on solid medium, the isolates showed a range of responses in various phenotypic assays. These variants form biofilms with significant three-dimensional structure and more biomass than the wild-type parent. To further explore the nature of the variants, their transcriptional profiles were evaluated. The variants generally showed increased expression of the psl and pel loci, which have been previously implicated in the adherence of P. aeruginosa to solid surfaces. When a mutation in the psl locus was introduced into a colony morphology variant, the colony morphology was only partially affected, but hyperadherence and autoaggregation were lost. Finally, similar colony morphology variants were found in isolates from cystic fibrosis patients. These variants displayed many of the same characteristics as the laboratory variants, suggesting a link between laboratory and cystic fibrosis biofilms.

  12. Origin and Impact of Nitric Oxide in Pseudomonas aeruginosa Biofilms

    PubMed Central

    2015-01-01

    The formation of the organized bacterial community called biofilm is a crucial event in bacterial physiology. Given that biofilms are often refractory to antibiotics and disinfectants to which planktonic bacteria are susceptible, their formation is also an industrially and medically relevant issue. Pseudomonas aeruginosa, a well-known human pathogen causing acute and chronic infections, is considered a model organism to study biofilms. A large number of environmental cues control biofilm dynamics in bacterial cells. In particular, the dispersal of individual cells from the biofilm requires metabolic and morphological reprogramming in which the second messenger bis-(3′-5′)-cyclic dimeric GMP (c-di-GMP) plays a central role. The diatomic gas nitric oxide (NO), a well-known signaling molecule in both prokaryotes and eukaryotes, is able to induce the dispersal of P. aeruginosa and other bacterial biofilms by lowering c-di-GMP levels. In this review, we summarize the current knowledge on the molecular mechanisms connecting NO sensing to the activation of c-di-GMP-specific phosphodiesterases in P. aeruginosa, ultimately leading to c-di-GMP decrease and biofilm dispersal. PMID:26260455

  13. Measuring antimicrobial susceptibility of Pseudomonas aeruginosa using Poloxamer 407 gel.

    PubMed

    Yamada, Hiroyuki; Koike, Naohito; Ehara, Tomoko; Matsumoto, Tetsuya

    2011-04-01

    Pseudomonas aeruginosa is a Gram-negative bacterium that causes various opportunistic infections. Chronic and intractable infections with P. aeruginosa are closely related to the high levels of resistance displayed by this organism to antimicrobial agents and its ability to form biofilms. Although the standard method for examining antimicrobial resistance involves susceptibility testing using Mueller-Hinton agar or broth, this method does not take into account the influence of biofilm formation on antimicrobial susceptibility. Poloxamer 407 is a hydrophilic, nonionic surfactant of the more general class of copolymers that can be used to culture bacteria with similar properties as cells in a biofilm environment. Therefore, the aim of this study was to compare the antimicrobial susceptibility of bacteria cultured in Poloxamer 407 gel to those grown on Mueller-Hinton agar using the Kirby-Bauer disk diffusion method with 24 strains of P. aeruginosa. Antimicrobial sensibility differed between the two mediums, with >60% of the strains displaying increased resistance to β-lactams when cultured on Poloxamer 407 gel. In addition, scanning electron microscopy revealed that typical biofilm formation and extracellular polymeric substance production was only observed with bacteria grown on Poloxamer 407 gel. Therefore, antimicrobial susceptibility test using Poloxamer 407 gel may provide more accurate information and allow the selection of suitable antimicrobial agents for treating patients infected with biofilm-forming pathogens.

  14. Mycofabricated biosilver nanoparticles interrupt Pseudomonas aeruginosa quorum sensing systems

    PubMed Central

    Singh, Braj R.; Singh, Brahma N.; Singh, Akanksha; Khan, Wasi; Naqvi, Alim H.; Singh, Harikesh B.

    2015-01-01

    Quorum sensing (QS) is a chemical communication process that Pseudomonas aeruginosa uses to regulate virulence and biofilm formation. Disabling of QS is an emerging approach for combating its pathogenicity. Silver nanoparticles (AgNPs) have been widely applied as antimicrobial agents against human pathogenic bacteria and fungi, but not for the attenuation of bacterial QS. Here we mycofabricated AgNPs (mfAgNPs) using metabolites of soil fungus Rhizopus arrhizus BRS-07 and tested their effect on QS-regulated virulence and biofilm formation of P. aeruginosa. Transcriptional studies demonstrated that mfAgNPs reduced the levels of LasIR-RhlIR. Treatment of mfAgNPs inhibited biofilm formation, production of several virulence factors (e.g. LasA protease, LasB elastrase, pyocyanin, pyoverdin, pyochelin, rhamnolipid, and alginate) and reduced AHLs production. Further genes quantification analyses revealed that mfAgNPs significantly down-regulated QS-regulated genes, specifically those encoded to the secretion of virulence factors. The results clearly indicated the anti-virulence property of mfAgNPs by inhibiting P. aeruginosa QS signaling. PMID:26347993

  15. In vitro antimicrobial activity of LED irradiation on Pseudomonas aeruginosa.

    PubMed

    Petrini, Morena; Trentini, Paolo; Tripodi, Domenico; Spoto, Giuseppe; D'Ercole, Simonetta

    2017-03-01

    Pseudomonas aeruginosa is an opportunistic pathogen responsible of many deaths due to nosocomial pneumonia each year. It is particularly resistant to many different classes of antibiotics and disinfectants. For all these reasons, there is the necessity to find novel approaches of treatment. The aim of this study was to evaluate the effect of 880nm light emitting diodes (LED) irradiation on P. aeruginosa, in vitro. Different LED irradiation parameters (time, energy output and the addition of methylene blue and chlorhexidine) have been tested in order to evaluate the effects on this bacterium. After treatment, the colony forming units per milliliter (CFU mL-1) were recorded and the data were submitted to ANOVA and Bonferroni post hoc tests at a level of significance of 5%. A statistical significant reduction of bacterial count has been registered after 5min of LED irradiation. The antibacterial effect was directly proportional to irradiation time and the output energy. The pre-treatment with methylene blue, seems to be not effective against P. aeruginosa, independently from irradiation parameters. On the contrary, the contemporary action of LED and chlorhexidine has shown a great reduction of bacterial count that was statistical significant respect chlorhexidine and LED alone. The effect of LED irradiation was visible also after 24h, when a lower bacterial count characterized all irradiated samples respect controls.

  16. Indole and 7‐hydroxyindole diminish Pseudomonas aeruginosa virulence

    PubMed Central

    Lee, Jintae; Attila, Can; Cirillo, Suat L. G.; Cirillo, Jeffrey D.; Wood, Thomas K.

    2009-01-01

    Summary Indole is an extracellular biofilm signal for Escherichia coli, and many bacterial oxygenases readily convert indole to various oxidized compounds including 7‐hydroxyindole (7HI). Here we investigate the impact of indole and 7HI on Pseudomonas aeruginosa PAO1 virulence and quorum sensing (QS)‐regulated phenotypes; this strain does not synthesize these compounds but degrades them rapidly. Indole and 7HI both altered extensively gene expression in a manner opposite that of acylhomoserine lactones; the most repressed genes encode the mexGHI‐opmD multidrug efflux pump and genes involved in the synthesis of QS‐regulated virulence factors including pyocyanin (phz operon), 2‐heptyl‐3‐hydroxy‐4(1H)‐quinolone (PQS) signal (pqs operon), pyochelin (pch operon) and pyoverdine (pvd operon). Corroborating these microarray results, indole and 7HI decreased production of pyocyanin, rhamnolipid, PQS and pyoverdine and enhanced antibiotic resistance. In addition, indole affected the utilization of carbon, nitrogen and phosphorus, and 7HI abolished swarming motility. Furthermore, 7HI reduced pulmonary colonization of P. aeruginosa in guinea pigs and increased clearance in lungs. Hence, indole‐related compounds have potential as a novel antivirulence approach for the recalcitrant pathogen P. aeruginosa. PMID:21261883

  17. Indole and 7-hydroxyindole diminish Pseudomonas aeruginosa virulence.

    PubMed

    Lee, Jintae; Attila, Can; Cirillo, Suat L G; Cirillo, Jeffrey D; Wood, Thomas K

    2009-01-01

    Indole is an extracellular biofilm signal for Escherichia coli, and many bacterial oxygenases readily convert indole to various oxidized compounds including 7-hydroxyindole (7HI). Here we investigate the impact of indole and 7HI on Pseudomonas aeruginosa PAO1 virulence and quorum sensing (QS)-regulated phenotypes; this strain does not synthesize these compounds but degrades them rapidly. Indole and 7HI both altered extensively gene expression in a manner opposite that of acylhomoserine lactones; the most repressed genes encode the mexGHI-opmD multidrug efflux pump and genes involved in the synthesis of QS-regulated virulence factors including pyocyanin (phz operon), 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS) signal (pqs operon), pyochelin (pch operon) and pyoverdine (pvd operon). Corroborating these microarray results, indole and 7HI decreased production of pyocyanin, rhamnolipid, PQS and pyoverdine and enhanced antibiotic resistance. In addition, indole affected the utilization of carbon, nitrogen and phosphorus, and 7HI abolished swarming motility. Furthermore, 7HI reduced pulmonary colonization of P. aeruginosa in guinea pigs and increased clearance in lungs. Hence, indole-related compounds have potential as a novel antivirulence approach for the recalcitrant pathogen P. aeruginosa.

  18. Strategies for improved rhamnolipid production by Pseudomonas aeruginosa PA1

    PubMed Central

    Pereira Jr, Nei; Freire, Denise M.G.

    2016-01-01

    Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies for increasing the production of rhamnolipid-type biosurfactants produced by Pseudomonas aeruginosa strain PA1. The influence of pH, the addition of P. aeruginosa spent culture medium and the use of a fed-batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of synthesized mono- and dirhamnolipids. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. The recycling of 20% of the spent culture medium in where P. aeruginosa was grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed-batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (2.9 g L−1–10.9 g L−1). These results offer promising pathways for the optimization of processes for the production of rhamnolipids. PMID:27257553

  19. Gallium induces the production of virulence factors in Pseudomonas aeruginosa.

    PubMed

    García-Contreras, Rodolfo; Pérez-Eretza, Berenice; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Coria-Jiménez, Rafael; Rangel-Vega, Adrián; Maeda, Toshinari; Wood, Thomas K

    2014-02-01

    The novel antimicrobial gallium is a nonredox iron III analogue with bacteriostatic and bactericidal properties, effective for the treatment of Pseudomonas aeruginosa in vitro and in vivo in mouse and rabbit infection models. It interferes with iron metabolism, transport, and presumably its homeostasis. As gallium exerts its antimicrobial effects by competing with iron, we hypothesized that it ultimately will lead cells to an iron deficiency status. As iron deficiency promotes the expression of virulence factors in vitro and promotes the pathogenicity of P. aeruginosa in animal models, it is anticipated that treatment with gallium will also promote the production of virulence factors. To test this hypothesis, the reference strain PA14 and two clinical isolates from patients with cystic fibrosis were exposed to gallium, and their production of pyocyanin, rhamnolipids, elastase, alkaline protease, alginate, pyoverdine, and biofilm was determined. Gallium treatment induced the production of all the virulence factors tested in the three strains except for pyoverdine. In addition, as the Ga-induced virulence factors are quorum sensing controlled, co-administration of Ga and the quorum quencher brominated furanone C-30 was assayed, and it was found that C-30 alleviated growth inhibition from gallium. Hence, adding both C-30 and gallium may be more effective in the treatment of P. aeruginosa infections.

  20. Mechanism of azithromycin inhibition of HSL synthesis in Pseudomonas aeruginosa

    PubMed Central

    Zeng, Jianming; Zhang, Ni; Huang, Bin; Cai, Renxin; Wu, Binning; E, Shunmei; Fang, Chengcai; Chen, Cha

    2016-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen and a leading cause of nosocomial infections. Unfortunately, P. aeruginosa has low antibiotic susceptibility due to several chromosomally encoded antibiotic resistance genes. Hence, we carried out mechanistic studies to determine how azithromycin affects quorum sensing and virulence in P. aeruginosa. lasI and rhlI single and double mutants were constructed. We then undertook a quantitative approach to determine the optimal concentration of azithromycin and culture time that can affect the expression of HSLs. Furthermore, based on the above results, the effect on quorum sensing was analyzed at a transcriptional level. It was found that 2 μg/mL azithromycin caused a 79% decrease in 3-oxo-C12-HSL secretion during cultivation, while C4-HSL secretion was strongly repressed in the early stages. Azithromycin acts on ribosomes; to determine whether this can elicit alternative modes of gene expression, transcriptional regulation of representative virulence genes was analyzed. We propose a new relationship for lasI and rhlI: lasI acts as a cell density sensor, and rhlI functions as a fine-tuning mechanism for coordination between different quorum sensing systems. PMID:27075730

  1. Quorum sensing and policing of Pseudomonas aeruginosa social cheaters.

    PubMed

    Wang, Meizhen; Schaefer, Amy L; Dandekar, Ajai A; Greenberg, E Peter

    2015-02-17

    The bacterium Pseudomonas aeruginosa is an opportunistic human pathogen that uses a quorum sensing signal cascade to activate expression of dozens of genes when sufficient population densities have been reached. Quorum sensing controls production of several key virulence factors, including secreted proteases such as elastase. Cooperating groups of bacteria growing on protein are susceptible to social cheating by quorum-sensing defective mutants. A possible way to restrict cheater emergence is by policing where cooperators produce costly goods to sanction or punish cheats. The P. aeruginosa LasR-LasI quorum sensing system controls genes including those encoding proteases and also those encoding a second quorum-sensing system, the RhlR-RhlI system, which controls numerous genes including those for cyanide production. By using RhlR quorum sensing mutants and cyanide synthesis mutants, we show that cyanide production is costly and cyanide-producing cooperators use cyanide to punish LasR-null social cheaters. Cooperators are less susceptible to cyanide than are LasR mutants. These experiments demonstrate policing in P. aeruginosa, provide a mechanistic understanding of policing, and show policing involves the cascade organization of the two quorum sensing systems in this bacterium.

  2. Strategies for improved rhamnolipid production by Pseudomonas aeruginosa PA1.

    PubMed

    Soares Dos Santos, Alexandre; Pereira, Nei; Freire, Denise M G

    2016-01-01

    Rhamnolipids are biosurfactants with potential for diversified industrial and environmental uses. The present study evaluated three strategies for increasing the production of rhamnolipid-type biosurfactants produced by Pseudomonas aeruginosa strain PA1. The influence of pH, the addition of P. aeruginosa spent culture medium and the use of a fed-batch process were examined. The culture medium adjusted to pH 7.0 was the most productive. Furthermore, the pH of the culture medium had a measurable effect on the ratio of synthesized mono- and dirhamnolipids. At pH values below 7.3, the proportion of monorhamnolipids decreased from 45 to 24%. The recycling of 20% of the spent culture medium in where P. aeruginosa was grown up to the later stationary phase was responsible for a 100% increase in rhamnolipid volumetric productivity in the new culture medium. Finally, the use of fed-batch operation under conditions of limited nitrogen resulted in a 3.8-fold increase in the amount of rhamnolipids produced (2.9 g L(-1)-10.9 g L(-1)). These results offer promising pathways for the optimization of processes for the production of rhamnolipids.

  3. Pseudomonas Aeruginosa Lectins As Targets for Novel Antibacterials

    PubMed Central

    Grishin, A. V.; Krivozubov, M. S.; Karyagina, A. S.; Gintsburg, A. L.

    2015-01-01

    Pseudomonas aeruginosa is one of the most widespread and troublesome opportunistic pathogens that is capable of colonizing various human tissues and organs and is often resistant to many currently used antibiotics. This resistance is caused by different factors, including the acquisition of specific resistance genes, intrinsic capability to diminish antibiotic penetration into the bacterial cell, and the ability to form biofilms. This situation has prompted the development of novel compounds differing in their mechanism of action from traditional antibiotics that suppress the growth of microorganisms or directly kill bacteria. Instead, these new compounds should decrease the pathogens’ ability to colonize and damage human tissues by inhibiting the virulence factors and biofilm formation. The lectins LecA and LecB that bind galactose and fucose, as well as oligo- and polysaccharides containing these sugars, are among the most thoroughly-studied targets for such novel antibacterials. In this review, we summarize the results of experiments highlighting the importance of these proteins for P. aeruginosa pathogenicity and provide information on existing lectins inhibitors and their effectiveness in various experimental models. Particular attention is paid to the effects of lectins inhibition in animal models of infection and in clinical practice. We argue that lectins inhibition is a perspective approach to combating P. aeruginosa. However, despite the existence of highly effective in vitro inhibitors, further experiments are required in order to advance these inhibitors into pre-clinical studies. PMID:26085942

  4. Proteolytic regulation of alginate overproduction in Pseudomonas aeruginosa.

    PubMed

    Damron, F Heath; Goldberg, Joanna B

    2012-05-01

    Pseudomonas aeruginosa, a Gram-negative bacterium, is a significant opportunistic pathogen associated with skin and soft tissue infections, nosocomial pneumonia and sepsis. In addition, it can chronically colonize the lungs of cystic fibrosis (CF) patients. Overproduction of the exopolysaccharide called alginate provides P. aeruginosa with a selective advantage and facilitates survival in the CF lung. The in vitro phenotype of alginate overproduction observed on solid culture media is referred to as mucoid. Expression of the alginate machinery and biosynthetic enzymes are controlled by the extracytoplasmic sigma factor, σ(22) (AlgU/T). The key negative regulator of both σ(22) activity and the mucoid phenotype is the cognate anti-sigma factor MucA. MucA sequesters σ(22) to the inner membrane inhibiting the sigma factor's transcriptional activity. The well-studied mechanism for transition to the mucoid phenotype is mutation of mucA, leading to loss of MucA function and therefore activation of σ(22) . Recently, regulated intramembrane proteolysis (RIP) has been recognized as a mechanism whereby proteolysis of the anti-sigma factor MucA leads to active σ(22) allowing P. aeruginosa to respond to environmental stress conditions by overproduction of alginate. The goal of this review is to illuminate the pathways leading to RIP that have been identified and proposed.

  5. General and condition-specific essential functions of Pseudomonas aeruginosa

    PubMed Central

    Lee, Samuel A.; Gallagher, Larry A.; Thongdee, Metawee; Staudinger, Benjamin J.; Lippman, Soyeon; Singh, Pradeep K.; Manoil, Colin

    2015-01-01

    The essential functions of a bacterial pathogen reflect the most basic processes required for its viability and growth, and represent potential therapeutic targets. Most screens for essential genes have assayed a single condition—growth in a rich undefined medium—and thus have not distinguished genes that are generally essential from those that are specific to this particular condition. To help define these classes for Pseudomonas aeruginosa, we identified genes required for growth on six different media, including a medium made from cystic fibrosis patient sputum. The analysis used the Tn-seq circle method to achieve high genome coverage and analyzed more than 1,000,000 unique insertion positions (an average of one insertion every 6.0 bp). We identified 352 general and 199 condition-specific essential genes. A subset of assignments was verified in individual strains with regulated expression alleles. The profile of essential genes revealed that, compared with Escherichia coli, P. aeruginosa is highly vulnerable to mutations disrupting central carbon-energy metabolism and reactive oxygen defenses. These vulnerabilities may arise from the stripped-down architecture of the organism’s carbohydrate utilization pathways and its reliance on respiration for energy generation. The essential function profile thus provides fundamental insights into P. aeruginosa physiology as well as identifying candidate targets for new antibacterial agents. PMID:25848053

  6. Mycofabricated biosilver nanoparticles interrupt Pseudomonas aeruginosa quorum sensing systems.

    PubMed

    Singh, Braj R; Singh, Brahma N; Singh, Akanksha; Khan, Wasi; Naqvi, Alim H; Singh, Harikesh B

    2015-09-08

    Quorum sensing (QS) is a chemical communication process that Pseudomonas aeruginosa uses to regulate virulence and biofilm formation. Disabling of QS is an emerging approach for combating its pathogenicity. Silver nanoparticles (AgNPs) have been widely applied as antimicrobial agents against human pathogenic bacteria and fungi, but not for the attenuation of bacterial QS. Here we mycofabricated AgNPs (mfAgNPs) using metabolites of soil fungus Rhizopus arrhizus BRS-07 and tested their effect on QS-regulated virulence and biofilm formation of P. aeruginosa. Transcriptional studies demonstrated that mfAgNPs reduced the levels of LasIR-RhlIR. Treatment of mfAgNPs inhibited biofilm formation, production of several virulence factors (e.g. LasA protease, LasB elastrase, pyocyanin, pyoverdin, pyochelin, rhamnolipid, and alginate) and reduced AHLs production. Further genes quantification analyses revealed that mfAgNPs significantly down-regulated QS-regulated genes, specifically those encoded to the secretion of virulence factors. The results clearly indicated the anti-virulence property of mfAgNPs by inhibiting P. aeruginosa QS signaling.

  7. Comparative study of semi-specific Aeromonas hydrophila and universal Pseudomonas fluorescens biosensors for BOD measurements in meat industry wastewaters.

    PubMed

    Raud, Merlin; Tenno, Toomas; Jõgi, Eerik; Kikas, Timo

    2012-04-05

    Aeromonas hydrophila P69.1 (A. hydrophila) was used to construct a semi-specific biosensor to estimate biochemical oxygen demand (BOD) in high fat and grease content wastewaters. A. hydrophila cells were grown in fat containing medium to induce necessary enzymes for transport and degradation of fatty substances. Universal biosensor based on non-specific Pseudomonas fluorescens P75 (P. fluorescens) was used to conduct comparison experiments. Biosensors were calibrated using OECD synthetic wastewater and steady-state method, subsequently several experiments with synthetic and industrial wastewaters were conducted. A linear range up to 45 mg l(-1) BOD(7) was gained using A. hydrophila biosensor, in comparison to 40 mg l(-1) BOD(7) obtained using P. fluorescens biosensors. The lower limit of detection was 5 mg l(-1) BOD(7). Service life of A. hydrophila and P. fluorescens biosensors were 110 and 115 days, respectively. The response time of the biosensors depended on the BOD(7) of measuring solution and was up to 20 min when analyzing different wastewaters. Both biosensors underestimated BOD in meat industry wastewater from 43% up to 71%, but more accurate results could be obtained with A. hydrophila biosensor. Semi-specific A. hydrophila biosensor was able to measure proportion of fat found in wastewater sample, while other refractory compounds remained undetectable to both biosensors.

  8. Understanding the molecular basis of plant growth promotional effect of Pseudomonas fluorescens on rice through protein profiling

    PubMed Central

    2009-01-01

    Background Plant Growth Promoting Rhizobacteria (PGPR), Pseudomonas fluorescens strain KH-1 was found to exhibit plant growth promotional activity in rice under both in-vitro and in-vivo conditions. But the mechanism underlying such promotional activity of P. fluorescens is not yet understood clearly. In this study, efforts were made to elucidate the molecular responses of rice plants to P. fluorescens treatment through protein profiling. Two-dimensional polyacrylamide gel electrophoresis strategy was adopted to identify the PGPR responsive proteins and the differentially expressed proteins were analyzed by mass spectrometry. Results Priming of P. fluorescens, 23 different proteins found to be differentially expressed in rice leaf sheaths and MS analysis revealed the differential expression of some important proteins namely putative p23 co-chaperone, Thioredoxin h- rice, Ribulose-bisphosphate carboxylase large chain precursor, Nucleotide diPhosphate kinase, Proteosome sub unit protein and putative glutathione S-transferase protein. Conclusion Functional analyses of the differential proteins were reported to be directly or indirectly involved in growth promotion in plants. Thus, this study confirms the primary role of PGPR strain KH-1 in rice plant growth promotion. PMID:20034395

  9. Effect of Human Burn Wound Exudate on Pseudomonas aeruginosa Virulence

    PubMed Central

    Gonzalez, Manuel R.; Fleuchot, Betty; Lauciello, Leonardo; Jafari, Paris; Applegate, Lee Ann; Raffoul, Wassim; Que, Yok-Ai

    2016-01-01

    ABSTRACT Burn wound sepsis is currently the main cause of morbidity and mortality after burn trauma. Infections by notorious pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii impair patient recovery and can even lead to fatality. In this study, we investigated the effect of burn wound exudates (BWEs) on the virulence of those pathogens. BWEs were collected within 7 days after burn trauma from 5 burn patients. We first monitored their effect on pathogen growth. In contrast to A. baumannii and S. aureus, P. aeruginosa was the only pathogen able to grow within these human fluids. Expression of typical virulence factors such as pyocyanin and pyoverdine was even enhanced compared the levels seen with standard laboratory medium. A detailed chemical composition analysis of BWE was performed, which enabled us to determine the major components of BWE and underline the metabolic modifications induced by burn trauma. These data are essential for the development of an artificial medium mimicking the burn wound environment and the establishment of an in vitro system to analyze the initial steps of burn wound infections. IMPORTANCE Microbial infection of severe burn wounds is currently a major medical challenge. Of the infections by bacteria able to colonize such injuries, those by Pseudomonas aeruginosa are among the most severe, causing major delays in burn patient recovery or leading to fatal issues. In this study, we investigated the growth properties of several burn wound pathogens in biological fluids secreted from human burn wounds. We found that P. aeruginosa strains were able to proliferate but not those of the other pathogens tested. In addition, burn wound exudates (BWEs) stimulate the expression of virulence factors in P. aeruginosa. The chemical composition analysis of BWEs enabled us to determine the major components of these fluids. These data are essential for the development of an artificial medium mimicking the

  10. Effect of Human Burn Wound Exudate on Pseudomonas aeruginosa Virulence.

    PubMed

    Gonzalez, Manuel R; Fleuchot, Betty; Lauciello, Leonardo; Jafari, Paris; Applegate, Lee Ann; Raffoul, Wassim; Que, Yok-Ai; Perron, Karl

    2016-01-01

    Burn wound sepsis is currently the main cause of morbidity and mortality after burn trauma. Infections by notorious pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii impair patient recovery and can even lead to fatality. In this study, we investigated the effect of burn wound exudates (BWEs) on the virulence of those pathogens. BWEs were collected within 7 days after burn trauma from 5 burn patients. We first monitored their effect on pathogen growth. In contrast to A. baumannii and S. aureus, P. aeruginosa was the only pathogen able to grow within these human fluids. Expression of typical virulence factors such as pyocyanin and pyoverdine was even enhanced compared the levels seen with standard laboratory medium. A detailed chemical composition analysis of BWE was performed, which enabled us to determine the major components of BWE and underline the metabolic modifications induced by burn trauma. These data are essential for the development of an artificial medium mimicking the burn wound environment and the establishment of an in vitro system to analyze the initial steps of burn wound infections. IMPORTANCE Microbial infection of severe burn wounds is currently a major medical challenge. Of the infections by bacteria able to colonize such injuries, those by Pseudomonas aeruginosa are among the most severe, causing major delays in burn patient recovery or leading to fatal issues. In this study, we investigated the growth properties of several burn wound pathogens in biological fluids secreted from human burn wounds. We found that P. aeruginosa strains were able to proliferate but not those of the other pathogens tested. In addition, burn wound exudates (BWEs) stimulate the expression of virulence factors in P. aeruginosa. The chemical composition analysis of BWEs enabled us to determine the major components of these fluids. These data are essential for the development of an artificial medium mimicking the burn wound

  11. A comparison of enumeration methods for culturable Pseudomonas fluorescens cells marked with green fluorescent protein.

    PubMed

    Cassidy, M B; Leung, K T; Lee, H; Trevors, J T

    2000-04-01

    The detection of bacteria in environmental samples using genetic markers is valuable in microbial ecology. The green fluorescent protein (GFP) reporter gene was studied under nutrient starvation conditions at 4 degrees C, 23 degrees C and 30 degrees C in Pseudomonas fluorescens R2fG1 cells tagged with a red-shifted gfp. Fluorescence intensity was not significantly different in cells maintained in a buffer for at least 48 days at all the tested temperatures. gfp-Tagged R2fG1 cells were introduced into bulk soil microcosms and soil microcosms with wheat seedlings. GFP-marked cells were enumerated immediately after inoculation into soil and again in soil and root samples after 10 days. Counts of culturable colonies were obtained from drop plates using 5-microl aliquots of serial dilutions viewed with an epifluorescent microscope. Traditional spread plates (using 100-microl aliquots) and the most-probable-number (MPN) method using a spectrofluorometer were also used to enumerate the GFP-marked Pseudomonas cells in soil, rhizosphere and rhizoplane samples. Microcolonies were visualized on root surfaces under the epifluorescent microscope after immobilizing in agar and incubation for 24 h. Counts from traditional spread plates were significantly higher (P<0.05) than the population estimates of the MPN method for all treatments at any sampling time. Counts using the drop plate method, however, were not significantly different (P<0.05) except in one treatment, and provided similar estimates in half the time of spread plates and at an estimated third of the cost.

  12. Biochemical, Genetic, and Zoosporicidal Properties of Cyclic Lipopeptide Surfactants Produced by Pseudomonas fluorescens

    PubMed Central

    de Souza, Jorge T.; de Boer, Marjan; de Waard, Pieter; van Beek, Teris A.; Raaijmakers, Jos M.

    2003-01-01

    Zoospores play an important role in the infection of plant and animal hosts by oomycetes and other zoosporic fungi. In this study, six fluorescent Pseudomonas isolates with zoosporicidal activities were obtained from the wheat rhizosphere. Zoospores of multiple oomycetes, including Pythium species, Albugo candida, and Phytophthora infestans, were rendered immotile within 30 s of exposure to cell suspensions or cell culture supernatants of the six isolates, and subsequent lysis occurred within 60 s. The representative strain SS101, identified as Pseudomonas fluorescens biovar II, reduced the surface tension of water from 73 to 30 mN m−1. The application of cell suspensions of strain SS101 to soil or hyacinth bulbs provided significant protection against root rot caused by Pythium intermedium. Five Tn5 mutants of strain SS101lacked the abilities to reduce the surface tension of water and to cause lysis of zoospores. Genetic characterization of two surfactant-deficient mutants showed that the transposons had integrated into condensation domains of peptide synthetases. A partially purified extract from strain SS101 reduced the surface tension of water to 30 mN m−1 and reached the critical micelle concentration at 25 μg ml−1. Reverse-phase high-performance liquid chromatography yielded eight different fractions, five of which had surface activity and caused lysis of zoospores. Mass spectrometry and nuclear magnetic resonance analyses allowed the identification of the main constituent as a cyclic lipopeptide (1,139 Da) containing nine amino acids and a 10-carbon hydroxy fatty acid. The other four zoosporicidal fractions were closely related to the main constituent, with molecular massesranging from 1,111 to 1,169 Da. PMID:14660362

  13. Biochemical, genetic, and zoosporicidal properties of cyclic lipopeptide surfactants produced by Pseudomonas fluorescens.

    PubMed

    De Souza, Jorge T; De Boer, Marjan; De Waard, Pieter; Van Beek, Teris A; Raaijmakers, Jos M

    2003-12-01

    Zoospores play an important role in the infection of plant and animal hosts by oomycetes and other zoosporic fungi. In this study, six fluorescent Pseudomonas isolates with zoosporicidal activities were obtained from the wheat rhizosphere. Zoospores of multiple oomycetes, including Pythium species, Albugo candida, and Phytophthora infestans, were rendered immotile within 30 s of exposure to cell suspensions or cell culture supernatants of the six isolates, and subsequent lysis occurred within 60 s. The representative strain SS101, identified as Pseudomonas fluorescens biovar II, reduced the surface tension of water from 73 to 30 mN m-1. The application of cell suspensions of strain SS101 to soil or hyacinth bulbs provided significant protection against root rot caused by Pythium intermedium. Five Tn5 mutants of strain SS101lacked the abilities to reduce the surface tension of water and to cause lysis of zoospores. Genetic characterization of two surfactant-deficient mutants showed that the transposons had integrated into condensation domains of peptide synthetases. A partially purified extract from strain SS101 reduced the surface tension of water to 30 mN m-1 and reached the critical micelle concentration at 25 micrograms ml-1. Reverse-phase high-performance liquid chromatography yielded eight different fractions, five of which had surface activity and caused lysis of zoospores. Mass spectrometry and nuclear magnetic resonance analyses allowed the identification of the main constituent as a cyclic lipopeptide (1,139 Da) containing nine amino acids and a 10-carbon hydroxy fatty acid. The other four zoosporicidal fractions were closely related to the main constituent, with molecular massesranging from 1,111 to 1,169 Da.

  14. Modeling high-intensity pulsed electric field inactivation of a lipase from Pseudomonas fluorescens.

    PubMed

    Soliva-Fortuny, R; Bendicho-Porta, S; Martín-Belloso, O

    2006-11-01

    The inactivation kinetics of a lipase from Pseudomonas fluorescens (EC 3.1.1.3.) were studied in a simulated skim milk ultrafiltrate treated with high-intensity pulsed electric fields. Samples were subjected to electric field intensities ranging from 16.4 to 27.4 kV/cm for up to 314.5 micros, thus achieving a maximum inactivation of 62.1%. The suitability of describing experimental data using mechanistic first-order kinetics and an empirical model based on the Weibull distribution function is discussed. In addition, different mathematical expressions relating the residual activity values to field strength and treatment time are supplied. A first-order fractional conversion model predicted residual activity with good accuracy (A(f) = 1.018). A mechanistic insight of the model kinetics was that experimental values were the consequence of different structural organizations of the enzyme, with uneven resistance to the pulsed electric field treatments. The Weibull model was also useful in predicting the energy density necessary to achieve lipase inactivation.

  15. Benzaldehyde lyase, a novel thiamine PPi-requiring enzyme, from Pseudomonas fluorescens biovar I.

    PubMed Central

    González, B; Vicuña, R

    1989-01-01

    Pseudomonas fluorescens biovar I can grow on benzoin as the sole carbon and energy source. This ability is due to benzaldehyde lyase, a new type of enzyme that irreversibly cleaves the acyloin linkage of benzoin, producing two molecules of benzaldehyde. Benzaldehyde lyase was purified 70-fold and found to require catalytic amounts of thiamine PPi (TPP) and a divalent cation as cofactors. Optimal activity was obtained with a 1.0 mM concentration of Mn2+, Mg2+, or Ca2+. Gel permeation chromatography indicated a native molecular weight of 80,000, whereas the enzyme migrated in sodium dodecyl sulfate-containing polyacrylamide gels as a single polypeptide with a molecular weight of 53,000. Benzaldehyde lyase is highly specific; of a variety of structurally related compounds tested, only benzoin and anisoin (4,4'-dimethoxybenzoin) acted as substrates, their apparent Kms being 9.0 x 10(-3) and 3.25 x 10(-2) mM, respectively. A catalytic mechanism for the enzyme is proposed. Images PMID:2496105

  16. Enzymes involved in vinyl acetate decomposition by Pseudomonas fluorescens PCM 2123 strain.

    PubMed

    Szczyrba, Elżbieta; Greń, Izabela; Bartelmus, Grażyna

    2014-03-01

    Esterases are widely used in food processing industry, but there is little information concerning enzymes involved in decompositions of esters contributing to pollution of environment. Vinyl acetate (an ester of vinyl alcohol and acetic acid) is a representative of volatile organic compounds (VOCs) in decomposition, of which hydrolyses and oxidoreductases are mainly involved. Their activities under periodically changing conditions of environment are essential for the removal of dangerous VOCs. Esterase and alcohol/aldehyde dehydrogenase activities were determined in crude cell extract from Pseudomonas fluorescens PMC 2123 after vinyl acetate induction. All examined enzymes exhibit their highest activity at 30-35 °C and pH 7.0-7.5. Esterase preferably hydrolyzed ester bonds with short fatty chains without plain differences for C2 or C4. Comparison of Km values for alcohol and aldehyde dehydrogenases for acetaldehyde suggested that this metabolite was preferentially oxidized than reduced. Activity of alcohol dehydrogenase reducing acetaldehyde to ethanol suggested that one mechanism of defense against the elevated concentration of toxic acetaldehyde could be its temporary reduction to ethanol. Esterase activity was inhibited by phenylmethanesulfonyl fluoride, while β-mercaptoethanol, dithiothreitol, and ethylenediaminetetraacetic acid had no inhibitor effect. From among metal ions, only Mg(2+) and Fe(2+) stimulated the cleavage of ester bond.

  17. Milk-deteriorating exoenzymes from Pseudomonas fluorescens 041 isolated from refrigerated raw milk

    PubMed Central

    Martins, Maurilio L.; Pinto, Uelinton M.; Riedel, Katharina; Vanetti, Maria C.D.

    2015-01-01

    The practice of refrigerating raw milk at the farm has provided a selective advantage for psychrotrophic bacteria that produce heat-stable proteases and lipases causing severe quality problems to the dairy industry. In this work, a protease (AprX) and a lipase (LipM) produced by Pseudomonas fluorescens 041, a highly proteolytic and lipolytic strain isolated from raw milk obtained from a Brazilian farm, have been purified and characterized. Both enzymes were purified as recombinant proteins from Escherichia coli . The AprX metalloprotease exhibited activity in a broad temperature range, including refrigeration, with a maximum activity at 37 °C. It was active in a pH range of 4.0 to 9.0. This protease had maximum activity with the substrates casein and gelatin in the presence of Ca +2 . The LipM lipase had a maximum activity at 25 °C and a broad pH optimum ranging from 7.0 to 10. It exhibited the highest activity, in the presence of Ca +2 , on substrates with long-chain fatty acid residues. These results confirm the spoilage potential of strain 041 in milk due to, at least in part, these two enzymes. The work highlights the importance of studies of this kind with strains isolated in Brazil, which has a recent history on the implementation of the cold chain at the dairy farm. PMID:26221110

  18. Metabolic networks to generate pyruvate, PEP and ATP from glycerol in Pseudomonas fluorescens.

    PubMed

    Alhasawi, Azhar; Thomas, Sean C; Appanna, Vasu D

    2016-04-01

    Glycerol is a major by-product of the biodiesel industry. In this study we report on the metabolic networks involved in its transformation into pyruvate, phosphoenolpyruvate (PEP) and ATP. When the nutritionally-versatile Pseudomonas fluorescens was exposed to hydrogen peroxide (H2O2) in a mineral medium with glycerol as the sole carbon source, the microbe reconfigured its metabolism to generate adenosine triphosphate (ATP) primarily via substrate-level phosphorylation (SLP). This alternative ATP-producing stratagem resulted in the synthesis of copious amounts of PEP and pyruvate. The production of these metabolites was mediated via the enhanced activities of such enzymes as pyruvate carboxylase (PC) and phosphoenolpyruvate carboxylase (PEPC). The high energy PEP was subsequently converted into ATP with the aid of pyruvate phosphate dikinase (PPDK), phosphoenolpyruvate synthase (PEPS) and pyruvate kinase (PK) with the concomitant formation of pyruvate. The participation of the phospho-transfer enzymes like adenylate kinase (AK) and acetate kinase (ACK) ensured the efficiency of this O2-independent energy-generating machinery. The increased activity of glycerol dehydrogenase (GDH) in the stressed bacteria provided the necessary precursors to fuel this process. This H2O2-induced anaerobic life-style fortuitously evokes metabolic networks to an effective pathway that can be harnessed into the synthesis of ATP, PEP and pyruvate. The bioconversion of glycerol to pyruvate will offer interesting economic benefit.

  19. Thermal deactivation kinetics of Pseudomonas fluorescens lipase entrapped in AOT/isooctane reverse micelles.

    PubMed

    Park, Kyung Min; Kwon, Chang Woo; Choi, Seung Jun; Son, Young-Hwan; Lim, Seokwon; Yoo, Yoonjung; Chang, Pahn-Shick

    2013-10-02

    Thermostability of the lipase (EC 3.1.1.3) was found to be increased by the enzyme-entrapment in 50 mM AOT/isooctane reverse micelles. The half-life (15.75 h) of Pseudomonas fluorescens lipase entrapped in reverse micelles at 70 °C was 9.72- and 11.41-fold longer than those solubilized in a glycerol pool or in 10 mM phosphate buffer (pH 8.0), respectively. The enzyme deactivation model considering a two-step series-type was employed, and deactivation constants for the second step (k₂) at all temperatures were drastically decreased after the lipase was entrapped in reverse micelles. In particular, k₂ (0.0354 h⁻¹) at 70 °C in reverse micelles was 12.33- and 13.14-fold lower than in a glycerol pool or in the phosphate buffer, respectively. The deactivation energies (from k₁, k₂) for the lipase entrapped in the reverse micelles, solubilized in a glycerol pool, or in the aqueous buffer were 7.51, 26.35 kcal/mol, 5.93, 21.08 kcal/mol, and 5.53, 17.57 kcal/mol, respectively.

  20. Immobilization of Pseudomonas fluorescens lipase onto magnetic nanoparticles for resolution of 2-octanol.

    PubMed

    Xun, Er-na; Lv, Xiao-li; Kang, Wei; Wang, Jia-xin; Zhang, Hong; Wang, Lei; Wang, Zhi

    2012-10-01

    The lipase from Pseudomonas fluorescens (Lipase AK, AKL) was immobilized onto the magnetic Fe(3)O(4) nanoparticles via hydrophobic interaction. Enzyme loading and immobilization yield were determined as 21.4±0.5 mg/g and 49.2±1.8 %, respectively. The immobilized AKL was successfully used for resolution of 2-octanol with vinyl acetate used as acyl donor. Effects of organic solvent, water activity, substrate ratio, and temperature were investigated. Under the optimum conditions, the preferred isomer for AKL is the (R)-2-octanol and the highest enantioselectivity (E=71.5±2.2) was obtained with a higher enzyme activity (0.197±0.01 μmol/mg/min). The results also showed that the immobilized lipase could be easily separated from reaction media by the magnetic steel and remained 89 % of its initial activity as well as the nearly unchanged enantioselectivity after five consecutive cycles, indicating a high stability in practical operation.

  1. Fate of uranyl in a quaternary system composed of uranyl, citrate, goethite, and Pseudomonas fluorescens.

    PubMed

    Bencheikh-Latmani, Rizlan; Leckie, James O; Bargar, John R

    2003-08-15

    This study investigated the partitioning of uranyl within a quaternary system made up of uranyl, citrate, goethite, and the bacterium Pseudomonas fluorescens. In the absence of cells, uranyl was sorbed to goethite as a complex involving surface groups and/or citrate. Measurements of the evolution of CO2 indicated that the addition of bacterial cells lead to the gradual biodegradation of citrate. Throughout the biodegradation process, uranyl remained sorbed to the insoluble fraction comprised of goethite and cells. EXAFS (Extended X-ray Absorption Fine Structure) measurements showed that bacterial cells outcompeted goethite for uranyl under the experimental conditions and caused the repartitioning of uranyl from goethite to cell matter, independently from citrate degradation. Citrate degradation caused further release of uranyl from goethite surfaces, followed by subsequent association of uranyl with cells. At long equilibration times (3 months), cell lysis and phosphate release resulted in the precipitation of an autunite-like phase. This work suggests that bacterial degradation of uranyl-complexing ligands in contaminated subsurface media containing iron oxides should not necessarily lead to an increase in the mobility of uranyl.

  2. Detection and analysis of chromosomal arsenic resistance in Pseudomonas fluorescens strain MSP3.

    PubMed

    Prithivirajsingh, S; Mishra, S K; Mahadevan, A

    2001-02-09

    Pseudomonas fluorescens MSP3 isolated from sea water was resistant to arsenate. This bacterium harbored no plasmids, indicating that arsenic resistance was chromosomally encoded. The chromosomal DNA from MSP3 when transformed onto Escherichia coli DH5alpha using pBluescript exhibited resistance to sodium arsenate and sodium arsenite. Three clones MSA1, MSA2, and MSI3 containing the ars genes were obtained and further subcloning resulted in three fragments of size 2.2, 2.6, and 2.1 kb for pMSA11, pMSA12, and pMSI13, respectively, which contained the genes arsRBC of the arsenic operon. An efflux mechanism of detoxification was observed which was ATP dependent. The resistance mechanism was encoded from a single operon which consisted of an arsenite inducible repressor that regulates the expression of arsenate reductase (ars C) and inner membrane associated arsenite export system encoded by ars B. The chromosomal operon was cloned, sequenced, and found to consist of three cistrons, named as ars R, ars B, and ars C. Southern hybridization and mating experiments confirmed the functioning of the ars genes in the operon, thereby conferring increased resistance to sodium arsenate and sodium arsenite.

  3. Promotion of plant growth by Pseudomonas fluorescens strain SS101 via novel volatile organic compounds.

    PubMed

    Park, Yong-Soon; Dutta, Swarnalee; Ann, Mina; Raaijmakers, Jos M; Park, Kyungseok

    2015-05-29

    Volatile organic compounds (VOCs) from plant growth-promoting rhizobacteria (PGPR) play key roles in modulating plant growth and induced systemic resistance (ISR) to pathogens. Despite their significance, the physiological functions of the specific VOCs produced by Pseudomonas fluorescens SS101 (Pf.SS101) have not been precisely elucidated. The effects of Pf.SS101 and its VOCs on augmentation of plant growth promotion were investigated in vitro and in planta. A significant growth promotion was observed in plants exposed Pf.SS101 under both conditions, suggesting that its VOCs play a key role in promoting plant growth. Solid-phase micro-extraction (SPME) and a gas chromatography-mass spectrophotometer (GC-MS) system were used to characterize the VOCs emitted by Pf.SS101 and 11 different compounds were detected in samples inoculated this bacterium, including 13-Tetradecadien-1-ol, 2-butanone and 2-Methyl-n-1-tridecene. Application of these compounds resulted in enhanced plant growth. This study suggests that Pf.SS101 promotes the growth of plants via the release of VOCs including 13-Tetradecadien-1-ol, 2-butanone and 2-Methyl-n-1-tridecene, thus increasing understanding of the role of VOCs in plant-bacterial inter-communication.

  4. Use of an ultraviolet light at point-of-dispense faucet to eliminate Pseudomonas aeruginosa.

    PubMed

    Gerba, Charles P

    2015-05-01

    Tap water is believed to be a significant source of Pseudomonas aeruginosa in health care environments. This study evaluated an ultraviolet (UV) light point-of-dispense water treatment system for control of P aeruginosa. No P aeruginosa was detected in 30 different water dispensers in which the UV light device had been operating for 1-34 months. In comparison, P aeruginosa was found in other taps that did not feature this UV light system.

  5. Functionalized polyanilines disrupt Pseudomonas aeruginosa and Staphylococcus aureus biofilms.

    PubMed

    Gizdavic-Nikolaidis, Marija R; Pagnon, Joanne C; Ali, Naseem; Sum, Reuben; Davies, Noel; Roddam, Louise F; Ambrose, Mark

    2015-12-01

    The purpose of the present study was to investigate the antimicrobial effects of functionalized polyanilines (fPANIs) against stationary phase cells and biofilms of Pseudomonas aeruginosa and Staphylococcus aureus using homopolymer of sulfanilic acid (poly-SO3H) as a model. The chemically synthesized poly-SO3H was characterized using Fourier Transform Infra-Red (FTIR) and Ultraviolet-Visible (UV-Vis) spectroscopies. The molecular weight (Mw) and elemental analysis of homopolymer poly-SO3H were also examined. We found that poly-SO3H was bactericidal against stationary phase cells of P. aeruginosa and S. aureus at a concentration of 20 mgml(-1). Surprisingly, we discovered that the same concentration (20 mgml(-1)) of poly-SO3H significantly disrupted and killed bacterial cells present in pre-established forty-eight hour static biofilms of these organisms, as shown by crystal violet and bacterial live/dead fluorescence staining assays. In support of these data, poly-SO3H extensively diminished the expression of bacterial genes related to biofilm formation in stationary phase cells of P. aeruginosa, and seemed to greatly reduce the amount of the quorum sensing molecule N-(3-oxododecanoyl)-l-homoserine lactone (3OC12-HSL) able to be recovered from biofilms of this organism. Furthermore, we found that poly-SO3H was able to effectively penetrate and kill cells in biofilms formed by the P. aeruginosa (AESIII) isolate derived from the sputum of a cystic fibrosis patient. Taken together, the results of the present study emphasise the broad antimicrobial activities of fPANI, and suggest that they could be developed further and used in some novel ways to construct medical devices and/or industrial equipment that are refractory to colonization by biofilm-forming bacteria.

  6. Enterobactin-mediated iron transport in Pseudomonas aeruginosa.

    PubMed Central

    Poole, K; Young, L; Neshat, S

    1990-01-01

    A pyoverdine-deficient strain of Pseudomonas aeruginosa was unable to grow in an iron-deficient minimal medium in the presence of the nonmetabolizable iron chelator ethylene diamine-di(omega-hydroxyphenol acetic acid) (EDDHA), although addition of enterobactin to EDDHA-containing minimal media did restore growth of the pyoverdine-deficient P. aeruginosa. Consistent with the apparent ability of enterobactin to provide iron to P. aeruginosa, enterobactin-dependent 55Fe3+ uptake was observed in cells of P. aeruginosa previously grown in an iron-deficient medium containing enterobactin (or enterobactin-containing Escherichia coli culture supernatant). This uptake was energy dependent, was observable at low concentrations (60 nM) of FeCl3, and was absent in cells cultured without enterobactin. A novel protein with a molecular weight of approximately 80,000 was identified in the outer membranes of cells grown in iron-deficient minimal medium containing enterobactin, concomitant with the induction of enterobactin-dependent iron uptake. A Tn501 insertion mutant lacking this protein was isolated and shown to be deficient in enterobactin-mediated iron transport at 60 nM FeCl3, although it still exhibited enterobactin-dependent growth in iron-deficient medium containing EDDHA. It was subsequently observed that the mutant was, however, capable of enterobactin-mediated iron transport at much higher concentrations (600 nM) of FeCl3. Indeed, enterobactin-dependent iron uptake at this concentration of iron was observed in both the mutant and parent strains irrespective of whether they had been cultured in the presence of enterobactin.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:2174865

  7. Genetics of O-Antigen Biosynthesis in Pseudomonas aeruginosa

    PubMed Central

    Rocchetta, H. L.; Burrows, L. L.; Lam, J. S.

    1999-01-01

    Pathogenic bacteria produce an elaborate assortment of extracellular and cell-associated bacterial products that enable colonization and establishment of infection within a host. Lipopolysaccharide (LPS) molecules are cell surface factors that are typically known for their protective role against serum-mediated lysis and their endotoxic properties. The most heterogeneous portion of LPS is the O antigen or O polysaccharide, and it is this region which confers serum resistance to the organism. Pseudomonas aeruginosa is capable of concomitantly synthesizing two types of LPS referred to as A band and B band. The A-band LPS contains a conserved O polysaccharide region composed of d-rhamnose (homopolymer), while the B-band O-antigen (heteropolymer) structure varies among the 20 O serotypes of P. aeruginosa. The genes coding for the enzymes that direct the synthesis of these two O antigens are organized into two separate clusters situated at different chromosomal locations. In this review, we summarize the organization of these two gene clusters to discuss how A-band and B-band O antigens are synthesized and assembled by dedicated enzymes. Examples of unique proteins required for both A-band and B-band O-antigen synthesis and for the synthesis of both LPS and alginate are discussed. The recent identification of additional genes within the P. aeruginosa genome that are homologous to those in the A-band and B-band gene clusters are intriguing since some are able to influence O-antigen synthesis. These studies demonstrate that P. aeruginosa represents a unique model system, allowing studies of heteropolymeric and homopolymeric O-antigen synthesis, as well as permitting an examination of the interrelationship of the synthesis of LPS molecules and other virulence determinants. PMID:10477307

  8. Toxicogenomic response of Pseudomonas aeruginosa to ortho-phenylphenol

    PubMed Central

    Nde, Chantal W; Jang, Hyeung-Jin; Toghrol, Freshteh; Bentley, William E

    2008-01-01

    Background Pseudomonas aeruginosa (P. aeruginosa) is the most common opportunistic pathogen implicated in nosocomial infections and in chronic lung infections in cystic fibrosis patients. Ortho-phenylphenol (OPP) is an antimicrobial agent used as an active ingredient in several EPA registered disinfectants. Despite its widespread use, there is a paucity of information on its target molecular pathways and the cellular responses that it elucidates in bacteria in general and in P. aeruginosa in particular. An understanding of the OPP-driven gene regulation and cellular response it elicits will facilitate more effective utilization of this antimicrobial and possibly lead to the development of more effective disinfectant treatments. Results Herein, we performed a genome-wide transcriptome analysis of the cellular responses of P. aeruginosa exposed to 0.82 mM OPP for 20 and 60 minutes. Our data indicated that OPP upregulated the transcription of genes encoding ribosomal, virulence and membrane transport proteins after both treatment times. After 20 minutes of exposure to 0.82 mM OPP, genes involved in the exhibition of swarming motility and anaerobic respiration were upregulated. After 60 minutes of OPP treatment, the transcription of genes involved in amino acid and lipopolysaccharide biosynthesis were upregulated. Further, the transcription of the ribosome modulation factor (rmf) and an alternative sigma factor (rpoS) of RNA polymerase were downregulated after both treatment times. Conclusion Results from this study indicate that after 20 minutes of exposure to OPP, genes that have been linked to the exhibition of anaerobic respiration and swarming motility were upregulated. This study also suggests that the downregulation of the rmf and rpoS genes may be indicative of the mechanism by which OPP causes decreases in cell viability in P. aeruginosa. Consequently, a protective response involving the upregulation of translation leading to the increased synthesis of

  9. Prediction of growth of Pseudomonas fluorescens in milk during storage under fluctuating temperature.

    PubMed

    Lin, Hao; Shavezipur, Mohammad; Yousef, Ahmed; Maleky, Farnaz

    2016-03-01

    Accurate prediction of growth of undesirable organisms (e.g., Pseudomonas fluorescens) in perishable foods (e.g., milk), held under sub-ideal storage conditions, can help ensure the quality and safety of these foods at the point of consumption. In this investigation, we inoculated sterile milk with P. fluorescens (~10(3) cfu/mL) and monitored inoculum growth behavior at constant and fluctuating storage temperatures. Three storage temperatures, 4 °C, 15 °C and 29 °C, were selected to simulate proper refrigeration conditions (4 °C) and temperature abuse, respectively. To simulate temperature fluctuation, milk held at 4 °C was subjected to temperature shifts to 15 °C or 29 °C for 4 to 6h. A modified logistic model was used to obtain the best-fit curve for the microbial growth under constant storage temperature. The specific growth rates at 4 °C, 15 °C, and 29 °C, obtained from experimental data, were 0.056 ± 0.00, 0.17 ± 0.05, and 0.46 ± 0.02 h(-1), respectively, and the lag time values were 29.5 ± 4.2, 12.7 ± 4.4, and 2.8 ± 0.3h, respectively. A model predicting bacterial growth under different temperature fluctuations was obtained using the growth parameters extracted from constant temperature experiments. Growth behavior predicted by the fluctuating temperature model and that obtained experimentally were in good agreement. Lag time exhibited a larger variation compared with specific growth rate, suggesting that it depends not only on growth temperature but also on the sample population and temperature gradient. Additionally, experimental data showed that changing the temperature during the lag phase induced an additional lag time before growth; however, no significant lag time was observed under the temperature fluctuation during the exponential phase. The results of this study provide information for precise shelf-life determination and reduction of food waste, particularly for milk and milk-containing food products.

  10. Genetic characterization of psp encoding the DING protein in Pseudomonas fluorescens SBW25

    PubMed Central

    Zhang, Xue-Xian; Scott, Ken; Meffin, Rebecca; Rainey, Paul B

    2007-01-01

    Background DING proteins constitute a conserved and broadly distributed set of proteins found in bacteria, fungi, plants and animals (including humans). Characterization of DING proteins from animal and plant tissues indicated ligand-binding ability suggesting a role for DING proteins in cell signaling and biomineralization. Surprisingly, the genes encoding DING proteins in eukaryotes have not been identified in the eukaryotic genome or EST databases. Recent discovery of a DING homologue (named Psp here) in the genome of Pseudomonas fluorescens SBW25 provided a unique opportunity to investigate the physiological roles of DING proteins. P. fluorescens SBW25 is a model bacterium that can efficiently colonize plant surfaces and enhance plant health. In this report we genetically characterize Psp with a focus on conditions under which psp is expressed and the protein exported. Results Psp is closely related to the periplasmic Pi binding component of the ABC-type phosphate transporter system (Pst). psp is flanked by a gene cluster predicted to function as a type II protein secretion system (Hxc). Deletion analysis combined with chromosomally integrated 'lacZ fusions showed that both psp and pstC are induced by Pi limitation and that pstC is required for competitive growth of the bacterium in Pi limited medium. hxcR is not regulated by Pi limitation. Psp was detected (using anti-DING serum) in the supernatant of wild-type culture but was greatly reduced in the supernatant of an isogenic strain carrying an hxcR mutation (ΔhxcR). A promoter fusion between hxcR and a promoterless copy of a gene ('dapB) essential for growth in the plant environment showed that expression of hxcR is elevated during colonization of sugar beet seedlings. A similar analysis of psp showed that it is not induced in the plant environment. Conclusion Psp gene is expressed under conditions of Pi limitation. It is an exoprotein secreted mainly via the Hxc type II secretion system, whose expression is

  11. Antioxidative responses of Pseudomonas fluorescens YZ2 to simultaneous exposure of Zn and Cefradine.

    PubMed

    Xu, Yan-Bin; Xu, Jia-Xin; Chen, Jin-Liang; Huang, Lu; Zhou, Shao-Qi; Zhou, Yan; Wen, Li-Hua

    2015-10-01

    Binary pollution of both heavy metals and antibiotics has received increasing attentions for their joint effects of eco-toxicity and health hazards. To reveal the effects of mixtures of different pollutants on bacterial antioxidant response system, Pseudomonas fluorescens ZY2, a new strain isolated from swine wastewater, was chosen to determinate growth (bacterial density OD600), reactive oxygen species (ROS) concentration, protein concentration and superoxide dismutase (SOD) activity under exposure treatments of Zn, Cefradine or Zn + Cefradine. Bacterial densities of all the treatment groups increased significantly over the incubation time, but those containing pollutant addition were slightly lower than the control at different times of incubation. Both ROS concentration and SOD activity increased first and then decreased (p < 0.01) over time, which was opposite to the protein concentrations (p < 0.01), showing a much significant increase by Cefradine alone. With Zn concentration increasing from 40 to 160 mg/L, the intracellular SOD activity increased as a response to the improvement of ROS (p < 0.05), while the balance between ROS and SOD was broken down due to the disproportionate change of total SOD activity and ROS concentration, the bacterial densities therefore decreased for the weak resistance. With the combined treatment of Zn (200 mg/L) and Cefradine (1 mg/L), though the toxicity of Zn caused a much significant increase of ROS, the bacterial resistance was further improved showing a more significant increase of total SOD activity and the bacterial densities therefore increased bacterial growth. Zn concentration also affected the protein synthesis. Either single or binary stress induced the bacterial resistance by regulating SOD activity to eliminate ROS. All results of the bacterial oxidant stress, SOD response and protein synthesis in the combined treatment groups were more complicated than those in single treatment groups, which depended on the

  12. Influence of Incubation Conditions on Biofilm Formation by Pseudomonas Fluorescens Isolated from Dairy Products and Dairy Manufacturing Plants

    PubMed Central

    Rossi, Chiara; Chaves-López, Clemencia; Serio, Annalisa; Goffredo, Elisa; Goga, Beniamino Terzo Cenci; Paparella, Antonello

    2016-01-01

    In this study, biofilm formation of 64 Pseudomonas fluorescens strains isolated from milk, dairy products and dairy plants was compared. The strains were grown on Tryptic Soy Broth supplemented with 0.2% of glucose, on polystyrene microplates at 10 and 30°C for 48 h. In general, 57/64 P. fluorescens strains formed biofilm, although with great variability at both tested temperatures. Moreover, our results evidenced that the biofilm-forming ability of the strains was temperature- and strain-dependent. Interestingly, the ability of several isolates to form biofilms was associated with the low temperature after 48 h. Our findings evidenced that temperature was more important than incubation time for biofilm formation. Considering the origin of the strains, it is relevant to underline the importance of performing accurate cleaning and disinfection procedures on food processing surfaces. PMID:27853712

  13. Pseudomonas fluorescens HK44: Lessons Learned from a Model Whole-Cell Bioreporter with a Broad Application History

    PubMed Central

    Trögl, Josef; Chauhan, Archana; Ripp, Steven; Layton, Alice C.; Kuncová, Gabriela; Sayler, Gary S.

    2012-01-01

    Initially described in 1990, Pseudomonas fluorescens HK44 served as the first whole-cell bioreporter genetically endowed with a bioluminescent (luxCDABE) phenotype directly linked to a catabolic (naphthalene degradative) pathway. HK44 was the first genetically engineered microorganism to be released in the field to monitor bioremediation potential. Subsequent to that release, strain HK44 had been introduced into other solids (soils, sands), liquid (water, wastewater), and volatile environments. In these matrices, it has functioned as one of the best characterized chemically-responsive environmental bioreporters and as a model organism for understanding bacterial colonization and transport, cell immobilization strategies, and the kinetics of cellular bioluminescent emission. This review summarizes the characteristics of P. fluorescens HK44 and the extensive range of its applications with special focus on the monitoring of bioremediation processes and biosensing of environmental pollution. PMID:22438725

  14. Pseudomonas fluorescens HK44: lessons learned from a model whole-cell bioreporter with a broad application history.

    PubMed

    Trögl, Josef; Chauhan, Archana; Ripp, Steven; Layton, Alice C; Kuncová, Gabriela; Sayler, Gary S

    2012-01-01

    Initially described in 1990, Pseudomonas fluorescens HK44 served as the first whole-cell bioreporter genetically endowed with a bioluminescent (luxCDABE) phenotype directly linked to a catabolic (naphthalene degradative) pathway. HK44 was the first genetically engineered microorganism to be released in the field to monitor bioremediation potential. Subsequent to that release, strain HK44 had been introduced into other solids (soils, sands), liquid (water, wastewater), and volatile environments. In these matrices, it has functioned as one of the best characterized chemically-responsive environmental bioreporters and as a model organism for understanding bacterial colonization and transport, cell immobilization strategies, and the kinetics of cellular bioluminescent emission. This review summarizes the characteristics of P. fluorescens HK44 and the extensive range of its applications with special focus on the monitoring of bioremediation processes and biosensing of environmental pollution.

  15. Critical aspects of analysis of Micrococcus luteus, Neisseria cinerea, and Pseudomonas fluorescens by means of capillary electrophoresis.

    PubMed

    Hoerr, Verena; Stich, August; Holzgrabe, Ulrike

    2004-10-01

    Within the frame of our study we investigated Microccocus luteus, Neisseria cinerea, and Pseudomonas fluorescens by means of capillary zone electrophoresis (CZE). They form chains and clusters on a different scale, which can be reflected in the electropherograms. A low buffer concentration of Tris-borate and Na2EDTA containing a polymeric matrix of 0.0125% poly(ethylene) oxide (PEO) was used. Key factors were the standardization and optimization of CE conditions, buffer solution, and pretreatment of bacterial samples, which are not transferable to different bacterial strains, in general. The different compositions of the cell wall of on the one hand Gram-positive (M. luteus) and Gram-negative (N. cinerea) cocci and on the other hand Gram-negative, rod-shaped bacteria (P. fluorescens), are probably responsible for the different pretreatment conditions.

  16. Assessment of DAPG-producing Pseudomonas fluorescens for Management of Meloidogyne incognita and Fusarium oxysporum on Watermelon

    PubMed Central

    Meyer, Susan L. F.; Everts, Kathryne L.; Gardener, Brian McSpadden; Masler, Edward P.; Abdelnabby, Hazem M. E.; Skantar, Andrea M.

    2016-01-01

    Pseudomonas fluorescens isolates Clinto 1R, Wayne 1R, and Wood 1R, which produce the antibiotic 2,4-diacetylphloroglucinol (DAPG), can suppress soilborne diseases and promote plant growth. Consequently, these beneficial bacterial isolates were tested on watermelon plants for suppression of Meloidogyne incognita (root-knot nematode: RKN) and Fusarium oxysporum f. sp. niveum (Fon). In a greenhouse trial, Wayne 1R root dip suppressed numbers of RKN eggs per gram root on ‘Charleston Gray’ watermelon by 28.9%. However, in studies focused on ‘Sugar Baby’ watermelon, which is commercially grown in Maryland, a Wayne 1R root dip did not inhibit RKN reproduction or plant death caused by Fon. When all three isolates were applied as seed coats, plant stand in the greenhouse was reduced up to 60% in treatments that included Fon ± P. fluorescens, and eggs per gram root did not differ among treatments. In a microplot trial with Clinto 1R and Wayne 1R root dips, inoculation with P. fluorescens and/or Fon resulted in shorter vine lengths than treatment with either P. fluorescens isolate plus RKN. Root weights, galling indices, eggs per gram root, and second-stage juvenile (J2) numbers in soil were similar among all RKN-inoculated treatments, and fruit production was not affected by treatment. Plant death was high in all treatments. These studies demonstrated that the tested P. fluorescens isolates resulted in some inhibition of vine growth in the field, and were not effective for enhancing plant vigor or suppressing RKN or Fon on watermelon. PMID:27168652

  17. Characterization of Toxin Complex Gene Clusters and Insect Toxicity of Bacteria Representing Four Subgroups of Pseudomonas fluorescens

    PubMed Central

    Rangel, Lorena I.; Henkels, Marcella D.; Shaffer, Brenda T.; Walker, Francesca L.; Davis, Edward W.; Stockwell, Virginia O.; Bruck, Denny; Taylor, Barbara J.; Loper, Joyce E.

    2016-01-01

    Ten strains representing four lineages of the Pseudomonas fluorescens group (P. chlororaphis, P. corrugata, P. koreensis, and P. fluorescens subgroups) were evaluated for toxicity to the tobacco hornworm Manduca sexta and the common fruit fly Drosophila melanogaster. The three strains within the P. chlororaphis subgroup exhibited both oral and injectable toxicity to the lepidopteran M. sexta. All three strains have the gene cluster encoding the FitD insect toxin and a ΔfitD mutant of P. protegens strain Pf-5 exhibited diminished oral toxicity compared to the wildtype strain. Only one of the three strains, P. protegens Pf-5, exhibited substantial levels of oral toxicity against the dipteran D. melanogaster. Three strains in the P. fluorescens subgroup, which lack fitD, consistently showed significant levels of injectable toxicity against M. sexta. In contrast, the oral toxicity of these strains against D. melanogaster was variable between experiments, with only one strain, Pseudomonas sp. BG33R, causing significant levels of mortality in repeated experiments. Toxin complex (Tc) gene clusters, which encode insecticidal properties in Photorhabdus luminescens, were identified in the genomes of seven of the ten strains evaluated in this study. Within those seven genomes, six types of Tc gene clusters were identified, distinguished by gene content, organization and genomic location, but no correlation was observed between the presence of Tc genes and insect toxicity of the evaluated strains. Our results demonstrate that members of the P. fluorescens group have the capacity to kill insects by both FitD-dependent and independent mechanisms. PMID:27580176

  18. Iron-regulated metabolites produced by Pseudomonas fluorescens WCS374r are not required for eliciting induced systemic resistance against Pseudomonas syringae pv. tomato in Arabidopsis.

    PubMed

    Djavaheri, Mohammad; Mercado-Blanco, Jesús; Versluis, C; Meyer, J-M; Loon, L C; Bakker, Peter A H M

    2012-09-01

    The plant growth-promoting rhizobacterium Pseudomonas fluorescens WCS374r produces several iron-regulated metabolites, including the fluorescent siderophore pseudobactin (Psb374), salicylic acid (SA), and pseudomonine (Psm), a siderophore that contains a SA moiety. After purification of Psb374 from culture supernatant of WCS374r, its structure was determined following isoelectrofocusing and tandem mass spectrometry, and found to be identical to the fluorescent siderophore produced by P. fluorescens ATCC 13525. To study the role of SA and Psm production in colonization of Arabidopsis thaliana roots and in induced systemic resistance (ISR) against Pseudomonas syringae pv. tomato (Pst) by strain WCS374r, mutants disrupted in the production of these metabolites were obtained by homologous recombination. These mutants were further subjected to transposon Tn5 mutagenesis to generate mutants also deficient in Psb374 production. The mutants behaved similar to the wild type in both their Arabidopsis rhizosphere-colonizing capacity and their ability to elicit ISR against Pst. We conclude that Psb374, SA, and Psm production by P. fluorescens WCS374r are not required for eliciting ISR in Arabidopsis.

  19. Survival and ecological fitness of Pseudomonas fluorescens genetically engineered with dual biocontrol mechanisms.

    PubMed

    Bainton, N J; Lynch, J M; Naseby, D; Way, J A

    2004-10-01

    The antibiotic 2,4-diacetylphloroglucinol (Phl) is produced by a range of naturally occurring fluorescent pseudomonads. One isolate, Pseudomonas fluorescens F113, protects pea plants from the pathogenic fungus Pythium ultimum by reducing the number of pathogenic lesions on plant roots, but with a concurrent reduction in the emergence of plants such as pea. The genes responsible for Phl production have been shown to be functionally conserved between the wild-type (wt) P. fluorescens strains F113 and Q2-87. In this study the genes from F113 were isolated using an optimized long PCR method and a 6.7-kb gene cluster inserted into the chromosome of the non-Phl-producing P. fluorescens strain SBW25 EeZY6KX. This strain is a lacZY, km(R) marked derivative of the wt SBW25 which effects biological control against the plant pathogen Pythium ultimum by competitive exclusion as a result of its strong rhizosphere-colonizing ability. We describe here the integration of the Phl antifungal and competitive exclusion mechanisms into a single strain, and the impact this has on survival and plant emergence in microcosms. The insertion of the Phl biosynthetic genes from the F113 into the SBW25 chromosome gave a Phl-producing transformant (strain Pa21) able to suppress P. ultimum through antibiotic production. The growth of Pa21 was not reduced in flask culture at 20 degrees C compared with its parent strain. When inoculated on pea seedlings, the strain containing the Phl operon behaved similarly to the SBW25 EeZY6KX parent but did not show the tendency of the wt Phl producer F113 to cause lower pea seed emergence. Pea roots inoculated with SBW25 EeZY6KX have significantly lower indigenous populations than with F113 and the control. This is indicative of this strain's strong colonising presence. Pa21, the Phl-modified strain, is able to exclude the resident population from roots to the same degree as the SBW25 EeZY6KX from which it is derived. This suggests that it has maintained its

  20. The Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid inhibits growth of Erwinia amylovora and acts as a seed germination-arrest factor.

    PubMed

    Lee, Xiaoyun; Azevedo, Mark D; Armstrong, Donald J; Banowetz, Gary M; Reimmann, Cornelia

    2013-02-01

    The Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid (AMB) shares biological activities with 4-formylaminooxyvinylglycine, a related molecule produced by Pseudomonas fluorescens WH6. We found that culture filtrates of a P. aeruginosa strain overproducing AMB weakly interfered with seed germination of the grassy weed Poa annua and strongly inhibited growth of Erwinia amylovora, the causal agent of the devastating orchard crop disease known as fire blight. AMB was active against a 4-formylaminooxyvinylglycine-resistant isolate of E. amylovora, suggesting that the molecular targets of the two oxyvinylglycines in Erwinia do not, or not entirely, overlap. The AMB biosynthesis and transport genes were shown to be organized in two separate transcriptional units, ambA and ambBCDE, which were successfully expressed from IPTG-inducible tac promoters in the heterologous host P. fluorescens CHA0. Engineered AMB production enabled this model biocontrol strain to become inhibitory against E. amylovora and to weakly interfere with the germination of several graminaceous seeds. We conclude that AMB production requires no additional genes besides ambABCDE and we speculate that their expression in marketed fire blight biocontrol strains could potentially contribute to disease control.

  1. A physical genome map of Pseudomonas aeruginosa PAO.

    PubMed Central

    Römling, U; Grothues, D; Bautsch, W; Tümmler, B

    1989-01-01

    A complete macrorestriction map of the 5.9 Mb genome of Pseudomonas aeruginosa PAO (DSM 1707) was constructed by the combination of various one- and two-dimensional pulsed field gel electrophoresis techniques. A total of 51 restriction sites (36 SpeI sites, 15 DpnI sites) were placed on the physical map yielding an average resolution of 110 kb. Several genes encoding virulence factors and enzymes of metabolic pathways were located on the anonymous map by Southern hybridization. Distances between the gene loci were similar on the genetic and physical maps, suggesting an even distribution of genome mobility throughout the bacterial chromosome. The four rRNA operons were organized in pairs of inverted repeats. The two-dimensional macro-restriction techniques described herein are generally applicable for the genome mapping of any prokaryote and lower eukaryote which yields resolvable fragment patterns on two-dimensional pulsed field gels. Images PMID:2512121

  2. Heat shock mediated labelling of Pseudomonas aeruginosa with quantum dots.

    PubMed

    Kumar, Natasha; Wiraja, Christian; Palanisamy, Kannan; Marsili, Enrico; Xu, Chenjie

    2016-06-01

    Biocompatible nanoparticles are good candidates to label bacteria for imaging and diagnosis purposes. A high labeling efficiency reduces the concentration of nanoparticles required for labeling and allows the labeled bacteria to be tracked for longer periods. This report explores the optimal labeling strategy for Pseudomonas aeruginosa, a common gram-negative opportunistic pathogen, with quantum dots. Three strategies including direct incubation, calcium chloride treatment, and heat shock are compared and the labeling efficiency is assessed through fluorescence microscopy and flow cytometry analysis. Of the three, heat shock is finally selected due to its comparable labeling efficiency and simplicity. Through the assay of the respiration rate of bacteria together with morphology analysis, the heat shock process does not show any negative effect over the cells activity even at sub-toxic concentrations.

  3. Decrease of Pseudomonas aeruginosa biofilm formation by food waste materials.

    PubMed

    Maderova, Zdenka; Horska, Katerina; Kim, Sang-Ryoung; Lee, Chung-Hak; Pospiskova, Kristyna; Safarikova, Mirka; Safarik, Ivo

    2016-01-01

    The formation of bacterial biofilm on various surfaces has significant negative economic effects. The aim of this study was to find a simple procedure to decrease the Pseudomonas aeruginosa biofilm formation in a water environment by using different food waste biological materials as signal molecule adsorbents. The selected biomaterials did not reduce the cell growth but affected biofilm formation. Promising biomaterials were magnetically modified in order to simplify manipulation and facilitate their magnetic separation. The best biocomposite, magnetically modified spent grain, exhibited substantial adsorption of signal molecules and decreased the biofilm formation. These results suggest that selected food waste materials and their magnetically responsive derivatives could be applied to solve biofilm problems in water environment.

  4. Production of proteinase on noncarbohydrate carbon sources by Pseudomonas aeruginosa.

    PubMed

    Morihara, K

    1965-09-01

    Proteinase production by Pseudomonas aeruginosa was studied in medium containing noncarbohydrate materials, especially various hydrocarbons, as the sole carbon source. On heavy oil, kerosene, n-paraffinic hydrocarbon of C(12), C(14), or C(16), and propylene glycol, the bacteria grew well and high protinase production was observed. However, production on paraffinic hydrocarbon differed remarkably with strains of varied origins. The elastase-positive strain, IFO 3455, showed abundant growth and high proteinase production on medium containing a paraffin of C(12), C(14), or C(16), whereas the elastase-negative strain, IFO 3080, showed little growth on the same medium. Neither elastase-positive nor elastase-negative strains, however, utilized n-paraffins of C(5) to C(10), or various aromatic hydrocarbons such as benzene, naphthalene, phenanthrene, and anthracene. The proteinases produced on the noncarbohydrate medium were identical with those produced in glucose medium.

  5. Bioengineered lysozyme in combination therapies for Pseudomonas aeruginosa lung infections

    PubMed Central

    Griswold, Karl E; Bement, Jenna L; Teneback, Charlotte C; Scanlon, Thomas C; Wargo, Matthew J; Leclair, Laurie W

    2014-01-01

    There is increasing urgency in the battle against drug-resistant bacterial pathogens, and this public health crisis has created a desperate need for novel antimicrobial agents. Recombinant human lysozyme represents one interesting candidate for treating pulmonary infections, but the wild type enzyme is subject to electrostatic mediated inhibition by anionic biopolymers that accumulate in the infected lung. We have redesigned lysozyme’s electrostatic potential field, creating a genetically engineered variant that is less susceptible to polyanion inhibition, yet retains potent bactericidal activity. A recent publication demonstrated that the engineered enzyme outperforms wild type lysozyme in a murine model of Pseudomonas aeruginosa lung infection. Here, we expand upon our initial studies and consider dual therapies that combine lysozymes with an antimicrobial peptide. Consistent with our earlier results, the charge modified lysozyme combination outperformed its wild type counterpart, yielding more than an order-of-magnitude reduction in bacterial burden following treatment with a single dose. PMID:24637705

  6. Pseudomonas aeruginosa KUCD1, a possible candidate for cadmium bioremediation

    PubMed Central

    Sinha, Sangram; Mukherjee, Samir Kumar

    2009-01-01

    A cadmium (8 mM) resistant Pseudomonas aeruginosa strain KUCd1 exhibiting high Cd accumulation under in vitro aerobic condition has been reported. The isolate showed a significant ability to remove more than 75% and 89% of the soluble cadmium during the active growth phase from the growth medium and from Cd-amended industrial wastewater under growth supportive condition. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDXS) suggest the presence of Cd in the cells from mid stationary phase. The cell fractionation study revealed membrane and periplasm to be the major accumulating site in this strain. The chemical nature of the accumulated Cd was studied by X-ray powder diffraction analysis. PMID:24031411

  7. Crystal structure of PvdO from Pseudomonas aeruginosa.

    PubMed

    Yuan, Zenglin; Gao, Fei; Bai, Guohui; Xia, Hengchuan; Gu, Lichuan; Xu, Sujuan

    2017-02-26

    Pyoverdine I (PVDI) is a water-soluble fluorescein siderophore with strong iron chelating ability from the gram-negative pathogen Pseudomonas aeruginosa PAO1. Compared to common siderophores, PVDI is a relatively large compound whose synthesis requires a group of enzymes with different catalytic activities. In addition to four nonribosomal peptide synthetases (NRPS) which are responsible for the production of the peptide backbone of PVDI, several additional enzymes are associated with the modification of the side chains. PvdO is one of these enzymes and participates in PVDI precursor maturation in the periplasm. We determined the crystal structure of PvdO at 1.24 Å resolution. The PvdO structure shares a common fold with some FGly-generating enzymes (FGE) and is stabilized by Ca(2+). However, the catalytic residues in FGE are not observed in PvdO, indicating PvdO adopts a unique catalytic mechanism.

  8. Magnetic fields suppress Pseudomonas aeruginosa biofilms and enhance ciprofloxacin activity.

    PubMed

    Bandara, H M H N; Nguyen, D; Mogarala, S; Osiñski, M; Smyth, H D C

    2015-01-01

    Due to the refractory nature of pathogenic microbial biofilms, innovative biofilm eradication strategies are constantly being sought. Thus, this study addresses a novel approach to eradicate Pseudomonas aeruginosa biofilms. Magnetic nanoparticles (MNP), ciprofloxacin (Cipro), and magnetic fields were systematically evaluated in vitro for their relative anti-biofilm contributions. Twenty-four-hour biofilms exposed to aerosolized MNPs, Cipro, or a combination of both, were assessed in the presence or absence of magnetic fields (Static one-sided, Static switched, Oscillating, Static + oscillating) using changes in bacterial metabolism, biofilm biomass, and biofilm imaging. The biofilms exposed to magnetic fields alone exhibited significant metabolic and biomass reductions (p < 0.05). When biofilms were treated with a MNP/Cipro combination, the most significant metabolic and biomass reductions were observed when exposed to static switched magnetic fields (p < 0.05). The exposure of P. aeruginosa biofilms to a static switched magnetic field alone, or co-administration with MNP/Cipro/MNP + Cipro appears to be a promising approach to eradicate biofilms of this bacterium.

  9. Chromosomal DNA deletion confers phage resistance to Pseudomonas aeruginosa.

    PubMed

    Le, Shuai; Yao, Xinyue; Lu, Shuguang; Tan, Yinling; Rao, Xiancai; Li, Ming; Jin, Xiaolin; Wang, Jing; Zhao, Yan; Wu, Nicholas C; Lux, Renate; He, Xuesong; Shi, Wenyuan; Hu, Fuquan

    2014-04-28

    Bacteria develop a broad range of phage resistance mechanisms, such as prevention of phage adsorption and CRISPR/Cas system, to survive phage predation. In this study, Pseudomonas aeruginosa PA1 strain was infected with lytic phage PaP1, and phage-resistant mutants were selected. A high percentage (~30%) of these mutants displayed red pigmentation phenotype (Red mutant). Through comparative genomic analysis, one Red mutant PA1r was found to have a 219.6 kb genomic fragment deletion, which contains two key genes hmgA and galU related to the observed phenotypes. Deletion of hmgA resulted in the accumulation of a red compound homogentisic acid; while A galU mutant is devoid of O-antigen, which is required for phage adsorption. Intriguingly, while the loss of galU conferred phage resistance, it significantly attenuated PA1r in a mouse infection experiment. Our study revealed a novel phage resistance mechanism via chromosomal DNA deletion in P. aeruginosa.

  10. Type IV pili mechanochemically regulate virulence factors in Pseudomonas aeruginosa

    PubMed Central

    Persat, Alexandre; Inclan, Yuki F.; Engel, Joanne N.; Stone, Howard A.; Gitai, Zemer

    2015-01-01

    Bacteria have evolved a wide range of sensing systems to appropriately respond to environmental signals. Here we demonstrate that the opportunistic pathogen Pseudomonas aeruginosa detects contact with surfaces on short timescales using the mechanical activity of its type IV pili, a major surface adhesin. This signal transduction mechanism requires attachment of type IV pili to a solid surface, followed by pilus retraction and signal transduction through the Chp chemosensory system, a chemotaxis-like sensory system that regulates cAMP production and transcription of hundreds of genes, including key virulence factors. Like other chemotaxis pathways, pili-mediated surface sensing results in a transient response amplified by a positive feedback that increases type IV pili activity, thereby promoting long-term surface attachment that can stimulate additional virulence and biofilm-inducing pathways. The methyl-accepting chemotaxis protein-like chemosensor PilJ directly interacts with the major pilin subunit PilA. Our results thus support a mechanochemical model where a chemosensory system measures the mechanically induced conformational changes in stretched type IV pili. These findings demonstrate that P. aeruginosa not only uses type IV pili for surface-specific twitching motility, but also as a sensor regulating surface-induced gene expression and pathogenicity. PMID:26041805

  11. Identification of Pseudomonas aeruginosa Phenazines that Kill Caenorhabditis elegans

    PubMed Central

    Cezairliyan, Brent; Vinayavekhin, Nawaporn; Grenfell-Lee, Daniel; Yuen, Grace J.; Saghatelian, Alan; Ausubel, Frederick M.

    2013-01-01

    Pathogenic microbes employ a variety of methods to overcome host defenses, including the production and dispersal of molecules that are toxic to their hosts. Pseudomonas aeruginosa, a Gram-negative bacterium, is a pathogen of a diverse variety of hosts including mammals and the nematode Caenorhabditis elegans. In this study, we identify three small molecules in the phenazine class that are produced by P. aeruginosa strain PA14 that are toxic to C. elegans. We demonstrate that 1-hydroxyphenazine, phenazine-1-carboxylic acid, and pyocyanin are capable of killing nematodes in a matter of hours. 1-hydroxyphenazine is toxic over a wide pH range, whereas the toxicities of phenazine-1-carboxylic acid and pyocyanin are pH-dependent at non-overlapping pH ranges. We found that acidification of the growth medium by PA14 activates the toxicity of phenazine-1-carboxylic acid, which is the primary toxic agent towards C. elegans in our assay. Pyocyanin is not toxic under acidic conditions and 1-hydroxyphenazine is produced at concentrations too low to kill C. elegans. These results suggest a role for phenazine-1-carboxylic acid in mammalian pathogenesis because PA14 mutants deficient in phenazine production have been shown to be defective in pathogenesis in mice. More generally, these data demonstrate how diversity within a class of metabolites could affect bacterial toxicity in different environmental niches. PMID:23300454

  12. Pseudomonas aeruginosa: my research passion. Interview by Hannah Branch.

    PubMed

    Hazlett, Linda

    2013-07-01

    Linda Hazlett is a department chair and distinguished professor at Wayne State University (MI, USA). Her research is focused on the host immune response to Pseudomonas aeruginosa and its role in ocular infections. Dr Hazlett has been funded continuously by the NIH by R01 support for 34 years. She is currently principal investigator of two R01 grants from the National Eye Institute that study pathogenesis of P. aeruginosa in the eye. Dr Hazlett oversees four Course Directors who lead Year 1 medical student teaching, in addition to two graduate course directors. Furthermore, although not involved in medical teaching, she educates graduate students and mentors a Research Scientist and a Research Assistant Professor. Throughout her career, Dr Hazlett has achieved several honors and awards including Distinguished Professor at Wayne State University (2008), National Eye Institute Core Center (P30) grant for 1987-2013, Chair of Physiology Search 2008-2009, Member of the Academy of Scholars at Wayne State University, Association for Research in Vision and Ophthalmology fellow at the Gold Medal level (2009) and was an invited speaker at the Gordon Conference 2010.

  13. Production and properties of crude enterotoxin of Pseudomonas aeruginosa.

    PubMed

    Grover, S; Batish, V K; Srinivasan, R A

    1990-05-01

    Pseudomonas aeruginosa CTM-3 was found to be the most potentially enterotoxigenic strain out of the 12 isolates recovered from milk, as a high fluid length ratio, i.e. F/L (1.1) in rabbit gut and a strong permeability response in rabbit skin (38.5 mm2 necrotic zone) was obtained with this culture. No clear-cut relationship between the two tests was observed. Six of the ethidium bromide (300 micrograms/ml) cured variants of this culture completely lost their ability to produce enterotoxin indicating the possible involvement of a plasmid in enterotoxin synthesis. The crude enterotoxin from P. aeruginosa CTM-3 was completely inactivated in 15 s at 72 degrees C. However, it was fairly stable at pH values in the range 4.5-7.5. Both pepsin and trypsin inactivated the enterotoxin activity at a concentration of 40 micrograms/ml. Organic acids, formalin and hydrogen peroxide had no significant effect on the enterotoxin activity. The need for further investigations with purified preparations is emphasized.

  14. Mechanical destruction of pseudomonas aeruginosa biofilms by ultrasound exposure

    NASA Astrophysics Data System (ADS)

    Xu, Jin; Bigelow, Timothy A.; Halverson, Larry J.; Middendorf, Jill; Rusk, Ben

    2012-10-01

    Medical implants are prone to colonization by bacterial biofilms, which are highly resistant to antibiotics. Normally, surgery is required to replace the infected implant. One promising non-invasive treatment option is to destroy the biofilm with high-intensity focused ultrasound (HIFU) exposure. In our study, Pseudomonas aeruginosa bacterial biofilms were grown on graphite disks in a flow chamber for three days prior to exposing them to ultrasound pulses of varying duration or burst period. The pulses were 20 cycles in duration at a frequency of 1.1 MHz from a spherically focused transducer (f/1, 63 mm focal length), creating peak compressional and rarefactional pressures at the disk surface of 30 and 13 MPa, respectively. P. aeruginosa were tagged with GFP and cells killed by HIFU were visualized using propidium iodide, which permeates membranes of dead cells, to aid determining the extent of biofilm destruction and whether cells are alive or dead. Our results indicate that a 30-s exposure and 6-ms pulse period or those combinations with the same number of pulses, were sufficient to destroy the biofilm and to kill the remaining cells. Reducing the number of pulses decreased biofilm destruction, leaving more dead and live bacteria on the surface.

  15. Pseudomonas aeruginosa sabotages the generation of host proresolving lipid mediators.

    PubMed

    Flitter, Becca A; Hvorecny, Kelli L; Ono, Emiko; Eddens, Taylor; Yang, Jun; Kwak, Daniel H; Bahl, Christopher D; Hampton, Thomas H; Morisseau, Christophe; Hammock, Bruce D; Liu, Xinyu; Lee, Janet S; Kolls, Jay K; Levy, Bruce D; Madden, Dean R; Bomberger, Jennifer M

    2017-01-03

    Recurrent Pseudomonas aeruginosa infections coupled with robust, damaging neutrophilic inflammation characterize the chronic lung disease cystic fibrosis (CF). The proresolving lipid mediator, 15-epi lipoxin A4 (15-epi LXA4), plays a critical role in limiting neutrophil activation and tissue inflammation, thus promoting the return to tissue homeostasis. Here, we show that a secreted P. aeruginosa epoxide hydrolase, cystic fibrosis transmembrane conductance regulator inhibitory factor (Cif), can disrupt 15-epi LXA4 transcellular biosynthesis and function. In the airway, 15-epi LXA4 production is stimulated by the epithelial-derived eicosanoid 14,15-epoxyeicosatrienoic acid (14,15-EET). Cif sabotages the production of 15-epi LXA4 by rapidly hydrolyzing 14,15-EET into its cognate diol, eliminating a proresolving signal that potently suppresses IL-8-driven neutrophil transepithelial migration in vitro. Retrospective analyses of samples from patients with CF supported the translational relevance of these preclinical findings. Elevated levels of Cif in bronchoalveolar lavage fluid were correlated with lower levels of 15-epi LXA4, increased IL-8 concentrations, and impaired lung function. Together, these findings provide structural, biochemical, and immunological evidence that the bacterial epoxide hydrolase Cif disrupts resolution pathways during bacterial lung infections. The data also suggest that Cif contributes to sustained pulmonary inflammation and associated loss of lung function in patients with CF.

  16. Genotyping of Pseudomonas aeruginosa isolated from cockroaches and human urine.

    PubMed

    Saitou, Keiko; Furuhata, Katsunori; Fukuyama, Masafumi

    2010-10-01

    Molecular-epidemiological analysis of Pseudomonas aeruginosa isolated from cockroaches captured in hospitals and from patient urine was performed, employing randomly amplified polymorphic DNA (RAPD) analysis to investigate the usefulness of RAPD analysis. Four specific bands at positions of 993, 875, 521, and 402 bp were commonly detected using primer 272 in 16 of 45 cockroach-derived strains (35.6%), but not in 21 urine-derived strains. On analysis using primer 208, 4 specific bands at positions of 1,235, 1,138, 1,068, and 303 bp were commonly detected in 15 of the 45 cockroach-derived (33.3%) and 10 of the 21 patient urine-derived (47.6%) strains, in a total of 25 of 66 strains (37.8%). On cluster analysis, 12 (48.5%) and 16 (66.7%) clusters were grouped based on a homology of 89% or greater, using primer 272 and primer 208, respectively, showing that primer 208 was suitable for the confirmation of diversity. Seven patterns were clustered based on 100% homology using either primer, and 6 of these consisted of only cockroach-derived strains. In the individual groups with 100% homology, all strains in the group were isolated at an identical site during the same period. P. aeruginosa isolated from cockroaches showed diverse genotypes suggesting several sources of contamination, indicating the necessity for investigating infection control targeting cockroaches inhabiting hospitals.

  17. Pseudomonas aeruginosa Exopolyphosphatase Is Also a Polyphosphate: ADP Phosphotransferase.

    PubMed

    Beassoni, Paola R; Gallarato, Lucas A; Boetsch, Cristhian; Garrido, Mónica N; Lisa, Angela T

    2015-01-01

    Pseudomonas aeruginosa exopolyphosphatase (paPpx; EC 3.6.1.11) catalyzes the hydrolysis of polyphosphates (polyP), producing polyPn-1 plus inorganic phosphate (Pi). In a recent work we have shown that paPpx is involved in the pathogenesis of P. aeruginosa. The present study was aimed at performing the biochemical characterization of this enzyme. We found some properties that were already described for E. coli Ppx (ecPpx) but we also discovered new and original characteristics of paPpx: (i) the peptide that connects subdomains II and III is essential for enzyme activity; (ii) NH4 (+) is an activator of the enzyme and may function at concentrations lower than those of K(+); (iii) Zn(2+) is also an activator of paPpx and may substitute Mg(2+) in the catalytic site; and (iv) paPpx also has phosphotransferase activity, dependent on Mg(2+) and capable of producing ATP regardless of the presence or absence of K(+) or NH4 (+) ions. In addition, we detected that the active site responsible for the phosphatase activity is also responsible for the phosphotransferase activity. Through the combination of molecular modeling and docking techniques, we propose a model of the paPpx N-terminal domain in complex with a polyP chain of 7 residues long and a molecule of ADP to explain the phosphotransferase activity.

  18. Computer simulation of the rough lipopolysaccharide membrane of Pseudomonas aeruginosa.

    PubMed Central

    Lins, R D; Straatsma, T P

    2001-01-01

    Lipopolysaccharides (LPSs) form the major constituent of the outer membrane of Gram-negative bacteria, and are believed to play a key role in processes that govern microbial metal binding, microbial adsorption to mineral surfaces, and microbe-mediated oxidation/reduction reactions at the bacterial exterior surface. A computational modeling capability is being developed for the study of geochemical reactions at the outer bacterial envelope of Gram-negative bacteria. A molecular model for the rough LPS of Pseudomonas aeruginosa has been designed based on experimentally determined structural information. An electrostatic model was developed based on Hartree-Fock SCF calculations of the complete LPS molecule to obtain partial atomic charges. The exterior of the bacterial membrane was assembled by replication of a single LPS molecule and a single phospholipid molecule. Molecular dynamics simulations of the rough LPS membrane of P. aeruginosa were carried out and trajectories were analyzed for the energetic and structural factors that determine the role of LPS in processes at the cell surface. PMID:11463645

  19. Phage selection restores antibiotic sensitivity in MDR Pseudomonas aeruginosa.

    PubMed

    Chan, Benjamin K; Sistrom, Mark; Wertz, John E; Kortright, Kaitlyn E; Narayan, Deepak; Turner, Paul E

    2016-05-26

    Increasing prevalence and severity of multi-drug-resistant (MDR) bacterial infections has necessitated novel antibacterial strategies. Ideally, new approaches would target bacterial pathogens while exerting selection for reduced pathogenesis when these bacteria inevitably evolve resistance to therapeutic intervention. As an example of such a management strategy, we isolated a lytic bacteriophage, OMKO1, (family Myoviridae) of Pseudomonas aeruginosa that utilizes the outer membrane porin M (OprM) of the multidrug efflux systems MexAB and MexXY as a receptor-binding site. Results show that phage selection produces an evolutionary trade-off in MDR P. aeruginosa, whereby the evolution of bacterial resistance to phage attack changes the efflux pump mechanism, causing increased sensitivity to drugs from several antibiotic classes. Although modern phage therapy is still in its infancy, we conclude that phages, such as OMKO1, represent a new approach to phage therapy where bacteriophages exert selection for MDR bacteria to become increasingly sensitive to traditional antibiotics. This approach, using phages as targeted antibacterials, could extend the lifetime of our current antibiotics and potentially reduce the incidence of antibiotic resistant infections.

  20. Lipopeptide biosurfactant viscosin enhances dispersal of Pseudomonas fluorescens SBW25 biofilms.

    PubMed

    Bonnichsen, Lise; Bygvraa Svenningsen, Nanna; Rybtke, Morten; de Bruijn, Irene; Raaijmakers, Jos M; Tolker-Nielsen, Tim; Nybroe, Ole

    2015-12-01

    Pseudomonads produce several lipopeptide biosurfactants that have antimicrobial properties but that also facilitate surface motility and influence biofilm formation. Detailed studies addressing the significance of lipopeptides for biofilm formation and architecture are rare. Hence, the present study sets out to determine the specific role of the lipopeptide viscosin in Pseudomonas fluorescens SBW25 biofilm formation, architecture and dispersal, and to relate viscA gene expression to viscosin production and effect. Initially, we compared biofilm formation of SBW25 and the viscosin-deficient mutant strain SBW25ΔviscA in static microtitre assays. These experiments demonstrated that viscosin had little influence on the amount of biofilm formed by SBW25 during the early stages of biofilm development. Later, however, SBW25 formed significantly less biofilm than SBW25ΔviscA. The indication that viscosin is involved in biofilm dispersal was confirmed by chemical complementation of the mutant biofilm. Furthermore, a fluorescent bioreporter showed that viscA expression was induced in biofilms 4 h prior to dispersal. Subsequent detailed studies of biofilms formed in flow cells for up to 5 days revealed that SBW25 and SBW25ΔviscA developed comparable biofilms dominated by well-defined, mushroom-shaped structures. Carbon starvation was required to obtain biofilm dispersal in this system. Dispersal of SBW25 biofilms was significantly greater than of SBW25ΔviscA biofilms after 3 h and, importantly, carbon starvation strongly induced viscA expression, in particular for cells that were apparently leaving the biofilm. Thus, the present study points to a role for viscosin-facilitated motility in dispersal of SBW25 biofilms.

  1. Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe

    NASA Astrophysics Data System (ADS)

    Hack, Norman; Reinwand, Christian; Abbt-Braun, Gudrun; Horn, Harald; Frimmel, Fritz H.

    2015-12-01

    Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp = 200…600 μm, porosity ε = 0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol) = 0 after t = 6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest.

  2. Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe.

    PubMed

    Hack, Norman; Reinwand, Christian; Abbt-Braun, Gudrun; Horn, Harald; Frimmel, Fritz H

    2015-12-01

    Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200...600 μm, porosity ε=0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol)=0 after t=6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest.

  3. Biosurfactant production by Pseudomonas fluorescens growing on molasses and its application in phenol degradation

    NASA Astrophysics Data System (ADS)

    Suryantia, Venty; Marliyana, Soerya Dewi; Wulandari, Astri

    2015-12-01

    A molasses based medium for the biosurfactant production by Pseudomonas fluorescens was developed, where the effect of pre-treated of molasses and medium composition were evaluated. Biosurfactant production was followed by measuring optical density (OD), surface tension and emulsifying index (E24) over 12 days of fermentation. The optimum condition for the biosurfactant production was obtained when a medium containing of 8 g/L nutrient broth, 5 g/L NaCl, 1 g/L NH4NO3 and 5% v/v pre-treated molasses with centrifugation was used as media with 3 days of fermentation. The biosurfactant was identified as a rhamnolipid type biosurfactant which had critical micelle concentration (CMC) value of 801 mg/L and was able to reduce the surface tension of the water from 80 mN/m to 51 mN/m. The biosurfactants had water in oil (w/o) emulsion type. Biosurfactant was able to emulsify various hydrocarbons, which were able to decrase the interfacial tension about 50-75% when benzyl chloride, anisaldehyde and palm oil were used as immiscible compounds. The biosurfactant exhibited the E24 value of about 50% and the stable emulsion was reached up to 30 days when lubricant was used as an immiscible compound. Up to 68% of phenol was degraded in the presence of biosurfactant within 15 days, whereas only 56% of phenol was degraded in the absence of biosurfactant. Overall, the results exhibited that molasses are recommended for the rhamnolipids production which possessed good surface-active properties and had potential application in the enhancement of phenol degradation.

  4. IMPACT OF SIPHONING ACTIVITY AND NATURALLY SUSPENDED PARTICLE LOAD ON MUSSEL KILL by PSEUDOMONAS FLUORESCENS

    SciTech Connect

    Daniel Molloy

    2003-08-04

    Under this USDOE-NETL contract, the bacterium Pseudomonas fluorescens is being developed as a biocontrol agent for zebra mussels. The specific purpose of the contract is to identify biotic and abiotic factors that affect mussel kill. Ingestion of these bacteria by zebra mussels is required to achieve kill, and tests evaluating factors that relate to mussel feeding are contained in this report. Specifically the impact of the following two factors were investigated: (1) Mussel siphoning behavior--In nature, zebra mussels typically have their two shells spread apart and their inhalant siphon tube extended from between their shells for taking food particles into their mantle cavities (Fig. 1). Our tests indicated that there is a direct correlation between mussel siphoning activity and mussel mortality achieved by a bacterial treatment. Therefore, to encourage mussel feeding on bacteria, future pipe treatments within power plants should be carried out using procedures which minimize disturbance to mussel siphoning. 2. Naturally suspended particle loads--Since bacterial cells are lethal only if ingested by mussels, waters containing very high levels of naturally suspended particles might reduce the mortality that can be achieved by a bacterial treatment. If true, this inhibition might occur as a result of particle exclusion, i.e., there could be reduced ingestion of bacterial cells since they represent a reduced percentage of all particles ingested. Our tests indicated that a range of particle concentrations that might naturally exist in a turbid river did not inhibit mussel kill by the bacterial cells, but that an artificially high load of natural particles was capable of causing a reduction in kill. To be conservative, therefore, future pipe treatments should be timed to occur when intake waters have relatively low quantities of naturally suspended particulate matter.

  5. Evolution of New Enzymatic Function by Structural Modulation of Cysteine Reactivity in Pseudomonas fluorescens Isocyanide Hydratase

    SciTech Connect

    Lakshminarasimhan, Mahadevan; Madzelan, Peter; Nan, Ruth; Milkovic, Nicole M.; Wilson, Mark A.

    2010-09-13

    Isocyanide (formerly isonitrile) hydratase (EC 4.2.1.103) is an enzyme of the DJ-1 superfamily that hydrates isocyanides to yield the corresponding N-formamide. In order to understand the structural basis for isocyanide hydratase (ICH) catalysis, we determined the crystal structures of wild-type and several site-directed mutants of Pseudomonas fluorescens ICH at resolutions ranging from 1.0 to 1.9 {angstrom}. We also developed a simple UV-visible spectrophotometric assay for ICH activity using 2-naphthyl isocyanide as a substrate. ICH contains a highly conserved cysteine residue (Cys101) that is required for catalysis and interacts with Asp17, Thr102, and an ordered water molecule in the active site. Asp17 has carboxylic acid bond lengths that are consistent with protonation, and we propose that it activates the ordered water molecule to hydrate organic isocyanides. In contrast to Cys101 and Asp17, Thr102 is tolerant of mutagenesis, and the T102V mutation results in a substrate-inhibited enzyme. Although ICH is similar to human DJ-1 (1.6 {angstrom} C-{alpha} root mean square deviation), structural differences in the vicinity of Cys101 disfavor the facile oxidation of this residue that is functionally important in human DJ-1 but would be detrimental to ICH activity. The ICH active site region also exhibits surprising conformational plasticity and samples two distinct conformations in the crystal. ICH represents a previously uncharacterized clade of the DJ-1 superfamily that possesses a novel enzymatic activity, demonstrating that the DJ-1 core fold can evolve diverse functions by subtle modulation of the environment of a conserved, reactive cysteine residue.

  6. Bistability in a Metabolic Network Underpins the De Novo Evolution of Colony Switching in Pseudomonas fluorescens

    PubMed Central

    Gallie, Jenna; Libby, Eric; Bertels, Frederic; Remigi, Philippe; Jendresen, Christian B.; Ferguson, Gayle C.; Desprat, Nicolas; Buffing, Marieke F.; Sauer, Uwe; Beaumont, Hubertus J. E.; Martinussen, Jan; Kilstrup, Mogens; Rainey, Paul B.

    2015-01-01

    Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical insight was delivered by an experiment in which populations of the bacterium Pseudomonas fluorescens SBW25 evolved, de novo, the ability to switch between two colony phenotypes. Here we unravel the molecular mechanism behind colony switching, revealing how a single nucleotide change in a gene enmeshed in central metabolism (carB) generates such a striking phenotype. We show that colony switching is underpinned by ON/OFF expression of capsules consisting of a colanic acid-like polymer. We use molecular genetics, biochemical analyses, and experimental evolution to establish that capsule switching results from perturbation of the pyrimidine biosynthetic pathway. Of central importance is a bifurcation point at which uracil triphosphate is partitioned towards either nucleotide metabolism or polymer production. This bifurcation marks a cell-fate decision point whereby cells with relatively high pyrimidine levels favour nucleotide metabolism (capsule OFF), while cells with lower pyrimidine levels divert resources towards polymer biosynthesis (capsule ON). This decision point is present and functional in the wild-type strain. Finally, we present a simple mathematical model demonstrating that the molecular components of the decision point are capable of producing switching. Despite its simple mutational cause, the connection between genotype and phenotype is complex and multidimensional, offering a rare glimpse of how noise in regulatory networks can provide opportunity for evolution. PMID:25763575

  7. The increasing threat of Pseudomonas aeruginosa high-risk clones.

    PubMed

    Oliver, Antonio; Mulet, Xavier; López-Causapé, Carla; Juan, Carlos

    2015-01-01

    The increasing prevalence of chronic and hospital-acquired infections produced by multidrug-resistant (MDR) or extensively drug-resistant (XDR) Pseudomonas aeruginosa strains is associated with significant morbidity and mortality. This growing threat results from the extraordinary capacity of this pathogen for developing resistance through chromosomal mutations and from the increasing prevalence of transferable resistance determinants, particularly those encoding carbapenemases or extended-spectrum β-lactamases (ESBLs). P. aeruginosa has a nonclonal epidemic population structure, composed of a limited number of widespread clones which are selected from a background of a large quantity of rare and unrelated genotypes that are recombining at high frequency. Indeed, recent concerning reports have provided evidence of the existence of MDR/XDR global clones, denominated high-risk clones, disseminated in hospitals worldwide; ST235, ST111, and ST175 are likely those more widespread. Noteworthy, the vast majority of infections by MDR, and specially XDR, strains are produced by these and few other clones worldwide. Moreover, the association of high-risk clones, particularly ST235, with transferable resistance is overwhelming; nearly 100 different horizontally-acquired resistance elements and up to 39 different acquired β-lactamases have been reported so far among ST235 isolates. Likewise, MDR internationally-disseminated epidemic strains, such as the Liverpool Epidemic Strain (LES, ST146), have been noted as well among cystic fibrosis patients. Here we review the population structure, epidemiology, antimicrobial resistance mechanisms and virulence of the P. aeruginosa high-risk clones. The phenotypic and genetic factors potentially driving the success of high-risk clones, the aspects related to their detection in the clinical microbiology laboratory and the implications for infection control and public health are also discussed.

  8. Pseudomonas aeruginosa EftM Is a Thermoregulated Methyltransferase*

    PubMed Central

    Owings, Joshua P.; Kuiper, Emily G.; Prezioso, Samantha M.; Meisner, Jeffrey; Varga, John J.; Zelinskaya, Natalia; Dammer, Eric B.; Duong, Duc M.; Seyfried, Nicholas T.; Albertí, Sebastián; Conn, Graeme L.; Goldberg, Joanna B.

    2016-01-01

    Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that trimethylates elongation factor-thermo-unstable (EF-Tu) on lysine 5. Lysine 5 methylation occurs in a temperature-dependent manner and is generally only seen when P. aeruginosa is grown at temperatures close to ambient (25 °C) but not at higher temperatures (37 °C). We have previously identified the gene, eftM (for EF-Tu-modifying enzyme), responsible for this modification and shown its activity to be associated with increased bacterial adhesion to and invasion of respiratory epithelial cells. Bioinformatic analyses predicted EftM to be a Class I S-adenosyl-l-methionine (SAM)-dependent methyltransferase. An in vitro methyltransferase assay was employed to show that, in the presence of SAM, EftM directly trimethylates EF-Tu. A natural variant of EftM, with a glycine to arginine substitution at position 50 in the predicted SAM-binding domain, lacks both SAM binding and enzyme activity. Mass spectrometry analysis of the in vitro methyltransferase reaction products revealed that EftM exclusively methylates at lysine 5 of EF-Tu in a distributive manner. Consistent with the in vivo temperature dependence of methylation of EF-Tu, preincubation of EftM at 37 °C abolished methyltransferase activity, whereas this activity was retained when EftM was preincubated at 25 °C. Irreversible protein unfolding at 37 °C was observed, and we propose that this instability is the molecular basis for the temperature dependence of EftM activity. Collectively, our results show that EftM is a thermolabile, SAM-dependent methyltransferase that directly trimethylates lysine 5 of EF-Tu in P. aeruginosa. PMID:26677219

  9. Biotic inactivation of the Pseudomonas aeruginosa quinolone signal molecule.

    PubMed

    Soh, Eliza Ye-Chen; Chhabra, Siri R; Halliday, Nigel; Heeb, Stephan; Müller, Christine; Birmes, Franziska S; Fetzner, Susanne; Cámara, Miguel; Chan, Kok-Gan; Williams, Paul

    2015-11-01

    In Pseudomonas aeruginosa, quorum sensing (QS) regulates the production of secondary metabolites, many of which are antimicrobials that impact on polymicrobial community composition. Consequently, quenching QS modulates the environmental impact of P. aeruginosa. To identify bacteria capable of inactivating the QS signal molecule 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), a minimal medium containing PQS as the sole carbon source was used to enrich a Malaysian rainforest soil sample. This yielded an Achromobacter xylosoxidans strain (Q19) that inactivated PQS, yielding a new fluorescent compound (I-PQS) confirmed as PQS-derived using deuterated PQS. The I-PQS structure was elucidated using mass spectrometry and nuclear magnetic resonance spectroscopy as 2-heptyl-2-hydroxy-1,2-dihydroquinoline-3,4-dione (HHQD). Achromobacter xylosoxidans Q19 oxidized PQS congeners with alkyl chains ranging from C1 to C5 and also N-methyl PQS, yielding the corresponding 2-hydroxy-1,2-dihydroquinoline-3,4-diones, but was unable to inactivate the PQS precursor HHQ. This indicates that the hydroxyl group at position 3 in PQS is essential and that A. xylosoxidans inactivates PQS via a pathway involving the incorporation of oxygen at C2 of the heterocyclic ring. The conversion of PQS to HHQD also occurred on incubation with 12/17 A. xylosoxidans strains recovered from cystic fibrosis patients, with P. aeruginosa and with Arthrobacter, suggesting that formation of hydroxylated PQS may be a common mechanism of inactivation.

  10. Regional Control of Chromosome Segregation in Pseudomonas aeruginosa

    PubMed Central

    Lagage, Valentine

    2016-01-01

    Chromosome segregation in bacteria occurs concomitantly with DNA replication, and the duplicated regions containing the replication origin oriC are generally the first to separate and migrate to their final specific location inside the cell. In numerous bacterial species, a three-component partition machinery called the ParABS system is crucial for chromosome segregation. This is the case in the gammaproteobacterium Pseudomonas aeruginosa, where impairing the ParABS system is very detrimental for growth, as it increases the generation time and leads to the formation of anucleate cells and to oriC mispositioning inside the cell. In this study, we investigate in vivo the ParABS system in P. aeruginosa. Using chromatin immuno-precipitation coupled with high throughput sequencing, we show that ParB binds to four parS site located within 15 kb of oriC in vivo, and that this binding promotes the formation of a high order nucleoprotein complex. We show that one parS site is enough to prevent anucleate cell formation, therefore for correct chromosome segregation. By displacing the parS site from its native position on the chromosome, we demonstrate that parS is the first chromosomal locus to be separated upon DNA replication, which indicates that it is the site of force exertion of the segregation process. We identify a region of approximatively 650 kb surrounding oriC in which the parS site must be positioned for chromosome segregation to proceed correctly, and we called it “competence zone” of the parS site. Mutant strains that have undergone specific genetic rearrangements allow us to propose that the distance between oriC and parS defines this “competence zone”. Implications for the control of chromosome segregation in P. aeruginosa are discussed. PMID:27820816

  11. Emergence of colistin resistant Pseudomonas aeruginosa at Tabriz hospitals, Iran

    PubMed Central

    Goli, Hamid Reza; Nahaei, Mohammad Reza; Ahangarzadeh Rezaee, Mohammad; Hasani, Alka; Samadi Kafil, Hossein; Aghazadeh, Mohammad

    2016-01-01

    Background and Objectives: The prevalence of multidrug resistant Pseudomonas aeruginosa is the main reason of new drugs resurgence such as colistin. The main objectives of this study were to determine the antibiotic resistance pattern and the rate of colistin resistance along with its correlation with overexpression of MexAB-OprM and MexXY-OprM efflux pumps among P. aeruginosa isolates. Materials and Methods: Hundred clinical isolates were collected from 100 patients during 6 months in 2014. Susceptibility to the eight antibiotics was investigated using Kirby-Bauer and agar dilution methods. The Quantitative Real-time PCR was used to determine the expression levels of efflux genes. Results: Resistance rates to various antibiotics were as follows: ticarcillin (73%), ciprofloxacin (65%), aztreonam (60%), ceftazidime (55%), gentamicin (55%), imipenem (49%), piperacillin/tazobactam (34%) and colistin (2%). In disk diffusion method, only two isolates were non susceptible to colistin, however in agar dilution method the two isolates were confirmed as resistant and two others were intermediate resistant. Sixty eight (68%) isolates were multi-drug resistant and 10 isolates were susceptible to all tested antibiotics. Both colistin resistant isolates showed overexpression of both efflux pumps, but two intermediate resistant isolates exhibited reduction of efflux genes expression. Conclusions: Emergence of colistin resistance is increasing in P. aeruginosa indicating great challenge in the treatment of infections caused by MDR strains of this organism in Iran. ParRS may promote either induced or constitutive resistance to colistin through the activation of distinct mechanisms such as MDR efflux pumps, and LPS modification. PMID:27092226

  12. Draft Genome Sequences of Pseudomonas fluorescens Strains PA4C2 and PA3G8 and Pseudomonas putida PA14H7, Three Biocontrol Bacteria against Dickeya Phytopathogens

    PubMed Central

    Cigna, Jérémy; Raoul des Essarts, Yannick; Mondy, Samuel; Hélias, Valérie; Beury-Cirou, Amélie

    2015-01-01

    Pseudomonas fluorescens strains PA4C2 and PA3G8 and Pseudomonas putida strain PA14H7 were isolated from potato rhizosphere and show an ability to inhibit the growth of Dickeya phytopathogens. Here, we report their draft genome sequences, which provide a basis for understanding the molecular mechanisms involved in antibiosis against Dickeya. PMID:25635023

  13. Effect of humic fractions and clay on biodegradation of phenanthrene by a Pseudomonas fluorescens strain isolated from soil

    SciTech Connect

    Ortega-Calvo, J.J.; Saiz-Jimenez, C.

    1998-08-01

    The mineralization of phenanthrene in pure cultures of a Pseudomonas fluorescens strain, isolated from soil, was measured in the presence of soil humic fractions and montmorillonite. Humic acid and clay, either separately or in combination, shortened the acclimation phase. A higher mineralization rate was measured in treatments with humic acid at 100 {micro}g/ml. Humic acid at 10 {micro}g/ml stimulated the transformation only in the presence of 10 g of clay per liter. The authors suggest that sorption of phenanthrene to these soil components may result in a higher concentration of substrate in the vicinity of the bacterial cells and therefore may increase its bioavailability.

  14. Quantifying Pseudomonas aeruginosa quinolones and examining their interactions with lipids.

    PubMed

    Palmer, Gregory C; Schertzer, Jeffrey W; Mashburn-Warren, Lauren; Whiteley, Marvin

    2011-01-01

    Pseudomonas aeruginosa produces a quorum sensing molecule termed the Pseudomonas Quinolone Signal (2-heptyl-3-hydroxy-4-quinolone; PQS) that regulates an array of genes involved in virulence. This chapter addresses four related techniques useful for detecting and quantifying PQS. First, extraction of PQS from complex mixtures (e.g. cell cultures) is described. Separation of PQS from extracts by Thin-Layer Chromatography (TLC) is used in combination with the natural fluorescence of the molecule for quantification. A second separation technique for the PQS precursor HHQ using High-Performance Liquid Chromatography (HPLC) is also described, and this assay exploits the molecule's characteristic absorbance for quantification. A third method for quantification of PQS from simple mixtures (e.g. enzyme assays) using fluorescence is outlined. Finally, a protocol for determining PQS interactions with membrane lipids through Fluorescence Resonance Energy Transfer (FRET) is presented. These techniques allow for quantification and characterization of PQS from diverse environments, a prerequisite to understanding the biological functions of QS molecules.

  15. Chemically defined antimicrobial susceptibility test medium for Pseudomonas aeruginosa.

    PubMed

    Jorgensen, J H; Lee, J C; Jones, P M

    1977-03-01

    A chemically defined growth medium containing physiological concentrations of magnesium and calcium ions was utilized in a microdilution procedure for antimicrobial drug susceptibility testing of Pseudomonas aeruginosa. Determinations of growth end points were simplified by use of sodium citrate as a sole carbon source and bromothymol blue as a pH indicator. Growth of the test organisms was detectable by a change in the indicator color from green to blue after alkalinization of the medium due to citrate utilization. Minimal inhibitory concentrations of amikacin, carbenicillin, gentamicin, and tobramycin were determined on 100 recent clinical isolates of Pseudomonas. Parallel determinations using the microdilution procedure and a conventional tube-broth dilution technique incorporating Mueller-Hinton broth with identical magnesium and calcium content generally agreed within one twofold dilution. Modal minimal inhibitory concentrations for susceptible strains using the microdilution method were: amikacin, 6 mug/ml; carbenicillin, 50 mug/ml; gentamicin, 1.5 mug/ml; tobramycin, 1.5 mug/ml. This modified microdilution technique allowed rapid, definitive minimal inhibitory concentration determinations, using growth end points defined by a color indicator change.

  16. Biocontrol of collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii by using rhizosphere-competent Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N.

    PubMed

    Singh, Anand; Mehta, Sangeeta; Singh, Harikesh Bahadur; Nautiyal, Chandra Shekhar

    2003-08-01

    Collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii is difficult to control by conventional means by use of chemicals; therefore, use of biocontrol agents is desirable. In the present study, 186 bacterial strains of different morphological types were screened for their biocontrol activity against S. rolfsii under in vitro conditions. Two strains, Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N, were selected for further studies because of their ability to inhibit the mycelial growth of the pathogen significantly. Spontaneous rifampicin-resistant (Rif) derivatives of P. fluorescens NBRI-N6 and P. fluorescens NBRI-N showing growth rate and membrane protein composition comparable to the wild type were selected to facilitate their monitoring in the rhizosphere. Field trials demonstrated that strain P. fluorescens NBRI-N6 was better than P. fluorescens NBRI-N in increasing the yield of betelvine significantly, whereas a consortium of the two strains controlled the disease more than either of the strains. The screening method should prove useful in identifying rhizosphere bacteria with the greatest potential for controlling diseases caused by phytopathogenic fungi.

  17. Comparison of UVB and UVC irradiation disinfection efficacies on Pseudomonas Aeruginosa (P. aeruginosa) biofilm

    NASA Astrophysics Data System (ADS)

    Argyraki, A.; Markvart, M.; Nielsen, Anne; Bjarnsholt, T.; Bjørndal, L.; Petersen, P. M.

    2016-04-01

    Disinfection routines are important in all clinical applications. The uprising problem of antibiotic resistance has driven major research efforts towards alternative disinfection approaches, involving light-based solutions. Pseudomonas aeruginosa (P. aeruginosa) is a common bacterium that can cause skin, soft tissue, lungs, kidney and urinary tract infections. Moreover, it can be found on and in medical equipment causing often cross infections in hospitals. The objective of this study was to test the efficiency, of two different light-based disinfection treatments, namely UVB and UVC irradiation, on P. aeruginosa biofilms at different growth stages. In our experiments a new type of UV light emitting diodes (LEDs) were used to deliver UV irradiation on the biofilms, in the UVB (296nm) and UVC (266nm) region. The killing rate was studied as a function of dose for 24h grown biofilms. The dose was ramped from 72J/m2 to 10000J/m2. It was shown that UVB irradiation was more effective than UVC irradiation in inactivating P. aeruginosa biofilms. No colony forming units (CFU) were observed for the UVB treated biofilms when the dose was 10000 J/m2 (CFU in control sample: 7.5 x 104). UVB irradiation at a dose of 20000J/m2 on mature biofilms (72h grown) resulted in a 3.9 log killing efficacy. The fact that the wavelength of 296nm exists in daylight and has such disinfection ability on biofilms gives new perspectives for applications within disinfection at hospitals.

  18. Influence of the hydrodynamic environment on quorum sensing in Pseudomonas aeruginosa biofilms.

    PubMed

    Kirisits, Mary Jo; Margolis, Jeffrey J; Purevdorj-Gage, Boloroo L; Vaughan, Benjamin; Chopp, David L; Stoodley, Paul; Parsek, Matthew R

    2007-11-01

    We provide experimental and modeling evidence that the hydrodynamic environment can impact quorum sensing (QS) in a Pseudomonas aeruginosa biofilm. The amount of biofilm biomass required for full QS induction of the population increased as the flow rate increased.

  19. Lichen secondary metabolite evernic acid as potential quorum sensing inhibitor against Pseudomonas aeruginosa.

    PubMed

    Gökalsın, Barış; Sesal, Nüzhet Cenk

    2016-09-01

    Cystic Fibrosis is a genetic disease and it affects the respiratory and digestive systems. Pseudomonas aeruginosa infections in Cystic Fibrosis are presented as the main cause for high mortality and morbidity rates. Pseudomonas aeruginosa populations can regulate their virulence gene expressions via the bacterial communication system: quorum sensing. Inhibition of quorum sensing by employing quorum sensing inhibitors can leave the bacteria vulnerable. Therefore, determining natural sources to obtain potential quorum sensing inhibitors is essential. Lichens have ethnobotanical value for their medicinal properties and it is possible that their secondary metabolites have quorum sensing inhibitor properties. This study aims to investigate an alternative treatment approach by utilizing lichen secondary metabolite evernic acid to reduce the expressions of Pseudomonas aeruginosa virulence factors by inhibiting quorum sensing. For this purpose, fluorescent monitor strains were utilized for quorum sensing inhibitor screens and quantitative reverse-transcriptase PCR analyses were conducted for comparison. Results indicate that evernic acid is capable of inhibiting Pseudomonas aeruginosa quorum sensing systems.

  20. Epidemiology and Ecology of Opportunistic Premise Plumbing Pathogens: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa

    EPA Science Inventory

    BACKGROUND: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa are opportunistic premise plumbing pathogens (OPPPs) that persist and grow in household plumbing, habitats they share with humans. Infections caused by these OPPPs involve individuals with preexis...

  1. Accelerated corrosion of 2205 duplex stainless steel caused by marine aerobic Pseudomonas aeruginosa biofilm.

    PubMed

    Xu, Dake; Xia, Jin; Zhou, Enze; Zhang, Dawei; Li, Huabing; Yang, Chunguang; Li, Qi; Lin, Hai; Li, Xiaogang; Yang, Ke

    2017-02-01

    Microbiologically influenced corrosion (MIC) of 2205 duplex stainless steel (DSS) in the presence of Pseudomonas aeruginosa was investigated through electrochemical and surface analyses. The electrochemical results showed that P. aeruginosa significantly reduced the corrosion resistance of 2205 DSS. Confocal laser scanning microscopy (CLSM) images showed that the depths of the largest pits on 2205 DSS with and without P. aeruginosa were 14.0 and 4.9μm, respectively, indicating that the pitting corrosion was accelerated by P. aeruginosa. X-ray photoelectron spectroscopy (XPS) results revealed that CrO3 and CrN formed on the 2205 DSS surface in the presence of P. aeruginosa.

  2. Isolation and characterization of antimicrobial cyclic dipeptides from Pseudomonas fluorescens and their efficacy on sorghum grain mold fungi.

    PubMed

    Sajeli Begum, Ahil; Basha, Shaik Ameer; Raghavendra, Govardhanam; Kumar, Mallela Venkata Nagesh; Singh, Yukthi; Patil, Jagannath V; Tanemura, Yuhei; Fujimoto, Yoshinori

    2014-01-01

    This study was aimed at isolation and characterization of natural antifungal compounds for grain mold, a key parasitic fungal disease of sorghum. Pseudomonas fluorescens strain isolated from rhizosphere of groundnut crop was selected as a source. Its biocontrolling ability was assessed by testing some biochemical attributes such as phosphate-solubilization, and HCN, NH3 , indole-3-acetic acid, and siderophore production. The strain showed positive result for all except indole-3-acetic acid, revealing its suitability for a further study. The antibiotic-sensitivity pattern of the strain against 43 antibiotics was also established, which showed resistance to 15 antibiotics. The efficacy of P. fluorescens strain against grain mold was identified by dual culture technique. Hundred percent inhibition was found against Fusarium moniliforme, an important causative agent of this disease. The strain was fermented for secondary metabolites and extracted with AcOEt. Chromatographic separation of the extract yielded four known compounds, cyclo(L-Pro-L-Phe) (1), cyclo(trans-4-hydroxy-L-Pro-L-Leu) (2), cyclo(trans-4-hydroxy-L-Pro-L-Phe) (3), and cyclo(Gly-L-Pro) (4), which were characterized by spectral analysis and optical rotation. The crude extract, a mixture of 2 and 3, and isolated 1 were proved to be significantly effective against grain mold fungi. This is the first report on production of these cyclic dipeptides by P. fluorescens and their antagonistic properties.

  3. Identification of a New Phosphatase Enzyme Potentially Involved in the Sugar Phosphate Stress Response in Pseudomonas fluorescens.

    PubMed

    Maleki, Susan; Hrudikova, Radka; Zotchev, Sergey B; Ertesvåg, Helga

    2017-01-15

    The alginate-producing bacterium Pseudomonas fluorescens utilizes the Entner-Doudoroff (ED) and pentose phosphate (PP) pathways to metabolize fructose, since the upper part of its Embden-Meyerhof-Parnas pathway is defective. Our previous study indicated that perturbation of the central carbon metabolism by diminishing glucose-6-phosphate dehydrogenase activity could lead to sugar phosphate stress when P. fluorescens was cultivated on fructose. In the present study, we demonstrate that PFLU2693, annotated as a haloacid dehalogenase-like enzyme, is a new sugar phosphate phosphatase, now designated Spp, which is able to dephosphorylate a range of phosphate substrates, including glucose 6-phosphate and fructose 6-phosphate, in vitro The effect of spp overexpression on growth and alginate production was investigated using both the wild type and several mutant strains. The results obtained suggested that sugar phosphate accumulation caused diminished growth in some of the mutant strains, since this was partially relieved by spp overexpression. On the other hand, overexpression of spp in fructose-grown alginate-producing strains negatively affected both growth and alginate production. The latter implies that Spp dephosphorylates the sugar phosphates, thus depleting the pool of these important metabolites. Deletion of the spp gene did not affect growth of the wild-type strain on fructose, but the gene could not be deleted in the alginate-producing strain. This indicates that Spp is essential for relieving the cells of sugar phosphate stress in P. fluorescens actively producing alginate.

  4. Development of bioformulation and delivery system of Pseudomonas fluorescens against bacterial leaf blight of rice (Xanthomonas oryzae pv. oryzae).

    PubMed

    Jambhulkar, P P; Sharma, P

    2014-09-01

    Antagonistic potential of Pseudomonas fluorescens isolate RRb-11 has been evaluated against bacterial leaf blight (BLB) pathogen of rice in vitro, in vivo, microplot and field tests. RRb-11 isolate mass multiplied in substrates like talc and kaolinite powder and bran of barley, soybean and wheat to prepare suitable bioformulation. The maximum shelf life of P. fluorescens was recorded in talc based bioformulation up to 150 days after storage. In rhizosphere competence study, the root rhizosphere of talc, kaolinite and barley based bioformulation treated plants showed good survivability and competence even up to 90 days after treatment. In field study, the talc based bioformulation was applied and the best results were obtained when talc based bioformulation of P. fluorescens RRb-11 was applied as seed treatment, seedling root dip and soil application in combination which reduced the disease by 92.3 and 88.5% over control in the year 2009 and 2010, respectively. This treatment also produced maximum yield of 3.88 t ha(-1) i.e., 61% greater than control.

  5. Pseudomonas fluorescens induces strain-dependent and strain-independent host plant responses in defense networks, primary metabolism and photosynthesis

    SciTech Connect

    Pelletier, Dale A; Morrell-Falvey, Jennifer L; Karve, Abhijit A; Lu, Tse-Yuan S; Tschaplinski, Timothy J; Tuskan, Gerald A; Chen, Jay; Martin, Madhavi Z; Jawdy, Sara; Weston, David; Doktycz, Mitchel John; Schadt, Christopher Warren

    2012-01-01

    Colonization of plants by nonpathogenic Pseudomonas fluorescens strains can confer enhanced defense capacity against a broad spectrum of pathogens. Few studies, however, have linked defense pathway regulation to primary metabolism and physiology. In this study, physiological data, metabolites, and transcript profiles are integrated to elucidate how molecular networks initiated at the root-microbe interface influence shoot metabolism and whole-plant performance. Experiments with Arabidopsis thaliana were performed using the newly identified P. fluorescens GM30 or P. fluorescens Pf-5 strains. Co-expression networks indicated that Pf-5 and GM30 induced a subnetwork specific to roots enriched for genes participating in RNA regulation, protein degradation, and hormonal metabolism. In contrast, only GM30 induced a subnetwork enriched for calcium signaling, sugar and nutrient signaling, and auxin metabolism, suggesting strain dependence in network architecture. In addition, one subnetwork present in shoots was enriched for genes in secondary metabolism, photosynthetic light reactions, and hormone metabolism. Metabolite analysis indicated that this network initiated changes in carbohydrate and amino acid metabolism. Consistent with this, we observed strain-specific responses in tryptophan and phenylalanine abundance. Both strains reduced host plant carbon gain and fitness, yet provided a clear fitness benefit when plants were challenged with the pathogen P. syringae DC3000.

  6. Induction of laccase activity in Rhizoctonia solani by antagonistic Pseudomonas fluorescens strains and a range of chemical treatments.

    PubMed

    Crowe, J D; Olsson, S

    2001-05-01

    Fungi often produce the phenoloxidase enzyme laccase during interactions with other organisms, an observation relevant to the development of biocontrols. By incorporating the laccase substrate 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) into agar, we analyzed laccase induction in the plant-pathogenic fungus Rhizoctonia solani when paired against isolates of the soil bacterium Pseudomonas fluorescens. Substantial induction of R. solani laccase was seen only in pairings with strains of P. fluorescens known to produce antifungal metabolites. To study laccase induction further, a range of chemical treatments was applied to R. solani liquid cultures. p-Anisidine, copper(II), manganese(II), calcium ionophore A23187, lithium chloride, calcium chloride, cyclic AMP (cAMP), caffeine, amphotericin B, paraquat, ethanol, and isopropanol were all found to induce laccase; however, the P. fluorescens metabolite viscosinamide did not do so at the concentrations tested. The stress caused by these treatments was assessed by measuring changes in lipid peroxidation levels and dry weight. The results indicated that the laccase induction seen in pairing plate experiments was most likely due to calcium or heat shock signaling in response to the effects of bacterial metabolites, but that heavy metal and cAMP-driven laccase induction was involved in sclerotization.

  7. Pseudomonas fluorescens Filamentous Hemagglutinin, an Iron-Regulated Protein, Is an Important Virulence Factor that Modulates Bacterial Pathogenicity

    PubMed Central

    Sun, Yuan-Yuan; Chi, Heng; Sun, Li

    2016-01-01

    Pseudomonas fluorescens is a common bacterial pathogen to a wide range of aquaculture animals including various species of fish. In this study, we employed proteomic analysis and identified filamentous hemagglutinin (FHA) as an iron-responsive protein secreted by TSS, a pathogenic P. fluorescens isolate. In vitro study showed that compared to the wild type, the fha mutant TSSfha (i) exhibited a largely similar vegetative growth profile but significantly retarded in the ability of biofilm growth and producing extracellular matrix, (ii) displayed no apparent flagella and motility, (iii) was defective in the attachment to host cells and unable to form self-aggregation, (iv) displayed markedly reduced capacity of hemagglutination and surviving in host serum. In vivo infection analysis revealed that TSSfha was significantly attenuated in the ability of dissemination in fish tissues and inducing host mortality, and that antibody blocking of the natural FHA produced by the wild type TSS impaired the infectivity of the pathogen. Furthermore, when introduced into turbot as a subunit vaccine, recombinant FHA elicited a significant protection against lethal TSS challenge. Taken together, these results indicate for the first time that P. fluorescens FHA is a key virulence factor essential to multiple biological processes associated with pathogenicity. PMID:27602029

  8. Small colony variants are more susceptible to copper-mediated contact killing for Pseudomonas aeruginosa and Staphylococcus aureus.

    PubMed

    Liu, Sha; Zhang, Xue-Xian

    2016-10-01

    Applying self-sanitizing copper surfaces to commonly touched places within hospital facilities is an emerging strategy to prevent healthcare-associated infections. This is due to the fact that bacterial pathogens are rapidly killed on copper, a process termed contact killing. However, the mechanisms of contact killing are not fully understood, and the potential of bacterial pathogens to develop resistance has rarely been explored. Here, we hypothesize that bacteria are predominantly killed by a burst release of toxic copper ions, resulting from chemical reactions between bacterial cell surface components and metallic copper. To test this, we isolated and characterized small colony variants (SCVs) derived from Pseudomonas aeruginosa and Staphylococcus aureus. SCVs overproduce extracellular polymeric substances (EPS), which will enhance copper ion release, causing more rapid death on copper. Indeed, all 13 SCVs tested were more rapidly killed than wild-types on the surfaces of both pure copper and brass (63.5 % Cu). Next, using the non-pathogenic Pseudomonas fluorescens SBW25 as a model, we examined the roles of specific cell surface components in contact killing, including EPS, LPS, capsule, flagella and pili. We also subjected P. fluorescens SBW25 to daily serial passage of sub-lethal conditions on brass. After 100 transfers, there was a slight increase of survival rate, but ~97 % of cells can still be killed within 60 min on brass. Together, our data implicate that the rate of contact killing on copper is largely determined by the cell surface components, and bacteria have limited ability to evolve resistance to metallic copper.

  9. Photodynamic antimicrobial therapy to inhibit pseudomonas aeruginosa of corneal isolates (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Durkee, Heather A.; Relhan, Nidhi; Arboleda, Alejandro; Halili, Francisco; De Freitas, Carolina; Alawa, Karam; Aguilar, Mariela C.; Amescua, Guillermo; Miller, Darlene; Parel, Jean-Marie

    2016-03-01

    Keratitis associated with Pseudomonas aeruginosa is difficult to manage. Treatment includes antibiotic eye drops, however, some strains of Pseudomonas aeruginosa are resistant. Current research efforts are focused on finding alternative and adjunct therapies to treat multi-drug resistant bacteria. One promising alternate technique is photodynamic therapy (PDT). The purpose of this study was to evaluate the effect of riboflavin- and rose bengal-mediated PDT on Pseudomonas aeruginosa keratitis isolates in vitro. Two isolates (S+U- and S-U+) of Pseudomonas aeruginosa were derived from keratitis patients and exposed to five experimental groups: (1) Control (dark, UV-A irradiation, 525nm irradiation); (2) 0.1% riboflavin (dark, UV-A irradiation); and (3) 0.1% rose bengal, (4) 0.05% rose bengal and (5) 0.01% rose bengal (dark, 525nm irradiation). Three days after treatment, in dark conditions of all concentration of riboflavin and rose bengal showed no inhibition in both S+U- and S-U+ strains of Pseudomonas aeruginosa. In 0.1% and 0.05% rose bengal irradiated groups, for both S+U- and S-U+ strains, there was complete inhibition of bacterial growth in the central 50mm zone corresponding to the diameter of the green light source. These in vitro results suggest that rose bengal photodynamic therapy may be an effective adjunct treatment for Pseudomonas aeruginosa keratitis.

  10. The Pseudomonas aeruginosa Pathogenicity Island PAPI-1 is transferred via a novel Type IV pilus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas aeruginosa is a major cause of nosocomial infections, particularly in immunocompromised patients or in individuals with cystic fibrosis. The notable ability of P. aeruginosa to inhabit a broad range of environments including humans is in part due to its large and diverse genomic repertoi...

  11. Draft Genome Sequence of Beneficial Rice Rhizosphere Isolate Pseudomonas aeruginosa PUPa3

    PubMed Central

    Uzelac, Gordana; Bertani, Iris; Kojic, Milan; Paszkiewicz, Konrad H.; Studholme, David J.; Passos da Silva, Daniel

    2014-01-01

    Pseudomonas aeruginosa PUPa3 is a rhizosphere-colonizing and plant growth-promoting strain isolated from the rhizosphere of rice. This strain has, however, been shown to be pathogenic in two nonmammalian infection models. Here we report the draft genome sequence of P. aeruginosa PUPa3. PMID:24994800

  12. Draft Genome Sequence of Beneficial Rice Rhizosphere Isolate Pseudomonas aeruginosa PUPa3.

    PubMed

    Uzelac, Gordana; Bertani, Iris; Kojic, Milan; Paszkiewicz, Konrad H; Studholme, David J; Passos da Silva, Daniel; Venturi, Vittorio

    2014-07-03

    Pseudomonas aeruginosa PUPa3 is a rhizosphere-colonizing and plant growth-promoting strain isolated from the rhizosphere of rice. This strain has, however, been shown to be pathogenic in two nonmammalian infection models. Here we report the draft genome sequence of P. aeruginosa PUPa3.

  13. Network-assisted investigation of virulence and antibiotic-resistance systems in Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Hwang, Sohyun; Kim, Chan Yeong; Ji, Sun-Gou; Go, Junhyeok; Kim, Hanhae; Yang, Sunmo; Kim, Hye Jin; Cho, Ara; Yoon, Sang Sun; Lee, Insuk

    2016-05-01

    Pseudomonas aeruginosa is a Gram-negative bacterium of clinical significance. Although the genome of PAO1, a prototype strain of P. aeruginosa, has been extensively studied, approximately one-third of the functional genome remains unknown. With the emergence of antibiotic-resistant strains of P. aeruginosa, there is an urgent need to develop novel antibiotic and anti-virulence strategies, which may be facilitated by an approach that explores P. aeruginosa gene function in systems-level models. Here, we present a genome-wide functional network of P. aeruginosa genes, PseudomonasNet, which covers 98% of the coding genome, and a companion web server to generate functional hypotheses using various network-search algorithms. We demonstrate that PseudomonasNet-assisted predictions can effectively identify novel genes involved in virulence and antibiotic resistance. Moreover, an antibiotic-resistance network based on PseudomonasNet reveals that P. aeruginosa has common modular genetic organisations that confer increased or decreased resistance to diverse antibiotics, which accounts for the pervasiveness of cross-resistance across multiple drugs. The same network also suggests that P. aeruginosa has developed mechanism of trade-off in resistance across drugs by altering genetic interactions. Taken together, these results clearly demonstrate the usefulness of a genome-scale functional network to investigate pathogenic systems in P. aeruginosa.

  14. Network-assisted investigation of virulence and antibiotic-resistance systems in Pseudomonas aeruginosa

    PubMed Central

    Hwang, Sohyun; Kim, Chan Yeong; Ji, Sun-Gou; Go, Junhyeok; Kim, Hanhae; Yang, Sunmo; Kim, Hye Jin; Cho, Ara; Yoon, Sang Sun; Lee, Insuk

    2016-01-01

    Pseudomonas aeruginosa is a Gram-negative bacterium of clinical significance. Although the genome of PAO1, a prototype strain of P. aeruginosa, has been extensively studied, approximately one-third of the functional genome remains unknown. With the emergence of antibiotic-resistant strains of P. aeruginosa, there is an urgent need to develop novel antibiotic and anti-virulence strategies, which may be facilitated by an approach that explores P. aeruginosa gene function in systems-level models. Here, we present a genome-wide functional network of P. aeruginosa genes, PseudomonasNet, which covers 98% of the coding genome, and a companion web server to generate functional hypotheses using various network-search algorithms. We demonstrate that PseudomonasNet-assisted predictions can effectively identify novel genes involved in virulence and antibiotic resistance. Moreover, an antibiotic-resistance network based on PseudomonasNet reveals that P. aeruginosa has common modular genetic organisations that confer increased or decreased resistance to diverse antibiotics, which accounts for the pervasiveness of cross-resistance across multiple drugs. The same network also suggests that P. aeruginosa has developed mechanism of trade-off in resistance across drugs by altering genetic interactions. Taken together, these results clearly demonstrate the usefulness of a genome-scale functional network to investigate pathogenic systems in P. aeruginosa. PMID:27194047

  15. Draft Genome Sequence of Pseudomonas aeruginosa Strain RB, a Bacterium Capable of Synthesizing Cadmium Selenide Nanoparticles.

    PubMed

    Ayano, Hiroyuki; Kuroda, Masashi; Soda, Satoshi; Ike, Michihiko

    2014-05-15

    Pseudomonas aeruginosa strain RB is a bacterium capable of synthesizing cadmium selenide (CdSe) nanoparticles and was isolated from a soil sample. Here, we present the draft genome sequence of P. aeruginosa strain RB. To the best of our knowledge, this is the first report of a draft genome of a CdSe-synthesizing bacterium.

  16. Plasmid-Determined Resistance to Boron and Chromium Compounds in Pseudomonas aeruginosa

    PubMed Central

    Summers, Anne O.; Jacoby, George A.

    1978-01-01

    Plasmids determining resistance to arsenic, mercury, silver, and tellurium compounds in Escherichia coli and Pseudomonas aeruginosa were tested for resistance to 40 other metal compounds. Resistance to trivalent boron and hexavalent chromium compounds was a property of certain P. aeruginosa plasmids. PMID:96730

  17. Role of the Pseudomonas quinolone signal (PQS) in sensitising Pseudomonas aeruginosa to UVA radiation.

    PubMed

    Pezzoni, Magdalena; Meichtry, Martín; Pizarro, Ramón A; Costa, Cristina S

    2015-01-01

    One of the main stress factors that bacteria face in the environment is solar ultraviolet-A (UVA) radiation, which leads to lethal effects through oxidative damage. The aim of this work was to investigate the role of 2-heptyl-3-hydroxi-4-quinolone (the Pseudomonas quinolone signal or PQS) in the response of Pseudomonas aeruginosa to UVA radiation. PQS is an intercellular quorum sensing signal associated to membrane vesicles which, among other functions, regulates genes related to iron acquisition, forms stable complexes with iron and participates in oxidative phenomena. UVA exposure of the wild-type PAO1 strain and a pqsA mutant unable to produce PQS revealed a sensitising role for this signal. Research into the mechanism involved in this phenomenon revealed that catalase, an essential factor in the UVA defence, is not related to PQS-mediated UVA sensitivity. Absorption of UVA by PQS produced its own photo-degradation, oxidation of the probe 2',7'- dichlorodihydrofluorescein and generation of singlet oxygen and superoxide anion, suggesting that this signal could be acting as an endogenous photosensitiser. The results presented in this study could explain the high sensitivity to UVA of P. aeruginosa when compared to enteric bacteria.

  18. Secretion of Pseudomonas aeruginosa Type III Cytotoxins is Dependent on Pseudomonas Quinolone Signal Concentration

    PubMed Central

    Singh, G.; Wu, B.; Baek, M.S.; Camargo, A.; Nguyen, A.; Slusher, N.A.; Srinivasan, R.; Wiener-Kronish, J.P.; Lynch, S.V.

    2010-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen that can, like other bacterial species, exist in antimicrobial resistant sessile biofilms and as free-swimming, planktonic cells. Specific virulence factors are typically associated with each lifestyle and several two-component response regulators have been shown to reciprocally regulate transition between biofilm-associated chronic, and free-swimming acute infections. Quorum sensing (QS) signal molecules belonging to the las and rhl systems are known to regulate virulence gene expression by P. aeruginosa. However the impact of a recently described family of novel quorum sensing signals produced by the Pseudomonas Quinolone Signal (PQS) biosynthetic pathway, on the transition between these modes of infection is less clear. Using clonal isolates from a patient developing ventilator-associated pneumonia, we demonstrated that clinical observations were mirrored by an in vitro temporal shift in isolate phenotype from a non-secreting, to a Type III cytotoxin secreting (TTSS) phenotype and further, that this phenotypic change was PQS-dependent. While intracellular type III cytotoxin levels were unaffected by PQS concentration, cytotoxin secretion was dependent on this signal molecule. Elevated PQS concentrations were associated with inhibition of cytotoxin secretion coincident with expression of virulence factors such as elastase and pyoverdin. In contrast, low concentrations or the inability to biosynthesize PQS resulted in a reversal of this phenotype. These data suggest that expression of specific P. aeruginosa virulence factors appears to be reciprocally regulated and that an additional level of PQS-dependent posttranslational control, specifically governing type III cytotoxin secretion, exists in this species. PMID:20570614

  19. Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

    PubMed Central

    Merrett, Neil D.

    2014-01-01

    Silver in its ionic form (Ag+), but not the bulk metal (Ag0), is toxic to microbial life forms and has been used for many years in the treatment of wound infections. The prevalence of bacterial resistance to silver is considered low due to the nonspecific nature of its toxicity. However, the recent increased use of silver as an antimicrobial agent for medical, consumer, and industrial products has raised concern that widespread silver resistance may emerge. Pseudomonas aeruginosa is a common pathogen that produces pyocyanin, a redox toxin and a reductant for molecular oxygen and ferric (Fe3+) ions. The objective of this study was to determine whether pyocyanin reduces Ag+ to Ag0, which may contribute to silver resistance due to lower bioavailability of the cation. Using surface plasmon resonance spectroscopy and scanning electron microscopy, pyocyanin was confirmed to be a reductant for Ag+, forming Ag0 nanoparticles and reducing the bioavailability of free Ag+ by >95% within minutes. Similarly, a pyocyanin-producing strain of P. aeruginosa (PA14) reduced Ag+ but not a pyocyanin-deficient (ΔphzM) strain of the bacterium. Challenge of each strain with Ag+ (as AgNO3) gave MICs of 20 and 5 μg/ml for the PA14 and ΔphzM strains, respectively. Removal of pyocyanin from the medium strain PA14 was grown in or its addition to the medium that ΔphzM mutant was grown in gave MICs of 5 and 20 μg/ml, respectively. Clinical isolates demonstrated similar pyocyanin-dependent resistance to Ag+. We conclude that pseudomonal silver resistance exists independently of previously recognized intracellular mechanisms and may be more prevalent than previously considered. PMID:25001302

  20. Sequences and expression of pyruvate dehydrogenase genes from Pseudomonas aeruginosa.

    PubMed Central

    Rae, J L; Cutfield, J F; Lamont, I L

    1997-01-01

    A mutant of Pseudomonas aeruginosa, OT2100, which appeared to be defective in the production of the fluorescent yellow-green siderophore pyoverdine had been isolated previously following transposon mutagenesis (T. R. Merriman and I. L. Lamont, Gene 126:17-23, 1993). DNA from either side of the transposon insertion site was cloned, and the sequence was determined. The mutated gene had strong identity with the dihydrolipoamide acetyltransferase (E2) components of pyruvate dehydrogenase (PDH) from other bacterial species. Enzyme assays revealed that the mutant was defective in the E2 subunit of PDH, preventing assembly of a functional complex. PDH activity in OT2100 cell extracts was restored when extract from an E1 mutant was added. On the basis of this evidence, OT2100 was identified as an aceB or E2 mutant. A second gene, aceA, which is likely to encode the E1 component of PDH, was identified upstream from aceB. Transcriptional analysis revealed that aceA and aceB are expressed as a 5-kb polycistronic transcript from a promoter upstream of aceA. An intergenic region of 146 bp was located between aceA and aceB, and a 2-kb aceB transcript that originated from a promoter in the intergenic region was identified. DNA fragments upstream of aceA and aceB were shown to have promoter activities in P. aeruginosa, although only the aceA promoter was active in Escherichia coli. It is likely that the apparent pyoverdine-deficient phenotype of mutant OT2100 is a consequence of acidification of the growth medium due to accumulation of pyruvic acid in the absence of functional PDH. PMID:9171401

  1. Fructooligosacharides Reduce Pseudomonas aeruginosa PAO1 Pathogenicity through Distinct Mechanisms

    PubMed Central

    Ortega-González, Mercedes; Sánchez de Medina, Fermín; Molina-Santiago, Carlos; López-Posadas, Rocío; Pacheco, Daniel; Krell, Tino; Martínez-Augustin, Olga; Abdelali, Daddaoua

    2014-01-01

    Pseudomonas aeruginosa is ubiquitously present in the environment and acts as an opportunistic pathogen on humans, animals and plants. We report here the effects of the prebiotic polysaccharide inulin and its hydrolysed form FOS on this bacterium. FOS was found to inhibit bacterial growth of strain PAO1, while inulin did not affect growth rate or yield in a significant manner. Inulin stimulated biofilm formation, whereas a dramatic reduction of the biofilm formation was observed in the presence of FOS. Similar opposing effects were observed for bacterial motility, where FOS inhibited the swarming and twitching behaviour whereas inulin caused its stimulation. In co-cultures with eukaryotic cells (macrophages) FOS and, to a lesser extent, inulin reduced the secretion of the inflammatory cytokines IL-6, IL-10 and TNF-α. Western blot experiments indicated that the effects mediated by FOS in macrophages are associated with a decreased activation of the NF-κB pathway. Since FOS and inulin stimulate pathway activation in the absence of bacteria, the FOS mediated effect is likely to be of indirect nature, such as via a reduction of bacterial virulence. Further, this modulatory effect is observed also with the highly virulent ptxS mutated strain. Co-culture experiments of P. aeruginosa with IEC18 eukaryotic cells showed that FOS reduces the concentration of the major virulence factor, exotoxin A, suggesting that this is a possible mechanism for the reduction of pathogenicity. The potential of these compounds as components of antibacterial and anti-inflammatory cocktails is discussed. PMID:24465697

  2. Biological Markers of Pseudomonas aeruginosa Epidemic High-Risk Clones

    PubMed Central

    Mulet, Xavier; Cabot, Gabriel; Ocampo-Sosa, Alain A.; Domínguez, M. Angeles; Zamorano, Laura; Juan, Carlos; Tubau, Fe; Rodríguez, Cristina; Moyà, Bartolomé; Peña, Carmen; Martínez-Martínez, Luis

    2013-01-01

    A limited number of Pseudomonas aeruginosa genotypes (mainly ST-111, ST-175, and ST-235), known as high-risk clones, are responsible for epidemics of nosocomial infections by multidrug-resistant (MDR) or extensively drug-resistant (XDR) strains worldwide. We explored the potential biological parameters that may explain the success of these clones. A total of 20 isolates from each of 4 resistance groups (XDR, MDR, ModR [resistant to 1 or 2 classes], and MultiS [susceptible to all antipseudomonals]), recovered from a multicenter study of P. aeruginosa bloodstream infections performed in 10 Spanish hospitals, were analyzed. A further set of 20 XDR isolates belonging to epidemic high-risk clones (ST-175 [n = 6], ST-111 [n = 7], and ST-235 [n = 7]) recovered from different geographical locations was also studied. When unknown, genotypes were documented through multilocus sequence typing. The biological parameters evaluated included twitching, swimming, and swarming motility, biofilm formation, production of pyoverdine and pyocyanin, spontaneous mutant frequencies, and the in vitro competition index (CI) obtained with a flow cytometry assay. All 20 (100%) XDR, 8 (40%) MDR, and 1 (5%) ModR bloodstream isolate from the multicenter study belonged to high-risk clones. No significant differences were observed between clonally diverse ModR and MultiS isolates for any of the parameters. In contrast, MDR/XDR high-risk clones showed significantly increased biofilm formation and mutant frequencies but significantly reduced motility (twitching, swimming, and swarming), production of pyoverdine and pyocyanin, and fitness. The defined biological markers of high-risk clones, which resemble those resulting from adaptation to chronic infections, could be useful for the design of specific treatment and infection control strategies. PMID:23979744

  3. Crystal structure of the flavoenzyme PA4991 from Pseudomonas aeruginosa

    SciTech Connect

    Jacewicz, Agata; Schnell, Robert; Lindqvist, Ylva; Schneider, Gunter

    2016-01-22

    PA4991 is a FAD-dependent oxidoreductase from the pathogen P. aeruginosa that is essential for virulence and survival in the infected host. The structure of this enzyme, determined to 2.4 Å resolution, reveals that PA4991 belongs to the GR{sub 2} family of flavoenzymes. The locus PA4991 in Pseudomonas aeruginosa encodes an open reading frame that has been identified as essential for the virulence and/or survival of this pathogenic organism in the infected host. Here, it is shown that this gene encodes a monomeric FAD-binding protein of molecular mass 42.2 kDa. The structure of PA4991 was determined by a combination of molecular replacement using a search model generated with Rosetta and phase improvement by a low-occupancy heavy-metal derivative. PA4991 belongs to the GR{sub 2} family of FAD-dependent oxidoreductases, comprising an FAD-binding domain typical of the glutathione reductase family and a second domain dominated by an eight-stranded mixed β-sheet. Most of the protein–FAD interactions are via the FAD-binding domain, but the isoalloxazine ring is located at the domain interface and interacts with residues from both domains. A comparison with the structurally related glycine oxidase and glycerol-3-phosphate dehydrogenase shows that in spite of very low amino-acid sequence identity (<18%) several active-site residues involved in substrate binding in these enzymes are conserved in PA4991. However, enzymatic assays show that PA4991 does not display amino-acid oxidase or glycerol-3-phosphate dehydrogenase activities, suggesting that it requires different substrates for activity.

  4. Structural Characterization of Novel Pseudomonas aeruginosa Type IV Pilins

    SciTech Connect

    Nguyen, Y.; Jackson, S; Aidoo, F; Junop, M; Burrows, L

    2010-01-01

    Pseudomonas aeruginosa type IV pili, composed of PilA subunits, are used for attachment and twitching motility on surfaces. P. aeruginosa strains express one of five phylogenetically distinct PilA proteins, four of which are associated with accessory proteins that are involved either in pilin posttranslational modification or in modulation of pilus retraction dynamics. Full understanding of pilin diversity is crucial for the development of a broadly protective pilus-based vaccine. Here, we report the 1.6-{angstrom} X-ray crystal structure of an N-terminally truncated form of the novel PilA from strain Pa110594 (group V), which represents the first non-group II pilin structure solved. Although it maintains the typical T4a pilin fold, with a long N-terminal {alpha}-helix and four-stranded antiparallel {beta}-sheet connected to the C-terminus by a disulfide-bonded loop, the presence of an extra helix in the {alpha}{beta}-loop and a disulfide-bonded loop with helical character gives the structure T4b pilin characteristics. Despite the presence of T4b features, the structure of PilA from strain Pa110594 is most similar to the Neisseria gonorrhoeae pilin and is also predicted to assemble into a fiber similar to the GC pilus, based on our comparative pilus modeling. Interactions between surface-exposed areas of the pilin are suggested to contribute to pilus fiber stability. The non-synonymous sequence changes between group III and V pilins are clustered in the same surface-exposed areas, possibly having an effect on accessory protein interactions. However, based on our high-confidence model of group III PilA{sub PA14}, compensatory changes allow for maintenance of a similar shape.

  5. Protein Network of the Pseudomonas aeruginosa Denitrification Apparatus

    PubMed Central

    Borrero-de Acuña, José Manuel; Rohde, Manfred; Wissing, Josef; Jänsch, Lothar; Schobert, Max; Molinari, Gabriella; Timmis, Kenneth N.

    2016-01-01

    ABSTRACT Oxidative phosphorylation using multiple-component, membrane-associated protein complexes is the most effective way for a cell to generate energy. Here, we systematically investigated the multiple protein-protein interactions of the denitrification apparatus of the pathogenic bacterium Pseudomonas aeruginosa. During denitrification, nitrate (Nar), nitrite (Nir), nitric oxide (Nor), and nitrous oxide (Nos) reductases catalyze the reaction cascade of NO3− → NO2− → NO → N2O → N2. Genetic experiments suggested that the nitric oxide reductase NorBC and the regulatory protein NosR are the nucleus of the denitrification protein network. We utilized membrane interactomics in combination with electron microscopy colocalization studies to elucidate the corresponding protein-protein interactions. The integral membrane proteins NorC, NorB, and NosR form the core assembly platform that binds the nitrate reductase NarGHI and the periplasmic nitrite reductase NirS via its maturation factor NirF. The periplasmic nitrous oxide reductase NosZ is linked via NosR. The nitrate transporter NarK2, the nitrate regulatory system NarXL, various nitrite reductase maturation proteins, NirEJMNQ, and the Nos assembly lipoproteins NosFL were also found to be attached. A number of proteins associated with energy generation, including electron-donating dehydrogenases, the complete ATP synthase, almost all enzymes of the tricarboxylic acid (TCA) cycle, and the Sec system of protein transport, among many other proteins, were found to interact with the denitrification proteins. This deduced nitrate respirasome is presumably only one part of an extensive cytoplasmic membrane-anchored protein network connecting cytoplasmic, inner membrane, and periplasmic proteins to mediate key activities occurring at the barrier/interface between the cytoplasm and the external environment. IMPORTANCE The processes of cellular energy generation are catalyzed by large multiprotein enzyme complexes

  6. Bioavailability of Iron to Pseudomonas fluorescens Strain A506 on Flowers of Pear and Apple.

    PubMed

    Temple, Todd N; Stockwell, Virginia O; Loper, Joyce E; Johnson, Kenneth B

    2004-12-01

    ABSTRACT The addition of 0.1 mM FeCl(3) to a defined culture medium induces the bacterial epiphyte Pseudomonas fluorescens strain A506 (A506) to produce an antibiotic toxic to the fire blight pathogen, Erwinia amylovora. Consequently, because A506 is registered and applied as a commercial product to suppress E. amylovora before floral infection of pear and apple, the relative availability of iron to A506 on surfaces of pear and apple flowers is of potential significance. An 'iron biosensor' construct of A506 was developed by transformation with an iron-regulated promoter (pvd) fused to a promoterless ice nucleation reporter gene (inaZ). This construct, A506 (pvd-inaZ), established high populations on pear and apple flowers, ranging from 10(4) to 10(6) CFU/flower. In seven trials on pear and apple trees, A506 (pvd-inaZ) expressed high ice nucleation activity (INA) on flowers, indicating limited iron bioavailability or a low-iron environment unlikely to induce antibiotic production by A506. A506 (pvd-inaZ) also colonized flowers when mixed with chemicals containing iron: FeSO(4) or the iron chelates ferric ethylenediaminedi-(o-hydroxyphenyl-acetic) acid (FeEDDHA) and ferric diethylenetriamine pentaacetate (FeDTPA). These compounds represent an array of commercial iron formulations applied to foliage to avert iron chlorosis. Treatment of flowers with a mixture of A506 (pvd-inaZ) and 3 mM FeEDDHA or FeDTPA significantly decreased INA compared with flowers treated with A506 (pvd-inaZ) in water. Lower concentrations (0.3 mM) of FeEDDHA, however, did not consistently suppress INA. These results indicate that apple and pear flowers represent an iron-limited environment to A506 and that treatment with 3 mM FeEDDHA is needed to increase significantly the level of iron available to this bacterium.

  7. Physiological and Morphological Changes Induced by Nutrient Limitation of Pseudomonas fluorescens 378 in Continuous Culture

    PubMed Central

    Persson, Anders; Molin, Göran; Weibull, Claes

    1990-01-01

    Pseudomonas fluorescens 378 was studied in continuous culture at a dilution rate of 0.05 or 0.15 h−1 and under a limitation of carbon/energy, nitrogen, phosphorus, iron(III), or oxygen. Cultures were examined for nutritional consumption, production of biosurfactant AP-6 and lipase, and electron microscopy morphology. Morphological features were lysis and plasmolysis of the cells, vacuoles in the cells, granules in cell nuclei, and DNA coagulation during transmission electron microscopy preparation. Biosurfactant and lipase production were lost after 8 to 15 retention times, but under iron limitation and at low dilution rate they were maintained for more than 30 retention times. Consumption of nutrients varied between different cultures. Between 2.4 and 6.0 g of succinic acid per g (dry weight) was consumed; the highest value was obtained under phosphorus limitation. The uptake of nitrogen was mostly about 0.16 g/g (dry weight), and that of phosphorus varied between 13 and 58 mg/g (dry weight). Phosphorus-limited cells reduced their phosphorus consumption by at least 50% compared with other limitations. Cell morphology varied among different cultures. Up to 25% cell lysis occurred at the higher dilution rate. The frequencies of plasmolysis varied between 0 and 85%. Granules in nuclei were found in 65 to 100% of the cells. Vacuoles appeared mostly in low numbers, but at the lower dilution rate under phosphorus or iron limitation the frequencies increased to between 25 and 85%. At high dilution rate, the DNA coagulated in 30 to 70% of the cells. Multivariate data analysis demonstrated a general difference between the two tested dilution rates; i.e., both nutritional and morphological features differed more between the two tested dilution rates than between the different limitations. Cultures at the lower dilution rate changed more with time; this was especially pronounced for phosphorus or iron limitation. The data analysis also showed a correlation between

  8. Detection of extended spectrum beta lactamases, ampc beta lactamases and metallobetalactamases in clinical isolates of ceftazidime resistant Pseudomonas Aeruginosa.

    PubMed

    Umadevi, Sivaraman; Joseph, Noyal M; Kumari, Kandha; Easow, Joshy M; Kumar, Shailesh; Stephen, Selvaraj; Srirangaraj, Sreenivasan; Raj, Sruthi

    2011-10-01

    We studied the prevalence of ceftazidime resistance in Pseudomonas aeruginosa and the rates of extended-spectrum β-lactamase (ESBL), AmpC β-lactamase (AmpC) and metallo-β-lactamase (MBL) production among the ceftazidime resistant Pseudomonas aeruginosa. A very high rate of MBL production was observed, which suggested it to be an important contributing factor for ceftazidime resistance among Pseudomonas aeruginosa.

  9. Pseudomonas aeruginosa outbreak in a pediatric oncology care unit caused by an errant water jet into contaminated siphons.

    PubMed

    Schneider, Henriette; Geginat, Gernot; Hogardt, Michael; Kramer, Alexandra; Dürken, Matthias; Schroten, Horst; Tenenbaum, Tobias

    2012-06-01

    We analyzed an outbreak of invasive infections with an exotoxin U positive Pseudomonas aeruginosa strain within a pediatric oncology care unit. Environmental sampling and molecular characterization of the Pseudomonas aeruginosa strains led to identification of the outbreak source. An errant water jet into the sink within patient rooms was observed. Optimized outbreak management resulted in an abundance of further Pseudomonas aeruginosa infections within the pediatric oncology care unit.

  10. Draft Genome Sequences of Pseudomonas fluorescens Strains SF39a and SF4c, Potential Plant Growth Promotion and Biocontrol Agents

    PubMed Central

    Ly, Lindsey K.; Underwood, Grace E.; McCully, Lucy M.; Bitzer, Adam S.; Godino, Agustina; Bucci, Vanni; Brigham, Christopher J.; Príncipe, Analía; Fischer, Sonia E.

    2015-01-01

    Pseudomonas fluorescens SF4c and SF39a, strains isolated from wheat rhizosphere, have potential applications in plant growth promotion and biocontrol of fungal diseases of crop plants. We report the draft genome sequences of SF4c and SF39a with estimated sizes of 6.5 Mb and 5.9 Mb, respectively. PMID:25814613

  11. Draft Genome Sequence of the Beneficial Rhizobacterium Pseudomonas fluorescens DSM 8569, a Natural Isolate of Oilseed Rape (Brassica napus)

    PubMed Central

    Nesemann, Kai; Braus-Stromeyer, Susanna A.; Thuermer, Andrea; Daniel, Rolf

    2015-01-01

    Pseudomonas fluorescens DSM 8569 represents a natural isolate of the rhizosphere of oilseed rape (Brassica napus) in Germany and possesses antagonistic potential toward the fungal pathogen Verticillium. We report here the draft genome sequence of strain DSM 8569, which comprises 5,914 protein-coding sequences. PMID:25814596

  12. The Rsm regulon of plant growth-promoting Pseudomonas fluorescens SS101: role of small RNAs in regulation of lipopeptide biosynthesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rhizobacterium Pseudomonas fluorescens SS101 inhibits growth of oomycete and fungal pathogens, and induces resistance in plants against pathogens and insects. To unravel regulatory pathways of secondary metabolite production in SS101, we conducted a genome-wide search for sRNAs and performed tra...

  13. Negative regulation of Germination-Arrest Factor (GAF) production in Pseudomonas fluorescens WH6 by a putative extracytoplasmic function sigma factor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens WH6 secretes a Germination-Arrest Factor (GAF) that we have previously identified as 4-formylaminooxyvinylglycine. GAF irreversibly inhibits germination of the seeds of numerous grassy weed species and selectively inhibits growth of the bacterial plant pathogen Erwinia amylo...

  14. Control of fire blight by Pseudomonas fluorescens A506 and Pantoea vagans C9-1 applied as single strains and mixed inocula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in ten field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to b...

  15. Functional analysis of a biosynthetic cluster essential for production of 4-formylaminooxyvinylglycine, a germination-arrest factor from Pseudomonas fluorescens WH6

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizosphere-associated Pseudomonas fluorescens WH6 produces the germination-arrest factor, 4-formylaminooxyvinylglycine (FVG). FVG has previously been shown to both arrest the germination of weedy grasses and to inhibit the growth of the bacterial plant pathogen Erwinia amylovora. Very little is kno...

  16. The effects of glutaraldehyde on the control of single and dual biofilms of Bacillus cereus and Pseudomonas fluorescens.

    PubMed

    Simões, Lucia C; Lemos, Madalena; Araújo, Paula; Pereira, Ana Margarida; Simões, Manuel

    2011-03-01

    Glutaraldehyde (GLUT) was evaluated for control of single and dual species biofilms of Bacillus cereus and Pseudomonas fluorescens on stainless steel surfaces using a chemostat system. The biofilms were characterized in terms of mass, cell density, total and matrix proteins and polysaccharides. The control action of GLUT was assessed in terms of inactivation and removal of biofilm. Post-biocide action was characterized 3, 7, 12, 24, 48 and 72 h after treatment. Tests with planktonic cells were also performed for comparison. The results demonstrated that in dual species biofilms the metabolic activity, cell density and the content of matrix proteins were higher than those of either single species. Planktonic B. cereus was more susceptible to GLUT than P. fluorescens. The biocide susceptibility of dual species planktonic cultures was an average of each single species. Planktonic cells were more susceptible to GLUT than their biofilm counterparts. Biofilm inactivation was similar for both of the single biofilms while dual biofilms were more resistant than single species biofilms. GLUT at 200 mg l(-1) caused low biofilm removal (<10%). Analysis of the post-biocide treatment data revealed the ability of biofilms to recover their activity over time. However, 12 h after biocide application, sloughing events were detected for both single and dual species biofilms, but were more marked for those formed by P. fluorescens (removal >40% of the total biofilm). The overall results suggest that GLUT exerts significant antimicrobial activity against planktonic bacteria and a partial and reversible activity against B. cereus and P. fluorescens single and dual species biofilms. The biocide had low antifouling effects when analysed immediately after treatment. However, GLUT had significant long-term effects on biofilm removal, inducing significant sloughing events (recovery in terms of mass 72 h after treatment for single biofilms and 42 h later for dual biofilms). In general, dual

  17. Ginger extract inhibits biofilm formation by Pseudomonas aeruginosa PA14.

    PubMed

    Kim, Han-Shin; Park, Hee-Deung

    2013-01-01

    Bacterial biofilm formation can cause serious problems in clinical and industrial settings, which drives the development or screening of biofilm inhibitors. Some biofilm inhibitors have been screened from natural products or modified from natural compounds. Ginger has been used as a medicinal herb to treat infectious diseases for thousands of years, which leads to the hypothesis that it may contain chemicals inhibiting biofilm formation. To test this hypothesis, we evaluated ginger's ability to inhibit Pseudomonas aeruginosa PA14 biofilm formation. A static biofilm assay demonstrated that biofilm development was reduced by 39-56% when ginger extract was added to the culture. In addition, various phenotypes were altered after ginger addition of PA14. Ginger extract decreased production of extracellular polymeric substances. This finding was confirmed by chemical analysis and confocal laser scanning microscopy. Furthermore, ginger extract formed noticeably less rugose colonies on agar plates containing Congo red and facilitated swarming motility on soft agar plates. The inhibition of biofilm formation and the altered phenotypes appear to be linked to a reduced level of a second messenger, bis-(3'-5')-cyclic dimeric guanosine monophosphate. Importantly, ginger extract inhibited biofilm formation in both Gram-positive and Gram-negative bacteria. Also, surface biofilm cells formed with ginger extract detached more easily with surfactant than did those without ginger extract. Taken together, these findings provide a foundation for the possible discovery of a broad spectrum biofilm inhibitor.

  18. Prevention of Pseudomonas aeruginosa adhesion by electric currents.

    PubMed

    Shim, Soojin; Hong, Seok Hoon; Tak, Yongsug; Yoon, Jeyong

    2011-02-01

    The process of controlling bacterial adhesion using an electric current deserves attention because of its ease of automation and environmentally friendly nature. This study investigated the role of electric currents (negative, positive, alternating) for preventing adhesion of Pseudomonas aeruginosa and achieving bacterial inactivation. Indium tin oxide (ITO) film was used as a working electrode to observe adhesion and inactivation under electric polarization. Electric current types were classified into negative, positive, and alternating current. The working electrode acted as a cathode or anode by applying a negative or positive current, and an alternating current indicates that the negative current was combined sequentially with the positive current. The numbers of adhered cells were compared under a flow condition, and the in situ behavior of the bacterial cells and the extent of their inactivation were also investigated using time-lapse recording and live/dead staining, respectively. The application of a negative current prevented bacterial adhesion significantly (∼81% at 15.0 μA cm(-2)). The positive current did not significantly inhibit adhesion (<20% at 15.0 μA cm(-2)), compared to the nonpolarized case. The alternating current had a similar effect as the negative current on preventing bacterial adhesion, but it also exhibited bactericidal effects, making it the most suitable method for bacterial adhesion control.

  19. PA0148 from Pseudomonas aeruginosa Catalyzes the Deamination of Adenine

    SciTech Connect

    Goble, A.M.; Swaminathan, S.; Zhang, Z.; Sauder, J. M.; Burley, S. K.; Raushel, F. M.

    2011-08-02

    Four proteins from NCBI cog1816, previously annotated as adenosine deaminases, have been subjected to structural and functional characterization. Pa0148 (Pseudomonas aeruginosa PAO1), AAur1117 (Arthrobacter aurescens TC1), Sgx9403e, and Sgx9403g have been purified and their substrate profiles determined. Adenosine is not a substrate for any of these enzymes. All of these proteins will deaminate adenine to produce hypoxanthine with k{sub cat}/K{sub m} values that exceed 10{sup 5} M{sup -1} s{sup -1}. These enzymes will also accept 6-chloropurine, 6-methoxypurine, N-6-methyladenine, and 2,6-diaminopurine as alternate substrates. X-ray structures of Pa0148 and AAur1117 have been determined and reveal nearly identical distorted ({beta}/{alpha}){sub 8} barrels with a single zinc ion that is characteristic of members of the amidohydrolase superfamily. Structures of Pa0148 with adenine, 6-chloropurine, and hypoxanthine were also determined, thereby permitting identification of the residues responsible for coordinating the substrate and product.

  20. Pa0148 from Pseudomonas aeruginosa Catalyzes the Deamination of Adenine

    SciTech Connect

    A Goble; Z Zhang; J Sauder; S Burley; S Swaminathan; F Raushel

    2011-12-31

    Four proteins from NCBI cog1816, previously annotated as adenosine deaminases, have been subjected to structural and functional characterization. Pa0148 (Pseudomonas aeruginosa PAO1), AAur1117 (Arthrobacter aurescens TC1), Sgx9403e, and Sgx9403g have been purified and their substrate profiles determined. Adenosine is not a substrate for any of these enzymes. All of these proteins will deaminate adenine to produce hypoxanthine with k{sub cat}/K{sub m} values that exceed 10{sup 5} M{sup -1} s{sup -1}. These enzymes will also accept 6-chloropurine, 6-methoxypurine, N-6-methyladenine, and 2,6-diaminopurine as alternate substrates. X-ray structures of Pa0148 and AAur1117 have been determined and reveal nearly identical distorted ({beta}/{alpha}){sub 8} barrels with a single zinc ion that is characteristic of members of the amidohydrolase superfamily. Structures of Pa0148 with adenine, 6-chloropurine, and hypoxanthine were also determined, thereby permitting identification of the residues responsible for coordinating the substrate and product.

  1. Uranyl Precipitation by Pseudomonas aeruginosa via Controlled Polyphosphate Metabolism

    PubMed Central

    Renninger, Neil; Knopp, Roger; Nitsche, Heino; Clark, Douglas S.; Keasling, Jay D.

    2004-01-01

    The polyphosphate kinase gene from Pseudomonas aeruginosa was overexpressed in its native host, resulting in the accumulation of 100 times the polyphosphate seen with control strains. Degradation of this polyphosphate was induced by carbon starvation conditions, resulting in phosphate release into the medium. The mechanism of polyphosphate degradation is not clearly understood, but it appears to be associated with glycogen degradation. Upon suspension of the cells in 1 mM uranyl nitrate, nearly all polyphosphate that had accumulated was degraded within 48 h, resulting in the removal of nearly 80% of the uranyl ion and >95% of lesser-concentrated solutions. Electron microscopy, energy-dispersive X-ray spectroscopy, and time-resolved laser-induced fluorescence spectroscopy (TRLFS) suggest that this removal was due to the precipitation of uranyl phosphate at the cell membrane. TRLFS also indicated that uranyl was initially sorbed to the cell as uranyl hydroxide and was then precipitated as uranyl phosphate as phosphate was released from the cell. Lethal doses of radiation did not halt phosphate secretion from polyphosphate-filled cells under carbon starvation conditions. PMID:15574942

  2. Paraffin Oxidation in Pseudomonas aeruginosa I. Induction of Paraffin Oxidation

    PubMed Central

    van Eyk, J.; Bartels, Trude J.

    1968-01-01

    The induction of paraffin oxidation in intact cells of Pseudomonas aeruginosa was investigated. Oxidation of 14C-heptane by cell-free extracts of adapted cells showed that the activity of whole cells is a reliable reflection of the synthesis of the first enzyme in the degradation of n-alkanes. Induction was significantly affected by glucose and could be completely repressed by malate. The amino acids l-proline, l-alanine, l-arginine, and l-tyrosine exhibited a rather low repressor action. Malonate, a nonrepressive carbon source, allowed gratuitous enzyme synthesis. A number of compounds which did not sustain growth were found to be suitable substitutes for paraffins as an inducer. Among these were cyclopropane and diethoxymethane. The induction studied under conditions of gratuity with the latter compound as an inducer showed immediate linear kinetics only at saturating inducer concentrations. With n-hexane as the inducer, a lag time was always observed, even when high concentrations were used. PMID:4979100

  3. Electron Flow through Nitrotyrosinate in Pseudomonas aeruginosa Azurin

    PubMed Central

    Warren, Jeffrey J.; Herrera, Nadia; Hill, Michael G.; Winkler, Jay R.; Gray, Harry B.

    2013-01-01

    We have designed ruthenium-modified Pseudomonas aeruginosa azurins that incorporate 3-nitrotyrosine (NO2YOH) between Ru(2,2′-bipyridine)2(imidazole)(histidine) and Cu redox centers in electron transfer (ET) pathways. We investigated the structures and reactivities of three different systems: RuH107NO2YOH109, RuH124NO2YOH122, and RuH126NO2YOH122. RuH107NO2YOH109, unlabeled H124NO2YOH122, and unlabeled H126NO2YOH122 were structurally characterized. The pKas of NO2YOH at positions 122 and 109 are 7.2 and 6.0, respectively. Reduction potentials of 3-nitrotyrosinate (NO2YO−)-modified azurins were estimated from cyclic and differential pulse voltammetry data: oxidation of NO2YO−122 occurs near 1.1 versus NHE; that for NO2YO−109 is near 1.2 V. Our analysis of transient optical spectroscopic experiments indicates that hopping via NO2YO− enhances CuI oxidation rates over single-step ET by factors of 32 (RuH107NO2YO−109), 46 (RuH126NO2YO−122), and 13 (RuH124NO2YO−122). PMID:23859602

  4. Biosurfactant Production by Pseudomonas aeruginosa from Renewable Resources.

    PubMed

    Thavasi, R; Subramanyam Nambaru, V R M; Jayalakshmi, S; Balasubramanian, T; Banat, Ibrahim M

    2011-01-01

    This study deals with production and characterization of biosurfactant from renewable resources by Pseudomonas aeruginosa. Biosurfactant production was carried out in 3L fermentor using waste motor lubricant oil and peanut oil cake. Maximum biomass (11.6 mg/ml) and biosurfactant production (8.6 mg/ml) occurred with peanut oil cake at 120 and 132 h respectively. Characterization of the biosurfactant revealed that, it is a lipopeptide with chemical composition of protein (50.2%) and lipid (49.8%). The biosurfactant (1 mg/ml) was able to emulsify waste motor lubricant oil, crude oil, peanut oil, kerosene, diesel, xylene, naphthalene and anthracene, comparatively the emulsification activity was higher than the activity found with Triton X-100 (1 mg/ml). Results obtained in the present study showed the possibility of biosurfactant production using renewable, relatively inexpensive and easily available resources. Emulsification activity found with the biosurfactant against different hydrocarbons showed its possible application in bioremediation of environments polluted with various hydrocarbons.

  5. Variability in Pseudomonas aeruginosa Lipopolysaccharide Expression during Crude Oil Degradation

    PubMed Central

    Norman, R. Sean; Frontera-Suau, Roberto; Morris, Pamela J.

    2002-01-01

    Bacterial utilization of crude oil components, such as the n-alkanes, requires complex cell surface adaptation to allow adherence to oil. To better understand microbial cell surface adaptation to growth on crude oil, the cell surface characteristics of two Pseudomonas aeruginosa strains, U1 and U3, both isolated from the same crude oil-degrading microbial community enriched on Bonny Light crude oil (BLC), were compared. Analysis of growth rates demonstrated an increased lag time for U1 cells compared to U3 cells. Amendment with EDTA inhibited U1 and U3 growth and degradation of the n-alkane component of BLC, suggesting a link between cell surface structure and crude oil degradation. U1 cells demonstrated a smooth-to-rough colony morphology transition when grown on BLC, while U3 cells exhibited rough colony morphology at the outset. Combining high-resolution atomic force microscopy of the cell surface and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of extracted lipopolysaccharides (LPS), we demonstrate that isolates grown on BLC have reduced O-antigen expression compared with that of glucose-grown cells. The loss of O-antigen resulted in shorter LPS molecules, increased cell surface hydrophobicity, and increased n-alkane degradation. PMID:12324360

  6. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

    2015-12-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

  7. Substituted Lactam and Cyclic Azahemiacetals Modulate Pseudomonas aeruginosa Quorum Sensing

    PubMed Central

    Malladi, Venkata L. A.; Sobczak, Adam J.; Maricic, Natalie; Murugapiran, Senthil Kumar; Schneper, Lisa; Makemson, John; Mathee, Kalai; Wnuk, Stanislaw F.

    2011-01-01

    Quorum sensing (QS) is a population-dependent signaling process bacteria use to control multiple processes including virulence that is critical for establishing infection. The most common QS signaling molecule used by Gram-negative bacteria are acylhomoserine lactones. The development of non-native acylhomoserine lactone (AHL) ligands has emerged as a promising new strategy to inhibit QS in Gram-negative bacteria. In this work, we have synthesized a set of optically pure γ-lactams and their reduced cyclic azahemiacetal analogues, bearing the additional alkylthiomethyl substituent, and evaluated their effect on the AHL-dependent Pseudomonas aeruginosa las and rhl QS pathways. The concentration of these ligands and the simple structural modification such as the length of the alkylthio substituent has notable effect on activity. The γ-lactam derivatives with nonylthio or dodecylthio chains acted as inhibitors of las signaling with moderate potency. The cyclic azahemiacetal with shorter propylthio or hexylthio substituent was found to strongly inhibit both las and rhl signaling at higher concentrations while the propylthio analogue strongly stimulated the las QS system at lower concentrations. PMID:21855349

  8. Inhibition of Neisseria gonorrhoeae by a Bacteriocin from Pseudomonas aeruginosa

    PubMed Central

    Morse, Stephen A.; Vaughan, Patrick; Johnson, Deanne; Iglewski, Barbara H.

    1976-01-01

    Supernatants from broth-grown cultures of Pseudomonas aeruginosa PA 103 exhibited bactericidal activity against Neisseria gonorrhoeae. The concentration of the bactericidal substance increased significantly after induction by mitomycin C. Purification was effected by salt fractionation, chromatography on diethylaminoethyl-cellulose, and sedimentation by centrifugation at 100,000 × g for 90 min. Electron microscopy of this purified preparation revealed structures resembling R-type pyocins in both the contracted and uncontracted state. Pyocins in the contracted state were observed in association with the gonococcal cell surface. No loss of bactericidal activity was observed after treatment with proteolytic enzymes. Standard pyocin typing procedures identified the pyocin pattern as 611 131. The bactericidal activity of this pyocin was examined on various species of Neisseria. Out of 56 strains of N. gonorrhoeae from disseminated and nondisseminated infections, all were susceptible to pyocin 611 131. However, only 3 of 20 strains of N. meningitidis and 5 of 16 strains of N. lactamica were susceptible. The bactericidal activity that pyocin 611 131 has for N. gonorrhoeae and other species of Neisseria is significant because it departs from the expected specificity that heretofore has distinguished bacteriocins from most “classical” antibiotics. Images PMID:825024

  9. Transcriptome Profiling of Antimicrobial Resistance in Pseudomonas aeruginosa

    PubMed Central

    Khaledi, Ariane; Schniederjans, Monika; Pohl, Sarah; Rainer, Roman; Bodenhofer, Ulrich; Xia, Boyang; Klawonn, Frank; Bruchmann, Sebastian; Preusse, Matthias; Eckweiler, Denitsa; Dötsch, Andreas

    2016-01-01

    Emerging resistance to antimicrobials and the lack of new antibiotic drug candidates underscore the need for optimization of current diagnostics and therapies to diminish the evolution and spread of multidrug resistance. As the antibiotic resistance status of a bacterial pathogen is defined by its genome, resistance profiling by applying next-generation sequencing (NGS) technologies may in the future accomplish pathogen identification, prompt initiation of targeted individualized treatment, and the implementation of optimized infection control measures. In this study, qualitative RNA sequencing was used to identify key genetic determinants of antibiotic resistance in 135 clinical Pseudomonas aeruginosa isolates from diverse geographic and infection site origins. By applying transcriptome-wide association studies, adaptive variations associated with resistance to the antibiotic classes fluoroquinolones, aminoglycosides, and β-lactams were identified. Besides potential novel biomarkers with a direct correlation to resistance, global patterns of phenotype-associated gene expression and sequence variations were identified by predictive machine learning approaches. Our research serves to establish genotype-based molecular diagnostic tools for the identification of the current resistance profiles of bacterial pathogens and paves the way for faster diagnostics for more efficient, targeted treatment strategies to also mitigate the future potential for resistance evolution. PMID:27216077

  10. Ginger Extract Inhibits Biofilm Formation by Pseudomonas aeruginosa PA14

    PubMed Central

    Kim, Han-Shin; Park, Hee-Deung

    2013-01-01

    Bacterial biofilm formation can cause serious problems in clinical and industrial settings, which drives the development or screening of biofilm inhibitors. Some biofilm inhibitors have been screened from natural products or modified from natural compounds. Ginger has been used as a medicinal herb to treat infectious diseases for thousands of years, which leads to the hypothesis that it may contain chemicals inhibiting biofilm formation. To test this hypothesis, we evaluated ginger’s ability to inhibit Pseudomonas aeruginosa PA14 biofilm formation. A static biofilm assay demonstrated that biofilm development was reduced by 39–56% when ginger extract was added to the culture. In addition, various phenotypes were altered after ginger addition of PA14. Ginger extract decreased production of extracellular polymeric substances. This finding was confirmed by chemical analysis and confocal laser scanning microscopy. Furthermore, ginger extract formed noticeably less rugose colonies on agar plates containing Congo red and facilitated swarming motility on soft agar plates. The inhibition of biofilm formation and the altered phenotypes appear to be linked to a reduced level of a second messenger, bis-(3′-5′)-cyclic dimeric guanosine monophosphate. Importantly, ginger extract inhibited biofilm formation in both Gram-positive and Gram-negative bacteria. Also, surface biofilm cells formed with ginger extract detached more easily with surfactant than did those without ginger extract. Taken together, these findings provide a foundation for the possible discovery of a broad spectrum biofilm inhibitor. PMID:24086697

  11. Crystal structure of Pseudomonas aeruginosa bacteriophytochrome: Photoconversion and signal transduction

    PubMed Central

    Yang, Xiaojing; Kuk, Jane; Moffat, Keith

    2008-01-01

    Phytochromes are red-light photoreceptors that regulate light responses in plants, fungi, and bacteria via reversible photoconversion between red (Pr) and far-red (Pfr) light-absorbing states. Here we report the crystal structure at 2.9 Å resolution of a bacteriophytochrome from Pseudomonas aeruginosa with an intact, fully photoactive photosensory core domain in its dark-adapted Pfr state. This structure reveals how unusual interdomain interactions, including a knot and an “arm” structure near the chromophore site, bring together the PAS (Per-ARNT-Sim), GAF (cGMP phosphodiesterase/adenyl cyclase/FhlA), and PHY (phytochrome) domains to achieve Pr/Pfr photoconversion. The PAS, GAF, and PHY domains have topologic elements in common and may have a single evolutionary origin. We identify key interactions that stabilize the chromophore in the Pfr state and provide structural and mutational evidence to support the essential role of the PHY domain in efficient Pr/Pfr photoconversion. We also identify a pair of conserved residues that may undergo concerted conformational changes during photoconversion. Modeling of the full-length bacteriophytochrome structure, including its output histidine kinase domain, suggests how local structural changes originating in the photosensory domain modulate interactions between long, cross-domain signaling helices at the dimer interface and are transmitted to the spatially distant effector domain, thereby regulating its histidine kinase activity. PMID:18799746

  12. Investigation of ciprofloxacin penetration into Pseudomonas aeruginosa biofilms.

    PubMed Central

    Suci, P A; Mittelman, M W; Yu, F P; Geesey, G G

    1994-01-01

    Bacterial infections associated with indwelling medical devices often demonstrate an intrinsic resistance to antimicrobial therapies. In order to explore the possibility of transport limitation to biofilm bacteria as a contributing factor, the penetration of a fluoroquinolone antibiotic, ciprofloxacin, through Pseudomonas aeruginosa biofilms was investigated. Attenuated total reflection Fourier transform infrared (ATR/FT-IR) spectrometry was employed to monitor bacterial colonization of a germanium substratum, transport of ciprofloxacin to the biofilm-substratum interface, and interaction of biofilm components with the antibiotic in a flowing system. Transport of the antibiotic to the biofilm-substratum interface during the 21-min exposure to 100 micrograms/ml was found to be significantly impeded by the biofilm. Significant changes in IR bands of the biofilm in regions of the spectrum associated with RNA and DNA vibrational modes appeared following exposure to the antibiotic, indicating chemical modification of biofilm components. These results suggest that transport limitations may be an important factor in the antimicrobial resistance of biofilm bacteria and that ATR/FT-IR spectrometry may be used to follow the time course of antimicrobial action in biofilms in situ. Images PMID:7811031

  13. Child abuse followed by fatal systemic Pseudomonas aeruginosa infection.

    PubMed

    Senati, Massimo; Polacco, Matteo; Grassi, Vincenzo M; Carbone, Arnaldo; De-Giorgio, Fabio

    2013-01-01

    Child abuse has become an increasingly serious diagnostic challenge for physicians. The clinical manifestations include malnutrition and sometimes infection. In fact, stress in children has been reported to increase corticosteroid levels. As a consequence, the thymus begins an involution process, producing a severe impairment in cellular and humoral immunity. Here, we report the case of a 7-year-old child who suffered a prolonged history of abuse and died from a systemic Pseudomonas aeruginosa infection. An initial local chronic infection propagated to the pelvic lymph nodes in an immunologically weak body and evolved into abscesses/phlegmons of the pelvic tissue, sepsis, acute respiratory distress syndrome, multiple organ failure and finally, death. Abused children have to be considered as potentially immunologically impaired patients; therefore, it is very important to screen them for opportunistic infections. Moreover, a history of unusual or recurring infections may indicate abuse, especially neglect or malnutrition. In these cases, further investigations should be conducted to determine if a protective service case should be opened. Thus, there is a need for multidisciplinary cooperation to ensure the early identification and prevention of child abuse.

  14. Crystal structure of the flavoenzyme PA4991 from Pseudomonas aeruginosa

    PubMed Central

    Jacewicz, Agata; Schnell, Robert; Lindqvist, Ylva; Schneider, Gunter

    2016-01-01

    The locus PA4991 in Pseudomonas aeruginosa encodes an open reading frame that has been identified as essential for the virulence and/or survival of this pathogenic organism in the infected host. Here, it is shown that this gene encodes a monomeric FAD-binding protein of molecular mass 42.2 kDa. The structure of PA4991 was determined by a combination of molecular replacement using a search model generated with Rosetta and phase improvement by a low-occupancy heavy-metal derivative. PA4991 belongs to the GR2 family of FAD-dependent oxidoreductases, comprising an FAD-binding domain typical of the glutathione reductase family and a second domain dominated by an eight-stranded mixed β-sheet. Most of the protein–FAD interactions are via the FAD-binding domain, but the isoalloxazine ring is located at the domain interface and interacts with residues from both domains. A comparison with the structurally related glycine oxidase and glycerol-3-phosphate dehydrogenase shows that in spite of very low amino-acid sequence identity (<18%) several active-site residues involved in substrate binding in these enzymes are conserved in PA4991. However, enzymatic assays show that PA4991 does not display amino-acid oxidase or glycerol-3-phosphate dehydrogenase activities, suggesting that it requires different substrates for activity. PMID:26841760

  15. Novel polymeric nanoparticles targeting the lipopolysaccharides of Pseudomonas aeruginosa.

    PubMed

    Long, Y; Li, Z; Bi, Q; Deng, C; Chen, Z; Bhattachayya, S; Li, C

    2016-04-11

    Considering outburst of various infectious diseases globally, nanoparticle assisted targeted drug delivery has emerged as a promising strategy that can enhance the therapeutic efficacy and minimize the undesirable side effects of an antimicrobial agents. Molecular imprinting is a newly developed strategy that can synthesize a drug carrier with highly stable ligand-like 'cavity', may serve as a new platform of ligand-free targeted drug delivery systems. In this study, we use the amphiphilic lipopolysaccharides, derived from Pseudomonas aeruginosa as imprinting template and obtained an evenly distributed sub-40 nm polymeric nanoparticles by using inverse emulsion method. These molecularly imprinted nanoparticles (MIPNPs) showed specific binding to the lipopolysaccharide as determined by fluorescence polarization and microscale thermophoresis. MIPNPs showed selective recognition of target bacteria as detected by flow cytometry. Additionally, MIPNPs exhibited the in vivo targeting capabilities in both the keratitis model and meningitis model. Moreover, the photosensitizer methylene blue-loaded MIPNPs presented significantly strong inhibition of bacterial Growth, compared to non-imprinted controls for in vitro model of the photodynamic therapy. Our study shows an attempt to design a magic bullet by molecular imprinting that may provide a novel approach to generate synthetic carrier for targeting pathogen and treatment for a variety of infectious human diseases.

  16. Catalytic mechanism of the arylsulfatase promiscuous enzyme from Pseudomonas aeruginosa.

    PubMed

    Marino, Tiziana; Russo, Nino; Toscano, Marirosa

    2013-02-04

    To elucidate the working mechanism of the "broad substrate specificity" by the Pseudomonas aeruginosa aryl sulfatase (PAS) enzyme, we present here a full quantum chemical study performed at the density functional level. This enzyme is able to catalyze the hydrolysis of the original p-nitrophenyl-sulfate (PNPS) substrate and the promiscuous p-nitrophenyl-phosphate (PNPP) one with comparable reaction kinetics. Based on the obtained results, a multistep mechanism including activation of the nucleophile, the nucleophilic attack, and the cleavage of the S-O (P-O) bond is proposed. Regarding the phosphate monoester, the results indicate that only some steps of the promiscuous reaction are identical to those in the native process. Differences concern mainly the last step in which the His115 residue acts as a general base to accept the proton by the O atom of the FGly51 in the PNPS, whereas in PNPP, the Asp317 protonated residue works as a general acid to deliver a proton by a water molecule to the oxygen atom of the C-O bond. The shapes of the relative potential-energy surface (PES) are similar in the two examined cases but the rate-determining step is different (nucleophile attack vs. nucleophile activation). The influence of the dispersion contributions on the investigated reactions was also taken into account.

  17. Experimental Pseudomonas aeruginosa Infection of the Mouse Cornea

    PubMed Central

    Gerke, John R.; Magliocco, Michael V.

    1971-01-01

    Pseudomonas aeruginosa infection of human cornea is rare but serious. The work of previous investigators using experimental infection primarily of rabbit cornea resulted in successful therapy for 10 to 50% of clinical cases. The advantage of using the mouse is demonstrated. The methods we adapted for characterizing the untreated experimental infection included: incising the cornea to enable establishing the infection; corneal examination with a steroscopic microscope; grading corneal pathology; qualitative and quantitative monitoring of the infecting bacteria by culturing and staining sectioned and dissected tissues. The characteristics of the tissue pathology, host response, and infection were similar to those reported for other animals and man. Corneal pathology was frequently nearly maximal 1 day after infection; host response involved a progression of events of long duration; pathology persisted well beyond the period of bacterial infection. The infection was essentially noncommunicable, and invasiveness was limited to the tissues of the incised eye. The results show the possibility of tests for invasiveness of clinical isolates and for screening for therapeutic and prophylactic measures. PMID:16557955

  18. Arabinanase A from Pseudomonas fluorescens subsp. cellulosa exhibits both an endo- and an exo- mode of action.

    PubMed Central

    McKie, V A; Black, G W; Millward-Sadler, S J; Hazlewood, G P; Laurie, J I; Gilbert, H J

    1997-01-01

    Pseudomonas fluorescens subsp. cellulosa expressed arabinanase activity when grown on media supplemented with arabinan or arabinose. Arabinanase activity was not induced by the inclusion of other plant structural polysaccharides, and was repressed by the addition of glucose. The majority of the Pseudomonas arabinanase activity was extracellular. Screening of a genomic library of P. fluorescens subsp. cellulosa DNA constructed in Lambda ZAPII, for recombinants that hydrolysed Red-dyed arabinan, identified five arabinan-degrading plaques. Each of the phage contained the same Pseudomonas arabinanase gene, designated arbA, which was present as a single copy in the Pseudomonas genome. The nucleotide sequence of arbA revealed an open reading frame of 1041 bp encoding a protein, designated arabinanase A (ArbA), of Mr 39438. The N-terminal sequence of ArbA exhibited features typical of a prokaryotic signal peptide. Analysis of the primary structure of ArbA indicated that, unlike most Pseudomonas plant cell wall hydrolases, it did not contain linker sequences or have a modular structure, but consisted of a single catalytic domain. Sequence comparison between the Pseudomonas arabinanase and proteins in the SWISS-PROT database showed that ArbA exhibits greatest sequence identity with arabinanase A from Aspergillus niger, placing the enzyme in glycosyl hydrolase Family 43. The significance of the differing substrate specificities of enzymes in Family 43 is discussed. ArbA purifed from a recombinant strain of Escherichia coli had an Mr of 34000 and an N-terminal sequence identical to residues 32-51 of the deduced sequence of ArbA, and hydrolysed linear arabinan, carboxymethylarabinan and arabino-oligosaccharides. The enzyme displayed no activity against other plant structural polysaccharides, including branched sugar beet arabinan. ArbA produced almost exclusively arabinotriose from linear arabinan and appeared to hydrolyse arabino-oligosaccharides by successively releasing

  19. Alginate Lyase Promotes Diffusion of Aminoglycosides through the Extracellular Polysaccharide of Mucoid Pseudomonas aeruginosa

    PubMed Central

    Hatch, Richard A.; Schiller, Neal L.

    1998-01-01

    We demonstrated that a 2% suspension of Pseudomonas aeruginosa alginate completely blocked the diffusion of gentamicin and tobramycin, but not that of carbenicillin, illustrating how alginate production can help protect P. aeruginosa growing within alginate microcolonies in patients with cystic fibrosis (CF) from the effects of aminoglycosides. This aminoglycoside diffusion barrier was degraded with a semipurified preparation of P. aeruginosa alginate lyase, suggesting that this enzyme deserves consideration as an adjunctive agent for CF patients colonized by mucoid strains of P. aeruginosa. PMID:9559826

  20. Virulence genome analysis of Pseudomonas aeruginosa VRFPA10 recovered from patient with scleritis.

    PubMed

    Murugan, Nandagopal; Malathi, Jambulingam; Umashankar, Vetrivel; Madhavan, Hajib Narahari Rao

    2017-06-01

    Infectious keratitis is a major cause of blindness, next to cataract and majority of cases are mainly caused by gram negative bacterium Pseudomonas aeruginosa (P. aeruginosa). In this study, we investigated a P. aeruginosa VRFPA10 genome which exhibited susceptibility to commonly used drugs in vitro but the patient had poor prognosis due to its hyper virulent nature. Genomic analysis of VRFPA10 deciphered multiple virulence factors and P.aeruginosa Genomic Islands (PAGIs) VRFPA10 genome which correlated with hyper virulence nature of the organism. The genome sequence has been deposited in DDBJ/EMBL/GenBank under the accession numbers LFMZ01000001-LFMZ01000044.

  1. Pseudomonas aeruginosa forms Biofilms in Acute InfectionIndependent of Cell-to-Cell Signaling

    SciTech Connect

    Schaber, J. Andy; Triffo, W.J.; Suh, Sang J.; Oliver, Jeffrey W.; Hastert, Mary C.; Griswold, John A.; Auer, Manfred; Hamood, Abdul N.; Rumbaugh, Kendra P.

    2006-09-20

    Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 hours of infection in thermally-injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections. P. aeruginosa biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild type and QS-deficient P. aeruginosa formed similar biofilms in vivo. Our findings demonstrate that P. aeruginosa forms biofilms on specific host tissues independent of QS.

  2. Expression of a fully functional cd1 nitrite reductase from Pseudomonas aeruginosa in Pseudomonas stutzeri.

    PubMed

    Arese, Marzia; Zumft, Walter G; Cutruzzolà, Francesca

    2003-01-01

    Nitrite reductases are redox enzymes catalysing the one electron reduction of nitrite to nitrogen monoxide (NO) within the bacterial denitrification process. We have cloned the gene for cd(1) nitrite reductase (Pa-nirS) from Pseudomonas aeruginosa into the NiRS(-) strain MK202 of Pseudomonas stutzeri and expressed the enzyme under denitrifying conditions. In the MK202 strain, denitrification is abolished by the disruption of the endogenous nitrite reductase gene; thus, cells can be grown only in the presence of oxygen. After complementation with Pa-nirS gene, cells supplemented with nitrate can be grown in the absence of oxygen. The presence of nitrite reductase was proven in vivo by the demonstration of NO production, showing that the enzyme was expressed in the active form, containing both heme c and d(1). A purification procedure for the recombinant PaNir has been developed, based on the P. aeruginosa purification protocol; spectroscopic analysis of the purified protein fully confirms the presence of the d(1) heme cofactor. Moreover, the functional characterisation of the recombinant NiR has been carried out by monitoring the production of NO by the purified NiR enzyme in the presence of nitrite by an NO electrode. The full recovery of the denitrification properties in the P. stutzeri MK202 strain by genetic complementation with Pa-NiR underlines the high homology between enzymes of nitrogen oxianion respiration. Our work provides an expression system for cd(1) nitrite reductase and its site-directed mutants in a non-pathogenic strain and is a starting point for the in vivo study of recombinant enzyme variants.

  3. New insights into Pseudomonas fluorescens alginate biosynthesis relevant for the establishment of an efficient production process for microbial alginates.

    PubMed

    Maleki, Susan; Mærk, Mali; Hrudikova, Radka; Valla, Svein; Ertesvåg, Helga

    2017-07-25

    Alginate denotes a family of linear polysaccharides with a wide range of industrial and pharmaceutical applications. Presently, all commercially available alginates are manufactured from brown algae. However, bacterial alginates have advantages with regard to compositional homogeneity and reproducibility. In order to be able to design bacterial strains that are better suited for industrial alginate production, defining limiting factors for alginate biosynthesis is of vital importance. Our group has been studying alginate biosynthesis in Pseudomonas fluorescens using several complementary approaches. Alginate is synthesised and transported out of the cell by a multiprotein complex spanning from the inner to the outer membrane. We have developed an immunogold labelling procedure in which the porin AlgE, as a part of this alginate factory, could be detected by transmission electron microscopy. No time-dependent correlation between the number of such factories on the cell surface and alginate production level was found in alginate-producing strains. Alginate biosynthesis competes with the central carbon metabolism for the key metabolite fructose 6-phosphate. In P. fluorescens, glucose, fructose and glycerol, are metabolised via the Entner-Doudoroff and pentose phosphate pathways. Mutational analysis revealed that disruption of the glucose 6-phosphate dehydrogenase gene zwf-1 resulted in increased alginate production when glycerol was used as carbon source. Furthermore, alginate-producing P. fluorescens strains cultivated on glucose experience acid stress due to the simultaneous production of alginate and gluconate. The combined results from our studies strongly indicate that the availability of fructose 6-phosphate and energy requires more attention in further research aimed at the development of an optimised alginate production process.

  4. Enhanced citric acid biosynthesis in Pseudomonas fluorescens ATCC 13525 by overexpression of the Escherichia coli citrate synthase gene.

    PubMed

    Buch, Aditi D; Archana, G; Kumar, G Naresh

    2009-08-01

    Citric acid secretion by fluorescent pseudomonads has a distinct significance in microbial phosphate solubilization. The role of citrate synthase in citric acid biosynthesis and glucose catabolism in pseudomonads was investigated by overexpressing the Escherichia coli citrate synthase (gltA) gene in Pseudomonas fluorescens ATCC 13525. The resultant approximately 2-fold increase in citrate synthase activity in the gltA-overexpressing strain Pf(pAB7) enhanced the intracellular and extracellular citric acid yields during the stationary phase, by about 2- and 26-fold, respectively, as compared to the control, without affecting the growth rate, glucose depletion rate or biomass yield. Decreased glucose consumption was paralleled by increased gluconic acid production due to an increase in glucose dehydrogenase activity. While the extracellular acetic acid yield increased in Pf(pAB7), pyruvic acid secretion decreased, correlating with an increase in pyruvate carboxylase activity and suggesting an increased demand for the anabolic precursor oxaloacetate. Activities of two other key enzymes, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase, remained unaltered, and the contribution of phosphoenolpyruvate carboxylase and isocitrate lyase to glucose catabolism was negligible. Strain Pf(pAB7) demonstrated an enhanced phosphate-solubilizing ability compared to the control. Co-expression of the Synechococcus elongatus PCC 6301 phosphoenolpyruvate carboxylase and E. coli gltA genes in P. fluorescens ATCC 13525, so as to supplement oxaloacetate for citrate biosynthesis, neither significantly affected citrate biosynthesis nor caused any change in the other physiological and biochemical parameters measured, despite approximately 1.3- and 5-fold increases in citrate synthase and phosphoenolpyruvate carboxylase activities, respectively. Thus, our results demonstrate that citrate synthase is rate-limiting in enhancing citrate biosynthesis in P. fluorescens ATCC 13525

  5. Construction and Application of Variants of the Pseudomonas fluorescens EBC191 Arylacetonitrilase for Increased Production of Acids or Amides▿ †

    PubMed Central

    Sosedov, Olga; Baum, Stefanie; Bürger, Sibylle; Matzer, Kathrin; Kiziak, Christoph; Stolz, Andreas

    2010-01-01

    The arylacetonitrilase from Pseudomonas fluorescens EBC191 differs from previously studied arylacetonitrilases by its low enantiospecificity during the turnover of mandelonitrile and by the large amounts of amides that are formed in the course of this reaction. In the sequence of the nitrilase from P. fluorescens, a cysteine residue (Cys163) is present in direct neighborhood (toward the amino terminus) to the catalytic active cysteine residue, which is rather unique among bacterial nitrilases. Therefore, this cysteine residue was exchanged in the nitrilase from P. fluorescens EBC191 for various amino acid residues which are present in other nitrilases at the homologous position. The influence of these mutations on the reaction specificity and enantiospecificity was analyzed with (R,S)-mandelonitrile and (R,S)-2-phenylpropionitrile as substrates. The mutants obtained demonstrated significant differences in their amide-forming capacities. The exchange of Cys163 for asparagine or glutamine residues resulted in significantly increased amounts of amides formed. In contrast, a substitution for alanine or serine residues decreased the amounts of amides formed. The newly discovered mutation was combined with previously identified mutations which also resulted in increased amide formation. Thus, variants which possessed in addition to the mutation Cys163Asn also a deletion at the C terminus of the enzyme and/or the modification Ala165Arg were constructed. These constructs demonstrated increased amide formation capacity in comparison to the mutants carrying only single mutations. The recombinant plasmids that encoded enzyme variants which formed large amounts of mandeloamide or that formed almost stoichiometric amounts of mandelic acid from mandelonitrile were used to transform Escherichia coli strains that expressed a plant-derived (S)-hydroxynitrile lyase. The whole-cell biocatalysts obtained in this way converted benzaldehyde plus cyanide either to (S)-mandeloamide or (S

  6. Pseudomonas aeruginosa facilitates Campylobacter jejuni growth in biofilms under oxic flow conditions.

    PubMed

    Culotti, Alessandro; Packman, Aaron I

    2015-12-01

    We investigated the growth of Campylobacter jejuni in biofilms with Pseudomonas aeruginosa under oxic flow conditions. We observed the growth of C. jejuni in mono-culture, deposited on pre-established P. aeruginosa biofilms, and co-inoculated with P. aeruginosa. In mono-culture, C. jejuni was unable to form biofilms. However, deposited C. jejuni continuously grew on pre-established P. aeruginosa biofilms for a period of 3 days. The growth of scattered C. jejuni clusters was strictly limited to the P. aeruginosa biofilm surface, and no intergrowth was observed. Co-culturing of C. jejuni and P. aeruginosa also enabled the growth of both organisms in biofilms, with C. jejuni clusters developing on the surface of the P. aeruginosa biofilm. Dissolved oxygen (DO) measurements in the medium showed that P. aeruginosa biofilms depleted the effluent DO from 9.0 to 0.5 mg L(-1) 24 hours after inoculation. The localized microaerophilic environment generated by P. aeruginosa promoted the persistence and growth of C. jejuni. Our findings show that P. aeruginosa not only prolongs the survival of C. jejuni under oxic conditions, but also enables the growth of C. jejuni on the surface of P. aeruginosa biofilms.

  7. Photocatalytic disinfection of spoilage bacteria Pseudomonas fluorescens and Macrococcus caseolyticus by nano-TiO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Photocatalytic disinfection of spoilage bacteria gram-negative (G-) P. fluorescens and gram-positive (G+) M. caseolyticus by nano-TiO2 under different experimental conditions and the disinfection mechanism were investigated. The experimental conditions included the initial bacterial populations, nan...

  8. Effect of Tyrosol and Farnesol on Virulence and Antibiotic Resistance of Clinical Isolates of Pseudomonas aeruginosa.

    PubMed

    Abdel-Rhman, Shaymaa Hassan; El-Mahdy, Areej Mostafa; El-Mowafy, Mohammed

    2015-01-01

    Mixed-species biofilms could create a protected environment that allows for survival to external antimicrobials and allows different bacterial-fungal interactions. Pseudomonas aeruginosa-Candida albicans coexistence is an example for such mixed-species community. Numerous reports demonstrated how P. aeruginosa or its metabolites could influence the growth, morphogenesis, and virulence of C. albicans. In this study, we investigated how the C. albicans quorum sensing compounds, tyrosol and farnesol, might affect Egyptian clinical isolates of P. aeruginosa regarding growth, antibiotic sensitivity, and virulence. We could demonstrate that tyrosol possesses an antibacterial activity against P. aeruginosa (10 µM inhibited more than 50% of growth after 16 h cultivation). Moreover, we could show for the first time that tyrosol strongly inhibits the production of the virulence factors hemolysin and protease in P. aeruginosa, whereas farnesol inhibits, to lower extent, hemolysin production in this bacterial pathogen. Cumulatively, tyrosol is expected to strongly affect P. aeruginosa in mixed microbial biofilm.

  9. Evolution under different storage conditions of anomalous blue coloration of Mozzarella cheese intentionally contaminated with a pigment-producing strain of Pseudomonas fluorescens.

    PubMed

    Cenci-Goga, B T; Karama, M; Sechi, P; Iulietto, M F; Novelli, S; Mattei, S

    2014-11-01

    Several widespread occurrences of anomalous blue coloration of Mozzarella cheese have been recorded in the United States and some European countries. Official laboratory analysis and health authorities have linked the occurrences to contamination of the processing water with strains of Pseudomonas fluorescens, although several experts questioned how to unequivocally link the blue color to the presence of the microorganism. To establish a method to determine whether a given Pseudomonas spp. strain is responsible for the defect and study the evolution of the coloration under different storage conditions, we developed an in vitro system for the evaluation of blue coloration of Mozzarella cheese intentionally contaminated with strains of P. fluorescens. The purpose of the system was to determine whether P.fluorescens strains, isolated from Mozzarella cheese with anomalous blue coloration, were able to reproduce the blue coloration under controlled experimental conditions. Thirty-six trials of experimental inoculation of Mozzarella cheese in different preservation liquids were conducted using various suspensions of P.fluorescens (P. fluorescens ATCC 13525, P.fluorescens CFBP 3150, and P. fluorescens 349 field strain isolated from blue-colored Mozzarella cheese) at different concentrations and incubated at different temperatures. Growth curves of all tested P.fluorescens strains demonstrated that after 3 d of incubation the concentration was generally >10(6) cfu/g of Mozzarella cheese incubated in either tryptic soy broth (control) or conditioning brine. Prolonged incubation for 5 d at either 20 °C or 8 °C led to concentrations up to 10(9) cfu/g of Mozzarella cheese incubated in tryptic soy broth and up to 10(8) cfu/g of Mozzarella cheese incubated in preservation liquid. All Mozzarella cheeses inoculated with the field strain of P. fluorescens, except those opened 1h after packaging and stored at 8 °C, showed the characteristic anomalous blue coloration, which

  10. Mycorrhization between Cistus ladanifer L. and Boletus edulis Bull is enhanced by the mycorrhiza helper bacteria Pseudomonas fluorescens Migula.

    PubMed

    Mediavilla, Olaya; Olaizola, Jaime; Santos-del-Blanco, Luis; Oria-de-Rueda, Juan Andrés; Martín-Pinto, Pablo

    2016-02-01

    Boletus edulis Bull. is one of the most economically and gastronomically valuable fungi worldwide. Sporocarp production normally occurs when symbiotically associated with a number of tree species in stands over 40 years old, but it has also been reported in 3-year-old Cistus ladanifer L. shrubs. Efforts toward the domestication of B. edulis have thus focused on successfully generating C. ladanifer seedlings associated with B. edulis under controlled conditions. Microorganisms have an important role mediating mycorrhizal symbiosis, such as some bacteria species which enhance mycorrhiza formation (mycorrhiza helper bacteria). Thus, in this study, we explored the effect that mycorrhiza helper bacteria have on the efficiency and intensity of the ectomycorrhizal symbiosis between C. ladanifer and B. edulis. The aim of this work was to optimize an in vitro protocol for the mycorrhizal synthesis of B. edulis with C. ladanifer by testing the effects of fungal culture time and coinoculation with the helper bacteria Pseudomonas fluorescens Migula. The results confirmed successful mycorrhizal synthesis between C. ladanifer and B. edulis. Coinoculation of B. edulis with P. fluorescens doubled within-plant mycorrhization levels although it did not result in an increased number of seedlings colonized with B. edulis mycorrhizae. B. edulis mycelium culture time also increased mycorrhization levels but not the presence of mycorrhizae. These findings bring us closer to controlled B. edulis sporocarp production in plantations.

  11. Optimization of lipase production on agro-industrial residue medium by Pseudomonas fluorescens (NRLL B-2641) using response surface methodology

    PubMed Central

    Tanyol, Mehtap; Uslu, Gülşad; Yönten, Vahap

    2015-01-01

    The aim of our research was to explore the most cost-efficient and optimal medium composition for the production of lipase from Pseudomonas fluorescens (NRLL B-2641) culture grown on sunflower oil cake (SuOC) by applying response surface methodology (RSM). The oil cake was used instead of carbon sources. Peptone, ammonium sulphate and the carbon source (SuOC) were the most important factors as it is obligatory for microbial growth. Subsequently, the optimum values for the carbon source, peptone and ammonium sulphate were found to be 11.10% (w/v), 1.18% (w/v) and 0.83% (w/v), respectively. Experiments carried out under optimum conditions revealed a maximum lipase activity of 10.8 U mL−1, which was achieved after 48 h of fermentation. The obtained results were finally verified with batch experiments carried out under the optimum conditions evaluated and it was demonstrated that the SuOC from agro-industrial residue as substrates can be used as an inexpensive base (carbon source) for the production of lipase by P. fluorescens (NRLL B-2641). PMID:26740789

  12. Evaluate the heavy metal toxicity to Pseudomonas fluorescens in a low levels of metal-chelates minimal medium.

    PubMed

    Wang, Fei; Yao, Jun; Chen, Huilun; Yi, Zhengji; Yu, Chan; Tuo, Yujie; Ma, Lan; Yu, Qian

    2014-01-01

    A 2-(n-morpholino)ethane sulfonic acid (MES)-buffered minimal medium with low levels of metal chelates was used to evaluate the heavy metal (Co+2, Pb+2, Zn+2, Fe+2, Fe+3, Cd+2, Cu+2, and Cr+6) toxicity to Pseudomonas fluorescens through minimizing the limitation of the existing medium. The interaction between bacteria and heavy metals was real-time monitored by microcalorimetry and reflected by thermogenic curves. Compared with the main parameters, microbial growth rate constant k and total heat evolution Q total, a general order of toxicity was found to be Fe+3fluorescens biomass identified by Fourier transform infrared (FTIR) were amino, carboxyl, hydroxyl, and phosphoryl groups, which maybe involved in the biosorption of metal ions.

  13. The type III secretion system of biocontrol Pseudomonas fluorescens KD targets the phytopathogenic Chromista Pythium ultimum and promotes cucumber protection.

    PubMed

    Rezzonico, Fabio; Binder, Christian; Défago, Geneviève; Moënne-Loccoz, Yvan

    2005-09-01

    The type III secretion system (TTSS) is used by Proteobacteria for pathogenic or symbiotic interaction with plant and animal hosts. Recently, TTSS genes thought to originate from the phytopathogen Pseudomonas syringae were evidenced in Pseudomonas fluorescens KD, which protects cucumber from the oomycete Pythium ultimum (kingdom Chromista/Stramenopila). However, it is not known whether the TTSS contributes to plant protection by the bacterium and, if so, whether it targets the plant or the phytopathogen. Inactivation of TTSS gene hrcV following the insertion of an omega cassette strongly reduced the biocontrol activity of the pseudomonad against P. ultimum on cucumber when compared with the wild type, but had no effect on its root-colonization ability. Analysis of a plasmid-based transcriptional hrpJ'-inaZ reporter fusion revealed that expression in strain KD of the operon containing hrcV was strongly stimulated in vitro and in situ by the oomycete and not by the plant. In vitro, both strain KD and its hrcV mutant reduced the activity level of the pectinase polygalacturonase (a key pathogenicity factor) from P. ultimum, but the reduction was much stronger with the wild type. Together, these results show that the target range of bacterial TTSS is not restricted to plants and animals but also can include members of Chromista/Stramenopila, and suggest that virulence genes acquired horizontally from phytopathogenic bacteria were functionally recycled in biocontrol saprophytic Pseudomonas spp., resulting in enhanced plant protection by the latter.

  14. QapR (PA5506) represses an operon that negatively affects the Pseudomonas quinolone signal in Pseudomonas aeruginosa.

    PubMed

    Tipton, Kyle A; Coleman, James P; Pesci, Everett C

    2013-08-01

    Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen that can cause disease in varied sites within the human body and is a significant source of morbidity and mortality in those afflicted with cystic fibrosis. P. aeruginosa is able to coordinate group behaviors, such as virulence factor production, through the process of cell-to-cell signaling. There are three intercellular signaling systems employed by P. aeruginosa, and one of these systems utilizes the small molecule 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas quinolone signal [PQS]). PQS is required for virulence in multiple infection models and has been found in the lungs of cystic fibrosis patients colonized by P. aeruginosa. In this study, we have identified an RpiR family transcriptional regulator, QapR, which is an autoregulatory repressor. We found that mutation of qapR caused overexpression of the qapR operon. We characterized the qapR operon to show that it contains genes qapR, PA5507, PA5508, and PA5509 and that QapR directly controls the transcription of these genes in a negative manner. We also show that derepression of this operon greatly reduces PQS concentration in P. aeruginosa. Our results suggest that qapR affects PQS concentration by repressing an enzymatic pathway that acts on PQS or a PQS precursor to lower the PQS concentration. We believe that this operon comprises a novel mechanism to regulate PQS concentration in P. aeruginosa.

  15. QapR (PA5506) Represses an Operon That Negatively Affects the Pseudomonas Quinolone Signal in Pseudomonas aeruginosa

    PubMed Central

    Tipton, Kyle A.; Coleman, James P.

    2013-01-01

    Pseudomonas aeruginosa is a Gram-negative, opportunistic pathogen that can cause disease in varied sites within the human body and is a significant source of morbidity and mortality in those afflicted with cystic fibrosis. P. aeruginosa is able to coordinate group behaviors, such as virulence factor production, through the process of cell-to-cell signaling. There are three intercellular signaling systems employed by P. aeruginosa, and one of these systems utilizes the small molecule 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas quinolone signal [PQS]). PQS is required for virulence in multiple infection models and has been found in the lungs of cystic fibrosis patients colonized by P. aeruginosa. In this study, we have identified an RpiR family transcriptional regulator, QapR, which is an autoregulatory repressor. We found that mutation of qapR caused overexpression of the qapR operon. We characterized the qapR operon to show that it contains genes qapR, PA5507, PA5508, and PA5509 and that QapR directly controls the transcription of these genes in a negative manner. We also show that derepression of this operon greatly reduces PQS concentration in P. aeruginosa. Our results suggest that qapR affects PQS concentration by repressing an enzymatic pathway that acts on PQS or a PQS precursor to lower the PQS concentration. We believe that this operon comprises a novel mechanism to regulate PQS concentration in P. aeruginosa. PMID:23708133

  16. Quorum-sensing inhibition abrogates the deleterious impact of Pseudomonas aeruginosa on airway epithelial repair.

    PubMed

    Ruffin, Manon; Bilodeau, Claudia; Maillé, Émilie; LaFayette, Shantelle L; McKay, Geoffrey A; Trinh, Nguyen Thu Ngan; Beaudoin, Trevor; Desrosiers, Martin-Yvon; Rousseau, Simon; Nguyen, Dao; Brochiero, Emmanuelle

    2016-09-01

    Chronic Pseudomonas aeruginosa lung infections are associated with progressive epithelial damage and lung function decline. In addition to its role in tissue injury, the persistent presence of P. aeruginosa-secreted products may also affect epithelial repair ability, raising the need for new antivirulence therapies. The purpose of our study was to better understand the outcomes of P. aeruginosa exoproducts exposure on airway epithelial repair processes to identify a strategy to counteract their deleterious effect. We found that P. aeruginosa exoproducts significantly decreased wound healing, migration, and proliferation rates, and impaired the ability of directional migration of primary non-cystic fibrosis (CF) human airway epithelial cells. Impact of exoproducts was inhibited after mutations in P. aeruginosa genes that encoded for the quorum-sensing (QS) transcriptional regulator, LasR, and the elastase, LasB, whereas impact was restored by LasB induction in ΔlasR mutants. P. aeruginosa purified elastase also induced a significant decrease in non-CF epithelial repair, whereas protease inhibition with phosphoramidon prevented the effect of P. aeruginosa exoproducts. Furthermore, treatment of P. aeruginosa cultures with 4-hydroxy-2,5-dimethyl-3(2H)-furanone, a QS inhibitor, abrogated the negative impact of P. aeruginosa exoproducts on airway epithelial repair. Finally, we confirmed our findings in human airway epithelial cells from patients with CF, a disease featuring P. aeruginosa chronic respiratory infection. These data demonstrate that secreted proteases under the control of the LasR QS system impair airway epithelial repair and that QS inhibitors could be of benefit to counteract the deleterious effect of P. aeruginosa in infected patients.-Ruffin, M., Bilodeau, C., Maillé, É., LaFayette, S. L., McKay, G. A., Trinh, N. T. N., Beaudoin, T., Desrosiers, M.-Y., Rousseau, S., Nguyen, D., Brochiero, E. Quorum-sensing inhibition abrogates the deleterious impact

  17. The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

    PubMed Central

    Nadal Jimenez, Pol; Koch, Gudrun; Thompson, Jessica A.; Xavier, Karina B.; Cool, Robbert H.

    2012-01-01

    Summary: Cell-to-cell communication is a major process that allows bacteria to sense and coordinately react to the fluctuating conditions of the surrounding environment. In several pathogens, this process triggers the production of virulence factors and/or a switch in bacterial lifestyle that is a major determining factor in the outcome and severity of the infection. Understanding how bacteria control these signaling systems is crucial to the development of novel antimicrobial agents capable of reducing virulence while allowing the immune system of the host to clear bacterial infection, an approach likely to reduce the selective pressures for development of resistance. We provide here an up-to-date overview of the molecular basis and physiological implications of cell-to-cell signaling systems in Gram-negative bacteria, focusing on the well-studied bacterium Pseudomonas aeruginosa. All of the known cell-to-cell signaling systems in this bacterium are described, from the most-studied systems, i.e., N-acyl homoserine lactones (AHLs), the 4-quinolones, the global activator of antibiotic and cyanide synthesis (GAC), the cyclic di-GMP (c-di-GMP) and cyclic AMP (cAMP) systems, and the alarmones guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp), to less-well-studied signaling molecules, including diketopiperazines, fatty acids (diffusible signal factor [DSF]-like factors), pyoverdine, and pyocyanin. This overview clearly illustrates that bacterial communication is far more complex than initially thought and delivers a clear distinction between signals that are quorum sensing dependent and those relying on alternative factors for their production. PMID:22390972

  18. Structural and Functional Characterization of Pseudomonas aeruginosa AlgX

    PubMed Central

    Riley, Laura M.; Weadge, Joel T.; Baker, Perrin; Robinson, Howard; Codée, Jeroen D. C.; Tipton, Peter A.; Ohman, Dennis E.; Howell, P. Lynne

    2013-01-01

    The exopolysaccharide alginate, produced by mucoid Pseudomonas aeruginosa in the lungs of cystic fibrosis patients, undergoes two different chemical modifications as it is synthesized that alter the properties of the polymer and hence the biofilm. One modification, acetylation, causes the cells in the biofilm to adhere better to lung epithelium, form microcolonies, and resist the effects of the host immune system and/or antibiotics. Alginate biosynthesis requires 12 proteins encoded by the algD operon, including AlgX, and although this protein is essential for polymer production, its exact role is unknown. In this study, we present the X-ray crystal structure of AlgX at 2.15 Å resolution. The structure reveals that AlgX is a two-domain protein, with an N-terminal domain with structural homology to members of the SGNH hydrolase superfamily and a C-terminal carbohydrate-binding module. A number of residues in the carbohydrate-binding module form a substrate recognition “pinch point” that we propose aids in alginate binding and orientation. Although the topology of the N-terminal domain deviates from canonical SGNH hydrolases, the residues that constitute the Ser-His-Asp catalytic triad characteristic of this family are structurally conserved. In vivo studies reveal that site-specific mutation of these residues results in non-acetylated alginate. This catalytic triad is also required for acetylesterase activity in vitro. Our data suggest that not only does AlgX protect the polymer as it passages through the periplasm but that it also plays a role in alginate acetylation. Our results provide the first structural insight for a wide group of closely related bacterial polysaccharide acetyltransferases. PMID:23779107

  19. Isolation and characterization of gallium resistant Pseudomonas aeruginosa mutants.

    PubMed

    García-Contreras, Rodolfo; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Hernández-González, Ismael L; Maeda, Toshinari; Hashimoto, Takahiro; Boogerd, Fred C; Sheng, Lili; Wood, Thomas K; Moreno-Sánchez, Rafael

    2013-12-01

    Pseudomonas aeruginosa PA14 cells resistant to the novel antimicrobial gallium nitrate (Ga) were developed using transposon mutagenesis and by selecting spontaneous mutants. The mutants showing the highest growth in the presence of Ga were selected for further characterization. These mutants showed 4- to 12-fold higher Ga minimal inhibitory growth concentrations and a greater than 8-fold increase in the minimum biofilm eliminating Ga concentration. Both types of mutants produced Ga resistant biofilms whereas the formation of wild-type biofilms was strongly inhibited by Ga. The gene interrupted in the transposon mutant was hitA, which encodes a periplasmic iron binding protein that delivers Fe³⁺ to the HitB iron permease; complementation of the mutant with the hitA gene restored the Ga sensitivity. This hitA mutant showed a 14-fold decrease in Ga internalization versus the wild-type strain, indicating that the HitAB system is also involved in the Ga uptake. Ga uptake in the spontaneous mutant was also lower, although no mutations were found in the hitAB genes. Instead, this mutant harbored 64 non-silent mutations in several genes including those of the phenazine pyocyanin biosynthesis. The spontaneous mutant produced 2-fold higher pyocyanin basal levels than the wild-type; the addition of this phenazine to wild-type cultures protected them from the Ga bacteriostatic effect. The present data indicate that mutations affecting Ga transport and probably pyocyanin biosynthesis enable cells to develop resistance to Ga.

  20. Characterization of temporal protein production in Pseudomonas aeruginosa biofilms.

    PubMed

    Southey-Pillig, Christopher J; Davies, David G; Sauer, Karin

    2005-12-01

    Phenotypic and genetic evidence supporting the notion of biofilm formation as a developmental process is growing. In the present work, we provide additional support for this hypothesis by identifying the onset of accumulation of biofilm-stage specific proteins during Pseudomonas aeruginosa biofilm maturation and by tracking the abundance of these proteins in planktonic and three biofilm developmental stages. The onset of protein production was found to correlate with the progression of biofilms in developmental stages. Protein identification revealed that proteins with similar function grouped within similar protein abundance patterns. Metabolic and housekeeping proteins were found to group within a pattern separate from virulence, antibiotic resistance, and quorum-sensing-related proteins. The latter were produced in a progressive manner, indicating that attendant features that are characteristic of biofilms such as antibiotic resistance and virulence may be part of the biofilm developmental process. Mutations in genes for selected proteins from several protein production patterns were made, and the impact of these mutations on biofilm development was evaluated. The proteins cytochrome c oxidase, a probable chemotaxis transducer, a two-component response regulator, and MexH were produced only in mature and late-stage biofilms. Mutations in the genes encoding these proteins did not confer defects in growth, initial attachment, early biofilm formation, or twitching motility but were observed to arrest biofilm development at the stage of cell cluster formation we call the maturation-1 stage. The results indicated that expression of theses genes was required for the progression of biofilms into three-dimensional structures on abiotic surfaces and the completion of the biofilm developmental cycle. Reverse transcription-PCR analysis confirmed the detectable change in expression of the respective genes ccoO, PA4101, and PA4208. We propose a possible mechanism for the

  1. Preparation and biophysical characterization of recombinant Pseudomonas aeruginosa phosphorylcholine phosphatase.

    PubMed

    Beassoni, Paola R; Berti, Federico Pérez de; Otero, Lisandro H; Risso, Valeria A; Ferreyra, Raul G; Lisa, Angela T; Domenech, Carlos E; Ermácora, Mario R

    2010-06-01

    Pseudomonas aeruginosa infections constitute a widespread health problem with high economical and social impact, and the phosphorylcholine phosphatase (PchP) of this bacterium is a potential target for antimicrobial treatment. However, drug design requires high-resolution structural information and detailed biophysical knowledge not available for PchP. An obstacle in the study of PchP is that current methods for its expression and purification are suboptimal and allowed only a preliminary kinetic characterization of the enzyme. Herein, we describe a new procedure for the efficient preparation of recombinant PchP overexpressed in Escherichia coli. The enzyme is purified from urea solubilized inclusion bodies and refolded by dialysis. The product of PchP refolding is a mixture of native PchP and a kinetically-trapped, alternatively-folded aggregate that is very slowly converted into the native state. The properly folded and fully active enzyme is isolated from the refolding mixture by size-exclusion chromatography. PchP prepared by the new procedure was subjected to chemical and biophysical characterization, and its basic optical, hydrodynamic, metal-binding, and catalytic properties are reported. The unfolding of the enzyme was also investigated, and its thermal stability was determined. The obtained information should help to compare PchP with other phosphatases and to obtain a better understanding of its catalytic mechanism. In addition, preliminary trials showed that PchP prepared by the new protocol is suitable for crystallization, opening the way for high-resolution studies of the enzyme structure.

  2. [Metabolic products of hydrocarbon-oxidizing strains of Mycococcus lactis and Pseudomonas fluorescens and their influence on culture growth].

    PubMed

    Spitsyna, D N; Gradova, N B; Davidova, E G

    1977-01-01

    The effect of concentrations of organic acids in the cultural broth on growth was studied with the strains of Mycococcus lactis and Pseudomonas fluorescens oxidizing hydrocarbons. The ratio between the acid and neutral fractions in the cultural broth of Mycococcus lactis was also investigated as well as their action on the bacterial growth. Mycococcus lactis growing on paraffin was found to produce acid and neutral products at a ratio of 1:2. The acid and neutral products of metabolism produced different action on the growth of the carbohydrate oxidizing bacteria. The acid products inhibited the growth at a concentration of organic acids in the medium above 500 mg/litre. The neutral products were partily assimilated by Mycococcus lactis.

  3. The impact of culture medium on the development and physiology of biofilms of Pseudomonas fluorescens formed on polyurethane paint.

    PubMed

    Crookes-Goodson, Wendy J; Bojanowski, Caitlin L; Kay, Michelle L; Lloyd, Pamela F; Blankemeier, Andrew; Hurtubise, Jennifer M; Singh, Kristi M; Barlow, Daniel E; Ladouceur, Harold D; Matt Eby, D; Johnson, Glenn R; Mirau, Peter A; Pehrsson, Pehr E; Fraser, Hamish L; Russell, John N

    2013-01-01

    Microbial biofilms cause the deterioration of polymeric coatings such as polyurethanes (PUs). In many cases, microbes have been shown to use the PU as a nutrient source. The interaction between biofilms and nutritive substrata is complex, since both the medium and the substratum can provide nutrients that affect biofilm formation and biodeterioration. Historically, studies of PU biodeterioration have monitored the planktonic cells in the medium surrounding the material, not the biofilm. This study monitored planktonic and biofilm cell counts, and biofilm morphology, in long-term growth experiments conducted with Pseudomonas fluorescens under different nutrient conditions. Nutrients affected planktonic and biofilm cell numbers differently, and neither was representative of the system as a whole. Microscopic examination of the biofilm revealed the presence of intracellular storage granules in biofilms grown in M9 but not yeast extract salts medium. These granules are indicative of nutrient limitation and/or entry into stationary phase, which may impact the biodegradative capability of the biofilm.

  4. Aldol reactions of the trans-o-hydroxybenzylidenepyruvate hydratase-aldolase (tHBP-HA) from Pseudomonas fluorescens N3.

    PubMed

    Sello, Guido; Di Gennaro, Patrizia

    2013-08-01

    In this paper, a recombinant trans-o-hydroxybenzylidenepyruvate hydratase-aldolase (tHBP-HA) of Pseudomonas fluorescens N3 was used as a new catalyst for aldol condensation reactions. The reaction of some aldehydes with a different electronic activation catalyzed by tHBP-HA is presented and discussed together with some hints on the product structure. The enzyme is strictly pyruvate-dependent but uses different aldehydes as acceptors. The structure of the products is highly dependent on the electronic characteristics of the aldehyde. The results are interesting for both their synthetic importance and the mechanism of the formation of the products. Not only the products obtained and the recognition power are reported, but also some characteristics of its mechanism are analyzed. The results clearly show that the enzyme is efficiently prepared, purified, and stored, that it recognizes many different substrates, and that the products depend on the substrate electronic nature.

  5. Adaptive Divergence in Experimental Populations of Pseudomonas fluorescens. V. Insight into the Niche Specialist Fuzzy Spreader Compels Revision of the Model Pseudomonas Radiation

    PubMed Central

    Ferguson, Gayle C.; Bertels, Frederic; Rainey, Paul B.

    2013-01-01

    Pseudomonas fluorescens is a model for the study of adaptive radiation. When propagated in a spatially structured environment, the bacterium rapidly diversifies into a range of niche specialist genotypes. Here we present a genetic dissection and phenotypic characterization of the fuzzy spreader (FS) morphotype—a type that arises repeatedly during the course of the P. fluorescens radiation and appears to colonize the bottom of static broth microcosms. The causal mutation is located within gene fuzY (pflu0478)—the fourth gene of the five-gene fuzVWXYZ operon. fuzY encodes a β-glycosyltransferase that is predicted to modify lipopolysaccharide (LPS) O antigens. The effect of the mutation is to cause cell flocculation. Analysis of 92 independent FS genotypes showed each to have arisen as the result of a loss-of-function mutation in fuzY, although different mutations have subtly different phenotypic and fitness effects. Mutations within fuzY were previously shown to suppress the phenotype of mat-forming wrinkly spreader (WS) types. This prompted a reinvestigation of FS niche preference. Time-lapse photography showed that FS colonizes the meniscus of broth microcosms, forming cellular rafts that, being too flimsy to form a mat, collapse to the vial bottom and then repeatably reform only to collapse. This led to a reassessment of the ecology of the P. fluorescens radiation. Finally, we show that ecological interactions between the three dominant emergent types (smooth, WS, and FS), combined with the interdependence of FS and WS on fuzY, can, at least in part, underpin an evolutionary arms race with bacteriophage SBW25Φ2, to which mutation in fuzY confers resistance. PMID:24077305

  6. A case of orbital apex syndrome due to Pseudomonas aeruginosa infection.

    PubMed

    Kusunoki, Takeshi; Kase, Kaori; Ikeda, Katsuhisa

    2011-09-28

    Orbital apex syndrome is commonly been thought to have a poor prognosis. Many cases of this syndrome have been reported to be caused by paranasal sinus mycosis. We encountered a very rare case (60-year-old woman) of sinusitis with orbital apex syndrome due to Pseudomonas aeruginosa infection. She had received insulin and dialysis for diabtes and diabetic nephropathy, moreover anticoagulants after heart by-pass surgery. She underwent endoscopic sinus operation and was treated with antibiotics, but her loss of left vision did not improve. Recently, sinusitis cases due to Pseudomonas aeruginosa were reported to be a increasing. Therefore, we should consider the possibility of Pseudomonas aeruginosa as well as mycosis as infections of the sinus, especially inpatients who are immunocompromised body.

  7. A case of orbital apex syndrome due to Pseudomonas aeruginosa infection

    PubMed Central

    Kusunoki, Takeshi; Kase, Kaori; Ikeda, Katsuhisa

    2011-01-01

    Orbital apex syndrome is commonly been thought to have a poor prognosis. Many cases of this syndrome have been reported to be caused by paranasal sinus mycosis. We encountered a very rare case (60-year-old woman) of sinusitis with orbital apex syndrome due to Pseudomonas aeruginosa infection. She had received insulin and dialysis for diabtes and diabetic nephropathy, moreover anticoagulants after heart by-pass surgery. She underwent endoscopic sinus operation and was treated with antibiotics, but her loss of left vision did not improve. Recently, sinusitis cases due to Pseudomonas aeruginosa were reported to be a increasing. Therefore, we should consider the possibility of Pseudomonas aeruginosa as well as mycosis as infections of the sinus, especially inpatients who are immunocompromised body. PMID:24765368

  8. Research on the treatment of Pseudomonas aeruginosa pneumonia in children by macrolide antibiotics

    PubMed Central

    Huang, Xu-qiang; Deng, Li; Lu, Gen; He, Chun-hui; Wu, Pei-qiong; Xie, Zhi-wei; Ashraf, Muhammad Aqeel

    2015-01-01

    To observe a therapeutic effect of macrolide antibiotics in children with Pseudomonas aeruginosa pneumonia. Fifty-four cases of children with Pseudomonas aeruginosa pneumonia were randomly divided into an observation group (n=30) and a control group (n=24). The observation group was treated with macrolide antibiotics and cefoperazone/sulbactam. The control group was treated with cefoperazone/sulbactam during a course of 10–14 days. The total effective rate was 93.3% in the observation group, and 58.3% in the control group, and results in the observation group were superior to the control group notably (P>0.05). There were no significant differences in bacterial clearance rate, adverse reaction rate between two groups (P>0.05). The combined application of cefoperazone/sulbactam with macrolide antibiotics to treat Pseudomonas aeruginosa pneumonia in children would be a more effective clinical method. PMID:28352740

  9. Multidrug resistant Pseudomonas aeruginosa infection in children undergoing chemotherapy and hematopoietic stem cell transplantation

    PubMed Central

    Caselli, Désirée; Cesaro, Simone; Ziino, Ottavio; Zanazzo, Giulio; Manicone, Rosaria; Livadiotti, Susanna; Cellini, Monica; Frenos, Stefano; Milano, Giuseppe M.; Cappelli, Barbara; Licciardello, Maria; Beretta, Chiara; Aricò, Maurizio; Castagnola, Elio

    2010-01-01

    Pseudomonas aeruginosa is one leading gram-negative organism associated with nosocomial infections. Bacteremia is life-threatening in the immunocompromised host. Increasing frequency of multi-drug-resistant (MDRPA) strains is concerning. We started a retrospective survey in the pediatric hematology oncology Italian network. Between 2000 and 2008, 127 patients with Pseudomonas aeruginosa bacteremia were reported from 12 centers; 31.4% of isolates were MDRPA. Death within 30 days of a positive blood culture occurred in 19.6% (25/127) of total patients; in patients with MDRPA infection it occurred in 35.8% (14/39). In the multivariate analysis, only MDRPA had significant association with infection-related death. This is the largest series of Pseudomonas aeruginosa bacteremia cases from pediatric hematology oncology centers. Monitoring local bacterial isolates epidemiology is mandatory and will allow empiric antibiotic therapy to be tailored to reduce fatalities. PMID:20305140

  10. Strong incidence of Pseudomonas aeruginosa on bacterial rrs and ITS genetic structures of cystic fibrosis sputa

    PubMed Central

    Pages-Monteiro, Laurence; Marti, Romain; Commun, Carine; Alliot, Nolwenn; Bardel, Claire; Meugnier, Helene; Perouse-de-Montclos, Michele; Reix, Philippe; Durieu, Isabelle; Durupt, Stephane; Vandenesch, Francois; Freney, Jean; Cournoyer, Benoit; Doleans-Jordheim, Anne

    2017-01-01

    Cystic fibrosis (CF) lungs harbor a complex community of interacting microbes, including pathogens like Pseudomonas aeruginosa. Meta-taxogenomic analysis based on V5-V6 rrs PCR products of 52 P. aeruginosa-positive (Pp) and 52 P. aeruginosa-negative (Pn) pooled DNA extracts from CF sputa suggested positive associations between P. aeruginosa and Stenotrophomonas and Prevotella, but negative ones with Haemophilus, Neisseria and Burkholderia. Internal Transcribed Spacer analyses (RISA) from individual DNA extracts identified three significant genetic structures within the CF cohorts, and indicated an impact of P. aeruginosa. RISA clusters Ip and IIIp contained CF sputa with a P. aeruginosa prevalence above 93%, and of 24.2% in cluster IIp. Clusters Ip and IIIp showed lower RISA genetic diversity and richness than IIp. Highly similar cluster IIp RISA profiles were obtained from two patients harboring isolates of a same P. aeruginosa clone, suggesting convergent evolution in the structure of their microbiota. CF patients of cluster IIp had received significantly less antibiotics than patients of clusters Ip and IIIp but harbored the most resistant P. aeruginosa strains. Patients of cluster IIIp were older than those of Ip. The effects of P. aeruginosa on the RISA structures could not be fully dissociated from the above two confounding factors but several trends in these datasets support the conclusion of a strong incidence of P. aeruginosa on the genetic structure of CF lung microbiota. PMID:28282386

  11. VDUP1 exacerbates bacteremic shock in mice infected with Pseudomonas aeruginosa.

    PubMed

    Piao, Zheng-Hao; Kim, Mi Sun; Jeong, Mira; Yun, Sohyun; Lee, Suk Hyung; Sun, Hu-Nan; Song, Hae Young; Suh, Hyun-Woo; Jung, Haiyoung; Yoon, Suk Ran; Kim, Tae-Don; Lee, Young-Ho; Choi, Inpyo

    2012-11-01

    Vitamin-D3 upregulated protein-1 (VDUP1) is a stress response protein. Pseudomonas aeruginosa (P. aeruginosa) infection is a leading cause of death. Mice infected with live P. aeruginosa exhibit significantly decreased VDUP1 expression. However, the function of VDUP1 during P. aeruginosa-induced mouse bacteremic shock is unknown. To address the function of VDUP1 in P. aeruginosa-infected mice, we constructed a bacteremic shock model wherein both wild-type and VDUP1-deficient mice were infected intra-peritoneally with live P. aeruginosa. We found that VDUP1-deficient mice were more resistant to P. aeruginosa-induced bacteremic shock than wild-type mice, as shown by the increased survival, accelerated bacterial clearance and suppression of cytokine overproduction of the VDUP1-deficient mice. VDUP1 promoted the recruitment of neutrophils into the peritoneal cavities of infected mice. VDUP1 impeded the phagocytosis of non-opsonized P. aeruginosa via phosphatidylinositide 3-kinase (PI3K) pathway in macrophages. P. aeruginosa infection induced the generation of reactive oxygen species (ROS), and the increased production of ROS by the peritoneal cells of VDUP1-deficient mice was advantageous in clearing the bacteria. Overall, VDUP1 aggravates bacteremic shock; thus, VDUP1 can be considered a target molecule for the inhibition of P. aeruginosa-induced bacteremic shock.

  12. Nosocomial Infections with IMP-19−Producing Pseudomonas aeruginosa Linked to Contaminated Sinks, France

    PubMed Central

    Amoureux, Lucie; Riedweg, Karena; Chapuis, Angélique; Bador, Julien; Siebor, Eliane; Péchinot, André; Chrétien, Marie-Lorraine; de Curraize, Claire

    2017-01-01

    We isolated IMP-19–producing Pseudomonas aeruginosa from 7 patients with nosocomial infections linked to contaminated sinks in France. We showed that blaIMP-19 was located on various class 1 integrons among 8 species of gram-negative bacilli detected in sinks: P. aeruginosa, Achromobacter xylosoxidans, A. aegrifaciens, P. putida, Stenotrophomonas maltophilia, P. mendocina, Comamonas testosteroni, and Sphingomonas sp. PMID:28098548

  13. Antibiotic Tolerance Induced by Lactoferrin in Clinical Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

    PubMed Central

    Andrés, María T.; Viejo-Diaz, Mónica; Pérez, Francisco; Fierro, José F.

    2005-01-01

    Lactoferrin-induced cell depolarization and a delayed tobramycin-killing effect on Pseudomonas aeruginosa cells were correlated. This antibiotic tolerance effect (ATE) reflects the ability of a defense protein to modify the activity of an antibiotic as a result of its modulatory effect on bacterial physiology. P. aeruginosa isolates from cystic fibrosis patients showed higher ATE values (≤6-fold) than other clinical strains. PMID:15793153

  14. Influence of phenolic acids on indole acetic acid production and on the type III secretion system gene transcription in food-associated Pseudomonas fluorescens KM05.

    PubMed

    Myszka, Kamila; Schmidt, Marcin T; Olejnik-Schmidt, Agnieszka K; Leja, Katarzyna; Czaczyk, Katarzyna

    2014-12-01

    The purpose of these investigations was to evaluate the reduction capability of phenolic acids (ferulic, chlorogenic, gallic, and p-coumaric acids) on indole acetic acid synthesis by food-associated Pseudomonas fluorescens KM05. Specific genetic primer for the type III secretion system (TTSS) in P. fluorescens KM05 was designed and the influence of phenolic acids on its expression was investigated. In the work the ferulic and chlorogenic acids at the concentration of 0.02 and 0.04 μg/ml affected on bacterial growth pattern and the signal molecules production. The phenolic acids, that were appreciable effective against P. fluorescens KM05 indole acetic acid production, significantly suppressed TTSS gene.

  15. Swimming Behavior of Pseudomonas aeruginosa Studied by Holographic 3D Tracking

    PubMed Central

    Vater, Svenja M.; Weiße, Sebastian; Maleschlijski, Stojan; Lotz, Carmen; Koschitzki, Florian; Schwartz, Thomas; Obst, Ursula; Rosenhahn, Axel

    2014-01-01

    Holographic 3D tracking was applied to record and analyze the swimming behavior of Pseudomonas aeruginosa. The obtained trajectories allow to qualitatively and quantitatively analyze the free swimming behavior of the bacterium. This can be classified into five distinct swimming patterns. In addition to the previously reported smooth and oscillatory swimming motions, three additional patterns are distinguished. We show that Pseudomonas aeruginosa performs helical movements which were so far only described for larger microorganisms. Occurrence of the swimming patterns was determined and transitions between the patterns were analyzed. PMID:24498187

  16. Metabolic profile of sodium dodecyl sulphate (SDS) biodegradation by Pseudomonas aeruginosa (MTCC 10311).

    PubMed

    Ambily, P S; Jisha, M S

    2014-09-01

    Sodium dodecyl sulfate (SDS) is one of the main components in the detergent and cosmetic industries. Its bioremediation by suitable microorganism has received greater attention. Pseudomonas aeruginosa MTCC 10311 was isolated from detergent contaminated soil which had degraded 96% of SDS in 48 hrs. Attempts were made to study the metabolic byproducts of SDS degradation using GC-MS analysis. Analysis of ether extracts of surfactant established the sequential production of Dodecanol, Dodecanal and Decanoic acid. At this point, the pathway diverged into the formation of acid residues through beta oxidation. This SDS degrading isolate, Pseudomonas aeruginosa can be exploited for decontamination of detergent contaminated waste water.

  17. Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation

    PubMed Central

    Smadhi, Meriem; Gingras, Marc; Abderrahim, Raoudha

    2014-01-01

    Summary Readily accessible, low-valency glycoclusters based on a triazine core bearing D-galactose and L-fucose epitopes are able to inhibit biofilm formation by Pseudomonas aeruginosa. These multivalent ligands are simple to synthesize, are highly soluble, and can be either homofunctional or heterofunctional. The galactose-decorated cluster shows good affinity for Pseudomonas aeruginosa lectin lecA. They are convenient biological probes for investigating the roles of lecA and lecB in biofilm formation. PMID:25246957

  18. Biodegradation of methyl parathion and endosulfan using Pseudomonas aeruginosa and Trichoderma viridae.

    PubMed

    Senthilkumar, S; Anthonisamy, A; Arunkumar, S; Sivakumari, V

    2011-01-01

    Microorganisms play an important role in the bioconversion and total breakdown of pesticides in the environment. This study was conducted to assess the pesticide degradation (endosulfan and methyl parathion) ability of the bacteria and fungi (Pseudomonas aeruginosa and Trichoderma viridae). The screening test conducted to reveal the ability to degrade endosulfan and methyl parathion shows that Trichoderma viridae was effective compared to Pseudomonas aeruginosa. The pesticide degradation was estimated by optical density method. Methyl parathion was highly degraded compared to endosulfan. This study clearly proves that pesticides and their residue degradation can be accelerated by employing microbes which can be effectively utilized both as biocontrol agent and soil cleanser.

  19. Post-translational modifications in Pseudomonas aeruginosa revolutionized by proteomic analysis.

    PubMed

    Ouidir, Tassadit; Jouenne, Thierry; Hardouin, Julie

    2016-06-01

    Pseudomonas aeruginosa is an opportunistic pathogen that causes severe infections in vulnerable individuals. It is known that post-translational modifications (PTMs) play a key role in bacterial physiology. Their characterization is still challenging and the recent advances in proteomics allow large-scale and high-throughput analyses of PTMs. Here, we provide an overview of proteomic data about the modified proteins in P. aeruginosa. We emphasize the significant contribution of proteomics in knowledge enhancement of PTMs (phosphorylation, N-acetylation and glycosylation) and we discuss their importance in P. aeruginosa physiology.

  20. Pseudomonas aeruginosa porphobilinogen synthase assembly state regulators: hit discovery and initial SAR studies

    PubMed Central

    Reitz, Allen B.; Ramirez, Ursula D.; Stith, Linda; Du, Yanming; Smith, Garry R.; Jaffe, Eileen K.

    2010-01-01

    Porphobilinogen synthase (PBGS) catalyzes the first common step in the biosynthesis of the essential heme, chlorophyll and vitamin B12 heme pigments. PBGS activity is regulated by assembly state, with certain oligomers exhibiting biological activity and others either partially or completely inactive, affording an innovative means of allosteric drug action. Pseudomonas aeruginosa PBGS is functionally active as an octamer, and inactive as a dimer. We have identified a series of compounds that stabilize the inactive P. aeruginosa dimer by a computational prescreen followed by native PAGE gel mobility shift analysis. From those results, we have prepared related thiadiazoles and evaluated their ability to regulate P. aeruginosa PBGS assembly state. PMID:21643541

  1. Specific cleavage of human type III and IV collagens by Pseudomonas aeruginosa elastase.

    PubMed Central

    Heck, L W; Morihara, K; McRae, W B; Miller, E J

    1986-01-01

    Purified Pseudomonas aeruginosa elastase cleaved human type III and IV collagens with the formation of specific cleavage products. Furthermore, type I collagen appeared to be slowly cleaved by both P. aeruginosa elastase and alkaline protease. These cleavage fragments from type III and IV collagens were separated from the intact collagen chains by SDS polyacrylamide gradient gel electrophoresis run under reducing conditions, and they were detected by their characteristic Coomassie blue staining pattern. The results of these studies suggest that the pathogenesis of tissue invasion and hemorrhagic tissue necrosis observed in P. aeruginosa infections may be related to the degradation of these collagen types by bacterial extracellular proteases. Images PMID:3079727

  2. R-type pyocin is required for competitive growth advantage between Pseudomonas aeruginosa strains.

    PubMed

    Heo, Yun-Jeong; Chung, In-Young; Choi, Kelly B; Cho, You-Hee

    2007-01-01

    R-type pyocin is a bacteriophage tail-shaped bacteriocin produced by Pseudomonas aeruginosa, but its physiological roles are relatively unknown. Here we describe a role of R-type pyocin in the competitive growth advantages between P. aeruginosa strains. Partial purification and gene disruption revealed that the major killing activity from the culture supernatant of PA14 is attributed to R-type pyocin, neither F-type nor S-type pyocins. These findings may provide insight into the forces governing P. aeruginosa population dynamics to promote and maintain its biodiversity.

  3. Enzyme-Mediated Quenching of the Pseudomonas Quinolone Signal (PQS) Promotes Biofilm Formation of Pseudomonas aeruginosa by Increasing Iron Availability

    PubMed Central

    Tettmann, Beatrix; Niewerth, Christine; Kirschhöfer, Frank; Neidig, Anke; Dötsch, Andreas; Brenner-Weiss, Gerald; Fetzner, Susanne; Overhage, Joerg

    2016-01-01

    The 2-alkyl-3-hydroxy-4(1H)-quinolone 2,4-dioxygenase HodC was previously described to cleave the Pseudomonas quinolone signal, PQS, which is exclusively used in the complex quorum sensing (QS) system of Pseudomonas aeruginosa, an opportunistic pathogen employing QS to regulate virulence and biofilm development. Degradation of PQS by exogenous addition of HodC to planktonic cells of P. aeruginosa attenuated production of virulence factors, and reduced virulence in planta. However, proteolytic cleavage reduced the efficacy of HodC. Here, we identified the secreted protease LasB of P. aeruginosa to be responsible for HodC degradation. In static biofilms of the P. aeruginosa PA14 lasB::Tn mutant, the catalytic activity of HodC led to an increase in viable biomass in newly formed but also in established biofilms, and reduced the expression of genes involved in iron metabolism and siderophore production, such as pvdS, pvdL, pvdA, and pvdQ. This is likely due to an increase in the levels of bioavailable iron by degradation of PQS, which is able to sequester iron from the surrounding environment. Thus, HodC, despite its ability to quench the production of virulence factors, is contraindicated for combating P. aeruginosa biofilms. PMID:28018312

  4. Bacteriophages of Pseudomonas aeruginosa: long-term prospects for use in phage therapy.

    PubMed

    Krylov, Victor N

    2014-01-01

    Bacteria Pseudomonas aeruginosa, being opportunistic pathogens, are the major cause of nosocomial infections and, in some cases, the primary cause of death. They are virtually untreatable with currently known antibiotics. Phage therapy is considered as one of the possible approaches to the treatment of P. aeruginosa infections. Difficulties in the implementation of phage therapy in medical practice are related, for example, to the insufficient number and diversity of virulent phages that are active against P. aeruginosa. Results of interaction of therapeutic phages with bacteria in different conditions and environments are studied insufficiently. A little is known about possible interactions of therapeutic phages with resident prophages and plasmids in clinical strains in the foci of infections. This chapter highlights the different approaches to solving these problems and possible ways to expand the diversity of therapeutic P. aeruginosa phages and organizational arrangements (as banks of phages) to ensure long-term use of phages in the treatment of P. aeruginosa infections.

  5. Assessment of biofilm formation in Pseudomonas aeruginosa by antisense mazE-PNA.

    PubMed

    Valadbeigi, Hassan; Sadeghifard, Nourkhoda; Salehi, Majid Baseri

    2017-03-01

    The hallmark patogenicity in Pseudomonas aeruginosa (P. aeruginosa) is biofilm formation that is not easy to eradicate, because it has variety mechanisms for antibiotic resistance. In addition, toxin-antitoxin (TA) system may play role in biofilm formation. The current study aimed to evaluate the role of TA loci in biofilm formation. Therefore, 18 P. aeruginosa clinical isolates were collected and evaluated for specific biofilm and TA genes. The analysis by RT-qPCR demonstrated that expression of mazE antitoxin in biofilm formation was increase. On the other hand, mazE antitoxin TA system was used as target for antisense PNA. mazE-PNA was able to influence in biofilm formation and was inhibit at 5,10 and 15 μM concentrations biofilm formation in P. aeruginosa. Therefore, it could be highlighted target for anti-biofilm target to eradicate P. aeruginosa biofilm producer.

  6. Pseudomonas aeruginosa PAO1 resistance to Zinc pyrithione: phenotypic changes suggest the involvement of efflux pumps.

    PubMed

    Abdel Malek, Suzanne M; Al-Adham, Ibrahim S; Matalka, Khalid Z; Collier, Philip J

    2009-08-01

    The aim of this study is to investigate the involvement of an efflux pump in the development of Pseudomonas aeruginosa resistance to zinc pyrithione (ZnPT). In the presence of efflux inhibitor carbonyl cyanide m-chlorophenyl-hydrazone (CCCP), the minimum inhibitory concentration of ZnPT for P. aeruginosa resistant cells is reduced significantly (p < 0.05). In addition, the concentration of ZnPT excluded by the resistant bacteria was reduced significantly (p < 0.01). However, the above reductions did not reach the levels measured for P. aeruginosa PAO1 sensitive strain. Furthermore, such changes in P. aeruginosa resistant cells were correlated with the overexpression of outer membrane proteins, reduced sensitivity toward imipenem (p < 0.01) and increased sensitivity toward sulphatriad and chloramphenicol (p < 0.05). In a continuation to a previous study, we conclude that P. aeruginosa resistance to ZnPT is multifactorial and involves induced efflux systems.

  7. Insights into the respiratory tract microbiota of patients with cystic fibrosis during early Pseudomonas aeruginosa colonization

    DOE PAGES

    Keravec, Marlène; Mounier, Jérôme; Prestat, Emmanuel; ...

    2015-08-09

    Pseudomonas aeruginosa plays a major role in cystic fibrosis (CF) progression. Therefore, it is important to understand the initial steps of P. aeruginosa infection. The structure and dynamics of CF respiratory tract microbial communities during the early stages of P. aeruginosa colonization were characterized by pyrosequencing and cloning-sequencing. The respiratory microbiota showed high diversity, related to the young age of the CF cohort (mean age 10 years). Wide inter- and intra-individual variations were revealed. A common core microbiota of 5 phyla and 13 predominant genera was found, the majority of which were obligate anaerobes. A few genera were significantly moremore » prevalent in patients never infected by P. aeruginosa. Persistence of an anaerobic core microbiota regardless of P. aeruginosa status suggests a major role of certain anaerobes in the pathophysiology of lung infections in CF. Some genera may be potential biomarkers of pulmonary infection state.« less

  8. Insights into the respiratory tract microbiota of patients with cystic fibrosis during early Pseudomonas aeruginosa colonization

    SciTech Connect

    Keravec, Marlene; Mounier, Jerome; Prestat , Emmanuel; Vallet, Sophie; Jansson, Janet K.; Bergaud , Gaetaqn; Rosec, Silvain; Gourious, Stephanie; Rault, Gilles; Coton, Emmanuel; Barbier, George; Hery-Arnaud, Geneveieve

    2015-08-09

    Abstract Pseudomonas aeruginosa plays a major role in cystic fibrosis (CF) progression. Therefore, it is important to understand the initial steps of P. aeruginosa infection. The structure and dynamics of CF respiratory tract microbial communities during the early stages of P. aeruginosa colonization were characterized by pyrosequencing and cloning-sequencing. The respiratory microbiota showed high diversity, related to the young age of the CF cohort (mean age 10 years). Wide inter- and intra-individual variations were revealed. A common core microbiota of 5 phyla and 13 predominant genera was found, the majority of which were obligate anaerobes. A few genera were significantly more prevalent in patients never infected by P. aeruginosa. Persistence of an anaerobic core microbiota regardless of P. aeruginosa status suggests a major role of certain anaerobes in the pathophysiology of lung infections in CF. Some genera may be potential biomarkers of pulmonary infection state.

  9. Pseudomonas aeruginosa on vinyl-canvas inflatables and foam teaching aids in swimming pools.

    PubMed

    Schets, F M; van den Berg, H H J L; Baan, R; Lynch, G; de Roda Husman, A M

    2014-12-01

    Swimming pool-related Pseudomonas aeruginosa infections mainly result in folliculitis and otitis externa. P. aeruginosa forms biofilms on surfaces in the swimming pool environment. The presence of P. aeruginosa on inflatables and foam teaching aids in 24 public swimming pools in the Netherlands was studied. Samples (n = 230) were taken from 175 objects and analysed for P. aeruginosa by culture. Isolated P. aeruginosa were tested for antibiotic resistance by disk diffusion. P. aeruginosa was detected in 63 samples (27%), from 47 objects (27%) in 19 (79%) swimming pools. More vinyl-canvas objects (44%) than foam objects (20%) were contaminated, as were wet objects (43%) compared to dry objects (13%). Concentrations were variable, and on average higher on vinyl-canvas than on foam objects. Forty of 193 (21%) P. aeruginosa isolates from 11 different objects were (intermediate) resistant to one or more of 12 clinically relevant antibiotics, mostly to imipenem and aztreonam. The immediate risk of a P. aeruginosa infection from exposure to swimming pool objects seems limited, but the presence of P. aeruginosa on pool objects is unwanted and requires attention of pool managers and responsible authorities. Strict drying and cleaning policies are needed for infrequently used vinyl-canvas objects.

  10. Cystic fibrosis transmembrane conductance regulator and caveolin-1 regulate epithelial cell internalization of Pseudomonas aeruginosa

    PubMed Central

    Bajmoczi, Milan; Gadjeva, Mihaela; Alper, Seth L.; Pier, Gerald B.; Golan, David E.

    2009-01-01

    Patients with cystic fibrosis (CF) exhibit defective innate immunity and are susceptible to chronic lung infection with Pseudomonas aeruginosa. To investigate the molecular bases for the hypersusceptibility of CF patients to P. aeruginosa, we used the IB3-1 cell line with two defective CF transmembrane conductance regulator (CFTR) genes (ΔF508/W1282X) to generate isogenic stable, clonal lung epithelial cells expressing wild-type (WT)-CFTR with an NH2-terminal green fluorescent protein (GFP) tag. GFP-CFTR exhibited posttranslational modification, subcellular localization, and anion transport function typical of WT-CFTR. P. aeruginosa internalization, a component of effective innate immunity, required functional CFTR and caveolin-1, as shown by: 1) direct correlation between GFP-CFTR expression levels and P. aeruginosa internalization; 2) enhanced P. aeruginosa internalization by aminoglycoside-induced read through of the CFTR W1282X allele in IB3-1 cells; 3) decreased P. aeruginosa internalization following siRNA knockdown of GFP-CFTR or caveolin-1; and 4) spatial association of P. aeruginosa with GFP-CFTR and caveolin-1 at the cell surface. P. aeruginosa internalization also required free lateral diffusion of GFP-CFTR, allowing for bacterial coclustering with GFP-CFTR and caveolin-1 at the plasma membrane. Thus efficient initiation of innate immunity to P. aeruginosa requires formation of an epithelial “internalization platform” involving both caveolin-1 and functional, laterally mobile CFTR. PMID:19386787

  11. Cystic fibrosis transmembrane conductance regulator and caveolin-1 regulate epithelial cell internalization of Pseudomonas aeruginosa.

    PubMed

    Bajmoczi, Milan; Gadjeva, Mihaela; Alper, Seth L; Pier, Gerald B; Golan, David E

    2009-08-01

    Patients with cystic fibrosis (CF) exhibit defective innate immunity and are susceptible to chronic lung infection with Pseudomonas aeruginosa. To investigate the molecular bases for the hypersusceptibility of CF patients to P. aeruginosa, we used the IB3-1 cell line with two defective CF transmembrane conductance regulator (CFTR) genes (DeltaF508/W1282X) to generate isogenic stable, clonal lung epithelial cells expressing wild-type (WT)-CFTR with an NH(2)-terminal green fluorescent protein (GFP) tag. GFP-CFTR exhibited posttranslational modification, subcellular localization, and anion transport function typical of WT-CFTR. P. aeruginosa internalization, a component of effective innate immunity, required functional CFTR and caveolin-1, as shown by: 1) direct correlation between GFP-CFTR expression levels and P. aeruginosa internalization; 2) enhanced P. aeruginosa internalization by aminoglycoside-induced read through of the CFTR W1282X allele in IB3-1 cells; 3) decreased P. aeruginosa internalization following siRNA knockdown of GFP-CFTR or caveolin-1; and 4) spatial association of P. aeruginosa with GFP-CFTR and caveolin-1 at the cell surface. P. aeruginosa internalization also required free lateral diffusion of GFP-CFTR, allowing for bacterial coclustering with GFP-CFTR and caveolin-1 at the plasma membrane. Thus efficient initiation of innate immunity to P. aeruginosa requires formation of an epithelial "internalization platform" involving both caveolin-1 and functional, laterally mobile CFTR.

  12. Synthesis, processing, and transport of Pseudomonas aeruginosa elastase.

    PubMed

    Kessler, E; Safrin, M

    1988-11-01

    Three cell-associated elastase precursors with approximate molecular weights of 60,000 (P), 56,000 (Pro I), and 36,000 (Pro II) were identified in Pseudomonas aeruginosa cells by pulse-labeling with [35S]methionine and immunoprecipitation. In the absence of inhibitors, cells of a wild-type strain as well as those of the secretion-defective mutant PAKS 18 accumulated Pro II as the only elastase-related radioactive protein. EDTA but not EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] inhibited the formation of Pro II, and this inhibition was accompanied by the accumulation of Pro I. P accumulated in cells labeled in the presence of ethanol (with or without EDTA), dinitrophenol plus EDTA, or carbonyl cyanide m-chlorophenyl hydrazone plus EDTA. Pro I and Pro II were localized to the periplasm, and as evident from pulse-chase experiments, Pro I was converted to the mature extracellular enzyme with Pro II as an intermediate of the reaction. P was located to the membrane fraction. Pro I but not Pro II was immunoprecipitated by antibodies specific to a protein of about 20,000 molecular weight (P20), which, as we showed before (Kessler and Safrin, J. Bacteriol. 170:1215-1219, 1988), forms a complex with an inactive periplasmic elastase precursor of about 36,000 molecular weight. Our results suggest that the elastase is made by the cells as a preproenzyme (P), containing a signal sequence of about 4,000 molecular weight and a "pro" sequence of about 20,000 molecular weight. Processing and export of the preproenzyme involve the formation of two periplasmic proenzyme species: proelastase I (56 kilodaltons [kDa]) and proelastase II (36 kDa). The former is short-lived, whereas proelastase II accumulates temporarily in the periplasm, most likely as a complex with the 20-kDa propeptide released from proelastase I upon conversion to proelastase II. The final step in elastase secretion seems to required both the proteolytic removal of a small peptide

  13. Pseudomonas fluorescens Transportome Is Linked to Strain-Specific Plant Growth Promotion in Aspen Seedlings under Nutrient Stress

    PubMed Central

    Shinde, Shalaka; Cumming, Jonathan R.; Collart, Frank R.; Noirot, Philippe H.; Larsen, Peter E.

    2017-01-01

    Diverse communities of bacteria colonize plant roots and the rhizosphere. Many of these rhizobacteria are symbionts and provide plant growth promotion (PGP) services, protecting the plant from biotic and abiotic stresses and increasing plant productivity by providing access to nutrients that would otherwise be unavailable to roots. In return, these symbiotic bacteria receive photosynthetically-derived carbon (C), in the form of sugars and organic acids, from plant root exudates. PGP activities have been characterized for a variety of forest tree species and are important in C cycling and sequestration in terrestrial ecosystems. The molecular mechanisms of these PGP activities, however, are less well-known. In a previous analysis of Pseudomonas genomes, we found that the bacterial transportome, the aggregate activity of a bacteria's transmembrane transporters, was most predictive for the ecological niche of Pseudomonads in the rhizosphere. Here, we used Populus tremuloides Michx. (trembling aspen) seedlings inoculated with one of three Pseudomonas fluorescens strains (Pf0-1, SBW25, and WH6) and one Pseudomonas protegens (Pf-5) as a laboratory model to further investigate the relationships between the predicted transportomic capacity of a bacterial strain and its observed PGP effects in laboratory cultures. Conditions of low nitrogen (N) or low phosphorus (P) availability and the corresponding replete media conditions were investigated. We measured phenotypic and biochemical parameters of P. tremuloides seedlings and correlated P. fluorescens strain-specific transportomic capacities with P. tremuloides seedling phenotype to predict the strain and nutrient environment-specific transporter functions that lead to experimentally observed, strain, and media-specific PGP activities and the capacity to protect plants against nutrient stress. These predicted transportomic functions fall in three groups: (i) transport of compounds that modulate aspen seedling root

  14. Complete genome sequence of Pseudomonas fluorescens strain PICF7, an indigenous root endophyte from olive (Olea europaea L.) and effective biocontrol agent against Verticillium dahliae

    PubMed Central

    2015-01-01

    Pseudomonas fluorescens strain PICF7 is a native endophyte of olive roots. Previous studies have shown this motile, Gram-negative, non-sporulating bacterium is an effective biocontrol agent against the soil-borne fungus Verticillium dahliae, the causal agent of one of the most devastating diseases for olive (Olea europaea L.) cultivation. Here, we announce and describe the complete genome sequence of Pseudomonas fluorescens strain PICF7 consisting of a circular chromosome of 6,136,735 bp that encodes 5,567 protein-coding genes and 88 RNA-only encoding genes. Genome analysis revealed genes predicting factors such as secretion systems, siderophores, detoxifying compounds or volatile components. Further analysis of the genome sequence of PICF7 will help in gaining insights into biocontrol and endophytism. PMID:25685259

  15. Ambroxol inhibits mucoid conversion of Pseudomonas aeruginosa and contributes to the bactericidal activity of ciprofloxacin against mucoid P. aeruginosa biofilms.

    PubMed

    Wang, Wenlei; Yu, Jialin; He, Yu; Wang, Zhengli; Li, Fang

    2016-07-01

    Pseudomonas aeruginosa is an opportunistic human pathogen that can cause severe infections in immunocompromised individuals. Because it forms biofilms, which protect against host immune attack and increase resistance to conventional antibiotics, mucoid P. aeruginosa is nearly impossible to eradicate. Moreover, mucoid conversion of P. aeruginosa in cystic fibrosis (CF) patients leads to poor outcomes. This conversion is mainly due to mucA gene mutation, which is thought to be induced by polymorphonuclear leukocytes (PMNs) and the reactive oxygen species they release. Ambroxol, a mucolytic agent with antioxidant characteristics, is used clinically, and this compound has recently been demonstrated to possess anti-biofilm properties. In this study, we found that ambroxol inhibits the H2 O2 -mediated conversion of P. aeruginosa from a non-mucoid to a mucoid phenotype, an effect that is due to its antioxidant property against H2 O2 . Furthermore, the bactericidal activity of ciprofloxacin against mucoid P. aeruginosa biofilms was increased in vitro when used in combination with ambroxol.

  16. Draft Genome Sequence of the Plant Growth-Promoting Rhizobacterium Pseudomonas fluorescens Strain CREA-C16 Isolated from Pea (Pisum sativum L.) Rhizosphere

    PubMed Central

    Sorrentino, Roberto; Scotti, Riccardo; Salzano, Melania; Aurilia, Vincenzo

    2017-01-01

    ABSTRACT Herein, we report the draft genome sequence of Pseudomonas fluorescens strain CREA-C16, a plant growth-promoting rhizobacterium that was isolated from the rhizosphere of Pisum sativum L. plants. The genome sequence is ~6 Mb in size, with a G+C content of 60.1%, and includes 4,457 candidate protein-encoding genes. PMID:28126933

  17. Effect of growth temperature and pH on the aminopeptidase activity of Pseudomonas putida, P. fluorescens and Flavobacterium odoratum; the 4-nitroaniline test is reliable.

    PubMed

    Lopez-Tomas, L A; Ordoñez, J A; Mediavilla, C; Rodriguez-Marin, J L; Sarmiento, P; Zamora, A; Garcia de Fernando, G

    2008-01-01

    No significant difference (p > 0.05) was observed in the specific aminopeptidase activity (SAA) developed by Pseudomonas fluorescens, P. putida and Flavobacterium odoratum either growing at pH 5.0-6.5 or at 7 and 12 degrees C. Nevertheless, a significant difference was found when comparing the SAA of these organisms. The SAA of F. odoratum was lower than those of pseudomonads. The 4-nitroaniline test is reliable to estimate the G(-) load of fresh food products.

  18. The EmhABC efflux pump decreases the efficiency of phenanthrene biodegradation by Pseudomonas fluorescens strain LP6a.

    PubMed

    Adebusuyi, Abigail A; Smith, Angela Y; Gray, Murray R; Foght, Julia M

    2012-08-01

    Pseudomonas fluorescens strain LP6a, designated here as strain WEN (wild-type PAH catabolism, efflux positive), utilizes the polycyclic aromatic hydrocarbon phenanthrene as a carbon source but also extrudes it into the extracellular medium using the efflux pump EmhABC. Because phenanthrene is considered a nontoxic carbon source for P. fluorescens WEP, its energy-dependent efflux seems counter-productive. We hypothesized that the efflux of phenanthrene would decrease the efficiency of its biodegradation. Indeed, an emhB disruptant strain, wild-type PAH catabolism, efflux negative (WEN), biodegraded 44% more phenanthrene than its parent strain WEP during a 6-day incubation. To determine whether efflux affected the degree of oxidation of phenanthrene, we quantified the conversion of ¹⁴C-phenanthrene to radiolabeled polar metabolites and ¹⁴CO₂. The emhB⁻ WEN strain produced approximately twice as much ¹⁴CO₂ and radiolabeled water-soluble metabolites as the WEP strain. In contrast, the mineralization of ¹⁴C-glucose, which is not a known EmhB efflux substrate, was equivalent in both strains. An early open-ring metabolite of phenanthrene, trans-4-(1-hydroxynaphth-2-yl)-2-oxo-3-butenoic acid, also was found to be a substrate of the EmhABC pump and accumulated in the supernatant of WEP but not WEN cultures. The analogous open-ring metabolite of dibenzothiophene, a heterocyclic analog of phenanthrene, was extruded by EmhABC plus a putative alternative efflux pump, whereas the end product 3-hydroxy-2-formylbenzothiophene was not actively extruded from either WEP or WEN cells. These results indicate that the active efflux of phenanthrene and its early metabolite(s) decreases the efficiency of phenanthrene degradation by the WEP strain. This activity has implications for the bioremediation and biocatalytic transformation of polycyclic aromatic hydrocarbons and heterocycles.

  19. The role of hydrodynamic stress on the phenotypic characteristics of single and binary biofilms of Pseudomonas fluorescens.

    PubMed

    Simões, M; Pereira, M O; Vieira, M J

    2007-01-01

    This study investigates the phenotype of turbulent (Re = 5,200) and laminar (Re = 2,000) flow-generated Pseudomonas fluorescens biofilms. Three P. fluorescens strains, the type strain ATCC 13525 and two strains isolated from an industrial processing plant, D3-348 and D3-350, were used throughout this study. The isolated strains were used to form single and binary biofilms. The biofilm physiology (metabolic activity, cellular density, mass, extracellular polymeric substances, structural characteristics and outer membrane proteins [OMP] expression) was compared. The results indicate that, for every situation, turbulent flow-generated biofilms were more active (p < 0.05), had more mass per cm(2) (p < 0.05), a higher cellular density (p < 0.05), distinct morphology, similar matrix proteins (p > 0.1) and identical (isolated strains -single and binary biofilms) and higher (type strain) matrix polysaccharides contents (p < 0.05) than laminar flow-generated biofilms. Flow-generated biofilms formed by the type strain revealed a considerably higher cellular density and amount of matrix polysaccharides than single and binary biofilms formed by the isolated strains (p < 0.05). Similar OMP expression was detected for the several single strains and for the binary situation, not dependent on the hydrodynamic conditions. Binary biofilms revealed an equal coexistence of the isolated strains with apparent neutral interactions. In summary, the biofilms formed by the type strain represent, apparently, the worst situation in a context of control. The results obtained clearly illustrate the importance of considering strain variation and hydrodynamics in biofilm development, and complement previous studies which have focused on physical aspects of structural and density differences.

  20. Conversion of Sterically Demanding α,α-Disubstituted Phenylacetonitriles by the Arylacetonitrilase from Pseudomonas fluorescens EBC191

    PubMed Central

    Baum, Stefanie; Williamson, Dael S.; Sewell, Trevor

    2012-01-01

    The nitrilase from Pseudomonas fluorescens EBC191 converted 2-methyl-2-phenylpropionitrile, which contains a quaternary carbon atom in the α-position toward the nitrile group, and also similar sterically demanding substrates, such as 2-hydroxy-2-phenylpropionitrile (acetophenone cyanohydrin) or 2-acetyloxy-2-methylphenylacetonitrile. 2-Methyl-2-phenylpropionitrile was hydrolyzed to almost stoichiometric amounts of the corresponding acid. Acetophenone cyanohydrin was transformed to the corresponding acid (atrolactate) and amide (atrolactamide) at a ratio of about 3.4:1. The (R)-acid and the (S)-amide were formed preferentially from acetophenone cyanohydrin. A homology model of the nitrilase suggested that steric hindrance with amino acid residue Tyr54 could impair the binding or conversion of sterically demanding substrates. Therefore, several enzyme variants that carried mutations in the respective residues were generated and subsequently analyzed for the substrate specificity and enantioselectivity of the reactions. Enzyme variants that demonstrated increased relative activities for the conversion of acetophenone cyanohydrin were identified. The chiral analysis of these reactions demonstrated peculiar reaction kinetics, which suggested that the enzyme variants converted the nonpreferred (S)-enantiomer of acetophenone cyanohydrin with a higher reaction rate than that of the (preferred) (R)-enantiomer. Recombinant whole-cell catalysts that simultaneously produced the nitrilase from P. fluorescens EBC191 and a plant-derived (S)-oxynitrilase from cassava (Manihot esculenta) converted acetophenone plus cyanide at pH 4.5 to (S)-atrolactate and (S)-atrolactamide. These recombinant cells are promising catalysts for the synthesis of stable chiral quaternary carbon centers from ketones. PMID:22020513

  1. Negative regulation of germination-arrest factor production in Pseudomonas fluorescens WH6 by a putative extracytoplasmic function sigma factor.

    PubMed

    Okrent, Rachel A; Halgren, Anne B; Azevedo, Mark D; Chang, Jeff H; Mills, Dallice I; Maselko, Maciej; Armstrong, Donald J; Banowetz, Gary M; Trippe, Kristin M

    2014-11-01

    Pseudomonas fluorescens WH6 secretes a germination-arrest factor (GAF) that we have identified previously as 4-formylaminooxyvinylglycine. GAF irreversibly inhibits germination of the seeds of numerous grassy weeds and selectively inhibits growth of the bacterial plant pathogen Erwinia amylovora. WH6-3, a mutant that has lost the ability to produce GAF, contains a Tn5 insertion in prtR, a gene that has been described previously in some strains of P. fluorescens as encoding a transmembrane regulator. As in these other pseudomonads, in WH6, prtR occurs immediately downstream of prtI, which encodes a protein homologous to extracytoplasmic function (ECF) sigma factors. These two genes have been proposed to function as a dicistronic operon. In this study, we demonstrated that deletion of prtI in WT WH6 had no effect on GAF production. However, deletion of prtI in the WH6-3 mutant overcame the effects of the Tn5 insertion in prtR and restored GAF production in the resulting double mutant. Complementation of the double prtIR mutant with prtI suppressed GAF production. This overall pattern of prtIR regulation was also observed for the activity of an AprX protease. Furthermore, reverse transcription quantitative real-time PCR analysis demonstrated that alterations in GAF production were mirrored by changes in the transcription of two putative GAF biosynthetic genes. Thus, we concluded that PrtI exerted a negative regulatory effect on GAF production, although the mechanism has not yet been determined. In addition, evidence was obtained that the transcription of prtI and prtR in WH6 may be more complex than predicted by existing models.

  2. Pseudomonas fluorescens F113 Can Produce a Second Flagellar Apparatus, Which Is Important for Plant Root Colonization

    PubMed Central

    Barahona, Emma; Navazo, Ana; Garrido-Sanz, Daniel; Muriel, Candela; Martínez-Granero, Francisco; Redondo-Nieto, Miguel; Martín, Marta; Rivilla, Rafael

    2016-01-01

    The genomic sequence of Pseudomonas fluorescens F113 has shown the presence of a 41 kb cluster of genes that encode the production of a second flagellar apparatus. Among 2,535 pseudomonads strains with sequenced genomes, these genes are only present in the genomes of F113 and other six strains, all but one belonging to the P. fluorescens cluster of species, in the form of a genetic island. The genes are homologous to the flagellar genes of the soil bacterium Azotobacter vinelandii. Regulation of these genes is mediated by the flhDC master operon, instead of the typical regulation in pseudomonads, which is through fleQ. Under laboratory conditions, F113 does not produce this flagellum and the flhDC operon is not expressed. However, ectopic expression of the flhDC operon is enough for its production, resulting in a hypermotile strain. This flagellum is also produced under laboratory conditions by the kinB and algU mutants. Genetic analysis has shown that kinB strongly represses the expression of the flhDC operon. This operon is activated by the Vfr protein probably in a c-AMP dependent way. The strains producing this second flagellum are all hypermotile and present a tuft of polar flagella instead of the single polar flagellum produced by the wild-type strain. Phenotypic variants isolated from the rhizosphere produce this flagellum and mutation of the genes encoding it, results in a defect in competitive colonization, showing its importance for root colonization. PMID:27713729

  3. Interaction between Medicago truncatula and Pseudomonas fluorescens: evaluation of costs and benefits across an elevated atmospheric CO(2).

    PubMed

    Lepinay, Clémentine; Rigaud, Thierry; Salon, Christophe; Lemanceau, Philippe; Mougel, Christophe

    2012-01-01

    Soil microorganisms play a key role in both plants nutrition and health. Their relation with plant varies from mutualism to parasitism, according to the balance of costs and benefits for the two partners of the interaction. These interactions involved the liberation of plant organic compounds via rhizodeposition. Modification of atmospheric CO(2) concentration may affect rhizodeposition and as a consequence trophic interactions that bind plants and microorganisms. Positive effect of elevated CO(2) on plants are rather well known but consequences for micoorganisms and their interactions with plants are still poorly understood. A gnotobiotic system has been developed to study the interaction between Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12 under two atmospheric CO(2) concentrations: ambient (365 ppm) versus enriched (750 ppm). Costs and benefits for each partner have been determined over time by measuring plant development and growth, the C and N contents of the various plant parts and the density of the bacteria in rhizosphere compartments. Following the increase in CO(2), there was a beneficial effect of P. fluorescens C7R12 on development, vegetative growth, and C/N content of M. truncatula. Concerning plant reproduction, an early seed production was noticed in presence of the bacterial strain combined with increased atmospheric CO(2) conditions. Paradoxically, this transient increase in seed production was correlated with a decrease in bacterial density in the rhizosphere soil, revealing a cost of increased CO(2) for the bacterial strain. This shift of costs-benefits ratio disappeared later during the plant growth. In conclusion, the increase in CO(2) concentration modifies transiently the cost-benefit balance in favor of the plant. These results may be explained either by a competition between the two partners or a change in bacterial physiology. The ecosystem functioning depends on the stability of many

  4. Quinolone signaling in the cell-to-cell communication system of Pseudomonas aeruginosa

    PubMed Central

    Pesci, Everett C.; Milbank, Jared B. J.; Pearson, James P.; McKnight, Susan; Kende, Andrew S.; Greenberg, E. Peter; Iglewski, Barbara H.

    1999-01-01

    Numerous species of bacteria use an elegant regulatory mechanism known as quorum sensing to control the expression of specific genes in a cell-density dependent manner. In Gram-negative bacteria, quorum sensing systems function through a cell-to-cell signal molecule (autoinducer) that consists of a homoserine lactone with a fatty acid side chain. Such is the case in the opportunistic human pathogen Pseudomonas aeruginosa, which contains two quorum sensing systems (las and rhl) that operate via the autoinducers, N-(3-oxododecanoyl)-l-homoserine lactone and N-butyryl-l-homoserine lactone. The s