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Sample records for probiont pseudomonas fluorescens

  1. Elucidation of the Vibrio anguillarum Genetic Response to the Potential Fish Probiont Pseudomonas fluorescens AH2, Using RNA-Arbitrarily Primed PCR

    PubMed Central

    Holmstrøm, Kim; Gram, Lone

    2003-01-01

    The antagonistic interaction between a potential fish probiont, Pseudomonas fluorescens strain AH2, and its target organism, Vibrio anguillarum, was investigated by studying the genetic response of the target organism when it was exposed to the antagonist. We compared the differential display of arbitrarily PCR-amplified gene transcripts in V. anguillarum serotype O1 when it was exposed to AH2 supernatant with the display of transcripts in nonexposed control cultures. Growth of V. anguillarum was immediately arrested when the organism was exposed to 50% (vol/vol) AH2 supernatant. A total of 10 potentially differentially expressed transcripts were identified. Among these we identified a gene homologous to rpoS that was induced in a dose-dependent manner when V. anguillarum was cultured in media supplemented with sterile filtered supernatant from AH2. rpoS was also induced when growth was arrested with the iron chelator 2,2-dipyridyl. A chromosomal transcript homologous to vibE that participates in vibriobactin synthesis in Vibrio cholerae was also upregulated during AH2 exposure. This transcript could represent a functionally active gene in V. anguillarum involved in biosynthesis of anguibactin or another V. anguillarum siderophore. On the pJM1 plasmid of V. anguillarum serotype O1, a pseudogene designated open reading frame E (ORF E) that contains a frameshift mutation was previously identified. The gene homologous to vibE identified in this study, interestingly, also has significant homology to ORF E on the amino acid level and does not possess the frameshift mutation. Thus, the chromosomally encoded vibE homologue could fulfil the role of the inactive plasmid-encoded ORF E pseudogene. Addition of Fe3+ to the system eliminated the growth arrest, and the genes homologous to rpoS and vibE were not induced. To our knowledge, this is the first study linking rpoS induction to iron starvation. Taken together, the results of this study suggest that a major part of the

  2. 40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 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...

  3. 40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 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...

  4. 40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 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...

  5. 40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 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...

  6. 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...

  7. Maltose metabolism of Pseudomonas fluorescens.

    PubMed Central

    Guffanti, A A; Corpe, W A

    1975-01-01

    Pseudomonas fluorescens W uses maltose exclusively by hydrolyzing it to glucose via an inducible alpha-glucosidase (alpha-D-glucoside glucohydrolase, EC 3.2.1.20). No evidence for phosphorolytic cleavage or oxidation to maltobionic acid was found in this organism. The alpha-glucosidase was totally intracellular and was most active at pH of 7.0. Induction occurred when cells were incubated with maltotriose or maltose. Induction was rapid and easily detectable within the first 5 min after the addition of the inducer. Glucose and its derivatives did not repress induction. Cells growing on DL-alanine or succinate plus maltose exhibited lower levels of alpha-glucosidase than those grown on maltose alone or maltose plus glucose. Induction required both messenger ribonucleic acid and protein synthesis. PMID:240805

  8. 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.

  9. Chromate resistance plasmid in Pseudomonas fluorescens.

    PubMed Central

    Bopp, L H; Chakrabarty, A M; Ehrlich, H L

    1983-01-01

    Chromate resistance of Pseudomonas fluorescens LB300, isolated from chromium-contaminated sediment in the upper Hudson River, was found to be plasmid specified. Loss of the plasmid (pLHB1) by spontaneous segregation or mitomycin C curing resulted in a simultaneous loss of chromate resistance. Subsequent transformation of such strains with purified pLHB1 plasmid DNA resulted in a simultaneous re-acquisition of the chromate resistance phenotype and the plasmid. When pLHB1 was transferred by conjugation to Escherichia coli, the plasmid still conferred chromate resistance. PMID:6309741

  10. 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...

  11. Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM 223

    PubMed Central

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

    2015-01-01

    Pseudomonas fluorescens LBUM 223 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 LBUM 223. PMID:25953163

  12. Complete Genome Sequence of Biocontrol Strain Pseudomonas fluorescens LBUM223.

    PubMed

    Roquigny, Roxane; Arseneault, Tanya; Gadkar, Vijay J; Novinscak, Amy; Joly, David L; Filion, Martin

    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

  13. The Gac Regulon of Pseudomonas fluorescens SBW25

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transcriptome analysis of Pseudomonas fluorescens SBW25 showed that 702 genes were differentially regulated (FC>4, P<0.0001) in a gacS::Tn5 mutant, with 300 and 402 genes up- and down-regulated, respectively. Similar to the Gac-regulon of four other Pseudomonas species, genes involved in motility, b...

  14. 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.

  15. BIOGEOGRAPHY OF 2,4-DIACETYLPHLOROGLUCINOL-PRODUCING PSEUDOMONAS FLUORESCENS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Strains of Pseudomonas fluorescens producing the antibiotic 2,4-diacetylphloroglucinol (phlD+) are biocontrol agents of soilborne pathogens and play a key role in the disease suppressiveness of some soils. Considerable variation among isolates has been observed by using genomic fingerprinting techn...

  16. 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. PMID:9846748

  17. Necrotizing hepatitis in pet birds associated with Pseudomonas fluorescens.

    PubMed

    Jackson, M K; Phillips, S N

    1996-01-01

    Six pet birds, from a flock of 100 birds of various species, died within a 2-day period. Drinking water had recently been changed from potable water to irrigation water. Three birds submitted for necropsy had hepatic necrosis with numerous gram-negative rodshaped bacteria present in necrotic areas and Kuppfer cells. Pseudomonas fluorescens was isolated in pure culture from the livers of all three birds and from other organs. This is the first report of naturally occurring disease in which P. fluorescens was the sole etiologic agent identified. PMID:8790902

  18. Porins of Pseudomonas fluorescens MFO as fibronectin-binding proteins.

    PubMed

    Rebière-Huët, J; Guérillon, J; Pimenta, A L; Di Martino, P; Orange, N; Hulen, C

    2002-09-24

    Bacterial adherence is a complex phenomenon involving specific interactions between receptors, including matricial fibronectin, and bacterial ligands. We show here that fibronectin and outer membrane proteins of Pseudomonas fluorescens were able to inhibit adherence of P. fluorescens to fibronectin-coated wells. We identified at least six fibronectin-binding proteins with molecular masses of 70, 55, 44, 37, 32 and 28 kDa. The presence of native (32 kDa) and heat-modified forms (37 kDa) of OprF was revealed by immuno-analysis and the 44-kDa band was composed of three proteins, their N-terminal sequences showing homologies with Pseudomonas aeruginosa porins (OprD, OprE1 and OprE3). PMID:12393211

  19. 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...

  20. 40 CFR 180.1304 - Pseudomonas fluorescens strain CL145A; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Pseudomonas fluorescens strain CL145A... RESIDUES IN FOOD Exemptions From Tolerances § 180.1304 Pseudomonas fluorescens strain CL145A; exemption... for residues of Pseudomonas fluorescens strain CL145A in or on all food commodities when applied as...

  1. 40 CFR 180.1200 - Pseudomonas fluorescens strain PRA-25; temporary exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 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...

  2. 40 CFR 180.1200 - Pseudomonas fluorescens strain PRA-25; temporary exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 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...

  3. 40 CFR 180.1200 - Pseudomonas fluorescens strain PRA-25; temporary exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 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...

  4. 40 CFR 180.1200 - Pseudomonas fluorescens strain PRA-25; temporary exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 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...

  5. 40 CFR 180.1304 - Pseudomonas fluorescens strain CL145A; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Pseudomonas fluorescens strain CL145A... RESIDUES IN FOOD Exemptions From Tolerances § 180.1304 Pseudomonas fluorescens strain CL145A; exemption... for residues of Pseudomonas fluorescens strain CL145A in or on all food commodities when applied as...

  6. 40 CFR 180.1304 - Pseudomonas fluorescens strain CL145A; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Pseudomonas fluorescens strain CL145A... RESIDUES IN FOOD Exemptions From Tolerances § 180.1304 Pseudomonas fluorescens strain CL145A; exemption... for residues of Pseudomonas fluorescens strain CL145A in or on all food commodities when applied as...

  7. 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...

  8. 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.

  9. Orthophosphite-Nicotinamide Adenine Dinucleotide Oxidoreductase from Pseudomonas fluorescens

    PubMed Central

    Malacinski, George M.; Konetzka, W. A.

    1967-01-01

    Information was obtained on the general properties and specificity of orthophosphite-nicotinamide adenine dinucleotide oxidoreductase. The enzyme was extracted from Pseudomonas fluorescens 195 grown in medium containing orthophosphite as the sole source of phosphorus. An enzyme preparation suitable for characterization was obtained from crude extracts by use of high-speed centrifugation, protamine sulfate precipitation, ammonium sulfate fractionation, and Sephadex gel filtration. The enzyme exhibited maximal activity at pH 7.0, and was inactivated within 6 min at 37 C. Arsenite, hypophosphite, nitrite, selenite, and tellurite were not oxidized by the enzyme. Sulfite inhibited the enzymatic oxidation of orthophosphite in an apparent competitive manner. PMID:4381632

  10. 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

  11. 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

  12. Genomic and Genetic Diversity within the Pseudomonas fluorescens Complex.

    PubMed

    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

  13. Functions Encoded by Pyrrolnitrin Biosynthetic Genes from Pseudomonas fluorescens

    PubMed Central

    Kirner, Sabine; Hammer, Philip E.; Hill, D. Steven; Altmann, Annett; Fischer, Ilona; Weislo, Laura J.; Lanahan, Mike; van Pée, Karl-Heinz; Ligon, James M.

    1998-01-01

    Pyrrolnitrin is a secondary metabolite derived from tryptophan and has strong antifungal activity. Recently we described four genes, prnABCD, from Pseudomonas fluorescens that encode the biosynthesis of pyrrolnitrin. In the work presented here, we describe the function of each prn gene product. The four genes encode proteins identical in size and serology to proteins present in wild-type Pseudomonas fluorescens, but absent from a mutant from which the entire prn gene region had been deleted. The prnA gene product catalyzes the chlorination of l-tryptophan to form 7-chloro-l-tryptophan. The prnB gene product catalyzes a ring rearrangement and decarboxylation to convert 7-chloro-l-tryptophan to monodechloroaminopyrrolnitrin. The prnC gene product chlorinates monodechloroaminopyrrolnitrin at the 3 position to form aminopyrrolnitrin. The prnD gene product catalyzes the oxidation of the amino group of aminopyrrolnitrin to a nitro group to form pyrrolnitrin. The organization of the prn genes in the operon is identical to the order of the reactions in the biosynthetic pathway. PMID:9537395

  14. 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.

  15. 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...

  16. Induction of defense gene homologues in wheat roots during interactions with pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Specific strains of Pseudomonas fluorescens directly inhibit soilborne fungal pathogens of Triticum aestivum (wheat) during colonization of the wheat rhizosphere, but until now the impact of these beneficial bacteria on wheat gene expression was unknown. To test the hypothesis that P. fluorescens i...

  17. 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-...

  18. RHIZOSPHERE COLONIZATION OF TRANSGENIC AND WILD-TYPE PSEUDOMONAS FLUORESCENS IS MODULATED BY THE CROP SPECIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens strain Q8r1-96 (genotype D) produces 2,4-diacetylphloroglucinol (DAPG). Transgenic strain Z30-97, constructed by stably inserting the phenazine-1-carboxylic acid (PCA) biosynthetic locus from P. fluorescens 2-79 into Q8r1-96, produces both antibiotics in vitro and in situ. Th...

  19. 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...

  20. 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

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

    PubMed

    Gamez, Rocío M; Rodríguez, Fernando; Ramírez, Sandra; Gómez, Yolanda; Agarwala, Richa; Landsman, David; Mariño-Ramírez, Leonardo

    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

  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. Pseudomonas putida and Pseudomonas fluorescens Species Group Recovery from Human Homes Varies Seasonally and by Environment

    PubMed Central

    Remold, Susanna K.; Purdy-Gibson, Megan E.; France, Michael T.; Hundley, Thomas C.

    2015-01-01

    By shedding light on variation in time as well as in space, long-term biogeographic studies can help us define organisms’ distribution patterns and understand their underlying drivers. Here we examine distributions of Pseudomonas in and around 15 human homes, focusing on the P. putida and P. fluorescens species groups. We describe recovery from 10,941 samples collected during up to 8 visits per home, occurring on average 2.6 times per year. We collected a mean of 141 samples per visit, from sites in most rooms of the house, from the surrounding yards, and from human and pet occupants. We recovered Pseudomonas in 9.7% of samples, with the majority of isolates being from the P. putida and P. fluorescens species groups (approximately 62% and 23% of Pseudomonas samples recovered respectively). Although representatives of both groups were recovered from every season, every house, and every type of environment sampled, recovery was highly variable across houses and samplings. Whereas recovery of P. putida group was higher in summer and fall than in winter and spring, P. fluorescens group isolates were most often recovered in spring. P. putida group recovery from soils was substantially higher than its recovery from all other environment types, while higher P. fluorescens group recovery from soils than from other sites was much less pronounced. Both species groups were recovered from skin and upper respiratory tract samples from healthy humans and pets, although this occurred infrequently. This study indicates that even species that are able to survive under a broad range of conditions can be rare and variable in their distributions in space and in time. For such groups, determining patterns and causes of stochastic and seasonal variability may be more important for understanding the processes driving their biogeography than the identity of the types of environments in which they can be found. PMID:26023929

  4. 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

  5. Lipase and Protease Double-Deletion Mutant of Pseudomonas fluorescens Suitable for Extracellular Protein Production

    PubMed Central

    Son, Myunghan; Moon, Yuseok; Oh, Mi Jin; Han, Sang Bin; Park, Ki Hyun; Kim, Jung-Gon

    2012-01-01

    Pseudomonas fluorescens, a widespread Gram-negative bacterium, is an ideal protein manufacturing factory (PMF) because of its safety, robust growth, and high protein production. P. fluorescens possesses a type I secretion system (T1SS), which mediates secretion of a thermostable lipase (TliA) and a protease (PrtA) through its ATP-binding cassette (ABC) transporter. Recombinant proteins in P. fluorescens are attached to the C-terminal signal region of TliA for transport as fusion proteins to the extracellular medium. However, intrinsic TliA from the P. fluorescens genome interferes with detection of the recombinant protein and the secreted recombinant protein is hydrolyzed, due to intrinsic PrtA, resulting in decreased efficiency of the PMF. In this research, the lipase and protease genes of P. fluorescens SIK W1 were deleted using the targeted gene knockout method. Deletion mutant P. fluorescens ΔtliA ΔprtA secreted fusion proteins without TliA or protein degradation. Using wild-type P. fluorescens as an expression host, degradation of the recombinant protein varied depending on the type of culture media and aeration; however, degradation did not occur with the P. fluorescens ΔtliA ΔprtA double mutant irrespective of growth conditions. By homologous expression of tliA and the ABC transporter in a plasmid, TliA secreted from P. fluorescens ΔprtA and P. fluorescens ΔtliA ΔprtA cells was found to be intact, whereas that secreted from the wild-type P. fluorescens and P. fluorescens ΔtliA cells was found to be hydrolyzed. Our results demonstrate that the P. fluorescens ΔtliA ΔprtA deletion mutant is a promising T1SS-mediated PMF that enhances production and detection of recombinant proteins in extracellular media. PMID:23042178

  6. 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

  7. pA506: A conjugative plasmid of the plant epiphyte Pseudomonas fluorescens A506

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens A506 is an plant-epiphytic bacterium that is used commercially in the United States for the biological control of fire blight disease of pear and apple. Here, we demonstrate that A506 has a 57 kB conjugative plasmid that can transfer to other strains of Pseudomonas spp. and ...

  8. Genomic Analysis of Antifungal Metabolite Production by Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The complete genomic sequences of several Pseudomonas spp. that inhabit the rhizosphere are now available, providing a new opportunity to advance knowledge of plant-growth promoting rhizobacteria through genomics. Among these is the biological control bacterium Pseudomonas fluorescens Pf-5. Nearly...

  9. Genomic Analysis of Secondary Metabolite Production by Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The complete genomic sequences of several Pseudomonas spp. that live in a commensal relationship with plants are now available. Among these is the biological control bacterium Pseudomonas fluorescens Pf-5. Nearly 6% of the 7.07 Mb genome of Pf-5 is devoted to the biosynthesis of secondary metaboli...

  10. Diluent sensitivity in thermally stressed cells of pseudomonas fluorescens.

    PubMed

    Gray, R J; Ordal, Z J; Witter, L D

    1977-05-01

    Thermally injured cells of Pseudomonas fluorescens were unable to produce colonies on Trypticase soy agar (TSA) after dilution with 0.1% peptone. Nutritional exigency could not be used as the criterion for this injury, since varying the composition of the plating medium had little effect on the number of colonies that developed. The injured cells had no requirement for compounds known to leak out during the heat treatment in order to recover. The cells did not exhibit injury if dilution preceded heat treatment on the plating medium, demonstrating that the heat treatment sensitized the cells to the trauma of dilution. Substitution of 0.1% peptone with growth medium as the diluent largely offset the previously observed drop in TSA count. Little difference in survival was observed when monosodium glutamate or the balance of the defined medium was used as the diluent. The diluent effect was ionic rather than osmotic. The presence of cations was important in maintaining the integrity of the injured cell, and divalent cations enhanced this protective effect. The role of these cations at the level of the cell envelope is discussed. PMID:406839

  11. Uptake of 2, 4-Dichlorophenoxyacetic acid by Pseudomonas fluorescens

    USGS Publications Warehouse

    Wedemeyer, G.A.

    1966-01-01

    WEDEMEYER, GARY (Fish-Pesticide Research Laboratory, Denver, Colo.). Uptake of 2,4-dichlorophenoxyacetic acid by Pseudomonas fluorescens. Appl. Microbiol. 14:486-491. 1966.-Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “nonmetabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carriermediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranylion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

  12. EXAFS Study of Uranyl Complexation at Pseudomonas fluorescens Cell Surfaces

    NASA Astrophysics Data System (ADS)

    Bencheikh, R.; Bargar, J. R.; Tebo, B. M.

    2002-12-01

    Little is known about the roles of microbial biomass as a sink and source for uranium in contaminated aquifers, nor of the impact of bacterial biochemistry on uranium speciation in the subsurface. A significant role is implied by the high affinities of both Gram positive and Gram negative cells for binding uranyl (UO2{ 2+}). In the present study, Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy was used to identify membrane functional groups involved in uranyl binding to the Gram negative bacterium Pseudomonas fluorescens from pH 3 to pH 8. Throughout this pH-range, EXAFS spectra can be described primarily in terms of coordination of carboxylic groups to uranyl. U-C distances characteristic of 4-, 5- and 8- membered rings were observed, as well as the possibility of phosphato groups. Both shell-by-shell fits and principle component analyses indicate that the functional groups involved in binding of uranyl to the cell surface do not vary systematically across the pH range investigated. This result contrasts with EXAFS results of uranyl sorbed to Gram positive bacteria, and suggests an important role for long-chain carboxylate-terminated membrane functional groups in binding uranyl.

  13. Influence of Temperature on Glucose Utilization by Pseudomonas fluorescens1

    PubMed Central

    Palumbo, Samuel A.; Witter, Lloyd D.

    1969-01-01

    The influence of temperature on the conversion of glucose into cell material and into energy for maintenance was determined for Pseudomonas fluorescens by a steady-state turbidity method and by a substrate utilization method. Conversion of glucose into cell material was measured as yield; conversion of glucose into energy for maintenance was measured as specific maintenance, the minimum dilution rate in continuous culture below which a steady state is not possible. The values obtained by the two methods were nearly identical; with both, the yield and specific maintenance decreased with decreasing temperature. The specific maintenance consumption rate (milligrams of glucose taken up per milligram of cell dry weight per hour at zero growth) was also calculated by the substrate utilization method and found to decrease with decreasing temperature. However, the amount of glucose consumed per generation for maintenance increased with decreasing temperature. This increased glucose consumption for maintenance may provide a partial explanation for the decrease in yield at low temperatures. Small amounts of glucose were also converted into pigment at all temperatures tested, with the greatest amount formed at 20 C. PMID:4896876

  14. [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. PMID:18069329

  15. Complete Genome Sequence of the Pseudomonas fluorescens Bacteriophage UFV-P2.

    PubMed

    Eller, Monique R; Salgado, Rafael L; Vidigal, Pedro M P; Alves, Maura P; Dias, Roberto S; de Oliveira, Leandro L; da Silva, Cynthia C; de Carvalho, Antônio F; De Paula, Sérgio O

    2013-01-01

    Milk proteolysis caused by Pseudomonas fluorescens is a serious problem in the dairy industries as a result of its ability to grow under refrigeration. The use of phages to control contaminants in food has been considered an alternative to traditional methods; therefore, a thorough understanding of such organisms is vital for their use. In this study, we show the complete genome sequence and analysis of a P. fluorescens phage isolated from wastewater of a dairy industry in Brazil. PMID:23405322

  16. Organophosphonate utilization by the wild-type strain of Pseudomonas fluorescens.

    PubMed

    Zboińska, E; Lejczak, B; Kafarski, P

    1992-09-01

    The wild-type strain of Pseudomonas fluorescens was found to utilize a range of structurally diverse organophosphonates as its sole carbon or nitrogen sources. Representative compounds included aminoalkylphosphonates, hydroxyalkylphosphonates, oxoalkylphosphonates, and phosphono dipeptides. Among them, amino(phenyl)methylphosphonate,2-aminoethylphosphonate, aminomethylphosphonate, diisopropyl 9-aminofluoren-9-ylphosphonate, and 2-oxoalkylphosphonates were used by P. fluorescens as its sole sources of phosphorus. Only slight growth was observed on the herbicide glyphosate (N-phosphonomethylglycine), which was metabolized to aminomethylphosphonate. Neither phosphinothricin nor its dialanyl tripeptide, bialaphos, supported growth of P. fluorescens. The possible mechanisms of organophosphonate degradation by this strain are discussed. PMID:1444412

  17. Organophosphonate utilization by the wild-type strain of Pseudomonas fluorescens.

    PubMed Central

    Zboińska, E; Lejczak, B; Kafarski, P

    1992-01-01

    The wild-type strain of Pseudomonas fluorescens was found to utilize a range of structurally diverse organophosphonates as its sole carbon or nitrogen sources. Representative compounds included aminoalkylphosphonates, hydroxyalkylphosphonates, oxoalkylphosphonates, and phosphono dipeptides. Among them, amino(phenyl)methylphosphonate,2-aminoethylphosphonate, aminomethylphosphonate, diisopropyl 9-aminofluoren-9-ylphosphonate, and 2-oxoalkylphosphonates were used by P. fluorescens as its sole sources of phosphorus. Only slight growth was observed on the herbicide glyphosate (N-phosphonomethylglycine), which was metabolized to aminomethylphosphonate. Neither phosphinothricin nor its dialanyl tripeptide, bialaphos, supported growth of P. fluorescens. The possible mechanisms of organophosphonate degradation by this strain are discussed. PMID:1444412

  18. Spread of Pseudomonas fluorescens due to contaminated drinking water in a bone marrow transplant unit.

    PubMed

    Wong, Vanessa; Levi, Katrina; Baddal, Buket; Turton, Jane; Boswell, Tim C

    2011-06-01

    Pseudomonas infections are an important cause of morbidity and mortality in immunocompromised patients. We present here data for the spread of Pseudomonas fluorescens caused by a contaminated drinking water dispenser in a bone marrow transplant unit. Over a 1-month period we observed a sharp increase in the isolation of P. fluorescens from weekly pharyngeal surveillance swabs. Environmental samples were taken from a variety of water sources throughout the unit. These samples were cultured on cetrimide agar medium, and isolates were epidemiologically characterized by antibiotic susceptibility patterns and molecular typing methods. Nine patients became colonized with P. fluorescens, and six out of the nine developed febrile neutropenia. P. fluorescens was cultured after the filtration of 100 ml of drinking water from one of two stand-alone chiller units supplying cooled bottled water to the bone marrow transplant unit. All other environmental samples were negative. There were no further cases of P. fluorescens colonization after the contaminated dispenser was removed. Molecular typing showed that all P. fluorescens isolates were identical by both random amplification of polymorphic DNA PCR and pulsed-field gel electrophoresis. We recommend that such bottled water supplies not be used in high-risk areas or be subject to regular microbiological monitoring. PMID:21450958

  19. Toxicity assessment of xenobiotic contaminated groundwater using lux modified Pseudomonas fluorescens.

    PubMed

    Boyd, E M; Killham, K; Wright, J; Rumford, S; Hetheridge, M; Cumming, R; Meharg, A A

    1997-11-01

    A bacterial bioassay, suitable for rapid screening to assess the relative toxicity of xenobiotic contaminated groundwater has been developed. The quantitative bioassay utilizes a decline in luminescence of the lux marked soil bacterium Pseudomonas fluorescens on exposure to contaminated groundwaters from which effective concentration (EC) values can be assessed and compared. P. fluorescens was most sensitive to semivolatile organics in groundwaters but there was no correlation between EC value and chemical content. The sensitivity and reproducibility of the P. fluorescens bioassay was compared with that of Microtox and results showed that mean EC50 values for diluted ground water replicate samples were 20% and 18% respectively. This suggested that the P. fluorescens bioassay was as applicable to groundwater screening as the widely used Microtox bioassay. PMID:9353912

  20. 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...

  1. Sensitivity of Pseudomonas fluorescens to gamma irradiation following surface inoculations on romaine lettuce and baby spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Irradiation of fresh fruits and vegetables is a post-harvest intervention measure often used to inactivate pathogenic food-borne microbes. We evaluated the sensitivity of Pseudomonas fluorescens strains (2-79, Q8R1, Q287) to gamma irradiation following surface inoculations on romaine lettuce and spi...

  2. 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...

  3. A Novel Gene Cluster Encoding an Insect Toxin in Plant-Associated Strains of Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens CHA0 and the related strain Pf-5 are well-characterized rhizosphere bacteria that have the capacity to protect crop plants from fungal root diseases, mainly by releasing a variety of exoproducts that are toxic to plant pathogenic fungi. Here, we report that the two plant-bene...

  4. 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.

  5. 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....

  6. Isolation and Identification of Rhizoxin Derivatives from Pseudomonas fluorescens Pf-5 using a Genomic Mining Strategy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The products synthesized from a hybrid polyketide synthase/nonribosomal peptide synthetase gene cluster in the genome of Pseudomonas fluorescens Pf-5 were identified using a genomics-guided strategy involving insertional mutagenesis and subsequent metabolite profiling. Five analogs of rhizoxin, a 1...

  7. 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. ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 lifes...

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

    PubMed

    Town, Jennifer; Cui, Nina; Audy, Patrice; Boyetchko, Sue; Dumonceaux, Tim J

    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

  10. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens Pf-5 is a plant-associated bacterium that inhabits the rhizosphere of a wide variety of plant species and produces secondary metabolites suppressive of fungal and oomycete plant pathogens. The Pf-5 genome is rich in features consistent with its commensal lifestyle, but has re...

  12. Bioinformatic Analysis of TonB-Dependent Receptors of Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  13. 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...

  14. 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...

  15. 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

  16. 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...

  17. 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. ...

  18. 76 FR 52871 - Pseudomonas fluorescens Strain CL145A; Exemption From the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-24

    ...) 305-5805. II. Background and Statutory Findings In the Federal Register of March 16, 2009 (74 FR 11100... tolerance (40 CFR 180.1129) in the Federal Register of August 24, 1994 (59 FR 43490) (FRL-4899-5); 2... Federal Register of September 16, 1992 (57 FR 42700) (FRL-4161-1); and 3. Pseudomonas fluorescens...

  19. 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...

  20. 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 ...

  1. Efficacy of Pseudomonas fluorescens for biocontrol of Escherichia coli 0157:H7 on spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of foodborne pathogens on leafy green vegetables is crucial for consumer food safety. Biocontrol microbes may inhibit or suppress foodborne pathogen growth and enhance existing post-harvest intervention controls. The efficacy of Pseudomonas fluorescens for biocontrol of Escherichia coli O157...

  2. 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

  3. Switching catalysis from hydrolysis to perhydrolysis in Pseudomonas fluorescens esterase.

    PubMed

    Yin, De Lu Tyler; Bernhardt, Peter; Morley, Krista L; Jiang, Yun; Cheeseman, Jeremy D; Purpero, Vincent; Schrag, Joseph D; Kazlauskas, Romas J

    2010-03-01

    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 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(cat), but K(m) also increased so the specificity constant, k(cat)/K(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 epsilon-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the active site blocks access

  4. Efflux as a glutaraldehyde resistance mechanism in Pseudomonas fluorescens and Pseudomonas aeruginosa biofilms.

    PubMed

    Vikram, Amit; Bomberger, Jennifer M; Bibby, Kyle J

    2015-01-01

    A major challenge in microbial biofilm control is biocide resistance. Phenotypic adaptations and physical protective effects have been historically thought to be the primary mechanisms for glutaraldehyde resistance in bacterial biofilms. Recent studies indicate the presence of genetic mechanisms for glutaraldehyde resistance, but very little is known about the contributory genetic factors. Here, we demonstrate that efflux pumps contribute to glutaraldehyde resistance in Pseudomonas fluorescens and Pseudomonas aeruginosa biofilms. The RNA-seq data show that efflux pumps and phosphonate degradation, lipid biosynthesis, and polyamine biosynthesis metabolic pathways were induced upon glutaraldehyde exposure. Furthermore, chemical inhibition of efflux pumps potentiates glutaraldehyde activity, suggesting that efflux activity contributes to glutaraldehyde resistance. Additionally, induction of known modulators of biofilm formation, including phosphonate degradation, lipid biosynthesis, and polyamine biosynthesis, may contribute to biofilm resistance and resilience. Fundamental understanding of the genetic mechanism of biocide resistance is critical for the optimization of biocide use and development of novel disinfection strategies. Our results reveal genetic components involved in glutaraldehyde resistance and a potential strategy for improved control of biofilms. PMID:25824217

  5. Efflux as a Glutaraldehyde Resistance Mechanism in Pseudomonas fluorescens and Pseudomonas aeruginosa Biofilms

    PubMed Central

    Vikram, Amit; Bomberger, Jennifer M.

    2015-01-01

    A major challenge in microbial biofilm control is biocide resistance. Phenotypic adaptations and physical protective effects have been historically thought to be the primary mechanisms for glutaraldehyde resistance in bacterial biofilms. Recent studies indicate the presence of genetic mechanisms for glutaraldehyde resistance, but very little is known about the contributory genetic factors. Here, we demonstrate that efflux pumps contribute to glutaraldehyde resistance in Pseudomonas fluorescens and Pseudomonas aeruginosa biofilms. The RNA-seq data show that efflux pumps and phosphonate degradation, lipid biosynthesis, and polyamine biosynthesis metabolic pathways were induced upon glutaraldehyde exposure. Furthermore, chemical inhibition of efflux pumps potentiates glutaraldehyde activity, suggesting that efflux activity contributes to glutaraldehyde resistance. Additionally, induction of known modulators of biofilm formation, including phosphonate degradation, lipid biosynthesis, and polyamine biosynthesis, may contribute to biofilm resistance and resilience. Fundamental understanding of the genetic mechanism of biocide resistance is critical for the optimization of biocide use and development of novel disinfection strategies. Our results reveal genetic components involved in glutaraldehyde resistance and a potential strategy for improved control of biofilms. PMID:25824217

  6. Effect of GABA, a bacterial metabolite, on Pseudomonas fluorescens surface properties and cytotoxicity.

    PubMed

    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

  7. 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

  8. An Improved, High-Quality Draft Genome Sequence of the Germination-Arrest Factor-Producing Pseudomonas fluorescens WH6

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens is a genetically and physiologically diverse species of bacteria present in many habitats and in association with plants. This species of bacteria produces a large array of secondary metabolites with potential as natural products. P. fluorescens isolate WH6 produces Germinati...

  9. 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...

  10. Phloroglucinol mediates crosstalk between the pyoluteorin and 2,4-diacetylphloroglucinol biosynthetic pathways in Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The antibiotics pyoluteorin and 2,4-diacetylphloroglucinol (DAPG) are involved in the biological control of certain soil-borne diseases by some strains of Pseudomonas fluorescens, including P. fluorescens Pf-5. These secondary metabolites also act as signaling molecules with each compound reported ...

  11. Involvement of a phospholipase C in the hemolytic activity of a clinical strain of Pseudomonas fluorescens

    PubMed Central

    Rossignol, Gaelle; Merieau, Annabelle; Guerillon, Josette; Veron, Wilfried; Lesouhaitier, Olivier; Feuilloley, Marc GJ; Orange, Nicole

    2008-01-01

    Background Pseudomonas fluorescens is a ubiquitous Gram-negative bacterium frequently encountered in hospitals as a contaminant of injectable material and surfaces. This psychrotrophic bacterium, commonly described as unable to grow at temperatures above 32°C, is now considered non pathogenic. We studied a recently identified clinical strain of P. fluorescens biovar I, MFN1032, which is considered to cause human lung infection and can grow at 37°C in laboratory conditions. Results We found that MFN1032 secreted extracellular factors with a lytic potential at least as high as that of MF37, a psychrotrophic strain of P. fluorescens or the mesophilic opportunistic pathogen, Pseudomonas aeruginosa PAO1. We demonstrated the direct, and indirect – through increases in biosurfactant release – involvement of a phospholipase C in the hemolytic activity of this bacterium. Sequence analysis assigned this phospholipase C to a new group of phospholipases C different from those produced by P. aeruginosa. We show that changes in PlcC production have pleiotropic effects and that plcC overexpression and plcC extinction increase MFN1032 toxicity and colonization, respectively. Conclusion This study provides the first demonstration that a PLC is involved in the secreted hemolytic activity of a clinical strain of Pseudomonas fluorescens. Moreover, this phospholipase C seems to belong to a complex biological network associated with the biosurfactant production. PMID:18973676

  12. 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

  13. Pseudomonas fluorescens alters epithelial permeability and translocates across Caco-2/TC7 intestinal cells

    PubMed Central

    2010-01-01

    Background Pseudomonas fluorescens has long been considered as a psychrotrophic microorganism. Recently, we have shown that clinical strains of P. fluorescens (biovar 1) are able to adapt at a growth temperature of 37°C or above and induce a specific inflammatory response. Interestingly, a highly specific antigen of P. fluorescens, I2, is detected in the serum of patients with Crohn's disease but the possible role of this bacterium in the disease has not yet been explored. In the present study, we examined the ability of a psychrotrophic and a clinical strain of P. fluorescens to modulate the permeability of a Caco-2/TC7 intestinal epithelial model, reorganize the actin cytoskeleton, invade the target cells and translocate across the epithelium. The behaviour of these two strains was compared to that of the well known opportunistic pathogen P. aeruginosa PAO1. Results Both strains of P. fluorescens were found to decrease the transepithelial resistance (TER) of Caco-2/TC7 differentiated monolayers. This was associated with an increase in paracellular permeability and F-actin microfilaments rearrangements. Moreover, the invasion and translocation tests demonstrated that the two strains used in this study can invade and translocate across the differentiated Caco-2/TC7 cell monolayers. Conclusions The present work shows for the first time, that P. fluorescens is able to alter the intestinal epithelial barrier function by disorganizing the F-actin microfilament network. Moreover, we reveal that independently of their origins, the two P. fluorescens strains can translocate across differentiated Caco-2/TC7 cell monolayers by using the transcellular pathway. These findings could, at least in part, explain the presence of the P. fluorescens specific I2 antigen in the serum of patients with Crohn's disease. PMID:21110894

  14. 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. PMID:26875795

  15. 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. PMID:25477941

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  17. 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.

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

    PubMed Central

    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. PMID:25477941

  19. Cell-associated hemolysis activity in the clinical strain of Pseudomonas fluorescens MFN1032

    PubMed Central

    2010-01-01

    Background MFN1032 is a clinical Pseudomonas fluorescens strain able to grow at 37°C. MFN1032 cells induce necrosis and apoptosis in rat glial cells at this temperature. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides. Under laboratory conditions, this activity is not expressed at 37°C. This activity is tightly regulated and is subject to phase variation. Results We found that MFN1032 displays a cell-associated hemolytic activity distinct from the secreted hemolytic activity. Cell-associated hemolysis was expressed at 37°C and was only detected in vitro in mid log growth phase in the presence of erythrocytes. We studied the regulation of this activity in the wild-type strain and in a mutant defective in the Gac two-component pathway. GacS/GacA is a negative regulator of this activity. In contrast to the Pseudomonas fluorescens strains PfO-1 and Pf5, whose genomes have been sequenced, the MFN1032 strain has the type III secretion-like genes hrcRST belonging to the hrpU operon. We showed that disruption of this operon abolished cell-associated hemolytic activity. This activity was not detected in P.fluorescens strains carrying similar hrc genes, as for the P. fluorescens psychrotrophic strain MF37. Conclusions To our knowledge this the first demonstration of cell-associated hemolytic activity of a clinical strain of Pseudomonas fluorescens. Moreover, this activity seems to be related to a functional hrpU operon and is independent of biosurfactant production. Precise link between a functional hrpU operon and cell-associated hemolytic activity remains to be elucidated. PMID:20416103

  20. Root cap influences root colonisation by Pseudomonas fluorescens SBW25 on maize.

    PubMed

    Humphris, Sonia N; Bengough, A Glyn; Griffiths, Bryan S; Kilham, Ken; Rodger, Sheena; Stubbs, Vicky; Valentine, Tracy A; Young, Iain M

    2005-09-01

    We investigated the influence of root border cells on the colonisation of seedling Zea mays roots by Pseudomonas fluorescens SBW25 in sandy loam soil packed at two dry bulk densities. Numbers of colony forming units (CFU) were counted on sequential sections of root for intact and decapped inoculated roots grown in loose (1.0 mg m(-3)) and compacted (1.3 mg m(-3)) soil. After two days of root growth, the numbers of P. fluorescens (CFU cm(-1)) were highest on the section of root just below the seed with progressively fewer bacteria near the tip, irrespective of density. The decapped roots had significantly more colonies of P. fluorescens at the tip compared with the intact roots: approximately 100-fold more in the loose and 30-fold more in the compact soil. In addition, confocal images of the root tips grown in agar showed that P. fluorescens could only be detected on the tips of the decapped roots. These results indicated that border cells, and their associated mucilage, prevented complete colonization of the root tip by the biocontrol agent P. fluorescens, possibly by acting as a disposable surface or sheath around the cap. PMID:16329978

  1. Genomics of Secondary Metabolite Production by Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas spp. are prolific producers of secondary metabolites, and the availability of genomic sequences now opens the door for discovery of novel natural products with potential roles in the ecology and plant growth promoting properties of these bacteria. The rhizosphere bacterium Pseudomonas f...

  2. Draft Genome Sequence of Pseudomonas fluorescens Strain ET76, Isolated from Rice Rhizosphere in Northwestern Morocco.

    PubMed

    Aarab, Saida; Arakrak, Abdelhay; Ollero, Francisco Javier; Megías, Manuel; Gomes, Douglas Fabiano; Ribeiro, Renan Augusto; Hungria, Mariangela

    2016-01-01

    Pseudomonas fluorescens ET76 was isolated from rice rhizosphere in northwestern Morocco. Its draft genome was estimated to be 6,681,652 bp with 5,789 coding sequences (CDSs). Genes encoding for type I to VI secretion systems, PvdQ, proteases, siderophores, hydrogen cyanide synthase, ACC-deaminase, among others, highlight its potential use in biological control of plant pathogens. PMID:27198014

  3. Comparison of the growth kinetics and proteolytic activities of Chryseobacterium species and Pseudomonas fluorescens.

    PubMed

    Bekker, A; Steyn, L; Charimba, G; Jooste, P; Hugo, C

    2015-12-01

    The effect of temperature on the growth kinetics and proteolytic activity of Chryseobacterium joostei and Chryseobacterium bovis was determined during this study. The results were compared with the activities of Pseudomonas fluorescens, which is regarded to be a major food spoilage psychrotolerant microorganism. For the growth studies, cultures were incubated in nutrient broth in a temperature gradient incubator (from 9 to 50 °C) and separately at 4 °C, and the optical density was measured at different time intervals. Growth temperature profiles for each organism were constructed. For determination of proteolytic activity, the cultures were incubated in fat-free ultra-high temperature processed milk in the temperature gradient incubator for 72 h (temperature range as above). Cell-free extracts were used to determine the proteolytic activity using the azocasein method. Results of the growth studies showed that C. joostei had the ability to grow over a wider temperature range than C. bovis and P. fluorescens without being affected by changes in the temperature. For the proteolytic activity, C. joostei had significantly (p < 0.001) higher activity per milligram of protein at 15.5 °C, followed by C. bovis and P. fluorescens. The results showed that C. joostei potentially has an even greater spoilage capacity in milk on the basis of growth rate and proteolytic activity than did P. fluorescens. PMID:26451905

  4. Role of Vfr in the regulation of antifungal compound production by Pseudomonas fluorescens FD6.

    PubMed

    Zhang, Qingxia; Ji, Yanyan; Xiao, Qi; Chng, Soonie; Tong, Yunhui; Chen, Xijun; Liu, Fengquan

    2016-01-01

    Pseudomonas fluorescens FD6 has been shown to possess many beneficial traits involved in the biocontrol of fungal plant pathogens, such as Botrytis cinerea and Monilinia fructicola. Vfr (virulence factor regulator) a highly conserved global regulator of gram-negative bacteria, such as the human pathogen Pseudomonas aeruginosa, is required for the expression of many important virulence traits. The role of Vfr in the regulation of biocontrol traits, such as the production of antibiotics to control fungal pathogens by antagonistic bacteria, has not been elucidated. This study investigated the effect of a vfr mutant derived from P. fluorescens FD6 to better understand the regulation of some important biocontrol traits associated with the bacterium. Biochemical studies indicated that the production of the antibiotics 2,4-diacetylphloroglucinol, pyrrolnitrin and pyoluteorin, was markedly enhanced in the vfr mutant. The vfr mutation also increased biofilm production, swimming motility and the expression of exopolysaccharide-associated gene (pelA, pslA and pslB) transcripts, but reduced protease production. Wheat rhizosphere and root tip colonization by the vfr mutant was higher than that by the wild type at 7 and 21days after inoculation. These findings demonstrate that Vfr modulates the expression of several key traits and the production of important antibiotics involved in the biocontrol potential of P. fluorescens FD6. PMID:27296968

  5. The effect of essential oils of basil on the growth of Aeromonas hydrophila and Pseudomonas fluorescens.

    PubMed

    Wan, J; Wilcock, A; Coventry, M J

    1998-02-01

    Basil essential oils, including basil sweet linalool (BSL) and basil methyl chavicol (BMC), were screened for antimicrobial activity against a range of Gram-positive and Gram-negative bacteria, yeasts and moulds using an agar well diffusion method. Both essential oils showed antimicrobial activity against most of the micro-organisms examined except Clostridium sporogenes, Flavimonas oryzihabitans, and three species of Pseudomonas. The minimum inhibitory concentration (MIC) of BMC against Aeromonas hydrophila and Pseudomonas fluorescens in TSYE broth (as determined using an indirect impedance method) was 0.125 and 2% (v/v), respectively; the former was not greatly affected by the increase of challenge inoculum from 10(3) to 10(6) cfu ml-1. Results with resting cells demonstrated that BMC was bactericidal to both Aer. hydrophila and Ps. fluorescens. The growth of Aer. hydrophila in filter-sterilized lettuce extract was completely inhibited by 0.1% (v/v) BMC whereas that of Ps. fluorescens was not significantly affected by 1% (v/v) BMC. In addition, the effectiveness of washing fresh lettuce with 0.1 or 1% (v/v) BMC on survival of natural microbial flora was comparable with that effected by 125 ppm chlorine. PMID:9633630

  6. Extracellular thermostable proteolytic activity of the milk spoilage bacterium Pseudomonas fluorescens PS19 on bovine caseins.

    PubMed

    Stuknytė, M; Decimo, M; Colzani, M; Silvetti, T; Brasca, M; Cattaneo, S; Aldini, G; De Noni, I

    2016-06-01

    We studied the thermostable proteolytic activity of Pseudomonas fluorescens PS19 isolated from raw bovine milk. The heat-treated cell-free supernatant (HT-CFS) contained a thermostable protease of approximately 45 kDa, as revealed by casein zymography. We assigned this enzyme to P. fluorescens AprX metalloprotease (UniProtKB Acc. No. C9WKP6). After concentration by ultrafiltration at 10 kDa, the HT-CFS showed 2 other thermostable proteolytic bands on zymogram, with molecular masses of approximately 15 and 25 kDa. The former resulted a fragment of the AprX protease, whereas the 25-kDa protease was not homologous to any known protein of Pseudomonas spp. Subsequently, we assessed the proteolytic activity of the HT-CFS on bovine αS-, β-, and κ-casein during in vitro incubation at 7 or 22°C. By means of ultra-performance liquid chromatography-tandem mass spectrometry we identified the released peptides (n=591). Some of them resisted proteolysis during the whole incubation period at both incubation temperatures and, therefore, they could be assumed as indicators of the proteolytic action of P. fluorescens PS19 on bovine caseins. PMID:26995139

  7. Possible involvement of Pseudomonas fluorescens and Bacillaceae in structural modifications of Tuber borchii fruit bodies.

    PubMed

    Citterio, B; Malatesta, M; Battistelli, S; Marcheggiani, F; Baffone, W; Saltarelli, R; Stocchi, V; Gazzanelli, G

    2001-03-01

    Previous studies on Tuber borchii fruit bodies in early maturation stages suggested a role of bacteria in sporocarp structural modifications. In order to verify this hypothesis, in the present study we investigated by means of microbial and ultrastructural approaches, the bacterial population of T. borchii sporocarps from intermediate maturation phases to advanced decomposition stages, paying particular attention to chitinolytic and cellulolytic bacteria and to their relationships with ascii and ascospores. We found that Pseudomonas fluorescens and spore-forming Bacillaceae, both able to degrade cellulose and chitin, are present inside the sporocarps in all maturation stages investigated. Moreover, rod-shaped bacteria seem able to erode ascus walls and colonize the interior of ascii containing mature spores. These results suggest a possible role of these bacteria in the process of ascus opening. Moreover, the presence of P. fluorescens and Bacillaceae on isolated mature spores after decontamination suggests an intimate association between these bacteria and the ascospores. PMID:11315117

  8. Association of uranyl with the cell wall of Pseudomonas fluorescens inhibits metabolism

    NASA Astrophysics Data System (ADS)

    Bencheikh-Latmani, Rizlan; Leckie, James O.

    2003-11-01

    Citric acid is found along with uranyl in the subsurface of former nuclear facilities because of its use as a decontamination agent in the nuclear industry. Citrate's metal chelating properties affect the mobility of uranyl in the subsurface and consequently, citrate biodegradation may significantly impact uranyl fate and transport. Under the non-growth conditions considered, low (micromolar) uranyl concentrations inhibit the biodegradation of citrate by Pseudomonas fluorescens, a common subsurface denitrifying bacterium. Additionally, uranyl is found readily associated with the cell envelope of P. fluorescens. The observed inhibition appears to be linked to the binding of uranyl to the cell surface and is reversible by desorbing cell-bound uranyl. This study establishes a link between uranyl association with the cell surface and the observed inhibitory effect of uranyl on cell metabolism.

  9. Oxidation-Reduction Potential and Growth of Clostridium perfringens and Pseudomonas fluorescens1

    PubMed Central

    Tabatabai, L. B.; Walker, H. W.

    1970-01-01

    A new apparatus was developed for measuring changes in Eh, pH, and cell numbers. With this apparatus, the relationships of these parameters were studied at initial Eh levels of 200 and 40 mv (pH 7.0), by using Clostridium perfringens and Pseudomonas fluorescens. One of the strains of C. perfringens grew more luxuriantly at the higher Eh, in the presence of small quantities of oxygen, than at the lower one in the absence of oxygen. P. fluorescens could grow at a relatively low Eh (40 mv, pH 7.0) in pure culture but not in the presence of C. perfringens under the same conditions. PMID:4320922

  10. Production and properties of biosurfactants from a newly isolated Pseudomonas fluorescens HW-6 growing on hexadecane.

    PubMed

    Vasileva-Tonkova, Evgenia; Galabova, Danka; Stoimenova, Emilia; Lalchev, Zdravko

    2006-01-01

    The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g l(-1)) when grown on hexadecane as a sole carbon source. Biosurfactants decreased the surface tension of the air/ water interface by 35 mN m(-1) and possessed a low critical micelle concentration value of 20 mg l(-1), which indicated high surface activity. They efficiently emulsified aromatic hydrocarbons, kerosene, n-paraffins and mineral oils. Biosurfactant production contributed to a significant increase in cell hydrophobicity correlated with an increased growth of the strain on hexadecane. The results suggested that the newly isolated strain of Ps. fluorescens and produced glycolipid biosurfactants with effective surface and emulsifying properties are very promising and could find application for bioremediation of hydrocarbon-polluted sites. PMID:16989316

  11. 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

  12. Analysis of Bacillus thuringiensis Population Dynamics and Its Interaction With Pseudomonas fluorescens in Soil

    PubMed Central

    Rojas-Ruiz, Norma Elena; Sansinenea-Royano, Estibaliz; Cedillo-Ramirez, Maria Lilia; Marsch-Moreno, Rodolfo; Sanchez-Alonso, Patricia; Vazquez-Cruz, Candelario

    2015-01-01

    Background: Bacillus thuringiensis is the most successful biological control agent, however, studies so far have shown that B. thuringiensis is very sensitive to environmental factors such as soil moisture and pH. Ultraviolet light from the sun had been considered as the main limiting factor for its persistence in soil and it has recently been shown that the antagonism exerted by other native soil organisms, such as Pseudomonas fluorescens, is a determining factor in the persistence of this bacterium under in vitro culture conditions. Objectives: The aim of the present investigation was to analyze the population dynamics of B. thuringiensis and its interaction with P. fluorescens using microbiological and molecular methods in soil, under different conditions, and to determinate the effect of nutrients and moisture on its interaction. Materials and Methods: The monitoring was performed by microbiological methods, such as viable count of bacteria, and molecular methods such as Polymerase Chain Reaction (PCR) and hybridization, using the direct extraction of DNA from populations of inoculated soil. Results: The analysis of the interaction between B. thuringiensis and P. fluorescens in soil indicated that the disappearance of B. thuringiensis IPS82 is not dependent on the moisture but the composition of nutrients that may be affecting the secretion of toxic compounds in the environment of P. fluorescens. The results showed that the recovered cells were mostly spores and not vegetative cells in all proved treatments. The molecular methods were effective for monitoring bacterial population inoculated in soil. Conclusions: Bacillus thuringiensis is very sensitive to the interaction of P. fluorescens, however is capable to survive in soil due to its capacity of sporulate. Some of the cells in the form of spores germinated and folded slightly and remained in a constant cycle of sporulation and germination. This confirms that B. thuringiensis IPS82 can germinate, grow and

  13. 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

  14. Antibiotic and antimicrobial peptide combinations: synergistic inhibition of Pseudomonas fluorescens and antibiotic-resistant variants.

    PubMed

    Naghmouchi, Karim; Le Lay, Christophe; Baah, John; Drider, Djamel

    2012-02-01

    Variants resistant to penicillin G (RvP), streptomycin (RvS), lincomycin (RvL) and rifampicin (RvR) were developed from a colistin-sensitive isolate of Pseudomonas fluorescens LRC-R73 (P. fluorescens). Cell fatty acid composition, K(+) efflux and sensitivity to antimicrobial peptides (nisin Z, pediocin PA-1/AcH and colistin) alone or combined with antibiotics were determined. P. fluorescens was highly sensitive to kanamycin, tetracycline and chloramphenicol at minimal inhibitory concentrations of 0.366, 0.305 and 0.732 μg/ml respectively. P. fluorescens, RvP, RvS, RvL and RvR were resistant to nisin Z and pediocin PA-1/AcH at concentrations ≥100 μg/ml but sensitive to colistin at 0.076, 0.043, 0.344, 0.344 and 0.258 μg/ml respectively. A synergistic inhibitory effect (FICI ≤0.5) was observed when resistant variants were treated with peptide/antibiotic combinations. No significant effect on K(+) efflux from the resistant variants in the presence of antibiotics or peptides alone or combined was observed. The proportion of C16:0 was significantly higher in antibiotic-resistant variants than in the parent strain, accounting for 32.3%, 46.49%, 43.3%, 40.1% and 44.1% of the total fatty acids in P. fluorescens, RvP, RvS, RvL and RvR respectively. Combination of antibiotics with antimicrobial peptides could allow reduced use of antibiotics in medical applications and could help slow the emergence of bacteria resistant to antibiotics. PMID:22172555

  15. 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.

  16. Optical characterization of Pseudomonas fluorescens on meat surfaces using time-resolved fluorescence

    NASA Astrophysics Data System (ADS)

    Bouchard, Alain; Frechette, Julie; Vernon, Marcia L.; Cormier, Jean-François; Beaulieu, Rene M.; Vallée, Réal; Mafu, Akier A.

    2006-01-01

    A scanning optical system for the detection of bacteria on meat surfaces based on fluorescence lifetime and intensity measurements is described. The system detects autofluorescent light emitted by naturally occurring fluorophores in bacteria. The technique only requires minimal sample preparation and handling, thus the chemical properties of the specimen are preserved. This work presents the preliminary results obtained from a time-resolved fluorescence imaging system for the characterization of a nonpathogenic gram-negative bacteria, Pseudomonas fluorescens. Initial results indicate that the combination of fluorescence lifetime and intensity measurements provides a means for characterizing biological media and for detecting microorganisms on surfaces.

  17. Influence of Temperature on Substrate and Energy Conversion in Pseudomonas fluorescens1

    PubMed Central

    Mennett, Randall H.; Nakayama, T. O. M.

    1971-01-01

    The influence of temperature on yield, maintenance rate, growth rate, and conversion of calories to biomass was studied with Pseudomonas fluorescens grown in a chemostat. Maintenance and growth rate are influenced linearly with temperature. Both rates increased with increasing temperature and gave linear Arrhenius plots over a limited range. Cells harvested during the steady-state at each temperature were burned in a microcalorimeter. The number of kilocalories per gram (dry weight) of organism was not influenced significantly by the temperature during growth, indicating that the conversion of substrate calories into biomass is apparently regulated in the range of temperature studied. PMID:5002310

  18. 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. PMID:10792522

  19. Cloning and characterization of styrene catabolism genes from Pseudomonas fluorescens ST

    SciTech Connect

    Marconi, A.M.; Solinas, F.; Galli, E.; Bestetti, G.

    1996-01-01

    Styrene is used in large quantities in the manufacturing of plastics, synthetic rubber, and resins. Styrene-utilizing microorganisms have been isolate in consideration of their potential applications as biocatalysts in the removal of styrene in industrial wastes. However, data conserving styrene catabolism in bacteria are not abundant. In this paper the isolated of the Pseudomonas fluorescens ST genes involved in the first steps of styrene degradation are reported as well as the identification of the intermediates accumulated by single recombinant clones. 33 refs., 5 figs., 1 tab.

  20. Pseudomonas fluorescens CHA0 produces enantio-pyochelin, the optical antipode of the Pseudomonas aeruginosa siderophore pyochelin.

    PubMed

    Youard, Zeb A; Mislin, Gaëtan L A; Majcherczyk, Paul A; Schalk, Isabelle J; Reimmann, Cornelia

    2007-12-01

    The siderophore pyochelin is made by a thiotemplate mechanism from salicylate and two molecules of cysteine. In Pseudomonas aeruginosa, the first cysteine residue is converted to its D-isoform during thiazoline ring formation whereas the second cysteine remains in its L-configuration, thus determining the stereochemistry of the two interconvertible pyochelin diastereoisomers as 4'R, 2''R, 4''R (pyochelin I) and 4'R, 2''S, 4''R (pyochelin II). Pseudomonas fluorescens CHA0 was found to make a different stereoisomeric mixture, which promoted growth under iron limitation in strain CHA0 and induced the expression of its biosynthetic genes, but was not recognized as a siderophore and signaling molecule by P. aeruginosa. Reciprocally, pyochelin promoted growth and induced pyochelin gene expression in P. aeruginosa, but was not functional in P. fluorescens. The structure of the CHA0 siderophore was determined by mass spectrometry, thin-layer chromatography, NMR, polarimetry, and chiral HPLC as enantio-pyochelin, the optical antipode of the P. aeruginosa siderophore pyochelin. Enantio-pyochelin was chemically synthesized and confirmed to be active in CHA0. Its potential biosynthetic pathway in CHA0 is discussed. PMID:17938167

  1. Pepsin-digested bovine lactoferrin prevents Mozzarella cheese blue discoloration caused by Pseudomonas fluorescens.

    PubMed

    Caputo, Leonardo; Quintieri, Laura; Bianchi, Daniela Manila; Decastelli, Lucia; Monaci, Linda; Visconti, Angelo; Baruzzi, Federico

    2015-04-01

    The aim of this work was to check the efficacy of bovine lactoferrin hydrolyzed by pepsin (LFH) to prevent blue discoloration of Mozzarella cheese delaying the growth of the related spoilage bacteria. Among 64 Pseudomonas fluorescens strains, isolated from 105 Mozzarella samples, only ten developed blue discoloration in cold-stored Mozzarella cheese slices. When Mozzarella cheese samples from dairy were treated with LFH and inoculated with a selected P. fluorescens strain, no pigmentation and changes in casein profiles were found up to 14 days of cold storage. In addition, starting from day 5, the count of P. fluorescens spoiling strain was steadily ca. one log cycle lower than that of LFH-free samples. ESI-Orbitrap-based mass spectrometry analyses allowed to reveal the pigment leucoindigoidine only in the blue LFH-free cheese samples indicating that this compound could be considered a chemical marker of this alteration. For the first time, an innovative mild approach, based on the antimicrobial activity of milk protein hydrolysates, for counteracting blue Mozzarella event and controlling psychrotrophic pigmenting pseudomonads, is here reported. PMID:25475261

  2. The combined effects of Pseudomonas fluorescens and Tuber melanosporum on the quality of Pinus halepensis seedlings.

    PubMed

    Dominguez, J A; Martin, A; Anriquez, A; Albanesi, A

    2012-08-01

    The ecological, economic and social values of the ectomycorrhizal fungi of the black truffle found in the rural Mediterranean are well known. The inoculation of Pinus halepensis seedlings with mycorrhizal fungi and rhizobacteria can improve the morphology and physiology of the seedlings and benefit the regeneration of arid regions and the reintroduction of inocula of mycorrhizal fungi into these areas. Some rhizobacteria can improve the establishment and functioning of ectomycorrhizal symbiosis. In this study, seedlings of P. halepensis were inoculated with the mycorrhizal fungus Tuber melanosporum and the rhizobacteria Pseudomonas fluorescens CECT 844 under non-limiting greenhouse conditions. Five months after inoculation, we analysed the growth, water parameters (osmotic potential at saturation, osmotic potential at turgor loss and modulus of elasticity), concentrations of mycorrhizal colonies, nutrient concentration and nutrient contents (N, P, K, Ca, Mg and Fe) in roots and aerial parts of the seedlings. Subsequently, tests were performed to estimate the root growth potentials. None of the treatments changed the water parameters or growth potentials of the roots. The inoculations improved the growth and nutrient uptake of the seedlings, although the combination of P. fluorescens CECT 844 and T. melanosporum did not generally lead to a significant improvement over the positive effects of a simple inoculation of T. melanosporum; however, the addition of P. fluorescens CECT 844 did double the rate of the mycorrhization of T. melanosporum. These results may be promising for enhancing the cultivation of truffles. PMID:22068563

  3. 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

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

    PubMed

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

    2016-04-01

    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

  5. 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.

  6. 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. PMID:25754557

  7. Antibacterial activity and mutagenesis of sponge-associated Pseudomonas fluorescens H41.

    PubMed

    Ye, Lumeng; Santos-Gandelman, Juliana F; Hardoim, Cristiane C P; George, Isabelle; Cornelis, Pierre; Laport, Marinella S

    2015-07-01

    Marine sponges (phylum Porifera) are well known to harbour a complex and diverse bacterial community. Some of these sponge-associated bacteria have been shown to be the real producers of secondary metabolites with a wide range of activities from antimicrobials to anticancer agents. Previously, we revealed that the strain Pseudomonas fluorescens H41 isolated from the sponge Haliclona sp. (collected at the coast of Rio de Janeiro, Brazil) showed a strong antimicrobial activity against clinical and marine bacteria. Thus, in this study the genes involved in the antimicrobial activity of P. fluorescens H41 were identified. To this end, a library of mutants was generated via miniTnphoA3 transposon mutagenesis and the resulting clones were characterized for their antimicrobial activity. It was demonstrated that genes involved in the biosynthesis of the pyoverdine siderophore are related to the inhibitory activity of P. fluorescens H41. Therefore, this strain might play an important role in the biocontrol of the host sponge. PMID:25957971

  8. Colonization and bioherbicidal activity on green foxtail by Pseudomonas fluorescens BRG100 in a pesta formulation.

    PubMed

    Caldwell, Caressa J; Hynes, Russell K; Boyetchko, Susan M; Korber, Darren R

    2012-01-01

    Pseudomonas fluorescens BRG100 produces secondary metabolites with herbicidal activity on green foxtail ( Setaria viridis ), an important weed pest in Canadian agriculture. Five gfp transformants of P. fluorescens BRG100 were compared with the wild-type isolate for green foxtail root herbicide activity, i.e., root growth suppression, doubling time, carbon utilization, and colonization of green foxtail root (proximal and distal regions). The most revealing comparison between the wild type and its gfp transformants was herbicidal activity on green foxtail. Herbicidal activity of transformant gfp-7 was not significantly different from the uninoculated control, suggesting that insertion of the gfp gene may have interfered with a gene, or genes, vital to the bioherbicide process. Doubling time, carbon utilization, and colonization of green foxtail did not differ to a great extent between the wild type and the gfp transformants, indicating their suitability as conservatively tagged organisms for subsequent colonization-herbicidal activity studies. Accordingly, a pesta granule formulation delivered transformant gfp-2 to the seed coat and roots of green foxtail. Epifluorescent and confocal laser scanning microscopy revealed the transformant gfp-2 colonized the ventral portion of the seed coat, root hairs, and all areas of the root except the root cap region, where gfp-2 presumably exerted herbicidal effects. These results suggest that P. fluorescens BRG100 has considerable potential as a bioherbicide because of its successful colonization and suppressive activity on green foxtail root growth. PMID:22188391

  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. Di-rhamnolipid is a mosquito pupicidal metabolite from Pseudomonas fluorescens (VCRC B426).

    PubMed

    Prabakaran, G; Hoti, S L; Rao, H Surya Prakash; Vijjapu, Satish

    2015-08-01

    Pseudomonas fluorescens Migula (VCRC B426) produces a secondary metabolite, which was found to be active against pupae of vector mosquitoes namely Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti. The mosquito pupicidal metabolite from P. fluoescens was mass produced and separated by ethyl acetate extraction and purified further by silica gel column chromatography, FPLC, HPLC and TLC. The purified metabolite was characterized by NMR, FT-IR, LC-MS and MALDI-TOF. The FT-IR, (1)H and (13)C NMR results showed that it is a rhamnolipid (di-rhamnolipid). The matrix assisted laser desorption and ionization-time-of-flight spectrum of the sample showed predominant pupicidal component produced by P. fluorescens was the molecule mass of 673.40 Da. Owing to its high toxicity to mosquito pupae, especially Anopheles sp., and Aedes sp., the di-rhamnolipd has potential in the control of the vectors of dengue, chikungunya, yellow fever and malaria. This is the first report of mosquito pupicidal di-rhamnolipid from P. fluorescens. PMID:25912083

  11. Nonribosomal Peptides, Key Biocontrol Components for Pseudomonas fluorescens In5, Isolated from a Greenlandic Suppressive Soil

    PubMed Central

    Michelsen, Charlotte F.; Watrous, Jeramie; Glaring, Mikkel A.; Kersten, Roland; Koyama, Nobuhiro

    2015-01-01

    ABSTRACT Potatoes are cultivated in southwest Greenland without the use of pesticides and with limited crop rotation. Despite the fact that plant-pathogenic fungi are present, no severe-disease outbreaks have yet been observed. In this report, we document that a potato soil at Inneruulalik in southern Greenland is suppressive against Rhizoctonia solani Ag3 and uncover the suppressive antifungal mechanism of a highly potent biocontrol bacterium, Pseudomonas fluorescens In5, isolated from the suppressive potato soil. A combination of molecular genetics, genomics, and matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) imaging mass spectrometry (IMS) revealed an antifungal genomic island in P. fluorescens In5 encoding two nonribosomal peptides, nunamycin and nunapeptin, which are key components for the biocontrol activity by strain In5 in vitro and in soil microcosm experiments. Furthermore, complex microbial behaviors were highlighted. Whereas nunamycin was demonstrated to inhibit the mycelial growth of R. solani Ag3, but not that of Pythium aphanidermatum, nunapeptin instead inhibited P. aphanidermatum but not R. solani Ag3. Moreover, the synthesis of nunamycin by P. fluorescens In5 was inhibited in the presence of P. aphanidermatum. Further characterization of the two peptides revealed nunamycin to be a monochlorinated 9-amino-acid cyclic lipopeptide with similarity to members of the syringomycin group, whereas nunapeptin was a 22-amino-acid cyclic lipopeptide with similarity to corpeptin and syringopeptin. PMID:25784695

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

    DOE PAGESBeta

    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; et al

    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

  13. Pseudomonas fluorescens-like bacteria from the stomach: A microbiological and molecular study

    PubMed Central

    Patel, Saurabh Kumar; Pratap, Chandra Bhan; Verma, Ajay Kumar; Jain, Ashok Kumar; Dixit, Vinod Kumar; Nath, Gopal

    2013-01-01

    AIM: To characterize oxidase- and urease-producing bacterial isolates, grown aerobically, that originated from antral biopsies of patients suffering from acid peptic diseases. METHODS: A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production, acid tolerance and aerobic growth. The selected isolates were further characterized by molecular techniques viz. amplifications for 16S rRNA using universal eubacterial and HSP60 gene specific primers. The amplicons were subjected to restriction analysis and partial sequencing. A phylogenetic tree was generated using unweighted pair group method with arithmetic mean (UPGMA) from evolutionary distance computed with bootstrap test of phylogeny. Assessment of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10-7 mol/L to 10-1 mol/L. RESULTS: Of the 258 antral biopsy specimens collected from patients, 179 (69.4%) were positive for urease production by rapid urease test and 31% (80/258) yielded typical Helicobacter pylori (H. pylori) after 5-7 d of incubation under a microaerophilic environment. A total of 240 (93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight incubation. The partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species. A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens (P. fluorescens). On the basis of HSP60 sequences applied to the UPGMA phylogenetic tree, it was observed that isolated strains in an aerobic environment were likely to be P. fluorescens, and HSP60 sequences had more discriminatory potential rather than 16S rRNA sequences. Interestingly, this bacterium was acid tolerant for hours at low pH. Further, a total of 250 (96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive

  14. Interaction of Pseudomonas fluorescens with Eu(III) and Ce(IV) - Desferrioxamine Complexes

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Ozaki, T.; Ohnuki, T.; Francis, A.

    2002-12-01

    Naturally occurring chelating agents-, such as siderophores, are able to form complexes with actinides and enhance their solubility and mobility in the environment. Adsorption and/or biodegradation of chelated actinides by microorganisms are important processes which regulate their mobility in the natural environment. In this study, association of Eu(III), Ce(IV), and Fe(III) - desferrioxamine B (DFO) complexes with aerobic bacterium, Pseudomonas fluorescens (ATCC 55241), was investigated-, Eu(III) and Ce(IV) were used as analogues to trivalent and tetravalent actinides, respectively. When 20 μM of 1:1 Eu(III) - and Ce(IV) - DFO complexes were incubated with P. fluorescens in 0.1 M Tris-HCl buffer (pH = 7.3), the metals were removed from solution, with no change in DFO in solution. With decreasing metal/DFO molar ratio from 1 to 0.01, the accumulation of Eu(III) and Ce(IV) by P. fluorescens decreased. Kinetics study showed that accumulation of Eu(III) reached the maximum within 30 minutes, and then it decreased slightly with time. On the other hand, Ce(IV) accumulation proceeded in a parabolic process where the kinetics was slower than that of Eu(III) accumulation. In comparison to Eu(III) and Ce(IV), the removal of Fe(III) added as a DFO complex by P. fluorescens was not observed. The formation constants (log K) of Eu(III) - DFO and Fe(III) - DFO are reported to be 15 and 30.6, respectively. These results suggest that Eu(III) - DFO complex was dissociated in the presence of bacteria cells and was readily biosorbed.

  15. 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. PMID:20850191

  16. Pseudomonas fluorescens: identification of Fur-regulated proteins and evaluation of their contribution to pathogenesis.

    PubMed

    Liu, Li; Chi, Heng; Sun, Li

    2015-06-29

    Pseudomonas fluorescens is a Gram-negative bacterium and a common pathogen to a wide range of farmed fish. In a previous study, we found that the ferric uptake regulator gene (fur) is essential to the infectivity of a pathogenic fish isolate of P. fluorescens (wild-type strain TSS). In the present work, we conducted comparative proteomic analysis to examine the global protein profiles of TSS and the P. fluorescens fur knockout mutant TFM. Twenty-eight differentially produced proteins were identified, which belong to different functional categories. Four of these proteins, viz. TssP (a type VI secretion protein), PspA (a serine protease), OprF (an outer membrane porin), and ClpP (the proteolytic subunit of an ATP-dependent Clp protease), were assessed for virulence participation in a model of turbot Scophthalmus maximus. The results showed that the oprF and clpP knockouts exhibited significantly reduced capacities in (1) resistance against the bactericidal effect of host serum, (2) dissemination into and colonization of host tissues, and (3) inducing host mortality. In contrast, mutation of tssP and pspA had no apparent effect on the pathogenicity of TSS. Purified recombinant OprF, when used as a subunit vaccine, induced production of specific serum antibodies in immunized fish and elicited significant protection against lethal TSS challenge. Antibody blocking of the OprF in TSS significantly impaired the ability of the bacteria to invade host tissues. Taken together, these results indicate for the first time that in pathogenic P. fluorescens, Fur regulates the expression of diverse proteins, some of which are required for optimal infection. PMID:26119301

  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. PMID:26051958

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

    PubMed

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

    2011-06-01

    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

  19. 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. PMID:25724953

  20. Pseudomonas fluorescens Pirates both Ferrioxamine and Ferricoelichelin Siderophores from Streptomyces ambofaciens

    PubMed Central

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

    2015-01-01

    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. PMID:25724953

  1. The pathogenic potential of Pseudomonas fluorescens MFN1032 on enterocytes can be modulated by serotonin, substance P and epinephrine.

    PubMed

    Biaggini, Kelly; Barbey, Corinne; Borrel, Valérie; Feuilloley, Marc; Déchelotte, Pierre; Connil, Nathalie

    2015-10-01

    Pseudomonas fluorescens is a commensal bacterium present at low level in the human digestive tract that has also been reported in many clinical samples (blood, urinary tract, skin, lung, etc.) and sometimes associated with acute opportunistic infections. It has recently been found that the human β-defensin-2 can enhance the pathogenic potential of P. fluorescens. In this study, we evaluated the effect of other intestinal molecules (5HT, SP and Epi) on growth and virulence of the clinical strain P. fluorescens MFN1032. We found that P. fluorescens MFN1032 growth was not mainly affected by these factors, but several modifications in the virulence behavior of this bacterium were observed. 5HT, SP and Epi were able to modulate the motility of P. fluorescens MFN1032. 5HT and SP had an effect on pyoverdin production and IL-8 secretion, respectively. Infection of Caco-2/TC7 cells with P. fluorescens MFN1032 pretreated by SP or Epi enhanced the permeability of the monolayers and led to a partial delocalization of F-actin to the cytoplasm. These findings show that some intestinal molecules can modulate the pathogenic potential of P. fluorescens MFN1032. We can hypothesize that this dialogue between the host and the human gut microbiota may participate in health and disease. PMID:26175088

  2. A non-modular endo-beta-1,4-mannanase from Pseudomonas fluorescens subspecies cellulosa.

    PubMed Central

    Braithwaite, K L; Black, G W; Hazlewood, G P; Ali, B R; Gilbert, H J

    1995-01-01

    Pseudomonas fluorescens subsp. cellulosa when cultured in the presence of carob galactomannan degraded the polysaccharide. To isolate gene(s) from P. fluorescens subsp. cellulosa encoding endo-beta-1,4-mannanase (mannanase) activity, a genomic library of Pseudomonas DNA, constructed in lambda ZAPII, was screened for mannanase-expressing clones using the dye-labelled substrate, azo-carob galactomannan. The nucleotide sequence of the pseudomonad insert from a mannanase-positive clone revealed a single open reading frame of 1257 bp encoding a protein of M(r) 46,938. The deduced N-terminal sequence of the putative polypeptide conformed to a typical prokaryotic signal peptide. Truncated derivatives of the mannanase, lacking 54 and 16 residues from the N- and C-terminus respectively of the mature form of the enzyme, did not exhibit catalytic activity. Inspection of the primary structure of the mannanase did not reveal any obvious linker sequences or protein motifs characteristic of the non-catalytic domains located in other Pseudomonas plant cell wall hydrolases. These data indicate that the mannanase is non-modulator, comprising a single catalytic domain. Comparison of the mannanase sequence with those in the SWISSPROT database revealed greatest sequence homology with the mannanase from Bacillus sp. Thus the Pseudomonas enzyme belongs to glycosyl hydrolase Family 26, a family containing mannanases and endoglucanases. Analysis of the substrate specificity of the mannanase showed that the enzyme hydrolysed mannan and galactomannan, but displayed little activity towards other polysaccharides located in the plant cell wall. The enzyme had a pH optimum of approx. 7.0, was resistant to proteolysis and had an M(r) of 46,000 when expressed by Escherichia coli. Images Figure 2 Figure 3 Figure 6 PMID:7848261

  3. Crystallization, diffraction data collection and preliminary crystallographic analysis of DING protein from Pseudomonas fluorescens

    SciTech Connect

    Moniot, Sebastien; Elias, Mikael; Kim, Donghyo; Scott, Ken; Chabriere, Eric

    2007-07-01

    Crystallization of DING protein from P. fluorescens is reported. A complete data set was collected to 1.43 Å resolution. PfluDING is a phosphate-binding protein expressed in Pseudomonas fluorescens. This protein is clearly distinct from the bacterial ABC transporter soluble phosphate-binding protein PstS and is more homologous to eukaryotic DING proteins. Interestingly, bacterial DING proteins have only been detected in certain Pseudomonas species. Although DING proteins seem to be ubiquitous in eukaryotes, they are systematically absent from eukaryotic genomic databases and thus are still quite mysterious and poorly characterized. PfluDING displays mitogenic activity towards human cells and binds various ligands such as inorganic phosphate, pyrophosphate, nucleotide triphosphates and cotinine. Here, the crystallization of PfluDING is reported in a monoclinic space group (P2{sub 1}), with typical unit-cell parameters a = 36.7, b = 123.7, c = 40.8 Å, α = 90, β = 116.7, γ = 90°. Preliminary crystallographic analysis reveals good diffraction quality for these crystals and a 1.43 Å resolution data set has been collected.

  4. Volatiles released by endophytic Pseudomonas fluorescens promoting the growth and volatile oil accumulation in Atractylodes lancea.

    PubMed

    Zhou, Jia-Yu; Li, Xia; Zheng, Jiao-Yan; Dai, Chuan-Chao

    2016-04-01

    Atractylodes lancea is a well-known, but endangered, Chinese medicinal plant whose volatile oils are its main active components. As the volatile oil content in cultivated A. lancea is much lower than that in the wild herb, the application of microbes or related elicitors to promote growth and volatile oil accumulation in the cultivated herb is an important area of research. This study demonstrates that the endophytic bacterium Pseudomonas fluorescens ALEB7B isolated from the geo-authentic A. lancea can release several nitrogenous volatiles, such as formamide and N,N-dimethyl-formamide, which significantly promote the growth of non-infected A. lancea. Moreover, the main bacterial volatile benzaldehyde significantly promotes volatile oil accumulation in non-infected A. lancea via activating plant defense responses. Notably, the bacterial nitrogenous volatiles cannot be detected in the A. lancea - Pseudomonas fluorescens symbiont while the benzaldehyde can be detected, indicating the nitrogenous volatiles or their precursors may have been consumed by the host plant. This study firstly demonstrates that the interaction between plant and endophytic bacterium is not limited to the commonly known physical contact, extending the ecological functions of endophyte in the phytosphere and deepening the understandings about the symbiotic interaction. PMID:26874622

  5. Pseudomonas fluorescens 134 as a biological control agent (BCA) model in cell immobilization technology.

    PubMed

    Russo, Anna; Basaglia, Marina; Casella, Sergio; Nuti, Marco Paolo

    2005-01-01

    Antifungal activity against Rhizoctonia solani was achieved in vivo through the application of Pseudomonas fluorescens strain 134 encapsulated in sodium alginate beads of different sizes (0.5, 1, and 2 mm). The activity was compared to that obtainable with chemical treatments and bead-derived liquid formulations. The latter was obtained by dissolving alginate beads of 1 and 0.5 mm in 1% Na-citrate solution before application, without any significant (P < 0.05) reduction of bacterial numbers during the dissolution process. The dry bead formulations were applied next to the seeds in plant inoculation experiments, resulting in a reduction of disease symptoms, which were markedly reduced when the liquid formulation was applied. Moreover, the rate of disease symptoms related to liquid formulations from both 1 and 0.5 mm beads was comparable (near to 10%) to that of chemical treatment. Pseudomonas fluorescens strain 134 delivered as both dry and liquid formulations was able to colonize cotton root at a population density of about 10(8) CFU/g fresh root, 15 days after sowing. PMID:15903270

  6. Roles of Rhizoxin and 2,4-diacetylphloroglucinol in Suppression of Fusarium spp. by the Rhizobacterium Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens strain Pf-5 is a rhizosphere bacterium that acts as a biocontrol agent of soilborne plant diseases and produces at least 10 different secondary metabolites, including several with antifungal properties. We derived site-directed mutants of Pf-5 with single and multiple mutatio...

  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. Flagella of a plant-growth-stimulating Pseudomonas fluorescens strain are required for colonization of potato roots.

    PubMed Central

    De Weger, L A; van der Vlugt, C I; Wijfjes, A H; Bakker, P A; Schippers, B; Lugtenberg, B

    1987-01-01

    The role of motility in the colonization of potato roots by Pseudomonas bacteria was studied. Four Tn5-induced flagella-less mutants of the plant-growth-stimulating P. fluorescens WCS374 appeared to be impaired in their ability to colonize growing potato roots. Images PMID:3294806

  9. 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...

  10. Molecular Analysis of a Novel Gene Cluster Encoding an Insect Toxin in Plant-Associated Strains of Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens CHA0 and the related strain Pf-5 are well-characterized representatives of rhizosphere bacteria that have the capacity to protect crop plants from fungal root diseases, mainly by releasing a variety of exoproducts that are toxic to plant pathogenic fungi. Here, we report that...

  11. Arbitrary PCR for Rapid Mapping of Tn5 Insertions in Pyoverdine Genes of Pseudomonas fluorescens Pf-5

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A collection of 13 transposon mutants deficient in pyoverdine production was analyzed using an arbitrary polymerase chain reaction (PCR) approach to map the sites of Tn5 insertions in the genome of Pseudomonas fluorescens Pf-5. The arbitrary PCR method involved two rounds of reactions, with the fi...

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

    PubMed

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

    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

  13. The effect of Pseudomonas fluorescens strain q2-87 in pathogen inhibition and growth promotion of slash pine seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens strain Q2-87 showed significant antagonistic activity against the damping-off pathogens of slash pine (Pinus elliottii), including Rhizoctonia solani, Alternaria alternata and Fusarium oxysporum. In vitro assays showed that strain Q2-87, which has an inhibition index higher t...

  14. 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...

  15. Diversity of TonB-dependent outer-membrane proteins in plant-associated strains of Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genomic sequences of ten strains of plant-associated Pseudomonas spp. were surveyed for the presence of TonB-dependent outer-membrane proteins (TBDPs), which function in the uptake of substrates from the environment by many Gram-negative bacteria. The ten strains, representing P. fluorescens, P. ch...

  16. Characterization of toxin complex gene clusters and insect toxicity of bacteria representing four sub-groups 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...

  17. Inactivation of the GacA Response Regulator in Pseudomonas fluorescens Pf-5 Has Far-Reaching Transcriptomic Consequences

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The GacS/GacA signal transduction system is a central regulator in Pseudomonas spp., including the biological control strain P. fluorescens Pf-5, in which GacS/GacA controls the production of secondary metabolites and exoenzymes that suppress plant pathogens. A whole genome oligonucleotide microarra...

  18. 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.

  19. Cyclic lipopeptide surfactant production by Pseudomonas fluorescens SS101 is not required for suppression of complex Pythium spp. populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previously, zoosporicidal activity and control of Pythium intermedium by Pseudomonas fluorescens strain SS101 was attributed, in part, to the production of the cyclic lipopeptide surfactant massetolide A. In the current study, capacity of SS101 and its surfactant-deficient mutant strain 10.24 to sup...

  20. 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

  1. Structural and functional analysis of the type III secretion system from Pseudomonas fluorescens Q8r1-96

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pseudomonas fluorescens Q8r1-96 represents a group of rhizosphere strains responsible for the suppressiveness of agricultural soils to take-all disease of wheat. It produces the antibiotic 2,4-diacetylphloroglucinol and aggressively colonizes the roots of cereal crops. In this study, we analyzed t...

  2. 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...

  3. Variation in the TonB-dependent Outer-Membrane Proteins in Plant-Associated Strains of Pseudomonas fluorescens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient acquisition is key to the ecological fitness of environmental bacteria such as Pseudomonas fluorescens and TonB-dependent outer-membrane proteins are important components of the cellular machinery for the uptake of substrates from the environment. Genomic sequences of ten strains of plant-a...

  4. Factors impacting the activity of 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens against take-all of wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Take-all, caused by Gaeumannomyces graminis var. tritici, is an important soilborne disease of wheat worldwide. Pseudomonas fluorescens producing the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are biocontrol agents of take-all and provide natural suppression of the disease during wheat monocul...

  5. 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. PMID:21875627

  6. 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 ...

  7. Soluble periplasmic production of human granulocyte colony-stimulating factor (G-CSF) in Pseudomonas fluorescens.

    PubMed

    Jin, Hongfan; Cantin, Greg T; Maki, Steven; Chew, Lawrence C; Resnick, Sol M; Ngai, Jerry; Retallack, Diane M

    2011-07-01

    Cost-effective production of soluble recombinant protein in a bacterial system remains problematic with respect to expression levels and quality of the expressed target protein. These constraints have particular meaning today as "biosimilar" versions of innovator protein drugs are entering the clinic and the marketplace. A high throughput, parallel processing approach to expression strain engineering was used to evaluate soluble expression of human granulocyte colony-stimulating factor (G-CSF) in Pseudomonas fluorescens. The human g-csf gene was optimized for expression in P. fluorescens and cloned into a set of periplasmic expression vectors. These plasmids were transformed into a variety of P. fluorescens host strains each having a unique phenotype, to evaluate soluble expression in a 96-well growth and protein expression format. To identify a strain producing high levels of intact, soluble Met-G-CSF product, more than 150 protease defective host strains from the Pfēnex Expression Technology™ toolbox were screened in parallel using biolayer interferometry (BLI) to quantify active G-CSF binding to its receptor. A subset of these strains was screened by LC-MS analysis to assess the quality of the expressed G-CSF protein. A single strain with an antibiotic resistance marker insertion in the pfaI gene was identified that produced>99% Met-GCSF. A host with a complete deletion of the autotransporter-coding gene pfaI from the genome was constructed, and expression of soluble, active Met-GSCF in this strain was observed to be 350mg/L at the 1 liter fermentation scale. PMID:21396452

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

    PubMed Central

    2013-01-01

    Background Pseudomonas fluorescens SBW25 has been extensively studied because of its plant growth promoting properties and potential as a biocontrol agent. The genome of SBW25 has been sequenced, and among sequenced strains of pseudomonads, SBW25 appears to be most closely related to P. fluorescens WH6. In the authors’ laboratories, WH6 was previously shown to produce and secrete 4-formylaminooxyvinylglycine (FVG), a non-proteinogenic amino acid with selective herbicidal and antimicrobial activity. Although SBW25 does not have the genetic capacity to produce FVG, we were interested in determining whether this pseudomonad might produce some other type of non-proteinogenic amino acid. Results P. fluorescens SBW25 was found to produce and secrete a ninhydrin-reactive compound with selective antimicrobial properties. This compound was purified from SBW25 culture filtrate and identified as the non-proteinogenic amino acid L-furanomycin [2S,2′R,5′S)-2-amino-2-(5′methyl-2′,5′-dihydrofuran-2′-yl)acetic acid]. Conclusions The identification of furanomycin as a secondary metabolite of SBW25 is the first report of the production of furanomycin by a pseudomonad. This compound was known previously only as a natural product produced by a strain of Streptomyces. This report adds furanomycin to the small list of non-proteinogenic amino acids that have been identified as secondary products of pseudomonads. This study also extends the list of bacteria that are inhibited by furanomycin to include several plant pathogenic bacteria. PMID:23688329

  9. An ATP and oxalate generating variant tricarboxylic acid cycle counters aluminum toxicity in Pseudomonas fluorescens.

    PubMed

    Singh, Ranji; Lemire, Joseph; Mailloux, Ryan J; Chénier, Daniel; Hamel, Robert; Appanna, Vasu D

    2009-01-01

    Although the tricarboxylic acid (TCA) cycle is essential in almost all aerobic organisms, its precise modulation and integration in global cellular metabolism is not fully understood. Here, we report on an alternative TCA cycle uniquely aimed at generating ATP and oxalate, two metabolites critical for the survival of Pseudomonas fluorescens. The upregulation of isocitrate lyase (ICL) and acylating glyoxylate dehydrogenase (AGODH) led to the enhanced synthesis of oxalate, a dicarboxylic acid involved in the immobilization of aluminum (Al). The increased activity of succinyl-CoA synthetase (SCS) and oxalate CoA-transferase (OCT) in the Al-stressed cells afforded an effective route to ATP synthesis from oxalyl-CoA via substrate level phosphorylation. This modified TCA cycle with diminished efficacy in NADH production and decreased CO(2)-evolving capacity, orchestrates the synthesis of oxalate, NADPH, and ATP, ingredients pivotal to the survival of P. fluorescens in an Al environment. The channeling of succinyl-CoA towards ATP formation may be an important function of the TCA cycle during anaerobiosis, Fe starvation and O(2)-limited conditions. PMID:19809498

  10. Insights into the uranium(VI) speciation with Pseudomonas fluorescens on a molecular level.

    PubMed

    Lütke, Laura; Moll, Henry; Bernhard, Gert

    2012-11-21

    Microorganisms have great potential to bind and thus transport actinides in the environment. Thus microbes indigenous to designated nuclear waste disposal sites have to be investigated regarding their interaction mechanisms with soluble actinyl ions when assessing the safety of a planned repository. This paper presents results on the pH-dependent sorption of U(VI) onto Pseudomonas fluorescens isolated from the granitic rock aquifers at Äspö Hard Rock Laboratory, Sweden. To characterize the U(VI) interaction on a molecular level, potentiometric titration in combination with time-resolved laser-induced fluorescence spectroscopy (TRLFS) were applied. This paper as a result is one of the very few sources which provide stability constants of U(VI) complexed by cell surface functional groups. In addition the bacteria-mediated liberation of inorganic phosphate in dependence on [U(VI)] at different pHs was studied to judge the influence of phosphate release on U(VI) mobilization. The results demonstrate that in the acidic pH range U(VI) is bound by the cells mainly via protonated phosphoryl and carboxylic sites. The complexation by carboxylic groups can be observed over a wide pH range up to around pH 7. At neutral pH fully deprotonated phosphoryl groups are mainly responsible for U(VI) binding. U(VI) can be bound by P. fluorescens with relatively high thermodynamic stability. PMID:23007661

  11. Ecological basis for biocontrol of damping-off disease by pseudomonas fluorescens 54/96

    PubMed

    Ellis; Timms-Wilson; Beringer; Rhodes; Renwick; Stevenson; Bailey

    1999-09-01

    Pseudomonas fluorescens 54/96, originally isolated from the rhizosphere of sugar beet, has been shown to be commercially effective in field trials for the suppression of a number of fungal diseases of seedlings. In vitro and microcosm-based assays revealed that both the timing and method of application of bacteria were important for effective control of Pythium ultimum, the causative agent of damping-off disease. Following transposon mutagenesis (Tn5lac), mutants deficient for the suppression of Pythium ultimum infections of peas were isolated. Three major classes of insertional mutants of Ps. fluorescens 54/96 were identified which either inhibited sporulation, reduced mycelial growth or affected the regulation of bacterial metabolic activity. Evaluation of the metabolic capability of pathogen and antagonist revealed evidence for direct competition, as both the fungus and bacterium had similar sole carbon source nutrient utilization profiles. Further comparisons of the activity of the transposon mutants indicated that although the mechanisms of disease control were multifactorial, the most significant factor was the prevention of rapid spore germination in the presence of pea seeds. PMID:10540249

  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. [Pseudomonas fluorescens survival in soils with different contents of organic matter].

    PubMed

    Perotti, E B R; Menéndez, L T; Gaia, O E; Pidello, A

    2005-01-01

    Pseudomonas fluorescens are plant growth promoting rhizobacteria (PGPR). The survival of this inoculated heterotrophic bacterium may be affected by soil organic matter content (SOM). To confirm this hypothesis, three strains of P. fluorescens: UP61, C7R12 y P190 (native of Balcarce, Buenos Aires) were inoculated, in laboratory conditions, into three argentine rhizospheric soils: two Argiudolls (Balcarce, and Zavalla, Santa Fe) and a Torrifluvens (Cipolletti, Río Negro) with different SOM: 7.2; 4.3; and 2.6%, respectibily. The results indicated that the all three isolates survival in general was not different. The slopes of the regression curves in Zavalla soil were very similars, while in the Balcarce soil the strains behaviour were very different. CO2 production was superior in the Balcarce than the Zavalla soil. These results suggest that the situations that affected the survival in the Balcarce soil may be associated with the presence of a larger number of functional microflora compared with Zavalla soil. The survival in the Cipolietti soil was the lowest; independently of the protective effect of the SOM in relation with the capability of survival of the inoculated bacteria, the scarcity of survival in this soil, specially after the great fall observed, is not attributable to the low SOM content, it might be related with its high electric conductivity. The UP61 had the best survival rate in all soils. PMID:16178468

  14. 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. PMID:26505308

  15. Elucidation of the 4-Hydroxyacetophenone Catabolic Pathway in Pseudomonas fluorescens ACB▿

    PubMed Central

    Moonen, Mariëlle J. H.; Kamerbeek, Nanne M.; Westphal, Adrie H.; Boeren, Sjef A.; Janssen, Dick B.; Fraaije, Marco W.; van Berkel, Willem J. H.

    2008-01-01

    The catabolism of 4-hydroxyacetophenone in Pseudomonas fluorescens ACB is known to proceed through the intermediate formation of hydroquinone. Here, we provide evidence that hydroquinone is further degraded through 4-hydroxymuconic semialdehyde and maleylacetate to β-ketoadipate. The P. fluorescens ACB genes involved in 4-hydroxyacetophenone utilization were cloned and characterized. Sequence analysis of a 15-kb DNA fragment showed the presence of 14 open reading frames containing a gene cluster (hapCDEFGHIBA) of which at least four encoded enzymes are involved in 4-hydroxyacetophenone degradation: 4-hydroxyacetophenone monooxygenase (hapA), 4-hydroxyphenyl acetate hydrolase (hapB), 4-hydroxymuconic semialdehyde dehydrogenase (hapE), and maleylacetate reductase (hapF). In between hapF and hapB, three genes encoding a putative intradiol dioxygenase (hapG), a protein of the Yci1 family (hapH), and a [2Fe-2S] ferredoxin (hapI) were found. Downstream of the hap genes, five open reading frames are situated encoding three putative regulatory proteins (orf10, orf12, and orf13) and two proteins possibly involved in a membrane efflux pump (orf11 and orf14). Upstream of hapE, two genes (hapC and hapD) were present that showed weak similarity with several iron(II)-dependent extradiol dioxygenases. Based on these findings and additional biochemical evidence, it is proposed that the hapC and hapD gene products are involved in the ring cleavage of hydroquinone. PMID:18502868

  16. 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

  17. The effect of iron limitation on the transcriptome and proteome of Pseudomonas fluorescens Pf-5.

    PubMed

    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

  18. Three small RNAs jointly ensure secondary metabolism and biocontrol in Pseudomonas fluorescens CHA0

    PubMed Central

    Kay, Elisabeth; Dubuis, Christophe; Haas, Dieter

    2005-01-01

    In many Gram-negative bacteria, the GacS/GacA two-component system positively controls the expression of extracellular products or storage compounds. In the plant-beneficial rhizosphere bacterium Pseudomonas fluorescens CHA0, the GacS/GacA system is essential for the production of antibiotic compounds and hence for biological control of root-pathogenic fungi. The small (119-nt) RNA RsmX discovered in this study, together with RsmY and RsmZ, forms a triad of GacA-dependent small RNAs, which sequester the RNA-binding proteins RsmA and RsmE and thereby antagonize translational repression exerted by these proteins in strain CHA0. This small RNA triad was found to be both necessary and sufficient for posttranscriptional derepression of biocontrol factors and for protection of cucumber from Pythium ultimum. The same three small RNAs also positively regulated swarming motility and the synthesis of a quorum-sensing signal, which is unrelated to N-acyl-homoserine lactones, and which autoinduces the Gac/Rsm cascade. Expression of RsmX and RsmY increased in parallel throughout cell growth, whereas RsmZ was produced during the late growth phase. This differential expression is assumed to facilitate fine tuning of GacS/A-controlled cell population density-dependent regulation in P. fluorescens. PMID:16286659

  19. Three small RNAs jointly ensure secondary metabolism and biocontrol in Pseudomonas fluorescens CHA0.

    PubMed

    Kay, Elisabeth; Dubuis, Christophe; Haas, Dieter

    2005-11-22

    In many Gram-negative bacteria, the GacS/GacA two-component system positively controls the expression of extracellular products or storage compounds. In the plant-beneficial rhizosphere bacterium Pseudomonas fluorescens CHA0, the GacS/GacA system is essential for the production of antibiotic compounds and hence for biological control of root-pathogenic fungi. The small (119-nt) RNA RsmX discovered in this study, together with RsmY and RsmZ, forms a triad of GacA-dependent small RNAs, which sequester the RNA-binding proteins RsmA and RsmE and thereby antagonize translational repression exerted by these proteins in strain CHA0. This small RNA triad was found to be both necessary and sufficient for posttranscriptional derepression of biocontrol factors and for protection of cucumber from Pythium ultimum. The same three small RNAs also positively regulated swarming motility and the synthesis of a quorum-sensing signal, which is unrelated to N-acyl-homoserine lactones, and which autoinduces the Gac/Rsm cascade. Expression of RsmX and RsmY increased in parallel throughout cell growth, whereas RsmZ was produced during the late growth phase. This differential expression is assumed to facilitate fine tuning of GacS/A-controlled cell population density-dependent regulation in P. fluorescens. PMID:16286659

  20. Physiological analysis of the expression of the styrene degradation gene cluster in Pseudomonas fluorescens ST.

    PubMed

    Santos, P M; Blatny, J M; Di Bartolo, I; Valla, S; Zennaro, E

    2000-04-01

    The effects of different carbon sources on expression of the styrene catabolism genes in Pseudomonas fluorescens ST were analyzed by using a promoter probe vector, pPR9TT, which contains transcription terminators upstream and downstream of the beta-galactosidase reporter system. Expression of the promoter of the stySR operon, which codes for the styrene two-component regulatory system, was found to be constitutive and not subject to catabolite repression. This was confirmed by the results of an analysis of the stySR transcript in P. fluorescens ST cells grown on different carbon sources. The promoter of the operon of the upper pathway, designated PstyA, was induced by styrene and repressed to different extents by organic acids or carbohydrates. In particular, cells grown on succinate or lactate in the presence of styrene started to exhibit beta-galactosidase activity during the mid-exponential growth phase, before the preferred carbon sources were depleted, indicating that there is a threshold succinate and lactate concentration which allows induction of styrene catabolic genes. In contrast, cells grown on glucose, acetate, or glutamate and styrene exhibited a diauxic growth curve, and beta-galactosidase activity was detected only after the end of the exponential growth phase. In each experiment the reliability of the reporter system constructed was verified by comparing the beta-galactosidase activity and the activity of the styrene monooxygenase encoded by the first gene of the styrene catabolic operon. PMID:10742204

  1. 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

  2. Upon impact: the fate of adhering Pseudomonas fluorescens cells during nanofiltration.

    PubMed

    Habimana, Olivier; Semião, Andrea J C; Casey, Eoin

    2014-08-19

    Nanofiltration (NF) is a high-pressure membrane filtration process increasingly applied in drinking water treatment and water reuse processes. NF typically rejects divalent salts, organic matter, and micropollutants. However, the efficiency of NF is adversely affected by membrane biofouling, during which microorganisms adhere to the membrane and proliferate to create a biofilm. Here we show that adhered Pseudomonas fluorescens cells under high permeate flux conditions are met with high fluid shear and convective fluxes at the membrane-liquid interface, resulting in their structural damage and collapse. These results were confirmed by fluorescent staining, flow cytometry, and scanning electron microscopy. This present study offers a "first-glimpse" of cell damage and death during the initial phases of bacterial adhesion to NF membranes and raises a key question about the role of this observed phenomena during early-stage biofilm formation under permeate flux and cross-flow conditions. PMID:25072514

  3. Functional characterization of Pseudomonas fluorescens OprE and OprQ membrane proteins.

    PubMed

    Jaouen, Thomas; Coquet, Laurent; Marvin-Guy, Laure; Orange, Nicole; Chevalier, Sylvie; Dé, Emmanuelle

    2006-08-01

    Outer membrane (OM) proteins of the OprD family may enable bacteria of the genus Pseudomonas to adapt to various environments by modulating OM permeability. The OprE and OprQ porins from P. fluorescens strain MF0 were purified and identified by MALDI-TOF mass spectrometry and N-terminal and internal microsequencing. These proteins, when reconstituted in an artificial planar lipid bilayer, induced similar ion channels with low single-conductance values. Secondary structure prediction of both proteins showed similar folding patterns into a 16 transmembrane beta-strands barrel but a highly variable amino-acid composition and length for their putative external loops implicated in porin function. Both proteins were overexpressed under poor oxygenation conditions, but not by using several amino acids as sole carbon source, indicating a different specificity for these proteins compared to the paradigm of this protein family, OprD. PMID:16777062

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

    PubMed

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

    2016-02-01

    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

  5. Isolation and identification of N-mercapto-4-formylcarbostyril, an antibiotic produced by Pseudomonas fluorescens.

    PubMed

    Fakhouri, W; Walker, F; Vogler, B; Armbruster, W; Buchenauer, H

    2001-12-01

    Pseudomonas fluorescens strain G308 isolated from barley leaves produces a novel antibiotic substance that was purified by preparative TLC and HPLC and identified as N-mercapto-4-formylcarbostyril (Cbs) by LC/DAD, IR, LC-ES(+)/MS, LC-ES(-)/MS, GC-EI/MS, LC-HRES(+)/MS, mass isotope ratios analysis, 1H NMR and 13C NMR analysis. The purified new antibiotic compound is effective against many phytopathogenic fungi in vitro. The compound inhibited at 25 ppm spore germination and germ tube growth of the following fungi; Fusarium oxysporum f. sp. lycopersici, Fusarium culmorum, Cladosporium cucumerinum and Colletotrichum lagenarium. At concentrations up to 125 ppm, the compound did not interfere with release of zoospores from sporangia and germination of encysted zoospores of Phytophthora infestans. PMID:11738425

  6. 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

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

    PubMed

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

    1996-02-01

    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

  8. 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. PMID:24294253

  9. 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

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

    PubMed Central

    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. PMID:24294253

  11. 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. PMID:27497132

  12. Draft Genome Sequence of the Biocontrol and Plant Growth-Promoting Rhizobacterium Pseudomonas fluorescens strain UM270.

    PubMed

    Hernández-Salmerón, Julie E; Hernández-León, Rocio; Orozco-Mosqueda, Ma Del Carmen; Valencia-Cantero, Eduardo; Moreno-Hagelsieb, Gabriel; Santoyo, Gustavo

    2016-01-01

    The Pseudomonas fluorescens strain UM270 was isolated form the rhizosphere of wild Medicago spp. A previous work has shown that this pseudomonad isolate was able to produce diverse diffusible and volatile compounds involved in plant protection and growth promotion. Here, we present the draft genome sequence of the rhizobacterium P. fluorescens strain UM270. The sequence covers 6,047,974 bp of a single chromosome, with 62.66 % G + C content and no plasmids. Genome annotations predicted 5,509 genes, 5,396 coding genes, 59 RNA genes and 110 pseudogenes. Genome sequence analysis revealed the presence of genes involved in biological control and plant-growth promoting activities. We anticipate that the P. fluorescens strain UM270 genome will contribute insights about bacterial plant protection and beneficial properties through genomic comparisons among fluorescent pseudomonads. PMID:26767092

  13. pA506, a conjugative plasmid of the plant epiphyte Pseudomonas fluorescens A506.

    PubMed

    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; Loper, Joyce E

    2013-09-01

    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

  14. Pseudomonas fluorescens strain CL145A - a biopesticide for the control of zebra and quagga mussels (Bivalvia: Dreissenidae).

    PubMed

    Molloy, Daniel P; Mayer, Denise A; Gaylo, Michael J; Morse, John T; Presti, Kathleen T; Sawyko, Paul M; Karatayev, Alexander Y; Burlakova, Lyubov E; Laruelle, Franck; Nishikawa, Kimi C; Griffin, Barbara H

    2013-05-01

    Zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis) are the "poster children" of high-impact aquatic invasive species. In an effort to develop an effective and environmentally acceptable method to control their fouling of raw-water conduits, we have investigated the potential use of bacteria and their natural metabolic products as selective biological control agents. An outcome of this effort was the discovery of Pseudomonas fluorescens strain CL145A - an environmental isolate that kills these dreissenid mussels by intoxication (i.e., not infection). In the present paper, we use molecular methods to reconfirm that CL145A is a strain of the species P. fluorescens, and provide a phylogenetic analysis of the strain in relation to other Pseudomonas spp. We also provide evidence that the natural product lethal to dreissenids is associated with the cell wall of P. fluorescens CL145A, is a heat-labile secondary metabolite, and has degradable toxicity within 24 h when applied to water. CL145A appears to be an unusual strain of P. fluorescens since it was the only one among the ten strains tested to cause high mussel mortality. Pipe trials conducted under once-through conditions indicated: (1) P. fluorescens CL145A cells were efficacious against both zebra and quagga mussels, with high mortalities achieved against both species, and (2) as long as the total quantity of bacterial cells applied during the entire treatment period was the same, similar mussel mortality could be achieved in treatments lasting 1.5-12.0 h, with longer treatment durations achieving lower mortalities. The efficacy data presented herein, in combination with prior demonstration of its low risk of non-target impact, indicate that P. fluorescens CL145A cells have significant promise as an effective and environmentally safe control agent against these invasive mussels. PMID:23295683

  15. Crystal Structure of the Terminal Oxygenase Component of Cumene Dioxygenase from Pseudomonas fluorescens IP01†

    PubMed Central

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

    2005-01-01

    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 Å 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. PMID:15774891

  16. Four genes from Pseudomonas fluorescens that encode the biosynthesis of pyrrolnitrin.

    PubMed Central

    Hammer, P E; Hill, D S; Lam, S T; Van Pée, K H; Ligon, J M

    1997-01-01

    Pyrrolnitrin is a secondary metabolite of Pseudomonas and Burkholderia sp. strains with strong antifungal activity. Production of pyrrolnitrin has been correlated with the ability of some bacteria to control plant diseases caused by fungal pathogens, including the damping-off pathogen Rhizoctonia solani. Pseudomonas fluorescens BL915 has been reported to produce pyrrolnitrin and to be an effective biocontrol agent for this pathogen. We have isolated a 32-kb genomic DNA fragment from this strain that contains genes involved in the biosynthesis of pyrrolnitrin. Marker-exchange mutagenesis of this DNA with Tn5 revealed the presence of a 6.2-kb region that contains genes required for the synthesis of pyrrolnitrin. The nucleotide sequence of the 6.2-kb region was determined and found to contain a cluster of four genes that are required for the production of pyrrolnitrin. Deletion mutations in any of the four genes resulted in a pyrrolnitrin-nonproducing phenotype. The putative coding sequences of the four individual genes were cloned by PCR and fused to the tac promoter from Escherichia coli. In each case, the appropriate tac promoter-pyrrolnitrin gene fusion was shown to complement the pyrrolnitrin-negative phenotype of the corresponding deletion mutant. Transfer of the four gene cluster to E. coli resulted in the production of pyrrolnitrin by this organism, thereby demonstrating that the four genes are sufficient for the production of this metabolite and represent all of the genes required to encode the pathway for pyrrolnitrin biosynthesis. PMID:9172332

  17. TonB-dependent outer-membrane proteins and siderophore utilization in Pseudomonas fluorescens Pf-5.

    PubMed

    Hartney, Sierra L; Mazurier, Sylvie; Kidarsa, Teresa A; Quecine, Maria Carolina; Lemanceau, Philippe; Loper, Joyce E

    2011-04-01

    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 conserved β-barrel and plug domains of TonB-dependent proteins but only 18 of them have an N-terminal signaling domain characteristic of TonB-dependent transducers (TBDTs), which participate in cell-surface signaling systems. Phylogenetic analyses of the 18 TBDTs and 27 TonB-dependent receptors (TBDRs), which lack the N-terminal signaling domain, suggest a complex evolutionary history including horizontal transfer among different microbial lineages. Putative functions were assigned to certain TBDRs and TBDTs in clades including well-characterized orthologs from other Pseudomonas spp. A mutant of Pf-5 with deletions in pyoverdine and enantio-pyochelin biosynthesis genes was constructed and characterized for iron-limited growth and utilization of a spectrum of siderophores. The mutant could utilize as iron sources a large number of pyoverdines with diverse structures as well as ferric citrate, heme, and the siderophores ferrichrome, ferrioxamine B, enterobactin, and aerobactin. The diversity and complexity of the TBDTs and TBDRs with roles in iron uptake clearly indicate the importance of iron in the fitness and survival of Pf-5 in the environment. PMID:21080032

  18. Amplification of the housekeeping sigma factor in Pseudomonas fluorescens CHA0 enhances antibiotic production and improves biocontrol abilities.

    PubMed Central

    Schnider, U; Keel, C; Blumer, C; Troxler, J; Défago, G; Haas, D

    1995-01-01

    Pseudomonas fluorescens CHA0 produces a variety of secondary metabolites, in particular the antibiotics pyoluteorin and 2,4-diacetylphloroglucinol, and protects various plants from diseases caused by soilborne pathogenic fungi. The rpoD gene encoding the housekeeping sigma factor sigma 70 of P. fluorescens was sequenced. The deduced RpoD protein showed 83% identity with RpoD of Pseudomonas aeruginosa and 67% identity with RpoD of Escherichia coli. Attempts to inactivate the single chromosomal rpoD gene of strain CHA0 were unsuccessful, indicating an essential role of this gene. When rpoD was carried by an IncP vector in strain CHA0, the production of both antibiotics was increased severalfold and, in parallel, protection of cucumber against disease caused by Pythium ultimum was improved, in comparison with strain CHA0. PMID:7665535

  19. Interaction between the bacterium Pseudomonas fluorescens and vermiculite: Effects on chemical, mineralogical, and mechanical properties of vermiculite

    NASA Astrophysics Data System (ADS)

    Müller, Barbara; DéFago, GenèVieve

    2006-06-01

    On an expanded and crushed vermiculite, changes in chemical, mineralogical, and rheological properties of the mineral affected by microbial activity were investigated. Determination of the water content, grain size, X-ray diffraction pattern, intercrystalline swelling with glycerol, layer charge, CEC, exchangeable cations, BET surface, and rheology provided the necessary information about the differences between pure vermiculite, vermiculite suspensions containing the nutrient medium, and vermiculite suspensions containing the nutrient medium and the bacterium Pseudomonas fluorescens strain CHA0. The aerobic bacterium Pseudomonas fluorescens causes a decrease in grain size, aggregation of vermiculite grains as evidenced by smaller BET surfaces, and enhanced viscosity of the bacteria containing slurries. Layer charge, intercrystalline swelling, and CEC were not affected by the microbial activity, nor did the bacteria count for the exchange of potassium and magnesium against sodium in the vermiculite. The microbes inhibited this exchange process during the first stage of the experiments; however, increasing run time favors the exchange as well.

  20. Influence of Soil Temperature and Matric Potential on Sugar Beet Seedling Colonization and Suppression of Pythium Damping-Off by the Antagonistic Bacteria Pseudomonas fluorescens and Bacillus subtilis.

    PubMed

    Schmidt, C S; Agostini, F; Leifert, C; Killham, K; Mullins, C E

    2004-04-01

    ABSTRACT Pseudomonas fluorescens B5 and Bacillus subtilis MBI 600 colonized sugar beet seedlings at matric potentials of -7 x 10(3), -140 x 10(3), and -330 x 10(3) Pa and under five temperature regimes ranging from 7 to 35 degrees C, with diurnal fluctuations of 5 to 22 degrees C. No interaction between matric potential and temperature was observed. In situ bioluminescence indicated physiological activity of Pseudomonas fluorescens B5. Colonization of the root at >/=4 cm below the seed decreased at very low matric potential (-330 x 10(3) Pa). Total population size of Pseudomonas fluorescens B5 per seedling was significantly increased at -140 x 10(3) Pa. However, matric potential had no significant effect on the population density of Pseudomonas fluorescens per gram of root fresh weight and did not affect the distribution of the population down the root. Total population size per seedling and downward colonization by Pseudomonas fluorescens B5 were significantly reduced at high temperatures (25 to 35 degrees C). Maximum colonization down the root occurred at intermediate temperature (15 degrees C) at both matric potentials (-7 x 10(3) and -140 x 10(3) Pa). Addition of B. subtilis MBI 600 to the seed had no effect on rhizosphere populations of Pseudomonas fluorescens B5. Populations of B. subtilis MBI 600, which consisted largely of spores, were slightly reduced at lower matric potentials and were not affected by temperature. Survival and dry weight of plants in soils infested with Pythium spp. decreased with increasing soil temperature and matric potential, indicating an increase in disease pressure. However, there was no significant interaction between the two factors. At -330 x 10(3) Pa, soil dryness but not Pythium infection was the limiting factor for plant emergence. At temperatures of 7 to 25 degrees C and matric potentials of -7 x 10(3) to 120 x 10(3) Pa, treatment with Pseudomonas fluorescens B5 increased plant survival and dry weight. At 7 degrees C and

  1. A New Biocatalyst for Production of Optically Pure Aryl Epoxides by Styrene Monooxygenase from Pseudomonas fluorescens ST

    PubMed Central

    Di Gennaro, Patrizia; Colmegna, Andrea; Galli, Enrica; Sello, Guido; Pelizzoni, Francesca; Bestetti, Giuseppina

    1999-01-01

    We developed a biocatalyst by cloning the styrene monooxygenase genes (styA and styB) from Pseudomonas fluorescens ST responsible for the oxidation of styrene to its corresponding epoxide. Recombinant Escherichia coli was able to oxidize different aryl vinyl and aryl ethenyl compounds to their corresponding optically pure epoxides. The results of bioconversions indicate the broad substrate preference of styrene monooxygenase and its potential for the production of several fine chemicals. PMID:10347083

  2. Isolation and characterization of a stilbene-degrading strain of Pseudomonas fluorescens, and production of antioxidant compounds by stilbene metabolism.

    PubMed

    Leahy, Joseph G; Batchelor, Patricia J; Setzer, Mary C; Setzer, William N

    2003-10-01

    In this study, we consider the use of hydrocarbon-degrading bacteria that degrade trans-stilbene as a novel approach for synthesizing potentially bioactive hydroxylated stilbenes. A trans-stilbene-degrading bacterium, MN2, was isolated from activated sludge through enrichment culture, and identified as Pseudomonas fluorescens using conventional techniques. Degradation of trans-stilbene by this strain yielded two metabolites that had significant antioxidant activity. PMID:14586124

  3. Cloning, sequence analysis, and expression of ansB from Pseudomonas fluorescens, encoding periplasmic glutaminase/asparaginase.

    PubMed

    Hüser, A; Klöppner, U; Röhm, K H

    1999-09-15

    A gene (ansB) encoding a class II glutaminase/asparaginase has been cloned from Pseudomonas fluorescens and characterized by DNA sequencing, promoter analysis and heterologous expression in Escherichia coli. We show that ansB is monocistronic and depends on the alternate sigma factor sigma 54 for expression. A second open reading frame located downstream of ansB is highly homologous to a number of bacterial genes that encode secreted endonucleases of unknown function. PMID:10499283

  4. 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

  5. Pseudomonas fluorescens contamination of a feline packed red blood cell unit and studies of canine units

    PubMed Central

    Kessler, Rebecca J.; Rankin, Shelley; Young, Sheri; O’Shea, Kathleen; Calabrese, Maria; Guldin, Amy; Lipson, Nicole; Oakley, Donna A.; Giger, Urs

    2011-01-01

    Background While screening programs have reduced the risk of infectious disease transmission by donors in human and veterinary blood banking, bacterial contamination of blood products has emerged as a major complication in human medicine. Objectives To describe a Pseudomonas fluorescens (Pf)-contaminated feline packed RBC (pRBC) unit and experimentally investigate Pf-contaminated canine pRBCs. Methods Canine pRBCs were inoculated with Pf-rich pRBCs from the sentinel feline unit and stored at 4°C or 20°C for 72 hours. Aliquots from the pRBCs were serially evaluated by microscopy, culture, and a eubacterial 16S rRNA real-time PCR assay. Results One Pf-contaminated feline unit turned black after 22 days of storage and was removed from the blood bank; a source was not found, and no other contaminated units were identified. Canine pRBCs spiked with 5 or 25 μL of the sentinel unit became culture- and/or 16S PCR-positive at ≥8 hours at 20°C and 48 hours at 4°C and developed a color change at ≥24 hours. Sensitivity studies indicated that without incubation, inoculation of ≥100 μL Pf-rich pRBCs was necessary for a positive 16S PCR test result. Conclusions P. fluorescens grows in stored pRBCs slowly at 4°C and rapidly at 20°C. Screening of blood products for color change, estimating bacterial concentration with microscopy, and 16S PCR testing are simple and fast ways to detect bacteria in stored blood. Aseptic collection, temperature-controlled storage, and regular visual monitoring of stored units is recommended. Discolored units should not be transfused, but examined for bacterial contamination or other blood product quality problems. PMID:19843300

  6. 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. PMID:23426012

  7. 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

  8. 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

  9. 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

  10. 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

    2016-01-01

    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

  11. 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

  12. Toxicity of Pseudomonas fluorescens strain Pf-5 to Drosophila larvae is due to downstream gene targets of the GacA/GacS signal transduction system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Given the vast number of microorganisms in the environment, surprisingly, only a few are lethal or cause morbidity to host organisms. Pseudomonas spp are a diverse genus of Gram-negative bacteria commonly found in soil, water, or in association with plants and animals. Pseudomonas fluorescens has be...

  13. Rhizoremediation of Trichloroethylene by a Recombinant, Root-Colonizing Pseudomonas fluorescens Strain Expressing Toluene ortho-Monooxygenase Constitutively

    PubMed Central

    Yee, Dennis C.; Maynard, Jennifer A.; Wood, Thomas K.

    1998-01-01

    Trichloroethylene (TCE) was removed from soils by using a wheat rhizosphere established by coating seeds with a recombinant, TCE-degrading Pseudomonas fluorescens strain that expresses the tomA+ (toluene o-monooxygenase) genes from Burkholderia cepacia PR123(TOM23C). A transposon integration vector was used to insert tomA+ into the chromosome of P. fluorescens 2-79, producing a stable strain that expressed constitutively the monooxygenase at a level of 1.1 nmol/min · mg of protein (initial TCE concentration, 10 μM, assuming that all of the TCE was in the liquid) for more than 280 cell generations (36 days). We also constructed a salicylate-inducible P. fluorescens strain that degraded TCE at an initial rate of 2.6 nmol/min · mg of protein in the presence of 10 μM TCE [cf. B. cepacia G4 PR123(TOM23C), which degraded TCE at an initial rate of 2.5 nmol/min · mg of protein]. A constitutive strain, P. fluorescens 2-79TOM, grew (maximum specific growth rate, 0.78 h−1) and colonized wheat (3 × 106 CFU/cm of root) as well as wild-type P. fluorescens 2-79 (maximum specific growth rate, 0.77 h−1; level of colonization, 4 × 106 CFU/cm of root). Rhizoremediation of TCE was demonstrated by using microcosms containing the constitutive monooxygenase-expressing microorganism, soil, and wheat. These closed microcosms degraded an average of 63% of the initial TCE in 4 days (20.6 nmol of TCE/day · plant), compared to the 9% of the initial TCE removed by negative controls consisting of microcosms containing wild-type P. fluorescens 2-79-inoculated wheat, uninoculated wheat, or sterile soil. PMID:9435067

  14. 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

  15. 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

  16. A spectroscopic study on U(VI) biomineralization in cultivated Pseudomonas fluorescens biofilms isolated from granitic aquifers.

    PubMed

    Krawczyk-Bärsch, Evelyn; Lütke, Laura; Moll, Henry; Bok, Frank; Steudtner, Robin; Rossberg, André

    2015-03-01

    The interaction between the Pseudomonas fluorescens biofilm and U(VI) were studied using extended X-ray absorption fine structure spectroscopy (EXAFS), and time-resolved laser fluorescence spectroscopy (TRLFS). In EXAFS studies, the formation of a stable uranyl phosphate mineral, similar to autunite (Ca[UO2]2[PO4]2•2-6H2O) or meta-autunite (Ca[UO2]2[PO4]2•10-12H2O) was observed. This is the first time such a biomineralization process has been observed in P. fluorescens. Biomineralization occurs due to phosphate release from the cellular polyphosphate, likely as a cell's response to the added uranium. It differs significantly from the biosorption process occurring in the planktonic cells of the same strain. TRLFS studies of the uranium-contaminated nutrient medium identified aqueous Ca2UO2(CO3)3 and UO2(CO3)3 (4-) species, which in contrast to the biomineralization in the P. fluorescens biofilm, may contribute to the transport and migration of U(VI). The obtained results reveal that biofilms of P. fluorescens may play an important role in predicting the transport behavior of uranium in the environment. They will also contribute to the improvement of remediation methods in uranium-contaminated sites. PMID:25318416

  17. 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

  18. 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. PMID:14660362

  19. Expression, Purification, Crystallization and Preliminary X-ray Analysis of Pseudomonas fluorescens AlgK

    SciTech Connect

    Keiski,C.; Yip, P.; Robinson, H.; Burrows, L.; Howell, P.

    2007-01-01

    AlgK is an outer-membrane lipoprotein involved in the biosynthesis of alginate in Pseudomonads and Azotobacter vinelandii. A recombinant form of Pseudomonas fluorescens AlgK with a C-terminal polyhistidine affinity tag has been expressed and purified from the periplasm of Escherichia coli cells and diffraction-quality crystals of AlgK have been grown using the hanging-drop vapour-diffusion method. The crystals grow as flat plates with unit-cell parameters a = 79.09, b = 107.85, c = 119.15 {angstrom}, = 96.97{sup o}. The crystals exhibit the symmetry of space group P2{sub 1} and diffract to a minimum d-spacing of 2.5 {angstrom} at Station X29 of the National Synchrotron Light Source, Brookhaven National Laboratory. On the basis of the Matthews coefficient (V{sub M} = 2.53 {angstrom}{sup 3} Da{sup -1}), four protein molecules are estimated to be present in the asymmetric unit.

  20. 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

    2013-10-01

    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. PMID:23984828

  1. Glycine metabolism and anti-oxidative defence mechanisms in Pseudomonas fluorescens.

    PubMed

    Alhasawi, Azhar; Castonguay, Zachary; Appanna, Nishma D; Auger, Christopher; Appanna, Vasu D

    2015-02-01

    The role of metabolism in anti-oxidative defence is only now beginning to emerge. Here, we show that the nutritionally-versatile microbe, Pseudomonas fluorescens, reconfigures its metabolism in an effort to generate NADPH, ATP and glyoxylate in order to fend off oxidative stress. Glyoxylate was produced predominantly via the enhanced activities of glycine dehydrogenase-NADP(+) (GDH), glycine transaminase (GTA) and isocitrate lyase (ICL) in a medium exposed to hydrogen peroxide (H₂O₂). This ketoacid was utilized to produce ATP by substrate-level phosphorylation and to neutralize reactive oxygen species with the concomitant formation of formate. The latter was also a source of NADPH, a process mediated by formate dehydrogenase-NADP(+) (FDH). The increased activities of phosphoenolpyruvate carboxylase (PEPC) and pyruvate orthophosphate dikinase (PPDK) worked in tandem to synthesize ATP in the H₂O₂-challenged cells that had markedly diminished capacity for oxidative phosphorylation. These metabolic networks provide an effective means of combating ROS and reveal therapeutic targets against microbes resistant to oxidative stress. PMID:25644949

  2. The Metabolic Reprogramming Evoked by Nitrosative Stress Triggers the Anaerobic Utilization of Citrate in Pseudomonas fluorescens

    PubMed Central

    Auger, Christopher; Lemire, Joseph; Cecchini, Dominic; Bignucolo, Adam; Appanna, Vasu D.

    2011-01-01

    Nitrosative stress is an ongoing challenge that most organisms have to contend with. When nitric oxide (NO) that may be generated either exogenously or endogenously encounters reactive oxygen species (ROS), it produces a set of toxic moieties referred to as reactive nitrogen species (RNS). As these RNS can severely damage essential biomolecules, numerous organisms have evolved elaborate detoxification strategies to nullify RNS. However, the contribution of cellular metabolism in fending off nitrosative stress is poorly understood. Using a variety of functional proteomic and metabolomic analyses, we have identified how the soil microbe Pseudomonas fluorescens reprogrammed its metabolic networks to survive in an environment enriched by sodium nitroprusside (SNP), a generator of nitrosative stress. To combat the RNS-induced ineffective aconitase (ACN) and tricarboxylic acid (TCA) cycle, the microbe invoked the participation of citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate phosphate dikinase (PPDK) to convert citrate, the sole source of carbon into pyruvate and ATP. These enzymes were not evident in the control conditions. This metabolic shift was coupled to the concomitant increase in the activities of such classical RNS detoxifiers as nitrate reductase (NR), nitrite reductase (NIR) and S-nitrosoglutathione reductase (GSNOR). Hence, metabolism may hold the clues to the survival of organisms subjected to nitrosative stress and may provide therapeutic cues against RNS-resistant microbes. PMID:22145048

  3. Role of flagella in adhesion of Pseudomonas fluorescens to tendon slices.

    PubMed Central

    Piette, J P; Idziak, E S

    1991-01-01

    Tendon slices were used as model surfaces to investigate the role of flagella in the adhesion of Pseudomonas fluorescens to meat. The slices were introduced into a specially designed flow chamber, which was then filled with a suspension of the organism, and the tendon surface was observed at a x640 magnification. The same events that occur during the colonization of glass surfaces (apical adhesion of cells with rotation around the contact point, longitudinal adhesion, detachment of apically and longitudinally adherent cells) were also observed on tendon. Mechanical removal of the flagella resulted in no change in the contact angles with 0.1 M saline or alpha-bromonaphthalene, in the electrophoretic mobility, or in the adhesion of the organism to hydrophobic and ion-exchange resins. In addition, cells from which flagella had been mechanically removed still adhered extensively to tendon. Nevertheless, under comparable conditions (bacterial concentration, contact time), flagellated cells adhered to tendon in larger numbers than did deflagellated cells. This was entirely due to the ability of the motile flagellated cells to reach tendon in greater numbers than deflagellated cells. Images PMID:1908206

  4. 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. PMID:23913099

  5. Growth of an extracellular proteinase-deficient strain of Pseudomonas fluorescens on milk and milk proteins.

    PubMed

    Torrie, J P; Cholette, H; Froehlich, D A; McKellar, R C

    1983-08-01

    An extracellular proteinase-and lipase-deficient mutant of a psychrotroph, Pseudomonas fluorescens strain 32A, has been isolated and the absence of the proteinase enzyme confirmed by growth on differential media, enzyme assay and polyacrylamide gel electrophoresis. Competition between the parent and the mutant was observed when equal numbers of the 2 strains were inoculated together into raw skim-milk at 6 degrees C. Bitterness was detected at 6 degrees C in pasteurized skim-milk inoculated with the parent cells concurrent with the detection of proteolytic activity. In the case of the mutant, slight bitterness which did not increase with increasing cell numbers was detected in the absence of proteolysis. Mutant cells failed to grow on Na caseinate as the sole source of carbon. It was concluded that the extracellular proteinase, while not essential for growth in milk, does provide a selective advantage to the producer organism. This enzyme is, however, essential for growth on milk proteins and contributes to the development of bitterness in pasteurized milk. PMID:6413562

  6. Biosurfactant yields and nutrient consumption of Pseudomonas fluorescens 378 studied in a microcomputer controlled multifermentation system.

    PubMed

    Persson, A; Molin, G; Andersson, N; Sjöholm, J

    1990-07-01

    Production of biosurfactant AP-6 and consumption of carbon (succinic acid) and nitrogen (ammonium ions) by Pseudomonas fluorescens 378 were studied under different growth conditions. The study was performed in a microcomputer controlled multibatch fermentation system which enabled simultaneous running of 10 fermentors. The fermentors were mantled glass vessels, temperature controlled by circulated water, and mixing was arranged by magnetic stirrers. They were connected to the computer system (pH measurement and control) via signal conditioning cards. The microcomputer had a 128 kbytes RAM, two 800-kbyte floppy disc drives, a graphic terminal, and expansion cards. Biosurfactant production was independent of the carbon-to-nitrogen ratio and the phosphorus content in the medium. Omitting the Fe(III) supplement to the medium increased the product yield by 120%. Changes in oxygen transfer rate and pH in the iron deficient cultures did not have any effect on the product yield. Iron deficiency increased the cell consumption of carbon source. Consumption of carbon source in relation to nitrogen uptake (carbon/nitrogen quotient) increased with increasing quotient in the growth medium. The uptake of carbon and nitrogen changed in the intervals of 1.2-1.5 g/g biomass and 0.09-0.16 g/g biomass, respectively. The consumption of carbon increased from 1.5 g/g biomass to 2.0 g/g biomass when the medium concentration of phosphorus was decreased from 0.18 to 0.027 g/L. PMID:18595075

  7. Pseudomonas fluorescens PICF7 displays an endophytic lifestyle in cultivated cereals and enhances yield in barley.

    PubMed

    Mercado-Blanco, Jesús; Alós, Enriqueta; Rey, María Dolores; Prieto, Pilar

    2016-08-01

    Pseudomonas fluorescens PICF7, an indigenous inhabitant of olive roots, displays an endophytic lifestyle in this woody crop and exerts biocontrol against the fungal phytopathogen Verticillium dahliae Here we report microscopy evidence that the strain PICF7 is also able to colonize and persist on or in wheat and barley root tissues. Root colonization of both cereal species followed a similar pattern to that previously reported in olive, including inner colonization of the root hairs. This demonstrates that strain PICF7 can colonize root systems of distant botanical species. Barley plants germinated from PICF7-treated seeds showed enhanced vegetative growth. Moreover, significant increases in the number of grains (up to 19.5%) and grain weight (up to 20.5%) per plant were scored in this species. In contrast, growth and yield were not significantly affected in wheat plants by the presence of PICF7. Proteomics analysis of the root systems revealed that different proteins were exclusively found depending on the presence or absence of PICF7 and only one protein with hydrogen ion transmembrane transporter activity was exclusively found in both PICF7-inoculated barley and wheat plants but not in the controls. PMID:27130938

  8. 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

  9. Partial purification and characterization of manganese-oxidizing factors of Pseudomonas fluorescens GB-1.

    PubMed Central

    Okazaki, M; Sugita, T; Shimizu, M; Ohode, Y; Iwamoto, K; de Vrind-de Jong, E W; de Vrind, J P; Corstjens, P L

    1997-01-01

    The Mn(2+)-oxidizing bacterium Pseudomonas fluorescens GB-1 deposits Mn oxide around the cell. During growth of a culture, the Mn(2+)-oxidizing activity of the cells first appeared in the early stationary growth phase. It depended on the O2 concentration in the culture during the late logarithmic growth phase. Maximal activity was observed at an oxygen concentration of 26% saturation. The activity could be recovered in cell extracts and was proportional to the protein concentration in the cell extracts. The specific activity was increased 125-fold by ammonium sulfate precipitation followed by reversed-phase and gel filtration column chromatographies. The activity of the partly purified Mn(2+)-oxidizing preparation had a pH optimum of circa 7 and a temperature optimum of 35 degrees C and was lost by heating. The Mn(2+)-oxidizing activity was sensitive to NaN3 and HgCl2. It was inhibited by KCN, EDTA, Tris, and o-phenanthroline. Although most data indicated the involvement of protein in Mn2+ oxidation, the activity was slightly stimulated by sodium dodecyl sulfate at a low concentration and by treatment with pronase and V8 protease. By polyacrylamide gel electrophoresis, two Mn(2+)-oxidizing factors with estimated molecular weights of 180,000 and 250,000 were detected. PMID:9406397

  10. Mechanisms of biodegradation of metal-citrate complexes by Pseudomonas fluorescens.

    PubMed Central

    Joshi-Tope, G; Francis, A J

    1995-01-01

    Biodegradation of metal-citrate complexes by Pseudomonas fluorescens depends on the nature of the complex formed between the metal and citric acid. Bidentate Fe(III)-, Ni-, and Zn-citrate complexes were readily biodegraded, but the tridentate Cd- and Cu-citrate, and U-citrate complexes were not. The biodegradation of Ni- and Zn-citrate commenced after an initial lag period; the former showed only partial (70%) degradation, whereas the latter was completely degraded. Uptake studies with 14C-labeled citric acid and metal-citrate complexes showed that cells grown in medium containing citric acid transported free citric acid at the rate of 28 nmol min-1 and Fe(III)-citrate at the rate of 12.6 nmol min-1 but not Cd-, Cu-, Ni-, U-, and Zn-citrate complexes. However, cells grown in medium containing Ni- or Zn-citrate transported both Ni- and Zn-citrate, suggesting the involvement of a common, inducible transport factor. Cell extracts degraded Fe(III)-, Ni-, U-, and Zn-citrate complexes in the following order: The cell extract did not degrade Cd- or Cu-citrate complexes. These results show that the biodegradation of the U-citrate complex was limited by the lack of transport inside the cell and that the tridentate Cd- and Cu-citrate complexes were neither transported inside the cell nor metabolized by the bacterium. PMID:7721690

  11. Utilization of benzylpenicillin as carbon, nitrogen and energy source by a Pseudomonas fluorescens strain.

    PubMed

    Johnsen, J

    1977-12-15

    A bacterium which utilizes benzylpenicillin as carbon, nitrogen and energy source was isolated from a lake sediment. The organism was identified as a strain of Pseudomonas fluorescens with a GC content of 59.71 Mol%. After growth of the organism on a mineral salts medium containing benzylpenicillin, the derivatives benzylpenicilloic acid, benzylpenilloic acid and benzylpenicillenic acid were found in culture media. There was no indication that the phenylacetate side chain of benzylpenicillin is decomposed. In uninoculated culture media benzylpenicillin, benzylpenicilloic acid and benzylpenicillenic acid were demonstrable. The following compounds were found to be absent from inoculated or uninoculated culture fluids: D-penicillamine, L-valine, L-cysteine, benzylpenillic acid and 6-aminopenicillanic acid. The organism possesses penicillinase. Penicillin acylase was not demonstrable. The reaction product of penicillinase, benzylpenicilloic acid, supports only little growth. There is no growth on 6-aminopenicillanic acid with or without NH4Cl. Relatively little growth occurs on 6-aminopenicillanic acid in the presence of phenylacetic acid. The data indicate that the nucleus of the benzylpenicillin molecule is utilized as carbon, nitrogen and energy source. During growth a part of the substrate is destroyed into scarcely usable benzylpenicilloic acid; hereby the antibiotic is detoxified. PMID:414683

  12. Technoeconomic analysis of large scale production of pre-emergent Pseudomonas fluorescens microbial bioherbicide in Canada.

    PubMed

    Mupondwa, Edmund; Li, Xue; Boyetchko, Susan; Hynes, Russell; Geissler, Jon

    2015-01-01

    The study presents an ex ante technoeconomic analysis of commercial production of Pseudomonas fluorescens BRG100 bioherbicide in Canada. An engineering economic model is designed in SuperPro Designer® to investigate capital investment scaling and profitability. Total capital investment for a stand-alone BRG100 fermentation plant at baseline capacity (two 33,000L fermenters; 3602tonnesannum(-1)) is $17.55million. Total annual operating cost is $14.76million. Raw materials account for 50% of operating cost. The fermentation plant is profitable over wide operating scale, evaluated over a range of BRG100 prices and costs of capital. Smaller plants require higher NPV breakeven prices. However, larger plants are more sensitive to changes in the cost of capital. Unit production costs decrease as plant capacity increases, indicating scale economies. A plant operating for less than one year approaches positive NPV for periods as low as 2months. These findings can support bioherbicide R&D investment and commercialization strategies. PMID:25459863

  13. 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. PMID:26920481

  14. 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. PMID:25892516

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

    PubMed

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

    2015-03-01

    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

  16. Role of a phenazine antibiotic from Pseudomonas fluorescens in biological control of Gaeumannomyces graminis var. tritici.

    PubMed Central

    Thomashow, L S; Weller, D M

    1988-01-01

    Pseudomonas fluorescens 2-79 (NRRL B-15132) and its rifampin-resistant derivative 2-79RN10 are suppressive to take-all, a major root disease of wheat caused by Gaeumannomyces graminis var. tritici. Strain 2-79 produces the antibiotic phenazine-1-carboxylate, which is active in vitro against G. graminis var. tritici and other fungal root pathogens. Mutants defective in phenazine synthesis (Phz-) were generated by Tn5 insertion and then compared with the parental strain to determine the importance of the antibiotic in take-all suppression on wheat roots. Six independent, prototrophic Phz- mutants were noninhibitory to G. graminis var. tritici in vitro and provided significantly less control of take-all than strain 2-79 on wheat seedlings. Antibiotic synthesis, fungal inhibition in vitro, and suppression of take-all on wheat were coordinately restored in two mutants complemented with cloned DNA from a 2-79 genomic library. These mutants contained Tn5 insertions in adjacent EcoRI fragments in the 2-79 genome, and the restriction maps of the region flanking the insertions and the complementary DNA were colinear. These results indicate that sequences required for phenazine production were present in the cloned DNA and support the importance of the phenazine antibiotic in disease suppression in the rhizosphere. Images PMID:2841289

  17. Purification and characterization of a ferulic acid decarboxylase from Pseudomonas fluorescens.

    PubMed Central

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

    1994-01-01

    A ferulic acid decarboxylase enzyme which catalyzes the decarboxylation of ferulic acid to 4-hydroxy-3-methoxystyrene was purified from Pseudomonas fluorescens UI 670. The enzyme requires no cofactors and contains no prosthetic groups. Gel filtration estimated an apparent molecular mass of 40.4 (+/- 6%) kDa, whereas sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a molecular mass of 20.4 kDa, indicating that ferulic acid decarboxylase is a homodimer in solution. The purified enzyme displayed an optimum temperature range of 27 to 30 degrees C, exhibited an optimum pH of 7.3 in potassium phosphate buffer, and had a Km of 7.9 mM for ferulic acid. This enzyme also decarboxylated 4-hydroxycinnamic acid but not 2- or 3-hydroxycinnamic acid, indicating that a hydroxy group para to the carboxylic acid-containing side chain is required for the enzymatic reaction. The enzyme was inactivated by Hg2+, Cu2+, p-chloromercuribenzoic acid, and N-ethylmaleimide, suggesting that sulfhydryl groups are necessary for enzyme activity. Diethyl pyrocarbonate, a histidine-specific inhibitor, did not affect enzyme activity. Images PMID:7928951

  18. Biochemical characterization of a multiple heavy metal, pesticides and phenol resistant Pseudomonas fluorescens strain.

    PubMed

    Wasi, Samina; Jeelani, Ghulam; Ahmad, Masood

    2008-04-01

    Pseudomonas fluorescens SM1 isolate was found to be resistant to some major water pollutants namely Cd2+, Cr6+, Cu2+, Ni2+, Pb2+, BHC, 2,4-D, mancozeb and phenols up to a concentration four times to the normal levels occurring in the highly pollulated regions. Curing experiment brought about the loss of one or more resistance markers indicating the plasmid born resistance. Plasmid profile of SM1 strain showed the presence of one DNA band of 43.6 kb. This Plasmid was isolated from SM1 strain and introduced into Escherichia coli DH5 alpha with a transformation frequency of 6.7 x 10(-4)transformants/recipient cell. The test SM1 strain was also capable of biotransforming Cr(VI) to Cr(III) which is less toxic compounds. Present studies further indicated that the test SM1 strain was not only resistant to 2,4-D, phenols and catechol but also capable of bioremediating these toxicants quite efficiently. Moreover, studies with inhibitors like sodium azide, 2,4-DNP and chloramphenicol suggested that the major mechanism for the bioremediation of the heavy metals other than Cr6+ would be the biosorption process. PMID:18164050

  19. Extracellular enzyme production and cheating in Pseudomonas fluorescens depend on diffusion rates

    PubMed Central

    Allison, Steven D.; Lu, Lucy; Kent, Alyssa G.; Martiny, Adam C.

    2014-01-01

    Bacteria produce extracellular enzymes to obtain resources from complex chemical substrates, but this strategy is vulnerable to cheating by cells that take up reaction products without paying the cost of enzyme production. We hypothesized that cheating would suppress enzyme production in co-cultures of cheater and producer bacteria, particularly under well-mixed conditions. To test this hypothesis, we monitored protease expression and frequencies of Pseudomonas fluorescens producer and cheater genotypes over time in mixed liquid cultures and on agar plates. In mixed culture inoculated with equal frequencies of cheaters and producers, enzyme concentration declined to zero after 20 days, consistent with our hypothesis. We observed a similar decline in cultures inoculated with producers only, suggesting that cheater mutants arose de novo and swept the population. DNA sequencing showed that genetic changes most likely occurred outside the protease operon. In one experimental replicate, the population regained the ability to produce protease, likely due to further genetic changes or population dynamics. Under spatially structured conditions on agar plates, cheaters did not sweep the population. Instead, we observed a significant increase in the variation of enzyme activity levels expressed by clones isolated from the population. Together these results suggest that restricted diffusion favors a diversity of enzyme production strategies. In contrast, well-mixed conditions favor population sweeps by cheater strains, consistent with theoretical predictions. Cheater and producer strategies likely coexist in natural environments with the frequency of cheating increasing with diffusion rate. PMID:24782855

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

    PubMed Central

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

    2012-01-01

    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. PMID:23170230

  1. 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

  2. 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. PMID:26723126

  3. 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

  4. Environmental Factors Modulating Antibiotic and Siderophore Biosynthesis by Pseudomonas fluorescens Biocontrol Strains

    PubMed Central

    Duffy, Brion K.; Défago, Geneviève

    1999-01-01

    Understanding the environmental factors that regulate the biosynthesis of antimicrobial compounds by disease-suppressive strains of Pseudomonas fluorescens is an essential step toward improving the level and reliability of their biocontrol activity. We used liquid culture assays to identify several minerals and carbon sources which had a differential influence on the production of the antibiotics 2,4-diacetylphloroglucinol (PHL), pyoluteorin (PLT), and pyrrolnitrin and the siderophores salicylic acid and pyochelin by the model strain CHA0, which was isolated from a natural disease-suppressive soil in Switzerland. Production of PHL was stimulated by Zn2+, NH4Mo2+, and glucose; the precursor compound mono-acetylphloroglucinol was stimulated by the same factors as PHL. Production of PLT was stimulated by Zn2+, Co2+, and glycerol but was repressed by glucose. Pyrrolnitrin production was increased by fructose, mannitol, and a mixture of Zn2+ and NH4Mo2+. Pyochelin production was increased by Co2+, fructose, mannitol, and glucose. Interestingly, production of its precursor salicylic acid was increased by different factors, i.e., NH4Mo2+, glycerol, and glucose. The mixture of Zn2+ and NH4Mo2+ with fructose, mannitol, or glycerol further enhanced the production of PHL and PLT compared with either the minerals or the carbon sources used alone, but it did not improve siderophore production. Extending fermentation time from 2 to 5 days increased the accumulation of PLT, pyrrolnitrin, and pyochelin but not of PHL. When findings with CHA0 were extended to an ecologically and genetically diverse collection of 41 P. fluorescens biocontrol strains, the effect of certain factors was strain dependent, while others had a general effect. Stimulation of PHL by Zn2+ and glucose was strain dependent, whereas PLT production by all strains that can produce this compound was stimulated by Zn2+ and transiently repressed by glucose. Inorganic phosphate reduced PHL production by CHA0 and seven

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

    PubMed

    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

  6. 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

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

    PubMed

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

    2016-03-01

    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

  8. 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

  9. The clinical Pseudomonas fluorescens MFN1032 strain exerts a cytotoxic effect on epithelial intestinal cells and induces Interleukin-8 via the AP-1 signaling pathway

    PubMed Central

    2010-01-01

    Background Pseudomonas fluorescens is present in low number in the intestinal lumen and has been proposed to play a role in Crohn's disease (CD). Indeed, a highly specific antigen, I2, has been detected in CD patients and correlated to the severity of the disease. We aimed to determine whether P. fluorescens was able to adhere to human intestinal epithelial cells (IECs), induce cytotoxicity and activate a proinflammatory response. Results Behaviour of the clinical strain P. fluorescens MFN1032 was compared to that of the psychrotrophic strain P. fluorescens MF37 and the opportunistic pathogen P. aeruginosa PAO1. Both strains of P. fluorescens were found to adhere on Caco-2/TC7 and HT-29 cells. Their cytotoxicity towards these two cell lines determined by LDH release assays was dose-dependent and higher for the clinical strain MFN1032 than for MF37 but lower than P. aeruginosa PAO1. The two strains of P. fluorescens also induced IL-8 secretion by Caco-2/TC7 and HT-29 cells via the AP-1 signaling pathway whereas P. aeruginosa PAO1 potentially used the NF-κB pathway. Conclusions The present work shows, for the first time, that P. fluorescens MFN1032 is able to adhere to IECs, exert cytotoxic effects and induce a proinflammatory reaction. Our results are consistent with a possible contribution of P. fluorescens in CD and could explain the presence of specific antibodies against this bacterium in the blood of patients. PMID:20698984

  10. 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.