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FEMS Microbiology Ecology Aug 2016Microorganisms can be versatile in their interactions with each other, being variously beneficial, neutral or antagonistic in their effect. Although this versatility has...
Microorganisms can be versatile in their interactions with each other, being variously beneficial, neutral or antagonistic in their effect. Although this versatility has been observed among many microorganisms and in many environments, little is known regarding the mechanisms leading to these changes in behavior. In the present work, we analyzed the mechanism by which the soil bacterium Pseudomonas fluorescens BBc6R8 shifts from stimulating the growth of the ectomycorrhizal fungus Laccaria bicolor S238N to killing the fungus. We show that among the three secondary metabolites produced by the bacterial strain-the siderophores enantio-pyochelin and pyoverdine, and the biosurfactant viscosin-the siderophores are mainly responsible for the antagonistic activity of the bacterium under iron-limited conditions. While the bacterial strain continues to produce beneficial factors, their effects are overridden by the action of their siderophores. This antagonistic activity of the strain P. fluorescens BBC6R8 in iron-depleted environments is not restricted to its influence on L. bicolor, since it was also seen to inhibit the growth of the actinomycete Streptomyces ambofaciens ATCC23877. We show that the strain P. fluorescens BBc6R8 uses different strategies to acquire iron, depending on certain biotic and abiotic factors.
Topics: Iron; Mycorrhizae; Oligopeptides; Phenols; Pseudomonas fluorescens; Siderophores; Soil; Soil Microbiology; Streptomyces; Thiazoles
PubMed: 27199346
DOI: 10.1093/femsec/fiw107 -
FEMS Microbiology Letters Apr 2007DNA microarray technology was used to survey changes in gene expression in Pseudomonas fluorescens after mitomycin C treatment. As expected, genes associated with the...
DNA microarray technology was used to survey changes in gene expression in Pseudomonas fluorescens after mitomycin C treatment. As expected, genes associated with the SOS response were upregulated, such as those encoding the recombination protein RecA, DNA repair protein RecN, excinuclease ABC subunit A UvrA, and the LexA repressor protein. Interestingly, expression of 33 clustered bacteriophage-like genes was upregulated, suggesting that mitomycin C (MMC) may induce a prophage resident in the P. fluorescens genome. However, no phage particles were detected in P. fluorescens strain DC206 that had been treated with MMC using transmission electron microscopy. The same preparation failed to produce phage plaques on lawns of any of 10 different Pseudomonas strains tested, indicating that the 33 bacteriophage-like gene cluster represents a defective prophage.
Topics: Bacterial Proteins; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Genome, Bacterial; Mitomycin; Oligonucleotide Array Sequence Analysis; Pseudomonas Phages; Pseudomonas fluorescens; SOS Response, Genetics; Transcription, Genetic; Up-Regulation; Virus Activation
PubMed: 17250760
DOI: 10.1111/j.1574-6968.2007.00630.x -
Microbiology (Reading, England) Jun 2012R-type and F-type pyocins are high-molecular-mass bacteriocins produced by Pseudomonas aeruginosa that resemble bacteriophage tails. They contain no head structures and...
R-type and F-type pyocins are high-molecular-mass bacteriocins produced by Pseudomonas aeruginosa that resemble bacteriophage tails. They contain no head structures and no DNA, and are used as defence systems. In this report, we show that Pseudomonas fluorescens SF4c, a strain isolated from the wheat rhizosphere, produces a high-molecular-mass bacteriocin which inhibits the growth of closely related bacteria. A mutant deficient in production of this antimicrobial compound was obtained by transposon mutagenesis. Sequence analysis revealed that the transposon had disrupted a gene that we have named ptm, since it is homologous to that encoding phage tape-measure protein in P. fluorescens Pf0-1, a gene belonging to a prophage similar to phage-like pyocin from P. aeruginosa PAO1. In addition, we have identified genes from the SF4c pyocin cluster that encode a lytic system and regulatory genes. We constructed a non-polar ptm mutant of P. fluorescens SF4c. Heterologous complementation of this mutation restored the production of bacteriocin. Real-time PCR was used to analyse the expression of pyocin under different stress conditions. Bacteriocin was upregulated by mitomycin C, UV light and hydrogen peroxide, and was downregulated by saline stress. This report constitutes, to our knowledge, the first genetic characterization of a phage tail-like bacteriocin in a rhizosphere Pseudomonas strain.
Topics: Anti-Bacterial Agents; Bacteriophages; Molecular Sequence Data; Molecular Weight; Pseudomonas fluorescens; Pyocins; Rhizosphere; Soil Microbiology; Triticum
PubMed: 22442306
DOI: 10.1099/mic.0.056002-0 -
Biofouling 2014Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor Pseudomonas fluorescens biofilms in situ, non-destructively, in real...
Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor Pseudomonas fluorescens biofilms in situ, non-destructively, in real time, and under fully hydrated conditions. Changes accompanying the metabolic evolution of the sessile bacterial cells from the nascent biofilm monolayer to the beginning of the multi-layered structure in the presence of nutrients were identified via the ATR-FTIR fingerprints of the young biofilm on the ATR crystal. The ATR-FTIR spectra were analysed by classical methods (time evolution of integrated intensities and profile evolution of specific bands), and also by a multivariate curve resolution, Bayesian positive source separation, to extract the pure component spectra and their change of concentration over time occurring during biofilm settlement. This work showed clearly the overproduction of glycogen by sessile P. fluorescens, which had not previously been described by other research groups.
Topics: Bayes Theorem; Biofilms; Glycogen; Microscopy, Fluorescence; Multivariate Analysis; Pseudomonas fluorescens; Spectroscopy, Fourier Transform Infrared
PubMed: 24835847
DOI: 10.1080/08927014.2014.915956 -
Microbiological Research 2006Pseudomonas flourescens NCIM 2100 was obtained from NCL, Pune, India, that was adapted to growth on 4 amino 1-1 azo benzene 3,4-Disulfonic acid. This strains was tested...
Pseudomonas flourescens NCIM 2100 was obtained from NCL, Pune, India, that was adapted to growth on 4 amino 1-1 azo benzene 3,4-Disulfonic acid. This strains was tested by UV, (1)H NMR, and IR spectroscopy for its ability to degrade the dye which resulted in to sulfonated analogs namely p-amino benzene sulfonic acid sodium salt and 2,4 diamino benzene sulfonic acid sodium salt. These compound further changed to either 2,4 dihydroxy benzene sulfonic acid sodium salt or 2 amino 4 hydroxy benzene sulfonic acid sodium salt, or 4 amino 2 hydroxy benzene sulfonic acid sodium salt. These breakdown compounds were non toxic in nature.
Topics: Azo Compounds; Biodegradation, Environmental; Magnetic Resonance Spectroscopy; Pseudomonas fluorescens; Substrate Specificity
PubMed: 16412621
DOI: 10.1016/j.micres.2005.11.003 -
Advances in Experimental Medicine and... 1990
Topics: Chromatography, Gas; Endotoxins; Magnetic Resonance Spectroscopy; Oligosaccharides; Phenotype; Pseudomonas fluorescens
PubMed: 2109500
DOI: 10.1007/978-1-4757-5140-6_9 -
Biofouling 2007This study investigated the phenotypic characteristics of monoculture P. fluorescens biofilms grown under turbulent and laminar flow, using flow cells reactors with...
This study investigated the phenotypic characteristics of monoculture P. fluorescens biofilms grown under turbulent and laminar flow, using flow cells reactors with stainless steel substrata. The cellular physiology and the overall biofilm activity, structure and composition were characterized, and compared, within hydrodynamically distinct conditions. The results indicate that turbulent flow-generated biofilm cells were significantly less extensive, with decreased metabolic activity and a lower protein and polysaccharides composition per cell than those from laminar flow-generated biofilms. The effect of flow regime did not cause significantly different outer membrane protein expression. From the analysis of biofilm activity, structure and composition, turbulent flow-generated biofilms were metabolically more active, had twice more mass per cm(2), and higher cellular density and protein content (mainly cellular) than laminar flow-generated biofilms. Conversely, laminar flow-generated biofilms presented higher total and matrix polysaccharide contents. Direct visualisation and scanning electron microscopy analysis showed that these different flows generate structurally different biofilms, corroborating the quantitative results. The combination of applied methods provided useful information regarding a broad spectrum of biofilm parameters, which can contribute to control and model biofilm processes.
Topics: Bacterial Proteins; Biofilms; Microbial Viability; Microscopy, Electron, Scanning; Oxygen; Phenotype; Polysaccharides; Pseudomonas fluorescens; Water Movements
PubMed: 17653934
DOI: 10.1080/08927010701368476 -
Applied and Environmental Microbiology Feb 2000Transposon mutant strain 3G6 of Pseudomonas fluorescens ATCC 17400 which was deficient in pyoverdine production, was found to produce another iron-chelating molecule;...
Transposon mutant strain 3G6 of Pseudomonas fluorescens ATCC 17400 which was deficient in pyoverdine production, was found to produce another iron-chelating molecule; this molecule was identified as 8-hydroxy-4-methoxy-quinaldic acid (designated quinolobactin). The pyoverdine-deficient mutant produced a supplementary 75-kDa iron-repressed outer membrane protein (IROMP) in addition to the 85-kDa IROMP present in the wild type. The mutant was also characterized by substantially increased uptake of (59)Fe-quinolobactin. The 75-kDa IROMP was produced by the wild type after induction by quinolobactin-containing culture supernatants obtained from the pyoverdine-negative mutant or by purified quinolobactin. Conversely, adding purified wild-type pyoverdine to the growth medium resulted in suppression of the 75-kDa IROMP in the pyoverdine-deficient mutant; however, suppression was not observed when Pseudomonas aeruginosa PAO1 pyoverdine, a siderophore utilized by strain 3G6, was added to the culture. Therefore, we assume that the quinolobactin receptor is the 75-kDa IROMP and that the quinolobactin-mediated iron uptake system is repressed by the cognate pyoverdine.
Topics: Bacterial Outer Membrane Proteins; Culture Media; DNA Transposable Elements; Electrophoresis, Polyacrylamide Gel; Iron; Mutagenesis, Insertional; Oligopeptides; Pigments, Biological; Pseudomonas fluorescens; Quinolines; Siderophores
PubMed: 10653708
DOI: 10.1128/AEM.66.2.487-492.2000 -
Phytopathology Dec 2010The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of...
The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in 10 field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to blossoms influenced establishment of the pathogen and the efficacy of biological control. Pantoea vagans C9-1 suppressed fire blight in all five trials in which the pathogen was applied as lyophilized cells but in none of the trials in which the pathogen was applied as freshly harvested cells. In contrast, Pseudomonas fluorescens A506 reduced disease significantly in only one trial. A mixture of the two strains also suppressed fire blight, but the magnitude of disease suppression over all field trials (averaging 32%) was less than that attained by C9-1 alone (42%). The two biological control agents did not antagonize one another on blossom surfaces, and application of the mixture of A506 and C9-1 to blossoms resulted in a greater proportion of flowers having detectable populations of at least one bacterial antagonist than the application of individual strains. Therefore, the mixture of A506 and C9-1 provided less disease control than expected based upon the epiphytic population sizes of the antagonists on blossom surfaces. We speculate that the biocontrol mixture was less effective than anticipated due to incompatibility between the mechanisms by which A506 and C9-1 suppress disease.
Topics: Malus; Pantoea; Plant Diseases; Pseudomonas fluorescens; Pyrus; Trees
PubMed: 20839963
DOI: 10.1094/PHYTO-03-10-0097 -
International Journal of Biological... Jul 2019Nanotechnology is one of the most fascinating sciences with a great potential to improve many agricultural products. Use of nanoparticles in plant disease management is...
Nanotechnology is one of the most fascinating sciences with a great potential to improve many agricultural products. Use of nanoparticles in plant disease management is a novel area which may prove very effective in future. Use of nanomaterials and biocompatible compounds in nano-encapsulation of antagonist bacteria is an important step in enhancing the efficiency of these agents in adverse environmental conditions. Two strains of Pseudomonas fluorescens (VUPF5 and T17-4) were used for alginate-gelatin nanocomposite beads with different concentrations of gelatin. The moisture content, swelling, and releasing of encapsulated viable bacteria was investigated in vitro and in vivo conditions. The results of FT-IR and X-ray diffraction analysis revealed that when gelatin was added into sodium alginate, electrostatic interaction occurred. The swelling and moisture content of nanocomposite beads grew with gelatin enhancement. The maximum encapsulation efficiency at the gelatin concentration of 1.5% in VUPF5 and T17-4 was 91.23% and 87.23%, respectively. Further, the greenhouse experiment showed that inoculation of potato with bacterial strains and nanocomposite beads of these strains reduced disease incidence. The encapsulation method described in this study can be effectively used to protect the plant probiotic bacteria inoculum from harmful conditions of the soil for its successful establishment in the rhizosphere.
Topics: Alginates; Biofilms; Capsules; Fusarium; Gelatin; Hydrogen Cyanide; Hydrogen-Ion Concentration; Nanocomposites; Nanotechnology; Peptide Hydrolases; Pseudomonas fluorescens; Solanum tuberosum; Temperature
PubMed: 31004642
DOI: 10.1016/j.ijbiomac.2019.04.071