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Applied Microbiology and Biotechnology Mar 2013The EmhABC efflux pump in Pseudomonas fluorescens LP6a effluxes polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene and anthracene but not naphthalene. We...
The EmhABC efflux pump in Pseudomonas fluorescens LP6a effluxes polycyclic aromatic hydrocarbons (PAHs) such as phenanthrene and anthracene but not naphthalene. We previously showed that the presence of EmhABC decreased the efficiency of phenanthrene biodegradation. In this study, we determined whether P. fluorescens LP6a tolerance to naphthalene is a function of the EmhABC efflux pump and how its presence affects the efficiency of naphthalene biodegradation. Growth, membrane fatty acid (FA) composition, and cell morphology showed that 5-mmol L(-1) naphthalene is inhibitory to P. fluorescens LP6a strains. The deleterious effect of naphthalene is suppressed in the presence of EmhABC, which suggests that, although naphthalene is not effluxed by EmhABC, this efflux pump is involved in tolerance of naphthalene toxicity. LP6a mutants lacking the EmhB efflux pump were unable to convert cis-unsaturated FAs to cyclopropane FAs, indicating that naphthalene interferes with the formation of cyclopropane FAs and supporting the proposal that EmhABC is involved in FA turnover in P. fluorescens LP6a strains. The EmhABC efflux pump increases the efficiency of naphthalene metabolism in strain LP6a, which may make naphthalene efflux unnecessary. Thus, the activity of hydrocarbon efflux pumps may be an important factor to consider when selecting bacterial strains for bioremediation or biocatalysis of PAHs.
Topics: Anti-Bacterial Agents; Biological Transport, Active; Biotransformation; Fatty Acids; Gene Deletion; Membrane Transport Proteins; Metabolic Networks and Pathways; Microbial Sensitivity Tests; Naphthalenes; Pseudomonas fluorescens
PubMed: 22940805
DOI: 10.1007/s00253-012-4373-9 -
ACS Applied Materials & Interfaces Jan 2009Bacterial adhesion and spreading on biomaterials are considered key features of pathogenicity. Roughness and topography of the substrate have been reported to affect...
Bacterial adhesion and spreading on biomaterials are considered key features of pathogenicity. Roughness and topography of the substrate have been reported to affect bacterial adhesion, but little is known about their effect on spreading. Submicron row and channel tuning with bacterial diameter (S2) were designed to test bacterial motility on these surfaces. Random nanometer-sized structures (S1) were used as controls. Optical microscopy and AFM were employed to detect biological and surface pattern details in the micro- and nanoscale, respectively. Results showed that motility strategies (flagella orientation, elongation, aggregation in rafts, formation of network structures, and development of a bacterial frontier) were affected by the presence of submicropatterns. Importantly, the rate of bacterial spreading on S2 was significantly reduced and influenced by the orientation of the submicropatterns. Consequently, submicroengineered substrates could be employed as a tool to downgrade bacterial colonization. Such patterns could impact on the design of proper engineered structures to control biofilm spreading on solid surfaces.
Topics: Bacterial Adhesion; Biofilms; Colony Count, Microbial; Gold; Microscopy, Atomic Force; Microtechnology; Pseudomonas fluorescens; Surface Properties
PubMed: 20355765
DOI: 10.1021/am8000677 -
Current Microbiology Jul 2003Four different bacterial isolates obtained from a stable bacterial consortium were capable of utilizing pentachlorophenol (PCP) as sole carbon and energy source. The...
Four different bacterial isolates obtained from a stable bacterial consortium were capable of utilizing pentachlorophenol (PCP) as sole carbon and energy source. The consortium was developed by continuous enrichment in the chemostat. The degradation of PCP by bacterial strain was preceded through an oxidative route as indicated by accumulation of tetrachloro-rho-hydroquinone and dichlorohydroquinone as determined by high performance liquid chromatography (HPLC). Among the four isolates, Pseudomonas fluorescens exhibited maximum degradation capability and enzyme production. PCP-monooxygenase enzyme was extracted from culture extract and fractionated by DEAE-cellulose ion exchange chromatography. The molecular weight of the enzyme, purified from Pseudomonas fluorescens, determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography was found to be 24000 Da.
Topics: Biodegradation, Environmental; Chromatography, High Pressure Liquid; Culture Media; India; Industrial Waste; Mixed Function Oxygenases; Oxidation-Reduction; Pentachlorophenol; Pseudomonas fluorescens; Tanning
PubMed: 12783196
DOI: 10.1007/s00284-002-3927-y -
Virologica Sinica Feb 2015
Topics: Bacteriophages; Biological Therapy; Humans; Pseudomonas Infections; Pseudomonas fluorescens
PubMed: 25595213
DOI: 10.1007/s12250-014-3490-2 -
Journal of Microbiology (Seoul, Korea) Dec 2011Sclerotinia stem rot (SSR) caused by the fungus Sclerotinia sclerotiorum has been an increasing threat to oilseed rape (Brassica napus L.) cultivation. Efficient and...
Sclerotinia stem rot (SSR) caused by the fungus Sclerotinia sclerotiorum has been an increasing threat to oilseed rape (Brassica napus L.) cultivation. Efficient and environment-friendly treatments are much needed. Here we focus on microbial control. The Pseudomonas fluorescens P13 that was isolated from oilseed rape cultivation soil, proved to be a useful biocontrol strain for application. Morphology, physiological and biochemical tests and 16S rDNA analysis demonstrated that it was P. fluorescens P13 and that it had a broad antagonistic spectrum, significantly lessening the mycelial growth of S. sclerotiorum by 84.4% and suppressing sclerotial formation by 95-100%. Scanning electron microscopy studies attested that P13 deformed S. sclerotiorum mycelia when they were cultured together. P13 did not produce chitinase but did produce hydrogen cyanide (HCN) which was likely one of the antagonistic mechanisms. The density of P13 remained at a high level (≥10(6) CFU/ml) during 5 weeks in the rhizosphere soil and roots. P13 reduced SSR severity at least by 59% in field studies and also promoted seedling growth (p<0.05) at the seedling stage. From these data, our work provided evidence that P13 could be a good alternative biological resource for biocontrol of S. sclerotiorum.
Topics: Antibiosis; Ascomycota; Brassica rapa; Molecular Sequence Data; Pest Control, Biological; Plant Diseases; Plant Stems; Pseudomonas fluorescens
PubMed: 22203550
DOI: 10.1007/s12275-011-1261-4 -
Letters in Applied Microbiology 2003To improve the efficacy of Pseudomonas fluorescens CHA0 and its genetically modified (GM) derivatives by adding ammonium molybdate to control Meloidogyne javanica, the...
AIMS
To improve the efficacy of Pseudomonas fluorescens CHA0 and its genetically modified (GM) derivatives by adding ammonium molybdate to control Meloidogyne javanica, the root-knot nematode in mungbean.
METHODS AND RESULTS
Culture filtrate of P. fluorescens CHA0 and its GM derivative (antibiotic overproducing strain CHA0/pME3424 and antibiotic-deficient CHA89) obtained from nutrient broth yeast extract medium amended with 1, 2 or 4 mm of ammonium molybdate (NH4-Mo) caused substantial mortality of M. javanica juveniles in vitro. Pseudomonas fluorescens CHA0 or CHA0/pME3424 applied in conjunction with NH4-Mo caused greater reduction of nematode penetration in mungbean roots compared with the bacterial application alone. Ammonium molybdate at 4 mg kg-1 of soil along with CHA0 also enhanced plant height while shoot weight remained unaffected. Either used alone or in conjunction with NH4-Mo, strain CHA89 did not reduce nematode invasion compared with the controls. Bacterial strains did not differ significantly in their colonization potential in the mungbean rhizosphere. Efficacy of the biocontrol bacteria to control root-knot nematode was accentuated when soil was treated with NH4-Mo and zinc (both at 1 mg kg-1 of soil).
CONCLUSION
The addition of ammonium molybdate enhances the production of nematicidal compounds by P. fluorescensin vitro and improves bacterial efficacy against root-knot nematode under glasshouse conditions.
SIGNIFICANCE AND IMPACT OF THE STUDY
Application of minerals such as ammonium molybdate is appealing because they are cheap and can easily be applied under field conditions to improve biocontrol potential of the bacterial inoculants. They also significantly reduce the amount of biocontrol inoculant biomass required to achieve root-knot disease control, with a consequent reduction in cost.
Topics: Animals; Biomass; Fabaceae; Molybdenum; Pest Control, Biological; Plant Diseases; Pseudomonas fluorescens; Tylenchoidea
PubMed: 12641719
DOI: 10.1046/j.1472-765x.2003.01299.x -
Carbohydrate Polymers Jan 2016Pseudomonas fluorescens, isolated from rhizosphere soil, was exploited for the production of exopolysaccharide (EPS). A medium was constituted to enhance the yield of...
Pseudomonas fluorescens, isolated from rhizosphere soil, was exploited for the production of exopolysaccharide (EPS). A medium was constituted to enhance the yield of EPS. This study involved an agro waste as carbon substrate, rice bran, a replacement of glucose. Plackett-Burman statistical design was applied to evaluate the selected sixteen components from which, rice bran, peptone, NaCl and MnCl2 were found to be effective and significant on the fermentation process. To study the concentration of each component, central composite design was carried out and response surface plots indicated that the following concentrations significantly enhanced the production - rice bran 5.02%, peptone 0.35%, NaCl 0.51%, MnCl2 0.074%. Kinetic modeling was also performed to simulate the process parameters. Logistic model for microbial growth and Luedeking-Piret equation for product formation and substrate utilization were found to fit the experiment. The present investigation resulted in a maximum yield of 4.62g of EPS/L at 48h. High DPPH scavenging ability was a positive indication to use EPS as an antioxidant. The extracted polysaccharide could thus be ecofriendly due to its biodegradability and nontoxicity, and subjected to various industrial and pharmaceutical applications.
Topics: Antioxidants; Biphenyl Compounds; Kinetics; Phylogeny; Picrates; Polysaccharides, Bacterial; Pseudomonas fluorescens; RNA, Bacterial; RNA, Ribosomal, 16S; Rhizosphere
PubMed: 26453848
DOI: 10.1016/j.carbpol.2015.08.080 -
Genome Biology 2009Pseudomonas fluorescens are common soil bacteria that can improve plant health through nutrient cycling, pathogen antagonism and induction of plant defenses. The genome...
BACKGROUND
Pseudomonas fluorescens are common soil bacteria that can improve plant health through nutrient cycling, pathogen antagonism and induction of plant defenses. The genome sequences of strains SBW25 and Pf0-1 were determined and compared to each other and with P. fluorescens Pf-5. A functional genomic in vivo expression technology (IVET) screen provided insight into genes used by P. fluorescens in its natural environment and an improved understanding of the ecological significance of diversity within this species.
RESULTS
Comparisons of three P. fluorescens genomes (SBW25, Pf0-1, Pf-5) revealed considerable divergence: 61% of genes are shared, the majority located near the replication origin. Phylogenetic and average amino acid identity analyses showed a low overall relationship. A functional screen of SBW25 defined 125 plant-induced genes including a range of functions specific to the plant environment. Orthologues of 83 of these exist in Pf0-1 and Pf-5, with 73 shared by both strains. The P. fluorescens genomes carry numerous complex repetitive DNA sequences, some resembling Miniature Inverted-repeat Transposable Elements (MITEs). In SBW25, repeat density and distribution revealed 'repeat deserts' lacking repeats, covering approximately 40% of the genome.
CONCLUSIONS
P. fluorescens genomes are highly diverse. Strain-specific regions around the replication terminus suggest genome compartmentalization. The genomic heterogeneity among the three strains is reminiscent of a species complex rather than a single species. That 42% of plant-inducible genes were not shared by all strains reinforces this conclusion and shows that ecological success requires specialized and core functions. The diversity also indicates the significant size of genetic information within the Pseudomonas pan genome.
Topics: Ecosystem; Genome, Bacterial; Plants; Pseudomonas fluorescens
PubMed: 19432983
DOI: 10.1186/gb-2009-10-5-r51 -
Bulletin of Environmental Contamination... Oct 1992
Topics: Decontamination; Industrial Waste; Nuclear Reactors; Pseudomonas fluorescens; Yttrium
PubMed: 1421858
DOI: 10.1007/BF00196308 -
Journal of Proteomics Oct 2016In the marine environment, bacteria from estuarine and coastal sediments are among the first targets of nanoparticle pollution; it is therefore relevant to improve the...
UNLABELLED
In the marine environment, bacteria from estuarine and coastal sediments are among the first targets of nanoparticle pollution; it is therefore relevant to improve the knowledge of interactions between bacteria and nanoparticles. In this work, the response of the marine bacterium Pseudomonas fluorescens BA3SM1 to CdSe nanocrystals (CdSe NPs) of 3nm (NP3) and 8nm (NP8) in diameter was evaluated through microscopic, physiological, biochemical and proteomic approaches. Transmission electron microscopy images showed that NP3 were able to penetrate the bacteria, while NP8 were highly concentrated around the cells, embedded in large exopolysaccharides. In our experimental conditions, both CdSe NP sizes induced a decrease in respiration during the stationary growth phase, while only NP8 caused growth retardation and a decrease in pyoverdine production. Proteomic analyses highlighted that the strain responded to CdSe NP toxicity by inducing various defence mechanisms such as cell aggregation, extracellular CdSe NP sequestration, effective protection against oxidative stress, modifications of envelope organization and properties, and cadmium export. In addition, BA3SM1 presented a biosorption capacity of 1.6×10(16)NP3/g dry weight and 1.7×10(15)NP8/g dry weight. This strain therefore appears as a promising agent for NP bioremediation processes. Proteomic data are available via ProteomeXchange with identifier PXD004012.
BIOLOGICAL SIGNIFICANCE
To the best of our knowledge, this is the first report focussing on the effects of CdSe colloidal nanocrystals (CdSe NPs) on a marine strain of Pseudomonas fluorescens. CdSe NPs are extensively used in the industry of renewable energies and it is regrettably expected that these pollutants will sometime soon appear in the marine environment through surface runoff, urban effluents and rivers. Bacteria living in estuarine and coastal sediments will be among the first targets of these new pollutants. The pseudomonads are frequently found in these ecosystems. They are involved in several biogeochemical cycles and are known for their high resistance to pollutants. Consequently, this study focussing on the effects of CdSe NPs on the marine strain P. fluorescens BA3SM1 is highly relevant for several reasons. First, it aims at improving knowledge about the interactions between bacteria and NPs. This is fundamental to effectively use NPs against pathogenic bacteria. Secondly, in spite of CdSe NP interactions with the bacterial cells, the strain BA3SM1 can develop various strategies to counteract CdSe NP toxicity and ensure its growth. It exhibits interesting properties to sequester CdSe NPs and it retains its ability to form biofilm. The strain therefore appears as a promising agent for NP bioremediation thanks to biofiltration processes. Finally, this study shows that CdSe NPs of 8nm in diameter cause a decrease in the secretion of siderophore pyoverdine, a secondary metabolite playing a key role in microbial ecology since it drives bacterial survival and competitiveness in ecosystems. Bacteria producing effective siderophores survive better in a Fe-deficient environment where they antagonize the growth of other microbes thought iron deprivation. Furthermore, siderophores are also employed as virulence factors in human pathogenic strains such as P. aeruginosa. Consequently, this study highlights that NPs can impact the secondary metabolism of bacteria with environmental and medical implications. In addition, in this work, Data-Dependant Acquisition (DDA) provided state of the art Mass Spectrometry data by Spectral Counting and MS1 Label-Free. The combination of these two well-known proteomic techniques including manual validations strengthened the identification and quantification of regulated proteins. Moreover, numerous correlations between proteomic analyses and other observations (physiological, biochemical, microscopic) consolidated our interpretations.
Topics: Biodegradation, Environmental; Cadmium Compounds; Ecosystem; Industrial Waste; Metal Nanoparticles; Particle Size; Proteomics; Pseudomonas fluorescens; Selenium Compounds; Water Pollutants, Chemical
PubMed: 27523480
DOI: 10.1016/j.jprot.2016.07.021