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Biotechnology Letters May 2016The adhesion of colloidal probes of stainless steel, glass and cellulose to Pseudomonas fluorescens biofilms was examined using atomic force microscopy (AFM) to allow...
OBJECTIVES
The adhesion of colloidal probes of stainless steel, glass and cellulose to Pseudomonas fluorescens biofilms was examined using atomic force microscopy (AFM) to allow comparisons between surfaces to which biofilms might adhere.
RESULTS
Biofilm was grown on a stainless steel substrate and covered most of the surface after 96 h. AFM approach and retraction curves were obtained when the biofilm was immersed in a tryptone/soy medium. On approach, all the colloidal probes experienced a long non-contact phase more than 100 nm in length, possibly due to the steric repulsion by extracellular polymers from the biofilm and hydrophobic effects. Retraction data showed that the adhesion varied from position to position on the biofilm. The mean value of adhesion of glass to the biofilm (48 ± 7 nN) was the greatest, followed by stainless steel (30 ± 7 nN) and cellulose (7.8 ± 0.4 nN).
CONCLUSION
The method allows understanding of adhesion between the three materials and biofilm, and development of a better strategy to remove the biofilm from these surfaces relevant to different industrial applications.
Topics: Bacterial Adhesion; Biofilms; Cellulose; Glass; Microscopy, Atomic Force; Pseudomonas fluorescens; Stainless Steel
PubMed: 26892223
DOI: 10.1007/s10529-016-2047-x -
Chemosphere Oct 2020Plant growth-promoting bacteria (PGPB) can promote root uptake and shoot accumulation of cadmium (Cd) in hyperaccumulator plants, but the mechanisms by which PGPB...
Plant growth-promoting bacteria (PGPB) can promote root uptake and shoot accumulation of cadmium (Cd) in hyperaccumulator plants, but the mechanisms by which PGPB accelerate root-to-shoot transport of Cd is still unknown. A better understanding of these mechanisms is necessary to develop the strategies that can promote the practical phytoextraction of Cd-polluted soils. In this study, we found that Pseudomonas fluorescens accelerates a reversed and a long-distance transport of Cd and sucrose in Sedum alfredii, by examining the xylem and phloem sap and by quantifying the concentrations of Cd and sucrose in shoot and root. The transcriptome sequencing has revealed the up-regulated expressions of starch metabolism and sucrose biosynthesis related genes in the shoots of Cd hyperaccumulator plant S. alfredii that was inoculated with PGPB P. fluorescens. In addition, the genes of sugar, cation and anion transporters were also up-regulated by bacterial treatment, showing a complicated co-expression network with sucrose biosynthesis related genes. The expression levels of Cd transporter genes, such as ZIP1, ZIP2, HMA2, HMA3 and CAX2, were elevated after PGPB inoculation. As a result, the PGPB successfully colonized the root, and promoted the sucrose shoot-to-root transport and Cd root-to-shoot transport in S. alfredii. Since non-photosynthetic root-associated bacteria usually obtain sugars from photosynthetic plants, our results highlight the importance of PGPB-induced changes in hyperaccumlator plants for both the host and the PGPB.
Topics: Biodegradation, Environmental; Cadmium; Photosynthesis; Plant Development; Plant Roots; Pseudomonas fluorescens; Sedum; Soil Pollutants; Sucrose
PubMed: 32559889
DOI: 10.1016/j.chemosphere.2020.127156 -
ELife Nov 2019Microscopic water films allow bacteria to survive the seemingly dry surface of plant leaves.
Microscopic water films allow bacteria to survive the seemingly dry surface of plant leaves.
Topics: Plant Leaves; Pseudomonas fluorescens
PubMed: 31674912
DOI: 10.7554/eLife.52123 -
Biomolecules Nov 2021Genome-wide analysis of plant-growth-promoting strain SS101 (SS101) followed by site-directed mutagenesis previously suggested that sulfur assimilation may play an...
Genome-wide analysis of plant-growth-promoting strain SS101 (SS101) followed by site-directed mutagenesis previously suggested that sulfur assimilation may play an important role in growth promotion and induced systemic resistance in . Here, we investigated the effects of sulfur metabolism in SS101 on growth, defense, and shoot metabolomes of and the Brassica crop, Broccoli. Root tips of seedlings of and two Broccoli cultivars were treated with SS101 or with a mutant disrupted in the adenylsulfate reductase , a key gene in cysteine and methionine biosynthesis. Phenotyping of plants treated with wild-type SS101 or its mutant revealed that sulfur assimilation in SS101 was associated with enhanced growth of but with a reduction in shoot biomass of two Broccoli cultivars. Untargeted metabolomics revealed that -mediated sulfur assimilation in SS101 had significant effects on shoot chemistry of , in particular on chain elongation of aliphatic glucosinolates (GLSs) and on indole metabolites, including camalexin and the growth hormone indole-3-acetic acid. In Broccoli, SS101 sulfur assimilation significantly upregulated the relative abundance of several shoot metabolites, in particular, indolic GLSs and phenylpropanoids. These metabolome changes in Broccoli plants coincided with SS101-mediated suppression of leaf infections by . Our study showed the metabolic interconnectedness of plants and their root-associated microbiota.
Topics: Arabidopsis; Brassicaceae; Glucosinolates; Pseudomonas fluorescens
PubMed: 34827700
DOI: 10.3390/biom11111704 -
Journal of Bacteriology Oct 2022Cells in microbial communities on surfaces live and divide in close proximity, which greatly enhances the potential for social interactions. Spatiogenetic structures are...
Cells in microbial communities on surfaces live and divide in close proximity, which greatly enhances the potential for social interactions. Spatiogenetic structures are manifested through competitive and cooperative interactions among the same and different genotypes within a shared space, and extracellular secretions appear to function dynamically at the forefront. A previous experimental evolution study utilizing Pseudomonas fluorescens Pf0-1 colonies demonstrated that diverse mutations in the gene were repeatedly and exclusively selected through the formation of a dominant spatial structure. RsmE's primary molecular function is translation repression, and its homologs regulate various social and virulence phenotypes. Pseudomonas spp. possess multiple paralogs of Rsm proteins, and RsmA, RsmE, and RsmI are the most prevalent. Here, we demonstrate that the production of a mucoid polymer and a biosurfactant are exclusively regulated through RsmE, contradicting the generalized notion of functional redundancy among the Rsm paralogs. Furthermore, we identified the biosurfactant as the cyclic lipopeptide gacamide A. Competition and microscopy analyses showed that the mucoid polymer is solely responsible for creating a space of low cellular density, which is shared exclusively by the same genotype. Gacamide A and other RsmE-regulated products appear to establish a physical boundary that prevents the encroachment of the competing genotype into the newly created space. Although cyclic lipopeptides and other biosurfactants are best known for their antimicrobial properties and reducing surface tension to promote the spreading of cells on various surfaces, they also appear to help define spatial structure formation within a dense community. In densely populated colonies of the bacterium Pseudomonas fluorescens Pf0-1, diverse mutations in the gene are naturally selected by solving the problem of overcrowding. Here, we show that RsmE-regulated secretions function together to create and protect space of low cell density. A biosurfactant generally promotes the spreading of bacterial cells on abiotic surfaces; however, it appears to function atypically within a crowded population by physically defining genotypic boundaries. Another significant finding is that these secretions are not regulated by RsmE's paralogs that share high sequence similarity. The experimental pipeline described in this study is highly tractable and should facilitate future studies to explore additional RsmE-regulated products and address why RsmE is functionally unique from its paralogs.
Topics: Pseudomonas fluorescens; Gene Expression Regulation, Bacterial; Bacterial Proteins; Pseudomonas; Peptides, Cyclic; Lipopeptides; Polymers
PubMed: 36165622
DOI: 10.1128/jb.00285-22 -
Pakistan Journal of Biological Sciences... Jan 2021<b>Background and Objective:</b> Nanoparticles with a little size to an enormous surface (1-100 nm) have expected clinical, mechanical and agricultural...
<b>Background and Objective:</b> Nanoparticles with a little size to an enormous surface (1-100 nm) have expected clinical, mechanical and agricultural applications. This study aimed to produce nano Zinc Oxide (ZnO) and nano Copper Oxide (CuO) particles by green synthesis. <b>Materials and Methods:</b> Two strains of <i>Pseudomonas fluorescens</i> i.e., PSI and PSII, both cell culture supernatants and cell pellets from the two strains were examined separately in CuSO<sub>4</sub> or ZnSO<sub>4</sub> solutions. The supernatants from both strains produced color changes in both solutions referring to the formation of nano CuO or ZnO particles. The solutions were examined for nano-particle characteristics using UV-spectroscopy, particle size and morphology were tested using a scanning electron microscope and transmission electron microscopy. <b>Results:</b> UV-Vis absorption spectrum of solutions at a wavelength range 200-800 nm exhibits a distinct absorption peak in the region of 238-331 and at 303-366 nm for CuO or ZnO NPs, respectively. Absorption bands and the characteristic Surface Plasmon Resonance (SPR) spectra confirm the existence of CuO and ZnO NPs. SEM analysis micrographs indicated that CuO NPs were formed as spherical particles, while the exact shape of ZnO NPs could be identified as oval aggregates. <b>Conclusion:</b> Changes of color occurred in both solutions of two strains referring to the formation of nano CuO or ZnO particles.
Topics: Chemistry Techniques, Synthetic; Copper; Egypt; Metal Nanoparticles; Nanoparticles; Pseudomonas fluorescens; Zinc
PubMed: 34486303
DOI: 10.3923/pjbs.2021.445.453 -
Canadian Journal of Microbiology Jun 2018The ability of Pseudomonas fluorescens isolates 1-112, 2-28, and 4-6, to control Mucor piriformis (Mucor rot) on Gala, McIntosh, Ambrosia, and Spartan apple cultivars in...
The ability of Pseudomonas fluorescens isolates 1-112, 2-28, and 4-6, to control Mucor piriformis (Mucor rot) on Gala, McIntosh, Ambrosia, and Spartan apple cultivars in commercial cold storage and their possible mechanisms of action were investigated. Isolates 1-112 and 2-28 provided significant levels of disease control on McIntosh and Spartan apples, while isolate 4-6 provided control of Mucor rot on Gala and Spartan apples, compared with control fruits after 15 weeks of storage at 0 °C. Mycelial growth of M. piriformis was markedly inhibited by cell-free supernatant and volatile organic compounds produced by P. fluorescens isolates, in vitro. In filter-sterilized apple juice, living cells of all 3 P. fluorescens isolates or their metabolites significantly inhibited spore germination by 99.8% and 61.6%, on average, respectively. Electron microscopy indicated that all 3 isolates of P. fluorescens colonized the hyphae of M. piriformis, but only isolate 1-112 was observed to colonize M. piriformis spores in vitro. In the wounds of apple, all 3 isolates formed a biofilm on the fungal hyphae and on the fruit tissue. Potential mechanisms of antagonism utilized by P. fluorescens against M. piriformis may include competition for nutrients and space, production of inhibitory metabolites and volatiles, and biofilm formation, leading to inhibition of spore germination and mycelial growth.
Topics: Food Storage; Malus; Mucor; Plant Diseases; Pseudomonas fluorescens
PubMed: 29505734
DOI: 10.1139/cjm-2017-0776 -
Journal of Food Protection Aug 2021Pseudomonas fluorescens is a specific spoilage microorganism of refrigerated marine fish, and is highly adapted to low temperature. Cold shock proteins (CSPs) play an...
ABSTRACT
Pseudomonas fluorescens is a specific spoilage microorganism of refrigerated marine fish, and is highly adapted to low temperature. Cold shock proteins (CSPs) play an important role in cold adaptation of bacteria. In this study, CSP genes were identified from the genome of P. fluorescens PF08 by search of the conserved domain of CSPs with HMMER software, and the CSP physicochemical properties, structures, and functions were analyzed through bioinformatics. Five typical CSPs were identified in the P. fluorescens PF08 genome (PfCSPs). All five PfCSPs are small hydrophilic acidic proteins with a molecular mass of ca. 7.4 kDa. They are located in the cytoplasm and are nonsecretory and nontransmembrane proteins. Multiple sequence alignment analysis indicated that the CSPs are highly conserved between species, especially in DNA-binding sites and RNA-binding motifs that can bind to single-stranded DNA and RNA. The five PfCSPs clustered with CspD from Escherichia coli and Salmonella Typhimurium, which suggests a close homology and high functional similarity among the five PfCSPs and CspD. The secondary and tertiary structures of the PfCSPs are in accordance with the characteristics of the CSP family, and ligand binding sites with higher likelihood were found in PfCSPs. The five PfCSPs were predicted to interact with some of the same proteins that are involved in virulence, stress responses (including to low temperature), cell growth, ribosome assembly, and RNA degradation. The results provide further elucidation of the function of CSPs in adaptation to low temperatures by P. fluorescens.
Topics: Amino Acid Sequence; Animals; Bacterial Proteins; Cold Shock Proteins and Peptides; Cold Temperature; Computer Simulation; Heat-Shock Proteins; Pseudomonas fluorescens
PubMed: 33852731
DOI: 10.4315/JFP-21-044 -
Journal of Applied Microbiology Jan 2020The aim of this paper was to determine whether the quality of formulated Pseudomonas fluorescens Pf153 can be influenced by changes in fermentation conditions. In this...
AIM
The aim of this paper was to determine whether the quality of formulated Pseudomonas fluorescens Pf153 can be influenced by changes in fermentation conditions. In this study, the influence of the fermentation temperature on the growth and its consequence on shelf life, viability and biocontrol efficacy of freeze-dried cells of P. fluorescens Pf153 was investigated.
METHODS AND RESULTS
Cells of P. fluorescens Pf153 were grown at 20 and 28°C in flasks and fermenter and harvested in the mid-log and the beginning of the stationary phase. The survival during storage of freeze-dried cells was tested at 25°C. Cells fermented at 20°C survived in storage better than those grown at 28°C, irrespective of the harvesting time. Compared to the untreated control, in in vitro tests Pf153 was in all production temperature/duration combinations significantly effective against all tested Botrytis cinerea strains. But no differences between temperature/duration combinations were found. In bioassay on detached Vicia faba leaves, it was found that young cells, when fermented at 28°C had a significant positive influence on the biocontrol efficacy.
CONCLUSIONS
These results demonstrate that fermentation parameters have an influence on the performance and quality of a formulated product.
SIGNIFICANCE AND IMPACT OF THE STUDY
Only limited numbers of biocontrol products based on antagonistic pseudomonads are on the market. This can be attributed to the lack of suitable formulated products with high numbers of viable cells and a good shelf life. Currently, only limited information on the influence of the fermentation on subsequent downstreaming process is available. Within this study, we focused on the influence of the two important parameters fermentation temperature and harvest time on survival, shelf life and biocontrol efficacy of P. fluorescens Pf153.
Topics: Biological Control Agents; Botrytis; Fermentation; Freeze Drying; Microbial Viability; Preservation, Biological; Pseudomonas fluorescens; Temperature; Vicia faba
PubMed: 31544331
DOI: 10.1111/jam.14458 -
International Journal of Systematic and... Nov 2020The taxonomic classification of species has been revised and updated several times. This study utilized average nucleotide identity (ANI) and digital DNA-DNA...
The taxonomic classification of species has been revised and updated several times. This study utilized average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) cutoff values of 95 and 70 %, respectively, to re-identify the species of strains deposited in GenBank as , and . Of the 264 deposited strains, 259 were correctly identified as , but the remaining five were not. All 28 deposited strains had been incorrectly identified as . Four of these strains were re-identified, including two as and one each as and , but the remaining 24 could not be re-identified. Similarly, all 35 deposited strains had been incorrectly identified as . Nineteen of these strains were re-identified, including 12 as , four as and one each as , and . These results strongly suggest that bacteria should be identified using ANI and dDDH analyses based on whole genome sequencing when species are initially deposited in GenBank/DDBJ/EMBL databases.
Topics: Bacterial Typing Techniques; DNA, Bacterial; Databases, Nucleic Acid; Nucleic Acid Hybridization; Pseudomonas aeruginosa; Pseudomonas fluorescens; Pseudomonas putida; Sequence Analysis, DNA; Whole Genome Sequencing
PubMed: 32936751
DOI: 10.1099/ijsem.0.004468