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Sample records for pseudomonas fluorescens alginate

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

    Science.gov (United States)

    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. New insights into Pseudomonas fluorescens alginate biosynthesis relevant for the establishment of an efficient production process for microbial alginates.

    Science.gov (United States)

    Maleki, Susan; Mærk, Mali; Hrudikova, Radka; Valla, Svein; Ertesvåg, Helga

    2017-07-25

    Alginate denotes a family of linear polysaccharides with a wide range of industrial and pharmaceutical applications. Presently, all commercially available alginates are manufactured from brown algae. However, bacterial alginates have advantages with regard to compositional homogeneity and reproducibility. In order to be able to design bacterial strains that are better suited for industrial alginate production, defining limiting factors for alginate biosynthesis is of vital importance. Our group has been studying alginate biosynthesis in Pseudomonas fluorescens using several complementary approaches. Alginate is synthesised and transported out of the cell by a multiprotein complex spanning from the inner to the outer membrane. We have developed an immunogold labelling procedure in which the porin AlgE, as a part of this alginate factory, could be detected by transmission electron microscopy. No time-dependent correlation between the number of such factories on the cell surface and alginate production level was found in alginate-producing strains. Alginate biosynthesis competes with the central carbon metabolism for the key metabolite fructose 6-phosphate. In P. fluorescens, glucose, fructose and glycerol, are metabolised via the Entner-Doudoroff and pentose phosphate pathways. Mutational analysis revealed that disruption of the glucose 6-phosphate dehydrogenase gene zwf-1 resulted in increased alginate production when glycerol was used as carbon source. Furthermore, alginate-producing P. fluorescens strains cultivated on glucose experience acid stress due to the simultaneous production of alginate and gluconate. The combined results from our studies strongly indicate that the availability of fructose 6-phosphate and energy requires more attention in further research aimed at the development of an optimised alginate production process. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Plant growth promotion by Pseudomonas fluorescens

    NARCIS (Netherlands)

    Cheng, X.

    2016-01-01

    Pseudomonas fluorescens is a Gram-negative rod shaped bacterium that has a versatile metabolism and is widely spread in soil and water. P. fluorescens strain SBW25 (Pf.SBW25) is a well-known model strain to study bacterial evolution, plant colonization and biocontrol of plant diseases. It produces

  4. Growth of Pseudomonas fluorescens on Cassava Starch ...

    African Journals Online (AJOL)

    This involved hydrolysis of starch extracted from freshly harvested cassava tubers using enzyme-enzyme method of hydrolysis, followed by aerobic fermentation of Pseudomonas fluorescens on a mixture of the hydrolysate and nutrient media in a fermentor in batch cultures. The reducing sugar hydrolysate served as the ...

  5. Water flow induced transport of Pseudomonas fluorescens cells through soil columns as affected by inoculant treatment

    NARCIS (Netherlands)

    Hekman, W.E.; Heijnen, C.E.; Trevors, J.T.; Elsas, van J.D.

    1994-01-01

    Water flow induced transport of Pseudomonas fluorescens cells through soil columns was measured as affected by the inoculant treatment. Bacterial cells were introduced into the topsoil of columns, either encapsulated in alginate beads of different types or mixed with bentonite clay in concentrations

  6. Pseudomonas fluorescens' view of the periodic table.

    Science.gov (United States)

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

    2008-01-01

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

  7. Detection of Pseudomonas fluorescens from broth, water and ...

    African Journals Online (AJOL)

    Loop mediated isothermal amplification is rapid, highly sensitive and specifically developed method for detection of bacterial infections. AprX gene for alkaline metalloprotease of Pseudomonas fluorescens was used to design four primers and loop mediated isothermal amplification (LAMP) conditions were standardized for ...

  8. Characterization and identification of Pseudomonas fluorescens ...

    African Journals Online (AJOL)

    user

    2011-01-24

    Jan 24, 2011 ... fluorescens can be used for bioremediation of textile effluents containing CV dye in sequential cycles. Key words: Crystal violet, ... extensively in textile dyeing and dye-stuff manufacturing industries, in human and ... nuclear magnetic resonance spectra of the test samples were run at Brukar AC 200 M Hz in ...

  9. The evolution of a pleiotropic fitness tradeoff in Pseudomonas fluorescens

    OpenAIRE

    MacLean, R. Craig; Bell, Graham; Rainey, Paul B.

    2004-01-01

    The evolution of ecological specialization is expected to carry a cost, due to either antagonistic pleiotropy or mutation accumulation. In general, it has been difficult to distinguish between these two possibilities. Here, we demonstrate that the experimental evolution of niche-specialist genotypes of the bacterium Pseudomonas fluorescens that colonize the air–broth interface of spatially structured microcosms is accompanied by pleiotropic fitness costs in terms of reduced carbon catabolism....

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

    Science.gov (United States)

    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...

  11. Pseudomonas fluorescens subsp. cellulosa: an alternative model for bacterial cellulase.

    Science.gov (United States)

    Hazlewood, G P; Laurie, J I; Ferreira, L M; Gilbert, H J

    1992-03-01

    Pseudomonas fluorescens subsp. cellulosa, a Gram-negative soil bacterium, can utilize crystalline cellulose or xylan as main sources of carbon and energy. Synthesis of endoglucanases and xylanases is induced by Avicel, filter paper, carboxymethylcellulose or xylan and is repressed by cellobiose, glucose or xylose. These enzymes are secreted into the culture supernatant fluid and do not form aggregates or associate with the cell surface. Cells of Ps. fluorescens subsp. cellulosa do not adhere to cellulose. In cultures containing Avicel or filter paper, a significant proportion of the secreted cellulase and xylanase activities becomes tightly bound to the insoluble cellulose. Western blotting has revealed that endoglucanase B, xylanase A and a cellodextrinase encoded by genes previously isolated from Ps. fluorescens subsp. cellulosa and expressed in Escherichia coli, are synthesized by the pseudomonad under a variety of conditions. These enzymes appear to be post-translationally modified, probably through glycosylation. Overall, it appears that the cellulase/hemicellulase system of Ps. fluorescens subsp. cellulosa differs from the model established for celluloytic anaerobes such as Clostridium thermocellum.

  12. MICROBIAL BIOFILMS PRODUCED BY PSEUDOMONAS FLUORESCENS ON SOLID SURFACES

    Directory of Open Access Journals (Sweden)

    Dagmar Kozelová

    2011-04-01

    Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 Normal 0 21 false false false MicrosoftInternetExplorer4 A biofilm is a complex aggregation of microorganisms growing on a solid substrate. Biofilms are characterized by structural heterogeneity, genetic diversity, complex community interactions, and an extracellular matrix of polymeric substances. The experimental part was focused on the adhesion of bacterial cells under static conditions and testing the effectiveness of disinfectants on created biofilm. In laboratory conditions we prepared and formed the bacterial biofilms Pseudomonas fluorescens in the four test surfaces of stainless steel, glass and plastic materials - PE (polyethylene and EPDM (ethylene propylene diene monomer. Over the next 72 hours and 72 hours were observed numbers of adhesion bacterial cells of P. fluorescens on solid surfaces of tested materials. The highest values adhesion cells reached P. fluorescens cells after 72 hours of cultivation on plastic surfaces, where  was increased in adhesion bacterial cells for EPDM in the values of 105 CFU/cm2 and for PE up to 106 CFU/cm2. The subsequent repeated 72-hour cultivation P. fluorescens was an increase (growth in the number of adhesion bacterial cells to all tested surfaces.doi:10.5219/18  

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

    Science.gov (United States)

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

    2013-06-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Adaptive synonymous mutations in an experimentally evolved Pseudomonas fluorescens population

    DEFF Research Database (Denmark)

    Bailey, Susan; Hinz, Aaron; Kassen, Rees

    2014-01-01

    Conventional wisdom holds that synonymous mutations, nucleotide changes that do not alter the encoded amino acid, have no detectable effect on phenotype or fitness. However, a growing body of evidence from both comparative and experimental studies suggests otherwise. Synonymous mutations have been...... in an experimentally evolved population of Pseudomonas fluorescens. We show experimentally that these mutations increase fitness by an amount comparable to non-synonymous mutations and that the fitness increases stem from increased gene expression. These results provide unequivocal evidence that synonymous mutations...... can drive adaptive evolution and suggest that this class of mutation may be underappreciated as a cause of adaptation and evolutionary dynamics....

  16. Uji Lapangan Formula Cair Pseudomonas fluorescens P60 terhadap Layu Fusarium pada Tanaman Tomat

    Directory of Open Access Journals (Sweden)

    Loekas Soesanto

    2011-12-01

    Full Text Available A research aimed at knowing 1 the effect of Pseudomonas fluorescens P60 in liquid formula on Fusarium wilt of tomato, 2 the effect of P. fluorescens P60 in the formula on tomato growth and yield, and 3 P. fluorescens P60 mechanisms on tomata was carried out at tomato field of Selomoyo Village, Kaliangkrik Subdistrict, Magelang Regency at altitude of 826 m above sea level. Randomized block design was used with seven treatments and four replicates. The treatments were control, with P. fluorescens P60 soaked for 15 min and without fungicide, pathogen without P. fluorescens P60 with fungicide (PBG1, pathogen with P. fluorescens P60 without fungicide, pathogen with pouring P. fluorescens P60 1, 3, and 5 times. Result indicated that application of formulated P. fluorescens P60 for 5 times decreased the disease intensity as high as 26.77%, and late population of the pathogen but increased P. fluorescens P60 as high as 4.54×1010 cfu ml-1. P. fluorescens P60 affected growth and yield of tomato. P. Fluorescens P60 induced tomato resistance by increasing qualitatively its phenolic compound content (saponin, tannin, glycoside.   Penelitian dengan tujuan untuk mengetahui: 1 pengaruh Pseudomonas fluorescens P60 dalam formula cair terhadap penyakit layu fusarium pada tanaman tomat, 2 pengaruh P. fluorescens P60 dalam formula cair terhadap pertumbuhan dan produksi tanaman tomat, dan 3 mekanisme P. fluorescens P60 pada tanaman tomat dilakukan di lahan Desa Selomoyo, Kecamatan Kaliangkrik, Kabupaten Magelang dengan ketinggian 826 m di atas permukaan laut. Penelitian menggunakan Rancangan Acak Kelompok (RAK, dengan 7 perlakuan dan jumlah ulangan 4 kali, dan setiap unit terdiri atas 8 tanaman. Perlakuan tersebut meliputi kontrol; dengan P. fluorescens P60 rendam 15 menit dan tanpa fungisida; dengan patogen; tanpa P. fluorescens P60; dengan fungisida (PBG1; patogen, tanpa P. fluorescens P60, tanpa fungisida; patogen, dengan penyiraman P. fluorescens P60 1 kali

  17. Effect of Pseudomonas fluorescens on Buried Steel Pipeline Corrosion.

    Science.gov (United States)

    Spark, Amy J; Law, David W; Ward, Liam P; Cole, Ivan S; Best, Adam S

    2017-08-01

    Buried steel infrastructure can be a source of iron ions for bacterial species, leading to microbiologically influenced corrosion (MIC). Localized corrosion of pipelines due to MIC is one of the key failure mechanisms of buried steel pipelines. In order to better understand the mechanisms of localized corrosion in soil, semisolid agar has been developed as an analogue for soil. Here, Pseudomonas fluorescens has been introduced to the system to understand how bacteria interact with steel. Through electrochemical testing including open circuit potentials, potentiodynamic scans, anodic potential holds, and electrochemical impedance spectroscopy it has been shown that P. fluorescens increases the rate of corrosion. Time for oxide and biofilms to develop was shown to not impact on the rate of corrosion but did alter the consistency of biofilm present and the viability of P. fluorescens following electrochemical testing. The proposed mechanism for increased corrosion rates of carbon steel involves the interactions of pyoverdine with the steel, preventing the formation of a cohesive passive layer, after initial cell attachment, followed by the formation of a metal concentration gradient on the steel surface.

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

    Directory of Open Access Journals (Sweden)

    Daniel Garrido-Sanz

    Full Text Available 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

  19. Isolation and characterization of a T7-like lytic phage for Pseudomonas fluorescens

    OpenAIRE

    Neubauer Peter; Sillankorva Sanna; Azeredo Joana

    2008-01-01

    Background: Despite the proven relevance of Pseudomonas fluorescens as a spoilage microorganism in milk, fresh meats and refrigerated food products and the recognized potential of bacteriophages as sanitation agents, so far no phages specific for P. fluorescens isolates from dairy industry have been closely characterized in view of their lytic efficiency. Here we describe the isolation and characterization of a lytic phage capable to infect a variety of P. fluorescens strains i...

  20. ANOMALOUS BLUE COLOURING OF MOZZARELLA CHEESE INTENTIONALLY CONTAMINATED WITH PIGMENT PRODUCING STRAINS OF PSEUDOMONAS FLUORESCENS

    Directory of Open Access Journals (Sweden)

    P. Sechi

    2011-04-01

    Full Text Available In summer 2010 a large outbreak of anomalous blue coloration of mozzarella cheese was recorded in Italy and some northern European countries. Official laboratory analysis and health authorities linked the outbreak to the contamination of processing water with strains of Pseudomonas fluorescens, although several expert raised the question of how to unequivocally link the blue coloring to the presence of the micro-organism. In an attempt to set-up a method to determine whether a given Pseudomonas spp. strain is responsible of the defect, an in vitro system for the evaluation of blue colouring of mozzarella cheese intentionally contaminated with strains of Pseudomonas fluorescens. was developed The system is aimed to ascertain whether P. fluorescens strains, isolated from mozzarella cheese with anomalous blue coloration, are able to reproduce the blue coloration under controlled experimental condition. 96 trials of experimental inoculation of mozzarella cheese in different preservation liquids, were conducted using various suspension of Pseudomonas spp. (P. fluorescens ATCC 13525, P. fluorescens CFBP 3150, one P. fluorescens field strain isolated from blue-colored mozzarella cheese and P. aeruginosa ATCC 10145 as positive control at different concentrations and incubated at different temperatures. Growth curve of all Pseudomonas spp. strains tested demonstrated that after three days of incubation the concentration was generally higher than 106 CFU/g of mozzarella cheese incubated in Tryptic Soy Broth (TSB, and higher than 105 CFU/g of mozzarella cheese incubated in preservation liquid. All mozzarella cheeses inoculated with the field strain of Pseudomonas fluorescens showed the characteristic anomalous blue coloration, which is often associated with Pseudomonas fluorescens contamination of water used during mozzarella cheesemaking. With the proposed system, which enabled a considerable amount of samples to be analysed under controlled experimental

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

    Science.gov (United States)

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

    2010-03-01

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

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

    Science.gov (United States)

    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-...

  3. Bacteriocins and the assembly of natural Pseudomonas fluorescens populations.

    Science.gov (United States)

    Bruce, J B; West, S A; Griffin, A S

    2017-02-01

    When competing for space and resources, bacteria produce toxins known as bacteriocins to gain an advantage over competitors. Recent studies in the laboratory have confirmed theoretical predictions that bacteriocin production can determine coexistence, by eradicating sensitive competitors or driving the emergence of resistant genotypes. However, there is currently limited evidence that bacteriocin-mediated competition influences the coexistence and distribution of genotypes in natural environments, and what factors drive interactions towards inhibition remain unclear. Using natural soil populations of Pseudomonas fluorescens, we assessed the ability of the isolates to inhibit one another with respect to spatial proximity in the field, genetic similarity and niche overlap. The majority of isolates were found to produce bacteriocins; however, widespread resistance between coexisting isolates meant relatively few interactions resulted in inhibition. When inhibition did occur, it occurred more frequently between ecologically similar isolates. However, in contrast with results from other natural populations, we found no relationship between the frequency of inhibition and the genetic similarity of competitors. Our results suggest that bacteriocin production plays an important role in mediating competition over resources in natural settings and, by selecting for isolates resistant to local bacteriocin production, can influence the assembly of natural populations of P. fluorescens. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  4. Boolean models of biosurfactants production in Pseudomonas fluorescens.

    Directory of Open Access Journals (Sweden)

    Adrien Richard

    Full Text Available 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 (plcC and not restored by plcC 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.

  5. Bioreporter pseudomonas fluorescens HK44 immobilized in a silica matrix

    Directory of Open Access Journals (Sweden)

    Trogl J.

    2003-01-01

    Full Text Available The bioluminescent bioreporter Pseudomonas fluorescens HK44, the whole cell bacterial biosensor that responds to naphthalene and its metabolites via the production of visible light, was immobilized into a silica matrix by the sol-gel technique. The bioluminescence intensities were measured in the maximum of the bioluminescence band at X = 500 nm. The immobilized cells (>105 cells per g silica matrix produced light after induction by salicylate (cone. > 10 g/l, naphthalene and aminobenzoic acid. The bioluminescence intensities induced by 2,3-dihydroxynaphthalene 3-hydroxybenzoic acid and 4-hydroxybenzoic acid were comparable to a negative control. The cells in the silica layers on glass slides produced light in response to the presence of an inductor at least 8 months after immobilization, and >50 induction cycles. The results showed that these test slides could be used as assays for the multiple determination of water pollution.

  6. Anaerobic production of alginate by Pseudomonas aeruginosa: alginate restricts diffusion of oxygen.

    OpenAIRE

    Hassett, D J

    1996-01-01

    Pseudomonas aeruginosa produced alginate and elevated algD (encoding GDPmannose 6-dehydrogenase) transcription under strict anaerobic conditions, especially when using nitrate as a terminal electron acceptor. Purified alginate added to bacterial suspensions caused a decrease in growth, suggesting that alginate contributes to oxygen limitation for the organism and likely for patients afflicted with the inherited autosomal disease cystic fibrosis.

  7. The cellodextrinase from Pseudomonas fluorescens subsp. cellulosa consists of multiple functional domains

    National Research Council Canada - National Science Library

    Ferreira, L M; Hazlewood, G P; Barker, P J; Gilbert, H J

    1991-01-01

    A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA was constructed in pUC18 and Escherichia coli recombinants expressing 4-methylumbelliferyl beta-D-cellobioside-hydrolysing activity (MUCase) were isolated...

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

    NARCIS (Netherlands)

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

    2015-01-01

    Abstract 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

  9. Alginate overproduction affects Pseudomonas aeruginosa biofilm structure and function

    DEFF Research Database (Denmark)

    Hentzer, Morten; Teitzel, G.M.; Balzer, G.J.

    2001-01-01

    During the course of chronic cystic fibrosis (CF) infections, Pseudomonas aeruginosa undergoes a conversion to a mucoid phenotype, which is characterized by overproduction of the exopolysaccharide alginate. Chronic P. aeruginosa infections involve surface-attached, highly antibiotic-resistant com...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    1977-01-01

    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

  12. Global control in Pseudomonas fluorescens mediating antibiotic synthesis and suppression of black root rot of tobacco.

    OpenAIRE

    Laville, J; Voisard, C; C. Keel; Maurhofer, M.; Défago, G; Haas, D

    1992-01-01

    Pseudomonas fluorescens CHA0 colonizes plant roots, produces several secondary metabolites in stationary growth phase, and suppresses a number of plant diseases, including Thielaviopsis basicola-induced black root rot of tobacco. We discovered that mutations in a P. fluorescens gene named gacA (for global antibiotic and cyanide control) pleiotropically block the production of the secondary metabolites 2,4-diacetylphloroglucinol (Phl), HCN, and pyoluteorin. The gacA mutants of strain CHA0 have...

  13. Bioremediation of crude oil contaminated soil by bioaugmentation of Pseudomonas fluorescens NS1.

    Science.gov (United States)

    Barathi, S; Vasudevan, N

    2003-09-01

    A feasibility study was conducted to evaluate the efficiency of Pseudomonas fluorescens NS1 bioaugmented to stimulate in situ bioremediation of crude oil-contaminated soil with different amendments in treatment units. Pure culture of P. fluorescens NS1 was isolated from a petroleum-contaminated soil. The rate of degradation of petroleum hydrocarbons by the indigenous soil microflora and in the presence of P. fluorescens NS1 was assessed with the addition of nutrients and bulking agents for a period of about 35 days. The study showed that addition of wheat bran as bulking agent rapidly enhanced bioremediation of crude oil-contaminated soil compared to amendments in other treatment units.

  14. The effect of phylogenetically different bacteria on the fitness of Pseudomonas fluorescens in sand microcosms.

    Directory of Open Access Journals (Sweden)

    Olaf Tyc

    Full Text Available In most environments many microorganisms live in close vicinity and can interact in various ways. Recent studies suggest that bacteria are able to sense and respond to the presence of neighbouring bacteria in the environment and alter their response accordingly. This ability might be an important strategy in complex habitats such as soils, with great implications for shaping the microbial community structure. Here, we used a sand microcosm approach to investigate how Pseudomonas fluorescens Pf0-1 responds to the presence of monocultures or mixtures of two phylogenetically different bacteria, a Gram-negative (Pedobacter sp. V48 and a Gram-positive (Bacillus sp. V102 under two nutrient conditions. Results revealed that under both nutrient poor and nutrient rich conditions confrontation with the Gram-positive Bacillus sp. V102 strain led to significant lower cell numbers of Pseudomonas fluorescens Pf0-1, whereas confrontation with the Gram-negative Pedobacter sp. V48 strain did not affect the growth of Pseudomonas fluorescens Pf0-1. However, when Pseudomonas fluorescens Pf0-1 was confronted with the mixture of both strains, no significant effect on the growth of Pseudomonas fluorescens Pf0-1 was observed. Quantitative real-time PCR data showed up-regulation of genes involved in the production of a broad-spectrum antibiotic in Pseudomonas fluorescens Pf0-1 when confronted with Pedobacter sp. V48, but not in the presence of Bacillus sp. V102. The results provide evidence that the performance of bacteria in soil depends strongly on the identity of neighbouring bacteria and that inter-specific interactions are an important factor in determining microbial community structure.

  15. Transposon Tn5 mutagenesis of pseudomonas fluorescens to isolate mutants deficient in antibacterial activity.

    Science.gov (United States)

    Rajendran, N; Jahn, D; Jayaraman, K; Marahiel, M A

    1994-01-15

    Pseudomonas fluorescens was subjected to insertion mutagenesis studies using the transposon Tn5-GM to generate mutants deficient in antibacterial activity minus mutants. The transposon located on the temperature-sensitive plasmid pCHR84 was conjugally transferred into the non-pathogenic pseudomonad using the triparental mating procedure. Random integration of Tn5-GM into the chromosome of P. fluorescens was achieved by heat treatment of the transformed cells at 42 degrees C. Approximately 2% of transconjugants revealed an auxotrophic phenotype indicating efficient integration of the employed transposon into the chromosome of P. fluorescens. One transposon insertion mutant was obtained showing an antibacterial activity minus phenotype. This mutant (MM-7) was found to be defective in the production of an unidentified antibacterial compound against B. subtilis. These results introduce Tn5 transposon mutagenesis as a new useful tool for the molecular analysis of P. fluorescens.

  16. Chromium phytoextraction from tannery effluent-contaminated soil by Crotalaria juncea infested with Pseudomonas fluorescens.

    Science.gov (United States)

    Agarwal, Anamika; Singh, Harminder Pal; Rai, J P N

    2014-01-01

    The aim of present study was to remediate chromium (Cr)-contaminated soil by Crotalaria juncea in the presence of Pseudomonas fluorescens. Inoculation of P. fluorescens in pot soil grown with C. juncea significantly increased (~2-fold) the water-soluble (Ws) and exchangeable (Ex) Cr contents in contaminated soil under greenhouse condition. It also enhanced the chlorophyll content by 92 % and plant biomass by 99 % as compared to the uninoculated C. juncea plant. The analysis showed that root and shoot uptake of Cr in C. juncea inoculated by P. fluorescens was 3.08- and 2.82-fold, respectively. This research showed that the association of C. juncea and P. fluorescens could be a promising technology for increasing the soil Cr bioavailability and plant growth for successful phytoextraction of Cr from the contaminated soil.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  18. Effects of ambroxol on alginate of mature Pseudomonas aeruginosa biofilms.

    Science.gov (United States)

    Li, Fang; Yu, Jialin; Yang, Hua; Wan, Zhenyan; Bai, Dan

    2008-07-01

    Biofilm-forming bacteria Pseudomonas aeruginosa is a common pathogen in mechanically ventilated newborns, which can cause life-threatening infections. Alginate of mucoid Pseudomonas aeruginosa biofilms is considered an important virulence factor which contributes to the resistance to antibiotics. Traditionally, ambroxol is widely used in newborns with lung problems as a mucolytic agent and antioxidant agent as well. And there are few studies that demonstrated the anti-biofilm activity of ambroxol. In this study, we found that ambroxol can affect the structure of mucoid Pseudomonas aeruginosa biofilms. Further, we found that ambroxol reduces the production of alginate, the expression of the important genes and the activity of key enzyme guanosine diphospho-D-mannose dehydrogenase (GDP-mannose dehydrogenase; GMD) which were involved in alginate biosynthesis.

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

    Energy Technology Data Exchange (ETDEWEB)

    Deveau, Aurelie [French National Insitute for Agricultural Research (INRA); Grob, Harald [University of Bonn, Germany; Morin, Emmanuelle [INRA, Nancy, France; Karpinets, Tatiana V [ORNL; Utturkar, Sagar M [ORNL; Mehnaz, Samina [University of the Punjab, Pakistan; Kurz, Sven [University of Bonn, Germany; Martin, Francis [INRA, Nancy, France; Frey-Klett, Pascale [INRA, Nancy, France; Labbe, Jessy L [ORNL

    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.

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

    Science.gov (United States)

    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...

  1. Improved Performance of Pseudomonas fluorescens lipase by covalent immobilization onto Amberzyme

    NARCIS (Netherlands)

    Aslan, Yakup; Handayani, Nurrahmi; Stavila, Erythrina; Loos, Katja

    2013-01-01

    Objective: In this study, the conditions of covalent immobilization of Pseudomonas fluorescens lipase onto an oxirane-activated support (Amberzyme) were optimized to obtain a high activity yield. Furthermore, the operational and storage stabilities of immobilized lipase were tested. Methods: Optimum

  2. Evolutionary history of the phl gene cluster in the plant-associated bacterium Pseudomonas fluorescens

    NARCIS (Netherlands)

    Moynihan, J.A.; Morrissey, J.P.; Coppoolse, E.; Stiekema, W.J.; O'Gara, F.; Boyd, E.F.

    2009-01-01

    Pseudomonas fluorescens is of agricultural and economic importance as a biological control agent largely because of its plant-association and production of secondary metabolites, in particular 2, 4-diacetylphloroglucinol (2, 4-DAPG). This polyketide, which is encoded by the eight gene phl cluster,

  3. Iron-regulated metabolites of plant growth-promoting Pseudomonas fluorescens WCS374 : Their role in induced systemic resistance

    NARCIS (Netherlands)

    Djavaheri, M.

    2007-01-01

    The plant growth-promoting rhizobacterium Pseudomonas fluorescens WCS374r effectively suppresses fusarium wilt in radish by induced systemic resistance (ISR). In radish, WCS374r-mediated ISR depends partly on iron-regulated metabolites. Under iron-limiting conditions, P. fluorescens WCS374r produces

  4. The structure-function relationship of WspR, a Pseudomonas fluorescens response regulator with a GGDEF output domain

    National Research Council Canada - National Science Library

    Malone, J. G; Williams, R; Christen, M; Jenal, U; Spiers, A. J; Rainey, P. B

    2007-01-01

    ...{at}auckland.ac.nz The GGDEF response regulator WspR couples the chemosensory Wsp pathway to the overproduction of acetylated cellulose and cell attachment in the Pseudomonas fluorescens SBW25 wrinkly spreader (WS) genotype...

  5. HETEROLOGOUS EXPRESSION OF A CHITINASE GENE FROM AEROMONAS CAVIAEIN PSEUDOMONAS FLUORESCENS

    Directory of Open Access Journals (Sweden)

    ANTONIUS SUWANTO

    2003-01-01

    Full Text Available A transcriptional fusion for an Aeromonas caviae chitinase gene was constructed under the control of a constitutive promoter of the kanaraycin resistance gene (PKmR. The construct was inserted into a medium copy number broad host range plasmid vector to yield recombinant plasmid pAM340, which harbored transcriptional fusion PKmR- chi. Another transcriptional fusion, Ptac-chi, in a recombinant plasmid pAM630, was conducted as comparison. Triparental mating of E. coli carrying the recombinant plasmids with Pseudomotws fluorescens 5100, a phyllosphere bacterium, was performed. Pseudomonas fluorescens 5100 exconjugants were examined for constitutive expression of chitinase employing a spectrophotometric assay; they showed stronger chitin degradation activity than Escherichia coli transformants. Using a fungal antagonism plate assay, this chitinolytic P. fluorescens, however, could not inhibit selected phytopathogenic fungi.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  8. Pseudomine, an isoxazolidone with siderophoric activity from Pseudomonas fluorescens AH2 isolated from Lake Victorian Nile Perch

    DEFF Research Database (Denmark)

    Anthoni, U.; Christophersen, C.; Nielsen, P.H.

    1995-01-01

    A siderophore, pseudomonine, and sodium salicylate were isolated from the culture broth of iron-deficient cultures of Pseudomonas fluorescens AH2 isolated from the surface of spoiled Nile Perch from Lake Victoria......A siderophore, pseudomonine, and sodium salicylate were isolated from the culture broth of iron-deficient cultures of Pseudomonas fluorescens AH2 isolated from the surface of spoiled Nile Perch from Lake Victoria...

  9. Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens.

    Science.gov (United States)

    Hol, W H Gera; Bezemer, T Martijn; Biere, Arjen

    2013-01-01

    Plant growth-promoting rhizobacteria (PGPR) are increasingly appreciated for their contributions to primary productivity through promotion of growth and triggering of induced systemic resistance in plants. Here we focus on the beneficial effects of one particular species of PGPR (Pseudomonas fluorescens) on plants through induced plant defense. This model organism has provided much understanding of the underlying molecular mechanisms of PGPR-induced plant defense. However, this knowledge can only be appreciated at full value once we know to what extent these mechanisms also occur under more realistic, species-diverse conditions as are occurring in the plant rhizosphere. To provide the necessary ecological context, we review the literature to compare the effect of P. fluorescens on induced plant defense when it is present as a single species or in combination with other soil dwelling species. Specifically, we discuss combinations with other plant mutualists (bacterial or fungal), plant pathogens (bacterial or fungal), bacterivores (nematode or protozoa), and decomposers. Synergistic interactions between P. fluorescens and other plant mutualists are much more commonly reported than antagonistic interactions. Recent developments have enabled screenings of P. fluorescens genomes for defense traits and this could help with selection of strains with likely positive interactions on biocontrol. However, studies that examine the effects of multiple herbivores, pathogens, or herbivores and pathogens together on the effectiveness of PGPR to induce plant defenses are underrepresented and we are not aware of any study that has examined interactions between P. fluorescens and bacterivores or decomposers. As co-occurring soil organisms can enhance but also reduce the effectiveness of PGPR, a better understanding of the biotic factors modulating P. fluorescens-plant interactions will improve the effectiveness of introducing P. fluorescens to enhance plant production and defense.

  10. Inhibition of quorum sensing-controlled virulence factors and biofilm formation in Pseudomonas fluorescens by cinnamaldehyde.

    Science.gov (United States)

    Li, Tingting; Wang, Dangfeng; Liu, Nan; Ma, Yan; Ding, Ting; Mei, Yongchao; Li, Jianrong

    2018-02-01

    Pseudomonas fluorescens, an important food spoiling bacteria, uses quorum sensing to control biofilm formation and motility. To date, only a few compounds targeting the LuxR-based quorum sensing system of P. fluorescens have been identified. In the present study, the quorum sensing inhibitory effect of cinnamaldehyde at sublethal concentrations was investigated in terms of inhibition of the extracellular protease, biofilm formation, and swimming and swarming motility. The total volatile basic nitrogen value was also measured to evaluate the effect of cinnamaldehyde on quality preservation of turbot fillets stored at 4 ± 1 °C for 15 days. The results showed that cinnamaldehyde significantly inhibited quorum sensing-dependent factors in P. fluorescens and extended the storage life of turbot. Unexpectedly, cinnamaldehyde did not interfere with production of AHLs (N-acylhomoserine lactones) by P. fluorescens, as shown by measurement of AHL production using GC-MS. Molecular docking analysis revealed that cinnamaldehyde can interact with the LuxR-type protein of P. fluorescens, which could constitute the molecular basis of the quorum sensing inhibition observed. These findings strongly suggest that cinnamaldehyde is a quorum sensing inhibitor with great potential for the preservation of aquatic products to guarantee food safety. Copyright © 2018. Published by Elsevier B.V.

  11. Aplikasi Formula Cair Pseudomonas fluorescens P60 untuk Menekan Penyakit Virus Cabai Merah

    Directory of Open Access Journals (Sweden)

    Loekas Soesanto

    2014-08-01

    Full Text Available Viral diseases of chilli pepper are difficult to control, therefore the use of Pseudomonas fluorescens P60 should be evaluated. The aims of this research were to determine the influence of liquid formula of P. fluorescens P60 on virod disease and on growth and yield of chili pepper. Randomized block design (RBD experiment was composed of 7 treatments and 4 replicates, i.e., control, insecticide applicaton, P. fluorescens P60 application by seedling drenching and spraying for 1, 2, 3, 5, and 7 times. The result showed that 5 times application of P. fluorescens P60 by drenching and spraying was able to suppress viral disease and reduce disease intensity by to 73.37%, increasing density level of P. fluorescens P60 to 9.50 x 1011 and increase phenolic compounds (saponin, tannin and glycoside. The same treatment could increase plant height 23.7%, root lenght 6.44%, plant dry weight 66.68%, root dry weight 23.59%, and yield weight 53.16%.

  12. SANITATION PROCESS OPTIMALIZATION IN RELATION TO THE MICROBIAL BIOFILM OF PSEUDOMONAS FLUORESCENS

    Directory of Open Access Journals (Sweden)

    Vladimír Vietoris

    2012-02-01

    Full Text Available Biofilms have been of considerable interest in the context of food hygiene. Extracellular polymeric substances play an important role in the attachment and colonization of microorganisms to food-contact surfaces. If the microorganisms from food-contact surfaces are not completely removed, they may lead to biofilm formation and also increase the biotransfer potential. The experimental part was focused on the adhesion of bacterial cells under static conditions and testing the effectiveness of disinfectants on created biofilm. In laboratory conditions we prepared and formed the bacterial biofilms Pseudomonas fluorescens in the test surfaces of stainless steel. Over the 72 hours and the next 72 hours were observed numbers of adhesion bacterial cells of Pseudomonas fluorescens on solid surfaces of tested materials.

  13. Biosynthesis and regulation of cyclic lipopeptides in Pseudomonas fluorescens

    NARCIS (Netherlands)

    Bruijn, de I.

    2009-01-01

    Cyclic lipopeptides (CLPs) are surfactant and antibiotic metabolites produced by a variety of bacterial genera. For the genus Pseudomonas, many structurally different CLPs have been identified. CLPs play an important role in surface motility of Pseudomonas strains, but also in virulence and

  14. The cellodextrinase from Pseudomonas fluorescens subsp. cellulosa consists of multiple functional domains.

    OpenAIRE

    Ferreira, L M; Hazlewood, G P; Barker, P J; Gilbert, H J

    1991-01-01

    A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA was constructed in pUC18 and Escherichia coli recombinants expressing 4-methylumbelliferyl beta-D-cellobioside-hydrolysing activity (MUCase) were isolated. Enzyme produced by MUCase-positive clones did not hydrolyse either cellobiose or cellotriose but converted cellotetraose into cellobiose and cleaved cellopentaose and cellohexaose, producing a mixture of cellobiose and cellotriose. There was no activity against CM-cellulose,...

  15. Cyanase-mediated utilization of cyanate in Pseudomonas fluorescens NCIB 11764.

    OpenAIRE

    Kunz, D. A.; Nagappan, O

    1989-01-01

    Pseudomonas fluorescens NCIB 11764 was capable of utilizing cyanate (OCN-) as a sole nitrogen source for growth. Crude cell extracts from cells grown on cyanate, but not on ammonium sulfate, were induced for an enzyme catalyzing cyanate conversion to ammonia. Enzymatic activity was shown to be bicarbonate dependent and specific for cyanate as a substrate, suggesting that cyanate utilization in this organism is facilitated by an enzyme resembling cyanase (cyanate amidohydrolase; EC 3.5.5.3), a...

  16. Adhesion of Pseudomonas fluorescens biofilms to glass, stainless steel and cellulose

    OpenAIRE

    Wan Dagang, W.R.Z.; Bowen, J.; O'Keeffe, J.; Robbins, P.T.; Zhang, Z.

    2016-01-01

    Objectives: \\ud 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.\\ud \\ud Results: \\ud 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 prob...

  17. A genetically engineered Pseudomonas fluorescens strain possesses the dual activity against phytopathogenic fungi and insects.

    Science.gov (United States)

    Lu, Wenwei; Zhang, Weiqiong; Bai, Yan; Fu, Yingying; Chen, Jun; Geng, Xiaolu; Wang, Yujing; Xiao, Ming

    2010-02-01

    A Pseudomonas fluorescens strain was isolated and showed antagonistic activity against phytopathogenic fungi and found to possess a gene responsible for production of antibiotic 2, 4-diacetylphloroglucinol. For the extension of biocontrol range, a gene for an Androctonus australis Hector insect toxin 1 (AaHIT1), one of the most toxic known insect-selective peptides, was designed and synthesized according to the preferred codon usage of Pseudomonas fluorescens, cloned and transformed into the strain by pSUP106 vector, a broad-host-range plasmid. Bioassays indicated that the engineered strain was able to produce AaHIT1 with insecticidal activity, in the same time retained the activity against plant pathogen. The experiments for nonplanted soil and rhizosphere colonization showed that, similar to the population of the wild-type strain, that of the engineered strain remained relatively constant in the first 10 d, and the subsequent 50 d, suggesting that AaHIT expression in the bacterial cell does not substantially impair its long-term colonization. It is first reported that a Pseudomonas fluorescens strain expressing an active scorpion neurotoxin has dual activity against phytopathogenic fungi and insects, attractive for agronomic applications.

  18. Initial characterization of a bolA homologue from Pseudomonas fluorescens indicates different roles for BolA-like proteins in em>P. fluorescens and Escherichia coli

    DEFF Research Database (Denmark)

    Koch, Birgit; Nybroe, Ole

    2006-01-01

    The RpoS-regulated bolA gene in Escherichia coli is important for the decrease in cell size during stationary phase or sudden carbon starvation. A Pseudomonas fluorescens strain mutated in a gene with homology to bolA reduced its cell size upon carbon starvation, and RpoS had little effect on bol...

  19. Isolation and characterization of a T7-like lytic phage for Pseudomonas fluorescens

    Directory of Open Access Journals (Sweden)

    Neubauer Peter

    2008-10-01

    Full Text Available Abstract Background Despite the proven relevance of Pseudomonas fluorescens as a spoilage microorganism in milk, fresh meats and refrigerated food products and the recognized potential of bacteriophages as sanitation agents, so far no phages specific for P. fluorescens isolates from dairy industry have been closely characterized in view of their lytic efficiency. Here we describe the isolation and characterization of a lytic phage capable to infect a variety of P. fluorescens strains isolated from Portuguese and United States dairy industries. Results Several phages were isolated which showed a different host spectrum and efficiency of lysis. One of the phages, phage ϕIBB-PF7A, was studied in detail due to its efficient lysis of a wide spectrum of P. fluorescens strains and ribotypes. Phage ϕIBB-PF7A with a head diameter of about 63 nm and a tail size of about 13 × 8 nm belongs morphologically to the Podoviridae family and resembles a typical T7-like phage, as analyzed by transmission electron microscopy (TEM. The phage growth cycle with a detected latent period of 15 min, an eclipse period of 10 min, a burst size of 153 plaque forming units per infected cell, its genome size of approximately 42 kbp, and the size and N-terminal sequence of one of the protein bands, which gave similarity to the major capsid protein 10A, are consistent with this classification. Conclusion The isolated T7-like phage, phage ϕIBB-PF7A, is fast and efficient in lysing different P. fluorescens strains and may be a good candidate to be used as a sanitation agent to control the prevalence of spoilage causing P. fluorescens strains in dairy and food related environments.

  20. Genome-wide analysis of bacterial determinants of plant growth promotion and induced systemic resistance by Pseudomonas fluorescens

    NARCIS (Netherlands)

    Cheng, Xu; Etalo, Desalegn W.; van de Mortel, Judith E.; Dekkers, Ester; Nguyen, Linh; Medema, Marnix H; Raaijmakers, Jos M.

    2017-01-01

    Pseudomonas fluorescens strain SS101 (Pf.SS101) promotes growth of Arabidopsis thaliana, enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). Here, targeted and untargeted approaches were adopted to

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

    Energy Technology Data Exchange (ETDEWEB)

    Vasileva-Tonkova, E.; Galabova, D. [Bulgarian Academy of Sciences, Dept. of Microbial Biochemistry, Sofia (Bulgaria); Stoimenova, E.; Lalchev, Z. [Dept. of Biochemistry, Sofia Univ. ' ' St. Kliment Ohridski' ' , Sofia (Bulgaria)

    2006-07-15

    The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g 1{sup -1}) when grown on hexadecane as a sole carbon source. Biosurfactants decreased the surface tension of the air/water interface by 35 mN m{sup -1} and possessed a low critical micelle concentration value of 20 mg 1{sup -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. (orig.)

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2015-09-01

    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. 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. 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. 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. 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 sporulate in soil.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  5. Supervivencia de Pseudomonas fluorescens en suelos con diferente contenido de materia orgánica Pseudomonas fluorescens survival in soils with different contents of organic matter

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    E.B.R. Perotti

    2005-06-01

    Full Text Available Pseudomonas fluorescens es una bacteria PGPR (plant growth promoting rhizobacteria, heterótrofa, capaz de combatir fitopatógenos edáficos. Su supervivencia podría estar favorecida por el elevado contenido de materia orgánica del suelo (MOS. Para probarlo, se inocularon, en condiciones de laboratorio, tres cepas de P. fluorescens: UP61, C7R12, y P190 (nativa de Balcarce, Buenos Aires en suelos rizosféricos de tomate representativos de diferentes zonas de Argentina: suelo Argiudol (Balcarce, y Zavalla, Santa Fe y suelo Torrifluvens (Cipolletti, Río Negro (MOS %: 7,2; 4,3 y 2,6 respectivamente. Los resultados indicaron que la supervivencia de P. fluorescens en los suelos Argiudoles fue similar; aunque las pendientes de las curvas de supervivencia en el suelo de Zavalla fueron menores que las observadas en el suelo de Balcarce. La producción de CO2 fue superior en el suelo de Balcarce que en el suelo de Zavalla (4,3 y 2,8 mmol.g-1suelo, esta diferencia podría ser explicada por la existencia de una mayor presión competitiva por parte de la microflora nativa. La supervivencia en el suelo Torrifluvens resultó mínima, lo que sería atribuible a su elevada conductividad eléctrica más que al menor contenido de MOS. La cepa UP61 presentó en todos los casos la mejor supervivencia.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

  6. Cyanase-mediated utilization of cyanate in Pseudomonas fluorescens NCIB 11764.

    Science.gov (United States)

    Kunz, D A; Nagappan, O

    1989-01-01

    Pseudomonas fluorescens NCIB 11764 was capable of utilizing cyanate (OCN-) as a sole nitrogen source for growth. Crude cell extracts from cells grown on cyanate, but not on ammonium sulfate, were induced for an enzyme catalyzing cyanate conversion to ammonia. Enzymatic activity was shown to be bicarbonate dependent and specific for cyanate as a substrate, suggesting that cyanate utilization in this organism is facilitated by an enzyme resembling cyanase (cyanate amidohydrolase; EC 3.5.5.3), as described previously in Escherichia coli and Flavobacterium sp.

  7. The Influence of Pseudomonas fluorescens on Corrosion Products of Archaeological Tin-Bronze Analogues

    Science.gov (United States)

    Ghiara, G.; Grande, C.; Ferrando, S.; Piccardo, P.

    2018-01-01

    In this study, tin-bronze analogues of archaeological objects were investigated in the presence of an aerobic Pseudomonas fluorescens strain in a solution, containing chlorides, sulfates, carbonates and nitrates according to a previous archaeological characterization. Classical fixation protocols were employed in order to verify the attachment capacity of such bacteria. In addition, classical metallurgical analytical techniques were used to detect the effect of bacteria on the formation of uncommon corrosion products in such an environment. Results indicate quite a good attachment capacity of the bacteria to the metallic surface and the formation of the uncommon corrosion products sulfates and sulfides is probably connected to the bacterial metabolism.

  8. Exposure-related effects of Pseudomonas fluorescens (Pf-CL145A) on juvenile unionid mussels

    Science.gov (United States)

    Weber, Kerry L.; Luoma, James A.; Mayer, Denise A.; Aloisi, Douglas B.; Eckert, Nathan L.

    2015-01-01

    The exposure-related effects of a commercially prepared spray-dried powder (SDP) or freeze-dried powder (FDP) formulation of Pseudomonas fluorescens (strain CL145A) on the survival of seven species of newly metamorphosed (randomly distributed to test chambers and each species independently exposed for 24 hours to a static dose of either SDP (four species: Lampsilis cardium, Lampsilis siliquoidea, Lampsilis higginsii, andLigumia recta) or FDP (three species: Obovaria olivaria, Actinonaias ligamentina, andMegalonaias nervosa).

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

    Science.gov (United States)

    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.

  10. Growth of Amanita caesarea in the presence of Pseudomonas fluorescens and Bacillus cereus.

    Science.gov (United States)

    Cano, J M; Berrocal-Lobo, M; Domínguez-Núñez, J A

    2017-09-01

    The ectomycorrhizal (ECM) fungus Amanita caesarea CECT 20127 was tested in vitro with two potentially mycorrhizal-promoting bacterial strains, Pseudomonas fluorescens CECT 844 and Bacillus cereus CECT 148. Although P. fluorescens showed spatial and temporal compatibility with A. caesarea, it did not affect growth of the fungus. Conversely, B. cereus exhibited no such compatibility and also inhibited fungal growth. The expression pattern of the A. caesarea gene AcMST-1 was analysed using real-time quantitative polymerase chain reaction (qPCR) at three time points. This gene displays a high degree of homology with two genes, possible orthologues to AcMST-1, previously described in Amanita muscaria (AmMST-1) and Laccaria bicolor (LbMST-1) and encoding monosaccharide transporter proteins. The transcription levels of AcMST1 increased shortly after initial contact between A. caesarea and B. cereus, but expression of the gene was inhibited in the presence of P. fluorescens. Our results show that A. caesarea may possess orthologous genes of similar ECM fungal species that would allow it to adapt in nature to optimize sugar uptake from the environment depending on the presence of different microorganisms. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Collin M Timm

    2015-10-01

    Full Text Available The bacterial microbiota of plants is diverse, with 1,000s of operational taxonomic units (OTUs associated with any individual plant. In this work we investigate the differences between 19 sequenced Pseudomonas fluorescens strains, isolated from Populus deltoides rhizosphere and endosphere and which represent a single OTU, 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 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 towards 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 towards 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.

  14. Rhizobacteria Pseudomonas fluorescens and Azospirillum sp. association enhances growth of Lactuca sativa L. under tropical conditions

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    Amael APONTE

    2017-06-01

    Full Text Available The selection of microorganisms that enhance plant growth and confer biotic and abiotic tolerance to crops constitutes a biotechnology currently gaining importance on a global scale. The aim of this investigation was to evaluate the effects of inoculating rhizobacteria to lettuce (Lactuca sativa L. on seed germination and vegetative development in order to use isolates as potential biofertilizers under tropical conditions. Five isolates of Pseudomonas fluorescens (Pf and one of Azospirillum sp. (Az were inoculated to seeds using a bacterial suspension of 1.5*108 CFU*mL-1. In vitro, none of the isolates promoted germination. In vivo, isolates promoted growth and acted as stress alleviators by conferring tolerance to high temperatures (≥ 30 °C. The highest seedling emergence percentages were induced by the association of P.fluorescens with Azospirillum. This association also promoted the highest leaf-area in 25 d seedlings and exhibited a significantly higher dry-weight in 40 d plants compared to the control (P≤0.05 supporting the advantages of bio-consortiums over individual strains. The strains were able to produce dependent L-tryptophan indole-3-acetic acid (IAA, to solubilize phosphorous in vitro and tolerated at least 5%-salt stress. The results indicate that isolate Pf (26 and Az possess plant growth promoting rhizobacteria (PGPR traits and should be further assessed. This study suggests that P. fluorescens and Azospirillum act synergically and are able to trigger an induced-tolerance mechanism in lettuce under abiotic stress.

  15. Nonribosomal peptides, key biocontrol components for Pseudomonas fluorescens In5, isolated from a Greenlandic suppressive soil.

    Science.gov (United States)

    Michelsen, Charlotte F; Watrous, Jeramie; Glaring, Mikkel A; Kersten, Roland; Koyama, Nobuhiro; Dorrestein, Pieter C; Stougaard, Peter

    2015-03-17

    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. Crop rotation and systematic pest management are used to only a limited extent in Greenlandic potato farming. Nonetheless, although plant-pathogenic fungi are present in the soil, the farmers do not experience major plant disease outbreaks. Here, we show that a Greenlandic potato soil is suppressive against Rhizoctonia solani, and we unravel the key biocontrol components for Pseudomonas fluorescens In5, one of the potent biocontrol bacteria

  16. Lethality and developmental delay in Drosophila melanogaster larvae after ingestion of selected Pseudomonas fluorescens strains.

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    Marika H Olcott

    2010-09-01

    Full Text Available The fruit fly, Drosophila melanogaster, is a well-established model organism for probing the molecular and cellular basis of physiological and immune system responses of adults or late stage larvae to bacterial challenge. However, very little is known about the consequences of bacterial infections that occur in earlier stages of development. We have infected mid-second instar larvae with strains of Pseudomonas fluorescens to determine how infection alters the ability of larvae to survive and complete development.We mimicked natural routes of infection using a non-invasive feeding procedure to study the toxicity of the three sequenced P. fluorescens strains (Pf0-1, SBW25, and Pf-5 to Drosophila melanogaster. Larvae fed with the three strains of P. fluorescens showed distinct differences in developmental trajectory and survival. Treatment with SBW25 caused a subset of insects to die concomitant with a systemic melanization reaction at larval, pupal or adult stages. Larvae fed with Pf-5 died in a dose-dependent manner with adult survivors showing eye and wing morphological defects. In addition, larvae in the Pf-5 treatment groups showed a dose-dependent delay in the onset of metamorphosis relative to control-, Pf0-1-, and SBW25-treated larvae. A functional gacA gene is required for the toxic properties of wild-type Pf-5 bacteria.These experiments are the first to demonstrate that ingestion of P. fluorescens bacteria by D. melanogaster larvae causes both lethal and non-lethal phenotypes, including delay in the onset of metamorphosis and morphological defects in surviving adult flies, which can be decoupled.

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

    Science.gov (United States)

    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. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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

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    Gerasimos F Kremmydas

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

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

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    Letícia Dias dos Anjos Gonçalves

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

  20. Survival of a Rifampicin-Resistant Pseudomonas fluorescens Strain in Nine Mollisols

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    Tami L. Stubbs

    2014-01-01

    Full Text Available Pseudomonas fluorescens strain D7 (P.f. D7 is a naturally occurring soil bacterium that shows promise as a biological herbicide to inhibit growth of annual grass weeds, including downy brome (Bromus tectorum L., in crop- and rangelands. Pseudomonas fluorescens strain D7rif (P.f. D7rif is a rifampicin-resistant strain of P.f. D7. One of the greatest obstacles to successful biological weed control is survival of the organism under field conditions. Nine soils in the taxonomic order of Mollisols, collected from downy brome-infested areas of the Western and Central United States, were inoculated with P.f. D7rif and incubated in the laboratory to determine the effects of soil type, soil properties, incubation temperature, and soil water potential on survival of P.f. D7rif over 63 days. Silt loam soils from Lind, Washington, and Moro, Oregon, sustained the highest P.f. D7rif populations, and recovery was the lowest from Pendleton, Oregon soil. Survival and recovery of P.f. D7rif varied with soil type and temperature but not with the two soil water potentials tested. After 63 days, P.f. D7rif was recovered at levels greater than log 5.5 colony forming units (CFU g−1 soil from five of the nine test soils, a level adequate to suppress downy brome under field or range conditions.

  1. Biocontrol of Rhizoctonia solani in native potato (Solanum phureja plants using native Pseudomonas fluorescens

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    Gloria Bautista

    2007-01-01

    Full Text Available Rhizoctonia solani is a soil borne phytopathogen associated with reduced plant vigor and tuber production in potato crops. There is a huge interest to search alternatives of biological control management of this disease, because the potato crops in Colombia are the highest consumers of chemical pesticides in Colombia. In order to obtain a fluorescent Pseudomonas strain with the capacity to reduce the disease symptoms produced by R. solani, determination and isolation of the predominant fluorescent Pseudomonas in several potato crops of the main Colombian producing region was done in a previous study. Six different P. fluorescens strains with none, moderate and high fungal growth inhibition capacity in vitro, were used in this study. Despite of the differences found in the dynamics of colonization and colonization capacity, all evaluated strains induced S. phureja growth and reduced disease symptoms produced by R. solani. Our results support the conclusion that association of P. fluorescens strains with S. phureja rhizosphere is a feasible alternative for the management of R. solani symptoms.

  2. Bioremediation of chromium contaminated soil by Pseudomonas fluorescens and indigenous microorganisms.

    Science.gov (United States)

    Jeyalakshmi, D; Kanmani, S

    2008-01-01

    Chromium is one of the toxic and hazardous pollutants in industrial wastewaters leading to soil contamination. In this study, the feasibility of remediating chromium contaminated soil using indigenous microorganisms and Pseudomonas fluorescens was evaluated. The contaminated soil sample was collected from Vellore and the pH, moisture content and chromium content were found to be 8.4, 22.5% and 5.1 mg/kg respectively. The effect of chromium on engineering properties showed decrease in permeability by 45.15%. For Pseudomonas fluorescens, the optimum pH, moisture content, biomass concentration and carbon source were found as 6.5, 20%, 10 mL and 10 mL/100 g respectively and for isolated mixed culture, the optimum parameters were found as 8.4, 25%, 15 mL and 15mL / 100 g respectively. Under optimum conditions, the reactor study showed 71.7% chromium reduction after 20 days. From the study, the bioremediation of chromium-contaminated soil by indigenous microorganisms was found to be a promising solution and after bioremediation, the engineering properties of the soil were found to be improved.

  3. Complete genome sequence of the lytic cold-active Pseudomonas fluorescens bacteriophage VSW-3 from Napahai plateau wetland.

    Science.gov (United States)

    Zhang, Chunjing; Zhang, Zhongyao; Li, Jiankai; Qin, Kunhao; Wei, Yunlin; Zhang, Qi; Lin, Lianbing; Ji, Xiuling

    2017-02-01

    The lytic cold-active bacteriophage VSW-3, belonging to the Podoviridae family and infecting the host Pseudomonas fluorescens SW-3, was isolated from the Napahai plateau wetland in China. With the development of sequencing technology, the study of Pseudomonas genomic diversity has increased; however, knowledge of cold-active phages infecting Pseudomonas is limited. The newly sequenced phage VSW-3 was classified based on virion morphology by transmission electron microscope. Sequence analysis revealed that the genome size was 40,556 bp with an overall GC content of 57.54 % and 46 open reading frames. The genome was organized into several modules containing genes for packaging, structural proteins, replication/transcription, and phage lysis. The sequence contained 45 potential promoters, 3 transcription terminators, and yet no tRNAs. This is the first report of cold-active Pseudomonas fluorescens bacteriophage genome sequencing.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Archana [ORNL; Layton, Alice [University of Tennessee, Knoxville (UTK); Williams, Daniel W [ORNL; Smart, Abby E. [University of Tennessee, Knoxville (UTK); Ripp, Steven Anthony [ORNL; Karpinets, Tatiana V [ORNL; Brown, Steven D [ORNL; Sayler, Gary Steven [ORNL

    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.

  5. Wave-like distribution patterns of Gfp-marked Pseudomonas fluorescens along roots of wheat plants grown in two soils

    NARCIS (Netherlands)

    Bruggen, van A.H.C.; Semenov, A.M.; Zelenev, V.V.; Semenov, A.V.; Raaijmakers, J.M.; Sayler, R.J.; Vos, de O.J.

    2008-01-01

    Culturable rhizosphere bacterial communities had been shown to exhibit wave-like distribution patterns along wheat roots. In the current work we show, for the first time, significant wave-like oscillations of an individual bacterial strain, the biocontrol agent Pseudomonas fluorescens 32 marked with

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

    Science.gov (United States)

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

    2011-01-01

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

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

    Science.gov (United States)

    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...

  8. Kinetic modelling of enzyme inactivation : kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F

    NARCIS (Netherlands)

    Schokker, E.P.

    1997-01-01

    The kinetics of heat inactivation of the extracellular proteinase from Pseudomonas fluorescens 22F was studied. It was established, by making use of kinetic modelling, that heat inactivation in the temperature range 35 - 70 °C was most likely caused

  9. Pseudomonas fluorescens F113 Mutant with Enhanced Competitive Colonization Ability and Improved Biocontrol Activity against Fungal Root Pathogens ▿

    Science.gov (United States)

    Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

    2011-01-01

    Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible. PMID:21685161

  10. Pseudomonas fluorescens F113 mutant with enhanced competitive colonization ability and improved biocontrol activity against fungal root pathogens.

    Science.gov (United States)

    Barahona, Emma; Navazo, Ana; Martínez-Granero, Francisco; Zea-Bonilla, Teresa; Pérez-Jiménez, Rosa María; Martín, Marta; Rivilla, Rafael

    2011-08-01

    Motility is one of the most important traits for efficient rhizosphere colonization by Pseudomonas fluorescens F113rif (F113). In this bacterium, motility is a polygenic trait that is repressed by at least three independent pathways, including the Gac posttranscriptional system, the Wsp chemotaxis-like pathway, and the SadB pathway. Here we show that the kinB gene, which encodes a signal transduction protein that together with AlgB has been implicated in alginate production, participates in swimming motility repression through the Gac pathway, acting downstream of the GacAS two-component system. Gac mutants are impaired in secondary metabolite production and are unsuitable as biocontrol agents. However, the kinB mutant and a triple mutant affected in kinB, sadB, and wspR (KSW) possess a wild-type phenotype for secondary metabolism. The KSW strain is hypermotile and more competitive for rhizosphere colonization than the wild-type strain. We have compared the biocontrol activity of KSW with those of the wild-type strain and a phenotypic variant (F113v35 [V35]) which is hypermotile and hypercompetitive but is affected in secondary metabolism since it harbors a gacS mutation. Biocontrol experiments in the Fusarium oxysporum f. sp. radicis-lycopersici/Lycopersicum esculentum (tomato) and Phytophthora cactorum/Fragaria vesca (strawberry) pathosystems have shown that the three strains possess biocontrol activity. Biocontrol activity was consistently lower for V35, indicating that the production of secondary metabolites was the most important trait for biocontrol. Strain KSW showed improved biocontrol compared with the wild-type strain, indicating that an increase in competitive colonization ability resulted in improved biocontrol and that the rational design of biocontrol agents by mutation is feasible.

  11. Longitudinal nosocomial outbreak of Pseudomonas fluorescens bloodstream infection of 2 years' duration in a coronary care unit.

    Science.gov (United States)

    Oba, Yuichiro; Nakajima, Takahiro; Ogida, Chiyo; Kawanami, Miyuki; Fujiwara, Mamoru; Matsumura, Ikuko

    2017-08-01

    Outbreaks of bloodstream infections (BSI) of nonfermenting bacteria are a critical issue and often associated with hospital environments. We experienced a long-lasting outbreak of Pseudomonas fluorescens BSI limited to a coronary care unit (CCU). We conducted a retrospective epidemiologic investigation and a case-control study for Pseudomonas fluorescens BSI from April 2011-July 2014. Environmental sample culture was conducted to detect the specific environmental source of transmission. Hospital-wide microbiology data from the term identified 13 case patients with P fluorescens BSI and 32 control patients with BSI due to organisms other than P fluorescens in the CCU. The case-control study revealed that the case group had significantly higher odds of exposure to only cardiac output (CO) measurement with thermodilution method (odds ratio, 22.0; 95% confidence interval, 2.4-202.3). The organism was identified only from an ice bath used for CO measurement. The susceptibility patterns were identical among all strains derived from the cases and the environment. The nosocomial outbreak of P fluorescens BSI in our CCU over 2 years was associated with a contaminated ice bath used for CO measurement within the unit. Detection and elimination of the specific source was essential to stop the outbreak. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Mavrodi, Dmitri V; Loper, Joyce E; Paulsen, Ian T; Thomashow, Linda S

    2009-01-13

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

  14. A modular esterase from Pseudomonas fluorescens subsp. cellulosa contains a non-catalytic cellulose-binding domain.

    OpenAIRE

    Ferreira, L M; Wood, T M; Williamson, G; Faulds, C; Hazlewood, G P; Black, G W; Gilbert, H J

    1993-01-01

    The 5' regions of genes xynB and xynC, coding for a xylanase and arabinofuranosidase respectively, are identical and are reiterated four times within the Pseudomonas fluorescens subsp. cellulosa genome. To isolate further copies of the reiterated xynB/C 5' region, a genomic library of Ps. fluorescens subsp. cellulosa DNA was screened with a probe constructed from the conserved region of xynB. DNA from one phage which hybridized to the probe, but not to sequences upstream or downstream of the ...

  15. Pseudomonas fluorescens

    African Journals Online (AJOL)

    Subhadfip Nandi

    2013-04-10

    Apr 10, 2013 ... Damping off caused by Sclerotium rolfsii on cowpea results in yield losses with serious socio- economic implication. Induction of defense responses by plant growth promoting rhizobacteria (PGPR) is largely associated with the production of defense enzyme phenyl ammonia lyase (PAL) and oxidative.

  16. Effect of a Pseudomonas fluorescens tailocin against phytopathogenic Xanthomonas observed by atomic force microscopy.

    Science.gov (United States)

    Fernandez, Maricruz; Godino, Agustina; Príncipe, Analía; Morales, Gustavo M; Fischer, Sonia

    2017-08-20

    Phage tail-like bacteriocins, called tailocins, represent a class of protein complexes produced by a multitude of bacteria. Pseudomonas fluorescens SF4c, a strain isolated from wheat rhizosphere, produces a bacteriocin similar to phage tail-like pyocins of Pseudomonas aeruginosa. This tailocin has antimicrobial activity against several phytopathogenic strains of the genus Xanthomonas and Pseudomonas. In this work, the effect of the SF4c tailocin on the phytopathogenic strain X. axonopodis pv vesicatoria Xcv Bv5-4a was analyzed through Atomic Force Microscopy (AFM). We demonstrated that tailocins adhere and cause damage to the cell envelope of strain Xcv Bv5-4a. This results in a rapid leakage of intracellular materials, with the subsequent decrease of cell volume. Finally, lysis of sensitive bacteria occurs. This study provides, to our knowledge, the first evidence about the effect of a tailocin analyzed by AFM. Further studies are in progress to evaluate the use of SF4c tailocin in the biocontrol of bacterial spot on tomato. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Evolution of fitness trade-offs in locally adapted populations of Pseudomonas fluorescens

    DEFF Research Database (Denmark)

    Schick, Alana; Bailey, Susan; Kassen, Rees

    2015-01-01

    characterize the genetic causes of trade-offs generating local adaptation in populations of Pseudomonas fluorescens that had previously been evolved for specialization on three different carbon resources. We measured the fitness effects of mutations that arose during selection in that environment...... and in alternative environments to quantify the degree of specialization. We find that all mutations are beneficial in the environment of selection and that those arising later during adaptation are associated with increasingly antagonistic effects in alternative environments compared with those arising earlier......, consistent with a multioptima version of Fisher’s geometric model of adaptation. We also find that fitness of pairs of beneficial mutations are consistently less than additive in selection environments, producing a pattern of diminishing returns, but are more variable in alternative environments, being...

  18. The impact of cellulose nanocrystals on the aggregation and initial adhesion of Pseudomonas fluorescens bacteria.

    Science.gov (United States)

    Sun, Xiaohui; Lu, Qingye; Boluk, Yaman; Liu, Yang

    2014-11-28

    Deposition on silica surfaces of two Pseudomonas fluorescens strains (CHA0 and CHA19-WS) having different extracellular polymeric substance (EPS) producing capacities was studied in the absence and presence of cellulose nanocrystals (CNCs). Batch (batch soaking) and continuous flow (quartz crystal microbalance with dissipation) methods were used to evaluate the impact of CNCs on bacterial initial adhesion. This study demonstrated that bacterial initial adhesion to solid surfaces can be significantly hindered by CNCs using both methods. In the presence of CNCs, it was observed that bacteria with more EPS aggregated more significantly compared to bacteria with less EPS, and that bacterial deposition under this condition decreased to a greater extent. The classic DLVO theory failed to predict bacterial adhesion behavior in this study. A detailed discussion is provided regarding potential antibacterial adhesion mechanisms of CNCs.

  19. Bistability in a Metabolic Network Underpins the De Novo Evolution of Colony Switching in Pseudomonas fluorescens

    DEFF Research Database (Denmark)

    Gallie, Jenna; Libby, Eric; Bertels, Frederic

    2015-01-01

    in central metabolism (carB) generates such a striking phenotype. We show that colony switching is underpinned by ON/OFF expression of capsules consisting of a colanic acid-like polymer. We use molecular genetics, biochemical analyses, and experimental evolution to establish that capsule switching results......Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical...... insight was delivered by an experiment in which populations of the bacterium Pseudomonas fluorescens SBW25 evolved, de novo, the ability to switch between two colony phenotypes. Here we unravel the molecular mechanism behind colony switching, revealing how a single nucleotide change in a gene enmeshed...

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

    Science.gov (United States)

    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.

  1. Utilization of Pseudomonas fluorescens as Antimicrobial agent on Lipolysis Inhibitition of Rice Bran

    Directory of Open Access Journals (Sweden)

    Titin Widiyastuti

    2002-01-01

    Full Text Available Feedstuff was limited by fat content, certainly, if the material feedstuff was storage on long time periods. Fat was oxidized or hydrolyzed, which was decreased nutritional quality. A Research on Inhibited of  Lypolysis Rice Bran with anti-microbial compound of Pseudomonas fluorescens was conducted during ten month. The research used experiment methods, with Randomized Completely Block Design, storage as block and concentration of anti-mikrobial compound as treatment. Fat and polyunsaturated fatty acids content during storage was observed. Result of experiment showed anti-microbial compound inhibited oxidize and hydrolyze process of fat rice bran during six month storage. (Animal Production 4(2: 89-93 (2002

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

    Science.gov (United States)

    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

  3. BIOCONTROL OF Rhizoctonia solani IN NATIVE POTATO (Solanum phureja PLANTS USING NATIVE Pseudomonas fluorescens

    Directory of Open Access Journals (Sweden)

    GLORIA BAUTISTA

    2007-01-01

    Full Text Available Rhizoctonia solani es un hongo fitopatógeno del suelo, el cual produce una reducción significativa del vigor de las plantas y de la producción de tubérculos en cultivos de papa. Es de gran interés la búsqueda de alternativas de manejo de esta enfermedad, especialmente desde la perspectiva de control biológico ya que los cultivos de papa son los mayores consumidores de plaguicidas de origen químicos en Colombia. Con el objeto de obtener una cepa del grupo de las Pseudomonas fluorescentes con la capa- cidad para reducir los síntomas de la enfermedad producidos por R. solani, se realizó en un estudio previo el aislamiento y caracterización de una colección de aislamientos de Pseudomonas fluorescentes provenientes de diferentes cultivos de la región papera más productiva del país. Seis cepas nativas de P. fluorescens con buena, moderada o ninguna capacidad para inhibir el crecimiento fúngico in vitro fueron seleccionadas. A pesar de las diferencias encontradas en términos de la dinámica y capacidad de colonización, todas las cepas evaluadas indujeron el crecimiento en las plantas de S. phureja y redujeron los síntomas de la enfermedad producidos por R. solani a nivel de invernadero. Nuestros resultados sustentan la conclusión que la asociación de cepas de P. fluorescens con la rizosfera de S. phureja es una alternativa para el manejo de R. solani en papa.

  4. LapD Is a Bis-(3', 5')-Cyclic Dimeric GMP-Binding Protein That Regulates Surface Attachment by Pseudomonas fluorescens Pf0-1

    National Research Council Canada - National Science Library

    Peter D. Newell; Russell D. Monds; George A. O'Toole; Emil C. Gotschlich

    2009-01-01

    .... For Pseudomonas fluorescens Pf0-1, c-di-GMP impacts the secretion and localization of the adhesin LapA, which is absolutely required for stable surface attachment and biofilm formation by this bacterium...

  5. Contribution of alginate and levan production to biofilm formation by Pseudomonas syringae

    DEFF Research Database (Denmark)

    Laue, H.; Schenk, A.; Li, H.

    2006-01-01

    formation, biofilms of Pseudomonas syringae strains with different EPS patterns were compared. The mucoid strain PG4180.muc, which produces levan and alginate, and its levan- and/or alginate-deficient derivatives all formed biofilms in the wells of microtitre plates and in flow chambers. Confocal laser...

  6. Exposure-related effects of formulated Pseudomonas fluorescens strain CL145A to glochidia from seven unionid mussel species

    Science.gov (United States)

    Luoma, James A.; Weber, Kerry L.; Severson, Todd J.; Schreier, Theresa M.; Mayer, Denise A.; Aloisi, Douglas B.; Eckert, Nathan L.

    2015-01-01

    The study was completed to evaluate the exposure-related effects of a biopesticide for dreissenid mussel (Dreissena polymorpha, zebra mussel and Dreissena rostriformis bugensis, quagga mussel) control on glochidia from unionid mussels endemic to the Great Lakes and Upper Mississippi River Basins. The commercially prepared biopesticide was either a spray-dried powder (SDP) or freeze-dried powder (FDP) formulation of Pseudomonas fluorescens, strain CL145A. Glochidia of the unionid mussel species Lampsilis cardium, Lampsilis siliquoidea,Lampsilis higginsii, Ligumia recta, Obovaria olivaria, and Actinonaias ligamentina were exposed to SDP-formulated P. fluorescens andLampsilis cardium and Megalonaias nervosa were exposed to FDP-formulated P. fluorescens.

  7. KAJIAN MEKANISME ANTAGONIS PSEUDOMONAS FLUORESCENS P60 TERHADAP FUSARIUM OXYSPORUM F.SP. LYCOPERSICI PADA TANAMAN TOMAT IN VIVO

    Directory of Open Access Journals (Sweden)

    Loekas Soesanto, Endang Mugiastuti & Ruth Feti Rahayuniati .

    2011-11-01

    Full Text Available Antagonistic mechanisms study of Pseudomonas fluorescens P60 on Fusarium oxysporum f.sp. lycopersici of tomato in vivo.  This research was conducted to evaluate the effect of P. fluorescens P60 in controlling Fusarium wilt on tomato and its inhibition mechanisms. Randomized Block Design was used with four replicates and each consisted of 12 crops. The treatments tested were combination between supernatant or suspension of P. fluorescens P60 and application time, i.e., 5 days before planting, in the same time with planting, and 5 days after planting. Variables observed were phenolic compound (tannin, saponin, and glycoside, disease intensity, infection rate, late pathogen and antagonist population density, crop height, stem diameter, fresh and dry weight of roots, and fresh weight of fruit. The result showed that the application of P. fluorescens P60 either in supernatant or suspension form, could increase phenolic compound in the crop tissue, decrease the Fusarium wilt intensity on tomato as 66.00-77.88%, suppress infection rate as 73.18-79.09%, decrease late F. oxysporum f.sp. lycopersici density as 35.71%, increase the antagonist as 10 fold, increase crop height as 26.50%, improve root dry weight as 55.69%, and increase fruit weight crop-1 as 59.79%. Mechanisms of the antagonist P. fluorescens P60 in order to control the disease in the field were induced resistance, antibiosis, and plant growth promoting rhizobacteria.

  8. Effects of Pseudomonas fluorescens on the Water Parameters of Mycorrhizal and Non-Mycorrhizal Seedlings of Pinus halepensis

    Directory of Open Access Journals (Sweden)

    José A. Saiz de Omeñaca

    2013-08-01

    Full Text Available Inoculation of forest seedlings with mycorrhizal fungi and rhizobacteria can improve the morphological and physiological qualities of plants, especially those used for regeneration of arid areas. In this paper, under standard nursery conditions, Aleppo pine seedlings were inoculated with Pseudomonas fluorescens CECT 5281 rhizobacteria. Some of these seedlings were also inoculated with the ectomycorrhizal fungus Pisolithus tinctorius. Five months after the inoculations, we examined the growth, water parameters (osmotic potential at full turgor [Ψπfull], osmotic potential at zero turgor [Ψπ0], and the tissue modulus of elasticity near full turgor [Emax], mycorrhizal colonisation, and concentration of macronutrients (N, P, K, Ca and Mg in the seedlings. Subsequently, a trial was conducted to assess the root growth potential. P. fluorescens CECT 5281 decreased the cellular osmotic potential of P. halepensis seedlings but increased its elasticity. P. tinctorius + P. fluorescens caused osmotic adjustment at zero turgor and increased tissue elasticity, which improved tolerance to water stress. All inoculations improved the growth and nutrition of the seedlings but caused non-significant effects on root growth potential. The co-inoculation Pisolithus tinctorius + Pseudomonas fluorescens at the nursery may be a suitable technique for producing improved seedling material for restoration purposes.

  9. The nucleotide sequence of a carboxymethylcellulase gene from Pseudomonas fluorescens subsp. cellulosa.

    Science.gov (United States)

    Hall, J; Gilbert, H J

    1988-07-01

    The complete nucleotide sequence of the gene coding for one of the carboxymethylcellulases (CMCase), expressed by Pseudomonas fluorescens subsp. cellulosa, has been determined. The structural gene consists of an open reading frame, commencing with an ATG start codon, of 2886 base pairs followed by a TAA stop codon. The gene was shown to code for a signal peptide which closely resembles the signal peptides of other secreted proteins. Unlike most Pseudomonas genes, the CMCase sequence does not have a high G + C (51%) content and there is no marked preference for codons ending in G or C. Upstream of the structural gene there are no sequences which bear a strong resemblance to consensus Escherichia coli promoters. A sequence is present, however, which exhibits homology to the consensus DNA sequence that binds the catabolic activator protein (CAP). Bal31 deletions of the structural gene revealed the extent by which the gene could be modified and still encode a functional CMCase. Subclones of the cellulase gene have been constructed in pUC18 and pUC19. One of the resultant plasmids, pJHS1 directs a 20-fold increase in CMCase synthesis, when compared to the original construct, pJHH2. Analysis of cells harbouring pJHS1 showed the cellulase polypeptide to have a molecular weight of 106000. This is in close agreement with the predicted size of the enzyme deduced from the nucleotide sequence data.

  10. A phosphate-starvation-inducible outermembrane protein of Pseudomonas fluorescens Ag1 as an immunological phosphate-starvation marker

    DEFF Research Database (Denmark)

    Leopold, Kristine; Jacobsen, Susanne; Nybroe, Ole

    1997-01-01

    A phosphate-starvation-inducible outer-membrane protein of Pseudomonas fluorescens Ag1, expressed at phosphate concentrations below0.08-0.13 mM, was purified and characterized. The purification method involved separation of outer-membrane proteins by SDS-PAGE andextraction of the protein from...... nitrocellulose or PVDF membranes after electrotransfer of proteins to the membranes. The N-terminal amino acidsequence of the purified protein, called Psi1, did not show homology to any known proteins, and in contrast to the phosphate-specific porin OprP ofP. aeruginosa its mobility in SDS-PAGE was not affected...... by solubilization temperature. An antiserum against Psi1 recognized a protein of M,55,000 in four other P. fluorescens strains among 24 tested strains representing Pseudomonas rRNA homology group I, showing antigenicheterogeneity within this group. A method for immunofluorescence microscopy involving cell...

  11. Inhibition of Vibrio anguillarum by Pseudomonas fluorescens AH2, a possible probiotic treatment of fish

    DEFF Research Database (Denmark)

    Gram, Lone; Melchiorsen, Jette; Spanggaard, Bettina

    1999-01-01

    of P.fluorescens AH2 was studied under iron-rich and iron-limited conditions. Sterile-filtered culture supernatants from iron- limited P. fluorescens AH2 inhibited the growth of V. anguillarum, whereas sterile-filtered supernatants from iron- replete cultures of P. fluorescens AH2 did not. P...

  12. Optimization of worm-bed leachate for culturing of tomato (Lycopersicon esculentum Mill) inoculated with Glomus fasciculatum and Pseudomonas fluorescens

    OpenAIRE

    Oliva-Llaven,María Ángela; Rodríguez-Hernández,Ludwi; Mendoza-Nazar,Paula; Ruiz-Sesma, Benigno; Álvarez-Solís,José David; Dendooven, Luc; Federico A. Gutiérrez-Miceli

    2010-01-01

    A response surface technique was used to analyze the effect of Glomus fasciculatum, Pseudomonas fluorescens and worm-bed leachate (WBL) on growth, yield and characteristics of tomato (Lycopersicon esculentum Mill). The treatments combined inoculation with or without P. fluorescensor G. fasciculatum and the application of WBL at 20% (v/v) each day or every three days. Plant height, number of leaves and yield of tomato fruits was not affected by the factors studied. However, plants with foliar ...

  13. Draft genome sequence of the polycyclic aromatic hydrocarbon-degrading, genetically engineered bioluminescent bioreporter Pseudomonas fluorescens HK44.

    Science.gov (United States)

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

    2011-09-01

    Pseudomonas fluorescens strain HK44 (DSM 6700) is a genetically engineered lux-based bioluminescent bioreporter. Here we report the draft genome sequence of strain HK44. Annotation of ∼6.1 Mb of sequence indicates that 30% of the traits are unique and distributed over five genomic islands, a prophage, and two plasmids. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

  14. Efficacy of Pseudomonas fluorescens (Pf-CL145A) spray dried powder for controlling zebra mussels adhering to test substrates

    Science.gov (United States)

    Luoma, James A.; Severson, Todd J.; Weber, Kerry L.; Mayer, Denise A.

    2015-01-01

    A mobile bioassay trailer was used to assess the efficacy of Pseudomonas fluorescens (Pf-CL145A) spray dried powder (SDP) formulation for controlling zebra mussels (Dreissena polymorpha) from two midwestern lakes: Lake Carlos (Alexandria, Minnesota) and Shawano Lake (Shawano, Wisconsin). The effects of SDP exposure concentration and exposure duration on zebra mussel survival were evaluated along with the evaluation of a benthic injection application technique to reduce the amount of SDP required to induce zebra mortality.

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

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    Daniel Garcia-Seco

    Full Text Available 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.

  16. The cellodextrinase from Pseudomonas fluorescens subsp. cellulosa consists of multiple functional domains.

    Science.gov (United States)

    Ferreira, L M; Hazlewood, G P; Barker, P J; Gilbert, H J

    1991-11-01

    A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA was constructed in pUC18 and Escherichia coli recombinants expressing 4-methylumbelliferyl beta-D-cellobioside-hydrolysing activity (MUCase) were isolated. Enzyme produced by MUCase-positive clones did not hydrolyse either cellobiose or cellotriose but converted cellotetraose into cellobiose and cleaved cellopentaose and cellohexaose, producing a mixture of cellobiose and cellotriose. There was no activity against CM-cellulose, insoluble cellulose or xylan. On this basis, the enzyme is identified as an endo-acting cellodextrinase and is designated cellodextrinase C (CELC). Nucleotide sequencing of the gene (celC) which directs the synthesis of CELC revealed an open reading frame of 2153 bp, encoding a protein of Mr 80,189. The deduced primary sequence of CELC was confirmed by the Mr of purified CELC (77,000) and by the experimentally determined N-terminus of the enzyme which was identical with residues 38-47 of the translated sequence. The N-terminal region of CELC showed strong homology with endoglucanase, xylanases and an arabinofuranosidase of Ps. fluorescens subsp. cellulosa; homologous sequences included highly conserved serine-rich regions. Full-length CELC bound tightly to crystalline cellulose. Truncated forms of celC from which the DNA sequence encoding the conserved domain had been deleted, directed the synthesis of a functional cellodextrinase that did not bind to crystalline cellulose. This is consistent with the N-terminal region of CELC comprising a non-catalytic cellulose-binding domain which is distinct from the catalytic domain. The role of the cellulose-binding region is discussed.

  17. Pseudomonas fluorescens F113 can produce a second flagellar apparatus, which is important for root colonization.

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    Emma Barahona

    2016-09-01

    Full Text Available The genomic sequence of Pseudomonas fluorescens F113 has shown the presence of a 41 kb cluster of genes that encode the production of a second flagellar apparatus. Among 2535 pseudomonads strains with sequenced genomes, these genes are only present in the genomes of F113 and other six strains, all but one belonging to the P. fluorescens cluster of species, in the form of a genetic island. The genes are homologous to the flagellar genes of the soil bacterium Azotobacter vinelandii. Regulation of these genes is mediated by the flhDC master operon, instead of the typical regulation in pseudomonads, which is through fleQ. Under laboratory conditions, F113 does not produce this flagellum and the flhDC operon is not expressed. However, ectopic expression of the flhDC operon is enough for its production, resulting in a hypermotile strain. This flagellum is also produced under laboratory conditions by the kinB and algU mutants. Genetic analysis has shown that kinB strongly represses the expression of the flhDC operon. This operon is activated by the Vfr protein probably in a c-AMP dependent way. The strains producing this second flagellum are all hypermotile and present a tuft of polar flagella instead of the single polar flagellum produced by the wild-type strain. Phenotypic variants isolated from the rhizosphere produce this flagellum and mutation of the genes encoding it, results in a defect in competitive colonization, showing its importance for root colonization.

  18. INFLUÊNCIA DA ATIVIDADE ENZIMÁTICA DE PSEUDOMONAS FLUORESCENS 041 EM LABNEH

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    Andreza Angélica Ferreira

    2012-04-01

    Full Text Available A refrigeração do leite proporciona a seleção de bactérias psicrotróficas deteriorantes produtoras de enzimas termoresistentes que podem comprometer a qualidade do leite e derivados. O objetivo deste trabalho foi avaliar as implicações causadas pela atividade enzimática de Pseudomonas fluorescens 041 na produção de Labneh. O leite pasteurizado foi inoculado intencionalmente com, aproximadamente, 106 UFC.mL-1 de P. fluorescens 041 e Labneh foi produzido imediatamente após inoculação no leite (tempo 0 e após 48, 72 e 96 horas de inoculação e armazenamento a 4 ºC. A qualidade físico-química do leite, do Labneh e do soro resultante da fabricação foi determinada. O rendimento prático, o rendimento técnico ajustado e o aproveitamento final de sólidos no Labneh em relação ao volume de leite (coeficiente GL também foram avaliados. Constatou-se alterações nas características físico-químicas do soro e do Labneh fabricado com leite armazenado a partir de 48 horas. Também, observou-se um aumento significativo em litros de leite destinado à produção de um quilo do produto ao longo do tempo de estocagem do leite inoculado com P. fluorescens 041, sendo os rendimentos prático, técnico ajustado e o coeficiente GL afetados pelo fator tempo. Portanto, a redução do tempo de estocagem do leite sob refrigeração e a prevenção da contaminação da matéria-prima por meio da adoção de boas práticas na cadeia do leite são medidas a serem adotadas para assegurar a qualidade e o rendimento do produto final.

  19. The effect of alginate lyase on the gentamicin resistance of Pseudomonas aeruginosa in mucoid biofilms.

    Science.gov (United States)

    Germoni, L A P; Bremer, P J; Lamont, I L

    2016-07-01

    Pseudomonas aeruginosa can secrete large amounts of alginate during chronic infections and this has been associated with high resistance to antibiotics. The major aim of this study was to investigate whether degradation of extracellular alginate by alginate lyase would increase the sensitivity of Ps. aeruginosa to gentamicin, an aminoglycoside antibiotic. Degradation of alginate from Ps. aeruginosa was monitored using a spectrometric assay. Alginate lyase depolymerized alginate, but calcium and zinc cations at concentrations found in the cystic fibrosis lung reduced enzyme activity. Biofilms formed on agar were partially degraded by alginate lyase, but staining with crystal violet showed that the biomass of biofilms grown in liquid was not significantly affected by the enzyme. Viability testing showed that the sensitivity to gentamicin of biofilm bacteria and of bacteria released from biofilms was unaffected by alginate lyase. Our results show that at least under the conditions used here alginate lyase does not affect gentamicin resistance of Ps. aeruginosa. Our study indicates that alginate does not contribute to resistance to gentamicin and so does not provide support for the concept of treating patients with alginate lyase in order to increase the antibiotic sensitivity of Ps. aeruginosa. © 2016 The Society for Applied Microbiology.

  20. Impact of alginate-producing Pseudomonas aeruginosa on alveolar macrophage apoptotic cell clearance

    Science.gov (United States)

    Poirier, Christophe; Serban, Karina A.

    2014-01-01

    Pseudomonas aeruginosa infection is a hallmark of lung disease in cystic fibrosis. Acute infection with P. aeruginosa profoundly inhibits alveolar macrophage clearance of apoptotic cells (efferocytosis) via direct effect of virulence factors. During chronic infection, P. aeruginosa evades host defense by decreased virulence, which includes the production or, in the case of mucoidy, overproduction of alginate. The impact of alginate on innate immunity, in particular on macrophage clearance of apoptotic cells is not known. We hypothesized that P. aeruginosa strains that exhibit reduced virulence impair macrophage clearance of apoptotic cells and we investigated if the polysaccharide alginate produced by mucoid P. aeruginosa is sufficient to inhibit alveolar macrophage efferocytosis. Rat alveolar or human peripheral blood monocyte (THP-1)-derived macrophages cell lines were exposed in vitro to exogenous alginate or to wild type or alginate-overproducing mucoid P. aeruginosa prior to challenge with apoptotic human Jurkat T-lymphocytes. The importance of LPS contamination and that of structural integrity of alginate polymers was tested using alginate of different purities and alginate lyase, respectively. Alginate inhibited alveolar macrophage efferocytosis in a dose- and time-dependent manner. This effect was augmented but not exclusively attributed to lipopolysaccharide (LPS) present in alginates. Alginate-producing P. aeruginosa inhibited macrophage efferocytosis by more than 50%. Although alginate lyase did not significantly restore efferocytosis in the presence of exogenous alginate, it had a marked beneficial effect on efferocytosis of alveolar macrophages exposed to mucoid P. aeruginosa. Despite decreased virulence, mucoid P. aeruginosa may contribute to ongoing airway inflammation through significant inhibition of alveolar clearance of apoptotic cells and debris. The mechanism by which mucoid bacteria inhibit efferocytosis may involve alginate production and

  1. Impact du séchage sur la viabilité de Pseudomonas fluorescens (synthèse bibliographique

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    Mputu Kanyinda, JN.

    2014-01-01

    Full Text Available Impact of drying on Pseudomonas fluorescens viability. A review. Drying Pseudomonas fluorescens makes for more economical storage, transportation and marketing. The aim of the drying process is to stop and to stabilize all biological activity for optimal storage, compatible with the conservation of the maximum desired viability of the microorganisms. However, the viability rate of the bacteria after drying depends on the operating conditions of the drying process. One of the most important criteria to consider during the drying of biologically active products is the quality of the final dried product. Freeze-drying is the drying method most commonly used for Pseudomonas fluorescens. After their production, the bacteria are harvested by centrifugation and are freeze-dried, but the changes in temperature induced by freeze-drying are not without consequence for the cells. The freeze-drying process induces cell damage: peroxidation of fatty acids and proteins and DNA oxidation. However, use of protective compounds during freeze-drying and during storage increases significantly the rate of cell viability.

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

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    Rawia F. Gamal

    2013-01-01

    Full Text Available 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.

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

    Science.gov (United States)

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

    2016-03-17

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

  4. Antimicrobial activity of four essential oils against pigmenting Pseudomonas fluorescens and biofilmproducing Staphylococcus aureus of dairy origin

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    Francesca Pedonese

    2017-12-01

    Full Text Available Essential oils (EOs are mixtures of secondary metabolites of plant origin with many useful properties, among which the antimicrobial activity is also of interest for the food industry. EOs can exert their antimicrobial potential both directly, in food products and active packaging, and indirectly, as sanitizing and anti-biofilm agents of food facility surfaces. Aim of this research was to evaluate the antimicrobial activity of four EOs (bergamot, cinnamon, manuka and thyme against Pseudomonas fluorescens and Staphylococcus aureus isolated from milk and dairy products. The chemical composition of EOs was evaluated by Gas Chromatography-Mass Spectrometry analysis. Minimum Inhibitory Concentration values were determined by a microplate method against 9 Ps. fluorescens from marketed mozzarella with blue discoloration defect, and 3 biofilm-producing S. aureus from milk. Reference ATCC strains were included. Pigment production activity by Ps. fluorescens was assessed both in culture and in cheese. EOs of manuka (leptospermone 23% and thyme (carvacrol 30%, pcymene 20%, thymol 15% showed the highest antimicrobial activity against S. aureus, MIC values were 0.012%-0.024% and 0.024% v/v, respectively; meanwhile EOs from thyme and cinnamon (cinnamaldehyde 55% exhibited the best activity against Ps. fluorescens with MIC values of 0.098%-0.195% and 0.195%-0.391% v/v, respectively. The antimicrobial activity of these EOs is promising and they could be exploited in the dairy production chain.

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

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    Thiruvengadam Raguchander

    2009-12-01

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

  6. Metabolic and transcriptomic changes induced in Arabidopsis by the rhizobacterium Pseudomonas fluorescens SS101.

    Science.gov (United States)

    van de Mortel, Judith E; de Vos, Ric C H; Dekkers, Ester; Pineda, Ana; Guillod, Leandre; Bouwmeester, Klaas; van Loon, Joop J A; Dicke, Marcel; Raaijmakers, Jos M

    2012-12-01

    Systemic resistance induced in plants by nonpathogenic rhizobacteria is typically effective against multiple pathogens. Here, we show that root-colonizing Pseudomonas fluorescens strain SS101 (Pf.SS101) enhanced resistance in Arabidopsis (Arabidopsis thaliana) against several bacterial pathogens, including Pseudomonas syringae pv tomato (Pst) and the insect pest Spodoptera exigua. Transcriptomic analysis and bioassays with specific Arabidopsis mutants revealed that, unlike many other rhizobacteria, the Pf.SS101-induced resistance response to Pst is dependent on salicylic acid signaling and not on jasmonic acid and ethylene signaling. Genome-wide transcriptomic and untargeted metabolomic analyses showed that in roots and leaves of Arabidopsis plants treated with Pf.SS101, approximately 1,910 genes and 50 metabolites were differentially regulated relative to untreated plants. Integration of both sets of "omics" data pointed to a prominent role of camalexin and glucosinolates in the Pf.SS101-induced resistance response. Subsequent bioassays with seven Arabidopsis mutants (myb51, cyp79B2cyp79B3, cyp81F2, pen2, cyp71A12, cyp71A13, and myb28myb29) disrupted in the biosynthesis pathways for these plant secondary metabolites showed that camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf.SS101. Also for the insect S. exigua, the indolic glucosinolates appeared to play a role in the Pf.SS101-induced resistance response. This study provides, to our knowledge for the first time, insight into the substantial biochemical and temporal transcriptional changes in Arabidopsis associated with the salicylic acid-dependent resistance response induced by specific rhizobacteria.

  7. Characterization and expression in Escherichia coli of an endoglucanase gene of Pseudomonas fluorescens subsp. cellulosa.

    Science.gov (United States)

    Lejeune, A; Dartois, V; Colson, C

    1988-07-13

    An endoglucanase gene of Pseudomonas fluorescens subsp. cellulosa present on plasmid pRUCL150 and expressed in Escherichia coli was subcloned in plasmid pBR322. Plasmid pRUCL153 contained the smallest DNA insert (2.9 kb) with endoglucanase activity. The plasmids directed the synthesis of a mostly periplasmic enzyme in E. coli and the level of enzyme activity was comparable in several strains. Analysis by non-denaturing polyacrylamide gel electrophoresis of the endoglucanase produced with various recombinant plasmids showed that it was unique. The endoglucanase gene on plasmid pRUCL153 was localized by physical mapping of independent transposon Tn5 insertions. Hence, its size was estimated to be approx. 1.3 kb. In vivo radioactive labelling of plasmid-encoded proteins using minicells, followed by denaturing polyacrylamide gel electrophoresis, allowed us to determine the size of the endoglucanase: Mr 40,000 for the precursor and Mr 38,000 for the mature enzyme. It was demonstrated that no cellulase operon, but a single gene, was cloned. The direction of transcription of the gene was determined by placing it under the control of the promoter of the lactose operon.

  8. Influence of mineral amendment on disease suppressive activity of Pseudomonas fluorescens to Fusarium wilt of chickpea.

    Science.gov (United States)

    Saikia, Ratul; Varghese, Saju; Singh, Bhim Pratap; Arora, Dilip K

    2009-01-01

    Fusarium wilt caused by Fusarium oxysporum f. sp. ciceri causes considerable yield loss of chickpea. Pseudomonas fluorescens4-92 (Pf4-92) strain can suppress the disease. Amendment of zinc EDTA and copper EDTA could not suppress the disease significantly when used alone; however, they significantly suppressed the disease in presence of Pf4-92. In vitro observation showed that at 40, 30 and 20microgml(-1) concentrations of these minerals, i.e. Zn, Cu and Zn plus Cu, respectively, completely repressed the production of the phytotoxin, fusaric acid (FA). FA concentration (0.5microgml(-1)) has been shown to suppress the production of 2,4-diacetylphloroglucinol (DAPG) by Pf4-92, and DAPG, salicylic acid, pyochelin and pyoluteorin production was enhanced by these mineral amendments. In rockwool bioassays, Zn, Cu and Zn plus Cu amendments reduced FA production and enhanced DAPG production. This study demonstrates that Zn and Cu enhance biocontrol activity by reducing FA produced by the pathogen, F. oxysporum f. sp. ciceri.

  9. Colonisation of Pinus halepensis roots by Pseudomonas fluorescens and interaction with the ectomycorrhizal fungus Suillus granulatus.

    Science.gov (United States)

    Rincón, Ana; Ruiz-Díez, Beatriz; García-Fraile, Sonia; García, José Antonio Lucas; Fernández-Pascual, Mercedes; Pueyo, José J; de Felipe, María R

    2005-02-01

    Colonisation of Pinus halepensis roots by GFP-tagged Pseudomonas fluorescens Aur6 was monitored by epifluorescence microscopy and dilution plating. Aur6-GFP was able to colonise and proliferate on P. halepensis roots. Co-inoculation with the ectomycorrhizal fungus Suillus granulatus did not affect the bacterial colonisation pattern whereas it had an effect on bacterial density. Bacterial counts increased during the first 20 days of seedling growth, irrespective of seedlings being mycorrhizal or not. After 40 days, bacterial density significantly decreased and bacteria concentrated on the upper two-thirds of the pine root. The presence of S. granulatus significantly stimulated survival of bacteria in the root elongation zone where fungal colonisation was higher. The number of mycorrhizas formed by S. granulatus was not affected by co-inoculation with Aur6-GFP. Neither Aur6-GFP nor S. granulatus stimulated P. halepensis development when inoculated alone, but a synergistic effect was observed on seedling growth when bacteria and fungus were co-inoculated.

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

    Science.gov (United States)

    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.

  11. Cheating and resistance to cheating in natural populations of the bacterium Pseudomonas fluorescens.

    Science.gov (United States)

    Bruce, John B; Cooper, Guy A; Chabas, Hélène; West, Stuart A; Griffin, Ashleigh S

    2017-10-01

    Bacteria perform cooperative behaviors that are exploitable by noncooperative cheats, and cheats frequently arise and coexist with cooperators in laboratory microcosms. However, evidence of competitive dynamics between cooperators and cheats in nature remains limited. Using the production of pyoverdine, an iron-scavenging molecule, and natural soil populations of Pseudomonas fluorescens, we found that (1) nonproducers are present in the population; (2) they co-occur (cheats in soil: utilizing the pyoverdine of others while producing little or none themselves. However, we found considerable variation in the extent to which nonproducers can exploit producers, as some isolates appear to produce exclusive forms of pyoverdine or kill nonproducers with toxins. We examined the consequences of this variation using theoretical modeling. We found variance in exploitability leads to some cheats gaining increased fitness benefits and others decreased benefits. However, the absolute gain in fitness from high exploitation is lower than the drop in fitness from low exploitation, decreasing the mean fitness of cheats and subsequently lowering the proportion of cheats maintained in the population. Our results suggest that although cooperator-cheat dynamics can occur in soil, a range of mechanisms can prevent nonproducers from exploiting producers. © 2017 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  12. Pseudomonas fluorescens R68 assisted enhancement in growth and fertilizer utilization of Amaranthus tricolor (L.).

    Science.gov (United States)

    Jimtha John, C; Jishma, P; Karthika, N R; Nidheesh, K S; Ray, J G; Mathew, Jyothis; Radhakrishnan, E K

    2017-08-01

    Plant probiotic potential of rhizosphere microbiome and its role in phytofertilizer mobilization are largely unexplored. In the current study, the rhizobacterium Pseudomonas fluorescens R68 (PFR68) isolated from Western Ghat was analyzed for its growth enhancement effect on the leafy vegetable Amaranthus tricolor (L.). One month of field growth of PFR68 inoculated A. tricolor has found to have enhanced growth parameters such as leaf number (1.57 fold), root number (1.76 fold), shoot length (1.28 fold) and fresh weight (2.31 fold). The treatment also improved soil fertility in terms of Nitrogen, Phosphorus and Potassium content. Most remarkably, application of PFR68 alone and 50% of recommended NPK dose along with PFR68 has resulted in enhanced growth of A. tricolor comparable to plants treated with full dose of NPK. In addition to this, application of PFR68 along with 50% NPK augmented the available Nitrogen and Phosphorus content in soil. This indicates the potential of selected organism in enrichment of soil health and enhancement of crop productivity. In conclusion, field performance of PFR68 on growth of A. tricolor confirms its promises to develop into plant probiotic formulation.

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

    Science.gov (United States)

    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

  14. Pit formation on stainless steel surfaces pre-treated with biosurfactants produced by Pseudomonas fluorescens

    Energy Technology Data Exchange (ETDEWEB)

    Dagbert, Catherine [ECP-LGPM, Grande Voie des Vignes, 92295 Chatenay-Malabry (France)], E-mail: catherine.dagbert@ecp.fr; Meylheuc, Thierry; Bellon-Fontaine, Marie-Noelle [INRA, UMR 763 Bioadhesion et Hygiene des Materiaux, F-91300 Massy (France); AGROPARISTECH, UMR 763 Bioadhesion et Hygiene des Materiaux, F-91300 Massy (France)

    2008-12-01

    Today, it is widely established that the surface tension of water can be reduced by some microorganisms capable of synthesizing surface-active compounds called biosurfactants (BS). BS characteristics depend on the microorganism that produces them and therefore, on the microorganism culture conditions. Some studies on chemical surfactants have shown that the adsorption of surface-active compounds plays a major role in corrosion; indeed they are used as a good corrosion inhibition tool. The purpose of this study was first, to estimate the importance and behavior of the stainless steels passive film on the adsorption of BS, produced by the Gram negative bacteria Pseudomonas fluorescens, and secondly, to study the impact of these treatments on the pitting corrosion. In this paper, the galvanostatic polarization technique, used as accelerated method for determining the characteristic pit potentials on stainless steels, is examined. Pit growth, shape and cover formation were also observed. The surface topography of the corroded specimens was investigated using field emission scanning electron microscopy (FESEM)

  15. Correlation of Carbohydrate Catabolism and Synthesis of Macromolecules During Enzyme Synthesis in Pseudomonas fluorescens.

    Science.gov (United States)

    Kirkland, J J; Durham, N N

    1965-07-01

    Kirkland, Jerry J. (Oklahoma State University, Stillwater), and Norman N. Durham. Correlation of carbohydrate catabolism and synthesis of macromolecules during enzyme synthesis in Pseudomonas fluorescens. J. Bacteriol. 90: 23-28. 1965.-Glucose, ribose, and fructose shorten the lag period required for synthesis of protocatechuate oxygenase. Radioactivity from uracil-2-C(14) is incorporated into the hot trichloroacetic acid-soluble fraction after a lag period of approximately 20 min after addition of protocatechuic acid. Addition of glucose or ribose simultaneously with the inducer shortens the lag period to approximately 5 min and increases the rate of uracil incorporation. The inducer must be present to initiate incorporation of radioactivity, and the exogenous carbon source accelerates incorporation but is not sufficient to initiate synthesis by itself. The addition of protocatechuic acid increases the rate and total incorporation of radioactivity from uniformly labeled glucose or ribose-1-C(14) into the hot trichloroacetic acid-soluble fraction. Ribose decreases the incorporation of radioactivity from uniformly labeled glucose into the hot trichloroacetic acid-soluble fraction, and glucose shows a similar effect on incorporation of radioactivity from ribose-1-C(14), indicating the two sugars are serving in the same capacity to enhance enzyme synthesis. Radioactivity from glucose-1-C(14) is not incorporated into the hot trichloroacetic acid-soluble fraction. The results suggest that glucose and ribose shorten the lag period for inducible enzyme formation by serving as a "specific" carbon source for synthesis of macromolecules such as ribonucleic acid.

  16. Adhesion of Pseudomonas fluorescens biofilms to glass, stainless steel and cellulose.

    Science.gov (United States)

    Wan Dagang, W R Z; Bowen, J; O'Keeffe, J; Robbins, P T; Zhang, Z

    2016-05-01

    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. 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). 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.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2009-12-11

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

  19. Characterization of a Pseudomonas fluorescens strain from tomato rhizosphere and its use for integrated management of tomato damping-off

    Energy Technology Data Exchange (ETDEWEB)

    Jayaraj, J; Parthasarathi, T.; Radhakrishnan, N.V. [Annamalai University, Annamalainagar (India). Faculty of Agriculture

    2007-10-15

    A highly antagonistic Pseudomonas fluorescens strain was isolated from tomato rhizosphere and characterized for its in vitro and in vivo biocontrol potential against Pythium aphanidermatum. The identified Pseudomonas fluorescens strain (PfT-8) was capable of producing high levels of chitinase, beta-1,3-glucanase, cellulase, fungitoxic metabolites and siderophores. Seven different carrier formulations including a talc-based powder, lignite-based powder, peat-based powder, lignite + fly ash-based powder, wettable powder, bentonite-paste and polyethylene glycol (PEG) paste were prepared utilizing PfT-8. Shelf life was evaluated for up to 6 months of storage at ambient room temperature (28{sup o}C). Biocontrol efficacy of formulations was studied under greenhouse and field conditions. Among the formulations, peat, lignite, lignite+fly-ash and bentonite paste based formulations maintained higher propagule number than others and also showed greater biocontrol potential. However, propagule number gradually decreased with time. Soil incorporation of organic amendments and specifically poultry manure and FYM, significantly reduced damping-off incidence and also augmented the rhizosphere population of the marked P. fluorescens strain that was resistant to streptomycin and rifampicin.

  20. Combinatorial efficacy of Trichoderma spp. and Pseudomonas fluorescens to enhance suppression of cell wall degrading enzymes produced by Fusarium wilt of Arachis hypogaea.L

    Directory of Open Access Journals (Sweden)

    P Rajeswari

    2017-12-01

    Full Text Available Fusarium oxysporum, the soil borne pathogen causes vascular wilt, on majority of crop plants. It has been demonstrated that two different species of Trichoderma and Pseudomonas fluorescens suppress disease by different mechanisms. Therefore, application of a mixture of these biocontrol agents, and thus of several suppressive mechanisms, may represent a viable control strategy. A necessity for biocontrol by combinations of biocontrol agents can be the compatibility of the co-inoculated micro-organisms. Hence, compatibility between Trichoderma spp. and Pseudomonas fluorescens that have the ability to suppress Fusarium oxysporum in vitro on the activity of pectinolytic enzymes of Fusarium oxysporum. The activity of pectinolytic enzymes, i.e. pectin methyl esterase, endo and exo polymethylgalacturonases and exo and endo pectin trans eliminases produced by Fusarium oxysporum (Control was higher. Maximum inhibition of pectin methylesterase, exo and endo polymethylgalacturonase and exo and endopectin trans eliminase was shown by culture filtrate of Trichoderma viride + Pseudomonas fluorescens (Tv+Pf (1+2%, followed by Trichoderma harzianum + Pseudomonas fluorescens, (Th +Pf (1.5+2% and Trichoderma viride + Trichoderma harzianum (Tv+Th (1+1.5%. However, pathogenecity suppression of Fusarium oxysporum, a causative of Arachis hypogaea. L by the compatible combination of Trichodema viride + Pseudomonas fluorescens (1+2% was significantly better as compared to the single bio-agent. This indicates that specific interactions between biocontrol agents influence suppression of pathogenicity factors directly by combinations of these compatible bio-agents.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Gary S. Sayler

    2012-02-01

    Full Text Available 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.

  3. Control biológico de Rhizoctonia solani en plantas de papa criollaSolanum phureja usando cepas nativas de Pseudomonas fluorescens BIOCONTROL OF Rhizoctonia solani IN NATIVE POTATO (Solanum phureja PLANTS USING NATIVE Pseudomonas fluorescens

    Directory of Open Access Journals (Sweden)

    GLORIA BAUTISTA

    2007-06-01

    Full Text Available Rhizoctonia solani es un hongo fitopatógeno del suelo, el cual produce una reducción significativa del vigor de las plantas y de la producción de tubérculos en cultivos de papa. Es de gran interés la búsqueda de alternativas de manejo de esta enfermedad, especialmente desde la perspectiva de control biológico ya que los cultivos de papa son los mayores consumidores de plaguicidas de origen químicos en Colombia. Con el objeto de obtener una cepa del grupo de las Pseudomonas fluorescentes con la capacidad para reducir los síntomas de la enfermedad producidos por R. solani, se realizó en un estudio previo el aislamiento y caracterización de una colección de aislamientos de Pseudomonas fluorescentes provenientes de diferentes cultivos de la región papera más productiva del país. Seis cepas nativas de P. fluorescens con buena, moderada o ninguna capacidad para inhibir el crecimiento fúngico in vitro fueron seleccionadas. A pesar de las diferencias encontradas en términos de la dinámica y capacidad de colonización, todas las cepas evaluadas indujeron el crecimiento en las plantas de S. phureja y redujeron los síntomas de la enfermedad producidos por R. solani a nivel de invernadero. Nuestros resultados sustentan la conclusión que la asociación de cepas de P. fluorescens con la rizosfera de S. phureja es una alternativa para el manejo de R. solani en papa.Rhizoctonia solani is a soil borne phytopathogen associated with reduced plant vigor and tuber production in potato crops. There is a huge interest to search alternatives of biological control management of this disease, because the potato crops in Colombia are the highest consumers of chemical pesticides in Colombia. In order to obtain a fluorescent Pseudomonas strain with the capacity to reduce the disease symptoms produced by R. solani, determination and isolation of the predominant fluorescent Pseudomonas in several potato crops of the main Colombian producing region was done

  4. Pemanfaatan Beberapa Kaldu Hewan sebagai Bahan Formula Cair Pseudomonas fluorescens P60 untuk Mengendalikan Sclerotium rolfsii pada Tanaman Mentimun

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    Endang Mugiastuti

    2011-07-01

    Full Text Available A research aiming at knowing the potency of several animal broths as organic liquid formula of Pseudomonas fluorescens P60, soaking period of Sclerotium rolfsii sclerotia, and its application method on cucumber stem-end rot was done. Completely randomized design and randomized block design both arranged by factorial were used for in vitro and in planta tests, respectively. The first factor was six kinds of animal broth, i.e., golden snail, local chicken,broiler chicken, catfish, cow bone, and rat. The second one for in vitro test was the soaking period in the Pseudomonas fluorescens P60 formula, i.e., 0, 1, 10, and 100 hours and for in planta one was application methods, i.e., seed soaking or crop spraying. Result of the research showed that the best animal broth as liquid formula for Pseudomonas fluorescens P60 was golden snail broth indicated by suppression of sclerotial germination up to 97.4% after soaking for 100 hours. The best application method to suppress the disease was spraying method showed by suppressed of sclerotial germination, longer incubation period, and suppressed disease incidence and sclerotial late population of 55.79, 147.35, 66.67, and 59.68%, repectively. Spraying the formula could also increase crop height difference, fresh and dry weight of crop, fresh and dry weight of root, and root length to 146.83, 86.62, 112.5, 87.88, 140, and 159.68%, respectively. Penelitian dengan tujuan untuk mengetahui potensi beberapa kaldu hewan sebagai formula cair organik Pseudomonas fluorescens P60, lama perendaman sklerotium Sclerotium rolfsii, dan cara aplikasinya terhadap penyakit busuk pangkal batang mentimun dilakukan. Rancangan acak lengkap faktorial dan rancangan acak kelompok faktorial digunakan dalam penelitian in vitro dan in planta. Faktor pertama yang diuji adalah enam jenis kaldu yang terdiri atas kaldu keong mas, ayam kampung, ayam potong, ikan lele, tulang sapi, dan tikus. Faktor kedua pada penelitian in vitro adalah lama

  5. Biocontrol of collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii by using rhizosphere-competent Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N.

    Science.gov (United States)

    Singh, Anand; Mehta, Sangeeta; Singh, Harikesh Bahadur; Nautiyal, Chandra Shekhar

    2003-08-01

    Collar rot disease of betelvine (Piper betle L.) caused by Sclerotium rolfsii is difficult to control by conventional means by use of chemicals; therefore, use of biocontrol agents is desirable. In the present study, 186 bacterial strains of different morphological types were screened for their biocontrol activity against S. rolfsii under in vitro conditions. Two strains, Pseudomonas fluorescens NBRI-N6 and P. fluorescens NBRI-N, were selected for further studies because of their ability to inhibit the mycelial growth of the pathogen significantly. Spontaneous rifampicin-resistant (Rif) derivatives of P. fluorescens NBRI-N6 and P. fluorescens NBRI-N showing growth rate and membrane protein composition comparable to the wild type were selected to facilitate their monitoring in the rhizosphere. Field trials demonstrated that strain P. fluorescens NBRI-N6 was better than P. fluorescens NBRI-N in increasing the yield of betelvine significantly, whereas a consortium of the two strains controlled the disease more than either of the strains. The screening method should prove useful in identifying rhizosphere bacteria with the greatest potential for controlling diseases caused by phytopathogenic fungi.

  6. Pyrroloquinoline Quinone Is a Plant Growth Promotion Factor Produced by Pseudomonas fluorescens B161

    Science.gov (United States)

    Choi, Okhee; Kim, Jinwoo; Kim, Jung-Gun; Jeong, Yeonhwa; Moon, Jae Sun; Park, Chang Seuk; Hwang, Ingyu

    2008-01-01

    Pseudomonas fluorescens B16 is a plant growth-promoting rhizobacterium. To determine the factors involved in plant growth promotion by this organism, we mutagenized wild-type strain B16 using ΩKm elements and isolated one mutant, K818, which is defective in plant growth promotion, in a rockwool culture system. A cosmid clone, pOK40, which complements the mutant K818, was isolated from a genomic library of the parent strain. Tn3-gusA mutagenesis of pOK40 revealed that the genes responsible for plant growth promotion reside in a 13.3-kb BamHI fragment. Analysis of the DNA sequence of the fragment identified 11 putative open reading frames, consisting of seven known and four previously unidentified pyrroloquinoline quinone (PQQ) biosynthetic genes. All of the pqq genes showed expression only in nutrient-limiting conditions in a PqqH-dependent manner. Electrospray ionization-mass spectrometry analysis of culture filtrates confirmed that wild-type B16 produces PQQ, whereas mutants defective in plant growth promotion do not. Application of wild-type B16 on tomato (Solanum lycopersicum) plants cultivated in a hydroponic culture system significantly increased the height, flower number, fruit number, and total fruit weight, whereas none of the strains that did not produce PQQ promoted tomato growth. Furthermore, 5 to 1,000 nm of synthetic PQQ conferred a significant increase in the fresh weight of cucumber (Cucumis sativus) seedlings, confirming that PQQ is a plant growth promotion factor. Treatment of cucumber leaf discs with PQQ and wild-type B16 resulted in the scavenging of reactive oxygen species and hydrogen peroxide, suggesting that PQQ acts as an antioxidant in plants. PMID:18055583

  7. Pyrroloquinoline quinone is a plant growth promotion factor produced by Pseudomonas fluorescens B16.

    Science.gov (United States)

    Choi, Okhee; Kim, Jinwoo; Kim, Jung-Gun; Jeong, Yeonhwa; Moon, Jae Sun; Park, Chang Seuk; Hwang, Ingyu

    2008-02-01

    Pseudomonas fluorescens B16 is a plant growth-promoting rhizobacterium. To determine the factors involved in plant growth promotion by this organism, we mutagenized wild-type strain B16 using OmegaKm elements and isolated one mutant, K818, which is defective in plant growth promotion, in a rockwool culture system. A cosmid clone, pOK40, which complements the mutant K818, was isolated from a genomic library of the parent strain. Tn3-gusA mutagenesis of pOK40 revealed that the genes responsible for plant growth promotion reside in a 13.3-kb BamHI fragment. Analysis of the DNA sequence of the fragment identified 11 putative open reading frames, consisting of seven known and four previously unidentified pyrroloquinoline quinone (PQQ) biosynthetic genes. All of the pqq genes showed expression only in nutrient-limiting conditions in a PqqH-dependent manner. Electrospray ionization-mass spectrometry analysis of culture filtrates confirmed that wild-type B16 produces PQQ, whereas mutants defective in plant growth promotion do not. Application of wild-type B16 on tomato (Solanum lycopersicum) plants cultivated in a hydroponic culture system significantly increased the height, flower number, fruit number, and total fruit weight, whereas none of the strains that did not produce PQQ promoted tomato growth. Furthermore, 5 to 1,000 nm of synthetic PQQ conferred a significant increase in the fresh weight of cucumber (Cucumis sativus) seedlings, confirming that PQQ is a plant growth promotion factor. Treatment of cucumber leaf discs with PQQ and wild-type B16 resulted in the scavenging of reactive oxygen species and hydrogen peroxide, suggesting that PQQ acts as an antioxidant in plants.

  8. Effect of exogenous ectoines on some antifungal activity of Pseudomonas fluorescens UTPF5 under salt conditions

    Directory of Open Access Journals (Sweden)

    Arghavan Kamaly

    2016-06-01

    Full Text Available Introduction: Plant probiotic bacteria like fluorescent pseudomonads are worldly used against soil-borne pathogens through mechanisms such as production of bacterial metabolites and enzymes. These bacteria can also help plants to tolerate environmental stresses. Ectoine is a compatible solution which plays an important role in environmental osmotic stresses. Materials and methods: Tolerance of 24 bacterial strains to salt and heat was tested and 6 tolerant strains were chosen. Then dual culture of Fusarium solani and bacteria grown in presence of ectoine and hydroxy ectoine with 3 NaCl concentrations (0, 150 and 300 mM was done and Pseudomonas fluorescens UTPF5 was selected. Finally the effect of ectoine, hydroxyectoine and NaCl on bacterial population, lipase, protease, siderophore and hydrogen-cyanide production and biofilm formation was investigated. Results: In 300 mM NaCl, the bacterium grown in presence of ectoines, increased the inhibition percentage 5- times more than control. NaCl had a positive effect on bacterial population in water and ectoine, hydrogen-cyanide production in all treatment and biofilm formation in ectoine and hydroxyectoine and negative effect on bacterial population in hydroxyectoine, protease and siderophore production in all treatments and biofilm formation in water. On the other hand, ectoine increased lipase and hydrogen-cyanide production and biofilm formation in 300 mM NaCl and siderophore production in 150 mM. Hydroxyectoine had similar effects with little differences. Discussion and conclusion: Ectoine and hydroxyectoine moderate the biocontrol reduction in presence of NaCl through positive effect on lipase and hydrogen-cyanide production and biofilm formation.

  9. Cost of Adaptation and Fitness Effects of Beneficial Mutations in Pseudomonas fluorescens

    Science.gov (United States)

    Bataillon, Thomas; Zhang, Tianyi; Kassen, Rees

    2011-01-01

    Adaptations are constructed through the sequential substitution of beneficial mutations by natural selection. However, the rarity of beneficial mutations has precluded efforts to describe even their most basic properties. Do beneficial mutations typically confer small or large fitness gains? Are their fitness effects environment specific, or are they broadly beneficial across a range of environments? To answer these questions, we used two subsets (n = 18 and n = 63) of a large library of mutants carrying antibiotic resistance mutations in the bacterium Pseudomonas fluorescens whose fitness, along with the antibiotic sensitive ancestor, was assayed across 95 novel environments differing in the carbon source available for growth. We explore patterns of genotype-by-environment (G×E) interactions and ecological specialization among the 18 mutants initially found superior to the sensitive ancestor in one environment. We find that G×E is remarkably similar between the two sets of mutants and that beneficial mutants are not typically associated with large costs of adaptation. Fitness effects among beneficial mutants depart from a strict exponential distribution: they assume a variety of shapes that are often roughly L shaped but always right truncated. Distributions of (beneficial) fitness effects predicted by a landscape model assuming multiple traits underlying fitness and a single optimum often provide a good description of the empirical distributions in our data. Simulations of data sets containing a mixture of single and double mutants under this landscape show that inferences about the distribution of fitness effects of beneficial mutants is quite robust to contamination by second-site mutations. PMID:21868607

  10. Biosurfactant production by Pseudomonas fluorescens growing on molasses and its application in phenol degradation

    Science.gov (United States)

    Suryantia, Venty; Marliyana, Soerya Dewi; Wulandari, Astri

    2015-12-01

    A molasses based medium for the biosurfactant production by Pseudomonas fluorescens was developed, where the effect of pre-treated of molasses and medium composition were evaluated. Biosurfactant production was followed by measuring optical density (OD), surface tension and emulsifying index (E24) over 12 days of fermentation. The optimum condition for the biosurfactant production was obtained when a medium containing of 8 g/L nutrient broth, 5 g/L NaCl, 1 g/L NH4NO3 and 5% v/v pre-treated molasses with centrifugation was used as media with 3 days of fermentation. The biosurfactant was identified as a rhamnolipid type biosurfactant which had critical micelle concentration (CMC) value of 801 mg/L and was able to reduce the surface tension of the water from 80 mN/m to 51 mN/m. The biosurfactants had water in oil (w/o) emulsion type. Biosurfactant was able to emulsify various hydrocarbons, which were able to decrase the interfacial tension about 50-75% when benzyl chloride, anisaldehyde and palm oil were used as immiscible compounds. The biosurfactant exhibited the E24 value of about 50% and the stable emulsion was reached up to 30 days when lubricant was used as an immiscible compound. Up to 68% of phenol was degraded in the presence of biosurfactant within 15 days, whereas only 56% of phenol was degraded in the absence of biosurfactant. Overall, the results exhibited that molasses are recommended for the rhamnolipids production which possessed good surface-active properties and had potential application in the enhancement of phenol degradation.

  11. Chemotactic Motility of Pseudomonas fluorescens F113 under Aerobic and Denitrification Conditions.

    Directory of Open Access Journals (Sweden)

    Candela Muriel

    Full Text Available The sequence of the genome of Pseudomonas fluorescens F113 has shown the presence of multiple traits relevant for rhizosphere colonization and plant growth promotion. Among these traits are denitrification and chemotactic motility. Besides aerobic growth, F113 is able to grow anaerobically using nitrate and nitrite as final electron acceptors. F113 is able to perform swimming motility under aerobic conditions and under anaerobic conditions when nitrate is used as the electron acceptor. However, nitrite can not support swimming motility. Regulation of swimming motility is similar under aerobic and anaerobic conditions, since mutants that are hypermotile under aerobic conditions, such as gacS, sadB, kinB, algU and wspR, are also hypermotile under anaerobic conditions. However, chemotactic behavior is different under aerobic and denitrification conditions. Unlike most pseudomonads, the F113 genome encode three complete chemotaxis systems, Che1, Che2 and Che3. Mutations in each of the cheA genes of the three Che systems has shown that the three systems are functional and independent. Mutation of the cheA1 gene completely abolished swimming motility both under aerobic and denitrification conditions. Mutation of the cheA2 gene, showed only a decrease in swimming motility under both conditions, indicating that this system is not essential for chemotactic motility but is necessary for optimal motility. Mutation of the cheA3 gene abolished motility under denitrification conditions but only produced a decrease in motility under aerobic conditions. The three Che systems proved to be implicated in competitive rhizosphere colonization, being the cheA1 mutant the most affected.

  12. Extracellular Protease of Pseudomonas fluorescens CHA0, a Biocontrol Factor with Activity against the Root-Knot Nematode Meloidogyne incognita

    OpenAIRE

    Siddiqui, Imran Ali; Haas, Dieter; Heeb, Stephan

    2005-01-01

    In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocon...

  13. Estrategias de identificación de genes de proteasas en una cepa de pseudomonas fluorescens alterante de leche

    OpenAIRE

    Rodrigo Torres, Lidia

    2013-01-01

    La leche es un alimento muy completo nutricionalmente y por ello fácilmente alterable por microorganismos si no se adoptan unas medidas de higiene adecuadas. El análisis de un lote de leche esterilizada comercial alterada reveló la presencia de una cepa de Pseudomonas fluorescens con actividad proteolítica y lipolítica. El objetivo de este trabajo fue diseñar oligonucleótidos y utilizar la técnica de amplificación por PCR (Polymerase Chain Reaction), seguida de secuenciación o de clonación...

  14. Isolation and characterization of antimicrobial cyclic dipeptides from Pseudomonas fluorescens and their efficacy on sorghum grain mold fungi.

    Science.gov (United States)

    Sajeli Begum, Ahil; Basha, Shaik Ameer; Raghavendra, Govardhanam; Kumar, Mallela Venkata Nagesh; Singh, Yukthi; Patil, Jagannath V; Tanemura, Yuhei; Fujimoto, Yoshinori

    2014-01-01

    This study was aimed at isolation and characterization of natural antifungal compounds for grain mold, a key parasitic fungal disease of sorghum. Pseudomonas fluorescens strain isolated from rhizosphere of groundnut crop was selected as a source. Its biocontrolling ability was assessed by testing some biochemical attributes such as phosphate-solubilization, and HCN, NH3 , indole-3-acetic acid, and siderophore production. The strain showed positive result for all except indole-3-acetic acid, revealing its suitability for a further study. The antibiotic-sensitivity pattern of the strain against 43 antibiotics was also established, which showed resistance to 15 antibiotics. The efficacy of P. fluorescens strain against grain mold was identified by dual culture technique. Hundred percent inhibition was found against Fusarium moniliforme, an important causative agent of this disease. The strain was fermented for secondary metabolites and extracted with AcOEt. Chromatographic separation of the extract yielded four known compounds, cyclo(L-Pro-L-Phe) (1), cyclo(trans-4-hydroxy-L-Pro-L-Leu) (2), cyclo(trans-4-hydroxy-L-Pro-L-Phe) (3), and cyclo(Gly-L-Pro) (4), which were characterized by spectral analysis and optical rotation. The crude extract, a mixture of 2 and 3, and isolated 1 were proved to be significantly effective against grain mold fungi. This is the first report on production of these cyclic dipeptides by P. fluorescens and their antagonistic properties. Copyright © 2014 Verlag Helvetica Chimica Acta AG, Zürich.

  15. Pseudomonas fluorescens induces strain-dependent and strain-independent host plant responses in defense networks, primary metabolism and photosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Pelletier, Dale A [ORNL; Morrell-Falvey, Jennifer L [ORNL; Karve, Abhijit A [ORNL; Lu, Tse-Yuan S [ORNL; Tschaplinski, Timothy J [ORNL; Tuskan, Gerald A [ORNL; Chen, Jay [ORNL; Martin, Madhavi Z [ORNL; Jawdy, Sara [ORNL; Weston, David [ORNL; Doktycz, Mitchel John [ORNL; Schadt, Christopher Warren [ORNL

    2012-01-01

    Colonization of plants by nonpathogenic Pseudomonas fluorescens strains can confer enhanced defense capacity against a broad spectrum of pathogens. Few studies, however, have linked defense pathway regulation to primary metabolism and physiology. In this study, physiological data, metabolites, and transcript profiles are integrated to elucidate how molecular networks initiated at the root-microbe interface influence shoot metabolism and whole-plant performance. Experiments with Arabidopsis thaliana were performed using the newly identified P. fluorescens GM30 or P. fluorescens Pf-5 strains. Co-expression networks indicated that Pf-5 and GM30 induced a subnetwork specific to roots enriched for genes participating in RNA regulation, protein degradation, and hormonal metabolism. In contrast, only GM30 induced a subnetwork enriched for calcium signaling, sugar and nutrient signaling, and auxin metabolism, suggesting strain dependence in network architecture. In addition, one subnetwork present in shoots was enriched for genes in secondary metabolism, photosynthetic light reactions, and hormone metabolism. Metabolite analysis indicated that this network initiated changes in carbohydrate and amino acid metabolism. Consistent with this, we observed strain-specific responses in tryptophan and phenylalanine abundance. Both strains reduced host plant carbon gain and fitness, yet provided a clear fitness benefit when plants were challenged with the pathogen P. syringae DC3000.

  16. Pseudomonas fluorescens filamentous hemagglutinin, an iron-regulated protein, is an important virulence factor that modulates bacterial pathogenicity

    Directory of Open Access Journals (Sweden)

    Yuan-yuan Sun

    2016-08-01

    Full Text Available Pseudomonas fluorescens is a common bacterial pathogen to a wide range of aquaculture animals including various species of fish. In this study, we employed proteomic analysis and identified filamentous hemagglutinin (FHA as an iron-responsive protein secreted by TSS, a pathogenic P. fluorescens isolate. In vitro study showed that compared to the wild type, the fha mutant TSSfha (i exhibited a largely similar vegetative growth profile but significantly retarded in the ability of biofilm growth and producing extracellular matrix, (ii displayed no apparent flagella and motility, (iii was defective in the attachment to host cells and unable to form self-aggregation, (iv displayed markedly reduced capacity of hemagglutination and surviving in host serum. In vivo infection analysis revealed that TSSfha was significantly attenuated in the ability of dissemination in fish tissues and inducing host mortality, and that antibody blocking of the natural FHA produced by the wild type TSS impaired the infectivity of the pathogen. Furthermore, when introduced into turbot as a subunit vaccine, recombinant FHA elicited a significant protection against lethal TSS challenge. Taken together, these results indicate for the first time that P. fluorescens FHA is a key virulence factor essential to multiple biological processes associated with pathogenicity.

  17. Listeria monocytogenes Impact on Mature or Old Pseudomonas fluorescens Biofilms During Growth at 4 and 20°C.

    Science.gov (United States)

    Puga, Carmen H; Orgaz, Belen; SanJose, Carmen

    2016-01-01

    Changes in spatial organization, as observed by confocal laser scanning microscopy (CLSM), viable cell content, biovolume, and substratum surface coverage of the biofilms formed on glass by Pseudomonas fluorescens resulting from co-culture with Listeria monocytogenes, were examined. Two strains of L. monocytogenes, two culture temperatures and two biofilm developmental stages were investigated. Both L. monocytogenes strains, a persistently sampled isolate (collected repeatedly along 3 years from a meat factory) and Scott A, induced shrinkage in matrix volume, both at 20°C and 4°C, in mature or old biofilms, without loss of P. fluorescens cell count per surface unit. The nearly homogeneous pattern of surface coverage shown by mono-species P. fluorescens biofilms, turned into more irregular layouts in co-culture with L. monocytogenes. The upper layer of both mono and dual-species biofilms turned to predominantly consist of matrix, with plenty of viable cells underneath, in old biofilms cultured at 20°C, but not in those grown at 4°C. Between 15 and 56% of the substratum area was covered by biofilm, the extent depending on temperature, time and L. monocytogenes strain. Real biofilms in food-related surfaces may thus be very heterogeneous regarding their superficial components, i.e., those more accessible to disinfectants. It is therefore a hygienic challenge to choose an adequate agent to disrupt them.

  18. Phytohormone production and colonization of canola (Brassica napus L.) roots by Pseudomonas fluorescens 6-8 under gnotobiotic conditions.

    Science.gov (United States)

    Pallai, Rajash; Hynes, Russell K; Verma, Brij; Nelson, Louise M

    2012-02-01

    Pseudomonas fluorescens 6-8, a rhizosphere isolate previously shown to enhance root elongation of canola ( Brassica napus L.), was characterized for its ability to produce indole-3-acetic acid and cytokinins in pure culture and in the rhizosphere of canola under gnotobiotic conditions in comparison with the cytokinin-producing strain P. fluorescens G20-18 and its mutant CNT2. Strain 6-8 produced isopentenyl adenosine, zeatin riboside, and dihydroxyzeatin riboside at levels similar to those of G20-18, but only very low concentrations of indole-3-acetic acid. In a gnotobiotic assay canola inoculated with 6-8 and G20-18 had higher concentrations of isopentenyl adenosine and zeatin riboside in the rhizosphere and greater root length than the noninoculated control. The ability of strain 6-8 to colonize canola roots was assessed following transformation with the green fluorescent protein and inoculation onto canola seed in a gnotobiotic assay. Higher populations of strain 6-8 were observed on the proximal region of the root closest to the seed than on the mid and distal portions 9 days after seed inoculation. The ability of P. fluorescens 6-8 to produce cytokinins, colonize the roots of canola seedlings, and enhance root elongation may contribute to its ability to survive in the rhizosphere and may benefit seedling growth.

  19. On the role of metabolic activity on the transport und deposition of Pseudomonas fluorescens in saturated porous media.

    Science.gov (United States)

    Jansen, Sandra; Vereecken, Harry; Klumpp, Erwin

    2010-02-01

    A study was conducted to understand the role of cell concentration and metabolic state in the transport and deposition behaviour of Pseudomonas fluorescens with and without substrate addition. Column experiments using the short-pulse technique (pulse was equivalent to 0.028 pore volume) were performed in quartz sand operating under saturated conditions. For comparison, experiments with microspheres and inactive (killed) bacteria were also conducted. The effluent concentrations, the retained particle concentrations and the cell shape were determined by fluorescent microscopy. For the transport of metabolically-active P. fluorescens without substrate addition a bimodal breakthrough curve was observed, which could be explained by the different breakthrough behaviour of the rod-shaped and coccoidal cells of P. fluorescens. The 70:30 rod/coccoid ratio in the influent drastically changed during the transport and it was about 20:80 in the effluent and in the quartz sand packing. It was assumed that the active rod-shaped cells were subjected to shrinkage into coccoidal cells. The change from active rod-shaped cells to coccoidal cells could be explained by oxygen deficiency which occurs in column experiments under saturated conditions. Also the substrate addition led to two consecutive breakthrough peaks and to more bacteria being retained in the column. In general, the presence of substrate made the assumed stress effects more pronounced. In comparison to microspheres and inactive (killed) bacteria, the transport of metabolically-active bacteria with and without substrate addition is affected by differences in physiological state between rod-shaped and the formed stress-resistant coccoidal cells of P. fluorescens. Copyright 2010 Elsevier Ltd. All rights reserved.

  20. A conformational landscape for alginate secretion across the outer membrane of Pseudomonas aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Jingquan [Trinity College, Dublin (Ireland); Rouse, Sarah L. [University of Oxford, South Parks Road, Oxford (United Kingdom); Li, Dianfan; Pye, Valerie E.; Vogeley, Lutz; Brinth, Alette R.; El Arnaout, Toufic [Trinity College, Dublin (Ireland); Whitney, John C.; Howell, P. Lynne [The Hospital for Sick Children, Toronto, Ontario (Canada); University of Toronto, Toronto, Ontario (Canada); Sansom, Mark S. P. [University of Oxford, South Parks Road, Oxford (United Kingdom); Caffrey, Martin, E-mail: martin.caffrey@tcd.ie [Trinity College, Dublin (Ireland)

    2014-08-01

    Crystal structures of the β-barrel porin AlgE reveal a mechanism whereby alginate is exported from P. aeruginosa for biofilm formation. The exopolysaccharide alginate is an important component of biofilms produced by Pseudomonas aeruginosa, a major pathogen that contributes to the demise of cystic fibrosis patients. Alginate exits the cell via the outer membrane porin AlgE. X-ray structures of several AlgE crystal forms are reported here. Whilst all share a common β-barrel constitution, they differ in the degree to which loops L2 and T8 are ordered. L2 and T8 have been identified as an extracellular gate (E-gate) and a periplasmic gate (P-gate), respectively, that reside on either side of an alginate-selectivity pore located midway through AlgE. Passage of alginate across the membrane is proposed to be regulated by the sequential opening and closing of the two gates. In one crystal form, the selectivity pore contains a bound citrate. Because citrate mimics the uronate monomers of alginate, its location is taken to highlight a route through AlgE taken by alginate as it crosses the pore. Docking and molecular-dynamics simulations support and extend the proposed transport mechanism. Specifically, the P-gate and E-gate are flexible and move between open and closed states. Citrate can leave the selectivity pore bidirectionally. Alginate docks stably in a linear conformation through the open pore. To translate across the pore, a force is required that presumably is provided by the alginate-synthesis machinery. Accessing the open pore is facilitated by complex formation between AlgE and the periplasmic protein AlgK. Alginate can thread through a continuous pore in the complex, suggesting that AlgK pre-orients newly synthesized exopolysaccharide for delivery to AlgE.

  1. One-step purification and characterization of alginate lyase from a clinical Pseudomonas aeruginosa with destructive activity on bacterial biofilm.

    Science.gov (United States)

    Ghadam, Parinaz; Akhlaghi, Fatemeh; Ali, Ahya Abdi

    2017-05-01

    Pseudomonas aeruginosa is a Gram-negative and aerobic rod bacterium that displays mucoid and non-mucoid phenotype. Mucoid strains secrete alginate, which is the main agent of biofilms in chronic P. aeruginosa infections, show high resistance to antibiotics; consequently, the biological disruption of mucoid P. aeruginosa biofilms is an attractive area of study for researchers. Alginate lyase gene (algl) is a member of alginate producing operon which by glycosidase activity produces primer for other enzymes in this cluster. Also this activity can destroy the extracellular alginate; therefore this enzyme participates in alginate production and destruction pathway. Alginate lyase causes detachment of a biofilm by reducing its adhesion to the surfaces, and increases phagocytosis and antibiotic susceptibility. In this study, alginate lyase was purified in just one step and its properties were investigated. The purification was done by affinity chromatography, analysed by SDS-PAGE, and its effect on P. aeruginosa biofilms was surveyed by micro titer plate assay and SEM. The substrate specificity of the enzyme was determined by PCR. Alginate lyase from isolate 48 was purified in one step. It is more thermally resistant than alginate lyase from Pseudomonas aeruginosa PAO1 and poly M, poly G and poly MG alginate were the substrate of this enzyme. Moreover, it has an eradication effect on biofilms from P. aeruginosa 48 and PAO1. In this study an alginate lyase with many characteristics suitable in medicine such as thermal stability, effective on poly M alginate, and bacterial biofilm destructive was introduced and purified.

  2. Cloning and expression of Pseudomonas fluorescens 26-2 lipase gene in Pichia pastoris and characterizing for transesterification.

    Science.gov (United States)

    Yang, Jiangke; Zhang, Bo; Yan, Yunjun

    2009-11-01

    Pseudomonas lipases are important biocatalysts widely used in a variety of industrial fields. An extracellular lipase gene lipA with 1,854-bp open reading frame was cloned from Pseudomonas fluorescens 26-2. The multialignment assay of the putative amino acid and the secondary structure prediction revealed this enzyme could be classified into the lipolytic subfamily I.3 and secreted via adenosine-triphosphate-binding cassette pathway. The lipA gene was integrated into Pichia pastoris GS115, and the methanol-inducible recombinants with Mut(S) and Mut(+) phenotypes were acquired. The characteristics and the transesterification capacity shown by this enzyme suggested it is a useful biocatalyst for biodiesel preparation.

  3. Identification of anthranilate and benzoate metabolic operons of Pseudomonas fluorescens and functional characterization of their promoter regions

    Directory of Open Access Journals (Sweden)

    Lee Vincent D

    2006-01-01

    Full Text Available Abstract Background In an effort to identify alternate recombinant gene expression systems in Pseudomonas fluorescens, we identified genes encoding two native metabolic pathways that were inducible with inexpensive compounds: the anthranilate operon (antABC and the benzoate operon (benABCD. Results The antABC and benABCD operons were identified by homology to the Acinetobacter sp. anthranilate operon and Pseudomonas putida benzoate operon, and were confirmed to be regulated by anthranilate or benzoate, respectively. Fusions of the putative promoter regions to the E. coli lacZ gene were constructed to confirm inducible gene expression. Each operon was found to be controlled by an AraC family transcriptional activator, located immediately upstream of the first structural gene in each respective operon (antR or benR. Conclusion We have found the anthranilate and benzoate promoters to be useful for tightly controlling recombinant gene expression at both small (

  4. Comparative study on the in vitro effects of Pseudomonas aeruginosa and seaweed alginates on human gut microbiota.

    Directory of Open Access Journals (Sweden)

    Shaofeng Bai

    Full Text Available Alginates pertain to organic polysaccharides that have been extensively used in food- and medicine-related industries. The present study obtained alginates from an alginate overproducing Pseudomonas aeruginosa PAO1 mutant by screening transposon mutagenesis libraries. The interaction between bacterial and seaweed alginates and gut microbiota were further studied by using an in vitro batch fermentation system. Thin-layer chromatography (TLC analysis indicated that both bacterial and seaweed alginates can be completely degraded by fecal bacteria isolated from study volunteers, indicating that a minor structural difference between bacterial and seaweed alginates (O-acetylation and lack of G-G blocks didn't affect the digestion of alginates by human microbiota. Although, the digestion of bacterial and seaweed alginates was attributed to different Bacteroides xylanisolvens strains, they harbored similar alginate lyase genes. Genus Bacteroides with alginate-degrading capability were enriched in growth medium containing bacterial or seaweed alginates after in vitro fermentation. Short-chain fatty acid (SCFA production in both bacterial and seaweed alginates was also comparable, but was significantly higher than the same medium using starch. In summary, the present study has isolated an alginate-overproducing P. aeruginosa mutant strain. Both seaweed and bacterial alginates were degraded by human gut microbiota, and their regulatory function on gut microbiota was similar.

  5. Legionella pneumophila persists within biofilms formed by Klebsiella pneumoniae, Flavobacterium sp., and Pseudomonas fluorescens under dynamic flow conditions.

    Directory of Open Access Journals (Sweden)

    Catherine R Stewart

    Full Text Available Legionella pneumophila, the agent of Legionnaires' disease pneumonia, is transmitted to humans following the inhalation of contaminated water droplets. In aquatic systems, L. pneumophila survives much of time within multi-organismal biofilms. Therefore, we examined the ability of L. pneumophila (clinical isolate 130 b to persist within biofilms formed by various types of aquatic bacteria, using a bioreactor with flow, steel surfaces, and low-nutrient conditions. L. pneumophila was able to intercalate into and persist within a biofilm formed by Klebsiella pneumoniae, Flavobacterium sp. or Pseudomonas fluorescens. The levels of L. pneumophila within these biofilms were as much as 4 × 10(4 CFU per cm(2 of steel coupon and lasted for at least 12 days. These data document that K. pneumoniae, Flavobacterium sp., and P. fluorescens can promote the presence of L. pneumophila in dynamic biofilms. In contrast to these results, L. pneumophila 130 b did not persist within a biofilm formed by Pseudomonas aeruginosa, confirming that some bacteria are permissive for Legionella colonization whereas others are antagonistic. In addition to colonizing certain mono-species biofilms, L. pneumophila 130 b persisted within a two-species biofilm formed by K. pneumoniae and Flavobacterium sp. Interestingly, the legionellae were also able to colonize a two-species biofilm formed by K. pneumoniae and P. aeruginosa, demonstrating that a species that is permissive for L. pneumophila can override the inhibitory effect(s of a non-permissive species.

  6. Mutation rate, spectrum, topology, and context-dependency in the DNA mismatch repair-deficient Pseudomonas fluorescens ATCC948.

    Science.gov (United States)

    Long, Hongan; Sung, Way; Miller, Samuel F; Ackerman, Matthew S; Doak, Thomas G; Lynch, Michael

    2014-12-23

    High levels of genetic diversity exist among natural isolates of the bacterium Pseudomonas fluorescens, and are especially elevated around the replication terminus of the genome, where strain-specific genes are found. In an effort to understand the role of genetic variation in the evolution of Pseudomonas, we analyzed 31,106 base substitutions from 45 mutation accumulation lines of P. fluorescens ATCC948, naturally deficient for mismatch repair, yielding a base-substitution mutation rate of 2.34 × 10(-8) per site per generation (SE: 0.01 × 10(-8)) and a small-insertion-deletion mutation rate of 1.65 × 10(-9) per site per generation (SE: 0.03 × 10(-9)). We find that the spectrum of mutations in prophage regions, which often contain virulence factors and antibiotic resistance, is highly similar to that in the intergenic regions of the host genome. Our results show that the mutation rate varies around the chromosome, with the lowest mutation rate found near the origin of replication. Consistent with observations from other studies, we find that site-specific mutation rates are heavily influenced by the immediately flanking nucleotides, indicating that mutations are context dependent. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  7. Synthesis of silver nanoparticles by endosymbiont Pseudomonas fluorescens CA 417 and their bactericidal activity.

    Science.gov (United States)

    Syed, Baker; M N, Nagendra Prasad; B L, Dhananjaya; K, Mohan Kumar; S, Yallappa; S, Satish

    2016-12-01

    The present study emphasizes on biogenic synthesis of silver nanoparticles and their bactericidal activity against human and phytopathogens. Nanoparticle synthesis was performed using endosymbiont Pseudomonas fluorescens CA 417 inhabiting Coffea arabica L. Synthesized nanoparticles were characterized using hyphenated spectroscopic techniques such as UV-vis spectroscopy which revealed maximum absorption 425nm. Fourier transform infrared spectroscopy (FTIR) analysis revealed the possible functional groups mediating and stabilizing silver nanoparticles with predominant peaks occurring at 3346 corresponding to hydroxyl group, 1635 corresponding carbonyl group and 680 to aromatic group. X-ray diffraction (XRD) analysis revealed the Bragg's diffraction pattern with distinct peaks at 38° 44°, 64° and 78° revealing the face-centered cubic (fcc) metallic crystal corresponding to the (111), (200), (220) and (311) facets of the crystal planes at 2θ angle. The energy dispersive X-ray spectroscopy (EDS) analysis revealed presence of high intense absorption peak at 3keV is a typical characteristic of nano-crystalline silver which confirmed the presence of elemental silver. TEM analysis revealed the size of the nanoparticles to be in the range 5-50nm with polydisperse nature of synthesized nanoparticles bearing myriad shapes. The particle size determined by Dynamic light scattering (DLS) method revealed average size to be 20.66nm. The synthesized silver nanoparticles exhibited significant antibacterial activity against panel of test pathogens. The results showed Klebsiella pneumoniae (MTCC 7407) and Xanthomonas campestris to be more sensitive among the test human pathogen and phyto-pathogen respectively. The study also reports synergistic effect of silver nanoparticles in combination with kanamycin which displayed increased fold activity up to 58.3% against Klebsiella pneumoniae (MTCC 7407). The results of the present investigation are promising enough and attribute towards

  8. Structure Revision of N-Mercapto-4-formylcarbostyril Produced by Pseudomonas fluorescens G308 to 2-(2-Hydroxyphenyl)thiazole-4-carbaldehyde [aeruginaldehyde

    DEFF Research Database (Denmark)

    Guillemyn, Karel; Ballet, Steven; Ye, Lumeng

    2014-01-01

    An antibiotic substance isolated from Pseudomonas fluorescens strain G308 was earlier assigned the structure of N-mercapto-4-formylcarbostyril, but computational predictions of the H-1 and C-13 NMR magnetic shielding tensors show this structure to be incompatible with the published spectroscopic...

  9. Draft Genome Sequences of Pseudomonas fluorescens BS2 and Pusillimonas noertemannii BS8, Soil Bacteria That Cooperate To Degrade the Poly- -D-Glutamic Acid Anthrax Capsule

    KAUST Repository

    Stabler, R. A.

    2013-01-24

    A mixed culture of Pseudomonas fluorescens BS2 and Pusillimonas noertemannii BS8 degraded poly-γ-d-glutamic acid; when the 2 strains were cultured separately, no hydrolytic activity was apparent. Here we report the draft genome sequences of both soil isolates.

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

    DEFF Research Database (Denmark)

    Dueholm, Morten S; Søndergaard, Mads; Nilsson, Martin

    2013-01-01

    The fap operon, encoding functional amyloids in Pseudomonas (Fap), is present in most pseudomonads, but so far the expression and importance for biofilm formation has only been investigated for P. fluorescens strain UK4. In this study, we demonstrate the capacity of P. aeruginosa PAO1, P. fluores...

  11. Saccharomyces cerevisiae genome-wide mutant screen for sensitivity to 2,4-diacetylphloroglucinol, a biocontrol antibiotic produced by Pseudomonas fluorescens

    Science.gov (United States)

    2,4-diacetylphloroglucinol (2,4-DAPG) is an antibiotic produced by Pseudomonas fluorescens that plays a key role in the ability of the bacterium to suppress phytopathogenic fungi. 2,4-DAPG has broad antibiotic activity, affecting organisms ranging from bacteria to higher plants. The biosynthesis and...

  12. Elucidation of the Vibrio anguillarum genetic response to the potential fish probiont Pseudomonas fluorescens AH2, using RNA-arbitrarily primed PCR

    DEFF Research Database (Denmark)

    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 ......, which results in instant iron deprivation of the pathogen V. anguillarum and complete growth arrest....

  13. The Rsm regulon of plant growth-promoting Pseudomonas fluorescens SS101: role of small RNAs in regulation of lipopeptide biosynthesis

    NARCIS (Netherlands)

    Song, C.; Voort, van der M.; Mortel, van de J.; Hassan, K.A.; Elbourne, L.D.H.; Paulsen, I.T.; Loper, J.E.; Raaijmakers, J.M.

    2015-01-01

    The rhizobacterium Pseudomonas fluorescens SS101 inhibits growth of oomycete and fungal pathogens, and induces resistance in plants against pathogens and insects. To unravel regulatory pathways of secondary metabolite production in SS101, we conducted a genome-wide search for sRNAs and performed

  14. Susceptibility of Mycobacterium immunogenum and Pseudomonas fluorescens to formaldehyde and non-formaldehyde biocides in semi-synthetic metalworking fluids.

    Science.gov (United States)

    Selvaraju, Suresh B; Khan, Izhar U H; Yadav, Jagjit S

    2011-01-20

    Mycobacterium immunogenum, a newly identified member of the Mycobacterium chelonae_M. abscessus complex is considered a potential etiological agent for hypersensitivity pneumonitis (HP) in machine workers exposed to contaminated metalworking fluid (MWF). This study investigated the biocidal efficacy of the frequently applied commercial formaldehyde-releasing (HCHO) biocides Grotan and Bioban CS 1135 and non-HCHO type biocides Kathon 886 MW (isothiazolone) and Preventol CMK 40 (phenolic) toward this emerging mycobacterial species (M. immunogenum) in HP-linked MWFs, alone and in presence of a representative of the Gram-negative bacterial contaminants, Pseudomonas fluorescens, using two semi-synthetic MWF matrices (designated Fluid A and Fluid B). Relative biocide susceptibility analysis indicated M immunogenum to be comparatively more resistant (2-1600 fold) than P. fluorescens to the tested biocides under the varied test conditions. In terms of minimum inhibitory concentration, Kathon was the most effective biocide against M. immunogenum. Fluid factors had a major effect on the biocide susceptibility. Fluid A formulation provided greater protective advantage to the test organisms than Fluid B. Fluid dialysis (Fluid A) led to an increased biocidal efficacy of Grotan, Kathon and Preventol against M. immunogenum further implying the role of native fluid components. Used fluid matrix, in general, increased the resistance of the two test organisms against the biocides, with certain exceptions. M. immunogenum resistance increased in presence of the co-contaminant P. fluorescens. Collectively, the results show a multifactorial nature of the biocide susceptibility of MWF-colonizing mycobacteria and highlight the importance of more rigorous efficacy testing and validation of biocides prior to and during their application in metalworking fluid operations.

  15. Susceptibility of Mycobacterium immunogenum and Pseudomonas fluorescens to Formaldehyde and Non-Formaldehyde Biocides in Semi-Synthetic Metalworking Fluids

    Directory of Open Access Journals (Sweden)

    Suresh B. Selvaraju

    2011-01-01

    Full Text Available Mycobacterium immunogenum, a newly identified member of the Mycobacterium chelonae_M. abscessus complex is considered a potential etiological agent for hypersensitivity pneumonitis (HP in machine workers exposed to contaminated metalworking fluid (MWF. This study investigated the biocidal efficacy of the frequently applied commercial formaldehyde-releasing (HCHO biocides Grotan and Bioban CS 1135 and non-HCHO type biocides Kathon 886 MW (isothiazolone and Preventol CMK 40 (phenolic toward this emerging mycobacterial species (M. immunogenum in HP-linked MWFs, alone and in presence of a representative of the Gram-negative bacterial contaminants, Pseudomonas fluorescens, using two semi-synthetic MWF matrices (designated Fluid A and Fluid B. Relative biocide susceptibility analysis indicated M immunogenum to be comparatively more resistant (2–1600 fold than P. fluorescens to the tested biocides under the varied test conditions. In terms of minimum inhibitory concentration, Kathon was the most effective biocide against M. immunogenum. Fluid factors had a major effect on the biocide susceptibility. Fluid A formulation provided greater protective advantage to the test organisms than Fluid B. Fluid dialysis (Fluid A led to an increased biocidal efficacy of Grotan, Kathon and Preventol against M. immunogenum further implying the role of native fluid components. Used fluid matrix, in general, increased the resistance of the two test organisms against the biocides, with certain exceptions. M. immunogenum resistance increased in presence of the co-contaminant P. fluorescens. Collectively, the results show a multifactorial nature of the biocide susceptibility of MWF-colonizing mycobacteria and highlight the importance of more rigorous efficacy testing and validation of biocides prior to and during their application in metalworking fluid operations.

  16. Enhanced citric acid biosynthesis in Pseudomonas fluorescens ATCC 13525 by overexpression of the Escherichia coli citrate synthase gene.

    Science.gov (United States)

    Buch, Aditi D; Archana, G; Kumar, G Naresh

    2009-08-01

    Citric acid secretion by fluorescent pseudomonads has a distinct significance in microbial phosphate solubilization. The role of citrate synthase in citric acid biosynthesis and glucose catabolism in pseudomonads was investigated by overexpressing the Escherichia coli citrate synthase (gltA) gene in Pseudomonas fluorescens ATCC 13525. The resultant approximately 2-fold increase in citrate synthase activity in the gltA-overexpressing strain Pf(pAB7) enhanced the intracellular and extracellular citric acid yields during the stationary phase, by about 2- and 26-fold, respectively, as compared to the control, without affecting the growth rate, glucose depletion rate or biomass yield. Decreased glucose consumption was paralleled by increased gluconic acid production due to an increase in glucose dehydrogenase activity. While the extracellular acetic acid yield increased in Pf(pAB7), pyruvic acid secretion decreased, correlating with an increase in pyruvate carboxylase activity and suggesting an increased demand for the anabolic precursor oxaloacetate. Activities of two other key enzymes, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase, remained unaltered, and the contribution of phosphoenolpyruvate carboxylase and isocitrate lyase to glucose catabolism was negligible. Strain Pf(pAB7) demonstrated an enhanced phosphate-solubilizing ability compared to the control. Co-expression of the Synechococcus elongatus PCC 6301 phosphoenolpyruvate carboxylase and E. coli gltA genes in P. fluorescens ATCC 13525, so as to supplement oxaloacetate for citrate biosynthesis, neither significantly affected citrate biosynthesis nor caused any change in the other physiological and biochemical parameters measured, despite approximately 1.3- and 5-fold increases in citrate synthase and phosphoenolpyruvate carboxylase activities, respectively. Thus, our results demonstrate that citrate synthase is rate-limiting in enhancing citrate biosynthesis in P. fluorescens ATCC 13525

  17. Photocatalytic disinfection of spoilage bacteria Pseudomonas fluorescens and Macrococcus caseolyticus by nano-TiO2

    Science.gov (United States)

    Photocatalytic disinfection of spoilage bacteria gram-negative (G-) P. fluorescens and gram-positive (G+) M. caseolyticus by nano-TiO2 under different experimental conditions and the disinfection mechanism were investigated. The experimental conditions included the initial bacterial populations, nan...

  18. Whole-genome sequence of Pseudomonas fluorescens EK007-RG4, a promising biocontrol agent against a broad range of bacteria, including the fire blight bacterium Erwinia amylovora

    DEFF Research Database (Denmark)

    Habibi, Roghayeh; Tarighi, Saeed; Behravan, Javad

    2017-01-01

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

  19. Mycorrhization between Cistus ladanifer L. and Boletus edulis Bull is enhanced by the mycorrhiza helper bacteria Pseudomonas fluorescens Migula.

    Science.gov (United States)

    Mediavilla, Olaya; Olaizola, Jaime; Santos-del-Blanco, Luis; Oria-de-Rueda, Juan Andrés; Martín-Pinto, Pablo

    2016-02-01

    Boletus edulis Bull. is one of the most economically and gastronomically valuable fungi worldwide. Sporocarp production normally occurs when symbiotically associated with a number of tree species in stands over 40 years old, but it has also been reported in 3-year-old Cistus ladanifer L. shrubs. Efforts toward the domestication of B. edulis have thus focused on successfully generating C. ladanifer seedlings associated with B. edulis under controlled conditions. Microorganisms have an important role mediating mycorrhizal symbiosis, such as some bacteria species which enhance mycorrhiza formation (mycorrhiza helper bacteria). Thus, in this study, we explored the effect that mycorrhiza helper bacteria have on the efficiency and intensity of the ectomycorrhizal symbiosis between C. ladanifer and B. edulis. The aim of this work was to optimize an in vitro protocol for the mycorrhizal synthesis of B. edulis with C. ladanifer by testing the effects of fungal culture time and coinoculation with the helper bacteria Pseudomonas fluorescens Migula. The results confirmed successful mycorrhizal synthesis between C. ladanifer and B. edulis. Coinoculation of B. edulis with P. fluorescens doubled within-plant mycorrhization levels although it did not result in an increased number of seedlings colonized with B. edulis mycorrhizae. B. edulis mycelium culture time also increased mycorrhization levels but not the presence of mycorrhizae. These findings bring us closer to controlled B. edulis sporocarp production in plantations.

  20. The use of Pseudomonas fluorescens P13 to control sclerotinia stem rot (Sclerotinia sclerotiorum) of oilseed rape.

    Science.gov (United States)

    Li, Hui; Li, Huaibo; Bai, Yan; Wang, Jing; Nie, Ming; Li, Bo; Xiao, Ming

    2011-12-01

    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 (psclerotiorum.

  1. 1-aminocyclopropane-1-carboxylate deaminase from Pseudomonas fluorescens promoting the growth of Chinese cabbage and its polyclonal antibody.

    Science.gov (United States)

    Soh, Byoung Yul; Lee, Gun Woong; Go, Eun Byeul; Kim, Byeo-Ri; Lee, Kui-Jae; Chae, Jong-Chan

    2014-05-01

    Bacterial 1-aminocyclopropane-1-carboxlyate (ACC) deaminase (AcdS) is an enzyme that cleaves ACC, a precursor of the plant hormone ethylene, into α-ketobutyrate and ammonia. The acdS gene was cloned from Pseudomonas fluorescens, which was capable of improving the seedling of Chinese cabbage under salinity condition. The recombinant AcdS (rAcdS) exhibited optimal activity at pH 8.5 and 30°C. Strong activity was sustained at up to 100 mM NaCl. The polyclonal anti-P. fluorescens AcdS antibody was produced in a rabbit that had been immunized with the purified rAcdS. This antibody successfully recognized the homologous antigens derived from the total proteins of isolated plant growth-promoting microorganisms. A statistically significant correlation was observed between the intensity of hybridization signal and AcdS activity measured by a biochemical method, suggesting its application as a useful indicator for active deaminases.

  2. Exposure-related effects of Pseudomonas fluorescens, strain CL145A, on coldwater, coolwater, and warmwater fish

    Science.gov (United States)

    Luoma, James A.; Weber, Kerry L.; Denise A. Mayer,

    2015-01-01

    The exposure-related effects of a commercially prepared spray-dried powder (SDP) formulation of Pseudomonas fluorescens, strain CL145A, were evaluated on coldwater, coolwater, and warmwater fish endemic to the Great Lakes and Upper Mississippi River Basins. Nine species of young-of-the-year fish were exposed to SDP for 24 hours by using continuous-flow, serial-dilution exposure systems at temperatures of 12 degrees Celsius (°C; 2 species; Oncorhynchus mykiss [rainbow trout] and Salvelinus fontinalis [brook trout]), 17 °C (3 species; Perca flavescens [yellow perch], Sander vitreus [walleye], and Acipenser fulvescens [lake sturgeon]), or 22 °C (4 species; Micropterus salmoides [largemouth bass], Micropterus dolomieu [smallmouth bass], Lepomis macrochirus [bluegill sunfish], and Ictalurus punctatus [channel catfish]).

  3. Influence of phenolic acids on indole acetic acid production and on the type III secretion system gene transcription in food-associated Pseudomonas fluorescens KM05.

    Science.gov (United States)

    Myszka, Kamila; Schmidt, Marcin T; Olejnik-Schmidt, Agnieszka K; Leja, Katarzyna; Czaczyk, Katarzyna

    2014-12-01

    The purpose of these investigations was to evaluate the reduction capability of phenolic acids (ferulic, chlorogenic, gallic, and p-coumaric acids) on indole acetic acid synthesis by food-associated Pseudomonas fluorescens KM05. Specific genetic primer for the type III secretion system (TTSS) in P. fluorescens KM05 was designed and the influence of phenolic acids on its expression was investigated. In the work the ferulic and chlorogenic acids at the concentration of 0.02 and 0.04 μg/ml affected on bacterial growth pattern and the signal molecules production. The phenolic acids, that were appreciable effective against P. fluorescens KM05 indole acetic acid production, significantly suppressed TTSS gene. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  4. Iron-Regulated Expression of Alginate Production, Mucoid Phenotype, and Biofilm Formation by Pseudomonas aeruginosa

    Science.gov (United States)

    Wiens, Jacinta R.; Vasil, Adriana I.; Schurr, Michael J.; Vasil, Michael L.

    2014-01-01

    ABSTRACT Pseudomonas aeruginosa strains of non-cystic fibrosis (non-CF) origin do not produce significant amounts of extracellular alginate and are nonmucoid. In CF, such isolates can become mucoid through mutation of one of the genes (mucA, mucB, mucC, or mucD) that produce regulatory factors that sequester AlgU, required for increased expression of alginate genes. Mutation of the muc genes in the nonmucoid PAO1, PA14, PAKS-1, and Ps388 strains led to increased levels of extracellular alginate and an obvious mucoid phenotype, but only under iron-limiting growth conditions (≤5 µM), not under iron-replete conditions (≥10 µM). In contrast, >50% of P. aeruginosa isolates from chronic CF pulmonary infections expressed increased levels of alginate and mucoidy both under iron-limiting and iron-replete conditions (i.e., iron-constitutive phenotype). No single iron regulatory factor (e.g., Fur, PvdS) was associated with this loss of iron-regulated alginate expression and mucoidy in these CF isolates. However, the loss of only pyoverdine production, or its uptake, abrogated the ability of P. aeruginosa to produce a robust biofilm that represents the Psl-type of biofilm. In contrast, we show that mutation of the pyoverdine and pyochelin biosynthesis genes and the pyoverdine receptor (FpvA) lead to iron-constitutive expression of the key alginate biosynthesis gene, algD, and an explicitly mucoid phenotype in both iron-limiting and iron-replete conditions. These data indicate that alginate production and mucoidy, in contrast to other types of biofilms produced by P. aeruginosa, are substantially enhanced under iron limitation. These results also have compelling implications in relation to the use of iron chelators in the treatment of P. aeruginosa CF infections. PMID:24496793

  5. Effect of Pseudomonas fluorescens RB4 and Bacillus subtilis 189 on the phytoremediation potential of Catharanthus roseus (L.) in Cu and Pb-contaminated soils.

    Science.gov (United States)

    Khan, Waheed Ullah; Ahmad, Sajid Rashid; Yasin, Nasim Ahmad; Ali, Aamir; Ahmad, Aqeel

    2017-06-03

    The remediation of heavy metal-contaminated soils has become a critical issue due to toxic effects of these metals on living organisms. The current research was conducted to study the effect of Pseudomonas fluorescens RB4 and Bacillus subtilis 189 on the growth and phytoremediation potential of Catharanthus roseus in Cu- and Pb-contaminated soils. The bacterial strains exhibited significantly higher level of water-extractable Pb and Cu in Pb, Cu, and Cu+Pb-contaminated. The P. fluorescens RB4 inoculated plants, produced 102%, 48%, and 45% higher fresh weight (FW) in soils contaminated with Cu, Pb, and both elements, respectively, as compared to un-inoculated control plants. Similarly, B. subtilis 189 inoculated plants produced 108%, 43%, and 114% more FW in the presence of Cu, Pb, and both elements. The plants co-cultivated with both bacteria exhibited 121%, 102%, and 177% higher FW, in Cu, Pb, and both elements contaminated soils, as compared to respective un-inoculated control. Co-cultivation of P. fluorescens RB4, B. subtilis 189, and P. fluorescens RB4 + B. subtilis 189 resulted in higher accumulation of Cu and Pb in shoots of the C. roseus grown in contaminated soils as compared to un-inoculated control. Bacterial treatments also improved the translocation and metal bioconcentration factors. The growth and phytoextraction capability of C. roseus was improved by inoculation of P. fluorescens RB4 and B. subtilis 189.

  6. Biocontrol strain Pseudomonas fluorescens WCS365 inhibits germination of Fusarium oxysporum spores in tomato root exudate as well as subsequent formation of new spores.

    Science.gov (United States)

    Kamilova, Faina; Lamers, Gerda; Lugtenberg, Ben

    2008-09-01

    Fusarium oxysporum f.sp.radicis-licopersici (Forl) is a soilborne pathogenic fungus which can cause tomato foot and root rot (TFRR). Tomato root exudate is a good source of nutrients for both Forl and the TFRR-suppressing biocontrol bacterium Pseudomonas fluorescens strain WCS365. Incubation of Forl microconidia in tomato root exudate stimulates their germination. This phenomenon is observed, to a lesser extent, upon incubation in plant nutrient solution supplemented with citrate or glucose, the major organic acid and sugar components, respectively, of tomato root exudate. Here we show that induction of germination of microconidia is significantly reduced in the presence of P. fluorescens WCS365 in all tested media. Scanning electron microscopy revealed that P. fluorescens WCS365 colonizes developing hyphae. Efficient colonization correlates with low nutrient availability. Eventually, new microconidia are formed. The presence of P. fluorescens WCS365 reduces the number of newly formed microconidia. This reduction does not depend on physical contact between bacteria and hyphae. We discuss that the ability of P. fluorescens WCS365 to slow down the processes of microconidia germination and development of new microconidia of the phytopathogen, and therefore the ability to reduce fungal dissemination, is likely to contribute to the biocontrol efficacy of this strain.

  7. Effects of phosphorus fertilizer rate and Pseudomonas fluorescens strain on field pea (Pisum sativum subsp. arvense (L. Asch. growth and yield

    Directory of Open Access Journals (Sweden)

    Bahram SALEHI

    2015-11-01

    Full Text Available A field experiment was conducted at Rezvanshahr, Guilan province, Iran, to evaluate the effects of phosphorus fertilizer rate and Pseudomonas fluorescens strains on growth and yield of field pea (Pisum sativum L.. The experimental design was a randomized complete block in a factorial arrangement with three replicates. Factors were phosphorus fertilizer rates (0, 25, 50, 75, and 100 kg P2O5 ha-1 as triple superphosphate, and seed inoculation with P. florescens strains [control (non-inoculated, inoculated with strain R41, and strain R187. Analysis of variance showed that plant height, seed yield, pod number per m2, 100-seed weight, biological yield, harvest index, and leaf P concentration were significantly influenced by phosphorus fertilizer rate and P. florescens strain. At the same time, phosphorus fertilizer rate × P. fluorescens strain interaction was significant only for 100-seed weight. On the other hand, seed number per pod was significantly affected neither by phosphorus fertilizer rate nor by pseudomonas strains. Result showed that seed yield was significantly increased from 1099 ± 67 to 1898 ± 118 kg ha-1 as P2O5 application rate increased from 0 to 75 kg ha-1, and thereafter relatively remained constant. There was no significant difference in seed yield between plants raised from inoculated seeds with P. fluorescens, strain R187 (1664 ± 97 kg ha-1 and those raised from inoculated seeds with P. fluorescens, strain R41 (1669 ± 104 kg ha-1. At the same time, plants raised from inoculated seeds with P. fluorescens (both strains produced greater grain yield compared to those raised from uninoculated seeds (1370 ± 80 kg ha-1. Based on the results of this study, P2O5 application at the rate of 75 kg ha-1 and inoculation with pseudomonas bacteria are recommended for obtaining the greatest seed yield in field pea.

  8. One-step purification and characterization of alginate lyase from a clinical Pseudomonas aeruginosa with destructive activity on bacterial biofilm

    Directory of Open Access Journals (Sweden)

    Parinaz Ghadam

    2017-05-01

    Full Text Available Objective(s: Pseudomonas aeruginosais a Gram-negative and aerobic rod bacterium that displays mucoid and non-mucoid phenotype. Mucoid strains secrete alginate, which is the main agent of biofilms in chronic P. aeruginosa infections, show high resistance to antibiotics; consequently, the biological disruption of mucoid P. aeruginosa biofilms is an attractive area of study for researchers. Alginate lyase gene (algl is a member of alginate producing operon which by glycosidase activity produces primer for other enzymes in this cluster. Also this activity can destroy the extracellular alginate; therefore this enzyme participates in alginate production and destruction pathway. Alginate lyase causes detachment of a biofilm by reducing its adhesion to the surfaces, and increases phagocytosis and antibiotic susceptibility. In this study, alginate lyase was purified in just one step and its properties were investigated. Materials and Methods: The purification was done by affinity chromatography, analysed by SDS-PAGE, and its effect on P. aeruginosa biofilms was surveyed by micro titer plate assay and SEM. The substrate specificity of the enzyme was determined by PCR. Results: Alginate lyase from isolate 48 was purified in one step. It is more thermally resistant than alginate lyase from Pseudomonas aeruginosa PAO1 and poly M, poly G and poly MG alginate were the substrate of this enzyme. Moreover, it has an eradication effect on biofilms from P. aeruginosa 48 and PAO1. Conclusion: In this study an alginate lyase with many characteristics suitable in medicine such as thermal stability, effective on poly M alginate, and bacterial biofilm destructive was introduced and purified.

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

    National Research Council Canada - National Science Library

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

    2013-01-01

    .... Based on the in vitro performance of indigenous Trichoderma spp. and Pseudomonas spp., four effective antagonists were selected and screened under greenhouse experiment for their growth enhancement potential...

  10. Proteomic Detection of Non-Annotated Protein-Coding Genes in Pseudomonas fluorescens Pf0-1

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Wook; Silby, Mark W.; Purvine, Samuel O.; Nicoll, Julie S.; Hixson, Kim K.; Monroe, Matthew E.; Nicora, Carrie D.; Lipton, Mary S.; Levy, Stuart B.

    2009-12-24

    Genome sequences are annotated by computational prediction of coding sequences, followed by similarity searches such as BLAST, which provide a layer of (possible) functional information. While the existence of processes such as alternative splicing complicates matters for eukaryote genomes, the view of bacterial genomes as a linear series of closely spaced genes leads to the assumption that computational annotations which predict such arrangements completely describe the coding capacity of bacterial genomes. We undertook a proteomic study to identify proteins expressed by Pseudomonas fluorescens Pf0-1 from genes which were not predicted during the genome annotation. Mapping peptides to the Pf0-1 genome sequence identified sixteen non-annotated protein-coding regions, of which nine were antisense to predicted genes, six were intergenic, and one read in the same direction as an annotated gene but in a different frame. The expression of all but one of the newly discovered genes was verified by RT-PCR. Few clues as to the function of the new genes were gleaned from informatic analyses, but potential orthologues in other Pseudomonas genomes were identified for eight of the new genes. The 16 newly identified genes improve the quality of the Pf0-1 genome annotation, and the detection of antisense protein-coding genes indicates the under-appreciated complexity of bacterial genome organization.

  11. Genetic responses induced in olive roots upon colonization by the biocontrol endophytic bacterium Pseudomonas fluorescens PICF7.

    Directory of Open Access Journals (Sweden)

    Elisabetta Schilirò

    Full Text Available Knowledge on the genetic basis underlying interactions between beneficial bacteria and woody plants is still very limited, and totally absent in the case of olive. We aimed to elucidate genetic responses taking place during the colonization of olive roots by the native endophyte Pseudomonas fluorescens PICF7, an effective biocontrol agent against Verticillium wilt of olive. Roots of olive plants grown under non-gnotobiotic conditions were collected at different time points after PICF7 inoculation. A Suppression Subtractive Hybridization cDNA library enriched in induced genes was generated. Quantitative real time PCR (qRT-PCR analysis validated the induction of selected olive genes. Computational analysis of 445 olive ESTs showed that plant defence and response to different stresses represented nearly 45% of genes induced in PICF7-colonized olive roots. Moreover, quantitative real-time PCR (qRT-PCR analysis confirmed induction of lipoxygenase, phenylpropanoid, terpenoids and plant hormones biosynthesis transcripts. Different classes of transcription factors (i.e., bHLH, WRKYs, GRAS1 were also induced. This work highlights for the first time the ability of an endophytic Pseudomonas spp. strain to mount a wide array of defence responses in an economically-relevant woody crop such as olive, helping to explain its biocontrol activity.

  12. Genetic Responses Induced in Olive Roots upon Colonization by the Biocontrol Endophytic Bacterium Pseudomonas fluorescens PICF7

    Science.gov (United States)

    Schilirò, Elisabetta; Ferrara, Massimo; Nigro, Franco; Mercado-Blanco, Jesús

    2012-01-01

    Knowledge on the genetic basis underlying interactions between beneficial bacteria and woody plants is still very limited, and totally absent in the case of olive. We aimed to elucidate genetic responses taking place during the colonization of olive roots by the native endophyte Pseudomonas fluorescens PICF7, an effective biocontrol agent against Verticillium wilt of olive. Roots of olive plants grown under non-gnotobiotic conditions were collected at different time points after PICF7 inoculation. A Suppression Subtractive Hybridization cDNA library enriched in induced genes was generated. Quantitative real time PCR (qRT-PCR) analysis validated the induction of selected olive genes. Computational analysis of 445 olive ESTs showed that plant defence and response to different stresses represented nearly 45% of genes induced in PICF7-colonized olive roots. Moreover, quantitative real-time PCR (qRT-PCR) analysis confirmed induction of lipoxygenase, phenylpropanoid, terpenoids and plant hormones biosynthesis transcripts. Different classes of transcription factors (i.e., bHLH, WRKYs, GRAS1) were also induced. This work highlights for the first time the ability of an endophytic Pseudomonas spp. strain to mount a wide array of defence responses in an economically-relevant woody crop such as olive, helping to explain its biocontrol activity. PMID:23144916

  13. Di-Adenosine Tetraphosphate (Ap4A) Metabolism Impacts Biofilm Formation by Pseudomonas fluorescens via Modulation of c-di-GMP-Dependent Pathways▿

    OpenAIRE

    Monds, Russell D.; Newell, Peter D.; Wagner, Jeffrey C.; Schwartzman, Julia A.; Lu, Wenyun; Rabinowitz, Joshua D.; O'Toole, George A.

    2010-01-01

    Dinucleoside tetraphosphates are common constituents of the cell and are thought to play diverse biological roles in organisms ranging from bacteria to humans. In this study we characterized two independent mechanisms by which di-adenosine tetraphosphate (Ap4A) metabolism impacts biofilm formation by Pseudomonas fluorescens. Null mutations in apaH, the gene encoding nucleoside tetraphosphate hydrolase, resulted in a marked increase in the cellular level of Ap4A. Concomitant with this increase...

  14. Biosynthesis of the antimicrobial cyclic lipopeptides nunamycin and nunapeptin by Pseudomonas fluorescens strain In5 is regulated by the LuxR-type transcriptional regulator NunF

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Phippen, Christopher; Nielsen, Kristian Fog

    2017-01-01

    Nunamycin and nunapeptin are two antimicrobial cyclic lipopeptides (CLPs) produced by Pseudomonas fluorescens In5 and synthesized by nonribosomal synthetases (NRPS) located on two gene clusters designated the nun-nup regulon. Organization of the regulon is similar to clusters found in other CLP-p...... that environmental elicitors may also influence nunF expression which upon activation regulates nunamycin and nunapeptin production required for the growth inhibition of phytopathogens....

  15. Stabilitäten der Benzaldehydlyase aus Pseudomonas fluorescens und der Carbonylreduktase aus Candida parapsilosis in wässrig-organischen Zweiphasensystemen

    OpenAIRE

    Van Den Wittenboer, Anne

    2009-01-01

    Benzaldehyde lyase from Pseudomonas fluorescens (BAL) and carbonylreductase from Candida parapsilosis (CPCR) are versatile catalysts for the production of various chiral intermediates, which are of interest for the pharmaceutical industry. Due to the mostly hydrophobic reactants only low productivities can be achieved in aqueous reaction systems and thus the use of alternative reaction media is desirable. Especially the use of aqueous-organic biphasic systems is promising, since the extractio...

  16. A modular esterase from Pseudomonas fluorescens subsp. cellulosa contains a non-catalytic cellulose-binding domain.

    Science.gov (United States)

    Ferreira, L M; Wood, T M; Williamson, G; Faulds, C; Hazlewood, G P; Black, G W; Gilbert, H J

    1993-09-01

    The 5' regions of genes xynB and xynC, coding for a xylanase and arabinofuranosidase respectively, are identical and are reiterated four times within the Pseudomonas fluorescens subsp. cellulosa genome. To isolate further copies of the reiterated xynB/C 5' region, a genomic library of Ps. fluorescens subsp. cellulosa DNA was screened with a probe constructed from the conserved region of xynB. DNA from one phage which hybridized to the probe, but not to sequences upstream or downstream of the reiterated xynB/C locus, was subcloned into pMTL22p to construct pFG1. The recombinant plasmid expressed a protein in Escherichia coli, designated esterase XYLD, of M(r) 58,500 which bound to cellulose but not to xylan. XYLD hydrolysed aryl esters, released acetate groups from acetylxylan and liberated 4-hydroxy-3-methoxycinnamic acid from destarched wheat bran. The nucleotide sequence of the XYLD-encoding gene, xynD, revealed an open reading frame of 1752 bp which directed the synthesis of a protein of M(r) 60,589. The 5' 817 bp of xynD and the amino acid sequence between residues 37 and 311 of XYLD were almost identical with the corresponding regions of xynB and xynC and their encoded proteins XYLB and XYLC. Truncated derivatives of XYLD lacking the N-terminal conserved sequence retained the capacity to hydrolyse ester linkages, but did not bind cellulose. Expression of truncated derivatives of xynD, comprising the 5' 817 bp sequence, encoded a non-catalytic polypeptide that bound cellulose. These data indicate that XYLD has a modular structure comprising of a N-terminal cellulose-binding domain and a C-terminal catalytic domain.

  17. Biological control of wheat root diseases by the CLP-producing strain Pseudomonas fluorescens HC1-07.

    Science.gov (United States)

    Yang, Ming-Ming; Wen, Shan-Shan; Mavrodi, Dmitri V; Mavrodi, Olga V; von Wettstein, Diter; Thomashow, Linda S; Guo, Jian-Hua; Weller, David M

    2014-03-01

    Pseudomonas fluorescens HC1-07, previously isolated from the phyllosphere of wheat grown in Hebei province, China, suppresses the soilborne disease of wheat take-all, caused by Gaeumannomyces graminis var. tritici. We report here that strain HC1-07 also suppresses Rhizoctonia root rot of wheat caused by Rhizoctonia solani AG-8. Strain HC1-07 produced a cyclic lipopeptide (CLP) with a molecular weight of 1,126.42 based on analysis by electrospray ionization mass spectrometry. Extracted CLP inhibited the growth of G. graminis var. tritici and R. solani in vitro. To determine the role of this CLP in biological control, plasposon mutagenesis was used to generate two nonproducing mutants, HC1-07viscB and HC1-07prtR2. Analysis of regions flanking plasposon insertions in HC1-07prtR2 and HC1-07viscB revealed that the inactivated genes were similar to prtR and viscB, respectively, of the well-described biocontrol strain P. fluorescens SBW25 that produces the CLP viscosin. Both genes in HC1-07 were required for the production of the viscosin-like CLP. The two mutants were less inhibitory to G. graminis var. tritici and R. solani in vitro and reduced in ability to suppress take-all. HC1-07viscB but not HC-07prtR2 was reduced in ability to suppress Rhizoctonia root rot. In addition to CLP production, prtR also played a role in protease production.

  18. Interaction between Medicago truncatula and Pseudomonas fluorescens: evaluation of costs and benefits across an elevated atmospheric CO(2.

    Directory of Open Access Journals (Sweden)

    Clémentine Lepinay

    Full Text Available Soil microorganisms play a key role in both plants nutrition and health. Their relation with plant varies from mutualism to parasitism, according to the balance of costs and benefits for the two partners of the interaction. These interactions involved the liberation of plant organic compounds via rhizodeposition. Modification of atmospheric CO(2 concentration may affect rhizodeposition and as a consequence trophic interactions that bind plants and microorganisms. Positive effect of elevated CO(2 on plants are rather well known but consequences for micoorganisms and their interactions with plants are still poorly understood. A gnotobiotic system has been developed to study the interaction between Medicago truncatula Jemalong J5 and the mutualistic bacteria Pseudomonas fluorescens strain C7R12 under two atmospheric CO(2 concentrations: ambient (365 ppm versus enriched (750 ppm. Costs and benefits for each partner have been determined over time by measuring plant development and growth, the C and N contents of the various plant parts and the density of the bacteria in rhizosphere compartments. Following the increase in CO(2, there was a beneficial effect of P. fluorescens C7R12 on development, vegetative growth, and C/N content of M. truncatula. Concerning plant reproduction, an early seed production was noticed in presence of the bacterial strain combined with increased atmospheric CO(2 conditions. Paradoxically, this transient increase in seed production was correlated with a decrease in bacterial density in the rhizosphere soil, revealing a cost of increased CO(2 for the bacterial strain. This shift of costs-benefits ratio disappeared later during the plant growth. In conclusion, the increase in CO(2 concentration modifies transiently the cost-benefit balance in favor of the plant. These results may be explained either by a competition between the two partners or a change in bacterial physiology. The ecosystem functioning depends on the

  19. [Incidence of alginate-coding gene in carbapenem-resistant Pseudomonas aeruginosa strains].

    Science.gov (United States)

    Bogiel, Tomasz; Kwiecińska-Piróg, Joanna; Kozuszko, Sylwia; Gospodarek, Eugenia

    2011-01-01

    Pseudomonas aeruginosa rods are one of the most common isolated opportunistic nosocomial pathogens. Strains usually are capable to secret a capsule-like polysaccharide called alginate important for evasion of host defenses, especially during chronic pulmonary disease of patients with cystic fibrosis. Most genes for alginate biosynthesis and lysis are encoded by the operon. The aim of our study was to evaluate the incidence of algD sequence, generally use for alginate-coding gene detection, in 120 P. aeruginosa strains resistant to carbapenems. All isolates were obtained in the Department of Clinical Microbiology University Hospital no. 1 of dr A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruń. Examined strains demonstrated resistance to carbenicillin (90,0%), ticarcillin (89,2%) and ticarcillin clavulanate (86,7%). All strains were susceptible to colistin. The majority of examined strains was susceptible to ceftazidime and cefepime (40,8% each) and norfloxacin (37,5%). Presence of algD gene - noted in 112 (93,3%) strains proves that not every strain is capable to produce alginate. It was also found out that differences in algD genes incidence in case of different clinical material that strains were isolated from were not statistically important.

  20. PENGARUH APLIKASI PSEUDOMONAS FLUORESCENS P60 TERHADAP MUTU PATOLOGIS, MUTU FISIOLOGIS, DAN PERTUMBUHAN BIBIT PADI IR 64

    Directory of Open Access Journals (Sweden)

    Lisa Navitasari

    2014-08-01

    Full Text Available Effect of Pseudomonas fluorescens P60 on pathological and physiological quality and growth of rice IR 64  seedlings. The research objectives were (1 detection and identification of seed-borne pathogens of IR 64 rice, (2 testing Pseudomonas fluorescents P60 in inhibiting the in vitro growth of seed-borne pathogens colonies, (3 testing P. fluorescents P60 for pathological and physiological seed quality, and (4 testing P. fluorescents P60 on the growth of seedlings in the greenhouse. The results showed that some seed-borne pathogens can be found both on farmers’ IR 64 rice and factory’s; they were Aspergillus flavus, Alternaria padwickii, Pseudomonas glumae, and P. syringae. Application of P. flourescens P60 was able to inhibit the in vitrogrowth of colonies of all seed-borne pathogens, except P. syringae.  Related to pathological quality, the effect of P. flourescens P60 on percentage of seed-borne pathogens attack did not significantly different from that of benomil but smaller than distilled water. On the physiological quality of seeds, treatment of P. flourescens P60 has the same effect with benomil and distilled water, with  germination rate was more than 80%. In the greenhouse study,treatment of seed immersion time  in P. flourescens P60 suspension showed that the effect of immersion time as long as15 minutes and 25 minutes on  seedling height, root length, and seedling dry weightdid not significantly different. were. However, 25 minutes immersion time resulted in fresh seedling weight and root dry weight higher than that of 15 minutes immersion time.

  1. Functional Characterization of the Mannitol Promoter of Pseudomonas fluorescens DSM 50106 and Its Application for a Mannitol-Inducible Expression System for Pseudomonas putida KT2440.

    Directory of Open Access Journals (Sweden)

    Jana Hoffmann

    Full Text Available A new pBBR1MCS-2-derived vector containing the Pseudomonas fluorescens DSM10506 mannitol promoter PmtlE and mtlR encoding its AraC/XylS type transcriptional activator was constructed and optimized for low basal expression. Mannitol, arabitol, and glucitol-inducible gene expression was demonstrated with Pseudomonas putida and eGFP as reporter gene. The new vector was applied for functional characterization of PmtlE. Identification of the DNA binding site of MtlR was achieved by in vivo eGFP measurement with PmtlE wild type and mutants thereof. Moreover, purified MtlR was applied for detailed in vitro investigations using electrophoretic mobility shift assays and DNaseI footprinting experiments. The obtained data suggest that MtlR binds to PmtlE as a dimer. The proposed DNA binding site of MtlR is AGTGC-N5-AGTAT-N7-AGTGC-N5-AGGAT. The transcription activation mechanism includes two binding sites with different binding affinities, a strong upstream binding site and a weaker downstream binding site. The presence of the weak downstream binding site was shown to be necessary to sustain mannitol-inducibility of PmtlE. Two possible functions of mannitol are discussed; the effector might stabilize binding of the second monomer to the downstream half site or promote transcription activation by inducing a conformational change of the regulator that influences the contact to the RNA polymerase.

  2. Functional Characterization of the Mannitol Promoter of Pseudomonas fluorescens DSM 50106 and Its Application for a Mannitol-Inducible Expression System for Pseudomonas putida KT2440

    Science.gov (United States)

    Hoffmann, Jana; Altenbuchner, Josef

    2015-01-01

    A new pBBR1MCS-2-derived vector containing the Pseudomonas fluorescens DSM10506 mannitol promoter PmtlE and mtlR encoding its AraC/XylS type transcriptional activator was constructed and optimized for low basal expression. Mannitol, arabitol, and glucitol-inducible gene expression was demonstrated with Pseudomonas putida and eGFP as reporter gene. The new vector was applied for functional characterization of PmtlE. Identification of the DNA binding site of MtlR was achieved by in vivo eGFP measurement with PmtlE wild type and mutants thereof. Moreover, purified MtlR was applied for detailed in vitro investigations using electrophoretic mobility shift assays and DNaseI footprinting experiments. The obtained data suggest that MtlR binds to PmtlE as a dimer. The proposed DNA binding site of MtlR is AGTGC-N5-AGTAT-N7-AGTGC-N5-AGGAT. The transcription activation mechanism includes two binding sites with different binding affinities, a strong upstream binding site and a weaker downstream binding site. The presence of the weak downstream binding site was shown to be necessary to sustain mannitol-inducibility of PmtlE. Two possible functions of mannitol are discussed; the effector might stabilize binding of the second monomer to the downstream half site or promote transcription activation by inducing a conformational change of the regulator that influences the contact to the RNA polymerase. PMID:26207762

  3. In vitro effects of Laccaria bicolor S238 N and Pseudomonas fluorescens strain BBc6 on rooting of de-rooted shoot hypocotyls of Norway spruce.

    Science.gov (United States)

    Karabaghli, C.; Frey-Klett, P.; Sotta, B.; Bonnet, M.; Le Tacon, F.

    1998-02-01

    The ectomycorrhizal fungus Laccaria bicolor S238 N and the bacterium Pseudomonas fluorescens BBc6 were used separately and in combination to induce in vitro rooting of de-rooted shoot hypocotyls of Norway spruce (Picea abies (L.) Karst.). When the culture medium was supplemented with tryptophan, a precursor of indole-3-acetic acid (IAA) synthesis, the presence of the ectomycorrhizal fungus increased the percentage of hypocotyls forming roots; furthermore, both the fungal and bacterial inoculations enhanced the number of roots formed per rooted hypocotyl. Similar results were obtained by adding exogenous IAA (5 and 10 &mgr;M) to the rooting medium. After the rooting phase, the fungal inoculation enhanced adventitious root elongation and branching as well as the aerial growth of the cuttings. Pseudomonas fluorescens BBc6 had no effect on these parameters. The production of IAA by pure cultures of L. bicolor S238 N and P. fluorescens BBc6 was estimated by immunochemical analysis using specific anti-IAA antibodies. Both L. bicolor S238 N and P. fluorescens BBc6 synthesized IAA in pure culture and synthesis was stimulated in the presence of tryptophan. Thus, the effect of the fungus in stimulating adventitious root formation and subsequent elongation and branching can be attributed, at least partially, to the synthesis of IAA by the fungus. The finding that P. fluorescens BBc6 had no effect on root elongation and branching although it produced IAA suggests that either IAA was not the only parameter involved in the stimulation of these processes by L. bicolor S238 N or the bacterium produced other compounds that counteracted the stimulatory effects of IAA on root elongation and branching.

  4. The Effect of Bacteria Colony Pseudomonas fluorescens (UB_Pf1 and Bacillus subtilis (UB_Bs1 on the Mortality of Pratylenchus coffeae (Tylenchida: Pratylenchidae

    Directory of Open Access Journals (Sweden)

    Presti Mardiyani Purwaningtyas

    2016-11-01

    Full Text Available Parasitic Root-Lession nematode of Pratylenchus coffeae can reduce the Indonesian coffee plants productivity. Several studies reported that Pseudomonas fluorescens and Bacillus subtilis endophytic bacteria were antagonistic bacteria to nematode. The objective of this research was to reveal the effectiveness of bacterial colonies density of P. fluorescens (UB_Pf1, B.subtilis (UB BS1, and a combination of both bacteria on nematode mortality using median lethal concentration (LC50 and median lethal time 50 (LT50. The densities of bacteria used in this study were 107, 109, 1011 and 1013 cfu/ml. 35 testing nematodes were used and the mortality was counted at 6, 12, 24, 36, and 48 hours after treatments. The results showed that LC50 values of P. fluorescens was (UB_Pf1 was 4,3x108 cfu/ml, LC50 B. subtilis (UB_Bs1 was 1,9x109cfu/ ml, and LC50 combination of both bacteria was, 8x107 cfu/ml. It implies that the application of the combination of both bacteria are more pathogenic than single bacterial treatment. The results also showed that the highest LT50 value was 13.21  hours combination of bacterial colonies with a density of 1013 cfu/ml and the lowest LT50 value was 52.00 hours on P. fluorescens (UB_Pf1 treatment with colonies density of 107 cfu/ml.How to CitePurwaningtyas, P. M., Rahardjo, B. T., & Tarno, H. (2016. The Effect of Bacteria Colony Pseudomonas fluorescens (UB_Pf1 and Bacillus subtilis (UB_Bs1 on the Mortality of Pratylenchus coffeae (Tylenchida: Pratylenchidae. Biosaintifika: Journal of Biology & Biology Education, 8(3, 286-293. 

  5. Activation Mechanism and Cellular Localization of Membrane-Anchored Alginate Polymerase in Pseudomonas aeruginosa.

    Science.gov (United States)

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

    2017-05-01

    The exopolysaccharide alginate, produced by the opportunistic human pathogen Pseudomonas aeruginosa, confers a survival advantage to the bacterium by contributing to the formation of characteristic biofilms during infection. Membrane-anchored proteins Alg8 (catalytic subunit) and Alg44 (copolymerase) constitute the alginate polymerase that is being activated by the second messenger molecule bis-(3', 5')-cyclic dimeric GMP (c-di-GMP), but the mechanism of activation remains elusive. To shed light on the c-di-GMP-mediated activation of alginate polymerization in vivo, an in silico structural model of Alg8 fused to the c-di-GMP binding PilZ domain informed by the structure of cellulose synthase, BcsA, was developed. This structural model was probed by site-specific mutagenesis and different cellular levels of c-di-GMP. Results suggested that c-di-GMP-mediated activation of alginate polymerization involves amino acids residing at two loops, including H323 (loop A) and T457 and E460 (loop B), surrounding the catalytic site in the predicted model. The activities of the respective Alg8 variants suggested that c-di-GMP-mediated control of substrate access to the catalytic site of Alg8 is dissimilar to the known activation mechanism of BcsA. Alg8 variants responded differently to various c-di-GMP levels, while MucR imparted c-di-GMP for activation of alginate polymerase. Furthermore, we showed that Alg44 copolymerase constituted a stable dimer, with its periplasmic domains required for protein localization and alginate polymerization and modification. Superfolder green fluorescent protein (GFP) fusions of Alg8 and Alg44 showed a nonuniform, punctate, and patchy arrangement of both proteins surrounding the cell. Overall, this study provides insights into the c-di-GMP-mediated activation of alginate polymerization while assigning functional roles to Alg8 and Alg44, including their subcellular localization and distribution.IMPORTANCE The exopolysaccharide alginate is an

  6. Interaction of the psychrotroph Pseudomonas fluorescens In5 with phytopathogens in cold soils

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Olsson, Stefan; Stougaard, Peter

    sequencing was conducted to investigate the response of the bacterium to different plant pathogens in dual-culture. Results/Discussion: Key biocontrol components of P. fluorescens In5 identified to date include the two secondary metabolites nunamycin and nunapeptin that form part of a complex interaction...... for combatting plant pathogenic fungi. Current studies are aimed at unravelling further the complex mode of action underpinning the antagonistic activity of In5 in order to develop effective microbial biocontrol agents (mBCAs) for the management of soil-borne plant diseases.......Aim: Potato cultivation in southwest Greenland, at Inneruulalik, omits the use of pesticides while relying on limited crop rotations and despite the presence of plant pathogens in the soil does not suffer from major disease outbreaks. Previously, we have shown that the soil at Inneruulalik...

  7. Effect of biocontrol agent Pseudomonas fluorescens 2P24 on soil fungal community in cucumber rhizosphere using T-RFLP and DGGE.

    Science.gov (United States)

    Gao, Guanpeng; Yin, Danhan; Chen, Shengju; Xia, Fei; Yang, Jie; Li, Qing; Wang, Wei

    2012-01-01

    Fungi and fungal community play important roles in the soil ecosystem, and the diversity of fungal community could act as natural antagonists of various plant pathogens. Biological control is a promising method to protect plants as chemical pesticides may cause environment pollution. Pseudomonas fluorescens 2P24 had strong inhibitory on Rastonia solanacearum, Fusarium oxysporum and Rhizoctonia solani, etc., and was isolated from the wheat rhizosphere take-all decline soils in Shandong province, China. However, its potential effect on soil fungal community was still unknown. In this study, the gfp-labeled P. fluorescens 2P24 was inoculated into cucumber rhizosphere, and the survival of 2P24 was monitored weekly. The amount decreased from 10(8) to 10(5) CFU/g dry soils. The effect of 2P24 on soil fungal community in cucumber rhizosphere was investigated using T-RFLP and DGGE. In T-RFLP analysis, principle component analysis showed that the soil fungal community was greatly influenced at first, digested with restriction enzyme Hinf I and Taq I. However, there was little difference as digested by different enzymes. DGGE results demonstrated that the soil fungal community was greatly shocked at the beginning, but it recovered slowly with the decline of P. fluorescens 2P24. Four weeks later, there was little difference between the treatment and control. Generally speaking, the effect of P. fluorescens 2P24 on soil fungal community in cucumber rhizosphere was just transient.

  8. Effect of biocontrol agent Pseudomonas fluorescens 2P24 on soil fungal community in cucumber rhizosphere using T-RFLP and DGGE.

    Directory of Open Access Journals (Sweden)

    Guanpeng Gao

    Full Text Available Fungi and fungal community play important roles in the soil ecosystem, and the diversity of fungal community could act as natural antagonists of various plant pathogens. Biological control is a promising method to protect plants as chemical pesticides may cause environment pollution. Pseudomonas fluorescens 2P24 had strong inhibitory on Rastonia solanacearum, Fusarium oxysporum and Rhizoctonia solani, etc., and was isolated from the wheat rhizosphere take-all decline soils in Shandong province, China. However, its potential effect on soil fungal community was still unknown. In this study, the gfp-labeled P. fluorescens 2P24 was inoculated into cucumber rhizosphere, and the survival of 2P24 was monitored weekly. The amount decreased from 10(8 to 10(5 CFU/g dry soils. The effect of 2P24 on soil fungal community in cucumber rhizosphere was investigated using T-RFLP and DGGE. In T-RFLP analysis, principle component analysis showed that the soil fungal community was greatly influenced at first, digested with restriction enzyme Hinf I and Taq I. However, there was little difference as digested by different enzymes. DGGE results demonstrated that the soil fungal community was greatly shocked at the beginning, but it recovered slowly with the decline of P. fluorescens 2P24. Four weeks later, there was little difference between the treatment and control. Generally speaking, the effect of P. fluorescens 2P24 on soil fungal community in cucumber rhizosphere was just transient.

  9. Effect of Two Biological Formulations Based on Bacillus subtilis and Pseudomonas fluorescens on Control of Didymella applanata, the Causal Agent of Red Raspberry Cane Spur Blight

    Directory of Open Access Journals (Sweden)

    Margarita Shternshis

    2016-01-01

    Full Text Available In vitro and in vivo studies were conducted to estimate the efficacy of the two microbial formulations based on Bacillus subtilis Cohn. and Pseudomonas fluorescens Mig. on the fungus Didymella applanata (Niessl. Sacc., the causal agent of red raspberry (Rubus idaeus L. spur blight. In vitro, both bacteria reduced the growth of D. applanata. In inoculation experiments with raspberry canes in two cultivars with different susceptibility to D. applanata, these antagonistic bacteria suppressed fungal development by reducing the lesions area and the number of D. applanata fruiting bodies. Field trials of two biological formulations under natural conditions showed a significant suppression of the disease. B. subtilis and P. fluorescens included in the formulations revealed antagonistic activity towards D. applanata that depended on the red raspberry cultivar and weather conditions. In all cases, B. subtilis showed better results than P. fluorescens in biocontrol of the raspberry spur blight. This study demonstrated for the first time the ability of the biocontrol agents B. subtilis and P. fluorescens to suppress red raspberry cane spur blight, a serious worldwide disease.

  10. Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system

    Directory of Open Access Journals (Sweden)

    Sperandio Daniel

    2012-09-01

    Full Text Available Abstract Background Pseudomonas fluorescens biovar I MFN1032 is a clinical isolate able to grow at 37°C. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides, and a cell-associated hemolytic activity distinct from the secreted hemolytic activity. Cell-associated hemolysis is independent of biosurfactant production and remains in a gacA mutant. Disruption of the hrpU-like operon (the basal part of type III secretion system from rhizospheric strains suppresses this activity. We hypothesized that this phenotype could reflect evolution of an ancestral mechanism involved in the survival of this species in its natural niche. In this study, we evaluated the hrpU-like operon’s contribution to other virulence mechanisms using a panel of Pseudomonas strains from various sources. Results We found that MFN1032 inhibited the growth of the amoebae Dictyostelium discoideum and that this inhibition involved the hrpU-like operon and was absent in a gacA mutant. MFN1032 was capable of causing macrophage lysis, if the hrpU-like operon was intact, and this cytotoxicity remained in a gacA mutant. Cell-associated hemolytic activity and macrophage necrosis were found in other P. fluorescens clinical isolates, but not in biocontrol P. fluorescens strains harbouring hrpU-like operon. The growth of Dictyostelium discoideum was inhibited to a different extent by P. fluorescens strains without correlation between this inhibition and hrpU-like operon sequences. Conclusions In P. fluorescens MFN1032, the basal part of type III secretion system plays a role in D. discoideum growth inhibition and macrophage necrosis. The inhibition of D. discoideum growth is dependent on the GacS/GacA system, while cell-associated hemolytic activity and macrophage lysis are not. Virulence against eukaryotic cells based on the hrpU-like operon may be more than just a stochastic evolution of a conserved system dedicated to survival in

  11. Ability of the marine bacterium Pseudomonas fluorescens BA3SM1 to counteract the toxicity of CdSe nanoparticles.

    Science.gov (United States)

    Poirier, Isabelle; Kuhn, Lauriane; Demortière, Arnaud; Mirvaux, Boris; Hammann, Philippe; Chicher, Johana; Caplat, Christelle; Pallud, Marie; Bertrand, Martine

    2016-10-04

    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. 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

  12. Pseudomonas aeruginosa Aggregate Formation in an Alginate Bead Model System Exhibits In Vivo-Like Characteristics.

    Science.gov (United States)

    Sønderholm, Majken; Kragh, Kasper Nørskov; Koren, Klaus; Jakobsen, Tim Holm; Darch, Sophie E; Alhede, Maria; Jensen, Peter Østrup; Whiteley, Marvin; Kühl, Michael; Bjarnsholt, Thomas

    2017-05-01

    Alginate beads represent a simple and highly reproducible in vitro model system for diffusion-limited bacterial growth. In this study, alginate beads were inoculated with Pseudomonas aeruginosa and followed for up to 72 h. Confocal microscopy revealed that P. aeruginosa formed dense clusters similar in size to in vivo aggregates observed ex vivo in cystic fibrosis lungs and chronic wounds. Bacterial aggregates primarily grew in the bead periphery and decreased in size and abundance toward the center of the bead. Microsensor measurements showed that the O2 concentration decreased rapidly and reached anoxia ∼100 μm below the alginate bead surface. This gradient was relieved in beads supplemented with NO3- as an alternative electron acceptor allowing for deeper growth into the beads. A comparison of gene expression profiles between planktonic and alginate-encapsulated P. aeruginosa confirmed that the bacteria experienced hypoxic and anoxic growth conditions. Furthermore, alginate-encapsulated P. aeruginosa exhibited a lower respiration rate than the planktonic counterpart and showed a high tolerance toward antibiotics. The inoculation and growth of P. aeruginosa in alginate beads represent a simple and flexible in vivo-like biofilm model system, wherein bacterial growth exhibits central features of in vivo biofilms. This was observed by the formation of small cell aggregates in a secondary matrix with O2-limited growth, which was alleviated by the addition of NO3- as an alternative electron acceptor, and by reduced respiration rates, as well as an enhanced tolerance to antibiotic treatment.IMPORTANCEPseudomonas aeruginosa has been studied intensively for decades due to its involvement in chronic infections, such as cystic fibrosis and chronic wounds, where it forms biofilms. Much research has been dedicated to biofilm formation on surfaces; however, in chronic infections, most biofilms form small aggregates of cells not attached to a surface, but embedded in host

  13. Metabolic and Transcriptomic Changes Induced in Arabidopsis by the Rhizobacterium Pseudomonas fluorescens SS1011[W][OA

    Science.gov (United States)

    van de Mortel, Judith E.; de Vos, Ric C.H.; Dekkers, Ester; Pineda, Ana; Guillod, Leandre; Bouwmeester, Klaas; van Loon, Joop J.A.; Dicke, Marcel; Raaijmakers, Jos M.

    2012-01-01

    Systemic resistance induced in plants by nonpathogenic rhizobacteria is typically effective against multiple pathogens. Here, we show that root-colonizing Pseudomonas fluorescens strain SS101 (Pf.SS101) enhanced resistance in Arabidopsis (Arabidopsis thaliana) against several bacterial pathogens, including Pseudomonas syringae pv tomato (Pst) and the insect pest Spodoptera exigua. Transcriptomic analysis and bioassays with specific Arabidopsis mutants revealed that, unlike many other rhizobacteria, the Pf.SS101-induced resistance response to Pst is dependent on salicylic acid signaling and not on jasmonic acid and ethylene signaling. Genome-wide transcriptomic and untargeted metabolomic analyses showed that in roots and leaves of Arabidopsis plants treated with Pf.SS101, approximately 1,910 genes and 50 metabolites were differentially regulated relative to untreated plants. Integration of both sets of “omics” data pointed to a prominent role of camalexin and glucosinolates in the Pf.SS101-induced resistance response. Subsequent bioassays with seven Arabidopsis mutants (myb51, cyp79B2cyp79B3, cyp81F2, pen2, cyp71A12, cyp71A13, and myb28myb29) disrupted in the biosynthesis pathways for these plant secondary metabolites showed that camalexin and glucosinolates are indeed required for the induction of Pst resistance by Pf.SS101. Also for the insect S. exigua, the indolic glucosinolates appeared to play a role in the Pf.SS101-induced resistance response. This study provides, to our knowledge for the first time, insight into the substantial biochemical and temporal transcriptional changes in Arabidopsis associated with the salicylic acid-dependent resistance response induced by specific rhizobacteria. PMID:23073694

  14. Phenazine-1-Carboxylic Acid Production by Pseudomonas fluorescens LBUM636 Alters Phytophthora infestans Growth and Late Blight Development.

    Science.gov (United States)

    Morrison, Christopher K; Arseneault, Tanya; Novinscak, Amy; Filion, Martin

    2017-03-01

    Phytophthora infestans causes late blight of potato, one of the most devastating diseases affecting potato production. Alternative approaches for controlling late blight are being increasingly sought due to increasing environmental concerns over the use of chemical pesticides and the increasing resistance of P. infestans to fungicides. Our research group has isolated a new strain of Pseudomonas fluorescens (LBUM636) of biocontrol interest producing the antibiotic phenazine-1-carboxylic acid (PCA). Wild-type LBUM636 was shown to significantly inhibit the growth of Phytophthora infestans in in vitro confrontational assays whereas its isogenic mutant (phzC-; not producing PCA) only slightly altered the pathogen's growth. Wild-type LBUM636 but not the phzC- mutant also completely repressed disease symptom development on tubers. A pot experiment revealed that wild-type LBUM636 can significantly reduce P. infestans populations in the rhizosphere and in the roots of potato plants, as well as reduce in planta disease symptoms due to PCA production. The expression of eight common plant defense-related genes (ChtA, PR-1b, PR-2, PR-5, LOX, PIN2, PAL-2, and ERF3) was quantified in tubers, roots, and leaves by reverse-transcription quantitative polymerase chain reaction and revealed that the biocontrol observed was not associated with the induction of a plant defense response by LBUM636. Instead, a direct interaction between P. infestans and LBUM636 is required and PCA production appears to be a key factor for LBUM636's biocontrol ability.

  15. A novel psychrophilic lipase from Pseudomonas fluorescens with unique property in chiral resolution and biodiesel production via transesterification.

    Science.gov (United States)

    Luo, Yu; Zheng, Yitao; Jiang, Zhengbing; Ma, Yushu; Wei, Dongzhi

    2006-11-01

    A lipase-producing bacterium strain B68 screened from soil samples of China was identified as Pseudomonas fluorescens. With GenomeWalker, the open reading frame of lipase gene lipB68, encoding 476 amino acids, was cloned and expressed in Escherichia coli BL21 (DE3). By affinity chromatography, the recombinant LipB68 protein was purified to the purity of 95%. As a member of lipase subfamily I.3, LipB68 has a unique optimum temperature of 20 degrees C, which was the lowest in this subfamily. In chiral resolution, LipB68 effectively catalyzed the transesterification of both alpha-phenylethanol and alpha-phenylpropanol at 20 degrees C, achieving E values greater than 100 and 60 after 120 h, respectively. Among all the known catalysts in biodiesel production, LipB68 produced biodiesel with a yield of 92% after 12 h, at the lowest temperature of 20 degrees C, and is the first one of the I.3 lipase subfamily reported to be capable of catalyzing the transesterification reaction of biodiesel production. Since lipase-mediated biodiesel production is normally carried out at 35-50 degrees C, the availability of a highly active lipase with a low optimal temperature can provide substantial savings in energy consumption. Thus, this novel psychrophilic lipase (LipB68) may represent a highly competitive energy-saving biocatalyst.

  16. A novel psychrophilic lipase from Pseudomonas fluorescens with unique property in chiral resolution and biodiesel production via transesterification

    Energy Technology Data Exchange (ETDEWEB)

    Luo Yu; Zheng Yitao; Jiang Zhengbing; Ma Yushu; Wei Dongzhi [East China Univ. of Science and Tech., Shanghai (China). State Key Lab. of Bioreactor Engineering

    2006-11-15

    A lipase-producing bacterium strain B68 screened from soil samples of China was identified as Pseudomonas fluorescens. With GenomeWalker, the open reading frame of lipase gene lipB68, encoding 476 amino acids, was cloned and expressed in Escherichia coli BL21 (DE3). By affinity chromatography, the recombinant LipB68 protein was purified to the purity of 95%. As a member of lipase subfamily I.3, LipB68 has a unique optimum temperature of 20 C, which was the lowest in this subfamily. In chiral resolution, LipB68 effectively catalyzed the transesterification of both a-phenylethanol and a-phenylpropanol at 20 C, achieving E values greater than 100 and 60 after 120 h, respectively. Among all the known catalysts in biodiesel production, LipB68 produced biodiesel with a yield of 92% after 12 h, at the lowest temperature of 20 C, and is the first one of the I.3 lipase subfamily reported to be capable of catalyzing the transesterification reaction of biodiesel production. Since lipasemediated biodiesel production is normally carried out at 35-50 C, the availability of a highly active lipase with a low optimal temperature can provide substantial savings in energy consumption. Thus, this novel psychrophilic lipase (LipB68) may represent a highly competitive energy-saving biocatalyst. (orig.)

  17. A ptsP deficiency in PGPR Pseudomonas fluorescens SF39a affects bacteriocin production and bacterial fitness in the wheat rhizosphere.

    Science.gov (United States)

    Godino, Agustina; Príncipe, Analía; Fischer, Sonia

    2016-04-01

    Pseudomonas fluorescens SF39a is a plant-growth-promoting bacterium isolated from wheat rhizosphere. In this report, we demonstrate that this native strain secretes bacteriocins that inhibit growth of phytopathogenic strains of the genera Pseudomonas and Xanthomonas. An S-type pyocin gene was detected in the genome of strain SF39a and named pys. A non-polar pys::Km mutant was constructed. The bacteriocin production was impaired in this mutant. To identify genes involved in bacteriocin regulation, random transposon mutagenesis was carried out. A miniTn5Km1 mutant, called P. fluorescens SF39a-451, showed strongly reduced bacteriocin production. This phenotype was caused by inactivation of the ptsP gene which encodes a phosphoenolpyruvate phosphotransferase (EI(Ntr)) of the nitrogen-related phosphotransferase system (PTS(Ntr)). In addition, this mutant showed a decrease in biofilm formation and protease production, and an increase in surface motility and pyoverdine production compared with the wild-type strain. Moreover, we investigated the ability of strain SF39a-451 to colonize the wheat rhizosphere under greenhouse conditions. Interestingly, the mutant was less competitive than the wild-type strain in the rhizosphere. To our knowledge, this study provides the first evidence of both the relevance of the ptsP gene in bacteriocin production and functional characterization of a pyocin S in P. fluorescens. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  18. Draft genome sequences of seven 4-Formylaminooxyvinylglycine producers belonging to the Pseudomonas fluorescens species complex

    Science.gov (United States)

    Vinylglycines are non-proteinogenic amino acids that inhibit amino acid metabolism and ethylene production. In this report, we describe the draft genome sequences of seven isolates of Pseudomonas that produce 4-formylaminooxyvinylglycine, a compound known to inhibit the germination of grasses and t...

  19. Biosynthesis of the antimicrobial cyclic lipopeptides nunamycin and nunapeptin by Pseudomonas fluorescens strain In5 is regulated by the LuxR-type transcriptional regulator NunF

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Phippen, Christopher; Nielsen, Kristian Fog

    2017-01-01

    Nunamycin and nunapeptin are two antimicrobial cyclic lipopeptides (CLPs) produced by Pseudomonas fluorescens In5 and synthesized by nonribosomal synthetases (NRPS) located on two gene clusters designated the nun-nup regulon. Organization of the regulon is similar to clusters found in other CLP......-producing pseudomonads except for the border regions where putative LuxR-type regulators are located. This study focuses on understanding the regulatory role of the LuxR-type-encoding gene nunF in CLP production of P. fluorescens In5. Functional analysis of nunF coupled with liquid chromatography-high-resolution mass...... spectrometry (LC-HRMS) showed that CLP biosynthesis is regulated by nunF. Quantitative real-time PCR analysis indicated that transcription of the NRPS genes catalyzing CLP production is strongly reduced when nunF is mutated indicating that nunF is part of the nun-nup regulon. Swarming and biofilm formation...

  20. Biocidal Activity of Formaldehyde and Nonformaldehyde Biocides toward Mycobacterium immunogenum and Pseudomonas fluorescens in Pure and Mixed Suspensions in Synthetic Metalworking Fluid and Saline

    Science.gov (United States)

    Selvaraju, Suresh B.; Khan, Izhar U. H.; Yadav, Jagjit S.

    2005-01-01

    The microbicidal activity of four different biocides was studied in synthetic metalworking fluid (MWF) against Mycobacterium immunogenum, a suspected causative agent for hypersensitivity pneumonitis, and Pseudomonas fluorescens, a representative for the predominant gram-negative bacterial contaminants of MWF. The results indicated that M. immunogenum is more resistant than P. fluorescens to the tested formaldehyde-releasing biocides (Grotan and Bioban), isothiazolone (Kathon), and phenolic biocide (Preventol). Kathon was effective against mycobacteria at lower concentrations than the other three test biocides in MWF. In general, there was a marked increase in biocidal resistance of both the test organisms when present in MWF matrix compared to saline. Increased resistance of the two test organisms to biocides was observed when they were in a mixed suspension (1:1 ratio). The results indicate the protective effect of the MWF matrix against the action of commonly used biocides on the MWF-colonizing microbial species of occupational health significance, including mycobacteria. PMID:15640232

  1. Survival of Escherichia coli o157:h7 co-cultured with different levels of pseudomonas fluorescens and lactobacillus plantarum on fresh beef

    Science.gov (United States)

    Tshabalala, P. A.; de Kock, H. L.; Buys, E. M.

    2012-01-01

    The purpose of this study was to investigate the effect of different levels of Pseudomonas fluorescens (102 and 106 log10 cfu/ml) and Lactobacillus plantarum (102 and 104 log10 cfu/ml) on the growth of Escherichia coli O157:H7 on beef loins. Beef loins inoculated with E. coli O157:H7 and P. fluorescens were aerobically stored for 7 days at 4 ºC, while those inoculated with E. coli O157:H7 and L. plantarum were vacuum packaged and stored for 8 weeks at 4 ºC. Aerobic Plate Counts (APC), E. coli O157:H7 and either P. fluorescens or L. plantarum counts were determined at different storage intervals. For the aerobically packaged beef loins, E. coli O157:H7 was detected throughout the 7 day storage period regardless of the P. fluorescens level in the inoculum. For the vacuum packaged beef loins, similar inoculum levels of E. coli O157:H7 and L. plantarum allowed E. coli O157:H7 to survive until week 5 of storage, while a higher inoculum level of L. plantarum inhibited E. coli O157:H7 from week 3. Once fresh beef has been contaminated with E. coli O157:H7, the level of P. fluorescens in the background flora does not inhibit its survival and growth. However, under vacuum storage, the application of L. plantarum as a biopreservative inhibits the survival of E. coli O157:H7 on beef. The higher the level of L. plantarum in the system, the earlier the onset of the inhibition. Farmers and abattoirs have to strengthen preventive strategies to eliminate contamination of beef carcasses with E. coli O157:H7. PMID:24031970

  2. Phenol biodegradation by immobilized Pseudomonas putida FNCC-0071 cells in alginate beads

    Science.gov (United States)

    Hakim, Lukman Nul; Rochmadi, Sutijan

    2017-06-01

    Phenol is one of industrial liquid waste which is harmful to the environment, so it must be degraded. It can be degraded by immobilized Pseudomonas putida FNCC-0071 cells. It needs the kinetics and mass transfer data to design this process which can be estimated by the proposed dynamic model in this study. This model involves simultaneous diffusion and reaction in the alginate bead and liquid bulk. The preliminary stage of phenol biodegradation process was acclimatization cells. This is the stage where cells were acclimated to phenol as carbon source (substrate). Then the acclimated cells were immobilized in alginate beads by extrusion method. The variation of the initial phenol concentration in the solution is 350 to 850 ppm where 60 g alginate bead contained by cells loaded into its solution in reactor batch, so then biodegradation occurs. In this study, the average radius of alginate bead was 0.152 cm. The occurred kinetic reaction process can be explained by Blanch kinetic model with the decreasing of parameter μmax' while the increasing values of initial phenol concentration in the same time, but the parameters KM, KM', and kt were increasing by the rising values of initial phenol concentration. The value of the parameter β is almost zero. Effective diffusivity of phenol and cells are 1.11 × 10-5±4.5% cm2 s-1 and 1.39 × 10-7± 0.04% cm2 s-1. The partition coefficient of phenol and cells are 0.39 ± 15% and 2.22 ± 18%.

  3. Reduction of Fusarium wilt in watermelon by Pseudomonas chlororaphis PCL1391 and P. fluorescens WCS365

    Directory of Open Access Journals (Sweden)

    G.T. Tziros

    2007-12-01

    Full Text Available Fusarium wilt of watermelon (Citrullus lanatus caused by Fusarium oxysporum f. sp. niveum is a devastatine soil-borne disease that causes extensive losses throughout the world. Two known Pseudomonas biocontrol strains were used separately and in combination to assess their antagonistic effectiveness against F. oxysporum f. sp. niveum in pot experiments. P. chlororaphis PCL1391 signifi cantly reduced disease severity. P. fl uorescens WCS365 was less effective in disease suppression, while a combination of the two bacteria had intermediate effects. The biological control of Fusarium wilt with P. chlororaphis offers a potentially useful tool in an integrated pest management program to control Fusarium wilt of watermelon.

  4. Investigation for zoonotic disease pathogens (Aeromonas hydrophila, Pseudomonas fluorescens, Streptococcus iniae) seen in carp farms in Duhok region of Northern Iraq by molecular methods

    Science.gov (United States)

    Mohammed, Kamiran Abdulrahman; Arabacı, Muhammed; Önalan, Şükrü

    2017-04-01

    The aim of this study was to determine the zoonotic bacteria in carp farms in Duhok region of the Northern Iraq. Carp is the main fish species cultured in the Duhok region. The most common zoonotic bacteria generally seen in carp farms are Aeromonas hydrophila, Pseudomonas fluorescens and Streptococcus iniae. Samples were collected from 20 carp farms in the Duhok Region of the Northern Iraq. Six carp samples were collected from each carp farm. Head kidney tissue samples and intestine tissue samples were collected from each carp sample. Than head kidney and intestine tissue samples were pooled. The total bacterial DNA extraction from the pooled each 20 head kidney tissue samples and pooled each 20 intestinal tissue samples. Primers for pathogens were originally designed from 16S Ribosomal gene region. Zoonotic bacteria were scanned in all tissue samples by absent / present analysis in the RT-PCR. After RT-PCR, Capillary gel electrophoresis bands were used for the confirmation of the size of amplicon which was planned during primer designing stage. As a result, one sample was positive in respect to Aeromonas hydrophila, from intestine and one carp farm was positive in respect to Pseudomonas fluorescens from intestine and two carp farms were positive in respect to Streptococcus iniae. Totally 17 of 20 carp farms were negative in respect to the zoonotic bacteria. In conclusion the zoonotic bacteria were very low (15 %) in carp farms from the Duhok Region in the Northern Iraq. Only in one Carp farms, both Aeromonas hydrophila and Pseudomonas fluorescens were positive. Also Streptococcus inia were positive in two carp farms.

  5. Toluene promotes lid 2 interfacial activation of cold active solvent tolerant lipase from Pseudomonas fluorescens strain AMS8.

    Science.gov (United States)

    Yaacob, Norhayati; Mohamad Ali, Mohd Shukuri; Salleh, Abu Bakar; Rahman, Raja Noor Zaliha Raja Abdul; Leow, Adam Thean Chor

    2016-07-01

    The utilization of cold active lipases in organic solvents proves an excellent approach for chiral synthesis and modification of fats and oil due to the inherent flexibility of lipases under low water conditions. In order to verify whether this lipase can function as a valuable synthetic catalyst, the mechanism concerning activation of the lid and interacting solvent residues in the presence of organic solvent must be well understood. A new alkaline cold-adapted lipase, AMS8, from Pseudomonas fluorescens was studied for its structural adaptation and flexibility prior to its exposure to non-polar, polar aprotic and protic solvents. Solvents such as ethanol, toluene, DMSO and 2-propanol showed to have good interactions with active sites. Asparagine (Asn) and tyrosine (Tyr) were key residues attracted to solvents because they could form hydrogen bonds. Unlike in other solvents, Phe-18, Tyr-236 and Tyr-318 were predicted to have aromatic-aromatic side-chain interactions with toluene. Non-polar solvent also was found to possess highest energy binding compared to polar solvents. Due to this circumstance, the interaction of toluene and AMS8 lipase was primarily based on hydrophobicity and molecular recognition. The molecular dynamic simulation showed that lid 2 (residues 148-167) was very flexible in toluene and Ca(2+). As a result, lid 2 moves away from the catalytic areas, leaving an opening for better substrate accessibility which promotes protein activation. Only a single lid (lid 2) showed the movement following interactions with toluene, although AMS8 lipase displayed double lids. The secondary conformation of AMS8 lipase that was affected by toluene observed a reduction of helical strands and increased coil structure. Overall, this work shows that cold active lipase, AMS8 exhibits distinguish interfacial activation and stability in the presence of polar and non-polar solvents. Copyright © 2016. Published by Elsevier Inc.

  6. The biocontrol endophytic bacterium Pseudomonas fluorescens PICF7 induces systemic defense responses in aerial tissues upon colonization of olive roots

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    Carmen eGómez-Lama Cabanás

    2014-09-01

    Full Text Available Pseudomonas fluorescens PICF7, a native olive root endophyte and effective biocontrol agent (BCA against Verticillium wilt of olive, is able to trigger a broad range of defense responses in root tissues of this woody plant. In order to elucidate whether strain PICF7 also induces systemic defense responses in above-ground organs, aerial tissues of olive plants grown under non-gnotobiotic conditions were collected at different time points after root bacterization with this endophytic BCA. A suppression subtractive hybridization (SSH cDNA library, enriched in up-regulated genes, was generated. This strategy enabled the identification of 376 ESTs (99 contigs and 277 singlets, many of them related to response to different stresses. Five ESTs, involved in defense responses, were selected to carry out time-course quantitative real-time PCR (qRT-PCR experiments aiming to: (i validate the induction of these genes, and (ii shed light on their expression pattern along time (from 1 to 15 days. Induction of olive genes potentially coding for lypoxigenase 2, catalase, 1-aminocyclopropane-1-carboxylate oxidase and phenylananine ammonia-lyase was thus confirmed at some time points. Computational analysis also revealed that different transcription factors were up-regulated in olive aerial tissues (i.e. jerf, bHLH, WRKYs, as previously reported for roots. Results confirmed that root colonization by this endophytic bacterium does not only trigger defense responses in this organ but also mount a wide array of systemic defense responses in distant tissues (stems, leaves. This sheds light on how olive plants respond to the ‘non-hostile’ colonization by a bacterial endophyte and how induced defense response can contribute to the biocontrol activity of strain PICF7.

  7. Xylanase B and an arabinofuranosidase from Pseudomonas fluorescens subsp. cellulosa contain identical cellulose-binding domains and are encoded by adjacent genes.

    OpenAIRE

    Kellett, L E; Poole, D M; Ferreira, L M; Durrant, A J; Hazlewood, G P; Gilbert, H J

    1990-01-01

    The complete nucleotide sequence of the Pseudomonas fluorescens subsp. cellulosa xynB gene, encoding an endo-beta-1,4-xylanase (xylanase B; XYLB) has been determined. The structural gene consists of an open reading frame (ORF) of 1775 bp coding for a protein of Mr 61,000. A second ORF (xynC) of 1712 bp, which starts 148 bp downstream of xynB, encodes a protein, designated xylanase C (XYLC), of Mr 59,000. XYLB hydrolyses oat spelt xylan to xylobiose and xylose, whereas XYLC releases only arabi...

  8. Characterization of an Endoglucanase from Pseudomonas fluorescens subsp. cellulosa Produced in Escherichia coli and Regulation of the Expression of Its Cloned Gene.

    OpenAIRE

    Lejeune, André; Courtois, Stéphane; Colson, Charles

    1988-01-01

    Several enzymatic properties of an endoglucanase produced in Escherichia coli by a gene from Pseudomonas fluorescens subsp. cellulosa were investigated. Gel filtration revealed a single peak of M(r) 36,000 with endoglucanase activity. The pH optimum of the enzyme was 7.0. Carboxymethyl cellulose and barley beta-glucan (mixed beta-1,3 and 1,4 linkages) were good substrates, but not laminarin (beta-1,3 linkages), amylose, filter paper, microcrystalline cellulose (Avicel), or cellotriose. The mo...

  9. Safety of spray-dried powder formulated Pseudomonas fluorescens strain CL145A exposure to subadult/adult unionid mussels during simulated open-water treatments

    Science.gov (United States)

    Luoma, James A.; Weber, Kerry L.; Waller, Diane L.; Wise, Jeremy K.; Mayer, Denise A.; Aloisi, Douglas B.

    2015-01-01

    The exposure effects of a commercially prepared spray dried powder (SDP) formulation ofPseudomonas fluorescens (strain CL145A) on the survival of seven species of unionid mussels endemic to the Great Lakes and Mississippi River basins was evaluated in this study. The study exposures were completed within replicated 350-liter test tanks contained within a mobile bioassay laboratory sited on the shores of the Black River near La Crosse, Wisconsin. The test tanks were supplied with flowing, filtered river water which was interrupted during the exposure period.

  10. Quantitative and qualitative variability of the caseinolytic potential of different strains of Pseudomonas fluorescens: implications for the stability of casein micelles of UHT milks during their storage.

    Science.gov (United States)

    Baglinière, François; Tanguy, Gaëlle; Jardin, Julien; Matéos, Aurélie; Briard, Valérie; Rousseau, Florence; Robert, Benoît; Beaucher, Eric; Humbert, Gérard; Dary, Annie; Gaillard, Jean Luc; Amiel, Caroline; Gaucheron, Frédéric

    2012-12-15

    Pseudomonas fluorescens grows at low temperature and produces thermo-resistant protease(s) that can destabilize UHT (Ultra High Temperature) milk during its storage. The consequences of contamination of microfiltered milk with 9 strains of P. fluorescens on the stability of the corresponding UHT milk during storage had been investigated in this study. The strains were classified in two groups according to their ability to destabilize UHT milk. For the group of highly destabilizing strains, sedimentations of UHT milks, low values to phosphate test and the presence of aggregates were observed. Zeta potential and hydration of casein micelles decreased, whereas non casein nitrogen (NCN) and non protein nitrogen (NPN) contents increased. The analyses of NCN fraction by liquid chromatography coupled to mass spectrometry indicated that the different casein molecules were hydrolyzed in a similar way for the destabilizing strains suggesting that the same enzyme was implicated. For the group of slightly or not destabilizing strains no visual and biochemical alteration were found. This study showed that destabilization of UHT milk by P. fluorescens was highly variable and strain-dependent. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Investigating the ability of Pseudomonas fluorescens UW4 to reduce cadmium stress in Lactuca sativa via an intervention in the ethylene biosynthetic pathway.

    Science.gov (United States)

    Albano, Lucas J; Macfie, Sheila M

    2016-12-01

    A typical plant response to any biotic or abiotic stress, including cadmium (Cd), involves increased ethylene synthesis, which causes senescence of the affected plant part. Stressed plants can experience reduced ethylene and improved growth if they are inoculated with bacteria that have the enzyme ACC deaminase, which metabolizes the ethylene precursor ACC (1-aminocyclopropane-1-carboxylate). We investigated whether one such bacterium, Pseudomonas fluorescens UW4, reduces the production of ethylene and improves the growth of lettuce (Lactuca sativa) sown in Cd-contaminated potting material (PRO-MIX® BX). Plants were inoculated with the wild-type P. fluorescens UW4 or a mutant strain that cannot produce ACC deaminase. Cadmium-treated plants contained up to 50 times more Cd than did control plants. In noninoculated plants, Cd induced a 5-fold increase in ethylene concentration. The wild-type bacterium prevented Cd-induced reductions in root biomass but there was no relationship between Cd treatment and ethylene production in inoculated plants. In contrast, when the concentration of ethylene was plotted against the extent of bacterial colonization of the roots, increased colonization with wild-type P. fluorescens UW4 was associated with 20% less ethylene production. Ours is the first study to show that the protective effect of this bacterium is proportional to the quantity of bacteria on the root surface.

  12. Colonization process of olive tissues by Verticillium dahliae and its in planta interaction with the biocontrol root endophyte Pseudomonas fluorescens PICF7

    Science.gov (United States)

    Prieto, Pilar; Navarro‐Raya, Carmen; Valverde‐Corredor, Antonio; Amyotte, Stefan G.; Dobinson, Katherine F.; Mercado‐Blanco, Jesús

    2009-01-01

    Summary The colonization process of Olea europaea by the defoliating pathotype of Verticillium dahliae, and the in planta interaction with the endophytic, biocontrol strain Pseudomonas fluorescens PICF7 were determined. Differential fluorescent protein tagging was used for the simultaneous visualization of P. fluorescens PICF7 and V. dahliae in olive tissues. Olive plants were bacterized with PICF7 and then transferred to V. dahliae‐infested soil. Monitoring olive colonization events by V. dahliae and its interaction with PICF7 was conducted using a non‐gnotobiotic system, confocal laser scanner microscopy and tissue vibratoming sections. A yellow fluorescently tagged V. dahliae derivative (VDAT‐36I) was obtained by Agrobacterium tumefaciens‐mediated transformation. Isolate VDAT‐36I quickly colonized olive root surface, successfully invaded root cortex and vascular tissues via macro‐ and micro‐breakages, and progressed to the aerial parts of the plant through xylem vessel cells. Strain PICF7 used root hairs as preferred penetration site, and once established on/in root tissues, hindered pathogen colonization. For the first time using this approach, the entire colonization process of a woody plant by V. dahliae is reported. Early and localized root surface and root endophytic colonization by P. fluorescens PICF7 is needed to impair full progress of verticillium wilt epidemics in olive. PMID:21255281

  13. Membrane-anchored MucR mediates nitrate-dependent regulation of alginate production in Pseudomonas aeruginosa

    KAUST Repository

    Wang, Yajie

    2015-04-29

    Alginates exhibit unique material properties suitable for medical and industrial applications. However, if produced by Pseudomonas aeruginosa, it is an important virulence factor in infection of cystic fibrosis patients. The alginate biosynthesis machinery is activated by c-di-GMP imparted by the inner membrane protein, MucR. Here, it was shown that MucR impairs alginate production in response to nitrate in P. aeruginosa. Subsequent site-specific mutagenesis of MucR revealed that the second MHYT sensor motif (MHYT II, amino acids 121–124) of MucR sensor domain was involved in nitrate sensing. We also showed that both c-di-GMP synthesizing and degrading active sites of MucR were important for alginate production. Although nitrate and deletion of MucR impaired alginate promoter activity and global c-di-GMP levels, alginate yields were not directly correlated with alginate promoter activity or c-di-GMP levels, suggesting that nitrate and MucR modulate alginate production at a post-translational level through a localized pool of c-di-GMP. Nitrate increased pel promoter activity in the mucR mutant while in the same mutant the psl promoter activity was independent of nitrate. Nitrate and deletion of mucR did not impact on swarming motility but impaired attachment to solid surfaces. Nitrate and deletion of mucR promoted the formation of biofilms with increased thickness, cell density, and survival. Overall, this study provided insight into the functional role of MucR with respect to nitrate-mediated regulation of alginate biosynthesis. © 2015 Springer-Verlag Berlin Heidelberg

  14. PRODUCTION AND CHARACTERIZATION OF BIOSURFACTANT BY Pseudomonas fluorescens USING CASSAVA FLOUR WASTEWATER AS MEDIA

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    Venty Suryanti

    2013-12-01

    Full Text Available Biosurfactant with efficient emulsification properties could be produced by Pseudomonas flourescens using cassava flour wastewater (manipueira as media. The ability of P. flourescens to produce biosurfactant could suggest potential use in industrial and environmental applications. Media containing a mixture of natural manipueira and nutrient broth with 48 h fermentation was the optimum condition for the biosurfactant production. Based on UV-Vis and FT-IR spectra, the biosurfactant was indicated as rhamnolipids containing hydroxyl, ester, carboxylic and aliphatic carbon chain functional groups. Biosurfactant exhibited critical micelle concentration (CMC value of 715 mg/L and reduced the surface tension of the water from 80 mN/m to 59 mN/m. The biosurfactant was able to decrease the interfacial tension about 51-70% when benzyl chloride, palm oil and kerosene were used as water-immiscible compounds. The biosurfactant was able to form stable emulsion until 30 days when paraffin, soybean oil, lubricant oil and kerosene were used as water-immiscible compounds.

  15. Factors screening to statistical experimental design of racemic atenolol kinetic resolution via transesterification reaction in organic solvent using free Pseudomonas fluorescens lipase.

    Science.gov (United States)

    Agustian, Joni; Kamaruddin, Azlina Harun; Aboul-Enein, Hassan Y

    2017-07-01

    As the (R)-enantiomer of racemic atenolol has no β-blocking activity and no lack of side effects, switching from the racemate to the (S)-atenolol is more favorable. Transesterification of racemic atenolol using free enzymes investigated as a resource to resolve the racemate via this method is limited. Screenings of enzyme, medium, and acetyl donor were conducted first to give Pseudomonas fluorescens lipase, tetrahydrofuran, and vinyl acetate. A statistical design of the experiment was then developed using Central Composite Design on some operational factors, which resulted in the conversions of 11.70-61.91% and substrate enantiomeric excess (ee) of 7.31-100%. The quadratic models are acceptable with R 2 of 95.13% (conversion) and 89.63% (ee). The predicted values match the observed values reasonably well. Temperature, agitation speed, and substrate molar ratio factor have low effects on conversion and ee, but enzyme loading affects the responses highly. The interaction of temperature-agitation speed and temperature-substrate molar ratio show significant effects on conversion, while temperature-agitation speed, temperature-substrate molar ratio, and agitation speed-substrate molar ratio affect ee highly. Optimum conditions for the use of Pseudomonas fluorescens lipase, tetrahydrofuran, and vinyl acetate were found at 45°C, 175 rpm, 2000 U, and 1:3.6 substrate molar ratio. © 2017 Wiley Periodicals, Inc.

  16. A full-length Plasmodium falciparum recombinant circumsporozoite protein expressed by Pseudomonas fluorescens platform as a malaria vaccine candidate.

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    Amy R Noe

    Full Text Available The circumsporozoite protein (CSP of Plasmodium falciparum is a major surface protein, which forms a dense coat on the sporozoite's surface. Preclinical research on CSP and clinical evaluation of a CSP fragment-based RTS, S/AS01 vaccine have demonstrated a modest degree of protection against P. falciparum, mediated in part by humoral immunity and in part by cell-mediated immunity. Given the partial protective efficacy of the RTS, S/AS01 vaccine in a recent Phase 3 trial, further improvement of CSP-based vaccines is crucial. In this report, we describe the preclinical development of a full-length, recombinant CSP (rCSP-based vaccine candidate against P. falciparum malaria suitable for current Good Manufacturing Practice (cGMP production. Utilizing a novel high-throughput Pseudomonas fluorescens expression platform, we demonstrated greater efficacy of full-length rCSP as compared to N-terminally truncated versions, rapidly down-selected a promising lead vaccine candidate, and developed a high-yield purification process to express immunologically active, intact antigen for clinical trial material production. The rCSP, when formulated with various adjuvants, induced antigen-specific antibody responses as measured by enzyme-linked immunosorbent assay (ELISA and immunofluorescence assay (IFA, as well as CD4+ T-cell responses as determined by ELISpot. The adjuvanted rCSP vaccine conferred protection in mice when challenged with transgenic P. berghei sporozoites containing the P. falciparum repeat region of CSP. Furthermore, heterologous prime/boost regimens with adjuvanted rCSP and an adenovirus type 35-vectored CSP (Ad35CS showed modest improvements in eliciting CSP-specific T-cell responses and anti-malarial protection, depending on the order of vaccine delivery. Collectively, these data support the importance of further clinical development of adjuvanted rCSP, either as a stand-alone product or as one of the components in a heterologous prime

  17. Removal of aldrin, dieldrin, heptachlor, and heptachlor epoxide using activated carbon and/or Pseudomonas fluorescens free cell cultures.

    Science.gov (United States)

    Bandala, Erick R; Andres-Octaviano, Juan; Pastrana, Paulino; Torres, Luis G

    2006-01-01

    Degradation of aldrin (1,2,3,4,10,10-Hexachloro-1,4,4a,5,8,8a-hexahydro-1,4:5-8-dimethanonaphthalene), heptachlor (1H-1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-methano indene), dieldrin (1aalpha,2beta,2aalpha,3beta,6beta,6aalpha,7beta,7aalpha)-3,4,5,6,9,9-Hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-d-methanonaphtha[2,3-b]oxirene, and heptachlor epoxide (1aalpha, 1bbeta,2alpha,5alpha,5alphabeta,6beta,6aalpha-2,3,4,5,6,7,7-Heptachloro-1a,1b,5,5a,6,6a-hexahydro-2,5-methano-2H-inden[1,2-b]-oxirene) was tested using free cultures of Pseudomonas fluorescens under controlled conditions. Pesticide concentrations were monitored by gas chromatography during 120 h. Percentages of degradation and biodegradation rates (BDR) were calculated. Data showed a trend suggesting a relation between chemical structure and degradability. Degradation kinetics for each pesticide tested showed that the highest degradation rates were found in the first 24 h. Kinetics data were adjusted to an empirical equation in order to predict their behavior, and the correlation coefficients obtained were satisfactory. Gas chromatography/mass spectrometry (GC/MS) analysis of the final extracts allowed the identification of chlordene and monodechlorodieldrin, which have been reported as final metabolite produced in the biodegradation of this kind of compounds. Regarding adsorption of pesticides on activated vegetal carbon, we concluded that removal efficiencies between 95.45 and 97.18% can be reached, depending on the pesticide and the carbon dose applied. The values for K from the Freundlich equation were quite similar for the four pesticides (between 1.0001 and 1.04), whereas the n values were quite different for each pesticide in the following order of affinity: dieldrin > aldrin > heptachlor epoxide > heptachlor. Equilibrium times, very important for scaling up the process, were between 43 min and 1 h, for the heptachlor epoxide and the heptachlor, respectively.

  18. A comparison between Pseudomonas aureofaciens (chlororaphis and P. fluorescens in biological control of cotton seedling damping-off disease

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    Samaneh Samavat

    2014-07-01

    Full Text Available Due to the importance of the biological control of plant diseases, testing and introducing new biocontrol-active microorganisms is a major concern among plant pathologists. The causal agent of cotton seedling damping-off disease is Rhizoctonia solani. In this regard, we tried to investigate the antagonistic activities of Pseudomonas aureofaciens (chlororaphis 30–84 (phenazine producing wild type and non-phenazine producing mutant strains on R. solani, in comparison with some isolates of P. fluorescent under both in vitro (laboratory and in vivo (greenhouse conditions. In the laboratory experiment, the inhibitory effects of all the bacteria, on the growth of R. solani, were evaluated using the dual culture procedure. Results showed that five isolates of P. fluorescent along with both strains of P. aureofaciens significantly inhibited the growth of R. solani. Effective bacterial antagonists were then evaluated in a greenhouse experiment where cotton seeds were coated with their suspensions and were sown in pasteurised field-soil. The soil had been pre-inoculated with a virulent isolate of R. solani. The efficacy of the bacterial antagonists was evaluated by counting the number of surviving seedlings in different treatments, at 15 and 60 days after sowing, for determining pre- and post-emergence damping-off incidence. According to the results of the greenhouse experiment, at both intervals, two isolates of P. fluorescens along with both strains of P. aureofaciens caused significant increases in the number of healthy seedlings, in comparison with the untreated control, and a commonly used fungicide (carboxin-thiram. The efficacy of phenazine producing a wild type strain of P. aureofaciens was higher than its non-phenazine producing mutant, indicating that phenazine plays an important role in the antagonistic activity of P. aureofaciens. Effective bacterial antagonists were then studied for their antagonistic mechanisms. The results showed that all

  19. Genome Analysis of Pseudomonas fluorescens PCL1751: A Rhizobacterium that Controls Root Diseases and Alleviates Salt Stress for Its Plant Host.

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    Shu-Ting Cho

    Full Text Available Pseudomonas fluorescens PCL1751 is a rod-shaped Gram-negative bacterium isolated from the rhizosphere of a greenhouse-grown tomato plant in Uzbekistan. It controls several plant root diseases caused by Fusarium fungi through the mechanism of competition for nutrients and niches (CNN. This mechanism does not rely on the production of antibiotics, so it avoids the concerns of resistance development and is environmentally safe. Additionally, this bacterium promotes plant growth by alleviating salt stress for its plant host. To investigate the genetic mechanisms that may explain these observations, we determined the complete genome sequence of this bacterium, examined its gene content, and performed comparative genomics analysis with other Pseudomonas strains. The genome of P. fluorescens PCL1751 consisted of one circular chromosome that is 6,143,950 base-pairs (bp in size; no plasmid was found. The annotation included 19 rRNA, 70 tRNA, and 5,534 protein-coding genes. The gene content analysis identified a large number of genes involved in chemotaxis and motility, colonization of the rhizosphere, siderophore biosynthesis, and osmoprotectant production. In contrast, the pathways involved in the biosynthesis of phytohormones or antibiotics were not found. Comparison with other Pseudomonas genomes revealed extensive variations in their genome size and gene content. The presence and absence of secretion system genes were highly variable. As expected, the synteny conservation among strains decreased as a function of phylogenetic divergence. The integration of prophages appeared to be an important driver for genome rearrangements. The whole-genome gene content analysis of this plant growth-promoting rhizobacterium (PGPR provided some genetic explanations to its phenotypic characteristics. The extensive and versatile substrate utilization pathways, together with the presence of many genes involved in competitive root colonization, provided further support

  20. Kynureninase-Type enzymes of Penicillum roqueforti, Aspergillus niger, Rhizopus stolonifer, and Pseudomonas fluorescens: further evidence for distinct kynureninase and hydroxykynureninase activities.

    Science.gov (United States)

    Shetty, A S; Gaertner, F H

    1975-04-01

    The kynureninase-type enzymes of three fungi and one bacterium were isolated and examined kinetically for their ability to catalyze the hydrolysis of L-kynurenine and L-3-hydroxykynurenine. The phycomycete Rhizopus stolonifer was found to contain a single, constitutive enzyme with Km for L-3-hydroxykynurenine and L-kynurenine of 6.67 times 10-minus 6 and 2.5 times 10-minus 4 M, respectively. The ascomycetes Aspergillus niger and Penicillium roqueforti each contain an enzyme, induced by L-tryptophan, with similar Km for L-3-hydroxykynurenine and L-kynurenine ranging from 5.9 times 10-minus 5 to 14.3 times 10-minus 5 M, as well as a constitutive enzyme with Km for the two substrates of similar to 4 times 10-minus 6 M and 10-minus 4 M. The bacterium Pseudomonas fluorescens has a single, inducible enzyme with Km for L-3-hydroxykynurenine and L-kynurenine of 5 times 10-minus 4 and 7 times 10-minus 5 M. In addition, significant differences in maximal velocities (Vmax) were observed in two cases. The Vmax of the inducible activity from P. fluorescens was 4.5 times greater for L-kynurenine than L-3-hydroxykynurenine, whereas the Vmax of the constitutive activity from R. stolonifer was 2.5 times greater for L-3-hydroxykynurenine. It is concluded (i) that the constitutive activities are hydroxykynureninases involved in the biosynthesis of nicotinamide adenine dinucleotide from L-tryptophan, (ii) that the inducible activities are kynureninases involved in the catabolism of L-tryptophan to anthranilate, and (iii) that R. stolonifer and P. fluorescens, respectively, carry the most specific examples of each type of enzyme.

  1. Expression of the translocator protein (TSPO from Pseudomonas fluorescens Pfo-1 requires the stress regulatory sigma factors AlgU and RpoH

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    Charlène eLeneveu-Jenvrin

    2015-09-01

    Full Text Available The translocator protein (TSPO, previously designated as peripheral-type benzodiazepine receptor, is an evolutionary conserved protein that is found in many Eukarya, Archae and Bacteria, in which it plays several important functions including for example membrane biogenesis, signaling and stress response. A tspo homologue gene has been identified in several members of the Pseudomonas genus, among which the soil bacterium P. fluorescens Pf0-1. In this bacterium, the tspo gene is located in the vicinity of a putative hybrid histidine kinase-encoding gene. Since tspo has been involved in water stress related response in plants, we explored the effects of hyperosmolarity and temperature on P. fluorescens Pf0-1 tspo expression using a strategy based on lux-reporter fusions. We show that the two genes Pfl01_2810 and tspo are co-transcribed forming a transcription unit. The expression of this operon is growth phase-dependent and is increased in response to high concentrations of NaCl, sucrose and to a D-cycloserine treatment, which are conditions leading to activity of the major cell wall stress responsive extracytoplasmic sigma factor AlgU. Interestingly, the promoter region activity is strongly lowered in a P. aeruginosa algU mutant, suggesting that AlgU may be involved at least partly in the molecular mechanism leading to Pfl01_2810-tspo expression. In silico analysis of this promoter region failed to detect an AlgU consensus binding site; however, we detect a putative binding site for the heat shock response RpoH sigma factor. Accordingly, the promoter activity of the region containing this sequence is increased in response to high growth temperature and slightly lowered in a P. aeruginosa rpoH mutant strain. Taken together, our data suggest that P. fluorescens tspo gene may belong at least partly to the cell wall stress response.

  2. Pseudomonas fluorescens ATCC 13525 containing an artificial oxalate operon and Vitreoscilla hemoglobin secretes oxalic acid and solubilizes rock phosphate in acidic alfisols.

    Directory of Open Access Journals (Sweden)

    Kavita Yadav

    Full Text Available Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah, Fomitopsis plaustris oxalate transporter (FpOAR and Vitreoscilla hemoglobin (vgb in various combinations. Pf (pKCN2 transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4 secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2 transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2 containing artificial oxalate operon (plac-FpOAR-oah and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil.

  3. Xylanase B and an arabinofuranosidase from Pseudomonas fluorescens subsp. cellulosa contain identical cellulose-binding domains and are encoded by adjacent genes.

    Science.gov (United States)

    Kellett, L E; Poole, D M; Ferreira, L M; Durrant, A J; Hazlewood, G P; Gilbert, H J

    1990-12-01

    The complete nucleotide sequence of the Pseudomonas fluorescens subsp. cellulosa xynB gene, encoding an endo-beta-1,4-xylanase (xylanase B; XYLB) has been determined. The structural gene consists of an open reading frame (ORF) of 1775 bp coding for a protein of Mr 61,000. A second ORF (xynC) of 1712 bp, which starts 148 bp downstream of xynB, encodes a protein, designated xylanase C (XYLC), of Mr 59,000. XYLB hydrolyses oat spelt xylan to xylobiose and xylose, whereas XYLC releases only arabinose from the same substrate. Thus XYLB is a typical xylanase and XYLC is an arabinofuranosidase. Both enzymes bind to crystalline cellulose (Avicel), but not to xylan. The nucleotide sequences between residues 114 and 931 of xynB and xynC were identical, as were amino acid residues 39-311 of XYLB and XYLC. This conserved sequence is reiterated elsewhere in the P. fluorescens subsp. cellulosa genome. Truncated derivatives of XYLB and XYLC, in which the conserved sequence had been deleted, retained catalytic activity, but did not exhibit cellulose binding. A hybrid gene in which the 5' end of xynC, encoding residues 1-110 of XYLC, was fused to the Escherichia coli pho A' gene (encodes mature alkaline phosphatase) directed the synthesis of a fusion protein which exhibited alkaline phosphatase activity and bound to cellulose.

  4. Characterization of an Endoglucanase from Pseudomonas fluorescens subsp. cellulosa Produced in Escherichia coli and Regulation of the Expression of Its Cloned Gene.

    Science.gov (United States)

    Lejeune, A; Courtois, S; Colson, C

    1988-02-01

    Several enzymatic properties of an endoglucanase produced in Escherichia coli by a gene from Pseudomonas fluorescens subsp. cellulosa were investigated. Gel filtration revealed a single peak of M(r) 36,000 with endoglucanase activity. The pH optimum of the enzyme was 7.0. Carboxymethyl cellulose and barley beta-glucan (mixed beta-1,3 and 1,4 linkages) were good substrates, but not laminarin (beta-1,3 linkages), amylose, filter paper, microcrystalline cellulose (Avicel), or cellotriose. The mode of action was typical of an "endo"-acting enzyme. Taken together, these properties do not correspond to those of any of the endoglucanases described in P. fluorescens subsp. cellulosa. Consequently, the gene was designated egIX. The enzyme was sensitive to end-product inhibition by cellobiose but was only moderately inhibited by glucose. The enzyme was formed constitutively in E. coli throughout the growth phase. Urea had no effect on endoglucanase synthesis, but glucose acted as a catabolite repressor. The formation of the enzyme in E. coli was partially dependent on cyclic AMP.

  5. The N-terminal region of an endoglucanase from Pseudomonas fluorescens subspecies cellulosa constitutes a cellulose-binding domain that is distinct from the catalytic centre.

    Science.gov (United States)

    Gilbert, H J; Hall, J; Hazlewood, G P; Ferreira, L M

    1990-05-01

    The substrate specificity of an endoglucanase (EGB) from Pseudomonas fluorescens subspecies cellulosa was determined. The enzyme was most active against barley beta-glucan, but showed significant activity against amorphous and crystalline cellulose. EGB was purified to homogeneity by affinity chromatography with crystalline cellulose (Avicel). The Mr of the purified enzyme was 50,000, which is in good agreement with the size of EGB deduced from the nucleotide sequence of the celB gene, coding for EGB. The N-terminal region of the mature form of EGB showed strong homology to another endoglucanase and to a xylanase expressed by the same organism; homologous sequences included highly conserved serine-rich regions. Truncated forms of celB, in which the gene sequence encoding the conserved domain had been deleted, directed the synthesis of a functional endoglucanase that did not bind to crystalline cellulose. This indicates that the conserved region of endoglucanases and xylanases expressed by P. fluorescens subsp. cellulosa constitutes a cellulose-binding domain, which is distinct from the active centre. The possible role of this substrate-binding region is discussed.

  6. Methylobacterium sp. resides in unculturable state in potato tissues in vitro and becomes culturable after induction by Pseudomonas fluorescens IMGB163.

    Science.gov (United States)

    Podolich, O; Laschevskyy, V; Ovcharenko, L; Kozyrovska, N; Pirttilä, A M

    2009-03-01

    To induce growth of endophytic bacteria residing in an unculturable state in tissues of in vitro-grown potato plantlets. To isolate and identify the induced bacteria and to localize the strains in tissues of in vitro-grown potato plantlets. The inoculation of in vitro-grown potato plants with Pseudomonas fluorescens IMBG163 led to induction of another bacterium, a pink-pigmented facultative methylotroph that was identified as Methylobacterium sp. using phylogenetic 16S rDNA approach. Two molecular methods were used for localizing methylobacteria in potato plantlets: PCR and in situ hybridization (ISH/FISH). A PCR product specific for the Methylobacterium genus was found in DNA isolated from the surface-sterilized plantlet leaves. Presence of Methylobacterium rRNA was detected by ISH/FISH in leaves and stems of inoculated as well as axenic potato plantlets although the bacterium cannot be isolated from the axenic plants. Methylobacterium sp. resides in unculturable state within tissues of in vitro-grown potato plants and becomes culturable after inoculation with P. fluorescens IMBG163. In order to develop endophytic biofertilizers and biocontrol agents, a detailed knowledge of the life-style of endophytes is essential. To our knowledge, this is the first report on increase of the culturability of endophytes in response to inoculation by nonpathogenic bacteria.

  7. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

    Science.gov (United States)

    Maldonado-González, M. Mercedes; Bakker, Peter A. H. M.; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-01-01

    The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

  8. Characterisation of the thermostable protease AprX in strains of Pseudomonas fluorescens and impact on the shelf-life of dairy products: preliminary results

    Directory of Open Access Journals (Sweden)

    Nadia Andrea Andreani

    2016-12-01

    Full Text Available Bacterial proteases are involved in food spoilage and shelf-life reduction. Among the bacterial proteases, a predominant role in spoilage of dairy products seems to be played by the thermostable metallo-protease AprX, which is produced by various strains of Pseudomonas fluorescens. Differences in AprX enzyme activity among different strains were highlighted, but the most proteolytic strains were not identified. In this study, the presence of the aprX gene was evaluated in 69 strains isolated from food matrices and 18 reference strains belonging to the P. fluorescens group, which had been previously typed by the multi locus sequence typing method. Subsequently, a subset of reference strains was inoculated in ultra-high temperature milk, and the expression of the aprX gene was evaluated at 22 and 6°C. On the same milk samples, the proteolytic activity was then evaluated through Azocasein and trinitrobenzenesulfonic acid solution assays. Finally, to assess the applicability of the former assay directly on dairy products the proteolityc activity was tested on industrial ricotta samples using the Azocasein assay. These results demonstrate the spread of aprX gene in most strains tested and the applicability of Azocasein assay to monitor the proteolytic activity in dairy products.

  9. Non-target trials with Pseudomonas fluorescens strain CL145A, a lethal control agent of dreissenid mussels (Bivalvia: Dreissenidae

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    Daniel P. Molloy

    2013-01-01

    Full Text Available In an effort to develop an efficacious and environmentally safe method for managing zebra mussels (Dreissena polymorpha and quaggamussels (Dreissena rostriformis bugensis, we initiated a research project investigating the potential use of bacteria and their naturalmetabolic products as biocontrol agents. This project resulted in the discovery of an environmental isolate lethal to dreissenid mussels,Pseudomonas fluorescens strain CL145A (Pf-CL145A. In previous published reports we have demonstrated that: 1 Pf-CL145A’s mode ofaction is intoxication (not infection; 2 natural product within ingested bacterial cells lyse digestive tract epithelial cells leading to dreisseniddeath; and 3 high dreissenid kill rates (>90% are achievable following treatment with Pf-CL145A cells, irrespective of whether thebacterial cells are dead or alive. Investigating the environmental safety of Pf-CL145A was also a key element in our research efforts, andherein, we report the results of non-target trials demonstrating Pf-CL145A’s high specificity to dreissenids. These acute toxicity trials weretypically single-dose, short-term (24-72 h exposures to Pf-CL145A cells under aerated conditions at concentrations highly lethal todreissenids (100 or 200 mg/L. These trials produced no evidence of mortality among the ciliate Colpidium colpoda, the cladoceran Daphniamagna, three fish species (Pimephales promelas, Salmo trutta, and Lepomis macrochirus, and seven bivalve species (Mytilus edulis,Pyganodon grandis, Pyganodon cataracta, Lasmigona compressa, Strophitus undulatus, Lampsilis radiata, and Elliptio complanata. Lowmortality (3-27% was recorded in the amphipod Hyalella azteca, but additional trials suggested that most, if not all, of the mortality couldbe attributed to some other unidentified factor (e.g., possibly particle load or a water quality issue rather than Pf-CL145A’s dreissenidkillingnatural product. In terms of potential environmental safety, the results of

  10. Non-target effects of the microbial control agents Pseudomonas fluorescens DR54 and Clonostachys rosea IK726 in soils cropped with barley followed by sugar beet

    DEFF Research Database (Denmark)

    Johansen, Anders; Knudsen, Inge M.B.; Binnerup, Svend J.

    2005-01-01

    Non-target effects of a bacterial (Pseudomonas fluorescens DR54) and a fungal (Clonostachys rosea IK726) microbial control agent (MCA), on the indigenous microbiota in bulk soil and rhizosphere of barley, and subsequent a sugar beet crop, were studied in a greenhouse experiment. MCAs were...... by a factor of 106 and 20, respectively, and DR54 showed a short-lasting growth increase in the sugar beet rhizosphere. In general, the non-target effects were small and transient. IK726 seemed to have general stimulating effects on soil enzyme activity and the soil microbiota, and resulted in a significant...... introduced by seed and soil inoculation. Bulk and rhizosphere soils were sampled regularly during the growth of barley and sugar beet. The soils were assayed for the fate of MCAs and various features of the indigenous soil microbiota. At the end of the experiment (193 d), DR54 and IK726 had declined...

  11. Investigation of zoonotic disease pathogens (Aeromonas hydrophila, Pseudomonas fluorescens, Streptococcus iniae) seen in carp farms in the Northern Iraq-Erbil region by molecular methods

    Science.gov (United States)

    Ibraheem, Azad Saber; Önalan, Şükrü; Arabacı, Muhammed

    2017-04-01

    The aim of this study was to determine the zoonotic bacteria in carp farms in the Northern Iraq-Erbil region. Carp is the main fish species cultured in Erbil region. The most common zoonotic bacteria generally seen in carp farms are Aeromonas hydrophila, Pseudomonas fluorescens and Streptococcus iniae. Samples were collected from 25 carp farms in the Northern Iraq-Erbil region. Six carp samples were collected from each carp farm. Head kidney and intestine tissue samples were collected from each carp sample. Then head kidney and intestine tissue samples were pooled separately from each carp farm. Total bacterial DNA had been extracted from the 25 pooled head kidney and 25 intestinal tissue samples. The pathogen Primers were originally designed from 16S RNA gene region. Zoonotic bacteria were scanned in all tissue samples with absent/present analysis by RT-PCR. Furthermore, the capillary gel electrophoresis bands were used for confirmation of amplicon size which was planned during primer designing stage. As a result, thirteen carp farms were positive in the respect to Aeromonas hydrophila, eight carp farms were positive from head kidney and six carp farms were positive from the intestine, only one carp farm was positive from both head kidney and the intestine tissue samples. In the respect to Streptococcus iniae, four carp farms were positive from head kidney and two carp farms were positive from the intestine. Only one carp farm was positive in the respect to Pseudomonas fluorescens from the intestine. Totally, 9 of 25 carp farms were cleared (negative) the zoonotic bacteria. In conclusion, the zoonotic bacteria were high (64 %) in carp farms in the Northern Iraq-Erbil region.

  12. Influencia de la concentración salina y la temperatura en la composición de ácidos grasos de membrana de Pseudomonas fluorescens GNP-OHP-3 Influence of salinity and temperature on fatty acid composition of Pseudomonas fluorescens GNP-OHP-3 membrane

    Directory of Open Access Journals (Sweden)

    G. N. Pucci

    2004-03-01

    Full Text Available Las bacterias responden a los cambios ambientales modificando su composición, para evitar el daño que dichos cambios podrían ejercer. Una de las modificaciones más importantes es la variación de la composición de los ácidos grasos de las membranas celulares, que le permite mantener la homeoviscosidad ante situaciones de estrés. Trabajos previos han estudiado la acción de la temperatura, presión hidrostática y diferentes solventes sobre cepas de Pseudomonas putida. En este trabajo se estudió la acción conjunta de la temperatura y la salinidad sobre la composición de ácidos grasos de membranas celulares de Pseudomonas fluorescens GNP-OHP-3, una cepa bacteriana aislada de un hábitat contaminado con petróleo. Pseudomonas fluorescens GNP-OHP-3 respondió a las variaciones de temperatura modificando los ácidos grasos de sus membranas de manera similar a lo descripto en otros integrantes de su género: ante el aumento de temperatura se observó un incremento de ácidos grasos saturados y una disminución de los ácidos grasos insaturados. En el rango de concentraciones salinas ensayadas las variaciones de los ácidos grasos mayoritarios fueron en general erráticas. La respuesta de los ácidos grasos ciclo propano pudo expresarse con ecuaciones matemáticas que permitieron predecir el porcentaje de estos ácidos en relación a la concentración de cloruro de sodio.The bacteria respond to environmental changes modifying their composition. One of the most important modifications is the variation on fatty acid composition of cellular membranes to maintain the homeoviscosity. The action of temperature, hydrostatic pressure and solvents on Pseudomonas putida has been thoroughly studied. In this paper, the combined action of the temperature and salinity on fatty acid composition of cellular membranes of Pseudomonas fluorescens GNP-OHP-3, a bacterial strain isolated from a petroleum contaminated habitat, was studied. The modifications in the

  13. Development and validation of a real-time TaqMan assay for the detection and enumeration of Pseudomonas fluorescens ATCC 13525 used as a challenge organism in testing of food equipments.

    Science.gov (United States)

    Saha, Ratul; Bestervelt, Lorelle L; Donofrio, Robert S

    2012-02-01

    Pseudomonas fluorescens ATCC 13525 is used as the challenge organism to evaluate the efficacy of the clean-in-place (CIP) process of food equipment (automatic ice-maker) as per NSF/ANSI Standard 12. Traditional culturing methodology is presently used to determine the concentration of the challenge organism, which takes 48 h to confirm the cell density. Storage of the challenge preparation in the refrigerator might alter the cell density as P. fluorescens is capable of growing at 4 °C. Also, background organism can grow on the Pseudomonas F agar (PFA) used for the recovery of P. fluorescens thus affecting the results of the test. Real-time TaqMan assay targeting the cpn60 gene was developed for the enumeration and the identification of P. fluorescens because of its specificity, accuracy, and shorter turnaround time. The TaqMan primer-probe pair developed using the Allele ID® 7.0 probe design software was highly specific and sensitive for the target organism. The sensitivity of the assay was 10 colony forming units (CFU)/mL. The assay was also successful in determining the concentration of the challenge preparation within 2 h. Based on these observations, TaqMan assay targeting the cpn60 gene can be efficiently used for strain level identification and enumeration of bacteria. Pseudomonas fluorescens ATCC 13525 is used as a challenge organism in the efficacy testing of clean-in-place process of food equipments. Currently, culturing technique is used for its identification and estimation, which is not only time-consuming but also prone to error. Real-time TaqMan assay is more specific, sensitive, and accurate along with a shorter turnaround time compared to culturing techniques, thereby increasing the overall quality of the testing methodology to evaluate the clean-in-place process critical for the food industry to protect public health and safety. © 2012 Institute of Food Technologists®

  14. Proteinase production in Pseudomonas fluorescens ON2 is affected by carbon sources and allows surface-attached but not planktonic cells to utilize protein for growth in lake water

    DEFF Research Database (Denmark)

    Nicolaisen, Mette Haubjerg; Worm, Jakob; Jørgensen, Niels O. G.

    2012-01-01

    Proteins may be an important carbon and nitrogen source to bacteria in aquatic habitats, yet knowledge on the actual utilization of this substrate by proteolytic bacteria is scarce. In the present study, Pseudomonas fluorescens ON2 produced an alkaline proteinase (AprX) during growth and there wa......Proteins may be an important carbon and nitrogen source to bacteria in aquatic habitats, yet knowledge on the actual utilization of this substrate by proteolytic bacteria is scarce. In the present study, Pseudomonas fluorescens ON2 produced an alkaline proteinase (AprX) during growth...... the proteinase during growth unless a preferred carbon source like citrate is present. Lake water model systems were subsequently used to investigate the ability of proteolytic versus non-proteolytic ON2 strains to utilize protein for growth at moderate cell densities. Only cells forming surface-attached micro...

  15. Sequencing and Analysis of the Pseudomonas fluorescens GcM5-1A Genome: A Pathogen Living in the Surface Coat of Bursaphelenchus xylophilus.

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    Kai Feng

    Full Text Available It is known that several bacteria are adherent to the surface coat of pine wood nematode (Bursaphelenchus xylophilus, but their function and role in the pathogenesis of pine wilt disease remains debatable. The Pseudomonas fluorescens GcM5-1A is a bacterium isolated from the surface coat of pine wood nematodes. In previous studies, GcM5-1A was evident in connection with the pathogenicity of pine wilt disease. In this study, we report the de novo sequencing of the GcM5-1A genome. A 600-Mb collection of high-quality reads was obtained and assembled into sequence contigs spanning a 6.01-Mb length. Sequence annotation predicted 5,413 open reading frames, of which 2,988 were homologous to genes in the other four sequenced P. fluorescens isolates (SBW25, WH6, Pf0-1 and Pf-5 and 1,137 were unique to GcM5-1A. Phylogenetic studies and genome comparison revealed that GcM5-1A is more closely related to SBW25 and WH6 isolates than to Pf0-1 and Pf-5 isolates. Towards study of pathogenesis, we identified 79 candidate virulence factors in the genome of GcM5-1A, including the Alg, Fl, Waa gene families, and genes coding the major pathogenic protein fliC. In addition, genes for a complete T3SS system were identified in the genome of GcM5-1A. Such systems have proved to play a critical role in subverting and colonizing the host organisms of many gram-negative pathogenic bacteria. Although the functions of the candidate virulence factors need yet to be deciphered experimentally, the availability of this genome provides a basic platform to obtain informative clues to be addressed in future studies by the pine wilt disease research community.

  16. Application of Endophytic Pseudomonas fluorescens and a Bacterial Consortium to Brassica napus Can Increase Plant Height and Biomass under Greenhouse and Field Conditions

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    Richard D. Lally

    2017-12-01

    Full Text Available Plant associated bacteria with plant growth promotion (PGP properties have been proposed for use as environmentally friendly biofertilizers for sustainable agriculture; however, analysis of their efficacy in the field is often limited. In this study, greenhouse and field trials were carried out using individual endophytic Pseudomonas fluorescens strains, the well characterized rhizospheric P. fluorescens F113 and an endophytic microbial consortium of 10 different strains. These bacteria had been previously characterized with respect to their PGP properties in vitro and had been shown to harbor a range of traits associated with PGP including siderophore production, 1-aminocyclopropane-1-carboxylic acid (ACC deaminase activity, and inorganic phosphate solubilization. In greenhouse experiments individual strains tagged with gfp and Kmr were applied to Brassica napus as a seed coat and were shown to effectively colonize the rhizosphere and root of B. napus and in addition they demonstrated a significant increase in plant biomass compared with the non-inoculated control. In the field experiment, the bacteria (individual and consortium were spray inoculated to winter oilseed rape B. napus var. Compass which was grown under standard North Western European agronomic conditions. Analysis of the data provides evidence that the application of the live bacterial biofertilizers can enhance aspects of crop development in B. napus at field scale. The field data demonstrated statistically significant increases in crop height, stem/leaf, and pod biomass, particularly, in the case of the consortium inoculated treatment. However, although seed and oil yield were increased in the field in response to inoculation, these data were not statistically significant under the experimental conditions tested. Future field trials will investigate the effectiveness of the inoculants under different agronomic conditions.

  17. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

    Directory of Open Access Journals (Sweden)

    M. Mercedes eMaldonado-González

    2015-04-01

    Full Text Available The effective management of Verticillium wilts, diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control Verticillium wilt of olive caused by the highly-virulent, defoliating (D pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V.dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i olive D and non-defoliating (ND V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii strain PICF7 controls Verticillium wilt (VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. Arabidopsis thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7.

  18. Influence of Arbuscular Mycorrhizal Fungi and Pseudomonas fluorescens at Different Superphosphate Levels on Linseed (Linum usitatissimum L. Growth Response Influencia de Hongos Micorriza Arbusculares y Pseudomonas fluorescens con Diferentes Niveles de Superfosfato sobre la Respuesta al Crecimiento de Lino (Linum usitatissimum L.

    Directory of Open Access Journals (Sweden)

    Neetu Neetu

    2012-06-01

    Full Text Available The aim of this study was to investigate the influence of arbuscular mycorrhizal fungi (AMF Glomus mosseae (T.H. Nicolson & Gerd. Gerd. & Trappe and Acaulospora laevis (Gerd. & Trappe on linseed (Linum usitatissimum L. growth response with phosphate solubilizing bacteria Pseudomonas fluorescens; different doses of superphosphate were used: 20 kg ha4 (half recommended dose, 40 kg ha4 (recommended dose, and 80 kg ha4 (double recommended dose in earthen pots filled with sterilized soil under greenhouse conditions. Among all the growth parameters, the following were the highest in the G. mosseae + P. fluorescens combination at the medium concentration (recommended superphosphate dose: plant height (78.74 ± 1.8 cm, fresh shoot weight (3.45 ± 0.294 g, dry shoot weight (0.57 ± 0.007 g, fresh root weight (0.223 ± 0.023 g, dry root weight (0.036 ± 0.004 g, root length (17.67 ± 0.48 cm, AM spore number (94.4 ± 9.86, shoot (1.14 ± 0.115% and root (1.29 ± 0.110% P content, and acidic (0.447 ± 0.012 IU g-1 FW and alkaline phosphatase activity (0.119 ± 0.008 IU g-1 FW. The percentage mycorrhizal root colonization with the A. laevis + P. fluorescens (86.86 ± 2.17% combination and chlorophyll content with the G. mosseae + A. laevis + P. fluorescens (0.474 ± 0.009 mg g-1 FW combination recorded the highest values at the low concentration (half recommended superphosphate dose as compared with non-mycorrhizal plants (control. The high superphosphate dose clearly reduced or decreased all the growth parameters. Therefore, vigorous growth and maximum flax yield can be achieved by inoculating plants with AM fungi and P. fluorescens with the recommended dose or less than the recommended dose of superphosphate.La presente investigation tuvo como objetivo estudiar la influencia de hongos micorrícicos arbusculares (AMF, i.e., Glomus mosseae (T.H. Nicolson & Gerd. Gerd. & Trappey Acaulospora laevis (Gerd. & Trappe, en la respuesta de crecimiento de lino

  19. Pseudomonas aeruginosa Alginate Overproduction Promotes Coexistence with Staphylococcus aureus in a Model of Cystic Fibrosis Respiratory Infection

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    Dominique H. Limoli

    2017-03-01

    Full Text Available While complex intra- and interspecies microbial community dynamics are apparent during chronic infections and likely alter patient health outcomes, our understanding of these interactions is currently limited. For example, Pseudomonas aeruginosa and Staphylococcus aureus are often found to coinfect the lungs of patients with cystic fibrosis (CF, yet these organisms compete under laboratory conditions. Recent observations that coinfection correlates with decreased health outcomes necessitate we develop a greater understanding of these interbacterial interactions. In this study, we tested the hypothesis that P. aeruginosa and/or S. aureus adopts phenotypes that allow coexistence during infection. We compared competitive interactions of P. aeruginosa and S. aureus isolates from mono- or coinfected CF patients employing in vitro coculture models. P. aeruginosa isolates from monoinfected patients were more competitive toward S. aureus than P. aeruginosa isolates from coinfected patients. We also observed that the least competitive P. aeruginosa isolates possessed a mucoid phenotype. Mucoidy occurs upon constitutive activation of the sigma factor AlgT/U, which regulates synthesis of the polysaccharide alginate and dozens of other secreted factors, including some previously described to kill S. aureus. Here, we show that production of alginate in mucoid strains is sufficient to inhibit anti-S. aureus activity independent of activation of the AlgT regulon. Alginate reduces production of siderophores, 2-heptyl-4-hydroxyquinolone-N-oxide (HQNO, and rhamnolipids—each required for efficient killing of S. aureus. These studies demonstrate alginate overproduction may be an important factor driving P. aeruginosa coinfection with S. aureus.

  20. Colony morphology and transcriptome profiling of Pseudomonas putida KT2440 and its mutants deficient in alginate or all EPS synthesis under controlled matric potentials

    DEFF Research Database (Denmark)

    Gülez, Gamze; Altintas, Ali; Fazli, Mustafa

    2014-01-01

    Pseudomonas putida is a versatile bacterial species adapted to soil and its fluctuations. Like many other species living in soil, P. putida often faces water limitation. Alginate, an exopolysaccharide (EPS) produced by P. putida, is known to create hydrated environments and alleviate the effect...... of water limitation. In addition to alginate, P. putida is capable of producing cellulose (bcs), putida exopolysaccharide a (pea), and putida exopolysaccharide b (peb). However, unlike alginate, not much is known about their roles under water limitation. Hence, in this study we examined the role...... of different EPS components under mild water limitation. To create environmentally realistic water limited conditions as observed in soil, we used the Pressurized Porous Surface Model. Our main hypothesis was that under water limitation and in the absence of alginate other exopolysaccharides would be more...

  1. Pseudomonas aeruginosa alginate is refractory to Th1 immune response and impedes host immune clearance in a mouse model of acute lung infection

    DEFF Research Database (Denmark)

    Song, Zhijun; Wu, Hong; Ciofu, Oana

    2003-01-01

    . The effect of alginate production on pathogenicity was investigated by using an acute lung infection mouse model that compared a non-mucoid P. aeruginosa strain, PAO1, to its constitutive alginate-overproducing derivative, Alg(+) PAOmucA22, and an alginate-defective strain, Alg(-) PAOalgD. Bacterial......Pseudomonas aeruginosa is an opportunistic respiratory pathogen that accounts for most of the morbidity and mortality in cystic fibrosis (CF) patients. In CF-affected lungs, the bacteria undergo conversion from a non-mucoid to a non-tractable mucoid phenotype, due to overproduction of alginate...... suspensions were instilled into the left bronchus and examined 24 and 48 h post-infection. The highest bacterial loads and the most severe lung pathology were observed with strain Alg(-) PAOalgD at 24 h post-infection, which may have been due to an increase in expression of bacterial elastase by the mutant...

  2. Proteolytic activity of protease produced by Pseudomonas fluorescens IB 2312 in skimmed milk subject to the process of high pressure homogenization

    Directory of Open Access Journals (Sweden)

    Claudia Regina Gonçalves Pinho

    2014-08-01

    Full Text Available The presence of thermoresistant proteases produced by psychrotrophic microorganisms have been identified as a limiting factor of the UHT milk shelflife, causing undesirable changes in milk products. High pressure homogenization (HPH processing is a non-thermal method of food preservation, able to promotes the microbiological safety and inactivation of some enzymes. Thus, this work assessed the proteolytic activity of protease produced by Pseudomonas fluorescens in skim milk subjected to high pressure homogenization process. The milk samples were added by the protease enzymatic extract (10% v/v and subjected to pressures up to 300 MPa. The assays showed that pressures on the order of 300 MPa caused a 72.5% reduction in proteolytic activity. Therefore, the process at high pressures resulted in significant inactivation of this thermoresistent enzyme, which possibly favors the shelf-life extension of the UHT milk and also limits the yield and quality loss of cheeses due to undesirable sensory changes in flavor and texture caused by this enzyme.

  3. Immobilization of Pseudomonas fluorescens lipase on hydrophobic supports and application in biodiesel synthesis by transesterification of vegetable oils in solvent-free systems.

    Science.gov (United States)

    Lima, Lionete N; Oliveira, Gladson C; Rojas, Mayerlenis J; Castro, Heizir F; Da Rós, Patrícia C M; Mendes, Adriano A; Giordano, Raquel L C; Tardioli, Paulo W

    2015-04-01

    This work describes the preparation of biocatalysts for ethanolysis of soybean and babassu oils in solvent-free systems. Polystyrene, Amberlite (XAD-7HP), and octyl-silica were tested as supports for the immobilization of Pseudomonas fluorescens lipase (PFL). The use of octyl-silica resulted in a biocatalyst with high values of hydrolytic activity (650.0 ± 15.5 IU/g), immobilization yield (91.3 ± 0.3 %), and recovered activity (82.1 ± 1.5 %). PFL immobilized on octyl-silica was around 12-fold more stable than soluble PFL, at 45 °C and pH 8.0, in the presence of ethanol at 36 % (v/v). The biocatalyst provided high vegetable oil transesterification yields of around 97.5 % after 24 h of reaction using babassu oil and around 80 % after 48 h of reaction using soybean oil. The PFL-octyl-silica biocatalyst retained around 90 % of its initial activity after five cycles of transesterification of soybean oil. Octyl-silica is a promising support that can be used to immobilize PFL for subsequent application in biodiesel synthesis.

  4. Synthesis of amino-silane modified superparamagnetic Fe{sub 3}O{sub 4} nanoparticles and its application in immobilization of lipase from Pseudomonas fluorescens Lp1

    Energy Technology Data Exchange (ETDEWEB)

    Kanimozhi, S., E-mail: skanimo@gmail.com [Department of Biotechnology, Sathyabama University, Jeppiaar Nagar, Rajivgandhi Salai, Chennai 600119, Tamil Nadu (India); Perinbam, K. [Department of Plant Biology and Biotechnology, Nandanam Arts College (Men), Chennai 600035, Tamil Nadu (India)

    2013-05-15

    Highlights: ► Magnetic nanoparticles were synthesized by chemical co-precipitation method. ► Surface was functionalized with amino-silane and used for lipase immobilization. ► Characterized through TEM, SEM, XRD, FT-IR and VSM analysis. ► The functionalization and immobilization did not affect the magnetite properties. ► The immobilized lipase showed greater functional property than free lipase. - Abstract: Superparamagnetic nanoparticles (Fe{sub 3}O{sub 4}–magnetite) were prepared by chemical co-precipitation method and their surface was functionalized with 3-aminopropyltriethoxysilane via silanization reaction to obtain amino functionalized magnetic nanoparticles. The purified lipase from Pseudomonas fluorescens Lp1 was immobilized onto functionalized magnetite using glutaraldehyde as the coupling agent. The characterization of the nanoparticles was done by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, vibrating sample magnetometry and Fourier transformed infrared spectroscopy. The size of the magnetite was measured about 10–30 nm. The results of characterization study revealed the successful immobilization of lipase on to functionalized magnetite. The saturation magnetization of magnetic nanoparticles was found to be 28.34 emu/g whereas the immobilized magnetic nanoparticle was 17.074 emu/g. The immobilized lipase had greater activity at 50 °C and thermal stability upto 70 °C. It exhibited excellent reusability for 4 cycles and storage stability upto 15 days by retaining 75% of its initial activity.

  5. Efficacy of Pseudomonas fluorescens strain CL145A spray dried powder for controlling zebra mussels adhering to native unionid mussels within field enclosures

    Science.gov (United States)

    Luoma, James A.; Weber, Kerry L.; Severson, Todd J.; Mayer, Denise A.

    2015-01-01

    The efficacy of a commercially prepared spray dried powder (SDP) formulation of Pseudomonas fluorescens (strain CL145A) was evaluated for removing zebra mussels (Dreissena polymorpha) adhering to a population of unionid mussels in Lake Darling (Alexandria, Minnesota). Two groups of unionid mussels were used in the study. Unionid mussels were collected near the test area, weighed, photographed, individually tagged, and randomly allocated to one of nine test enclosures in equal proportions and then divided into two groups. The first group of unionid mussels (Group 1, n = 5 per test enclosure) were indiscriminately selected from each test enclosure and used to estimate the number of zebra mussels adhering to unionid mussels prior to exposure. The second group of unionid mussels (Group 2, n = 22 per test enclosure) were used to evaluate the efficacy of SDP for removal of adhering zebra mussels. Both Group 1 and Group 2 mussels were used to evaluate the effects of SDP exposure on unionid mussel survival.

  6. Diversity and functional analysis of LuxR-type transcriptional regulators of cyclic lipopeptide biosynthesis in Pseudomonas fluorescens

    NARCIS (Netherlands)

    Bruijn, de I.; Raaijmakers, J.M.

    2009-01-01

    Cyclic lipopeptides (CLPs) are produced by many Pseudomonas species and have several biological functions, including a role in surface motility, biofilm formation, virulence, and antimicrobial activity. This study focused on the diversity and role of LuxR-type transcriptional regulators in CLP

  7. Pseudomonas aeruginosa Alginate Overproduction Promotes Coexistence with Staphylococcus aureus in a Model of Cystic Fibrosis Respiratory Infection.

    Science.gov (United States)

    Limoli, Dominique H; Whitfield, Gregory B; Kitao, Tomoe; Ivey, Melissa L; Davis, Michael R; Grahl, Nora; Hogan, Deborah A; Rahme, Laurence G; Howell, P Lynne; O'Toole, George A; Goldberg, Joanna B

    2017-03-21

    While complex intra- and interspecies microbial community dynamics are apparent during chronic infections and likely alter patient health outcomes, our understanding of these interactions is currently limited. For example, Pseudomonas aeruginosa and Staphylococcus aureus are often found to coinfect the lungs of patients with cystic fibrosis (CF), yet these organisms compete under laboratory conditions. Recent observations that coinfection correlates with decreased health outcomes necessitate we develop a greater understanding of these interbacterial interactions. In this study, we tested the hypothesis that P. aeruginosa and/or S. aureus adopts phenotypes that allow coexistence during infection. We compared competitive interactions of P. aeruginosa and S. aureus isolates from mono- or coinfected CF patients employing in vitro coculture models. P. aeruginosa isolates from monoinfected patients were more competitive toward S. aureus than P. aeruginosa isolates from coinfected patients. We also observed that the least competitive P. aeruginosa isolates possessed a mucoid phenotype. Mucoidy occurs upon constitutive activation of the sigma factor AlgT/U, which regulates synthesis of the polysaccharide alginate and dozens of other secreted factors, including some previously described to kill S. aureus Here, we show that production of alginate in mucoid strains is sufficient to inhibit anti-S. aureus activity independent of activation of the AlgT regulon. Alginate reduces production of siderophores, 2-heptyl-4-hydroxyquinolone-N-oxide (HQNO), and rhamnolipids-each required for efficient killing of S. aureus These studies demonstrate alginate overproduction may be an important factor driving P. aeruginosa coinfection with S. aureusIMPORTANCE Numerous deep-sequencing studies have revealed the microbial communities present during respiratory infections in cystic fibrosis (CF) patients are diverse, complex, and dynamic. We now face the challenge of determining

  8. Opening Study on the Development of a New Biosensor for Metal Toxicity Based on Pseudomonas fluorescens Pyoverdine

    Directory of Open Access Journals (Sweden)

    Alessandro Chiadò

    2013-12-01

    Full Text Available To date, different kinds of biosensing elements have been used effectively for environmental monitoring. Microbial cells seem to be well-suited for this task: they are cheap, adaptable to variable field conditions and give a measurable response to a broad number of chemicals. Among different pollutants, heavy metals are still a major problem for the environment. A reasonable starting point for the selection of a biorecognition element to develop a biosensor for metals could be that of a microorganism that exhibits good mechanisms to cope with metals. Pseudomonads are characterized by the secretion of siderophores (e.g., pyoverdine, low-molecular weight compounds that chelate Fe3+ during iron starvation. Pyoverdine is easily detected by colorimetric assay, and it is suitable for simple online measurements. In this work, in order to evaluate pyoverdine as a biorecognition element for metal detection, the influence of metal ions (Fe3+, Cu2+, Zn2+, but also of temperature, pH and nutrients, on microbial growth and pyoverdine regulation has been studied in P. fluorescens. Each of these variables has been shown to influence the synthesis of siderophore: for instance, the lower the temperature, the higher the production of pyoverdine. Moreover, the concentration of pyoverdine produced in the presence of metals has been compared with the maximum allowable concentrations indicated in international regulations (e.g., 98/83/EC, and a correlation that could be useful to build a colorimetric biosensor has been observed.

  9. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation

    DEFF Research Database (Denmark)

    Stapper, A.P.; Narasimhan, G.; Oman, D.E.

    2004-01-01

    -overproducing (mucA22) and alginate-defective (algD) variants in order to discern the role of alginate in biofilm formation. These strains, PAO1, Alg(+) PAOmucA22 and Alg(-) PAOalgD, tagged with green fluorescent protein, were grown in a continuous flow cell system to characterize the developmental cycles...... of their biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (BIP) and Community Statistics (COMSTAT) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating...... that the production of alginate is not critical for biofilm formation. Observation over a period of 5 days indicated a three-stage development pattern consisting of initiation, establishment and maturation. Furthermore, this study showed that phenotypically distinguishable biofilms can be quantitatively...

  10. The oxyanion hole of Pseudomonas fluorescens mannitol 2-dehydrogenase: a novel structural motif for electrostatic stabilization in alcohol dehydrogenase active sites.

    Science.gov (United States)

    Klimacek, Mario; Nidetzky, Bernd

    2009-12-23

    The side chains of Asn191 and Asn300 constitute a characteristic structural motif of the active site of Pseudomonas fluorescens mannitol 2-dehydrogenase that lacks precedent in known alcohol dehydrogenases and resembles the canonical oxyanion binding pocket of serine proteases. We have used steady-state and transient kinetic studies of the effects of varied pH and deuterium isotopic substitutions in substrates and solvent on the enzymatic rates to delineate catalytic consequences resulting from individual and combined replacements of the two asparagine residues by alanine. The rate constants for the overall hydride transfer to and from C-2 of mannitol, which were estimated as approximately 5 x 102 s-1 and approximately 1.5 x 103 s-1 in the wild-type enzyme respectively, were selectively slowed, between 540- and 2700-fold, in single-site mannitol 2-dehydrogenase mutants. These effects were additive in the corresponding doubly mutated enzyme, suggesting independent functioning of the two asparagine residues in catalysis. Partial disruption of the oxyanion hole in single-site mutants caused an upshift, by >or=1.2 pH units, in the kinetic pK of the catalytic acid-base Lys295 in the enzyme-NAD+-mannitol complex. The oxyanion hole of mannitol 2-dehydrogenase is suggested to drive a precatalytic conformational equilibrium at the ternary complex level in which the reactive group of the substrate is 'activated' for chemical conversion through its precise alignment with the unprotonated side chain of Lys295 (mannitol oxidation) and C=O bond polarization by the carboxamide moieties of Asn191 and Asn300 (fructose reduction). In the subsequent hydride transfer step, the two asparagine residues provide approximately 40 kJ/mol of electrostatic stabilization.

  11. Improvement of a dry formulation of Pseudomonas fluorescens EPS62e for fire blight disease biocontrol by combination of culture osmoadaptation with a freeze-drying lyoprotectant.

    Science.gov (United States)

    Cabrefiga, J; Francés, J; Montesinos, E; Bonaterra, A

    2014-10-01

    To study the effect of lyoprotectants and osmoadaptation on viability of Pseudomonas fluorescens EPS62e during freeze-drying and storage and to evaluate the formulation in terms of efficacy in biocontrol and fitness on pear flowers. A wettable powder formulation of a biocontrol agent of fire blight was optimized by means of lyoprotectants and culture osmoadaptation. Freeze-drying was used to obtain dehydrated cells, and the best viability (70% of survival) was obtained using lactose as lyoprotectant. Survival during lyophilization was additionally improved using physiological adaptation of cells during cultivation under salt-amended medium (osmoadaptation). The procedure increased the survival of cells after freeze-drying attaining viability values close to a 100% in the lactose-formulated product (3 × 10(11) CFU g(-1) ), and through the storage period of 1 year at 4°C. The dry formulation showed also an improved biocontrol efficacy and survival of EPS62e on pear flowers under low relative humidity conditions. Cell viability after freeze-drying was improved using lactose as lyoprotectant combined with a procedure of osmoadaptation during cultivation. The powder-formulated product remained active for 12 months and retained biocontrol levels similar to that of fresh cells. The formulation showed an improved survival of EPS62e on flowers and an increase of the efficacy of biocontrol of fire blight at low relative humidity. The results have a potential value for commercial application in biocontrol agents not only of fire blight but also of other plant diseases. © 2014 The Society for Applied Microbiology.

  12. Control biológico del marchitamiento vascular causado por fusarium oxysporum f. sp. phaseoli en fríjol phaseolus vulgaris l., mediante la acción combinada de entrophospora colombiana, trichoderma sp. y pseudomonas fluorescens

    OpenAIRE

    Avendaño, Camila; Arbeláez, Germán; Rondón, Guillermo

    2010-01-01

    Entrophospora colombiana, Trichoderma sp., Pseudomonas fluorescens y una combinación de estos antagonistas fueron evaluados como biocontroladores de Fusarium oxysporumf. sp. Phaseoli en plantas de fríjol de la variedad ‘ICA Tundama’. El ensayo se estableció en una casa de malla del Programa nacional de manejo integrado de plagas (MIP) de la Corporación Colombiana de Investigación Agropecuaria (Corpoica), en el Centro de Investigación Tibaitatá, Mosquera (Cundinamarca), utilizando un diseño co...

  13. Nitrogen availability to Pseudomonas fluorescens DF57 is limited during decomposition of barley straw in bulk soil and in the barley rhizosphere.

    Science.gov (United States)

    Jensen, L E; Nybroe, O

    1999-10-01

    The availability of nitrogen to Pseudomonas fluorescens DF57 during straw degradation in bulk soil and in barley rhizosphere was studied by introducing a bioluminescent reporter strain (DF57-N3), responding to nitrogen limitation, to model systems of varying complexity. DF57-N3 was apparently not nitrogen limited in the natural and sterilized bulk soil used for these experiments. The soil was subsequently amended with barley straw, representing a plant residue with a high carbon-to-nitrogen ratio (between 60 and 100). In these systems the DF57-N3 population gradually developed a nitrogen limitation response during the first week of straw decomposition, but exclusively in the presence of the indigenous microbial population. This probably reflects the restricted ability of DF57 to degrade plant polymers by hydrolytic enzymes. The impact of the indigenous population on nitrogen availability to DF57-N3 was mimicked by the cellulolytic organism Trichoderma harzianum Rifai strain T3 when coinoculated with DF57-N3 in sterilized, straw-amended soil. Limitation occurred concomitantly with fungal cellulase production, pointing to the significance of hydrolytic activity for the mobilization of straw carbon sources, thereby increasing the nitrogen demand. Enhanced survival of DF57-N3 in natural soil after straw amendment further indicated that DF57 was cross-fed with carbon/energy sources. The natural barley rhizosphere was experienced by DF57-N3 as an environment with restricted nitrogen availability regardless of straw amendment. In the rhizosphere of plants grown in sterilized soil, nitrogen limitation was less severe, pointing to competition with indigenous microorganisms as an important determinant of the nitrogen status for DF57-N3 in this environment. Hence, these studies have demonstrated that nitrogen availability and gene expression in Pseudomonas is intimately linked to the structure and function of the microbial community. Further, it was demonstrated that the

  14. Salicylic acid degradation from aqueous solutions using Pseudomonas fluorescens HK44: parameters studies and application tools Degradação de ácido salicílico presente em soluções sintéticas utilizando Pseudomonas fluorescens HK44

    Directory of Open Access Journals (Sweden)

    Tatyane R. Silva

    2007-03-01

    Full Text Available The optimal conditions for salicylic acid biodegradation by Pseudomonas fluorescens HK44 were determined in this study with the intention to create a microbial sensor. Kinetic experiments permitted a definition of 60 and 30min the time needed to achieve the maximum degradation of salicylic acid presented in a medium with and without yeast extract, respectively. The degradation in medium without yeast extract and the quantification by spectrophotometry 230 nm were selected to be used in further tests. The use of preactivated cells or on the exponential growth phase showed better salicylic acid degradation percentages when compared to nonactivated cells or on the stationary growth state. Finally, the best cellular concentration used on the salicylic acid degradation was 0,1 g.L-1. Strain HK44 shows to be capable of degrade salicylic acid presented in simple aqueous systems, making this strain a promising tool for the application on a luminescent microbial sensor.Com a intenção de criar um sensor microbiano, as condições ótimas para a biodegradação de ácido salicílico por Pseudomonas fluorescens HK44 foram determinadas neste estudo. Os experimentos cinéticos permitiram a definição dos tempos de 60 e 30 minutos como necessários para atingir a máxima degradação de ácido salicílico presente em meio com ou sem extrato de lêvedo, respectivamente. A degradação no meio sem extrato de lêvedo e a quantificação através de espectrofotometria 230 nm foram selecionadas para serem utilizadas em testes posteriores. O uso de células pré-ativadas ou na fase exponencial de crescimento apresentou melhores porcentagens de degradação de ácido salicílico quando comparadas a células não-ativadas ou no estado estacionário de crescimento. Além disso, a melhor concentração celular utilizada nessa degradação foi 0,1 g.L¹. A cepa HK44 parece ser capaz de degradar o ácido salicílico presente em sistemas aquosos simples, tornando este

  15. Annual changes in bioactive contents and production in field-grown blackberry after inoculation with Pseudomonas fluorescens.

    Science.gov (United States)

    Ramos-Solano, B; Garcia-Villaraco, A; Gutierrez-Mañero, F J; Lucas, J A; Bonilla, A; Garcia-Seco, D

    2014-01-01

    The aim of this study was two-fold: first, to characterize blackberry fruits from Rubus sp. var. Lochness along the year, and secondly, to evaluate the ability of a Pseudomonas strain (N21.4) to improve fruit yield and quality under field conditions in production greenhouses throughout the year. The strain was root or leaf inoculated to blackberry plants and fruits were harvested in each season. Nutritional parameters, antioxidant potential and bioactive contents were determined; total fruit yield was recorded. Blackberries grown under short day conditions (autumn and winter) showed significantly lower °Brix values than fruits grown under long day conditions. Interestingly, an increase in fruit °Brix, relevant for quality, was detected after bacterial challenge, together with significant and sustained increases in total phenolics and flavonoids. Improvements in inoculated fruits were more evident from October through early March, when environmental conditions are worse. In summary, N21.4 is an effective agent to increase fruit quality and production along the year in blackberry; this is an environmentally friendly approach to increase fruit quality. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  16. INFLUENCIA DE LA BACTERIA Pseudomonas fluorescens EN LA LECHE, SOBRE LAS CARACTERÍSTICAS SENSORIALES DEL QUESO DOBLE CREMA

    Directory of Open Access Journals (Sweden)

    SJ González

    2007-01-01

    Full Text Available El objetivo de este trabajo fue observar el efecto de la presencia de microorganismos psicro-tróÀcos en la leche, sobre las características sensoriales del queso doble crema. Para esto, se inoculó la leche con un cultivo de Pseudomonas Áuorescens, a un nivel de 108 unidades formadoras de colonia por mililitro (ufc/ml. La leche se refrigeró a 4 ºC por seis días, se pasteurizó y posteriormente se preparó el queso. Se elaboraron lotes de queso cada 10 días, con el Àn de obtener siete tiempos experimentales. A cada uno se le determinó la vida útil sensorial. Los resultados de las pruebas sensoriales se analizaron con el programa S-PLUS de estadísti-ca de supervivencia aplicada a la vida útil sensorial de alimentos. Se determinó que el tiempo de vida útil sensorial del queso doble crema elaborado con leche en estas condiciones, y alma-cenado a 4 °C, está alrededor de 30 días, disminuyendo en un 50% con relación al patrón.

  17. Conjugation of alginate to a synthetic peptide containing T- and B-cell epitopes as an induction for protective immunity against Pseudomonas aeruginosa.

    Science.gov (United States)

    Farjaha, Ali; Owlia, Parviz; Siadat, Seyed Davar; Mousavi, Seyed Fazlollah; Shafieeardestani, Mehdi

    2014-12-20

    Pseudomonas aeruginosa is a major cause of respiratory tract infections worldwide, particularly in hospitalized patients with immunosuppressed conditions and cystic fibrosis (CF). Excessive use of antibiotics means that there is currently resistance among bacterial infections to many drugs. Vaccination is a strategy that can reduce mortality and morbidity rates in infections such as those caused by P. aeruginosa. Alginate has a critical role in such infections and affects pathogenicity of the bacterium. In this work, the bioinformatics approach was used to design and synthesis a carrier peptide (ERRANAVRDVLVNEY), derived from OMP F P. aeruginosa. This peptide contained both B- and T-cell epitopes based on prediction models. Conjugation of alginate to carrier peptide was performed and then analyzed by Fourier transform infrared spectroscopy (FTIR). Results of this study on mice showed that the conjugate elicited anti-alginate-IgG that were not detected after immunization with naive alginate. The effect of the antibodies to alginate conjugate was evaluated as highly opsonic and showed moderate to high-level killing activity against two mucoid strains. IgG1 was also dominant among IgG subclasses. Mice vaccinated with the conjugate vaccine survived lethal challenges (2 ×LD 50). Furthermore, using an acute pneumonia model of infection in mice, determined that levels of P. aeruginosa in mice were significantly reduced in the vaccinated group. Thus, tests confirmed ability of this conjugate to elicit protective and opsonophagocytic antibodies that candidate our vaccine for further studies.

  18. Zinc Improves Biocontrol of Fusarium Crown and Root Rot of Tomato by Pseudomonas fluorescens and Represses the Production of Pathogen Metabolites Inhibitory to Bacterial Antibiotic Biosynthesis.

    Science.gov (United States)

    Duffy, B K; Défago, G

    1997-12-01

    ABSTRACT Crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici is an increasing problem in Europe, Israel, Japan, and North America. The biocontrol agent Pseudomonas fluorescens strain CHA0 provides only moderate control of this disease. A one-time amendment of zinc EDTA at 33 mug of Zn(2+)/ml to hydroponic nutrient solution in soilless rockwool culture did not reduce disease when used alone, but did reduce disease by 25% in the presence of CHA0. In in vitro studies with the pathogen, zinc at concentrations as low as 10 mug/ml abolished production of the phytotoxin fusaric acid, a Fusarium pathogenicity factor, and increased production of microconidia over 100-fold, but reduced total biomass. Copper EDTA at 33 mug of Cu(2+)/ml had a similar effect as zinc on the pathogen in vitro; it reduced disease when used alone, and increased the biocontrol activity of CHA0 in soilless culture. Ammonium-molybdate neither improved the biocontrol activity of CHA0 nor affected production of fusaric acid or microconidia. Strain CHA0 did not degrade fusaric acid. Fusaric acid at concentrations as low as 0.12 mug/ml repressed production by CHA0 of the antibiotic 2,4-diacetylphloroglucinol, a key factor in the biocontrol activity of this strain. Production of pyoluteorin by CHA0 was also reduced, but production of hydrogen cyanide and protease was not affected, suggesting that fusaric acid affects biosynthesis at a regulatory level downstream of gacA and apdA genes. Fusaric acid did not affect the recovery of preformed antibiotics nor did it affect bacterial growth even at concentrations as high as 200 mug/ml. When microbial meta-bolite production was measured in the rockwool bioassay, zinc amendments reduced fusaric acid production and enhanced 2,4-diacetylphloro-glucinol production. We suggest that zinc, which did not alleviate the repression of antibiotic biosynthesis by fusaric acid, improved biocontrol activity by reducing fusaric acid production by

  19. Efficacy of spray –Dried Pseudomonas fluorescens, strain CL145A (Zequanox®), for controlling Zebra Mussels (Dreissena polymorpha) within Lake Minnetonka, MN enclosures

    Science.gov (United States)

    Luoma, James A.; Severson, Todd J.

    2016-01-01

    The efficacy of whole water column and subsurface applications of the biopesticide Zequanox®, a commercially prepared spray-dried powder formulation of Pseudomonas fluorescens (strain CL145A), were evaluated for controlling zebra mussels (Dreissena polymorpha) within 27-m2 enclosures in Lake Minnetonka (Deephaven, Minnesota). Five treatments consisting of (1) two whole water column Zequanox applications, (2) two subsurface Zequanox applications, and (3) an untreated control were completed on each of three independent treatment days during September 2014. The two types of samplers used in the study were (1) type 1 samplers, which were custom built multi-plate samplers (wood, perforated aluminum, and tile substrates) that were placed into Robinson’s Bay in June of 2013 to allow for natural colonization by zebra mussels, and (2) type 2 samplers, which consisted of zebra mussels adhering to perforated aluminum trays that were placed into mesh containment bags. One day prior to treatment, three individual samplers of each type were distributed to test enclosures and exposed to a randomly assigned treatment. Sampling to determine the zebra mussel biomass adhering to type 1 samplers and the survival assessments for zebra mussels contained in type 2 samplers were completed ~40 days after exposure. The zebra mussel biomass adhering to type 1 samplers and the survival of zebra mussels contained in type 2 samplers were significantly less in groups treated with the highest Zequanox concentrations and in groups that received whole water column applications than comparable groups treated with lower Zequanox concentrations and subsurface applications. However, standardization of biomass and survival results to the amount of Zequanox applied showed that the lower concentrations and subsurface applications were more cost efficient, with respect to product used, at reducing zebra mussel biomass and for inducing zebra mussel mortality. Although the subsurface application methods

  20. The interplay of StyR and IHF regulates substrate-dependent induction and carbon catabolite repression of styrene catabolism genes in Pseudomonas fluorescens ST

    Directory of Open Access Journals (Sweden)

    Leoni Livia

    2008-06-01

    Full Text Available Abstract Background In Pseudomonas fluorescens ST, the promoter of the styrene catabolic operon, PstyA, is induced by styrene and is subject to catabolite repression. PstyA regulation relies on the StyS/StyR two-component system and on the IHF global regulator. The phosphorylated response regulator StyR (StyR-P activates PstyA in inducing conditions when it binds to the high-affinity site STY2, located about -40 bp from the transcription start point. A cis-acting element upstream of STY2, named URE, contains a low-affinity StyR-P binding site (STY1, overlapping the IHF binding site. Deletion of the URE led to a decrease of promoter activity in inducing conditions and to a partial release of catabolite repression. This study was undertaken to assess the relative role played by IHF and StyR-P on the URE, and to clarify if PstyA catabolite repression could rely on the interplay of these regulators. Results StyR-P and IHF compete for binding to the URE region. PstyA full activity in inducing conditions is achieved when StyR-P and IHF bind to site STY2 and to the URE, respectively. Under catabolite repression conditions, StyR-P binds the STY1 site, replacing IHF at the URE region. StyR-P bound to both STY1 and STY2 sites oligomerizes, likely promoting the formation of a DNA loop that closes the promoter in a repressed conformation. We found that StyR and IHF protein levels did not change in catabolite repression conditions, implying that PstyA repression is achieved through an increase in the StyR-P/StyR ratio. Conclusion We propose a model according to which the activity of the PstyA promoter is determined by conformational changes. An open conformation is operative in inducing conditions when StyR-P is bound to STY2 site and IHF to the URE. Under catabolite repression conditions StyR-P cellular levels would increase, displacing IHF from the URE and closing the promoter in a repressed conformation. The balance between the open and the closed

  1. Impact of higher alginate expression on deposition of Pseudomonas aeruginosa in radial stagnation point flow and reverse osmosis systems.

    Science.gov (United States)

    Herzberg, Moshe; Rezene, Tesfalem Zere; Ziemba, Christopher; Gillor, Osnat; Mathee, Kalai

    2009-10-01

    Extracellular polymeric substances (EPS) have major impact on biofouling of reverse osmosis (RO) membranes. On one hand, EPS can reduce membrane permeability and on the other, EPS production by the primary colonizers may influence their deposition and attachment rate and subsequently affect the biofouling propensity of the membrane. The role of bacterial exopolysaccharides in bacterial deposition followed by the biofouling potential of an RO membrane was evaluated using an alginate overproducing (mucoid) Pseudomonas aeruginosa. The mucoid P. aeruginosa PAOmucA22 was compared with its isogenic nonmucoid prototypic parent PAO1 microscopically in a radial stagnation point flow (RSPF) system for their bacterial deposition characteristics. Then, biofouling potential of PAO1 and PAOmucA22 was determined in a crossflow rectangular plate-and-frame membrane cell, in which the strains were cultivated on a thin-film composite, polyamide, flat RO membrane coupon (LFC-1) under laminar flow conditions. In the RSPF system, the observed deposition rate of the mucoid strain was between 5- and 10-fold lower than of the wild type using either synthetic wastewater medium (with ionic strength of 14.7 mM and pH 7.4) or 15 mM KCl solution (pH of 6.2). The slower deposition rate of the mucoid strain is explained by 5- to 25-fold increased hydrophilicity of the mucoid strain as compared to the isogenic wild type, PAO1. Corroborating with these results, a significant delay in the onset of biofouling of the RO membrane was observed when the mucoid strain was used as the membrane colonizer, in which the observed time for the induced permeate flux decline was delayed (ca. 2-fold). In conclusion, the lower initial cell attachment of the mucoid strain decelerated biofouling of the RO membrane. Bacterial deposition and attachment is a critical step in biofilm formation and governed by intimate interactions between outer membrane proteins of the bacteria and the surface. Shielding these

  2. Effects of the tomato pathogen Fusarium oxysporum f. sp. radicis-lycopersici and of the biocontrol bacterium Pseudomonas fluorescens WCS365 on the composition of organic acids and sugars in tomato root exudate.

    Science.gov (United States)

    Kamilova, Faina; Kravchenko, Lev V; Shaposhnikov, Alexander I; Makarova, Nataliya; Lugtenberg, Ben

    2006-10-01

    The effects of the pathogenic fungus Fusarium oxysporum f. sp. radicis-lycopersici and of the bacterial biocontrol strain Pseudomonas fluorescens WCS365, and of both microbes, on the amounts and composition of root exudate components of tomato plants grown in a gnotobiotic stonewool substrate system were studied. Conditions were selected under which introduction of F. oxysporum f. sp. radicis-lycopersici caused severe foot and root rot, whereas inoculation of the seed with P. fluorescens WCS365 decreased the percentage of diseased plants from 96 to 7%. This is a much better disease control level than was observed in potting soil. Analysis of root exudate revealed that the presence of F. oxysporum f. sp. radicis-lycopersici did not alter the total amount of organic acids, but that the amount of citric acid decreased and that of succinic acid increased compared with the nontreated control. In contrast, in the presence of the P. fluorescens biocontrol strain WCS365, the total amount of organic acid increased, mainly due to a strong increase of the amount of citric acid, whereas the amount of succinic acid decreased dramatically. Under biocontrol conditions, when both microbes are present, the content of succinic acid decreased and the level of citric acid was similar to that in the nontreated control. The amount of sugar was approximately half that of the control sample when either one of the microbes was present alone or when both were present. Analysis of the interactions between the two microbes grown together in sterile tomato root exudate showed that WCS365 inhibited multiplication of F. oxysporum f. sp. radicis-lycopersici, whereas the fungus did not affect the number of CFU of the bacterium.

  3. Nunamycin and Nunapeptin: Two novel cyclic peptides are key components of the antimicrobial activity of the Greenlandic isolate Pseudomonas fluorescens In5

    DEFF Research Database (Denmark)

    Hennessy, Rosanna Catherine; Phippen, Christopher; Nielsen, Kristian F.

    suppressive soil, P. fluorescens In5 is therefore a promising potential biocontrol agent with potent activity against plant pathogens. Studies to date have shown nunamycin and nunapeptin as key compounds underpinning this antimicrobial activity. A combination of molecular genetic strain manipulations and omic...

  4. Characterization of the CrbS/R Two-Component System in Pseudomonas fluorescens Reveals a New Set of Genes under Its Control and a DNA Motif Required for CrbR-Mediated Transcriptional Activation

    Directory of Open Access Journals (Sweden)

    Edgardo Sepulveda

    2017-11-01

    Full Text Available The CrbS/R system is a two-component signal transduction system that regulates acetate utilization in Vibrio cholerae, P. aeruginosa, and P. entomophila. CrbS is a hybrid histidine kinase that belongs to a recently identified family, in which the signaling domain is fused to an SLC5 solute symporter domain through aSTAC domain. Upon activation by CrbS, CrbR activates transcription of the acs gene, which encodes an acetyl-CoA synthase (ACS, and the actP gene, which encodes an acetate/solute symporter. In this work, we characterized the CrbS/R system in Pseudomonas fluorescens SBW25. Through the quantitative proteome analysis of different mutants, we were able to identify a new set of genes under its control, which play an important role during growth on acetate. These results led us to the identification of a conserved DNA motif in the putative promoter region of acetate-utilization genes in the Gammaproteobacteria that is essential for the CrbR-mediated transcriptional activation of genes under acetate-utilizing conditions. Finally, we took advantage of the existence of a second SLC5-containing two-component signal transduction system in P. fluorescens, CbrA/B, to demonstrate that the activation of the response regulator by the histidine kinase is not dependent on substrate transport through the SLC5 domain.

  5. Carvacrol and 1,8-cineole alone or in combination at sublethal concentrations induce changes in the cell morphology and membrane permeability of Pseudomonas fluorescens in a vegetable-based broth.

    Science.gov (United States)

    de Sousa, Jossana Pereira; Torres, Rayanne de Araújo; de Azerêdo, Geíza Alves; Figueiredo, Regina Célia Bressan Queiroz; Vasconcelos, Margarida Angélica da Silva; de Souza, Evandro Leite

    2012-08-01

    This study aimed to investigate the effects of sublethal concentrations of carvacrol (CAR) and 1,8-cineole (CIN) alone and in combination on the morphology, cell viability and membrane permeability of Pseudomonas fluorescens ATCC 11253 cultivated in a vegetable-based broth. Transmission and scanning electron microscopy images of bacterial cells exposed to CAR and CIN alone or in combination showed marked ultrastructural changes after 1h of exposure. These changes included shrunken protoplasm, discontinuity of the outer and cytoplasmic membranes and leakage of the intracellular material. Confocal scanning laser microscopy images corroborated the electron microscopy data, showing a decrease in the number of SYTO-9 cells (intact cells) with a concomitant increase in the number of PI-positive cells (dead cells). All of these morphological changes are indicative of increased membrane permeability and the loss of bacterial envelope integrity, which ultimately lead to cell death. The combination of sublethal concentrations of CAR and CIN could be applied to inhibit the growth of P. fluorescens on vegetables. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Kinetics of biofilm formation and desiccation survival of Listeria monocytogenes in single and dual species biofilms with Pseudomonas fluorescens, Serratia proteamaculans or Shewanella baltica on food-grade stainless steel surfaces.

    Science.gov (United States)

    Daneshvar Alavi, Hessam Edin; Truelstrup Hansen, Lisbeth

    2013-01-01

    This study investigated the dynamics of static biofilm formation (100% RH, 15 °C, 48-72 h) and desiccation survival (43% RH, 15 °C, 21 days) of Listeria monocytogenes, in dual species biofilms with the common spoilage bacteria, Pseudomonas fluorescens, Serratia proteamaculans and Shewanella baltica, on the surface of food grade stainless steel. The Gram-negative bacteria reduced the maximum biofilm population of L. monocytogenes in dual species biofilms and increased its inactivation during desiccation. However, due to the higher desiccation resistance of Listeria relative to P. fluorescens and S. baltica, the pathogen survived in greater final numbers. In contrast, S. proteamaculans outcompeted the pathogen during the biofilm formation and exhibited similar desiccation survival, causing the N21 days of Serratia to be ca 3 Log10(CFU cm(-2)) greater than that of Listeria in the dual species biofilm. Microscopy revealed biofilm morphologies with variable amounts of exopolymeric substance and the presence of separate microcolonies. Under these simulated food plant conditions, the fate of L. monocytogenes during formation of mixed biofilms and desiccation depended on the implicit characteristics of the co-cultured bacterium.

  7. The role of fluoroquinolones in the promotion of alginate synthesis and antibiotic resistance in Pseudomonas aeruginosa.

    Science.gov (United States)

    Piña, S E; Mattingly, S J

    1997-08-01

    Treatment of nonmucoid Pseudomonas aeruginosa with gyrase inhibitors such as ciprofloxacin, norfloxacin, and ofloxacin, which target the A subunit of topoisomerase II, resulted in 100% conversion to the mucoid phenotype. However, antibiotics that partially inhibited growth and macromolecular synthesis (DNA, RNA, protein, or peptidoglycan) of nonmucoid isolates in a gluconate-limited chemostat culture system did not promote conversion to mucoid subpopulations. An increase in resistance was observed in populations that expressed the mucoid phenotype. Both mucoid conversion and antibiotic resistance were completely reversible when ciprofloxacin pressure was withdrawn, but only partially reversible by the removal of norfloxacin and ofloxacin. Thus, these experiments indicate that in the presence of some fluoroquinolones, a conditional response resulting in mucoid conversion and antibiotic resistance may occur.

  8. Gene-scrambling mutagenesis: generation and analysis of insertional mutations in the alginate regulatory region of Pseudomonas aeruginosa.

    Science.gov (United States)

    Mohr, C D; Deretic, V

    1990-11-01

    A novel method for random mutagenesis of targeted chromosomal regions in Pseudomona aeruginosa was developed. This method can be used with a cloned DNA fragment of indefinite size that contains a putative gene of interest. Cloned DNA is digested to produce small fragments that are then randomly reassembled into long DNA inserts by using cosmid vectors and lambda packaging reaction. This DNA is then transferred into P. aeruginosa and forced into the chromosome via homologous recombination, producing in a single step a random set of insertional mutants along a desired region of the chromosome. Application of this method to extend the analysis of the alginate regulatory region, using a cloned 6.2-kb fragment with the algR gene and the previously uncharacterized flanking regions, produced several insertional mutations. One mutation was obtained in algR, a known transcriptional regulatory of mucoidy in P. aeruginosa. The null mutation of algR was generated in a mucoid derivative of the standard genetic strain PAO responsive to different environmental factors. This mutation was used to demonstrate that the algR gene product was not essential for the regulation of its promoters. Additional insertions were obtained in regions downstream and upstream of algR. A mutation that did not affect mucoidy was generated in a gene located 1 kb upstream of algR. This gene was transcribed in the direction opposite that of algR transcription and encoded a polypeptide of 47 kDa. Partial nucleotide sequence analysis revealed strong homology of its predicted gene product with the human and yeast argininosuccinate lyases. An insertion downstream of algR produced a strain showing reduced induction of mucoidy in response to growth on nitrate as the nitrogen source.

  9. Pseudomonas aeruginosa biofilms exposed to imipenem exhibit changes in global gene expression and beta-lactamase and alginate production

    DEFF Research Database (Denmark)

    Bagge, Niels; Schuster, Martin; Hentzer, Morten

    2004-01-01

    . As expected, the most strongly induced gene was ampC, which codes for chromosomal beta-lactamase. We also found that genes coding for alginate biosynthesis were induced by exposure to imipenem. Alginate production is correlated to the development of impaired lung function, and P. aeruginosa strains isolated...... from chronically colonized lungs of CF patients are nearly always mucoid due to the overproduction of alginate. Exposure to subinhibitory concentrations of imipenem caused structural changes in the biofilm, e.g., an increased biofilm volume. Increased levels of alginate production may be an unintended...

  10. INOCULACIÓN AL SUELO CON Pseudomonas fluorescens, Azospirillum oryzae, Bacillus subtilis Y MICROORGANISMOS DE MONTAÑA (MM Y SU EFECTO SOBRE UN SISTEMA DE ROTACIÓN SOYA-TOMATE BAJO CONDICIONES DE INVERNADERO

    Directory of Open Access Journals (Sweden)

    Leida Castro Barquero

    2015-01-01

    Full Text Available Se evaluó un sistema de rotación soya- tomate, con incorporación de biomasa verde y aplicación de inóculos microbianos individuales y en mezcla sobre el crecimiento de las plantas y propiedades edáficas; para ello se evaluaron en invernadero por 24 meses los siguientes 9 trata - mientos: solo tomate (T; rotación tomate-soya (TS; rotación tomate-soya con inoculaciones individuales de Azospirillum oryzae (A; de Pseudomonas fluorescens (P; de Bacillus sub - tilis (B; de microorganismos de montaña (MM; y las inoculaciones en mezcla de B. subtilis y P. fluorescens (BP; de B. subtilis, P. fluorescens y A. oryzae ( BPA; d e B. subtilis , P. fluorescens , Azospirillum sp. y MM (BPAMM. Se evalua - ron las variables físicas: densidad aparente y de partículas; conductividad hidráulica; poros totales; estabilidad de agregados; resistencia a la penetración (RP; las variables químicas: pH; conductividad eléctrica; contenido de N y C; relación C/N; contenido de nutrientes en suelos y foliares; las variables biológicas: respiración de suelos, unidades formadoras de colonias de hongos, bacterias y actinomicetos y el peso fres - co y seco foliar. Las variables físicas no fueron afectadas por los tratamientos, con excepción de RP, que fue mayor en el tratamiento T. Las varia - bles biológicas y químicas fueron sensibles a los tratamientos, con valores significativamente más altos en presencia de MM. Destaca el incremento del P en solución de suelo en tratamientos a los que se adicionó MM: pasó de 6 a 20 mg.l -1 ; esta condición se reflejó además en la cantidad de P en el tejido foliar al final del ensayo. Se determi - nó que el pH, CE y la respiración del suelo fueron afectados por la interacción entre los tratamientos aplicados y el tiempo transcurrido; los mayores valores se obtuvieron al final del ensayo y en los tratamientos con MM.

  11. Inoculación al suelo con Pseudomonas fluorescens, Azospirillum oryzae, Bacillus subtilis y microorganismos de montaña (mm y su efecto sobre un sistema de rotación soya-tomate bajo condiciones de invernadero

    Directory of Open Access Journals (Sweden)

    Leida Castro Barquero

    2015-11-01

    Full Text Available Se evaluó un sistema de rotación soyatomate, con incorporación de biomasa verde y aplicación de inóculos microbianos individuales y en mezcla sobre el crecimiento de las plantas y propiedades edáficas; para ello se evaluaron en invernadero por 24 meses los siguientes 9 tratamientos: solo tomate (T; rotación tomate-soya (TS; rotación tomate-soya con inoculaciones individuales de Azospirillum oryzae (A; de Pseudomonas fluorescens (P; de Bacillus subtilis (B; de microorganismos de montaña (MM; y las inoculaciones en mezcla de B. subtilis y P. fluorescens (BP; de B. subtilis, P. fluorescens y A. oryzae (BPA; de B. subtilis, P. fluorescens, Azospirillum sp. y MM (BPAMM. Se evaluaron las variables físicas: densidad aparente y de partículas; conductividad hidráulica; poros totales; estabilidad de agregados; resistencia a la penetración (RP; las variables químicas: pH; conductividad eléctrica; contenido de N y C; relación C/N; contenido de nutrientes en suelos y foliares; las variables biológicas: respiración de suelos, unidades formadoras de colonias de hongos, bacterias y actinomicetos y el peso fresco y seco foliar. Las variables físicas no fueron afectadas por los tratamientos, con excepción de RP, que fue mayor en el tratamiento T. Las variables biológicas y químicas fueron sensibles a los tratamientos, con valores significativamente más altos en presencia de MM. Destaca el incremento del P en solución de suelo en tratamientos a los que se adicionó MM: pasó de 6 a 20 mg.l-1; esta condición se reflejó además en la cantidad de P en el tejido foliar al final del ensayo. Se determinó que el pH, CE y la respiración del suelo fueron afectados por la interacción entre los tratamientos aplicados y el tiempo transcurrido; los mayores valores se obtuvieron al final del ensayo y en los tratamientos con MM.

  12. Control of Fusarium verticillioides, cause of ear rot of maize, by Pseudomonas fluorescens

    DEFF Research Database (Denmark)

    Nayaka, Siddaiah Chandra; Shankar, Akarere C. Udaya; Reddy, Munagala S.

    2009-01-01

    Abstract BACKGROUND: Maize is one of the staple food crops grown in India. Fusarium verticillioides (Sacc.) Nirenberg is the most important fungal pathogen of maize, associated with diseases such as ear rot and kernel rot. Apart from the disease, it is capable of producing fumonisins, which have...... and the formulations, in comparison with the control, increased plant growth and vigour as measured by seed germination, seedling vigour, plant height, 1000 seed weight and yield. P. fluorescens pure culture used as seed treatment and as spray treatment enhanced the growth parameters and reduced the incidence of F....... verticillioides and the level of fumonisins to a maximum extent compared with the other treatments. CONCLUSION: The study demonstrates the potential role of P. fluorescens and its formulations in ear rot disease management. The biocontrol potential of this isolate is more suited for fumonisin reduction in maize...

  13. In vitro inoculation of Aeromonas hydrophila and Pseudomonas fluorescens in cryopreserved silver barb (Barbodes gonionotus) milt: Effect on fertilization capacity and transmission potential to embryos.

    Science.gov (United States)

    Boonthai, Traimat; Khaopong, Weerasith; Sangsong, Jumlong; Vuthiphandchai, Verapong; Nimrat, Subuntith

    2017-11-16

    Purposive use of cryopreserved sperm contaminated with pathogenic agents has increased the risk of spreading of fish diseases. The objective of this study was to investigate the effects of A. hydrophila subsp. hydrophila and P. fluorescens inoculations into cryostored milt on fertilization capacity and transmission potential to embryos of silver barb (Barbodes gonionotus) with or without 0.25% penicillin-streptomycin (PS) administration. The experiment comprised six treatments: addition of milt into T1) extender only, T2) extender with 0.25% PS, T3) extender with A. hydrophila subsp. hydrophila (BG19), T4) extender with A. hydrophila subsp. hydrophila (BG19) and 0.25% PS, T5) extender with P. fluorescens (BG20) and T6) extender with P. fluorescens (BG20) and 0.25% PS. Milt were loaded into 0.25-mL straws and cryostored in the controlled-rate programmable freezer. After a cryostorage for 28 d, post-thawed sperm were evaluated for the fertilization capacity and risk of pathogen transmission to embryos. Inoculation of A. hydrophila subsp. hydrophila and P. fluorescens into extended milt (T3 and T5) caused a reduction (P fertilization capacity of cryopreserved sperm. Cryopreserved sperm inoculated with the two pathogenic bacteria and 0.25% PS (T4 and T6) did not fertilize the eggs. The two pathogenic bacteria could be transmitted into embryos after artificial insemination of eggs with bacterial-inoculated cryopreserved sperm, suggesting that the risks of disease transmission via cryopreserved fish sperm would exist. This is the first study reporting pathogenic bacterial transmission on in vitro fish embryos through artificial insemination of cryopreserved sperm. Copyright © 2017. Published by Elsevier Inc.

  14. Evaluation of gamma irradiation effect and Pseudomonas ...

    African Journals Online (AJOL)

    Antagonistic effect of Pseudomonas fluorescens and influence of gamma irradiation on the development of Penicillium expansum, the causal agent of postharvest disease on apple fruit was studied. P. fluorescens was originally isolated from rhizosphere of the apple trees. Suspension of P. fluorescens and P. expansum ...

  15. Efficiency of the formulated plant-growth promoting Pseudomonas fluorescens MC46 inoculant on triclocarban treatment in soil and its effect on Vigna radiata growth and soil enzyme activities.

    Science.gov (United States)

    Sipahutar, Merry Krisdawati; Piapukiew, Jittra; Vangnai, Alisa S

    2018-02-15

    For bioaugmentation-based treatment of triclocarban (TCC), an emerging soil pollutant that is recalcitrant to biodegradation and phytotransformation, efficient TCC-degrading bacteria with an effective soil-delivering means are required. This work developed the formulated bacterial inoculant, and successfully demonstrated its TCC removal and detoxification performance in pot soil experiment with Vigna radiata plants. The soil bacterium Pseudomonas fluorescens MC46 was isolated as TCC-degrading, plant-growth promoting bacterium. The characterizations were conducted in vitro revealing that it could utilize TCC as a sole carbon source, and at a wide and higher concentration range from 1.6-31.6mgkg -1 than those previously reported, while the detoxification was assessed by cytogenotoxicity and phytotoxicity tests. The developed sawdust-based inoculant formula combined with molasses (5% w/w), and either PEG or CMC-starch blend (1% w/w) could maintain a 20-week shelf-life inoculant stability in terms of cell viability, and TCC-degrading activity. Bioaugmentation of the formulated inoculants into TCC-contaminated soil efficiently removed TCC up to 74-76% of the initial concentration, mitigated toxicity, restored plant growth and health, and enhanced soil enzyme activities. This work is the first to demonstrate potential application of the formulated plant-growth promoting bacterial inoculant for the treatment and detoxification of a persistent TCC contaminated in soil. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Alkaline lipase from Pseudomonas fluorescens non-covalently immobilised on pristine versus oxidised multi-wall carbon nanotubes as efficient and recyclable catalytic systems in the synthesis of Solketal esters.

    Science.gov (United States)

    Boncel, Sławomir; Zniszczoł, Aurelia; Szymańska, Katarzyna; Mrowiec-Białoń, Julita; Jarzębski, Andrzej; Walczak, Krzysztof Z

    2013-09-10

    In order to produce effective and recyclable catalysts for enantioselective transesterification in the industrial applications, alkaline lipase from Pseudomonas fluorescens was non-covalently immobilised (ca. 6 wt%) on pristine multi-wall carbon nanotubes (MWCNTs) and oxidised MWCNTs (O-MWCNTs) using an adsorption technique. Mesoporous silica modified with n-octyl groups was used as a reference support. Irreversible transesterifications of three vinyl esters (acyl donors) by racemic Solketal with a chromatographically (GC) traced kinetics were selected as model reactions. The undertaken comparative studies revealed that different morphology and chemical functionalisation of the supports led to various enzyme loadings, catalytic activities and enantioselectivities. MWCNT-lipase emerged as the exceptionally active (yield up to 98%, t=1h, 1320 Ug(-1), i.e. 9 times more active than native enzyme) whereas lipase immobilised on O-MWCNTs as the most enantioselective system, particularly for longer acyl chain esters (e.e. up to 72% after 30 min at yield of 20%, 340 Ug(-1)). Moreover, the activity of all nanotube-based catalysts after 10 cycles of transesterification remained practically unchanged. The differences in performance of MWCNTs and O-MWCNTs as solid supports were found to be based on geometry of pores, dominating hydrophobic interactions and absence/presence of the surface polar groups. Due to an excellent activity and reusability of the nanotube-lipase catalysts one can propose (O-)MWCNT as supports of a prospective industrial relevance. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M114: evidence for the involvement of iron, the ECF sigma factor, PbrA and pseudobactin M114 siderophore.

    Science.gov (United States)

    Maunsell, Bláithín; Adams, Claire; O'Gara, Fergal

    2006-01-01

    In the soil bacterium Pseudomonas fluorescens M114, extracellular proteolytic activity and fluorescent siderophore (pseudobactin M114) production were previously shown to be co-ordinately negatively regulated in response to environmental iron levels. An iron-starvation extracytoplasmic function sigma factor, PbrA, required for the transcription of siderophore biosynthetic genes, was also implicated in M114 protease regulation. The current study centred on the characterization and genetic regulation of the gene(s) responsible for protease production in M114. A serralysin-type metalloprotease gene, aprA, was identified and found to encode the major, if not only, extracellular protease produced by this strain. The expression of aprA and its protein product were found to be subject to complex regulation. Transcription analysis confirmed that PbrA was required for full aprA transcription under low iron conditions, while the ferric uptake regulator, Fur, was implicated in aprA repression under high iron conditions. Interestingly, the iron regulation of AprA was dependent on culture conditions, with PbrA-independent AprA-mediated proteolytic activity observed on skim milk agar supplemented with yeast extract, when supplied with iron or purified pseudobactin M114. These effects were not observed on skim milk agar without yeast extract. PbrA-independent aprA expression was also observed from a truncated transcriptional fusion when grown in sucrose asparagine tryptone broth supplied with iron or purified pseudobactin M114. Thus, experimental evidence suggested that iron mediated its effects via transcriptional activation by PbrA under low iron conditions, while an as-yet-unidentified sigma factor(s) may be required for the PbrA-independent aprA expression and AprA proteolytic activity induced by siderophore and iron.

  18. High mannose-binding antiviral lectin PFL from Pseudomonas fluorescens Pf0-1 promotes cell death of gastric cancer cell MKN28 via interaction with α2-integrin.

    Directory of Open Access Journals (Sweden)

    Yuichiro Sato

    Full Text Available Novel anti-HIV lectin family which shows a strict binding specificity for high mannose glycans has been found in lower organisms. The bacterial orthologue has been identified in the genome of Pseudomonas fluorescens Pf0-1 and the gene coding a putative lectin was cloned, expressed in Escherichia coli and purified by one step gel filtration. Glycan array screening of the recombinant lectin, termed PFL, has revealed that PFL preferentially recognizes high mannose glycans with α1-3 Man that was highly exposed at the D2 position. In contrast, masking of this α1-3 Man with α1-2 Man dramatically impaired lectin-carbohydrate interactions. Reducing terminal disaccharide, GlcNAc-GlcNAc of high mannose glycans was also essential for PFL-binding. PFL showed a potent anti-influenza virus activity by inhibiting the virus entry into cells at doses of low nanomolar concentration. At micromolar concentration or higher, PFL showed a cytotoxicity accompanying loss of the cell adhesion against human gastric cancer MKN28 cells. The cell surface molecule to which PFL bound was co-precipitated with biotin-labeled PFL and identified as integrin α2 by peptide mass fingerprinting using MALDI-TOF mass spectrometry. Intriguingly, upon treatment with exogenous PFL, integrin α2 on the cell surface underwent rapid internalization to the cytoplasm and accumulated to perinuclear region, together with the bound PFL. The resulting loss of cell adherence would trigger a signaling pathway that induced anoikis-like cell death. These events were effectively inhibited by pretreatment of PFL with mannnan, indicating the involvement of high mannose glycans on PFL-induced cell death that was triggered by PFL-integrin α2 interactions.

  19. Evaluation of economically feasible, natural plant extract-based microbiological media for producing biomass of the dry rot biocontrol strain Pseudomonas fluorescens P22Y05 in liquid culture.

    Science.gov (United States)

    Khalil, Sadia; Ali, Tasneem Adam; Skory, Chris; Slininger, Patricia J; Schisler, David A

    2016-02-01

    The production of microbial biomass in liquid media often represents an indispensable step in the research and development of bacterial and fungal strains. Costs of commercially prepared nutrient media or purified media components, however, can represent a significant hurdle to conducting research in locations where obtaining these products is difficult. A less expensive option for providing components essential to microbial growth in liquid culture is the use of extracts of fresh or dried plant products obtained by using hot water extraction techniques. A total of 13 plant extract-based media were prepared from a variety of plant fruits, pods or seeds of plant species including Allium cepa (red onion bulb), Phaseolus vulgaris (green bean pods), and Lens culinaris (lentil seeds). In shake flask tests, cell production by potato dry rot antagonist Pseudomonas fluorescens P22Y05 in plant extract-based media was generally statistically indistinguishable from that in commercially produced tryptic soy broth and nutrient broth as measured by optical density and colony forming units/ml produced (P ≤ 0.05, Fisher's protected LSD). The efficacy of biomass produced in the best plant extract-based media or commercial media was equivalent in reducing Fusarium dry rot by 50-96% compared to controls. In studies using a high-throughput microbioreactor, logarithmic growth of P22Y05 in plant extract-based media initiated in 3-5 h in most cases but specific growth rate and the time of maximum OD varied as did the maximum pH obtained in media. Nutrient analysis of selected media before and after cell growth indicated that nitrogen in the form of NH4 accumulated in culture supernatants, possibly due to unbalanced growth conditions brought on by a scarcity of simple sugars in the media tested. The potential of plant extract-based media to economically produce biomass of microbes active in reducing plant disease is considerable and deserves further research.

  20. Biodegradation of tetrahydrofuran by Pseudomonas oleovorans DT4 immobilized in calcium alginate beads impregnated with activated carbon fiber: mass transfer effect and continuous treatment.

    Science.gov (United States)

    Chen, Dong-Zhi; Fang, Jun-Yi; Shao, Qian; Ye, Jie-Xu; Ouyang, Du-Juan; Chen, Jian-Meng

    2013-07-01

    A novel entrapment matrix, calcium alginate (CA) coupled with activated carbon fiber (ACF), was prepared to immobilize Pseudomonas oleovorans DT4 for degrading tetrahydrofuran (THF). The addition of 1.5% ACF increased the adsorption capacity of the immobilized bead, thus resulting in an enhanced average removal rate of 30.3mg/(Lh). The synergism between adsorption and biodegradation was observed in the hybrid CA-ACF beads instead of in the system comprising CA beads and freely suspended ACF. The effective diffusion coefficient of the CA-ACF bead was not significantly affected by bead size, but the bead's value of 1.14×10(-6)cm(2)/s (for the bead diameter of 0.4 cm) was larger than that of the CA bead by almost one order of magnitude based on the intraparticle diffusion-reaction kinetics analysis. Continuous treatment of the THF-containing wastewater was succeeded by CA-ACF immobilized cells in a packed-bed reactor for 54 d with a >90% removal efficiency. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Effectiveness of cleaning and sanitizing procedures in controlling the adherence of Pseudomonas fluorescens, Salmonella Enteritidis, and Staphylococcus aureus to domestic kitchen surfaces Eficiência dos procedimentos de limpeza e de sanitização no controle da adesão de Pseudomonas fluorescens, Salmonella Enteritidis e Staphylococcus aureus em superfícies usadas em cozinhas domésticas

    Directory of Open Access Journals (Sweden)

    Iara Dias Silva

    2010-03-01

    Full Text Available The effectiveness of cleaning and sanitizing procedures in controlling Staphylococcus aureus, Salmonella Enteritidis, and Pseudomonasfluorescens adhered to granite and stainless steel was evaluated. There was no significant difference (p > 0.05 in the adherence of pure cultures of these microorganisms to stainless steel. The numbers of P. fluorescens and S. Enteritidis adhered to granite were greater (p 0.05 between the surfaces. However, a significant difference was observed (p A eficiência dos procedimentos de limpeza e sanitização no controle de Staphylococcus aureus, Salmonella Enteritidis e Pseudomonasfluorescens aderidas em granito e aço inoxidável foi avaliada. Não houve diferença significativa (p > 0,05 na adesão destes microrganismos quando em cultura pura, em aço inoxidável. O número de células aderidas de P. fluorescens e S. Enteritidis foi maior (p 0,05 entre as superfícies. Entretanto, observou-se uma diferença (p < 0,05 entre as soluções sanitizantes utilizadas. Hipoclorito de sódio e ácido peracético apresentaram maior ação bactericida (p < 0,05 que o composto de amônia quaternária. Observou-se que S. aureus apresentou menor resistência à ação desses sanitizantes. Os resultados mostram a importância da adequada realização dos procedimentos de limpeza e sanitização para evitar a adesão bacteriana e formação de biofilme.

  2. Transesterification of Jatropha oil using immobilized Pseudomonas ...

    African Journals Online (AJOL)

    mild transesterification has become of much current interest for alternative fuel production. In the present study the ability of a commercial immobilized Pseudomonas fluorescens MTCC 103 to catalyze the transesterification of Jatropha oil and methanol was investigated. The cell of P. fluorescens was easily immobilized ...

  3. Carbazole-degradative IncP-7 plasmid pCAR1.2 is structurally unstable in Pseudomonas fluorescens Pf0-1, which accumulates catechol, the intermediate of the carbazole degradation pathway.

    Science.gov (United States)

    Takahashi, Yurika; Shintani, Masaki; Li, Li; Yamane, Hisakazu; Nojiri, Hideaki

    2009-06-01

    We determined the effect of the host on the function and structure of the nearly identical IncP-7 carbazole-degradative plasmids pCAR1.1 and pCAR1.2. We constructed Pseudomonas aeruginosa PAO1(pCAR1.2) and P. fluorescens Pf0-1Km(pCAR1.2) and compared their growth on carbazole- and succinate-containing media with that of P. putida KT2440(pCAR1.1). We also assessed the stability of the genetic structures of the plasmids in each of the three hosts. Pf0-1Km(pCAR1.2) showed dramatically delayed growth when carbazole was supplied as the sole carbon source, while the three strains grew at nearly the same rate on succinate. Among the carbazole-grown Pf0-1Km(pCAR1.2) cells, two types of deficient strains appeared and dominated the population; such dominance was not observed in the other two strains or for succinate-grown Pf0-1Km(pCAR1.2). Genetic analysis showed that the two deficient strains possessed pCAR1.2 derivatives in which the carbazole-degradative car operon was deleted or its regulatory gene, antR, was deleted by homologous recombination between insertion sequences. From genomic information and quantitative reverse transcription-PCR analyses of the genes involved in carbazole mineralization by Pf0-1Km(pCAR1.2), we found that the cat genes on the chromosome of Pf0-1Km, which are necessary for the degradation of catechol (a toxic intermediate in the carbazole catabolic pathway), were not induced in the presence of carbazole. The resulting accumulation of catechol may have enabled the strain that lost its carbazole-degrading ability to have overall higher fitness than the wild-type strain. These results suggest that the functions of the chromosomal genes contributed to the selection of plasmid derivatives with altered structures.

  4. Modulation of behaviour and virulence of a high alginate expressing Pseudomonas aeruginosa strain from cystic fibrosis by oral commensal bacterium Streptococcus anginosus.

    Directory of Open Access Journals (Sweden)

    Richard D Waite

    Full Text Available Cystic fibrosis (CF airways harbour complex and dynamic polymicrobial communities that include many oral bacteria. Despite increased knowledge of CF airway microbiomes the interaction between established CF pathogens and other resident microbes and resulting impact on disease progression is poorly understood. Previous studies have demonstrated that oral commensal streptococci of the Anginosus group (AGS can establish chronic pulmonary infections and become numerically dominant in CF sputa indicating that they play an important role in CF microbiome dynamics. In this study a strain of Pseudomonas aeruginosa (DWW2 of the mucoid alginate overproducing phenotype associated with chronic CF airway infection and a strain of the oral commensal AGS species Streptococcus anginosus (3a from CF sputum were investigated for their ability to co-exist and their responses to biofilm co-culture. Bacteria in biofilms were quantified, pyocyanin expression by DWW2 was measured and the effect of AGS strain 3a on reversion of DWW2 to a non-mucoidal phenotype investigated. The virulence of DWW2, 3a and colony variant phenotypes of DWW2 in mono- and co-culture were compared in a Galleria mellonella infection model. Co-culture biofilms were formed in normoxic, hypercapnic (10% CO2 and anoxic atmospheres with the streptococcus increasing in number in co-culture, indicating that these bacteria would be able to co-exist and thrive within the heterogeneous microenvironments of the CF airway. The streptococcus caused increased pyocyanin expression by DWW2 and colony variants by stimulating reversion of the mucoid phenotype to the high pyocyanin expressing non-mucoid phenotype. The latter was highly virulent in the infection model with greater virulence when in co-culture with the streptococcus. The results of this study demonstrate that the oral commensal S. anginosus benefits from interaction with P. aeruginosa of the CF associated mucoid phenotype and modulates the

  5. Kinetics studies of p-cresol biodegradation by using Pseudomonas putida in batch reactor and in continuous bioreactor packed with calcium alginate beads.

    Science.gov (United States)

    Mathur, A K; Bala, Shashi; Majumder, C B; Sarkar, S

    2010-01-01

    Present study deals with the biodegradation of p-cresol by using Pseudomonas putida in a batch reactor and a continuous bioreactor packed with calcium alginate beads. The maximum specific growth rate of 0.8121 h(-1) was obtained at 200 mg L(-1) concentration of p-cresol in batch reactor. The maximum p-cresol degradation rate was obtained 6.598 mg L(-1) h(-1) at S(o)=200 mg L(-1) and 62.8 mg L(-1) h(-1) at S(o)=500 mg L(-1) for batch reactor and a continuous bioreactor, respectively. The p-cresol degradation rate of continuous bioreactor was 9 to 10-fold higher than those of the batch reactor. It shows that the continuous bioreactor could tolerate a higher concentration of p-cresol. A Haldane model was also used for p-cresol inhibition in batch reactor and a modified equation similar to Haldane model for continuous bioreactor. The Haldane parameters were obtained as µ(max) 0.3398 h(-1), K(s) 110.9574 mg L(-1), and K(I) 497.6169 mg L(-1) in batch reactor. The parameters used in continuous bioreactor were obtained as D(max) 91.801 mg L(-1) h(-1), K(s) 131.292 mg L(-1), and K(I) 1217.7 mg L(-1). The value K(I) of continuous bioreactor is approximately 2.5 times higher than the batch reactor. Higher K(I) value of continuous bioreactor indicates P. putida can grow at high range of p-cresol concentration. The ability of tolerance of higher p-cresol concentrations may be one reason for biofilm attachment on the packed bed in the continuous operation.

  6. Colony morphology and transcriptome profiling of Pseudomonas putida KT2440 and its mutants deficient in alginate or all EPS synthesis under controlled matric potentials

    DEFF Research Database (Denmark)

    Gülez, Gamze; Altintas, Ali; Fazli, Mustafa

    2014-01-01

    of water limitation. In addition to alginate, P. putida is capable of producing cellulose (bcs), putida exopolysaccharide a (pea), and putida exopolysaccharide b (peb). However, unlike alginate, not much is known about their roles under water limitation. Hence, in this study we examined the role...... active to maintain homeostasis. To test our hypothesis, we investigated colony morphologies and whole genome transcriptomes of P. putida KT2440 wild type and its mutants deficient in synthesis of either alginate or all known EPS. Overall our results support that alginate is an important exopolysaccharide...

  7. Interacción sinérgica entre hongos formadores de micorrizas arbusculares - Pseudomonas fluorescens y su relación en la nutrición vegetal de fósforo / Synergic interaction between arbuscular mycorrhizal fungi and Pseudomonas fluorescens and its effect on plant phosphorus uptake

    OpenAIRE

    Ordoñez Castañeda, Yuli Marcela

    2009-01-01

    Ciertos microorganismos (género Pseudomonas) y Hongos Formadores de Micorrizas Arbusculares (HFMA) tienen la habilidad de incrementar el fósforo disponible para la planta y mejorar la productividad de los cultivos agícolas. El uso coordinado de especies seleccionadas, tanto de bacterias como de HFMA, se convierte en una alternativa interesante, donde las bacterias liberan fosfatos y el micelio extraradical (MER) de este tipo de hongos puede movilizarlo hacia las raíces de la planta a la cual ...

  8. Alginate-modifying enzymes: Biological roles and biotechnological uses

    Directory of Open Access Journals (Sweden)

    Helga eErtesvåg

    2015-05-01

    Full Text Available Alginate denotes a group of industrially important 1-4-linked biopolymers composed of the C-5-epimers β-D-mannuronic acid (M and α-L-guluronic acid (G. The polysaccharide is manufactured from brown algae where it constitutes the main structural cell wall polymer. The physical properties of a given alginate molecule, e.g. gel-strength, water-binding capacity, viscosity and biocompatibility, are determined by polymer length, the relative amount and distribution of G residues and the acetyl content, all of which are controlled by alginate modifying enzymes. Alginate has also been isolated from some bacteria belonging to the genera Pseudomonas and Azotobacter, and bacterially synthesized alginate may be O-acetylated at O-2 and/or O-3. Initially, alginate is synthesized as polymannuronic acid, and some M residues are subsequently epimerized to G residues. In bacteria a mannuronan C-5-epimerase (AlgG and an alginate acetylase (AlgX are integral parts of the protein complex necessary for alginate polymerisation and export. All alginate-producing bacteria use periplasmic alginate lyases to remove alginate molecules aberrantly released to the periplasm. Alginate lyases are also produced by organisms that utilize alginate as carbon source. Most alginate-producing organisms encode more than one mannuronan C-5 epimerase, each introducing its specific pattern of G residues. Acetylation protects against further epimerization and from most alginate lyases. One enzyme with alginate deacetylase activity from Pseudomonas syringae has been reported. Functional and structural studies reveal that alginate lyases and epimerases have related enzyme mechanisms and catalytic sites. Alginate lyases are now utilized as tools for alginate characterization. Secreted epimerases have been shown to function well in vitro, and have been engineered further in order to obtain enzymes that can provide alginates with new and desired properties for use in medical and

  9. Growth of Pseudomonas fluorescens on Cassava Starch ...

    African Journals Online (AJOL)

    Michael Horsfall

    (Potassium sodium tartarate) and 1% (w/v) sodium hydroxide. To prepare 1 – litre of solution, 10 g of sodium hydroxide pellet was dissolved in 1- litre of distilled water. To this was added 10 g of powdered. 3,5 – Di-nitrosalicylic acid, 0.5 g of sodium bisulphite, 2.52 ml of 80% Phenol and stirred to complete dissolution.

  10. Characterization and identification of Pseudomonas fluorescens ...

    African Journals Online (AJOL)

    If you would like more information about how to print, save, and work with PDFs, Highwire Press provides a helpful Frequently Asked Questions about PDFs. Alternatively, you can download the PDF file directly to your computer, from where it can be opened using a PDF reader. To download the PDF, click the Download link ...

  11. Peudomonas fluorescens diversity and abundance in the rhizosphere

    Science.gov (United States)

    Amina, Melinai; Ahmed, Bensoltane; Khaladi, Mederbel

    2010-05-01

    It is now over 30 years since that a several plant associated strains of fluorescent Pseudomonas spp. are known to produce antimicrobial metabolites, playing a significant role in the biological control of a lot of plant diseases. For that, the interest in the use of these bacteria for biocontrol of plant pathogenic agents has increased. However, few comprehensive studies have described the abundance of this soil borne bacteria in the region of Mascara (Northern-Algerian West). In the connection of this problem, this work was done by monitoring the number of indigenous Pseudomonas fluorescens organisms in three stations characterizing different ecosystems, to document their abundance, diversity and investigate the relationship between P. fluorescens abundance and soil properties. Our quantitative plate counting results hence the conception of their ecology in the rhizosphere. Thus, quantitative results has confirmed that P. fluorescens are successful root colonizers with strong predominance and competed for many ecological niche, where their distribution were correlated significantly (P<0.05) with the majority of soil properties. Keywords: P. Fluorescens, Ecosystems, Abundance, Diversity, Correlated, Soil Properties.

  12. Pseudomonas aeruginosa aggregate formation in an alginate bead model system exhibits In Vivo-like characteristics

    DEFF Research Database (Denmark)

    Sønderholm, Majken; Kragh, Kasper Nørskov; Koren, Klaus

    2017-01-01

    and reached anoxia ∼100 μm below the alginate bead surface. This gradient was relieved in beads supplemented with NO3− as an alternative electron acceptor allowing for deeper growth into the beads. A comparison of gene expression profiles between planktonic and alginate-encapsulated P. aeruginosa confirmed...... that the bacteria experienced hypoxic and anoxic growth conditions. Furthermore, alginate-encapsulated P. aeruginosa exhibited a lower respiration rate than the planktonic counterpart and showed a high tolerance toward antibiotics. The inoculation and growth of P. aeruginosa in alginate beads represent a simple...... and flexible in vivo-like biofilm model system, wherein bacterial growth exhibits central features of in vivo biofilms. This was observed by the formation of small cell aggregates in a secondary matrix with O2-limited growth, which was alleviated by the addition of NO3− as an alternative electron acceptor...

  13. Optimization of alkaline protease production from Pseudomonas ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-12-15

    Dec 15, 2009 ... A protease producing bacteria was isolated from meat waste contaminated soil and identified as. Pseudomonas ... Key words: Alkaline protease, casein agar, meat waste contaminated soil, Pseudomonas fluorescens. INTRODUCTION ... advent of new frontiers in biotechnology, the spectrum of protease ...

  14. Control biológico del marchitamiento vascular causado por Fusarium oxysporum f. sp. phaseoli en fríjol Phaseolus vulgaris L., mediante la acción combinada de Entrophospora colombiana, Trichoderma sp. Y Pseudomonas fluorescens

    Directory of Open Access Journals (Sweden)

    Avendaño Camila

    2006-06-01

    Hidden="false" UnhideWhenUsed="false" QFormat="true" Name="Intense Emphasis" /> Entrophospora colombiana, Trichoderma sp., Pseudomonas fluorescens y una combinación de estos antagonistas fueron evaluados como biocontroladores de Fusarium oxysporumf. sp. Phaseoli en plantas de fríjol de la variedad ‘ICA Tundama’. El ensayo se estableció en una casa de malla del Programa nacional de manejo integrado de plagas (MIP de la Corporación Colombiana de Investigación Agropecuaria (Corpoica, en el Centro de Investigación Tibaitat

  15. A Direct Quantitative Agar-Plate Based Assay for Analysis of Pseudomonas protegens PF-5 Degradation of Polyurethane Films (Postprint)

    Science.gov (United States)

    2014-10-02

    activity in Pseudomonas fluorescens CHA0. Mol. Plant - Microbe . Interact . 25, 1440e1449. Yang, X., Wang, S., Zhou, L., 2012. Effect of carbon source, C... Interactions between the Pf-5 colonies and thin polyurethane (PU) coatings on ZnSe coupons were evaluated for degradation using infrared spectroscopy...Small (1 mm diameter) colonies of Pseudomonas protegens Pf-5 (formerly Pseudomonas fluorescens Pf-5) were used for this work. Interactions between

  16. Optimization of alkaline protease production from Pseudomonas ...

    African Journals Online (AJOL)

    A protease producing bacteria was isolated from meat waste contaminated soil and identified as Pseudomonas fluorescens. Optimization of the fermentation medium for maximum protease production was carried out. The culture conditions like inoculum concentration, incubation time, pH, temperature, carbon sources, ...

  17. Alginate oligosaccharides

    DEFF Research Database (Denmark)

    Falkeborg, Mia; Cheong, Ling-Zhi; Gianfico, Carlo

    2014-01-01

    the presence of the conjugated alkene acid structure formed during enzymatic depolymerization. According to the resonance hybrid theory, the parent radicals of AOs are delocalized through allylic rearrangement, and as a consequence, the reactive intermediates are stabilized. AOs were weak ferrous ion chelators....... This work demonstrated that AOs obtained from a facile enzymatic treatment of abundant alginate is an excellent natural antioxidant, which may find applications in the food industry....

  18. A complex multilevel attack on Pseudomonas aeruginosa algT/U expression and AlgT/U activity results in the loss of alginate production

    DEFF Research Database (Denmark)

    Sautter, Robert; Ramos, Damaris; Schneper, Lisa

    2012-01-01

    Infection by the opportunistic pathogen Pseudomonas aeruginosa is a leading cause of morbidity and mortality seen in cystic fibrosis (CF) patients. This is mainly due to the genotypic and phenotypic changes of the bacteria that cause conversion from a typical nonmucoid to a mucoid form in the CF...... off mechanism has been mapped to the algT/U locus, and the molecular basis for this conversion was partially attributed to mutations in the algT/U gene itself. To further characterize molecular changes resulting in the unstable phenotype, an isogenic PAO1 derivative that is constitutively Alg+ due...... carrying algT/U (Group A). The remaining sap mutants were not (Group B). The members of Group B fall into two subsets: one similar to PAO1, and another comparable to PDO300. Sequence analysis of the algT/U and mucA genes in Group A shows that mucA22 is intact, whereas algT/U contains mutations. Genetic...

  19. Coating of alginate capsules

    OpenAIRE

    Hadjialirezaei, Soosan

    2013-01-01

    Alginate is a popular candidate for encapsulation of cells due to the formation of gels with divalent ions under physiological conditions. Stable alginate gels can be formed by the selection of alginates with a high content of guluronic acid (G) and gelling in a mixture of calcium and barium. These alginate gels have been proposed as immune protective barriers for the transplantation of human pancreatic islets (insulin producing cells) for the treatment of type 1 diabetes where the alginate g...

  20. Novel Pseudomonas fluorescens Septic Sacroiliitis in a Healthy Soldier

    Science.gov (United States)

    2013-08-01

    pain and intermittent non-bloody diarrhea . Laboratory studies were unremarkable, concurrent abdominal computed tomography (CT) and lumbar MRI showed no...Microbiol 2008; 8: 189–202. 4. Dubey L, Krasinski K, Hernanz-Schulman M: Osteomyelitis secondary to trauma or infected contiguous soft tissue. Pediatr ...51. 17. Wu M-S, Chang S-S, Lee S-H, Lee C-C: Pyogenic sacroiliitis—a com- parison between pediatric and adult patients. Rheumatology 2007; 46: 1684–7

  1. Bacterial alginate production: an overview of its biosynthesis and potential industrial production.

    Science.gov (United States)

    Urtuvia, Viviana; Maturana, Nataly; Acevedo, Fernando; Peña, Carlos; Díaz-Barrera, Alvaro

    2017-10-07

    Alginate is a linear polysaccharide that can be used for different applications in the food and pharmaceutical industries. These polysaccharides have a chemical structure composed of subunits of (1-4)-β-D-mannuronic acid (M) and its C-5 epimer α-L-guluronic acid (G). The monomer composition and molecular weight of alginates are known to have effects on their properties. Currently, these polysaccharides are commercially extracted from seaweed but can also be produced by Azotobacter vinelandii and Pseudomonas spp. as an extracellular polymer. One strategy to produce alginates with different molecular weights and with reproducible physicochemical characteristics is through the manipulation of the culture conditions during fermentation. This mini-review provides a comparative analysis of the metabolic pathways and molecular mechanisms involved in alginate polymerization from A. vinelandii and Pseudomonas spp. Different fermentation strategies used to produce alginates at a bioreactor laboratory scale are described.

  2. Disruption of transporters affiliated with enantio-pyochelin biosynthesis gene cluster of Pseudomonas protegens Pf-5 has pleiotropic effects

    Science.gov (United States)

    Pseudomonas protegens Pf-5 (formerly Pseudomonas fluorescens) is a biocontrol bacterium that produces the siderophore enantio-pyochelin under conditions of iron starvation in a process that is often accompanied by the secretion of its biosynthesis intermediates, salicylic acid and dihydroaeruginoic ...

  3. Characterization of AlgMsp, an alginate lyase from Microbulbifer sp. 6532A.

    Directory of Open Access Journals (Sweden)

    Steven M Swift

    Full Text Available Alginate is a polysaccharide produced by certain seaweeds and bacteria that consists of mannuronic acid and guluronic acid residues. Seaweed alginate is used in food and industrial chemical processes, while the biosynthesis of bacterial alginate is associated with pathogenic Pseudomonas aeruginosa. Alginate lyases cleave this polysaccharide into short oligo-uronates and thus have the potential to be utilized for both industrial and medicinal applications. An alginate lyase gene, algMsp, from Microbulbifer sp. 6532A, was synthesized as an E.coli codon-optimized clone. The resulting 37 kDa recombinant protein, AlgMsp, was expressed, purified and characterized. The alginate lyase displayed highest activity at pH 8 and 0.2 M NaCl. Activity of the alginate lyase was greatest at 50°C; however the enzyme was not stable over time when incubated at 50°C. The alginate lyase was still highly active at 25°C and displayed little or no loss of activity after 24 hours at 25°C. The activity of AlgMsp was not dependent on the presence of divalent cations. Comparing activity of the lyase against polymannuronic acid and polyguluronic acid substrates showed a higher turnover rate for polymannuronic acid. However, AlgMSP exhibited greater catalytic efficiency with the polyguluronic acid substrate. Prolonged AlgMsp-mediated degradation of alginate produced dimer, trimer, tetramer, and pentamer oligo-uronates.

  4. Phenazine-producing fluorescent Pseudomonas spp.: Diversity and biogeography in central Washington state

    Science.gov (United States)

    Strains of the rhizosphere bacterium Pseudomonas fluorescens produce redox-active phenazine antibiotics that suppress a wide variety of soilborne plant pathogens. Our laboratory recently detected these bacteria a population levels up to 106 colony-forming units (cfu) per gram of root (fresh weight)...

  5. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface

    Directory of Open Access Journals (Sweden)

    Danila Soares Caixeta

    2012-03-01

    Full Text Available The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1 when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.

  6. 40 CFR 180.1107 - Delta endotoxin of Bacillus thuringiensis variety kurstaki encapsulated into killed Pseudomonas...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Delta endotoxin of Bacillus... From Tolerances § 180.1107 Delta endotoxin of Bacillus thuringiensis variety kurstaki encapsulated into killed Pseudomonas fluorescens; exemption from the requirement of a tolerance. The delta endotoxin of...

  7. Preparation methods of alginate nanoparticles

    NARCIS (Netherlands)

    Paques, J.P.; Linden, van der E.; Rijn, van C.J.M.; Sagis, L.M.C.

    2014-01-01

    This article reviews available methods for the formation of alginate nano-aggregates, nanocapsules and nanospheres. Primarily, alginate nanoparticles are being prepared by two methods. In the “complexation method”, complex formation on the interface of an oil droplet is used to form alginate

  8. Screening of alginate lyase-excreting microorganisms from the surface of brown algae.

    Science.gov (United States)

    Wang, Mingpeng; Chen, Lei; Zhang, Zhaojie; Wang, Xuejiang; Qin, Song; Yan, Peisheng

    2017-12-01

    Alginate lyase is a biocatalyst that degrades alginate to produce oligosaccharides, which have many bioactive functions and could be used as renewable biofuels. Here we report a simple and sensitive plate assay for screening alginate lyase-excreting microorganisms from brown algae. Brown algae Laminaria japonica, Sargassum horneri and Sargassum siliquatrum were cultured in sterile water. Bacteria growing on the surface of seaweeds were identified and their capacity of excreting alginate lyase was analyzed. A total of 196 strains were recovered from the three different algae samples and 12 different bacterial strains were identified capable of excreting alginate lyases. Sequence analysis of the 16S rRNA gene revealed that these alginate lyase-excreting strains belong to eight genera: Paenibacillus (4/12), Bacillus (2/12), Leclercia (1/12), Isoptericola (1/12), Planomicrobium (1/12), Pseudomonas (1/12), Lysinibacillus (1/12) and Sphingomonas (1/12). Further analysis showed that the LJ-3 strain (Bacillus halosaccharovorans) had the highest enzyme activity. To our best knowledge, this is the first report regarding alginate lyase-excreting strains in Paenibacillus, Planomicrobium and Leclercia. We believe that our method used in this study is relatively easy and reliable for large-scale screening of alginate lyase-excreting microorganisms.

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

    Science.gov (United States)

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

  10. 21 CFR 184.1187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH control...

  11. 21 CFR 184.1610 - Potassium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium alginate. 184.1610 Section 184.1610 Food... Specific Substances Affirmed as GRAS § 184.1610 Potassium alginate. (a) Potassium alginate (CAS Reg. No... algae. Potassium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  12. Catalytic Mechanism and Mode of Action of the Periplasmic Alginate Epimerase AlgG

    NARCIS (Netherlands)

    Wolfram, Francis; Kitova, Elena N.; Robinson, Howard; Walvoort, Marthe T. C.; Codee, Jeroen D. C.; Klassen, John S.; Howell, P. Lynne

    2014-01-01

    Background: The alginate epimerase AlgG converts mannuronate to its C5 epimer guluronate at the polymer level. Results: The structure of Pseudomonas syringae AlgG has been determined, and the protein has been functionally characterized. Conclusion: His(319) acts as the catalytic base, whereas

  13. Protozoan growth rates on secondary-metabolite-producing Pseudomonas spp. correlate with high-level protozoan taxonomy

    DEFF Research Database (Denmark)

    Pedersen, Annette L.; Winding, Anne; Altenburger, Andreas

    2011-01-01

    Different features can protect bacteria against protozoan grazing, for example large size, rapid movement, and production of secondary metabolites. Most papers dealing with these matters focus on bacteria. Here, we describe protozoan features that affect their ability to grow on secondary......-metabolite-producing bacteria, and examine whether different bacterial secondary metabolites affect protozoa similarly. We investigated the growth of nine different soil protozoa on six different Pseudomonas strains, including the four secondary-metabolite-producing Pseudomonas fluorescens DR54 and CHA0, Pseudomonas...... chlororaphis MA342 and Pseudomonas sp. DSS73, as well as the two nonproducers P. fluorescens DSM50090T and P. chlororaphis ATCC43928. Secondary metabolite producers affected protozoan growth differently. In particular, bacteria with extracellular secondary metabolites seemed more inhibiting than bacteria...

  14. Diversity of Pseudomonas Genomes, Including Populus-Associated Isolates, as Revealed by Comparative Genome Analysis

    Science.gov (United States)

    Jun, Se-Ran; Wassenaar, Trudy M.; Nookaew, Intawat; Hauser, Loren; Wanchai, Visanu; Land, Miriam; Timm, Collin M.; Lu, Tse-Yuan S.; Schadt, Christopher W.; Doktycz, Mitchel J.; Pelletier, Dale A.

    2015-01-01

    The Pseudomonas genus contains a metabolically versatile group of organisms that are known to occupy numerous ecological niches, including the rhizosphere and endosphere of many plants. Their diversity influences the phylogenetic diversity and heterogeneity of these communities. On the basis of average amino acid identity, comparative genome analysis of >1,000 Pseudomonas genomes, including 21 Pseudomonas strains isolated from the roots of native Populus deltoides (eastern cottonwood) trees resulted in consistent and robust genomic clusters with phylogenetic homogeneity. All Pseudomonas aeruginosa genomes clustered together, and these were clearly distinct from other Pseudomonas species groups on the basis of pangenome and core genome analyses. In contrast, the genomes of Pseudomonas fluorescens were organized into 20 distinct genomic clusters, representing enormous diversity and heterogeneity. Most of our 21 Populus-associated isolates formed three distinct subgroups within the major P. fluorescens group, supported by pathway profile analysis, while two isolates were more closely related to Pseudomonas chlororaphis and Pseudomonas putida. Genes specific to Populus-associated subgroups were identified. Genes specific to subgroup 1 include several sensory systems that act in two-component signal transduction, a TonB-dependent receptor, and a phosphorelay sensor. Genes specific to subgroup 2 contain hypothetical genes, and genes specific to subgroup 3 were annotated with hydrolase activity. This study justifies the need to sequence multiple isolates, especially from P. fluorescens, which displays the most genetic variation, in order to study functional capabilities from a pangenomic perspective. This information will prove useful when choosing Pseudomonas strains for use to promote growth and increase disease resistance in plants. PMID:26519390

  15. 40 CFR 180.1108 - Delta endotoxin of Bacillus thuringiensis variety San Diego encapsulated into killed Pseudomonas...

    Science.gov (United States)

    2010-07-01

    ... From Tolerances § 180.1108 Delta endotoxin of Bacillus thuringiensis variety San Diego encapsulated... of Bacillus thuringiensis variety San Diego encapsulated into killed Pseudomonas fluorescens is... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Delta endotoxin of Bacillus...

  16. Effect of Genetically Modified Pseudomonas putida WCS358r on the Fungal Rhizosphere Microflora of Field-Grown Wheat

    NARCIS (Netherlands)

    Glandorf, D.C.M.; Verheggen, Patrick; Jansen, Timo; Jorritsma, J.-W.; Smit, Eric; Leeflang, Paula; Wernars, Karel; Thomashow, L.S.; Laureijs, Eric; Thomas-Oates, J.E.; Bakker, P.A.H.M.; Loon, L.C. van

    2001-01-01

    We released genetically modified Pseudomonas putida WCS358r into the rhizospheres of wheat plants. The two genetically modified derivatives, genetically modified microorganism (GMM) 2 and GMM 8, carried the phz biosynthetic gene locus of strain P. fluorescens 2-79 and constitutively produced the

  17. Quantification of alginate by aggregation induced by calcium ions and fluorescent polycations.

    Science.gov (United States)

    Zheng, Hewen; Korendovych, Ivan V; Luk, Yan-Yeung

    2016-01-01

    For quantification of polysaccharides, including heparins and alginates, the commonly used carbazole assay involves hydrolysis of the polysaccharide to form a mixture of UV-active dye conjugate products. Here, we describe two efficient detection and quantification methods that make use of the negative charges of the alginate polymer and do not involve degradation of the targeted polysaccharide. The first method utilizes calcium ions to induce formation of hydrogel-like aggregates with alginate polymer; the aggregates can be quantified readily by staining with a crystal violet dye. This method does not require purification of alginate from the culture medium and can measure the large amount of alginate that is produced by a mucoid Pseudomonas aeruginosa culture. The second method employs polycations tethering a fluorescent dye to form suspension aggregates with the alginate polyanion. Encasing the fluorescent dye in the aggregates provides an increased scattering intensity with a sensitivity comparable to that of the conventional carbazole assay. Both approaches provide efficient methods for monitoring alginate production by mucoid P. aeruginosa. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Alginate Production from Alternative Carbon Sources and Use of Polymer Based Adsorbent in Heavy Metal Removal

    Directory of Open Access Journals (Sweden)

    Çiğdem Kıvılcımdan Moral

    2016-01-01

    Full Text Available Alginate is a biopolymer composed of mannuronic and guluronic acids. It is harvested from marine brown algae; however, alginate can also be synthesized by some bacterial species, namely, Azotobacter and Pseudomonas. Use of pure carbohydrate sources for bacterial alginate production increases its cost and limits the chance of the polymer in the industrial market. In order to reduce the cost of bacterial alginate production, molasses, maltose, and starch were utilized as alternative low cost carbon sources in this study. Results were promising in the case of molasses with the maximum 4.67 g/L of alginate production. Alginates were rich in mannuronic acid during early fermentation independent of the carbon sources while the highest guluronic acid content was obtained as 68% in the case of maltose. The polymer was then combined with clinoptilolite, which is a natural zeolite, to remove copper from a synthetic wastewater. Alginate-clinoptilolite beads were efficiently adsorbed copper up to 131.6 mg Cu2+/g adsorbent at pH 4.5 according to the Langmuir isotherm model.

  19. Structural Basis for Alginate Secretion Across the Bacterial Outer Membrane

    Energy Technology Data Exchange (ETDEWEB)

    J Whitney; I Hay; C Li; P Eckford; H Robinson; M Amaya; L Wood; D Ohman; C Bear; et al.

    2011-12-31

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  20. Structural basis for alginate secretion across the bacterial outer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, J.C.; Robinson, H.; Hay, I. D.; Li, C.; Eckford, P. D. W.; Amaya, M. F.; Wood, L. F.; Ohman, D. E.; Bear, C. E.; Rehm, B. H.; Howell, P. L.

    2011-08-09

    Pseudomonas aeruginosa is the predominant pathogen associated with chronic lung infection among cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Secretion of newly synthesized alginate across the outer membrane is believed to occur through the outer membrane protein AlgE. Here we report the 2.3 {angstrom} crystal structure of AlgE, which reveals a monomeric 18-stranded {beta}-barrel characterized by a highly electropositive pore constriction formed by an arginine-rich conduit that likely acts as a selectivity filter for the negatively charged alginate polymer. Interestingly, the pore constriction is occluded on either side by extracellular loop L2 and an unusually long periplasmic loop, T8. In halide efflux assays, deletion of loop T8 ({Delta}T8-AlgE) resulted in a threefold increase in anion flux compared to the wild-type or {Delta}L2-AlgE supporting the idea that AlgE forms a transport pathway through the membrane and suggesting that transport is regulated by T8. This model is further supported by in vivo experiments showing that complementation of an algE deletion mutant with {Delta}T8-AlgE impairs alginate production. Taken together, these studies support a mechanism for exopolysaccharide export across the outer membrane that is distinct from the Wza-mediated translocation observed in canonical capsular polysaccharide export systems.

  1. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface Sanificantes químicos no controle de biofilmes formados por duas espécies de Pseudomonas em superfície de aço inoxidável

    Directory of Open Access Journals (Sweden)

    Danila Soares Caixeta

    2012-03-01

    Full Text Available The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1 when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.A capacidade de adesão e formação de biofilme por Pseudomonas aeruginosa e Pseudomonas fluorescens em aço inoxidável AISI 304, na presença de leite desnatado resconstituído sobre diferentes temperaturas foi conduzido e o potencial de três sanificantes químicos na remoção de biofilmes monoespécies foi comparado. Pseudomonas aeruginosa cultivada em leite desnatado a 28 °C apresentou melhor crescimento (10,4 log UFC.mL-1 quando comparado com 3,7 and 4,2 log UFC.mL-1 para P. aeruginosa e P. fluorescens cultivadas a 7 °C, respectivamente. Pseudomonas aeruginosa formou biofilme quando cultivada a 28 °C. Contudo foi observado somente adesão de P. aeruginosa e P. fluorescens quando incubada a 7 °C. O dicloroisocianurato de sódio foi o sanificante mais eficiente na redução de células aderidas e em biofilme de P. aeruginosa a 7 e 28 °C, respectivamente. O peróxido de hidrogênio foi o mais eficiente na redução de células aderidas de P. fluorescens a 7 °C.

  2. Generation and initial characterization of Pseudomonas stutzeri KC mutants with impaired ability to degrade carbon tetrachloride.

    Science.gov (United States)

    Sepúlveda-Torres, L C; Rajendran, N; Dybas, M J; Criddle, C S

    1999-01-01

    Under iron-limiting conditions, Pseudomonas stutzeri KC secretes a small but as yet unidentified factor that transforms carbon tetrachloride (CT) to CO2 and nonvolatile products when activated by reduction at cell membranes. Pseudomonas fluorescens and other cell types activate the factor. Triparental mating was used to generate kanamycin-resistant lux::Tn5 recombinants of strain KC. Recombinants were streaked onto the surface of agar medium plugs in microtiter plates and were then screened for carbon tetrachloride degradation by exposing the plates to gaseous 14C-carbon tetrachloride. CT+ recombinants generated nonvolatile 14C-labeled products, but four CT- recombinants did not generate significant nonvolatile 14C-labeled products and had lost the ability to degrade carbon tetrachloride. When colonies of P. fluorescens were grown next to colonies of CT+ recombinants and were exposed to gaseous 14C-carbon tetrachloride, 14C-labeled products accumulated around the P. fluorescens colonies, indicating that the factor secreted by CT+ colonies had diffused through the agar and become activated. When P. fluorescens was grown next to CT- colonies, little carbon tetrachloride transformation was observed, indicating a lack of active factor. Expression of lux reporter genes in three of the CT- mutants was regulated by added iron and was induced under the same iron-limiting conditions that induce carbon tetrachloride transformation in the wild-type.

  3. Chromosomal insertion of the entire Escherichia coli lactose operon, into two strains of Pseudomonas, using a modified mini-Tn5 delivery system

    DEFF Research Database (Denmark)

    Hansen, L. H.; Sørensen, S. J.; Jensen, Lars Bogø

    1997-01-01

    A 12-kb PstI fragment including the entire E. coli lactose operon (lacIPOZYA) was inserted in one copy into the chromosome of Pseudomonas putida, Pseudomonas fluorescens and an E. coli strain with lac(-) phenotype. This was made possible by improvements of an already existing mini-Tn5 transposon...... flanked by NotI sites needed in the mini-Tn5 delivery system; (b) the generation of E. coli nonlysogenic strains expressing the pi protein thus being capable of maintaining and delivering R6K-based mini-Tn5 vectors to other E. coli strains; (c) the successful insertion of the E. coli lactose operon...... into the P. fluorescens chromosome giving P. fluorescens the ability to grow on lactose; (d) evidence from Southern blotting that contradicts the assumption that the mini-Tn5 delivery system always creates one-copy inserts. These improvements allow insertion of large DNA fragments encoding highly expressed...

  4. Microbial alginate production, modification and its applications

    Science.gov (United States)

    Hay, Iain D; Rehman, Zahid Ur; Moradali, M Fata; Wang, Yajie; Rehm, Bernd H A

    2013-01-01

    Alginate is an important polysaccharide used widely in the food, textile, printing and pharmaceutical industries for its viscosifying, and gelling properties. All commercially produced alginates are isolated from farmed brown seaweeds. These algal alginates suffer from heterogeneity in composition and material properties. Here, we will discuss alginates produced by bacteria; the molecular mechanisms involved in their biosynthesis; and the potential to utilize these bacterially produced or modified alginates for high-value applications where defined material properties are required. PMID:24034361

  5. Variation of the Pseudomonas community structure on oak leaf lettuce during storage detected by culture-dependent and -independent methods.

    Science.gov (United States)

    Nübling, Simone; Schmidt, Herbert; Weiss, Agnes

    2016-01-04

    The genus Pseudomonas plays an important role in the lettuce leaf microbiota and certain species can induce spoilage. The aim of this study was to investigate the occurrence and diversity of Pseudomonas spp. on oak leaf lettuce and to follow their community shift during a six day cold storage with culture-dependent and culture-independent methods. In total, 21 analysed partial Pseudomonas 16S rRNA gene sequences matched closely (> 98.3%) to the different reference strain sequences, which were distributed among 13 different phylogenetic groups or subgroups within the genus Pseudomonas. It could be shown that all detected Pseudomonas species belonged to the P. fluorescens lineage. In the culture-dependent analysis, 73% of the isolates at day 0 and 79% of the isolates at day 6 belonged to the P. fluorescens subgroup. The second most frequent group, with 12% of the isolates, was the P. koreensis subgroup. This subgroup was only detected at day 0. In the culture-independent analysis the P. fluorescens subgroup and P. extremaustralis could not be differentiated by RFLP. Both groups were most abundant and amounted to approximately 46% at day 0 and 79% at day 6. The phytopathogenic species P. salmonii, P. viridiflava and P. marginalis increased during storage. Both approaches identified the P. fluorescens group as the main phylogenetic group. The results of the present study suggest that pseudomonads found by plating methods indeed represent the most abundant part of the Pseudomonas community on oak leaf lettuce. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Two strains of Pseudomonas fluorscens bacteria differentially affect survivorship of waxworm (Galleria mellonella) larvae exposed to an arthropod fungal pathogen, Beauveria bassiana

    Science.gov (United States)

    Two strains of Pseudomonas fluorescens were found contaminating a biopesticide used in a previous study against Varroa destructor infestations in honey bee hives. In the aforementioned study the biopesticide, a formulation of the arthropod pathogen Beauveria bassiana, failed to have any impact on t...

  7. Bacterial Feeders, the Nematode Caenorhabditis elegans and the Flagellate Cercomonas longicauda, have different Effects on Outcome of Competition among the Pseudomonas Biocontrol Strains CHA0 and DSS73

    DEFF Research Database (Denmark)

    Pedersen, Annette; Nybroe, Ole; Winding, Anne

    2009-01-01

    selective feeding flagellate Cercomonas longicauda versus the non-selective feeding nematode Caenorhabditis elegans) influence the abundance of two bacteria that compete for resources in simple model communities. Microcosms consisted of either one gfp-tagged bacterial strain (Pseudomonas fluorescens DSM...

  8. Imunomodulator Activity of Alginate Oligosaccharides from Alginate Sargassum crassifolium

    Directory of Open Access Journals (Sweden)

    Subaryono Subaryono

    2017-04-01

    Full Text Available Alginate oligosaccharides (AOS are oligosaccharides produced from depolimerization of the alginate polymer, and is reported to have various biological activities. The study aims is to determine the effect of AOSproduction conditions and their effects on products and its activities as an immunomodulatory compound. Production of alginate oligosaccharides (AOS enzymatically carried out with the help of alginate lyase enzyme produced from the bacterium Bacillus megaterium S245. Variation of incubation time is 2, 4, 6 and 8 hours at concentrations of alginate lyase enzyme addition of 25, 50, 75 and 100U. Treatment of enzyme concentration and the duration of incubation in the production of AOS produces a degree of polymerization (DP 2-7. In vitro activity test showed AOS is have ability to induce cell proliferation of human lymphocytes.This type of cell lymphocytes proliferation induced by AOS is a CD 8 cells or cytotoxic T cell and non cell CD4 / CD8. AOS production conditions with the addition of alginate lyase enzyme 50 U and incubation period 2 hours has produce AOS with the highest index of lymphocyte proliferation  117.6+3.6% or an increase of 43.24% compared to the native alginat polymer.

  9. Kinetics of Enantiomerically Enriched Synthesis of Solketal Esters Using Native and SBA-15 supported P. Fluorescens Lipase

    Directory of Open Access Journals (Sweden)

    Zniszczoł Aurelia

    2017-06-01

    Full Text Available The studies showed that alkaline lipase from Pseudomonas fluorescens enables an irreversible transesterification of vinyl esters to give enantiomeric excess (eeR of about 80% using vinyl butyrate as acyl donor and diisopropyl ether as a solvent, at partially optimized conditions. For the native lipase the process was adequately described by a five-parameter Ping-Pong Bi Bi model for both enantiomers plus expression accounting for the formation of enzyme-acyl donor complex, but for the same lipase supported on mesoporous materials of SBA-15-Oc type, R-product inhibition also had to be taken into account. The use of hydrophobic support increased by more than two-fold the rate of the S-solketal conversion but even more that of R-solketal. Thus the immobilization of lipase had very positive effect on the process kinetics but decreased its enantioselectivity.

  10. Alginate immobilized enrichment culture for atrazine degradation in soil and water system.

    Science.gov (United States)

    Kumar, Anup; Nain, Lata; Singh, Neera

    2017-04-03

    An atrazine degrading enrichment culture, a consortium of bacteria of genus Bacillus along with Pseudomonas and Burkholderia, was immobilized in sodium alginate and was used to study atrazine degradation in mineral salts medium (MSM), soil and wastewater effluent. Sodium alginate immobilized consortium, when stored at room temperature (24 ± 5°C), was effective in degrading atrazine in MSM up to 90 days of storage. The survival of bacteria in alginate beads, based on colony formation unit (CFU) counts, suggested survival up to 90 days and population counts decreased to 1/5 th on 120 days. Comparison of atrazine degrading ability of the freely suspended enrichment culture and immobilized culture suggested that the immobilized culture took longer time for complete degradation of atrazine as a lag phase of 2 days was observed in the MSM inoculated with alginate immobilized culture. The free cells resulted in complete degradation of atrazine within 6 days, while immobilized cells took 10 days for 100% atrazine degradation. Further, immobilized cultures were able to degrade atrazine in soil and wastewater effluent. Alginate beads were stable and effective in degrading atrazine till 3rd transfer and disintegrated thereafter. The study suggested that immobilized enrichment culture, due to its better storage and application, can be used to degrade atrazine in soil water system.

  11. 21 CFR 582.7724 - Sodium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium alginate. 582.7724 Section 582.7724 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... alginate. (a) Product. Sodium alginate. (b) Conditions of use. This substance is generally recognized as...

  12. 21 CFR 582.7133 - Ammonium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammonium alginate. 582.7133 Section 582.7133 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Ammonium alginate. (a) Product. Ammonium alginate. (b) Conditions of use. This substance is generally...

  13. 21 CFR 582.7187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is generally...

  14. 21 CFR 582.7610 - Potassium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium alginate. 582.7610 Section 582.7610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Potassium alginate. (a) Product. Potassium alginate. (b) Conditions of use. This substance is generally...

  15. 21 CFR 184.1011 - Alginic acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Alginic acid. 184.1011 Section 184.1011 Food and... Substances Affirmed as GRAS § 184.1011 Alginic acid. (a) Alginic acid is a colloidal, hydrophilic.../code_of_federal_regulations/ibr_locations.html. (c) In accordance with § 184.1(b)(2), the ingredient is...

  16. 21 CFR 184.1133 - Ammonium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ammonium alginate. 184.1133 Section 184.1133 Food... Specific Substances Affirmed as GRAS § 184.1133 Ammonium alginate. (a) Ammonium alginate (CAS Reg. No. 9005... accordance with § 184.1(b)(2), the ingredient is used in food only within the following specific limitations...

  17. Efficient functionalization of alginate biomaterials.

    Science.gov (United States)

    Dalheim, Marianne Ø; Vanacker, Julie; Najmi, Maryam A; Aachmann, Finn L; Strand, Berit L; Christensen, Bjørn E

    2016-02-01

    Peptide coupled alginates obtained by chemical functionalization of alginates are commonly used as scaffold materials for cells in regenerative medicine and tissue engineering. We here present an alternative to the commonly used carbodiimide chemistry, using partial periodate oxidation followed by reductive amination. High and precise degrees of substitution were obtained with high reproducibility, and without formation of by-products. A protocol was established using l-Tyrosine methyl ester as a model compound and the non-toxic pic-BH3 as the reducing agent. DOSY was used to indirectly verify covalent binding and the structure of the product was further elucidated using NMR spectroscopy. The coupling efficiency was to some extent dependent on alginate composition, being most efficient on mannuronan. Three different bioactive peptide sequences (GRGDYP, GRGDSP and KHIFSDDSSE) were coupled to 8% periodate oxidized alginate resulting in degrees of substitution between 3.9 and 6.9%. Cell adhesion studies of mouse myoblasts (C2C12) and human dental stem cells (RP89) to gels containing various amounts of GRGDSP coupled alginate demonstrated the bioactivity of the material where RP89 cells needed higher peptide concentrations to adhere. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Role of Exopolysaccharides in Pseudomonas aeruginosa Biofilm Formation and Architecture ▿ †

    Science.gov (United States)

    Ghafoor, Aamir; Hay, Iain D.; Rehm, Bernd H. A.

    2011-01-01

    Pseudomonas aeruginosa is an opportunistic human pathogen and has been established as a model organism to study bacterial biofilm formation. At least three exopolysaccharides (alginate, Psl, and Pel) contribute to the formation of biofilms in this organism. Here mutants deficient in the production of one or more of these polysaccharides were generated to investigate how these polymers interactively contribute to biofilm formation. Confocal laser scanning microscopy of biofilms formed in flow chambers showed that mutants deficient in alginate biosynthesis developed biofilms with a decreased proportion of viable cells than alginate-producing strains, indicating a role of alginate in viability of cells in biofilms. Alginate-deficient mutants showed enhanced extracellular DNA (eDNA)-containing surface structures impacting the biofilm architecture. PAO1 ΔpslA Δalg8 overproduced Pel, and eDNA showing meshwork-like structures presumably based on an interaction between both polymers were observed. The formation of characteristic mushroom-like structures required both Psl and alginate, whereas Pel appeared to play a role in biofilm cell density and/or the compactness of the biofilm. Mutants producing only alginate, i.e., mutants deficient in both Psl and Pel production, lost their ability to form biofilms. A lack of Psl enhanced the production of Pel, and the absence of Pel enhanced the production of alginate. The function of Psl in attachment was independent of alginate and Pel. A 30% decrease in Psl promoter activity in the alginate-overproducing MucA-negative mutant PDO300 suggested inverse regulation of both biosynthesis operons. Overall, this study demonstrated that the various exopolysaccharides and eDNA interactively contribute to the biofilm architecture of P. aeruginosa. PMID:21666010

  19. Effects of atmospheric conditions on ice nucleation activity of Pseudomonas

    Directory of Open Access Journals (Sweden)

    C. Glaux

    2012-11-01

    Full Text Available Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i acidic pH (ii NO2 and O3 exposure and (iii UV-A exposure on the ice nucleation activity (INA of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

  20. 3D Cell Culture in Alginate Hydrogels.

    Science.gov (United States)

    Andersen, Therese; Auk-Emblem, Pia; Dornish, Michael

    2015-03-24

    This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell-matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue.

  1. Synthesis of multiple Pseudomonas aeruginosa biofilm matrix exopolysaccharides is post-transcriptionally regulated.

    Science.gov (United States)

    Ma, Luyan; Wang, Juan; Wang, Shiwei; Anderson, Erin M; Lam, Joseph S; Parsek, Matthew R; Wozniak, Daniel J

    2012-08-01

    Exopolysaccharide is a critical biofilm matrix component, yet little is known about how the synthesis of multiple exopolysaccharides is regulated. Pseudomonas aeruginosa can produce several biofilm matrix exopolysaccharides that include alginate, Psl and Pel. Here we demonstrated that AlgC, a key enzyme that provides sugar precursors for the synthesis of alginate and lipopolysaccharides (LPS) is also required for both Psl and Pel production. We showed that forced-synthesis of Psl in alginate-producing mucoid bacteria reduced alginate production but this was not due to transcription of the alginate biosynthesis-operon. Likewise, when either alginate or Psl were overproduced, levels of B-band LPS decreased. Induction of Pel resulted in a reduction of Psl levels. Because the effects of reduced exopolysaccharide synthesis when another is overproduced didn't appear to be regulated at the transcriptional level, this suggests that the biosynthesis pathways of Psl, Pel, alginate, and LPS compete for common sugar precursors. As AlgC is the only enzyme that provides precursors for each of these exopolysaccharides, we propose that AlgC is a key checkpoint enzyme that coordinates the total amount of exopolysaccharide biosynthesis by controlling sugar precursor pool. Our data also provide a plausible strategy that P.aeruginosa utilizes to modulate its biofilm matrix exopolysaccharides. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

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

    Czech Academy of Sciences Publication Activity Database

    Grosskinsky, D. K.; Tafner, R.; Moreno, M. V.; Stenglein, S. A.; Garcia de Salamone, I. E.; Nelson, L. M.; Novák, Ondřej; Strnad, Miroslav; van der Graaff, E.; Roitsch, Thomas

    2016-01-01

    Roč. 6, MAR 17 (2016), s. 23310 ISSN 2045-2322 R&D Projects: GA MŠk(CZ) LO1204; GA ČR GA15-22322S; GA MŠk(CZ) LO1415 Institutional support: RVO:61389030 ; RVO:67179843 Keywords : GROWTH-PROMOTING RHIZOBACTERIA * PLANT -GROWTH * SALICYLIC-ACID Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.259, year: 2016

  3. Anti-pseudomona and Anti-bacilli Activity of Some Medicinal Plants of Iran

    Directory of Open Access Journals (Sweden)

    Gholam Hosein Shahidi Bonjar

    2003-10-01

    Full Text Available The use of plants in treatment of burns, dermatophytes, and infectious diseases is common in traditional medicine of Iran. Based on ethno pharmacological and taxonomic information, antibacterial activities of methanol extracts of some medicinal plants of Iran were determined by In Vitro bioassays using agar diffusion-method against standard strains of Pseudomonas aeruginosa, P. fluorescens, Bacillus subtilis, B. cereus and B. pumilis at 20 mg/ml. From 180 plant species of 72 families, 78 species (43.3% in 42 families (58.3% showed antibacterial activities against B. cereus (88.4%, B. subtilis (39.7%, B. pumilis (37.1%, P. fluorescens (37.1% and P. aeruginos (10.2%. The most active plant families were Apiaceae, Compositae and Labiatae with 9, 8 and 7 active plant species respectively. Minimum inhibitory concentrations (MIC of the active plants were determined using two fold serial dilutions. Most active plant against Bacilli was Myrtus communis L. with MIC of 1.87 mg/ml. For Pseudomonas species, Dianthus caryophyllus L. and Terminalia chebula (Gaertner Retz. were more active with the MIC of 0.46 mg/ml for P. fluorescens and of 1.87 mg/ml for P. aeruginosa respectively.

  4. Perfluorinated alginate for cellular encapsulation.

    Science.gov (United States)

    Gattás-Asfura, Kerim M; Fraker, Christopher A; Stabler, Cherie L

    2012-08-01

    Molecules of pentadecafluorooctanoyl chloride (PFC) were grafted onto alginate (Alg) using a linear poly(ethylene glycol) linker and amide bonds. The resulting Alg-PFC material was characterized by proton nuclear magnetic resonance and infrared spectroscopies. The degree of PFC functionalization significantly influenced the physical and chemical properties of Alg-PFC, particularly when the resulting polymer was ionically crosslinked into hydrogels. Alg-PFC hydrogel beads fabricated via Ba(2+) crosslinking were found to match the permeability properties of control alginate beads, except upon swelling over time in culture media. When used to encapsulate MIN6 cells, a beta cell line, Alg-PFC beads demonstrated enhanced cell proliferation over alginate control beads. These results indicate that Alg-PFC hydrogels retain some of the PFC's biological-relevant benefits, such as enhancement of mass transport and bioinertness, to enhance cellular viability within alginate three-dimensional hydrogel environments. We envision these functionalized hydrogels to be particularly useful in the encapsulation of cells with a high metabolic demand, such as pancreatic islets. Copyright © 2012 Wiley Periodicals, Inc.

  5. Impact of Medium on the Development and Physiology of Pseudomonas fluorescens Biofilms on Polyurethane Paint

    Science.gov (United States)

    2012-02-01

    contribute to the degradation of those coatings. Specifically, we characterized how medium conditions and substrate composition contribute to growth of...interfaces (Brown et al. 2010; Branda et al. 2005). Pseudomonad bacteria have been shown to be common constituents of aviation fuel microbiota in...These results demonstrate that medium composition impacts both the biofilm and cell populations, but not in the same way. In addition, carbon is

  6. 76 FR 52871 - Pseudomonas fluorescens Strain CL145A; Exemption From the Requirement of a Tolerance

    Science.gov (United States)

    2011-08-24

    ... with plants, including those food plants consumed raw. The Manual of Clinical Microbiology (8th edition... a joint U.N. Food and Agriculture Organization/World Health Organization food standards program, and...

  7. Heterologous Expression of a Chitinase Gene From Aeromonas Caviaein Pseudomonas Fluorescens

    OpenAIRE

    Suwanto, Antonius; Malik, Amarila; TJAHJONO, BUDI; Harling, Rob

    2003-01-01

    A transcriptional fusion for an Aeromonas caviae chitinase gene was constructed under the control of a constitutive promoter of the kanaraycin resistance gene (PKmR). The construct was inserted into a medium copy number broad host range plasmid vector to yield recombinant plasmid pAM340, which harbored transcriptional fusion PKmR- chi. Another transcriptional fusion, Ptac-chi, in a recombinant plasmid pAM630, was conducted as comparison. Triparental mating of E. coli carrying the recombinant...

  8. HETEROLOGOUS EXPRESSION OF A CHITINASE GENE FROM AEROMONAS CAVIAEIN PSEUDOMONAS FLUORESCENS

    OpenAIRE

    ANTONIUS SUWANTO; AMARILA MAHK; BUDI TJAHJONO

    2003-01-01

    A transcriptional fusion for an Aeromonas caviae chitinase gene was constructed under the control of a constitutive promoter of the kanaraycin resistance gene (PKmR). The construct was inserted into a medium copy number broad host range plasmid vector to yield recombinant plasmid pAM340, which harbored transcriptional fusion PKmR- chi. Another transcriptional fusion, Ptac-chi, in a recombinant plasmid pAM630, was conducted as comparison. Triparental mating of E. coli carrying the recom...

  9. Lipopeptide biosurfactant viscosin enhances dispersal of Pseudomonas fluorescens SBW25 biofilms

    DEFF Research Database (Denmark)

    Bonnichsen, Lise; Svenningsen, Nanna Bygvraa; Rybtke, Morten Levin

    2015-01-01

    Pseudomonads produce several lipopeptide biosurfactants that have antimicrobial properties but that also facilitate surface motility and influence biofilm formation. Detailed studies addressing the significance of lipopeptides for biofilm formation and architecture are rare. Hence, the present st...

  10. The effect of phylogenetically different bacteria on the fitness of Pseudomonas fluorescens in sand microcosms

    NARCIS (Netherlands)

    Tyc, Olaf; Wolf, Alexandra; Garbeva, Paolina

    2015-01-01

    n most environments many microorganisms live in close vicinity and can interact in various ways. Recent studies suggest that bacteria are able to sense and respond to the presence of neighbouring bacteria in the environment and alter their response accordingly. This ability might be an important

  11. Pseudomonas spp. ISOLATED FROM THE ORAL CAVITY OF HEALTHCARE WORKERS FROM AN ONCOLOGY HOSPITAL IN MIDWESTERN BRAZIL

    Science.gov (United States)

    LIMA, Ana Beatriz Mori; LEÃO-VASCONCELOS, Lara Stefânia Netto de Oliveira; COSTA, Dayane de Melo; VILEFORT, Larissa Oliveira Rocha; ANDRÉ, Maria Cláudia Dantas Porfírio Borges; BARBOSA, Maria Alves; PRADO-PALOS, Marinésia Aparecida

    2015-01-01

    This cross-sectional study, performed in an oncology hospital in Goiania, aimed to characterize the prevalence of oral colonization and antimicrobial susceptibility of Pseudomonas spp. isolated from the saliva of healthcare workers. Microorganisms were subjected to biochemical tests, susceptibility profile, and phenotypic detection. Of 76 participants colonized with Gram negative bacilli, 12 (15.8%) harbored Pseudomonas spp. Of all isolates, P. aeruginosa (75.0%), P. stutzeri (16.7%), and P. fluorescens (8.3%), were resistant to cefoxitin, and therefore likely to be AmpC producers. The results are clinically relevant and emphasize the importance of surveillance to minimize bacterial dissemination and multiresistance. PMID:27049706

  12. Thermostable Alginate degrading enzymes and their methods of use

    NARCIS (Netherlands)

    Hreggvidsson, Gudmundur Oli; Jonsson, Oskar W.J.; Bjornsdottir, Bryndis; Fridjonsson, Hedinn O; Altenbuchner, Josef; Watzlawick, Hildegard; Dobruchowska, Justyna; Kamerling, Johannis

    2015-01-01

    The present invention relates to the identification, production and use of thermostable alginate lyase enzymes that can be used to partially degrade alginate to yield oligosaccharides or to give complete degradation of alginate to yield (unsaturated) mono-uronates.

  13. Rheological characterization of an injectable alginate gel system

    OpenAIRE

    Larsen, Benjamin E; Bjørnstad, Jorunn; Pettersen, Erik O; Tønnesen, Hanne H; Melvik, Jan E

    2015-01-01

    Background This work investigates a general method for producing alginate gel matrices using an internal mode of gelation that depends solely on soluble alginate and alginate/gelling ion particles. The method involves the formulation of two-component kits comprised of soluble alginate and insoluble alginate/gelling ion particles. Gelling kinetics, elastic and Young’s moduli were investigated for selected parameters with regard to soluble alginate guluronate content, molecul...

  14. Alginate Microbeads for Cell and Protein Delivery.

    Science.gov (United States)

    Somo, Sami I; Khanna, Omaditya; Brey, Eric M

    2017-01-01

    Alginate hydrogels have been used for a broad variety of medical applications. The ability to assemble alginate gels at neutral pH and mild temperatures makes alginate a promising choice for the encapsulation and delivery of cells and proteins. This chapter covers the basics of cell encapsulation and protein delivery using two different variations of alginate microbeads, single layered and multilayer systems. The first section describes a method for encapsulating cells within alginate microbeads coated with a permselective polymer layer. The second section describes a multilayer alginate microbead system that allows simultaneous encapsulation of cells and delivery of growth factors. The primary goal of the systems described is for encapsulation of islets as a treatment for type I diabetes. However, these microbeads can be used for a broad variety of applications in tissue engineering, cell encapsulation, and regenerative medicine.

  15. Vaccination promotes TH1-like inflammation and survival in chronic Pseudomonas aeruginosa pneumonia in rats

    DEFF Research Database (Denmark)

    Johansen, H K; Hougen, H P; Cryz, S J

    1995-01-01

    In a rat model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis (CF) we studied whether the inflammatory response could be altered by vaccination. Rats were immunized with either a depolymerized alginate toxin A conjugate (D-ALG toxin A), purified alginate, an O-polysacc......In a rat model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis (CF) we studied whether the inflammatory response could be altered by vaccination. Rats were immunized with either a depolymerized alginate toxin A conjugate (D-ALG toxin A), purified alginate, an O......-polysaccharide toxin A conjugate, or sterile saline. After challenge none of the rats immunized with D-ALG toxin A died, in contrast to the other two vaccine groups combined (p = 0.03). A significant reduction in the severity of the macroscopic lung inflammation was seen in rats immunized with D-ALG toxin A, compared...... with the other three groups (p = 0.009). The histopathologic response in the control rats was dominated by numerous polymorphonuclear leukocytes (PMN) surrounding the alginate beads. In contrast, the histopathologic response in rats immunized with D-ALG toxin A changed within the first week after challenge from...

  16. Effect of the alginate composition on the biocompatibility of alginate-polylysine microcapsules

    NARCIS (Netherlands)

    DeVos, P; DeHaan, B; VanSchilfgaarde, R

    Alginate-polylysine (PLL) capsules are commonly applied for immunoprotection of endocrine tissues. Alginate is composed of mannuronic acid (M) and guluronic acid (G). Different types of alginate have different ratios of G to M, but little is known of the influence of these differences on

  17. Alginate encapsulated nanoparticle-microorganism system for trichloroethylene remediation

    Science.gov (United States)

    Shanbhogue, Sai Sharanya

    Nanoscale zero-valent iron (NZVI) particles were encapsulated in calcium alginate capsules for application in environmental remediation. TCE degradation rates for encapsulated and bare NZVI were similar indicating no adverse effects of encapsulation on degradation kinetics. Microorganisms were separately encapsulated and used along with encapsulated NZVI and co-encapsulated in calcium alginate capsules. Batch experiments were performed to test the efficacy of the combined iron-Pseudomonas sp. (PpF1) system. The combined system removed 100% TCE over the first three hours of the experiment followed by 70% TCE removal post TCE re-dosing. Complete reduction of TCE was achieved by NZVI between 0--3 h and the second phase of treatment (3--36 h) was mostly achieved by microorganisms. Experiments conducted with co-encapsulated NZVI-D.BAV1 achieved 100% TCE removal. During the first three hours of the experiment 100% TCE removal was achieved by NZVI, and 100% removal was achieved post re-dosing where D.BAV1 accomplished the treatment.

  18. Pseudomonas aeruginosa in Healthcare Settings

    Science.gov (United States)

    ... Sepsis Sharps Safety - CDC Transplant Safety Vaccine Safety Pseudomonas aeruginosa in Healthcare Settings Recommend on Facebook Tweet Share ... aeruginosa . Pseudomonas aeruginosa What types of infections does Pseudomonas aeruginosa cause? Serious Pseudomonas infections usually occur in people ...

  19. Engineering alginate as bioink for bioprinting.

    Science.gov (United States)

    Jia, Jia; Richards, Dylan J; Pollard, Samuel; Tan, Yu; Rodriguez, Joshua; Visconti, Richard P; Trusk, Thomas C; Yost, Michael J; Yao, Hai; Markwald, Roger R; Mei, Ying

    2014-10-01

    Recent advances in three-dimensional (3-D) printing offer an excellent opportunity to address critical challenges faced by current tissue engineering approaches. Alginate hydrogels have been used extensively as bioinks for 3-D bioprinting. However, most previous research has focused on native alginates with limited degradation. The application of oxidized alginates with controlled degradation in bioprinting has not been explored. Here, a collection of 30 different alginate hydrogels with varied oxidation percentages and concentrations was prepared to develop a bioink platform that can be applied to a multitude of tissue engineering applications. The authors systematically investigated the effects of two key material properties (i.e. viscosity and density) of alginate solutions on their printabilities to identify a suitable range of material properties of alginates to be applied to bioprinting. Further, four alginate solutions with varied biodegradability were printed with human adipose-derived stem cells (hADSCs) into lattice-structured, cell-laden hydrogels with high accuracy. Notably, these alginate-based bioinks were shown to be capable of modulating proliferation and spreading of hADSCs without affecting the structure integrity of the lattice structures (except the highly degradable one) after 8days in culture. This research lays a foundation for the development of alginate-based bioink for tissue-specific tissue engineering applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Antibiotic penetration and bacterial killing in a Pseudomonas aeruginosa biofilm model

    DEFF Research Database (Denmark)

    Cao, Bao; Christophersen, Lars; Thomsen, Kim

    2015-01-01

    OBJECTIVES: Treating biofilm infections successfully is a challenge. We hypothesized that biofilms may be considered as independent compartments with particular pharmacokinetics. We therefore studied the pharmacokinetics and pharmacodynamics of tobramycin in a seaweed alginate-embedded biofilm...... model. METHODS: Seaweed alginate beads containing Pseudomonas aeruginosa were cultured in LB medium, sampled at day 1, 3, 5 or 7 and examined for the effect of treatment with tobramycin for 30 min. Treated beads were homogenized and the number of cfu was determined. The antibiotic concentration...

  1. Novel mouse model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis

    DEFF Research Database (Denmark)

    Hoffmann, Nadine; Rasmussen, Thomas Bovbjerg; Jensen, Peter Østrup

    2005-01-01

    Pseudomonas aeruginosa causes a chronic infection in the lungs of cystic fibrosis (CF) patients by establishing an alginate-containing biofilm. The infection has been studied in several animal models; however, most of the models required artificial embedding of the bacteria. We present here a new...... pulmonary mouse model without artificial embedding. The model is based on a stable mucoid CF sputum isolate (NH57388A) with hyperproduction of alginate due to a deletion in mucA and functional N-acylhomoserine lactone (AHL)-based quorum-sensing systems. Chronic lung infection could be established in both CF...

  2. Non-Invasive Evaluation of Alginate/Poly-L-lysine/Alginate Microcapsules by Magnetic Resonance Microscopy

    OpenAIRE

    Constantinidis, Ioannis; Grant, Samuel C.; Celper, Susanne; Gauffin-Holmberg, Isabel; Agering, Kristina; Oca-Cossio, Jose A.; Bui, Jonathan D.; Flint, Jeremy; Hamaty, Christine; Simpson, Nicholas E.; Blackband, Stephen J.

    2007-01-01

    In this report, we present data to demonstrate the utility of 1H MR microscopy to noninvasively examine alginate/poly-L-lysine/alginate (APA) microcapsules. Specifically, high-resolution images were used to visualize and quantify the poly-L-lysine (PLL) layer, and monitor temporal changes in the alginate gel microstructure during a month long in vitro culture. The thickness of the alginate/PLL layer was quantified to be 40.6±6.2 μm regardless of the alginate composition used to generate the b...

  3. Radiation degradation of alginate and some results of biological effect of degraded alginate on plants

    Energy Technology Data Exchange (ETDEWEB)

    Hien, N.Q.; Hai, L.; Luan, L.Q.; Hanh, T.T. [Nuclear Research Institute, Dalat (Viet Nam); Nagasawa, Naotsugu; Yoshii, Fumio; Makuuchi, Keizo; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2000-03-01

    Radiation degradation yields (Gd) of alginate in aqueous solution with different concentration were determined by viscometry method. The relationship between Gd and the alginate concentration was found out as: Gd=33.5 x C{sup -0.68}, with C% (w/v) and dry alginate referred to C=100%. An empirical equation for preparing degraded alginate with the desired low viscometry average molecular weight (Mv) by radiation was proposed. Alginate extracted directly horn seaweed'Sagassum, degraded by radiation was used for field experiments and results of the biological effect on plants (tea, carrot, chrysanthemum) were presented. (author)

  4. Players over the Surface: Unraveling the Role of Exopolysaccharides in Zinc Biosorption by Fluorescent Pseudomonas Strain Psd.

    Science.gov (United States)

    Upadhyay, Anamika; Kochar, Mandira; Rajam, Manchikatla V; Srivastava, Sheela

    2017-01-01

    Fluorescent Pseudomonas strain Psd is a soil isolate, possessing multiple plant growth promoting (PGP) properties and biocontrol potential. In addition, the strain also possesses high Zn2+ biosorption capability. In this study, we have investigated the role exopolysaccharides (EPS) play in Zn2+ biosorption. We have identified that alginates are the prime components contributing to Zn2+ biosorption. Deletion of the alg8 gene, which codes for a sub-unit of alginate polymerase, led to a significant reduction in EPS production by the organism. We have also demonstrated that the increased alginate production in response to Zn2+ exposure leads to improved biofilm formation by the strain. In the alg8 deletion mutant, however, biofilm formation was severely compromised. Further, we have studied the functional implications of Zn2+ biosorption by Pseudomonas strain Psd by demonstrating the effect on the PGP and biocontrol potential of the strain.

  5. Crystal structure of bacterial cell-surface alginate-binding protein with an M75 peptidase motif

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yukie; Ochiai, Akihito [Laboratory of Basic and Applied Molecular Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan); Mikami, Bunzo [Laboratory of Applied Structural Biology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan); Hashimoto, Wataru [Laboratory of Basic and Applied Molecular Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan); Murata, Kousaku, E-mail: kmurata@kais.kyoto-u.ac.jp [Laboratory of Basic and Applied Molecular Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2011-02-18

    Research highlights: {yields} Bacterial alginate-binding Algp7 is similar to component EfeO of Fe{sup 2+} transporter. {yields} We determined the crystal structure of Algp7 with a metal-binding motif. {yields} Algp7 consists of two helical bundles formed through duplication of a single bundle. {yields} A deep cleft involved in alginate binding locates around the metal-binding site. {yields} Algp7 may function as a Fe{sup 2+}-chelated alginate-binding protein. -- Abstract: A gram-negative Sphingomonas sp. A1 directly incorporates alginate polysaccharide into the cytoplasm via the cell-surface pit and ABC transporter. A cell-surface alginate-binding protein, Algp7, functions as a concentrator of the polysaccharide in the pit. Based on the primary structure and genetic organization in the bacterial genome, Algp7 was found to be homologous to an M75 peptidase motif-containing EfeO, a component of a ferrous ion transporter. Despite the presence of an M75 peptidase motif with high similarity, the Algp7 protein purified from recombinant Escherichia coli cells was inert on insulin B chain and N-benzoyl-Phe-Val-Arg-p-nitroanilide, both of which are substrates for a typical M75 peptidase, imelysin, from Pseudomonas aeruginosa. The X-ray crystallographic structure of Algp7 was determined at 2.10 A resolution by single-wavelength anomalous diffraction. Although a metal-binding motif, HxxE, conserved in zinc ion-dependent M75 peptidases is also found in Algp7, the crystal structure of Algp7 contains no metal even at the motif. The protein consists of two structurally similar up-and-down helical bundles as the basic scaffold. A deep cleft between the bundles is sufficiently large to accommodate macromolecules such as alginate polysaccharide. This is the first structural report on a bacterial cell-surface alginate-binding protein with an M75 peptidase motif.

  6. Disinfectant Efficacy of 0.525% Sodium Hypochlorite and Epimax on Alginate Impression Material.

    Science.gov (United States)

    Choudhury, Gopal Krishna; Chitumalla, Rajkiran; Manual, Litto; Rajalbandi, Santosh Kumar; Chauhan, Mahinder Singh; Talukdar, Pratim

    2018-01-01

    Species of Streptococcus, Escherichia coli, Staphylococcus, Actinomyces, Pseudomonas, Klebsiella, and Candida are commonly seen in the oral cavity. Impression materials are commonly contaminated with microorganisms. The present study was conducted to assess the disinfection efficacy of Epimax and 0.525% sodium hypochlorite on alginate impression over a period of 10 minutes. This study was conducted in the Department of Prosthodontics in the year 2015. An alginate impression material was prepared. For each bacteria species, 15 samples were used. Out of 15 samples, 3 were used by 0.525% sodium hypochlorite for disinfection for 5 minutes and 3 others for 10 minutes. Similarly, 3 samples were used by Epimax for 5 minutes and other 3 for 10 minutes. Three samples were used as controls. Each sample was polluted with Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus strains. There was no statistical difference in P. aeruginosa and C. albicans after 5 minutes, whereas S. aureus showed significant difference (p < 0.05). Epimax was found to be more effective in removing S. aureus as compared with other disinfectants. Both Epimax and 0.525% sodium hypochlorite did not show significant difference against P. aeruginosa and C. albicans, whereas significant difference was found between both agents against S. aureus (p < 0.05). It was seen that Epimax eliminated S. aureus after 5 minutes and P. aeruginosa after 10 minutes and 99.8% C. albicans after 10 minutes. About 0.525% sodium hypochlorite eliminated 99.1% of C. albicans after 10 minutes, whereas 98.5 and 99% of S. aureus and P. aeruginosa were eliminated after 10 minutes respectively. Both Epimax and 0.525% sodium hypochlorite can disinfect the alginate impression material against C. albicans, P. aeruginosa, and S. aureus strains. However, Epimax was found to be more effective against S. aureus as compared with 0.525% sodium hypochlorite. Efficacy of disinfection of sodium hypo-chlorite and Epimax on

  7. Chronic Pseudomonas aeruginosa lung infection in normal and athymic rats

    DEFF Research Database (Denmark)

    Johansen, H K; Espersen, F; Pedersen, S S

    1993-01-01

    We have compared a chronic lung infection with Pseudomonas aeruginosa embedded in alginate beads in normal and athymic rats with an acute infection with free live P. aeruginosa bacteria. The following parameters were observed and described: mortality, macroscopic and microscopic pathologic changes......, and antibody responses. The rats challenged with P. aeruginosa alginate beads experienced a generally more severe lung pathology and the antibody responses were more homogeneous with less dispersion as compared to the rats having free live P. aeruginosa bacteria. In general, manifestations were more severe...... in the athymic rats compared to the normal rats. It is, however, notable that the athymic rats developed similar microscopic lung manifestations as the normal rats when given a large number of P. aeruginosa in the beads, with dense accumulation of neutrophil granulocytes and microcolonies comparable...

  8. Formulation of Sodium Alginate Nanospheres Containing ...

    African Journals Online (AJOL)

    Purpose: The aim of this work was to formulate sodium alginate nanospheres of amphotericin B by controlled gellification method and to evaluate the role of the nanospheres as a “passive carrier” in targeted antifungal therapy. Methods: Sodium alginate nanospheres of amphotericin B were prepared by controlled ...

  9. Drying and Rehydration of Calcium Alginate Gels

    NARCIS (Netherlands)

    Vreeker, R.; Li, L.; Fang, Y.; Appelqvist, I.; Mendes, E.

    2008-01-01

    In this paper, we study the rehydration properties of air-dried calcium alginate gel beads. Rehydration is shown to depend on alginate source (i.e. mannuronic to guluronic acid ratio) and the salt concentration in the rehydration medium. Rehydration curves are described adequately by the empirical

  10. Engineering alginate for intervertebral disc repair

    NARCIS (Netherlands)

    Bron, Johannes L.; Vonk, Lucienne A.; Smit, Theodoor H.; Koenderink, Gijsje H.

    2011-01-01

    Alginate is frequently studied as a scaffold for intervertebral disc (IVD) repair, since it closely mimics mechanical and cell-adhesive properties of the nucleus pulposus (NP) of the IVD. The aim of this study was to assess the relation between alginate concentration and scaffold stiffness and find

  11. Technological Advance for Alginate Production in Mexico

    Directory of Open Access Journals (Sweden)

    Hernández-Carmona G.

    2012-04-01

    Full Text Available Alginates are polysaccharides extracted from brown seaweeds. They are used in food industry, pharmaceutical, textile, among other, because of their properties to give high viscous solution and gel forming. This review describes the optimized process at pilot plant level for alginate production. The process includes washing the algae with HCl at pH 4, extraction of the alginate in Na2CO3 solution at pH 10 and heating to 80oC, dilution of the paste and filtrate with a vacuum rotary filter. Alginate precipitation is carried out by adding CaCl2 filtration. The fibers obtained are treated with HCl to obtain alginic acid. The product is neutralized with Na2CO3 to obtain sodium alginate. The product is dried with hot air, milled, and screened at different mesh sizes. We described the different products obtained and their physical and chemical properties. Finally, costs and barriers found that limit the alginate production at commercial level in Mexico are discussed, including the lack of the industrial design, the international cost of the alginates, the policy to give the seaweeds beds concessions, and the role of the investors.

  12. Preparation of Alginate Gel Beads Containing Metformin ...

    African Journals Online (AJOL)

    A new emulsion gelation method was used to prepare gel beads for a highly water-soluble drug metformin hydrochloride using sodium alginate as the polymer. The gel beads containing oil was prepared by gently mixing or homogenizing oil and water phase containing sodium alginate which was then extruded into calcium ...

  13. Method Designed To Detect Alginate-Degrading Bacteria

    OpenAIRE

    Kitamikado, Manabu; Yamaguchi, Kuniko; Tseng, Chao-Huang; Okabe, Bun'Ichi

    1990-01-01

    A simple turbidimetric method was developed to detect alginate degradation. Bacteria were grown in alginate-containing media, and culture fluids were mixed with an acidic albumin solution. Failure to develop a white turbidity indicated an alginate degrader. The method showed alginate degradation by Vibrio alginolyticus ATCC 17749, in contrast to prior descriptions.

  14. Pseudomonas aeruginosa biofilms in cystic fibrosis

    DEFF Research Database (Denmark)

    Høiby, Niels; Ciofu, Oana; Bjarnsholt, Thomas

    2010-01-01

    of mutations, slow growth and adaptation of the bacteria to the conditions in the lungs, and to antibiotic therapy. Low bacterial metabolic activity and increase of doubling times of the bacterial cells in CF lungs are responsible for some of the tolerance to antibiotics. Conventional resistance mechanisms......, such as chromosomal ß-lactamase, upregulated efflux pumps, and mutations of antibiotic target molecules in the bacteria, also contribute to the survival of P. aeruginosa biofilms. Biofilms can be prevented by early aggressive antibiotic prophylaxis or therapy, and they can be treated by chronic suppressive therapy.......The persistence of chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) patients is due to biofilm-growing mucoid (alginate-producing) strains. A biofilm is a structured consortium of bacteria, embedded in a self-produced polymer matrix consisting of polysaccharide, protein...

  15. Encapsulation of Autoinducer Sensing Reporter Bacteria in Reinforced Alginate-Based Microbeads.

    Science.gov (United States)

    Li, Ping; Müller, Mareike; Chang, Matthew Wook; Frettlöh, Martin; Schönherr, Holger

    2017-07-12

    Quorum sensing, in which bacteria communities use signaling molecules for inter- and intracellular communication, has been intensively studied in recent decades. In order to fabricate highly sensitive easy-to-handle point of care biosensors that detect quorum sensing molecules, we have developed, as is reported here, reporter bacteria loaded alginate-methacrylate (alginate-MA) hydrogel beads. The alginate-MA beads, which were obtained by electrostatic extrusion, were reinforced by photo-cross-linking to increase stability and thereby to reduce bacteria leaching. In these beads the genetically engineered fluorescent reporter bacterium Escherichia coli pTetR-LasR-pLuxR-GFP (E. coli pLuxR-GFP) was encapsulated, which responds to the autoinducer N-(3-oxododecanoyl)homoserine lactone secreted by Pseudomonas aeruginosa. After encapsulation in alginate-MA hydrogel beads with diameters in the range of 100-300 μm that were produced by an electrostatic extrusion method and rapid photo-cross-linking, the E. coli pLuxR-GFP were found to possess a high degree of viability and sensing activity. The encapsulated bacteria could proliferate inside the hydrogel beads, when exposed to bacteria culture medium. In media containing the autoinducer N-(3-oxododecanoyl)homoserine lactone, the encapsulated reporter bacteria responded with a strong fluorescence signal due to an increased green fluorescent protein (GFP) expression. A prototype dipstick type sensor developed here underlines the potential of encapsulation of viable and functional reporter bacteria inside reinforced alginate-methacrylate hydrogel beads for whole cell sensors for bacteria detection.

  16. Exopolysaccharides Produced by Phytopathogenic Pseudomonas syringae Pathovars in Infected Leaves of Susceptible Hosts

    Science.gov (United States)

    Fett, William F.; Dunn, Michael F.

    1989-01-01

    Bacterial exopolysaccharide (EPS) was extracted from infected leaves of several host plants inoculated with phytopathogenic strains of Pseudomonas syringae pathovars. Extraction was by a facilitated diffusion procedure or by collection of intercellular fluid using a centrifugation method. The extracted EPS was purified and characterized. All bacterial pathogens which induced watersoaked lesions on their host leaves, a characteristic of most members of this bacterial group, were found to produce alginic acid (a polymer consisting of varying ratios of mannuronic and guluronic acids). Only trace amounts of bacterial EPS could be isolated from leaves inoculated with a pathovar (pv. syringae) which does not induce the formation of lesions with a watersoaked appearance. Guluronic acid was either present in very low amounts or absent in the alginic acid preparations. All bacterial alginates were acetylated (7-11%). Levan (a fructan) was apparently not produced as an EPS in vivo by any of the pathogens tested. PMID:16666545

  17. Methods of detecting and controlling mucoid Pseudomonas biofilm production

    Science.gov (United States)

    Yu, Hongwei D. (Inventor); Qiu, Dongru (Inventor)

    2013-01-01

    Compositions and methods for detecting and controlling the conversion to mucoidy in Pseudomonas aeruginosa are disclosed. The present invention provides for detecting the switch from nonmucoid to mucoid state of P. aeruginosa by measuring mucE expression or MucE protein levels. The interaction between MucE and AlgW controls the switch to mucoidy in wild type P. aeruginosa. Also disclosed is an alginate biosynthesis heterologous expression system for use in screening candidate substances that inhibit conversion to mucoidy.

  18. Azithromycin blocks quorum sensing and alginate polymer formation and increases the sensitivity to serum and stationary growth phase killing of P. aeruginosa and attenuates chronic P. aeruginosa lung infection in Cftr -/--mice

    DEFF Research Database (Denmark)

    Hoffmann, N.; Lee, Bao le ri; Hentzer, Morten

    2007-01-01

    The consequences of O-acetylated alginate-producing Pseudomonas aeruginosa biofilms in the lungs of chronically infected cystic fibrosis (CF) patients are tolerance to both antibiotic treatments and effects on the innate and the adaptive defense mechanisms. In clinical trials, azithromycin (AZM...

  19. Pseudomonas aeruginosa PAO1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance.

    Science.gov (United States)

    Periasamy, Saravanan; Nair, Harikrishnan A S; Lee, Kai W K; Ong, Jolene; Goh, Jie Q J; Kjelleberg, Staffan; Rice, Scott A

    2015-01-01

    Pseudomonas aeruginosa PAO1 produces three polysaccharides, alginate, Psl, and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl, and Pel during biofilm formation of P. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of P. aeruginosa, Pseudomonas protegens, and Klebsiella pneumoniae. Loss of the Psl polysaccharide had the biggest impact on the integration of P. aeruginosa in the mixed species biofilms, where the percent composition of the psl mutant was significantly lower (0.06%) than its wild-type (WT) parent (2.44%). In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in P. aeruginosa representing 8.4 and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of P. aeruginosa and K. pneumoniae were not affected by loss of alginate, Pel, or Psl, while the mucoid P. aeruginosa strain achieved a greater biomass than its parent strain. When P. aeruginosa was grown with P. protegens, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the WT PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35-40% of P. aeruginosa, which was significantly higher than the WT (5-20%). Loss of the Psl polysaccharide significantly reduced the percentage composition of P. aeruginosa in dual species biofilms with P. protegens (<1%). Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such communities.

  20. Pseudomonas aeruginosa PAO1 exopolysaccharides are important for mixed species biofilm community development and stress tolerance

    Directory of Open Access Journals (Sweden)

    Saravanan ePeriasamy

    2015-08-01

    Full Text Available Pseudomonas aeruginosa PAO1 produces three polysaccharides, alginate, Psl and Pel that play distinct roles in attachment and biofilm formation for monospecies biofilms. Considerably less is known about their role in the development of mixed species biofilm communities. This study has investigated the roles of alginate, Psl and Pel during biofilm formation of P. aeruginosa in a defined and experimentally informative mixed species biofilm community, consisting of P. aeruginosa, Pseudomonas protegens and Klebsiella pneumoniae. Loss of the Psl polysaccharide had the biggest impact on the integration of P. aeruginosa in the mixed species biofilms, where the percent composition of the psl mutant was significantly lower (0.06% than its wild-type parent (2.44%. In contrast, loss of the Pel polysaccharide had no impact on mixed species biofilm development. Loss of alginate or its overproduction resulted in P. aeruginosa representing 8.4% and 18.11%, respectively, of the mixed species biofilm. Dual species biofilms of P. aeruginosa and K. pneumoniae were not affected by loss of alginate, Pel or Psl, while the mucoid P. aeruginosa strain achieved a greater biomass than its parent strain. When P. aeruginosa was grown with P. protegens, loss of the Pel or alginate polysaccharides resulted in biofilms that were not significantly different from biofilms formed by the wild-type PAO1. In contrast, overproduction of alginate resulted in biofilms that were comprised of 35-40% of P. aeruginosa, which was significantly higher than the wild-type (5-20%. Loss of the Psl polysaccharide significantly reduced the percentage composition of P. aeruginosa in dual species biofilms with P. protegens (<1%. Loss of the Psl polysaccharide significantly disrupted the communal stress resistance of the three species biofilms. Thus, the polysaccharide composition of an individual species significantly impacts mixed species biofilm development and the emergent properties of such

  1. Encapsulation of cells in alginate gels.

    Science.gov (United States)

    Sánchez, Pello; Hernández, Rosa María; Pedraz, José Luis; Orive, Gorka

    2013-01-01

    Cell microencapsulation is based on the immobilization of cells for continuous release of therapeutics. This approach has been tested in the treatment of many diseases and several clinical trials have been performed. Factors such as the choice of cells to be encapsulated, the biomaterial used, and the procedure for carrying out the capsules are important issues when implementing this technology.This book chapter makes a comprehensive description of alginate, the most frequently employed biomaterial, passing by its structure, the extraction and treatment, and finishing with the process of gelation. It also describes the various modifications that can be carried out to allow the interaction between the alginate and the integrin receptors of encapsulated cells. The main microencapsulation technologies are presented as well as how 100 μm alginate-Poly-L-Lysine-alginate microcapsules can be fabricated with Flow-focusing technology.

  2. [Progress of alginate-based biomedical materials].

    Science.gov (United States)

    Wei, Xiaojuan; Xi, Tingfei; Gu, Qisheng; Zheng, Yufeng

    2013-08-01

    To review the current situation of alginate-based biomedical materials, especially focus on the clinical strategies and research progress in the clinical applications and point out several key issues that should be concerned about. Based on extensive investigation of domestic and foreign alginate-based biomedical materials research and related patent, literature, and medicine producted, the paper presented the comprehensive analysis of its research and development, application status, and then put forward several new research directions which should be focused on. Alginate-based biomedical materials have been widely used in clinical field with a number of patients, but mainly in the fields of wound dressings and dental impression. Heart failure treatment, embolization, tissue engineering, and stem cells culture are expected to become new directions of research and products development. Development of alginate-based new products has good clinical feasibility and necessity, but a lot of applied basic researches should be carried out in the further investigations.

  3. Alginate dressing as a donor site haemostat.

    OpenAIRE

    Groves, A. R.; Lawrence, J. C.

    1986-01-01

    An alginate fibre dressing has been used to reduce blood loss from skin graft donor sites. Significant haemostasis has been achieved in the immediate post surgery phase and no adverse reactions observed.

  4. Stability of alginate microbead properties in vitro

    Science.gov (United States)

    Moya, Monica L.; Morley, Michael; Khanna, Omaditya; Opara, Emmanuel C.

    2013-01-01

    Alginate microbeads have been investigated clinically for a number of therapeutic interventions, including drug delivery for treatment of ischemic tissues, cell delivery for tissue regeneration, and islet encapsulation as a therapy for type I diabetes. The physical properties of the microbeads play an important role in regulating cell behavior, protein release, and biological response following implantation. In this research alginate microbeads were synthesized, varying composition (mannuronic acid to guluronic acid ratio), concentration of alginate and needle gauge size. Following synthesis, the size, volume fraction, and morphometry of the beads were quantified. In addition, these properties were monitored over time in vitro in the presence of varying calcium levels in the microenvironment. The initial volume available for solute diffusion increased with alginate concentration and mannuronic (M) acid content, and bead diameter decreased with M content but increased with needle diameter. Interestingly, microbeads eroded completely in saline in less than 3 weeks regardless of synthesis conditions much faster than what has been observed in vivo. However, microbead stability was increased by the addition of calcium in the culture medium. Beads synthesized with low alginate concentration and high G content exhibited a more rapid change in physical properties even in the presence of calcium. These data suggest that temporal variations in the physical characteristics of alginate microbeads can occur in vitro depending on synthesis conditions and microbead environment. The results presented here will assist in optimizing the design of the materials for clinical application in drug delivery and cell therapy. PMID:22350778

  5. Antibiotic resistance patterns of Pseudomonas spp. isolated from the River Danube

    Directory of Open Access Journals (Sweden)

    Clemens eKittinger

    2016-05-01

    Full Text Available Spread and persistence of antibiotic resistance pose a severe threat to human health, yet there is still lack of knowledge about reservoirs of antibiotic resistant bacteria in the environment. We took the opportunity of the Joint Danube Survey 3 (JDS3, the world's biggest river research expedition of its kind in 2013, to analyse samples originating from different sampling points along the whole length of the river. Due to its high clinical relevance, we concentrated on the characterization of Pseudomonas spp. and evaluated the resistance profiles of Pseudomonas spp. which were isolated from eight sampling points. In total, 520 Pseudomonas isolates were found, 344 (66.0% isolates were identified as Pseudomonas putida, and 141 (27.1% as Pseudomonas fluorescens, all other Pseudomonas species were represented by less than five isolates, among those two P. aeruginosa isolates. Thirty seven percent (37% of all isolated Pseudomonas species showed resistance to at least one out of eleven tested antibiotics. The most common resistance was against meropenem (30.4% / 158 isolates piperacillin/tazobactam (10.6% / 55 isolates and ceftazidime (4.2% / 22 isolates. 16 isolates (3.1% / 16 isolates were multi-resistant. For each tested antibiotic at least one resistant isolate could be detected. Sampling points from the upper stretch of the River Danube showed more resistant isolates than downriver. Our results suggest that antibiotic resistance can be acquired by and persists even in Pseudomonas species that are normally not in direct contact with humans. A possible scenario is that these bacteria provide a reservoir of antibiotic resistance genes that can spread to related human pathogens by horizontal gene transfer.

  6. Antifungal Activity of Selected Indigenous Pseudomonas and Bacillus from the Soybean Rhizosphere

    Science.gov (United States)

    León, M.; Yaryura, P. M.; Montecchia, M. S.; Hernández, A. I.; Correa, O. S.; Pucheu, N. L.; Kerber, N. L.; García, A. F.

    2009-01-01

    The purpose of this study was to isolate and select indigenous soil Pseudomonas and Bacillus bacteria capable of developing multiple mechanisms of action related to the biocontrol of phytopathogenic fungi affecting soybean crops. The screening procedure consisted of antagonism tests against a panel of phytopathogenic fungi, taxonomic identification, detection by PCR of several genes related to antifungal activity, in vitro detection of the antifungal products, and root colonization assays. Two isolates, identified and designated as Pseudomonas fluorescens BNM296 and Bacillus amyloliquefaciens BNM340, were selected for further studies. These isolates protected plants against the damping-off caused by Pythium ultimum and were able to increase the seedling emergence rate after inoculation of soybean seeds with each bacterium. Also, the shoot nitrogen content was higher in plants when seeds were inoculated with BNM296. The polyphasic approach of this work allowed us to select two indigenous bacterial strains that promoted the early development of soybean plants. PMID:20016811

  7. In vitro and in vivo evaluation of alginate and alginate- chitosan ...

    African Journals Online (AJOL)

    Keywords: Alginate, Beads, Chitosan, Metformin, Diabetes, In vivo study. Tropical ... Diabetes, and the American Diabetes. Association as the first line therapy for Type 2 diabetes [2,3]. Following oral administration, the drug is mainly absorbed from the upper small intestine ..... HCl-loaded fenugreek seed mucilage alginate.

  8. Production of Alginate Oligosaccharides (AOS as Prebiotic Ingredients through by Alginate lyase enzyme

    Directory of Open Access Journals (Sweden)

    Fahriza Sri Afni

    2017-04-01

    Full Text Available Prebiotics is indigestible foods that can not be digested but can stimulate the growth and activity of bacteria in the digestive tract effecting human health. Alginate oligosaccharides (AOS can be used as a source of prebiotic. That compounds can be produced enzymatically by cutting long chain alginates using alginate lyase. The aim of this study was to produce alginate lyase enzyme then producing Alginate oligosaccharides (AOS as a prebiotic ingredients. The alginate lyase enzyme can be produced from Bacillus megaterium bacteria using a discontinuous fermentor. The enzyme was  optimum temperature of 45°C and an optimum pH of 7.0. Alginate oligosaccharides production was performed with the addition of different enzyme concentrations 25, 50, 75, and 100 U. The result of the addition of enzyme (25, 50,75 U showed that the value of polymerization degrees (DP were between 4-5. However, the addition of enzyme (100 U was in the range of  DP 3-4. Bacterial probiotic growth test results of Bifidobacteria and Lactobacillus showed that 1% added AOS media were able to increase the growth of probiotic bacteria compared to themedia without addition of AOS. The addition Alginate lyase activity of 50 U in AOS production is the best treatment of both probiotic bacteria.

  9. PLGA/alginate composite microspheres for hydrophilic protein delivery

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Peng [Department of Anatomy and Cell Biology, University of Saskatchewan, S7N5E5 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada); Chen, X.B. [Department of Mechanical Engineering, University of Saskatchewan, S7N5A9 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada); Schreyer, David J., E-mail: david.schreyer@usask.ca [Department of Anatomy and Cell Biology, University of Saskatchewan, S7N5E5 (Canada); Division of Biomedical Engineering, University of Saskatchewan, S7N5A9 (Canada)

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate. - Highlights: • A double emulsion technique is used to prepare protein-loaded PLGA or PLGA/alginate microspheres. • PLGA, alginate and protein are distributed evenly within microsphere structure. • Addition of alginate improves loading efficiency and slows degradation and protein release. • PLGA/alginate microspheres have favorable biocompatibility.

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

    Science.gov (United States)

    2017-02-02

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

  11. Pengaruh Waktu Pengisian Cetakan Alginate Terhadap Ketepatan Model Hasil Cetakan

    OpenAIRE

    Suhailatun Nasifah Rangkuti

    2008-01-01

    Bahan cetak alginate sampai sekarang masih banyak digunakan di Kedokteran Gigi dengan alasan penanganannya mudah, alat yang dipergunakan relatif sederhana, elastis, cukup akurat dan relatif lebih murah. Umumnya komposisi alginate terdiri dari polasturn alginate, diatomaceus earth, zinc oxide, kalsium sulfaty potasium sulfat, sodium fo&fat, glikol serta bahan pewangi. Tiap komponen mempunyai fungsi tertentu dan mempengaruhi sifat-sifat bahan cetak alginate. Dalam pemanipulasian bahan ...

  12. Versatile click alginate hydrogels crosslinked via tetrazine–norbornene chemistry

    OpenAIRE

    Desai, Rajiv; Koshy, Sandeep Tharian; Hilderbrand, Scott A.; Mooney, David J.; Joshi, Neel S.

    2015-01-01

    Alginate hydrogels are well-characterized, biologically inert materials that are used in many biomedical applications for the delivery of drugs, proteins, and cells. Unfortunately, canonical covalently crosslinked alginate hydrogels are formed using chemical strategies that can be biologically harmful due to their lack of chemoselectivity. In this work we introduce tetrazine and norbornene groups to alginate polymer chains and subsequently form covalently crosslinked click alginate hydrogels ...

  13. Invasive behaviour and depolarization effect of Pseudomonas ...

    African Journals Online (AJOL)

    ... reveals that P. fluorescens induces the sequential activation of a constitutive calcium dependent NOS and that of an inducible NOS activated by LPS. Ours results also suggest that P. fluorescens cytotoxicity and invasion are not mutually exclusive events. Key Words: Cytotoxicity, Lipopolysaccharide, Patch-clamp, Invasion ...

  14. Comparative evaluation of organic formulations of Pseudomonas ...

    African Journals Online (AJOL)

    Jane

    2011-07-20

    Jul 20, 2011 ... ment of the potential biocontrol agent P. fluorescens and explore the efficacy of P. fluorescens based bioformu- lations in suppressing bacterial wilt of brinjal in pot experiment and field conditions. MATERIALS AND METHODS. Source of the pathogen. Brinjal plants showing typical symptoms of bacterial wilt ...

  15. An effect of alginate on the stability of LDH nanosheets in aqueous solution and preparation of alginate/LDH nanocomposites.

    Science.gov (United States)

    Kang, Hongliang; Shu, Yang; Li, Zhuang; Guan, Bo; Peng, Shunjin; Huang, Yong; Liu, Ruigang

    2014-01-16

    Nanosheets under 10nm in thickness are obtained by exfoliating layered double hydroxide (LDH) in formamide. The LDH nanosheets are dispersed and stabilized in an alginate aqueous solution after removing formamide by water washing and ultracentrifugation. During the water washing stage LDH nanosheets can be prevented from restacking by electrostatic stabilization of the surface of LDH sheets through the adsorption of alginate. Alginate/LDH nanocomposites can be prepared by drying the dispersion, and sandwich-like structures in the nanocomposites are formed with two alginate layers contained between two LDH sheets. LDH nanosheets in the dried alginate/LDH nanocomposites can be re-dispersed in water. The thermal stability of alginate in the nanocomposite is increased by LDH. Alginate membranes containing this layered nanocomposite can be prepared. The addition of LDH into the alginate matrix leads to an increase in the mechanical properties of the nanocomposite. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Pseudomonas granadensis sp. nov., a new bacterial species isolated from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain.

    Science.gov (United States)

    Pascual, Javier; García-López, Marina; Bills, Gerald F; Genilloud, Olga

    2015-02-01

    During the course of screening bacterial isolates as sources of as-yet unknown bioactive compounds with pharmaceutical applications, a chemo-organotrophic, Gram-negative bacterium was isolated from a soil sample taken from the Tejeda, Almijara and Alhama Natural Park, Granada, Spain. Strain F-278,770(T) was oxidase- and catalase-positive, aerobic, with a respiratory type of metabolism with oxygen as the terminal electron acceptor, non-spore-forming and motile by one polar flagellum, although some cells had two polar flagella. Phylogenetic analysis of the 16S rRNA, gyrB, rpoB and rpoD genes revealed that strain F-278,770(T) belongs to the Pseudomonas koreensis subgroup (Pseudomonas fluorescens lineage), with Pseudomonas moraviensis, P. koreensis, P. baetica and P. helmanticensis as its closest relatives. Chemotaxonomic traits such as polar lipid and fatty acid compositions and G+C content of genomic DNA corroborated the placement of strain F-278,770(T) in the genus Pseudomonas. DNA-DNA hybridization assays and phenotypic traits confirmed that this strain represents a novel species of the genus Pseudomonas, for which the name Pseudomonas granadensis sp. nov. is proposed. The type strain is F-278,770(T) ( = DSM 28040(T) = LMG 27940(T)). © 2015 Fundacion MEDINA, Centro de Excelencia en Investigacion de Medicamentos Innovadores en Andalucia.

  17. Development of Alginate/Chitosan Microparticles for Dust Mite ...

    African Journals Online (AJOL)

    Erah

    Conclusion: This study indicates that alginate and alginate-coated chitosan microparticles are safe and can be further developed for mucosal ... properties. Additionally, chitosan micro/nanoparticles can be easily prepared by ionic ... obstacles is by coating an acid-resistant polymer, such as sodium alginate, onto the.

  18. Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization

    OpenAIRE

    Mori, Tetsushi; Takahashi, Mami; Tanaka, Reiji; Miyake, Hideo; Shibata, Toshiyuki; Chow, Seinen; Kuroda, Kouichi; Ueda, Mitsuyoshi; Takeyama, Haruko

    2016-01-01

    Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a prim...

  19. Alginate Lyases from Alginate-Degrading Vibrio splendidus 12B01 Are Endolytic

    Science.gov (United States)

    Badur, Ahmet H.; Jagtap, Sujit Sadashiv; Yalamanchili, Geethika; Lee, Jung-Kul; Zhao, Huimin

    2015-01-01

    Alginate lyases are enzymes that degrade alginate through β-elimination of the glycosidic bond into smaller oligomers. We investigated the alginate lyases from Vibrio splendidus 12B01, a marine bacterioplankton species that can grow on alginate as its sole carbon source. We identified, purified, and characterized four polysaccharide lyase family 7 alginates lyases, AlyA, AlyB, AlyD, and AlyE, from V. splendidus 12B01. The four lyases were found to have optimal activity between pH 7.5 and 8.5 and at 20 to 25°C, consistent with their use in a marine environment. AlyA, AlyB, AlyD, and AlyE were found to exhibit a turnover number (kcat) for alginate of 0.60 ± 0.02 s−1, 3.7 ± 0.3 s−1, 4.5 ± 0.5 s−1, and 7.1 ± 0.2 s−1, respectively. The Km values of AlyA, AlyB, AlyD, and AlyE toward alginate were 36 ± 7 μM, 22 ± 5 μM, 60 ± 2 μM, and 123 ± 6 μM, respectively. AlyA and AlyB were found principally to cleave the β-1,4 bonds between β-d-mannuronate and α-l-guluronate and subunits; AlyD and AlyE were found to principally cleave the α-1,4 bonds involving α-l-guluronate subunits. The four alginate lyases degrade alginate into longer chains of oligomers. PMID:25556193

  20. Biochemical Characteristics and Variable Alginate-Degrading Modes of a Novel Bifunctional Endolytic Alginate Lyase.

    Science.gov (United States)

    Cheng, Yuanyuan; Wang, Dandan; Gu, Jingyan; Li, Junge; Liu, Huihui; Li, Fuchuan; Han, Wenjun

    2017-12-01

    Bifunctional alginate lyases can efficiently degrade alginate comprised of mannuronate (M) and guluronate (G), but their substrate-degrading modes have not been thoroughly elucidated to date. In this study, we present Aly1 as a novel bifunctional endolytic alginate lyase of the genus Flammeovirga The recombinant enzyme showed optimal activity at 50°C and pH 6.0. The enzyme produced unsaturated disaccharide (UDP2) and trisaccharide fractions as the final main alginate digests. Primary substrate preference tests and further structure identification of various size-defined final oligosaccharide products demonstrated that Aly1 is a bifunctional alginate lyase and prefers G to M. Tetrasaccharide-size fractions are the smallest substrates, and M, G, and UDP2 fractions are the minimal product types. Remarkably, Aly1 can vary its substrate-degrading modes in accordance with the terminus types, molecular sizes, and M/G contents of alginate substrates, producing a series of small size-defined saturated oligosaccharide products from the nonreducing ends of single or different saturated sugar chains and yielding unsaturated products in distinct but restricted patterns. The action mode changes can be partially inhibited by fluorescent labeling at the reducing ends of oligosaccharide substrates. Deletion of the noncatalytic region (NCR) of Aly1 caused weak changes of biochemical characteristics but increased the degradation proportions of small size-defined saturated M-enriched oligosaccharide substrates and unsaturated tetrasaccharide fractions without any size changes of degradable oligosaccharides, thereby enhancing the M preference and enzyme activity. Therefore, our results provided insight into the variable action mode of a novel bifunctional endolytic alginate lyase to inform accurate enzyme use.IMPORTANCE The elucidated endolytic alginate lyases usually degrade substrates into various size-defined unsaturated oligosaccharide products (≥UDP2), and exolytic enzymes

  1. Pseudomonas Lipopeptide Biosurfactants

    DEFF Research Database (Denmark)

    Bonnichsen, Lise

    Pseudomonas lipopetide biosurfactants are amphiphilic molecules with a broad range of natural functions. Due to their surface active properties, it has been suggested that Pseudomonas lipopetides potentially play a role in biodegradation of hydrophobic compounds and have essential functions...... in biofilm formation, however, detailed studies of these roles have not yet been carried out. The overall aim of this PhD project was therefore to elucidate in more depth the roles played by Pseudomonas lipopetides in pollutant biodegradation and biofilm formation. This study investigated the effect...... of the Pseudomonas lipopeptides belonging to different structural groups on important biodegradation parameters, mainly; solubilization and emulsification of hydrophobic pollutants (alkanes and PAHs) and increase of cell surface hydrophobicity of bacterial degraders. Ultimately, it was tested if these parameters led...

  2. Storage duration effect on deformation recovery of repacked alginates

    Directory of Open Access Journals (Sweden)

    Siti Sunarintyas

    2009-09-01

    Full Text Available Background: Manufacturers supply alginate impression materials as a powder that is packaged in bulk and in individual container. Some Indonesian dental suppliers often repackage the bulk alginate into individual plastic packages which are not tied tightly and stored in the display room without air conditioner. It is known that critical factors to the shelf life of alginate includer avoidance of moisture contamination which may lead to premature setting of the alginate and avoidance of high temperature which may cause depolymerization of the alginate. Purpose: The aim of this study was to determine storage duration effect of repacked alginates on deformation recovery. Methods: Two brands of alginates (Tulip®TU, and Aroma Fine DF III®AF were repacked into 120 plastic containers. The samples were stored in room condition (temperature 29° C ± 1° C, relative humidity 60% ± 10% for 1, 2, 3, 4 and 5 weeks. The alginates setting time and recovery from deformation were measured according to the ANSI/ADA specification number 18 (ISO 1563. result: The results revealed that there was decreased setting time during 5 weeks but there was slight decreased in deformation recovery after 3 weeks storage. The ANOVA showed there was no significant difference of alginates deformation recovery among the storage times (p > 0.05. Conclusion: Storage duration of repacked alginates in plastic containers during 5 weeks in room condition do not influence the alginate deformation recovery.

  3. Physicochemical properties of marine collagen-alginate biomaterial

    Science.gov (United States)

    Soon, K. S.; Hii, S. L.; Wong, C. L.; Leong, L. K.; Woo, K. K.

    2017-12-01

    Collagen base biomaterials are widely applied in the field of tissue engineering. However, these fibrous proteins in animal connective tissues are insufficient to fulfill the mechanical properties for such applications. Therefore, alginate as a natural polysaccharide was incorporated. In this study, Smooth wolf herring skins was collected from the local fish ball processing industry for collagen extraction using acid solubilisation method. On the other hand, alginate from brown seaweed (Sargassum polycystum) was extracted with calcium carbonate at 50 °C. The composite films of different collagen and alginate ratio were prepared by lyophilisation with pure collagen film as control. The effects of alginate on swelling behaviour, porosity, collagenase degradation and tensile strength of the composite films were investigated. Swelling behaviour increased with alginate content, 50 % alginate film achieved 1254.75 % swelling after 24 h. All composite films achieved more than 80 % porosity except the film with 80 % collagen (65.41 %). Porosity was highest in 100 % alginate (94.30 %). Highest tensile strength (1585.87 kPa) and young modulus (27.05 MPa) was found in 50 % alginate film. In addition, resistance to collagenase degradation was improved with alginate content, lowest degradation rate was determined in 80 % alginate film. Results indicated alginate is efficient in improving some mechanical properties of the composite film.

  4. Antimicrobial Activity of Various Plant Extracts on Pseudomonas Species Associated with Spoilage of Chilled Fish

    Directory of Open Access Journals (Sweden)

    Osan Bahurmiz

    2016-11-01

    Full Text Available The antimicrobial activity of various plant extracts on Pseudomonas bacteria isolated from spoiled chilled tilapia (Oreochromis sp. was evaluated in this study. In the first stage of this study, red tilapia was subjected to chilled storage (4°C for 3 weeks, and spoilage bacteria were isolated and identified from the spoiled fish. Pseudomonas was the dominant bacteria isolated from the spoiled fish and further identification revealed that P. putida, P. fluorescens and Pseudomonas spp. were the main species of this group. In the second stage, methanolic extracts of 15 selected plant species were screened for their antimicrobial activity, by agar disc diffusion method, against the Pseudomonas isolates. Results indicated that most of the extracts had different degrees of activity against the bacterial isolates. The strongest activity was exhibited by bottlebrush flower (Callistemon viminalis extract. This was followed by extracts from guava bark (Psidium guajava and henna leaf (Lawsonia inermis. Moderate antimicrobial activities were observed in extracts of clove (Syzygium aromaticum, leaf and peel of tamarind (Tamarindus indica, cinnamon bark (Cinnamomum zeylanicum, wild betel leaf (Piper sarmentosum and fresh thyme (Thymus spp.. Weak or no antimicrobial activity was observed from the remaining extracts. The potential antimicrobial activity shown by some plant extracts in this study could significantly contribute to the fish preservation.

  5. Influence of volatile organic compounds emitted by Pseudomonas and Serratia strains on Agrobacterium tumefaciens biofilms.

    Science.gov (United States)

    Plyuta, Vladimir; Lipasova, Valentina; Popova, Alexandra; Koksharova, Olga; Kuznetsov, Alexander; Szegedi, Erno; Chernin, Leonid; Khmel, Inessa

    2016-07-01

    The ability to form biofilms plays an important role in bacteria-host interactions, including plant pathogenicity. In this work, we investigated the action of volatile organic compounds (VOCs) produced by rhizospheric strains of Pseudomonas chlororaphis 449, Pseudomonas fluorescens B-4117, Serratia plymuthica IC1270, as well as Serratia proteamaculans strain 94, isolated from spoiled meat, on biofilms formation by three strains of Agrobacterium tumefaciens which are causative agents of crown-gall disease in a wide range of plants. In dual culture assays, the pool of volatiles emitted by the tested Pseudomonas and Serratia strains suppressed the formation of biofilms of A. tumefaciens strains grown on polycarbonate membrane filters and killed Agrobacterium cells in mature biofilms. The individual VOCs produced by the tested Pseudomonas strains, that is, ketones (2-nonanone, 2-heptanone, 2-undecanone), and dimethyl disulfide (DMDS) produced by Serratia strains, were shown to kill A. tumefaciens cells in mature biofilms and suppress their formation. The data obtained in this study suggest an additional potential of some ketones and DMDS as protectors of plants against A. tumefaciens strains, whose virulence is associated with the formation of biofilms on the infected plants. © 2016 APMIS. Published by John Wiley & Sons Ltd.

  6. Dissemination and persistence of Pseudomonas spp. in small-scale dairy farms

    Directory of Open Access Journals (Sweden)

    Daniele Michele Nucera

    2016-05-01

    Full Text Available This study was aimed at collecting data on presence, dissemination and persistence of Pseudomonas in small-scale dairy farms. Six farms (located in Piedmont were visited three times over 2014: 116 waters (wells and different faucets/pipes and 117 environmental samples (milking equipments and drains were collected. Enumeration of Pseudomonadaceae was performed, 3-5 colonies/samples were selected for identification via 16SrDNA/oprI polymerase chain reaction (PCR, and typed by enterobacterial-repetitive- intergenic-consensus (ERIC-PCR. Pseudomonadaceae were detected in 77% of samples. No statistical differences were found among proportions of positives across farms, sample typologies and seasons. Most isolates were Pseudomonas fluorescens (45%, and ERIC-PCR showed 32 persistent types diffused across farms. All in all, Pseudomonas spp. represents a challenge, considering its presence over time in water as well as in teat cups, indicating a continuous source of contamination. Moreover, persistency of strains may indicate biofilm-formation and/or sanitisers resistance, therefore emphasising the role of primary production for preventing milk contamination by Pseudomonas spp.

  7. In vitro and in vivo evaluation of alginate and alginate- chitosan ...

    African Journals Online (AJOL)

    chitosan (AL-CS) beads for oral application and to evaluate their in vitro .... gelling medium at room temperature [18,19]. After filtration, the beads were also ..... metformin HCl through incorporation into stomach specific floating alginate beads.

  8. Usefulness of Alginate Lyases Derived from Marine Organisms for the Preparation of Alginate Oligomers with Various Bioactivities.

    Science.gov (United States)

    Takeshita, S; Oda, T

    Alginate-degrading enzyme, alginate lyase, catalyzes the cleavage of glycosidic 1-4 O-linkages between uronic acid residues of alginate by a β-elimination reaction leaving a 4-deoxy-l-erythro-hex-4-ene pyranosyluronate as nonreducing terminal end. The enzymes from a wide variety of sources such as marine molluscs, seaweeds, and marine bacteria have been discovered and studied not only from a point of view of enzymological interest of enzyme itself but also for elucidation of fine chemical structure of alginate, structure-activity relationship of alginate, and biological activities and physicochemical features of the enzymatic digestion products. Based on the substrate specificities, alginate lyases are classified into three groups: poly(β-d-mannuronate) lyase, poly(α-l-guluronate) lyase, and bifunctional alginate lyase, which are specific to mannuronate, guluronate, and both uronic acid residues, respectively. We have studied enzymological aspects of these three types of alginate lyases, and bioactivities of enzymatically digested alginate oligomers. In this chapter, we described the purification and characterization of three types of alginate lyases from different marine origins and overviewed the bioactivities of alginate oligomers. © 2016 Elsevier Inc. All rights reserved.

  9. Self-disinfecting Alginate vs Conventional Alginate: Effect on Surface Hardness of Gypsum Cast-An in vitro Study.

    Science.gov (United States)

    Madhavan, Ranjith; George, Navia; Thummala, Niharika R; Ravi, S V; Nagpal, Ajay

    2017-11-01

    For the construction of any dental prosthesis, accurate impressions are necessary. Hence, we undertook the present study to evaluate and compare the surface hardness of gypsum casts poured from impressions made using conventional alginate and self-disinfecting alginate. A total of 30 impressions of stainless steel die were made, out of which 15 impressions were made with conventional alginate and 15 were made with self-disinfecting alginate and poured using Type III dental stone. Thirty stone specimens were subjected for hardness testing. Data were analyzed using independent samples t-test to compare the mean surface hardness. Difference in surface hardness was statistically insignificant (p > 0.05). Surface hardness of gypsum casts poured using impressions made from self-disinfecting alginate and conventional alginates were comparable. Self-disinfecting alginates may be employed in clinical practice as safe and effective materials to overcome the infection control issues without compromising on the properties of the material.

  10. Development of sodium alginate and konkoli gumgrafted ...

    African Journals Online (AJOL)

    This experiment is a continuation of our effort to develop a blend membrane of sodium alginate and “konkoli” gum-g-polyacrylamide (KG-g-PAAm) for bioremediation of wastewater. The effect of graft reaction conditions on the percentage graft yield in the graft copolymerization was investigated. It was observed that grafting ...

  11. An effective device for generating alginate microcapsules

    Directory of Open Access Journals (Sweden)

    Tatiana A.B. Bressel

    2008-01-01

    Full Text Available An alternative approach to somatic gene therapy is to deliver the therapeutic protein by implanting genetically modified cells that could overexpress the gene of interest. Microencapsulation devices were designed to protect cells from host rejection and prevent the foreign cells from spreading while allowing protein secretion. Alginate microcapsules form a semi-permeable structure that is suitable for in vivo injection. In this study, we report an effective laboratory protocol for producing calcium alginate microcapsules, following optimization of uniformly shaped and sized particles containing viable cells. Encapsulation of baby hamster kidney (BHK cells in alginate microcapsules was performed using a simple device consisting of a cylinder of compressed air and a peristaltic pump. A cell suspension flow of 100 mL h-1 and an air jet flow of 10 L min-1 produced the best uniformity of microcapsule size and shape. Cells maintained viability in culture for 4 weeks without any signs of necrosis, and protein diffusion was observed during this period. Our results clearly demonstrated that microisolation of BHK cells in alginate using a simple assembly device could provide an environment that is capable of preserving live cells. In addition, encapsulated cells under the conditions described were able to secrete an active enzyme even after four weeks, thus becoming potentially compatible with therapeutic protein delivery.

  12. Rusip with Alginate Addition as Seasoning

    Directory of Open Access Journals (Sweden)

    Dyah Koesoemawardani

    2017-02-01

    Full Text Available AbstractRusip was a fermented food of fish that have a distinctive aroma so that potential to be developed into instant seasoning. This research was aimed to optimize powder processing of rusip with the addition of alginate. The treatments were concentration of alginate (5% , 10% , 15% and 20% w/w and the heating temperature (50oC, 60oC , 70oC and 80oC. Data was analyzed using advanced test Honestly Significant Difference (HSD at 5% level. The results showed that the best rusip powder was alginate 5% with heating at 50oC and 70°C . The character were 5.98% and 7.57% water content; pH 5.69 and 5.85; 7.77% and 8.77% salt content; 28% and 27.65% protein content, respectively. This study proves that the addition of alginate 5% (w/w, heating at a temperature of 50oC and 70°C can trap volatile compounds formed during fermentation in rusip processing into powder.

  13. Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation.

    Science.gov (United States)

    Laverty, Garry; Gorman, Sean P; Gilmore, Brendan F

    2014-07-18

    Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl), pellicle Formation (Pel) and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides) that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation.

  14. Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Garry Laverty

    2014-07-01

    Full Text Available Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl, pellicle Formation (Pel and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation.

  15. Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation

    Science.gov (United States)

    Laverty, Garry; Gorman, Sean P.; Gilmore, Brendan F.

    2014-01-01

    Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl), pellicle Formation (Pel) and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides) that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation. PMID:25438014

  16. Discovery of a Novel Alginate Lyase from Nitratiruptor sp. SB155-2 Thriving at Deep-sea Hydrothermal Vents and Identification of the Residues Responsible for Its Heat Stability*

    Science.gov (United States)

    Inoue, Akira; Anraku, Moe; Nakagawa, Satoshi; Ojima, Takao

    2016-01-01

    Extremophiles are expected to represent a source of enzymes having unique functional properties. The hypothetical protein NIS_0185, termed NitAly in this study, was identified as an alginate lyase-homolog protein in the genomic database of ϵ-Proteobacteria Nitratiruptor sp. SB155-2, which was isolated from deep-sea hydrothermal vents at a water depth of 1,000 m. Among the characterized alginate lyases in the polysaccharide lyase family 7 (PL-7), the amino acid sequence of NitAly showed the highest identity (39%) with that of red alga Pyropia yezoensis alginate lyase PyAly. Recombinant NitAly (rNitAly) was successfully expressed in Escherichia coli. Purified rNitAly degraded alginate in an endolytic manner. Among alginate block types, polyM was preferable to polyG and polyMG as a substrate, and its end degradation products were mainly tri-, tetra-, and penta-saccharides. The optimum temperature and pH values were 70 °C and around 6, respectively. A high concentration of NaCl (0.8–1.4 m) was required for maximum activity. In addition, a 50% loss of activity was observed after incubation at 67 °C for 30 min. Heat stability was decreased in the presence of 5 mm DTT, and Cys-80 and Cys-232 were identified as the residues responsible for heat stability but not lyase activity. Introducing two cysteines into PyAly based on homology modeling using Pseudomonas aeruginosa alginate lyase PA1167 as the template enhanced its heat stability. Thus, NitAly is a functional alginate lyase, with its unique optimum conditions adapted to its environment. These insights into the heat stability of NitAly could be applied to improve that of other PL-7 alginate lyases. PMID:27231344

  17. Discovery of a Novel Alginate Lyase from Nitratiruptor sp. SB155-2 Thriving at Deep-sea Hydrothermal Vents and Identification of the Residues Responsible for Its Heat Stability.

    Science.gov (United States)

    Inoue, Akira; Anraku, Moe; Nakagawa, Satoshi; Ojima, Takao

    2016-07-22

    Extremophiles are expected to represent a source of enzymes having unique functional properties. The hypothetical protein NIS_0185, termed NitAly in this study, was identified as an alginate lyase-homolog protein in the genomic database of ϵ-Proteobacteria Nitratiruptor sp. SB155-2, which was isolated from deep-sea hydrothermal vents at a water depth of 1,000 m. Among the characterized alginate lyases in the polysaccharide lyase family 7 (PL-7), the amino acid sequence of NitAly showed the highest identity (39%) with that of red alga Pyropia yezoensis alginate lyase PyAly. Recombinant NitAly (rNitAly) was successfully expressed in Escherichia coli Purified rNitAly degraded alginate in an endolytic manner. Among alginate block types, polyM was preferable to polyG and polyMG as a substrate, and its end degradation products were mainly tri-, tetra-, and penta-saccharides. The optimum temperature and pH values were 70 °C and around 6, respectively. A high concentration of NaCl (0.8-1.4 m) was required for maximum activity. In addition, a 50% loss of activity was observed after incubation at 67 °C for 30 min. Heat stability was decreased in the presence of 5 mm DTT, and Cys-80 and Cys-232 were identified as the residues responsible for heat stability but not lyase activity. Introducing two cysteines into PyAly based on homology modeling using Pseudomonas aeruginosa alginate lyase PA1167 as the template enhanced its heat stability. Thus, NitAly is a functional alginate lyase, with its unique optimum conditions adapted to its environment. These insights into the heat stability of NitAly could be applied to improve that of other PL-7 alginate lyases. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Adsorption of CO2 by alginate immobilized zeolite beads

    Science.gov (United States)

    Suratman, A.; Kunarti, E. S.; Aprilita, N. H.; Pamurtya, I. C.

    2017-03-01

    Immobilized zeolit in alginate beads for adsorption of CO2 was developed. Alginate immobilized zeolit beads was generated by dropping the mixture of Na-alginate and zeolite solution into Ca2+ solution. The adsorption efficacy such as the influence of contact time, mass of zeolite, flowrate of CO2, and mass of adsorbent was evaluated. The adsorption of CO2 onto alginate immobilized zeolit beads was investigated by performing both equilibrium and kinetic batch test. Bead was characterized by FTIR and SEM. Alginate immobilized zeolit beads demonstrated significantly higher sorption efficacy compared to plain alginate beads and zeolite with 0.25 mmol CO2 adsorbed /g adsorbent. Optimum condition was achieved with mass composition of alginate:zeolite (3:1), flowrate 50 mL/min for 20 minutes. The alginate immobilized zeolit beads showed that adsorption of CO2 followed Freundlich isotherm and pseudo second order kinetic model. Adsorption of CO2 onto alginate immobilized zeolite beads is a physisorption with adsorption energy of 6.37 kJ/mol. This results indicates that the alginate immobilized zeolit beads can be used as promising adsorbents for CO2.

  19. Produção de alginato por microrganismos Alginate production by microorganisms

    Directory of Open Access Journals (Sweden)

    José Miguel Müller

    2011-01-01

    Full Text Available O alginato é um copolímero linear constituído de unidades de ácidos α-L-gulurônicos e β-D-manurônicos e é extensamente utilizado devido as suas propriedades espessantes, estabilizantes e gelificantes. Estas características fazem com que este biopolímero encontre aplicações na indústria de alimentos, na indústria têxtil e de papel, em cosméticos e na área farmacêutica e médica. Atualmente para este conjunto de aplicações sua principal fonte são algas marrons, entretanto, o alginato pode ser obtido a partir de biossíntese, utilizando-se microrganismos do gênero Pseudomonas e Azotobacter. A produção bacteriana de alginato apresenta-se como uma alternativa interessante e sua produção por microrganismos, além de possibilitar a produção de biopolímeros de alta qualidade com características específicas e pré-determinadas, irá diminuir o impacto ambiental nas regiões em que as algas marinhas das quais é extraído são coletadas. Nos últimos anos, vários estudos relacionados à produção de alginato por microrganismos foram realizados com o objetivo de avaliar sua produção e rota metabólica de biossíntese, para caracterizar o material produzido e para determinar as potencialidades de aplicação deste novo material. O rápido desenvolvimento de aplicações do alginato na área médica e farmacêutica, bem como a descoberta de propriedades imunológicas únicas deste material tem aumentado o interesse no desenvolvimento de processos para produzi-lo. Neste artigo são abordados aspectos relacionados à produção e as características do alginato bacteriano e também reportadas às potencialidades e aplicações inovadoras nas quais este material vem sendo utilizado.Alginate is a linear copolymer consisting of units of α-L-guluronic and β-D-mannuronic acid which is widely used due to its thickening, stabilizing and gelling properties. These characteristics mean that it has many applications in the food

  20. Functional Analysis of Genes for Biosynthesis of Pyocyanin and Phenazine-1-Carboxamide from Pseudomonas aeruginosa PAO1

    Science.gov (United States)

    Mavrodi, Dmitri V.; Bonsall, Robert F.; Delaney, Shannon M.; Soule, Marilyn J.; Phillips, Greg; Thomashow, Linda S.

    2001-01-01

    Two seven-gene phenazine biosynthetic loci were cloned from Pseudomonas aeruginosa PAO1. The operons, designated phzA1B1C1D1E1F1G1 and phzA2B2C2D2E2F2G2, are homologous to previously studied phenazine biosynthetic operons from Pseudomonas fluorescens and Pseudomonas aureofaciens. Functional studies of phenazine-nonproducing strains of fluorescent pseudomonads indicated that each of the biosynthetic operons from P. aeruginosa is sufficient for production of a single compound, phenazine-1-carboxylic acid (PCA). Subsequent conversion of PCA to pyocyanin is mediated in P. aeruginosa by two novel phenazine-modifying genes, phzM and phzS, which encode putative phenazine-specific methyltransferase and flavin-containing monooxygenase, respectively. Expression of phzS alone in Escherichia coli or in enzymes, pyocyanin-nonproducing P. fluorescens resulted in conversion of PCA to 1-hydroxyphenazine. P. aeruginosa with insertionally inactivated phzM or phzS developed pyocyanin-deficient phenotypes. A third phenazine-modifying gene, phzH, which has a homologue in Pseudomonas chlororaphis, also was identified and was shown to control synthesis of phenazine-1-carboxamide from PCA in P. aeruginosa PAO1. Our results suggest that there is a complex pyocyanin biosynthetic pathway in P. aeruginosa consisting of two core loci responsible for synthesis of PCA and three additional genes encoding unique enzymes involved in the conversion of PCA to pyocyanin, 1-hydroxyphenazine, and phenazine-1-carboxamide. PMID:11591691

  1. Glyphosate-Induced Specific and Widespread Perturbations in the Metabolome of Soil Pseudomonas Species

    Directory of Open Access Journals (Sweden)

    Ludmilla Aristilde

    2017-06-01

    Full Text Available Previous studies have reported adverse effects of glyphosate on crop-beneficial soil bacterial species, including several soil Pseudomonas species. Of particular interest is the elucidation of the metabolic consequences of glyphosate toxicity in these species. Here we investigated the growth and metabolic responses of soil Pseudomonas species grown on succinate, a common root exudate, and glyphosate at different concentrations. We conducted our experiments with one agricultural soil isolate, P. fluorescens RA12, and three model species, P. putida KT2440, P. putida S12, and P. protegens Pf-5. Our results demonstrated both species- and strain-dependent growth responses to glyphosate. Following exposure to a range of glyphosate concentrations (up to 5 mM, the growth rate of both P. protegens Pf-5 and P. fluorescens RA12 remained unchanged whereas the two P. putida strains exhibited from 0 to 100% growth inhibition. We employed a 13C-assisted metabolomics approach using liquid chromatography-mass spectrometry to monitor disruptions in metabolic homeostasis and fluxes. Profiling of the whole-cell metabolome captured deviations in metabolite levels involved in the tricarboxylic acid cycle, ribonucleotide biosynthesis, and protein biosynthesis. Altered metabolite levels specifically in the biosynthetic pathway of aromatic amino acids (AAs, the target of toxicity for glyphosate in plants, implied the same toxicity target in the soil bacterium. Kinetic flux experiments with 13C-labeled succinate revealed that biosynthetic fluxes of the aromatic AAs were not inhibited in P. fluorescens Pf-5 in the presence of low and high glyphosate doses but these fluxes were inhibited by up to 60% in P. putida KT2440, even at sub-lethal glyphosate exposure. Notably, the greatest inhibition was found for the aromatic AA tryptophan, an important precursor to secondary metabolites. When the growth medium was supplemented with aromatic AAs, P. putida S12 exposed to a lethal

  2. Alginate-polylysine-alginate microcapsules: effect of size reduction on capsule properties.

    Science.gov (United States)

    Strand, B L; Gåserød, O; Kulseng, B; Espevik, T; Skjåk-Baek, G

    2002-01-01

    Alginate-polylysine-alginate capsules containing insulin-producing cells have been used as a bio-artificial pancreas in the treatment of diabetes mellitus. In a search for microcapsules with improved diffusion characteristics, a high voltage system was developed that produces 250,000 beads/min with a diameter of 160 microm +/- 3-5%. The diameter of the beads could be varied between 160-700 microm depending on the needle diameter and construction, the voltage, the distance between the electrodes and the flow of alginate solution. Ca-alginate beads with diameters of 200 and 500 microm were produced by the high voltage electrostatic system. The 200 microm beads were sensitive to poly-L-lysine (PLL) exposure and had to be washed in ion-free solution to avoid collapse. The 200 microm beads swelled more than the 500 microm beads in the washing and PLL treatment. Also, the porosity of the capsules changed with size, but capsules impermeable to tumour necrosis factor (TNF) could be made by exchanging PLL with poly-D-lysine (PDL) for the 500 microm beads. The 200 microm beads were impermeable to IgG after PLL exposure. Islets of Langerhans were encapsulated in alginate-PLL-alginate capsules and evaluated by measuring protruding islets and insulin production. Islets in microcapsules made by the high voltage electrostatic system did not function differently from islets in larger microcapsules made by an air jet system. In conclusion, alginate capsules made by a high voltage electrostatic system enable large-scale production of small capsules with a narrow size distribution that can meet the functional properties of larger capsules by small changes in the encapsulation procedure.

  3. Falsirhodobacter sp. alg1 Harbors Single Homologs of Endo and Exo-Type Alginate Lyases Efficient for Alginate Depolymerization.

    Science.gov (United States)

    Mori, Tetsushi; Takahashi, Mami; Tanaka, Reiji; Miyake, Hideo; Shibata, Toshiyuki; Chow, Seinen; Kuroda, Kouichi; Ueda, Mitsuyoshi; Takeyama, Haruko

    2016-01-01

    Alginate-degrading bacteria play an important role in alginate degradation by harboring highly efficient and unique alginolytic genes. Although the general mechanism for alginate degradation by these bacteria is fairly understood, much is still required to fully exploit them. Here, we report the isolation of a novel strain, Falsirhodobacter sp. alg1, the first report for an alginate-degrading bacterium from the family Rhodobacteraceae. Genome sequencing reveals that strain alg1 harbors a primary alginate degradation pathway with only single homologs of an endo- and exo-type alginate lyase, AlyFRA and AlyFRB, which is uncommon among such bacteria. Subsequent functional analysis showed that both enzymes were extremely efficient to depolymerize alginate suggesting evolutionary interests in the acquirement of these enzymes. The exo-type alginate lyase, AlyFRB in particular could depolymerize alginate without producing intermediate products making it a highly efficient enzyme for the production of 4-deoxy-L-erythro-5-hexoseulose uronic acid (DEH). Based on our findings, we believe that the discovery of Falsirhodobacter sp. alg1 and its alginolytic genes hints at the potentiality of a more diverse and unique population of alginate-degrading bacteria.

  4. Sodium alginate and gum acacia hydrogels of ZnO nanoparticles show wound healing effect on fibroblast cells.

    Science.gov (United States)

    Raguvaran, R; Manuja, Balvinder K; Chopra, Meenu; Thakur, Rajesh; Anand, Taruna; Kalia, Anu; Manuja, Anju

    2017-03-01

    An ideal biomaterial for wound dressing applications should possess antibacterial and anti-inflammatory properties without any toxicity to the host cells while providing the maximum healing activity. Zinc oxide nanoparticles (ZnONPs) possess antimicrobial activity and enhance wound healing, but the questions regarding their safety arise before application to the biological systems. We synthesized ZnONPs-loaded-sodium alginate-gum acacia hydrogels (SAGA-ZnONPs) by cross linking hydroxyl groups of the polymers sodium alginate and gum acacia with the aldehyde group of gluteradehyde. Here, we report the wound healing properties of sodium alginate/gum acacia/ZnONPs, circumventing the toxicity of ZnONPs simultaneously. We demonstrated the concentration-dependent zones of inhibition in treated cultures of Pseudomonas aerigunosa and Bacillus cereus and biocompatability on peripheral blood mononuclear/fibroblast cells. SAGA-ZnONPs hydrogels showed a healing effect at a low concentration of ZnONPs using sheep fibroblast cells. Our findings suggest that high concentrations of ZnONPs were toxic to cells but SAGA-ZnONPs hydrogels significantly reduced the toxicity and preserved the beneficial antibacterial and healing effect. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Accelerated aerobic granulation using alternating feed loadings: alginate-like exopolysaccharides.

    Science.gov (United States)

    Yang, Ya-Chun; Liu, Xiang; Wan, Chunli; Sun, Supu; Lee, Duu-Jong

    2014-11-01

    Alginate-like exopolysaccharides (ALE) likely contribute markedly to strength of aerobic granules. This study cultivated aerobic granules from propionate wastewaters using strategies with different organic loading rates (OLRs) (4.4-17.4 kg/m(3)-d). When the OLR increased suddenly, the constituent cells (Pseudomonas, Clostridium, Thauera and Arthrobacter) were stimulated to secret extracellular cyclic diguanylate (c-di-GMP) and produced excess ALE, which formed a large quantity of sticky materials that served as the precursor of aerobic granules. Formation of excess ALE was the prerequisite for accelerated granulation. Conversely, this study observed no enrichment of poly guluronic acid blocks in ALE during granulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Diffusion Retardation by Binding of Tobramycin in an Alginate Biofilm Model

    DEFF Research Database (Denmark)

    Cao, Bao; Christophersen, Lars; Kolpen, Mette

    2016-01-01

    Microbial cells embedded in a self-produced extracellular biofilm matrix cause chronic infections, e. g. by Pseudomonas aeruginosa in the lungs of cystic fibrosis patients. The antibiotic killing of bacteria in biofilms is generally known to be reduced by 100–1000 times relative to planktonic...... to be uniformly distributed throughout the volume of the alginate bead. The power-law appears to be a consequence of binding to a multitude of different binding sites. In a diffusion model these results are shown to produce pronounced retardation of the penetration of tobramycin into the biofilm. This filtering...... of the free tobramycin concentration inside biofilm beads is expected to aid in augmenting the survival probability of bacteria residing in the biofilm....

  7. Structure-function relationship of flavoproteins : with special reference to p-hydroxybenzoate hydroxylase from Pseudomonas fluorescens

    NARCIS (Netherlands)

    Berkel, van W.J.H.

    1989-01-01

    In this thesis different studies probing the structurefunction relationship of some flavoproteins are dealt with. The attention has been focused on two central themes:
    The first part of the thesis deals with studies concerning the application of affinity

  8. Protozoan-induced regulation of cyclic lipopeptide biosynthesis Is an effective predation defense mechanism for Pseudomonas fluorescens

    NARCIS (Netherlands)

    Mazzola, M.; Bruijn, de I.; Cohen, M.F.; Raaijmakers, J.M.

    2009-01-01

    Environmental bacteria are exposed to a myriad of biotic interactions that influence their function and survival. The grazing activity of protozoan predators significantly impacts the dynamics, diversification, and evolution of bacterial communities in soil ecosystems. To evade protozoan predation,

  9. [Diagnostic value of alginate test in gastroesophageal reflux disease].

    Science.gov (United States)

    Bordin, D S; Masharova, A A; Droxzdov, V N; Firsova, L D; Kozhurina, T S

    2010-01-01

    To evaluate the diagnostic accuracy of single dose of gaviscon (the alginates test) in detecting gastroesophageal reflux disease (GERD) in patients with heartburn symptoms. 123 patients (male 46, female 77, age 43.6 +/- 15.5 years) with symptoms suggestive of GERD were investigated. Symptom response to the alginates test compared in GERD positive and GERD negative patients according traditional diagnostic criteria of GERD (upper endoscopy, 24-hr pH-monitoring, esophageal manometry, response to treatment with PPIs). Of 91 (78.9%) patients with positive alginates test, 87 were classified as GERD positive and 4 as GERD negative. Of 32 (26%) patients with negative alginates test, 29 were GERD negative and 3 GERD positive. The results providing a sensitivity of alginates test of 96.7% and a specificity of 87.7%. The alginates test is sensitive and specific for diagnosing GERD in patients with typical GERD symptoms.

  10. Radiation protection by ascorbic acid in sodium alginate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Aliste, A.J.; Mastro, N.L. Del [Center of Radiation Technology, IPEN/CNEN/SP, University City, 05508-000 Sao Paulo (Brazil)]. E-mail: ajaliste@ipen.br

    2004-07-01

    Alginates are gelling hydrocolloids extracted from brown seaweed used widely in the nourishing and pharmaceutical industries. As alginic acid gellification retard food entrance in the stomach alginate is an additive used in diets. The objective of this work was to study the protective action of the ascorbic acid in alginate solutions against the action of {sup 60} Co gamma radiation. One % (w/v) solutions of alginate had been used and concentrations of ascorbic acid varied from 0 to 2.5% (w/v). The solutions were irradiated with doses up to 10 kGy. Viscosity/dose relationship and the p H of the solutions at 25 Centigrade were determined. Ascorbic acid behaved as an antioxidant against radiation oxidative shock in this model system of an irradiated viscous solution. Besides its radiation protective role on alginate solutions ascorbic acid promoted a viscosity increase in the range of concentrations employed. (Author)

  11. Cytotoxicity, Bactericidal, and Antioxidant Activity of Sodium Alginate Hydrosols Treated with Direct Electric Current

    Directory of Open Access Journals (Sweden)

    Żaneta Król

    2017-03-01

    Full Text Available The aim of the study was to investigate the effect of using direct electric current (DC of 0, 200, and 400 mA for five minutes on the physiochemical properties, cytotoxicity, antibacterial, and antioxidant activity of sodium alginate hydrosols with different sodium chloride concentrations. The pH, oxidation-reduction potential (ORP, electrical conductivity (EC, and available chlorine concentration (ACC were measured. The effect of sodium alginate hydrosols treated with DC on Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Micrococcus luteus, Escherichia coli, Salmonella enteritidis, Yersinia enterocolitica, Pseudomonas fluorescence, and RAW 264.7 and L929 cells was investigated. Subsequently, the antioxidant properties of hydrosols were evaluated by determining the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH and ferric reducing antioxidant power (FRAP. The results have shown that after applying 400 mA in hydrosol samples with 0.1% and 0.2% NaCl all tested bacteria were inactivated. The ACC concentration of C400 samples with NaCl was equal to 13.95 and 19.71 mg/L, respectively. The cytotoxicity analysis revealed that optimized electric field conditions and the addition of sodium chloride allow for the avoidance of toxicity effects on normal cells without disturbing the antibacterial effects. Due to the presence of oxidizing substances, the DPPH of variants treated with DC was lower than the DPPH of control samples.

  12. Polyelectroylte complex composed of chitosan and sodium alginate for wound dressing application.

    Science.gov (United States)

    Kim, H J; Lee, H C; Oh, J S; Shin, B A; Oh, C S; Park, R D; Yang, K S; Cho, C S

    1999-01-01

    Drug-impregnated polyelectrolyte complex (PEC) sponge composed of chitosan and sodium alginate was prepared for wound dressing application. The morphological structure of this wound dressing was observed to be composed of a dense skin outer layer and a porous cross-section layer by scanning electron microscopy (SEM). Equilibrium water content and release of silver sulfadiazine (AgSD) could be controlled by the number of repeated in situ PEC reactions between chitosan and sodium alginate. The release of AgSD from AgSD-impregnated PEC wound dressing in PBS buffer (PH = 7.4) was dependent on the number of repeated in situ complex formations for the wound dressing. The antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. From the behavior of antimicrobial release and the suppression of bacterial proliferation, it is thought that the PEC wound dressing containing antimicrobial agents could protect the wound surfaces from bacterial invasion and effectively suppress bacterial proliferation. In the cytotoxicity test, cellular damage was reduced by the controlled released of AgSD from the sponge matrix of AgSD-medicated wound dressing. In vivo tests showed that granulation tissue formation and wound contraction for the AgSD plus dihydroepiandrosterone (DHEA) impregnated PEC wound dressing were faster than any other groups.

  13. Variations in Calcium and Alginate Ions Concentration in Relation to the Properties of Calcium Alginate Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hamed Daemi

    2013-05-01

    Full Text Available Alginate belongs to a group of natural polymers called polysaccharides. They have carboxylic functional groups beside hydroxyls which are common in all polysaccharides. These materials show interesting properties due to theirfunctional groups. One of these properties is the ability of this polymer as a suitable carrier of protecting and transferring drugs and biomolecules. The particle sizes of these polymers are very important for their applications, so different techniques were used for preparation of these materials. In this way polymeric nanoparticles of calcium alginate which are excellent carriers in drug delivery systems were prepared by addition of calcium chloride solution to dilute solution of sodium alginate. Investigation of the size and distribution of nanoparticles were analyzed by SEM method. The concentration effects of both alginate and calcium ions on the size and distribution of  nanoparticles were studied in this research. Results showed that the size of nanoparticles obviously decreased with decreasing polymeric alginate concentration because of lower active sites in polymer chain. On the other hand, thesize and distribution of nanoparticles are significantly improved with increase of calcium cation concentrations. The mean particle size 40-70 nm and spherical shape are the main characteristics of the prepared nanoparticles.

  14. Alginate Encapsulation of Human Hepatocytes and Assessment of Microbeads.

    Science.gov (United States)

    Mitry, Ragai R; Jitraruch, Suttiruk; Iansante, Valeria; Dhawan, Anil

    2017-01-01

    Alginate encapsulation of cells is an attractive technique in which alginate becomes polymerized entrapping the cells. The structure of formed microbeads/microcapsules is semipermeable as it allows oxygen and nutrients to go in, and waste products and other materials produced by the cells to go out. Here, we describe basic protocols for alginate encapsulation of human hepatocytes and methods for assessing the microbeads produced.

  15. PLGA/alginate composite microspheres for hydrophilic protein delivery.

    Science.gov (United States)

    Zhai, Peng; Chen, X B; Schreyer, David J

    2015-11-01

    Poly(lactic-co-glycolic acid) (PLGA) microspheres and PLGA/alginate composite microspheres were prepared by a novel double emulsion and solvent evaporation technique and loaded with bovine serum albumin (BSA) or rabbit anti-laminin antibody protein. The addition of alginate and the use of a surfactant during microsphere preparation increased the encapsulation efficiency and reduced the initial burst release of hydrophilic BSA. Confocal laser scanning microcopy (CLSM) of BSA-loaded PLGA/alginate composite microspheres showed that PLGA, alginate, and BSA were distributed throughout the depths of microspheres; no core/shell structure was observed. Scanning electron microscopy revealed that PLGA microspheres erode and degrade more quickly than PLGA/alginate composite microspheres. When loaded with anti-laminin antibody, the function of released antibody was well preserved in both PLGA and PLGA/alginate composite microspheres. The biocompatibility of PLGA and PLGA/alginate microspheres were examined using four types of cultured cell lines, representing different tissue types. Cell survival was variably affected by the inclusion of alginate in composite microspheres, possibly due to the sensitivity of different cell types to excess calcium that may be released from the calcium cross-linked alginate. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Versatile click alginate hydrogels crosslinked via tetrazine-norbornene chemistry.

    Science.gov (United States)

    Desai, Rajiv M; Koshy, Sandeep T; Hilderbrand, Scott A; Mooney, David J; Joshi, Neel S

    2015-05-01

    Alginate hydrogels are well-characterized, biologically inert materials that are used in many biomedical applications for the delivery of drugs, proteins, and cells. Unfortunately, canonical covalently crosslinked alginate hydrogels are formed using chemical strategies that can be biologically harmful due to their lack of chemoselectivity. In this work we introduce tetrazine and norbornene groups to alginate polymer chains and subsequently form covalently crosslinked click alginate hydrogels capable of encapsulating cells without damaging them. The rapid, bioorthogonal, and specific click reaction is irreversible and allows for easy incorporation of cells with high post-encapsulation viability. The swelling and mechanical properties of the click alginate hydrogel can be tuned via the total polymer concentration and the stoichiometric ratio of the complementary click functional groups. The click alginate hydrogel can be modified after gelation to display cell adhesion peptides for 2D cell culture using thiol-ene chemistry. Furthermore, click alginate hydrogels are minimally inflammatory, maintain structural integrity over several months, and reject cell infiltration when injected subcutaneously in mice. Click alginate hydrogels combine the numerous benefits of alginate hydrogels with powerful bioorthogonal click chemistry for use in tissue engineering applications involving the stable encapsulation or delivery of cells or bioactive molecules. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Microencapsulation of probiotics using sodium alginate

    Directory of Open Access Journals (Sweden)

    Mariana de Araújo Etchepare

    2015-07-01

    Full Text Available The consumption of probiotics is constantly growing due to the numerous benefits conferred on the health of consumers. In this context, Microencapsulation is a technology that favors the viability of probiotic cultures in food products, mainly by the properties of protection against adverse environmental conditions and controlled release. Currently there are different procedures for microencapsulation using polymers of various types of natural and synthetic origin. The use of sodium alginate polymers is one of the largest potential application in the encapsulation of probiotics because of their versatility, biocompatibility and toxicity exemption. The aim of this review is to present viable encapsulation techniques of probiotics with alginate, emphasizing the internal ionic gelation and external ionic gelation, with the possibility of applying, as well as promising for improving these techniques.

  18. Amphiphilic Alginates for Marine Antifouling Applications.

    Science.gov (United States)

    Jakobi, Victoria; Schwarze, Jana; Finlay, John A; Nolte, Kim A; Spöllmann, Stephan; Becker, Hans-Werner; Clare, Anthony S; Rosenhahn, Axel

    2018-02-12

    Amphiphilic polymers are promising candidates for novel fouling-release coatings for marine applications. We grafted amphiphilic alginates with fluorinated side chains to glass and silicon substrates and characterized the obtained films by contact angle goniometry, spectroscopic ellipsometry, XPS, and ATR-FTIR. The potential to inhibit protein attachment was tested against four different proteins, and intermediate fluorine loadings showed the strongest reduction with respect to hydrophobic, aliphatic controls. A similar trend was observed in dynamic attachment experiments using Navicula perminuta diatoms and settlement experiments with zoospores of the green algae Ulva linza. The results indicate that amphiphilic alginates are promising natural and renewable biomacromolecules that could be included in future protective coating technologies.

  19. Covalent stabilization of alginate hydrogel beads via Staudinger ligation: Assessment of poly(ethylene glycol) and alginate cross-linkers

    OpenAIRE

    Gattás-Asfura, Kerim M.; Fraker, Christopher A.; Stabler, Cherie L.

    2011-01-01

    Cellular encapsulation within alginate hydrogel capsules has broad applications in tissue engineering. In seeking to improve the inherent instability of ionically cross-linked alginate hydrogels, we previously demonstrated the covalent stabilization of Ba2+ cross-linked alginate-azide beads via chemoselective Staudinger ligation using a 1-methyl-2-diphenylphosphino-terephthalate (MDT) terminated poly(ethylene glycol) linker. In this study, we functionalized variant PEG, linear and branched, a...

  20. Alginate-Collagen Fibril Composite Hydrogel

    Directory of Open Access Journals (Sweden)

    Mahmoud Baniasadi

    2015-02-01

    Full Text Available We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

  1. Pseudomonas cichorii as the causal agent of midrib rot, an emerging disease of greenhouse-grown butterhead lettuce in Flanders.

    Science.gov (United States)

    Cottyn, Bart; Heylen, Kim; Heyrman, Jeroen; Vanhouteghem, Katrien; Pauwelyn, Ellen; Bleyaert, Peter; Van Vaerenbergh, Johan; Höfte, Monica; De Vos, Paul; Maes, Martine

    2009-05-01

    Bacterial midrib rot of greenhouse-grown butterhead lettuce (Lactuca sativa L. var. capitata) is an emerging disease in Flanders (Belgium) and fluorescent pseudomonads are suspected to play an important role in the disease. Isolations from infected lettuces, collected from 14 commercial greenhouses in Flanders, yielded 149 isolates that were characterized polyphasically, which included morphological characteristics, pigmentation, pathogenicity tests by both injection and spraying of lettuce, LOPAT characteristics, FAME analysis, BOX-PCR fingerprinting, 16S rRNA and rpoB gene sequencing, as well as DNA-DNA hybridization. Ninety-eight isolates (66%) exhibited a fluorescent pigmentation and were associated with the genus Pseudomonas. Fifty-five of them induced an HR+ (hypersensitive reaction in tobacco leaves) response. The other 43 fluorescent isolates were most probably saprophytic bacteria and about half of them were able to cause rot on potato tuber slices. BOX-PCR genomic fingerprinting was used to assess the genetic diversity of the Pseudomonas midrib rot isolates. The delineated BOX-PCR patterns matched quite well with Pseudomonas morphotypes defined on the basis of colony appearance and variation in fluorescent pigmentation. 16S rRNA and rpoB gene sequence analyses allowed most of the fluorescent isolates to be allocated to Pseudomonas, and they belonged to either the Pseudomonas fluorescens group, Pseudomonas putida group, or the Pseudomonas cichorii/syringae group. In particular, the isolates allocated to this latter group constituted the vast majority of HR+ isolates and were identified as P. cichorii by DNA-DNA hybridization. They were demonstrated by spray-inoculation tests on greenhouse-grown lettuce to induce the midrib rot disease and could be re-isolated from lesions of inoculated plants. Four HR+ non-fluorescent isolates associated with one sample that showed an atypical midrib rot were identified as Dickeya sp.

  2. Organic acid production in vitro and plant growth promotion in maize under controlled environment by phosphate-solubilizing fluorescent Pseudomonas

    Directory of Open Access Journals (Sweden)

    Vyas Pratibha

    2009-08-01

    Full Text Available Abstract Background Phosphorus deficiency is a major constraint to crop production due to rapid binding of the applied phosphorus into fixed forms not available to the plants. Microbial solubilization of inorganic phosphates has been attributed mainly to the production of organic acids. Phosphate-solubilizing microorganisms enhance plant growth under conditions of poor phosphorus availability by solubilizing insoluble phosphates in the soil. This paper describes the production of organic acids during inorganic phosphate solubilization and influence on plant growth as a function of phosphate solubilization by fluorescent Pseudomonas. Results Nineteen phosphate-solubilizing fluorescent Pseudomonas strains of P. fluorescens, P. poae, P. trivialis, and Pseudomonas spp. produced gluconic acid, oxalic acid, 2-ketogluconic acid, lactic acid, succinic acid, formic acid, citric acid and malic acid in the culture filtrates during the solubilization of tricalcium phosphate, Mussoorie rock phosphate, Udaipur rock phosphate and North Carolina rock phosphate. The strains differed quantitatively and qualitatively in the production of organic acids during solubilization of phosphate substrates. Cluster analysis based on organic acid profiling revealed inter-species and intra-species variation in organic acids produced by Pseudomonas strains. The phosphate-solubilizing bacterial treatments P. trivialis BIHB 745, P. trivialis BIHB 747, Pseudomonas sp. BIHB 756 and P. poae BIHB 808 resulted in significantly higher or statistically at par growth and total N, P and K content over single super phosphate treatment in maize. These treatments also significantly affected pH, organic matter, and N, P, and K content of the soil. Conclusion The results implied that organic acid production by Pseudomonas strains is independent of their genetic relatedness and each strain has its own ability of producing organic acids during the solubilization of inorganic phosphates

  3. Organic acid production in vitro and plant growth promotion in maize under controlled environment by phosphate-solubilizing fluorescent Pseudomonas.

    Science.gov (United States)

    Vyas, Pratibha; Gulati, Arvind

    2009-08-22

    Phosphorus deficiency is a major constraint to crop production due to rapid binding of the applied phosphorus into fixed forms not available to the plants. Microbial solubilization of inorganic phosphates has been attributed mainly to the production of organic acids. Phosphate-solubilizing microorganisms enhance plant growth under conditions of poor phosphorus availability by solubilizing insoluble phosphates in the soil. This paper describes the production of organic acids during inorganic phosphate solubilization and influence on plant growth as a function of phosphate solubilization by fluorescent Pseudomonas. Nineteen phosphate-solubilizing fluorescent Pseudomonas strains of P. fluorescens, P. poae, P. trivialis, and Pseudomonas spp. produced gluconic acid, oxalic acid, 2-ketogluconic acid, lactic acid, succinic acid, formic acid, citric acid and malic acid in the culture filtrates during the solubilization of tricalcium phosphate, Mussoorie rock phosphate, Udaipur rock phosphate and North Carolina rock phosphate. The strains differed quantitatively and qualitatively in the production of organic acids during solubilization of phosphate substrates. Cluster analysis based on organic acid profiling revealed inter-species and intra-species variation in organic acids produced by Pseudomonas strains. The phosphate-solubilizing bacterial treatments P. trivialis BIHB 745, P. trivialis BIHB 747, Pseudomonas sp. BIHB 756 and P. poae BIHB 808 resulted in significantly higher or statistically at par growth and total N, P and K content over single super phosphate treatment in maize. These treatments also significantly affected pH, organic matter, and N, P, and K content of the soil. The results implied that organic acid production by Pseudomonas strains is independent of their genetic relatedness and each strain has its own ability of producing organic acids during the solubilization of inorganic phosphates. Significant difference in plant growth promotion by efficient

  4. Arsenic-contaminated soils. Genetically modified Pseudomonas spp. and their arsenic-phytoremediation potential

    Energy Technology Data Exchange (ETDEWEB)

    Sizova, O.I.; Kochetkov, V.V.; Validov, S.Z.; Boronin, A.M. [Inst. of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Moscow (Russian Federation); Kosterin, P.V.; Lyubun, Y.V. [Inst. of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov (Russian Federation)

    2002-07-01

    Sorghum was inoculated with Pseudomonas bacteria, including strains harboring an As-resistance plasmid, pBS3031, to enhance As-extraction by the plants. Pseudomonas strains (P. fluorescens 38a, P. putida 53a, and P. aureofaciens BS1393) were chosen because they are antagonistic to a wide range of phytopathogenic fungi and bacteria, and they can stimulate plant growth. The resistance of natural rhizospheric pseudomonads to sodium arsenite was assessed. Genetically modified Pseudomonas strains resistant to As(III)/As(V) were obtained via conjugation or transformation. The effects of the strains on the growth of sorghum on sodium-arsenite-containing soils were assessed. The conclusions from this study are: (1) It is possible to increase the survivability of sorghum growing in sodium-arsenite-containing soil by using rhizosphere pseudomonads. (2) The presence of pBS3031 offers the strains a certain selective advantage in arsenite-contaminated soil. (3) The presence of pBS3031 impairs plant growth, due to the As-resistance mechanism determined by this plasmid: the transformation of the less toxic arsenate into the more toxic, plant-root-available arsenite by arsenate reductase and the active removal of arsenite from bacterial cells. (4) Such a mechanism makes it possible to develop a bacteria-assisted phytoremediation technology for the cleanup of As-contaminated soils and is the only possible way of removing the soil-sorbed arsenates from the environment. (orig.)

  5. Virulence Attributes and Host Response Assays for Determining Pathogenic Potential of Pseudomonas Strains Used in Biotechnology.

    Directory of Open Access Journals (Sweden)

    Azam F Tayabali

    Full Text Available Pseudomonas species are opportunistically pathogenic to humans, yet closely related species are used in biotechnology applications. In order to screen for the pathogenic potential of strains considered for biotechnology applications, several Pseudomonas strains (P.aeruginosa (Pa, P.fluorescens (Pf, P.putida (Pp, P.stutzeri (Ps were compared using functional virulence and toxicity assays. Most Pa strains and Ps grew at temperatures between 28°C and 42°C. However, Pf and Pp strains were the most antibiotic resistant, with ciprofloxacin and colistin being the most effective of those tested. No strain was haemolytic on sheep blood agar. Almost all Pa, but not other test strains, produced a pyocyanin-like chromophore, and caused cytotoxicity towards cultured human HT29 cells. Murine endotracheal exposures indicated that the laboratory reference strain, PAO1, was most persistent in the lungs. Only Pa strains induced pro-inflammatory and inflammatory responses, as measured by elevated cytokines and pulmonary Gr-1 -positive cells. Serum amyloid A was elevated at ≥ 48 h post-exposure by only some Pa strains. No relationship was observed between strains and levels of peripheral leukocytes. The species designation or isolation source may not accurately reflect pathogenic potential, since the clinical strain Pa10752 was relatively nonvirulent, but the industrial strain Pa31480 showed comparable virulence to PAO1. Functional assays involving microbial growth, cytotoxicity and murine immunological responses may be most useful for identifying problematic Pseudomonas strains being considered for biotechnology applications.

  6. The complete genome sequence of the plant growth-promoting bacterium Pseudomonas sp. UW4.

    Directory of Open Access Journals (Sweden)

    Jin Duan

    Full Text Available The plant growth-promoting bacterium (PGPB Pseudomonas sp. UW4, previously isolated from the rhizosphere of common reeds growing on the campus of the University of Waterloo, promotes plant growth in the presence of different environmental stresses, such as flooding, high concentrations of salt, cold, heavy metals, drought and phytopathogens. In this work, the genome sequence of UW4 was obtained by pyrosequencing and the gaps between the contigs were closed by directed PCR. The P. sp. UW4 genome contains a single circular chromosome that is 6,183,388 bp with a 60.05% G+C content. The bacterial genome contains 5,423 predicted protein-coding sequences that occupy 87.2% of the genome. Nineteen genomic islands (GIs were predicted and thirty one complete putative insertion sequences were identified. Genes potentially involved in plant growth promotion such as indole-3-acetic acid (IAA biosynthesis, trehalose production, siderophore production, acetoin synthesis, and phosphate solubilization were determined. Moreover, genes that contribute to the environmental fitness of UW4 were also observed including genes responsible for heavy metal resistance such as nickel, copper, cadmium, zinc, molybdate, cobalt, arsenate, and chromate. Whole-genome comparison with other completely sequenced Pseudomonas strains and phylogeny of four concatenated "housekeeping" genes (16S rRNA, gyrB, rpoB and rpoD of 128 Pseudomonas strains revealed that UW4 belongs to the fluorescens group, jessenii subgroup.

  7. Commensal Pseudomonas Species Isolated from Wastewater and Freshwater Milieus in the Eastern Cape Province, South Africa, as Reservoir of Antibiotic Resistant Determinants

    Directory of Open Access Journals (Sweden)

    Anthony I. Okoh

    2012-07-01

    Full Text Available Pseudomonas species are opportunistic pathogens with implications in a wide range of diseases including cystic fibrosis and sickle cell anaemia. Because of their status as multidrug resistant (MDR and extremely drug resistant (XDR bacteria Pseudomonas species represent a threat to public health. Prevalence, antibiogram and associated antibiotic resistant genes of Pseudomonas species isolated from freshwater and mixed liquor environments in the Eastern Cape Province of South Africa were assessed. Polymerase chain reaction (PCR based technique was used to identify the isolates and screen for antibiotic resistant genes. The result shows occurrence of Pseudomonas spp. in freshwater and mixed liquor as follows: 71.42% and 37.5% (P. putida, 14.28% and 31.25% (P. flourescens, 7.14% and 6.25% (P. aeruginosa and 7.14% and 25% for other Pseudomonas species respectively. Disk diffusion antibiogram of the Pseudomonas isolates from the two locations showed 100% resistance to penicillin, oxacillin, clindamycin, rifampicin and 100% susceptibility to ciprofloxacin and gentamicin with varied percentage resistances to cephalothin, nalidixic acid, tetracycline, and ampicillin. The blaTEM antibiotic resistant gene was detected in 12.5% of P. putida, 57.14% of P. fluorescens, 100% P. aeruginosa and 40% in other Pseudomonas species. Similarly, Integrons conserved segment were detected in 12.5% of P. putida, 57.14% of P. fluorescens, 100% of P. aeruginosa and 40% of other Pseudomonas species. The presence of blaTEM gene and integrons conserved segment in some of the isolates is worrisome and suggest Pseudomonas species as important reservoirs of multidrug resistance genes in the Eastern Cape Province environment.

  8. The compartmented alginate fibres optimisation for bitumen rejuvenator encapsulation

    NARCIS (Netherlands)

    Tabaković, Amir; Copuroglu, O.; Post, W.; Garcia Espallargas, Santiago J.; Schlangen, H.E.J.G.

    2017-01-01

    This article presents development of a novel self-healing technology for asphalt pavements, where asphalt binder rejuvenator is encapsulated within the compartmented alginate fibres. The key objective of the study was to optimise the compartmented alginate fibre design, i.e., maximising amount of

  9. Comparison Of The Dimensional Stability Of Alginate Impressions ...

    African Journals Online (AJOL)

    Objective: To determine and compare the dimensional stability of alginate impressions disinfected with Sodium hypochlorite using the spray and immersion methods. Methodology: Alginate impressions of a master model of truncated metal cones were made and disinfected with 1% sodium hypochlorite constituted from ...

  10. Alginate Nanospheres Prepared by Internal or External Gelation with Nanoparticles

    NARCIS (Netherlands)

    Paques, J.P.

    2015-01-01

    Alginate is a biodegradable polymer that can be used for the formation of nanospheres with applications in food, biomedicine, and biotechnology. Alginate gels in mild conditions, and does not require organic solvents for the formation of nanospheres. This makes them ideal for entrapment of sensitive

  11. Properties of advanced (reduced) graphene oxide-alginate biopolymer films

    NARCIS (Netherlands)

    Vilcinskas, K.

    2016-01-01

    In this work, properties of Calcium alginate-reduced graphene oxide and Barium alginate‐reduced graphene oxide composite films are explored. In addition, the properties of the divalent metal ion-cross-linked alginate composite films are compared to the analogous properties of uncross‐linked Sodium

  12. A Controlled Drug-Delivery Experiment Using Alginate Beads

    Science.gov (United States)

    Farrell, Stephanie; Vernengo, Jennifer

    2012-01-01

    This paper describes a simple, cost-effective experiment which introduces students to drug delivery and modeling using alginate beads. Students produce calcium alginate beads loaded with drug and measure the rate of release from the beads for systems having different stir rates, geometries, extents of cross-linking, and drug molecular weight.…

  13. Alginate derivatization: a review of chemistry, properties and applications.

    Science.gov (United States)

    Pawar, Siddhesh N; Edgar, Kevin J

    2012-04-01

    Alginates have become an extremely important family of polysaccharides because of their utility in preparing hydrogels at mild pH and temperature conditions, suitable for sensitive biomolecules like proteins and nucleic acids, and even for living cells such as islets of Langerhans. In addition, the complex monosaccharide sequences of alginates, and our growing ability to create controlled sequences by the action of isolated epimerases upon the alginate precursor poly(mannuronic acid), create remarkable opportunities for understanding the relationship of properties to sequence in natural alginates (control of monosaccharide sequence being perhaps the greatest synthetic challenge in polysaccharide chemistry). There is however a trend in recent years to create "value-added" alginates, by performing derivatization reactions on the polysaccharide backbone. For example, chemical derivatization may enable alginates to achieve enhanced hydroxyapatite (HAP) nucleation and growth, heparin-like anticoagulation properties, improved cell-surface interactions, degradability, or tuning of the hydrophobic-hydrophilic balance for optimum drug release. The creation of synthetic derivatives therefore has the potential to empower the next generation of applications for alginates. Herein we review progress towards controlled synthesis of alginate derivatives, and the properties and applications of these derivatives. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. A novel wound dressing material—fibrin–chitosan–sodium alginate ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 35; Issue 7. A novel wound dressing material — fibrin–chitosan–sodium alginate composite sheet ... FTIR spectrum confirmed the interaction between amino groups of chitosan, fibrin and sodium alginate and SEM studies revealed composite nature of the material.

  15. 21 CFR 172.858 - Propylene glycol alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Propylene glycol alginate. 172.858 Section 172.858... CONSUMPTION Multipurpose Additives § 172.858 Propylene glycol alginate. The food additive propylene glycol... information required by the act: (1) The name of the additive, “propylene glycol alginate” or “propylene...

  16. Composition dependent properties of graphene (oxide)-alginate biopolymer nanocomposites

    NARCIS (Netherlands)

    Vilcinskas, K.; Jansen, K.M.B.; Mulder, F.M.; Picken, S.J.; Koper, G.J.M.

    2016-01-01

    We report on the thermal, electrical, and mechanical properties of alginate biopolymer nanocomposites prepared by solution casting with various amounts of graphene oxide (GO) or reduced GO (rGO). Our data shows that the thermal stability of alginate nanocomposites can be improved by the

  17. Alginate-based hybrid aerogel microparticles for mucosal drug delivery.

    Science.gov (United States)

    Gonçalves, V S S; Gurikov, P; Poejo, J; Matias, A A; Heinrich, S; Duarte, C M M; Smirnova, I

    2016-10-01

    The application of biopolymer aerogels as drug delivery systems (DDS) has gained increased interest during the last decade since these structures have large surface area and accessible pores allowing for high drug loadings. Being biocompatible, biodegradable and presenting low toxicity, polysaccharide-based aerogels are an attractive carrier to be applied in pharmaceutical industry. Moreover, some polysaccharides (e.g. alginate and chitosan) present mucoadhesive properties, an important feature for mucosal drug delivery. This feature allows to extend the contact of DDS with biological membranes, thereby increasing the absorption of drugs through the mucosa. Alginate-based hybrid aerogels in the form of microparticles (aerogel microparticles were obtained for alginate, hybrid alginate/pectin and alginate/κ-carrageenan aerogels, presenting high specific surface area (370-548m(2)g(-1)) and mucoadhesive properties. The microparticles were loaded with ketoprofen via adsorption from its solution in sc-CO2, and with quercetin via supercritical anti-solvent precipitation. Loading of ketoprofen was in the range between 17 and 22wt% whereas quercetin demonstrated loadings of 3.1-5.4wt%. Both the drugs were present in amorphous state. Loading procedure allowed the preservation of antioxidant activity of quercetin. Release of both drugs from alginate/κ-carrageenan aerogel was slightly faster compared to alginate/pectin. The results indicate that alginate-based aerogel microparticles can be viewed as promising matrices for mucosal drug delivery applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Applications of Alginate-Based Bioinks in 3D Bioprinting

    Science.gov (United States)

    Axpe, Eneko; Oyen, Michelle L.

    2016-01-01

    Three-dimensional (3D) bioprinting is on the cusp of permitting the direct fabrication of artificial living tissue. Multicellular building blocks (bioinks) are dispensed layer by layer and scaled for the target construct. However, only a few materials are able to fulfill the considerable requirements for suitable bioink formulation, a critical component of efficient 3D bioprinting. Alginate, a naturally occurring polysaccharide, is clearly the most commonly employed material in current bioinks. Here, we discuss the benefits and disadvantages of the use of alginate in 3D bioprinting by summarizing the most recent studies that used alginate for printing vascular tissue, bone and cartilage. In addition, other breakthroughs in the use of alginate in bioprinting are discussed, including strategies to improve its structural and degradation characteristics. In this review, we organize the available literature in order to inspire and accelerate novel alginate-based bioink formulations with enhanced properties for future applications in basic research, drug screening and regenerative medicine. PMID:27898010

  19. [PROGRESS OF ALGINATE DERIVATIVES BASED ON BIOMEDICAL MATERIALS].

    Science.gov (United States)

    Wei, Xiaojuan; Gu, Qisheng; Wang, Qingsheng; Xiao, Jimin

    2015-04-01

    To summarize the current research status of alginate derivatives based on biomedical materials, and analyze several key points as novel clinical products. The general preparation and application methods of alginate derivatives based on biomedical materials at home and abroad were reviewed. The present status and problems were analyzed. The derivation methods to prepare alginate derivatives include crosslink, sulfation, biological factors derivatization, hydrophobic modification, and graft copolymerization. With excellent bionic performance of structure and properties, many alginate derivatives are available for tissue engineering scaffolds, artificial organs, and drug delivery systems etc. However, more systematic applied basic research data should be collected and statistically analyzed for risk managements. Alginate derivatives have good feasibility as novel medical products, meanwhile, systematic evaluation and verification should be executed for their safety, effectiveness, and suitability.

  20. Synthesis and antimicrobial properties of Zn-mineralized alginate nanocomposites.

    Science.gov (United States)

    Malagurski, Ivana; Levic, Steva; Pantic, Milena; Matijasevic, Danka; Mitric, Miodrag; Pavlovic, Vladimir; Dimitrijevic-Brankovic, Suzana

    2017-06-01

    New bioactive and antimicrobial biomaterials were produced by alginate-mediated biomineralization with Zn-mineral phase. The synthesis procedure is simple, cost-effective and resulted in two different Zn-mineralized alginate nanocomposites, Zn-carbonate/Zn-alginate and Zn-phosphate/Zn-alginate. The presence of Zn-mineral phase and its type, have significantly affected nanocomposite morphology, stability, total metallic loading and potential to release Zn(II) in physiological environment. Antimicrobial experiments showed that both types of Zn-mineralized nanocomposites exhibit strong antimicrobial effect against Escherichia coli, Staphylococcus aureus and Candida albicans. These results suggest that alginate biomineralization, where minerals are salts of essential metallic ions like Zn(II), represents a good strategy for designing multifunctional biomaterials for potential biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. One Pot Synthesis and Characterization of Alginate Stabilized Semiconductor Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sundarrajan, Parani; Eswaran, Prabakaran; Marimuthu, Alexander; Subhadra, Lakshmi Baddireddi; Kannaiyan, Pandian [Univ., of Madras, Chennai (India)

    2012-10-15

    Uniform and well dispersed metal sulfide semiconductor nanoparticles incorporated into matrices of alginate biopolymer are prepared by using a facile in situ method. The reaction was accomplished by impregnation of alginate with divalent metal ions followed by reaction with thioacetamide. XRD analysis showed that the nanoparticles incorporated in the polymer matrix were of cubic structure with the average particle diameter of 1.8 to 4.8 nm. Field emission scanning electron microscopy and high resolution transmission electron microscopy images indicated that the particles were well dispersed and distributed uniformly in the matrices of alginate polymer. FT-IR spectra confirmed the presence of alginate in the nanocomposite. The crystalline nature and thermal stability of the alginate polymer was found to be influenced by the nature of the divalent metal ions used for the synthesis. The proposed method is considered to be a simple and greener approach for large scale synthesis of uniform sized nanoparticles.

  2. Biodegradable Nanocomposite Films Based on Sodium Alginate and Cellulose Nanofibrils

    Directory of Open Access Journals (Sweden)

    B. Deepa

    2016-01-01

    Full Text Available Biodegradable nanocomposite films were prepared by incorporation of cellulose nanofibrils (CNF into alginate biopolymer using the solution casting method. The effects of CNF content (2.5, 5, 7.5, 10 and 15 wt % on mechanical, biodegradability and swelling behavior of the nanocomposite films were determined. The results showed that the tensile modulus value of the nanocomposite films increased from 308 to 1403 MPa with increasing CNF content from 0% to 10%; however, it decreased with further increase of the filler content. Incorporation of CNF also significantly reduced the swelling percentage and water solubility of alginate-based films, with the lower values found for 10 wt % in CNF. Biodegradation studies of the films in soil confirmed that the biodegradation time of alginate/CNF films greatly depends on the CNF content. The results evidence that the stronger intermolecular interaction and molecular compatibility between alginate and CNF components was at 10 wt % in CNF alginate films.

  3. Population Structure of Pseudomonas aeruginosa

    National Research Council Canada - National Science Library

    Lutz Wiehlmann; Gerd Wagner; Nina Cramer; Benny Siebert; Peter Gudowius; Gracia Morales; Thilo Köhler; Christian van Delden; Christian Weinel; Peter Slickers; Burkhard Tümmler

    2007-01-01

    The metabolically versatile Gram-negative bacterium Pseudomonas aeruginosa inhabits terrestrial, aquatic, animal-, human-, and plant-host-associated environments and is an important causative agent...

  4. Preparation and Biochemical Property of Penicillin G Amidase-Loaded Alginate and Alginate/Chitosan Hydrogel Beads.

    Science.gov (United States)

    Nupur, Neh; Ashish, EmptyYN Y; Debnath, Mira

    2016-01-01

    Penicillin G amidase (PGA) (EC 3.5.1.11) are enzymes that are mainly involved in the synthesis of semi-synthetic }-lactam antibiotics. Soluble PGA is costly and lacks long term operational stability. We revised most of the patents related to Penicillin G amidase (PGA) immobilization in the section "Recent Patents on Immobilized Penicillin G Amidase". The aim of this work was to study comparative biochemical property of PGA enzyme immobilized in two hydro-gel beads - Ca-alginate and alginate+chitosan hybrid and morphologically characterised by SEM. PGA immobilized in alginate+chitosan hybrid bead shows high pH and thermal stability. Km, Vmax and Effectiveness factor (1) value of free PGA were 56.19 mg/ml, 1.786 U/ml and 1, respectively. These parameters for PGA immobilized alginate beads were 64.84 mg/ml, 0.781U/ml and 0.437, respectively and for PGA immobilized alginate+chitosan hybrid beads were 87.08 mg/ml, 0.622 U/ml and 0.348, respectively. Immobilized PGA on alginate+chitosan hybrid beads gave the highest thermal stability, reusability and storage stability than alginate immobilized PGA. The entrapment of PGA on alginate+chitosan hybrid beads revealed several advantages and could be used in 6APA (6- aminopenicillanic acid) production.

  5. Comparison of some biochemical properties of artichoke polyphenol oxidase entrapped in alginate-carrageenan and alginate gels.

    Science.gov (United States)

    Yagar, Hulya; Kocaturk, Selin

    2014-08-01

    Polyphenol oxidase (PPO, EC.1.14.18.1) isolated from artichoke (Cynara scolymus) was entrapped within alginate and alginate+ carrageenan beads, and the catecholase and cresolase activities of both entrapped enzymes were determined. Some properties of these immobilized enzymes such as optimum pH and temperature, kinetic parameters (Km and Vmax), thermal, and storage stability were determined and compared to each other. The highest catecholase activity was observed in alginate gel (370 U/g bead) while the highest cresolase activity was in alginate+ carrageenan gel (90 U/g bead). For catecholase and cresolase activities, optimum pHs of alginate and alginate+ carrageenan beads were determined to be 7.0 and 4.0, respectively. Optimum temperatures for catecholase activity were determined to be 40°C for both entrapped enzymes. These values for cresolase activity were 30°C and 20°C, respectively. Immobilized artichoke PPOs greatly preserved their thermal stability which exists anyway. The catalytic efficiency value (Vmax/Km) of the alginate beads is approximately high as two-and-a-half folds of that of alginate+κ-carrageenan beads for cresolase activity. These values were very close for catecholase activity. Immobilized beads saved their both activities after 30 days of storage at 4°C.

  6. Adhesion of nonmotile Pseudomonas aeruginosa on "soft" polyelectrolyte layer in a radial stagnation point flow system: measurements and model predictions.

    Science.gov (United States)

    de Kerchove, Alexis J; Weroński, Paweł; Elimelech, Menachem

    2007-11-20

    Prediction of bacterial deposition rates onto substrates in natural aquatic systems is quite challenging because of the inherent complexity of such systems. In this study, we compare experimental deposition kinetics of nonmotile bacteria (Pseudomonas aeruginosa) on an alginate-coated substrate in a radial stagnation point flow (RSPF) system to predictions based on DLVO theory. The "softness" of the surface layer of the bacteria and alginate-coated substrate was considered in the calculations of their electrokinetic surface properties, and the relevance of both the classical zeta potential and the outer surface potential as surrogates for surface potential was investigated. Independent of the used electrical potentials, we showed that significant discrepancies exist between theory and experiments. Analysis of microscopic images in the RSPF system has demonstrated, for the first time, that irreversible deposition of particles or cells entrapped in the secondary energy minimum can occur on the alginate layer, despite the hydrodynamic forces resulting from the radial flow in the RSPF system. It is suggested that polymeric structures associated with the surface of the particle/cell and the alginate-coated substrate are responsible for the transition between the secondary minimum and primary energy well. This mode of deposition is likely to be important in the deposition of microorganisms in complex aquatic systems.

  7. Sorbsan calcium alginate fibre dressings in footcare.

    Science.gov (United States)

    Fraser, R; Gilchrist, T

    1983-07-01

    This report outlines the successful application of Sorbsan-calcium alginate fibre dressings in footcare. This biomaterial has been found in clinical trials to have quite outstanding merit and can be used for sinus drainage and in the treatment of fissures, hypergranulation tissue, interdigital maceration, heloma molle and other lesions. Sorbsan bonds with and aids natural healing scabs and effects drainage of moist sites thus assisting in creating an environment conducive to the healing process. Similar promise has been demonstrated for this material in ongoing trials in hospitals in Sunderland where Sorbsan has been used effectively in the treatment of diabetic and trophic ulcers.

  8. Synthesis and evaluation of dual crosslinked alginate microbeads.

    Science.gov (United States)

    Somo, Sami I; Langert, Kelly; Yang, Chin-Yu; Vaicik, Marcella K; Ibarra, Veronica; Appel, Alyssa A; Akar, Banu; Cheng, Ming-Huei; Brey, Eric M

    2018-01-01

    Alginate hydrogels have been investigated for a broad variety of medical applications. The ability to assemble hydrogels at neutral pH and mild temperatures makes alginate a popular choice for the encapsulation and delivery of cells and proteins. Alginate has been studied extensively for the delivery of islets as a treatment for type 1 diabetes. However, poor stability of the encapsulation systems after implantation remains a challenge. In this paper, alginate was modified with 2-aminoethyl methacrylate hydrochloride (AEMA) to introduce groups that can be photoactivated to generate covalent bonds. This enabled formation of dual crosslinked structure upon exposure to ultraviolet light following initial ionic crosslinking into bead structures. The degree of methacrylation was varied and in vitro stability, long term swelling, and cell viability examined. At low levels of the methacrylation, the beads could be formed by first ionic crosslinks followed by exposure to ultraviolet light to generate covalent bonds. The methacrylated alginate resulted in more stable beads and cells were viable following encapsulation. Alginate microbeads, ionic (unmodified) and dual crosslinked, were implanted into a rat omentum pouch model. Implantation was performed with a local injection of 100 µl of 50 µg/ml of Lipopolysaccharide (LPS) to stimulate a robust inflammatory challenge in vivo. Implants were retrieved at 1 and 3 weeks for analysis. The unmodified alginate microbeads had all failed by week 1, whereas the dual-crosslinked alginate microbeads remained stable up through 3 weeks. The modified alginate microbeads may provide a more stable alternative to current alginate-based systems for cell encapsulation. Alginate, a naturally occurring polysaccharide, has been used for cell encapsulation to prevent graft rejection of cell transplants for people with type I diabetes. Although some success has been observed in clinical trials, the lack of reproducibility and failure to

  9. Ca2+ released from calcium alginate gels can promote inflammatory responses in vitro and in vivo

    OpenAIRE

    Chan, Gail; Mooney, David J.

    2013-01-01

    In general, alginate hydrogels are considered to be biologically inert and are commonly used for biomedical purposes that require minimum inflammation. However, Ca2+, which is commonly used to crosslink alginate, is a critical second messenger in immune cell signaling, and little has been done to understand its effect on immune cell fate when delivered as a component of alginate gels. We found that dendritic cells (DCs) encapsulated in Ca2+-crosslinked alginate (calcium alginate) secreted at ...

  10. Antimicrobial activity of gallic acid against food-related Pseudomonas strains and its use as biocontrol tool to improve the shelf life of fresh black truffles.

    Science.gov (United States)

    Sorrentino, Elena; Succi, Mariantonietta; Tipaldi, Luca; Pannella, Gianfranco; Maiuro, Lucia; Sturchio, Marina; Coppola, Raffaele; Tremonte, Patrizio

    2018-02-02

    Refrigeration alone or in combination with other technologies represents the main tool used in the last decades to preserve the freshness of black truffles. This is principally due to the delicateness and vulnerability of this edible hypogeous fungus, so that other invasive preservation practices cannot be adopted. However, the proliferation of some microbial species during the cold storage still represents an unsolved problem. Pseudomonads are among the main spoiler bacteria responsible for the deterioration of refrigerated black truffles. Their growth ability at low temperatures requires the use of additional hurdles to prolong the shelf-life of truffles without altering their major features. The use of natural compounds may represent an alternative system for the biocontrol of this kind of product. Specifically, gallic acid (GA) is a phenolic acid naturally present in different foods, whose effectiveness was in vitro demonstrated against Pseudomonas spp. In our study, we reported the antimicrobial activity expressed by GA not only in vitro, using as target bacteria Pseudomonas putida DSMZ 291 T , P. fluorescens DSMZ 50090 T , P. fragi DSMZ 3456 T and Pseudomonas spp. P30-4, previously isolated from black truffles, but also in situ on fresh black truffles stored at 4°C for 28days. Our results showed Minimum Inhibitory Concentrations (MIC) of 2.5mg/mL GA for all tested strains, except for P. fluorescens DSMZ 50090 T , having a MIC corresponding to 5mg/mL GA. The Minimum Bactericidal Concentration (MBC) was 10mg/mL for all strains. The analysis of kinetic parameters showed that the survival declined passing from 2.5 to 10mg/mL GA concentrations, with P. fluorescens confirmed to be the most resistant strain. Moreover, images obtained from Scanning Electron Microscopy revealed that Pseudomonas cells were strongly injured by the treatment with GA at 2.5mg/mL concentration, displaying visible pores on the cellular surfaces, absence of flagella and lysis with loss of

  11. Ambroxol interferes with Pseudomonas aeruginosa quorum sensing.

    Science.gov (United States)

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

    2010-09-01

    The mucolytic agent ambroxol has been reported to interfere with the formation of Pseudomonas aeruginosa-derived biofilms in addition to reducing alginate production by undefined mechanisms. Since quorum sensing is a key regulator of virulence and biofilm formation, we examined the effects of ambroxol on P. aeruginosa PAO1 wild-type bacterial clearance rates, adhesion profiles and biofilm formation compared with the quorum sensing-deficient, double-mutant strains DeltalasR DeltarhlR and DeltalasI DeltarhlI. Data presented in this report demonstrated that ambroxol treatment reduced survival rates of the double-mutant strains compared with the wild-type strain in a dose-dependent manner even though the double-mutants had increased adhesion in the presence of ambroxol compared with the wild-type strain. The PAO1 wild-type strain produced a significantly thicker biofilm (21.64+/-0.57 microm) compared with the biofilms produced by the DeltalasR DeltarhlR (7.36+/-0.2 microm) and DeltalasI DeltarhlI (6.62+/-0.31 microm) isolates. Ambroxol treatment reduced biofilm thickness, increased areal porosity, and decreased the average diffusion distance and textual entropy of wild-type and double-mutant strains. However, compared with the double-mutant strains, the changes observed for the wild-type strain were more clearly defined. Finally, ambroxol exhibited significant antagonistic quorum-sensing properties, suggesting that it could be adapted for use clinically in the treatment of cystic fibrosis and to reduce biofilm formation and in the colonisation of indwelling devices. Copyright (c) 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  12. Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Alhede, Maria; Bjarnsholt, Thomas; Givskov, Michael

    2014-01-01

    The opportunistic gram-negative bacterium Pseudomonas aeruginosa is implicated in many chronic infections and is readily isolated from chronic wounds, medical devices, and the lungs of cystic fibrosis patients. P. aeruginosa is believed to persist in the host organism due to its capacity to form...... biofilms, which protect the aggregated, biopolymer-embedded bacteria from the detrimental actions of antibiotic treatments and host immunity. A key component in the protection against innate immunity is rhamnolipid, which is a quorum sensing (QS)-regulated virulence factor. QS is a cell-to-cell signaling...

  13. A commensal streptococcus hijacks a Pseudomonas aeruginosa exopolysaccharide to promote biofilm formation.

    Directory of Open Access Journals (Sweden)

    Jessica A Scoffield

    2017-04-01

    Full Text Available Pseudomonas aeruginosa causes devastating chronic pulmonary infections in cystic fibrosis (CF patients. Although the CF airway is inhabited by diverse species of microorganisms interlaced within a biofilm, many studies focus on the sole contribution of P. aeruginosa pathogenesis in CF morbidity. More recently, oral commensal streptococci have been identified as cohabitants of the CF lung, but few studies have explored the role these bacteria play within the CF biofilm. We examined the interaction between P. aeruginosa and oral commensal streptococci within a dual species biofilm. Here we report that the CF P. aeruginosa isolate, FRD1, enhances biofilm formation and colonization of Drosophila melanogaster by the oral commensal Streptococcus parasanguinis. Moreover, production of the P. aeruginosa exopolysaccharide, alginate, is required for the promotion of S. parasanguinis biofilm formation and colonization. However, P. aeruginosa is not promoted in the dual species biofilm. Furthermore, we show that the streptococcal adhesin, BapA1, mediates alginate-dependent enhancement of the S. parasanguinis biofilm in vitro, and BapA1 along with another adhesin, Fap1, are required for the in vivo colonization of S. parasanguinis in the presence of FRD1. Taken together, our study highlights a new association between streptococcal adhesins and P. aeruginosa alginate, and reveals a mechanism by which S. parasanguinis potentially colonizes the CF lung and interferes with the pathogenesis of P. aeruginosa.

  14. A commensal streptococcus hijacks a Pseudomonas aeruginosa exopolysaccharide to promote biofilm formation.

    Science.gov (United States)

    Scoffield, Jessica A; Duan, Dingyu; Zhu, Fan; Wu, Hui

    2017-04-01

    Pseudomonas aeruginosa causes devastating chronic pulmonary infections in cystic fibrosis (CF) patients. Although the CF airway is inhabited by diverse species of microorganisms interlaced within a biofilm, many studies focus on the sole contribution of P. aeruginosa pathogenesis in CF morbidity. More recently, oral commensal streptococci have been identified as cohabitants of the CF lung, but few studies have explored the role these bacteria play within the CF biofilm. We examined the interaction between P. aeruginosa and oral commensal streptococci within a dual species biofilm. Here we report that the CF P. aeruginosa isolate, FRD1, enhances biofilm formation and colonization of Drosophila melanogaster by the oral commensal Streptococcus parasanguinis. Moreover, production of the P. aeruginosa exopolysaccharide, alginate, is required for the promotion of S. parasanguinis biofilm formation and colonization. However, P. aeruginosa is not promoted in the dual species biofilm. Furthermore, we show that the streptococcal adhesin, BapA1, mediates alginate-dependent enhancement of the S. parasanguinis biofilm in vitro, and BapA1 along with another adhesin, Fap1, are required for the in vivo colonization of S. parasanguinis in the presence of FRD1. Taken together, our study highlights a new association between streptococcal adhesins and P. aeruginosa alginate, and reveals a mechanism by which S. parasanguinis potentially colonizes the CF lung and interferes with the pathogenesis of P. aeruginosa.

  15. The compartmented alginate fibres optimisation for bitumen rejuvenator encapsulation

    Directory of Open Access Journals (Sweden)

    Amir Tabaković

    2017-08-01

    Full Text Available This article presents development of a novel self-healing technology for asphalt pavements, where asphalt binder rejuvenator is encapsulated within the compartmented alginate fibres. The key objective of the study was to optimise the compartmented alginate fibre design, i.e., maximising amount of rejuvenator encapsulated within the fibre. The results demonstrate that optimum rejuvenator content in the alginate fibre is of 70:30 rejuvenator/alginate ratio. The fibres are of sufficient thermal and mechanical strength to survive harsh asphalt mixing and compaction processes. Furthermore, results illustrate that zeer open asfalt beton (ZOAB asphalt mix containing 5% of 70:30 rejuvenator/alginate ratio compartmented alginate fibres has higher strength, stiffness and better healing properties in comparison to the control asphalt mix, i.e., mix without fibres, and mix containing fibres with lower rejuvenator content. These results show that compartmented alginate fibres encapsulating bitumen rejuvenator present a promising new approach for the development of self-healing asphalt pavement systems.

  16. Modeling carbon dioxide effect in a controlled atmosphere and its interactions with temperature and pH on the growth of L. monocytogenes and P. fluorescens.

    Science.gov (United States)

    Couvert, Olivier; Guégan, Stéphanie; Hézard, Bernard; Huchet, Véronique; Lintz, Adrienne; Thuault, Dominique; Stahl, Valérie

    2017-12-01

    The effect of carbon dioxide, temperature, and pH on growth of Listeria monocytogenes and Pseudomonas fluorescens was studied, following a protocol to monitor microbial growth under a constant gas composition. In this way, the CO2 dissolution didn't modify the partial pressures in the gas phase. Growth curves were acquired at different temperatures (8, 12, 22 and 37 °C), pH (5.5 and 7) and CO2 concentration in the gas phase (0, 20, 40, 60, 80, 100% of the atmospheric pressure, and over 1 bar). These three factors greatly influenced the growth rate of L. monocytogenes and P. fluorescens, and significant interactions have been observed between the carbon dioxide and the temperature effects. Results showed no significant effect of the CO2 concentration at 37 °C, which may be attributed to low CO2 solubility at high temperature. An inhibitory effect of CO2 appeared at lower temperatures (8 and 12 °C). Regardless of the temperature, the gaseous CO2 is sparingly soluble at acid pH. However, the CO2 inhibition was not significantly different between pH 5.5 and pH 7. Considering the pKa of the carbonic acid, these results showed the dissolved carbon under HCO3- form didn't affect the bacterial inhibition. Finally, a global model was proposed to estimate the growth rate vs. CO2 concentration in the aqueous phase. This dissolved concentration is calculated according to the physical equations related to the CO2 equilibriums, involving temperature and pH interactions. This developed model is a new tool available to manage the food safety of MAP. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Enhanced inactivation of Salmonella and Pseudomonas biofilms on stainless steel by use of T-128, a fresh-produce washing aid, in chlorinated wash solutions.

    Science.gov (United States)

    Shen, Cangliang; Luo, Yaguang; Nou, Xiangwu; Bauchan, Gary; Zhou, Bin; Wang, Qin; Millner, Patricia

    2012-10-01

    The effect of the washing aid T-128 (generally recognized as safe [GRAS] formulation, composed mainly of phosphoric acid and propylene glycol) on inactivation of Salmonella and Pseudomonas populations in biofilms on stainless steel was evaluated under conditions of increasing organic matter loads in chlorinated wash solutions dominated by hypochlorous acid. Biofilms were formed statically on stainless steel coupons suspended in 2% lettuce extract after inoculation with Salmonella enterica serovar Thompson or Newport or with Pseudomonas fluorescens. Coupons with biofilms were washed in chlorine solutions (0, 0.5, 1, 2, 5, 10, or 20 mg/liter at pH 6.5, 5.0 and 2.9), with or without T-128, and with increasing loads of organic matter (0, 0.25, 0.5, 0.75, or 1.0% lettuce extract). Cell populations on coupons were dispersed using intermittent, pulsed ultrasonication and vortexing and enumerated by colony counts on XLT-4 or Pseudomonas agars. Cell responses to fluorescent viability staining of biofilm treatment washing solutions were examined using confocal laser scanning microscopy. Results showed that 0.1% T-128 (without chlorine) reduced P. fluorescens biofilm populations by 2.5 log(10) units but did not reduce Salmonella populations. For both Salmonella and Pseudomonas, the sanitizing effect of free chlorine (1.0 to 5.0 mg/liter) was enhanced (P biofilms compared to treatments without T-128. Image analysis of surfaces stained with SYTO and propidium iodide corroborate the cultural assay results showing that T-128 can aid in reducing pathogen viability in biofilms and thus can aid in sanitizing stainless steel contact surfaces during processing of fresh-cut produce.

  18. Controlled Electrospray Generation of Nonspherical Alginate Microparticles.

    Science.gov (United States)

    Jeyhani, Morteza; Mak, Sze Yi; Sammut, Stephen; Shum, Ho Cheung; Hwang, Dae Kun; Tsai, Scott S H

    2017-12-11

    Electrospraying is a technique used to generate microparticles in a high throughput manner. For biomedical applications, a biocompatible electrosprayed material is often desirable. Using polymers, such as alginate hydrogels, makes it possible to create biocompatible and biodegradable microparticles that can be used for cell encapsulation, to be employed as drug carriers, and for use in 3D cell culturing. Evidence in the literature suggests that the morphology of the biocompatible microparticles is relevant in controlling the dynamics of the microparticles in drug delivery and 3D cell culturing applications. Yet, most electrospray-based techniques only form spherical microparticles, and there is currently no widely adopted technique for producing nonspherical microparticles at a high throughput. Here, we demonstrate the generation of nonspherical biocompatible alginate microparticles by electrospraying, and control the shape of the microparticles by varying experimental parameters such as chemical concentration and the distance between the electrospray tip and the particle-solidification bath. Importantly, we show that these changes to the experimental setup enable the synthesis of different shaped particles, and the systematic change in parameters, such as chemical concentration, result in monotonic changes to the particle aspect ratio. We expect that these results will find utility in many biomedical applications that require biocompatible microparticles of specific shapes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Alginate based scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Valente, J.F.A.; Valente, T.A.M. [CICS-UBI - Centro de Investigacao em Ciencias da Saude, Faculdade de Ciencias da Saude, Universidade da Beira Interior, Covilha (Portugal); Alves, P.; Ferreira, P. [CIEPQPF, Departamento de Engenharia Quimica, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-290 Coimbra (Portugal); Silva, A. [Centro de Ciencia e Tecnologia Aeroespaciais, Universidade da Beira Interior, Covilha (Portugal); Correia, I.J., E-mail: icorreia@ubi.pt [CICS-UBI - Centro de Investigacao em Ciencias da Saude, Faculdade de Ciencias da Saude, Universidade da Beira Interior, Covilha (Portugal)

    2012-12-01

    The design and production of scaffolds for bone tissue regeneration is yet unable to completely reproduce the native bone properties. In the present study new alginate microparticle and microfiber aggregated scaffolds were produced to be applied in this area of regenerative medicine. The scaffolds' mechanical properties were characterized by thermo mechanical assays. Their morphological characteristics were evaluated by isothermal nitrogen adsorption and scanning electron microscopy. The density of both types of scaffolds was determined by helium pycnometry and mercury intrusion porosimetry. Furthermore, scaffolds' cytotoxic profiles were evaluated in vitro by seeding human osteoblast cells in their presence. The results obtained showed that scaffolds have good mechanical and morphological properties compatible with their application as bone substitutes. Moreover, scaffold's biocompatibility was confirmed by the observation of cell adhesion and proliferation after 5 days of being seeded in their presence and by non-radioactive assays. - Highlights: Black-Right-Pointing-Pointer Design and production of scaffolds for bone tissue regeneration. Black-Right-Pointing-Pointer Microparticle and microfiber alginate scaffolds were produced through a particle aggregation technique; Black-Right-Pointing-Pointer Scaffolds' mechanically and biologically properties were characterized through in vitro studies;.

  20. Quantitative Assessment of Islets of Langerhans Encapsulated in Alginate

    Science.gov (United States)

    Johnson, Amy S.; O'Sullivan, Esther; D'Aoust, Laura N.; Omer, Abdulkadir; Bonner-Weir, Susan; Fisher, Robert J.; Weir, Gordon C.

    2011-01-01

    Improved methods have recently been developed for assessing islet viability and quantity in human islet preparations for transplantation, and these measurements have proven useful for predicting transplantation outcome. The objectives of this study were to adapt these methods for use with microencapsulated islets, to verify that they provide meaningful quantitative measurements, and to test them with two model systems: (1) barium alginate and (2) barium alginate containing a 70% (w/v) perfluorocarbon (PFC) emulsion, which presents challenges to use of these assays and is of interest in its own right as a means for reducing oxygen supply limitations to encapsulated tissue. Mitochondrial function was assessed by oxygen consumption rate measurements, and the analysis of data was modified to account for the increased solubility of oxygen in the PFC-alginate capsules. Capsules were dissolved and tissue recovered for nuclei counting to measure the number of cells. Capsule volume was determined from alginate or PFC content and used to normalize measurements. After low oxygen culture for 2 days, islets in normal alginate lost substantial viable tissue and displayed necrotic cores, whereas most of the original oxygen consumption rate was recovered with PFC alginate, and little necrosis was observed. All nuclei were recovered with normal alginate, but some nuclei from nonrespiring cells were lost with PFC alginate. Biocompatibility tests revealed toxicity at the islet periphery associated with the lipid emulsion used to provide surfactants during the emulsification process. We conclude that these new assay methods can be applied to islets encapsulated in materials as complex as PFC-alginate. Measurements made with these materials revealed that enhancement of oxygen permeability of the encapsulating material with a concentrated PFC emulsion improves survival of encapsulated islets under hypoxic conditions, but reformulation of the PFC emulsion is needed to reduce toxicity