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Sample records for fluorescens ip01 cumd

  1. 40 CFR 180.1114 - Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS...

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae 742RS; exemptions from the requirement of a tolerance... Tolerances § 180.1114 Pseudomonas fluorescens A506, Pseudomonas fluorescens 1629RS, and Pseudomonas syringae...

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

    Michael Horsfall

    ABSTRACT: The potential of local strains of microorganism (Pseudomonas fluorescens) in polyhydroxbutyrate production ... The demand for the use of biopolymers ... This work therefore investigates the production of polyhydroxybutyrate from.

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

    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...

  4. Pseudomonas fluorescens' view of the periodic table.

    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.

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

    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 ...

  6. ADHESION OF PSEUDOMONAS-FLUORESCENS TO METALLIC SURFACES

    VIEIRA, MJ; OLIVEIRA, R; MELO, L; PINHEIRO, M; VANDERMEI, HC

    1992-01-01

    Deposition of Pseudomonas fluorescens on aluminium, brass and copper plates was studied in a flow system. The number of bacteria deposited on aluminium was greater than on the other two types of metals. The results are discussed in terms of the mechanisms (transport and/or adhesion) that may control

  7. Genome Sequence of the Biocontrol Strain Pseudomonas fluorescens F113

    Redondo-Nieto, Miguel; Barret, Matthieu; Morrisey, John P.; Germaine, Kieran; Martínez-Granero, Francisco; Barahona, Emma; Navazo, Ana; Sánchez-Contreras, María; Moynihan, Jennifer A.; Giddens, Stephen R.; Coppoolse, Eric R.; Muriel, Candela; Stiekema, Willem J.; Rainey, Paul B.; Dowling, David; O'Gara, Fergal; Martín, Marta

    2012-01-01

    Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) that has biocontrol activity against fungal plant pathogens and is a model for rhizosphere colonization. Here, we present its complete genome sequence, which shows that besides a core genome very similar to those of other strains sequenced within this species, F113 possesses a wide array of genes encoding specialized functions for thriving in the rhizosphere and interacting with eukaryotic organisms. PMID:22328765

  8. Production of yellow-green fluorescent pigment by Pseudomonas fluorescens

    Gildo Almeida da Silva

    2006-05-01

    Full Text Available A medium was prepared from brewery waste yeast with and without mineral salts to study growth and yellow-green fluorescent pigment production (YGFP by Pseudomonas fluorescens. The King's medium used for detection of siderophore production were expressively weaker inductors of YGFP formation when compared to FYE medium. Although FYE and CYE could be used for growth of P. fluorescens, only FYE was an attractive medium for detection of YGFP strain producers.Diversos microrganismos secretam substâncias com alta afinidade por ferro. Estas moléculas, sideróforos, transportam ferro para o interior das células. Como a produção destas moléculas depende da composição do meio, foi avaliada a influência do extrato de levedura (FYE, proveniente de resíduo de cervejaria, com e sem adição de sais minerais, sobre o crescimento de Pseudomonas fluorescens e sobre a formação de pigmento fluorescente verde-amarelado (YGFP. Observou-se que (i FYE com sacarose (G7 e o extrato de levedura comercial (CYE possuem um pico bem definido próximo a 260 nm; (ii FYE, mas não CYE, promove alta formação de YGFP. Os meios de King's, usados para detectar a formação de sideróforo, se comportaram como indutores expressivamente mais fracos de YGFP que o meio FYE. Embora FYE e CYE possam ser usados para o crescimento de P. fluorescens, apenas FYE pode ser usado como meio para a detecção de linhagens formadoras de YGFP.

  9. Foam separation of Pseudomonas fluorescens and Bacillus subtilis var. niger.

    Grieves, R B; Wang, S L

    1967-01-01

    An experimental investigation established the effect of the presence of inorganic salts on the foam separation of Pseudomonas fluorescens and of Bacillus subtilis var. niger (B. globigii) from aqueous suspension by use of a cationic surfactant. For P. fluorescens, 5.0 mueq/ml of NaCl, KCl, Na(2)SO(4), K(2)SO(4), CaCl(2), CaSO(4), MgCl(2), or MgSO(4) produced increases in the cell concentration in the residual suspension (not carried into the foam) from 2.9 x 10(5) up to 1.6 x 10(6) to 2.8 x 10(7) cells per milliliter (initial suspensions contain from 3.3 x 10(7) to 4.8 x 10(7) cells per milliliter). The exceptional influence of magnesium was overcome by bringing the cells into contact first with the surfactant and then the salt. For B. subtilis, the presence of 5.0 mueq/ml of any of the eight salts increased the residual cell concentration by one order of magnitude from 1.2 x 10(4) to about 4.0 x 10(5) cells per milliliter. This occurred regardless of the sequence of contact as long as the surfactant contact period was sufficient. The presence of salts increased collapsed foam volumes with P. fluorescens and decreased collapsed foam volumes with B. subtilis.

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

    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.

  11. 40 CFR 180.1200 - Pseudomonas fluorescens strain PRA-25; temporary exemption from the requirement of a tolerance.

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Pseudomonas fluorescens strain PRA-25... RESIDUES IN FOOD Exemptions From Tolerances § 180.1200 Pseudomonas fluorescens strain PRA-25; temporary... established for residues of the microbial pesticide, pseudomonas fluorescens strain PRA-25 when used on peas...

  12. Effects of cysteine on growth, protease production, and catalase activity of Pseudomonas fluorescens.

    Himelbloom, B H; Hassan, H M

    1986-01-01

    Cysteine inhibits growth of and protease production by Pseudomonas fluorescens NC3. Catalase activity in P. fluorescens NC3 was increased by cysteine. The addition of exogenous hydrogen peroxide did not increase catalase activity, thus suggesting a role for the endogenous generation of hydrogen peroxide via the autoxidation of cysteine.

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

    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-...

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

    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

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

    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.

  16. Boolean models of biosurfactants production in Pseudomonas fluorescens.

    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.

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

    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.

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

    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

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

    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...... shown to impact gene expression, protein folding and fitness, however, direct evidence that they can be positively selected, and so contribute to adaptation, is lacking. Here we report the recovery of two beneficial synonymous single base pair changes that arose spontaneously and independently...... 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...

  20. Bioreporter pseudomonas fluorescens HK44 immobilized in a silica matrix

    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.

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

    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

  2. IDENTIFIKASI SURFAKTIN PADA PSEUDOMONAS FLUORESCENS ST1 PENGENDALI EFEKTIF PENYAKIT PUSTUL KEDELAI

    Suskandini Ratih Dirmawati .

    2011-11-01

    Full Text Available Identification of surfactin in Pseudomonas fluorescens ST1 which effectively suppres soybean bacterial pustule.   Identification of surfactin in Pseudomonas fluorescens ST1 filtrate was conducted in Plant Pest and Disease Laboratory, Bogor Agriculture University.  The 48 hours cultured suspension of  P. fluorescens ST1 with 108 CFU/ml density was centrifuged to obtain the supernatant.  The supernatant was analyzed for its surfactin content by High Performance Liquid Chromatography with Colum ODS-5 and eluen acetonitril and acetat acid.  The result showed  that  surfactin was producted by P. fluorescens ST1 and this bioactive substance could suppres the bacterial pustule on soybean.

  3. Effect of charged particle flux on Bacillus mesentericus and Pseudomonas fluorescens cultures

    Ostapenkov, A.M.; Kaptereva, Yu.V.; Merinov, N.S.; Lavrova, V.L.

    1979-01-01

    Studied was the effect of a strong electric field and charged particle (aerions) flow on Bac. mesentericus and Ps. fluorescens cultures causing the spoiling of foodstuffs and food raw materials. It has been found, that under the effects of the electric field and positive or negative ions reduced is the Bac. mesentericus and Ps. fluorescens viability, cultivated on a solid nutrient medium; the effect of the electric field only does not affect the Bac. mesentericus viability

  4. Effect of GABA, a Bacterial Metabolite, on Pseudomonas fluorescens Surface Properties and Cytotoxicity

    Marc G. J. Feuilloley

    2013-06-01

    Full Text Available Different bacterial species and, particularly Pseudomonas fluorescens, can produce gamma-aminobutyric acid (GABA and express GABA-binding proteins. In this study, we investigated the effect of GABA on the virulence and biofilm formation activity of different strains of P. fluorescens. Exposure of a psychotropic strain of P. fluorescens (MF37 to GABA (10−5 M increased its necrotic-like activity on eukaryotic (glial cells, but reduced its apoptotic effect. Conversely, muscimol and bicuculline, the selective agonist and antagonist of eukaryote GABAA receptors, respectively, were ineffective. P. fluorescens MF37 did not produce biosurfactants, and its caseinase, esterase, amylase, hemolytic activity or pyoverdine productions were unchanged. In contrast, the effect of GABA was associated to rearrangements of the lipopolysaccharide (LPS structure, particularly in the lipid A region. The surface hydrophobicity of MF37 was marginally modified, and GABA reduced its biofilm formation activity on PVC, but not on glass, although the initial adhesion was increased. Five other P. fluorescens strains were studied, and only one, MFP05, a strain isolated from human skin, showed structural differences of biofilm maturation after exposure to GABA. These results reveal that GABA can regulate the LPS structure and cytotoxicity of P. fluorescens, but that this property is specific to some strains.

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

    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.

  6. Enhanced extracellular chitinase production in Pseudomonas fluorescens: biotechnological implications

    Azhar Alhasawi

    2017-06-01

    Full Text Available Chitin is an important renewable biomass of immense commercial interest. The processing of this biopolymer into value-added products in an environmentally-friendly manner necessitates its conversion into N-acetyl glucosamine (NAG, a reaction mediated by the enzyme chitinase. Here we report on the ability of the soil microbe Pseudomonas fluorescens to secrete copious amounts of chitinase in the spent fluid when cultured in mineral medium with chitin as the sole source of carbon and nitrogen. Although chitinase was detected in various cellular fractions, the enzyme was predominantly localized in the extracellular component that was also rich in NAG and glucosamine. Maximal amounts of chitinase with a specific activity of 80 µmol NAG produced mg–1 protein min–1 was obtained at pH 8 after 6 days of growth in medium with 0.5 g of chitin. In-gel activity assays and Western blot studies revealed three isoenzymes. The enzyme had an optimal activity at pH 10 and a temperature range of 22–38 ℃. It was stable for up to 3 months. Although it showed optimal specificity toward chitin, the enzyme did readily degrade shrimp shells. When these shells (0.1 g were treated with the extracellular chitinase preparation, NAG [3 mmoles (0.003 g-mol] was generated in 6 h. The extracellular nature of the enzyme coupled with its physico-chemical properties make this chitinase an excellent candidate for biotechnological applications.

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

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

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

    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

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

    Zhang, Xianhui; Yang, Si-ze [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Dongping [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Sun, Yue [School of Physics, Changchun University of Science and Technology, Changchun 130022 (China)

    2013-05-15

    The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

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

    Nayaka, Siddaiah Chandra; Shankar, Arakere C Udaya; Reddy, Munagala S; Niranjana, Siddapura R; Prakash, Harishchandra S; Shetty, Hunthrike S; Mortensen, Carmen N

    2009-07-01

    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 elicited considerable attention over the past decade owing to their association with animal disease syndromes. Hence, the present study was conducted to evaluate ecofriendly approaches by using a maize rhizosphere isolate of Pseudomonas fluorescens (Trev.) Mig. and its formulation to control ear rot disease and fumonisin accumulation, and also to study the capacity to promote growth and yield of maize. In vitro assays were conducted to test the efficacy of P. fluorescens as a seed treatment on seed germination, seedling vigour and also the incidence of F. verticillioides in different maize cultivars. The field trials included both seed treatment and foliar spray. For all the experiments, P. fluorescens was formulated using corn starch, wheat bran and talc powder. In each case there were three different treatments of P. fluorescens, a non-treated control and chemical control. Pure culture 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. 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 kernels intended for human and animal feed. (c) 2009 Society of Chemical Industry.

  11. Switching catalysis from hydrolysis to perhydrolysis in P. fluorescens esterase

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

    2010-01-01

    Many serine hydrolases catalyze perhydrolysis – the reversible formation of per-acids 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. Angew. Chem. Intl. Ed. 2005, 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 ε-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 two fold higher kcat, but Km also increased so the specificity constant, kcat/Km, 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 ε-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the active site blocks access for

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

    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

  13. Expression analysis of the gacS mutant of Pseudomonas fluorescens SBW25

    Cheng, Xu; Bruijn, de Irene; Voort, van der M.; Raaijmakers, Jos

    2013-01-01

    Pseudomonas species are ubiquitous in plant-associated environments and produce an array of volatiles, enzymes and antimicrobials. The biosynthesis of many metabolites is regulated by the GacS/GacA two-component regulatory system. Transcriptome analysis of Pseudomonas fluorescens SBW25 revealed that

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

    Gram, Lone; Melchiorsen, Jette; Spanggaard, Bettina

    1999-01-01

    To study the possible use of probiotics in fish farming, we evaluated the in vitro and in vivo antagonism of antibacterial strain Pseudomonas fluorescens strain AH2 against the fish- pathogenic bacterium Vibrio anguillarum. As iron is important in virulence and bacterial interactions, the effect....... fluorescens AH2 inhibited the growth of V. anguillarum during coculture, independently of the iron concentration, when the initial count of the antagonist was 100 to 1,000 times greater that of the fish pathogen. These in vitro results were successfully repeated in vivo. A probiotic effect in vivo was tested...... by exposing rainbow trout (Oncorynchus mykiss Walbaum) to P. fluorescens AH2 at a density of 10(5) CFU/ml for 5 days before a challenge with V. anguillarum at 10(4) to 10(5) CFU/ml for 1 h. Some fish were also exposed to P. fluorescens AH2 at 10(7) CFU/ml during the 1-h infection. The combined probiotic...

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

    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...

  16. Interactions of trivalent and tetravalent heavy metal-siderophore complexes with pseudomonas fluorescens

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

    2004-01-01

    We investigated the interactions of the Fe(III)-, Eu(III)-, and Hf(IV)-desferrioxamine B (DFO) complexes with the Gram-negative aerobic bacterium Pseudomonas fluorescens. Potentiometric titration of 1:1 Fe(III)-, Eu(III)-, and Hf(IV)-DFO complexes showed that Hf(IV) formed a strong complex with DFO whose stability was comparable to that of the Fe(III)-DFO complex, while Eu(III) formed a weaker one. DFO in a growth medium was not degraded by P. fluorescens. Contact of P. fluorescens cells with the Fe(III)-, Eu(III)-, and Hf(IV)-DFO complexes at pH 4-9 revealed that there was negligible adsorption of Hf(IV) and Fe(III), whereas Eu(III) was dissociated from DFO and was readily adsorbed by the cells. These results suggest that Fe(III) and Hf(IV) form stable complexes with DFO and are not adsorbed by P. fluorescens cells. Europium(III) forms a weaker complex with DFO than Fe(III) and Hf(IV) do and its DFO complex is readily dissociated in the presence of the cells. (orig.)

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

    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

  18. Effects of gamma irradiation on the survival of Pseudomonas fluorescens inoculated on romaine lettuce

    Irradiation of fresh fruits and vegetables has been utilized as a post-harvest intervention measure for inactivation of microbial pathogens. Pseudomonas fluorescens 2-79, Q8R1, Q287 are non-plant pathogenic, non-pectolytic strains of a potential biocontrol agent. We tested the sensitivity of these s...

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

    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...

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

    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,

  1. Inactivation of Pseudomonas fluorescens in skim milk by combinations of pulsed electric fields and organic acids.

    Fernández-Molina, Juan J; Altunakar, Bilge; Bermúdez-Aguirre, Daniela; Swanson, Barry G; Barbosa-Cánovas, Gustavo V

    2005-06-01

    Pseudomonas fluorescens suspended in skim milk was inactivated by application of pulsed electric fields (PEF) either alone or in combination with acetic or propionic acid. The initial concentration of microorganisms ranged from 10(5) to 10(6) CFU/ml. Addition of acetic acid and propionic acid to skim milk inactivated 0.24 and 0.48 log CFU/ml P. fluorescens, respectively. Sets of 10, 20, and 30 pulses were applied to the skim milk using exponentially decaying pulses with pulse lengths of 2 micros and pulse frequencies of 3 Hz. Treatment temperature was maintained between 16 and 20 degrees C. In the absence of organic acids, PEF treatment of skim milk at field intensities of 31 and 38 kV/cm reduced P. fluorescens populations by 1.0 to 1.8 and by 1.2 to 1.9 log CFU/ml, respectively. Additions of acetic and propionic acid to the skim milk in a pH range of 5.0 to 5.3 and PEF treatment at 31, 33, and 34 kV/cm, and 36, 37, and 38 kV/cm reduced the population of P. fluorescens by 1.4 and 1.8 log CFU/ml, respectively. No synergistic effect resulted from the combination of PEF with acetic or propionic acid.

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

    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

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

    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

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

    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.)

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

    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.

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

    Susanna K Remold

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

  7. Effect of Naphthalene and Salicylate Analogues on the Bioluminescence of Bioreporter Pseudomonas Fluorescens HK44.

    Trögl, Josef; Kuncová, Gabriela; Kubicová, L.; Pařík, P.; Hálová, Jaroslava; Demnerová, K.; Ripp, S.; Sayler, G. S.

    2007-01-01

    Roč. 52, 1 (2007) , s. 3-14 ISSN 0015-5632 R&D Projects: GA ČR(CZ) GA104/05/2637; GA ČR(CZ) GA203/06/1244 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502 Keywords : pseudomonas fluorescens HK44 * bioluminescence * bioluminescence Subject RIV: CE - Biochemistry Impact factor: 0.989, year: 2007

  8. Sorption of Eu(III) on Pseudomonas fluorescens in the presence of citric acid

    Suzuki, Yoshinori; Tsushima, Satoru; Yamamoto, Ichiro; Nankawa, Takuya; Yoshida, Takahiro; Ozaki, Takuo; Ohnuki, Toshihiko; Francis, Arokiasamy J.; Enokida, Youichi

    2005-01-01

    We studied the sorption of Eu(III) on Pseudomonas fluorescens in the absence and presence of citric acid by a batch method. The cells were placed in a solution containing 2 μM of Eu(III) and 0, 100, or 1000 μM of citric acid at pH 3 9 for 5 hours. In the absence of citric acid, almost 100% of Eu(III) was sorbed on P. fluorescens at pHs below 7; above 7, sorption decreased with an increase in pH. The time course of Eu(III) sorption on P. fluorescens showed that a fraction of it was desorbed into the solution at alkaline pHs, suggesting that the bacterium may release some exudates. With citric acid present, we found that at higher concentrations there was lower sorption of Eu(III), reflecting the formation of Eu(III)-citrate complexes with the Eu(III)-cell-surface complexes. This decrease in Eu(III) sorption was significant in alkaline pHs. These findings suggest that citric acid which is ubiquitously found in the environment enhances migration of trivalent actinides in the alkaline environment. (author)

  9. Characterization of the SPI-1 and Rsp type three secretion systems in Pseudomonas fluorescens F113.

    Barret, Matthieu; Egan, Frank; Moynihan, Jennifer; Morrissey, John P; Lesouhaitier, Olivier; O'Gara, Fergal

    2013-06-01

    Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar beet rhizosphere. The recent annotation of the F113 genome sequence has revealed that this strain encodes a wide array of secretion systems, including two complete type three secretion systems (T3SSs) belonging to the Hrp1 and SPI-1 families. While Hrp1 T3SSs are frequently encoded in other P. fluorescens strains, the presence of a SPI-1 T3SS in a plant-beneficial bacterial strain was unexpected. In this work, the genetic organization and expression of these two T3SS loci have been analysed by a combination of transcriptional reporter fusions and transcriptome analyses. Overexpression of two transcriptional activators has shown a number of genes encoding putative T3 effectors. In addition, the influence of these two T3SSs during the interaction of P. fluorescens F113 with some bacterial predators was also assessed. Our data revealed that the transcriptional activator hilA is induced by amoeba and that the SPI-1 T3SS could potentially be involved in resistance to amoeboid grazing. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

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

    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.

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

    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

  12. Pseudomonas fluorescens-like bacteria from the stomach: a microbiological and molecular study.

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

    2013-02-21

    To characterize oxidase- and urease-producing bacterial isolates, grown aerobically, that originated from antral biopsies of patients suffering from acid peptic diseases. A total of 258 antral biopsy specimens were subjected to isolation of bacteria followed by tests for oxidase and urease production, acid tolerance and aerobic growth. The selected isolates were further characterized by molecular techniques viz. amplifications for 16S rRNA using universal eubacterial and HSP60 gene specific primers. The amplicons were subjected to restriction analysis and partial sequencing. A phylogenetic tree was generated using unweighted pair group method with arithmetic mean (UPGMA) from evolutionary distance computed with bootstrap test of phylogeny. Assessment of acidity tolerance of bacteria isolated from antrum was performed using hydrochloric acid from 10(-7) mol/L to 10(-1) mol/L. Of the 258 antral biopsy specimens collected from patients, 179 (69.4%) were positive for urease production by rapid urease test and 31% (80/258) yielded typical Helicobacter pylori (H. pylori) after 5-7 d of incubation under a microaerophilic environment. A total of 240 (93%) antral biopsies yielded homogeneous semi-translucent and small colonies after overnight incubation. The partial 16S rRNA sequences revealed that the isolates had 99% similarity with Pseudomonas species. A phylogenetic tree on the basis of 16S rRNA sequences denoted that JQ927226 and JQ927227 were likely to be related to Pseudomonas fluorescens (P. fluorescens). On the basis of HSP60 sequences applied to the UPGMA phylogenetic tree, it was observed that isolated strains in an aerobic environment were likely to be P. fluorescens, and HSP60 sequences had more discriminatory potential rather than 16S rRNA sequences. Interestingly, this bacterium was acid tolerant for hours at low pH. Further, a total of 250 (96.9%) genomic DNA samples of 258 biopsy specimens and DNA from 240 bacterial isolates were positive for the 613 bp

  13. 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

    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...

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

    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.

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

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

    2013-05-01

    Zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis) are the "poster children" of high-impact aquatic invasive species. In an effort to develop an effective and environmentally acceptable method to control their fouling of raw-water conduits, we have investigated the potential use of bacteria and their natural metabolic products as selective biological control agents. An outcome of this effort was the discovery of Pseudomonas fluorescens strain CL145A - an environmental isolate that kills these dreissenid mussels by intoxication (i.e., not infection). In the present paper, we use molecular methods to reconfirm that CL145A is a strain of the species P. fluorescens, and provide a phylogenetic analysis of the strain in relation to other Pseudomonas spp. We also provide evidence that the natural product lethal to dreissenids is associated with the cell wall of P. fluorescens CL145A, is a heat-labile secondary metabolite, and has degradable toxicity within 24 h when applied to water. CL145A appears to be an unusual strain of P. fluorescens since it was the only one among the ten strains tested to cause high mussel mortality. Pipe trials conducted under once-through conditions indicated: (1) P. fluorescens CL145A cells were efficacious against both zebra and quagga mussels, with high mortalities achieved against both species, and (2) as long as the total quantity of bacterial cells applied during the entire treatment period was the same, similar mussel mortality could be achieved in treatments lasting 1.5-12.0 h, with longer treatment durations achieving lower mortalities. The efficacy data presented herein, in combination with prior demonstration of its low risk of non-target impact, indicate that P. fluorescens CL145A cells have significant promise as an effective and environmentally safe control agent against these invasive mussels. Copyright © 2012 Elsevier Inc. All rights reserved.

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

    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.

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

    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 (<72 hours old) freshwater unionid mussels was evaluated. Forty unionid mussels of each species were 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).

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

    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.

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

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

    2007-01-01

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

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

    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.

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

    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.

  2. Physiological and biochemical changes in Matricaria chamomilla induced by Pseudomonas fluorescens and water deficit stress

    Hamid MOHAMMADI

    2018-04-01

    Full Text Available Environmental stresses and rhizosphere microorganisms affect growth parameters and accumulation of active ingredients especially in plants with medicinal properties. The present study examined the effects of chamomile (Matricaria chamomilla L. seedling inoculation with Pseudomonas fluorescens PF-135 strain on its growth parameters, photosynthetic pigments, proline, malondialdehyde (MDA, and hydrogen peroxide (H2O2 content, and essential oil concentration at both regular watering and water deficit experiments. Based on the obtained results, water deficit stress reduced root dry mass, and flower fresh and dry mass as well. However, amount of H2O2 and MDA in root and shoot tissues were considerably lower in inoculated plants compared to non-inoculated ones under both normal watering and water deficit regimes. It indicates that lipid peroxidation and production of reactive oxygen species has been diminished in inoculated plants. Also, essential oil content in inoculated plants significantly increased compared with that of non-inoculated ones under water deficit stress condition. It can be concluded that P. fluorescens PF-135 strain has an outstanding potential to alleviate adverse effects of water deficit on plant growth, and hence can be used as an excellent PGPR in order to boost chamomile productivity especially under water deficit stress condition.

  3. Spatial distributions of Pseudomonas fluorescens colony variants in mixed-culture biofilms.

    Workentine, Matthew L; Wang, Siyuan; Ceri, Howard; Turner, Raymond J

    2013-07-28

    The emergence of colony morphology variants in structured environments is being recognized as important to both niche specialization and stress tolerance. Pseudomonas fluorescens demonstrates diversity in both its natural environment, the rhizosphere, and in laboratory grown biofilms. Sub-populations of these variants within a biofilm have been suggested as important contributors to antimicrobial stress tolerance given their altered susceptibility to various agents. As such it is of interest to determine how these variants might be distributed in the biofilm environment. Here we present an analysis of the spatial distribution of Pseudomonas fluorescens colony morphology variants in mixed-culture biofilms with the wildtype phenotype. These findings reveal that two variant colony morphotypes demonstrate a significant growth advantage over the wildtype morphotype in the biofilm environment. The two variant morphotypes out-grew the wildtype across the entire biofilm and this occurred within 24 h and was maintained through to 96 h. This competitive advantage was not observed in homogeneous broth culture. The significant advantage that the variants demonstrate in biofilm colonization over the wildtype denotes the importance of this phenotype in structured environments.

  4. Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L.).

    Prasad, Andhare A; Babu, Subramanian

    2017-01-01

    We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU) and one biocontrol agent (Pseudomonas fluorescens strain PF1) for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

  5. Compatibility of Azospirillum brasilense and Pseudomonas fluorescens in growth promotion of groundnut ( Arachis hypogea L.

    ANDHARE A. PRASAD

    Full Text Available ABSTRACT We attempted to study the compatibility among plant beneficial bacteria in the culture level by growing them near in the nutrient agar plates. Among all the bacteria tested, Rhizobium was found to inhibit the growth of other bacteria. From the compatible group of PGPR, we have selected one biofertilizer (Azospirillum brasilense strain TNAU and one biocontrol agent (Pseudomonas fluorescens strain PF1 for further studies in the pot culture. We have also developed a bioformulation which is talc powder based, for individual bacteria and mixed culture. This formulation was used as seed treatment, soil application, seedling root dip and foliar spray in groundnut crop in vitro germination conditions. A. brasilense was found to enhance the tap root growth and P. fluorescens, the lateral root growth. The other growth parameters like shoot growth, number of leaves were enhanced by the combination of both of the bacteria than their individual formulations. Among the method of application tested in our study, soil application was found to be the best in yielding better results of plant growth promotion.

  6. Detoxification of selenite and mercury by reduction and mutual protection in the assimilation of both elements by Pseudomonas fluorescens

    Belzile, Nelson; Wu Gaojun; Chen, Yu-Wei; Appanna, Vasu D.

    2006-01-01

    A study on the assimilation and detoxification of selenium and mercury and on the interaction between these two elements was conducted on Pseudomonas fluorescens. P. fluorescens was able to convert separately both elements to their elemental forms, which are less toxic and biologically less available. To study the converting mechanism of selenite to elemental Se, cells were grown in the presence of various selenite concentrations and several parameters such as extracellular protein concentrations, pH, carbohydrate concentrations, isocitrate dehydrogenase (ICDH) and malic enzyme were monitored. Transmission electron microscopy (TEM) and various analytical methods were applied to confirm the interaction between selenium and cell. The former appeared as a red precipitate localized predominantly in the consumed culture medium. P. fluorescens also resisted to the toxic effect of mercury by converting Hg 2+ to the volatile and less toxic form Hg . Mercury reductase was likely responsible for the conversion of Hg 2+ to Hg . More importantly, the interaction between mercury and selenium was also studied. The presence of selenite significantly reduced the accumulation of mercury in P. fluorescens. It was also interesting to note that mercury appeared to behave as a protecting agent against selenium intoxication as the bioaccumulation of Se was also inhibited by this metal. The formation of Se-Hg complexes could explain this mutual protective effect. No precipitate of elemental Se could be detected when Hg was present in the cultures

  7. LETHALITY OF PSEUDOMONAS FLUORESCENS STRAIN CLO145A TO THE 2 ZEBRA MUSSEL SPECIES PRESENT IN NORTH AMERICA

    Molloy, Daniel P.

    2001-01-01

    These experiments indicated that bacterial strain CL0145A of Pseudomonas fluorescens is equally lethal to the 2 zebra mussel species present in North America, Dreissena polymorpha and Dreissena bugensis. Thus, this bacterial strain should be equally effective at killing zebra mussels in power plant pipes, irrespective of which species is present

  8. Characterization of toxin complex gene clusters and insect toxicity of bacteria representing four subgroups of Pseudomonas fluorescens

    Ten strains representing four lineages of Pseudomonas (P. chlororaphis, P. corrugata, P. koreensis, and P. fluorescens subgroups) were evaluated for toxicity to the tobacco hornworm Manduca sexta and the fruit fly Drosophila melanogaster. The three strains within the P. chlororaphis subgroup exhibi...

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

    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.

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

    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...

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

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

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

    Kandasamy, Saveetha; Loganathan, Karthiba; Muthuraj, Raveendran; Duraisamy, Saravanakumar; Seetharaman, Suresh; Thiruvengadam, Raguchander; Ponnusamy, Balasubramanian; Ramasamy, Samiyappan

    2009-12-24

    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. 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. 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.

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

    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.

  14. LETHALITY OF PSEUDOMONAS FLUORESCENS STRAIN CLO145A TO THE 2 ZEBRA MUSSEL SPECIES PRESENT IN NORTH AMERICA

    Daniel P. Molloy

    2001-10-28

    These experiments indicated that bacterial strain CL0145A of Pseudomonas fluorescens is equally lethal to the 2 zebra mussel species present in North America, Dreissena polymorpha and Dreissena bugensis. Thus, this bacterial strain should be equally effective at killing zebra mussels in power plant pipes, irrespective of which species is present.

  15. Cost modeling of pseudomonoas fluorescens and pseudomonoas chlororphis biocontrol for competitive exclusion of salmonella enterica on tomatoes

    Biocontrol measures may enhance postharvest interventions, however; published research on process-based models for biocontrol of foodborne pathogens on produce is limited. The aim of this research was to develop cost model estimates for competitive exclusion process using Pseudomonas fluorescens and...

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

    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.

  17. Differential impact of some Aspergillus species on Meloidogyne javanica biocontrol by Pseudomonas fluorescens strain CHA0.

    Siddiqui, I A; Shaukat, S S; Khan, A

    2004-01-01

    The aim was to determine the influence of some Aspergillus species on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Six species of Aspergillus, isolated from the rhizosphere of certain crops, produced a variety of secondary metabolites in vitro. Culture filtrate (CF) obtained from Ps. fluorescens strain CHA0 and its2,4-diacetylphloroglucinol overproducing mutant CHA0/pME3424 grown in King's B liquid medium caused significant mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with CF of A. niger enhanced nematicidal and beta-galactosidase activities of fluorescent pseudomonads while A. quadrilineatus repressed such activities. Methanol or ethyl acetate extracts of the CF of A. niger markedly optimized bacterial efficacy to cause nematode deaths while hexane extract of the fungus had no influence on the nematicidal activity of the bacterial strains. A. niger applied alone or in conjunction with the bacterial inoculants inhibited root-knot nematode galling in tomato. On the other hand, A. quadrilineatus used alone or together with CHA0 did not inhibit nematode galling but when used in combination with strain CHA0/pME3424 did reduce galling intensity. Aspergillus niger enhances the production of nematicidal compounds by Ps. fluorescensin vitro and improves biocontrol potential of the bacterial inoculants in tomato while A. quadrilineatus reduces bacterial performance to suppress root-knot nematodes. Rhizosphere harbours a variety of micro-organisms including bacteria, fungi and viruses. Aspergillus species are ubiquitous in most agricultural soils and generally produce a variety of secondary metabolites. Such metabolites synthesized by Aspergillus species may influence the production of nematicidal agents and subsequent biocontrol performance of the bacterial inoculants against plant-parasitic nematodes. This fact needs to be taken into

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

    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.

  19. Evaluación de la biorremediación en suelos contaminados con hidrocarburos utilizando pseudomonas fluorescens.

    Pérez Pozo, Marco Rafael

    2018-01-01

    Since the discovery of hydrocarbons, their use in industries has caused severe environmental impacts, which have been occurring frequently in various parts of the Ecuadorian Amazon. In the present investigation the biodegradation capacity of Pseudomonas fluorescens was assessed by bioaumentation in soils of the Ecuadorian Amazon contaminated with PAHs (Polycyclic Aromatic Hydrocarbons) and TPHs (Total Petroleum Hydrocarbons). The bioaumentation, is an efficient alternative for this type of...

  20. Enlightening mineral iron sensing in Pseudomonas fluorescens by surface active maghemite nanoparticles: Involvement of the OprF porin.

    Magro, Massimiliano; Fasolato, Luca; Bonaiuto, Emanuela; Andreani, Nadia Andrea; Baratella, Davide; Corraducci, Vittorino; Miotto, Giovanni; Cardazzo, Barbara; Vianello, Fabio

    2016-10-01

    Mineral iron(III) recognition by bacteria is considered a matter of debate. The peculiar surface chemistry of novel naked magnetic nanoparticles, called SAMNs (surface active maghemite nanoparticles) characterized by solvent exposed Fe(3+) sites on their surface, was exploited for studying mineral iron sensing in Pseudomonas fluorescens. SAMNs were applied for mimicking Fe(3+) ions in solution, acting as magnetically drivable probes to evaluate putative Fe(3+) recognition sites on the microorganism surface. Culture broths and nano-bio-conjugates were characterized by UV-Vis spectroscopy and mass spectrometry. The whole heritage of a membrane porin (OprF) of P. fluorescens Ps_22 cells was recognized and firmly bound by SAMNs. The binding of nanoparticles to OprF porin was correlated to a drastic inhibition of a siderophore (pyoverdine) biosynthesis and to the stimulation of the production and rate of formation of a secondary siderophore. The analysis of metabolic pathways, based on P. fluorescens Ps_22 genomic information, evidenced that this putative secondary siderophore does not belong to a selection of the most common siderophores. In the scenario of an adhesion mechanism, it is plausible to consider OprF as the biological component deputed to the mineral iron sensing in P. fluorescens Ps_22, as well as one key of siderophore regulation. The present work sheds light on mineral iron sensing in microorganisms. Peculiar colloidal naked iron oxide nanoparticles offer a useful approach for probing the adhesion of bacterial surface on mineral iron for the identification of the specific recognition site for this iron uptake regulation in microorganisms. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    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.

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

    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.

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

    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.

  4. Listeria monocytogenes impact on mature or old Pseudomonas fluorescens biofilms during growth at 4 and 20ºC

    Puga eCH

    2016-02-01

    Full Text Available 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 20ºC and 4ºC, 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 20ºC, but not in those grown at 4ºC. 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.

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

    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.

  6. Effect of Eu(III) on the degradation of malic acid by Pseudomonas fluorescens

    Nankawa, T.; Ozaki, T.; Ohnuki, T.; Suzuki, Y.; Francis, A.J.

    2005-01-01

    Full text of publication follows: The transuranic elements, such as Am(III) and Cm(III), are highly toxic because they emit high-energy α particles and have long half-lives. To estimate their long-term environmental behavior, we need to elucidate degradation of actinide-organic complexes by microorganisms. We studied the biodegradation of Eu(III)-malic acid complexes by Pseudomonas fluorescens. Malic acid is ubiquitous in the environment and is one of the microbial metabolites that is part of the tri-carboxylic acid (TCA) cycle. Europium(III) is a good analogue for Am(III) and Cm(III). To investigate the effect of Eu(III) on the degradation of malic acid by P. fluorescens, we compared the degradation behavior of Eu(III)-malic acid complexes to that of Fe(III) and Al(III)-malic acid complexes. In the medium containing 1 mM malic acid and 0-0.5 mM Fe(III), malic acid was degraded completely. In the medium containing 1 mM malic acid and 0.05-0.5 mM Al(III), malic acid was degraded until the concentration of malic acid became equal to that of Al(III), indicating that Al(III)-malic acid complex with 1: 1 molar ratio was recalcitrant to biodegradation. In the medium containing 1 mM malic acid and 0.05-0.5 mM Eu(III), degradation of malic acid was not observed. The effect of metals on degradation of malic acid was in the order of Fe(III) < Al(III) < Eu(III). The stability constants of 1:1 Fe(III)-, Al(III)-, and Eu(III)-malic acid complexes are 7.1, 4.6, and 4.9, respectively. These results indicate that degradability of malic acid does not depend on the stability constants of metal-malic acid complexes. We found that 10 mM malic acid was degraded in the presence of 0.05 and 0.1 mM Eu(III) but 1 mM malic acid was not degraded in the presence of 0.05 and 0.1 mM Eu(III). The degradation rate of malic acid increased with a decreasing ratio of Eu(III) to malic acid. (authors)

  7. Response to gaseous NO2 air pollutant of P. fluorescens airborne strain MFAF76a and clinical strain MFN1032

    Tatiana eKondakova

    2016-03-01

    Full Text Available Human exposure to nitrogen dioxide (NO2, an air pollutant of increasing interest in biology, results in several toxic effects to human health and also to the air microbiota. The aim of this study was to investigate the bacterial response to gaseous NO2. Two Pseudomonas fluorescens strains, namely the airborne strain MFAF76a and the clinical strain MFN1032 were exposed to 0.1, 5 or 45 ppm concentrations of NO2, and their effects on bacteria were evaluated in terms of motility, biofilm formation, antibiotic resistance, as well as expression of several chosen target genes. While 0.1 and 5 ppm of NO2 did not lead to any detectable modification in the studied phenotypes of the two bacteria, several alterations were observed when the bacteria were exposed to 45 ppm of gaseous NO2. We thus chose to focus on this high concentration. NO2-exposed P. fluorescens strains showed reduced swimming motility, and decreased swarming in case of the strain MFN1032. Biofilm formed by NO2-treated airborne strain MFAF76a showed increased maximum thickness compared to non-treated cells, while NO2 had no apparent effect on the clinical MFN1032 biofilm structure. It is well known that biofilm and motility are inversely regulated by intracellular c-di-GMP level. The c-di-GMP level was however not affected in response to NO2 treatment. Finally, NO2-exposed P. fluorescens strains were found to be more resistant to ciprofloxacin and chloramphenicol. Accordingly, the resistance nodulation cell division (RND MexEF-OprN efflux pump encoding genes were highly upregulated in the two P. fluorescens strains. Noticeably, similar phenotypes had been previously observed following a NO treatment. Interestingly, an hmp-homologue gene in P. fluorescens strains MFAF76a and MFN1032 encodes a NO dioxygenase that is involved in NO detoxification into nitrites. Its expression was upregulated in response to NO2, suggesting a possible common pathway between NO and NO2 detoxification. Taken

  8. Metabolic engineering of Pseudomonas fluorescens for the production of vanillin from ferulic acid.

    Di Gioia, Diana; Luziatelli, Francesca; Negroni, Andrea; Ficca, Anna Grazia; Fava, Fabio; Ruzzi, Maurizio

    2011-12-20

    Vanillin is one of the most important flavors in the food industry and there is great interest in its production through biotechnological processes starting from natural substrates such as ferulic acid. Among bacteria, recombinant Escherichia coli strains are the most efficient vanillin producers, whereas Pseudomonas spp. strains, although possessing a broader metabolic versatility, rapidly metabolize various phenolic compounds including vanillin. In order to develop a robust Pseudomonas strain that can produce vanillin in high yields and at high productivity, the vanillin dehydrogenase (vdh)-encoding gene of Pseudomonas fluorescens BF13 strain was inactivated via targeted mutagenesis. The results demonstrated that engineered derivatives of strain BF13 accumulate vanillin if inactivation of vdh is associated with concurrent expression of structural genes for feruloyl-CoA synthetase (fcs) and hydratase/aldolase (ech) from a low-copy plasmid. The conversion of ferulic acid to vanillin was enhanced by optimization of growth conditions, growth phase and parameters of the bioconversion process. The developed strain produced up to 8.41 mM vanillin, which is the highest final titer of vanillin produced by a Pseudomonas strain to date and opens new perspectives in the use of bacterial biocatalysts for biotechnological production of vanillin from agro-industrial wastes which contain ferulic acid. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Immobilization of Pseudomonas fluorescens lipase onto magnetic nanoparticles for resolution of 2-octanol.

    Xun, Er-na; Lv, Xiao-li; Kang, Wei; Wang, Jia-xin; Zhang, Hong; Wang, Lei; Wang, Zhi

    2012-10-01

    The lipase from Pseudomonas fluorescens (Lipase AK, AKL) was immobilized onto the magnetic Fe(3)O(4) nanoparticles via hydrophobic interaction. Enzyme loading and immobilization yield were determined as 21.4±0.5 mg/g and 49.2±1.8 %, respectively. The immobilized AKL was successfully used for resolution of 2-octanol with vinyl acetate used as acyl donor. Effects of organic solvent, water activity, substrate ratio, and temperature were investigated. Under the optimum conditions, the preferred isomer for AKL is the (R)-2-octanol and the highest enantioselectivity (E=71.5±2.2) was obtained with a higher enzyme activity (0.197±0.01 μmol/mg/min). The results also showed that the immobilized lipase could be easily separated from reaction media by the magnetic steel and remained 89 % of its initial activity as well as the nearly unchanged enantioselectivity after five consecutive cycles, indicating a high stability in practical operation.

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

    Dagbert, Catherine; Meylheuc, Thierry; Bellon-Fontaine, Marie-Noelle

    2008-01-01

    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)

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

    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)

  12. Effects of high intensity pulsed electric field and thermal treatments on a lipase from Pseudomonas fluorescens.

    Bendicho, S; Estela, C; Giner, J; Barbosa-Cánovas, G V; Martin, O

    2002-01-01

    Milk and dairy products may contain microorganisms capable of secreting lipases that cause sensory defects and technological problems in the dairy industry. In this study, the effects of thermal and high-intensity pulsed electric field (HIPEF) treatments on an extracellular lipase from Pseudomonas fluorescens, suspended in a simulated skim milk ultrafiltrate (SMUF) have been evaluated. Heat treatments applied were up to 30 min from 50 to 90 degrees C. HIPEF treatments were carried out using pilot plant facilities in a batch or continuous flow mode, where treatment chambers consisted of parallel and coaxial configuration, respectively. Samples were subjected to up to 80 pulses at electric field intensities ranging from 16.4 to 37.3 kV/cm. This resulted in a lipase that was quite resistant to heat and also to HIPEF. High (75 degrees C-15 s) and low pasteurization treatments (63 degrees C-30 min) led to inactivations of 5 and 20%, respectively. Using the batch-mode HIPEF equipment, a 62.1% maximum activity depletion was achieved after 80 pulses at 27.4 kV/cm. However, when HIPEF treatments were applied in the continuous flow mode, an inactivation rate of just 13% was achieved, after applying 80 pulses at 37.3 kV/cm and 3.5 Hz. The results of both heat and HIPEF treatments on enzyme inactivation were adjusted with good agreement to a first-order kinetic model (R2 > 62.3%).

  13. Modeling high-intensity pulsed electric field inactivation of a lipase from Pseudomonas fluorescens.

    Soliva-Fortuny, R; Bendicho-Porta, S; Martín-Belloso, O

    2006-11-01

    The inactivation kinetics of a lipase from Pseudomonas fluorescens (EC 3.1.1.3.) were studied in a simulated skim milk ultrafiltrate treated with high-intensity pulsed electric fields. Samples were subjected to electric field intensities ranging from 16.4 to 27.4 kV/cm for up to 314.5 micros, thus achieving a maximum inactivation of 62.1%. The suitability of describing experimental data using mechanistic first-order kinetics and an empirical model based on the Weibull distribution function is discussed. In addition, different mathematical expressions relating the residual activity values to field strength and treatment time are supplied. A first-order fractional conversion model predicted residual activity with good accuracy (A(f) = 1.018). A mechanistic insight of the model kinetics was that experimental values were the consequence of different structural organizations of the enzyme, with uneven resistance to the pulsed electric field treatments. The Weibull model was also useful in predicting the energy density necessary to achieve lipase inactivation.

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

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

    2007-01-01

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

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

    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.

  16. Trichoderma harzianum enhances the production of nematicidal compounds in vitro and improves biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato.

    Siddiqui, I A; Shaukat, S S

    2004-01-01

    To determine the influence of soil-borne fungus Trichoderma harzianum on the biocontrol performance of Pseudomonas fluorescens strain CHA0 and its 2,4-diacetylphloroglucinol (DAPG) overproducing derivative CHA0/pME3424 against Meloidogyne javanica. Amendment of the culture filtrate (CF) or methanol extract of the CF of a T. harzianum strain Th6 to P. fluorescens growth medium enhanced the production of nematicidal compound(s) by bacterial inoculants in vitro. In addition, bacteria overwhelmingly expressed phl'-'lacZ reporter gene when the medium was amended with CF of T. harzianum. Pseudomonas fluorescens and T. harzianum applied together in unsterilized sandy loam soil caused greater reduction in nematode population densities in tomato roots. Trichoderma harzianum improves root-knot nematode biocontrol by the antagonistic rhizobacterium P. fluorescens both in vitro and under glasshouse conditions. The synergistic effect of T. harzianum on the production of nematicidal compound(s) critical in biocontrol may improve the efficacy of biocontrol bacteria against plant-parasitic nematodes. Considering the inconsistent performance of the biocontrol agents under field conditions, application of a mixture of compatible T. harzianum and P. fluorescens would more closely mimic the natural situation and might broaden the spectrum of biocontrol activity with enhanced efficacy and reliability of control.

  17. Type III secretion system and virulence markers highlight similarities and differences between human- and plant-associated pseudomonads related to Pseudomonas fluorescens and P. putida.

    Mazurier, Sylvie; Merieau, Annabelle; Bergeau, Dorian; Decoin, Victorien; Sperandio, Daniel; Crépin, Alexandre; Barbey, Corinne; Jeannot, Katy; Vicré-Gibouin, Maïté; Plésiat, Patrick; Lemanceau, Philippe; Latour, Xavier

    2015-04-01

    Pseudomonas fluorescens is commonly considered a saprophytic rhizobacterium devoid of pathogenic potential. Nevertheless, the recurrent isolation of strains from clinical human cases could indicate the emergence of novel strains originating from the rhizosphere reservoir, which could be particularly resistant to the immune system and clinical treatment. The importance of type three secretion systems (T3SSs) in the related Pseudomonas aeruginosa nosocomial species and the occurrence of this secretion system in plant-associated P. fluorescens raise the question of whether clinical isolates may also harbor T3SSs. In this study, isolates associated with clinical infections and identified in hospitals as belonging to P. fluorescens were compared with fluorescent pseudomonads harboring T3SSs isolated from plants. Bacterial isolates were tested for (i) their genetic relationships based on their 16S rRNA phylogeny, (ii) the presence of T3SS genes by PCR, and (iii) their infectious potential on animals and plants under environmental or physiological temperature conditions. Two groups of bacteria were delineated among the clinical isolates. The first group encompassed thermotolerant (41°C) isolates from patients suffering from blood infections; these isolates were finally found to not belong to P. fluorescens but were closely related and harbored highly conserved T3SS genes belonging to the Ysc-T3SS family, like the T3SSs from P. aeruginosa. The second group encompassed isolates from patients suffering from cystic fibrosis; these isolates belonged to P. fluorescens and harbored T3SS genes belonging to the Hrp1-T3SS family found commonly in plant-associated P. fluorescens. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  18. Effect of Pseudomonas fluorescens and pyoverdine on the phytoextraction of cesium by red clover in soil pots and hydroponics.

    Hazotte, Alice; Péron, Olivier; Gaudin, Pierre; Abdelouas, Abdesselam; Lebeau, Thierry

    2018-05-12

    With the aim of improving the phytoextraction rate of cesium (Cs), the effect of Pseudomonas fluorescens ATCC 17400 and its siderophore pyoverdine (PVD) on the uptake of Cs by red clover was studied in soil pots. This work also provides a mechanistic understanding of the Cs-bacteria (or PVD)-illite-plant interactions by using a simplified experimental design, i.e., hydroponics with either Cs in solution or Cs-spiked illite in suspension. For soil spiked with 11.2 mmol kg -1 (1480 mg kg -1 ) of Cs, 0.43% of total Cs was taken up by red clover in 12 days (119 μmol g -1 (16 mg g -1 ) of Cs dry matter in roots and 40 μmol g -1 (5 mg g -1 ) in shoots). In hydroponics with Cs in solution (0.1 mmol L -1 or 13 mg L -1 ), 75% of Cs was taken up vs. only 0.86% with Cs-spiked illite suspension. P. fluorescens and PVD did not increase Cs concentrations in aboveground parts and roots of red clover and even decreased them. The damaging effect of PVD on red clover growth was demonstrated with the biomass yielding 66% of the control in soil pots (and 100% mortality after 12 days of exposition) and only 56% in hydroponics (78% with illite in suspension). Nonetheless, PVD and, to a lesser extent, P. fluorescens increased the translocation factor up to a factor of 2.8. This study clearly showed a direct damaging effect of PVD and to a lower extent the retention of Cs by biofilm covering both the roots and illite, both resulting in the lower phytoextraction efficiency.

  19. No apparent costs for facultative antibiotic production by the soil bacterium Pseudomonas fluorescens Pf0-1.

    Garbeva, Paolina; Tyc, Olaf; Remus-Emsermann, Mitja N P; van der Wal, Annemieke; Vos, Michiel; Silby, Mark; de Boer, Wietse

    2011-01-01

    Many soil-inhabiting bacteria are known to produce secondary metabolites that can suppress microorganisms competing for the same resources. The production of antimicrobial compounds is expected to incur fitness costs for the producing bacteria. Such costs form the basis for models on the co-existence of antibiotic-producing and non-antibiotic producing strains. However, so far studies quantifying the costs of antibiotic production by bacteria are scarce. The current study reports on possible costs, for antibiotic production by Pseudomonas fluorescens Pf0-1, a soil bacterium that is induced to produce a broad-spectrum antibiotic when it is confronted with non-related bacterial competitors or supernatants of their cultures. We measured the possible cost of antibiotic production for Pseudomonas fluorescens Pf0-1 by monitoring changes in growth rate with and without induction of antibiotic production by supernatant of a bacterial competitor, namely Pedobacter sp.. Experiments were performed in liquid as well as on semi-solid media under nutrient-limited conditions that are expected to most clearly reveal fitness costs. Our results did not reveal any significant costs for production of antibiotics by Pseudomonas fluorescens Pf0-1. Comparison of growth rates of the antibiotic-producing wild-type cells with those of non-antibiotic producing mutants did not reveal costs of antibiotic production either. Based on our findings we propose that the facultative production of antibiotics might not be selected to mitigate metabolic costs, but instead might be advantageous because it limits the risk of competitors evolving resistance, or even the risk of competitors feeding on the compounds produced.

  20. No apparent costs for facultative antibiotic production by the soil bacterium Pseudomonas fluorescens Pf0-1.

    Paolina Garbeva

    Full Text Available BACKGROUND: Many soil-inhabiting bacteria are known to produce secondary metabolites that can suppress microorganisms competing for the same resources. The production of antimicrobial compounds is expected to incur fitness costs for the producing bacteria. Such costs form the basis for models on the co-existence of antibiotic-producing and non-antibiotic producing strains. However, so far studies quantifying the costs of antibiotic production by bacteria are scarce. The current study reports on possible costs, for antibiotic production by Pseudomonas fluorescens Pf0-1, a soil bacterium that is induced to produce a broad-spectrum antibiotic when it is confronted with non-related bacterial competitors or supernatants of their cultures. METHODOLOGY AND PRINCIPAL FINDINGS: We measured the possible cost of antibiotic production for Pseudomonas fluorescens Pf0-1 by monitoring changes in growth rate with and without induction of antibiotic production by supernatant of a bacterial competitor, namely Pedobacter sp.. Experiments were performed in liquid as well as on semi-solid media under nutrient-limited conditions that are expected to most clearly reveal fitness costs. Our results did not reveal any significant costs for production of antibiotics by Pseudomonas fluorescens Pf0-1. Comparison of growth rates of the antibiotic-producing wild-type cells with those of non-antibiotic producing mutants did not reveal costs of antibiotic production either. SIGNIFICANCE: Based on our findings we propose that the facultative production of antibiotics might not be selected to mitigate metabolic costs, but instead might be advantageous because it limits the risk of competitors evolving resistance, or even the risk of competitors feeding on the compounds produced.

  1. IMPACT OF SIPHONING ACTIVITY AND NATURALLY SUSPENDED PARTICLE LOAD ON MUSSEL KILL by PSEUDOMONAS FLUORESCENS

    Daniel Molloy

    2003-01-01

    Under this USDOE-NETL contract, the bacterium Pseudomonas fluorescens is being developed as a biocontrol agent for zebra mussels. The specific purpose of the contract is to identify biotic and abiotic factors that affect mussel kill. Ingestion of these bacteria by zebra mussels is required to achieve kill, and tests evaluating factors that relate to mussel feeding are contained in this report. Specifically the impact of the following two factors were investigated: (1) Mussel siphoning behavior--In nature, zebra mussels typically have their two shells spread apart and their inhalant siphon tube extended from between their shells for taking food particles into their mantle cavities (Fig. 1). Our tests indicated that there is a direct correlation between mussel siphoning activity and mussel mortality achieved by a bacterial treatment. Therefore, to encourage mussel feeding on bacteria, future pipe treatments within power plants should be carried out using procedures which minimize disturbance to mussel siphoning. 2. Naturally suspended particle loads--Since bacterial cells are lethal only if ingested by mussels, waters containing very high levels of naturally suspended particles might reduce the mortality that can be achieved by a bacterial treatment. If true, this inhibition might occur as a result of particle exclusion, i.e., there could be reduced ingestion of bacterial cells since they represent a reduced percentage of all particles ingested. Our tests indicated that a range of particle concentrations that might naturally exist in a turbid river did not inhibit mussel kill by the bacterial cells, but that an artificially high load of natural particles was capable of causing a reduction in kill. To be conservative, therefore, future pipe treatments should be timed to occur when intake waters have relatively low quantities of naturally suspended particulate matter

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

    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.

  3. D-glucose-6-phosphate dehydrogenase (Entner-Doudoroff enzyme) from Pseudomonas fluorescens

    Lessmann, D.; Schimz, K.L.; Kurz, G.

    1975-01-01

    The existence of two different D-glucose-6-phosphate dehydrogenases in Pseudomonas fluorescens has been demonstrated. Based on their different specificity and their different metabolic regulation one enzyme is appointed to the Entner-Doudoroff pathway and the other to the hexose monophosphate pathway. A procedure is described for the isolation of that D-glucose-6-phosphate dehydrogenase which forms part of the Entner-Doudoroff pathway (Entner-Doudoroff enzyme). A 950-fold purification was achieved with an overall yield of 44%. The final preparation, having a specific activity of about 300μmol NADH formed per min per mg protein, was shown to be homogeneous. The molecular weight of the Entner-Doudoroff enzyme has been determined to be 220,000 by gel permeation chromatography, and that of the other enzyme (Zwischenferment) has been shown to be 265,000. The pI of the Entner-Doudoroff enzyme has been shown to be 5.24 and that of the Zwischenferment 4.27. The Entner-Doudoroff enzyme is stable in the range of pH 6 to 10.5 and shows its maximal acivity at pH 8.9. The Entner-Doudoroff enzyme showed specificity for NAD + as well as for NADP + and exhibited homotropic effects for D-glucose 6-phosphate. It is inhibited by ATP which acts as a negative allosteric effector. Other nucleoside triphosphates as well as ADP are also inhibitory. The enzyme catalyzes the transfer of the axial hydrogen at carbon-1 of β-D-glucopyranose 6-phosphate to the si face of carbon-4 of the nicotinamide ring and must be classified as B-side stereospecific dehydrogenase. (orig.) [de

  4. Biodegradation of phenol, salicylic acid, benzenesulfonic acid, and iomeprol by Pseudomonas fluorescens in the capillary fringe.

    Hack, Norman; Reinwand, Christian; Abbt-Braun, Gudrun; Horn, Harald; Frimmel, Fritz H

    2015-12-01

    Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200...600 μm, porosity ε=0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol)=0 after t=6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest. Copyright © 2015 Elsevier B.V. All rights

  5. Lipopeptide biosurfactant viscosin enhances dispersal of Pseudomonas fluorescens SBW25 biofilms.

    Bonnichsen, Lise; Bygvraa Svenningsen, Nanna; Rybtke, Morten; de Bruijn, Irene; Raaijmakers, Jos M; Tolker-Nielsen, Tim; Nybroe, Ole

    2015-12-01

    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 study sets out to determine the specific role of the lipopeptide viscosin in Pseudomonas fluorescens SBW25 biofilm formation, architecture and dispersal, and to relate viscA gene expression to viscosin production and effect. Initially, we compared biofilm formation of SBW25 and the viscosin-deficient mutant strain SBW25ΔviscA in static microtitre assays. These experiments demonstrated that viscosin had little influence on the amount of biofilm formed by SBW25 during the early stages of biofilm development. Later, however, SBW25 formed significantly less biofilm than SBW25ΔviscA. The indication that viscosin is involved in biofilm dispersal was confirmed by chemical complementation of the mutant biofilm. Furthermore, a fluorescent bioreporter showed that viscA expression was induced in biofilms 4 h prior to dispersal. Subsequent detailed studies of biofilms formed in flow cells for up to 5 days revealed that SBW25 and SBW25ΔviscA developed comparable biofilms dominated by well-defined, mushroom-shaped structures. Carbon starvation was required to obtain biofilm dispersal in this system. Dispersal of SBW25 biofilms was significantly greater than of SBW25ΔviscA biofilms after 3 h and, importantly, carbon starvation strongly induced viscA expression, in particular for cells that were apparently leaving the biofilm. Thus, the present study points to a role for viscosin-facilitated motility in dispersal of SBW25 biofilms.

  6. IMPACT OF SIPHONING ACTIVITY AND NATURALLY SUSPENDED PARTICLE LOAD ON MUSSEL KILL by PSEUDOMONAS FLUORESCENS

    Daniel Molloy

    2003-08-04

    Under this USDOE-NETL contract, the bacterium Pseudomonas fluorescens is being developed as a biocontrol agent for zebra mussels. The specific purpose of the contract is to identify biotic and abiotic factors that affect mussel kill. Ingestion of these bacteria by zebra mussels is required to achieve kill, and tests evaluating factors that relate to mussel feeding are contained in this report. Specifically the impact of the following two factors were investigated: (1) Mussel siphoning behavior--In nature, zebra mussels typically have their two shells spread apart and their inhalant siphon tube extended from between their shells for taking food particles into their mantle cavities (Fig. 1). Our tests indicated that there is a direct correlation between mussel siphoning activity and mussel mortality achieved by a bacterial treatment. Therefore, to encourage mussel feeding on bacteria, future pipe treatments within power plants should be carried out using procedures which minimize disturbance to mussel siphoning. 2. Naturally suspended particle loads--Since bacterial cells are lethal only if ingested by mussels, waters containing very high levels of naturally suspended particles might reduce the mortality that can be achieved by a bacterial treatment. If true, this inhibition might occur as a result of particle exclusion, i.e., there could be reduced ingestion of bacterial cells since they represent a reduced percentage of all particles ingested. Our tests indicated that a range of particle concentrations that might naturally exist in a turbid river did not inhibit mussel kill by the bacterial cells, but that an artificially high load of natural particles was capable of causing a reduction in kill. To be conservative, therefore, future pipe treatments should be timed to occur when intake waters have relatively low quantities of naturally suspended particulate matter.

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

    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...

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

    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 biocontrol. PMID:16151170

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

    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...

  10. Novel ambler class A carbapenem-hydrolyzing beta-lactamase from a Pseudomonas fluorescens isolate from the Seine River, Paris, France.

    Girlich, Delphine; Poirel, Laurent; Nordmann, Patrice

    2010-01-01

    A Pseudomonas fluorescens isolate (PF-1) resistant to carbapenems was recovered during an environmental survey performed with water from the Seine River (Paris). It expressed a novel Ambler class A carbapenemase, BIC-1, sharing 68 and 59% amino acid identities with beta-lactamases SFC-1 from Serratia fonticola and the plasmid-encoded KPC-2, respectively. beta-Lactamase BIC-1 hydrolyzed penicillins, carbapenems, and cephalosporins except ceftazidime and monobactams. The bla(BIC-1) gene was chromosomally located and was also identified in two other P. fluorescens strains isolated from the Seine River 3 months later.

  11. The effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on model bacterial strains and isolates from industrial wastewater.

    Vasileva-Tonkova, Evgenia; Sotirova, Anna; Galabova, Danka

    2011-02-01

    In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant, depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain Bacillus subtilis 168. The growth and protein release of model Gram (-) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium. Rhamnolipid biosurfactant at the used concentrations supported the growth of some slow growing on hexadecane bacterial isolates, members of the microbial community. Changes in cell surface hydrophobicity and permeability of some Gram (+) and Gram (-) isolates in the presence of rhamnolipid biosurfactant were followed in experiments in vitro. It was found that bacterial cells treated with biosurfactant became more or less hydrophobic than untreated cells depending on individual characteristics and abilities of the strains. For all treated strains, an increase in the amount of released protein was observed with increasing the amount of biosurfactant, probably due to increased cell permeability as a result of changes in the organization of cell surface structures. The results obtained could contribute to clarify the relationships between members of the microbial community as well as suggest the efficiency of surface properties of rhamnolipid biosurfactant from Pseudomonas fluorescens making it potentially applicable in bioremediation of hydrocarbon-polluted environments.

  12. The study of Bacteriocin of Pseudomonas fluorescens and Citrus limon effects against Propionibacterium acnes and Staphylococcus epidermidis in acne patients

    Ahmed, Mais E.

    2018-05-01

    Research was carried out on the antibacterial effect of (Citrus limon) juice on Acnevulgaris. Samples were obtained from individuals with pimples by swabbing their faces. Natural substances that derive from plants are promising to treat disease cause Acnevulgaris, the study in vitro biological activity of the juice, as well as bacterocin cultivated and fruits was investigated on two strains of bacteria (Propionibacterium acnes, Staphylococcus epidermidis). The new antimicrobial (bacteriocin and Citrus juice) is an ongoing search. This study used juice at different concentrations at (20%, 30%, 40%, 60%, 80% and 100%). The bacteriocin produced from local P. fluorescens isolates from wound infection and majority of isolates were found to produce crude bacteriocin were (P1 and P2) in Pseudomonas agar at 37°C for 24 hrs. Crude bacteriocin and Citrus limon juice against some pathogenic skin bacteria was find to be effective juice Citrus limon aganist S. epidermidis at 100% Concentrations with a range of inhibition zone (18) mm. The isolates of P. fluorescens (P2) was positive as producer of bacteriocin with a wide inhibition growth against gram positive pathogenic bacteria with a range between (10-12) mm.

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

    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.

  14. Role of gallic and p-coumaric acids in the AHL-dependent expression of flgA gene and in the process of biofilm formation in food-associated Pseudomonas fluorescens KM120.

    Myszka, Kamila; Schmidt, Marcin T; Białas, Wojciech; Olkowicz, Mariola; Leja, Katarzyna; Czaczyk, Katarzyna

    2016-09-01

    In the process of Pseudomonas fluorescens biofilm formation, N-acyl-l-homoserine lactone (AHL)-mediated flagella synthesis plays a key role. Inhibition of AHL production may attenuate P. fluorescens biofilm on solid surfaces. This work validated the anti-biofilm properties of p-coumaric and gallic acids via the ability of phenolics to suppress AHL synthesis in P. fluorescens KM120. The dependence between synthesis of AHL molecules, expression of flagella gene (flgA) and the ability of biofilm formation by P. fluorescens KM120 on a stainless steel surface (type 304L) was also investigated. Research was carried out in a purpose-built flow cell device. Limitations on AHL synthesis in P. fluorescens KM120 were observed at concentrations of 120 and 240 µmol L(-1) of phenolic acids in medium. At such levels of gallic and p-coumaric acids the ability of P. fluorescens KM120 to synthesize 3-oxo-C6-homoserine lactone (HSL) was not observed. These concentrations caused decreased expression of flgA gene in P. fluorescens KM120. The changes in expression of AHL-dependent flgA gene significantly decreased the rate of microorganism colonization on the stainless steel surface. Phenolic acids are able to inhibit biofilm formation. The results obtained in the work may help to develop alternative techniques for anti-biofilm treatment in the food industry. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  15. 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

    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.

  16. Conjoint effect of oil-seed cakes and Pseudomonas fluorescens on the growth of chickpea in relation to the management of plant-parasitic nematodes

    Rose Rizvi

    2012-12-01

    Full Text Available Soil application of organics has been explored as an alternative means of organic management of plant-parasitic nematodes. Efficiency of different oil-seed cakes of neem (Azadirachta indica, castor (Ricinus communis, groundnut (Arachis hypogaea, linseed (Linum usitatissimum, sunflower (Helianthus annuus and soybean (Glycine max were evaluated in field conditions with association of Pseudomonas fluorescens in relation to growth parameters of chickpea and population of plant-parasitic nematodes. Their efficacious nature was highly effective in reducing the population of these dominant soil nematodes. Significant improvement was observed in plant-growth parameters such as plant weight, percent pollen fertility, pod numbers, root-nodulation and chlorophyll content of chickpea, seemed to be due to reduction in disease incidence and might be due to growth promoting substances secreted by P. fluorescens. The multiplication rate of nematodes was less in the presence of P. fluorescens as compared to its absence. Most effective combination of P. fluorescens was observed with neem cake.

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

    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.

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

    Stabler, Richard A; Negus, David; Pain, Arnab; Taylor, Peter W

    2013-01-01

    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.

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

    Stabler, Richard A.; Negus, David; Pain, Arnab; Taylor, Peter W.

    2013-01-01

    A mixed culture of Pseudomonas fluorescens BS2 and Pusillimonas noertemannii BS8 degraded poly-?-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.

  20. Isolation and characterization of two new lipopeptide biosurfactants produced by Pseudomonas fluorescens BD5 isolated from water from the Arctic Archipelago of Svalbard

    Janek, T.; Lukaszewicz, M.; Řezanka, Tomáš; Krasowska, A.

    2010-01-01

    Roč. 101, č. 15 (2010), s. 6118-6123 ISSN 0960-8524 Institutional research plan: CEZ:AV0Z50200510 Keywords : Pseudomonas fluorescens BD5 * Lipopeptide * Pseudofactins Subject RIV: EE - Microbiology, Virology Impact factor: 4.365, year: 2010

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

    Stabler, R. A.; Negus, D.; Pain, Arnab; Taylor, P. W.

    2013-01-01

    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.

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

    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. 

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

    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]).

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

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

    2017-01-01

    -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......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...... 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...

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

    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...... disease and fumonisin accumulation, and also to study the capacity to promote growth and yield of maize. In vitro assays were conducted to test the efficacy of P. fluorescens as a seed treatment on seed germination, seedling vigour and also the incidence of F. verticillioides in different maize cultivars....... 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...

  6. Heat Production by the Denitrifying Bacterium Pseudomonas fluorescens and the Dissimilatory Ammonium-Producing Bacterium Pseudomonas putrefaciens during Anaerobic Growth with Nitrate as the Electron Acceptor

    Samuelsson, M.-O.; Cadez, P.; Gustafsson, L.

    1988-01-01

    The heat production rate and the simultaneous nitrate consumption and production and consumption of nitrite and nitrous oxide were monitored during the anaerobic growth of two types of dissimilatory nitrate reducers. Pseudomonas fluorescens, a denitrifier, consumed nitrate and accumulated small amounts of nitrite or nitrous oxide. The heat production rate increased steadily during the course of nitrate consumption and decreased rapidly concomitant with the depletion of the electron acceptors....

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

    Hennessy, Rosanna C.; Phippen, Christopher B. W.; Nielsen, Kristian F.; Olsson, Stefan; Stougaard, Peter

    2017-01-01

    Abstract 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 nun...

  8. Type III secretion system and virulence markers highlight similarities and differences between human- and plant-associated Pseudomonads related to Pseudomonas fluorescens and P-putida

    Mazurier, Sylvie; Merieau, Annabelle; Bergeau, Dorian; Decoin, Victorien; Sperandio, Daniel; Crepin, Alexandre; Barbey, Corinne; Jeannot, Katy; Vicre-Gibouin, Maité; Plesiat, Patrick; Lemanceau, Philippe; Latour, Xavier

    2015-01-01

    Pseudomonas fluorescens is commonly considered a saprophytic rhizobacterium devoid of pathogenic potential. Nevertheless, the recurrent isolation of strains from clinical human cases could indicate the emergence of novel strains originating from the rhizosphere reservoir, which could be particularly resistant to the immune system and clinical treatment. The importance of type three secretion systems (T3SSs) in the related Pseudomonas aeruginosa nosocomial species and the occurrence of this se...

  9. Non-pathogenic Fusarium solani represses the biosynthesis of nematicidal compounds in vitro and reduces the biocontrol of Meloidogyne javanica by Pseudomonas fluorescens in tomato.

    Siddiqui, I A; Shaukat, S S

    2003-01-01

    The aim of the present investigation was to determine the influence of various Fusarium solani strains on the production of nematicidal agent(s) in vitro and biocontrol of Meloidogyne javanica in tomato by Pseudomonas fluorescens strains CHA0 and CHA0/pME3424. Culture filtrates (CF) of P. fluorescens strain CHA0 and its diacetylphloroglucinol-overproducing derivative CHA0/pME3424 caused substantial mortality of M. javanica juveniles in vitro. Bacterial growth medium amended with the growth medium of F. solani repressed the nematicidal activity of the bacteria. Methanol extract of F. solani CF resulting from Czapek's Dox liquid (CDL) medium without zinc amendment repressed the nematicidal activity of the bacteria while the CF obtained from CDL medium amended with zinc did not. Conidial suspension of F. solani strain Fs5 (repressor strain for the biosynthesis of nematicidal compounds in P. fluorescens) reduced biocontrol potential of the bacterial inoculants against M. javanica in tomato while strain Fs3 (non-repressor) did not. Fusarium solani strains with increased nematicidal activity repress the biosynthesis of nematicidal compounds by P. fluorescens strains in vitro and greatly alter its biocontrol efficacy against root-knot nematode under natural conditions. Fusarium solani strains are distributed worldwide and found in almost all the agricultural fields which suggest that some mycotoxin-producing strains will also be found in almost any soil sample taken. Besides the suppressive effect of these metabolite-producing strains on the production of nematicidal compound(s) critical in biocontrol, F. solani strains may also affect the performance of mycotoxin-sensitive biocontrol bacteria effective against plant-parasitic nematodes.

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

    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.

  11. The role of the antimicrobial compound 2,4-diacetylphloroglucinol in the impact of biocontrol Pseudomonas fluorescens F113 on Azospirillum brasilense phytostimulators.

    Couillerot, Olivier; Combes-Meynet, Emeline; Pothier, Joël F; Bellvert, Floriant; Challita, Elita; Poirier, Marie-Andrée; Rohr, René; Comte, Gilles; Moënne-Loccoz, Yvan; Prigent-Combaret, Claire

    2011-06-01

    Pseudomonads producing the antimicrobial metabolite 2,4-diacetylphloroglucinol (Phl) can control soil-borne phytopathogens, but their impact on other plant-beneficial bacteria remains poorly documented. Here, the effects of synthetic Phl and Phl(+) Pseudomonas fluorescens F113 on Azospirillum brasilense phytostimulators were investigated. Most A. brasilense strains were moderately sensitive to Phl. In vitro, Phl induced accumulation of carotenoids and poly-β-hydroxybutyrate-like granules, cytoplasmic membrane damage and growth inhibition in A. brasilense Cd. Experiments with P. fluorescens F113 and a Phl(-) mutant indicated that Phl production ability contributed to in vitro growth inhibition of A. brasilense Cd and Sp245. Under gnotobiotic conditions, each of the three strains, P. fluorescens F113 and A. brasilense Cd and Sp245, stimulated wheat growth. Co-inoculation of A. brasilense Sp245 and Pseudomonas resulted in the same level of phytostimulation as in single inoculations, whereas it abolished phytostimulation when A. brasilense Cd was used. Pseudomonas Phl production ability resulted in lower Azospirillum cell numbers per root system (based on colony counts) and restricted microscale root colonization of neighbouring Azospirillum cells (based on confocal microscopy), regardless of the A. brasilense strain used. Therefore, this work establishes that Phl(+) pseudomonads have the potential to interfere with A. brasilense phytostimulators on roots and with their plant growth promotion capacity.

  12. Adsorption of Th(IV) and Pu(IV) on the surface of Pseudomonas fluorescens and Bacillus subtilis in the presence of desferrioxamine siderophore

    Yoshida, Takahiro; Ozaki, Takuo; Ohnuki, Toshihiko; Francis, Arokiasamy J.

    2005-01-01

    Adsorption of Th(IV) and Pu(IV) on a Gram-negative bacterium Pseudomonas fluorescens and a Gram-positive bacterium Bacillus subtilis in the presence of siderophore desferrioxamine B (DFO) was studied. Thorium(IV) and Pu(IV) were dissociated from DFO during adsorption on the cells. Thorium(IV) adsorption on bacterial cells in the presence of DFO was larger than that of Pu(IV) because of the smaller stability of the Th(IV)-DFO complex than that of the Pu(IV)-DFO complex. On the other hand, adsorption of Pu(IV) was larger than that of Fe(III), wherein the stability of the Pu(IV)- and Fe(III)-DFO complex is comparable. P. fluorescens showed a higher affinity for Th(IV) and Pu(IV) than B. subtilis, though potentiometric titration of bacterial cells indicated that surfaces of P. fluorescens and B. subtilis cells showed similar proton binding properties. (author)

  13. Structure of a putative BenF-like porin from Pseudomonas fluorescens Pf-5 at 2.6 A resolution

    Sampathkumar, P.; Swaminathan, S.; Lu, F.; Zhao, X.; Li, Z.; Gilmore, J.; Bain, K.; Rutter, M. E.; Gheyi, T.; Schwinn, D.; Bonanno, J. B.; Pieper, U.; Fajardo, J. E.; Fiser, A.; Almo, S. C.; Chance, M. R.; Baker, D.; Atwell, S.; Thompson, D. A.; Emtage, J. S.; Wasserman, S. R.; Sali, A.; Sauder, J. M.; Burley, S. K.

    2010-11-01

    Gram-negative bacteria typically overcome poor permeability of outer membranes through general porins like OmpF and OmpC, which form water-filled transmembrane pores permitting diffusion of hydrophilic molecules with no particular selectivity. Many bacteria lacking such general porins use substrate-specific porins to overcome growth-limiting conditions and facilitate selective transport of metabolites. Exclusive reliance on substrate-specific porins yields lower membrane permeability to small molecules (<600 Da) versus that seen for Escherichia coli. In Pseudomonads, transit of most small molecules across the cell membrane is thought to be mediated by substrate-specific channels of the OprD superfamily. This property explains, at least in part, the high incidence of Pseudomonas aeruginosa antibiotic resistance. High-throughput DNA sequencing of the P. aeruginosa chromosome revealed the presence of 19 genes encoding structurally related, substrate-specific porins (with 30-45% pairwise amino acid sequence identity) that mediate transmembrane passage of small, water-soluble compounds. The OprD superfamily encompasses the eponymous OprD subfamily, which includes 9 P. aeruginosa proteins that convey basic amino acids and carbapenem antibiotics, and the OpdK subfamily, which includes 11 P. aeruginosa proteins that convey aromatic acids and other small aromatic compounds. Genome sequencing of other gram-negative bacteria has revealed additional members of the OprD and OpdK subfamilies in various organisms, including other pseudomonads. Among the many bacteria in which OprD superfamily members have been identified are P. putida, P. fluorescens Pf-5, P. syringae, and Azotobacter vinelandii, all of which share closely related genes that encode the so-called BenF-like porins. In P. putida, benF is part of an operon involved in benzoate catabolism regulated by benR. Within this operon, benK, benE, and benF genes have been suggested to contribute toward either influx or efflux

  14. Measurement of glucose utilization by Pseudomonas fluorescens that are free-living and that are attached to surfaces

    Fletcher, M.

    1986-01-01

    The assimilation and respiration of glucose by attached and free-living Pseudomonas fluorescens were compared. The attachment surfaces were polyvinylidene fluoride, polyethylene, and glass. Specific uptake of [ 1 C]glucose was determined after bacterial biomass was measured by (1) microscopic counts or (2) prelabelling of cells by providing [ 3 H]leucine as substrate, followed by dual-labelling scintillation counting. The glucose concentration was 1.4, 3.5, 5.5, 7.6, or 9.7 μM. Glucose assimilation by cells which became detached from the surfaces during incubation with glucose was also measured after the detached cells were collected by filtration. The composition of the substratum had no effect on the amount of glucose assimilated by attached cells. Glucose assimilation by attached cells exceeded that by free-living cells by a factor of between 2 and 5 or more, and respiration of glucose by surface-associated cells was greater than that by free-living bacteria. Glucose assimilation by detached cells was greater than that by attached bacteria. Measurements of biomass by microscopic counts gave more consistent results than those obtained with dual-labelling, but in general, results obtained by both methods were corroborative

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

    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.

  16. Pseudomonas fluorescens ATCC 13525 Containing an Artificial Oxalate Operon and Vitreoscilla Hemoglobin Secretes Oxalic Acid and Solubilizes Rock Phosphate in Acidic Alfisols

    Archana, G.; Naresh Kumar, G.

    2014-01-01

    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. PMID:24705024

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

    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.

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

    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.

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

    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.

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

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

    Pseudomonas spp. are a rich source of secondary metabolites including bioactive non-ribosomal peptides (NRPs) and polyketides. NRPs are synthesised in large assembly lines by multi-domain modular enzymes known as NRP-synthetases (NRPS). Nunamycin and nunapeptin are two cyclic NRPs synthesised...... by the Greenlandic isolate P. fluorescens In5. Nunamycin shows antifungal activity against the basidiomycete Rhizoctonia solani whereas the only partially structure elucidated nunapeptin appears most active against the ascomycete Fusarium graminearum and the oomycete Pythium aphanidermatum. Originally isolated from...

  1. Pseudomonas fluorescens ATCC 13525 Containing an Artificial Oxalate Operon and Vitreoscilla Hemoglobin Secretes Oxalic Acid and Solubilizes Rock Phosphate in Acidic Alfisols

    Yadav, Kavita; Kumar, Chanchal; Archana, G.; Naresh Kumar, G.

    2014-01-01

    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) s...

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

    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.

  3. Efeito da pré-incubação de Pseudomonas fluorescens em diferentes temperaturas de refrigeração sobre a hidrólise de caseína no leite desnatado pasteurizado microfiltrado

    Netto, Gabriel Gama

    2012-01-01

    Este trabalho objetivou avaliar o efeito da multiplicação de uma estirpe psicrotrófica proteolítica de Pseudomonas fluorescens nas temperaturas de 4, 7 e 10 ºC, estabelecidas pela Instrução Normativa 62 do MAPA, nas características físicoquímicas e proteólise do leite microfiltrado. Amostras leite desnatado e pasteurizado foram inoculadas com a cepa Pseudomonas fluorescens 041 em uma concentração de aproximadamente 104 UFC mL-1 e incubadas nas três temperaturas por 48 h e, posteriormente, ...

  4. Lipid transfer proteins and protease inhibitors as key factors in the priming of barley responses to Fusarium head blight disease by a biocontrol strain of Pseudomonas fluorescens.

    Petti, Carloalberto; Khan, Mojibur; Doohan, Fiona

    2010-11-01

    Strains of non-pathogenic pseudomonad bacteria, can elicit host defence responses against pathogenic microorganisms. Pseudomonas fluorescens strain MKB158 can protect cereals from pathogenesis by Fusarium fungi, including Fusarium head blight which is an economically important disease due to its association with both yield loss and mycotoxin contamination of grain. Using the 22 K barley Affymetrix chip, trancriptome studies were undertaken to determine the local effect of P. fluorescens strain MKB158 on the transcriptome of barley head tissue, and to discriminate transcripts primed by the bacterium to respond to challenge by Fusarium culmorum, a causal agent of the economically important Fusarium head blight disease of cereals. The bacterium significantly affected the accumulation of 1203 transcripts and primed 74 to positively, and 14 to negatively, respond to the pathogen (P = 0.05). This is the first study to give insights into bacterium priming in the Triticeae tribe of grasses and associated transcripts were classified into 13 functional classes, associated with diverse functions, including detoxification, cell wall biosynthesis and the amplification of host defence responses. In silico analysis of Arabidopsis homologs of bacterium-primed barley genes indicated that, as is the case in dicots, jasmonic acid plays a role in pseudomonad priming of host responses. Additionally, the transcriptome studies described herein also reveal new insights into bacterium-mediated priming of host defences against necrotrophs, including the positive effects on grain filling, lignin deposition, oxidative stress responses, and the inhibition of protease inhibitors and proteins that play a key role in programmed cell death.

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

    Hennessy, Rosanna C; Phippen, Christopher B W; Nielsen, Kristian F; Olsson, Stefan; Stougaard, Peter

    2017-12-01

    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 was reduced in a nunF knockout mutant suggesting that these CLPs may also play a role in these phenomena as observed in other pseudomonads. Fusion of the nunF promoter region to mCherry showed that nunF is strongly upregulated in response to carbon sources indicating the presence of a fungus suggesting that environmental elicitors may also influence nunF expression which upon activation regulates nunamycin and nunapeptin production required for the growth inhibition of phytopathogens. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  6. Interaction between the Bacterium Pseudomonas fluorescens strain CHA0, its genetic derivatives and vermiculite: Effects on chemical, mineralogical and mechanical properties of vermiculite

    Mueller, Barbara

    2016-04-01

    Using bacteria of the strain Pseudomonas fluorescens wild type CHA0 and its genetic derivative strains CHA77, CHA89, CHA400, CHA631 and CHA661 (which differ in one gene only) the changes in chemical, mineralogical and rheological properties of the clay mineral vermiculite affected by microbial activity were studied in order to test whether the individually different production of metabolites by the genetically engineered strains may alter the clay mineral vermiculite in distinct ways. With the novel strategy of working with living wild type bacteria, their genetic derivatives and clay, the following properties of the mineral altered by the various strains of Pseudomonas fluorescens were determined: grain size, X-Ray diffraction pattern, intercrystalline swelling with glycerol, layer charge, CEC, BET surface and uptake of trace elements. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to determine the changes in major, minor and trace elements of the clay vermiculite affected by microbial activity. Among all analyzed trace elements, Fe, Mn and Cu are the most interesting. Fe and Mn are taken up from the clay mineral by all bacterial strains whereas Cu is only removed from vermiculite by strains CHA0, CHA77, CHA400 and CHA661. The latter mentioned strains all produce the antibiotics 2,4-diacetylphloroglucinol and monoacetylphloroglucinol which can complex Cu efficiently. Therefore the alteration of only one gene of the bacteria is causing significant effects on the clay mineral.

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

    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.

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

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

    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

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

    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

  11. Identification of copper-induced genes in Pseudomonas fluorescens and use of a reporter strain to monitor bioavailable copper in soil

    Tom-Petersen, Andreas; Hosbond, Carsten; Nybroe, Ole

    2001-01-01

    -amended soil microcosms in a concentration-dependent manner. The chelator EDTA reduced the availability of Cu to P. fluorescens in soil. This showed that complex-bound Cu is not necessarily available to bacteria, We compared chemical analysis of soluble Cu and the reporter assay on soil solutions from Cu-containing......-Cu15, the gene interrupted by the transposon encoded a protein carrying a Cu-binding domain but with low homology to known proteins. DF57-Cu15 was the most suitable Cu reporter due to its high specific response and tolerance to Cu in pure culture. DF57-Cu15 responded to soil solutions from Cu...... soil microcosms supplemented with either manure or straw. Organic matter increased the amount of soluble Cu but not the amount of bioavailable Cu. Probably, Cu binds with high affinity to organic constituents in pig manure or barley straw. Hence, determination of soluble Cu by chemical analysis cannot...

  12. Bacterial attack on phenolic ethers. Purification and characterization of the components of the meta O-dealkylase of Pseudomonas fluorescens Tp.

    Pietrowski, R A; Cartwright, N J

    1977-01-01

    The meta O-dealkylase of Pseudomonas fluorescens Tp has been resolved into two protein components, neither of which is a cytochrome. The substrate binding terminal oxidase has been purified and shown to be a non-haem iron protein of approximate molecular weight 118,000, consisting of two seemingly identical subunits, each of molecular weight 55,000. Binding of substrate by the terminal oxidase has been established by difference spectroscopy. The amino acid composition of the protein has also been determined. The NADH-dependent reductase of the system has been partly purified and appears to have a molecular weight of 80,000. The similarity between this and other bacterial O-dealkylases is discussed.

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

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

    2017-01-01

    -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...... that environmental elicitors may also influence nunF expression which upon activation regulates nunamycin and nunapeptin production required for the growth inhibition of phytopathogens....

  14. Endophytic Bacterium Pseudomonas fluorescens RG11 May Transform Tryptophan to Melatonin and Promote Endogenous Melatonin Levels in the Roots of Four Grape Cultivars.

    Ma, Yaner; Jiao, Jian; Fan, Xiucai; Sun, Haisheng; Zhang, Ying; Jiang, Jianfu; Liu, Chonghuai

    2016-01-01

    Endophytes have been verified to synthesize melatonin in vitro and promote abiotic stress-induced production of endogenous melatonin in grape ( Vitis vinifera L.) roots. This study aimed to further characterize the biotransformation of tryptophan to melatonin in the endophytic bacterium Pseudomonas fluorescens RG11 and to investigate its capacity for enhancing endogenous melatonin levels in the roots of different grape cultivars. Using ultra performance liquid chromatography-tandem mass spectrometry combined with 15N double-labeled L -tryptophan as the precursor for melatonin, we detected isotope-labeled 5-hydroxytryptophan, serotonin, N -acetylserotonin, and melatonin, but tryptamine was not detected during the in vitro incubation of P. fluorescens RG11. Furthermore, the production capacity of these four compounds peaked during the exponential growth phase. RG11 colonization increased the endogenous levels of 5-hydroxytryptophan, N -acetylserotonin, and melatonin, but reduced those of tryptamine and serotonin, in the roots of the Red Globe grape cultivar under salt stress conditions. Quantitative real-time PCR revealed that RG11 reduced the transcription of grapevine tryptophan decarboxylase and serotonin N -acetyltransferase genes when compared to the un-inoculated control. These results correlated with decreased reactive oxygen species bursts and cell damage, which were alleviated by RG11 colonization under salt stress conditions. Additionally, RG11 promoted plant growth and enhanced the levels of endogenous melatonin in different grape cultivars. Intraspecific variation in the levels of melatonin precursors was found among four grape cultivars, and the associated root crude extracts appeared to significantly induce RG11 melatonin biosynthesis in vitro . Overall, this study provides useful information that enhances the existing knowledge of a potential melatonin synthesis pathway in rhizobacteria, and it reveals plant-rhizobacterium interactions that affect

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

    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.

  16. The periplasmic transaminase PtaA of Pseudomonas fluorescens converts the glutamic acid residue at the pyoverdine fluorophore to α-ketoglutaric acid.

    Ringel, Michael T; Dräger, Gerald; Brüser, Thomas

    2017-11-10

    The periplasmic conversion of ferribactin to pyoverdine is essential for siderophore biogenesis in fluorescent pseudomonads, such as pathogenic Pseudomonas aeruginosa or plant growth-promoting Pseudomonas fluorescens The non-ribosomal peptide ferribactin undergoes cyclizations and oxidations that result in the fluorophore, and a strictly conserved fluorophore-bound glutamic acid residue is converted to a range of variants, including succinamide, succinic acid, and α-ketoglutaric acid residues. We recently discovered that the pyridoxal phosphate-containing enzyme PvdN is responsible for the generation of the succinamide, which can be hydrolyzed to succinic acid. Based on this, a distinct unknown enzyme was postulated to be responsible for the conversion of the glutamic acid to α-ketoglutaric acid. Here we report the identification and characterization of this enzyme in P. fluorescens strain A506. In silico analyses indicated a periplasmic transaminase in fluorescent pseudomonads and other proteobacteria that we termed PtaA for " p eriplasmic t ransaminase A " An in-frame-deleted ptaA mutant selectively lacked the α-ketoglutaric acid form of pyoverdine, and recombinant PtaA complemented this phenotype. The ptaA / pvdN double mutant produced exclusively the glutamic acid form of pyoverdine. PtaA is homodimeric and contains a pyridoxal phosphate cofactor. Mutation of the active-site lysine abolished PtaA activity and affected folding as well as Tat-dependent transport of the enzyme. In pseudomonads, the occurrence of ptaA correlates with the occurrence of α-ketoglutaric acid forms of pyoverdines. As this enzyme is not restricted to pyoverdine-producing bacteria, its catalysis of periplasmic transaminations is most likely a general tool for specific biosynthetic pathways. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

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

    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.

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

    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.

  19. Role of ptsP, orfT, and sss recombinase genes in root colonization by Pseudomonas fluorescens Q8r1-96.

    Mavrodi, Olga V; Mavrodi, Dmitri V; Weller, David M; Thomashow, Linda S

    2006-11-01

    Pseudomonas fluorescens Q8r1-96 produces 2,4-diacetylphloroglucinol (2,4-DAPG), a polyketide antibiotic that suppresses a wide variety of soilborne fungal pathogens, including Gaeumannomyces graminis var. tritici, which causes take-all disease of wheat. Strain Q8r1-96 is representative of the D-genotype of 2,4-DAPG producers, which are exceptional because of their ability to aggressively colonize and maintain large populations on the roots of host plants, including wheat, pea, and sugar beet. In this study, three genes, an sss recombinase gene, ptsP, and orfT, which are important in the interaction of Pseudomonas spp. with various hosts, were investigated to determine their contributions to the unusual colonization properties of strain Q8r1-96. The sss recombinase and ptsP genes influence global processes, including phenotypic plasticity and organic nitrogen utilization, respectively. The orfT gene contributes to the pathogenicity of Pseudomonas aeruginosa in plants and animals and is conserved among saprophytic rhizosphere pseudomonads, but its function is unknown. Clones containing these genes were identified in a Q8r1-96 genomic library, sequenced, and used to construct gene replacement mutants of Q8r1-96. Mutants were characterized to determine their 2,4-DAPG production, motility, fluorescence, colony morphology, exoprotease and hydrogen cyanide (HCN) production, carbon and nitrogen utilization, and ability to colonize the rhizosphere of wheat grown in natural soil. The ptsP mutant was impaired in wheat root colonization, whereas mutants with mutations in the sss recombinase gene and orfT were not. However, all three mutants were less competitive than wild-type P. fluorescens Q8r1-96 in the wheat rhizosphere when they were introduced into the soil by paired inoculation with the parental strain.

  20. Exploiting genotypic diversity of 2,4-diacetylphloroglucinol-producing Pseudomonas spp.: characterization of superior root-colonizing P. fluorescens strain Q8r1-96.

    Raaijmakers, J M; Weller, D M

    2001-06-01

    The genotypic diversity that occurs in natural populations of antagonistic microorganisms provides an enormous resource for improving biological control of plant diseases. In this study, we determined the diversity of indigenous 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas spp. occurring on roots of wheat grown in a soil naturally suppressive to take-all disease of wheat. Among 101 isolates, 16 different groups were identified by random amplified polymorphic DNA (RAPD) analysis. One RAPD group made up 50% of the total population of DAPG-producing Pseudomonas spp. Both short- and long-term studies indicated that this dominant genotype, exemplified by P. fluorescens Q8r1-96, is highly adapted to the wheat rhizosphere. Q8r1-96 requires a much lower dose (only 10 to 100 CFU seed(-1) or soil(-1)) to establish high rhizosphere population densities (10(7) CFU g of root(-1)) than Q2-87 and 1M1-96, two genotypically different, DAPG-producing P. fluorescens strains. Q8r1-96 maintained a rhizosphere population density of approximately 10(5) CFU g of root(-1) after eight successive growth cycles of wheat in three different, raw virgin soils, whereas populations of Q2-87 and 1M1-96 dropped relatively quickly after five cycles and were not detectable after seven cycles. In short-term studies, strains Q8r1-96, Q2-87, and 1M1-96 did not differ in their ability to suppress take-all. After eight successive growth cycles, however, Q8r1-96 still provided control of take-all to the same level as obtained in the take-all suppressive soil, whereas Q2-87 and 1M1-96 gave no control anymore. Biochemical analyses indicated that the superior rhizosphere competence of Q8r1-96 is not related to in situ DAPG production levels. We postulate that certain rhizobacterial genotypes have evolved a preference for colonization of specific crops. By exploiting diversity of antagonistic rhizobacteria that share a common trait, biological control can be improved significantly.

  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

    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. Polymorphism of a lipid extract from Pseudomonas fluorescens: Structure analysis of a hexagonal phase and of a novel cubic phase of extinction symbol Fd--

    Mariani, P.; Rivas, E.; Delacroix, H.; Luzzati, V.

    1990-01-01

    The phase diagram of the Pseudomonas fluorescens lipid extract is unusual, in the sense that it displays a cubic phase straddled by a hexagonal phase. The hexagonal phase was studied over an extended concentration range, and the reflections were phased on the assumption that the structure contains circular cylinders of known radius. The cubic phase, whose extinction symbol is Fd--, was analyzed by reference to space group No. 227 (Fd3m). The phases of the reflections were determined by using a novel pattern recognition approach, based upon the notion that the average fourth power of the electron density contrast 4 > is dependent on chemical composition but not on physical structure, provided that the function Δr(r) satisfies the constraints = 0 and 2 > = 1. The authors analyzed two cubic samples of different composition: for each of them they generated all the phase combinations compatible with the X-ray scattering data and they searched for those whose 4 > best agrees with the hexagonal phase. They concluded that the chemical composition of the phases being compared must be identical, that the X-ray scattering data should not be truncated artificially, and that the apodization must be mild so that the curvature takes a value intermediate between those corresponding to the raw data of the two phases. The structure may be visualized as a 3D generalization of the lipid monolayer. The structure, moreover, does not belong to the class of the infinite periodic surfaces without intersections

  3. Pseudomonas fluorescens JH 70-4 promotes pb stabilization and early seedling growth of sudan grass in contaminated mining site soil.

    Shim, Jaehong; Babu, A Giridhar; Velmurugan, Palanivel; Shea, Patrick J; Oh, Byung-Taek

    2014-01-01

    A bacterial strain (JH 70-4) exhibiting plant growth promoting characteristics (indoleacetic acid production and 1-aminocyclopropane-1-carboxylate deaminase activity), as well as heavy metal(loid) (HM) tolerance and Pb precipitation, was isolated from HM-contaminated soil at an abandoned mine site. The bacterium was identified as Pseudomonas fluorescens based on 16S rDNA sequencing. The JH 70-4 strain induced precipitation of Pb as PbS nanoparticles, confirmed by X-ray diffraction. Solution pH, incubation time, and Pb concentration influenced removal and PbS formation. Inoculating contaminated soil with JH 70-4 decreased Pb availability; exchangeable Pb decreased while organic- and sulphide-bound Pb increased. The toxicity characteristic leaching procedure showed a 65% decrease in Pb in leachate 60 d after inoculating soil with JH 70-4. Shoot and root lengths of Sudan grass grown in the inoculated soil were greater than in the uninoculated soil. Findings suggest that microbial Pb fixation is a viable strategy for remediating soil and promoting plant growth for phytostabilization of contaminated sites.

  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

    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

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

    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.

  7. Phenylacetic acid-producing Rhizoctonia solani represses the biosynthesis of nematicidal compounds in vitro and influences biocontrol of Meloidogyne incognita in tomato by Pseudomonas fluorescens strain CHA0 and its GM derivatives.

    Siddiqui, I A; Shaukat, S S

    2005-01-01

    The aim of the present investigation was to determine the influence of Rhizoctonia solani and its pathogenicity factor on the production of nematicidal agent(s) by Pseudomonas fluorescens strain CHA0 and its GM derivatives in vitro and nematode biocontrol potential by bacterial inoculants in tomato. One (Rs7) of the nine R. solani isolates from infected tomato roots inhibited seedling emergence and caused root rot in tomato. Thin layer chromatography revealed that culture filtrates of two isolates (Rs3 and Rs7) produced brown spots at Rf-values closely similar to synthetic phenylacetic acid (PAA), a phytotoxic factor. Filtrates from isolate Rs7, amended with the growth medium of P. fluorescens, markedly repressed nematicidal activity and PhlA'-'LacZ reporter gene expression of the bacteria in vitro. On the contrary, isolate Rs4 enhanced nematicidal potential of a 2,4-diacetylphloroglucinol overproducing mutant, CHA0/pME3424, of P. fluorescens strain CHA0 in vitro. Therefore, R. solani isolates Rs4 and Rs7 were tested more rigorously for their potential to influence biocontrol effectiveness of the bacterial agents. Methanol extract of the culture filtrates of PAA-producing isolate Rs7 resulting from medium amended with phenylalanine enhanced fungal repression of the production of nematicidal agents by bacteria, while amendments with zinc or molybdenum eliminated such fungal repression, thereby restoring bacterial potential to cause nematode mortality in vitro. A pot experiment was carried out, 3-week-old tomato seedlings were infested with R. solani isolates Rs4 or Rs7 and/or inoculated with Meloidogyne incognita, the root-knot nematode. The infested soil was treated with aqueous cell suspensions (10(8) CFU) of P. fluorescens strain CHA0 or its GM derivatives or left untreated (as a control). Observations taken 45 days after nematode inoculation revealed that, irrespective of the bacterial treatments, galling intensity per gram of fresh tomato roots was markedly

  8. Impact of biocontrol Pseudomonas fluorescens CHA0 and a genetically modified derivative on the diversity of culturable fungi in the cucumber rhizosphere.

    Girlanda, M; Perotto, S; Moenne-Loccoz, Y; Bergero, R; Lazzari, A; Defago, G; Bonfante, P; Luppi, A M

    2001-04-01

    Little is known about the effects of Pseudomonas biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent Pseudomonas fluorescens CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including Pythium spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium, and Monocillium) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day

  9. Enhanced biosorption of mercury(II) and cadmium(II) by cold-induced hydrophobic exobiopolymer secreted from the psychrotroph Pseudomonas fluorescens BM07

    Zamil, Sheikh Shawkat; Choi, Mun Hwan; Song, Jung Hyun; Park, Hyunju; Xu, Ju; Yoon, Sung Chul [Gyeongsang National Univ., Jinju (Korea). Nano-Biomaterials Science Lab.; Chi, Ki-Whan [Ulsan Univ. (Korea). Dept. of Chemistry

    2008-09-15

    The cells of psychrotrophic Pseudomonas fluorescens BM07 were found to secrete large amounts of exobiopolymer (EBP) composed of mainly hydrophobic (water insoluble) polypeptide(s) (as contain {proportional_to}50 mol% hydrophobic amino acids, lacking cysteine residue) when grown on fructose containing limited M1 medium at the temperatures as low as 0-10 C but trace amount at high (30 C, optimum growth) temperature. Two types of nonliving BM07 cells (i.e., cells grown at 30 C and 10 C) as well as the freeze-dried EBP were compared for biosorption of mercury (Hg(II)) and cadmium (Cd(II)). The optimum adsorption pH was found 7 for Hg(II) but 6 for Cd(II), irrespective of the type of biomass. Equilibrium adsorption data well fitted the Langmuir adsorption model. The maximum adsorption (Q{sub max}) was 72.3, 97.4, and 286.2 mg Hg(II)/g dry biomass and 18.9, 27.0, and 61.5 mg Cd(II)/g dry biomass for cells grown at 30 C and 10 C and EBP, respectively, indicating major contribution of heavy metal adsorption by cold-induced EBP. Mercury(II) binding induced a significant shift of infrared (IR) amide I and II absorption of EBP whereas cadmium(II) binding showed only a very little shift. These IR shifts demonstrate that mercury(II) and cadmium(II) might have different binding sites in EBP, which was supported by X-ray diffraction and differential scanning calorimetric analysis and sorption results of chemically modified biomasses. This study implies that the psychrotrophs like BM07 strain may play an important role in the bioremediation of heavy metals in the temperate regions especially in the inactive cold season. (orig.)

  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

    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. Transcriptomic profiling of microbe-microbe interactions reveals the specific response of the biocontrol strain P. fluorescens In5 to the phytopathogen Rhizoctonia solani

    Hennessy, Rosanna Catherine; Glaring, Mikkel Andreas; Olsson, Stefan

    2017-01-01

    reads per sample. RESULTS: No significant changes in global gene expression were recorded during dual-culture of P. fluorescens In5 with any of the two pathogens but rather each pathogen appeared to induce expression of a specific set of genes. A particularly strong transcriptional response to R. solani...... and in particular the fungus R. solani. This highlights the importance of studying microbe-microbe interactions to gain a better understanding of how different systems function in vitro and ultimately in natural systems where biocontrol agents can be used for the sustainable management of plant diseases....

  12. Prokaryotic Homologs of the Eukaryotic 3-Hydroxyanthranilate 3,4-Dioxygenase and 2-Amino-3-Carboxymuconate-6-Semialdehyde Decarboxylase in the 2-Nitrobenzoate Degradation Pathway of Pseudomonas fluorescens Strain KU-7†

    Muraki, Takamichi; Taki, Masami; Hasegawa, Yoshie; Iwaki, Hiroaki; Lau, Peter C. K.

    2003-01-01

    The 2-nitrobenzoic acid degradation pathway of Pseudomonas fluorescens strain KU-7 proceeds via a novel 3-hydroxyanthranilate intermediate. In this study, we cloned and sequenced a 19-kb DNA locus of strain KU-7 that encompasses the 3-hydroxyanthranilate meta-cleavage pathway genes. The gene cluster, designated nbaEXHJIGFCDR, is organized tightly and in the same direction. The nbaC and nbaD gene products were found to be novel homologs of the eukaryotic 3-hydroxyanthranilate 3,4-dioxygenase a...

  13. 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

    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.

  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

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

    2012-01-01

    -colonies were able to utilize this resource, while planktonic cells were not. Our experiments are the first to experimentally support models predicting that production of extra-cellular enzymes in dilute environments may be a waste of resources, whereas it represents a favorable feeding strategy in organic...... and there was no evidence for cell density-regulated or starvation-induced proteinase production. Proteinase was produced in the absence of an organic nitrogen source, and citrate had a negative while glucose had a positive effect on the production. Hence P. fluorescens ON2 seems to exploit protein sources by expressing...

  15. 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

    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

  16. 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.

    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.

  17. Quantification of Pseudomonas fluorescens strains F113, CHA0 and Pf153 in the rhizosphere of maize by strain-specific real-time PCR unaffected by the variability of DNA extraction efficiency.

    Von Felten, Andreas; Défago, Geneviève; Maurhofer, Monika

    2010-05-01

    Pseudomonas fluorescens strains F113 and CHA0 are well-known plant growth-promoting rhizobacteria (PGPR) often used as model strains in biocontrol experiments. To monitor their persistence in large scale field experiments, culture-independent methods are needed. In this study, a strain-specific real-time PCR quantification tool was developed based on sequence-characterized amplified regions (SCAR) for P. fluorescens strains F113, CHA0 and Pf153. Differences in DNA extraction efficiencies from rhizosphere samples were circumvented using plasmid APA9 as internal standard to normalize C(T) values after real-time amplification. The detection limits of the real-time PCR assays for all three strains were approximately 10 cells for genomic DNA and 10(4)cells/g rhizosphere for maize samples grown in different natural soils. Population sizes of the three strains in the rhizosphere of maize measured by the new real-time PCR approaches were similar to those measured by most probable number (MPN)-PCR. A persistence study of the three strains indicated that the strains persisted differently over a period of 5weeks. In conclusion the newly developed real-time PCR approach is a fast and resource efficient method for monitoring individual biocontrol strains in natural soil, which makes it an apt quantification tool for future large-scale field experiments. Copyright 2010 Elsevier B.V. All rights reserved.

  18. 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

    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.

  19. Regulation of Soluble Phosphate on the Ability of Phytate Mineralization and β-Propeller Phytase Gene Expression of Pseudomonas fluorescens JZ-DZ1, a Phytate-Mineralizing Rhizobacterium.

    Shen, Lan; Wu, Xiao-Qin; Zeng, Qing-Wei; Liu, Hong-Bin

    2016-12-01

    Phytate-mineralizing rhizobacteria (PMR) play an important role in providing phosphorus for the sustainable plant growth. It is important to investigate the ability of PMR to produce phytase under different phosphate levels for its application. The effects of different concentrations of soluble phosphate on the ability of phytate mineralization of Pseudomonas fluorescens JZ-DZ1, a phytate-mineralizing rhizobacterium, were investigated in both solid and liquid media. The results on solid media showed that halo zone width gradually reduced with concentrations of soluble phosphate increasing from 0.05 to 20 mM, indicating the reduction of the ability of phytate mineralization. The results were consistent with the quantitative detection of phytase activity from the overall trend. An 1866-bp β-propeller phytase (BPP) gene (phyPf) was cloned from the strain, and the deduced amino acid sequence of phyPf shared 98 % of identity with a known BPP from Pseudomonas sp. BS10-3 (AJF36073.1). The results of relative real-time quantitative PCR assay showed that the expression of phyPf was induced by a low concentration (0.1 mM) of soluble phosphate, suggesting that BPP secretion was regulated by gene phyPf. The BPP-harboring bacterium P. fluorescens JZ-DZ1 with low phosphate-inducible ability of phytate mineralization could be potentially applied to promote phosphorus uptake for plants in the future.

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

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

    Johansen, A.; Knudsen, I. M. B.; Binnerup, S. 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...... 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...... 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...

  2. Análisis de las polihidroxialcanoato sintasas (PhaC1 y PhaC2 en una cepa de Pseudomonas fluorescens IBUN S1602, aislada en suelos colombianos

    Julieth Serrano Riaño

    2011-07-01

    Full Text Available Título en ingles: Analysis of polyhydroxyalkanoate synthases (PhaC1 and PhaC2 in a strain of Pseudomonas fluorescens   IBUN S1602 isolated from Colombian soil. Resumen La cepa Pseudomonas fluorescens IBUN S1602 conforma el grupo de aislamientos provenientes de suelos colombianos de caña de azúcar, que acumula polihidrioxialcanoato (PHA, fue seleccionada como promisoria para escalamiento comercial por tener afinidad por sustratos alternativos y económicos como el glicerol, aceites usados, suero de leche, entre otros. Dada la importancia de la enzima sintasa en la síntesis de los PHAs, en el presente trabajo se realizó el análisis molecular de los genes phaC1 y phaC2 que codifican las enzimas sintasas tipo II (PhaC1 y PhaC2. Para la obtención de los amplímeros requeridos en la secuenciación, se utilizó la técnica de PCR bajo condiciones estandarizadas para iniciadores diseñados reportados en las bases de datos. Se identificaron dos fragmentos de 1680 pb y 1683 pb correspondientes a  phaC1 y phaC2. El análisis comparativo de las secuencias proteicas resultantes de estos genes demuestra que la sintasa  IBUN S1602 contiene la región α/β hidrolasa y 8 residuos de aminoácidos conservados, que son características de las sintasas examinadas a nivel mundial. Se analizó la estructura enzimática a nivel primario y se predijo la secundaria. Se concluyó que  las sintasas de la cepa Pseudomonas fluorescens IBUN S1602 presentan alta homología con las sintasas tipo II  que se reportan para Pseudomonas. Los resultados obtenidos contribuyen al entendimiento básico de la biosíntesis de PHA,  la cual permitirá, en un futuro, el aumento de la calidad de PHA debida a la modulación del nivel de sintasa que se exprese en un organismo recombinante, con el fin de variar el peso molecular del biopolímero, propiedad esencial en el estudio de aplicaciones industriales.   Palabras clave: polihidroxialcanoatos, PHA sintasa, bioinform

  3. An N-terminal Retention Module Anchors the Giant Adhesin LapA of Pseudomonas fluorescens at the Cell Surface: A Novel Sub-family of Type I Secretion Systems.

    Smith, T Jarrod; Font, Maria E; Kelly, Carolyn M; Sondermann, Holger; O'Toole, George A

    2018-02-05

    LapA of Pseudomonas fluorescens Pf0-1 belongs to a diverse family of cell surface associated bacterial adhesins that are secreted via the type-1 secretion system (T1SS). We previously reported that the periplasmic protease LapG cleaves the N-terminus of LapA at a canonical dialanine motif to release the adhesin from the cell surface under conditions unfavorable to biofilm formation, thus decreasing biofilm formation. Here, we characterize LapA as the first type 1 secreted substrate that does not follow the "one-step" rule of T1SS. Rather, a novel N-terminal element, called the retention module (RM), localizes LapA at the cell surface as a secretion intermediate. Our genetic, biochemical, and molecular modeling analysis support a model wherein LapA is tethered to the cell surface through its T1SS outer membrane TolC-like pore, LapE, until LapG cleaves LapA in the periplasm. We further demonstrate this unusual retention strategy is likely conserved among LapA-like proteins, and reveals a new subclass of T1SS ABC transporters involved in transporting this group of surface-associated, LapA-like adhesins. These studies demonstrate a novel cell surface retention strategy used throughout the Proteobacteria and highlight a previously unappreciated flexibility of function for T1SS. Importance. Bacteria have evolved multiple secretion strategies to interact with their environment. For many bacteria, the secretion of cell surface associated adhesins is key for initiating contact with a preferred substratum to facilitate biofilm formation. Our work demonstrates that P. fluorescens uses a previously unrecognized secretion strategy to retain the giant adhesin LapA at its cell surface. Further, we identify likely LapA-like adhesins in various pathogenic and commensal Proteobacteria and provide phylogenetic evidence that these adhesins are secreted by a new subclass of T1SS ABC transporters. Copyright © 2018 American Society for Microbiology.

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

    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.

  5. Kynurenine 3-monooxygenase from Pseudomonas fluorescens: substrate-like inhibitors both stimulate flavin reduction and stabilize the flavin-peroxo intermediate yet result in the production of hydrogen peroxide.

    Crozier-Reabe, Karen R; Phillips, Robert S; Moran, Graham R

    2008-11-25

    Kynurenine 3-monooxygenase (KMO) is a flavin-dependent hydroxylase that catalyzes the conversion of l-kynurenine (l-Kyn) to 3-hydroxykynurenine (3OHKyn) in the pathway for tryptophan catabolism. KMO inhibition has been widely suggested as an early treatment for stroke and other neurological disorders that involve ischemia. We have investigated the reductive and the oxidative half-reactions of a stable form of KMO from Pseudomonas fluorescens (KMO). The binding of l-Kyn by the enzyme is relatively slow and involves at least two reversible steps. The rate constant for reduction of the flavin cofactor by NADPH increases by a factor of approximately 2.5 x 10(3) when l-Kyn is bound. The rate of reduction of the KMO.l-Kyn complex is 160 s(-1), and the K(d) for the NADPH complex is 200 microM with charge-transfer absorption bands for the KMO(RED).l-Kyn.NADP(+) complex accumulating after reduction. The reduction potential of KMO is -188 mV and is unresponsive to the addition of l-Kyn or other inhibitory ligands. KMO inhibitors whose structures are reminiscent of l-Kyn such as m-nitrobenzoylalanine and benzoylalanine also stimulate reduction of flavin by NADPH and, in the presence of dioxygen, result in the stoichiometric liberation of hydrogen peroxide, diminishing the perceived therapeutic potential of inhibitors of this type. In the presence of the native substrate, the oxidative half-reaction exhibits triphasic absorbance data. A spectrum consistent with that of a peroxyflavin species accumulates and then decays to yield the oxidized enzyme. This species then undergoes minor spectral changes that, based on flavin difference spectra defined in the presence of 3OHKyn, can be correlated with product release. The oxidative half-reaction observed in the presence of saturating benzoylalanine or m-nitrobenzoylalanine also shows the accumulation of a peroxyflavin species that then decays to yield hydrogen peroxide without hydroxylation.

  6. 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

    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

  7. Novel Pseudomonas fluorescens Septic Sacroiliitis in a Healthy Soldier

    2013-08-01

    acute pathology or sacroiliac (SI) joint involvement, and a colonoscopy with random rectal mucosal biopsy was normal. Two months later, he experienced...an acute episode of excru- ciating, focal left sacroiliac pain after a fall from a seated height of two feet, necessitating this hospital admission...bone marrow edema of the left sacroiliac joint, and muscle edema of the left iliacus and gluteus medius. FIGURE 2. CT-guided arthrocentesis of the left

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

    sonal

    2015-04-08

    Apr 8, 2015 ... Author(s) agree that this article remains permanently open access under the terms of ... grown in nutrient broth overnight, pond water, mucus and kidney ... a rapid test for detection of Pseudomonas strains in milk is required.

  9. Pseudomonas fluorescens strains selectively suppress annual bluegrass (Poa annua L.)

    Annual bluegrass (Poa annua L.) is a cool-season annual grass that is a major weed species in turf, turfgrass-seed production, sod production, and golf courses of the western United States. There are few selective herbicides available for the management of annual bluegrass. While the life cycles o...

  10. Biosynthesis and regulation of cyclic lipopeptides in Pseudomonas fluorescens

    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

  11. Structural and Mechanistic Insights into the Pseudomonas fluorescens 2-Nitrobenzoate 2-Nitroreductase NbaA.

    Kim, Yong-Hak; Song, Wooseok; Kim, Jin-Sik; Jiao, Li; Lee, Kangseok; Ha, Nam-Chul

    2015-08-01

    The bacterial 2-nitroreductase NbaA is the primary enzyme initiating the degradation of 2-nitrobenzoate (2-NBA), and its activity is controlled by posttranslational modifications. To date, the structure of NbaA remains to be elucidated. In this study, the crystal structure of a Cys194Ala NbaA mutant was determined to a 1.7-Å resolution. The substrate analog 2-NBA methyl ester was used to decipher the substrate binding site by inhibition of the wild-type NbaA protein. Tandem mass spectrometry showed that 2-NBA methyl ester produced a 2-NBA ester bond at the Tyr193 residue in the wild-type NbaA but not residues in the Tyr193Phe mutant. Moreover, covalent binding of the 2-NBA methyl ester to Tyr193 reduced the reactivity of the Cys194 residue on the peptide link. The Tyr193 hydroxyl group was shown to be essential for enzyme catalysis, as a Tyr193Phe mutant resulted in fast dissociation of flavin mononucleotide (FMN) from the protein with the reduced reactivity of Cys194. FMN binding to NbaA varied with solution NaCl concentration, which was related to the catalytic activity but not to cysteine reactivity. These observations suggest that the Cys194 reactivity is negatively affected by a posttranslational modification of the adjacent Tyr193 residue, which interacts with FMN and the substrate in the NbaA catalytic site. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

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

    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.

  13. Nanodiamanty - fluorescenční a zobrazovací nanosondy

    Šlegerová, Jitka; Cígler, Petr

    2014-01-01

    Roč. 108, č. 4 (2014), s. 387-393 ISSN 0009-2770 R&D Projects: GA ČR GAP108/12/0640; GA MŠk(CZ) LH11027 Institutional support: RVO:61388963 Keywords : nanodiamond * fluorescence * biocompatibility Subject RIV: CC - Organic Chemistry Impact factor: 0.272, year: 2014

  14. Impact of Medium on the Development and Physiology of Pseudomonas fluorescens Biofilms on Polyurethane Paint

    2012-02-01

    can provide nutrients that affect biofilm formation and biodeterioration. Historically, studies of polyurethane biodeterioration have monitored the...microbial growth can accelerate the degradation of fuel tank coatings and cause corrosion of aluminum and stainless steel tanks and pipelines (Passman...conditions are determinants of both biofilm formation /dispersion and the degradative impact of bacteria on PU substrates. For example, the transition of

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

    Gallie, Jenna; Libby, Eric; Bertels, Frederic

    2015-01-01

    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 ...

  16. Lipopeptide biosurfactant viscosin enhances dispersal of Pseudomonas fluorescens SBW25 biofilms

    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...

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

    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.

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

    2011-08-24

    ... factors such as ultraviolet light, nutrient depletion and bacterial grazing/predation by protists and...., environmental factors such as ultraviolet light, nutrient depletion and bacterial grazing/predation by protists...

  19. Nanodiamanty jako cílené fluorescenční značky

    Šlegerová, Jitka; Řehoř, Ivan; Šácha, Pavel; Richter, Jan; Cígler, Petr

    2013-01-01

    Roč. 107, č. 5 (2013), s. 439-439 ISSN 0009-2770. [Mezioborové setkání mladých biologů, biochemiků a chemiků /13./. 14.5.2013-17.5.2013, Žďár nad Sázavou] Institutional support: RVO:61388963 ; RVO:61388971 Keywords : vectoring * fluorescent nanodiamond * GCPII * cancer cells * polymer coating Subject RIV: CC - Organic Chemistry

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

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

    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...... growth phase and upon physical encounter with fungal hyphae. Furthermore, the regulator is strongly upregulated in response to carbon sources indicating the presence of a fungus suggesting that environmental elicitors may also influence regulator expression, which upon activation controls nunamycin...... temperatures could lead to increased problems with soil-borne pathogens and importantly the application of synthetic fungicides in cold areas may be problematic due to slow degradation. Thus, the application of environmentally friendly biological control agents may provide an alternative sustainable solution...

  1. Female sexual arousal: genital anatomy and orgasm in intercourse.

    Wallen, Kim; Lloyd, Elisabeth A

    2011-05-01

    In men and women sexual arousal culminates in orgasm, with female orgasm solely from sexual intercourse often regarded as a unique feature of human sexuality. However, orgasm from sexual intercourse occurs more reliably in men than in women, likely reflecting the different types of physical stimulation men and women require for orgasm. In men, orgasms are under strong selective pressure as orgasms are coupled with ejaculation and thus contribute to male reproductive success. By contrast, women's orgasms in intercourse are highly variable and are under little selective pressure as they are not a reproductive necessity. The proximal mechanisms producing variability in women's orgasms are little understood. In 1924 Marie Bonaparte proposed that a shorter distance between a woman's clitoris and her urethral meatus (CUMD) increased her likelihood of experiencing orgasm in intercourse. She based this on her published data that were never statistically analyzed. In 1940 Landis and colleagues published similar data suggesting the same relationship, but these data too were never fully analyzed. We analyzed raw data from these two studies and found that both demonstrate a strong inverse relationship between CUMD and orgasm during intercourse. Unresolved is whether this increased likelihood of orgasm with shorter CUMD reflects increased penile-clitoral contact during sexual intercourse or increased penile stimulation of internal aspects of the clitoris. CUMD likely reflects prenatal androgen exposure, with higher androgen levels producing larger distances. Thus these results suggest that women exposed to lower levels of prenatal androgens are more likely to experience orgasm during sexual intercourse. Copyright © 2011. Published by Elsevier Inc.

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

    Koch, Birgit; Nybroe, Ole

    2006-01-01

    A expression. The mutant grew slower than the wild-type strain in minimal medium with L-serine as the sole nitrogen source, while growth rates were similar on a mixture of L-serine and L-cysteine. Reverse transcriptase polymerase chain reaction analysis indicated that the bolA homologue is the second gene...

  3. Effect of organic management of soils on suppressiveness to Gaeumannomyces graminis var. tritici and its antagonist, Pseudomonas fluorescens

    Hiddink, G.A.; Bruggen, van A.H.C.; Termorshuizen, A.J.; Raaijmakers, J.M.; Semenov, A.V.

    2005-01-01

    Organic management of soils is generally considered to reduce the incidence and severity of plant diseases caused by soil-borne pathogens. In this study, take-all severity on roots of barley and wheat, caused by Gaeumannomyces graminis var. tritici, was significantly lower in organically-managed

  4. No apparent costs for facultative antibiotic production by the soil bacterium Pseudomonas fluorescens Pf0-1

    Garbeva, P.V.; Tyc, O.; Remus-Emsermann, M.N.P.; Van der Wal, A.; Vos, M.; Silby, M.W.; De Boer, W.

    2011-01-01

    Background: Many soil-inhabiting bacteria are known to produce secondary metabolites that can suppress microorganisms competing for the same resources. The production of antimicrobial compounds is expected to incur fitness costs for the producing bacteria. Such costs form the basis for models on the

  5. Evidence for a role of biosurfactants produced by Pseudomonas fluorescens in the spoilage of fresh aerobically stored chicken meat.

    Mellor, Glen E; Bentley, Jessica A; Dykes, Gary A

    2011-08-01

    Fresh chicken meat is a fat-rich environment and we therefore hypothesised that production of biosurfactants to increase bioavailability of fats may represent one way in which spoilage bacteria might enhance the availability of nutrients. Numbers of Pseudomonas were determined on a total of 20 fresh and 20 spoiled chicken thighs with skin. A total of 400 randomly isolated Pseudomonas colonies from fresh (200) and spoiled (200) chicken were screened for the presence of biosurfactant production. Biosurfactant producing strains represented 5% and 72% of the Pseudomonas spp. isolates from fresh (mean count 2.3 log(10) cfu g(-1)) and spoiled (mean count 7.4 log(10) cfu g(-1)) chicken skin, respectively. Partially-purified biosurfactants derived from a subgroup of four Pseudomonasfluorescens strains obtained through the screening process were subsequently used to investigate the role that the addition of these compounds plays in the spoilage of aerobically stored chicken. Emulsification potential of the four selected biosurfactants was measured against a range of hydrocarbons and oils. All four biosurfactants displayed a greater ability to emulsify rendered chicken fat than hydrocarbons (paraffin liquid, toluene and hexane) and oils (canola, olive, sunflower and vegetable). Storage trials (4 °C) of chicken meat treated with the four selected biosurfactants revealed a significantly greater (P increase in total aerobic count (1.3-1.7 log(10) cfu g(-1)) occurred following one day of incubation. These results indicate that biosurfactants produced by Pseudomonas spp. may play an important role in the spoilage of aerobically stored chicken meat by making nutrients more freely available and providing strains producing them with a competitive advantage. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    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.

  7. Adaptive Divergence in Experimental Populations of Pseudomonas fluorescens. IV. Genetic Constraints Guide Evolutionary Trajectories in a Parallel Adaptive Radiation

    McDonald, Michael J.; Gehrig, Stefanie M.; Meintjes, Peter L.; Zhang, Xue-Xian; Rainey, Paul B.

    2009-01-01

    The capacity for phenotypic evolution is dependent upon complex webs of functional interactions that connect genotype and phenotype. Wrinkly spreader (WS) genotypes arise repeatedly during the course of a model Pseudomonas adaptive radiation. Previous work showed that the evolution of WS variation was explained in part by spontaneous mutations in wspF, a component of the Wsp-signaling module, but also drew attention to the existence of unknown mutational causes. Here, we identify two new muta...

  8. Competition for nitrate and glucose between Pseudomonas fluorescens and Bacillus licheniformis under continuous or fluctuating anoxic conditions

    Nijburg, J.W.; Gerards, S.; Laanbroek, H.J.

    1998-01-01

    The dissimilatory nitrate-reducing bacterial community in the rhizosphere of aerenchymatous plant species such as Glyceria maxima, consists of oxidative. denitrifying and fermentative nitrate-ammonifying bacteria. To study the respective ecological niches of both types of nitrate-reducing bacteria,

  9. Competition for nitrate and glucose between Pseudomonas fluorescens and Bacillus licheniformis under continuous or fluctuating anoxic conditions

    Nijburg, J.W.; Gerards, S.; Laanbroek, H.J.

    1998-01-01

    The dissimilatory nitrate-reducing bacterial community in the rhizosphere of aerenchymatous plant species such as Glyceria maxima, consists of oxidative, denitrifying and fermentative nitrate-ammonifying bacteria. To study the respective ecological niches of both types of nitrate-reducing

  10. Polychlorinated biphenyl rhizoremediation by Pseudomonas fluorescens F113 derivatives, using a Sinorhizobium meliloti nod system to drive bph gene expression

    Villacieros, M.; Whelan, C.; Macková, Martina; Molgaard, J.; Sánchez-Contreras, M.; Lloret, J.; Cárcer de, D.; Oruezábal, R. I.; Bolanos, L.; Macek, Tomáš; Karlson, U.; Dowling, D. N.; Martín, M.; Rivilla, R.

    2005-01-01

    Roč. 71, č. 5 (2005), 2687-2694 ISSN 0099-2240 Grant - others:5thFW(XE) QLK3-CT-2001-00101; European Commission(XE) BIO4-CT97-2227 Institutional research plan: CEZ:AV0Z4055905 Keywords : polychlorinated biphenyls * rhizoremediation Subject RIV: CC - Organic Chemistry Impact factor: 3.818, year: 2005

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

    Hol, W.H.G.; Bezemer, T.M.; Biere, A.

    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

  12. Metody studia vodních bakterií pomocí fluorescenční mikroskopie

    Šimek, Karel

    2016-01-01

    Roč. 64, č. 2 (2016), s. 76 ISSN 0044-4812 Institutional support: RVO:60077344 Keywords : microbial ecology * bacteria- protozoa interactions * fluorescence microscopy Subject RIV: EE - Microbiology, Virology

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

    Trögl, J.; Chauhan, A.; Ripp, S.; Layton, A.C.; Kuncová, Gabriela; Sayler, G.S.

    2012-01-01

    Roč. 12, č. 2 (2012), s. 1544-1571 ISSN 1424-8220 R&D Projects: GA MŠk ME 892; GA MŠk ME 893 Grant - others:USDA(US) 2009-39210-20230 Institutional research plan: CEZ:AV0Z40720504 Keywords : bioluminiscence * bioreporter * biosensors Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.953, year: 2012

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

    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

  15. 40 CFR 180.1107 - Delta endotoxin of Bacillus thuringiensis variety kurstaki encapsulated into killed Pseudomonas...

    2010-07-01

    ... thuringiensis variety kurstaki encapsulated into killed Pseudomonas fluorescens; exemption from the requirement... killed Pseudomonas fluorescens; exemption from the requirement of a tolerance. The delta endotoxin of Bacillus thuringiensis variety kurstaki encapsulated into killed Pseudomonas fluorescens is exempt from the...

  16. 40 CFR 180.1108 - Delta endotoxin of Bacillus thuringiensis variety San Diego encapsulated into killed Pseudomonas...

    2010-07-01

    ... thuringiensis variety San Diego encapsulated into killed Pseudomonas fluorescens; exemption from the requirement... into killed Pseudomonas fluorescens; exemption from the requirement of a tolerance. The delta endotoxin of Bacillus thuringiensis variety San Diego encapsulated into killed Pseudomonas fluorescens is...

  17. A combined microcosm and mesocosm approach to examine factors affecting survival and mortality of Pseudomonas fluorescens Ag1 in seawater

    Ahl, Thomas; Christoffersen, K.; Riemann, B.

    1995-01-01

    .5‰). In microcosms with 0.2 µm-filtered seawater, addition of a carbon + nitrogen + phosphorus nutrient mixture was needed to induce proliferation of Ag1. In nutrient-amended microcosms the Ag1 population maintained viability, as determined by the direct viable counts method, at a level close to 100%. In natural...

  18. From the root to the stem: interaction between the biocontrol root endophyte Pseudomonas fluorescens PICF7 and the pathogen Pseudomonas savastanoi NCPPB 3335 in olive knots

    Maldonado-González, M Mercedes; Prieto, Pilar; Ramos, Cayo; Mercado-Blanco, Jesús

    2013-01-01

    Olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, is one of the most important biotic constraints for olive cultivation. Pseudomonas fluorescens PICF7, a natural colonizer of olive roots and effective biological control agent (BCA) against Verticillium wilt of olive, was examined as potential BCA against olive knot disease. Bioassays using in vitro-propagated olive plants were carried out to assess whether strain PICF7 controlled knot development either when co-inoculated with the pathogen in stems or when the BCA (in roots) and the pathogen (in stems) were spatially separated. Results showed that PICF7 was able to establish and persist in stem tissues upon artificial inoculation. While PICF7 was not able to suppress disease development, its presence transiently decreased pathogen population size, produced less necrotic tumours, and sharply altered the localization of the pathogen in the hyperplasic tissue, which may pose epidemiological consequences. Confocal laser scanning microscopy combined with fluorescent tagging of bacteria revealed that when PICF7 was absent the pathogen tended to be localized at the knot surface. However, presence of the BCA seemed to confine P. savastanoi at inner regions of the tumours. This approach has also enabled to prove that the pathogen can moved systemically beyond the hypertrophied tissue. PMID:23425069

  19. Uptake of Hydrocarbon by Pseudomonas fluorescens (P1) and Pseudomonas putida (K1) Strains in the Presence of Surfactants: A Cell Surface Modification

    Kaczorek, Ewa; Olszanowski, Andrzej

    2010-01-01

    The objective of this research was the evaluation of the effects of exogenous added surfactants on hydrocarbon biodegradation and on cell surface properties. Crude oil hydrocarbons are often difficult to remove from the environment because of their insolubility in water. The addition of surfactants enhances the removal of hydrocarbons by raising the solubility of these compounds. These surfactants cause them to become more vulnerable to degradation, thereby facilitating transportation across ...

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

    Holmstrøm, Kim; Gram, Lone

    2003-01-01

    or another V. anguillarum siderophore. On the pJM1 plasmid of V anguillarum serotype O1, a pseudogene designated open reading frame E (ORF E) that contains a frameshift mutation was previously identified. The gene homologous to vibE identified in this study, interestingly, also has significant homology...... to ORF E on the amino acid level and does not possess the frameshift mutation. Thus, the chromosomally encoded vibE homologue could fulfil the role of the inactive plasmid-encoded ORF E pseudogene. Addition of Fe3+ to the system eliminated the growth arrest, and the genes homologous to rpoS and vibE were...

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

    Guillemyn, Karel; Ballet, Steven; Ye, Lumeng

    2014-01-01

    , displays spectroscopic data identical with those of the alleged carbostyril derivative. In addition, the published H-1 and C-13 NMR data are in agreement with those calculated for aeruginaldehyde. We propose that aeruginaldehyde and aeruginol originate from the non-ribosomal peptide synthetase enzymes...

  2. Effects of spray-dried Pseudomonas fluorescens, strain CL145A (Zequanox®) on reproduction and early development of the fathead minnow (Pimephales promelas).

    Waller, Diane L.; Luoma, James A.

    2016-01-01

    The biopesticide, Zequanox®, is registered for dreissenid mussel control in open water systems. Previous toxicity trials with nontarget organisms, including young-of-the year of several fish species and invertebrates, demonstrated selectivity of Zequanox for dreissenids. However, data are lacking on its safety to reproductive and early life stages of fish. The present study evaluated the effects of Zequanox on spawning and early life stages of the fathead minnow, Pimephales promelas, at the maximum approved concentration (100 mg Zequanox active ingredient /L) and exposure duration (8 h) for open water application. The results showed no significant effect of Zequanox on survival, condition, or cumulative egg deposition (21 d) in adult fathead minnow. Eggs (<24-h old) exposed to Zequanox developed to the eyed-stage at a similar rate to that of unexposed eggs. Additionally, Zequanox did not have a significant effect on survival and growth (90 d) of newly hatched fry (<24-h old). The results indicate that Zequanox treatment will not affect survival, spawning, and early life development of fathead minnows when applied at the recommended treatment regime.

  3. A New Twist to the Kirby-Bauer Antibiotic Susceptibility Test Activity?Increasing Antibiotic Sensitivity of Pseudomonas fluorescens through Thermal Stress

    Gerbig, Donald G.; Engohang-Ndong, Jean; Aubihl, Heather

    2013-01-01

    Antibiotic sensitivity and the effect of temperature on microbial growth are two standard laboratory activities found in most microbial laboratory manuals. We have found a novel way to combine the two activities to demonstrate how temperature can influence antibiotic sensitivity using a standard incubator in instructional laboratory settings. This activity reinforces the important concepts of microbial growth and temperature along with Kirby-Bauer antibiotic susceptibility testing. We found t...

  4. Sférické monodisperzní nanodiamanty - biologicky inertní sondy pro fluorescenční zobrazování

    Řehoř, Ivan; Šlegerová, Jitka; Havlík, Jan; Cígler, Petr

    2014-01-01

    Roč. 108, č. 5 (2014), s. 548 ISSN 0009-2770. [Mezioborové setkání mladých biologů, biochemiků a chemiků /14./. 13.05.2014-16.05.2014, Milovy] R&D Projects: GA ČR GAP108/12/0640; GA MŠk(CZ) LH11027 Institutional support: RVO:61388963 Keywords : fluorescent nanodiamonds * high-pressure high-temperature * click chemistry Subject RIV: CC - Organic Chemistry

  5. Exploiting genotypic diversity of 2,4-Diacetylphloroglucinol-producing Pseudomonas spp.: characterization of superior root-colonizing P. fluorescens strain Q8r1-96

    Raaijmakers, J.M.; Weller, D.M.

    2001-01-01

    The genotypic diversity that occurs in natural populations of antagonistic microorganisms provides an enormous resource for improving biological control of plant diseases. In this study, we determined the diversity of indigenous 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas spp. occurring

  6. Accelerated storage testing of freeze-dried Pseudomonas ...

    Accelerated storage testing of freeze-dried Pseudomonas fluorescens BTP1, ... of all P. fluorescens strains were not significantly different and thermal inactivation ... useful to the development of improved reference materials and samples held ...

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

    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 ...

  8. Stanovení aktivit rostlinných fosfolipas in situ s využitím fluorescenčně značených substrátů

    Pejchar, Přemysl; Valentová, O.; Martinec, Jan

    2003-01-01

    Roč. 68, č. 3 (2003), s. 227-234 ISSN 0366-0486 R&D Projects: GA ČR GA522/03/0353 Institutional research plan: CEZ:AV0Z5038910 Keywords : phospholipid signalling pathway * BODIPY-phosphatidylcholine * high performance thin-layer chromatography Subject RIV: CE - Biochemistry

  9. NCBI nr-aa BLAST: CBRC-PTRO-27-0010 [SEVENS

    Full Text Available CBRC-PTRO-27-0010 ref|YP_258895.1| DNA internalization-related competence protein C...omEC/Rec2 [Pseudomonas fluorescens Pf-5] gb|AAY91064.1| DNA internalization-related competence protein ComEC/Rec2 [Pseudomonas fluorescens Pf-5] YP_258895.1 7e-06 30% ...

  10. Growth response and nutrient uptake of blue pine (Pinus wallichiana seedlings inoculated with rhizosphere microorganisms under temperate nursery conditions

    M.A. Ahangar

    2012-11-01

    Full Text Available Microbial inoculants (Trichoderma harzianum, Pseudomonas fluorescens,Laccaria laccata inoculated either individually or in combinationsignificantly improved the growth and biomass of blue pine seedlings. The ECM fungus Laccaria laccata, when inoculated individually, showed significantly higher plant growth, followed by Pseudomonas fluorescens and Trichoderma harzianum. The combined inoculation of rhizosphere microorganisms showed synergistic growth promoting action and proved superior in enhancing the growth of blue pine than individual inoculation. Co-inoculation of L. laccata with P. fluorescens resulted in higher ectomycorrhizal root colonization. Uptake of nutrients (N, P, K was significantly improved by microbial inoculants, tested individually or in combination. Combined inoculation of L. laccata with T. harzianum and P. fluorescens significantly increased in N, P and K contents in blue pine seedlings as compared to control. Acid phosphatase activity in the rhizosphere of blue pine seedlings was also enhanced by these microorganisms. L. laccata exhibited higher acid phosphatase activity followed by P. fluorescens.

  11. Mining Genomes of Biological Control Strains of Pseudomonas spp.: Unexpected Gems and Tailings

    The biocontrol bacterium Pseudomonas fluorescens Pf-5 suppresses numerous soilborne plant diseases and produces an array of structurally-characterized secondary metabolites that are toxic to plant pathogenic bacteria, fungi and Oomycetes. Biosynthetic gene clusters for these metabolites compose nea...

  12. Weed-Suppressive Soil Bacteria to Reduce Cheatgrass and Improve Vegetation Diversity on ITD Rights-of-Way

    2017-06-01

    Transportation departments are challenged by the invasion of downy brome (cheatgrass) and medusahead. The reduction of downy brome (cheat grass) by Weed Suppressive Bacteria (WSB) Pseudomonas fluorescens strain ACK55 was evaluated on roadsides of I-8...

  13. African Journal of Biotechnology - Vol 11, No 101 (2012)

    Protection of melon plants against Cucumber mosaic virus infection using Pseudomonas fluorescens biofertilizer · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Rakib A Al-Ani, Mustafa A Adhab, 16579-16585 ...

  14. Isolation of Fungal Species from Fermentating Pearl Millet Gruel and ...

    Escherichia coli, Staphylococcus aureus, Bacillus cereus, Bacillus lichieniformis, Salmonella spp., Pseudomonas fluorescens, Pseudomonas aeruginosa, Pseudomonas syringae, Proteus sp. and Serratia sp. were utilized as indicator organisms. Secondary metabolites were also extracted from the respective moulds and ...

  15. Volatile-mediated interactions between phylogenetically different soil bacteria

    Paolina eGarbeva

    2014-06-01

    Full Text Available There is increasing evidence that organic volatiles play an important role in interactions between micro-organisms in the porous soil matrix. Here we report that volatile compounds emitted by different soil bacteria can affect the growth, antibiotic production and gene expression of the soil bacterium Pseudomonas fluorescens Pf0-1. We applied a novel cultivation approach that mimics the natural nutritional heterogeneity in soil in which P. fluorescens grown on nutrient-limited agar was exposed to volatiles produced by 4 phylogenetically different bacterial isolates (Collimonas pratensis, Serratia plymuthica, Paenibacillus sp. and Pedobacter sp. growing in sand containing artificial root exudates. Contrary to our expectation, the produced volatiles stimulated rather than inhibited the growth of P. fluorescens. A genome-wide, microarray-based analysis revealed that volatiles of all 4 bacterial strains affected gene expression of P. fluorescens, but with a different pattern of gene expression for each strain. Based on the annotation of the differently expressed genes, bacterial volatiles appear to induce a chemotactic motility response in P. fluorescens, but also an oxidative stress response. A more detailed study revealed that volatiles produced by C. pratensis triggered, antimicrobial secondary metabolite production in P. fluorescens. Our results indicate that bacterial volatiles can have an important role in communication, trophic - and antagonistic interactions within the soil bacterial community.

  16. Biocontrol of the Sugarcane Borer Eldana saccharina by Expression of the Bacillus thuringiensis cry1Ac7 and Serratia marcescens chiA Genes in Sugarcane-Associated Bacteria

    Downing, Katrina J.; Leslie, Graeme; Thomson, Jennifer A.

    2000-01-01

    The cry1Ac7 gene of Bacillus thuringiensis strain 234, showing activity against the sugarcane borer Eldana saccharina, was cloned under the control of the tac promoter. The fusion was introduced into the broad-host-range plasmid pKT240 and the integration vector pJFF350 and without the tac promoter into the broad-host-range plasmids pML122 and pKmM0. These plasmids were introduced into a Pseudomonas fluorescens strain isolated from the phylloplane of sugarcane and the endophytic bacterium Herbaspirillum seropedicae found in sugarcane. The ptac-cry1Ac7 construct was introduced into the chromosome of P. fluorescens using the integration vector pJFF350 carrying the artificial interposon Omegon-Km. Western blot analysis showed that the expression levels of the integrated cry1Ac7 gene were much higher under the control of the tac promoter than under the control of its endogenous promoter. It was also determined that multicopy expression in P. fluorescens and H. seropedicae of ptac-cry1Ac7 carried on pKT240 caused plasmid instability with no detectable protein expression. In H. seropedicae, more Cry1Ac7 toxin was produced when the gene was cloned under the control of the Nmr promoter on pML122 than in the opposite orientation and bioassays showed that the former resulted in higher mortality of E. saccharina larvae than the latter. P. fluorescens 14::ptac-tox resulted in higher mortality of larvae than did P. fluorescens 14::tox. An increased toxic effect was observed when P. fluorescens 14::ptac-tox was combined with P. fluorescens carrying the Serratia marcescens chitinase gene chiA, under the control of the tac promoter, integrated into the chromosome. PMID:10877771

  17. Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

    Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

    2013-10-01

    Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200-400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200-400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200-400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation.

  18. Interaction of bacteria-feeding soil flagellates and Pseudomonas spp

    Pedersen, Annette; Ekelund, Flemming; Johansen, Anders

    2010-01-01

    Pseudomonas strains may be used as alternatives to fungicides as some of them produce secondary metabolites, which can inhibit growth of plant pathogenic fungi. Increased knowledge of non-target effects of the antagonistic bacteria on other soil organisms as well as of the survival and predation...... resistance of the antagonistic bacteria is necessary for risk assessment and increased performance of antagonistic bacteria as biological control agents. In the present study, we aimed to investigate the difference between Pseudomonas spp. with respect to their predation resistance to and effects...... on the three different and common soil flagellates Bodo caudatus, Cercomonas longicauda, and Neocercomonas jutlandica. Two antagonistic Pseudomonas: Pseudomonas fluorescens CHA0 and P. fluorescens DR54 and two positive control strains: P. fluorescens DSM 50090T and Pseudomonas chlororaphis ATCC 43928 were...

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

    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...

  20. Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

    Singh, Udai B; Malviya, Deepti; Wasiullah; Singh, Shailendra; Pradhan, Jatindra K; Singh, Bhanu P; Roy, Manish; Imram, Mohd; Pathak, Neelam; Baisyal, B M; Rai, Jai P; Sarma, B K; Singh, Rajiv K; Sharma, P K; Kaur, Saman Deep; Manna, M C; Sharma, Sushil K; Sharma, Arun K

    2016-11-01

    Sheath blight of rice (Oryza sativa L.) caused by Rhizoctonia solani is a major disease and attempts are being made to develop microbe based technologies for biocontrol of this pathogen. However, the mechanisms of biocontrol are not fully understood and still require indepth study in the backdrop of emerging concepts in biological systems. The present investigation was aimed at deciphering the mechanisms of biocontrol of sheath blight of rice employing Pseudomonas fluorescens and Trichoderma harzianum as model agents for biocontrol. Initially 25, 5 and 5 strains of P. fluorescens, T. viride and T. harzianum, respectively, were screened for their biocontrol potential. Out of which, six strains with higher value of percent inhibition of fungal mycelium in dual plate assay were selected. The role of P. fluorescens, T. viride and T. harzianum were investigated in induction and bioaccumulation of natural antioxidants, defence-related biomolecules and other changes in plant which lead not only to growth promotion but also protection from pathogenic stress conditions in rice. The two most promising strains, P. fluorescens PF-08 and T. harzianum UBSTH-501 selected on the basis of in planta evaluation, when applied individually or in combination, significantly enhanced the accumulation of defence-related biomolecules, enzymes and exhibited biocontrol potential against R. solani. A modified/newly developed delivery system was applied for the first time in the experiments involving inoculation of plants with both bioagents, viz. P. fluorescens PF-08 and T. harzianum UBSTH-501. Results suggested that application of P. fluorescens PF-08 and T. harzianum UBSTH-501 alone or in combination, not only helps in control of the disease but also increases plant growth along with reduction in application of toxic chemical pesticides. Copyright © 2016 Elsevier GmbH. All rights reserved.

  1. Antibiotic and biosurfactant properties of cyclic lipopeptides produced by fluorescent Pseudomonas spp. from the sugar beet rhizosphere

    Nielsen, T H; Sørensen, D; Tobiasen, C

    2002-01-01

    Cyclic lipopeptides (CLPs) with antibiotic and biosurfactant properties are produced by a number of soil bacteria, including fluorescent Pseudomonas spp. To provide new and efficient strains for the biological control of root-pathogenic fungi in agricultural crops, we isolated approximately 600...... in the peptide moiety. Production of specific CLPs could be affiliated with Pseudomonas fluorescens strain groups belonging to biotype I, V, or VI. In vitro analysis using both purified CLPs and whole-cell P. fluorescens preparations demonstrated that all CLPs exhibited strong biosurfactant properties...

  2. Microbial degradation of phosmet on blueberry fruit and in aqueous systems by indigenous bacterial flora on lowbush blueberries (Vaccinium angustifolium).

    Crowe, K M; Bushway, A A; Bushway, R J; Davis-Dentici, K

    2007-10-01

    Phosmet-adapted bacteria isolated from lowbush blueberries (Vaccinium angustifolium) were evaluated for their ability to degrade phosmet on blueberry fruit and in minimal salt solutions. Microbial metabolism of phosmet by isolates of Enterobacter agglomerans and Pseudomonas fluorescens resulted in significant reductions (P blueberries and in minimal salt solutions. Thus, the role of adapted strains of E. agglomerans and P. fluorescens in degrading phosmet on blueberries represents an extensive plant-microorganism relationship, which is essential to determination of phosmet persistence under pre- and postharvest conditions.

  3. 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

    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.

  4. Evaluation of potential bio-control agents on root-knot nematode ...

    Indigenous strains of Trichoderma viride (ITCC No. 6889), Pseudomonas fluorescens (ITCC No. B0034) and Purpureocillium lilacinum (ITCC No.6887) were isolated from undisturbed forest eco-system of Southern India. These three bio-mediators were evaluated for their antagonism towards root knot nematode, ...

  5. Accelerated storage testing of freeze-dried Pseudomonas ...

    Erika-Chris

    Full Length Research Paper ... was possible to compare rate constants of survival for the freeze-dried P. fluorescens ... studying and predicting the survival loss rate of the ... Erlenmeyer flask containing 3000 ml King B medium. ... The strain was grown in 20 L bioreactor (Biolafite) containing 15 L .... fermented banana media.

  6. Rhizosphere competence of wild-type and genetically-engineered Pseudomonas brassicacearum is affected by the crop species

    2,4-diacetylphloroglucinol (2,4-DAPG)-producing Pseudomonas brassicacearum Q8r1-96 is a highly effective biocontrol agent of take-all disease of wheat. Strain Z30-97, a recombinant derivative of Q8r1-96 containing the phzABCDEFG operon from P. synxantha (formerly P. fluorescens) 2-79 inserted into ...

  7. Interactions of rare earth elements with bacteria and organic ligands

    Ozaki, Takuo; Suzuki, Yoshinori; Nankawa, Takuya; Yoshida, Takahiro; Ohnuki, Toshihiko; Kimura, Takaumi; Francis, Arokiasamy J.

    2006-01-01

    We investigated the interactions of rare earth elements (REEs) Eu(III) and/or Ce(III, IV) with the common soil bacterium Pseudomonas fluorescens and organic ligands, such as malic acid, citric acid, a siderophore (DFO), cellulose, chitin, and chitosan. Malic acid formed complexes with Eu(III), but degradation of malic acid was observed when the ratio of malic acid to Eu(III) was higher than 100. Citric acid formed a stoichiometric complex with Eu(III) that was not degraded by P. fluorescens. Adsorption of Eu(III) from the DFO complex occurred as a free ion dissociated from DFO and not as the Eu(III)-DFO complex. Cerium(III) was oxidized to Ce(IV) during complexation with DFO to form the Ce(IV)-DFO complex. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) analysis showed that cellulose, chitin, and chitosan, respectively, formed a weak complex, an inner-spherical complex, and an outer-spherical complex with Eu(III). This method also demonstrated that the coordination environment of Eu(III) adsorbed on P. fluorescens possessed similar characteristics to that of chitin, and revealed that adsorption of Eu(III) on P. fluorescens was through a multidentate and predominantly inner-spherical coordination

  8. Effects of inoculation with organic-phosphorus-mineralizing bacteria on soybean (Glycine max) growth and indigenous bacterial community diversity.

    Sun, Wei; Qian, Xun; Gu, Jie; Wang, Xiao-Juan; Li, Yang; Duan, Man-Li

    2017-05-01

    Three different organic-phosphorus-mineralizing bacteria (OPMB) strains were inoculated to soil planted with soybean (Glycine max), and their effects on soybean growth and indigenous bacterial community diversity were investigated. Inoculation with Pseudomonas fluorescens Z4-1 and Brevibacillus agri L7-1 increased organic phosphorus degradation by 22% and 30%, respectively, compared with the control at the mature stage. Strains P. fluorescens Z4-1 and B. agri L7-1 significantly improved the soil alkaline phosphatase activity, average well color development, and the soybean root activity. Terminal restriction fragment length polymorphism analysis demonstrated that P. fluorescens Z4-1 and B. agri L7-1 could persist in the soil at relative abundances of 2.0%-6.4% throughout soybean growth. Thus, P. fluorescens Z4-1 and B. agri L7-1 could potentially be used in organic-phosphorus-mineralizing biofertilizers. OPMB inoculation altered the genetic structure of the soil bacterial communities but had no apparent influence on the carbon source utilization profiles of the soil bacterial communities. Principal components analysis showed that the changes in the carbon source utilization profiles of bacterial community depended mainly on the plant growth stages rather than inoculation with OPMB. The results help to understand the evolution of the soil bacterial community after OPMB inoculation.

  9. Priming of plant innate immunity by rhizobacteria and β-aminobutyric acid: differences and similarities in regulation

    Ent, S. van der; Hulten, M.H.A. van; Pozo, Maria J.; Czechowski, Tomasz; Udvardi, Michael K.; Pieterse, C.M.J.; Ton, J.

    Pseudomonas fluorescens WCS417r bacteria and β-aminobutyric acid can induce disease resistance in Arabidopsis, which is based on priming of defence. In this study, we examined the differences and similarities of WCS417r- and β-aminobutyric acid-induced priming. Both WCS417r and β-aminobutyric acid

  10. Author Details

    Okolo, BN. Vol 15 (2011) - Articles Effects of Different Carbon Sources on Biosurfactant Production by a Pseudomonas fluorescens Isolate Abstract. ISSN: 1119-2283. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and ...

  11. Author Details

    Effects of Different Carbon Sources on Biosurfactant Production by a Pseudomonas fluorescens Isolate Abstract · Vol 16 (2013) - Articles Production and properties of fungal cellulase from native isolates using orange bagasse as carbon source. Abstract · Vol 16 (2013) - Articles Production and characterization of pectinases ...

  12. Metabolites change in Jatropha plants due to seed treatment with rhizobacteria and Rhizoctonia bataticola

    Surender Kumar

    2013-11-01

    Full Text Available An experiment on the metabolite [salicylic acid (SA, jasmonicacid (JA, hydrocyanic acid (HCN and chitinase activity] changes owing to seed treatment with pathogen, plant growth promoting rhizobacteria (PGPRs - (P. maltophilia, P. fluorescens and Bacillus subtilis alone and in combination was conducted at Chaudhary Charan Singh, Haryana Agricultural University, Regional Research Station, Bawal. Jatropha curcas plants raised from root rot pathogen (Rhizoctonia bataticola treated seeds showed an initial increase in SA and hydrocyanic acid HCN content and an opposite trend was observed for JA level and chitinase activity. Though, PGPRs inoculation resulted in higher increase in SA level, JA level and chitinaseactivity in both the cases alone as well as in integration with pathogen, however, maximum increase in JA content was explicited in plants raised after seed treatment with P. fluorescens, the most effective rhizobacteria amongst PGPRs studied. Highest increase in HCN content (45 μg g-1 over control (24 μg g-1 was noticed for P. fluorescens followed by co-seed inoculation with P. fluorescens + pathogen (43 μg g-1 at 10 DPI. The co-seed inoculation elicited 68 units at 10 DPI whereas the pathogen challenged plants showed lower chitinase activity with 42 units. All the metabolites declinedslightly or sharply with age of the plant irrespective of inoculations.

  13. Elimination of the formation of biofilm in industrial pipes using enzyme cleaning technique

    Xiaobo Liu

    2014-01-01

    Lastly, the terminal water was tested with SLYM-BART™ (HACH Corporation to find out whether there were biofilm-forming bacteria, such as Pseudomonas aeruginosa (Lakretz et al. (2011 [1], Pseudomonas fluorescens (O’Toole and Kolter (1998 [2], iron bacterium, etc.

  14. A quest for indigenous truffle helper prokaryotes

    Gryndler, Milan; Soukupová, Lucie; Hršelová, Hana; Gryndlerová, Hana; Borovička, Jan; Streiblová, Eva; Jansa, Jan

    2013-01-01

    Roč. 5, č. 3 (2013), s. 346-352 ISSN 1758-2229 R&D Projects: GA ČR GAP504/10/0382 Institutional support: RVO:67985831 ; RVO:61388971 Keywords : TUBER-BORCHII * PSEUDOMONAS -FLUORESCENS * ECTOMYCORRHIZAL FUNGI Subject RIV: EE - Microbiology, Virology Impact factor: 3.264, year: 2013

  15. Bacteriocinogenicity and production of pyocins from Pseudomonas ...

    ), P. fluorescens (13) and P. stutzeri (3) were isolated from Nigerian patients with burns, wound and skin infections, UTI, diarrhoea and eye infections. 81.5, 55.6, 76.9 and 33.3% of these species produced pyocins at a range of 410 – 670 g/ml.

  16. Regulatory mutations affecting the synthesis of cellulase in ...

    Pseudomonas fluorescens, was cultured in basal medium containing carboxymethyl-cellulose (CMC) as inducer and glucose or glycerol as carbon and energy sources. Ethylmethanesulphonate (EMS) was used to mutagenize the wild-type organism to produce mutants. The isolated mutants were screened for the isolation ...

  17. Rhizospheric Microflora Escalating Aroma Constituents and Yield Attributes in Ocimum tenuiflorum (L. cv. CIM-Ayu

    Shilpi Khare Saikia

    2014-01-01

    Full Text Available The exploration of rhizospheric microbial flora for crop yield enhancement is well established. Rhizospheric microbes influence the plant physiology by imparting several beneficial effects, namely, Nitrogen fixation, increased nutrient uptake, and secondary metabolites production on their host plants. The present study investigates the response of Bacillus megaterium ATCC No. 13525, Pseudomonas fluorescens ATCC No. 14581, and Trichoderma viride MTCC No. 167 in alone and combined treatments for their effect on growth and yield parameters in a commercially important Ocimum tenuiflorum L. cv. CIM-Ayu. The plant is therapeutically important for its essential oil constituents, namely, eugenol, β-caryophyllene, and various monoterpenes. The combination treatments, T7 (B. megaterium + P. fluorescens and T8 (B. megaterium + P. fluorescens + T. viride, showed maximum enhancement (27.27% of percentage essential oil as compared to untreated control. Nutrient uptake especially N2 content was significantly increased (43% with the treatment T8 (B. megaterium + P. fluorescens + T. viride. Amongst major essential oil constituents, eugenol content was maximally increased by 58.5% as compared to 42.9% (control indicating a cumulative role of microbial inoculants for crop yield boost-up.

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

    PRECIOUS

    2009-12-15

    Dec 15, 2009 ... protease production was 37°C at pH 9, with 2% inoculum in the medium for 24 h. .... Positive. Catalase test. Positive ... The enzyme activity gradually decreases from ... Effect of temperature on protease production by Pseudomonas fluorescens. 0 .... between RNA polymerase and upstream promotes DNA.

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

    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

  20. An integrated approach for the reduction of aflatoxin contamination in chilli (Capsicum annuum L.).

    Sudha, S; Naik, M K; Ajithkumar, K

    2013-02-01

    An integrated approach for management of aflatoxin contamination in chilli was undertaken by evaluating the fungicides, bioagents and plant extracts against Aspergillus flavus under both in vitro and field condition. Maximum inhibition of radial growth (91.1%) was observed with 0.3% mancozeb followed by captan (85.2%). Carbendazim (73%) was effective and superior over other systemic fungicides. A complete inhibition (100%) of A. flavus was observed in neem seed kernel extract (NSKE), nimbicidin and pongamia oil at 5%. An indigenous Pseudomonas fluorescens bioagent isolate inhibited (74.9%) the growth of A. flavus over Trichoderma harzianum (70.4%). The superior performing fungicides, plant extracts and bioagents identified under in vitro were used for challenge inoculation on chilli fruits and so also for field evaluation. The captan treated fruits recorded the least infection of A. flavus (1.6%) followed by P. fluorescens (2.0%), NSKE (2.2%) and nimbicidin treated fruits (7.8%) as against control (38.3%). As regards to field evaluation, the least incidence was recorded in NSKE sprayed chilli plot (1.6%) and was on par with captan (2.2%), P. fluorescens (2.4%) and T. harzianum (2.6%) compared to control (7.4%). Hence, a pre-harvest spray of NSKE (5%) or mancozeb (0.3%) or P. fluorescens (1 × 10(8) cfu/ml) 10 days before harvest of chilli is recommended for field level management of aflatoxin.

  1. Bacterial mediated amelioration of drought stress in drought tolerant ...

    yogendra

    2015-02-23

    Feb 23, 2015 ... for a beneficial effect of PGPRs application in enhancing drought tolerance of rice under water deficit conditions. ..... involvement of PGPRs in ROS metabolism in rice plants. ... osmoregulatory solute in plants (Kumar et al., 2011). ..... Pseudomonas fluorescens mediated saline resistance in groundnut.

  2. Effect of elevated oxygen and carbon dioxide on the surface growth of vegetable-associated micro-organisms

    Amanatidou, A.; Smid, E.J.; Gorris, L.G.M.

    1999-01-01

    The impact of a novel type of Modified Atmosphere (MA), referred to as high O2-MA, on micro-organisms associated with the spoilage of minimally-processed vegetables was studied. Pure cultures of Pseudomonas fluorescens, Enterobacter agglomerans, Aureobacterium strain 27, Candida guilliermondii, C.

  3. Evaluation of some bioagents and botanicals in in vitro control of ...

    SERVER

    2008-04-03

    Apr 3, 2008 ... culture with the pathogen to monitor antagonistic effect. In another experiment, botanicals of tobacco. (Nicotiana tabacum) and castor plant (Ricinus communis) were incorporated as poison in a growth media. Of all the four bio-agents used, only P. fluorescens was able to inhibit the growth of the pathogen.

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

    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.

  5. Comparative evaluation of organic formulations of Pseudomonas ...

    An experiment was conducted in the laboratory and farm of the Department of Biotechnology, Gauhati University, to explore the potentiality of various organic formulations of Pseudomonas fluorescens (Pf) and to manage bacterial wilt disease of brinjal (Solanum melongena L.) under local conditions. Different organic ...

  6. LONG-TERM STARVATION-INDUCED LOSS OF APPARENT ANTIBIOTIC RESISTANCE IN CELLS CONTAINING THE PLASMID PSA

    Escherichia coli, Pseudomonas fluorescens, and a Pseudomonas sp. strain 133B containing the pSa plasmid were starved in well water for up to 523 days. There were two patterns of apparent antibiotic resistance loss observed. In Pseudomonas sp. strain 133B, there was no apparent lo...

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

    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 ...

  8. Rapid prey evolution can alter the structure of predator-prey communities

    Friman, V. -P.; Jousset, A.; Buckling, A.

    Although microevolution has been shown to play an important role in pairwise antagonistic species interactions, its importance in more complex communities has received little attention. Here, we used two Pseudomonas fluorescens prey bacterial strains (SBW25 and F113) and Tetrahymena thermophila

  9. Synergistic interaction in simultaneous exposure to Streptomyces californicus and Stachybotrys chartarum

    Huttunen, K.; Pelkonen, J.; Nielsen, Kristian Fog

    2004-01-01

    chartarum, Bacillus cereus, Mycobacterium terrae, and Pseudomonas fluorescens) alone and together with the actinomycete Streptomyces californicus. The production of nitric oxide, levels of the proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6), and cytotoxicity were...

  10. Protection of melon plants against Cucumber mosaic virus infection ...

    This study was carried out to characterize a virus causing severe mosaic, yellowing, stunting and leaf deformation on melon (Cucumis melo L.), and evaluate the capacity of Pseudomonas fluorescens as biofertilizer to improve plant growth and restrict the accumulation of the virus in the plant. The virus was identified as an ...

  11. In Situ/On-Site Biodegradation of Refined Oils and Fuels (A Technology Review). Volume 2. Appendix A. Supplementary Text.

    1992-06-01

    Naphthalene oxidation predominates in the order Mucorales , which includes species of Cunninghamella, Syncephalastrum, and Mucor (Cerniglia, Hebert, Szaniszlo...naphthal inicum nonl quifaciciens, Pseudomonas desmo 1yticum, P. fluorescens, P. putida biotype B)" ~seudomonas oleovoransg, P. put da ’v, ( Mucorales

  12. Evolution of REP diversity: a comparative study

    Nunvář, Jaroslav; Lichá, I.; Schneider, Bohdan

    2013-01-01

    Roč. 14, č. 385 (2013) ISSN 1471-2164 R&D Projects: GA ČR GAP305/12/1801 Institutional research plan: CEZ:AV0Z50520701 Keywords : REP elements * Stenotrophomonas maltophilia * Pseudomonas fluorescens Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.041, year: 2013

  13. 1373-IJBCS-Article-Lamine Said Babamoussa

    KODJIO NORBERT

    Les rhizobactéries Pseudomonas fluorescens ont induit le rendement de maïs le plus élevé, dépassant de ... Bacillus licheniformis, Bacillus lentus, Bacillus circulans, Bacillus firmus et Azospirillum ..... asiciadas al cultivo del maiz. ... bacteria and their inoculation effects on growth and nitrogen uptake of crop plants. J.

  14. Dicty_cDB: Contig-U14564-1 [Dicty_cDB

    Full Text Available |pid:none) Pseudomonas fluorescens SBW25 c... 32 9.8 DQ447651_7( DQ447651 |pid:none) Lake Victoria marburgv...uschii clone CDS3047 al... 32 9.8 DQ447650_7( DQ447650 |pid:none) Lake Victoria marburgvirus - DRC19... 32 9

  15. ANALYSIS OF MATERIALS IN AN EXPERIMENTAL TESTING PIPE SYSTEM FOR AN INHIBITOR OF MUSSEL KILL

    Daniel P. Molloy

    2003-06-04

    A comprehensive series of 16 laboratory experiments demonstrated that the presence of vinyl tubing within a recirculating pipe system was responsible for lowering zebra mussel kill following treatment with the bacterium Pseudomonas fluorescens. All vinyl tubing was replaced in all testing units with silicone tubing, and high mussel kill (>95%) was then obtained.

  16. An automated technique for most-probable-number (MPN) analysis of densities of phagotrophic protists with lux-AB labelled bacteria as growth medium

    Ekelund, Flemming; Christensen, Søren; Rønn, Regin

    1999-01-01

    An automated modification of the most-probable-number (MPN) technique has been developed for enumeration of phagotrophic protozoa. The method is based on detection of prey depletion in micro titre plates rather than on presence of protozoa. A transconjugant Pseudomonas fluorescens DR54 labelled w...

  17. Utilization of Indigenous Microbial Isolates and their Mutants in the ...

    This study was designed to evaluate the ability of Pseudomonas fluorescens, Aspergillus fumigatus and Aspergillus niger to degrade cellulosic medical waste. Biodegradation was carried out in bioreactors and the ability to degrade or utilize cellulose was established on the basis of bacterial growth on cellulose medium ...

  18. Evaluation of some bioagents and botanicals in in vitro control of ...

    Collectotrichum destructivum has not been effectively controlled. This led to trials on the use of bioagents and botanicals to control the pathogen. The bio-agents such as Pseudomonas fluorescens, Bacillus subtilis, Trichoderma harzianum and Trichoderma pseudokoningii were inoculated as dixenic culture with the ...

  19. Metabolites change in Jatropha plants due to seed treatment with rhizobacteria and Rhizoctonia bataticola

    Surender Kumar

    2013-12-01

    Full Text Available An experiment on the metabolite [salicylic acid (SA, jasmonic acid (JA, hydrocyanic acid (HCN and chitinase activity] changes owing to seed treatn1ent with pathogen, plant growth pron1oting rhizobacteria (PGPRs - (P. maltophilia, P. fluorescens and Bacillus subtilis alone and in combination was conducted at Chaudhary Charan Singh, Haryana Agricultural University, Regional Research Station, Bawal. Jatropha curcas plants raised from root rot pathogen (Rhizoctonia bataticola treated seeds showed an initial increase in SA and hydrocyanic acid HCN content and an opposite trend was observed for JA level and chitinase activity. Though, PGPRs inoculation resulted in higher increase in SA level, JA level and chitinase activity in both the cases alone as well as in integration with pathogen, however, maximun1 increase in JA content was explicited in plants raised after seed treatment with P. fluorescens, the most effective rhizobacteria amongst PGPRs studied. Highest increase in HCN content (45 micrograms g-1 over control (24 micrograms g-1 was noticed for P. fluorescens followed by co-seed inoculation with P. fluorescens + pathogen (43 micrograms g-1 at 10 DPL. The co-seed inoculation elicited 68 units at 10 DPI, whereas the pathogen challenged plants showed lower chitinase activity with 42 units. All the metabolites declined slightly or sharply with age of the plant irrespective of inoculations.

  20. Integrated effect of gamma radiation and biocontrol agent on quality parameters of apple fruit: An innovative commercial preservation method

    Ahari Mostafavi, Hossein; Mahyar Mirmajlessi, Seyed; Fathollahi, Hadi; Shahbazi, Samira; Mohammad Mirjalili, Seyed

    2013-01-01

    Effects of gamma irradiation and biocontrol agent (Pseudomonas fluorescens) on the physico-chemical parameters (including moisture, total soluble solids, antioxidant activity, phenolic content and firmness) of cv. Golden Delicious apples were investigated for their ability to avoid the post-harvest blue mold caused by Penicillium expansum during cold storage. Freshly harvested apples were inoculated with P. expansum. Treated fruits were irradiated at doses of 0, 200, 400, 600 and 800 Gy and then inoculated with P. fluorescens suspension. Samples were evaluated at 3 month intervals. The results demonstrated a clear link between antioxidant activity and phenolic content, so that dose range of 200–400 Gy significantly increased phenolic content and antioxidant activity. Effect of P. fluorescens was similar to irradiation at 200 and 400 Gy that could prevent lesion diameter in pathogen-treated apples. As dose and storage time increased firmness decreased but, combination of P. fluorescens as well as irradiation (at 200–400 Gy) could decrease softening apple fruits during storage. In all parameters, P. fluorescens (as biocontrol agent) inhibited P. expansum similar to irradiation at 200–400 Gy. So, integrated treatment of irradiation and biocontrol agent explored the potential dual benefit of low doses (200 and 400 Gy) as a suitable method to sustain physico-chemical quality and conclusively reduce apple fruits losses during post-harvest preservation. - Highlights: • A suitable method to reduce apple quality losses during 9 month storage period. • Effects of γ radiation in combination with biocontrol agent on physico-chemical parameters of the apple fruits during cold storage. • The potential dual benefit of low irradiation dose combined with biocontrol agent. • Radiation dose determination for Penicillium expansum (postharvest pathogen) control

  1. Reactive oxygen species and hormone signaling cascades in endophytic bacterium induced essential oil accumulation in Atractylodes lancea.

    Zhou, Jia-Yu; Li, Xia; Zhao, Dan; Deng-Wang, Meng-Yao; Dai, Chuan-Chao

    2016-09-01

    Pseudomonas fluorescens induces gibberellin and ethylene signaling via hydrogen peroxide in planta . Ethylene activates abscisic acid signaling. Hormones increase sesquiterpenoid biosynthesis gene expression and enzyme activity, inducing essential oil accumulation. Atractylodes lancea is a famous Chinese medicinal plant, whose main active components are essential oils. Wild A. lancea has become endangered due to habitat destruction and over-exploitation. Although cultivation can ensure production of the medicinal material, the essential oil content in cultivated A. lancea is significantly lower than that in the wild herb. The application of microbes as elicitors has become an effective strategy to increase essential oil accumulation in cultivated A. lancea. Our previous study identified an endophytic bacterium, Pseudomonas fluorescens ALEB7B, which can increase essential oil accumulation in A. lancea more efficiently than other endophytes; however, the underlying mechanisms remain unknown (Physiol Plantarum 153:30-42, 2015; Appl Environ Microb 82:1577-1585, 2016). This study demonstrates that P. fluorescens ALEB7B firstly induces hydrogen peroxide (H2O2) signaling in A. lancea, which then simultaneously activates gibberellin (GA) and ethylene (ET) signaling. Subsequently, ET activates abscisic acid (ABA) signaling. GA and ABA signaling increase expression of HMGR and DXR, which encode key enzymes involved in sesquiterpenoid biosynthesis, leading to increased levels of the corresponding enzymes and then an accumulation of essential oils. Specific reactive oxygen species and hormone signaling cascades induced by P. fluorescens ALEB7B may contribute to high-efficiency essential oil accumulation in A. lancea. Illustrating the regulation mechanisms underlying P. fluorescens ALEB7B-induced essential oil accumulation not only provides the theoretical basis for the inducible synthesis of terpenoids in many medicinal plants, but also further reveals the complex and diverse

  2. Differentiation of isolated native of desulphurizators Pseudomonas by means of the study of the profile of fatty acids

    Silva Gomez, Edelberto; Morales P, Alicia Lucia; Callejas Castro Solange; Florez Sandoval Maria Cecilia; Rodriguez Wilson

    2000-01-01

    The content of cellular fatty acids was determined by HRGC of twelve Colombian isolated Pseudomonas aeruginosa 17,18, 19, 20, 21, 22 and 103 pseudomonas sp 23,24,25,26 and 27 with desulphurization capacity, pseudomonas aeruginosa ATCC 9027 and 10145, pseudomonas sp ATCC 39327 and pseudomonas fluorescens. Fifty-three different types of fatty acids were found, among saturated and unsaturated of lineal chain, and mainly hydroxy acids and ramified. Of these, 17 have not been described in the literature for this genus. A group of 6 acids was presented with more frequency (15:0; 16:0; 16:1; 17:1; 3-OH 16:0 and 2-OH 15:0) in more than 75% of the pseudomonas studied. The studied microorganisms are related because they share the presence of some characteristic fatty acids, that which allows assuring that they belong to same taxonomic unit. The analysis cluster developed by means of plotting in dendrograms of the qualitative and quantitative contents of the acids fatty totals showed the formation of two attaches, the I conformed by ATCC 39327 and the isolated 17 and 25, and the II by Ps. Fluorescens and the isolated one 27. The dendrogram of the hydroxy acids shows the formation of four attaches, the I attache, (isolated 17 and 20), the II A (isolated 22 and 103), the II B (isolated 27 and ps. fluorescens) and the attache III (isolated 18 and 19). In that of the ramified fatty acids the formation of a main attache is observed conformed by four sub-groups, the IA (isolated 17), the I B (isolated 18 and 24), the I C (isolated 19 and 25 and Ps. fluorescens) and I D (isolated 27). These results show that the isolated 27,25,24, 19, 18 and 17, in their order, have narrow relationship to Ps. fluorescens

  3. Combined use of different Gfp reporters for monitoring single-cell activities of a genetically modified PCB degrader in the rhizosphere of alfalfa

    Boldt, T.S.; Sørensen, J.; Karlsson, U.

    2004-01-01

    Single-cell localization and activity of Pseudomonas,fluorescens F113, colonizing alfalfa roots, were monitored using fusions of the Escherichia coli rrnBP1 ribosomal promoter and gfp genes encoding green fluorescent protein (Gfp) of different stability. The monitoring systems permitted non...... of chlorinated biphenyl was constructed, using another gfp fusion with the meta-pathway Pin promoter from Pseudomonas putida (TOL plasmid). Expression of this promoter, which is strongly induced by the PCB-2 degradation product, 3-chlorobenzoate, was tested in vitro and subsequently monitored in vivo on alfalfa...... roots using the P. fluorescens F113rifpcb reporter. A small but distinct fraction of the introduced bacteria activated the Pm promoter and thus appeared to sense a PCB-2 degradation product in the alfalfa rhizosphere. The degrading cells, which by design were identical to the sensing cells, were located...

  4. IMPACT OF WATER PH ON ZEBRA MUSSEL MORTALITY

    Molloy, Daniel P.

    2002-01-01

    The experiments conducted this past quarter have suggested that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels throughout the entire range of pH values tested (7.2 to 8.6). Highest mortality was achieved at pH values characteristic of preferred zebra mussel waterbodies, i.e., hard waters with a range of 7.8 to 8.6. In all water types tested, however, ranging from very soft to very hard, considerable mussel kill was achieved (83 to 99% mean mortality), suggesting that regardless of the pH or hardness of the treated water, significant mussel kill can be achieved upon treatment with P. fluorescens strain CL0145A. These results further support the concept that this bacterium has significant potential for use as a zebra mussel control agent in power plant pipes receiving waters with a wide range of physical and chemical characteristics

  5. Antibiotic and biosurfactant properties of cyclic lipopeptides produced by fluorescent Pseudomonas spp. from the sugar beet rhizosphere

    Nielsen, T.H.; Sørensen, D.; Tobiasen, C.

    2002-01-01

    Cyclic lipopeptides (CLPs) with antibiotic and biosurfactant properties are produced by a number of soil bacteria, including fluorescent Pseudomonas spp. To provide new and efficient strains for the biological control of root-pathogenic fungi in agricultural crops, we isolated approximately 600...... fluorescent Pseudomonas spp. from two different agricultural soils by using three different growth media. CLP production was observed in a large proportion of the strains (approximately 60%) inhabiting the sandy soil, compared to a low proportion (approximately 6%) in the loamy soil. Chemical structure...... in the peptide moiety. Production of specific CLPs could be affiliated with Pseudomonas fluorescens strain groups belonging to biotype I, V, or VI. In vitro analysis using both purified CLPs and whole-cell P. fluorescens preparations demonstrated that all CLPs exhibited strong biosurfactant properties...

  6. Removal of Cadmium and Zinc from Soil using Immobilized Cell of Biosurfactant Producing Bacteria

    Charoon Sarin

    2010-07-01

    Full Text Available Immobilized biosurfactant producing bacteria (Bacillus subtilis TP8 and Pseudomonas fluorescens G7 were assessed for survival in heavy metal contaminated soil and for their ability to remove cadmium and zinc from contaminated soil. P. fluorescens G7 was considered to be a good candidate for bioremediation of heavy metals because of its high minimum inhibitory concentrations (MIC for each heavy metal and because of the obviously increased numbers of cell surviving after incubation in the heavy metal contaminated soil up to 4 weeks. The results of soil remediation showed that approximately 19% of Zn and 16.7% of Cd could be removed by this immobilized biosurfactant producing bacteria after incubation for 2 weeks. The results confirm the potential applicability of the immobilized biosurfactant producing bacteria for heavy metal bioremediation.

  7. Continuous measurements of nitrous oxide isotopomers during incubation experiments

    Winther, Malte Nordmann; Balslev-Harder, David; Christensen, Søren

    2016-01-01

    relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N2O) and P. chlororaphis (only producing N2O). The continuous position dependent measurements reveal the transient pattern....... fluorescens, the calculations results in SP values of −5.7 ‰ ± 5.6 during production of N2O and 2.3 ‰ ± 3.2 during reduction of N2O. In summary, we implemented continuous measurements of N2O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better...... understanding of denitrifying bacteria and N2O turnover in soils and sediments and ultimately hands-on knowledge on the biotic mechanisms behind greenhouse gas exchange of the Globe....

  8. IMPACT OF WATER PH ON ZEBRA MUSSEL MORTALITY

    Daniel P. Molloy

    2002-10-15

    The experiments conducted this past quarter have suggested that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels throughout the entire range of pH values tested (7.2 to 8.6). Highest mortality was achieved at pH values characteristic of preferred zebra mussel waterbodies, i.e., hard waters with a range of 7.8 to 8.6. In all water types tested, however, ranging from very soft to very hard, considerable mussel kill was achieved (83 to 99% mean mortality), suggesting that regardless of the pH or hardness of the treated water, significant mussel kill can be achieved upon treatment with P. fluorescens strain CL0145A. These results further support the concept that this bacterium has significant potential for use as a zebra mussel control agent in power plant pipes receiving waters with a wide range of physical and chemical characteristics.

  9. In vitro efficacy of bacterial endophytes against the chilli damping-off pathogen Pythium aphanidermatum

    Arjunan MUTHUKUMAR

    2010-09-01

    Full Text Available Damping-off of chilli caused by Pythium aphanidermatum is a major nursery disease in vegetables. The effect of ten endophytic isolates of Pseudomonas fluorescens was tested against P. aphanidermatum under in vitro conditions. All the isolates tested were short rods and produced bright fluorescence when exposed to UV light. Among the isolates, EBS 20 produced the largest inhibition zone and the least mycelial growth of P. aphanidermatum. With regard to the secondary metabolites, P. fluorescens EBS 20 produced most salicylic acid, siderophore and hydrogen cyanide. The culture filtrate of this isolate at a 15% concentration totally inhibited mycelial growth of P. aphanidermatum. In addition, chilli seeds treated with culture filtrate of this isolate also led to the greatest plant growth in terms of root length, shoot length and vigour index.

  10. Co-metabolic formation of substituted phenylacetic acids by styrene-degrading bacteria

    Michel Oelschlägel

    2015-06-01

    The styrene-degrading strains Rhodococcus opacus 1CP, Pseudomonas fluorescens ST, and the novel isolates Sphingopyxis sp. Kp5.2 and Gordonia sp. CWB2 were investigated with respect to their applicability to co-metabolically produce substituted phenylacetic acids. Isolates were found to differ significantly in substrate tolerance and biotransformation yields. Especially, P. fluorescens ST was identified as a promising candidate for the production of several phenylacetic acids. The biotransformation of 4-chlorostyrene with cells of strain ST was shown to be stable over a period of more than 200 days and yielded about 38 mmolproduct gcelldryweight−1 after nearly 350 days. Moreover, 4-chloro-α-methylstyrene was predominantly converted to the (S-enantiomer of the acid with 40% enantiomeric excess.

  11. Pathogens Present in Acute Mangled Extremities From Afghanistan and Subsequent Pathogen Recovery

    2015-01-01

    0/pre-), Kloeckera spp (PID 0/post-) 4 Aspergillus niger (PID 5) 3 LLE 3 P. stutzeri (PID 0/pre-), P. fluorescens (PID 0/pre-), CNS (PID 0/pre...Streptococcus viridans group (PID 0/post-) 4 Penicillium spp (PID 5), Aspergillus spp (PID 5), Enterococcus hirae (PID 5), Bacillus spp (PID 5) 5 P...Penicillium spp (PID 1), Aspergillus spp (PID 1), Enterococcus faecium (PID 1) 5 E. coli (PID 7) LLE, left lower extremity; RLE, right lower extremity

  12. NeutrAvidin Functionalization of CdSe/CdS Quantum Nanorods and Quantification of Biotin Binding Sites using Biotin-4-Fluorescein Fluorescence Quenching

    Lippert, Lisa G.; Hallock, Jeffrey T.; Dadosh, Tali; Diroll, Benjamin T.; Murray, Christopher B.; Goldman, Yale E.

    2016-01-01

    We developed methods to solubilize, coat, and functionalize with NeutrAvidin elongated semiconductor nanocrystals (quantum nanorods, QRs) for use in single molecule polarized fluorescence microscopy. Three different ligands were compared with regard to efficacy for attaching NeutrAvidin using the “zero-length cross-linker” 1-ethyl-3-[3-(dimethylamino)propyl]-carbodiimide (EDC). Biotin-4-fluorescene (B4F), a fluorophore that is quenched when bound to avidin proteins, was used to quantify bioti...

  13. Biotransformations with nitrilases

    Martínková, Ludmila; Křen, Vladimír

    2010-01-01

    Roč. 14, č. 2 (2010), s. 130-137 ISSN 1367-5931 R&D Projects: GA AV ČR IAA500200708; GA MŠk(CZ) LC06010; GA MŠk OC09046; GA MPO FT-TA5/043 Institutional research plan: CEZ:AV0Z50200510 Keywords : ENZYME-PROMOTED DESYMMETRISATION * PSEUDOMONAS-FLUORESCENS EBC191 * SUBSTRATE-SPECIFICITY Subject RIV: CE - Biochemistry Impact factor: 9.312, year: 2010

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

    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.

  15. Gamma-ray decontamination of sodium lauryl-ethoxy-sulfate (SLES): microbiological and physicochemical aspects

    Lorelli, C. H.; Curzio, O. A.; Horak, Celina I.; Fernandez Gianotti, Tomas; Kairiyama, Eulogia

    1999-01-01

    Sodium Lauryl-Ethoxy-Sulfate (SLES) is used as a tensioactive in several cleaning and cosmetic products. The paper describes the irradiation tests carried out to decontaminate SLES. The results demonstrate that: 1) 60 Co gamma irradiation of SLES reduces the content of Pseudomona aeroginosa and Pseudomona fluorescens to the levels required by commercial specification; 2) The irradiation with doses u p to 200 Gy does not modify the tensioactive properties of the products. (author)

  16. Utilization of biological control agents for the management of postharvest pathogens of tomato

    Zafar, M.U.; Ansari, S.U.

    2016-01-01

    Twenty five isolates of Trichoderma, Bacillus and Pseudomonas spp. were obtained from rhizosphere of tomato growing fields using soil dilution technique on potato dextrose agar (PDA) and nutrient agar (NA) medium. Screening of these isolates were done against Geotrichum candidum, Trichothecium roseum and Rhizopus oryzae, causal agents of sour rot, pink mold rot and Rhizopus soft rot of tomato under the laboratory conditions. One promising isolate of each Trichoderma harzianum, Bacillus spp. and Pseudomonas fluorescens from the twenty five isolates were chosen and further evaluated as potential biological control agents (BCAs) against three important postharvest pathogens of tomato. Dual culture and spore concentration assay revealed that all three isolates inhibited radial growth of G. candidum, T. roseum and R. oryzae. Tomato fruits were inoculated with 25 micro L suspension of 10/sup 8/ cfu mL-1 for T. harzianum and 10/sup 8/cfu mL-1for each Bacillus sp. and P. fluorescens. Twenty four hours later the treated fruits were inoculated with 25 micro L of 105 conidia/mL of each of three postharvest pathogens. The results showed that P. fluorescens provided good control (78.1%) of G. candidum and (82.2%) R. oryzae, while, T. harzianum proved less effective to control all three pathogens. Bacillus spp. was only effective (88.4%) against T. roseum. Hence, our results depicted that Bacillus spp. and P. fluorescens proved to be a potential antagonist of T. roseum and R. oryzae however, all the tested BCAs were not consistent in their action against three postharvest pathogens of tomato. (author)

  17. Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent

    Petti, Carloalberto; Reiber, Kathrin; Ali, Shahin S; Berney, Margaret; Doohan, Fiona M

    2012-01-01

    Abstract Background Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA) and abscisic acid (ABA), are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB) disease of barley and to determine if biocontr...

  18. The Effect of Robusta Coffe Extract (Coffea Robusta) as Inhibitors of Growth Staphylococcus Aureus

    Mumun Nurmilawati, Muhammad Ainul Yaqin

    2015-01-01

    Chlorogenic and caffeine acid, which is a non-volatile organic acids in coffee, which can prevent the growth of some gram-positive and gram-negative bacteria including Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, Pseudomonas fluorescens, Staphylococcus aureus, Bacillus cereus, Lactobacillus bulgaricus, Streptococcus lactis and Streptococcus faecalis.Subject used in this study was Staphylococcus aureus were divided into 5 groups, where each group consisting of 8 repetitions. The...

  19. Dicty_cDB: Contig-U10497-1 [Dicty_cDB

    Full Text Available ce 9 from Patent WO0234921. ... 79 2e-13 AF511570_1( AF511570 |pid:none) Uncultured soil bacterium clone 57....000542_2092( CP000542 |pid:none) Verminephrobacter eiseniae EF01... 58 4e-07 AF511571_1( AF511571 |pid:none) Uncultured soil... Pseudomonas fluorescens Pf0-1, ... 51 7e-05 AF511572_1( AF511572 |pid:none) Uncultured soil bacterium clone

  20. Development of immunoassay for the identification of cold shock ...

    AJB SERVER

    2007-02-05

    Feb 5, 2007 ... Ps. fluorescens MTCC 665 and its mutants were incubated on trypticase soya peptone (TSP) broth composed of 0.5% soya peptone, 1.5% peptone, and 0.5% NaCl (pH-7.0) or TSP agar (TSP broth + 2% w/v agar). All other strains were incubated on nutrient broth composed of 0.5% peptone and 0.3% beef ...

  1. WW Domain Folding Complexity Revealed by Infrared Spectroscopy

    Davis, Caitlin M.; Dyer, R. Brian

    2014-01-01

    Although the intrinsic tryptophan fluorescence of proteins offers a convenient probe of protein folding, interpretation of the fluorescence spectrum is often difficult because it is sensitive to both global and local changes. Infrared (IR) spectroscopy offers a complementary measure of structural changes involved in protein folding, because it probes changes in the secondary structure of the protein backbone. Here we demonstrate the advantages of using multiple probes, infrared and fluorescen...

  2. Bioremediation of Petroleum hydrocarbon by using Pseudomonas species isolated from Petroleum contaminated soil

    Vijay Kumar; Simranjeet Singh; Anu Manhas; Joginder Singh; Sourav Singla; Parvinder Kaur; Shivika Data; Pritika Negi; Arjun Kalia

    2014-01-01

    A newly isolated strain Pseudomonas fluorescens (Accession number KF 279042.1) have potential in diesel degradation and can be recommended for bioremediation of sites that are contaminated with diesel. This bacterium was characterized on the basis of microbiological, biochemical and molecular analysis. Bacterial growth optimization was studied based on carbon source, nitrogen source, pH and temperature. The strain was selected based on its ability to show growth in medium containing diesel. I...

  3. Comparing a microbial biocide and chlorine as zebra mussel control strategies in an Irish drinking water treatment plant

    Sara Meehan; Frances E. Lucy; Bridget Gruber; Sarahann Rackl

    2013-01-01

    A need exists for an environmentally friendly mussel control method to replace chlorine and other traditional control methods currentlyutilised in drinking water plants and other infested facilities. Zequanox® is a newly commercialised microbial biocide for zebra and quaggamussels comprised of killed Pseudomonas fluorescens CL145A cells. The objective of this study was to compare the efficacy of adevelopmental formulation of Zequanox (referred to as MBI 401 FDP) and chlorine treatments on adu...

  4. Comparison of methods for detection and enumeration of airborne microorganisms collected by liquid impingement.

    Terzieva, S; Donnelly, J; Ulevicius, V; Grinshpun, S A; Willeke, K; Stelma, G N; Brenner, K P

    1996-01-01

    Bacterial agents and cell components can be spread as bioaerosols, producing infections and asthmatic problems. This study compares four methods for the detection and enumeration of aerosolized bacteria collected in an AGI-30 impinger. Changes in the total and viable concentrations of Pseudomonas fluorescens in the collection fluid with respect to time of impingement were determined. Two direct microscopic methods (acridine orange and BacLight) and aerodynamic aerosol-size spectrometry (Aeros...

  5. Dopamine-functionalized InP/ZnS quantum dots as fluorescence probes for the detection of adenosine in microfluidic chip

    An, Seong Soo; Ankireddy,Seshadri Reddy; Kim,Jongsung

    2015-01-01

    Seshadri Reddy Ankireddy, Jongsung Kim Department of Chemical and Biological Engineering, Gachon University, Seongnam, Gyeonggi-Do, South Korea Abstract: Microbeads are frequently used as solid supports for biomolecules such as proteins and nucleic acids in heterogeneous microfluidic assays. Chip-based, quantum dot (QD)-bead-biomolecule probes have been used for the detection of various types of DNA. In this study, we developed dopamine (DA)-functionalized InP/ZnS QDs (QDs-DA) as fluorescen...

  6. Evaluation of antibacterial properties of some medicinal plants used in Iran.

    Bonjar, Shahidi

    2004-10-01

    Forty-five species of 29 plant families used in the traditional medicine by Iranian people, showed antibacterial activities against one or more of the bacterial species: Bacillus cereus, Bacillus pumilus, Bordetella bronchiseptica, Escherichia coli, Klebsiella pneumoniae, Micrococcus luteus, Pseudomonas aeruginosa, Pseudomonas fluorescens, Serratia marcescens, Staphylococcus aureus and Staphylococcus epidermidis. No plant showed activity against Serratia marcescens; Bordetella bronchiseptica being the most susceptible species. All extracts showed the same activity 18 months later.

  7. Detection of Methylobacterium radiotolerans IMBG290 in potato plants by in situ hybridization

    Pirttila A. M.; Kozyrovska N. O.; Ovcharenko L. P.; Podolich O. V.

    2009-01-01

    A new bacterial strain of pink-pigmented facultative methylotroph (M. radiotolerans IMBG290) which was previously isolated from in vitro grown potato plantlets after their inoculation with Pseudomonas fluorescens IMBG163 was detected in tissues by in situ hybridization method (ISH/FISH). The presence of Methylobacterium rRNA was observed in leaves and stems of potato plantlets, whereas no signal was detected in potato roots. The signal was less abundant in the untreated plants than in the pla...

  8. Development of an online biosensor for in situ monitoring of chlorine dioxide gas disinfection efficacy

    Del Busto-Ramos, M.; Budzik, M.; Corvalan, C.; Morgan, M.; Nivens, D.; Applegate, B. [Purdue Univ., West Lafayette, IN (United States). Dept. of Food Science; Turco, R. [Purdue Univ., West Lafayette, IN (United States). Dept. of Agronomy

    2008-03-15

    A prototype bioluminescence-based biosensor was designed and constructed to evaluate the antimicrobial efficacy of chlorine dioxide (ClO{sub 2}) gas under various treatment conditions. The biosensor consisted of a bioluminescent bioreporter (Pseudomonas fluorescens 5RL), an optical transducer (photomultiplier tube), and a light-tight chamber housing, the bioreporter and the transducer. The bioluminescent recombinant P. fluorescens 5RL in the biosensor allowed for online monitoring of bioluminescence during ClO{sub 2} gas disinfection. Experiments were performed to evaluate the effects of the two key physical parameters associated with ClO{sub 2} disinfection: relative humidity (40, 60, 80%) and ClO{sub 2} gas concentration (0.5, 1.0, 1.6, 2.1 mg/l) on the bioreporter. Results showed that increasing concentrations of ClO{sub 2} gas corresponded to a faster decrease in luminescence. The rates of luminescence decrease from P. fluorescens 5RL, and the log reduction time (LRT, time required to obtain 1-log reduction in luminescence) were calculated for each treatment tested. The LRT values of luminescence were 103, 78, 53, and 35 s for 0.5, 1.0, 1.6, and 2.1 mg/l of ClO{sub 2} gas treatment, respectively, at 78% relative humidity. The gas concentration which caused a tenfold change in LRT (z value) for luminescence of P. fluorescens 5RL was 3.4 mg/l of ClO{sub 2}. The prototype biosensor showed potential for many applications, such as monitoring real-time microbial inactivation and understanding parameters that influence the efficacy of gaseous decontamination procedures. (orig.)

  9. Catalase and Superoxide Dismutase of Root-Colonizing Saprophytic Fluorescent Pseudomonads †

    Katsuwon, Jirasak; Anderson, Anne J.

    1990-01-01

    Root-colonizing, saprophytic fluorescent pseudomonads of the Pseudomonas putida-P. fluorescens group express similar levels of catalase and superoxide dismutase activities during growth on a sucrose- and amino acid-rich medium. Increased specific activities of catalase but not superoxide dismutase were observed during growth of these bacteria on components washed from root surfaces. The specific activities of both enzymes were also regulated during contact of these bacteria with intact bean r...

  10. Immobilized Lipases on Functionalized Silica Particles as Potential Biocatalysts for the Synthesis of  Fructose Oleate in an Organic Solvent/Water System

    Vinicius Vescovi; Raquel L. C. Giordano; Adriano A. Mendes; Paulo W. Tardioli

    2017-01-01

    Lipases from Thermomyces lanuginosus (TLL) and Pseudomonas fluorescens (PFL) wereimmobilized on functionalized silica particles aiming their use in the synthesis of fructose oleate in a tert‐butyl alcohol/water system. Silica particles were chemically modified with octyl (OS), octyl plus glutaraldehyde (OSGlu), octyl plus glyoxyl(OSGlx), and octyl plus epoxy groups(OSEpx). PFL was hyperactivated on all functionalized supports (more than 100% recovered activity) using low protein loading (1 mg...

  11. Microbial Community Analysis of Field-Grown Soybeans with Different Nodulation Phenotypes▿

    Ikeda, Seishi; Rallos, Lynn Esther E.; Okubo, Takashi; Eda, Shima; Inaba, Shoko; Mitsui, Hisayuki; Minamisawa, Kiwamu

    2008-01-01

    Microorganisms associated with the stems and roots of nonnodulated (Nod−), wild-type nodulated (Nod+), and hypernodulated (Nod++) soybeans [Glycine max (L.) Merril] were analyzed by ribosomal intergenic transcribed spacer analysis (RISA) and automated RISA (ARISA). RISA of stem samples detected no bands specific to the nodulation phenotype, whereas RISA of root samples revealed differential bands for the nodulation phenotypes. Pseudomonas fluorescens was exclusively associated with Nod+ soybe...

  12. Investigation of Real-Time Two-Dimensional Visualization of Fuel Spray Liquid/Vapor Distribution via Exciplex Fluorescence.

    1987-08-30

    EXCIPLEX FLUORESCENCE ~N 0FINAL REPORT 00 JAMES F. VERDIECK AND ARTHUR A. ROTUNNO UNITED TECHNOLOGIES RESEARCH CENTER 0 AND LYNN A. MELTON D I UNIVERSITY...DOCUMENTATION. "NWA 0. INVESTIGATION OF REAL-TINE TWO-DIMENSIONAL VISUALIZATION OF FUEL SPRAY LIQUID/VAPOR DISTRIBUTION VIA EXCIPLEX FLUORESCENCE FINAL...Spray Liquid/Vapor Distribution Via Exciplex Fluorescen , - 12. PERSONAL AUTHOR(S) J. F. Yeardierk. A- A. Rnriiunn-l L_ A. Millo - 13a TYPE OF REPORT

  13. Dicty_cDB: Contig-U16219-1 [Dicty_cDB

    Full Text Available CP000094 |pid:none) Pseudomonas fluorescens Pf0-1, ... 235 6e-60 AB241242_1( AB241242 |pid:none) Symbiotic p...59 CP000378_251( CP000378 |pid:none) Burkholderia cenocepacia AU 1054... 233 2e-59 AB241241_1( AB241241 |pid:none) Symbiotic...243 |pid:none) Trichomonas vaginalis strain G3 sm... 220 1e-55 AB241243_1( AB241243 |pid:none) Symbiotic pro

  14. Interactions between biosurfactant-producing Pseudomonas and Phytophthora species

    Tran, H.

    2007-01-01

    Fluorescent Pseudomonas bacteria produce a wide variety of antimicrobial metabolites, including soap-like compounds referred to as biosurfactants. The results of this thesis showed that biosurfactant-producing Pseudomonas bacteria are effective in controlling Phytophthora foot rot disease of black pepper in Vietnam and promote root and shoot development of the ‘King of Spices’. Biosurfactant-producing P. fluorescens strain SS101 was also effective in controlling tomato late blight caused by P...

  15. Influence of Nitrogen Source on 2,4-diacetylphloroglucinol Production by the Biocontrol Strain Pf-5

    M, Hultberg; B, Alsanius

    2008-01-01

    The production of 2,4-diacetylphloroglucinol (DAPG) by the biocontrol agent Pseudomonas fluorescens Pf-5 was studied in nutrient-solution based media with varying nitrogen content. No production of DAPG was observed when organic nitrogen was omitted from the media, regardless of the inorganic nitrogen source used. Furthermore, a micromolar concentration range of organic nitrogen was insufficient to sustain production. When a millimolar concentration range of organic nitrogen was used, DAPG pr...

  16. OI Fluorescent Line Contamination in Soft X-Ray Diffuse Background Obtained with Suzaku/XIS

    Sekiya, Norio; Yamasaki, Noriko Y.; Mitsuda, Kazuhisa; Takei, Yoh

    2014-01-01

    The quantitative measurement of OVII line intensity is a powerful method for understanding the soft X-ray diffuse background. By systematically analyzing the OVII line intensity in 145 high-latitude Suzaku/XIS observations, the flux of OI fluorescent line in the XIS spectrum, contaminating the OVII line, is found to have an increasing trend with time especially after 2011. For these observations, the OVII line intensity would be overestimated unless taking into consideration the OI fluorescen...

  17. Identification of fungal plant pathogens associated with oak (Quercus humboldtii Bonpl.), In the municipalities of Encino (Santander), Arcabuco, and Tipacoque (Boyaca)

    Monroy Castro, Leidi Yunari; Lizarazo Forero, Luz Marina

    2010-01-01

    The objectives of this study were to isolate and determine the presence of the pathogen Phytophthora ramorum and other potential pathogens of Quercus humboldtii, and evaluate the possibility of using the antagonistic capacity of bacteria isolated from rhizosphere and phyllosphere against them. The study was conducted in the conservation corridor Guantiva - La Rusia - Iguaque, in the municipalities of Encino (Santander), Arcabuco and Tipacoque (Boyaca). The phytopathogenic fungi were isolated using direct seeding of leaves with symptoms of fungal infection in OGY, Sabouraud, and PDA + Lactic acid at 0.2%. We used the plate counting technique for the isolation of bacteria from rhizospheric and bulk soil. Phytophthora ramorum was not isolated, but phytopathogenic fungi of the genus Fusarium spp., and Pestalotia spp., were obtained in the isolates. Microbial populations of rhizospheric and bulk soil were scarce, exhibited low diversity, and were dominated by few morphotypes. We identified four species of bacteria: Pseudomonas fluorescens, Bacillus macerans, Pinus sylvestris and Staphylococcus epidermidis. The phyllosphere community was dominated by Pseudomonas fluorescens. The species Pseudomonas fluorescens and Pinus sylvestris did not exhibited antagonistic properties against Pestalotia spp. Further studies are required to confirm Fusarium spp., and Pestalotia spp., pathogenic activity against Quercus humboldtii.

  18. Antifouling coatings via plasma polymerization and atom transfer radical polymerization on thin film composite membranes for reverse osmosis

    Hirsch, Ulrike; Ruehl, Marco; Teuscher, Nico; Heilmann, Andreas

    2018-04-01

    A major drawback to otherwise highly efficient membrane-based desalination techniques like reverse osmosis (RO) is the susceptibility of the membranes to biofouling. In this work, a combination of plasma activation, plasma bromination and surface-initiated atom transfer radical polymerization (si-ATRP) of hydrophilic and zwitterionic monomers, namely hydroxyethyl methacrylate (HEMA), 2-methacryloyloxyethyl phosphorylcholine (MPC) and [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), was applied to generate non-specific, anti-adhesive coatings on thin film composite (TFC) membranes. The antifouling effect of the coatings was shown by short-time batch as well as long-time steady state cultivation experiments with the microorganism Pseudomonas fluorescens. It could be shown that plasma functionalization and polymerization is possible on delicate thin film composite membranes without restricting their filtration performance. All modified membranes showed an increased resistance towards the adhesion of Pseudomonas fluorescens. On average, the biofilm coverage was reduced by 51.4-12.6% (for HEMA, SBMA, and MPC), the highest reduction was monitored for MPC with a biofilm reduction by 85.4%. The hydrophilic coatings applied did not only suppress the adhesion of Pseudomonas fluorescens, but also significantly increase the permeate flux of the membranes relative to uncoated membranes. The stability of the coatings was however not ideal and will have to be improved for future commercial use.

  19. Isolation of Biosurfactant–Producing Bacteria with Antimicrobial Activity against Bacterial Pathogens

    Siripun Sarin

    2011-01-01

    Full Text Available The aims of this research were to study biosurfactant producing bacteria isolated from soil and to determine their property and efficiency as biosurfactants in order to inhibit bacterial pathogens. The result showed that there were 8 bacterial isolates out of 136 isolates of the total biosurfactant producing bacteria screened that exhibited the diameter of clear zone more than 1.5 cm. in the oil spreading test. The highest potential of emulsifying activity (%EA24 of 54.4 and the maximum additive concentration, (%MAC of 24.2 was obtained from the fermentation broth of the G7 isolate which the G7 isolate was later identified as Pseudomonas fluorescens. Escherichia coli, Staphylococcus aureus and Psuedomonas aeruginosa were the tested bacterial pathogens that were most sensitive to the acid precipitated biosurfactant obtained from P. fluorescens G7 with the lowest minimum inhibitory concentration (MIC of 41.6 mg/ml and minimum bactericidal concentration (MBC of 41.6 mg/ml compared with the acid precipitated bisurfactants of the other isolates used in the antimicrobial activity test. The type of the separated crude biosurfactant produced by P. fluorescens G7 analyzed later by using the rhamose test, TLC and FT-IR techniques was rhamnolipid.

  20. Characterization of rhizobacteria associated to maize crop in IAA, siderophores and salicylic acid metabolite production

    Annia Hernández

    2004-01-01

    Full Text Available It has been demonstrated that rhizobacteria are able to produce metabolites having agricultural interest, including salicylic acid, the siderophores and phytohormones. Indol acetic acid (IAA is the most well-known and studied auxin, playing a governing role in culture growth. The object of this work was to characterise rhizobacteria associated with the maize crop in terms of producing IAA, siderophores and salicylic acid metabolites. Burkholderia cepacia and Pseudomonas fluorescens strains previously isolated from maize Francisco variety rhizosphere were used. Colorimetric and chromatographic techniques for detecting these metabolites were studied; multi-variable analysis of hierarchic conglomerate and complete ligament were used for selecting the best strains for producing metabolites of interest. These results demonstrated that all rhizobacteria strains studied produced IAA, siderophores and salicylic acid metabolites. Burkholderia cepacia MBf21, MBp1, MBp2, MBf22, MBp3, MBf20, MBf 15 and Pseudomonas fluorescens MPp4strains have presented the greatest production of these metabolites, showing that these strains could be used in promoting vegetal growth in economically important cultures. Key words: Pseudomonas fluorescens, Burkholderia cepacia, IAA, siderophore, salicylic acid.

  1. Isolation and identification of plant growth promoting rhizobacteria from maize (Zea mays L. rhizosphere and their plant growth promoting effect on rice (Oryza sativa L.

    Karnwal Arun

    2017-06-01

    Full Text Available The use of plant growth promoting rhizobacteria is increasing in agriculture and gives an appealing manner to replace chemical fertilizers, pesticides, and dietary supplements. The objective of our research was to access the plant growth promotion traits of Pseudomonas aeruginosa, P. fluorescens and Bacillus subtilis isolated from the maize (Zea mays L. rhizosphere. In vitro studies showed that isolates have the potential to produce indole acetic acid (IAA, hydrogen cyanide, phosphate solubilisation, and siderophore. RNA analysis revealed that two isolates were 97% identical to P. aeruginosa strain DSM 50071 and P. aeruginosa strain NBRC 12689 (AK20 and AK31, while two others were 98% identical to P. fluorescens strain ATCC 13525, P. fluorescens strain IAM 12022 (AK18 and AK45 and one other was 99% identical to B. subtilis strain NCDO 1769 (AK38. Our gnotobiotic study showed significant differences in plant growth variables under control and inoculated conditions. In the present research, it was observed that the isolated strains had good plant growth promoting effects on rice.

  2. Successful strategy for the selection of new strawberry-associated rhizobacteria antagonistic to Verticillium wilt.

    Berg, G; Kurze, S; Buchner, A; Wellington, E M; Smalla, K

    2000-12-01

    In order to isolate and characterize new strawberry-associated bacteria antagonistic to the soil-borne pathogenic fungus Verticillium dahliae Kleb., rhizobacterial populations from two different strawberry species, Greenish Strawberry (Fragaria viridis) and Garden Strawberry (F. x ananassa) obtained after plating onto King's B and glycerol-arginine agar, were screened for in vitro antagonism toward V. dahliae. The proportion of isolates with antifungal activity determined in in vitro assay against V. dahliae was higher for the Garden Strawberry than for the Greenish Strawberry. From 300 isolates, 20 isolates with strong antifungal activity were selected characterized by physiological profiling and molecular fingerprinting methods. Diversity among the isolates was characterized with molecular fingerprints using amplified ribosomal DNA restriction analysis (ARDRA) and the more discriminating BOX-PCR fingerprint method. The physiological profiles were well correlated with molecular fingerprinting pattern analysis. Significant reduction of Verticillium wilt by bacterial dipping bath treatment was shown in the greenhouse and in fields naturally infested by V. dahliae. The relative increase of yield ranged from 117% (Streptomyces albidoflavus S1) to 344% (Pseudomonas fluorescens P10) in greenhouse trials, and 113% (Streptomyces albidoflavus S1) to 247% (Pseudomonas fluorescens P6) in field trials. Evaluation resulted in the selection of three effective biocontrol agents (Pseudomonas fluorescens P6, P10, and Streptomyces diastatochromogenes S9) antagonistic to the Verticillium wilt pathogen.

  3. Effect of Bawang Dayak (Eleutherine palmifolia (L) Merr) crude extract towards bacteria inhibition zone and carp (Cyprinus carpio) hematology

    Maftuch

    2017-05-01

    Negative impacts of antibiotics and chemical substance usage in aquaculture demand the researchers discover more efficient alternative yet environmentally friendly to overcome fish diseases. One alternative is by using Bawang Dayak (Eleutherine palmifolia (L.) Merr). This research aimed to reveal the effect of Bawang Dayak crude extract towards the inhibition zone of A. hydrophilia, V. harveyi, and P. fluorescens bacteria. Furthermore, it was also conducted to investigate the carp (C. carpio) hematology which was infected with A. hydrophila bacteria, and find the most appropriate dose of Bawang Dayak crude extract to inhibit the bacteria. This experimental research was performed by using Completely Randomized Design with 4 treatments and 3 replications. The best result of the zone of inhibition test in A. hydrophila bacteria was at the dose of 70 ppm while V. harveyi and P. Fluorescens bacteria were at the dose of 85 ppm. Then, fish hematology was found best at the dose of 80 ppm. Bawang Dayak crude extract was significant towards the inhibition zone of A. hydrophila, V. harveyi and P. Fluorescens bacteria, and carp hematology which was infected with A. hydrophila bacteria.

  4. Effects of Tween 80 on growth and biofilm formation in laboratory media

    Christina Krogsård Nielsen

    2016-11-01

    Full Text Available Tween 80 is a widely used nonionic emulsifier that is added to cosmetics, pharmaceuticals and foods. Because of its widespread use we need to understand how it affects bacteria on our skin, in our gut, and in food products. The aim of this study is to investigate how Tween 80 affects the growth and antimicrobial susceptibility of Staphylococcus aureus, Listeria monocytogenes and Pseudomonas fluorescens, which are common causes of spoilage and foodborne illnesses. Addition of 0.1% Tween 80 to laboratory growth media increased the growth rate of planktonic S. aureus batch cultures, and it also increased the total biomass when S. aureus was grown as biofilms. In contrast, Tween 80 had no effect on batch cultures of L. monocytogenes, it slowed the growth rate of P. fluorescens, and it led to formation of less biofilm by both L. monocytogenes and P. fluorescens. Furthermore, Tween 80 lowered the antibacterial efficacy of two hydrophobic antimicrobials: rifampicin and the essential oil isoeugenol. Our findings underline the importance of documenting indirect effects of emulsifiers when studying the efficacy of hydrophobic antimicrobials that are dispersed in solution by emulsification, or when antimicrobials are applied in food matrixes that include emulsifiers. Furthermore, the species-specific effects on microbial growth suggests that Tween 80 in cosmetics and food products could affect the composition of skin and gut microbiota, and the effect of emulsifiers on the human microbiome should therefore be explored to uncover potential health effects.

  5. Biological Control to Protect Watermelon Blossoms and Seed from Infection by Acidovorax avenae subsp. citrulli.

    Fessehaie, A; Walcott, R R

    2005-04-01

    ABSTRACT The efficacy of biological control seed treatments with Pseudomonas fluorescens (A506), Acidovorax avenae subsp. avenae (AAA 99-2), and an unidentified gram-positive bacterium recovered from watermelon seed (WS-1) was evaluated for the management of bacterial fruit blotch (BFB) of watermelon. In growth chamber and greenhouse experiments, seed treated with AAA 99-2 displayed superior disease suppression, reducing BFB transmission by 96.5%. AAA 99-2, P. fluorescens A506, and Kocide also suppressed the epiphytic growth of A. avenae subsp. citrulli when applied to attached watermelon blossoms 5 h prior to inoculation. Watermelon blossom protection reduced seed infestation by A. avenae subsp. citrulli. From blossoms treated with 0.1 M phosphate buffered saline (PBS), 63% of the resulting seed lots were infested with A. avenae subsp. citrulli. In contrast, for blossoms protected with WS-1, Kocide, P. fluorescens A506, and AAA 99-2, the proportion of infested seed lots were 48.3, 21.1, 24.1, and 13.8%, respectively. The effect of blossom treatments on seed lot infestation was statistically significant (P = 0.001) but WS-1 was not significantly different from PBS. These findings suggest that blossom protection with biological control agents could be a feasible option for managing BFB.

  6. Toxicity of 2,4-diacetylphloroglucinol (DAPG) to plant-parasitic and bacterial-feeding nematodes.

    Meyer, Susan L F; Halbrendt, John M; Carta, Lynn K; Skantar, Andrea M; Liu, Ting; Abdelnabby, Hazem M E; Vinyard, Bryan T

    2009-12-01

    The antibiotic 2,4-diacetylphloroglucinol (DAPG) is produced by some isolates of the beneficial bacterium Pseudomonas fluorescens. DAPG is toxic to many organisms, and crop yield increases have been reported after application of DAPG-producing P. fluorescens. This study was conducted to determine whether DAPG is toxic to selected nematodes. The plant-parasitic nematodes Heterodera glycines, Meloidogyne incognita, Pratylenchus scribneri and Xiphinema americanum, and the bacterial-feeding nematodes Caenorhabditis elegans, Pristionchus pacificus, and Rhabditis rainai, were immersed in concentrations ranging from 0 to 100 μg/ml DAPG. Egg hatch and viability of juveniles and adults were determined. DAPG was toxic to X. americanum adults, with an LD₅₀ of 8.3 μg/ml DAPG. DAPG decreased M. incognita egg hatch, but stimulated C. elegans hatch during the first hours of incubation. Viability of M. incognita J2 and of C. elegans J1 and adults was not affected. There were no observed effects on the other nematodes. The study indicated that DAPG is not toxic to all nematodes, and did not affect the tested species of beneficial bacterial-feeding nematodes. Augmentation of DAPG-producing P. fluorescens populations for nematode biocontrol could be targeted to specific nematode species known to be affected by this compound and by other antibiotics produced by the bacteria, or these bacteria could be used for other possible effects, such as induced plant resistance.

  7. Maple sap predominant microbial contaminants are correlated with the physicochemical and sensorial properties of maple syrup.

    Filteau, Marie; Lagacé, Luc; Lapointe, Gisèle; Roy, Denis

    2012-03-01

    Maple sap processing and microbial contamination are significant aspects that affect maple syrup quality. In this study, two sample sets from 2005 and 2008 were used to assess the maple syrup quality variation and its relationship to microbial populations, with respect to processing, production site and harvesting period. The abundance of maple sap predominant bacteria (Pseudomonas fluorescens group and two subgroups, Rahnella spp., Janthinobacterium spp., Leuconostoc mesenteroides) and yeast (Mrakia spp., Mrakiella spp.,Guehomyces pullulans) was assessed by quantitative PCR. Maple syrup properties were analyzed by physicochemical and sensorial methods. Results indicate that P. fluorescens, Mrakia spp., Mrakiella spp. G. pullulans and Rahnella spp. are stable contaminants of maple sap, as they were found for every production site throughout the flow period. Multiple factor analysis reports a link between the relative abundance of P. fluorescens group and Mrakia spp. in maple sap with maple and vanilla odor as well as flavor of maple syrup. This evidence supports the contribution of these microorganisms or a consortium of predominant microbial contaminants to the characteristic properties of maple syrup. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. A combination of biocontrol agents improves the management of dry root rot (Macrophomina phaseolina in greengram

    R. Thilagavathi

    2007-08-01

    Full Text Available The biocontrol agents Trichoderma viride (strains Tv1 and Tv13, Pseudomonas fluorescens (Pf1 and Py15 and Bacillus subtilis (Bs16 were tested individually and in combination for their effectiveness against root rot of greengram caused by Macrophomina phaseolina. As regards the compatibility of the biocontrol agents with each other, T. viride strains were not compatible with B. subtilis (Bs16, but P. fluorescens strains were compatible with B. subtilis and T. viride. Of the biocontrol agents tested in vitro against M. phaseolina, combinations of P. fluorescens+T. viride (Pf1+Tv1, Pf1+Tv13 and Py15+Tv1 inhibited mycelial growth of the pathogen and they also promoted the growth of the greengram seedlings. A combination of Pf1+Tv1 was most effective in reducing root rot incidence under glass-house and field conditions as compared with other single or combined treatments or the untreated control. The activity of the defense-related enzymes peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase was significantly greater in greengram plants treated with a talc based formulation containing Pf1+Tv1 followed by Pf1+Tv13 and Py15+Tv1, than in plants receiving other treatments or the untreated control. Moreover, a combination of Pf1+Tv1 followed by Pf1+Tv13 and Py15+Tv1 significantly increased yield under glass house and field conditions.

  9. Anti-pseudomona and Anti-bacilli Activity of Some Medicinal Plants of Iran

    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.

  10. Heterogeneity of heat-resistant proteases from milk Pseudomonas species.

    Marchand, Sophie; Vandriesche, Gonzalez; Coorevits, An; Coudijzer, Katleen; De Jonghe, Valerie; Dewettinck, Koen; De Vos, Paul; Devreese, Bart; Heyndrickx, Marc; De Block, Jan

    2009-07-31

    Pseudomonas fragi, Pseudomonas lundensis and members of the Pseudomonas fluorescens group may spoil Ultra High Temperature (UHT) treated milk and dairy products, due to the production of heat-stable proteases in the cold chain of raw milk. Since the aprX gene codes for a heat-resistant protease in P. fluorescens, the presence of this gene has also been investigated in other members of the genus. For this purpose an aprX-screening PCR test has been developed. Twenty-nine representatives of important milk Pseudomonas species and thirty-five reference strains were screened. In 42 out of 55 investigated Pseudomonas strains, the aprX gene was detected, which proves the potential of the aprX-PCR test as a screening tool for potentially proteolytic Pseudomonas strains in milk samples. An extensive study of the obtained aprX-sequences on the DNA and the amino acid level, however, revealed a large heterogeneity within the investigated milk isolates. Although this heterogeneity sets limitations to a general detection method for all proteolytic Pseudomonas strains in milk, it offers a great potential for the development of a multiplex PCR screening test targeting individual aprX-genes. Furthermore, our data illustrated the potential use of the aprX gene as a taxonomic marker, which may help in resolving the current taxonomic deadlock in the P. fluorescens group.

  11. Controlled field release of a bioluminescent genetically engineered microorganism for bioremediation process monitoring and control

    Ripp, S.; Nivens, D.E.; Ahn, Y.; Werner, C.; Jarrell, J. IV; Easter, J.P.; Cox, C.D.; Burlage, R.S.; Sayler, G.S.

    2000-03-01

    Pseudomonas fluorescens HK44 represents the first genetically engineered microorganism approved for field testing in the United States for bioremediation purposes. Strain HK44 harbors an introduced lux gene fused within a naphthalene degradative pathway, thereby allowing this recombinant microbe to bioluminescent as it degrades specific polyaromatic hydrocarbons such as naphthalene. The bioremediation process can therefore be monitored by the detection of light. P. fluorescens HK44 was inoculated into the vadose zone of intermediate-scale, semicontained soil lysimeters contaminated with naphthalene, anthracene, and phenanthrene, and the population dynamics were followed over an approximate 2-year period in order to assess the long-term efficacy of using strain HK44 for monitoring and controlling bioremediation processes. Results showed that P. fluorescens HK44 was capable of surviving initial inoculation into both hydrocarbon contaminated and uncontaminated soils and was recoverable from these soils 660 days post inoculation. It was also demonstrated that strain HK44 was capable of generating bioluminescence in response to soil hydrocarbon bioavailability. Bioluminescence approaching 166,000 counts/s was detected in fiber optic-based biosensor devices responding to volatile polyaromatic hydrocarbons, while a portable photomultiplier module detected bioluminescence at an average of 4300 counts/s directly from soil-borne HK44 cells within localized treatment areas. The utilization of lux-based bioreporter microorganisms therefore promises to be a viable option for in situ determination of environmental contaminant bioavailability and biodegradation process monitoring and control.

  12. Far from superficial: microbial diversity associated with the skin and mucus of fish

    Cipriano, Rocco C.; Dove, Alistair; Cipriano, R.C.; Bruckner, A.W.; Shchelkunov, I.S.

    2011-01-01

    During horizontal or water-borne infection involving an obligate pathogen (e.g. – Aeromonas salmonicida, cause of furunculosis), the pathogen interacted with and influenced the microbial diversity of the dermal mucus of fish. Prior to infection, the prevalent bacterial flora cultured from juvenile Atlantic salmon (Salmo salar) included Pseudomonas fluorescens, Comomonas terrigenia, Acinetobacter sp., Moraxella sp., Pseudomonas dimunita, Alcaligenes denitrificans, Pseudomonas pseudoalcaligenes, and Pseudomonas alcaligenes, Serratia liquefaciens, Aeromonas hydrophila, other motile Aeromonas spp., and Corynebacterium aquaticum. After A. salmonicida was initially detected in this population as an external mucus infection, Acinetobacter sp., Moraxella sp., C. terrigenia, P. fluorescens, and P. dimunita, Staphylococcus sp., and A. hydrophila, were also present in appreciable numbers. Within several weeks, however, the A. salmonicida infection amplified and composed 78% of the total flora in the mucus. Only P. dimunita (4%). P. fluorescens (2%), and C. terrigenia (1%) were cultured at that time and more than a third of these fish showed evidence of a systemic A. salmonicida infection within their kidneys. Eight weeks after oral oxytetracycline treatments, A. salmonicida was no longer isolated from the mucus or kidneys of any fish and glucose inert or other oxidative microbes (e.g., P. fluorescens, C. terrigenia, Acinetobacter sp., Moraxella sp.) were beginning to repopulate the external surface of the salmon in increasing frequency. Still present and composing fairly large percentages of the total flora were A. hydrophila, as well as Enterobacter sp., and P. putrefaciens. A normal microbial diversity was re-established as the fish recovered. In another investigation, reduced biological diversity was noted in the dermal mucus among smallmouth bass that were sampled from the Jackson River (Covington, VA). In these fish, A. hydrophila and P. putrefaciens were the two

  13. Effect of microbial cell-free meat extract on the growth of spoilage bacteria.

    Nychas, G-J E; Dourou, D; Skandamis, P; Koutsoumanis, K; Baranyi, J; Sofos, J

    2009-12-01

    This study examined the effect of microbial cell-free meat extract (CFME) derived from spoiled meat, in which quorum sensing (QS) compounds were present, on the growth kinetics (lag phase, and growth rate) of two spoilage bacteria, Pseudomonas fluorescens and Serratia marcescens. Aliquots of CFME from spoiled meat were transferred to Brain Heart Infusion broth inoculated with 10(3) CFU ml(-1) of 18 h cultures of Ps. fluorescens or Ser. marcescens, both fresh meat isolates; CFME derived from unspoiled fresh meat ('clean' meat) served as a control. Changes in impedance measurements were monitored for 48 h, and the detection time (Tdet) was recorded. It was found that in the absence of CFME containing QS compounds the Tdet was shorter (P meat. The rate of growth of Ps. fluorescens, recorded as the maximum slope rate of conductance changes (MSrCC), after Tdet, was higher (P meat. Similar results in MSrCC of impedance changes were obtained for Ser. marcescens. The study indicated that the growth rate (expressed in MSrCC units) of meat spoilage bacteria in vitro was enhanced in samples supplemented with CFME containing QS compounds compared to control samples (i.e., without CFME or with CFME from 'clean' meat). This behaviour may explain the dominant role of these two bacteria in the spoilage of meat. These results illustrate the potential effect of signalling compounds released during storage of meat on the behaviour of meat spoilage bacteria. Understanding such interactions may assist in the control of fresh meat quality and the extension of its shelf life.

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

    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; Ussery, David W

    2016-01-01

    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. Copyright © 2015 Jun et al.

  15. Bacterial Respiration and Growth Rates Affect the Feeding Preferences, Brood Size and Lifespan of Caenorhabditis elegans

    Yu, Li; Yan, Xiaomei; Ye, Chenglong; Zhao, Haiyan; Chen, Xiaoyun; Hu, Feng; Li, Huixin

    2015-01-01

    Bacteria serve as live food and nutrients for bacterial-feeding nematodes (BFNs) in soils, and influence nematodes behavior and physiology through their metabolism. Five bacterial taxa (Bacillus amyloliquefaciens JX1, Variovorax sp. JX14, Bacillus megaterium JX15, Pseudomonas fluorescens Y1 and Escherichia coli OP50) and the typical BFN Caenorhabditis elegans were selected to study the effects of bacterial respiration and growth rates on the feeding preferences, brood size and lifespan of nematodes. P. fluorescens Y1 and E. coli OP50 were found to be more active, with high respiration and rapid growth, whereas B. amyloliquefaciens JX1 and B. megaterium JX15 were inactive. The nematode C. elegans preferred active P. fluorescens Y1 and E. coli OP50 obviously. Furthermore, worms that fed on these two active bacteria produced more offspring but had shorter lifespan, while inactive and less preferred bacteria had increased nematodes lifespan and decreased the brood size. Based on these results, we propose that the bacterial activity may influence the behavior and life traits of C. elegans in the following ways: (1) active bacteria reproduce rapidly and emit high levels of CO2 attracting C. elegans; (2) these active bacteria use more resources in the nematodes’ gut to sustain their survival and reproduction, thereby reducing the worm's lifespan; (3) inactive bacteria may provide less food for worms than active bacteria, thus increasing nematodes lifespan but decreasing their fertility. Nematodes generally require a balance between their preferred foods and beneficial foods, only preferred food may not be beneficial for nematodes. PMID:26222828

  16. Comparative genomics of plant-associated Pseudomonas spp.: insights into diversity and inheritance of traits involved in multitrophic interactions.

    Joyce E Loper

    2012-07-01

    Full Text Available We provide here a comparative genome analysis of ten strains within the Pseudomonas fluorescens group including seven new genomic sequences. These strains exhibit a diverse spectrum of traits involved in biological control and other multitrophic interactions with plants, microbes, and insects. Multilocus sequence analysis placed the strains in three sub-clades, which was reinforced by high levels of synteny, size of core genomes, and relatedness of orthologous genes between strains within a sub-clade. The heterogeneity of the P. fluorescens group was reflected in the large size of its pan-genome, which makes up approximately 54% of the pan-genome of the genus as a whole, and a core genome representing only 45-52% of the genome of any individual strain. We discovered genes for traits that were not known previously in the strains, including genes for the biosynthesis of the siderophores achromobactin and pseudomonine and the antibiotic 2-hexyl-5-propyl-alkylresorcinol; novel bacteriocins; type II, III, and VI secretion systems; and insect toxins. Certain gene clusters, such as those for two type III secretion systems, are present only in specific sub-clades, suggesting vertical inheritance. Almost all of the genes associated with multitrophic interactions map to genomic regions present in only a subset of the strains or unique to a specific strain. To explore the evolutionary origin of these genes, we mapped their distributions relative to the locations of mobile genetic elements and repetitive extragenic palindromic (REP elements in each genome. The mobile genetic elements and many strain-specific genes fall into regions devoid of REP elements (i.e., REP deserts and regions displaying atypical tri-nucleotide composition, possibly indicating relatively recent acquisition of these loci. Collectively, the results of this study highlight the enormous heterogeneity of the P. fluorescens group and the importance of the variable genome in tailoring

  17. Selection of potent bacterial strain for over-production of PHB by using low cost carbon source for eco-friendly bioplastics

    Rahat Abdul Rehman

    2015-11-01

    Full Text Available Background: The microbial PHB production is a promising tool for the plastic industry for the synthesis of environmental friendly, biodegradable plastic in contrast to the conventional petro-chemical based non-degradable plastics. The selection of potent bacterial strains, inexpensive carbon source, efficient fermentation and recovery processes are important aspects that were taken into account during this study. Methods: Different bacterial strains i.e. Bacillus Spp, P. putida and P. fluorescens were screened for maximum PHB production. Under media optimization, various carbon and nitrogen sources (alone or in combination were used to achieve the maximum PHB production. Finally the degradation tests of the PHB sheet were also performed to test its biodegradability potential. Results: Shake flask studies have shown the PHB concentrations upto 7.02, 4.50 and 34.4 mg/g of dry cell mass of P. putida, P. fluorescens and Bacillus Spp. respectively. Almost same results were observed at laboratory scale production of PHB in 10 L fermenter i.e. 6.28, 6.23 and 39.5 mg/g of dry cell mass by P. putida, P. fluorescens and Bacillus Spp. respectively. On the basis of these observations, Bacillus Spp. was chosen for laboratory scale PHB production. Corn steep liquor (4% was chosen as the best medium to achieve the highest PHB contents. Isolated PHB has shown biodegradation in soil up to 86.7% at 37oC. Conclusion: The Bacillus Spp. Proved to be the best strain for PHB production on only 4% CSL which is cheapest and easily available.

  18. Antimicrobial peptides and pro-inflammatory cytokines are differentially regulated across epidermal layers following bacterial stimuli.

    Percoco, Giuseppe; Merle, Chloé; Jaouen, Thomas; Ramdani, Yasmina; Bénard, Magalie; Hillion, Mélanie; Mijouin, Lily; Lati, Elian; Feuilloley, Marc; Lefeuvre, Luc; Driouich, Azeddine; Follet-Gueye, Marie-Laure

    2013-12-01

    The skin is a natural barrier between the body and the environment and is colonised by a large number of microorganisms. Here, we report a complete analysis of the response of human skin explants to microbial stimuli. Using this ex vivo model, we analysed at both the gene and protein level the response of epidermal cells to Staphylococcus epidermidis (S. epidermidis) and Pseudomonas fluorescens (P. fluorescens), which are present in the cutaneous microbiota. We showed that both bacterial species affect the structure of skin explants without penetrating the living epidermis. We showed by real-time quantitative polymerase chain reaction (qPCR) that S. epidermidis and P. fluorescens increased the levels of transcripts that encode antimicrobial peptides (AMPs), including human β defensin (hBD)2 and hBD3, and the pro-inflammatory cytokines interleukin (IL)-1α and (IL)-1-β, as well as IL-6. In addition, we analysed the effects of bacterial stimuli on the expression profiles of genes related to innate immunity and the inflammatory response across the epidermal layers, using laser capture microdissection (LCM) coupled to qPCR. We showed that AMP transcripts were principally upregulated in suprabasal keratinocytes. Conversely, the expression of pro-inflammatory cytokines was upregulated in the lower epidermis. These findings were confirmed by protein localisation using specific antibodies coupled to optical or electron microscopy. This work underscores the potential value of further studies that use LCM on human skin explants model to study the roles and effects of the epidermal microbiota on human skin physiology. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-01-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  20. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-07-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  1. Burkholderia type VI secretion systems have distinct roles in eukaryotic and bacterial cell interactions

    Schwarz, Sandra; West, T Eoin; Boyer, Frédéric

    2010-01-01

    . From a group of 31 diverse bacteria, we identified several organisms that competed less effectively against wild-type B. thai than a strain lacking T6SS-1 function. Inactivation of T6SS-1 renders B. thai greatly more susceptible to cell contact-induced stasis by Pseudomonas putida, Pseudomonas...... fluorescens and Serratia proteamaculans-leaving it 100- to 1000-fold less fit than the wild-type in competition experiments with these organisms. Flow cell biofilm assays showed that T6S-dependent interbacterial interactions are likely relevant in the environment. B. thai cells lacking T6SS-1 were rapidly...

  2. Sensitivity of ice-nucleating bacteria to ultraviolet irradiation

    Obata, Hitoshi; Tanahashi, Shinji; Kawahara, Hidehisa (Kansai Univ., Suita, Osaka (Japan). Faculty of Engineering)

    1992-01-01

    The effect of ultraviolet (UV) irradiation on the ice-nucleating activity of the ice-nucleating bacteria was examined. Bacterial suspension was irradiated with UV (254 nm, 6Wx2) for 5 min at a distance of 20 cm from UV source. Although no viable cells were detected, the ice-nucreating activity of the cells was not affected. Furthermore, after UV irradiation for 3 hr, the ice-nucleating activity of Pseudomonas fluorescens and P. syringae was only slightly decreased, although that of P. viridiflava and Erwinia herbicola was significantly lowered. We succeeded in killing the ice-nucleating bacteria, while retaining their ice-nucleating activity with UV irradiation. (author).

  3. Study of the biological impact of Pseudomonas spp.fluoresents on hemolyphatic metabolites and histology of the digestive tract of larvae 15 migratory locust Locusta migratoria

    Oulebsir- Mohan, H.; Doumandji-Mitiche, B.

    2012-01-01

    This study allows to test the effect of entomopathogenic bacteria of Pseudomonas fluorescens bv III and Pseudomonas fluorescence bv V on the haemolymph of Locusta migratoria metabolites, namely proteins and carbohydrates as well as on the histology of the digestive system of fifth stage larvae of migratory locust Locusta migratoria. The results show an important decrease of haemolymph protein concentration compared to controls with an increase in carbohydrate concentration. Examination of histological sections of various parts of the digestive tract showed some changes in treated. (author)

  4. Efecto de la aplicación de pseudomonas fluorescentes en las propiedades físico-químicas y biológicas de suelo : balance nutricional y estimulación de hormonas

    Martínez Moreno, Joaquín Ignacio

    2015-01-01

    El objetivo de esta propuesta es el estudio del efecto de la aplicación de un fitofortificante (bacterias, Pseudomonas fluorescens) en la evolución tanto de las propiedades físico-químicas y microbiológicas/bioquímicas del suelo como en la estimulación de hormonas del crecimiento vegetal, así como estudiar su efecto en el balance nutricional, la calidad y la producción de los cultivos de maíz y melón. Escuela Técnica superior de Ingeniería Agronómica Universidad Politécnica ...

  5. Process for the aerobic conversion of poultry manure into high-protein feedstuff

    Shuler, M.L.; Roberts, E.D.; Mitchell, D.W.; Kargi, F.; Austic, R.E.; Henry, A.; Vashon, R.; Seeley, H.W. Jr.

    1979-01-01

    A two-stage aerobic continuous process is suggested for the conversion of poultry waste into a single-cell protein (SCP) product. The technical feasibility of the process is examined in this paper. Using bench-scale apparatus the approximate growth kinetics have been discovered. Possible modes of product recovery have been examined. The product consists primarily of a strain of Pseudomonas fluorescens which has a lysine-rich (approx. 9.3%) amino acid profile that could make this product an attractive feed ingredient for poultry diets.

  6. Detection of Methylobacterium radiotolerans IMBG290 in potato plants by in situ hybridization

    Pirttila A. M.

    2009-04-01

    Full Text Available A new bacterial strain of pink-pigmented facultative methylotroph (M. radiotolerans IMBG290 which was previously isolated from in vitro grown potato plantlets after their inoculation with Pseudomonas fluorescens IMBG163 was detected in tissues by in situ hybridization method (ISH/FISH. The presence of Methylobacterium rRNA was observed in leaves and stems of potato plantlets, whereas no signal was detected in potato roots. The signal was less abundant in the untreated plants than in the plantlets infected with M. radiotolerans IMBG290.

  7. IMPACT OF THE DURATION OF BACTERIAL EXPOSURE ON ZEBRA MUSSEL MORTALITY

    Molloy, Daniel P.

    2002-01-01

    These tests indicated that: (1) duration of exposure to bacterial strain CL0145A of Pseudomonas fluorescens is a key variable in obtaining zebra mussel mortality; (2) that given a choice of exposure periods up to 96 hr, the longer the exposure period, the higher the mean mortality that will be achieved; (3) that the first few hours that the mussels are exposed to the bacteria are the most important in achieving kill; (4) that the mortality achieved by exposure periods ≥72 hr may be somewhat amplified by the degraded water quality conditions which can develop in recirculating water systems over such extended time periods

  8. IMPACT OF THE DURATION OF BACTERIAL EXPOSURE ON ZEBRA MUSSEL MORTALITY

    Daniel P. Molloy

    2002-01-21

    These tests indicated that: (1) duration of exposure to bacterial strain CL0145A of Pseudomonas fluorescens is a key variable in obtaining zebra mussel mortality; (2) that given a choice of exposure periods up to 96 hr, the longer the exposure period, the higher the mean mortality that will be achieved; (3) that the first few hours that the mussels are exposed to the bacteria are the most important in achieving kill; (4) that the mortality achieved by exposure periods {>=}72 hr may be somewhat amplified by the degraded water quality conditions which can develop in recirculating water systems over such extended time periods.

  9. Environmentally Safe Control of Zebra Mussel Fouling

    Daniel Molloy

    2008-02-29

    The two primary objectives of this USDOE-NETL contract were successfully achieved during the project: (1) to accelerate research on the development of the bacterium Pseudomonas fluorescens strain CL145A (Pf-CL145A) as a biocontrol agent for zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis)--two invasive freshwater bivalve species that are infesting water pipes in power plants; and (2) to identify a private-sector company that would move forward to commercialize Pf-CL145A as a substitute for the current polluting use of biocide chemicals for control of these dreissenid mussels in power plant pipes.

  10. IMPACT OF WATER TEMPERATURE ON ZEBRA MUSSEL MORTALITY

    Daniel P. Molloy

    2002-08-07

    These tests conducted this past quarter have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels at water temperatures ranging from 7 to 23 C. Percent kill will likely be somewhat lower at very low temperatures, e.g., 7 C, but even at such low temperatures high mussel kill can still be achieved (>70% kill). This is significant because the development of a zebra mussel control method that is efficacious in such a wide range of temperatures broadens its usefulness as a potential commercial product.

  11. Biotransformations of organic energetic materials

    Matousek, J.

    2001-01-01

    This paper reviews data on the acute eco-toxicity and delayed effects (mutagenicity) of the model substance (TNT) and of a wide spectrum of its biodegradation products in the wastewaters. It also suggests main metabolic pathways of biotransformation, involving biological reduction. Some possibilities of remediation of contaminated soils utilising microbial catabolic pathways leading to the hydroxy derivatives and up to the cleavage of the aromatic ring system in the presence of the soil bacteria Pseudomonas fluorescens are shown, as well as the practical utilisation of fungi Phanerochaete chrysosporium under aerobic conditions

  12. Effet de la bactérisation des graines sur la croissance des plants de Cedrus atlantica Manetti

    Satrani B.

    2009-01-01

    Full Text Available Bacterization effect of seeds on the growth of Cedrus atlantica Manetti plants. The beneficial effect of five rhizobacterial strains on the growth of Cedrus atlantica plants was evaluated at forest nursery before out-planting. The obtained results showed a significant effect of bacterial strains on cedar seedlings growth and only Pseudomonas fluorescens A6RI and TGI252 significantly increased stem length, neck diameter, root dry weight and number of root tips. It will allow us to adapt this technology for the production of quality plants.

  13. Comparative genomic and functional analyses: unearthing the diversity and specificity of nematicidal factors in Pseudomonas putida strain 1A00316

    Guo, Jing; Jing, Xueping; Peng, Wen-Lei; Nie, Qiyu; Zhai, Yile; Shao, Zongze; Zheng, Longyu; Cai, Minmin; Li, Guangyu; Zuo, Huaiyu; Zhang, Zhitao; Wang, Rui-Ru; Huang, Dian; Cheng, Wanli; Yu, Ziniu; Chen, Ling-Ling; Zhang, Jibin

    2016-01-01

    We isolated Pseudomonas putida (P. putida) strain 1A00316 from Antarctica. This bacterium has a high efficiency against Meloidogyne incognita (M. incognita) in vitro and under greenhouse conditions. The complete genome of P. putida 1A00316 was sequenced using PacBio single molecule real-time (SMRT) technology. A comparative genomic analysis of 16 Pseudomonas strains revealed that although P. putida 1A00316 belonged to P. putida, it was phenotypically more similar to nematicidal Pseudomonas fluorescens (P. fluorescens) strains. We characterized the diversity and specificity of nematicidal factors in P. putida 1A00316 with comparative genomics and functional analysis, and found that P. putida 1A00316 has diverse nematicidal factors including protein alkaline metalloproteinase AprA and two secondary metabolites, hydrogen cyanide and cyclo-(l-isoleucyl-l-proline). We show for the first time that cyclo-(l-isoleucyl-l-proline) exhibit nematicidal activity in P. putida. Interestingly, our study had not detected common nematicidal factors such as 2,4-diacetylphloroglucinol (2,4-DAPG) and pyrrolnitrin in P. putida 1A00316. The results of the present study reveal the diversity and specificity of nematicidal factors in P. putida strain 1A00316. PMID:27384076

  14. Quantification of biofilm structures by the novel computer program COMSTAT.

    Heydorn, A; Nielsen, A T; Hentzer, M; Sternberg, C; Givskov, M; Ersbøll, B K; Molin, S

    2000-10-01

    The structural organization of four microbial communities was analysed by a novel computer program, COMSTAT, which comprises ten features for quantifying three-dimensional biofilm image stacks. Monospecies biofilms of each of the four bacteria, Pseudomonas: putida, P. aureofaciens, P. fluorescens and P. aeruginosa, tagged with the green fluorescent protein (GFP) were grown in flow chambers with a defined minimal medium as substrate. Analysis by the COMSTAT program of four variables describing biofilm structure - mean thickness, roughness, substratum coverage and surface to volume ratio - showed that the four Pseudomonas: strains represent different modes of biofilm growth. P. putida had a unique developmental pattern starting with single cells on the substratum growing into micro-colonies, which were eventually succeeded by long filaments and elongated cell clusters. P. aeruginosa colonized the entire substratum, and formed flat, uniform biofilms. P. aureofaciens resembled P. aeruginosa, but had a stronger tendency to form micro-colonies. Finally, the biofilm structures of P. fluorescens had a phenotype intermediate between those of P. putida and P. aureofaciens. Analysis of biofilms of P. aureofaciens growing on 0.03 mM, 0.1 mM or 0.5 mM citrate minimal media showed that mean biofilm thickness increased with increasing citrate concentration. Moreover, biofilm roughness increased with lower citrate concentrations, whereas surface to volume ratio increased with higher citrate concentrations.

  15. Selective inhibition of Erwinia amylovora by the herbicidally active germination-arrest factor (GAF) produced by Pseudomonas bacteria.

    Halgren, A; Azevedo, M; Mills, D; Armstrong, D; Thimmaiah, M; McPhail, K; Banowetz, G

    2011-10-01

     The germination-arrest factor (GAF) produced by Pseudomonas fluorescens WH6, and identified as 4-formylaminooxyvinylglycine, specifically inhibits the germination of a wide range of grassy weeds. This study was undertaken to determine whether GAF has antimicrobial activity in addition to its inhibitory effects on grass seed germination. Culture filtrate from Ps. fluorescens WH6 had little or no effect on 17 species of bacteria grown in Petri dish lawns, but the in vitro growth of Erwinia amylovora, the causal agent of the disease of orchard crops known as fire blight, was strongly inhibited by the filtrate. The anti-Erwinia activity of WH6 culture filtrate was shown to be due to its GAF content, and a commercially available oxyvinylglycine, 4-aminoethoxyvinylglycine (AVG), exhibited anti-Erwinia activity similar to that of GAF. The effects of GAF on Erwinia were reversed by particular amino acids. The biological properties of GAF include a rather specific antimicrobial activity against Erw. amylovora. This may be a general property of oxyvinylglycines as AVG exhibited similar activity. The ability of particular amino acids to reverse GAF inhibition is consistent with a potential effect of this compound on the activity of aminotransferases. The results presented here demonstrate a novel antimicrobial activity of oxyvinylglycines and suggest that GAF and/or GAF-producing bacteria may have potential for the control of fire blight. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology. No claim to US Government works.

  16. Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

    Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

    2016-01-01

    The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

  17. Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

    Nomura, Toshiyuki, E-mail: nomura@chemeng.osakafu-u.ac.jp; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro [Osaka Prefecture University, Department of Chemical Engineering (Japan)

    2016-06-15

    The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells (Escherichia coli and Lactococcuslactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

  18. Evaluation of indigenous bacterial strains for biocontrol of the frogeye leaf spot of soya bean caused by Cercospora sojina.

    Simonetti, E; Carmona, M A; Scandiani, M M; García, A F; Luque, A G; Correa, O S; Balestrasse, K B

    2012-08-01

    Assessment of biological control of Cercospora sojina, causal agent of frogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains, BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens). From cultures of each bacterial strain, cell suspensions and cell-free supernatants were obtained and assayed to determine their antifungal activity against C. sojina. Both mycelial growth and spore germination in vitro were more strongly inhibited by bacterial cell suspensions than by cell-free supernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungal growth to a similar degree (I ≈ 52-53%), while cells from P. fluorescens BNM297 caused a lesser reduction (I ≈ 32-34%) in the fungus colony diameter. The foliar application of the two Bacillus strains on soya bean seedlings, under greenhouse conditions, significantly reduced the disease severity with respect to control soya bean seedlings and those sprayed with BNM297. This last bacterial strain was not effective in controlling FLS in vivo. Our data demonstrate that the application of antagonistic bacteria may be a promising and environmentally friendly alternative to control the FLS of soya bean.   To our knowledge, this is the first report of biological control of C. sojina by using native Bacillus strains. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

  19. Identification of the potential of microbial combinations obtained from spent mushroom cultivation substrates for use in textile effluent decolorization.

    Singh, Rajender; Ahlawat, O P; Rajor, Anita

    2012-12-01

    The study presents variation in microbial population of Agaricus bisporus, Pleurotus sajor-caju and Volvariella volvacea spent substrates (SMS) along with ligninolytic enzymes activity and textile effluent decolorization potential of microorganisms isolated from these. The effect of temperature, pH, carbon sources and immobilizing agents on effluent decolorization using different combinations of these microorganisms has also been studied. SMS of P. sajor-caju harbored highest population and diversity of bacteria and fungi compared to other SMSs. Schizophyllum commune and Pezizomycotina sp. from P. sajor-caju SMS, exhibited highest activities of laccase (11.8 and 8.32U mL(-1)) and lignin peroxidase (339 and 318 UL(-1)), while Pseudomonas fluorescens of Manganese peroxidase. Highest decolorization was in presence of glucose and sucrose at 30°C, and microbial consortium comprised of the immobilized forms of S. commune and Pezizomycotina sp. on wheat straw and broth cultures of P. fluorescens, Bacillus licheniformis and Bacillus pumilus. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Silica-Gentamicin Nanohybrids: Synthesis and Antimicrobial Action

    Dina Ahmed Mosselhy

    2016-03-01

    Full Text Available Orthopedic applications commonly require the administration of systemic antibiotics. Gentamicin is one of the most commonly used aminoglycosides in the treatment and prophylaxis of infections associated with orthopedic applications, but gentamicin has a short half-life. However, silica nanoparticles (SiO2 NPs can be used as elegant carriers for antibiotics to prolong their release. Our goal is the preparation and characterization of SiO2-gentamicin nanohybrids for their potential antimicrobial administration in orthopedic applications. In vitro gentamicin release profile from the nanohybrids (gentamicin-conjugated SiO2 NPs prepared by the base-catalyzed precipitation exhibited fast release (21.4% during the first 24 h and further extension with 43.9% release during the five-day experiment. Antimicrobial studies of the SiO2-gentamicin nanohybrids versus native SiO2 NPs and free gentamicin were performed against Bacillus subtilis (B. subtilis, Pseudomonas fluorescens (P. fluorescens and Escherichia coli (E. coli. SiO2-gentamicin nanohybrids were most effective against B. subtilis. SiO2 NPs play no antimicrobial role. Parallel antimicrobial studies for the filter-sterilized gentamicin were performed to assess the effect of ultraviolet (UV-irradiation on gentamicin. In summary, the initial fast gentamicin release fits the need for high concentration of antibiotics after orthopedic surgical interventions. Moreover, the extended release justifies the promising antimicrobial administration of the nanohybrids in bone applications.

  1. Microorganism selection and biosurfactant production in a continuously and periodically operated bioslurry reactor.

    Cassidy, D P; Hudak, A J

    2001-06-29

    A continuous-flow reactor (CSTR) and a soil slurry-sequencing batch reactor (SS-SBR) were maintained in 8l vessels for 180 days to treat a soil contaminated with diesel fuel (DF). Concentrations of Candida tropicalis, Brevibacterium casei, Flavobacterium aquatile, Pseudomonas aeruginosa, and Pseudomonas fluorescens were determined using fatty acid methyl ester (FAME) analysis. DF removal (biological and volatile) and biosurfactant concentrations were measured. The SS-SBR encouraged the growth of biosurfactant-producing species relative to the CSTR. Counts of biosurfactant-producing species (C. tropicalis, P. aeruginosa, P. fluorescens) relative to total microbial counts were 88% in the SS-SBR and 23% in the CSTR. Biosurfactants were produced in the SS-SBR to levels of nearly 70 times the critical micelle concentration (CMC) early in the cycle, but were completely degraded by the end of each cycle. No biosurfactant production was observed in the CSTR. DF biodegradation rates were over 40% greater and DF stripping was over five times lower in the SS-SBR than the CSTR. However, considerable foaming occurred in the SS-SBR. Reversing the mode of operation in the reactors on day 80 caused a complete reversal in microbial consortia and reactor performance by day 120. These results show that bioslurry reactor operation can be manipulated to control overall reactor performance.

  2. Effect of the irradiation of bacteria upon their survival rate during conventional methods of meat preservation

    Szczawinska, M.

    1981-01-01

    The purpose of this paper is to define the effect of irradiation upon the survival rate of non-sporing bacteria (Staphylococcus aureus, Salmonella typhimurium, Escherichia coli, Pseudomonas fluorescens) during basic methods of meat preservation. The bacteria were irradiated in broth by X-rays at a dose that destroyed about 90% of the bacteria (D 10 ). The survival rate of unirradiated and irradiated bacteria during cooling and freezing, in solutions of sodium chloride, nitrates and liquid smoke, was defined. The number of microorganisms was determined directly after irradiation as well as 1, 3, 7, 14, 21 and 28 days after irradiation. The effect of irradiation upon heat resistance of the examined species of bacteria was also defined. The microorganisms were heated in broth, at 70 0 C for 1, 2 and 5 minutes. The obtained results were subjected to statistical analysis. On the basis of the research results, a faster dying rate of irradiated populations of S. aureus and E. coli during any type of preservation treatment, the lack of any reaction to irradiation regarding the survival rate of S. typhimurium, and the lack of any effect of irradiation upon the rate of deterioration of P. fluorescens during freezing and storage in a solution with 10% addition of NaCI, were observed. On the other hand, a pronounced effect of irradiation upon the lowering of the heat resistance of the bacteria, as well as delayed growth in other variants of the experiment, was determined. (author)

  3. Biological control of fusarium seedling blight disease of wheat and barley.

    Khan, Mojibur R; Fischer, Sven; Egan, Damian; Doohan, Fiona M

    2006-04-01

    ABSTRACT Fusarium fungi, including F. culmorum, cause seedling blight, foot rot, and head blight diseases of cereals, resulting in yield loss. In a screen for potential disease control organisms and agents, Pseudomonas fluorescens strains MKB 100 and MKB 249, P. frederiksbergensis strain 202, Pseudomonas sp. strain MKB 158, and chitosan all significantly reduced the extent of both wheat coleoptile growth retardation and wheat and barley seedling blight caused by F. culmorum (by 53 to 91%). Trichodiene synthase is a Fusarium enzyme necessary for trichothecene mycotoxin biosynthesis; expression of the gene encoding this enzyme in wheat was 33% lower in stem base tissue coinoculated with Pseudomonas sp. strain MKB 158 and F. culmorum than in wheat treated with bacterial culture medium and F. culmorum. When wheat and barley were grown in soil amended with either chitosan, P. fluorescens strain MKB 249, Pseudomonas sp. strain MKB 158, or culture filtrates of these bacteria, the level of disease symptoms on F. culmorum-inoculated stem base tissue (at 12 days post- F. culmorum inoculation) was >/=31% less than the level on F. culmorum-inoculated plants grown in culture medium-amended soil. It seems likely that at least part of the biocontrol activity of these bacteria and chitosan may be due to the induction of systemic disease resistance in host plants. Also, in coinoculation studies, Pseudomonas sp. strain MKB 158 induced the expression of a wheat class III plant peroxidase gene (a pathogenesis-related gene).

  4. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    Rahal, Raed

    2013-06-01

    This study describes a method derived from ISO/TC 206/SC specifications to assess the bactericidal activity against a bacterial strain, Pseudomonas fluorescens, of various photocatalytic fabrics, under UVA and filtered visible light. The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant bactericidal efficiency. TiO2-coated fabrics are very efficient against P. fluorescens after 4 h UVA irradiation (bacteria survival below the detection limit). Under UVA-free visible light, anthraquinone-sensitized TiO2 coated fabrics induced a significant bactericidal activity after 2 h irradiation, while anthraquinone alone-coated fabrics were not as efficient and TiO2 coated fabrics were almost inefficient. These results show that although exhibiting a weak n-π* band in the 350-420 nm range, anthraquinone is a good candidate as an efficient visible light photosensitizer. A synergy effect between anthraquinone and TiO2 was demonstrated. A possible reaction mechanism, involving a synergy effect for singlet oxygen formation with anthraquinone-sensitized TiO2 is proposed to account for these results. © 2012 Elsevier B.V. All rights reserved.

  5. Synergistic use of biochar, compost and plant growth-promoting rhizobacteria for enhancing cucumber growth under water deficit conditions.

    Nadeem, Sajid M; Imran, Muhammad; Naveed, Muhammad; Khan, Muhammad Y; Ahmad, Maqshoof; Zahir, Zahir A; Crowley, David E

    2017-12-01

    Limited information is available about the effectiveness of biochar with plant growth-promoting rhizobacteria (PGPR) and compost. A greenhouse study was conducted to evaluate the effect of biochar in combination with compost and PGPR (Pseudomonas fluorescens) for alleviating water deficit stress. Both inoculated and un-inoculated cucumber seeds were sown in soil treated with biochar, compost and biochar + compost. Three water levels - field capacity (D0), 75% field capacity (D1) and 50% field capacity (D2) - were maintained. The results showed that water deficit stress significantly suppressed the growth of cucumber; however, synergistic use of biochar, compost and PGPR mitigated the negative impact of stress. At D2, the synergistic use of biochar, compost and PGPR caused significant increases in shoot length, shoot biomass, root length and root biomass, which were respectively 88, 77, 89 and 74% more than in the un-inoculated control. Significant improvements in chlorophyll and relative water contents as well as reduction in leaf electrolyte leakage demonstrated the effectiveness of this approach. Moreover, the highest population of P. fluorescens was observed where biochar and compost were applied together. These results suggest that application of biochar with PGPR and/or compost could be an effective strategy for enhancing plant growth under stress. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  6. Effect of four growth-promoting rhizobacteria on crown blight caused by Phytophthora capsici in sweet pepper (Capsicum annuum

    Carlos Ramírez

    2015-11-01

    Full Text Available Crown blight, caused by Phytophthora capsici, is the most important disease of pepper (Capsicum annuum in the world and causes great economic losses in Costa Rica. Alternatives to chemical control against this disease are crucial to prevent damage to human health and the environment. The antagonism of Plant-Growth-Promoting Rhizobacteria (PGPR on P. capsici, and its ability to reduce wilt in pepper plants were evaluated. PGPR strains previously isolated from sugarcane and rice were identified, using 16S RNA gene sequence, as Pseudomonas fluorescens PC4, Stenotrophomonas rhizophila PC9, Pseudomonas fragi PC11 and Azospirillum lipoferum PCJ2. The inhibition of P. capcisi growth was evaluated in vitro, in the presence of the PGPR. The effect of the four bacterial strains on pepper plants inoculated with P. capsici (100 zoospores.plant-1 was evaluated in the greenhouse. P. fluorescens PC4, S. rhizophila PC9 and A. lipoferum PCJ2, inhibited in vitro growth of the oomycete by 54%, 30% and 50 % respectively, while S. rhizophila PC9 increased by 14% shoot fresh weight of pepper plants at the greenhouse. Furthermore, PCJ2 and PC9 strains reduced the shoot and root severity of the disease, and PCJ2-inoculated plants showed no symptoms at all, indicating that PC9 and PCJ2 are promising rizobacteria for the control of crown blight in pepper.

  7. Effect of fluorescent pseudomonades and Trichoderma sp. and their combination with two chemicals on Penicillium digitatum caused agent of citrus green mold.

    Zamani, M; Tehrani, A Sharifi; Ahmadzadeh, M; Abadi, A Alizadeh Ali

    2006-01-01

    Citrus green mold (Penicillium digitatum) causes economic losses. Chemical fungicides such as imazalil provide the primary means for controlling green mold decay of citrus fruits. Continuous use of fungicides has faced two major obstacles- increasing public concern regarding contamination of perishables with fungicidal residues, and proliferation of resistance in the pathogen populations. The aim of this research was to determine if the attacks of green mold on orange could be reduced by usage of biocontrol agent alone or in combination with low dosage of imazalil or sodium bicarbonate. Pseudomonas fluorescens isolate PN, P. fluorescens isolate PS and Trichoderma virens isolate TE were evaluated as potential biological agents for control of green mold of oranges caused by P. digitatum. Increasing concentration of SB decreased spore germination of P. digitatum. In laboratory tests, a cell suspension (10(8) cells per ml.) of bacterial strains reduced the incidence of green mold. On fruits surface biocontrol activity of antagonistic isolates was significantly increased when combined with low dosage of imazalil (500ppm) or sodium carbonate (5%). Effect of Trichoderma virens on controlling P. digitatum was better than others with or without these chemicals.

  8. Chemical Composition, Antioxidant and Antimicrobial Activity of Essential Oils from Organic Fennel, Parsley, and Lavender from Spain

    Marín, Irene; Sayas-Barberá, Estrella; Viuda-Martos, Manuel; Navarro, Casilda; Sendra, Esther

    2016-01-01

    The aim of this work was to (i) determine the chemical composition of the essential oils of three spices widely cultivated in Spain from organic growth: Foeniculum vulgare, Petroselium crispum, and Lavandula officinalis; (ii) determine the total phenolic content; (iii) determine the antioxidant activity of the essentials oils by means of three different antioxidant tests and (iv) determine the effectiveness of these essentials oils on the inhibition of Listeria innocua CECT 910 and Pseudomonas fluorescens CECT 844. There is a great variability in the chemical composition of the essential oils. Parsley had the highest phenolic content. Overall, parsley presented the best antioxidant profile, given its highest % of inhibition of DPPH radical (64.28%) and FRAP (0.93 mmol/L Trolox), but had a pro-oxidative behavior by TBARS. Lavender essential oil showed the highest antibacterial activity against L. innocua (>13 mm of inhibition at 20–40 μL oil in the discs), followed by parsley with an inhibition zone of 10 mm (when more than 5 μL oil in the discs), and fennel 10 mm (when more than 40 μL oil in the discs). P. fluorescens was not inhibited by the tested essential oils. PMID:28231113

  9. Artificial Citrate Operon Confers Mineral Phosphate Solubilization Ability to Diverse Fluorescent Pseudomonads

    Adhikary, Hemanta; Sanghavi, Paulomi B.; Macwan, Silviya R.; Archana, Gattupalli; Naresh Kumar, G.

    2014-01-01

    Citric acid is a strong acid with good cation chelating ability and can be very efficient in solubilizing mineral phosphates. Only a few phosphate solubilizing bacteria and fungi are known to secrete citric acids. In this work, we incorporated artificial citrate operon containing NADH insensitive citrate synthase (gltA1) and citrate transporter (citC) genes into the genome of six-plant growth promoting P. fluorescens strains viz., PfO-1, Pf5, CHAO1, P109, ATCC13525 and Fp315 using MiniTn7 transposon gene delivery system. Comprehensive biochemical characterization of the genomic integrants and their comparison with plasmid transformants of the same operon in M9 minimal medium reveals the highest amount of ∼7.6±0.41 mM citric and 29.95±2.8 mM gluconic acid secretion along with ∼43.2±3.24 mM intracellular citrate without affecting the growth of these P. fluorescens strains. All genomic integrants showed enhanced citric and gluconic acid secretion on Tris-Cl rock phosphate (TRP) buffered medium, which was sufficient to release 200–1000 µM Pi in TRP medium. This study demonstrates that MPS ability could be achieved in natural fluorescent pseudomonads by incorporation of artificial citrate operon not only as plasmid but also by genomic integration. PMID:25259527

  10. Cytotoxic and mutagenic effects of conventionally processed foods in comparison with irradiated foods

    Mohyuddin, M.

    1975-05-01

    Several kinds of spices and processed food namely onion, garlic, turmeric, red chillies, black pepper, cloves, cinnamon, simple curry, meat curry, curry prepared from irradiated onions and potatoes and curry from irradiated fish were tested for cytotoxocity and mutagenicity. Onion root tips were used in the studies of cytotoxicity. Pseudomonas fluorescens strain NCTC-9428, a streptomycin-sensitive strain, was used as the test organism in mutagenicity studies. Wide range of cytoxicity was observed in all spices and food tested, varying from 48% abnormality in root tips in black pepper to 97.7% in garlic extract. The degrees of cytotoxic abnormality of irradiated potatoes and onions appeared to be lower than in their control counterparts. The average percentages of cytotoxic abnormality in curry prepared from irradiated fish and the one prepared from irradiated potatoes and onions, at their original concentration, were 95.92% and 99.5% resp. Digesting curry prepared from irradiated potatoes and onions with bile salts appeared to show some detoxification characteristics. The mutation rate of Pseudomonas fluorescens grown in media containing unirradiated spice extract was significantly higher than in the control (media without spice extract). However, the mutation rate of an extract of irradiated onions (10 krad) showed no difference from the control. There was no difference in the mutation rate on extracts of curry prepared from irradiated onions and potatoes from the one prepared from unirradiated onions and potatoes

  11. Antibacterial isoeugenol coating on stainless steel and polyethylene surfaces prevents biofilm growth.

    Nielsen, C K; Subbiahdoss, G; Zeng, G; Salmi, Z; Kjems, J; Mygind, T; Snabe, T; Meyer, R L

    2018-01-01

    Pathogenic bacteria can spread between individuals or between food items via the surfaces they share. Limiting the survival of pathogens on surfaces, therefore, presents an opportunity to limit at least one route of how pathogens spread. In this study, we propose that a simple coating with the essential oil isoeugenol can be used to circumvent the problem of bacterial transfer via surfaces. Two commonly used materials, stainless steel and polyethylene, were coated by physical adsorption, and the coatings were characterized by Raman spectroscopy, atomic force microscopy and water contact angle measurements. We quantified and visualized the colonization of coated and uncoated surfaces by three bacteria: Staphylococcus aureus, Listeria monocytogenes and Pseudomonas fluorescens. No viable cells were detected on surfaces coated with isoeugenol. The isoeugenol coating prepared with simple adsorption proved effective in preventing biofilm formation on stainless steel and polyethylene surfaces. The result was caused by the antibacterial effect of isoeugenol, as the coating did not diminish the adhesive properties of the surface. Our study demonstrates that a simple isoeugenol coating can prevent biofilm formation of S. aureus, L. monocytogenes and P. fluorescens on two commonly used surfaces. © 2017 The Society for Applied Microbiology.

  12. Plant growth promotion rhizobacteria in onion production.

    Colo, Josip; Hajnal-Jafari, Timea I; Durić, Simonida; Stamenov, Dragana; Hamidović, Saud

    2014-01-01

    The aim of the research was to examine the effect of rhizospheric bacteria Azotobacter chroococcum, Pseudomonas fluorescens (strains 1 and 2) and Bacillus subtilis on the growth and yield of onion and on the microorganisms in the rhizosphere of onion. The ability of microorganisms to produce indole-acetic acid (IAA), siderophores and to solubilize tricalcium phosphate (TCP) was also assessed. The experiment was conducted in field conditions, in chernozem type of soil. Bacillus subtilis was the best producer of IAA, whereas Pseudomonas fluorescens strains were better at producing siderophores and solubilizing phosphates. The longest seedling was observed with the application of Azotobacter chroococcum. The height of the plants sixty days after sowing was greater in all the inoculated variants than in the control. The highest onion yield was observed in Bacillus subtilis and Azotobacter chroococcum variants. The total number of bacteria and the number of Azotobacter chroococcum were larger in all the inoculated variants then in the control. The number of fungi decreased in most of the inoculated variants, whereas the number of actinomycetes decreased or remained the same.

  13. Drought-Tolerant Plant Growth-Promoting Rhizobacteria Associated with Foxtail Millet in a Semi-arid Agroecosystem and Their Potential in Alleviating Drought Stress

    Xuguang Niu

    2018-01-01

    Full Text Available The application of plant growth promoting rhizobacteria (PGPR to agro-ecosystems is considered to have the potential for improving plant growth in extreme environments featured by water shortage. Herein, we isolated bacterial strains from foxtail millet (Setaria italica L., a drought-tolerant crop cultivated in semiarid regions in the northeast of China. Four isolates were initially selected for their ability to produce ACC deaminase as well as drought tolerance. The isolates were identified as Pseudomonas fluorescens, Enterobacter hormaechei, and Pseudomonas migulae on the basis of 16S rRNA sequence analysis. All of these drought-tolerant isolates were able to produce EPS (exopolysaccharide. Inoculation with these strains stimulated seed germination and seedling growth under drought stress. Pseudomonas fluorescens DR7 showed the highest level of ACC deaminase and EPS-producing activity. DR7 could efficiently colonize the root adhering soil, increased soil moisture, and enhance the root adhering soil/root tissue ratio. These results suggest drought tolerant PGPR from foxtail millet could enhance plant growth under drought stress conditions and serve as effective bioinoculants to sustain agricultural production in arid regions.

  14. Exploration of new biological specific function by heavy elements stimulus

    Macaskie, Lynne; Renshaw, Joanna; Ohnuki, Toshihiko; Nishiguchi, Norihiko; Utsunomiya, Satoshi; Suzuki, Yoshinori; Shirai, Osamu

    2014-01-01

    We have carried out experiments to investigate bio-mineralization of rare earth elements (REE) on the cell surface of yeast Saccharomyces cerevisiae, and the bacteria Bacillus subtilis, Pseudomonas fluorescens and Serratia sp. The continuous removal of 1 mM La (100%) Nd (100%) and Eu (>80%) was observed using a continuous flow through immobilized Serratia sp cell columns. Chemical and physical characterization of bio-mineralized La and Eu was done by XRD at Birmingham and showed the formation of phosphate minerals. Additional cell column work using S. cerevisiae, B. subtilis, or P. fluorescens, showed that these bacteria are capable of bio-mineralizing Ce(III) and Sm(III). Chemical and physical characterizations of bio-transformed Ce and Sm were analyzed by JAEA, Kyushu U., Tokyo U. Tech. and Kyoto U. using XAFS, SEM and TEM. Results showed that Ce and Sm nanoparticles were formed. The high radiostability of the metal accumulating enzyme of Serratia sp. (which promotes metal phosphate deposition) was shown in whole cells, whereas pure enzyme lost its activity quickly under irradiation. Additional work on radionuclide (Cm) incorporation into Serratia sp calcium phosphate minerals (analogue for human bones) using EXAFS and Time Resolved Laser Fluorescence Spectroscopy (in collaboration with Karlsruhe Institute of Technology) showed that this actinide binds at the grain boundaries between crystallites, which has health implications for human exposure. (author)

  15. Exploration of new biological specific function by heavy elements stimulus

    Macaskie, Lynne; Renshaw, Joanna; Ohnuki, Toshihiko; Nishiguchi, Norihiko; Utsunomiya, Satoshi; Suzuki, Yoshinori; Shirai, Osamu

    2012-01-01

    We have carried out experiments to investigate bio-mineralization of rare earth elements (REE) on the cell surface of yeast Saccharomyces cerevisiae, and the bacteria Bacillus subtilis, Pseudomonas fluorescens and Serratia sp. The continuous removal of 1 mM La (100%) Nd (100%) and Eu(>80%) was observed using a continuous flow through immobilized Serratia sp cell columns. Chemical and physical characterization of bio-mineralized La and Eu was done by XRD at Birmingham and showed the formation of phosphate minerals. Additional cell column work using S. cerevisiae, B. subtilis, or P. fluorescens, showed that these bacteria are capable of bio-mineralizing Ce(III) and Sm(III). Chemical and physical characterizations of bio-transformed Ce and Sm were analyzed by JAEA, Kyushu U., Tokyo U. Tech. and Kyoto U. using XAFS, SEM and TEM. Results showed that Ce and Sm nanoparticles were formed. The high radiostability of the metal accumulating enzyme of Serratia sp. (which promotes metal phosphate deposition) was shown in whole cells, whereas pure enzyme lost its activity quickly under irradiation. Additional work on radionuclide (Cm) incorporation into Serratia sp calcium phosphate minerals (analogue for human bones) using EXAFS and Time Resolved Laser Fluorescence Spectroscopy (in collaboration with Karlsruhe Institute of Technology) showed that this actinide binds at the grain boundaries between crystallites, which has health implications for human exposure. (author)

  16. Taxonomic characterization of the cellulose-degrading bacterium NCIB 10462

    Dees, C.; Ringleberg, D.; Scott, T.C. [Oak Ridge National Lab., TN (United States); Phelps, T. [Univ. of Tennessee, Knoxville, TN (United States)

    1994-06-01

    The gram negative cellulase-producing bacterium NCIB 10462 has been previously named Pseudomonas fluorescens subsp. or var. cellulosa. Since there is renewed interest in cellulose-degrading bacteria for use in bioconversion of cellulose to chemical feed stocks and fuels, we re-examined the characteristics of this microorganism to determine its proper taxonomic characterization and to further define it`s true metabolic potential. Metabolic and physical characterization of NCIB 10462 revealed that this was an alkalophilic, non-fermentative, gram negative, oxidase positive, motile, cellulose-degrading bacterium. The aerobic substrate utilization profile of this bacterium was found to have few characteristics consistent with a classification of P. fluorescens with a very low probability match with the genus Sphingomonas. Total lipid analysis did not reveal that any sphingolipid bases are produced by this bacterium. NCIB 10462 was found to grow best aerobically but also grows well in complex media under reducing conditions. NCIB 10462 grew slowly under full anaerobic conditions on complex media but growth on cellulosic media was found only under aerobic conditions. Total fatty acid analysis (MIDI) of NCIB 10462 failed to group this bacterium with a known pseudomonas species. However, fatty acid analysis of the bacteria when grown at temperatures below 37{degrees}C suggest that the organism is a pseudomonad. Since a predominant characteristic of this bacterium is it`s ability to degrade cellulose, we suggest it be called Pseudomonas cellulosa.

  17. Zinc and glycerol enhance the production of nematicidal compounds in vitro and improve the biocontrol of Meloidogyne javanica in tomato by fluorescent pseudomonads.

    Siddiqui, I A; Shaukat, S S

    2002-01-01

    To assess the effects of various carbon and mineral sources on the nematicidal potential of biocontrol inoculants of Pseudomonas aeruginosa IE-6S+ and Ps. fluorescens CHA0 under laboratory and glasshouse conditions. Culture filtrates of strains IE-6S+ and CHA0, cultured in nutrient yeast extract broth, caused substantial mortality of the juveniles of Meloidogyne javanica. The nematicidal activities of the culture filtrates were altered after amendment with various carbon and mineral sources. Soil amendment with zinc alone or in combination with glycerol improved the biocontrol efficacy against root-knot nematode, promoted tomato plant growth and enhanced bacterial rhizosphere and endophytic colonization. Appropriate quantities of glycerol and zinc alone or in combination enhance the nematicidal activity of Ps. aeruginosa and Ps. fluorescens. Glucose reduces the activity of these bacteria against nematodes. Minerals and carbon sources are appealing because they are easy and economical to provide during liquid fermentation of inoculants or as fertilizer amendments to improve the biocontrol activity of indigenous and introduced bacteria.

  18. Mechanisms regulating the reduction of selenite by aerobic gram (+) and (-) bacteria

    Garbisu, C.; Ishii, Takahisa; Yee, B.C.; Carlson, D.E.; Buchanan, B.B.; Leighton, T.; Smith, N.R.; Yee, A.

    1995-01-01

    Toxic species of selenium are pollutants found in agricultural and oil refinery wastestreams. Selenium contamination is particularly problematic in areas that have seleniferous subsurface geology, such as the central valley of California. The authors are developed a bacterial treatment system to mitigate selenium-contaminated wastestreams using Bacillus subtilis and Pseudomonas fluorescens, respectively, as model gram (+) and (-) soil bacteria. They have found that, during growth, both organisms reduce selenite, a major soluble toxic species, to red elemental selenium--an insoluble product generally regarded as nontoxic. In both cases, reduction depended on growth substrate and was effected by an inducible system that effectively removed selenite at concentrations typical of polluted sites--i.e., 50 to 300 microg/L. The bacteria studied differed in one respect: when grown in medium supplemented with nitrate or sulfate, the ability of P. fluorescens to remediate selenite was enhanced, whereas that of B. subtilis was unchanged. Current efforts are being directed toward understanding the biochemical mechanism(s) of detoxification and determining whether bacteria occurring in polluted environments such as soils and sludge systems are capable of selenite remediation

  19. Morphological and biochemical characterization of xanthomonas campestris (pammel) dawson pv. Sesame and it's management by bacterial antagonists

    Naqvi, S.F.; Haq, M.I.U.; Tahir, M.I.; Khan, M.A.; Ali, Z.

    2013-01-01

    Isolates of Xanthomonas campestris (Pammel) Dawson pv. sesami (Xcs) were collected from various locations in Pakistan and were characterized using several biochemical tests including; (KOH) string test, gram staining, H/sub 2/S production, catalase activity, oxidation/fermentation of glucose, oxidase activity and nitrate reduction. The isolates were positive in tests for KOH string assay, H/sub 2/S, catalase and showed negative reactions in gram staining, oxidase test and nitrate reduction while oxidative utilization of glucose was observed. To develop biological control for the pathogen we isolated numerous bacteria from the rhizosphere of sesame plants and screened them for antagonism against the pathogen using the zone inhibition method. Out of 87 isolates, 9 isolates were inhibitory to the pathogen in vitro. Pseudomonas fluorescens ID-3 exhibited the highest zone of inhibition i.e. 7.97mm. All antagonistic isolates were tested for disease control under greenhouse conditions. Four sesame lines that were found to be moderately resistant in previous studies (i.e. 95001, 96007, 96019, and 20003) were selected for evaluating biocontrol efficacy. The isolates were found to control the disease and reduced severity to 3% compared to untreated plants. The isolate P. fluorescens ID-3 was considered to provide the best disease control with each cultivar. Average biocontrol efficiency (BE) of ID-3 was 78.25% while the best BE was obtained in line 96019, i.e. 81%. (author)

  20. EFFECT OF REFINED PETROLEUM PRODUCTS CONTAMINATION ON BACTERIAL POPULATION AND PHYSICOCHEMICAL CHARACTERISTICS OF CULTIVATED AGRICULTURAL SOIL

    Adewale Sogo Olalemi

    2012-10-01

    Full Text Available An investigation into the effect of refined petroleum products contamination on bacterial population and physicochemical characteristics of cultivated agricultural soil was carried out. The soil samples obtained from the Teaching and Research Farm, Obakekere, Federal University of Technology, Akure, Ondo State were contaminated with varying volumes of petrol, diesel and kerosene. The results revealed higher bacterial populations in uncontaminated soils than contaminated soils. The counts of bacteria ranged from 3.0 × 105 to 5.0 × 105 cfu/g in uncontaminated soils and 1.0 × 105 to 3.0 × 105 cfu/g in contaminated soils. The isolated bacteria were identified as Bacillus subtilis, Flavobacterium lutescens, Micrococcus luteus, Corynebacterium variabilis, Pseudomonas fluorescens. The contamination had no significant effect on pH, potassium, sodium, organic carbon and nitrogen content of the soils, while the moisture, calcium, phosphorus and magnesium content of the contaminated soils were significantly different (P < 0.05 compared with the uncontaminated soils. The ability of Bacillus subtilis, Flavobacterium lutescens, Micrococcus luteus, and Pseudomonas fluorescens to utilize the refined petroleum products suggest that these bacteria had potential to bioremediate petroleum contaminated soils.

  1. Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

    Nomura, Toshiyuki; Fujisawa, Eri; Itoh, Shikibu; Konishi, Yasuhiro

    2016-06-01

    The cytotoxic effect of positively charged polystyrene latex nanoparticles (PSL NPs) was compared between planktonic bacterial cells and bacterial biofilms using confocal laser scanning microscopy, atomic force microscopy, and a colony counting method. Pseudomonas fluorescens, which is commonly used in biofilm studies, was employed as the model bacteria. We found that the negatively charged bacterial surface of the planktonic cells was almost completely covered with positively charged PSL NPs, leading to cell death, as indicated by the NP concentration being greater than that required to achieve single layer coverage. In addition, the relationship between surface coverage and cell viability of P. fluorescens cells correlated well with the findings in other bacterial cells ( Escherichia coli and Lactococcus lactis). However, most of the bacterial cells that formed the biofilm were viable despite the positively charged PSL NPs being highly toxic to planktonic bacterial cells. This indicated that bacterial cells embedded in the biofilm were protected by self-produced extracellular polymeric substances (EPS) that provide resistance to antibacterial agents. In conclusion, mature biofilms covered with EPS exhibit resistance to NP toxicity as well as antibacterial agents.

  2. Antimicrobial activities of commercial essential oils and their components against food-borne pathogens and food spoilage bacteria

    Mith, Hasika; Duré, Rémi; Delcenserie, Véronique; Zhiri, Abdesselam; Daube, Georges; Clinquart, Antoine

    2014-01-01

    This study was undertaken to determine the in vitro antimicrobial activities of 15 commercial essential oils and their main components in order to pre-select candidates for potential application in highly perishable food preservation. The antibacterial effects against food-borne pathogenic bacteria (Listeria monocytogenes, Salmonella Typhimurium, and enterohemorrhagic Escherichia coli O157:H7) and food spoilage bacteria (Brochothrix thermosphacta and Pseudomonas fluorescens) were tested using paper disk diffusion method, followed by determination of minimum inhibitory (MIC) and bactericidal (MBC) concentrations. Most of the tested essential oils exhibited antimicrobial activity against all tested bacteria, except galangal oil. The essential oils of cinnamon, oregano, and thyme showed strong antimicrobial activities with MIC ≥ 0.125 μL/mL and MBC ≥ 0.25 μL/mL. Among tested bacteria, P. fluorescens was the most resistant to selected essential oils with MICs and MBCs of 1 μL/mL. The results suggest that the activity of the essential oils of cinnamon, oregano, thyme, and clove can be attributed to the existence mostly of cinnamaldehyde, carvacrol, thymol, and eugenol, which appear to possess similar activities against all the tested bacteria. These materials could be served as an important natural alternative to prevent bacterial growth in food products. PMID:25473498

  3. Biodiesel production using waste frying oil

    Charpe, Trupti W.; Rathod, Virendra K.

    2011-01-01

    Research highlights: → Waste sunflower frying oil is successfully converted to biodiesel using lipase as catalyst. → Various process parameters that affects the conversion of transesterification reaction such as temperature, enzyme concentration, methanol: oil ratio and solvent are optimized. → Inhibitory effect of methanol on lipase is reduced by adding methanol in three stages. → Polar solvents like n-hexane and n-heptane increases the conversion of tranesterification reaction. - Abstract: Waste sunflower frying oil is used in biodiesel production by transesterification using an enzyme as a catalyst in a batch reactor. Various microbial lipases have been used in transesterification reaction to select an optimum lipase. The effects of various parameters such as temperature, methanol:oil ratio, enzyme concentration and solvent on the conversion of methyl ester have been studied. The Pseudomonas fluorescens enzyme yielded the highest conversion. Using the P. fluorescens enzyme, the optimum conditions included a temperature of 45 deg. C, an enzyme concentration of 5% and a methanol:oil molar ratio 3:1. To avoid an inhibitory effect, the addition of methanol was performed in three stages. The conversion obtained after 24 h of reaction increased from 55.8% to 63.84% because of the stage-wise addition of methanol. The addition of a non-polar solvent result in a higher conversion compared to polar solvents. Transesterification of waste sunflower frying oil under the optimum conditions and single-stage methanol addition was compared to the refined sunflower oil.

  4. Characterization of initial events in bacterial surface colonization by two Pseudomonas species using image analysis.

    Mueller, R F; Characklis, W G; Jones, W L; Sears, J T

    1992-05-01

    The processes leading to bacterial colonization on solid-water interfaces are adsorption, desorption, growth, and erosion. These processes have been measured individually in situ in a flowing system in real time using image analysis. Four different substrata (copper, silicon, 316 stainless-steel and glass) and 2 different bacterial species (Pseudomonas aeruginosa and Pseudomonas fluorescens) were used in the experiments. The flow was laminar (Re = 1.4) and the shear stress was kept constant during all experiments at 0.75 N m(-2). The surface roughness varied among the substrata from 0.002 microm (for silicon) to 0.015 microm (for copper). Surface free energies varied from 25.1 dynes cm(-1) for silicon to 31.2 dynes cm(-1) for copper. Cell curface hydrophobicity, reported as hydrocarbon partitioning values, ranged from 0.67 for Ps. fluorescens to 0.97 for Ps. aeruginosa.The adsorption rate coefficient varied by as much as a factor of 10 among the combinations of bacterial strain and substratum material, and was positively correlated with surface free energy, the surface roughness of the substratum, and the hydrophobicity of the cells. The probability of desorption decreased with increasing surface free energy and surface roughness of the substratum. Cell growth was inhibited on copper, but replication of cells overlying an initial cell layer was observed with increased exposure time to the cell-containing bulk water. A mathematical model describing cell accumulation on a substratum is presented.

  5. The Influence of Interfering Substances on the Antimicrobial Activity of Selected Quaternary Ammonium Compounds

    Paula A. Araújo

    2013-01-01

    Full Text Available Standard cleaning processes may not remove all the soiling typically found in food industry, such as carbohydrates, fats, or proteins. Contaminants have a high impact in disinfection as their presence may reduce the activity of disinfectants. The influence of alginic acid, bovine serum albumin, yeast extract, and humic acids was assessed on the antimicrobial activities of benzalkonium chloride and cetyltrimethyl ammonium bromide against Bacillus cereus vegetative cells and Pseudomonas fluorescens. The bacteria (single and consortium were exposed to surfactants (single and combined in the absence and presence of potential disinfection interfering substances. The antimicrobial effects of the surfactants were assessed based on the bacterial respiratory activity measured by oxygen uptake rate due to glucose oxidation. The tested surfactants were efficient against both bacteria (single and consortium with minimum bactericidal concentrations ranging from 3 to 35 mg·L−1. The strongest effect was caused by humic acids that severely quenched antimicrobial action, increasing the minimum bactericidal concentration of the surfactants on P. fluorescens and the consortium. The inclusion of the other interfering substances resulted in mild interferences in the antibacterial activity. This study clearly demonstrates that humic acids should be considered as an antimicrobial interfering substance in the development of disinfection strategies.

  6. Glyphosate-Induced Specific and Widespread Perturbations in the Metabolome of Soil Pseudomonas Species

    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

  7. 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.

    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

  8. Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent

    Petti Carloalberto

    2012-11-01

    Full Text Available Abstract Background Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA and abscisic acid (ABA, are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB disease of barley and to determine if biocontrol-associated hormones directly affect disease development. Results A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Conclusions Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced

  9. Auxin as a player in the biocontrol of Fusarium head blight disease of barley and its potential as a disease control agent.

    Petti, Carloalberto; Reiber, Kathrin; Ali, Shahin S; Berney, Margaret; Doohan, Fiona M

    2012-11-22

    Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA) and abscisic acid (ABA), are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens -mediated control of Fusarium head blight (FHB) disease of barley and to determine if biocontrol-associated hormones directly affect disease development. A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced both symptoms and yield loss asssociated with the disease

  10. Chemical resistance of the gram-negative bacteria to different sanitizers in a water purification system

    Penna Thereza CV

    2006-08-01

    Full Text Available Abstract Background Purified water for pharmaceutical purposes must be free of microbial contamination and pyrogens. Even with the additional sanitary and disinfecting treatments applied to the system (sequential operational stages, Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas alcaligenes, Pseudomonas picketti, Flavobacterium aureum, Acinetobacter lowffi and Pseudomonas diminuta were isolated and identified from a thirteen-stage purification system. To evaluate the efficacy of the chemical agents used in the disinfecting process along with those used to adjust chemical characteristics of the system, over the identified bacteria, the kinetic parameter of killing time (D-value necessary to inactivate 90% of the initial bioburden (decimal reduction time was experimentally determined. Methods Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas alcaligenes, Pseudomonas picketti, Flavobacterium aureum, Acinetobacter lowffi and Pseudomonas diminuta were called in house (wild bacteria. Pseudomonas diminuta ATCC 11568, Pseudomonas alcaligenes INCQS , Pseudomonas aeruginosa ATCC 15442, Pseudomonas fluorescens ATCC 3178, Pseudomonas picketti ATCC 5031, Bacillus subtilis ATCC 937 and Escherichia coli ATCC 25922 were used as 'standard' bacteria to evaluate resistance at 25°C against either 0.5% citric acid, 0.5% hydrochloric acid, 70% ethanol, 0.5% sodium bisulfite, 0.4% sodium hydroxide, 0.5% sodium hypochlorite, or a mixture of 2.2% hydrogen peroxide (H2O2 and 0.45% peracetic acid. Results The efficacy of the sanitizers varied with concentration and contact time to reduce decimal logarithmic (log10 population (n cycles. To kill 90% of the initial population (or one log10 cycle, the necessary time (D-value was for P. aeruginosa into: (i 0.5% citric acid, D = 3.8 min; (ii 0.5% hydrochloric acid, D = 6.9 min; (iii 70% ethanol, D = 9.7 min; (iv 0.5% sodium bisulfite, D = 5.3 min; (v 0.4% sodium hydroxide, D = 14.2 min; (vi 0.5% sodium

  11. Radionuclides can be mobilized by bacteria from the subsurface grown under aerobic as well as anaerobic conditions

    Johnsson, A.; Arlinger, J.; Pedersen, K.; Albinsson, Y.; Andlid, T.

    2005-01-01

    Full text of publication follows: Microbes can influence radionuclide mobility in many ways. They can change the pH or redox of their surroundings, act as nucleation sites for precipitation, transport metals sorbed to the cell surface and excrete organic compounds that form mobile radionuclide complexes. The processes behind bio-mobilization of radionuclides are important to study as they may have implications on e g radioactive waste disposal. Three bacterial species; Pseudomonas fluorescens, Pseudomonas stutzeri and Shewanella putrefaciens were selected for this study. All bacteria were grown under aerobic conditions and P. stutzeri and S. putrefaciens were also grown under anaerobic conditions. Aerobic and anaerobic cultures were centrifuged after having reached stationary phase. The supernatants, containing the exudates of the bacteria, were collected. 59 Fe(III), 147 Pm(III), 234 Th(IV) and 241 Am(III) were added to the supernatants and SiO 2 was added to the supernatant radionuclide mix. The amount of radionuclide in the liquid phase was analyzed using liquid scintillation counting and Na-I gamma spectrometry. Supernatants of all three species of aerobically grown bacteria mobilize more than 60% of all four radionuclides. High performance liquid chromatography (HPLC) analysis detected four Fe-complexing substances in the supernatant of P. fluorescens and two peaks and one peak, respectively, in the supernatants of P. stutzeri and S. putrefaciens. All substances eluted from the column varied in retention times, indicating that the microbes produced several metabolites that have different complexing abilities. Comparing HPLC data with mobilization data show that P. fluorescens mobilizes the largest percentage of radionuclide and S. putrefaciens mobilizes the least amount of radionuclides in all cases. Like aerobic supernatants the supernatants of anaerobically grown bacteria test positive for siderophores. Despite this 59 Fe(III) shows no net mobilization

  12. Microbial mobilization of cesium from illite: Role of organic acids and siderophores

    Hazotte, Alice; Peron, Olivier; Abdelouas, Abdesselam; Lebeau, Thierry

    2015-04-01

    Understanding the behavior of cesium (Cs) in soils and geological formations is interesting in the context of nuclear accidents and nuclear waste disposals. Indeed, this radionuclide with a 30-years half-life can contaminate crops and more generally the food chain. Cs with properties similar to potassium is known to be strongly accumulated in the clays of upper soil horizons. While excavation of contaminated soil cannot be feasible for the whole contaminated surfaces (huge volumes to be cleaned-up), in situ methods could provide a sustainable and low cost solution. Phytoextraction is one of a few solutions for in situ remediation of soils contaminated by trace elements and it preserves the quality of agricultural soils. However, many improvements are still needed to enhance phytoextraction effectiveness. The combination of bioaugmentation (soil inoculation with exogenous microorganisms) with phytoextraction is likely to increase the bioaccessibility of radionuclides and their accumulation in plants. The role of bacteria on soil-pollutants can be direct (direct metal complexation) and/or indirect (weathering of clays adsorbing Cs). This study aims to provide more specifically a mechanistic understanding of the bacterial mobilization of Cs from soil with the prospect of soil bioremediation. Bacterial metabolites of Pseudomonas fluorescens (ATCC 17400) were supplied to illite spiked with 0.1 and 1 mM of Cs. Purified siderophores including pyoverdine from P. fluorescens, or the whole metabolites from the bacterial culture supernatant were compared to low molecular weight organic acids (LMWOA) (citric and oxalic acids) at 0.04 mM, or synthetic chelants, i.e., acetohydroxamic acid (AHA) and desferrioxamine mesylate (DFOM) ranging from 50 µM up to 250 µM. The release of Cs and the structural alteration of illite (release of Al, Fe and Si) were monitored. When compared to the control, no release of Cs from illite was observed with LMWOA. On the contrary, a slight release

  13. Continuous measurements of nitrous oxide isotopomers during incubation experiments

    Winther, Malte; Balslev-Harder, David; Christensen, Søren; Priemé, Anders; Elberling, Bo; Crosson, Eric; Blunier, Thomas

    2018-02-01

    Nitrous oxide (N2O) is an important and strong greenhouse gas in the atmosphere. It is produced by microbes during nitrification and denitrification in terrestrial and aquatic ecosystems. The main sinks for N2O are turnover by denitrification and photolysis and photo-oxidation in the stratosphere. In the linear N = N = O molecule 15N substitution is possible in two distinct positions: central and terminal. The respective molecules, 14N15N16O and 15N14N16O, are called isotopomers. It has been demonstrated that N2O produced by nitrifying or denitrifying microbes exhibits a different relative abundance of the isotopomers. Therefore, measurements of the site preference (difference in the abundance of the two isotopomers) in N2O can be used to determine the source of N2O, i.e., nitrification or denitrification. Recent instrument development allows for continuous position-dependent δ15N measurements at N2O concentrations relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N2O) and Pseudomonas chlororaphis (only producing N2O). The continuous measurements of N2O isotopomers reveals the transient isotope exchange among KNO3, N2O, and N2. We find bulk isotopic fractionation of -5.01 ‰ ± 1.20 for P. chlororaphis, in line with previous results for production from denitrification. For P. fluorescens, the bulk isotopic fractionation during production of N2O is -52.21 ‰ ± 9.28 and 8.77 ‰ ± 4.49 during N2O reduction.The site preference (SP) isotopic fractionation for P. chlororaphis is -3.42 ‰ ± 1.69. For P. fluorescens, the calculations result in SP isotopic fractionation values of 5.73 ‰ ± 5.26 during production of N2O and 2.41 ‰ ± 3.04 during reduction of N2O. In summary, we implemented continuous measurements of N2O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better

  14. Antimicrobial activity of the bioactive components of essential oils from Pakistani spices against Salmonella and other multi-drug resistant bacteria

    2013-01-01

    Background The main objective of this study was the phytochemical characterization of four indigenous essential oils obtained from spices and their antibacterial activities against the multidrug resistant clinical and soil isolates prevalent in Pakistan, and ATCC reference strains. Methods Chemical composition of essential oils from four Pakistani spices cumin (Cuminum cyminum), cinnamon (Cinnamomum verum), cardamom (Amomum subulatum) and clove (Syzygium aromaticum) were analyzed on GC/MS. Their antibacterial activities were investigated by minimum inhibitory concentration (MIC) and Thin-Layer Chromatography-Bioautographic (TLC-Bioautographic) assays against pathogenic strains Salmonella typhi (D1 Vi-positive), Salmonella typhi (G7 Vi-negative), Salmonella paratyphi A, Escherichia coli (SS1), Staphylococcus aureus, Pseudomonas fluorescens and Bacillus licheniformis (ATCC 14580). The data were statistically analyzed by using Analysis of Variance (ANOVA) and Least Significant Difference (LSD) method to find out significant relationship of essential oils biological activities at p essential oils, oil from the bark of C. verum showed best antibacterial activities against all selected bacterial strains in the MIC assay, especially with 2.9 mg/ml concentration against S. typhi G7 Vi-negative and P. fluorescens strains. TLC-bioautography confirmed the presence of biologically active anti-microbial components in all tested essential oils. P. fluorescens was found susceptible to C. verum essential oil while E. coli SS1 and S. aureus were resistant to C. verum and A. subulatum essential oils, respectively, as determined in bioautography assay. The GC/MS analysis revealed that essential oils of C. cyminum, C. verum, A. subulatum, and S. aromaticum contain 17.2% cuminaldehyde, 4.3% t-cinnamaldehyde, 5.2% eucalyptol and 0.73% eugenol, respectively. Conclusions Most of the essential oils included in this study possessed good antibacterial activities against selected multi

  15. Efecto de rizobacterias promotoras de crecimiento vegetal solubilizadoras de fosfato en Lactuca sativa cultivar White Boston

    Diana Beatriz Sanchez López

    2014-07-01

    Full Text Available Título en español: Efecto de rizobacterias promotoras de crecimiento vegetal solubilizadoras de fosfato en Lactuca sativa cultivar White Boston Título en ingles: Effect of plant growth promoting rhizobacteria phosate solubilizing  Lactuca sativa cultivar White Boston Resumen:  En las últimas décadas, la agricultura colombiana se ha visto afectada por la reducción de la productividad en las zonas hortícolas, el incremento de los costos de producción y la dependencia del uso de productos químicos, produciendo un daño irreversible al medio ambiente y la calidad de vida de productores y consumidores. El objetivo de investigación fue evaluar el efecto de rizobacterias promotoras del crecimiento  vegetal del género Pseudomonas sp. sobre Lactuca sativa cultivar White Boston como solubilizadoras de roca fosfórica. El estudio se realizó en el Centro de Investigación Tibaitatá (Corpoica ubicado en Mosquera (Cundinamarca-Colombia. Los resultados demostraron que las cepas tienen la capacidad intrínseca para solubilizar fuentes de fósforo de baja solubilidad como la roca fosfórica. La aplicación de inoculantes con base en las cepas: Pseudomonas fluorescens FR1, Pseudomonas sp., UVLO27 y Pseudomonas sp. LEAV18 arrojaron los mejores resultados. Las cepas Pseudomonas sp. FR2, UVLO27 y K35, tienen la capacidad de producir índoles y sideróforos. El experimento en invernadero evidenció que las cepas Pseudomonas fluorescens FR1, Pseudomonas sp. FR2 y UVLO27 incrementaron de manera significativa (P<0.05 la biomasa y el desarrollo de las plantas. El uso de rocas fosfóricas representa una alternativa económica y ecológica viable, en sistemas de agricultura sostenible.  Palabras claves: Pseudomonas sp., Biofertilizantes, Roca fosfórica, Fósforo, Índoles totales. Abstract:  In the last decades, Colombian agriculture has been affected by the reduction in productivity in horticultural areas, increase in production costs and the dependence

  16. Two-step treatment of harmful industrial wastewater: an analysis of microbial reactor with integrated membrane retention for benzene and toluene removal

    Trusek-Holownia Anna

    2015-12-01

    Full Text Available Standards for highly toxic and carcinogenic pollutants impose strict guidelines, requiring values close to zero, regarding the degradation of such pollutants in industrial streams. In many cases, classic bioremoval processes fail. Therefore, we proposed a stream leaving the microbial membrane bioreactor (MBR that is directed to an additional membrane separation mode (NF/RO. Under certain conditions, the integrated process not only benefits the environment but may also increase the profitability of the bioreactor operation. An appropriate model was developed and tested in which the bioremoval of benzene and toluene by Pseudomonas fluorescens was used as an example. This paper presents equations for selecting the operation parameters of the integrated system to achieve the expected degree of industrial wastewater purification.

  17. The role of cellular catalase on the radiosensitization of bacterial vegetative cells by N2O

    Watanabe, H.; Takehisa, M.

    1983-01-01

    The radiosensitizing effect of N 2 O on eight strains of bacteria was measured in dilute suspensions. The dose-modifying factors (DMF) of N 2 O on M. radiodurans R 1 , P. radiora O-1, M. lysodeikticus and B. pumilus E601 (vegetative cells) were 3.4, 2.9, 2.4 and 1.7, respectively. But P. radiora RP-C, P. fluorescens B3-1, E. coli B/r and E. coli K-12 were hardly sensitized by N 2 O. From measurements of catalase activity of each bacterium, it was found that the DMF increases with increased catalase activity, suggesting that cellular catalase promotes the sensitizing action of N 2 O. (author)

  18. NÖTR VE ALKALİ pH'LARDAKİ KALSİYUM HİDROKSİT VE TİTANYUM DİOKSİT PATLARININ ANTİMİKROP ETKİLERİNİN KARŞILAŞTIRMALI OLARAK İNCELENMESİ*-COMPARISON OF ANTIBACTERIAL EFFECTIVENESS OF TITANIUM DIOXIDE AND CALCIUM HYDROXIDE PASTES AT NEUTRAL AND ALKALINE pHs

    Dindar, Seçkin; Külekçi, Güven; Özbaş, Hakan; Turan, Fatma

    2013-01-01

    ÖzetBu in vitro çalışmada farklı pH'lardaki titanyum diok-sit (Tİ02) ve kalsiyum hidroksit (Ca (OH)2)'nin anti-mikrop etkilerinin araştırılması amaçlanmıştır. TİO2 ve Ca (OH)2 patları pH:7 ve pH:10 olmak üzere hazır­lanmıştır. Patların antimikrop etkileri Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas fluorescens, Escherichia coli, Klebsiella pneumoniae, Peptostreptococcus sp., Lactobacillus sp., Fusobacte-rium sp., Porphyromonas gingivalis, Bacteroides fragilis, Clo...

  19. NÖTR VE ALKALİ pH'LARDAKİ KALSİYUM HİDROKSİT VE TİTANYUM DİOKSİT PATLARININ ANTİMİKROP ETKİLERİNİN KARŞILAŞTIRMALI OLARAK İNCELENMESİ*-COMPARISON OF ANTIBACTERIAL EFFECTIVENESS OF TITANIUM DIOXIDE AND CALCIUM HYDROXIDE PASTES AT NEUTRAL AND ALKALINE pHs

    Dindar, Seçkin; Külekçi, Güven; Özbaş, Hakan; Turan, Fatma

    2013-01-01

    ÖzetBu in vitro çalışmada farklı pH'lardaki titanyum diok-sit (Tİ02) ve kalsiyum hidroksit (Ca (OH)2)'nin anti-mikrop etkilerinin araştırılması amaçlanmıştır. TİO2 ve Ca (OH)2 patları pH:7 ve pH:10 olmak üzere hazır­lanmıştır. Patların antimikrop etkileri Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas fluorescens, Escherichia coli, Klebsiella pneumoniae, Peptostreptococcus sp., Lactobacillus sp., Fusobacte-rium sp., Porphyromonas gingivalis, Bacteroides fragilis, Clostridium s...

  20. Survival of heterotrophic bacteria in water environment under substrate deficiency

    Toth, D.

    1989-01-01

    The relationship between metabolic changes and survival of bacteria in the water environment under substrate deficiency was studied. The main factors supporting cell survival were cryptic growth, utilization of endogenous reserve substances and reorganization of metabolic activities. Based on the utilization of cell-free extract or lysates from dead bacteria, an Enterobacter aerogenes cell suspension yielded 50% more colonies. Metabolic processes of starved heterotrophic bacteria changed markedly and became stabilized at a lower level depending on species involved. The rate of utilization of endogenous reserve substances as indicated by endogenous respiration was related to the rate of cell mortality. Of the test bacteria, Pseudomonas fluorescens showed the lowest rates of endogenous respiration and mortality while in Enterobacter aerogenes these two rates were the highest. (author). 3 figs., 2 tabs.., 16 refs

  1. Role of trophallaxis in the dispersal of radioactive I/sup 131/ and of bacterial infections in the termite, Bifiditermes beesoni

    Khan, K.I.; Jafri, R.H.; Ahmad, M.

    1981-01-01

    Dispersal and localisation of radioactive iodine (I/sup 131/) through trophallaxis was studied in various organs of healthy or bacteria-infected pseudergates of Bifiditermes beesoni. The breakdown of the defence system by bacterial pathogens was also studied by means of I/sup 131/. Individual groups of pseudergates of B. beesoni were infected by various bacterial pathogens, i.e. Thuricide-HP (commercial preparation of Bacillus thuringiensis), B. thuringiensis 11-toumanoffi, B. thuringiensis serotype 3a, 3b, Pseudomonas fluorescens and Serratia marcescens, respectively. Healthy pseudergates retained more radioactivity in their guts and less in their exoskeletons. However, bacteria-infected 'donor' and 'recipient' pseudergates and soldiers retained less radioactivity in their guts and more in their exoskeletons. The flow of radioactivity from gut towards exoskeleton or other parts of B. beesoni pseudergates occurred after destruction and breakdown of the inestinal defence system of the host.

  2. Inhibition of in vitro growth of soil-borne pathogens by compost-inhabiting indigenous bacteria and fungi

    Ramzan, N.; Noreen, N.; Shahzad, S.

    2014-01-01

    During the present studies, compost-inhabiting microorganisms including 44 fungi and 15 bacteria isolated from different compost samples were evaluated for their in vitro efficacy against soil-borne pathogens viz., Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum, Rhizoctonia solani, and Sclerotium rolfsii. Compost inhabiting microbes like Trichoderma harzianum, T. virens, Bacillus cereus, B. pumilus, B. subtilis, Micrococcus varians and Pseudomonas fluorescens were found to inhibit all the test pathogens. Acrophialophora fusispora and Penicillium citrinum reduced the mycelial growth of all the test pathogens except Sclerotium rolfsii. Bacillus licheniformis and Bacillus megaterium showed biocontrol activity against all the pathogens except Rhizoctonia solani. Trichoderma harzianum parasitized mycelia of all the tested pathogens and produced coiling around the mycelium. (author)

  3. Potential of tara (Caesalpinia spinosa) gallotannins and hydrolysates as natural antibacterial compounds.

    Aguilar-Galvez, Ana; Noratto, Giuliana; Chambi, Flor; Debaste, Frédéric; Campos, David

    2014-08-01

    Gallotannins obtained from tara pod extracts (EE) and from the products of acid hydrolysis for 4 and 9h (HE-4 and HE-9) were characterised for their composition, antioxidant activity, antimicrobial activity (AA) and minimum inhibitory concentration (MIC). Results of AA and MIC showed that EE exerted the highest inhibitory activity against Staphylococcus aureus, followed by Pseudomonas fluorescens; and among these bacteria, the antibacterial potency was enhanced after EE hydrolysis only against S. aureus. The lowest minimum inhibitory concentration (MIC) value (0.13mg gallic acid equivalent (GAE)/ml) was exerted by HE-4 against S. aureus. These results indicate that tara gallotannins have the potential to inhibit pathogenic bacteria with potential application in foods as antimicrobials and their AA can be enhanced by acid hydrolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Effectiveness of some microorganisms in the limitation of grapevine cuttings infection by Phomopsis viticola Sacc.

    Ewa Król

    2013-12-01

    Full Text Available The possibilities of using antagonistic fungi and bacteria in the limitation of grapevine stems infection by Phomopsis viticola Sacc. were studied. Trichodema koningii Oud., T.viride Persoon ex S.F.,T.harzianum Rifai, Gliocladium catenulatum Gilman and Abbott, G.fimbriatum Gilman and Abbott, Bacillus sp., Pseudomonas fluorescens and five unidentified isolates of bacteria i.e.: 22a, 35, 40, 45, 66 were estimated. It was appeared what Trichoderma spp. were the most effective in protection of grapevine stems against the infection by P.viticola. After these antagonistic fungi were used on protected grapevine canes not numerous necrosis were observed and few cultures of pathogen were reisolated from them. Moreover, Trichoderma spp. survived on the grapevine stems during the period of experiment. The abilities of other microorganisms tested to protect grapevine cuttings against P.viticola infection and to exist on the stems were less than Trichoderma spp.

  5. A protein interaction map of the kalimantacin biosynthesis assembly line

    Birgit Uytterhoeven

    2016-11-01

    Full Text Available The antimicrobial secondary metabolite kalimantacin is produced by a hybrid polyketide/ non-ribosomal peptide system in Pseudomonas fluorescens BCCM_ID9359. In this study, the kalimantacin biosynthesis gene cluster is analyzed by yeast two-hybrid analysis, creating a protein-protein interaction map of the entire assembly line. In total, 28 potential interactions were identified, of which 13 could be confirmed further. These interactions include the dimerization of ketosynthase domains, a link between assembly line modules 9 and 10, and a specific interaction between the trans-acting enoyl reductase BatK and the carrier proteins of modules 8 and 10. These interactions reveal fundamental insight into the biosynthesis of secondary metabolites.This study is the first to reveal interactions in a complete biosynthetic pathway. Similar future studies could build a strong basis for engineering strategies in such clusters.

  6. High resistance of some oligotrophic bacteria to ionizing radiation

    Nikitin, D.I.; Tashtemirova, M.A.; Pitryuk, I.A.; Sorokin, V.V.; Oranskaya, M.S.; Nikitin, L.E.

    1994-01-01

    The resistance of seven cultures of eutrophic and oligotrophic bacteria to gamma radiation (at doses up to 360 Gy) was investigated. The bacteria under study were divided into three groups according to their survival ability after irradiation. Methylobacterium organophilum and open-quotes Pedodermatophilus halotoleransclose quotes (LD 50 = 270 Gy) were highly tolerant. By their tolerance, these organisms approached Deinococcus radiodurans. Aquatic ring-shaped (toroidal) bacteria Flectobacillus major and open-quotes Arcocella aquaticaclose quotes (LD 5 = 173 and 210 Gy, respectively) were moderately tolerant. Eutrophic Pseudomonas fluorescens and Escherichia coli (LD 50 = 43 and 38 Gy, respectively) were the most sensitive. X-ray microanalysis showed that in tolerant bacteria the intracellular content of potassium increased and the content of calcium decreased after irradiation. No changes in the element composition of the eutrophic bacterium E. coli were detected. Possible mechanisms of the resistance of oligotrophic bacteria to gamma radiation are discussed

  7. Biosynthesis of Cu, ZVI, and Ag nanoparticles using Dodonaea viscosa extract for antibacterial activity against human pathogens

    Kiruba Daniel, S. C. G.; Vinothini, G. [Anna University of Technology, Tiruchirappalli, Department of Nanoscience and Technology (India); Subramanian, N. [Anna University of Technology, Tiruchirappalli, Department of Pharmaceutical Technology (India); Nehru, K. [Anna University of Technology, Tiruchirappalli, Department of Chemistry (India); Sivakumar, M., E-mail: muthusiva@gmail.com [Anna University of Technology, Tiruchirappalli, Department of Nanoscience and Technology (India)

    2013-01-15

    Biosynthesis of copper, zero-valent iron (ZVI), and silver nanoparticles using leaf extract of Dodonaea viscosa has been investigated in this report. There are no additional surfactants/polymers used as capping or reducing agents for these syntheses. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, atomic force microscopy, and high-resolution transmission electron microscopy. The phase analysis was performed using selected area electron diffraction. The pH dependence of surface plasmon resonance and subsequent size variation has been determined. The synthesized nanoparticles showed spherical morphology and the average size of 29, 27, and 16 nm for Cu, ZVI, and Ag nanoparticles, respectively. Finally, biosynthesized Cu, ZVI, and Ag nanoparticles were tested against human pathogens viz. Gram-negative Escherichia coli, Klebsiella pneumonia, Pseudomonas fluorescens and Gram-positive Staphylococcus aureus and Bacillus subtilis, and showed good antimicrobial activity.

  8. Molecular basis and regulation of insect pathogenicity in plant-beneficial pseudomonads

    Kupferschmied, P.

    2015-01-01

    Les bactéries du genre Pseudomonas ont la capacité étonnante de s'adapter à différents habitats et d'y survivre, ce qui leur a permis de conquérir un large éventail de niches écologiques et d'interagir avec différents organismes hôte. Les espèces du groupe Pseudomonas fluorescens peuvent être facilement isolées de la rhizosphère et sont communément connues comme des Pseudomonas bénéfiques pour les plantes. Elles sont capables d'induire la résistance systémique des plantes, d'induire leur croi...

  9. Biosensor-based diagnostics of contaminated groundwater: assessment and remediation strategy

    Bhattacharyya, Jessica; Read, David; Amos, Sean; Dooley, Stephen; Killham, Kenneth; Paton, Graeme I.

    2005-01-01

    Shallow groundwater beneath a former airfield site in southern England has been heavily contaminated with a wide range of chlorinated solvents. The feasibility of using bacterial biosensors to complement chemical analysis and enable cost-effective, and focussed sampling has been assessed as part of a site evaluation programme. Five different biosensors, three metabolic (Vibrio fischeri, Pseudomonas fluorescens 10568 and Escherichia coli HB101) and two catabolic (Pseudomonas putida TVA8 and E. coli DH5α), were employed to identify areas where the availability and toxicity of pollutants is of most immediate environmental concern. The biosensors used showed different sensitivities to each other and to the groundwater samples tested. There was generally a good agreement with chemical analyses. The potential efficacy of remediation strategies was explored by coupling sample manipulation to biosensor tests. Manipulation involved sparging and charcoal treatment procedures to simulate remediative engineering solutions. Sparging was sufficient at most locations. - Luminescent bacteria complement chemical analysis and support remediation technology

  10. [Transformation of 2- and 4-cyanopyridines by free and immobilized cells of nitrile-hydrolyzing bacteria].

    Maksimova, Iu G; Vasil'ev, D M; Ovechkina, G V; Maksimov, A Iu; Demakov, V A

    2013-01-01

    The transformation dynamics of 2- and 4-cyanopyridines by cells suspended and adsorbed on inorganic carriers has been studied in the Rhodococcus ruber gt 1 strain possessing nitrile hydratase activity and the Pseudomonas fluorescens C2 strain containing nitrilase. It was shown that both nitrile hydratase and nitrilase activities of immobilized cells against 2-cyanopyridine were 1.5-4 times lower compared to 4-cyanopyridine and 1.6-2 times lower than the activities of free cells against 2-cyanpopyridine. The possibility of obtaining isonicotinic acid during the combined conversion of 4-cyanopyridine by a mixed suspension of R. ruber gt 1 cells with a high level of nitrile hydratase activity and R. erythropolis 11-2 cells with a pronounced activity of amidase has been shown. Immobilization of Rhodococcus cells on raw coal and Pseudomonas cells on china clay was shown to yield a heterogeneous biocatalyst for the efficient transformation of cyanopyridines into respective amides and carbonic acids.

  11. APPLICATIONS OF BIOTECHNOLOGY IN DEVELOPMENT OF BIOMATERIALS: NANOTECHNOLOGY AND BIOFILMS

    Brigmon, R.; Berry, T.; Narayan, R.

    2010-11-29

    Biotechnology is the application of biological techniques to develop new tools and products for medicine and industry. Due to various properties including chemical stability, biocompatibility, and specific activity, e.g. antimicrobial properties, many new and novel materials are being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. Many of these materials are less than 100 nanometers in size. Nanotechnology is the engineering discipline encompassing designing, producing, testing, and using structures and devices less than 100 nanometers. One of the challenges associated with biomaterials is microbial contamination that can lead to infections. In recent work we have examined the functionalization of nanoporous biomaterials and antimicrobial activities of nanocrystalline diamond materials. In vitro testing has revealed little antimicrobial activity against Pseudomonas fluorescens bacteria and associated biofilm formation that enhances recalcitrance to antimicrobial agents including disinfectants and antibiotics. Laser scanning confocal microscopy studies further demonstrated properties and characteristics of the material with regard to biofilm formation.

  12. Stochastic differential equations and a biological system

    Wang, Chunyan

    1994-01-01

    The purpose of this Ph.D. study is to explore the property of a growth process. The study includes solving and simulating of the growth process which is described in terms of stochastic differential equations. The identification of the growth and variability parameters of the process based...... on experimental data is considered. As an example, the growth of bacteria Pseudomonas fluorescens is taken. Due to the specific features of stochastic differential equations, namely that their solutions do not exist in the general sense, two new integrals - the Ito integral and the Stratonovich integral - have...... description. In order to identify the parameters, a Maximum likelihood estimation method is used together with a simplified truncated second order filter. Because of the continuity feature of the predictor equation, two numerical integration methods, called the Odeint and the Discretization method...

  13. Antibacterial and Antifungal Activities of Spices

    Liu, Qing; Meng, Xiao; Li, Ya; Zhao, Cai-Ning; Tang, Guo-Yi; Li, Hua-Bin

    2017-01-01

    Infectious diseases caused by pathogens and food poisoning caused by spoilage microorganisms are threatening human health all over the world. The efficacies of some antimicrobial agents, which are currently used to extend shelf-life and increase the safety of food products in food industry and to inhibit disease-causing microorganisms in medicine, have been weakened by microbial resistance. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Many spices—such as clove, oregano, thyme, cinnamon, and cumin—possessed significant antibacterial and antifungal activities against food spoilage bacteria like Bacillus subtilis and Pseudomonas fluorescens, pathogens like Staphylococcus aureus and Vibrio parahaemolyticus, harmful fungi like Aspergillus flavus, even antibiotic resistant microorganisms such as methicillin resistant Staphylococcus aureus. Therefore, spices have a great potential to be developed as new and safe antimicrobial agents. This review summarizes scientific studies on the antibacterial and antifungal activities of several spices and their derivatives. PMID:28621716

  14. Synthèse énantiosélective du Monate de méthyle C et réaction aldol organocatalysée d'aldéhydes a,b-insaturés : application à la synthèse de dérivés de la Goniothalamine

    van Innis, Livia

    2007-01-01

    Le Monate de méthyle C est produit par Pseudomonas Fluorescens et possède des propriétés antibactériennes intéressantes envers les bactéries Gram-positives. Afin de permettre un accès efficace au noyau pyrannique du (+)-Monate de méthyle C, une méthodologie impliquant une séquence ène-IMSC a été mise au point. L'introduction de la chaîne latérale axiale a été effectuée par une réaction d'allylation asymétrique suivie d'une métathèse croisée sélective. Enfin, une réduction de la cétone intermé...

  15. 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

    Pedersen, Annette; Nybroe, Ole; Winding, Anne

    2009-01-01

    How bacterial feeding fauna affects colonization and survival of bacteria in soil is not well understood, which constrains the applicability of bacterial inoculants in agriculture. This study aimed to unravel how food quality of bacteria and bacterial feeders with different feeding habits (the......50090 or one of two biocontrol strains P. fluorescens CHA0 or Pseudomonas sp. DSS73) or combinations of two bacterial strains. DSM50090 is a suitable food bacterium, DSS73 is of intermediate food quality, and CHA0 is inedible to the bacterial feeders. Bacterial and protozoan cell numbers were measured...... predation pressure. Hence, the results suggested that the outcome of competition among bacteria depended on their ability to cope with the prevailing bacterial predator....

  16. Role of trophallaxis in the dispersal of radioactive I131 and of bacterial infections in the termite, Bifiditermes beesoni

    Khan, K.I.; Jafri, R.H.; Ahmad, M.

    1981-01-01

    Dispersal and localisation of radioactive iodine (I 131 ) through trophallaxis was studied in various organs of healthy or bacteria-infected pseudergates of Bifiditermes beesoni. The breakdown of the defence system by bacterial pathogens was also studied by means of I 131 . Individual groups of pseudergates of B. beesoni were infected by various bacterial pathogens, i.e. Thuricide-HP (commercial preparation of Bacillus thuringiensis), B. thuringiensis 11-toumanoffi, B. thuringiensis serotype 3a, 3b, Pseudomonas fluorescens and Serratia marcescens, respectively. Healthy pseudergates retained more radioactivity in their guts and less in their exoskeletons. However, bacteria-infected 'donor' and 'recipient' pseudergates and soldiers retained less radioactivity in their guts and more in their exoskeletons. The flow of radioactivity from gut towards exoskeleton or other parts of B. beesoni pseudergates occurred after destruction and breakdown of the inestinal defence system of the host. (orig.) [de

  17. Statistical analysis of joint toxicity in biological growth experiments

    Spliid, Henrik; Tørslev, J.

    1994-01-01

    The authors formulate a model for the analysis of designed biological growth experiments where a mixture of toxicants is applied to biological target organisms. The purpose of such experiments is to assess the toxicity of the mixture in comparison with the toxicity observed when the toxicants are...... is applied on data from an experiment where inhibition of the growth of the bacteria Pseudomonas fluorescens caused by different mixtures of pentachlorophenol and aniline was studied.......The authors formulate a model for the analysis of designed biological growth experiments where a mixture of toxicants is applied to biological target organisms. The purpose of such experiments is to assess the toxicity of the mixture in comparison with the toxicity observed when the toxicants...

  18. [Nah-plasmids of IncP-9 group from natural strains of Pseudomonas].

    Levchuk, A A; Bulyga, I M; Izmalkova, T Iu; Sevast'ianovich, Ia R; Kosheleva, I A; Thomas, C M; Titok, M A

    2006-01-01

    Use of polymerase chain reaction helped to establish that the most frequent among naphthalene utilizing bacteria, isolated on the territory of Belarus, are Nah-plasmids of IncP-9 incompatibility group and those with indefinite systematic belonging. With the help of classical test of incompatibility, restriction and sequence analyses three new subgroups within the IncP-9 group were discovered (zeta, eta and IncP-9-like replicons). Conducting of restriction analysis for amplification products of nahG and nahAc genes allowed us to reveal, in addition to known sequences of stated determinants, two new types of nahG gene. Restriction analysis performed on amplification products of 16S RNA genes (ARDRA method) showed that native hosts of Nah-plasmids of IncP-9 group are not only fluorescent bacteria from genus Pseudomonas (P. fluorescens, P. putida, P. aeruginosa, P. species), but also non-fluorescent bacteria with indefinite specific belonging.

  19. The effect of high hydrostatic pressure on black truffle (tuber melanosporum) flavour compounds

    Verret, C; Ballestra, P; Cruz, C; Moueffak, A H E; Pardon, P; Largeteau, A

    2008-01-01

    The effects of high hydrostatic pressure (HHP), at 4 0 C or -18 0 C, on black truffle flavour compounds, alteration enzymes (lipoxigenase (LOX), peroxidase (POD) and polyphenoloxidase (PPO)) and microbiological qualities were evaluated. The choosen analytes for this study are six alcohols, three aldehydes, one ketone and on sulfur component. The highest flavour stability was observed when samples were pressurized at 300 MPa / 4 0 C / 10 min. All the treatments induced a drastic decrease of LOX activity and a slight decrease of POD activity. On the other hand, the PPO was not inactivated by pressurization at sub-zero (200 MPa / -18 0 C / 10 min) and was strongly increased after the 300 MPa / 4 0 C / 10 min treatment. Pressurization at 300 and 550 MPa lead to an almost complete Pseudomonas fluorescens reduction (6 and 6.5 log destruction, respectively) whereas pressurization at -18 0 C (200MPa) allowed to obtain only 3 log reduction

  20. Selection on non-social traits limits the invasion of social cheats

    Morgan, Andrew D; Quigley, Benjamin J Z; Brown, Sam P; Buckling, Angus

    2012-01-01

    While the conditions that favour the maintenance of cooperation have been extensively investigated, the significance of non-social selection pressures on social behaviours has received little attention. In the absence of non-social selection pressures, patches of cooperators are vulnerable to invasion by cheats. However, we show both theoretically, and experimentally with the bacterium Pseudomonas fluorescens, that cheats may be unable to invade patches of cooperators under strong non-social selection (both a novel abiotic environment and to a lesser extent, the presence of a virulent parasite). This is because beneficial mutations are most likely to arise in the numerically dominant cooperator population. Given the ubiquity of novel selection pressures on microbes, these results may help to explain why cooperation is the norm in natural populations of microbes. PMID:22639835

  1. Nitrogen-fixing and uricolytic bacteria associated with the gut of Dendroctonus rhizophagus and Dendroctonus valens (Curculionidae: Scolytinae).

    Morales-Jiménez, Jesús; Vera-Ponce de León, Arturo; García-Domínguez, Aidé; Martínez-Romero, Esperanza; Zúñiga, Gerardo; Hernández-Rodríguez, César

    2013-07-01

    The bark beetles of the genus Dendroctonus feed on phloem that is a nitrogen-limited source. Nitrogen fixation and nitrogen recycling may compensate or alleviate such a limitation, and beetle-associated bacteria capable of such processes were identified. Raoultella terrigena, a diazotrophic bacteria present in the gut of Dendroctonus rhizophagus and D. valens, exhibited high acetylene reduction activity in vitro with different carbon sources, and its nifH and nifD genes were sequenced. Bacteria able to recycle uric acid were Pseudomonas fluorescens DVL3A that used it as carbon and nitrogen source, Serratia proteomaculans 2A CDF and Rahnella aquatilis 6-DR that used uric acid as sole nitrogen source. Also, this is the first report about the uric acid content in whole eggs, larvae, and adults (male and female) samples of the red turpentine beetle (Dendroctonus valens). Our results suggest that the gut bacteria of these bark beetles could contribute to insect N balance.

  2. Chromium Resistant Bacteria: Impact on Plant Growth in Soil Microcosm

    Sayel Hanane

    2014-07-01

    Full Text Available Three chromium resistant bacterial strains, Pseudomonas fluorescens PF28, Enterobacter amnigenus EA31 and Enterococcus gallinarum S34 isolated from tannery waste contaminated soil were used in this study. All strains could resist a high concentration of K2Cr2O7 that is up to 300 mg/L. The effect of these strains on clover plants (Trifolium campestre in the presence of two chromium salts CrCl3 and K2Cr2O7 was studied in soil microcosm. Application of chromium salts adversely affected seed germination, root and shoot length. Bacterial inoculation improved the growth parameters under chromate stress when compared with non inoculated respective controls. There was observed more than 50% reduction of Cr(VI in inoculated soil microcosms, as compared to the uninoculated soil under the same conditions. The results obtained in this study are significant for the bioremediation of chromate pollution.

  3. The influence of radiation on bacterial cells and their proteolytic properties

    Szulc, M.; Stefaniakowa, A.; Stanczak, B.; Peconek, J.

    1980-01-01

    The suspension of bacterial cells and their spores were exposed to X rays in the environment with and without protein. The doses of radiation ranged from 1 to 100 Gy and in case of spores of B. subtilis from 50 to 1000 Gy. It was found that irradiation to Proteus vulgaris, Pseudomonas fluorescens and Ps. aeruginosa caused an inconsiderable decrease of proteolytic properties of the generation originated from irradiated bacteria. Irradiation of B. subtilis spores did not influence the proteolytic activity of bacterial cells derived from the exposed spores. The degree of wasting away of bacteria exposed to the same radiation was higher than the rate of proteolytic properties decrease. The presence of protein in the surroundings had no influence on proteolytic characteristics of new generations. (author)

  4. [Determination of minimal concentrations of biocorrosion inhibitors by a bioluminescence method in relation to bacteria, participating in biocorrosion].

    Efremenko, E N; Azizov, R E; Makhlis, T A; Abbasov, V M; Varfolomeev, S D

    2005-01-01

    By using a bioluminescence ATP assay, we have determined the minimal concentrations of some biocorrosion inhibitors (Katon, Khazar, VFIKS-82, Nitro-1, Kaspii-2, and Kaspii-4) suppressing most common microbial corrosion agents: Desulfovibrio desulfuricans, Desulfovibrio vulgaris, Pseudomonas putida, Pseudomonas fluorescens, and Acidithiobacillus ferrooxidans. The cell titers determined by the bioluminescence method, including not only dividing cells but also their dormant living counterparts, are two- to sixfold greater than the values determined microbiologically. It is shown that the bioluminescence method can be applied to determination of cell titers in samples of oil-field waters in the presence of iron ions (up to 260 mM) and iron sulfide (to 186 mg/l) and in the absence or presence of biocidal corrosion inhibitors.

  5. THE ASSESSMENT OF MICROBIOLOGICAL INDOOR AIR QUALITY IN BAKERIES

    Elżbieta Wołejko

    2016-05-01

    Full Text Available The aim of this study was to assess microbiological indoor air quality of selected bakeries located in the region of Podlasie. The microbiological studies were conducted in autumn in 2014 in three selected bakeries. Microbiological air counts were measured by impaction using an air sampler MAS-100 NT. The microbiological air studies, comprised the determination of the total number of psychrophilic and mesophilic bacteria, namely indicator bacteria such as: bacteria of the species Pseudomonas fluorescens, mannitol-positive and mannitol-negative Staphylococc, the total number of bacteria from the Enterobacteriaceae family and fungi found in atmospheric air. The results of the study of indoor air polluted with the analyzed groups of microorganisms differed depending on the type of test air and the location of the manufacturing plant. In the plants, the concentration of mesophilic bacteria and mannitol–positive and mannitol-negative Staphylococcus exceeded the limit values of unpolluted air, according to the Polish Standard recommendations.

  6. Influence of the nano-micro structure of the surface on bacterial adhesion

    Carolina Díaz

    2007-03-01

    Full Text Available Biomaterials failures are frequently associated to the formation of bacterial biofilms on the surface. The aim of this work is to study the adhesion of non motile bacteria streptococci consortium and motile Pseudomonas fluorescens. Substrates with micro and nanopatterned topography were used. The influence of surface characteristics on bacterial adhesion was investigated using optical and epifluorescence microscopy, scanning electron microscopy (SEM and atomic force microscopy (AFM. Results showed an important influence of the substratum nature. On microrough surfaces, initial bacterial adhesion was less significant than on smooth surfaces. In contrast, nanopatterned samples showed more bacterial attachment than the smooth control. It was also noted a remarkable difference in morphology, orientation and distribution of bacteria between the smooth and the nanostructured substrate. The results show the important effect of substratum nature and topography on bacterial adhesion which depended on the relation between roughness characteristics dimensions and bacterial size.

  7. Effect of flow rate on the enhancement of particulate fouling in the presence of a developing biofilm

    Burton, G.R.; Blimkie, M.E.; McGarvey, G.B.; Turner, C.W.

    2001-03-01

    The rate of magnetite deposition on a heated test section was investigated using radiotracing methods as a function of flow rate in the absence and presence of a growing biofilm of Pseudomonas fluorescens. The flow rate was adjusted to span Reynolds numbers from 2200 to 9600. For all flow rates, there was an increase in the rate of magnetite deposition in the presence of the growing biofilm. In addition, the rate of deposition was 10 times greater for a Reynolds number of 6400 than that observed at lower and higher flow rates with Reynolds numbers of 2200 and 9600, respectively. The results are discussed in relation to the shear stress on the biofilm and to the rate of transport of nutrients. (author)

  8. Microbial degradation of cyanide from gold metallurgical plants utilizing P. fluorecens

    Restrepo, Oscar Jaime; Montoya, Carlos Arturo; Munoz, Nury Alexandra

    2005-01-01

    Sodium cyanide is traditionally used in chemical metallurgy to obtain precious metals (gold and silver). Cyanide produces damages because of its toxicity and breath cell inhibition. Here we try a biotechnological process to degrade cyanide with P. fluorescens obtained by cyanide heap leaching process in gold metallurgy in Segovia, Colombia. In Colombia cyanide heap-leaching process in gold metallurgy is not controlled and cyanide is used excessively. It means that great quantities of sodium cyanide are lost in sands and in wastewater. Toxicity tests made by D. pulex show less than 54 ppm of cyanide is enough to kill them. Traditional treatments to cyanide degradation are useful and normal but they are expensive. Microbiological process eliminates cyanide successfully and cheap

  9. Biosynthesis of Cu, ZVI, and Ag nanoparticles using Dodonaea viscosa extract for antibacterial activity against human pathogens

    Kiruba Daniel, S. C. G.; Vinothini, G.; Subramanian, N.; Nehru, K.; Sivakumar, M.

    2013-01-01

    Biosynthesis of copper, zero-valent iron (ZVI), and silver nanoparticles using leaf extract of Dodonaea viscosa has been investigated in this report. There are no additional surfactants/polymers used as capping or reducing agents for these syntheses. The synthesized nanoparticles were characterized by UV–Vis spectroscopy, X-ray diffraction, atomic force microscopy, and high-resolution transmission electron microscopy. The phase analysis was performed using selected area electron diffraction. The pH dependence of surface plasmon resonance and subsequent size variation has been determined. The synthesized nanoparticles showed spherical morphology and the average size of 29, 27, and 16 nm for Cu, ZVI, and Ag nanoparticles, respectively. Finally, biosynthesized Cu, ZVI, and Ag nanoparticles were tested against human pathogens viz. Gram-negative Escherichia coli, Klebsiella pneumonia, Pseudomonas fluorescens and Gram-positive Staphylococcus aureus and Bacillus subtilis, and showed good antimicrobial activity.

  10. IMPACT OF OXYGEN CONCENTRATION ON ZEBRA MUSSEL MORTALITY

    Daniel P. Molloy

    2003-01-27

    These tests have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels in environments having dissolved oxygen (DO) concentrations ranging from very low to very high. The results suggest that the highest mussel kill can be achieved in moderately to highly aerated environments, while kill may be 0-20% lower under conditions of very low oxygen. For example, under highly oxygenated conditions 97% kill was achieved while conditions having low DO produced 79% mussel kill. Service water measured in a local power plant indicated that DO concentrations were in the range of 8-9 ppm (e.g., highly aerated) within their pipes. Therefore, we will not expect to see decreases in the efficacy of CL0145A treatments due to oxygen levels within such power plant pipes.

  11. IMPACT OF FIVE TREATMENT FACTORS ON MUSSEL MORTALITY

    Daniel P. Molloy

    2003-12-08

    Under this USDOE-NETL contract, the bacterium Pseudomonas fluorescens is being developed as a biocontrol agent for zebra mussels. The specific purpose of the contract is to identify factors that affect mussel kill. Test results reported herein indicate that mussel kill should not be affected by: (1) air bubbles being carried by currents through power plant pipes; (2) pipe orientation (e.g., vertical or horizontal); (3) whether the bacterial cell concentration during a treatment is constant or slightly varying; (4) whether a treatment is between 3 hr and 12 hr in duration, given that the total quantity of bacteria being applied to the pipe is a constant; and (5) whether the water temperature is between 13 C and 23 C.

  12. IMPACT OF OXYGEN CONCENTRATION ON ZEBRA MUSSEL MORTALITY

    Molloy, Daniel P.

    2003-01-01

    These tests have indicated that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels in environments having dissolved oxygen (DO) concentrations ranging from very low to very high. The results suggest that the highest mussel kill can be achieved in moderately to highly aerated environments, while kill may be 0-20% lower under conditions of very low oxygen. For example, under highly oxygenated conditions 97% kill was achieved while conditions having low DO produced 79% mussel kill. Service water measured in a local power plant indicated that DO concentrations were in the range of 8-9 ppm (e.g., highly aerated) within their pipes. Therefore, we will not expect to see decreases in the efficacy of CL0145A treatments due to oxygen levels within such power plant pipes

  13. Chitosan matrices modified with carbon nanotubes for use in mediated microbial biosensing

    Demirkol, D.O.; Timur, S.

    2011-01-01

    We describe a microbial sensor based on Pseudomonas fluorescens cells that was prepared by modifying graphite electrodes with chitosan and carbon nanotubes. Chronoamperometry was performed at +0.3 V in the presence of hexacyanoferrate as a mediator and revealed a good response to glucose which is linear in the 1.0 to 5.0 mM concentration range. Linearity was defined by the equation of y = 102.120x-13.279 (R2 = 0.998) (y shows current density as nA. cm-2 and x shows glucose concentration in mM). The effect of the CNTs on the response was compared to that of electrodes made without CNTs. (author)

  14. Electromechanical and elastic probing of bacteria in a cell culture medium

    Thompson, G L; Reukov, V V; Vertegel, A A; Nikiforov, M P; Jesse, S; Kalinin, S V

    2012-01-01

    Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of bacteria of different types in pure water. Here, the BEPFM method is performed for the first time on physiologically relevant electrolyte media, such as Dulbecco’s phosphate-buffered saline (DPBS) and Dulbecco’s modified Eagle’s medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria in DPBS are demonstrated. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media. (paper)

  15. The study of the antimicrobial activity of colloidal solutions of silver nanoparticles prepared using food stabilizers.

    Balandin, G V; Suvorov, O A; Shaburova, L N; Podkopaev, D O; Frolova, Yu V; Ermolaeva, G A

    2015-06-01

    The bactericidal effect of colloidal solutions of silver nanoparticles based on food stabilizers, gum arabic and chitosan, against bacterial cultures of microorganisms in food production is described. The antibacterial activity of nanotechnology products containing different amounts of stabilizing additives when applied to solid pH-neutral substrates is studied. For its evaluation a method making it possible to take into account the capability of nanoparticles to diffuse in solid media was applied. Minimal inhibitory concentrations of nanoparticles used against Erwinia herbicola, Pseudomonas fluorescens, Bacillus subtilis, Sarcina flava were found. A suggestion was made concerning the influence of the spatial structure of bacteria on the antibacterial activity of colloidal solutions of silver nanoparticles. The data concerning the antibacterial activity and minimal inhibiting concentrations of nanoparticles may be used for development of products suppressing activity of microorganisms hazardous for food production.

  16. Physico-chemical, spectroscopical and thermal characterization of bio diesel obtained by enzymatic route as a tool to select the most efficient immobilized lipase

    Silva, G.A.M.; Ros, P.C.M. da; Souza, L.T.A.; Costa, A.P.O.; Castro, H.F. de

    2012-01-01

    Two microbial lipases from Burkholderia cepacia and Pseudomonas fluorescens were evaluated as catalysts for the enzymatic transesterification of beef tallow with ethanol and the most efficient lipase source was selected by taking into account the properties of the product to be used as fuel. Both lipases were immobilized on an epoxy silica-polyvinyl alcohol composite by covalent immobilization and used to perform the reactions under the following operational conditions: beef tallow-to-ethanol molar ratio of 1:9, 45 degree C and 400 units of enzymatic activity per gram of fat. Products, characterized using Fourier Transform Infrared spectroscopy (FTIR), viscosimetry, thermogravimetry and 1 H NMR spectroscopy, suggested that the bio diesel sample obtained in the reaction catalyzed by Burkholderia cepacia lipase has the best set of properties for fuel usage. (author)

  17. Physico-chemical, spectroscopical and thermal characterization of bio diesel obtained by enzymatic route as a tool to select the most efficient immobilized lipase

    Silva, G.A.M.; Ros, P.C.M. da; Souza, L.T.A.; Costa, A.P.O.; Castro, H.F. de, E-mail: heizir@dequi.eel.usp.br [Engineering School of Lorena. University of Sao Paulo (EEL/USP), Lorena, SP (Brazil)

    2012-01-15

    Two microbial lipases from Burkholderia cepacia and Pseudomonas fluorescens were evaluated as catalysts for the enzymatic transesterification of beef tallow with ethanol and the most efficient lipase source was selected by taking into account the properties of the product to be used as fuel. Both lipases were immobilized on an epoxy silica-polyvinyl alcohol composite by covalent immobilization and used to perform the reactions under the following operational conditions: beef tallow-to-ethanol molar ratio of 1:9, 45 degree C and 400 units of enzymatic activity per gram of fat. Products, characterized using Fourier Transform Infrared spectroscopy (FTIR), viscosimetry, thermogravimetry and {sup 1}H NMR spectroscopy, suggested that the bio diesel sample obtained in the reaction catalyzed by Burkholderia cepacia lipase has the best set of properties for fuel usage. (author)

  18. Use of ceragenins to create novel biofouling resistant water-treatment membranes.

    Hibbs, Michael R.; Altman, Susan Jeanne; Feng, Yanshu (Brigham Young University, Provo, UT); Savage, Paul B. (Brigham Young University, Provo, UT); Pollard, Jacob (Brigham Young University, Provo, UT); Sanchez, Andres L. (LMATA, Albuquerque, NM); Fellows, Benjamin D.; Jones, Howland D. T.; McGrath, Lucas K. (LMATA, Albuquerque, NM)

    2008-12-01

    Scoping studies have demonstrated that ceragenins, when linked to water-treatment membranes have the potential to create biofouling resistant water-treatment membranes. Ceragenins are synthetically produced molecules that mimic antimicrobial peptides. Evidence includes measurements of CSA-13 prohibiting the growth of and killing planktonic Pseudomonas fluorescens. In addition, imaging of biofilms that were in contact of a ceragenin showed more dead cells relative to live cells than in a biofilm that had not been treated with a ceragenin. This work has demonstrated that ceragenins can be attached to polyamide reverse osmosis (RO) membranes, though work needs to improve the uniformity of the attachment. Finally, methods have been developed to use hyperspectral imaging with multivariate curve resolution to view ceragenins attached to the RO membrane. Future work will be conducted to better attach the ceragenin to the RO membranes and more completely test the biocidal effectiveness of the ceragenins on the membranes.

  19. Effect of two different germplasm of Mucuna pruriens seed extracts against some fish pathogens

    M. Marimuthu M

    2015-07-01

    Full Text Available To investigate the two different germplasm of Mucuna seeds were collected from agro geographical regions was evaluated for its antibacterial activities. Antibacterial activity of the seed extracts was studied against the fish pathogens of Aeromonas hydrophila, Pseudomonas fluorescens, Vibrio cholera and Klebsiella pneumonia using agar well diffusion method. Results showed that methanol and ethanol extracts showed more potent antibacterial activity than other solvent extracts. The results were expressed as mean ± SD. The results obtained in the study shows that velvet bean black seed extract has more antibacterial activity against fish pathogens. The antibacterial activity of all the Mucuna seed extracts are comparable ad their potential as alternative in the treatment of infectious by these microorganisms was present in the fish. Susceptibility testing is conducted on isolates using drug selected on the basis of their importance to human medicine and use I fish production.

  20. Effectiveness of beneficial plant-microbe interactions under hypobaric and hypoxic conditions in an advanced life support system

    MacIntyre, Olathe; Stasiak, Michael; Cottenie, Karl; Trevors, Jack; Dixon, Mike

    An assembled microbial community in the hydroponics solution of an advanced life support system may improve plant performance and productivity in three ways: (1) exclusion of plant pathogens from the initial community, (2) resistance to infection, and (3) plant-growth promotion. However, the plant production area is likely to have a hypobaric (low pressure) and hypoxic (low oxygen) atmosphere to reduce structural mass and atmosphere leakage, and these conditions may alter plant-microbe interactions. Plant performance and productivity of radish (Raphanus sativus L. cv. Cherry Bomb II) grown under hypobaric and hypoxic conditions were investigated at the University of Guelph's Controlled Environment Systems Research Facility. Changes in the microbial communities that routinely colonized the re-circulated nutrient solution, roots, and leaves of radishes in these experiments were quantified in terms of similarity in community composition, abundance of bacteria, and community diversity before and after exposure to hypobaric and hypoxic conditions relative to communities maintained at ambient growth conditions. The microbial succession was affected by extreme hypoxia (2 kPa oxygen partial pressure) while hypobaria as low as 10 kPa total pressure had little effect on microbial ecology. There were no correlations found between the physiological profile of these unintentional microbial communities and radish growth. The effects of hypobaric and hypoxic conditions on specific plant-microbe interactions need to be determined before beneficial gnotobiotic communities can be developed for use in space. The bacterial strains Tal 629 of Bradyrhizobium japonicum and WCS417 of Pseudomonas fluorescens, and the plant pathogen Fusarium oxysporum f. sp. raphani will be used in future experiments. B. japonicum Tal 629 promotes radish growth in hydroponics systems and P. fluorescens WCS417 induces systemic resistance to fusarium wilt (F. oxysporum f. sp. raphani) in radish under ambient

  1. Bactericidal efficacy of elevated pH on fish pathogenic and environmental bacteria

    Starliper, Clifford E.; Watten, Barnaby J.

    2013-01-01

    Ship ballast water is a recognized medium for transfer and introductions of nonindigenous species. There is a need for new ballast water treatment methods that effectively and safely eliminate or greatly minimize movements of these species. The present study employed laboratory methods to evaluate the bactericidal efficacy of increased pH (pH 10.0–12.0) for exposure durations of up to 72 h to kill a variety of Gram-negative and Gram-positive bacteria including fish pathogens (Aeromonas spp., Yersinia ruckeri, Edwardsiella ictaluri, Serratia liquefaciens, Carnobacterium sp.), other common aquatic-inhabitant bacteria (Serratia marcescens, Pseudomonas fluorescens, Staphylococcus sp., Bacillus sp.) and indicators listed in International Maritime Organization D2 Standards; namely, Vibrio cholera (an environmental isolate from fish), Escherichia coli and Enterococcus faecalis. Volumes of 5 N NaOH were added to tryptic soy broth to obtain desired pH adjustments. Viable cells were determined after 0, 4, 12, 24, 48, and 72 h. Initial (0 h) cell numbers ranged from 3.40 × 104 cfu/mL for Bacillus sp. to 2.44 × 107 cfu/mL for E. faecalis. The effective endpoints of pH and treatment duration necessary to realize 100% bactericidal effect varied; however, all bacteria tested were killed within 72 h at pH 12.0 or lower. The lowest parameters examined, 4 h at pH 10.0, were bactericidal to V. cholera, E. ictaluri, three of four isolates of E. coli, and (three of four) Aeromonas salmonicida subsp. salmonicida. Bactericidal effect was attained at pH 10.0 within 12 h for the other A. salmonicida subsp. salmonicida, and within 24 h for P. fluorescens, and the remaining E. coli.

  2. Biotransformation of plutonium complexed with citric acid

    Francis, A.J.; Dodge, C.J.; Gillow, J.B.

    2006-01-01

    The presence of organic ligands in radioactive wastes is a major concern because of their potential for increasing the transport of radionuclides from disposal sites. Biotransformation of radionuclides complexed with organic ligands should precipitate the radionuclides and retard their migration. We investigated the biotransformation of Pu(IV) (10 -8 to 10 -5 M), by Pseudomonas fluorescens in the presence of excess citric acid. Analysis of 242 Pu-citrate by electrospray ionization-mass spectrometry (ESI-MS) indicated the presence of biligand Pu-cit 2 as the predominant complex. XANES and EXAFS analyses showed that Pu was in the +4 oxidation state and associated with citric acid as a mononuclear complex. Citric acid was metabolized by P. fluorescens at a rate of 4.9 μM/h, but in the presence of 10 -8 and 10 -6 M Pu, this rate decreased to 4.0 and 3.8 μM/h, respectively. An increase in the ionic strength of the medium from 0.18 M to 0.9 M lowered citrate metabolism by ∝ 65%. Pu added to the growth medium in the absence of bacteria remained as Pu(IV) in solution as a complex with citric acid. However, solvent extraction by thenoyltrifluoroacetone (TTA) and microfiltration (0.03 μm) of the medium containing bacteria after citrate biodegradation revealed the presence of polymeric Pu. The extent of formation of the Pu polymer depended on the Pu: citrate ratio, the extent of citrate metabolism, and the ionic strength of the medium. (orig.)

  3. Combination of selected enzymes with cetyltrimethylammonium bromide in biofilm inactivation, removal and regrowth

    Araujo, Paula Alexandra Da Silva; Machado, Idalina; Meireles, Ana; Leiknes, TorOve; Mergulhã o, Filipe; Melo, Luí s F.; Simõ es, Manuel

    2017-01-01

    Enzymes are considered an innovative and environmentally friendly approach for biofilm control due to their lytic and dispersal activities. In this study, four enzymes (β-glucanase, α-amylase, lipase and protease) were tested separately and in combination with the quaternary ammonium compound cetyltrimethylammonium bromide (CTAB) to control flow-generated biofilms of Pseudomonas fluorescens. The four enzymes caused modest reduction of biofilm colony forming units (CFU). Protease, β-glucanase and α-amylase also caused modest biofilm removal. CTAB combined with either β-glucanase or α-amylase increased biofilm removal. Its combination with either β-glucanase or protease increased CFU reduction. However, CTAB−protease combination was antagonist in biofilm removal. Long-term effects in biofilm mass reduction were observed after protease exposure. In contrast, biofilms treated with β-glucanase were able to regrowth significantly after exposure. Moreover, short-term respirometry tests with planktonic cells were performed to understand the effects of enzymes and their combination with CTAB on P. fluorescens viability. Protease and lipase demonstrated antimicrobial action, while α-amylase increased bacterial metabolic activity. The combination of CTAB with either protease or α-amylase was antagonistic, decreasing the antimicrobial action of CTAB. The overall results demonstrate a modest effect of the selected enzymes in biofilm control, either when applied alone or each one in combination with CTAB. Total biofilm removal or CFU reduction was not achieved and, in some cases, the use of enzymes antagonized the effects of CTAB. The results also propose that complementary tests, to characterize biofilm integrity and microbial viability, are required when someone is trying to assess the role of novel biocide - enzyme mixtures for effective biofilm control.

  4. The influence of biosurfactant adsorption on the physicochemical behaviour of carbon steel surfaces using contact angle measurements and X-ray photoelectron spectroscopy

    Shubina, V., E-mail: varvara.shubina2014@gmail.com [LUNAM Université, IFSTTAR, MAST, SMC, F-44340 Bouguenais (France); Gaillet, L. [LUNAM Université, IFSTTAR, MAST, SMC, F-44340 Bouguenais (France); Ababou-Girard, S. [Institut de Physique de Rennes, Département Matériaux et Nanosciences, UMR 6251 CNRS, Université Rennes 1, 35000 Rennes-Cedex (France); Gaudefroy, V. [LUNAM Université, IFSTTAR, MAST, SMC, F-44340 Bouguenais (France); Chaussadent, T.; Farças, F. [Université Paris-Est, IFSTTAR, MAST, CPDM, F-77447 Marne-la-Vallée (France); Meylheuc, T. [INRA, UMR1319 Micalis, F-78352 Jouy-en-Josas (France); AgroParisTech, UMR Micalis, F-78352 Jouy-en-Josas (France); Dagbert, C. [2 Chemin de la Grand’côte, 36270 Éguzon-Chantôme (France); Creus, J. [LaSIE, UMR7356, Université de La Rochelle, Pôle Sciences et Technologie, Bâtiment Marie Curie, Avenue Michel Crépeau, 17000 La Rochelle (France)

    2015-10-01

    Highlights: • Surface modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells were investigated using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). • CAM allowed to establish an increase of electron-donating properties of steel surface due to the biosurfactant adsorption. • XPS demonstrated that biosurfactant molecules change the stoichiometry of mixted-oxide layer and the new outer layer mostly composed of magnetite. • Thickness and density of adsorbed biosurfactants layers were highlighted using a semiquantitative approach for 3 different concentrations of biomolecules. - Abstract: We investigated modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). After conditioning carbon steel in solutions with three different concentrations of biosurfactant molecules: 0.05, 0.3 and 1 g L{sup −1}, the average thickness of the biosurfactant layer on the carbon steel specimens was 7.9 ± 0.3, 12.1 ± 0.5 and 16.4 ± 0.7 Å, respectively. The biosurfactants changed the composition of both the Fe{sup 2+} and Fe{sup 3+} mixed-oxide layer and the outer layer, mostly composed of Fe{sup 3+} associated with magnetite. Contact angle measurements indicate decreased hydrophobic properties after the carbon steel was modified by biosurfactant. It was shown that the carbon steel surface free energy depends on the biosurfactant concentration, due to an acquisition of strong electron-donating properties.

  5. The influence of biosurfactant adsorption on the physicochemical behaviour of carbon steel surfaces using contact angle measurements and X-ray photoelectron spectroscopy

    Shubina, V.; Gaillet, L.; Ababou-Girard, S.; Gaudefroy, V.; Chaussadent, T.; Farças, F.; Meylheuc, T.; Dagbert, C.; Creus, J.

    2015-01-01

    Highlights: • Surface modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells were investigated using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). • CAM allowed to establish an increase of electron-donating properties of steel surface due to the biosurfactant adsorption. • XPS demonstrated that biosurfactant molecules change the stoichiometry of mixted-oxide layer and the new outer layer mostly composed of magnetite. • Thickness and density of adsorbed biosurfactants layers were highlighted using a semiquantitative approach for 3 different concentrations of biomolecules. - Abstract: We investigated modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). After conditioning carbon steel in solutions with three different concentrations of biosurfactant molecules: 0.05, 0.3 and 1 g L −1 , the average thickness of the biosurfactant layer on the carbon steel specimens was 7.9 ± 0.3, 12.1 ± 0.5 and 16.4 ± 0.7 Å, respectively. The biosurfactants changed the composition of both the Fe 2+ and Fe 3+ mixed-oxide layer and the outer layer, mostly composed of Fe 3+ associated with magnetite. Contact angle measurements indicate decreased hydrophobic properties after the carbon steel was modified by biosurfactant. It was shown that the carbon steel surface free energy depends on the biosurfactant concentration, due to an acquisition of strong electron-donating properties

  6. Desempenho de diferentes lipases imobilizadas na síntese de biodiesel de óleo de palma = Performance of different immobilized lipases in palm oil biodiesel synthesis

    Grazielle dos Santos Silva

    2011-04-01

    Full Text Available O presente trabalho teve como objetivo determinar as condicoes otimizadas da sintese enzimatica de biodiesel, a partir do oleo de palma e etanol, empregando diferentes lipases imobilizadas (lipase de Pseudomonas fluorescens imobilizada em SiO2-PVA e lipase de Candida antartica imobilizada em resina acrilica - Novozym„µ 435 em meio isento de solvente. Uma matriz de planejamento fatorial foi utilizada para avaliar a influencia da temperatura (42 ¡V 58„aC e a razao molar entre etanol e oleo de palma (6:1 ¡V 18:1 no rendimento detransesterificacao alcancado para cada preparacao de lipase. Os efeitos principais foram ajustados por analise de regressao multipla a modelos lineares e o rendimento maximo foi obtido quando o sistema operacional foi operado a 42„aC com substratos contendo etanol eoleo de palma na razao molar de 18:1. Os modelos matematicos que representam o rendimento global da reacao para cada lipase imobilizada foram considerados adequados para descrever os resultados experimentais.Optimized conditions for palm oil and ethanol enzymatic biodiesel synthesis were determined with different immobilized lipases SiO2-PVA-immobilized lipase from Pseudomonas fluorescens and acrylic resin-immobilized lipase, NovozymR435, from Candida antartica, in solvent-free medium. A full factorial design assessed the influence oftemperature (42 ¡V 58¢XC and ethanol: palm oil (6:1 ¡V 18:1 molar ratio on the transesterification yield. Main effects were adjusted by multiple regression analysis to linear models and the maximum transesterification yield was obtained at 42¢XC and 18:1 ethanol:palm oil molar ratio. Mathematical models featuring total yield for each immobilized lipase were suitable to describe the experimental results.

  7. Bactericidal efficacy of elevated pH on fish pathogenic and environmental bacteria

    Clifford E. Starliper

    2013-07-01

    Full Text Available Ship ballast water is a recognized medium for transfer and introductions of nonindigenous species. There is a need for new ballast water treatment methods that effectively and safely eliminate or greatly minimize movements of these species. The present study employed laboratory methods to evaluate the bactericidal efficacy of increased pH (pH 10.0–12.0 for exposure durations of up to 72 h to kill a variety of Gram-negative and Gram-positive bacteria including fish pathogens (Aeromonas spp., Yersinia ruckeri, Edwardsiella ictaluri, Serratia liquefaciens, Carnobacterium sp., other common aquatic-inhabitant bacteria (Serratia marcescens, Pseudomonas fluorescens, Staphylococcus sp., Bacillus sp. and indicators listed in International Maritime Organization D2 Standards; namely, Vibrio cholera (an environmental isolate from fish, Escherichia coli and Enterococcus faecalis. Volumes of 5 N NaOH were added to tryptic soy broth to obtain desired pH adjustments. Viable cells were determined after 0, 4, 12, 24, 48, and 72 h. Initial (0 h cell numbers ranged from 3.40 × 104 cfu/mL for Bacillus sp. to 2.44 × 107 cfu/mL for E. faecalis. The effective endpoints of pH and treatment duration necessary to realize 100% bactericidal effect varied; however, all bacteria tested were killed within 72 h at pH 12.0 or lower. The lowest parameters examined, 4 h at pH 10.0, were bactericidal to V. cholera, E. ictaluri, three of four isolates of E. coli, and (three of four Aeromonas salmonicida subsp. salmonicida. Bactericidal effect was attained at pH 10.0 within 12 h for the other A. salmonicida subsp. salmonicida, and within 24 h for P. fluorescens, and the remaining E. coli.

  8. Biocontrol of certain soilborne diseases and promotion of growth of capsicum annuum using biofungicides

    Madbouly, A.; Abdelbacki, A.M.M.

    2017-01-01

    Colored pepper (Capsicum annuum L.) has great economic importance as a food vegetable crop in Egypt and all over the world. This crop is prone to infection with soilborne fungal pathogens such as Rhizoctonia solani, Fusarium solani and Macrophomina phaseolina. These mycopathogens were isolated from diseased pepper seedlings, identified; their virulence was confirmed in the greenhouse. Eight bacterial isolates mainly; (Bacillus subtilis and Pseudomonas fluorescens), and many fungal isolates mainly, (Trichoderma harzianum and T. viride), were isolated from the rhizosphere soil of pepper. They caused appreciable In vitro inhibition of the radial growth of the 3 pathogens in dual culture technique, in percentages ranging from (71-79%) and (80-87%), respectively. On infestation of pepper soil with these bioagents and the 3 pathogens separately in the greenhouse, they caused In vivo reduction of disease symptoms of pepper compared with the pathogens infested and non-infested control soils. In addition, they caused significant improvement of pepper growth compared with the control soil, however, promotion exerted by B. subtilis and T. harzianum was more than that of P. fluorescens and T. viride. These promoting activities could be attributed to the production of metabolites such as growth hormones; solubilization of phosphates and improvement of nutrient uptake. This is the first record of promoting the growth of pepper in greenhouse by B. subtilis and T. harzianum in Egypt. Thus these bioagents could be formulated then applied in the future in pepper fields of this country as safe, effective, ecofriendly biofungicides to control soilborne pathogens and also could be used as biofertilizers to promote the growth and productivity of this crop. (author)

  9. Adhesion to brown trout skin mucus, antagonism against cyst adhesion and pathogenicity to rainbow trout of some inhibitory bacteria against Saprolegnia parasitica .

    Carbajal-González, M T; Fregeneda-Grandes, J M; González-Palacios, C; Aller-Gancedo, J M

    2013-04-29

    Biological control of saprolegniosis with bacteria might be an alternative to the use of chemical compounds. Among criteria for the selection of such bacteria are their absence of pathogenicity to fish and their ability to prevent adhesion of the pathogen to the skin mucus. The pathogenicity to rainbow trout of 21 bacterial isolates with in vitro inhibitory activity against Saprolegnia parasitica was studied. Fifteen of the isolates, identified as Aeromonas sobria, Pantoea agglomerans, Pseudomonas fluorescens, Serratia fonticola, Xanthomonas retroflexus and Yersinia kristensenii, were non-pathogenic when injected into rainbow trout. Their capacity to adhere to the skin mucus of male and female brown trout and to reduce the adhesion of S. parasitica cysts under exclusion, competition and displacement conditions was tested. The 15 bacterial isolates showed a low adhesion rate, ranging between 1.7% (for an A. sobria isolate) and 15.3% (a P. fluorescens isolate). This adhesion was greater in the case of mucus from male brown trout than from females. Similarities in the adhesion to male mucus and other substrates and correlation to that observed to polystyrene suggest that adhesion to skin mucus does not depend on the substrate. A high percentage (88.9%) of the S. parasitica cysts adhered to the skin mucus of male brown trout. Almost all of the bacteria reduced this adhesion ratio significantly under exclusion and competition conditions. However, only half of the isolates displaced cysts from skin mucus, and more bacterial cells were necessary for this effect. A novel method to study the adhesion of S. parasitica cysts to skin mucus of trout and their interactions with inhibitory bacteria is described.

  10. Biotransformation of Lactones with Methylcyclohexane Ring and Their Biological Activity

    Katarzyna Wińska

    2016-12-01

    Full Text Available The aim of the study was to obtain biological active compounds during biotransformation. Three bicyclic halolactones with methylcyclohexane ring (2-chloro-4-methyl-9-oxabicyclo-[4.3.0]nonan-8-one, 2-bromo-4-methyl-9-oxabicyclo[4.3.0]nona- -8-one and 2-iodo-4-methyl-9-oxabicyclo[4.3.0]nonan-8-one obtained from the corresponding γ,δ-unsaturated acid were subjected to a screening biotransformation using 22 fungal strains. Two of these strains (Cunninghamella japonica AM472 and Fusarium culmorum AM10 were able to transform halolactones into 2-hydroxy-4-methyl-9-oxabicyclo[4.3.0]nonan-8-one by hydrolytic dehalogenation with good yield. The biotransformation product was structurally different from its synthetically prepared analog. All halolactones and hydroxylactones were tested for their biological activity. The chlorolactone inhibited growth of Staphylococcus aureus (max ΔOD = 0, Escherichia coli (max ΔOD = 0.3 and Candida albicans (max ΔOD = 0 strains. Bromolactone caused inhibition of growth of Staphylococcus aureus (max ΔOD = 0 and Fusarium linii (max ΔOD = 0 strains. Iodolactone limited growth of Staphylococcus aureus (max ΔOD = 0, Escherichia coli (max ΔOD = 0.25, Candida albicans (max ΔOD = 0.45 and Pseudomonas fluorescens (max ΔOD = 0.42 strains. Hydroxylactone caused inhibition of growth of Staphylococcus aureus (max ΔOD = 0.36 and Pseudomonas fluorescens (max ΔOD = 0.39 strains only. The test performed on aphids Myzus persicae (Sulz. showed that chloro- and bromolactone exhibited deterrent activity after 24 h (ID = 0.5 and 0.4, respectively, while hydroxylactone was a weak attractant (ID = −0.3.

  11. Composts containing fluorescent pseudomonads suppress fusarium root and stem rot development on greenhouse cucumber.

    Bradley, Geoffrey G; Punja, Zamir K

    2010-11-01

    Three composts (Ball, dairy, and greenhouse) were tested for the ability to suppress the development of Fusarium root and stem rot (caused by Fusarium oxysporum f. sp. radicis-cucumerinum) on greenhouse cucumber. Dairy and greenhouse composts significantly reduced disease severity (P = 0.05), while Ball compost had no effect. Assessment of total culturable microbes in the composts showed a positive relationship between disease suppressive ability and total population levels of pseudomonads. In vitro antagonism assays between compost-isolated bacterial strains and the pathogen showed that strains of Pseudomonas aeruginosa exhibited the greatest antagonism. In growth room trials, strains of P. aeruginosa and nonantagonistic Pseudomonas maculicola, plus 2 biocontrol strains of Pseudomonas fluorescens, were tested for their ability to reduce (i) survival of F. oxysporum, (ii) colonization of plants by the pathogen, and (iii) disease severity. Cucumber seedlings grown in compost receiving P. aeruginosa and P. fluorescens had reduced disease severity index scores after 8 weeks compared with control plants without bacteria. Internal stem colonization by F. oxysporum was significantly reduced by P. aeruginosa. The bacteria colonized plant roots at 1.9 × 10(6) ± 0.73 × 10(6) CFU·(g root tissue)-1 and survival was >107 CFU·(g compost)-1 after 6 weeks. The locus for 2,4-diacetylphloroglucinol production was detected by Southern blot analysis and confirmed by PCR. The production of the antibiotic 2,4-diacetylphloroglucinol in liquid culture by P. aeruginosa was confirmed by thin layer chromatography. These results demonstrate that composts containing antibiotic-producing P. aeruginosa have the potential to suppress diseases caused by Fusarium species.

  12. Inhibition of food-related bacteria by antibacterial substances produced by Pseudomonas sp. strains isolated from pasteurized milk

    Ana Beatriz Ferreira Rangel

    2013-12-01

    Full Text Available In this work, the production of antimicrobial substances by strains of Pseudomonas sp. isolated from pasteurized milk and their potential action against food-related bacteria were investigated. Samples of pasteurized milk were purchased from arbitrarily chosen commercial establishments in the city of Rio de Janeiro, Brazil. Of the four samples analyzed, three presented several typical colonies of Pseudomonas. About 100 colonies were chosen and subjected to biochemical tests for confirmation of their identity. Eighteen strains of the Pseudomonas genus were identified and submitted to tests for the production of antimicrobial substances. Twelve strains (66.7% were identified as Pseudomonas fluorescens, four (22.2% as P. aeruginosa, one (5.5% as P. mendocina and one (5.5% as P. pseudoalcaligenes. Only two P. fluorescens strains were unable to produce any antimicrobial substance against any of the indicator strains tested. Most of the strains presented a broad spectrum of action, inhibiting reference and food-related strains such as Proteus vulgaris, Proteus mirabilis, Hafnia alvei, Yersinia enterocolitica, Escherichia coli and Salmonella typhi. Five antimicrobial substance-producing strains, which presented the broadest spectrum of action, were also tested against Staphylococcus aureus reference strains and 26 Staphylococcus sp. strains isolated from foods, some of which were resistant to antibiotics. The producer strains 8.1 and 8.3, both P. aeruginosa, were able to inhibit all the staphylococcal strains tested. The antimicrobial substances produced by strains 8.1 and 8.3 did not seem to be typical bacteriocins, since they were resistant to the three proteolytic enzymes tested. Experiments involving the characterization of these substances are being carried out in order to evaluate their biotechnological application.

  13. Export of recombinant proteins in Escherichia coli using ABC transporter with an attached lipase ABC transporter recognition domain (LARD

    Moon Yuseok

    2009-01-01

    Full Text Available Abstract Background ATP binding cassette (ABC transporter secretes the protein through inner and outer membranes simultaneously in gram negative bacteria. Thermostable lipase (TliA of Pseudomonas fluorescens SIK W1 is secreted through the ABC transporter. TliA has four glycine-rich repeats (GGXGXD in its C-terminus, which appear in many ABC transporter-secreted proteins. From a homology model of TliA derived from the structure of P. aeruginosa alkaline protease (AprA, lipase ABC transporter domains (LARDs were designed for the secretion of fusion proteins. Results The LARDs included four glycine-rich repeats comprising a β-roll structure, and were added to the C-terminus of test proteins. Either Pro-Gly linker or Factor Xa site was added between fusion proteins and LARDs. We attached different length of LARDs such as LARD0, LARD1 or whole TliA (the longest LARD to three types of proteins; green fluorescent protein (GFP, epidermal growth factor (EGF and cytoplasmic transduction peptide (CTP. These fusion proteins were expressed in Escherichia coli together with ABC transporter of either P. fluorescens or Erwinia chrysanthemi. Export of fusion proteins with the whole TliA through the ABC transporter was evident on the basis of lipase enzymatic activity. Upon supplementation of E. coli with ABC transporter, GFP-LARDs and EGF-LARDs were excreted into the culture supernatant. Conclusion The LARDs or whole TliA were attached to C-termini of model proteins and enabled the export of the model proteins such as GFP and EGF in E. coli supplemented with ABC transporter. These results open the possibility for the extracellular production of recombinant proteins in Pseudomonas using LARDs or TliA as a C-terminal signal sequence.

  14. Rapid detection of rRNA group I pseudomonads in contaminated metalworking fluids and biofilm formation by fluorescent in situ hybridization.

    Saha, Ratul; Donofrio, Robert S; Goeres, Darla M; Bagley, Susan T

    2012-05-01

    Metalworking fluids (MWFs), used in different machining operations, are highly prone to microbial degradation. Microbial communities present in MWFs lead to biofilm formation in the MWF systems, which act as a continuous source of contamination. Species of rRNA group I Pseudomonas dominate in contaminated MWFs. However, their actual distribution is typically underestimated when using standard culturing techniques as most fail to grow on the commonly used Pseudomonas Isolation Agar. To overcome this, fluorescent in situ hybridization (FISH) was used to study their abundance along with biofilm formation by two species recovered from MWFs, Pseudomonas fluorescens MWF-1 and the newly described Pseudomonas oleovorans subsp. lubricantis. Based on 16S rRNA sequences, a unique fluorescent molecular probe (Pseudo120) was designed targeting a conserved signature sequence common to all rRNA group I Pseudomonas. The specificity of the probe was evaluated using hybridization experiments with whole cells of different Pseudomonas species. The probe's sensitivity was determined to be 10(3) cells/ml. It successfully detected and enumerated the abundance and distribution of Pseudomonas indicating levels between 3.2 (± 1.1) × 10(6) and 5.0 (± 2.3) × 10(6) cells/ml in four different industrial MWF samples collected from three different locations. Biofilm formation was visualized under stagnant conditions using high and low concentrations of cells for both P. fluorescens MWF-1 and P. oleovorans subsp. lubricantis stained with methylene blue and Pseudo120. On the basis of these observations, this molecular probe can be successfully be used in the management of MWF systems to monitor the levels and biofilm formation of rRNA group I pseudomonads.

  15. Combination of selected enzymes with cetyltrimethylammonium bromide in biofilm inactivation, removal and regrowth

    Araujo, Paula Alexandra Da Silva

    2017-03-01

    Enzymes are considered an innovative and environmentally friendly approach for biofilm control due to their lytic and dispersal activities. In this study, four enzymes (β-glucanase, α-amylase, lipase and protease) were tested separately and in combination with the quaternary ammonium compound cetyltrimethylammonium bromide (CTAB) to control flow-generated biofilms of Pseudomonas fluorescens. The four enzymes caused modest reduction of biofilm colony forming units (CFU). Protease, β-glucanase and α-amylase also caused modest biofilm removal. CTAB combined with either β-glucanase or α-amylase increased biofilm removal. Its combination with either β-glucanase or protease increased CFU reduction. However, CTAB−protease combination was antagonist in biofilm removal. Long-term effects in biofilm mass reduction were observed after protease exposure. In contrast, biofilms treated with β-glucanase were able to regrowth significantly after exposure. Moreover, short-term respirometry tests with planktonic cells were performed to understand the effects of enzymes and their combination with CTAB on P. fluorescens viability. Protease and lipase demonstrated antimicrobial action, while α-amylase increased bacterial metabolic activity. The combination of CTAB with either protease or α-amylase was antagonistic, decreasing the antimicrobial action of CTAB. The overall results demonstrate a modest effect of the selected enzymes in biofilm control, either when applied alone or each one in combination with CTAB. Total biofilm removal or CFU reduction was not achieved and, in some cases, the use of enzymes antagonized the effects of CTAB. The results also propose that complementary tests, to characterize biofilm integrity and microbial viability, are required when someone is trying to assess the role of novel biocide - enzyme mixtures for effective biofilm control.

  16. Effect of nutrients and fermentation conditions on the production of biosurfactants using rhizobacteria isolated from fique plants

    Aura M. Pedroza-Rodríguez

    2010-12-01

    Full Text Available To isolate biosurfactant-producing microorganisms from the rhizosphere of fique and to select the best genus to evaluate theeffect of nutritional and fermentation conditions on the production of rhamnolipids. Materials and methods. Rhizospheric soil wassampled in three areas of Cauca. The best genus was selected for the experimental designs (Plackett Burman and 22 factorial and to find theproduction conditions for the growth kinetics at an Erlenmeyer flask scale. Results. Isolates from the rhizosphere of fique plants were fromgroups (or genera of Bacillus, Pseudomonas and Actinomycetes, being Pseudomonas the more responsive in preliminary testing foremulsification. From the results of the experimental designs and the kinetics of production, we found that rhamnose synthesis associatedwith rhamnolipids (3.2 g/l and emulsification (68% EC24 was significantly favored (p <0.0001 by cultivating an inoculum of 10% v/vof Pseudomonas fluorescens in a medium composed of: soybean oil 2% (v/v, K2HPO40.2% (w/v, yeast extract 0.4 g/l, NH4NO33.7 g/l, 1 ml trace elements (CoCl320 mg/l, H3BO330 mg/l, ZnSO410 mg/l, Cu2SO41 mg/l, Na2MoO43 mg/l, FeSO410 mg/l MnSO42,6 mg/l and pH 7.2. Conclusion. Of all the microbial genera isolated from the rhizosphere of fique, Pseudomonas fluorescens had the greatestpotential in the production of biosurfactants of the rhamnolipids family.

  17. Safety of the molluscicide Zequanox (R) to nontarget macroinvertebrates Gammarus lacustris (Amphipoda: Gammaridae) and Hexagenia spp. (Ephemeroptera: Ephemeridae)

    Waller, Diane L.; Luoma, James A.; Erickson, Richard A.

    2016-01-01

    Zequanox® is a commercial formulation of the killed bacterium, Pseudomonas fluorescens (strain CL145A), that was developed to control dreissenid mussels. In 2014, Zequanox became the second product registered by the United States Environmental Protection Agency (USEPA) for use in open water environments as a molluscicide. Previous nontarget studies demonstrated the safety and selectivity of P. fluorescens CL154A, but the database on the toxicity of the formulation (Zequanox) is limited for macroinvertebrate taxa and exposure conditions. We evaluated the safety of Zequanox to the amphipod Gammarus lacustris lacustris, and nymphs of the burrowing mayfly, Hexagenia spp. at the maximum approved concentration (100 mg/L active ingredient, A.I.) and exposure duration (8 h). Survival of animals was assessed after 8 h of exposure and again at 24 and 96 h post-exposure. Histopathology of the digestive tract of control and treated animals was compared at 96 h post-exposure. The results showed no significant effect of Zequanox on survival of either species. Survival of G. lacustris exceeded 85% in all concentrations at all three sampling time points. Survival of Hexagenia spp. ranged from 71% (control) to 91% at 8 h, 89–93% at 24 h post-exposure, and 70–73% at 96 h post-exposure across all treatments. We saw no evidence of pathology in the visceral organs of treated animals. Our results indicate that application of Zequanox at the maximum approved concentration and exposure duration did not cause significant mortality or treatment-related histopathological changes to G. lacustris and Hexagenia spp.

  18. Increasing potassium (K release from K-containing minerals in the presence of insoluble phosphate by bacteria

    Mohammad Reza Sarikhani

    2016-03-01

    Full Text Available Introduction: Phosphorus and potassium are major essential macronutrients for biological growth and development. Application of soil microorganisms is one approach to enhance crop growth. Some bacteria are efficient in releasing K and solubilizing P from mineral sources but their behavior was not studied more in presence together. Materials and methods: In this study the ability of seven bacterial strains, including Pseudomonas putida P13, P. putida Tabriz, P. fluorescens Tabriz, P. fluorescens Chao, Pantoea agglomerans P5, Azotobacter sp. and Bacillus megaterium JK3 to release mineral K from muscovite and biotite with application of insoluble (Ca3(PO42 or soluble (Na2HPO4 P-sources was investigated. Nutrient Broth was used to prepare an overnight culture of bacteria to inoculate in Aleksandrov medium, which was used to study the dissolution of silicate minerals. It should be mentioned that Aleksandrov medium was used to determine the amount of released P from tricalcium phosphate (TCP while muscovite was added to the medium as a sole source of potassium. Concentration of P was determined spectrophotometrically by ammonium-vanadate-molybdate method and K was determined by flame photometry. Results: The insoluble P-source led to a significantly increased released K into assay medium (66%, and the net release of K from the biotite was significantly enhanced. Among bacterial strains, the highest mean of released K was observed with P. putida P13 which released more K (27% than the control. The amounts of released K from micas in the presence of insoluble and soluble phosphate by P. putida P13 were 8.25 and 4.87 mg/g, respectively. Discussion and conclusion: Application of insoluble phosphate could increase K release from mica minerals. The enhanced releasing of mineral K might be attributed to the release of organic acids from the bacteria, a mechanism which plays a pivotal role in solubilizing phosphate from inorganic source of phosphate.

  19. Identification of Fic-1 as an enzyme that inhibits bacterial DNA replication by AMPylating GyrB, promoting filament formation.

    Lu, Canhua; Nakayasu, Ernesto S; Zhang, Li-Qun; Luo, Zhao-Qing

    2016-01-26

    The morphology of bacterial cells is important for virulence, evasion of the host immune system, and coping with environmental stresses. The widely distributed Fic proteins (filamentation induced by cAMP) are annotated as proteins involved in cell division because of the presence of the HPFx[D/E]GN[G/K]R motif. We showed that the presence of Fic-1 from Pseudomonas fluorescens significantly reduced the yield of plasmid DNA when expressed in Escherichia coli or P. fluorescens. Fic-1 interacted with GyrB, a subunit of DNA gyrase, which is essential for bacterial DNA replication. Fic-1 catalyzed the AMPylation of GyrB at Tyr(109), a residue critical for binding ATP, and exhibited auto-AMPylation activity. Mutation of the Fic-1 auto-AMPylated site greatly reduced AMPylation activity toward itself and toward GyrB. Fic-1-dependent AMPylation of GyrB triggered the SOS response, indicative of DNA replication stress or DNA damage. Fic-1 also promoted the formation of elongated cells when the SOS response was blocked. We identified an α-inhibitor protein that we named anti-Fic-1 (AntF), encoded by a gene immediately upstream of Fic-1. AntF interacted with Fic-1, inhibited the AMPylation activity of Fic-1 for GyrB in vitro, and blocked Fic-1-mediated inhibition of DNA replication in bacteria, suggesting that Fic-1 and AntF comprise a toxin-antitoxin module. Our work establishes Fic-1 as an AMPylating enzyme that targets GyrB to inhibit DNA replication and may target other proteins to regulate bacterial morphology. Copyright © 2016, American Association for the Advancement of Science.

  20. Impact of lead tolerant plant growth promoting rhizobacteria on growth, physiology, antioxidant activities, yield and lead content in sunflower in lead contaminated soil.

    Saleem, Muhammad; Asghar, Hafiz Naeem; Zahir, Zahir Ahmad; Shahid, Muhammad

    2018-03-01

    Present study was conducted to evaluate the effect of lead tolerant plant growth promoting rhizobacteria (LTPGPR) on growth, physiology, yield, antioxidant activities and lead uptake in sunflower in soil contaminated with lead under pot conditions. Three pre-characterized LTPGP strains (S2 (Pseudomonas gessardii strain BLP141), S5 (Pseudomonas fluorescens A506) and S10 (Pseudomonas fluorescens strain LMG 2189)) were used to inoculate sunflower growing in soil contaminated with different levels (300, 600 and 900 mg kg -1 ) of lead by using lead nitrate salt as source of lead. Treatments were arranged according to completely randomized design with factorial arrangements. At harvesting, data regarding growth attributes (root shoot length, root shoot fresh and dry weights), yield per plant, physiological attributes (Chlorophyll 'a', 'b' and carotenoids content), antioxidant activities (Ascorbate peroxidase, catalase, superoxide dismutase and glutathione reductase), proline and malanodialdehyde content, and lead content in root, shoot and achenes of sunflower were recorded. Data were analysed by standard statistical procedures. Results showed that lead contamination reduced the plants growth, physiology and yield at all levels of lead stress. But application of LTPGPR in soil contaminated with lead improved plant growth, physiology, yield, and antioxidant activities, proline, and reduced the malanodialdehyde content (that is reduced by the application of different strains in lead contamination) of sunflower as compared to plants grown in soil without inoculation. Inoculation also promoted the uptake of lead in root, shoots and reduced the uptake of lead in achenes of plants as compared to plants in lead contamination without inoculation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Pulsed-light inactivation of pathogenic and spoilage bacteria on cheese surface.

    Proulx, J; Hsu, L C; Miller, B M; Sullivan, G; Paradis, K; Moraru, C I

    2015-09-01

    Cheese products are susceptible to postprocessing cross-contamination by bacterial surface contamination during slicing, handling, or packaging, which can lead to food safety issues and significant losses due to spoilage. This study examined the effectiveness of pulsed-light (PL) treatment on the inactivation of the spoilage microorganism Pseudomonas fluorescens, the nonenterohemorrhagic Escherichia coli ATCC 25922 (nonpathogenic surrogate of Escherichia coli O157:H7), and Listeria innocua (nonpathogenic surrogate of Listeria monocytogenes) on cheese surface. The effects of inoculum level and cheese surface topography and the presence of clear polyethylene packaging were evaluated in a full factorial experimental design. The challenge microorganisms were grown to early stationary phase and subsequently diluted to reach initial inoculum levels of either 5 or 7 log cfu/slice. White Cheddar and process cheeses were cut into 2.5×5 cm slices, which were spot-inoculated with 100 µL of bacterial suspension. Inoculated cheese samples were exposed to PL doses of 1.02 to 12.29 J/cm(2). Recovered survivors were enumerated by standard plate counting or the most probable number technique, as appropriate. The PL treatments were performed in triplicate and data were analyzed using a general linear model. Listeria innocua was the least sensitive to PL treatment, with a maximum inactivation level of 3.37±0.2 log, followed by P. fluorescens, with a maximum inactivation of 3.74±0.8 log. Escherichia coli was the most sensitive to PL, with a maximum reduction of 5.41±0.1 log. All PL inactivation curves were nonlinear, and inactivation reached a plateau after 3 pulses (3.07 J/cm(2)). The PL treatments through UV-transparent packaging and without packaging consistently resulted in similar inactivation levels. This study demonstrates that PL has strong potential for decontamination of the cheese surface. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc

  2. A sulfonic anhydride derivative from dibenzyl trisulphide with agro-chemical activities.

    Williams, L A D; Vasquez, E; Klaiber, I; Kraus, W; Rosner, H

    2003-06-01

    In the present study, the biologically active natural product dibenzyl trisulphide (DTS) which was previously isolated from the sub-tropical shrub Petiveria alliacea was transformed to methyl benzyl sulphonic anhydride (MBSA) using a "one pot" transformation method. The anhydride was evaluated for anti-microbial activities on the bacteria, Bacillus subtilis and Pseudomonas fluorescens and found to be 2.5 fold more effective than the commercial agents isoniazid and ampicillin in inhibiting the growth of B. subtilis, while on P. fluorescens it was 2.5, 5.0 and 10.0 fold more inhibitory than isoniazid, ampicillin and dibenzyl trisulphide, respectively. DTS was inactive on B. subtillis. The MIC value (microgram/spot) found for DTS on the plant pathogenic fungus, Cladosporium cucumerinum was 5.0 microgram/spot, while MBSA gave a value of 0.1 microgram/spot, compared with 1.25 and 0.16 microgram/spot for the commercial agents ketoconazole and nystatin, respectively. On the larval nematode (Meloidogyne incognita) MBSA inflicted 97.72% and 57.47% Abbotts nematicidal activities at 125.0 and 62.5 ppm, respectively, while DTS had no effect at 125.0 ppm. Nematodes which were immobilized by the low concentrations of MBSA were unable to re-activate when exposed to 10.0 ppm picrotoxin, thus suggesting that the anhydride nematicidal activity is independent of the GABA-ergic neurophysiological pathway.MBSA demonstrated a strong dose dependent radicular suppression effect (r=0.984), on the radicles of Latuca sativa germinating seeds. DTS was weakly active.

  3. Bacterial Contamination of Boar Semen and its Relationship to Sperm Quality Preserved in Commercial Extender Containing Gentamicin Sulfate.

    Gączarzewicz, D; Udała, J; Piasecka, M; Błaszczyk, B; Stankiewicz, T

    2016-09-01

    This study was designed to determine the degree and type of bacterial contamination in boar semen (79 ejaculates from Large White and Landrace boars) and its consequences for sperm quality during storage (27 extended semen samples, 16°C for five days) under practical conditions of artificial insemination (AI). The results revealed the presence of aerobic bacteria in 99% of the ejaculates (from 80 to 370 ×106 colony-forming units/mL). Most of the ejaculates contained two or three bacterial contaminants, while the Staphylococcus, Streptococcus, and Pseudomonas bacterial genera were most frequently isolated. Also detected were Enterobacter spp., Bacillus spp., Proteus spp., Escherichia coli, P. fluorescens, and P. aeruginosa. In general, the growth of certain bacterial types isolated prior to semen processing (Enterobacter spp., E. coli, P. fluorescens, and P. aeruginosa) was not discovered on different days of storage, but fluctuations (with a tendency towards increases) were found in the frequencies of Bacillus spp., Pseudomonas spp., and Staphylococcus spp. isolates up to the end of storage. Semen preserved for five days exhibited decreases in sperm motility and increases in the average number of total aerobic bacteria; this was associated with sperm agglutination, plasma membrane disruption, and acrosome damage. We inferred that, due to the different degrees and types of bacterial contaminants in the boar ejaculates, the inhibitory activity of some antimicrobial agents used in swine extenders (such as gentamicin sulfate) may be limited. Because such agents can contribute to the overgrowth of certain aerobic bacteria and a reduction in the quality of stored semen, procedures with high standards of hygiene and microbiological control should be used when processing boar semen.

  4. Generation of ozone foam and its application for disinfection

    Hiragaki, Keisuke; Ishimaru, Tomiya; Nakanishi, Masaru; Muraki, Ryouji; Nieda, Masanori; Yamabe, Chobei

    2015-07-01

    Generated ozone foam was applied to the disinfection of Pseudomonas fluorescens. The effect of disinfection has been confirmed experimentally and new equipment for the disinfection of hands using this ozone foam has been put on the market for the practical use. The ozone foam was produced in the foam generator after mixing the water including surfactant (30 mL/min) and air including ozone (1000 ppm = 2.14 g/m3 ~ 1600 ppm = 3.4 g/m3, 300 mL/min). The liquid-to-gas ratio is 100 L/m3. The concentration of dissolved ozone in the thin liquid films of the bubbles was about 3 mg/L which was measured by the chemical method of the KI absorption and titration of sodium thiosulfate solution. The disinfection test samples were prepared using the PET disk on which Pseudomonas fluorescens of its number of more than 108 were attached. Test sample was inserted into ozone foam set on the glass plate for one to 6 min. The survival rate log (N/N0 decreased with time and its value of about-2.6 (i.e., ~1/400) was obtained at 6 min (2 min × 3 times repeated). It was also confirmed that the ozone foam was useful for the disinfection of hands. For more effective disinfection (in case of taking a long time for foam melting), the ozone foam was broken by force and changed into ozone water by which the survival rate decreased ×4 (i.e., N/N0 = 1/10 000) at 4 ~ 6 min. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  5. Vanillin production using metabolically engineered Escherichia coli under non-growing conditions.

    Barghini, Paolo; Di Gioia, Diana; Fava, Fabio; Ruzzi, Maurizio

    2007-04-16

    Vanillin is one of the most important aromatic flavour compounds used in the food and cosmetic industries. Natural vanillin is extracted from vanilla beans and is relatively expensive. Moreover, the consumer demand for natural vanillin highly exceeds the amount of vanillin extracted by plant sources. This has led to the investigation of other routes to obtain this flavour such as the biotechnological production from ferulic acid. Studies concerning the use of engineered recombinant Escherichia coli cells as biocatalysts for vanillin production are described in the literature, but yield optimization and biotransformation conditions have not been investigated in details. Effect of plasmid copy number in metabolic engineering of E. coli for the synthesis of vanillin has been evaluated by the use of genes encoding feruloyl-CoA synthetase and feruloyl hydratase/aldolase from Pseudomonas fluorescens BF13. The higher vanillin production yield was obtained using resting cells of E. coli strain JM109 harbouring a low-copy number vector and a promoter exhibiting a low activity to drive the expression of the catabolic genes. Optimization of the bioconversion of ferulic acid to vanillin was accomplished by a response surface methodology. The experimental conditions that allowed us to obtain high values for response functions were 3.3 mM ferulic acid and 4.5 g/L of biomass, with a yield of 70.6% and specific productivity of 5.9 micromoles/g x min after 3 hours of incubation. The final concentration of vanillin in the medium was increased up to 3.5 mM after a 6-hour incubation by sequential spiking of 1.1 mM ferulic acid. The resting cells could be reused up to four times maintaining the production yield levels over 50%, thus increasing three times the vanillin obtained per gram of biomass. Ferulic acid can be efficiently converted to vanillin, without accumulation of undesirable vanillin reduction/oxidation products, using E. coli JM109 cells expressing genes from the ferulic

  6. Acoplamiento molecular y actividad antibacteriana de las tioureas (R,R-N,N´-bis(1-ciclohexiletiltiourea y (R,R-N,N´-bis(1-feniletiltiourea

    Fabían Martínez Flores

    2013-05-01

    Full Text Available Las tioureas, son compuestos resultantes de sustituir el átomo de oxígeno de la urea (NH2CONH2 por un átomo de azufre (NH2CSNH2. Actualmente se ha visto que las tioureas presentan diversas actividades biológicas, dentro de las que se encuentra la antimicrobiana. En el presente estudio se evaluó la actividad antibacteriana mediante acoplamiento molecular entre la enzima DNA girasa (receptor y las tioureas (R, R-N,N´-bis(1 ciclohexiletiltiourea (CYTU1 y (R,R-N,N´-bis(1-feniletiltiourea (CYTU2 como ligando en busca del posible mecanismo de acción de estos compuestos, los resultados muestran que existe interacción entre la enzima y ambas tioureas en el sitio activo. Por otro lado, también se evaluó la actividad antibacteriana frente a cepas de Sthapylococcus aureus, Escherichia coli y Pseudomonas fluorescens, mediante el método de microdilución en caldo con la adición de bromuro de 3-(4,5-dimetil-2-tiazolil-2,5-difeniltetrazolium (MTT, como parte del ensayo de viabilidad, mostrando una disminución de la misma sólo contra las bacterias gram negativas, siendo la tiourea CYTU2 la que mostró mejor actividad antibacteriana. Molecular docking and antibacterial activity thioureas (R,R-N,N´-bis(1-cyclohexyethylthiourea and (R,R-N,N´-bis(1-phenylethylthiourea Abstract Thioureas are resultant compounds of substitute the oxygen atom from urea (NH2CONH2 for a sulfur atom (NH2CSNH2. There are evidential that show the biological activity of thioureas, within which are antibacterial activity. We studied the antibacterial activity of two thioureas (R,R-N,N´-bis(1 cyclohexylethylthiourea (CYTU1 y (R,R-N,N´-bis(1 phenylethylthiourea (CYTU2 in silico using Molecular Docking between the DNA gyrase enzyme (receptor and the two thioureas (ligand. The results showed interaction between DNA girase and both thioureas on the pocket of the enzyme. By other hand, the biological activity was evaluated against the following bacterial strains: Sthapylococcus

  7. Pyoverdine synthesis by the Mn(II-oxidizing bacterium Pseudomonas putida GB-1

    Dorothy Lundquist Parker

    2014-05-01

    Full Text Available When iron-starved, the Mn(II-oxidizing bacteria Pseudomonas putida strains GB-1 and MnB1 produce pyoverdines (PVDGB-1 and PVDMnB1, siderophores that both influence iron uptake and inhibit manganese(II oxidation by these strains. To explore the properties and genetics of a PVD that can affect manganese oxidation, LC-MS/MS and various siderotyping techniques were used to identify the peptides of PVDGB-1 and PVDMnB1 as being (for both PVDs: chromophore-Asp-Lys-OHAsp-Ser-Gly-aThr-Lys-cOHOrn, resembling a structure previously reported for P. putida CFML 90-51, which does not oxidize Mn. All three strains also produced an azotobactin and a sulfonated PVD, each with the peptide sequence above, but with unknown regulatory or metabolic effects. Bioinformatic analysis of the sequenced genome of P. putida GB-1 suggested that a particular non-ribosomal peptide synthetase, coded by the operon PputGB1_4083-4086, could produce the peptide backbone of PVDGB-1. To verify this prediction, plasmid integration disruption of PputGB1_4083 was performed and the resulting mutant failed to produce detectable PVD. In silico analysis of the modules in PputGB1_4083-4086 predicted a peptide sequence of Asp-Lys-Asp-Ser-Ala-Thr-Lsy-Orn, which closely matches the peptide determined by MS/MS. To extend these studies to other organisms, various Mn(II-oxidizing and non-oxidizing isolates of P. putida, P. fluorescens, P. marincola, P. fluorescens-syringae group, P. mendocina-resinovorans group and P. stutzerii group were screened for PVD synthesis. The PVD producers (12 out of 16 tested strains were siderotyped and placed into four sets of differing PVD structures, some corresponding to previously characterized PVDs and some to novel PVDs. These results combined with previous studies suggested that the presence of OHAsp or the flexibility of the pyoverdine polypeptide may enable efficient binding of Mn(III.

  8. Vanillin production using metabolically engineered Escherichia coli under non-growing conditions

    Fava Fabio

    2007-04-01

    Full Text Available Abstract Background Vanillin is one of the most important aromatic flavour compounds used in the food and cosmetic industries. Natural vanillin is extracted from vanilla beans and is relatively expensive. Moreover, the consumer demand for natural vanillin highly exceeds the amount of vanillin extracted by plant sources. This has led to the investigation of other routes to obtain this flavour such as the biotechnological production from ferulic acid. Studies concerning the use of engineered recombinant Escherichia coli cells as biocatalysts for vanillin production are described in the literature, but yield optimization and biotransformation conditions have not been investigated in details. Results Effect of plasmid copy number in metabolic engineering of E. coli for the synthesis of vanillin has been evaluated by the use of genes encoding feruloyl-CoA synthetase and feruloyl hydratase/aldolase from Pseudomonas fluorescens BF13. The higher vanillin production yield was obtained using resting cells of E. coli strain JM109 harbouring a low-copy number vector and a promoter exhibiting a low activity to drive the expression of the catabolic genes. Optimization of the bioconversion of ferulic acid to vanillin was accomplished by a response surface methodology. The experimental conditions that allowed us to obtain high values for response functions were 3.3 mM ferulic acid and 4.5 g/L of biomass, with a yield of 70.6% and specific productivity of 5.9 μmoles/g × min after 3 hours of incubation. The final concentration of vanillin in the medium was increased up to 3.5 mM after a 6-hour incubation by sequential spiking of 1.1 mM ferulic acid. The resting cells could be reused up to four times maintaining the production yield levels over 50%, thus increasing three times the vanillin obtained per gram of biomass. Conclusion Ferulic acid can be efficiently converted to vanillin, without accumulation of undesirable vanillin reduction/oxidation products

  9. Pathogenic and Ice-Nucleation Active (INA) Bacteria causing Dieback of Willows in Short Rotation Forestry

    Nejad, Pajand

    2005-03-01

    hypersensitive reaction in tobacco, as well as causing necrotic symptoms on willows exposed to frost treatment. The most frequently isolated types were found to be non-fluorescent P. fluorescens (biotype A, B, C, F, G) and/or Sphingomonas spp. Erwinia spp, P. fluorescens, Xanthomonas spp and P. syringae however, were considered to be the most important pathogens in the field. We conclude that diseases caused by INA bacteria in relationship with frost are a limiting factor in willow and poplar plantations in Sweden and most likely also in other temperate regions in the world.

  10. Comparative genomic analysis of four representative plant growth-promoting rhizobacteria in Pseudomonas

    2013-01-01

    Background Some Pseudomonas strains function as predominant plant growth-promoting rhizobacteria (PGPR). Within this group, Pseudomonas chlororaphis and Pseudomonas fluorescens are non-pathogenic biocontrol agents, and some Pseudomonas aeruginosa and Pseudomonas stutzeri strains are PGPR. P. chlororaphis GP72 is a plant growth-promoting rhizobacterium with a fully sequenced genome. We conducted a genomic analysis comparing GP72 with three other pseudomonad PGPR: P. fluorescens Pf-5, P. aeruginosa M18, and the nitrogen-fixing strain P. stutzeri A1501. Our aim was to identify the similarities and differences among these strains using a comparative genomic approach to clarify the mechanisms of plant growth-promoting activity. Results The genome sizes of GP72, Pf-5, M18, and A1501 ranged from 4.6 to 7.1 M, and the number of protein-coding genes varied among the four species. Clusters of Orthologous Groups (COGs) analysis assigned functions to predicted proteins. The COGs distributions were similar among the four species. However, the percentage of genes encoding transposases and their inactivated derivatives (COG L) was 1.33% of the total genes with COGs classifications in A1501, 0.21% in GP72, 0.02% in Pf-5, and 0.11% in M18. A phylogenetic analysis indicated that GP72 and Pf-5 were the most closely related strains, consistent with the genome alignment results. Comparisons of predicted coding sequences (CDSs) between GP72 and Pf-5 revealed 3544 conserved genes. There were fewer conserved genes when GP72 CDSs were compared with those of A1501 and M18. Comparisons among the four Pseudomonas species revealed 603 conserved genes in GP72, illustrating common plant growth-promoting traits shared among these PGPR. Conserved genes were related to catabolism, transport of plant-derived compounds, stress resistance, and rhizosphere colonization. Some strain-specific CDSs were related to different kinds of biocontrol activities or plant growth promotion. The GP72 genome

  11. Development of Smartphone based Optical Device

    Jung, Youngkee

    Due to the economy of scale, smartphones are becoming more affordable while their computing powers are increasing dramatically every year. Here we propose a ubiquitous and portable instrument for analyte quantitation by utilizing the characteristics of typical smartphone imaging system and specific design of transducers for different applications. Three testbeds included in this work are: quantitative colorimetric analysis, ultra-low radiant flux detection, and portable spectrometer. As a proof-of-principle for each device, 3-D printed cradle and theoretical simulation with MATLAB have been implemented. First example utilizes the native CMOS camera with their respective RGB channel data and perform an analyte quantitation for typical lateral flow devices (LFD). Histogram analysis method has been employed to detect the analyte concentration and calibration results show good correlation between perceived color change and analyte concentration. The second example shows the possibility of using a conventional CMOS camera for pico Watt level photon flux detection. Since most of consumer grade CMOS cameras cannot detect this level of light intensity and their dark current are relatively higher, a new algorithm called NREA (Noise Reduction by Ensemble Averaging) algorithm was developed to effectively reduce the noise level and increase the SNR (signal to noise ratio). This technique is effective for bioanalytical assays that has lower flux intensity such as fluorescence and luminescence. As a proof-of-principle, we tested the device with Pseudomonas fluorescens M3A and achieved a limit of detection of high 10? CFU/ml. In addition to basic schematic of detection model, another experiment with a silicon photomultiplier (SiPM) has been studied for more sensitive light detectability. Based on both the laser experiment and tw bioluminescent experiments, named Pseudomonas fluorescens M3A and NanoLuc, we found that the miniSM based device has a superior ability than the

  12. The effect of a novel low temperature-short time (LTST) process to extend the shelf-life of fluid milk.

    Myer, Phillip R; Parker, Kyle R; Kanach, Andrew T; Zhu, Tengliang; Morgan, Mark T; Applegate, Bruce M

    2016-01-01

    Pasteurization has long been the standard method to extend the shelf-life of dairy products, as well as a means to reduce microbial load and the risk of food-borne pathogens. However, the process has limitations, which include cost effectiveness, high energy input, and reduction of product quality/organoleptic characteristics. In an effort to reduce these limitations and extend shelf-life, this study examined a novel low temperature, short time (LTST) method in which dispersed milk in the form of droplets was treated with low heat/pressure variation over a short treatment time, in conjunction with pasteurization. Lactobacillus fermentum and Pseudomonas fluorescens Migula were exposed to conventional pasteurization treatments with and without LTST. Using these organisms, the LTST addition was able to reduce microbial load below detection limits; 1.0 × 10(1) cfu/mL, from approximately 1.2 × 10(8) and 1.0 × 10(7) cfu/mL for L. fermentum and P. fluorescens Migula, respectively. In addition, the shelf-life of the treated, raw, and uninoculated product was prolonged from 14 to 35 days, compared with standard pasteurization, to as long as 63 days with the LTST amendment. Sensory analysis of samples also demonstrated equal or greater preference for LTST + pasteurization treated milk when compared to pasteurization alone (α = 0.05). Conventional pasteurization was effective at reducing the above mentioned microorganisms by as much as 5.0 log10 cfu/mL. However, LTST was able to achieve 7.0-8.0 log10 cfu/mL reduction of the same microorganisms. In addition, BActerial Rapid Detection using Optical scattering Technology detected and identified microorganisms isolated both pre- and post-treatment, of which the only organisms surviving LTST were Bacillus spp. Increased lethality, improved shelf-life, and equal or better organoleptic characteristics without increased energy consumption demonstrate the effectiveness of the incorporation of LTST. The improved

  13. MICROBIAL IMPACTS ON THE MIGRATION OF ACTINIDES -EFFECTS OF EXUDATES ON ADSORPTION-

    OHNUKI, T.; OZAKI, T.; YOSHIDA, T.; NANKAWA, T.; KOZAI, N.; SAKAMOTO, F.; SUZUKI, Y.; FRANCIS, A.J.

    2006-01-01

    The interaction of actinides with microorganisms has been extensively studied to elucidate migration behavior of actinides in the environments. However, the mechanisms of interaction of microorganisms and actinides are poorly understood. They have been conducting basic science on microbial accumulation of actinides in order to elucidate the environmental behavior of actinides under relevant conditions. The effect of exudates from bacteria cells on the sorption of Eu(III) and Cm(III) by Chlorella vulgaris was studied by a batch method. The pH dependence of log K d of Eu(III) and Cm(III) for cellulose, major component of C. vulgaris cell, differed from that for C. vulgaris. On the contrary, log K d of Eu(III) and Cm(III) for cellulose in the solution containing exudates from C. vulgaris cells in a 0.5% NaCl solution showed a similar pH dependence to that by C. vulgaris. These results strongly suggested that exudates affect on the sorption of Eu(III) and Cm(III) on C. vulgaris. Effect of desferrioxamine B (DFO), one of exudates to chelate the insoluble Fe(III), on the sorption of Pu(IV), Th(IV) and Eu(III) by Pseudomonas fluorescens was studied. In the presence of DFO the sorption of Pu(IV), Th(IV) and Eu(III) on the cells increased with a decrease in pH from 7 to 4. In contrast, without DFO most of Pu(IV), Th(IV) and Eu(III) were precipitated from solution. Adsorption of DFO on the cells was negligible in the solution with and without metals. Adsorption of Pu(IV), Th(IV) and Eu(III) on P. fluorescens cells decreased in the order Eu(III) > Th(IV) > Pu(IV), which corresponds to increasing stability constant of the DFO complexes. These results indicate that Th(IV), Pu(IV) and Eu(III) dissociate when in contact with cells, after which the metals are adsorbed

  14. Microbial impacts on the migration of actinides. Effects of exudates on adsorption

    Ohnuki, Toshihiko; Ozaki, Takuo; Nakawa, Takuya; Kozai, Naofumi; Sakamoto, Fuminori; Suzuki, Yosinori; Yoshida, Takahiro; Francis, Arokiasamy J.

    2007-01-01

    The interaction of actinides with microorganisms has been extensively studied to elucidate migration behavior of actinides in the environments. However, the mechanisms of interaction of microorganisms and actinides are poorly understood. We have been conducting basic science on microbial accumulation of actinides in order to elucidate the environmental behavior of actinides under relevant conditions. The effect of exudates from bacteria cells on the sorption of Eu(III) and Cm(III) by Chlorella vulgaris was studied by a batch method. The pH dependence of log K d of Eu(III) and Cm(III) for cellulose, major component of C. vulgaris cell, differed from that for C. vulgaris. On the contrary, log K d of Eu(III) and Cm(III) for cellulose in the solution containing exudates from C. vulgaris cells in a 0.5% NaCl solution showed a similar pH dependence to that by C. vulgaris. These results strongly suggested that exudates affect on the sorption of Eu(III) and Cm(III) on C. vulgaris. Effect of desferrioxamine B (DFO), one of exudates to chelate with insoluble Fe(III), on the sorption of Pu(IV), Th(IV) and Eu(III) by Pseudomonas fluorescens was studied. In the presence of DFO the sorption of Pu(IV), Th(IV) and Eu(III) on the cells increased with a decrease in pH from 7 to 4. In contrast, without DFO most of Pu(IV), Th(IV) and Eu(III) were precipitated from solution. Adsorption of DFO on the cells was negligible in the solution with and without metals. Adsorption of Pu(IV), Th(IV) and Eu(III) on P. fluorescens cells decreased in the order Eu(III) > Th(IV) > Pu(IV), which corresponds to increasing stability constant of the DFO complexes. These results indicate that Th(IV), Pu(IV) and Eu(III) dissociate when in contact with cells, after which the metals are adsorbed. (author)

  15. Effect of fermented broth from lactic acid bacteria on pathogenic bacteria proliferation.

    Gutiérrez, S; Martínez-Blanco, H; Rodríguez-Aparicio, L B; Ferrero, M A

    2016-04-01

    In this study, the effect that 5 fermented broths of lactic acid bacteria (LAB) strains have on the viability or proliferation and adhesion of 7 potentially pathogenic microorganisms was tested. The fermented broth from Lactococcus lactis C660 had a growth inhibitory effect on Escherichia coli K92 that reached of 31%, 19% to Pseudomonas fluorescens, and 76% to Staphylococcus epidermidis. The growth of Staph. epidermidis was negatively affected to 90% by Lc. lactis 11454 broth, whereas the growth of P. fluorescens (25%) and both species of Staphylococcus (35% to Staphylococcus aureus and 76% to Staph. epidermidis) were inhibited when they were incubated in the presence of Lactobacillus casei 393 broth. Finally, the fermented broth of Lactobacillus rhamnosus showed an inhibitory effect on growth of E. coli K92, Listeria innocua, and Staph. epidermidis reached values of 12, 28, and 76%, respectively. Staphylococcus epidermidis was the most affected strain because the effect was detected from the early stages of growth and it was completely abolished. The results of bacterial adhesion revealed that broths from Lc. lactis strains, Lactobacillus paracasei, and Lb. rhamnosus caused a loss of E. coli K92 adhesion. Bacillus cereus showed a decreased of adhesion in the presence of the broths of Lc. lactis strains and Lb. paracasei. Listeria innocua adhesion inhibition was observed in the presence of Lb. paracasei broth, and the greatest inhibitory effect was registered when this pathogenic bacterium was incubated in presence of Lc. lactis 11454 broth. With respect to the 2 Pseudomonas, we observed a slight adhesion inhibition showed by Lactobacillus rhamnosus broth against Pseudomonas putida. These results confirm that the effect caused by the different LAB assayed is also broth- and species-specific and reveal that the broth from LAB tested can be used as functional bioactive compounds to regulate the adhesion and biofilm synthesis and ultimately lead to preventing food and

  16. Pyoverdine synthesis by the Mn(II)-oxidizing bacterium Pseudomonas putida GB-1

    Parker, Dorothy L.; Lee, Sung-Woo; Geszvain, Kati; Davis, Richard E.; Gruffaz, Christelle; Meyer, Jean-Marie; Torpey, Justin W.; Tebo, Bradley M.

    2014-01-01

    When iron-starved, the Mn(II)-oxidizing bacteria Pseudomonas putida strains GB-1 and MnB1 produce pyoverdines (PVDGB-1 and PVDMnB1), siderophores that both influence iron uptake and inhibit manganese(II) oxidation by these strains. To explore the properties and genetics of a PVD that can affect manganese oxidation, LC-MS/MS, and various siderotyping techniques were used to identify the peptides of PVDGB-1 and PVDMnB1 as being (for both PVDs): chromophore-Asp-Lys-OHAsp-Ser-Gly-aThr-Lys-cOHOrn, resembling a structure previously reported for P. putida CFML 90-51, which does not oxidize Mn. All three strains also produced an azotobactin and a sulfonated PVD, each with the peptide sequence above, but with unknown regulatory or metabolic effects. Bioinformatic analysis of the sequenced genome of P. putida GB-1 suggested that a particular non-ribosomal peptide synthetase (NRPS), coded by the operon PputGB1_4083-4086, could produce the peptide backbone of PVDGB-1. To verify this prediction, plasmid integration disruption of PputGB1_4083 was performed and the resulting mutant failed to produce detectable PVD. In silico analysis of the modules in PputGB1_4083-4086 predicted a peptide sequence of Asp-Lys-Asp-Ser-Ala-Thr-Lsy-Orn, which closely matches the peptide determined by MS/MS. To extend these studies to other organisms, various Mn(II)-oxidizing and non-oxidizing isolates of P. putida, P. fluorescens, P. marincola, P. fluorescens-syringae group, P. mendocina-resinovorans group, and P. stutzerii group were screened for PVD synthesis. The PVD producers (12 out of 16 tested strains) were siderotyped and placed into four sets of differing PVD structures, some corresponding to previously characterized PVDs and some to novel PVDs. These results combined with previous studies suggested that the presence of OHAsp or the flexibility of the pyoverdine polypeptide may enable efficient binding of Mn(III). PMID:24847318

  17. Promoção de crescimento e controle de tombamento de plântulas de pepino por rizobactérias Growth promotion and damping-off control of cucumber seedling by rhizobacteria

    Cleusa Maria Mantovanello Lucon

    2008-06-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de rizobactérias, no crescimento de plântulas de pepino e no controle de tombamento, causado por Pythium aphanidermatum. Foram realizados em laboratório ensaios de: degradação de 1-aminociclopropano-1-carboxilato (ACC; colonização das raízes de plântulas de pepino; e pareamento de culturas. A identificação dos melhores isolados foi feita pela determinação das seqüências do gene 16S rDNA. Trinta e sete isolados, dos 165 testados, aumentaram a massa de matéria seca das plantas de pepino em até 63%. Desses, somente um isolado (N13 - Pseudomonas fluorescens reduziu o tombamento de plântulas em 25%; 21 isolados inibiram o crescimento micelial de P. aphanidermatum, colonizaram o sistema radicular das plantas de pepino e cresceram em presença de ACC como única fonte de nitrogênio. Dos dez isolados que apresentaram resultados satisfatórios, cinco foram identificados como pertencentes aos gêneros Bacillus, quatro Pseudomonas e um Stenotrophomonas. Dos 165 isolados de rizobactérias testados, sete possuem potencial para promover o crescimento de plantas de pepino e um para controlar o tombamento causado por P. aphanidermatum.The aim of this work was to evaluate the rhizobacteria effect on cucumber seedling growth and in the control of damping-off disease Pythium aphanidermatum. In laboratory, the following tests were carried out: degradation of 1-aminocyclopropane-1-carboxylate (ACC; colonization of cucumber root system; and, the capacity to antagonize the pathogen. The best isolates were identified through determination of 16S rDNA gene sequences. Thirty-seven isolates, among 165 tested, enhanced the dry weight of cucumber plants in up to 63%. From these 37, only one isolate (N13 - Pseudomonas fluorescens reduced the incidence of pre-emergence damping-off disease by 25%; 21 isolates antagonized P. aphanidermatum in vitro, colonized the cucumber roots, and degradated ACC, as the only

  18. Desenvolvimento de um modelo da cinética enzimática da transesterificação de óleos vegetais para produção de biodiesel = Development of the enzymatic kinetics model of vegetable oils transesterification for biodiesel production

    Alexander Dimitrov Kroumov

    2007-01-01

    Full Text Available Atualmente, a tecnologia de produção enzimática do biodiesel é mais uma alternativa em relação aos métodos químicos que utilizam catalisadores ácidos ou básicos. A enzima lipase utilizada como catalisador desse processo pode ser obtida de microrganismoscomo Pseudomonas fluorescens, P. cepacia, Candida antarctica, dentre outros. Neste trabalho, propomos um mecanismo da transesterificação de triglicerídeos catalisada por enzima lipase. O processo foi formalizado em três reações consecutivas, nas quais são formados osdiglicerídeos e monoglicerídeos. Outras três etapas intermediárias das reações envolvendo a lipase foram consideradas. A identificação dos parâmetros do modelo desenvolvido foi feita para condições reacionais em que a alimentação é feita na proporção estequiométrica dos reagentes. O modelo desenvolvido foi testado com dados experimentais em diversas condições operacionais encontradas na literatura. Os resultados das simulações mostram boa flexibilidade do modelo, ajustando os dados em várias condições de transesterificaçãoenzimática para produção de biodiesel.Currently the technology of enzymatic production of biodiesel is more promising than that based on chemical methods, using acidic orbasic catalysts. The enzyme lipase used as catalyst in this process can be isolated from microorganisms such as Pseudomonas fluorescens, P. cepacia, Candida antarctica among others. In this work, a mechanism for the transesterification of triglycerides catalyzed by lipase for production of biodiesel is proposed. The process was modeled in three consecutive reactions where diglycerides and monoglycerides were formed. Other three intermediate stages involving lipase were considered. The identification of parameters with the developed model was performed for reaction conditions where stoichiometric amount of reagents were used. The developed modelwas tested for different operational conditions with

  19. Impact of low-concentrated acidic electrolysed water obtained by membrane electrolysis on the decontamination of meat microbiota

    Brychcy Ewa

    2015-09-01

    Full Text Available The influence of acidic electrolysed water (AEW treatment on inactivation of pure bacterial cultures inoculated onto the surface of agarised media and surface microbiota of pork meat were examined. Low-concentrated AEW (low concentration of sodium chloride and low current electrolysis was generated by electrolysis (5 or 10 min of 0.001% or 0.01% NaCl solution. The number of viable microorganisms was determined using a plate count method. The effect of AEW on bacterial cell morphology were investigated using scanning electron microscopy (SEM. After treatment with AEW, a significant, about 3.00 log reduction of Pseudomonas fluorescens, Yersinia enterocolitica, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes, and Micrococcus luteus populations was observed. In the AEW treatment of pork, the highest reduction of total number of microorganisms (2.1 log reduction, yeast and moulds (2.5-2.6 log reduction, and psychrotrophs (more than 1 log reduction was observed after spraying with 0.001% NaCl subjected to 10 min electrolysis. SEM revealed disruption and lysis of E. coli and S. aureus cells treated with AEW, suggesting a bactericidal effect. Higher available chlorine concentration (0.37-8.45 mg/L, redox potential (863.1-1049.8 mV, and lower pH (2.73-3.70 had an influence on the shape of bacteria and the number of breaks in the bacterial membrane.

  20. Molecular analysis of manufactured gas plant soils for naphthalene mineralization

    Sanseverino, J.; Werner, C.; Fleming, J.; Applegate, B.M.; King, J.M.H.; Sayler, G.S.; Blackburn, J.

    1991-01-01

    New molecular tools are being developed and tested to ascertain the biodegradability of hazardous wastes by soil bacterial population. The potential for manufactured gas plant (MGP) soil bacterial populations to degrade naphthalene, as a component mixture of polynuclear aromatic hydrocarbons, was evaluated by the detection of a naphthalene biodegradative genotype by DNA probe hybridization with DNA extracts and colonies of cultured bacteria of the MGP soils. The activity of the naphthalene-degrading populations was evaluated by mineralization assays, 14 CO 2 production from 14 C-naphthalene. Direct messenger RNA (mRNA) extraction from MGP soil was evaluated as an instantaneous measure of naphthalene catabolic gene expression in MGP soil. The bioavailability of naphthalene for bacterial degradation within the MGP soils was assessed by measuring the bioluminescent response of a naphthalene-lux catabolic reporter strain Pseudomonas fluorescens HK44 (pUTK21). DNA extracted from 5 MGP soils and 1 creosote-contaminated soil and hybridized with a nahA gene probe indicated that the naphthalene degradative genes were present in all samples in the range of 0.06 to 0.95 ng/100 μl DNA extract which was calculated to represent 3.58 x 10 8 to 1.05 x 10 10 nahA positive cells/g soil. Phenanthrene, anthracene, and benzo(a)pyrene were mineralized also by some of the soils. NAH7 homologous messenger RNA transcripts were detectable in one MGP soil and in the creosote-contaminated soil

  1. Continuous Reusability using Immobilized HasApf in Chemoenzymatic Deracemization: A New Heterogeneous Enzyme Catalysis

    Hiroyuki Nagaoka

    2016-10-01

    Full Text Available This study found that the calibration curve of heme acquisition system A (HasA, a new reactive active species immobilized by a porous ceramic particle (ImHApf; immobilized HasA from Pseudomonas fluorescens can be constructed in the range of 1750–1450 cm−1 using Fourier transform infrared spectroscopy (FTIR analysis, and evaluated its catalytic efficiency. In the asymmetric oxidation of rac-1-(6-methoxynaphthalen-2-ylethanol (rac-1: a naproxen precursor, a product ketone from the (R-isomer is desymmetrized using NaBH4 and continuously reused even if treated with an organic solvent in 50 mM glycine–NaOH buffer at 40 °C in the absence of nicotinamide adenine dinucleotide (NAD(P, leading to >99% enantiomeric excess and >90% chemical yield; the activity was calculated at 0.74 ± 0.03 mU/(mg·min and the turnover number was determined to be approximately 2 × 106. It was confirmed that the other sec-alcohols such as rac-1-(2-naphthylethanol (rac-2 and m- and p-substituted rac-1-phenyl ethanols (rac-3ab–6ab using ImHApf can also yield a single stereoisomer from a racemate. Therefore, HasA immobilization can be expected to become an important tool for building an environmentally friendly system that promotes industrial sustainability.

  2. Bacterial bioeffectors modify bioactive profile and increase isoflavone content in soybean sprouts (Glycine max var Osumi).

    Algar, Elena; Ramos-Solano, Beatriz; García-Villaraco, Ana; Sierra, M Dolores Saco; Gómez, M Soledad Martín; Gutiérrez-Mañero, F Javier

    2013-09-01

    The effect of two bacterial strains to enhance bioactive contents (total phenolic compounds, total flavonoid compounds and isoflavones) and antioxidant activity on 3-day-old soybean sprouts were investigated. To identify bacterial determinants responsible for these effects, viable and UV-treated strains were delivered to wounded seeds at different concentration. Multivariate analysis performed with all the evaluated parameters indicated the different effectiveness of Stenotrophomonas maltophilia N5.18 and Pseudomonas fluorescens N21.4 based on different structural and metabolic determinants for each. N21.4 increased total phenolics and isoflavones from the genistein family, while N5.18 triggered biosynthesis of daidzein and genistein families coupled to a decrease in total phenolics, suggesting different molecular targets in the phenilpropanoid pathway. Only extracts from N5.18 treated seeds showed an improved antioxidant activity according to the β-carotene bleaching prevention method. In summary, bioeffectors from both bacterial strains are effective tools to improve soybean sprouts quality; structural elicitors from N5.18 also enhanced antioxidant activity, being the best alternative for further development of a biotechnological procedure.

  3. Role of microbial inoculation and industrial by-product phosphogypsum in growth and nutrient uptake of maize (Zea mays L.) grown in calcareous soil.

    Al-Enazy, Abdul-Aziz R; Al-Oud, Saud S; Al-Barakah, Fahad N; Usman, Adel Ra

    2017-08-01

    Alkaline soils with high calcium carbonate and low organic matter are deficient in plant nutrient availability. Use of organic and bio-fertilizers has been suggested to improve their properties. Therefore, a greenhouse experiment was conducted to evaluate the integrative role of phosphogypsum (PG; added at 0.0, 10, 30, and 50 g PG kg -1 ), cow manure (CM; added at 50 g kg -1 ) and mixed microbial inoculation (Incl.; Azotobacter chroococcum, and phosphate-solubilizing bacteria Bacillus megaterium var. phosphaticum and Pseudomonas fluorescens) on growth and nutrients (N, P, K, Fe, Mn, Zn and Cu) uptake of maize (Zea mays L.) in calcareous soil. Treatment effects on soil chemical and biological properties and the Cd and Pb availability to maize plants were also investigated. Applying PG decreased soil pH. The soil available P increased when soil was inoculated and/or treated with CM, especially with PG. The total microbial count and dehydrogenase activity were enhanced with PG+CM+Incl. Inoculated soils treated with PG showed significant increases in NPK uptake and maize plant growth. However, the most investigated treatments showed significant decreases in shoot micronutrients. Cd and Pb were not detected in maize shoots. Applying PG with microbial inoculation improved macronutrient uptake and plant growth. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  4. Est16, a New Esterase Isolated from a Metagenomic Library of a Microbial Consortium Specializing in Diesel Oil Degradation.

    Pereira, Mariana Rangel; Mercaldi, Gustavo Fernando; Maester, Thaís Carvalho; Balan, Andrea; Lemos, Eliana Gertrudes de Macedo

    2015-01-01

    Lipolytic enzymes have attracted attention from a global market because they show enormous biotechnological potential for applications such as detergent production, leather processing, cosmetics production, and use in perfumes and biodiesel. Due to the intense demand for biocatalysts, a metagenomic approach provides methods of identifying new enzymes. In this study, an esterase designated as Est16 was selected from 4224 clones of a fosmid metagenomic library, revealing an 87% amino acid identity with an esterase/lipase (accession number ADM63076.1) from an uncultured bacterium. Phylogenetic studies showed that the enzyme belongs to family V of bacterial lipolytic enzymes and has sequence and structural similarities with an aryl-esterase from Pseudomonas fluorescens and a patented Anti-Kazlauskas lipase (patent number US20050153404). The protein was expressed and purified as a highly soluble, thermally stable enzyme that showed a preference for basic pH. Est16 exhibited activity toward a wide range of substrates and the highest catalytic efficiency against p-nitrophenyl butyrate and p-nitrophenyl valerate. Est16 also showed tolerance to the presence of organic solvents, detergents and metals. Based on molecular modeling, we showed that the large alpha-beta domain is conserved in the patented enzymes but not the substrate pocket. Here, it was demonstrated that a metagenomic approach is suitable for discovering the lipolytic enzyme diversity and that Est16 has the biotechnological potential for use in industrial processes.

  5. Biodegradable gelatin-chitosan films incorporated with essential oils as antimicrobial agents for fish preservation.

    Gómez-Estaca, J; López de Lacey, A; López-Caballero, M E; Gómez-Guillén, M C; Montero, P

    2010-10-01

    Essential oils of clove (Syzygium aromaticum L.), fennel (Foeniculum vulgare Miller), cypress (Cupressus sempervirens L.), lavender (Lavandula angustifolia), thyme (Thymus vulgaris L.), herb-of-the-cross (Verbena officinalis L.), pine (Pinus sylvestris) and rosemary (Rosmarinus officinalis) were tested for their antimicrobial activity on 18 genera of bacteria, which included some important food pathogen and spoilage bacteria. Clove essential oil showed the highest inhibitory effect, followed by rosemary and lavender. In an attempt to evaluate the usefulness of these essential oils as food preservatives, they were also tested on an extract made of fish, where clove and thyme essential oils were the most effective. Then, gelatin-chitosan-based edible films incorporated with clove essential oil were elaborated and their antimicrobial activity tested against six selected microorganisms: Pseudomonas fluorescens, Shewanella putrefaciens, Photobacterium phosphoreum, Listeria innocua, Escherichia coli and Lactobacillus acidophilus. The clove-containing films inhibited all these microorganisms irrespectively of the film matrix or type of microorganism. In a further experiment, when the complex gelatin-chitosan film incorporating clove essential oil was applied to fish during chilled storage, the growth of microorganisms was drastically reduced in gram-negative bacteria, especially enterobacteria, while lactic acid bacteria remained practically constant for much of the storage period. The effect on the microorganisms during this period was in accordance with biochemical indexes of quality, indicating the viability of these films for fish preservation. 2010 Elsevier Ltd. All rights reserved.

  6. RpA, an extracellular protease similar to the metalloprotease of serralysin family, is required for pathogenicity of Ralstonia pickettii.

    Chen, C-M; Liu, J-J; Chou, C-W; Lai, C-H; Wu, L-T

    2015-10-01

    To investigate the biochemical and functional properties of an extracellular protease, RpA, in Ralstonia pickettii WP1 isolated from water supply systems. An extracellular protease was identified and characterized from R. pickettii WP1. A mutant strain WP1M2 was created from strain WP1 by mini-Tn5 transposition. The culture filtrates from WP1M2 had a lower cytotoxic effect than the parental WP1 on several mammalian cell lines. Cloning and sequence analysis revealed the Tn5 transposon inserted at a protease gene (rpA) which is 81% homologous to prtA and aprX genes of Pseudomonas fluorescens. The rpA gene encodes a 482-residue protein showing sequence similarity to metalloproteases of the serralysin family. The RpA protein was expressed in Escherichia coli using a pET expression vector and purified as a 55 kDa molecular weight protein. Furthermore, the protease activity of RpA was inhibited by protease inhibitor and heat treatment. The in vitro cytotoxic activity of R. pickettii culture filtrates was attributed to RpA protease. An extracellular protease, RpA, was identified from R. pickettii WP1 isolated from water supply system. The RpA metalloproteases is required for the pathogenicity of R. pickettii to mammalian cell lines. © 2015 The Society for Applied Microbiology.

  7. Microstructured Block Copolymer Surfaces for Control of Microbe Adhesion and Aggregation

    Ryan R. Hansen

    2014-03-01

    Full Text Available The attachment and arrangement of microbes onto a substrate is influenced by both the biochemical and physical surface properties. In this report, we develop lectin-functionalized substrates containing patterned, three-dimensional polymeric structures of varied shapes and densities and use these to investigate the effects of topology and spatial confinement on lectin-mediated microbe immobilization. Films of poly(glycidyl methacrylate-block-4,4-dimethyl-2-vinylazlactone (PGMA-b-PVDMA were patterned on silicon surfaces into line arrays or square grid patterns with 5 μm wide features and varied pitch. The patterned films had three-dimensional geometries with 900 nm film thickness. After surface functionalization with wheat germ agglutinin, the size of Pseudomonas fluorescens aggregates immobilized was dependent on the pattern dimensions. Films patterned as parallel lines or square grids with a pitch of 10 μm or less led to the immobilization of individual microbes with minimal formation of aggregates. Both geometries allowed for incremental increases in aggregate size distribution with each increase in pitch. These engineered surfaces combine spatial confinement with affinity-based capture to control the extent of microbe adhesion and aggregation, and can also be used as a platform to investigate intercellular interactions and biofilm formation in microbial populations of controlled sizes.

  8. Gold biorecovery from e-waste: An improved strategy through spent medium leaching with pH modification.

    Natarajan, Gayathri; Ting, Yen-Peng

    2015-10-01

    Rapid technological advancement and relatively short life time of electronic goods have resulted in an alarming growth rate of electronic waste which often contains significant quantities of toxic and precious metals. Compared to conventional recovery methods, bioleaching is an environmentally friendly process for metal extraction. Gold was bioleached from electronic scrap materials (ESM) via gold-cyanide complexation using cyanide produced from pure and mixed cultures of cyanogenic bacteria Chromobacterium violaceum, Pseudomonas aeruginosa and Pseudomonas fluorescens. As ESM was toxic to the bacteria, a two-step bioleaching approach was adopted where the solid waste was added to the bacterial culture after it has reached maximum growth and cyanide production during early stationary phase. Pure culture of C. violaceum showed the highest cyanide production, yielding maximum gold recovery of 11.3% at 0.5% w/v pulp density of ESM in two-step bioleaching. At the same pulp density of ESM, spent medium bioleaching using bacterial cell-free metabolites achieved gold recovery of 18%. Recovery increased to 30% when the pH of the spent medium was increased to shift the equilibrium in favor of cyanide ions production. It is demonstrated for the first time that pH modification of spent medium further improved metal solubilization and yielded higher metal recovery (compared to two-step bioleaching). Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting Gram-negative rods.

    Bombicino, Karina A; Almuzara, Marisa N; Famiglietti, Angela M R; Vay, Carlos

    2007-01-01

    To evaluate the activity of pyrrolidonyl arylamidase (PYR) for the differentiation and identification of nonfermenting gram negative rods (NFGNR), 293 isolates were tested. A 24 h culture of each test organism was prepared. From this a 108-109 cfu/mL suspension was added to 0.25 mL of sterile physiologic solution. A PYR disk was then added and the test was incubated for 30 minutes at 35-37 degrees C, at environmental atmosphere. Reading was done by adding 1 drop of cinnamaldehyde reagent. Strains of Acinetobacter baumannii, Acinetobacter haemolyticus, Alcaligenes faecalis, Bergeyella zoohelcum, Bordetella bronchiseptica, Bordetella hinzii, Brevundimonas diminuta, Brevundimonas vesicularis, Brucella ovis, Brucella spp., Brucella suis, Burkholderia cepacia complex, Moraxella catarrhalis, Moraxella lacunata, Moraxella nonliquefaciens, Moraxella osloensis, Oligella ureolytica, Pseudomonas alcaligenes, Pseudomonas mendocina, Pseudomonas pseudoalcaligenes, Pseudomonas putida, Pseudomonas stutzeri, Pseudomonas Vb3, Psychrobacter phenylpyruvicus, and Stenotrophomonas maltophilia were PYR negative. On the other hand Achromobacter piechaudii, Achromobacter denitrificans, Achromobacter xylosoxidans, Burkholderia gladioli, Chryseobacterium gleum-indologenes, Comamonas testosroni, Cupriavidus pauculus, Delftia acidovorans, Elizabethkingia meningoseptica, Myroides spp., Ochrobactrum anthropi, Pseudomonas oryzihabitans, Ralstonia pickettii, Rhizobium radiobacter, Shewanella spp., Sphingobacterium multivorum, Sphingobacterium spiritivorum, and Weeksella virosa were PYR positive. Finally, Acinetobacter lwoffii, Pseudomonas aeruginosa, Pseudomonas fluorescens, Roseomonas spp., and Sphingomonas paucimobilis-parapaucimobilis were PYR variable. PYR testing should be considered as a useful tool to facilitate the identification of NFGNR.

  10. Novel DNA sequence detection method based on fluorescence energy transfer

    Kobayashi, S.; Tamiya, E.; Karube, I.

    1987-01-01

    Recently the detection of specific DNA sequence, DNA analysis, has been becoming more important for diagnosis of viral genomes causing infections disease and human sequences related to inherited disorders. These methods typically involve electrophoresis, the immobilization of DNA on a solid support, hybridization to a complementary probe, the detection using labeled with /sup 32/P or nonisotopically with a biotin-avidin-enzyme system, and so on. These techniques are highly effective, but they are very time-consuming and expensive. A principle of fluorescene energy transfer is that the light energy from an excited donor (fluorophore) is transferred to an acceptor (fluorophore), if the acceptor exists in the vicinity of the donor and the excitation spectrum of donor overlaps the emission spectrum of acceptor. In this study, the fluorescence energy transfer was applied to the detection of specific DNA sequence using the hybridization method. The analyte, single-stranded DNA labeled with the donor fluorophore is hybridized to a probe DNA labeled with the acceptor. Because of the complementary DNA duplex formation, two fluorophores became to be closed to each other, and the fluorescence energy transfer was occurred

  11. Assessment of hemolytic activity, enzyme production and bacteriocin characterization of Bacillus subtilis LR1 isolated from the gastrointestinal tract of fish.

    Banerjee, Goutam; Nandi, Ankita; Ray, Arun Kumar

    2017-01-01

    In the present investigation, probiotic potential (antagonistic activity, enzyme production, hemolytic activity, biosafety, antibiotic sensitivity and bile tolerance level) of Bacillus subtilis LR1 was evaluated. Bacteriocin produced by the bacterial strain B. subtilis LR1 isolated from the gastrointestinal tract of Labeo rohita was purified and characterized. The molecular weight of the purified bacteriocin was ~50 kDa in 12 % Native PAGE and showed inhibitory activity against four fish pathogens such as Bacillus mycoides, Aeromonas salmonicida, Pseudomonas fluorescens and Aeromonas hydrophila. The purified bacteriocin was maximally active at temperature 40 °C and pH 7.0, while none of the tested surfactants affect the bacteriocin activity. Extracellular enzyme activity of the selected bacterial strain was also evaluated. Amylase activity was estimated to be highest (38.23 ± 1.15 µg of maltose liberated mg -1  protein ml -1 of culture filtrate) followed by cellulase and protease activity. The selected bacterium was sensitive to most of the antibiotics used in this experiment, can tolerate 0.25 % bile salt and non-hemolytic in nature. Finally, the efficiency of the proposed probiotic candidate was evaluated in in vivo condition. It was detected that the bacterial strain can effectively reduce bacterial pathogenicity in Indian major carps.

  12. Identification of Biocontrol Agents to Control the Fungal Pathogen, Geomyces destructans, in Bats

    Braunstein, S.; Cheng, T.

    2013-12-01

    The fungal pathogen Geomyces destructans (Gd) causes the disease White-nose Syndrome (WNS) in bats and is estimated to have killed millions of bats since its emergence in North America in 2006. Gd is predicted to cause the local extinction of at least three bat species if rates of decline continue unabated. Given the devastating impacts of Gd to bat populations, identifying a viable method for controlling the pathogen is pertinent for conservation of affected bat species. Our work focuses on identifying naturally-occurring skin bacteria on bats that are antagonistic to Gd that could potentially be used as a biocontrol. We cultured bacteria from skin swabs taken from wild bats (Myotis lucifugus, Eptesicus fuscus, Myotis sodalis, Perimyotis subflavus). We conducted challenge experiments to identify bacterial strains that inhibited Gd growth. Bacteria that exhibited antifungal properties were identified using 16S and gyrB markers. Our methods identified several bacteria in the Pseudomonas fluorescens complex as potential biocontrol agents. Future work will continue to test the viability of these bacteria as biocontrol agents via experimental treatments with live captive bats. The failure of previous non-biocontrol methods highlights the importance of developing these bacteria as a biologically-friendly method for controlling Gd. A bat infected with Geomyces destructans. Photo by West Virginia Division of Natural Resources Bacterial culture from the swab of a bat's wings

  13. The complete genome sequence of the plant growth-promoting bacterium Pseudomonas sp. UW4.

    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.

  14. Survival of microorganisms representing the three Domains of life inside the International Space Station

    Francesco, Canganella; Giovanna, Bianconi

    2007-09-01

    The present work was mainly focused to study the response of representative non pathogenic microorganisms to the environment inside the space vehicle at different mission stages (10, 56, and 226 days) within the frame of the Italian ENEIDE mission, from Feb to Oct 2005. Microorganisms were chosen according to their phylogenetic position and cell structures; they were representatives of the three taxonomic domains and belonged to different ecosystems (food, soil, intestinal tract, plants, deep-sea). They were the followings: Thermococcus guaymasensis (Domain Archaea); Saccharomyces cerevisiae (Domain Eucarya); Escherichia coli, Bacillus subtilis, Lactobacillus acidophilus, Enterococcus faecium, Pseudomonas fluorescens, and Rhizobium tropici (Domain Bacteria). As main environmental parameters we were interested in: a) space radiations; b) microgravity; c) temperature. The response of microorganisms was investigated in terms of survival rates, cell structure modifications, and genomic damages. The survival of cells was affected by both radiation doses and intrinsec cell features. As expected, only samples kept on the ISS for 226 days showed significant levels of mortality. Asfar as regard the effect on cell structures, these samples showed also remarkable morphological changes, particularly for Escherichia coli, Enterococcus faecium, and Saccharomyces cerevisiae. The data collected allowed to get new insights into the biological traits of microorganisms exposed to space environment during the flight on a spacecraft. Moreover, the result obtained may be important for the improvement of human conditions aboard space vehicles (nutraceuticals for astronauts and disinfections of ISS modules) and also for the potential development of closed systems devoted to vegetable productions and organic recycling.

  15. Non-pathogenic rhizobacteria interfere with the attraction of parasitoids to aphid-induced plant volatiles via jasmonic acid signalling.

    Pineda, Ana; Soler, Roxina; Weldegergis, Berhane T; Shimwela, Mpoki M; VAN Loon, Joop J A; Dicke, Marcel

    2013-02-01

    Beneficial soil-borne microbes, such as mycorrhizal fungi or rhizobacteria, can affect the interactions of plants with aboveground insects at several trophic levels. While the mechanisms of interactions with herbivorous insects, that is, the second trophic level, are starting to be understood, it remains unknown how plants mediate the interactions between soil microbes and carnivorous insects, that is, the third trophic level. Using Arabidopsis thaliana Col-0 and the aphid Myzus persicae, we evaluate here the underlying mechanisms involved in the plant-mediated interaction between the non-pathogenic rhizobacterium Pseudomonas fluorescens and the parasitoid Diaeretiella rapae, by combining ecological, chemical and molecular approaches. Rhizobacterial colonization modifies the composition of the blend of herbivore-induced plant volatiles. The volatile blend from rhizobacteria-treated aphid-infested plants is less attractive to an aphid parasitoid, in terms of both olfactory preference behaviour and oviposition, than the volatile blend from aphid-infested plants without rhizobacteria. Importantly, the effect of rhizobacteria on both the emission of herbivore-induced volatiles and parasitoid response to aphid-infested plants is lost in an Arabidopsis mutant (aos/dde2-2) that is impaired in jasmonic acid production. By modifying the blend of herbivore-induced plant volatiles that depend on the jasmonic acid-signalling pathway, root-colonizing microbes interfere with the attraction of parasitoids of leaf herbivores. © 2012 Blackwell Publishing Ltd.

  16. Two-step bioleaching of copper and gold from discarded printed circuit boards (PCB).

    Işıldar, Arda; van de Vossenberg, Jack; Rene, Eldon R; van Hullebusch, Eric D; Lens, Piet N L

    2016-11-01

    An effective strategy for environmentally sound biological recovery of copper and gold from discarded printed circuit boards (PCB) in a two-step bioleaching process was experimented. In the first step, chemolithotrophic acidophilic Acidithiobacillus ferrivorans and Acidithiobacillus thiooxidans were used. In the second step, cyanide-producing heterotrophic Pseudomonas fluorescens and Pseudomonas putida were used. Results showed that at a 1% pulp density (10g/L PCB concentration), 98.4% of the copper was bioleached by a mixture of A. ferrivorans and A. thiooxidans at pH 1.0-1.6 and ambient temperature (23±2°C) in 7days. A pure culture of P. putida (strain WCS361) produced 21.5 (±1.5)mg/L cyanide with 10g/L glycine as the substrate. This gold complexing agent was used in the subsequent bioleaching step using the Cu-leached (by A. ferrivorans and A. thiooxidans) PCB material, 44.0% of the gold was mobilized in alkaline conditions at pH 7.3-8.6, and 30°C in 2days. This study provided a proof-of-concept of a two-step approach in metal bioleaching from PCB, by bacterially produced lixiviants. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Metabolic engineering of Pediococcus acidilactici BD16 for production of vanillin through ferulic acid catabolic pathway and process optimization using response surface methodology.

    Kaur, Baljinder; Chakraborty, Debkumar; Kumar, Balvir

    2014-10-01

    Occurrence of feruloyl-CoA synthetase (fcs) and enoyl-CoA hydratase (ech) genes responsible for the bioconversion of ferulic acid to vanillin have been reported and characterized from Amycolatopsis sp., Streptomyces sp., and Pseudomonas sp. Attempts have been made to express these genes in Escherichia coli DH5α, E. coli JM109, and Pseudomonas fluorescens. However, none of the lactic acid bacteria strain having GRAS status was previously proposed for heterologous expression of fcs and ech genes for production of vanillin through biotechnological process. Present study reports heterologous expression of vanillin synthetic gene cassette bearing fcs and ech genes in a dairy isolate Pediococcus acidilactici BD16. After metabolic engineering, statistical optimization of process parameters that influence ferulic acid to vanillin biotransformation in the recombinant strain was carried out using central composite design of response surface methodology. After scale-up of the process, 3.14 mM vanillin was recovered from 1.08 mM ferulic acid per milligram of recombinant cell biomass within 20 min of biotransformation. From LCMS-ESI spectral analysis, a metabolic pathway of phenolic biotransformations was predicted in the recombinant P. acidilactici BD16 (fcs (+)/ech (+)).

  18. Efficacy of lactoferricin B in controlling ready-to-eat vegetable spoilage caused by Pseudomonas spp.

    Federico, Baruzzi; Pinto, Loris; Quintieri, Laura; Carito, Antonia; Calabrese, Nicola; Caputo, Leonardo

    2015-12-23

    The microbial content of plant tissues has been reported to cause the spoilage of ca. 30% of chlorine-disinfected fresh vegetables during cold storage. The aim of this work was to evaluate the efficacy of antimicrobial peptides in controlling microbial vegetable spoilage under cold storage conditions. A total of 48 bacterial isolates were collected from ready-to-eat (RTE) vegetables and identified as belonging to Acinetobacter calcoaceticus, Aeromonas media, Pseudomonas cichorii, Pseudomonas fluorescens, Pseudomonas jessenii, Pseudomonas koreensis, Pseudomonas putida, Pseudomonas simiae and Pseudomonas viridiflava species. Reddish or brownish pigmentation was found when Pseudomonas strains were inoculated in wounds on leaves of Iceberg and Trocadero lettuce and escarole chicory throughout cold storage. Bovine lactoferrin (BLF) and its hydrolysates (LFHs) produced by pepsin, papain and rennin, were assayed in vitro against four Pseudomonas spp. strains selected for their heavy spoiling ability. As the pepsin-LFH showed the strongest antimicrobial effect, subsequent experiments were carried out using the peptide lactoferricin B (LfcinB), well known to be responsible for its antimicrobial activity. LfcinB significantly reduced (P ≤ 0.05) spoilage by a mean of 36% caused by three out of four inoculated spoiler pseudomonads on RTE lettuce leaves after six days of cold storage. The reduction in the extent of spoilage was unrelated to viable cell density in the inoculated wounds. This is the first paper providing direct evidence regarding the application of an antimicrobial peptide to control microbial spoilage affecting RTE leafy vegetables during cold storage.

  19. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-01-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  20. Effects of Some Beneficial Bacteria in Casing Soil on Growth and Yield of Cultivated Mushroom Agaricus bisporus

    Mehmet Çetin

    2016-03-01

    Full Text Available This research was carried out to determine the interaction between some bacteria naturally existing in casing soil and Agaricus bisporus (Sylvan Hauser A15 hypha in laboratory (in vitro and cultivation (in vivo conditions, and to confirm its effects on mushroom yield. Totally 32 bacteria (3 Gram (+ and 29 Fluorescent Pseudomonads was isolated from casing soil and healthy sporophores. As a result of in vitro experiment carried out to determine the effects of bacteria on mycelium growth of A. bisporus, 24 bacterial isolates were found more effective at the rate of 2 to 115% than control treatment. To determine the effects of bacterium, chosen at the end of in vitro experiments, on mushroom yield in cultivation conditions, three experiments were established in March, May and July in 2008. At the end of experiments, bacterial isolates provided 8 – 40 % increase in total yield. Population density and change in population number related to time was observed during growing period, after the inoculation of bacterial isolates into casing soil. According to the results, Pseudomonas fluorescens (T 4/2 and Ş 8, P.putida (Ş 2/1 and Ş 10 and Bacillus mycoides (T 7/2 bacterial isolates were colonized successfully both in casing soil and sporophores.