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PubMed1998

Metabolism of ferulic acid via vanillin using a novel CoA-dependent pathway in a newly-isolated strain of Pseudomonas fluorescens.

A soil bacterium, designated Pseudomonas fluorescens AN103, was isolated based on its ability to grow on ferulic acid as a sole source of carbon and energy. In addition, this strain was found to metabolize a number of related phenolic substrates which contained a hydroxyl group at the para position of the aromatic ring. During growth on ferulic acid, transient accumulation of vanillic acid and trace amounts of protocatechuic acid were detected in the culture medium. Washed cells grown on ferulic acid readily oxidized vanillin, vanillic acid and protocatechuic acid, the three putative intermediates of the metabolic pathway. The side-chain cleavage of ferulic acid to produce vanillin was demonstrated in vitro for the first time and this enzyme-catalysed reaction was shown to have an essential requirement for CoASH, ATP and MgCl2. This conversion involved a two-step process involving a CoA ligase followed by the side-chain cleavage. The addition of NAD increased the oxidation of vanillin to vanillic acid and had an overall effect of increasing the rate of ferulic acid cleavage. The application of 13C-NMR studies in vitro revealed acetyl-CoA as the C2 side-chain cleavage product. High levels of inducible ferulate-CoA ligase and NAD-linked vanillin dehydrogenase were detected and a novel pathway for ferulic acid metabolism in this organism is proposed.

Aldehyde Oxidoreductases↗

PubMed1991

Cloning of pectate lyase gene pel from Pseudomonas fluorescens and detection of sequences homologous to pel in Pseudomonas viridiflava and Pseudomonas putida.

Pectate lyase (PL) depolymerizes pectin and other polygalacturonates (PGAs) and is thought to play a role in bacterial invasion of plants. Production of PL by the soft-rotting pathogen Pseudomonas fluorescens CY091 is regulated by Ca2+. In the presence of Ca2+, this bacterium constitutively synthesizes PL in media containing glucose, glycerol, or PGA and excretes over 87% of total PL into culture fluids. In the absence of Ca2+, the organism fails to use PGA as a carbon source and produces very low levels of PL in media containing glucose or glycerol. Of the small amount of PL produced by the bacterium in Ca(2+)-deficient media, over 78% was detected within the cells, indicating that Ca2+ is critical not only for the production but also for the secretion of PL. The pel gene, encoding an alkaline PL (pI 10.0, Mr 41,000) was cloned and located on the overlapping region of a 4.3-kb SalI and a 7.1-kb EcoRI fragment. The 7.1-kb EcoRI fragment appears to contain a promoter for pel gene expression. A 1.7-kb SalI-XhoI subfragment of the 4.3-kb SalI fragment was cloned into pUC18 to give pROTM2. Escherichia coli cells carrying pROTM2 produce 50 to 100 times more PL than do cells carrying other pectolytic constructs. Production of PL by E. coli (pROTM2) was not affected by carbon sources or by Ca2+. The pI and Mr of PL from E. coli corresponded to values for its counterpart from P. fluorescens. A 0.7-kb BglII-ClaI fragment encoding the pel structural sequence was used to detect pel homologs in various species of fluorescent pseudomonads. Homologous sequences were observed in 10 of 11 strains of P. fluorescens, P. viridiflava, and P. putida. The pel gene in fluorescent pseudomonads is well conserved and may exist and remain repressed in certain strains or species which exhibit nonpectolytic phenotypes under laboratory conditions.

Calcium↗

PubMed1982

D-Malic enzyme of Pseudomonas fluorescens.

By the enrichment culture technique 14 gram-negative bacteria and two yeast strains were isolated that used D(+)-malic acid as sole carbon source. The bacteria were identified as Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas aeruginosa and Klebsiella aerogenes. In cell-free extracts of P. fluorescens and P. putida the presence of malate dehydrogenase, D-malic enzyme (NAD-dependent) and L-malic enzyme (NADP-dependent) was demonstrated. D-Malic enzyme from P. fluorescens was purified. Stabilization of the enzyme by 50 mM ammonium sulphate an 1 mM EDTA was essential. Preparation of D-malic enzyme that gave one band with disc gel electrophoresis showed a specific activity of 4-5 U/mg. D-Malic enzyme requires divalent cations. The Km values were for malate Km = 0.3 mM and for NAD Km = 0.08 mM. The pH optimum for the reaction was found to be in the range of pH 8.1 to pH 8.8. D-Malic enzyme is partially inhibited by oxaloacetic acid, meso-tartaric acid, D-lactic acid and ATP. Determined by gel filtration and gradient gel electrophoresis, the molecular weight was approximately 175 000.

Cell-Free System↗

PubMed1988

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.

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. A mean experimental enthalpy change value of -800 kJ/mol of nitrate and a mean growth yield value of 33 g (dry weight)/mol of nitrate consumed were obtained for different concentrations of nitrate. For Pseudomonas putrefaciens, a dissimilatory ammonium producer, the nitrate consumption resulted in an accumulation of nitrite and nitrous oxide. Nitrite consumption commenced after depletion of the nitrate; consequently, two phases were noted in the heat production rate curve during growth. A mean experimental enthalpy change value of -810 kJ/mol of nitrate was obtained for different concentrations of nitrate.

Journal Article↗

PubMed2003

Cytotoxic effects of the lipopolysaccharide from Pseudomonas fluorescens on neurons and glial cells.

Pseudomonas fluorescens is an emerging pathogen closely related to Pseudomonas aeruginosa. In the present study, the effect of the lipopolysaccharide (LPS) from P. fluorescens MF37 was investigated using indicators of apoptosis and necrosis and was compared to the effect of the LPS from P. aeruginosa PAO1. Capillary electrophoresis analysis of the LPS from P. fluorescens MF37 revealed the existence of three forms of the endotoxin and the absence of homology with the LPS from P. aeruginosa. In neurons and glial cells the LPS from P. fluorescens induced major morphological changes including a condensation of the cytoplasmic proteins, a leakage of the cytoplasmic content, the formation of blebs on the nuclear membrane and a marked reorganization of the cytoskeleton. In glial cells, the LPS from P. fluorescens provoked the migration of phosphatidylserine at the surface of the cytoplasmic membrane, a sign of apoptosis, but this reaction was associated to an increase in the permeability to propidium iodide characteristic of necrosis. Biochemical studies revealed an important activation of an inducible nitric oxide synthase and a release of lactate dehydrogenase, a stable cytosolic enzyme. These results demonstrate that the LPS from P. fluorescens induces apoptosis and a concomitant and limited necrosis, reveal the unexpected cytotoxicity of this endotoxin and provide the first demonstration of the apoptotic effect of a non-aeruginosa Pseudomonas on nerve cells.

Animals↗

PubMed1996

Cloning and characterization of styrene catabolism genes from Pseudomonas fluorescens ST.

A gene bank from Pseudomonas fluorescens ST was constructed in the broad-host-range cosmid pLAFR3 and mobilized into Pseudomonas putida PaW340. Identification of recombinant cosmids containing the styrene catabolism genes was performed by screening transconjugants for growth on styrene and epoxystyrene. Transposon mutagenesis and subcloning of one of the selected genome fragments have led to the identification of three enzymatic activities: a monooxygenase activity encoded by a 3-kb PstI-EcoRI fragment and an epoxystyrene isomerase activity and an epoxystyrene reductase activity encoded by a 2.3-kb BamHI fragment. Escherichia coli clones containing the 3-kb PstI-EcoRI fragment were able to transform styrene into epoxystyrene, and those containing the 2.3-kb BamHI fragment converted epoxystyrene into phenylacetaldehyde or, only in the presence of glucose, into 2-phenylethanol. The three genes appear to be clustered and are probably encoded by the same DNA strand. In E. coli, expression of the epoxystyrene reductase gene was under the control of its own promoter, whereas the expression of the other two genes was dependent on the presence of an external vector promoter.

Acetaldehyde↗

PubMed2002

Pseudomonas fluorescens pseudobacteraemia: a cautionary lesson.

OBJECTIVES: To describe an outbreak of pseudobacteraemia caused by Pseudomonas fluorescens in a paediatric population. To document and highlight the effect this outbreak had on clinical management and the steps taken to determine the source. METHODS: A clinical and microbiological investigation was carried out into a cluster of 38 pseudobacteraemias caused by Pseudomonas fluorescens in paediatric patients over a 10 month period. RESULTS: The source of the outbreak of pseudobacteraemia was found to be contaminated lithium heparin tubes, which were being filled prior to the filling of the blood culture bottle. Cultures of the same tubes yielded Pseudomonas fluorescens. As a result of the initial positive blood cultures, clinical management was altered in 18 cases. A staff education programme was instituted and eventually resulted in a cessation of the pseudobacteraemia. CONCLUSIONS: Pseudobacteraemias are a major cause of potentially inappropriate therapy in febrile children. Attention to detail in the collection of blood cultures can help reduce this outcome. Staff involved in the collection of blood cultures need to be aware of this potential source of contamination.

Adolescent↗

PubMed2006

Detoxification and bioremediation potential of a Pseudomonas fluorescens isolate against the major Indian water pollutants.

A Pseudomonas fluorescens strain was isolated from the soil of industrial estate of Aligarh, India. This strain was resistant to some of the major Indian water pollutants, namely Cd2+, Cr6+, Cu2+, Ni2+, Pb2+, BHC, 2,4-D, mancozeb and phenols up to the levels occurring in the highly polluted regions. Moreover, the test strain seems to have a great potential for the detoxification of these pollutants. The decrease in toxicity as determined by the Allium cepa test was recorded as 62.5% for the model water containing the mixture of test heavy metals, 71.9% for the pesticides, 73.2% for phenols, and 58.5% for combination of all these toxicants. These values were obtained after 24 hours, exposure to the immobilized cells of the test isolate in the calcium alginate matrix at the concentrations of these polutants supposedly present in the highly polluted water systems in India. The efficiency of bioremediation for certain heavy metals at the same concentrations by means of immobilized cells of the test Pseudomonas fluorescens isolate was estimated to be 75.9% for cadmium, 74.2% for hexavalent chromium and 61.0% for lead during the 24 hours' treatment. In view of the preliminary work, the test isolate seems to be a good candidate for the bioremediation of water pollutants.

Biodegradation, Environmental↗

PubMed1986

Cloning and nucleotide sequence of the aspartase gene of Pseudomonas fluorescens.

The aspartase gene (aspA) of Pseudomonas fluorescens was cloned and the nucleotide sequence of the 2,066-base-pair DNA fragment containing the aspA gene was determined. The amino acid sequence of the protein deduced from the nucleotide sequence was confirmed by N- and C-terminal sequence analysis of the purified enzyme protein. The deduced amino acid composition also fitted the previous amino acid analysis results well (Takagi et al. (1984) J. Biochem. 96, 545-552). These results indicate that aspartase of P. fluorescens consists of four identical subunits with a molecular weight of 50,859, composed of 472 amino acid residues. The coding sequence of the gene was preceded by a potential Shine-Dalgarno sequence and by a few promoter-like structures. Following the stop codon there was a structure which is reminiscent of the Escherichia coli rho-independent terminator. The G + C content of the coding sequence was found to be 62.3%. Inspection of the codon usage for the aspA gene revealed as high as 80.0% preference for G or C at the third codon position. The deduced amino acid sequence was 56.3% homologous with that of the enzyme of E. coli W (Takagi et al. (1985) Nucl. Acids Res. 13, 2063-2074). Cys-140 and Cys-430 of the E. coli enzyme, which had been assigned as functionally essential (Ida & Tokushige (1985) J. Biochem. 98, 793-797), were substituted by Ala-140 and Ala-431, respectively, in the P. fluorescens enzyme.

Amino Acid Sequence↗

PubMedDate not supplied

[Characteristics of lipopolysaccharide from Pseudomonas fluorescens (biovar I)].

Lipopolysaccharide (LPS) of the Pseudomonas fluorescens strain IMV 7769 (biovar I) was isolated and investigated. Fractions of the structural parts of the LPS macromolecule, lipid A, the core oligosaccharide, and the O-specific polysaccharide (O-PS), were obtained in a homogeneous state. 2-Hydroxydecanoic, 3-hydroxydecanoic, dodecanoic, 2-hydroxydodecanoic, 3-hydroxydodecanoic, hexadecanoic, octadecanoic, hexadecenoic, and octadecenoic fatty acids were identified in lipid A. In the hydrophilic moiety of lipid A, after acid hydrolysis, several amino acids, phosphoethanolamine, glucosamine, and three unidentified peaks forming a separate cluster together with glucosamine were found. Lipid A was shown to be phosphorylated. Glucose, fucose, rhamnose, glucosamine, galactosamine, two unidentified amino sugars, 2-keto-3-deoxyoctulonic acid (KDO), heptose, ethanolamine, phosphoethanolamine, and alanine were identified in the core oligosaccharide. O-PS of the LPS consisted of repeating trisaccharide fragments that included residues of amino sugars: 4-acetamido-4,6-dideoxy-D-galactose, 2-acetamido-2,6-dideoxy-D-glucose, and 2-acetamido-2,6-dideoxy-L-glucose. During growth, the strain under study excreted exocellular LPS (ELPS) into the medium. The LPS studied was similar to the LPS of the earlier investigated strains P. fluorescens (biovar I) IMV 1152 and IMV 1433 in the structure of O-PS, but differed from them in the composition of both lipid A and the core oligosaccharide. The LPS of the strain studied differed from LPS of the type strain P. fluorescens IMV 4125 (ATCC 13525) in all characteristics determined.

Chromatography, Gas↗

PubMed2002

Analysis of rILERS, an isoleucyl-tRNA synthetase gene associated with mupirocin production by Pseudomonas fluorescens NCIMB 10586.

Some strains of Pseudomonas fluorescens produce the antibiotic mupirocin, which functions as a competitive inhibitor of isoleucyl-tRNA synthetase (ILERS). Mupirocin-producing strains of P. fluorescens must overcome the inhibitory effects of the antibiotic to avoid self-suicide. However, it is not clear how P. fluorescens protects itself from the toxic effects of mupirocin. In this report, we describe a second gene encoding isoleucyl-tRNA synthetase (rILERS) in P. fluorescens that is associated with the mupirocin biosynthetic gene cluster. Random mutagenesis of the mupirocin-producing strain, P. fluorescens 10586, resulted in a mupirocin-defective mutant disrupted in a region with similarity to ILERS, the target site for mupirocin. The ILERS gene described in the present study was sequenced and shown to be encoded by a 3093 bp ORF, which is 264 bp larger than the ILERS gene previously identified in P. fluorescens 10586. rILERS from P. fluorescens is most closely related to prokaryotic or eukaryotic sources of ILERS that are resistant to mupirocin. Interestingly, the relatedness between rILERS and the ILERS previously described in P. fluorescens 10586 was low (24% similarity), which indicates that P. fluorescens contains two isoforms of isoleucyl-tRNA synthetase.

Amino Acid Sequence↗

PubMed1998

Structure and function of the genes involved in mannitol, arabitol and glucitol utilization from Pseudomonas fluorescens DSM50106.

A DNA fragment from Pseudomonas fluorescens DSM50106 containing the genes for the uptake and utilization of mannitol, arabitol and glucitol was cloned in Escherichia coli and sequenced. Seven open reading frames (mtlEFGKDYZ) were identified on the 10031 bp fragment. The deduced amino acid sequences of the first four open reading frames (mtlEFGK) revealed significant similarity to the components of the maltose transport system in E. coli and Salmonella typhimurium. The gene mtlD encoding a polyol dehydrogenase was located downstream of mtlK. The deduced proteins of the last two genes on the fragment showed a high similarity to a fructokinase from Vibrio alginolyticus (MtlZ) and a xylulose kinase from Streptomyces rubiginosus (MtlY), respectively. Both genes were expressed in E. coli. MtlZ phosphorylated fructose, glucose and glucitol whereas MtlY was highly specific for xylulose. Upstream of mtlE, a putative promoter/operator region was identified by promoter probe studies which was active in P. fluorescens but not in E. coli.

Aldehyde Reductase↗

PubMed2005

Microarray analysis of the gene expression profile induced by the endophytic plant growth-promoting rhizobacteria, Pseudomonas fluorescens FPT9601-T5 in Arabidopsis.

Pseudomonas fluorescens FPT9601-T5 was originally identified as an endophytic plant growth-promoting rhizobacteria (PGPR) on tomato. To perform a molecular dissecttion of physiological and biochemical changes occurring in the host triggered by P. fluorescens FPT9601-T5 colonization, the model plant Arabidopsis was used in this study. Root colonization of Arabidopsis with P. fluorescens FPT9601-T5 promoted plant growth later than three weeks after inoculation and partially suppressed disease symptoms caused by Pseudomonas syringae pv. tomato DC3000, indicating that P. fluorescens FPT9601-T5 acted as a PGPR on Arabidopsis. To obtain a global view on transcript modification during the Arabidopsis-FPT9601-T5 interaction, we performed microarray analysis using Affymetrix Genechip probe arrays representing approximately 22,800 genes. The results showed that 95 and 105 genes were up- or down-regulated, respectively, more than twofold in FPT9601-T5-treated Arabidopsis plants as compared with control plants. Those up-regulated included genes involved in metabolism, signal transduction, and stress response. Noteworthy, upon FPT9601-T5 colonization, putative auxin-regulated genes and nodulin-like genes were up-regulated, and some ethylene-responsive genes were down-regulated. Our results suggest that P. fluorescens FPT9601-T5 triggered plant responses in a manner similar to known PGPR and, at least in some aspects, to rhizobia.

Arabidopsis↗

PubMedDate not supplied

[Pseudobactin and pseudobactin A variants: new pyoverdin type peptide siderophores from Pseudomonas fluorescens "E2"].

From a strain of Pseudomonas fluorescens pseudobactin and several related compounds were isolated and their structures were elucidated. In this way a reference compound (5) could be obtained for the unambiguous determination of the absolute configuration of C-1 of the pyoverdin chromophore in newly isolated representatives of this class.

Amino Acid Sequence↗

PubMed1977

Induction of polymyxin resistance in Pseudomonas fluorescens by phosphate limitation.

Shift of Pseudomonas fluorescens NCMB 129 from a a phosphate rich into a phosphate limited medium results in a reduction of the membrane phospholipids phosphatidylethanolamine, phosphatidylglycerol and cardiolipin. Concomitantly a positively charged ornithine amide lipid is synthesized. The gradual increase of this lipid is paralleled by an increasing resistance to polymyxin B. The binding capacities of intact cells, and isolated inner and outer membranes for the antibiotic are reduced in the resistant organisms. It is discussed that the observed effect could be circumstantial evidence that the positively charged polymyxin B needs negatively charged receptors in biological membranes in order to exert its antibiotic activity.

Cardiolipins↗

PubMed2001

A relationship between RP4 plasmid acquisition and phenotypic changes in Pseudomonas fluorescens R2fN.

The physiological behaviour of Pseudomonas fluorescens strain R2fN was compared to that of transconjugants [R2fN(RP4)], and two aggregation phenotypes were identified (Agr- and Agr+). Agr+ phenotype is characterized by the appearance of macroscopic aggregates when cells are growing in liquid media. Transconjugants exhibited Agr+ phenotype whereas wild type strain represented Agr-. Evidence is presented to support correlation between Agr+ phenotype acquisition and the presence of the broad-host range plasmid RP4 in strain R2fN. In addition, according to bacterial adherence to hydrocarbon test the transconjugant cells appeared to be very hydrophilic whereas wild type R2fN cells were hydrophobic.

Bacterial Adhesion↗

PubMed2001

Decolourisation of molasses wastewater by cells of Pseudomonas fluorescens immobilised on porous cellulose carrier.

Pseudomonas fluorescens isolated from soil samples contaminated with molasses, decolourised molasses wastewater (MWW) samples up to 76% under non-sterile conditions in four days at 30 degrees C. Immobilised cells could be reused for decolourisation activity. However, in subsequent cycles, this was found to decrease from 76% to 50% and from 50% to 24%. Decolourisation activity was regenerated from 30% to 45% by recultivating the immobilised cells in a fresh growth medium. Cellulose carrier coated with collagen was found to be most effective carrier, which produced the highest decolourisation activity of 94% in a 4-day process. This carrier could be reused with 50% of the decolourisation activity retained until the seventh day.

Cells, Immobilized↗

PubMed1993

Crystallization and preliminary X-ray crystallographic analysis of arylesterase from Pseudomonas fluorescens.

Large crystals of arylesterase from Pseudomonas fluorescens have been grown at room temperature using ammonium sulfate as a precipitant. They grow to dimensions of 0.7 x 0.7 x 0.6 mm3 within a month. The crystals belong to the trigonal space group P3(1) (or P3(2)), with unit cell dimensions of a = 147.12 A and c = 131.08 A. The asymmetric unit seems to contain six molecules of dimeric arylesterase, with corresponding crystal volume per protein mass (VM) of 2.53 A3/Da and solvent fraction of 51.5% by volume. The crystals diffract to at least 2.2 A Bragg spacing when exposed to X-rays from a rotating-anode source. X-ray data have been collected to 2.9 A Bragg spacing from native crystals.

Carboxylic Ester Hydrolases↗