Interspecies Quorum Sensing as a Stress-Anticipation Signal in E. coli

DEFF Research Database (Denmark)

Høyland-Kroghsbo, Nina Molin

in the bacterial cell-cell communication field is why E. coli harbors SdiA, an orphan quorum sensing receptor that is activated in response to AHL quorum sensing molecules produced by other Gram-negative species. The overall aim of this PhD thesis was to investigate to what degree AHL quorum sensing signals...... are exploited by E. coli to increase its chances of surviving potential environmental threats. This thesis uncovers the first quorum sensing-regulated bacteriophage defense mechanism, which serves to protect E. coli against infection by the bacteriophage viruses λ and χ. Investigating the regulatory mechanism...... underlying the quorum sensing regulated defense mechanism, led to the discovery that AHL activates expression of cnu, encoding an Hha-family protein that interacts with the global regulatory protein H-NS, and potentially modifies its functions. Inspired by the discovery that AHL protects E. coli from...

Application of an E. coli signal sequence as a versatile inclusion body tag.

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Jong, Wouter S P; Vikström, David; Houben, Diane; van den Berg van Saparoea, H Bart; de Gier, Jan-Willem; Luirink, Joen

2017-03-21

Heterologous protein production in Escherichia coli often suffers from bottlenecks such as proteolytic degradation, complex purification procedures and toxicity towards the expression host. Production of proteins in an insoluble form in inclusion bodies (IBs) can alleviate these problems. Unfortunately, the propensity of heterologous proteins to form IBs is variable and difficult to predict. Hence, fusing the target protein to an aggregation prone polypeptide or IB-tag is a useful strategy to produce difficult-to-express proteins in an insoluble form. When screening for signal sequences that mediate optimal targeting of heterologous proteins to the periplasmic space of E. coli, we observed that fusion to the 39 amino acid signal sequence of E. coli TorA (ssTorA) did not promote targeting but rather directed high-level expression of the human proteins hEGF, Pla2 and IL-3 in IBs. Further analysis revealed that ssTorA even mediated IB formation of the highly soluble endogenous E. coli proteins TrxA and MBP. The ssTorA also induced aggregation when fused to the C-terminus of target proteins and appeared functional as IB-tag in E. coli K-12 as well as B strains. An additive effect on IB-formation was observed upon fusion of multiple ssTorA sequences in tandem, provoking almost complete aggregation of TrxA and MBP. The ssTorA-moiety was successfully used to produce the intrinsically unstable hEGF and the toxic fusion partner SymE, demonstrating its applicability as an IB-tag for difficult-to-express and toxic proteins. We present proof-of-concept for the use of ssTorA as a small, versatile tag for robust E. coli-based expression of heterologous proteins in IBs.

Purification and characterization of the bifunctional uridylyltransferase and the signal transducing proteins GlnB and GlnK from Herbaspirillum seropedicae.

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Bonatto, Ana C; Couto, Gustavo H; Souza, Emanuel M; Araújo, Luiza M; Pedrosa, Fabio O; Noindorf, Lilian; Benelli, Elaine M

2007-10-01

GlnD is a bifunctional uridylyltransferase/uridylyl-removing enzyme that has a central role in the general nitrogen regulatory system NTR. In enterobacteria, GlnD uridylylates the PII proteins GlnB and GlnK under low levels of fixed nitrogen or ammonium. Under high ammonium levels, GlnD removes UMP from these proteins (deuridylylation). The PII proteins are signal transduction elements that integrate the signals of nitrogen, carbon and energy, and transduce this information to proteins involved in nitrogen metabolism. In Herbaspirillum seropedicae, an endophytic diazotroph isolated from grasses, several genes coding for proteins involved in nitrogen metabolism have been identified and cloned, including glnB, glnK and glnD. In this work, the GlnB, GlnK and GlnD proteins of H. seropedicae were overexpressed in their native forms, purified and used to reconstitute the uridylylation system in vitro. The results show that H. seropedicae GlnD uridylylates GlnB and GlnK trimers producing the forms PII (UMP)(1), PII (UMP)(2) and PII (UMP)(3), in a reaction that requires 2-oxoglutarate and ATP, and is inhibited by glutamine. The quantification of these PII forms indicates that GlnB was more efficiently uridylylated than GlnK in the system used.

Enhanced target-specific signal detection using an Escherichia coli lysate in multiplex microbead immunoassays with E. coli-derived recombinant antigens.

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Crestani, Sandra; Leitolis, Amanda; Lima, Lucianna Freitas Oliveira; Krieger, Marco A; Foti, Leonardo

2016-08-01

Diverse techniques have been developed to analyze antibody-mediated responses to infections. However, the most common tests, i.e., enzyme-linked immunosorbent assays, require separate reactions for each antigen and consequently necessitate large sample volumes. Luminex technology allows the detection of multiple antibodies in a single experiment, but nonspecific binding can impair the results. Therefore, we examined the use of Escherichia coli lysates to reduce nonspecific binding and improve the results of liquid microarrays based on Luminex technology. Anti-bacteria antibodies were detected in human serum samples, as evidenced by high median fluorescence intensity (MFI) in assays performed with paramagnetic microspheres coupled with E. coli lysates. Moreover, the addition of an E. coli lysate as a blocker reduced the nonspecific binding of antigens produced by E. coli in a concentration-dependent manner. Tris-HCl reduced MFI values in negative samples, but did not affect MFI for positive samples. For microspheres coupled with different antigens, an E. coli lysate blocker significantly improved the fluorescence signals from positive samples. The addition of Tris-HCl and the E. coli lysate induced antigen-specific differences in MFI. This combination of the E. coli lysate blocker and Tris-HCl yielded a statistically significant improvement in MFI in the assays for Chagas disease and hepatitis C virus samples. However, for the Treponema pallidum p47 antigen improvement in MFI was only observed for the preparation with the E. coli blocker at a concentration of 3%. In conclusion, the addition of an E. coli lysate and Tris-HCl to the microarray assay reduced the nonspecific binding of human anti-bacteria antibodies and, therefore, increased the specific MFI. Copyright © 2016 Elsevier B.V. All rights reserved.

Consumer involvement with products: comparison of PII and NIP scales in the Brazilian context

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Victor Manoel Cunha de Almeida

2014-05-01

Full Text Available This study aims to evaluate the extent to which two scales of consumer involvement with products converge: PII (Personal Involvement Inventory, by Zaichkowsky (1994, and NIP (New Involvement Profile, by Jain and Srinivasan (1990. The literature review encompasses the main studies on measuring the involvement of consumers with products. Data was collected through a survey that was applied to a nonprobabilistic quota sample of undergraduate students from different institutions across the state of Rio de Janeiro. A total of 1,122 questionnaires were collected, of which 1,025 (91.4% were considered valid. In order to investigate the different levels of consumer involvement through different product categories, four products were used – sneakers, mobile phone, sports drinks and soft drinks. ANOVA and post hoc tests were used to verify the existence of significant difference on answers among product groups. This study’s substantive hypothesis, the degree of convergence between the classification results of the PII and NIP scales, was verified in two ways: through Spearman’s non-parametric correlation test and through the observation of the scales’ similar classification proportion rates. The scores’ independence was evaluated through the nonparametric Chi-Square test. Results show high classification convergence. The main contribution of this study is thus to empirically test the PII and NIP scales in the Brazilian context. Furthermore, the convergence of the scores of these scales suggests the possibility of comparing results of studies, using either scale.

Modelling the interactions between Pseudomonas putida and Escherichia coli O157:H7 in fish-burgers: use of the lag-exponential model and of a combined interaction index.

Science.gov (United States)

Speranza, B; Bevilacqua, A; Mastromatteo, M; Sinigaglia, M; Corbo, M R

2010-08-01

The objective of the current study was to examine the interactions between Pseudomonas putida and Escherichia coli O157:H7 in coculture studies on fish-burgers packed in air and under different modified atmospheres (30 : 40 : 30 O(2) : CO(2) : N(2), 5 : 95 O(2) : CO(2) and 50 : 50 O(2) : CO(2)), throughout the storage at 8 degrees C. The lag-exponential model was applied to describe the microbial growth. To give a quantitative measure of the occurring microbial interactions, two simple parameters were developed: the combined interaction index (CII) and the partial interaction index (PII). Under air, the interaction was significant (P exponential growth phase (CII, 1.72), whereas under the modified atmospheres, the interactions were highly significant (P exponential and in the stationary phase (CII ranged from 0.33 to 1.18). PII values for E. coli O157:H7 were lower than those calculated for Ps. putida. The interactions occurring into the system affected both E. coli O157:H7 and pseudomonads subpopulations. The packaging atmosphere resulted in a key element. The article provides some useful information on the interactions occurring between E. coli O157:H7 and Ps. putida on fish-burgers. The proposed index describes successfully the competitive growth of both micro-organisms, giving also a quantitative measure of a qualitative phenomenon.

Effect of signal peptide on stability and folding of Escherichia coli thioredoxin.

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Pranveer Singh

Full Text Available The signal peptide plays a key role in targeting and membrane insertion of secretory and membrane proteins in both prokaryotes and eukaryotes. In E. coli, recombinant proteins can be targeted to the periplasmic space by fusing naturally occurring signal sequences to their N-terminus. The model protein thioredoxin was fused at its N-terminus with malE and pelB signal sequences. While WT and the pelB fusion are soluble when expressed, the malE fusion was targeted to inclusion bodies and was refolded in vitro to yield a monomeric product with identical secondary structure to WT thioredoxin. The purified recombinant proteins were studied with respect to their thermodynamic stability, aggregation propensity and activity, and compared with wild type thioredoxin, without a signal sequence. The presence of signal sequences leads to thermodynamic destabilization, reduces the activity and increases the aggregation propensity, with malE having much larger effects than pelB. These studies show that besides acting as address labels, signal sequences can modulate protein stability and aggregation in a sequence dependent manner.

Effect of signal peptide on stability and folding of Escherichia coli thioredoxin.

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Singh, Pranveer; Sharma, Likhesh; Kulothungan, S Rajendra; Adkar, Bharat V; Prajapati, Ravindra Singh; Ali, P Shaik Syed; Krishnan, Beena; Varadarajan, Raghavan

2013-01-01

The signal peptide plays a key role in targeting and membrane insertion of secretory and membrane proteins in both prokaryotes and eukaryotes. In E. coli, recombinant proteins can be targeted to the periplasmic space by fusing naturally occurring signal sequences to their N-terminus. The model protein thioredoxin was fused at its N-terminus with malE and pelB signal sequences. While WT and the pelB fusion are soluble when expressed, the malE fusion was targeted to inclusion bodies and was refolded in vitro to yield a monomeric product with identical secondary structure to WT thioredoxin. The purified recombinant proteins were studied with respect to their thermodynamic stability, aggregation propensity and activity, and compared with wild type thioredoxin, without a signal sequence. The presence of signal sequences leads to thermodynamic destabilization, reduces the activity and increases the aggregation propensity, with malE having much larger effects than pelB. These studies show that besides acting as address labels, signal sequences can modulate protein stability and aggregation in a sequence dependent manner.

Investigations of Escherichia coli promoter sequences with artificial neural networks: new signals discovered upstream of the transcriptional startpoint

DEFF Research Database (Denmark)

Pedersen, Anders Gorm; Engelbrecht, Jacob

1995-01-01

We present a novel method for using the learning ability of a neural network as a measure of information in local regions of input data. Using the method to analyze Escherichia coli promoters, we discover all previously described signals, and furthermore find new signals that are regularly spaced...

Thiophenone Attenuates Enteropathogenic Escherichia coli O103:H2 Virulence by Interfering with AI-2 Signaling.

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Witsø, Ingun Lund; Valen Rukke, Håkon; Benneche, Tore; Aamdal Scheie, Anne

2016-01-01

Interference with bacterial quorum sensing communication provides an anti-virulence strategy to control pathogenic bacteria. Here, using the Enteropathogenic E. coli (EPEC) O103:H2, we showed for the first time that thiophenone TF101 reduced expression of lsrB; the gene encoding the AI-2 receptor. Combined results of transcriptional and phenotypic analyses suggested that TF101 interfere with AI-2 signalling, possibly by competing with AI-2 for binding to LsrB. This is supported by in silico docking prediction of thiophenone TF101 in the LsrB pocket. Transcriptional analyses furthermore showed that thiophenone TF101 interfered with expression of the virulence genes eae and fimH. In addition, TF101 reduced AI-2 induced E. coli adhesion to colorectal adenocarcinoma cells. TF101, on the other hand, did not affect epinephrine or norepinephrine enhanced E. coli adhesion. Overall, our results showed that thiophenone TF101 interfered with virulence expression in E. coli O103:H2, suggestedly by interfering with AI-2 mediated quorum sensing. We thus conclude that thiophenone TF101 might represent a promising future anti-virulence agent in the fight against pathogenic E. coli.

Role of PII proteins in nitrogen fixation control of Herbaspirillum seropedicae strain SmR1.

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Noindorf, Lilian; Bonatto, Ana C; Monteiro, Rose A; Souza, Emanuel M; Rigo, Liu U; Pedrosa, Fabio O; Steffens, Maria B R; Chubatsu, Leda S

2011-01-11

The PII protein family comprises homotrimeric proteins which act as transducers of the cellular nitrogen and carbon status in prokaryotes and plants. In Herbaspirillum seropedicae, two PII-like proteins (GlnB and GlnK), encoded by the genes glnB and glnK, were identified. The glnB gene is monocistronic and its expression is constitutive, while glnK is located in the nlmAglnKamtB operon and is expressed under nitrogen-limiting conditions. In order to determine the involvement of the H. seropedicae glnB and glnK gene products in nitrogen fixation, a series of mutant strains were constructed and characterized. The glnK- mutants were deficient in nitrogen fixation and they were complemented by plasmids expressing the GlnK protein or an N-truncated form of NifA. The nitrogenase post-translational control by ammonium was studied and the results showed that the glnK mutant is partially defective in nitrogenase inactivation upon addition of ammonium while the glnB mutant has a wild-type phenotype. Our results indicate that GlnK is mainly responsible for NifA activity regulation and ammonium-dependent post-translational regulation of nitrogenase in H. seropedicae.

Efficient secretory expression of recombinant proteins in Escherichia coli with a novel actinomycete signal peptide.

Science.gov (United States)

Cui, Yanbing; Meng, Yiwei; Zhang, Juan; Cheng, Bin; Yin, Huijia; Gao, Chao; Xu, Ping; Yang, Chunyu

2017-01-01

In well-established heterologous hosts, such as Escherichia coli, recombinant proteins are usually intracellular and frequently found as inclusion bodies-especially proteins possessing high rare codon content. In this study, successful secretory expression of three hydrolases, in a constructed inducible or constitutive system, was achieved by fusion with a novel signal peptide (Kp-SP) from an actinomycete. The signal peptide efficiently enabled extracellular protein secretion and also contributed to the active expression of the intracellular recombinant proteins. The thermophilic α-amylase gene of Bacillus licheniformis was fused with Kp-SP. Both recombinants, carrying inducible and constitutive plasmids, showed remarkable increases in extracellular and intracellular amylolytic activity. Amylase activity was observed to be > 10-fold in recombinant cultures with the constitutive plasmid, pBSPPc, compared to that in recombinants lacking Kp-SP. Further, the signal peptide enabled efficient secretion of a thermophilic cellulase into the culture medium, as demonstrated by larger halo zones and increased enzymatic activities detected in both constructs from different plasmids. For heterologous proteins with a high proportion of rare codons, it is difficult to obtain high expression in E. coli owing to the codon bias. Here, the fusion of an archaeal homologue of the amylase encoding gene, FSA, with Kp-SP resulted in > 5-fold higher extracellular activity. The successful extracellular expression of the amylase indicated that the signal peptide also contributed significantly to its active expression and signified the potential value of this novel and versatile signal peptide in recombinant protein production. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis and processing in Escherichia coli of human leucocyte interferon fused with the signal sequence of Bacillus amyloliquefaciens a-amylase

International Nuclear Information System (INIS)

Sorokin, A.V.; Avakov, A.S.; Bogush, V.G.

1985-01-01

Earlier, the authors reported cloning of the alpha-amylase gene of B. amyloliquefaciens in B. subtilis and E. coli. Currently, the authors report results on the expression of the hybrid gene consisting of the DNA fragment coding for the leader part of B. amyloliquefaciens alpha-amylase and the structural part of the human interferon alpha-2 in E. coli cells. This gene contains an additional methionine codon at the 5'-terminal, which codes for the interferon structure (without its own signal peptide). The interferon gene was inserted into plasmid /sub p/TG 278 at the cleavage site of EcoRI. The structure of the plasmid thus obtained the signal peptide of amylase, five amino acids (Val-Gly-Glu-Phe-Met), and the structural part of the interferon. The E. coli C600 cells carrying plasmid pTGA6 were used to study interferon secretions. The interferon activity was determined radioimmunologically with the use of monoclonal anti-bodies NK2

Role of PII proteins in nitrogen fixation control of Herbaspirillum seropedicae strain SmR1

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Steffens Maria BR

2011-01-01

Full Text Available Abstract Background The PII protein family comprises homotrimeric proteins which act as transducers of the cellular nitrogen and carbon status in prokaryotes and plants. In Herbaspirillum seropedicae, two PII-like proteins (GlnB and GlnK, encoded by the genes glnB and glnK, were identified. The glnB gene is monocistronic and its expression is constitutive, while glnK is located in the nlmAglnKamtB operon and is expressed under nitrogen-limiting conditions. Results In order to determine the involvement of the H. seropedicae glnB and glnK gene products in nitrogen fixation, a series of mutant strains were constructed and characterized. The glnK- mutants were deficient in nitrogen fixation and they were complemented by plasmids expressing the GlnK protein or an N-truncated form of NifA. The nitrogenase post-translational control by ammonium was studied and the results showed that the glnK mutant is partially defective in nitrogenase inactivation upon addition of ammonium while the glnB mutant has a wild-type phenotype. Conclusions Our results indicate that GlnK is mainly responsible for NifA activity regulation and ammonium-dependent post-translational regulation of nitrogenase in H. seropedicae.

Proteomic analysis of Herbaspirillum seropedicae reveals ammonium-induced AmtB-dependent membrane sequestration of PII proteins.

Science.gov (United States)

Huergo, Luciano F; Noindorf, Lilian; Gimenes, Camila; Lemgruber, Renato S P; Cordellini, Daniela F; Falarz, Lucas J; Cruz, Leonardo M; Monteiro, Rose A; Pedrosa, Fábio O; Chubatsu, Leda S; Souza, Emanuel M; Steffens, Maria B R

2010-07-01

This study was aimed at describing the spectrum and dynamics of proteins associated with the membrane in the nitrogen-fixing bacterium Herbaspirillum seropedicae according to the availability of fixed nitrogen. Using two-dimensional electrophoresis we identified 79 protein spots representing 45 different proteins in the membrane fraction of H. seropedicae. Quantitative analysis of gel images of membrane extracts indicated two spots with increased levels when cells were grown under nitrogen limitation in comparison with nitrogen sufficiency; these spots were identified as the GlnK protein and as a conserved noncytoplasmic protein of unknown function which was encoded in an operon together with GlnK and AmtB. Comparison of gel images of membrane extracts from cells grown under nitrogen limitation or under the same regime but collected after an ammonium shock revealed two proteins, GlnB and GlnK, with increased levels after the shock. The P(II) proteins were not present in the membrane fraction of an amtB mutant. The results reported here suggest that changes in the cellular localization of P(II) might play a role in the control of nitrogen metabolism in H. seropedicae.

Yeast hexokinase: substrate-induced association--dissociation reactions in the binding of glucose to hexokinase P-II.

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Hoggett, J G; Kellett, G L

1976-06-15

A method is described for the purification of native hexokinases P-I and P-II from yeast using preparative isoelectric focussing to separate the isozymes. The binding of glucose to hexokinase P-II, and the effect of this on the monomer--dimer association--dissociation reaction have been investigated quantitatively by a combination of titrations of intrinsic protein fluorescence and equilibrium ultracentrifugation. Association constants for the monomer-dimer reaction decreased with increasing pH, ionic strength and concentration of glucose. Saturating concentrations of glucose did not bring about complete dissociation of the enzyme showing that both sites were occupired in the dimer. At pH 8.0 and high ionic strength, where the enzyme existed as monomer, the dissociation constant of the enzyme-glucose complex was 3 X 10(-4) mol 1(-1) and was independent of the concentration of enzyme. Binding to the dimeric form at low pH and ionic strength (I=0.02 mol 1(-1), pH less than 7.5) was also independent of enzyme concentration (in the range 10-1000 mug ml-1) but was much weaker. The process could be described by a single dissociation constant, showing that the two available sites on the dimer were equivalent and non-cooperative; values of the intrinsic dissociation constant varied from 2.5 X 10(-3) mol 1(-1) at pH 7.0 to 6 X 10(-3) at pH 6.5. Under intermediate conditions (pH 7.0, ionic strength=0.15 mol 1(-1)), where monomer and dimer coexisted, the binding of glucose showed weak positive cooperatively (Hill coefficient 1.2); in addition, the binding was dependent upon the concentration of enzyme in the direction of stronger binding at lower concentrations. The results show that the phenomenon of half-sites reactivity observed in the binding of glucose to crystalline hexokinase P-II does not occur in solution; the simplest explanation of our finding the two sites to be equivalent is that the dimer results from the homologous association of two identical subunits.

Datasets will not be made accessible to the public due to the fact that they include household level data with PII.

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U.S. Environmental Protection Agency — Datasets will not be made accessible to the public due to the fact that they include household level data with PII. This dataset is not publicly accessible because:...

Phosphorylation near nuclear localization signal regulates nuclear import of adenomatous polyposis coli protein

OpenAIRE

Zhang, Fang; White, Raymond L.; Neufeld, Kristi L.

2000-01-01

Mutation of the adenomatous polyposis coli (APC) gene is an early step in the development of colorectal carcinomas. APC protein is located in both the cytoplasm and the nucleus. The objective of this study was to define the nuclear localization signals (NLSs) in APC protein. APC contains two potential NLSs comprising amino acids 1767–1772 (NLS1APC) and 2048–2053 (NLS2APC). Both APC NLSs are well conserved among human, mouse, rat, and fly. NLS1APC and NLS2APC each w...

Tissue localization and extracellular matrix degradation by PI, PII and PIII snake venom metalloproteinases: clues on the mechanisms of venom-induced hemorrhage.

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Cristina Herrera

2015-04-01

Full Text Available Snake venom hemorrhagic metalloproteinases (SVMPs of the PI, PII and PIII classes were compared in terms of tissue localization and their ability to hydrolyze basement membrane components in vivo, as well as by a proteomics analysis of exudates collected in tissue injected with these enzymes. Immunohistochemical analyses of co-localization of these SVMPs with type IV collagen revealed that PII and PIII enzymes co-localized with type IV collagen in capillaries, arterioles and post-capillary venules to a higher extent than PI SVMP, which showed a more widespread distribution in the tissue. The patterns of hydrolysis by these three SVMPs of laminin, type VI collagen and nidogen in vivo greatly differ, whereas the three enzymes showed a similar pattern of degradation of type IV collagen, supporting the concept that hydrolysis of this component is critical for the destabilization of microvessel structure leading to hemorrhage. Proteomic analysis of wound exudate revealed similarities and differences between the action of the three SVMPs. Higher extent of proteolysis was observed for the PI enzyme regarding several extracellular matrix components and fibrinogen, whereas exudates from mice injected with PII and PIII SVMPs had higher amounts of some intracellular proteins. Our results provide novel clues for understanding the mechanisms by which SVMPs induce damage to the microvasculature and generate hemorrhage.

Identifying mechanisms by which Escherichia coli O157:H7 subverts interferon-γ mediated signal transducer and activator of transcription-1 activation.

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Nathan K Ho

Full Text Available Enterohemorrhagic Escherichia coli serotype O157:H7 is a food borne enteric bacterial pathogen that causes significant morbidity and mortality in both developing and industrialized nations. E. coli O157:H7 infection of host epithelial cells inhibits the interferon gamma pro-inflammatory signaling pathway, which is important for host defense against microbial pathogens, through the inhibition of Stat-1 tyrosine phosphorylation. The aim of this study was to determine which bacterial factors are involved in the inhibition of Stat-1 tyrosine phosphorylation. Human epithelial cells were challenged with either live bacteria or bacterial-derived culture supernatants, stimulated with interferon-gamma, and epithelial cell protein extracts were then analyzed by immunoblotting. The results show that Stat-1 tyrosine phosphorylation was inhibited by E. coli O157:H7 secreted proteins. Using sequential anion exchange and size exclusion chromatography, YodA was identified, but not confirmed to mediate subversion of the Stat-1 signaling pathway using isogenic mutants. We conclude that E. coli O157:H7 subverts Stat-1 tyrosine phosphorylation in response to interferon-gamma through a still as yet unidentified secreted bacterial protein.

Mechanism underlying the inner membrane retention of Escherichia coli lipoproteins caused by Lol avoidance signals.

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Hara, Takashi; Matsuyama, Shin-ichi; Tokuda, Hajime

2003-10-10

Escherichia coli lipoproteins are localized to either the inner or outer membrane depending on the residue at position 2. The inner membrane retention signal, Asp at position 2 in combination with certain residues at position 3, functions as a Lol avoidance signal, i.e. the signal inhibits the recognition of lipoproteins by LolCDE that releases lipoproteins from the inner membrane. To understand the role of the residue at position 2, outer membrane-specific lipoproteins with Cys at position 2 were subjected to chemical modification followed by the release reaction in reconstituted proteoliposomes. Sulfhydryl-specific introduction of nonprotein molecules or a negative charge to Cys did not inhibit the LolCDE-dependent release. In contrast, oxidation of Cys to cysteic acid resulted in generation of the Lol avoidance signal, indicating that the Lol avoidance signal requires a critical length of negative charge at the second residue. Furthermore, not only modification of the carboxylic acid of Asp at position 2 but also that of the amine of phosphatidylethanolamine abolished the Lol avoidance function. Based on these results, the Lol avoidance mechanism is discussed.

Atomic physics at the Argonne PII ECR [electron cyclotron resonance] Ion Source

International Nuclear Information System (INIS)

Dunford, R.W.; Berry, H.G.; Billquist, P.J.; Pardo, R.C.; Zabransky, B.J.; Bakke, E.; Groeneveld, K.O.; Hass, M.; Raphaelian, M.L.A.

1987-01-01

An atomic physics beam line has been set up at the Argonne PII ECR Ion Source. The source is on a 350-kV high-voltage platform which is a unique feature of particular interest in work on atomic collisions. We describe our planned experimental program which includes: measurement of state-selective electron-capture cross sections, studies of doubly-excited states, precision spectroscopy of few-electron ions, tests of quantum electrodynamics, and studies of polarization transfer using optically pumped polarized alkali targets. The first experiments will be measurements of cross sections for electron capture into specific nl subshells in ion-atom collisions. Our method is to observe the characteristic radiation emitted after capture using a VUV spectrometer. Initial data from these experiments are presented. 12 refs., 4 figs

Yeast hexokinase. A fluorescence temperature-jump study of the kinetics of the binding of glucose to the monomer forms of hexokinases P-I and P-II.

Science.gov (United States)

Hoggett, J G; Kellett, G L

1976-09-15

The binding of glucose to the monomeric forms of hexokinases P-I and P-II in Tris and phosphate buffers at pH 8.0 in the presence of 1 mol l-1 KCl has been studied using the fluorescence temperature-jump technique. For both isozymes only one relaxation time was observed; values of tau-1 increased linearly with increasing concentration of free reacting partners. The apparent second-order rate constant for association was about 2 X 10(6) 1 mol-1 s-1 for both isozymes; the differences in the stabilities of the complexes with P-I and P-II are entirely attributable to the fact that glucose dissociates more slowly from its complex with P-I than P-II (approximately 300 s-1 and 1100 s-1 respectively). Although the kinetic data are compatible with a single-step mechanism for glucose binding the association rate constant was much lower than that expected for a diffusion-limited rate of encounter. Other mechanisms for describing an induced-fit are discussed. It is shown that the data are incompatible with a slow 'prior-isomerization' pathway of substrate binding, but are consistent with a 'substrate-guided' pathway involving isomerization of the enzyme-substrate complex.

Recognition of secretory proteins in Escherichia coli requires signals in addition to the signal sequence and slow folding

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Flower Ann M

2002-11-01

Full Text Available Abstract Background The Sec-dependent protein export apparatus of Escherichia coli is very efficient at correctly identifying proteins to be exported from the cytoplasm. Even bacterial strains that carry prl mutations, which allow export of signal sequence-defective precursors, accurately differentiate between cytoplasmic and mutant secretory proteins. It was proposed previously that the basis for this precise discrimination is the slow folding rate of secretory proteins, resulting in binding by the secretory chaperone, SecB, and subsequent targeting to translocase. Based on this proposal, we hypothesized that a cytoplasmic protein containing a mutation that slows its rate of folding would be recognized by SecB and therefore targeted to the Sec pathway. In a Prl suppressor strain the mutant protein would be exported to the periplasm due to loss of ability to reject non-secretory proteins from the pathway. Results In the current work, we tested this hypothesis using a mutant form of λ repressor that folds slowly. No export of the mutant protein was observed, even in a prl strain. We then examined binding of the mutant λ repressor to SecB. We did not observe interaction by either of two assays, indicating that slow folding is not sufficient for SecB binding and targeting to translocase. Conclusions These results strongly suggest that to be targeted to the export pathway, secretory proteins contain signals in addition to the canonical signal sequence and the rate of folding.

Human Meningitis-Associated Escherichia coli

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KIM, KWANG SIK

2016-01-01

E. coli is the most common Gram-negative bacillary organism causing meningitis and E. coli meningitis continues to be an important cause of mortality and morbidity throughout the world. Our incomplete knowledge of its pathogenesis contributes to such mortality and morbidity. Recent reports of E. coli strains producing CTX-M-type or TEM-type extended-spectrum β-lactamases create a challenge. Studies using in vitro and in vivo models of the blood-brain barrier have shown that E. coli meningitis follows a high-degree of bacteremia and invasion of the blood-brain barrier. E. coli invasion of the blood-brain barrier, the essentials step in the development of E. coli meningitis, requires specific microbial and host factors as well as microbe- and host-specific signaling molecules. Blockade of such microbial and host factors contributing to E. coli invasion of the blood-brain barrier is shown to be efficient in preventing E. coli penetration into the brain. The basis for requiring a high-degree of bacteremia for E. coli penetration of the blood-brain barrier, however, remains unclear. Continued investigation on the microbial and host factors contributing to a high-degree of bacteremia and E. coli invasion of the blood-brain barrier is likely to identify new targets for prevention and therapy of E. coli meningitis. PMID:27223820

Assessment of Nanobiotechnology-Targeted siRNA Designed to Inhibit NF-KappaB Classical and Alternative Signaling in Breast Tumor Macrophages

Science.gov (United States)

2014-07-01

Intraductal Injection of LPS as a Mouse Model of Mastitis : Signaling Visualized via an NF-κB Reporter Transgenic. J Vis Exp. (67). pii: 4030. 2012. PMID...injection of LPS as a mouse model of mastitis : signaling visualized via an NF-κB reporter transgenic. Journal of Visualized Experiments 2012. 4(67...supplies, including media, fetal bovine serum, antibiotics, and nonessential amino acids, were obtained from Life Technologies (Carlsbad, CA). The

Integration of AI-2 Based Cell-Cell Signaling with Metabolic Cues in Escherichia coli.

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Arindam Mitra

Full Text Available The quorum sensing molecule Autoinducer-2 (AI-2 is generated as a byproduct of activated methyl cycle by the action of LuxS in Escherichia coli. AI-2 is synthesized, released and later internalized in a cell-density dependent manner. Here, by mutational analysis of the genes, uvrY and csrA, we describe a regulatory circuit of accumulation and uptake of AI-2. We constructed a single-copy chromosomal luxS-lacZ fusion in a luxS + merodiploid strain and evaluated its relative expression in uvrY and csrA mutants. At the entry of stationary phase, the expression of the fusion and AI-2 accumulation was positively regulated by uvrY and negatively regulated by csrA respectively. A deletion of csrA altered message stability of the luxS transcript and CsrA protein exhibited weak binding to 5' luxS regulatory region. DNA protein interaction and chromatin immunoprecipitation analysis confirmed direct interaction of UvrY with the luxS promoter. Additionally, reduced expression of the fusion in hfq deletion mutant suggested involvement of small RNA interactions in luxS regulation. In contrast, the expression of lsrA operon involved in AI-2 uptake, is negatively regulated by uvrY and positively by csrA in a cell-density dependent manner. The dual role of csrA in AI-2 synthesis and uptake suggested a regulatory crosstalk of cell signaling with carbon regulation in Escherichia coli. We found that the cAMP-CRP mediated catabolite repression of luxS expression was uvrY dependent. This study suggests that luxS expression is complex and regulated at the level of transcription and translation. The multifactorial regulation supports the notion that cell-cell communication requires interaction and integration of multiple metabolic signals.

Rho-associated protein kinase regulates subcellular localisation of Angiomotin and Hippo-signalling during preimplantation mouse embryo development

Czech Academy of Sciences Publication Activity Database

Mihajlović, A. I.; Bruce, Alexander

2016-01-01

Roč. 33, č. 3 (2016), s. 381-390 ISSN 1472-6483 Grant - others:GA ČR(CZ) GA13-03295S; GA JU(CZ) 004/2015/P Institutional support: RVO:60077344 Keywords : Angiomotin * Hippo-signalling * polarization Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.249, year: 2016 http://www.sciencedirect.com/science/article/pii/S1472648316304047

Importance of juvenile hormone signaling arises with competence of insect larvae to metamorphose

Czech Academy of Sciences Publication Activity Database

Smýkal, Vlastimil; Daimon, T.; Kayukawa, T.; Takaki, Keiko; Shinoda, T.; Jindra, Marek

2014-01-01

Roč. 390, č. 2 (2014), s. 221-230 ISSN 0012-1606 R&D Projects: GA AV ČR IAA500960906 Grant - others:Marie Curie Fellowship Award(CZ) GA 276569; Japan Society for the Promotion of Science(JP) 25252059 Institutional support: RVO:60077344 Keywords : insect metamorphosis * hormonal signaling * juvenile hormone Subject RIV: ED - Physiology Impact factor: 3.547, year: 2014 http://www.sciencedirect.com/science/article/pii/S0012160614001419

The characteristics of Fugi IP Cassette Type PII and application for radiation oncology quality assurance tests and portal imaging

International Nuclear Information System (INIS)

Soh, H.S.; Ung, N.M.; Ng, K.H.

2008-01-01

Full text: The advancement of digital imaging has prompted more medical institutions to go filmless. The computed radiography (CR) system is becoming an important tool not only in diagnostic imaging, but also in radiation oncology. A new CR system that was specially designed for the use in radiation oncology. Fuji IP cassette type PII has been introduced to the market in the middle of year 2006. This project aimed to study some basic physical characteristics of this new type of cassette and explore its application for performing quality assurance (QA) tests and portal imaging in radiotherapy. All the images were read by FCR 5000 Plus reader. The image was found to reach its saturation value of 1023 (due to the image was stored in 10 bits data) by depending on the sensitivity value being adjusted. The uniformity test gave the result of 0.12%. The cassette was used to perform the QA tests which were previously performed using film. All the results met the specification as stated in AAPM Task Group 40. The comparison for the portal images of Portal Vision contrast-detail phantom showed that the spatial resolution of the images obtained by CR system (Fujifilm Co.. Ltd.. Tokyo. Japan) were better than the EPID (Varian Medical Systems. Inc.. Palo Alto. USA) and film system (Eastman Kodak Co.. New York. USA). The IP cassette type PII was found to be suitable as an alternative QA test tool and portal imaging in radiotherapy.

[Lactobacillus rhamnosus GG conditioned medium prevents E. coli meningitis by inhibiting nuclear factor-κB pathway].

Science.gov (United States)

Zeng, Qing; He, Xiao-Long; Xiao, Han-Sheng; DU, Lei; Li, Yu-Jing; Chen, Le-Cheng; Tian, Hui-Wen; Huang, Sheng-He; Cao, Hong

2017-01-20

To investigate whether Lactobacillus rhamnosus GG conditioned medium(LGG-CM)has preventive effect against E. coli K1-induced neuropathogenicity in vitro by inhibiting nuclear factor-κB (NF-κB) signaling pathway. An in vitro blood-brain barrier (BBB) model was constructed using human brain microvascular endothelial cells (HBMECs). The effect of LGG-CM on E. coli-actived NF-κB signaling pathway was assayed using Western blotting. Invasion assay and polymorphonuclear leukocyte (PMN) transmigration assay were performed to explore whether LGG-CM could inhibit E. coli invasion and PMN transmigration across the BBB in vitro. The expressions of ZO-1 and CD44 were detected using Western blotting and immunofluorescence. The changes of trans-epithelial electric resistance (TEER) and bacterial translocation were determined to evaluate the BBB permeability. Pre-treament with LGG-CM inhibited E. coli-activated NF-κB signaling pathway in HBMECs and decreased the invasion of E. coli K1 and transmigration of PMN. Western blotting showed that LGG-CM could alleviate E. coli-induced up-regulation of CD44 and down-regulation of ZO-1 expressions in HBMECs. In addition, pre-treatment with LGG-CM alleviated E. coli K1-induced reduction of TEER and suppressed bacterial translocation across the BBB in vitro. LGG-CM can block E. coli-induced activation of NF-κB signaling pathway and thereby prevents E. coli K1-induced neuropathogenicity by decreasing E. coli K1 invasion rates and PMN transmigration.

Signal peptide prediction suggests Mycobacterium tuberculosis curli pilin subunit secretion via the Sec pathway may hinder MTP overexpression in Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Naidoo, N.; Pillay, B.; Bubb, M.; Kumar, A.; Chiliza, T.; Pillay, M.

2017-07-01

Introduction Mycobacterium tuberculosis curli pili (MTP) are novel, potential TB diagnostic biomarkers as they are important virulence attributes, unique to the M. tuberculosis complex (MTBC). The production of high quality recombinant transmembrane and secretory proteins that can serve as biomarkers may be challenging due to their secretion attributes. For example, the signal peptide of MTP governed by the classical secretion pathway may hinder the purification of the protein in E. coli systems. In this study, the secretion characteristics of MTP were determined and the cloning, expression and purification of MTP was attempted in E.coli. Materials and methods A fragment of MTP unique to MTBC was cloned into pet101 and pGEX-6P-1 vectors. The clones were confirmed by nucleotide sequencing and expression of the protein was attempted at IPTG concentrations ranging from 0.1mM to 1mM and at temperatures between 25 °C to 37 °C. The pGEX-6P-1/mtp clone expressed protein was purified, yielding a MTP-GST fusion protein and a free GST band that were analysed by LC/MS mass spectrometry. Inclusion body preparation attempted from the pet101/mtp clone yielded two bands at 10 kDa and below 10 kDa, both of which were analysed by LC/MS mass spectrometry. Transcription activity of both the clones was interrogated by real time PCR on the cDNA derived from the induced clones at various time points after induction with IPTG. The signal peptide and protein secretion characteristics of the MTP protein were determined by bioinformatics analysis of the amino acid sequence using publically available software. Results The truncated MTP fragments were successfully cloned in both the vectors as confirmed by nucleotide sequencing. Expression of the pGEX-6P-1/mtp clone using 0.5 mM IPTG at 27 °C demonstrated the presence of the expected fragment at approximately 35 kDa. This was confirmed by Western Blotting using anti-GST antibodies. However, purification of MTP in adequate quantities as a

Signal peptide prediction suggests Mycobacterium tuberculosis curli pilin subunit secretion via the Sec pathway may hinder MTP overexpression in Escherichia coli

International Nuclear Information System (INIS)

Naidoo, N.; Pillay, B.; Bubb, M.; Kumar, A.; Chiliza, T.; Pillay, M.

2017-01-01

Introduction Mycobacterium tuberculosis curli pili (MTP) are novel, potential TB diagnostic biomarkers as they are important virulence attributes, unique to the M. tuberculosis complex (MTBC). The production of high quality recombinant transmembrane and secretory proteins that can serve as biomarkers may be challenging due to their secretion attributes. For example, the signal peptide of MTP governed by the classical secretion pathway may hinder the purification of the protein in E. coli systems. In this study, the secretion characteristics of MTP were determined and the cloning, expression and purification of MTP was attempted in E.coli. Materials and methods A fragment of MTP unique to MTBC was cloned into pet101 and pGEX-6P-1 vectors. The clones were confirmed by nucleotide sequencing and expression of the protein was attempted at IPTG concentrations ranging from 0.1mM to 1mM and at temperatures between 25 °C to 37 °C. The pGEX-6P-1/mtp clone expressed protein was purified, yielding a MTP-GST fusion protein and a free GST band that were analysed by LC/MS mass spectrometry. Inclusion body preparation attempted from the pet101/mtp clone yielded two bands at 10 kDa and below 10 kDa, both of which were analysed by LC/MS mass spectrometry. Transcription activity of both the clones was interrogated by real time PCR on the cDNA derived from the induced clones at various time points after induction with IPTG. The signal peptide and protein secretion characteristics of the MTP protein were determined by bioinformatics analysis of the amino acid sequence using publically available software. Results The truncated MTP fragments were successfully cloned in both the vectors as confirmed by nucleotide sequencing. Expression of the pGEX-6P-1/mtp clone using 0.5 mM IPTG at 27 °C demonstrated the presence of the expected fragment at approximately 35 kDa. This was confirmed by Western Blotting using anti-GST antibodies. However, purification of MTP in adequate quantities as a

Experimental enhancement of fuzzy fractional order PI+I controller of grid connected variable speed wind energy conversion system

International Nuclear Information System (INIS)

Beddar, Antar; Bouzekri, Hacene; Babes, Badreddine; Afghoul, Hamza

2016-01-01

Highlights: • Fuzzy fractional order PI+I for wind energy conversion system is developed. • Investigation of the control methods performances under wind and load variations. • PSO algorithm with frequency method are used for parameters tuning. • Experimental results are presented. - Abstract: In this paper, fuzzy fractional order PI+I (FFOPI+I) controller for grid connected Variable Speed Wind Energy Conversion System (VS-WECS) is proposed. The FFOPI+I controller is applied to control a Permanent Magnet Synchronous Generator (PMSG) connected to the grid and nonlinear load through a back-to-back AC-DC-AC PWM converter. The control strategy of the Machine Side Converter (MSC) aims, at first, to extract a maximum power under fluctuating wind speed. Then, the Grid Side Converter (GSC) is controlled to improve the power quality and ensure sinusoidal current in the grid side. The FFOPI+I controller implements a Fuzzy Logic Controller (FLC) in parallel with Fractional Order PI (FOPI) and conventional PI controllers by having a commune proportional gain. The FLC changes the integral gains at runtime. The initial parameters of the FFOPI+I controller were calculated using a frequency method to create a search space then the PSO algorithm is used to select the optimal parameters. To evaluate the performance of the proposed controller in steady and transient states, an experimental test bench has been built in laboratory using dSPACE1104 card. The experimental results demonstrate the effectiveness and feasibility of the FFOPI+I over FOPI and conventional PI controllers by realizing maximum power extraction and improving the grid-side power factor for a wide range of wind speed.

Pertussis Toxin Exploits Host Cell Signaling Pathways Induced by Meningitis-Causing E. coli K1-RS218 and Enhances Adherence of Monocytic THP-1 Cells to Human Cerebral Endothelial Cells

Directory of Open Access Journals (Sweden)

Laura Julia Starost

2016-10-01

Full Text Available Pertussis toxin (PTx, the major virulence factor of the whooping cough-causing bacterial pathogen Bordetella pertussis, permeabilizes the blood–brain barrier (BBB in vitro and in vivo. Breaking barriers might promote translocation of meningitis-causing bacteria across the BBB, thereby facilitating infection. PTx activates several host cell signaling pathways exploited by the neonatal meningitis-causing Escherichia coli K1-RS218 for invasion and translocation across the BBB. Here, we investigated whether PTx and E. coli K1-RS218 exert similar effects on MAPK p38, NF-κB activation and transcription of downstream targets in human cerebral endothelial TY10 cells using qRT-PCR, Western blotting, and ELISA in combination with specific inhibitors. PTx and E. coli K1-RS218 activate MAPK p38, but only E. coli K1-RS218 activates the NF-κB pathway. mRNA and protein levels of p38 and NF-κB downstream targets including IL-6, IL-8, CxCL-1, CxCL-2 and ICAM-1 were increased. The p38 specific inhibitor SB203590 blocked PTx-enhanced activity, whereas E. coli K1-RS218’s effects were inhibited by the NF-κB inhibitor Bay 11-7082. Further, we found that PTx enhances the adherence of human monocytic THP-1 cells to human cerebral endothelial TY10 cells, thereby contributing to enhanced translocation. These modulations of host cell signaling pathways by PTx and meningitis-causing E. coli support their contributions to pathogen and monocytic THP-1 cells translocation across the BBB.

Domain swapping reveals that the N-terminal domain of the sensor kinase KdpD in Escherichia coli is important for signaling

Directory of Open Access Journals (Sweden)

Lippert Marie-Luise

2009-07-01

Full Text Available Abstract Background The KdpD/KdpE two-component system of Escherichia coli regulates expression of the kdpFABC operon encoding the high affinity K+ transport system KdpFABC. The input domain of KdpD comprises a domain that belongs to the family of universal stress proteins (Usp. It has been previously demonstrated that UspC binds to this domain, resulting in KdpD/KdpE scaffolding under salt stress. However the mechanistic significance of this domain for signaling remains unclear. Here, we employed a "domain swapping" approach to replace the KdpD-Usp domain with four homologous domains or with the six soluble Usp proteins of E. coli. Results Full response to salt stress was only achieved with a chimera that contains UspC, probably due to unaffected scaffolding of the KdpD/KdpE signaling cascade by soluble UspC. Unexpectedly, chimeras containing either UspF or UspG not only prevented kdpFABC expression under salt stress but also under K+ limiting conditions, although these hybrid proteins exhibited kinase and phosphotransferase activities in vitro. These are the first KdpD derivatives that do not respond to K+ limitation due to alterations in the N-terminal domain. Analysis of the KdpD-Usp tertiary structure revealed that this domain has a net positively charged surface, while UspF and UspG are characterized by net negative surface charges. Conclusion The Usp domain within KdpD not only functions as a binding surface for the scaffold UspC, but it is also important for KdpD signaling. We propose that KdpD sensing/signaling involves alterations of electrostatic interactions between the large N- and C-terminal cytoplasmic domains.

Evaluation of mating type distribution and genetic diversity of three Magnaporthe oryzae avirulence genes, PWL-2, AVR-Pii and Avr-Piz-t, in Thailand rice blast isolates

Directory of Open Access Journals (Sweden)

Thanyaluk Sirisathaworn

2017-02-01

Full Text Available Rice blast disease, caused by the filamentous ascomycete fungus Magnaporthe oryzae (anamorph Pyricularia oryzae, has been ranked among the most important diseases of rice. The molecular mechanisms against this fungus follow the idea of “gene-for-gene interaction”, in which a plant resistance (R gene product recognizes a fungal avirulence (Avr effector and triggers the defense response. However, the Avr genes have been shown to be rapidly evolving resulting in high levels of genetic diversity. This study investigated genetic diversity that is influenced by sexual recombination and mutation for the adaptation of rice blast fungus to overcome the defense response. Mating type distribution and the nucleotide sequence variation of three avirulence genes were evaluated—PWL-2, Avr-Pii and Avr-Piz-t. In total, 77 rice blast isolates collected from infected rice plants in northern, northeastern and central Thailand in 2005, 2010 and 2012, were used in the analysis with mating type and avirulence gene-specific primers. The results revealed that all the tested blast isolates belonged to the mating type MAT1-2, suggesting a lack of sexual recombination within the population. The successful rates of PWL-2, Avr-Pii and Avr-Piz-t gene-specific primer amplification were 100%, 60% and 54%, respectively. Base substitution mutation was observed in coding regions of the Avr-Pii and Avr-Piz-t genes. Although these results showed a low level of genetic diversity in Thai rice blast isolates, non-synonymous mutations did occur which revealed common mechanisms of selective pressure that are prone to adaptation of Avr genes. The information on nucleotide sequence variation and the genetic diversity of Avr genes obtained from this study could be useful for planning novel strategies in the development of rice breeding programs in Thailand.

Molecular photonic imaging of cancer using light-emitting e. coli

International Nuclear Information System (INIS)

Park, Jae Hyo; Min, Jung Joon; Moon, Sung Min; Kim, Hyun Ju; Hong, Yeong Jin; Choy, Hyon E.; Bom, Hee Seung; Jeong, Jae Ho; Cho, Kyoung Oh

2005-01-01

Cancer research has long sought a magic bullet that would selectively target and destroy malignant cells. In this study, we exploited that E. coli injected into tumor-bearing mice selectively target and proliferate in solid tumors by employing optical imaging technique. Lux operon or GFP has been cloned into pUC19 plasmid to engineer pUC19Lux or pUC19gfp which was transformed into varying kinds of wild type (MG1655) or mutant E.coli strains. For stable expression, lux operon was cloned with asd (aspartate β-semialdehyde dehydrogenase) gene and transformed into asd defective E. coli (MG1655asd-/asd+lux). These bacteria were i.v. injected into tumor mice or directly into central necrosis of tumor. The imaging signal from wild type E.coli was detected initially at liver (20min), then migrated to and shine in the tumor mass until 2 weeks of injection which was consistently observed in immuno-defective (nude) and -competent (Balb/c) mice. Imaging signal of stbaly transformed strain (MG1655asd-/asd+lux) was stronger and longer-lasting than that of transiently transformed strain (MG1655lux). Flagella defective E. coli strain failed to reach tumor loci. Only a few amounts of stress regulatory defective E. coli strain arrived at but couldn't survive at the tumor loci. E. coli colonies expressing GFP was mostly observed at the border of central necrosis and peripheral proliferative areas in immunofluorescence studies. Directly injected MG1655ad-/asd+lux was transiently observed at central necrosis followed by spreading to the peripheral tumor mass which was consistent with the finding by tail vein injection. We successfully engineered E. coli strain stably expressing lux reporter gene. E. coli strongly targeted solid tumor regardless of host immune status. Our results support that the targeting of tumor by E.coli is an active process and would be applied as a delivery vehicle of varying imaging markers or therapeutic molecules

Molecular signal for induction of the adaptive response to alkylating agents in E. coli

Energy Technology Data Exchange (ETDEWEB)

Lindahl, T.; Sedgwick, B.; Teo, I.; Kilpatrick, M.; McCarthy, T.; Hughes, S.

1986-05-01

Exposure of E. coli to simple alkylating agents such as methylnitrosourea causes the induction of at least three DNA repair functions, which are under the control of the ada gene. The intracellular signal for switching on the response has been identified as one of the two stereoisomers of methyl phosphotriesters generated in DNA by alkylation. The methyl group is transferred from the phosphotriester moiety to a specific cysteine residue within the regulatory Ada protein in a self-methylation reaction. This protein also corrects the mutagenic lesion O/sup 6/-methylguanine by transfer of its methyl group to a separate cysteine residue in the Ada protein. Methylation of the protein from repair of a DNA phosphotriester residue, but not from O/sup 6/-methylguanine, converts it to an activator of transcription of genes involved in the adaptive response. The activated form of the Ada protein enhances transcription by binding specifically to a sequence d(AAA--AAAGCGCA), located immediately upstream of the RNA polymerase binding site in relevant promoter regions.

Secretory expression of nattokinase from Bacillus subtilis YF38 in Escherichia coli.

Science.gov (United States)

Liang, Xiaobo; Jia, Shifang; Sun, Yufang; Chen, Meiling; Chen, Xiuzhu; Zhong, Jin; Huan, Liandong

2007-11-01

Nattokinase producing bacterium, B. subtilis YF38, was isolated from douchi, using the fibrin plate method. The gene encoding this enzyme was cloned by polymerase chain reaction (PCR). Cytoplasmic expression of this enzyme in E. coli resulted in inactive inclusion bodies. But with the help of two different signal peptides, the native signal peptide of nattokinase and the signal peptide of PelB, active nattokinase was successfully expressed in E. coli with periplasmic secretion, and the nattokinase in culture medium displayed high fibrinolytic activity. The fibrinolytic activity of the expressed enzyme in the culture was determined to reach 260 urokinase units per micro-liter when the recombinant strain was induced by 0.7 mmol l(-1) isopropyl-beta-D- thiogalactopyranoside (IPTG) at 20 degrees C for 20 h, resulting 49.3 mg active enzyme per liter culture. The characteristic of this recombinant nattokinase is comparable to the native nattokinase from B. subtilis YF38. Secretory expression of nattokinase in E. coli would facilitate the development of this enzyme into a therapeutic product for the control and prevention of thrombosis diseases.

Evolutionary conservation of the polyproline II conformation surrounding intrinsically disordered phosphorylation sites.

Science.gov (United States)

Elam, W Austin; Schrank, Travis P; Campagnolo, Andrew J; Hilser, Vincent J

2013-04-01

Intrinsically disordered (ID) proteins function in the absence of a unique stable structure and appear to challenge the classic structure-function paradigm. The extent to which ID proteins take advantage of subtle conformational biases to perform functions, and whether signals for such mechanism can be identified in proteome-wide studies is not well understood. Of particular interest is the polyproline II (PII) conformation, suggested to be highly populated in unfolded proteins. We experimentally determine a complete calorimetric propensity scale for the PII conformation. Projection of the scale into representative eukaryotic proteomes reveals significant PII bias in regions coding for ID proteins. Importantly, enrichment of PII in ID proteins, or protein segments, is also captured by other PII scales, indicating that this enrichment is robustly encoded and universally detectable regardless of the method of PII propensity determination. Gene ontology (GO) terms obtained using our PII scale and other scales demonstrate a consensus for molecular functions performed by high PII proteins across the proteome. Perhaps the most striking result of the GO analysis is conserved enrichment (P ontology reveals an enrichment of PII bias near disordered phosphorylation sites that is conserved throughout eukaryotes. Copyright © 2013 The Protein Society.

Improving Fab' fragment retention in an autonucleolytic Escherichia coli strain by swapping periplasmic nuclease translocation signal from OmpA to DsbA.

Science.gov (United States)

Schofield, Desmond M; Sirka, Ernestas; Keshavarz-Moore, Eli; Ward, John M; Nesbeth, Darren N

2017-12-01

To reduce unwanted Fab' leakage from an autonucleolytic Escherichia coli strain, which co-expresses OmpA-signalled Staphylococcal nuclease and Fab' fragment in the periplasm, by substituting in Serratial nuclease and the DsbA periplasm translocation signal as alternatives. We attempted to genetically fuse a nuclease from Serratia marcescens to the OmpA signal peptide but plasmid construction failed, possibly due to toxicity of the resultant nuclease. Combining Serratial nuclease to the DsbA signal peptide was successful. The strain co-expressing this nuclease and periplasmic Fab' grew in complex media and exhibited nuclease activity detectable by DNAse agar plate but its growth in defined medium was retarded. Fab' coexpression with Staphylococcal nuclease fused to the DsbA signal peptide resulted in cells exhibiting nuclease activity and growth in defined medium. In cultivation to high cell density in a 5 l bioreactor, DsbA-fused Staphylococcal nuclease co-expression coincided with reduced Fab' leakage relative to the original autonucleolytic Fab' strain with OmpA-fused staphylococcal nuclease. We successfully rescued Fab' leakage back to acceptable levels and established a basis for future investigation of the linkage between periplasmic nuclease expression and leakage of co-expressed periplasmic Fab' fragment to the surrounding growth media.

Mutational analysis of GlnB residues critical for NifA activation in Azospirillum brasilense.

Science.gov (United States)

Inaba, Juliana; Thornton, Jeremy; Huergo, Luciano Fernandes; Monteiro, Rose Adele; Klassen, Giseli; Pedrosa, Fábio de Oliveira; Merrick, Mike; de Souza, Emanuel Maltempi

2015-02-01

PII proteins are signal transduction that sense cellular nitrogen status and relay this signals to other targets. Azospirillum brasilense is a nitrogen fixing bacterium, which associates with grasses and cereals promoting beneficial effects on plant growth and crop yields. A. brasilense contains two PII encoding genes, named glnB and glnZ. In this paper, glnB was mutagenised in order to identify amino acid residues involved in GlnB signaling. Two variants were obtained by random mutagenesis, GlnBL13P and GlnBV100A and a site directed mutant, GlnBY51F, was obtained. Their ability to complement nitrogenase activity of glnB mutant strains of A. brasilense were determined. The variant proteins were also overexpressed in Escherichia coli, purified and characterized biochemically. None of the GlnB variant forms was able to restore nitrogenase activity in glnB mutant strains of A. brasilense LFH3 and 7628. The purified GlnBY51F and GlnBL13P proteins could not be uridylylated by GlnD, whereas GlnBV100A was uridylylated but at only 20% of the rate for wild type GlnB. Biochemical and computational analyses suggest that residue Leu13, located in the α helix 1 of GlnB, is important to maintain GlnB trimeric structure and function. The substitution V100A led to a lower affinity for ATP binding. Together the results suggest that NifA activation requires uridylylated GlnB bound to ATP. Copyright © 2014 Elsevier GmbH. All rights reserved.

Uridylylation of Herbaspirillum seropedicae GlnB and GlnK proteins is differentially affected by ATP, ADP and 2-oxoglutarate in vitro.

Science.gov (United States)

Bonatto, Ana C; Souza, Emanuel M; Oliveira, Marco A S; Monteiro, Rose A; Chubatsu, Leda S; Huergo, Luciano F; Pedrosa, Fábio O

2012-08-01

PII are signal-transducing proteins that integrate metabolic signals and transmit this information to a large number of proteins. In proteobacteria, PII are modified by GlnD (uridylyltransferase/uridylyl-removing enzyme) in response to the nitrogen status. The uridylylation/deuridylylation cycle of PII is also regulated by carbon and energy signals such as ATP, ADP and 2-oxoglutarate (2-OG). These molecules bind to PII proteins and alter their tridimensional structure/conformation and activity. In this work, we determined the effects of ATP, ADP and 2-OG levels on the in vitro uridylylation of Herbaspirillum seropedicae PII proteins, GlnB and GlnK. Both proteins were uridylylated by GlnD in the presence of ATP or ADP, although the uridylylation levels were higher in the presence of ATP and under high 2-OG levels. Under excess of 2-OG, the GlnB uridylylation level was higher in the presence of ATP than with ADP, while GlnK uridylylation was similar with ATP or ADP. Moreover, in the presence of ADP/ATP molar ratios varying from 10/1 to 1/10, GlnB uridylylation level decreased as ADP concentration increased, whereas GlnK uridylylation remained constant. The results suggest that uridylylation of both GlnB and GlnK responds to 2-OG levels, but only GlnB responds effectively to variation on ADP/ATP ratio.

ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli

OpenAIRE

ANGGREINI, RAHAYU

2015-01-01

2015 RAHAYU ANGGREINI coli Penelitian ini bertujuan untuk melakukan identifikasi cemaran bakteri E. coli O157:H7 pada daging sapi di kota Makassar. Sampel pada penelitian ini sebanyak 72 sampel Kata Kunci : Daging sapi, pasar tradisional, E. coli, E. coli O157:H7, kontaminasi bakteri, identifikasi E. coli O157:H7.

The adenomatous polyposis coli protein.

OpenAIRE

Näthke, I S

1999-01-01

Mutations in the adenomatous polyposis coli (APC) gene are associated with most colorectal cancers. The APC protein has been implicated in many aspects of tumour development. This article will discuss recent data suggesting that APC may have multiple functions in the cell. First, APC is a component of the Wnt signalling pathway; second, APC may have a role in cell migration; finally, APC may regulate proliferation and apoptosis.

Structural and Functional Analysis of the Signal-Transducing Linker in the pH-Responsive One-Component System CadC of Escherichia coli.

Science.gov (United States)

Buchner, Sophie; Schlundt, Andreas; Lassak, Jürgen; Sattler, Michael; Jung, Kirsten

2015-07-31

The pH-responsive one-component signaling system CadC in Escherichia coli belongs to the family of ToxR-like proteins, whose members share a conserved modular structure, with an N-terminal cytoplasmic winged helix-turn-helix DNA-binding domain being followed by a single transmembrane helix and a C-terminal periplasmic pH-sensing domain. In E. coli CadC, a cytoplasmic linker comprising approximately 50 amino acids is essential for transmission of the signal from the sensor to the DNA-binding domain. However, the mechanism of transduction is poorly understood. Using NMR spectroscopy, we demonstrate here that the linker region is intrinsically disordered in solution. Furthermore, mutational analyses showed that it tolerates a range of amino acid substitutions (altering polarity, rigidity and α-helix-forming propensity), is robust to extension but is sensitive to truncation. Indeed, truncations either reversed the expression profile of the target operon cadBA or decoupled expression from external pH altogether. CadC dimerizes via its periplasmic domain, but light-scattering analysis provided no evidence for dimerization of the isolated DNA-binding domain, with or without the linker region. However, bacterial two-hybrid analysis revealed that CadC forms stable dimers in a stimulus- and linker-dependent manner, interacting only at pHpH. Thus, we propose that the disordered CadC linker is required for transducing the pH-dependent response of the periplasmic sensor into a structural rearrangement that facilitates dimerization of the cytoplasmic CadC DNA-binding domain. Copyright © 2015 Elsevier Ltd. All rights reserved.

Downregulation of adenomatous polyposis coli by microRNA-663 promotes odontogenic differentiation through activation of Wnt/beta-catenin signaling

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Sung; Park, Min-Gyeong; Lee, Seul Ah; Park, Sun-Young; Kim, Heung-Joong; Yu, Sun-Kyoung; Kim, Chun Sung; Kim, Su-Gwan; Oh, Ji-Su; You, Jae-Seek; Kim, Jin-Soo; Seo, Yo-Seob [Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 501-759 (Korea, Republic of); Chun, Hong Sung [Department of Biomedical Science, Chosun University, Gwangju 501-759 (Korea, Republic of); Park, Joo-Cheol [Department of Oral Histology-Developmental Biology, School of Dentistry and Dental Research Institute, BK 21, Seoul National University, Seoul 110-749 (Korea, Republic of); Kim, Do Kyung, E-mail: kdk@chosun.ac.kr [Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 501-759 (Korea, Republic of)

2014-04-18

Highlights: • miR-663 is significantly up-regulated during MDPC-23 odontoblastic cell differentiation. • miR-663 accelerates mineralization in MDPC-23 odontoblastic cells without cell proliferation. • miR-663 promotes odontoblastic cell differentiation by targeting APC and activating Wnt/β-catenin signaling in MDPC-23 cells. - Abstract: MicroRNAs (miRNAs) regulate cell differentiation by inhibiting mRNA translation or by inducing its degradation. However, the role of miRNAs in odontogenic differentiation is largely unknown. In this present study, we observed that the expression of miR-663 increased significantly during differentiation of MDPC-23 cells to odontoblasts. Furthermore, up-regulation of miR-663 expression promoted odontogenic differentiation and accelerated mineralization without proliferation in MDPC-23 cells. In addition, target gene prediction for miR-663 revealed that the mRNA of the adenomatous polyposis coli (APC) gene, which is associated with the Wnt/β-catenin signaling pathway, has a miR-663 binding site in its 3′-untranslated region (3′UTR). Furthermore, APC expressional was suppressed significantly by miR-663, and this down-regulation of APC expression triggered activation of Wnt/β-catenin signaling through accumulation of β-catenin in the nucleus. Taken together, these findings suggest that miR-663 promotes differentiation of MDPC-23 cells to odontoblasts by targeting APC-mediated activation of Wnt/β-catenin signaling. Therefore, miR-663 can be considered a critical regulator of odontoblast differentiation and can be utilized for developing miRNA-based therapeutic agents.

Systematic high-yield production of human secreted proteins in Escherichia coli

International Nuclear Information System (INIS)

Dai Xueyu; Chen Qiang; Lian Min; Zhou Yanfeng; Zhou Mo; Lu Shanyun; Chen Yunjia; Luo Jingchu; Gu Xiaocheng; Jiang Ying; Luo Ming; Zheng Xiaofeng

2005-01-01

Human secreted proteins play a very important role in signal transduction. In order to study all potential secreted proteins identified from the human genome sequence, systematic production of large amounts of biologically active secreted proteins is a prerequisite. We selected 25 novel genes as a trial case for establishing a reliable expression system to produce active human secreted proteins in Escherichia coli. Expression of proteins with or without signal peptides was examined and compared in E. coli strains. The results indicated that deletion of signal peptides, to a certain extent, can improve the expression of these proteins and their solubilities. More importantly, under expression conditions such as induction temperature, N-terminus fusion peptides need to be optimized in order to express adequate amounts of soluble proteins. These recombinant proteins were characterized as well-folded proteins. This system enables us to rapidly obtain soluble and highly purified human secreted proteins for further functional studies

Meta-Analysis of Transcriptional Responses to Mastitis-Causing Escherichia coli.

Directory of Open Access Journals (Sweden)

Sidra Younis

Full Text Available Bovine mastitis is a widespread disease in dairy cows, and is often caused by bacterial mammary gland infection. Mastitis causes reduced milk production and leads to excessive use of antibiotics. We present meta-analysis of transcriptional profiles of bovine mastitis from 10 studies and 307 microarrays, allowing identification of much larger sets of affected genes than any individual study. Combining multiple studies provides insight into the molecular effects of Escherichia coli infection in vivo and uncovers differences between the consequences of E. coli vs. Staphylococcus aureus infection of primary mammary epithelial cells (PMECs. In udders, live E. coli elicits inflammatory and immune defenses through numerous cytokines and chemokines. Importantly, E. coli infection causes downregulation of genes encoding lipid biosynthesis enzymes that are involved in milk production. Additionally, host metabolism is generally suppressed. Finally, defensins and bacteria-recognition genes are upregulated, while the expression of the extracellular matrix protein transcripts is silenced. In PMECs, heat-inactivated E. coli elicits expression of ribosomal, cytoskeletal and angiogenic signaling genes, and causes suppression of the cell cycle and energy production genes. We hypothesize that heat-inactivated E. coli may have prophylactic effects against mastitis. Heat-inactivated S. aureus promotes stronger inflammatory and immune defenses than E. coli. Lipopolysaccharide by itself induces MHC antigen presentation components, an effect not seen in response to E. coli bacteria. These results provide the basis for strategies to prevent and treat mastitis and may lead to the reduction in the use of antibiotics.

Data-driven quantification of the robustness and sensitivity of cell signaling networks

International Nuclear Information System (INIS)

Mukherjee, Sayak; Seok, Sang-Cheol; Vieland, Veronica J; Das, Jayajit

2013-01-01

Robustness and sensitivity of responses generated by cell signaling networks has been associated with survival and evolvability of organisms. However, existing methods analyzing robustness and sensitivity of signaling networks ignore the experimentally observed cell-to-cell variations of protein abundances and cell functions or contain ad hoc assumptions. We propose and apply a data-driven maximum entropy based method to quantify robustness and sensitivity of Escherichia coli (E. coli) chemotaxis signaling network. Our analysis correctly rank orders different models of E. coli chemotaxis based on their robustness and suggests that parameters regulating cell signaling are evolutionary selected to vary in individual cells according to their abilities to perturb cell functions. Furthermore, predictions from our approach regarding distribution of protein abundances and properties of chemotactic responses in individual cells based on cell population averaged data are in excellent agreement with their experimental counterparts. Our approach is general and can be used to evaluate robustness as well as generate predictions of single cell properties based on population averaged experimental data in a wide range of cell signaling systems. (paper)

Signal peptide of eosinophil cationic protein is toxic to cells lacking signal peptide peptidase

International Nuclear Information System (INIS)

Wu, C.-M.; Chang, Margaret Dah-Tsyr

2004-01-01

Eosinophil cationic protein (ECP) is a toxin secreted by activated human eosinophils. The properties of mature ECP have been well studied but those of the signal peptide of ECP (ECPsp) are not clear. In this study, several chimeric proteins containing N-terminal fusion of ECPsp were generated, and introduced into Escherichia coli, Pichia pastoris, and human epidermoid carcinoma cell line A431 to study the function of ECPsp. We found that expression of ECPsp chimeric proteins inhibited the growth of E. coli and P. pastoris but not A431 cells. Primary sequence analysis and in vitro transcription/translation of ECPsp have revealed that it is a potential substrate for human signal peptide peptidase (hSPP), an intramembrane protease located in endoplasmic reticulum. In addition, knockdown of the hSPP mRNA expression in ECPsp-eGFP/A431 cells caused the growth inhibitory effect, whereas complementally expression of hSPP in P. pastoris system rescued the cell growth. Taken together, we have demonstrated that ECPsp is a toxic signal peptide, and expression of hSPP protects the cells from growth inhibition

Effects of substitutions at position 180 in the Escherichia coli RNA ...

Indian Academy of Sciences (India)

Escherichia coli RNA polymerase, two mutant variants of the protein with substitutions for either alanine or glutamic .... promoter signals utilized for in vitro transcription assays and ..... free recombinant protein using a self-cleavable affinity tag.

Secretion of clostridium cellulase by E. coli

Science.gov (United States)

Yu, Ida Kuo

1998-01-01

A gene, encoding an endocellulase from a newly isolated mesophilic Clostridium strain IY-2 which can digest bamboo fibers, cellulose, rice straw, and sawdust, was isolated by shotgun cloning in an E. coli expression plasmid pLC2833. E. coli positive clones were selected based on their ability to hydrolyze milled bamboo fibers and cellulose present in agar plates. One clone contained a 2.8 kb DNA fragment that was responsible for cellulase activity. Western blot analyses indicated that the positive clone produced a secreted cellulase with a mass of about 58,000 daltons that was identical in size to the subunit of one of the three major Clostridium cellulases. The products of cellulose digestion by this cloned cellulase were cellotetraose and soluble higher polymers. The cloned DNA contained signal sequences capable of directing the secretion of heterologous proteins from an E. coli host. The invention describes a bioprocess for the treatment of cellulosic plant materials to produce cellular growth substrates and fermentation end products suitable for production of liquid fuels, solvents, and acids.

A magnetic biosensor system for detection of E. coli

KAUST Repository

Li, Fuquan

2013-07-01

This work describes a device for detecting E. coli bacteria by manipulating superparamagnetic beads to a sensing area and immobilizing them in a trapping well. The trapping well replaces the biochemical immobilization layer, which is commonly used in magnetic biosensor systems. A concept exploiting the volume difference between bare magnetic beads and magnetic bead-bioanalyte compounds is utilized to detect E. coli bacteria. Trapped beads are detected by the help of a tunnel magneto-resistive sensor. Frequency modulation is employed, in order to increase the signal-to-noise ratio, enabling the detection of individual superparamagnetic beads of 2.8 μm in diameter. Replacing the biochemical immobilization layer by the trapping well greatly simplifies the detection process. After applying the mixture of E. coli and magnetic beads to the biosensor system, bacteria detection is achieved in a single step, within a few minutes. © 2013 IEEE.

Graphene-Based FET Detector for E. coli K12 Real-Time Monitoring and Its Theoretical Analysis

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Jieyi Zhu

2016-01-01

Full Text Available This paper presents a theoretical analysis for a graphene-based FET real-time detector of the target bacteria E. coli K12. The motivation for this study is to design a sensor device for detection of bacteria in food and water in order to guarantee food safety. Graphene is chosen as our material for sensor design, which has outstanding electrical, physical, and optical performance. In our sensor structure, graphene-based solution gate field effect transistor (FET is the device model; fabrication and functionalization protocol are presented together in this paper. What is more, a real-time signal display system is the accompanied equipment for our designed biosensor device. In this system, the sensor bias current signal Ids would change obviously when the target bacteria are attached to the sensor surface. And the bias current Ids increases when the E. coli concentration increases. In the latter part, a theoretical interpretation of the sensor signal is to explain the bias current Ids increasing after the E. coli K12 attachment.

Escherichia coli pathotypes

Science.gov (United States)

Escherichia coli strains are important commensals of the intestinal tract of humans and animals; however, pathogenic strains, including diarrhea-inducing E. coli and extraintestinal pathogenic E. coli. Intestinal E. coli pathotypes may cause a dehydrating watery diarrhea, or more severe diseases su...

Recombinant cholera toxin B subunit in Escherichia coli: high-level secretion, purification, and characterization

NARCIS (Netherlands)

Slos, P.; Speck, D.; Accart, N.; Kolbe, H.V.; Schubnel, D.; Bouchon, B.; Bischoff, Rainer; Kieny, M.P.

1994-01-01

The gene coding for cholera toxin subunit B (CT-B) was fused to a modified ompA signal sequence and subsequently cloned into a high expression vector based on the regulatory signals of the arabinose operon of Salmonella typhimurium. Upon induction of gene expression in Escherichia coli, a product of

Voltage-gated calcium flux mediates Escherichia coli mechanosensation.

Science.gov (United States)

Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

2017-08-29

Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

Receptors and cGMP signalling mechanism for E. coli enterotoxin in opossum kidney

International Nuclear Information System (INIS)

Forte, L.R.; Krause, W.J.; Freeman, R.H.

1988-01-01

Receptors for the heat-stable enterotoxin produced by Escherichia coli were found in the kidney and intestine of the North American opossum and in cultured renal cell lines. The enterotoxin markedly increased guanosine 3',5'-cyclic monophosphate (cGMP) production in slices of kidney cortex and medulla, in suspensions of intestinal mucosa, and in the opossum kidney (OK) and rat kangaroo kidney (PtK-2) cell lines. In contrast, atrial natriuretic factor elicited much smaller increases in cGMP levels of kidney, intestine, or cultured kidney cell lines. The enterotoxin receptors in OK cells had a molecular mass of approximately 120 kDa when measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of receptors crosslinked with 125 I-enterotoxin. The occurrence of receptors for the E. coli peptide in OK implies that these receptors may be involved in the regulation of renal tubular function in the opossum. E. coli enterotoxin caused a much larger increase in urine cGMP excretion than did atrial natriuretic factor when these peptides were injected intravenously into opossums. However, atrial natriuretic factor elicited a marked diuresis, natriuresis, and increased urinary excretion of calcium, phosphate, potassium, and magnesium. In contrast, the enterotoxin did not acutely influence OK fluid and electrolyte excretion. Thus the substantial increase in cGMP synthesis produced by the bacterial peptide in OK cortex and medulla in vitro and the increased renal excretion of cGMP in vivo were not associated with changes in electrolyte or water excretion. Whether cGMP represents a second messenger molecule in the kidney is an interesting question that was raised but not answered in this series of experiments

Co-ordinate regulation of distinct host cell signalling pathways by multifunctional enteropathogenic Escherichia coli effector molecules.

Science.gov (United States)

Kenny, Brendan; Ellis, Sarah; Leard, Alan D; Warawa, Jonathan; Mellor, Harry; Jepson, Mark A

2002-05-01

Enteropathogenic Escherichia coli (EPEC) is a major cause of paediatric diarrhoea and a model for the family of attaching and effacing (A/E) pathogens. A/E pathogens encode a type III secretion system to transfer effector proteins into host cells. The EPEC Tir effector protein acts as a receptor for the bacterial surface protein intimin and is involved in the formation of Cdc42-independent, actin-rich pedestal structures beneath the adhered bacteria. In this paper, we demonstrate that EPEC binding to HeLa cells also induces Tir-independent, cytoskeletal rearrangement evidenced by the early, transient formation of filopodia-like structures at sites of infection. Filopodia formation is dependent on expression of the EPEC Map effector molecule - a protein that targets mitochondria and induces their dysfunction. We show that Map-induced filopodia formation is independent of mitochondrial targeting and is abolished by cellular expression of the Cdc42 inhibitory WASP-CRIB domain, demonstrating that Map has at least two distinct functions in host cells. The transient nature of the filopodia is related to an ability of EPEC to downregulate Map-induced cell signalling that, like pedestal formation, was dependent on both Tir and intimin proteins. The ability of Tir to downregulate filopodia was impaired by disrupting a putative GTPase-activating protein (GAP) motif, suggesting that Tir may possess such a function, with its interaction with intimin triggering this activity. Furthermore, we also found that Map-induced cell signalling inhibits pedestal formation, revealing that the cellular effects of Tir and Map must be co-ordinately regulated during infection. Possible implications of the multifunctional nature of EPEC effector molecules in pathogenesis are discussed.

Indian Hedgehog is an antagonist of Wnt signaling in colonic epithelial cell differentiation

NARCIS (Netherlands)

van den Brink, Gijs R.; Bleuming, Sylvia A.; Hardwick, James C. H.; Schepman, Berber L.; Offerhaus, G. Johan; Keller, Josbert J.; Nielsen, Corinne; Gaffield, William; van Deventer, Sander J. H.; Roberts, Drucilla J.; Peppelenbosch, Maikel P.

2004-01-01

Wnt signaling defines the colonic epithelial progenitor cell phenotype(1), and mutations in the gene adenomatous polyposis coli (APC) that activate the Wnt pathway cause the familial adenomatous polyposis coli (FAP) syndrome and most sporadic colon cancers(2). The mechanisms that regulate the

E coli enteritis

Science.gov (United States)

... coli; Food poisoning - E. coli; E. coli diarrhea; Hamburger disease ... coleslaw or potato salad) that have been out of the refrigerator too ... reheated Fish or oysters Raw fruits or vegetables that have ...

The EAL domain protein YciR acts as a trigger enzyme in a c-di-GMP signalling cascade in E. coli biofilm control

Science.gov (United States)

Lindenberg, Sandra; Klauck, Gisela; Pesavento, Christina; Klauck, Eberhard; Hengge, Regine

2013-01-01

C-di-GMP—which is produced by diguanylate cyclases (DGC) and degraded by specific phosphodiesterases (PDEs)—is a ubiquitous second messenger in bacterial biofilm formation. In Escherichia coli, several DGCs (YegE, YdaM) and PDEs (YhjH, YciR) and the MerR-like transcription factor MlrA regulate the transcription of csgD, which encodes a biofilm regulator essential for producing amyloid curli fibres of the biofilm matrix. Here, we demonstrate that this system operates as a signalling cascade, in which c-di-GMP controlled by the DGC/PDE pair YegE/YhjH (module I) regulates the activity of the YdaM/YciR pair (module II). Via multiple direct interactions, the two module II proteins form a signalling complex with MlrA. YciR acts as a connector between modules I and II and functions as a trigger enzyme: its direct inhibition of the DGC YdaM is relieved when it binds and degrades c-di-GMP generated by module I. As a consequence, YdaM then generates c-di-GMP and—by direct and specific interaction—activates MlrA to stimulate csgD transcription. Trigger enzymes may represent a general principle in local c-di-GMP signalling. PMID:23708798

Molecular basis of juvenile hormone signaling

Czech Academy of Sciences Publication Activity Database

Jindra, Marek; Bellés, X.; Shinoda, T.

2015-01-01

Roč. 11, Oct 09 (2015), s. 39-46 ISSN 2214-5745 R&D Projects: GA ČR GA15-23681S Institutional support: RVO:60077344 Keywords : juvenile hormone * JH receptor * Drosophila melanogaster Subject RIV: ED - Physiology Impact factor: 2.719, year: 2015 http://www.sciencedirect.com/science/article/pii/S2214574515001297

Analysis and Design of Stimulus Response Curves of E. coli

Directory of Open Access Journals (Sweden)

Andreas Kremling

2012-11-01

Full Text Available Metabolism and signalling are tightly coupled in bacteria. Combining several theoretical approaches, a core model is presented that describes transcriptional and allosteric control of glycolysis in Escherichia coli. Experimental data based on microarrays, signalling components and extracellular metabolites are used to estimate kinetic parameters. A newly designed strain was used that adjusts the incoming glucose flux into the system and allows a kinetic analysis. Based on the results, prediction for intracelluar metabolite concentrations over a broad range of the growth rate could be performed and compared with data from literature.

Study on E. coli and Salmonella biofilms from fresh fruits and vegetables.

Science.gov (United States)

Amrutha, Balagopal; Sundar, Kothandapani; Shetty, Prathapkumar Halady

2017-04-01

Foodborne outbreaks associated with fresh fruits and vegetables are on the rise worldwide. Biofilm formation is one of the important traits of pathogens making them strongly attached to substrates as well as express virulence phenotypes. Present study investigates the biofilm forming ability of E. coli and Salmonella sp. isolated from fresh fruits and vegetables. A total of 53 strains, including 35 E. coli and 18 Salmonella sp. isolated from different fruit and vegetable samples were taken into account for the study. Initial screening for biofilm formation was done using Congo Red agar plate test. Results revealed that 22.8% E. coli and 22.2% Salmonella sp. were potential biofilm formers. However, the MTP (Micro-Titre Plate) assay suggested more isolates of both E. coli and Salmonella sp. were moderate to strong biofilm producers. Agar plate diffusion assay with Agrobacterium tumefaciens NTL-4 showed the production of quorum signaling molecules (AHLs) by three isolates of E. coli and one Salmonella sp. Two E. coli isolates showed a significant amount of EPS production indicating higher biofilm forming potential. The Presence of LUX R homologue gene ( sdi A) in two of the Salmonella isolates were confirmed by PCR which demonstrated their potential pathogenicity. Results of the work underline the biofilm forming and potentially virulent capacities of isolates from the surface of fruits and vegetables.

Using fluorescence measurement of zinc ions liberated from ZnS nanoparticle labels in bioassay for Escherichia coli O157:H7

International Nuclear Information System (INIS)

Cowles, Chad L.; Zhu Xiaoshan; Pai, Chi-Yun

2011-01-01

In this study, an alternative approach using ZnS nanoparticle biolabels as fluorescence signal transducers is reported for the immunoassay of E. coli O157:H7 in tap water samples. Instead of measuring the fluorescence of ZnS nanoparticles in the assay, the fluorescence signal is generated through the binding of zinc ions released from nanoparticle labels with zinc-ion sensitive fluorescence indicator Fluozin-3. In the assay, ZnS nanoparticles around 50 nm in diameter were synthesized, bioconjugated, and applied for the detection of E. coli O157:H7. The assay shows a detection range over two orders of magnitude and a detection limit around 1000 colony-forming units (cfu) of E. coli O157:H7.

E. Coli Infections

Science.gov (United States)

E. coli is the name of a type of bacteria that lives in your intestines. Most types of E. coli are harmless. However, some types can make you ... type causes travelers' diarrhea. The worst type of E. coli causes bloody diarrhea, and can sometimes cause kidney ...

Export of Cytochrome P450 105D1 to the Periplasmic Space of Escherichia coli

OpenAIRE

Kaderbhai, Mustak A.; Ugochukwu, Cynthia C.; Kelly, Steven L.; Lamb, David C.

2001-01-01

CYP105D1, a cytochrome P450 from Streptomyces griseus, was appended at its amino terminus to the secretory signal of Escherichia coli alkaline phosphatase and placed under the transcriptional control of the native phoA promoter. Heterologous expression in E. coli phosphate-limited medium resulted in abundant synthesis of recombinant CYP105D1 that was translocated across the bacterial inner membrane and processed to yield authentic, heme-incorporated P450 within the periplasmic space. Cell ext...

E. Coli

Science.gov (United States)

... for the bacteria's medical name Escherichia coli . The strange thing about these bacteria — and lots of other ... In some cases, E. coli poisoning can cause life-threatening kidney problems. What Can Kids Do? Adults ...

Up-regulation of intestinal vascular endothelial growth factor by Afa/Dr diffusely adhering Escherichia coli.

Directory of Open Access Journals (Sweden)

Gaëlle Cane

Full Text Available BACKGROUND: Angiogenesis has been recently described as a novel component of inflammatory bowel disease pathogenesis. The level of vascular endothelial growth factor (VEGF has been found increased in Crohn's disease and ulcerative colitis mucosa. To question whether a pro-inflammatory Escherichia coli could regulate the expression of VEGF in human intestinal epithelial cells, we examine the response of cultured human colonic T84 cells to infection by E. coli strain C1845 that belongs to the typical Afa/Dr diffusely adhering E. coli family (Afa/Dr DAEC. METHODOLOGY: VEGF mRNA expression was examined by Northern blotting and q-PCR. VEGF protein levels were assayed by ELISA and its bioactivity was analysed in endothelial cells. The bacterial factor involved in VEGF induction was identified using recombinant E. coli expressing Dr adhesin, purified Dr adhesin and lipopolysaccharide. The signaling pathway activated for the up-regulation of VEGF was identified using a blocking monoclonal anti-DAF antibody, Western blot analysis and specific pharmacological inhibitors. PRINCIPAL FINDINGS: C1845 bacteria induce the production of VEGF protein which is bioactive. VEGF is induced by adhering C1845 in both a time- and bacteria concentration-dependent manner. This phenomenon is not cell line dependent since we reproduced this observation in intestinal LS174, Caco2/TC7 and INT407 cells. Up-regulation of VEGF production requires: (1 the interaction of the bacterial F1845 adhesin with the brush border-associated decay accelerating factor (DAF, CD55 acting as a bacterial receptor, and (2 the activation of a Src protein kinase upstream of the activation of the Erk and Akt signaling pathways. CONCLUSIONS: Results demonstrate that a Afa/Dr DAEC strain induces an adhesin-dependent activation of DAF signaling that leads to the up-regulation of bioactive VEGF in cultured human intestinal cells. Thus, these results suggest a link between an entero-adherent, pro

Expression, crystallization and preliminary X-ray analysis of the periplasmic stress sensory protein RseB from Escherichia coli

International Nuclear Information System (INIS)

Wollmann, Petra; Zeth, Kornelius

2006-01-01

The periplasmic stress protein RseB from E. coli was cloned, expressed and crystallized. Crystallographic data are presented and structure solution using the multiple isomorphous replacement approach (MIR) is in progress. Sensing external stress in the bacterial periplasm and signal transduction to the cytoplasm are important functions of the CpxAR, Bae and σ E signalling pathways. In Escherichia coli, the σ E pathway can be activated through degradation of the antisigma factor RseA by DegS and YaeL. The periplasmic protein RseB plays an important role in this pathway by exerting a direct or indirect negative effect on YaeL cleavage efficiency. RseB from E. coli, missing the periplasmic signal sequence (RseB ΔN ), was cloned, expressed, purified and crystallized. Crystals were obtained in two different forms belonging to space group P42 1 2 (form I) and C222 1 (form II) and diffracted to 2.8 and 2.4 Å resolution, respectively. In crystal form I two copies of the protein were located in the asymmetric unit according to heavy-atom analysis, while crystal form II contained three copies

Development and maturation of Escherichia coli K-12 biofilms

DEFF Research Database (Denmark)

Reisner, A.; Haagensen, J.A.J.; Schembri, Mark

2003-01-01

The development and maturation of E. coli biofilms in flow-chambers was investigated. We found that the presence of transfer constitutive IncF plasmids induced biofilm development forming structures resembling those reported for Pseudomonas aeruginosa . The development occurred in a step...... occurred in conjugation pilus proficient plasmid-carrying strains. The final shapes of the expanding structures in the mature biofilm seem to be determined by the pilus configuration, as various mutants affected in the processing and activity of the transfer pili displayed differently structured biofilms....... We further provide evidence that flagella, type 1 fimbriae, curli and Ag43 are all dispensable for the observed biofilm maturation. In addition, our results indicate that cell-to-cell signalling mediated by autoinducer 2 (AI-2) is not required for differentiation of E. coli within a biofilm community...

Chromosomal features of Escherichia coli serotype O2:K2, an avian pathogenic E. coli

DEFF Research Database (Denmark)

Jørgensen, Steffen L; Kudirkiene, Egle; Li, Lili

2017-01-01

Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production econo...

Regulation of gene expression in Escherichia coli and its bacteriophage

International Nuclear Information System (INIS)

Higgins, C.F.

1986-01-01

This chapter reviews the study of prokaryotic gene expression beginning with a look at the regulation of the lactose operon and the mechanism of attenuation in the tryptophan operon to the more recent development of recombinant DNA technology. The chapter deals almost entirely with escherichia coli and its bacteriophage. The only experimental technique which the authors explore in some detail is the construction and use of gene and operon fusions which have revolutionized the study of gene expression. Various mechanisms by which E. Coli regulate the cellular levels of individual messenger-RNA species are described. Translational regulation of the cellular levels of messenger-RNA include signals encoded within the messenger-RNA molecule itself and regulatory molecules which interact with the messenger-RNA and alter it translational efficiency

The order of expression is a key factor in the production of active transglutaminase in Escherichia coli by co-expression with its pro-peptide

Directory of Open Access Journals (Sweden)

Liu Song

2011-12-01

Full Text Available Abstract Background Streptomyces transglutaminase (TGase is naturally synthesized as zymogen (pro-TGase, which is then processed to produce active enzyme by the removal of its N-terminal pro-peptide. This pro-peptide is found to be essential for overexpression of soluble TGase in E. coli. However, expression of pro-TGase by E. coli requires protease-mediated activation in vitro. In this study, we developed a novel co- expression method for the direct production of active TGase in E. coli. Results A TGase from S. hygroscopicus was expressed in E. coli only after fusing with the pelB signal peptide, but fusion with the signal peptide induced insoluble enzyme. Therefore, alternative protocol was designed by co-expressing the TGase and its pro-peptide as independent polypeptides under a single T7 promoter using vector pET-22b(+. Although the pro-peptide was co-expressed, the TGase fused without the signal peptide was undetectable in both soluble and insoluble fractions of the recombinant cells. Similarly, when both genes were expressed in the order of the TGase and the pro-peptide, the solubility of TGase fused with the signal peptide was not improved by the co-expression with its pro-peptide. Interestingly, active TGase was only produced by the cells in which the pro-peptide and the TGase were fused with the signal peptide and sequentially expressed. The purified recombinant and native TGase shared the similar catalytic properties. Conclusions Our results indicated that the pro-peptide can assist correct folding of the TGase inter-molecularly in E. coli, and expression of pro-peptide prior to that of TGase was essential for the production of active TGase. The co-expression strategy based on optimizing the order of gene expression could be useful for the expression of other functional proteins that are synthesized as a precursor.

Investigation of Growth Acceleration Factors of E. coli ET2174 by Use of DO Signal

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Batdorj Batjargal

2003-06-01

Full Text Available Specific growth rate of E. coliAT247 1 was estimated by on-line monitoring of DO level. The following results were obtained. Amino acid content of preculture medium was the sole reason for the two stages growth of recombinant strain E. coli AT2471. The experiment of on an individual amino acid influence showed that the addition of most acids contained in the preculture medium, except valine, cysteine and methionine, have neither beneficial nor negative effects on the cell growth. Valine stopped the cell growth and addition of isoleucine could reduce this negative effect. Addition of cysteine to the medium increased specific growth rate of cells from 0.49 h-I to 0.62 h-'; methionine addition increased it to 0.69 h-'. The combination of these two amino acids enhanced cell growth resulting in a high value of p 0.91 h-'.

Mapping Stress-Induced Changes in Autoinducer AI-2 Production in Chemostat-Cultivated Escherichia coli K-12

Science.gov (United States)

DeLisa, Matthew P.; Valdes, James J.; Bentley, William E.

2001-01-01

Numerous gram-negative bacteria employ a cell-to-cell signaling mechanism, termed quorum sensing, for controlling gene expression in response to population density. Recently, this phenomenon has been discovered in Escherichia coli, and while pathogenic E. coli utilize quorum sensing to regulate pathogenesis (i.e., expression of virulence genes), the role of quorum sensing in nonpathogenic E. coli is less clear, and in particular, there is no information regarding the role of quorum sensing during the overexpression of recombinant proteins. The production of autoinducer AI-2, a signaling molecule employed by E. coli for intercellular communication, was studied in E. coli W3110 chemostat cultures using a Vibrio harveyi AI-2 reporter assay (M. G. Surrette and B. L. Bassler, Proc. Natl. Acad. Sci. USA 95:7046–7050, 1998). Chemostat cultures enabled a study of AI-2 regulation through steady-state and transient responses to a variety of environmental stimuli. Results demonstrated that AI-2 levels increased with the steady-state culture growth rate. In addition, AI-2 increased following pulsed addition of glucose, Fe(III), NaCl, and dithiothreitol and decreased following aerobiosis, amino acid starvation, and isopropyl-β-d-thiogalactopyranoside-induced expression of human interleukin-2 (hIL-2). In general, the AI-2 responses to several perturbations were indicative of a shift in metabolic activity or state of the cells induced by the individual stress. Because of our interest in the expression of heterologous proteins in E. coli, the transcription of four quorum-regulated genes and 20 stress genes was mapped during the transient response to induced expression of hIL-2. Significant regulatory overlap was revealed among several stress and starvation genes and known quorum-sensing genes. PMID:11292813

E. Coli and Pregnancy

Science.gov (United States)

... chat Live Help Fact Sheets Share Escherichia coli (E. coli) Friday, 01 September 2017 In every pregnancy, a ... risk. This sheet talks about whether exposure to E. coli may increase the risk for birth defects over ...

Chromosomal features of Escherichia coli serotype O2:K2, an avian pathogenic E. coli.

Science.gov (United States)

Jørgensen, Steffen L; Kudirkiene, Egle; Li, Lili; Christensen, Jens P; Olsen, John E; Nolan, Lisa; Olsen, Rikke H

2017-01-01

Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production economy and welfare worldwide. An almost defining characteristic of avian pathogenic E. coli is the carriage of plasmids, which may encode virulence factors and antibiotic resistance determinates. For the same reason, plasmids of avian pathogenic E. coli have been intensively studied. However, genes encoded by the chromosome may also be important for disease manifestation and antimicrobial resistance. For the E. coli strain APEC_O2 the plasmids have been sequenced and analyzed in several studies, and E. coli APEC_O2 may therefore serve as a reference strain in future studies. Here we describe the chromosomal features of E. coli APEC_O2. E. coli APEC_O2 is a sequence type ST135, has a chromosome of 4,908,820 bp (plasmid removed), comprising 4672 protein-coding genes, 110 RNA genes, and 156 pseudogenes, with an average G + C content of 50.69%. We identified 82 insertion sequences as well as 4672 protein coding sequences, 12 predicated genomic islands, three prophage-related sequences, and two clustered regularly interspaced short palindromic repeats regions on the chromosome, suggesting the possible occurrence of horizontal gene transfer in this strain. The wildtype strain of E. coli APEC_O2 is resistant towards multiple antimicrobials, however, no (complete) antibiotic resistance genes were present on the chromosome, but a number of genes associated with extra-intestinal disease were identified. Together, the information provided here on E. coli APEC_O2 will assist in future studies of avian pathogenic E. coli strains, in particular regarding strain of E. coli APEC_O2, and aid in the general understanding of the pathogenesis of avian pathogenic E. coli .

Impinging jets controlled by fluidic input signal

Czech Academy of Sciences Publication Activity Database

Tesař, Václav; Trávníček, Zdeněk; Peszyński, K.

2016-01-01

Roč. 249, October (2016), s. 85-92 ISSN 0924-4247 R&D Projects: GA ČR GA13-23046S; GA ČR GA14-08888S Institutional support: RVO:61388998 Keywords : fluidics * jets * impinging jets * coanda effect Subject RIV: BK - Fluid Dynamics Impact factor: 2.499, year: 2016 http://www.sciencedirect.com/science/article/pii/S0924424716303880

Receptor density balances signal stimulation and attenuation in membrane-assembled complexes of bacterial chemotaxis signaling proteins

Science.gov (United States)

Besschetnova, Tatiana Y.; Montefusco, David J.; Asinas, Abdalin E.; Shrout, Anthony L.; Antommattei, Frances M.; Weis, Robert M.

2008-01-01

All cells possess transmembrane signaling systems that function in the environment of the lipid bilayer. In the Escherichia coli chemotaxis pathway, the binding of attractants to a two-dimensional array of receptors and signaling proteins simultaneously inhibits an associated kinase and stimulates receptor methylation—a slower process that restores kinase activity. These two opposing effects lead to robust adaptation toward stimuli through a physical mechanism that is not understood. Here, we provide evidence of a counterbalancing influence exerted by receptor density on kinase stimulation and receptor methylation. Receptor signaling complexes were reconstituted over a range of defined surface concentrations by using a template-directed assembly method, and the kinase and receptor methylation activities were measured. Kinase activity and methylation rates were both found to vary significantly with surface concentration—yet in opposite ways: samples prepared at high surface densities stimulated kinase activity more effectively than low-density samples, whereas lower surface densities produced greater methylation rates than higher densities. FRET experiments demonstrated that the cooperative change in kinase activity coincided with a change in the arrangement of the membrane-associated receptor domains. The counterbalancing influence of density on receptor methylation and kinase stimulation leads naturally to a model for signal regulation that is compatible with the known logic of the E. coli pathway. Density-dependent mechanisms are likely to be general and may operate when two or more membrane-related processes are influenced differently by the two-dimensional concentration of pathway elements. PMID:18711126

Diarrheagenic Escherichia coli Markers and Phenotypes among Fecal E. coli Isolates Collected from Nicaraguan Infants ▿

OpenAIRE

Reyes, Daniel; Vilchez, Samuel; Paniagua, Margarita; Colque-Navarro, Patricia; Weintraub, Andrej; Möllby, Roland; Kühn, Inger

2010-01-01

We analyzed the prevalence of diarrheagenic Escherichia coli (DEC) markers and common phenotypes in 2,164 E. coli isolates from 282 DEC-positive samples. Enteropathogenic E. coli (EPEC) and enteroaggregative E. coli (EAEC) were very diverse and were not correlated with diarrhea. Enterotoxigenic E. coli (ETEC) estA and enterohemorrhagic E. coli (EHEC) belonged to a few phenotypes and were significantly correlated with diarrhea.

Effect of bile on growth, peritoneal absorption, and blood clearance of Escherichia coli in E coli peritonitis

International Nuclear Information System (INIS)

Andersson, R.; Schalen, C.; Tranberg, K.G.

1991-01-01

The effect of intraperitoneal bile on growth, peritoneal absorption, and clearance of Escherichia coli was determined in E coli peritonitis in the rat. In E coli peritonitis, intraperitoneal bacterial counts gradually decreased, whereas they increased (after 2 hours) with subsequent development of bacteremia in E coli plus bile peritonitis. After an intraperitoneal injection of labeled bacteria, blood radioactivity was only initially lower in E coli plus bile peritonitis compared with E coli peritonitis. Clearance from blood was lower in E coli plus bile peritonitis than in E coli peritonitis. Organ localization was similar in E coli peritonitis and E coli plus bile peritonitis with decreased splenic, increased pulmonary, and unchanged hepatic uptakes compared with controls. Impaired peritoneal absorption of bacteria, together with impaired local host defense, is likely to enhance the noxious effect of bile in E coli peritonitis

Conjugation in Escherichia coli

Science.gov (United States)

Boyer, Herbert

1966-01-01

Boyer, Herbert (Yale University, New Haven, Conn.). Conjugation in Escherichia coli. J. Bacteriol. 91:1767–1772. 1966.—The sex factor of Escherichia coli K-12 was introduced into an E. coli B/r strain by circumventing the host-controlled modification and restriction incompatibilities known to exist between these closely related strains. The sexual properties of the constructed F+ B strain and its Hfr derivatives were examined. These studies showed that the E. coli strain B/r F+ and Hfr derivatives are similar to the E. coli strain K-12 F+ and Hfr derivatives. However, the site of sex factor integration was found to be dependent on the host genome. PMID:5327905

Aberrant expression of sonic hedgehog pathway in colon cancer and melanosis coli.

Science.gov (United States)

Wang, Zhong Chuan; Gao, Jun; Zi, Shu Ming; Yang, Ming; Du, Peng; Cui, Long

2013-08-01

To determine the hedgehog (Hh) signaling pathway correlated with the development of colon cancer and melanosis coli. Protein and mRNA levels of Hh signaling pathway components (sonic hedgehog [Shh], protein patched homolog 1 [Ptch 1], GLI family zinc finger 1 [Gli 1] and suppressor of fused homolog [Drosophila] [Sufu]) in 127 patients with colon cancer, 36 with melanosis coli and 20 adjacent normal mucosal tissues taken from surgical specimens were evaluated using antibody staining and quantitative real-time polymerase chain reaction. In adjacent normal tissue Shh and Ptch1, but not Gli1 or Sufu, were weakly expressed and mainly in the lining epithelium of the colonic mucosa. In cancerous tissues Shh and Gli1 were uniformly strong while Ptch1 was patchy and weak, and Sufu uniformly weak, which paralleled their levels of corresponding mRNA. Elevated protein levels of Shh and Ptch were significantly associated with mucinous colonic tissues. Elevated Sufu protein levels were positively correlated with the diameter and invasion of the tumor. In patients with melanosis coli, mRNA levels of Shh, Ptch1, Gli1 and Sufu were very low, which was similar to those of adjacent normal tissues; but protein levels of Shh, Ptch1 and Gli1, but not Sufu, were high, which was similar to those of cancerous tissues. The mRNA and protein levels of Hh pathway components are aberrantly elevated in colon cancer, which may be the potential molecular classification markers. Further studies are required to determine the role of melanosis coli in the colon tumorigenesis. © 2013 The Authors. Journal of Digestive Diseases © 2013 Wiley Publishing Asia Pty Ltd and Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine.

ECMDB 2.0: A richer resource for understanding the biochemistry of E. coli.

Science.gov (United States)

Sajed, Tanvir; Marcu, Ana; Ramirez, Miguel; Pon, Allison; Guo, An Chi; Knox, Craig; Wilson, Michael; Grant, Jason R; Djoumbou, Yannick; Wishart, David S

2016-01-04

ECMDB or the Escherichia coli Metabolome Database (http://www.ecmdb.ca) is a comprehensive database containing detailed information about the genome and metabolome of E. coli (K-12). First released in 2012, the ECMDB has undergone substantial expansion and many modifications over the past 4 years. This manuscript describes the most recent version of ECMDB (ECMDB 2.0). In particular, it provides a comprehensive update of the database that was previously described in the 2013 NAR Database Issue and details many of the additions and improvements made to the ECMDB over that time. Some of the most important or significant enhancements include a 13-fold increase in the number of metabolic pathway diagrams (from 125 to 1650), a 3-fold increase in the number of compounds linked to pathways (from 1058 to 3280), the addition of dozens of operon/metabolite signalling pathways, a 44% increase in the number of compounds in the database (from 2610 to 3760), a 7-fold increase in the number of compounds with NMR or MS spectra (from 412 to 3261) and a massive increase in the number of external links to other E. coli or chemical resources. These additions, along with many other enhancements aimed at improving the ease or speed of querying, searching and viewing the data within ECMDB should greatly facilitate the understanding of not only the metabolism of E. coli, but also allow the in-depth exploration of its extensive metabolic networks, its many signalling pathways and its essential biochemistry. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Autodisplay of the La/SSB protein on LPS-free E. coli for the diagnosis of Sjögren's syndrome.

Science.gov (United States)

Yoo, Gu; Dilkaute, Carina; Bong, Ji-Hong; Song, Hyun-Woo; Lee, Misu; Kang, Min-Jung; Jose, Joachim; Pyun, Jae-Chul

2017-05-01

The objective of this study was to present an immunoassay for the diagnosis of Sjögren's syndrome based on the autodisplayed La/SSB protein on the outer membrane of intact E. coli (strain UT-5600) and LPS-free E. coli (ClearColi™). As the first step, an autodisplay vector (pCK002) was transfected into intact E. coli and LPS-free E. coli for comparison of efficiency of autdisplay of La/SSB. The maximal level of La/SSB expression was estimated to be similar for LPS-free E. coli and intact E. coli at different optimal induction periods. Intact E. coli was found to grow twofold faster than LPS-free E. coli, and the maximal level of expression for LPS-free E. coli was obtained with a longer induction period. When the zeta potential was measured, both intact E. coli and LPS-free E. coli showed negative values, and the autodisplay of negatively charged La/SSB protein (pIE. coli and LPS-free E. coli resulted in a slight change in zeta potential values. E. coli with autodisplayed La/SSB protein was used for an immunoassay of anti-La/SSB antibodies for the diagnosis of Sjögren's syndrome. The surface of E. coli with the autodisplayed antigen was modified with rabbit serum and papain to prevent false positive signals because of nonspecific binding of unrelated antibodies from human serum. LPS-free E. coli with autodisplayed La/SSB protein yielded sensitivity and selectivity of 81.6% and 78.6%, respectively. The Bland-Altman test showed that the immunoassays based on LPS-free E. coli and intact E. coli with autodisplayed La/SSB protein were statistically equivalent to a clinical immunoassay for detection of anti-La/SSB antibodies (confidence coefficient 95%). Copyright © 2017 Elsevier Inc. All rights reserved.

Persistent discharges in dentate gyrus perisoma-inhibiting interneurons require hyperpolarization-activated cyclic nucleotide-gated channel activation.

Science.gov (United States)

Elgueta, Claudio; Köhler, Johannes; Bartos, Marlene

2015-03-11

Parvalbumin (PV)-expressing perisoma-inhibiting interneurons (PIIs) of the dentate gyrus integrate rapidly correlated synaptic inputs and generate short-duration action potentials that propagate along the axon to their output synapses, supporting fast inhibitory signaling onto their target cells. Here we show that PV-PIIs in rat and mouse dentate gyrus (DG) integrate their intrinsic activity over time and can turn into a persistent firing mode characterized by the ability to generate long-lasting trains of action potentials at ∼50 Hz in the absence of additional inputs. Persistent firing emerges in the axons remote from the axon initial segment and markedly depends on hyperpolarization-activated cyclic nucleotide-gated channel (HCNC) activation. Persistent firing properties are modulated by intracellular Ca(2+) levels and somatic membrane potential. Detailed computational single-cell PIIs models reveal that HCNC-mediated conductances can contribute to persistent firing during conditions of a shift in their voltage activation curve to more depolarized potentials. Paired recordings from PIIs and their target granule cells show that persistent firing supports strong inhibitory output signaling. Thus, persistent firing may emerge during conditions of intense activation of the network, thereby providing silencing to the circuitry and the maintenance of sparse activity in the dentate gyrus. Copyright © 2015 the authors 0270-6474/15/354131-09$15.00/0.

Effect of promoter strength and signal sequence on the periplasmic ...

African Journals Online (AJOL)

Two plasmids, pFLAG-ATS and pET 26b(+), were studied for the periplasmic expression of recombinant human interferon-2b (IFN-2b) in Escherichia coli. The pFLAG-ATS contains ompA signal sequence and tac promoter while pET 26b(+) contains pelB signal sequence and T7lac promoter. It was observed that periplasmic ...

A sensitive lateral flow biosensor for Escherichia coli O157:H7 detection based on aptamer mediated strand displacement amplification

Energy Technology Data Exchange (ETDEWEB)

Wu, Wei [College of Food Science and Engineering, Ocean University of China, Qingdao 266003 (China); Zhao, Shiming [Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China); Mao, Yiping [Yueyang Institute for Food and Drug Control, Yueyang 430198 (China); Fang, Zhiyuan [Affiliated Tumor Hospital of Guangzhou Medical University, Guangzhou 510095 (China); Lu, Xuewen [Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China); Zeng, Lingwen, E-mail: zeng6@yahoo.com [Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530 (China)

2015-02-25

Highlights: • Limit of detection as low as 10 CFU mL{sup −1}Escherichia coli O157:H7. • No need of antibodies and substituted with aptamers. • Isothermal strand displacement amplification for signal amplification. • Results observed by the naked eye. • Great potential application in the area of food control. - Abstract: Foodborne diseases caused by pathogens are one of the major problems in food safety. Convenient and sensitive point-of-care rapid diagnostic tests for food-borne pathogens have been a long-felt need of clinicians. Commonly used methods for pathogen detection rely on conventional culture-based tests, antibody-based assays and polymerase chain reaction (PCR)-based techniques. These methods are costly, laborious and time-consuming. Herein, we present a simple and sensitive aptamer based biosensor for rapid detection of Escherichia coli O157:H7 (E. coli O157:H7). In this assay, two different aptamers specific for the outmembrane of E. coli O157:H7 were used. One of the aptamers was used for magnetic bead enrichment, and the other was used as a signal reporter for this pathogen, which was amplified by isothermal strand displacement amplification (SDA) and further detected by a lateral flow biosensor. Only the captured aptamers on cell membrane were amplified, limitations of conventional DNA amplification based method such as false-positive can be largely reduced. The generated signals (red bands on the test zone of a lateral flow strip) can be unambiguously read out by the naked eye. As low as 10 colony forming units (CFU) of E. coli O157:H7 were detected in this study. Without DNA extraction, the reduced handling and simpler equipment requirement render this assay a simple and rapid alternative to conventional methods.

A sensitive lateral flow biosensor for Escherichia coli O157:H7 detection based on aptamer mediated strand displacement amplification

International Nuclear Information System (INIS)

Wu, Wei; Zhao, Shiming; Mao, Yiping; Fang, Zhiyuan; Lu, Xuewen; Zeng, Lingwen

2015-01-01

Highlights: • Limit of detection as low as 10 CFU mL −1 Escherichia coli O157:H7. • No need of antibodies and substituted with aptamers. • Isothermal strand displacement amplification for signal amplification. • Results observed by the naked eye. • Great potential application in the area of food control. - Abstract: Foodborne diseases caused by pathogens are one of the major problems in food safety. Convenient and sensitive point-of-care rapid diagnostic tests for food-borne pathogens have been a long-felt need of clinicians. Commonly used methods for pathogen detection rely on conventional culture-based tests, antibody-based assays and polymerase chain reaction (PCR)-based techniques. These methods are costly, laborious and time-consuming. Herein, we present a simple and sensitive aptamer based biosensor for rapid detection of Escherichia coli O157:H7 (E. coli O157:H7). In this assay, two different aptamers specific for the outmembrane of E. coli O157:H7 were used. One of the aptamers was used for magnetic bead enrichment, and the other was used as a signal reporter for this pathogen, which was amplified by isothermal strand displacement amplification (SDA) and further detected by a lateral flow biosensor. Only the captured aptamers on cell membrane were amplified, limitations of conventional DNA amplification based method such as false-positive can be largely reduced. The generated signals (red bands on the test zone of a lateral flow strip) can be unambiguously read out by the naked eye. As low as 10 colony forming units (CFU) of E. coli O157:H7 were detected in this study. Without DNA extraction, the reduced handling and simpler equipment requirement render this assay a simple and rapid alternative to conventional methods

Sign epistasis caused by hierarchy within signalling cascades

NARCIS (Netherlands)

Nghe, Philippe; Kogenaru, Manjunatha; Tans, S.J.

2018-01-01

Sign epistasis is a central evolutionary constraint, but its causal factors remain difficult to predict. Here we use the notion of parameterised optima to explain epistasis within a signalling cascade, and test these predictions in Escherichia coli. We show that sign epistasis arises from the

The membrane transporter PotE is required for virulence in avian pathogenic Escherichia coli (APEC)

DEFF Research Database (Denmark)

Guerra, Priscila Regina; Herrero-Fresno, Ana; Pors, Susanne Elisabeth

2018-01-01

Over the last few years, polyamines have been described as key-signal of virulence in pathogenic bacteria. In the current study, we investigated whether the knockout of genes related to polyamine biosynthesis and putrescine transport affected the virulence of an avian pathogenic E. coli (APEC...

Graphene Field-Effect Transistors for the Sensitive and Selective Detection of Escherichia coli Using Pyrene-Tagged DNA Aptamer.

Science.gov (United States)

Wu, Guangfu; Dai, Ziwen; Tang, Xin; Lin, Zihong; Lo, Pik Kwan; Meyyappan, M; Lai, King Wai Chiu

2017-10-01

This study reports biosensing using graphene field-effect transistors with the aid of pyrene-tagged DNA aptamers, which exhibit excellent selectivity, affinity, and stability for Escherichia coli (E. coli) detection. The aptamer is employed as the sensing probe due to its advantages such as high stability and high affinity toward small molecules and even whole cells. The change of the carrier density in the probe-modified graphene due to the attachment of E. coli is discussed theoretically for the first time and also verified experimentally. The conformational change of the aptamer due to the binding of E. coli brings the negatively charged E. coli close to the graphene surface, increasing the hole carrier density efficiently in graphene and achieving electrical detection. The binding of negatively charged E. coli induces holes in graphene, which are pumped into the graphene channel from the contact electrodes. The carrier mobility, which correlates the gate voltage to the electrical signal of the APG-FETs, is analyzed and optimized here. The excellent sensing performance such as low detection limit, high sensitivity, outstanding selectivity and stability of the graphene biosensor for E. coli detection paves the way to develop graphene biosensors for bacterial detection. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A biosensor platform for rapid detection of E. coli in drinking water.

Science.gov (United States)

Hesari, Nikou; Alum, Absar; Elzein, Mohamad; Abbaszadegan, Morteza

2016-02-01

There remains a need for rapid, specific and sensitive assays for the detection of bacterial indicators for water quality monitoring. In this study, a strategy for rapid detection of Escherichia coli in drinking water has been developed. This strategy is based on the use of the substrate 4-methylumbelliferyl-β-d-glucuronide (MUG), which is hydrolyzed rapidly by the action of E. coli β-d-glucuronidase (GUD) enzyme to yield a fluorogenic 4-methylumbelliferone (4-MU) product that can be quantified and related to the number of E. coli cells present in water samples. In this study, the detection time required for the biosensor response ranged between 20 and 120 min, depending on the number of bacteria in the sample. This approach does not need extensive sample processing with a rapid detection capability. The specificity of the MUG substrate was examined in both, pure cultures of non-target bacterial genera such as Klebsiella, Salmonella, Enterobacter and Bacillus. Non-target substrates that included 4-methylumbelliferyl-β-d-galactopyranoside (MUGal) and l-leucine β-naphthylamide aminopeptidase (LLβ-N) were also investigated to identify nonspecific patterns of enzymatic activities in E. coli. GUD activity was found to be specific for E. coli and no further enzymatic activity was detected by other species. In addition, fluorescence assays were performed for the detection of E. coli to generate standard curves; and the sensitivity of the GUD enzymatic response was measured and repeatedly determined to be less than 10 E. coli cells in a reaction vial. The applicability of the method was tested by performing multiple fluorescence assays under pure and mixed bacterial flora in environmental samples. The results of this study showed that the fluorescence signals generated in samples using specific substrate molecules can be utilized to develop a bio-sensing platform for the detection of E. coli in drinking water. Furthermore, this system can be applied independently or

Annual Surveillance Summary: Escherichia coli (E. coli) Infections in the Military Health System (MHS), 2015

Science.gov (United States)

2017-03-01

Annual Surveillance Summary: Escherichia coli ( E . coli ) Infections in the Military Health System (MHS...or position of the Department of the Navy, Department of Defense, nor the U.S. Government. i i E . coli in the MHS: Annual Summary 2015 Prepared...March 2017 EpiData Center Department NMCPHC-EDC-TR-187-2017 ii ii E . coli in the MHS: Annual Summary 2015 Prepared March 2017 EpiData

Protective effects of indigenous Escherichia coli against a pathogenic E. coli challenge strain in pigs.

Science.gov (United States)

Vahjen, W; Cuisiniere, T; Zentek, J

2017-10-13

To investigate the inhibitory effect of indigenous enterobacteria on pathogenic Escherichia coli, a challenge trial with postweaning pigs was conducted. A pathogenic E. coli strain was administered to all animals and their health was closely monitored thereafter. Faecal samples were taken from three healthy and three diarrhoeic animals. Samples were cultivated on MacConkey agar and isolates were subcultured. A soft agar overlay assay was used to determine the inhibitory activity of the isolates. A total of 1,173 enterobacterial isolates were screened for their ability to inhibit the E. coli challenge strain. Colony forming units of enterobacteria on MacConkey agar were not different between healthy and diarrhoeic animals in the original samples. Furthermore, numbers of isolates per animal were also not significantly different between healthy (482 isolates) and diarrhoeic animals (691 isolates). A total of 43 isolates (3.7%) with inhibitory activity against the pathogenic E. coli challenge strain were detected. All inhibitory isolates were identified as E. coli via MALDI-TOF. The isolates belonged to the phylotypes A, C and E. Many isolates (67.4%) were commensal E. coli without relevant porcine pathogenic factors, but toxin- and fimbrial genes (stx2e, fae, estIb, elt1a, fas, fan) were detected in 14 inhibitory isolates. Healthy animals showed significantly (P=0.003) more inhibitory isolates (36 of 482 isolates; 7.5%) than diseased animals (7 of 691 isolates; 1.0%). There were no significant correlations regarding phylotype or pathogenic factors between healthy and diseased animals. This study has shown that a small proportion of indigenous E. coli is able to inhibit in vitro growth of a pathogenic E. coli strain in pigs. Furthermore, healthy animals possess significantly more inhibitory E. coli strains than diarrhoeic animals. The inhibition of pathogenic E. coli by specific indigenous E. coli strains may be an underlying principle for the containment of pathogenic

Serotonin disturbs colon epithelial tolerance of commensal E. coli by increasing NOX2-derived superoxide.

Science.gov (United States)

Banskota, Suhrid; Regmi, Sushil Chandra; Gautam, Jaya; Gurung, Pallavi; Lee, Yu-Jeong; Ku, Sae Kwang; Lee, Jin-Hyung; Lee, Jintae; Chang, Hyeun Wook; Park, Sang Joon; Kim, Jung-Ae

2017-05-01

Adherent-invasive E. coli colonization and Toll-like receptor (TLR) expression are increased in the gut of inflammatory bowel disease (IBD) patients. However, the underlying mechanism of such changes has not been determined. In the current study, it was examined whether gut serotonin (5-hydroxytryptamine, 5-HT) can induce adherent-invasive E. coli colonization and increase TLR expression. In a co-culture system, commensal E. coli strain (BW25113, BW) adhered minimally to colon epithelial cells, but this was significantly enhanced by 5-HT to the level of a pathogenic strain (EDL933). Without inducing bacterial virulence, such as, biofilm formation, 5-HT enhanced BW-induced signaling in colon epithelial cells, that is, NADPH oxidase (NOX)-dependent superoxide production, the up-regulations of IL-8, TLR2, TLR4, and ICAM-1, and the down-regulations of E-cadherin and claudin-2. In a manner commensurate with these gene modulations, BW induced an increase in NF-κB and a decrease in GATA reporter signals in colon epithelial cells. However, 5-HT-enhanced BW adhesion and colon epithelial responses were blocked by knock-down of NOX2, TLR2, or TLR4. In normal mice, 5-HT induced the invasion of BW into gut submucosa, and the observed molecular changes were similar to those observed in vitro, except for significant increases in TNFα and IL-1β, and resulted in death. In dextran sulfate sodium-induced colitis mice (an IBD disease model), in which colonic 5-HT levels were markedly elevated, BW administration induced death in along with large amount of BW invasion into colon submucosa, and time to death was negatively related to the amount of BW injected. Taken together, our results demonstrate that 5-HT induces the invasion of commensal E. coli into gut submucosa by amplifying commensal bacteria-induced epithelial signaling (superoxide production and the inductions of NOX2 and TLR2/TLR4). The authors suggest that these changes may constitute the molecular basis for the

Enterohemorrhagic Escherichia coli (EHEC

Directory of Open Access Journals (Sweden)

Abdullah Kilic

2011-08-01

Full Text Available Escherichia coli is a bacterium that is commonly found in the gut of humans and warm-blooded animals. Most strains of E. coli are harmless for human. E. coli O157:H7 is the most common member of a group of pathogenic E. coli strains known variously as enterohaemorrhagic, verocytotoxin-producing, or Shiga-toxin-producing organisms. EHEC bacterium is the major cause of haemorrhagic colitis and haemolytic uraemic syndrome. The reservoir of this pathogen appears to be mainly cattle and other ruminants such as camels. It is transmitted to humans primarily through consumption of contaminated foods. [TAF Prev Med Bull 2011; 10(4.000: 387-388

Impact of dry chilling on the genetic diversity of Escherichia coli on beef carcasses and on the survival of E. coli and E. coli O157.

Science.gov (United States)

Visvalingam, Jeyachchandran; Liu, Yang; Yang, Xianqin

2017-03-06

The objective of this study was to examine the effect of dry chilling on the genetic diversity of naturally occurring Escherichia coli on beef carcasses, and to examine whether two populations of E. coli recovered from carcasses during chilling and E. coli O157 differed in their response to desiccation. Isolates of E. coli were obtained from beef carcasses during a 67h dry chilling process and were genotyped using multiple-locus variable-number tandem-repeat analysis (MLVA). Ten E. coli genotypes found only at 0h (group A) and found more than once (group B), as well as five strains of E. coli O157 (group C) were inoculated on stainless steel coupons and their survival was examined after exposure to 75 and 100% relative humidity (RH) at 0 or 35°C for 67h. A total of 450 E. coli isolates were obtained, with 254, 49, 49, 51, 23, 20, and 4 from 0, 1, 2, 4, 6, 8 and 24h of chilling, respectively. No E. coli were recovered at 67h. MLVA of the isolates revealed 173 distinct genotypes. Genetic diversity of E. coli isolates, defined as ratio of the number of isolates to the number of genotypes, remained between 2.3 and 1.3 during the 24h of chilling. All strains inoculated on stainless steel coupons and exposed to 75% RH at 35°C were completely inactivated, irrespective of their groups. Inactivation of E. coli of the three groups was not significantly (P>0.05) different by exposure to 75% RH at 0°C. The findings indicate that the genetic diversity of E. coli on beef carcasses was not affected by dry chilling. In addition, inactivation of E. coli genotypes and E. coli O157 by desiccation on stainless steel simulating dry chilling conditions did not differ significantly (P>0.05). Thus, dry chilling may be used as an effective antimicrobial intervention for beef carcasses. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Cellulose as an Architectural Element in Spatially Structured Escherichia coli Biofilms

Science.gov (United States)

Serra, Diego O.; Richter, Anja M.

2013-01-01

Morphological form in multicellular aggregates emerges from the interplay of genetic constitution and environmental signals. Bacterial macrocolony biofilms, which form intricate three-dimensional structures, such as large and often radially oriented ridges, concentric rings, and elaborate wrinkles, provide a unique opportunity to understand this interplay of “nature and nurture” in morphogenesis at the molecular level. Macrocolony morphology depends on self-produced extracellular matrix components. In Escherichia coli, these are stationary phase-induced amyloid curli fibers and cellulose. While the widely used “domesticated” E. coli K-12 laboratory strains are unable to generate cellulose, we could restore cellulose production and macrocolony morphology of E. coli K-12 strain W3110 by “repairing” a single chromosomal SNP in the bcs operon. Using scanning electron and fluorescence microscopy, cellulose filaments, sheets and nanocomposites with curli fibers were localized in situ at cellular resolution within the physiologically two-layered macrocolony biofilms of this “de-domesticated” strain. As an architectural element, cellulose confers cohesion and elasticity, i.e., tissue-like properties that—together with the cell-encasing curli fiber network and geometrical constraints in a growing colony—explain the formation of long and high ridges and elaborate wrinkles of wild-type macrocolonies. In contrast, a biofilm matrix consisting of the curli fiber network only is brittle and breaks into a pattern of concentric dome-shaped rings separated by deep crevices. These studies now set the stage for clarifying how regulatory networks and in particular c-di-GMP signaling operate in the three-dimensional space of highly structured and “tissue-like” bacterial biofilms. PMID:24097954

Can E. coli fly?

DEFF Research Database (Denmark)

Lindeberg, Yrja Lisa; Egedal, Karen; Hossain, Zenat Zebin

2018-01-01

, and the numbers of flies landing on the exposed rice were counted. Following exposure, the surface of the rice was microbiologically and molecularly analysed for the presence of E. coli and genes of diarrheagenic E. coli and Shigella strains. RESULTS: Rice was at greater risk (p ... with E. coli if flies landed on the rice than if no flies landed on the rice (odds ratio 5·4 (p ...-landings, the average CFU per fly-landing was > 0·6 x 103 CFU. Genes of diarrheagenic E. coli and Shigella species were detected in 39 of 60 (65%) of exposed rice samples. Two fly species were identified; the common housefly (Musca domestica) and the oriental latrine fly (Chrysomya megacephala). CONCLUSION: Flies may...

Functionalized gold nanorod-based labels for amplified electrochemical immunoassay of E. coli as indicator bacteria relevant to the quality of dairy product.

Science.gov (United States)

Zhang, Xinai; Zhang, Fan; Zhang, Hongyin; Shen, Jianzhong; Han, En; Dong, Xiaoya

2015-01-01

In this paper, we report an amplified electrochemical immunoassay for Escherichia coli as indicator bacteria relevant to the quality of dairy product using the functionalized gold nanorod-based labels ({dAb-AuNR-FCA}). The {dAb-AuNR-FCA} labels were designed by exploiting silica-functionalized gold nanorods (AuNR@SiO2) as the carriers for immobilization of detection antibody (dAb) and ferrocenecarboxylic acid (FCA), in which dAb was used for recognition of E. coli and FCA tags served as signal-generating molecule. Greatly amplified signal was achieved in the sandwich-type immunoassay when enormous FCA linked to AuNR@SiO2. Compared with the commercially available {dAb-FCA}, the {dAb-AuNR-FCA} labels exhibited a better performance for E. coli assay due to the advantages of AuNR@SiO2 as carriers. Under optimal experimental conditions, it showed a linear relationship between the peak current of FCA and the logarithmic value of E. coli concentration ranging from 1.0×10(2) to 5.0×10(4) cfu mL(-1) with a detection limit of 60 cfu mL(-1) (S/N=3), and the electrochemical detection of E. coli could be achieved in 3h. Moreover, the proposed strategy was used to determine E. coli in dairy product (pure fresh milk, yogurt in shelf-life, and expired yogurt), and the recoveries of standard additions were in the range of 95.1-106%. This proposed strategy exhibited rapid response, high sensitivity and specificity for E. coli assay in dairy product, and could become a promising technique to estimate the quality of dairy product. Copyright © 2014 Elsevier B.V. All rights reserved.

99mTechnetium labelled Escherichia coli

International Nuclear Information System (INIS)

Diniz, S.O.F.; Cardoso, V.N.; Resende, B.M.; Nunan, E.A.; Simal, C.J.R.

1999-01-01

Samples of a culture of unlabeled Escherichia coli were incubated with different concentrations of stannous chloride for various time periods. 99m Tc (26.0 MBq) was added to each preparation and the results showed a labelling yield of 98% for E. coli. Since the bacterial viability of 99m Tc-E. coli and E. coli did not show any statistical differences, these results demonstrate that labelling of E. coli with 99m Tc does not modify the bacterial viability, and the radiolabelled bacteria may be a good model to study bacterial translocation

Subtractive Inhibition Assay for the Detection of E. coli O157:H7 Using Surface Plasmon Resonance

Directory of Open Access Journals (Sweden)

Chengyan Si

2011-03-01

Full Text Available A surface plasmon resonance (SPR immunosensor was developed for the detection of E. coli O157:H7 by means of a new subtractive inhibition assay. In the subtractive inhibition assay, E. coli O157:H7 cells and goat polyclonal antibodies for E. coli O157:H7 were incubated for a short of time, and then the E. coli O157:H7 cells which bound antibodies were removed by a stepwise centrifugation process. The remaining free unbound antibodies were detected through interaction with rabbit anti-goat IgG polyclonal antibodies immobilized on the sensor chip using a BIAcore 3000 biosensor. The results showed that the signal was inversely correlated with the concentration of E. coli O157:H7 cells in a range from 3.0 × 104 to 3.0 × 108 cfu/mL with a detection limit of 3.0 × 104 cfu/mL. Compared with direct SPR by immobilizing antibodies on the chip surface to capture the bacterial cells and ELISA for E. coli O157:H7 (detection limit: both 3.0 × 105 cfu/mL in this paper, the detection limit of subtractive inhibition assay method was reduced by one order of magnitude. The method simplifies bacterial cell detection to protein-protein interaction, which has the potential for providing a practical alternative for the monitoring of E. coli O157:H7 and other pathogens.

Responses triggered in chloroplast of Chlorella variabilis NC64A by long-term association with Paramecium bursaria.

Science.gov (United States)

Minaeva, Ekaterina; Ermilova, Elena

2017-07-01

The unicellular green alga Chlorella variabilis NC64A is an endosymbiont of the ciliate Paramecium bursaria. The host's control, including the transfer of biochemical substrates from P. bursaria to C. variabilis, is involved in symbiotic relationships. C. variabilis NC64A that had been re-infected to P. bursaria for more than 1 year and isolated from the host showed higher chlorophyll levels compared to those in free-living cells. Unlike the host, the expression of C. variabilis NC64A heat shock 70 kDa protein was independent of establishment of endosymbiosis. In symbiotic cells, the levels of PII signal transduction protein (CvPII) that coordinate the central C/N anabolic metabolism were slightly higher than those in free-living cells. Furthermore, the environmental cues (light and host food bacteria availability) affected the abundance of CvPII, suggesting that synthesis of the protein was influenced by the host. Moreover, arginine concentrations in the symbiotic algae of P. bursaria were also controlled by the host's nutritional conditions. Together, our results imply that signal substrates and/or products of metabolism in host cells might act as messengers mediating the regulation of key events in symbiont cells.

The oxygen effect in E. coli cells

International Nuclear Information System (INIS)

Myasnik, M.N.; Skvortsov, V.G.; Sokolov, V.A.

1982-01-01

In experiments on E. coli strains deficient in some stages of DNA repair from radiation damages, it was demonstrated that the value of the oxygen effect, under optimal conditions for manifestation thereof, decreases in the following order: E. coli WP2 (the wild type) → E. coli WP2 exr - and E. coli B → E. coli WP2 uvr A6 → E. coli WP2 rec Al and E. coli WP2 hcr - exr - . It was detected that 0.14 M NaCl solution sensitizes the anoxic cells of some E. coli strains to the effect of γ-radiation. It was established that mutation of the uvr A-gene increases sharply the sensitivity of cells to iradiation under the anoxic conditions in the presence of NaCl, the reverse'' oxygen effect being observed

Hemolytic porcine intestinal Escherichia coli without virulence-associated genes typical of intestinal pathogenic E. coli.

Science.gov (United States)

Schierack, Peter; Weinreich, Joerg; Ewers, Christa; Tachu, Babila; Nicholson, Bryon; Barth, Stefanie

2011-12-01

Testing 1,666 fecal or intestinal samples from healthy and diarrheic pigs, we obtained hemolytic Escherichia coli isolates from 593 samples. Focusing on hemolytic E. coli isolates without virulence-associated genes (VAGs) typical for enteropathogens, we found that such isolates carried a broad variety of VAGs typical for extraintestinal pathogenic E. coli.

escherichia coli serotypes confirmed in experimental mammary ...

African Journals Online (AJOL)

DJFLEX

VARIATIONS IN VIRULENCE OF THREE (3) ESCHERICHIA COLI. SEROTYPES CONFIRMED IN ... ows are susceptible to E. coli infection because. E. coli exist in the .... Coli infections in mice: A laboratory animal model for research in.

Targeting Wnt signaling in colorectal cancer. A Review in the Theme: Cell Signaling: Proteins, Pathways and Mechanisms

Science.gov (United States)

Novellasdemunt, Laura; Antas, Pedro

2015-01-01

The evolutionarily conserved Wnt signaling pathway plays essential roles during embryonic development and tissue homeostasis. Notably, comprehensive genetic studies in Drosophila and mice in the past decades have demonstrated the crucial role of Wnt signaling in intestinal stem cell maintenance by regulating proliferation, differentiation, and cell-fate decisions. Wnt signaling has also been implicated in a variety of cancers and other diseases. Loss of the Wnt pathway negative regulator adenomatous polyposis coli (APC) is the hallmark of human colorectal cancers (CRC). Recent advances in high-throughput sequencing further reveal many novel recurrent Wnt pathway mutations in addition to the well-characterized APC and β-catenin mutations in CRC. Despite attractive strategies to develop drugs for Wnt signaling, major hurdles in therapeutic intervention of the pathway persist. Here we discuss the Wnt-activating mechanisms in CRC and review the current advances and challenges in drug discovery. PMID:26289750

Prevalence and behavior of multidrug-resistant shiga toxin-producing Escherichia coli, enteropathogenic E. coli and enterotoxigenic E. coli on coriander.

Science.gov (United States)

Gómez-Aldapa, Carlos A; Segovia-Cruz, Jesús A; Cerna-Cortes, Jorge F; Rangel-Vargas, Esmeralda; Salas-Rangel, Laura P; Gutiérrez-Alcántara, Eduardo J; Castro-Rosas, Javier

2016-10-01

The prevalence and behavior of multidrug-resistant diarrheagenic Escherichia coli pathotypes on coriander was determined. One hundred coriander samples were collected from markets. Generic E. coli were determined using the most probable number procedure. Diarrheagenic E. coli pathotypes (DEPs) were identified using two multiplex polymerase chain reaction procedures. Susceptibility to sixteen antibiotics was tested for the isolated DEPs strains by standard test. The behavior of multidrug-resistant DEPs isolated from coriander was determined on coriander leaves and chopped coriander at 25°± 2 °C and 3°± 2 °C. Generic E. coli and DEPs were identified, respectively, in 43 and 7% of samples. Nine DEPs strains were isolated from positive coriander samples. The identified DEPs included Shiga toxin-producing E. coli (STEC, 4%) enterotoxigenic E. coli (ETEC, 2%) and enteropathogenic E. coli (EPEC, 1%). All isolated DEPs strains exhibited multi-resistance to antibiotics. On inoculated coriander leaves stored at 25°± 2 °C or 3°± 2 °C, no growth was observed for multidrug-resistant DEPs strains. However, multidrug-resistant DEPs strains grew in chopped coriander: after 24 h at 25° ± 2 °C, DEPs strains had grown to approximately 3 log CFU/g. However, at 3°± 2 °C the bacterial growth was inhibited. To the best of our knowledge, this is the first report of the presence and behavior of multidrug-resistant STEC, ETEC and EPEC on coriander and chopped coriander. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure of putative CutA1 from Homo sapiens determined at 2.05 Å resolution

International Nuclear Information System (INIS)

Bagautdinov, Bagautdin; Matsuura, Yoshinori; Bagautdinova, Svetlana; Kunishima, Naoki; Yutani, Katsuhide

2008-01-01

The X-ray structure of human CutA1 was solved in space group P2 1 2 1 2 1 , with unit-cell parameters a = 68.69, b = 88.84, c = 125.33 Å and six molecules per asymmetric unit. The structure of human brain CutA1 (HsCutA1) has been determined using diffraction data to 2.05 Å resolution. HsCutA1 has been implicated in the anchoring of acetylcholinesterase in neuronal cell membranes, while its bacterial homologue Escherichia coli CutA1 is involved in copper tolerance. Additionally, the structure of HsCutA1 bears similarity to that of the signal transduction protein PII, which is involved in regulation of nitrogen metabolism. Although several crystal structures of CutA1 from various sources with different rotation angles and degrees of interaction between trimer interfaces have been reported, the specific functional role of CutA1 is still unclear. In this study, the X-ray structure of HsCutA1 was determined in space group P2 1 2 1 2 1 , with unit-cell parameters a = 68.69, b = 88.84, c = 125.33 Å and six molecules per asymmetric unit. HsCutA1 is a trimeric molecule with intertwined antiparallel β-strands; each subunit has a molecular weight of 14.6 kDa and contains 135 amino-acid residues. In order to obtain clues to the possible function of HsCutA1, its crystal structure was compared with those of other CutA1 and PII proteins

Cloned polynucleotide and synthetic oligonucleotide probes used in colony hybridization are equally efficient in the identification of enterotoxigenic Escherichia coli

International Nuclear Information System (INIS)

Sommerfelt, H.; Kalland, K.H.; Raj, P.; Moseley, S.L.; Bhan, M.K.; Bjorvatn, B.

1988-01-01

Restriction endonuclease-generated polynucleotide and synthetically produced oligonucleotide gene probes used in colony hybridization assays proved to be efficient for the detection and differentiation of enterotoxigenic Escherichia coli. To compare their relative efficiencies, these two sets of probes were radiolabeled with 32 P and were applied to 74 strains of E. coli with known enterotoxin profiles and to 156 previously unexamined E. coli isolates. The enterotoxigenic bacteria Vibrio cholerae O1, Vibrio cholerae non-O1 (NAG), Yersinia enterocolitica, and E. coli harboring the plasmid vectors of the polynucleotide gene probes were examined for further evaluation of probe specificity. The two classes of probes showed a perfect concordance in their specific detection and differentiation of enterotoxigenic E. coli. In the analysis of six strains, the signal strength on autoradiography after hybridization with oligonucleotides was weaker than that obtained after hybridization with polynucleotide probes. The probes did not hybridize with DNA from V. cholerae O1, V. cholerae non-O1 (NAG), or Y. enterocolitica. The strains of E. coli harboring the plasmid vectors of the polynucleotide gene probes were, likewise, negative in the hybridization assays

Cloned polynucleotide and synthetic oligonucleotide probes used in colony hybridization are equally efficient in the identification of enterotoxigenic Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Sommerfelt, H.; Kalland, K.H.; Raj, P.; Moseley, S.L.; Bhan, M.K.; Bjorvatn, B.

1988-11-01

Restriction endonuclease-generated polynucleotide and synthetically produced oligonucleotide gene probes used in colony hybridization assays proved to be efficient for the detection and differentiation of enterotoxigenic Escherichia coli. To compare their relative efficiencies, these two sets of probes were radiolabeled with /sup 32/P and were applied to 74 strains of E. coli with known enterotoxin profiles and to 156 previously unexamined E. coli isolates. The enterotoxigenic bacteria Vibrio cholerae O1, Vibrio cholerae non-O1 (NAG), Yersinia enterocolitica, and E. coli harboring the plasmid vectors of the polynucleotide gene probes were examined for further evaluation of probe specificity. The two classes of probes showed a perfect concordance in their specific detection and differentiation of enterotoxigenic E. coli. In the analysis of six strains, the signal strength on autoradiography after hybridization with oligonucleotides was weaker than that obtained after hybridization with polynucleotide probes. The probes did not hybridize with DNA from V. cholerae O1, V. cholerae non-O1 (NAG), or Y. enterocolitica. The strains of E. coli harboring the plasmid vectors of the polynucleotide gene probes were, likewise, negative in the hybridization assays.

Identification and Prevalence of Escherichia coli and Escherichia coli O157: H7 in Foods

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Ancuta Mihaela Rotar

2013-11-01

Full Text Available The objective of this study is to investigate the incidence of Escherichia coli in animal and non-animal foods, and mainly the incidence of the serotype O157: H7 producing verotoxin. The presence of common Escherichia coli and Escherichia coli O157: H7 in various foods (of animal and non animal origin was performed in Transylvania area. We analyzed a total of one hundred forty-one samples of minced meat, one hundred twenty-six samples of meat , twenty six samples of meat products, five samples of alcoholic beverages, three samples of seafood, one hundred samples of cheese from pasteurized milk, seventeen samples of butter, four samples of vegetables and one sample of milk powder, using the standard cultural method and Vidas Eco method for E. coli O157: H7 strains. E. coli was identified in 50 samples of minced meat, 55 samples of meat prepared, 4 samples of meat products, 2 samples of alcoholic beverages, 25 samples of cheese from pasteurized milk, 6 samples of butter and 1 sample of vegetables. In this study were not been identified any foods contaminated with the E. coli O157: H7 serotype. The results of this reasearch have demostrated that E. coli wich represents a hygienic indicator of recent food contamination, can be destroyed with heat treatment and hygienic handling of foods. Our country over the years has been among the few countries where the incidence of the E. coli O157: H7 serotype has been minimal.

Functional expression of a human GDP-L-fucose transporter in Escherichia coli.

Science.gov (United States)

Förster-Fromme, Karin; Schneider, Sarah; Sprenger, Georg A; Albermann, Christoph

2017-02-01

To investigate the translocation of nucleotide-activated sugars from the cytosol across a membrane into the endoplasmatic reticulum or the Golgi apparatus which is an important step in the synthesis of glycoproteins and glycolipids in eukaryotes. The heterologous expression of the recombinant and codon-adapted human GDP-L-fucose antiporter gene SLC35C1 (encoding an N-terminal OmpA-signal sequence) led to a functional transporter protein located in the cytoplasmic membrane of Escherichia coli. The in vitro transport was investigated using inverted membrane vesicles. SLC35C1 is an antiporter specific for GDP-L-fucose and depending on the concomitant reverse transport of GMP. The recombinant transporter FucT1 exhibited an activity for the transport of 3 H-GDP-L-fucose with a V max of 8 pmol/min mg with a K m of 4 µM. The functional expression of SLC35C1 in GDP-L-fucose overproducing E. coli led to the export of GDP-L-fucose to the culture supernatant. The export of GDP-L-fucose by E. coli provides the opportunity for the engineering of a periplasmatic fucosylation reaction in recombinant bacterial cells.

Sos - response induction by gamma radiation in Escherichia coli strains with different repair capacities

International Nuclear Information System (INIS)

Serment Guerrero, J.H.

1992-01-01

The Sos - response in Escherichia coli is formed by several genes involved in mechanisms of tolerance and/or repair, and only activates when a DNA - damage appears. It is controlled by recA and lexA genes. In normal circumstances, LexA protein is linked in every Sos operators, blocking the transcription. When a DNA damage occurs, a Sos signal is generated, Rec A protein changes its normal functions, starts acting as a protease and cleaves Lex A, allowing the transcription of all Sos genes. This response can be quantified by means of Sos Chromo test, performed by Quillardet and Ofnung (1985). In using the Chromo test, it has been observed that the DNA damage made by gamma radiation in Escherichia coli depends on both the doses and the doses rate. It has been shown that the exposure of Escherichia coli PQ37 strain (uvrA) to low doses at low dose rate appears to retard the response, suggesting the action of a repair mechanism. (Brena 1990). In this work, we compare the response in Escherichia coli strains deficient in different mechanisms of repair and/or tolerance. It is observed the importance of rec N gene in the repair of DNA damage produced by gamma radiation. (Author)

The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E. coli strains in human urine

DEFF Research Database (Denmark)

Hancock, Viktoria; Ulett, G.C.; Schembri, M.A.

2006-01-01

Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract....... The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory...... to conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human...

A genomically modified Escherichia coli strain carrying an orthogonal E. coli histidyl-tRNA synthetase•tRNAHis pair.

Science.gov (United States)

Englert, Markus; Vargas-Rodriguez, Oscar; Reynolds, Noah M; Wang, Yane-Shih; Söll, Dieter; Umehara, Takuya

2017-11-01

Development of new aminoacyl-tRNA synthetase (aaRS)•tRNA pairs is central for incorporation of novel non-canonical amino acids (ncAAs) into proteins via genetic code expansion (GCE). The Escherichia coli and Caulobacter crescentus histidyl-tRNA synthetases (HisRS) evolved divergent mechanisms of tRNA His recognition that prevent their cross-reactivity. Although the E. coli HisRS•tRNA His pair is a good candidate for GCE, its use in C. crescentus is limited by the lack of established genetic selection methods and by the low transformation efficiency of C. crescentus. E. coli was genetically engineered to use a C. crescentus HisRS•tRNA His pair. Super-folder green fluorescent protein (sfGFP) and chloramphenicol acetyltransferase (CAT) were used as reporters for read-through assays. A library of 313 ncAAs coupled with the sfGFP reporter system was employed to investigate the specificity of E. coli HisRS in vivo. A genomically modified E. coli strain (named MEOV1) was created. MEVO1 requires an active C. crescentus HisRS•tRNA His pair for growth, and displays a similar doubling time as the parental E. coli strain. sfGFP- and CAT-based assays showed that the E. coli HisRS•tRNA His pair is orthogonal in MEOV1 cells. A mutation in the anticodon loop of E. coli tRNA His CUA elevated its suppression efficiency by 2-fold. The C. crescentus HisRS•tRNA His pair functionally complements an E. coli ΔhisS strain. The E. coli HisRS•tRNA His is orthogonal in MEOV1 cells. E. coli tRNA His CUA is an efficient amber suppressor in MEOV1. We developed a platform that allows protein engineering of E. coli HisRS that should facilitate GCE in E. coli. This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue. Copyright © 2017 Elsevier B.V. All rights reserved.

Secretion of d-alanine by Escherichia coli.

Science.gov (United States)

Katsube, Satoshi; Sato, Kazuki; Ando, Tasuke; Isogai, Emiko; Yoneyama, Hiroshi

2016-07-01

Escherichia coli has an l-alanine export system that protects the cells from toxic accumulation of intracellular l-alanine in the presence of l-alanyl-l-alanine (l-Ala-l-Ala). When a DadA-deficient strain was incubated with 6.0 mM l-Ala-l-Ala, we detected l-alanine and d-alanine using high-performance liquid chromatography (HPLC) analysis at a level of 7.0 mM and 3.0 mM, respectively, after 48 h incubation. Treatment of the culture supernatant with d-amino acid oxidase resulted in the disappearance of a signal corresponding to d-alanine. Additionally, the culture supernatant enabled a d-alanine auxotroph to grow without d-alanine supplementation, confirming that the signal detected by HPLC was authentic d-alanine. Upon introduction of an expression vector harbouring the alanine racemase genes, alr or dadX, the extracellular level of d-alanine increased to 11.5 mM and 8.5 mM, respectively, under similar conditions, suggesting that increased metabolic flow from l-alanine to d-alanine enhanced d-alanine secretion. When high-density DadA-deficient cells preloaded with l-Ala-l-Ala were treated with 20 µM carbonyl cyanide m-chlorophenyl hydrazone (CCCP), secretion of both l-alanine and d-alanine was enhanced ~twofold compared with that in cells without CCCP treatment. In contrast, the ATPase inhibitor dicyclohexylcarbodiimide did not exert such an effect on the l-alanine and d-alanine secretion. Furthermore, inverted membrane vesicles prepared from DadA-deficient cells lacking the l-alanine exporter AlaE accumulated [3H]D-alanine in an energy-dependent manner. This energy-dependent accumulation of [3H]D-alanine was strongly inhibited by CCCP. These results indicate that E. coli has a transport system(s) that exports d-alanine and that this function is most likely modulated by proton electrochemical potential.

Silver nanoparticle-E. coli colloidal interaction in water and effect on E. coli survival.

Science.gov (United States)

Dror-Ehre, A; Mamane, H; Belenkova, T; Markovich, G; Adin, A

2009-11-15

Silver nanoparticles exhibit antibacterial properties via bacterial inactivation and growth inhibition. The mechanism is not yet completely understood. This work was aimed at elucidating the effect of silver nanoparticles on inactivation of Escherichia coli, by studying particle-particle interactions in aqueous suspensions. Stable, molecularly capped, positively or negatively charged silver nanoparticles were mixed at 1 to 60microgmL(-1) with suspended E. coli cells to examine their effect on inactivation of the bacteria. Gold nanoparticles with the same surfactant were used as a control, being of similar size but made up of a presumably inert metal. Log reduction of 5log(10) and complete inactivation were obtained with the silver nanoparticles while the gold nanoparticles did not show any inactivation ability. The effect of molecularly capped nanoparticles on E. coli survival was dependent on particle number. Log reduction of E. coli was associated with the ratio between the number of nanoparticles and the initial bacterial cell count. Electrostatic attraction or repulsion mechanisms in silver nanoparticle-E. coli cell interactions did not contribute to the inactivation process.

Genetic Transfer of Salmonella typhimurium and Escherichia coli Lipopolysaccharide Antigens to Escherichia coli K-12

Science.gov (United States)

Jones, Randall T.; Koeltzow, Donald E.; Stocker, B. A. D.

1972-01-01

Escherichia coli K-12 ϰ971 was crossed with a smooth Salmonella typhimurium donor, HfrK6, which transfers early the ilv-linked rfa region determining lipopolysaccharide (LPS) core structure. Two ilv+ hybrids differing in their response to the LPS-specific phages FO and C21 were then crossed with S. typhimurium HfrK9, which transfers early the rfb gene cluster determining O repeat unit structure. Most recombinants selected for his+ (near rfb) were agglutinated by Salmonella factor 4 antiserum. Transfer of an F′ factor (FS400) carrying the rfb–his region of S. typhimurium to the same two ilv+ hybrids gave similar results. LPS extracted from two ilv+,his+, factor 4-positive hybrids contained abequose, the immunodominant sugar for factor 4 specificity. By contrast, his+ hybrids obtained from ϰ971 itself by similar HfrK9 and F′FS400 crosses were not agglutinated by factor 4 antiserum, indicating that the parental E. coli ϰ971 does not have the capacity to attach Salmonella O repeat units to its LPS core. It is concluded that the Salmonella rfb genes are expressed only in E. coli ϰ971 hybrids which have also acquired ilv-linked genes (presumably rfa genes affecting core structure or O-translocase ability, or both) from a S. typhimurium donor. When E. coli ϰ971 was crossed with a smooth E. coli donor, Hfr59, of serotype O8, which transfers his early, most his+ recombinants were agglutinated by E. coli O8 antiserum and lysed by the O8-specific phage, Ω8. This suggests that, although the parental E. coli K-12 strain ϰ971 cannot attach Salmonella-specific repeat units to its LPS core, it does have the capacity to attach E. coli O8-specific repeat units. PMID:4559827

Comparative genomics and transcriptomics of Escherichia coli isolates carrying virulence factors of both enteropathogenic and enterotoxigenic E. coli.

Science.gov (United States)

Hazen, Tracy H; Michalski, Jane; Luo, Qingwei; Shetty, Amol C; Daugherty, Sean C; Fleckenstein, James M; Rasko, David A

2017-06-14

Escherichia coli that are capable of causing human disease are often classified into pathogenic variants (pathovars) based on their virulence gene content. However, disease-associated hybrid E. coli, containing unique combinations of multiple canonical virulence factors have also been described. Such was the case of the E. coli O104:H4 outbreak in 2011, which caused significant morbidity and mortality. Among the pathovars of diarrheagenic E. coli that cause significant human disease are the enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC). In the current study we use comparative genomics, transcriptomics, and functional studies to characterize isolates that contain virulence factors of both EPEC and ETEC. Based on phylogenomic analysis, these hybrid isolates are more genomically-related to EPEC, but appear to have acquired ETEC virulence genes. Global transcriptional analysis using RNA sequencing, demonstrated that the EPEC and ETEC virulence genes of these hybrid isolates were differentially-expressed under virulence-inducing laboratory conditions, similar to reference isolates. Immunoblot assays further verified that the virulence gene products were produced and that the T3SS effector EspB of EPEC, and heat-labile toxin of ETEC were secreted. These findings document the existence and virulence potential of an E. coli pathovar hybrid that blurs the distinction between E. coli pathovars.

Thioredoxin from Escherichia coli

International Nuclear Information System (INIS)

Holmgren, A.; Ohlsson, I.; Grankvist, M.L.

1978-01-01

A competition radioimmunoassay for Escherichia coli thioredoxin using 125 I-labeled thioredoxin-S 2 and a double antibody technique was developed. The method permits determination of picomole amounts of thioredoxin in crude cell extracts and was used to study the localization of thioredoxin cell fractions. E. coli B was calculated to have approximately 10,000 copies of thioredoxin per cell mainly located in the soluble fraction after separation of the membrane and soluble fractions by gentle lysis and centrifugation. E. coli B tsnC mutants which are defective in the replication of phage T7 DNA in vivo and in vitro were examined for their content of thioredoxin. E. coli B tsnC 7004 contained no detectable level of thioredoxin in cell-free extracts examined under a variety of conditions. The results strongly suggest that tsnC 7004 is a nonsense or deletion mutant. Two other E. coli tsnC mutants, 7007 and 7008, contained detectable levels of thioredoxin in crude extracts as measured by thioredoxin reductase and gave similar immunoprecipitation reactions as the parent strain B/1. By radioimmunoassay incompletely cross-reacting material was present in both strains. These results show that tsnC 7007 and 7008 belong to a type of thioredoxin mutants with missence mutations in the thioredoxin gene affecting the function of thioredoxin as subunit in phage T7 DNA polymerase

Surface display of Salmonella epitopes in Escherichia coli and Staphylococcus carnosus.

Science.gov (United States)

Nhan, Nguyen Thanh; Gonzalez de Valdivia, Ernesto; Gustavsson, Martin; Hai, Truong Nam; Larsson, Gen

2011-04-11

Salmonella enterica serotype Enteritidis (SE) is considered to be one of the most potent pathogenic Salmonella serotypes causing food-borne disease in humans. Since a live bacterial vaccine based on surface display of antigens has many advantages over traditional vaccines, we have studied the surface display of the SE antigenic proteins, H:gm and SefA in Escherichia coli by the β-autotransporter system, AIDA. This procedure was compared to protein translocation in Staphylococcus carnosus, using a staphylococci hybrid vector earlier developed for surface display of other vaccine epitopes. Both SefA and H:gm were translocated to the outer membrane in Escherichia coli. SefA was expressed to full length but H:gm was shorter than expected, probably due to a proteolytic cleavage of the N-terminal during passage either through the periplasm or over the membrane. FACS analysis confirmed that SefA was facing the extracellular environment, but this could not be conclusively established for H:gm since the N-terminal detection tag (His6) was cleaved off. Polyclonal salmonella antibodies confirmed the sustained antibody-antigen binding towards both proteins. The surface expression data from Staphylococcus carnosus suggested that the H:gm and SefA proteins were transported to the cell wall since the detection marker was displayed by FACS analysis. Apart from the accumulated knowledge and the existence of a wealth of equipment and techniques, the results indicate the selection of E. coli for further studies for surface expression of salmonella antigens. Surface expression of the full length protein facing the cell environment was positively proven by standard analysis, and the FACS signal comparison to expression in Staphylococcus carnosus shows that the distribution of the surface protein on each cell was comparatively very narrow in E. coli, the E. coli outer membrane molecules can serve as an adjuvant for the surface antigenic proteins and multimeric forms of the SefA protein

Structures of the E. coli translating ribosome with SRP and its receptor and with the translocon.

Science.gov (United States)

Jomaa, Ahmad; Boehringer, Daniel; Leibundgut, Marc; Ban, Nenad

2016-01-25

Co-translational protein targeting to membranes is a universally conserved process. Central steps include cargo recognition by the signal recognition particle and handover to the Sec translocon. Here we present snapshots of key co-translational-targeting complexes solved by cryo-electron microscopy at near-atomic resolution, establishing the molecular contacts between the Escherichia coli translating ribosome, the signal recognition particle and the translocon. Our results reveal the conformational changes that regulate the latching of the signal sequence, the release of the heterodimeric domains of the signal recognition particle and its receptor, and the handover of the signal sequence to the translocon. We also observe that the signal recognition particle and the translocon insert-specific structural elements into the ribosomal tunnel to remodel it, possibly to sense nascent chains. Our work provides structural evidence for a conformational state of the signal recognition particle and its receptor primed for translocon binding to the ribosome-nascent chain complex.

Cloning, purification, crystallization and preliminary crystallographic analysis of LsrR from Escherichia coli

International Nuclear Information System (INIS)

Liu, Xiaotian; Wu, Minhao; Sun, Demeng; Zang, Jianye

2010-01-01

The E. coli transcription repressor LsrR has been overexpressed, purified and crystallized. Diffraction data were collected to about 3 Å resolution. In Escherichia coli, the lsr operon is composed of six genes lsrACDBFG which regulate uptake and modification of the signalling molecule AI-2. LsrR is a repressor of the lsr operon and itself, which can bind phospho-AI-2 and be released from the promoter region of the operon and thus activate gene expression. LsrR fused with an HHHHHH sequence at the C-terminus was expressed, purified and crystallized in order to determine its structure and elucidate the molecular mechanism of repression. The crystal belonged to space group I222, with unit-cell parameters a = 79.84, b = 116.65, c = 186.04 Å, and was estimated to contain two protein molecules per asymmetric unit

Exponential signaling gain at the receptor level enhances signal-to-noise ratio in bacterial chemotaxis.

Directory of Open Access Journals (Sweden)

Silke Neumann

Full Text Available Cellular signaling systems show astonishing precision in their response to external stimuli despite strong fluctuations in the molecular components that determine pathway activity. To control the effects of noise on signaling most efficiently, living cells employ compensatory mechanisms that reach from simple negative feedback loops to robustly designed signaling architectures. Here, we report on a novel control mechanism that allows living cells to keep precision in their signaling characteristics - stationary pathway output, response amplitude, and relaxation time - in the presence of strong intracellular perturbations. The concept relies on the surprising fact that for systems showing perfect adaptation an exponential signal amplification at the receptor level suffices to eliminate slowly varying multiplicative noise. To show this mechanism at work in living systems, we quantified the response dynamics of the E. coli chemotaxis network after genetically perturbing the information flux between upstream and downstream signaling components. We give strong evidence that this signaling system results in dynamic invariance of the activated response regulator against multiplicative intracellular noise. We further demonstrate that for environmental conditions, for which precision in chemosensing is crucial, the invariant response behavior results in highest chemotactic efficiency. Our results resolve several puzzling features of the chemotaxis pathway that are widely conserved across prokaryotes but so far could not be attributed any functional role.

Comparative genomics of Geobacter chemotaxis genes reveals diverse signaling function

Directory of Open Access Journals (Sweden)

Antommattei Frances M

2008-10-01

Full Text Available Abstract Background Geobacter species are δ-Proteobacteria and are often the predominant species in a variety of sedimentary environments where Fe(III reduction is important. Their ability to remediate contaminated environments and produce electricity makes them attractive for further study. Cell motility, biofilm formation, and type IV pili all appear important for the growth of Geobacter in changing environments and for electricity production. Recent studies in other bacteria have demonstrated that signaling pathways homologous to the paradigm established for Escherichia coli chemotaxis can regulate type IV pili-dependent motility, the synthesis of flagella and type IV pili, the production of extracellular matrix material, and biofilm formation. The classification of these pathways by comparative genomics improves the ability to understand how Geobacter thrives in natural environments and better their use in microbial fuel cells. Results The genomes of G. sulfurreducens, G. metallireducens, and G. uraniireducens contain multiple (~70 homologs of chemotaxis genes arranged in several major clusters (six, seven, and seven, respectively. Unlike the single gene cluster of E. coli, the Geobacter clusters are not all located near the flagellar genes. The probable functions of some Geobacter clusters are assignable by homology to known pathways; others appear to be unique to the Geobacter sp. and contain genes of unknown function. We identified large numbers of methyl-accepting chemotaxis protein (MCP homologs that have diverse sensing domain architectures and generate a potential for sensing a great variety of environmental signals. We discuss mechanisms for class-specific segregation of the MCPs in the cell membrane, which serve to maintain pathway specificity and diminish crosstalk. Finally, the regulation of gene expression in Geobacter differs from E. coli. The sequences of predicted promoter elements suggest that the alternative sigma factors �

An Effect of Cadmium and Lead Ions on Escherichia coli with the Cloned Gene for Metallothionein (MT-3) Revealed by Electrochemistry

International Nuclear Information System (INIS)

Adam, Vojtech; Chudobova, Dagmar; Tmejova, Katerina; Cihalova, Kristyna; Krizkova, Sona; Guran, Roman; Kominkova, Marketa; Zurek, Michal; Kremplova, Monika; Jimenez, Ana Maria Jimenez; Konecna, Marie

2014-01-01

This study was focused on the application of electrochemical methods for studying of bacterial strains Escherichia coli and Escherichia coli expressing human metallothionein gene (MT-3) before and after the application of cadmium and/or lead ions in four concentrations (25, 50, 75 and 150 μM). Bacterial strains Escherichia coli and Escherichia coli expressing human metallothionein gene (MT-3) were used like model organisms for studying of metals influence to metallothionein expression. Metallothionein was isolated using fast protein liquid chromatography and quantified by electrochemical methods. The occurrence of metallothionein in E.coli was confirmed by gel electrophoresis by the presence of the bands at 15 (MT dimer) and 22 kDa (MT trimer). The changes in electrochemical records due to the interactions of metallothioneins (MT-3 and MT-2A) with cadmium and lead ions showed decline of Cat2 signal of MT with the increasing interaction time because of metal ions binding to cysteines. Electrochemical determination also revealed that Cd(II) remains in E. coli cells in the higher amount than Pb (II). Opposite situation was found at E. coli–MT-3 strain. The antimicrobial effect of cadmium ions was determined by IC 50 and was statistically calculated as 39.2 and 95.5 μM for E. coli without cloned MT-3 and E. coli carrying MT-3 gene, respectively. High provided concentration IC 50 in strains after lead ions application (352.5 μM for E. coli without cloning and 207.0 μM for E. coli carrying cloned MT-3 gene) indicates lower toxicity of lead ions on bacterial strains compared to the cadmium ions

Electrochemical immunosensor assay (EIA) for sensitive detection of E. coli O157:H7 with signal amplification on a SG-PEDOT-AuNPs electrode interface.

Science.gov (United States)

Guo, Yuna; Wang, Yu; Liu, Su; Yu, Jinghua; Wang, Hongzhi; Cui, Min; Huang, Jiadong

2015-01-21

A novel electrochemical immunosensor assay (EIA) for highly sensitive and specific detection of Escherichia coli O157:H7 has been developed. This immunosensor is constructed by the assembly of capture antibody on SG-PEDOT-AuNPs composites modified glass carbon electrode. In the presence of target E. coli O157:H7, horseradish peroxidase (HRP)-labeled antibody is captured on the electrode surface to form a sandwich-type system via the specific identification. As a result, E. coli O157:H7 detection is realized by outputting a redox current from electro-reduction of hydrogen peroxide reaction catalyzed by HRP. In our assay, the combination of the unique properties of sulfonated graphene (SG) and gold nanoparticles (AuNPs) can not only accelerate electron transfer on electrode interface, but also provide an excellent scaffold for the conjugation of capture antibody that significantly improves the target capture efficiency and enhances the sensitivity of the biosensor. The results reveal the calibration plot obtained for E. coli O157:H7 is approximately linear from 7.8 × 10-7.8 × 10(6) colony-forming unit (cfu) mL(-1) with the limit of detection of 3.4 × 10 cfu mL(-1). In addition, the biosensor has been successfully applied to the quantitative assay of E. coli O157:H7 in synthetic samples (spring water and milk). Hence, the developed electrochemical-based immunosensor might provide a useful and practical tool for E. coli O157:H7 determination and related food safety analysis and clinical diagnosis.

Solid-state voltammetry-based electrochemical immunosensor for Escherichia coli using graphene oxide-Ag nanoparticle composites as labels.

Science.gov (United States)

Jiang, Xiaochun; Chen, Kun; Wang, Jing; Shao, Kang; Fu, Tao; Shao, Feng; Lu, Donglian; Liang, Jiangong; Foda, M Frahat; Han, Heyou

2013-06-21

A new electrochemical immunosensor based on solid-state voltammetry was fabricated for the detection of Escherichia coli (E. coli) by using graphene oxide-Ag nanoparticle composites (P-GO-Ag) as labels. To construct the platform, Au nanoparticles (AuNPs) were first self-assembled on an Au electrode surface through cysteamine and served as an effective matrix for antibody (Ab) attachment. Under a sandwich-type immunoassay format, the analyte and the probe (P-GO-Ag-Ab) were successively captured onto the immunosensor. Finally, the bonded AgNPs were detected through a solid-state redox process in 0.2 M of KCl solution. Combining the advantages of the high-loading capability of graphene oxide with promoted electron-transfer rate of AuNPs, this immunosensor produced a 26.92-fold signal enhancement compared with the unamplified protocol. Under the optimal conditions, the immunosensor exhibited a wide linear dependence on the logarithm of the concentration of E. coli ranging from 50 to 1.0 × 10(6) cfu mL(-1) with a detection limit of 10 cfu mL(-1). Moreover, as a practical application, the proposed immunosensor was used to monitor E. coli in lake water with satisfactory results.

Hemolytic Porcine Intestinal Escherichia coli without Virulence-Associated Genes Typical of Intestinal Pathogenic E. coli ▿ †

Science.gov (United States)

Schierack, Peter; Weinreich, Joerg; Ewers, Christa; Tachu, Babila; Nicholson, Bryon; Barth, Stefanie

2011-01-01

Testing 1,666 fecal or intestinal samples from healthy and diarrheic pigs, we obtained hemolytic Escherichia coli isolates from 593 samples. Focusing on hemolytic E. coli isolates without virulence-associated genes (VAGs) typical for enteropathogens, we found that such isolates carried a broad variety of VAGs typical for extraintestinal pathogenic E. coli. PMID:21965399

ESBL-Producing Escherichia coli

DEFF Research Database (Denmark)

Hertz, Frederik Boetius

Urinary tract infection (UTI) is one the most common bacterial infections and is regularly treated in primary health care. The most common cause of UTI is extraintestinal pathogenic Escherichia coli (ExPEC) already present in the intestinal microflora, often as the dominating strain. Resistance...... in E.coli is increasing and especially isolates producing Extended-Spectrum Beta-Lactamases (ESBL) have been reported worldwide. Treatment of UTI is usually initiated by the general practitioners and a significant proportion of clinical isolates are now resistant to first line antibiotics. The global...... to investigate (i) antibiotics involved in selection of ESBL-producing E.coli, in an experimental mouse model in vivo, (ii) risk factors for UTI with ESBL-producing E.coli and (iii) to describe the phylogenetic composition of E.coli populations with different resistance patterns. We found that different...

Signal conditioning and processing for metallic Hall sensors.

Czech Academy of Sciences Publication Activity Database

Entler, Slavomír; Ďuran, Ivan; Sládek, P.; Vayakis, G.; Kočan, M.

2017-01-01

Roč. 123, November (2017), s. 783-786 ISSN 0920-3796. [SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016] R&D Projects: GA MŠk LG14002 Institutional support: RVO:61389021 Keywords : Hall sensor * Lock-in * Synchronous detection * Current spinning * Hall effect * Planar hall effect suppression Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.319, year: 2016 http://www.sciencedirect.com/science/article/pii/S0920379617305070

21 CFR 866.3255 - Escherichia coli serological reagents.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Escherichia coli serological reagents. 866.3255... coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices that consist of antigens and antisera used in serological tests to identify Escherichia coli from cultured...

Phosphotyrosine-Mediated Regulation of Enterohemorrhagic Escherichia coli Virulence

Science.gov (United States)

Robertson, Colin D.; Hazen, Tracy H.; Kaper, James B.

2018-01-01

ABSTRACT Enteric pathogens with low infectious doses rely on the ability to orchestrate the expression of virulence and metabolism-associated genes in response to environmental cues for successful infection. Accordingly, the human pathogen enterohemorrhagic Escherichia coli (EHEC) employs a complex multifaceted regulatory network to link the expression of type III secretion system (T3SS) components to nutrient availability. While phosphorylation of histidine and aspartate residues on two-component system response regulators is recognized as an integral part of bacterial signaling, the involvement of phosphotyrosine-mediated control is minimally explored in Gram-negative pathogens. Our recent phosphotyrosine profiling study of E. coli identified 342 phosphorylated proteins, indicating that phosphotyrosine modifications in bacteria are more prevalent than previously anticipated. The present study demonstrates that tyrosine phosphorylation of a metabolite-responsive LacI/GalR family regulator, Cra, negatively affects T3SS expression under glycolytic conditions that are typical for the colonic lumen environment where production of the T3SS is unnecessary. Our data suggest that Cra phosphorylation affects T3SS expression by modulating the expression of ler, which encodes the major activator of EHEC virulence gene expression. Phosphorylation of the Cra Y47 residue diminishes DNA binding to fine-tune the expression of virulence-associated genes, including those of the locus of enterocyte effacement pathogenicity island that encode the T3SS, and thereby negatively affects the formation of attaching and effacing lesions. Our data indicate that tyrosine phosphorylation provides an additional mechanism to control the DNA binding of Cra and other LacI/GalR family regulators, including LacI and PurR. This study describes an initial effort to unravel the role of global phosphotyrosine signaling in the control of EHEC virulence potential. PMID:29487233

Phosphotyrosine-Mediated Regulation of Enterohemorrhagic Escherichia coli Virulence

Directory of Open Access Journals (Sweden)

Colin D. Robertson

2018-02-01

Full Text Available Enteric pathogens with low infectious doses rely on the ability to orchestrate the expression of virulence and metabolism-associated genes in response to environmental cues for successful infection. Accordingly, the human pathogen enterohemorrhagic Escherichia coli (EHEC employs a complex multifaceted regulatory network to link the expression of type III secretion system (T3SS components to nutrient availability. While phosphorylation of histidine and aspartate residues on two-component system response regulators is recognized as an integral part of bacterial signaling, the involvement of phosphotyrosine-mediated control is minimally explored in Gram-negative pathogens. Our recent phosphotyrosine profiling study of E. coli identified 342 phosphorylated proteins, indicating that phosphotyrosine modifications in bacteria are more prevalent than previously anticipated. The present study demonstrates that tyrosine phosphorylation of a metabolite-responsive LacI/GalR family regulator, Cra, negatively affects T3SS expression under glycolytic conditions that are typical for the colonic lumen environment where production of the T3SS is unnecessary. Our data suggest that Cra phosphorylation affects T3SS expression by modulating the expression of ler, which encodes the major activator of EHEC virulence gene expression. Phosphorylation of the Cra Y47 residue diminishes DNA binding to fine-tune the expression of virulence-associated genes, including those of the locus of enterocyte effacement pathogenicity island that encode the T3SS, and thereby negatively affects the formation of attaching and effacing lesions. Our data indicate that tyrosine phosphorylation provides an additional mechanism to control the DNA binding of Cra and other LacI/GalR family regulators, including LacI and PurR. This study describes an initial effort to unravel the role of global phosphotyrosine signaling in the control of EHEC virulence potential.

Asymptomatic bacteriuria Escherichia coli strains

DEFF Research Database (Denmark)

Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

2006-01-01

Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...... to uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...

Transphosphorylation of E. coli proteins during production of recombinant protein kinases provides a robust system to characterize kinase specificity

Science.gov (United States)

Protein kinase specificity is of fundamental importance to pathway regulation and signal transduction. Here, we report a convenient system to monitor the activity and specificity of recombinant protein kinases expressed in E.coli. We apply this to the study of the cytoplasmic domain of the plant rec...

Escherichia coli EDL933 Requires Gluconeogenic Nutrients To Successfully Colonize the Intestines of Streptomycin-Treated Mice Precolonized with E. coli Nissle 1917

Science.gov (United States)

Schinner, Silvia A. C.; Mokszycki, Matthew E.; Adediran, Jimmy; Leatham-Jensen, Mary; Conway, Tyrrell

2015-01-01

Escherichia coli MG1655, a K-12 strain, uses glycolytic nutrients exclusively to colonize the intestines of streptomycin-treated mice when it is the only E. coli strain present or when it is confronted with E. coli EDL933, an O157:H7 strain. In contrast, E. coli EDL933 uses glycolytic nutrients exclusively when it is the only E. coli strain in the intestine but switches in part to gluconeogenic nutrients when it colonizes mice precolonized with E. coli MG1655 (R. L. Miranda et al., Infect Immun 72:1666–1676, 2004, http://dx.doi.org/10.1128/IAI.72.3.1666-1676.2004). Recently, J. W. Njoroge et al. (mBio 3:e00280-12, 2012, http://dx.doi.org/10.1128/mBio.00280-12) reported that E. coli 86-24, an O157:H7 strain, activates the expression of virulence genes under gluconeogenic conditions, suggesting that colonization of the intestine with a probiotic E. coli strain that outcompetes O157:H7 strains for gluconeogenic nutrients could render them nonpathogenic. Here we report that E. coli Nissle 1917, a probiotic strain, uses both glycolytic and gluconeogenic nutrients to colonize the mouse intestine between 1 and 5 days postfeeding, appears to stop using gluconeogenic nutrients thereafter in a large, long-term colonization niche, but continues to use them in a smaller niche to compete with invading E. coli EDL933. Evidence is also presented suggesting that invading E. coli EDL933 uses both glycolytic and gluconeogenic nutrients and needs the ability to perform gluconeogenesis in order to colonize mice precolonized with E. coli Nissle 1917. The data presented here therefore rule out the possibility that E. coli Nissle 1917 can starve the O157:H7 E. coli strain EDL933 of gluconeogenic nutrients, even though E. coli Nissle 1917 uses such nutrients to compete with E. coli EDL933 in the mouse intestine. PMID:25733524

Chemotactic response and adaptation dynamics in Escherichia coli.

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Diana Clausznitzer

2010-05-01

Full Text Available Adaptation of the chemotaxis sensory pathway of the bacterium Escherichia coli is integral for detecting chemicals over a wide range of background concentrations, ultimately allowing cells to swim towards sources of attractant and away from repellents. Its biochemical mechanism based on methylation and demethylation of chemoreceptors has long been known. Despite the importance of adaptation for cell memory and behavior, the dynamics of adaptation are difficult to reconcile with current models of precise adaptation. Here, we follow time courses of signaling in response to concentration step changes of attractant using in vivo fluorescence resonance energy transfer measurements. Specifically, we use a condensed representation of adaptation time courses for efficient evaluation of different adaptation models. To quantitatively explain the data, we finally develop a dynamic model for signaling and adaptation based on the attractant flow in the experiment, signaling by cooperative receptor complexes, and multiple layers of feedback regulation for adaptation. We experimentally confirm the predicted effects of changing the enzyme-expression level and bypassing the negative feedback for demethylation. Our data analysis suggests significant imprecision in adaptation for large additions. Furthermore, our model predicts highly regulated, ultrafast adaptation in response to removal of attractant, which may be useful for fast reorientation of the cell and noise reduction in adaptation.

Solar signals detected within neutral atmospheric and ionospheric parameters

Czech Academy of Sciences Publication Activity Database

Koucká Knížová, Petra; Georgieva, K.; Mošna, Zbyšek; Kozubek, Michal; Kouba, Daniel; Kirov, B.; Potužníková, Kateřina; Boška, Josef

2018-01-01

Roč. 171, June (2018), s. 147-156 ISSN 1364-6826 R&D Projects: GA ČR(CZ) GA15-24688S Grant - others:AV ČR(CZ) BAS-17-06 Program:Bilaterální spolupráce Institutional support: RVO:68378289 Keywords : solar energy * upper atmosphere Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 1.326, year: 2016 http://www.sciencedirect.com/science/article/pii/S1364682617302365

Genes encoding two lipoproteins in the leuS-dacA region of the Escherichia coli chromosome

International Nuclear Information System (INIS)

Takase, I.; Ishino, F.; Wachi, M.; Kamata, H.; Doi, M.; Asoh, S.; Matsuzawa, H.; Ohta, T.; Matsuhashi, M.

1987-01-01

The coding of two rare lipoproteins by two genes, rlpA and rlpB, located in the leuS-dacA region (15 min) on the Escherichia coli chromosome was demonstrated by expression of subcloned genes in a maxicell system. The formation of these two proteins was inhibited by globomycin, which is an inhibitor of the signal peptidase for the known lipoproteins of E. coli. In each case, this inhibition was accompanied by formation of a new protein, which showed a slightly lower mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and which we suppose to be a prolipoprotein with an N-terminal signal peptide sequence similar to those of the bacterial major lipoproteins and lysis proteins of some bacteriocins. The incorporation of 3 H-labeled palmitate and glycerol into the two lipoproteins was also observed. Sequencing of DNA showed that the two lipoprotein genes contained sequences that could code for signal peptide sequences of 17 amino acids (rlpA lipoprotein) and 18 amino acids (rlpB lipoprotein). The deduced sequences of the mature peptides consisted of 345 amino acids (M/sub r/ 35,615, rlpA lipoprotein) and 175 amino acids (M/sub r/ 19,445, rlpB lipoprotein), with an N-terminal cysteine to which thioglyceride and N-fatty acyl residues may be attached. These two lioproteins may be important in duplication of the cells

Structure of putative CutA1 from Homo sapiens determined at 2.05 Å resolution

Energy Technology Data Exchange (ETDEWEB)

Bagautdinov, Bagautdin, E-mail: bagautdi@spring8.or.jp; Matsuura, Yoshinori; Bagautdinova, Svetlana; Kunishima, Naoki; Yutani, Katsuhide [Protein Structure Analysis Team, RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2008-05-01

The X-ray structure of human CutA1 was solved in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 68.69, b = 88.84, c = 125.33 Å and six molecules per asymmetric unit. The structure of human brain CutA1 (HsCutA1) has been determined using diffraction data to 2.05 Å resolution. HsCutA1 has been implicated in the anchoring of acetylcholinesterase in neuronal cell membranes, while its bacterial homologue Escherichia coli CutA1 is involved in copper tolerance. Additionally, the structure of HsCutA1 bears similarity to that of the signal transduction protein PII, which is involved in regulation of nitrogen metabolism. Although several crystal structures of CutA1 from various sources with different rotation angles and degrees of interaction between trimer interfaces have been reported, the specific functional role of CutA1 is still unclear. In this study, the X-ray structure of HsCutA1 was determined in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 68.69, b = 88.84, c = 125.33 Å and six molecules per asymmetric unit. HsCutA1 is a trimeric molecule with intertwined antiparallel β-strands; each subunit has a molecular weight of 14.6 kDa and contains 135 amino-acid residues. In order to obtain clues to the possible function of HsCutA1, its crystal structure was compared with those of other CutA1 and PII proteins.

Oxygen-Dependent Cell-to-Cell Variability in the Output of the Escherichia coli Tor Phosphorelay.

Science.gov (United States)

Roggiani, Manuela; Goulian, Mark

2015-06-15

Escherichia coli senses and responds to trimethylamine-N-oxide (TMAO) in the environment through the TorT-TorS-TorR signal transduction system. The periplasmic protein TorT binds TMAO and stimulates the hybrid kinase TorS to phosphorylate the response regulator TorR through a phosphorelay. Phosphorylated TorR, in turn, activates transcription of the torCAD operon, which encodes the proteins required for anaerobic respiration via reduction of TMAO to trimethylamine. Interestingly, E. coli respires TMAO in both the presence and absence of oxygen, a behavior that is markedly different from the utilization of other alternative electron acceptors by this bacterium. Here we describe an unusual form of regulation by oxygen for this system. While the average level of torCAD transcription is the same for aerobic and anaerobic cultures containing TMAO, the behavior across the population of cells is strikingly different under the two growth conditions. Cellular levels of torCAD transcription in aerobic cultures are highly heterogeneous, in contrast to the relatively homogeneous distribution in anaerobic cultures. Thus, oxygen regulates the variance of the output but not the mean for the Tor system. We further show that this oxygen-dependent variability stems from the phosphorelay. Trimethylamine-N-oxide (TMAO) is utilized by numerous bacteria as an electron acceptor for anaerobic respiration. In E. coli, expression of the proteins required for TMAO respiration is tightly regulated by a signal transduction system that is activated by TMAO. Curiously, although oxygen is the energetically preferred electron acceptor, TMAO is respired even in the presence of oxygen. Here we describe an interesting and unexpected form of regulation for this system in which oxygen produces highly variable expression of the TMAO utilization proteins across a population of cells without affecting the mean expression of these proteins. To our knowledge, this is the first reported example of a stimulus

Multiplex PCR Assay for Identification of Human Diarrheagenic Escherichia coli

OpenAIRE

Toma, Claudia; Lu, Yan; Higa, Naomi; Nakasone, Noboru; Chinen, Isabel; Baschkier, Ariela; Rivas, Marta; Iwanaga, Masaaki

2003-01-01

A multiplex PCR assay for the identification of human diarrheagenic Escherichia coli was developed. The targets selected for each category were eae for enteropathogenic E. coli, stx for Shiga toxin-producing E. coli, elt and est for enterotoxigenic E. coli, ipaH for enteroinvasive E. coli, and aggR for enteroaggregative E. coli. This assay allowed the categorization of a diarrheagenic E. coli strain in a single reaction tube.

Bacillus subtilis Intramembrane Protease RasP Activity in Escherichia coli and In Vitro.

Science.gov (United States)

Parrell, Daniel; Zhang, Yang; Olenic, Sandra; Kroos, Lee

2017-10-01

RasP is a predicted intramembrane metalloprotease of Bacillus subtilis that has been proposed to cleave the stress response anti-sigma factors RsiW and RsiV, the cell division protein FtsL, and remnant signal peptides within their transmembrane segments. To provide evidence for direct effects of RasP on putative substrates, we developed a heterologous coexpression system. Since expression of catalytically inactive RasP E21A inhibited expression of other membrane proteins in Escherichia coli , we added extra transmembrane segments to RasP E21A, which allowed accumulation of most other membrane proteins. A corresponding active version of RasP appeared to promiscuously cleave coexpressed membrane proteins, except those with a large periplasmic domain. However, stable cleavage products were not observed, even in clpP mutant E. coli Fusions of transmembrane segment-containing parts of FtsL and RsiW to E. coli maltose-binding protein (MBP) also resulted in proteins that appeared to be RasP substrates upon coexpression in E. coli , including FtsL with a full-length C-terminal domain (suggesting that prior cleavage by a site 1 protease is unnecessary) and RsiW designed to mimic the PrsW site 1 cleavage product (suggesting that further trimming by extracytoplasmic protease is unnecessary). Purified RasP cleaved His 6 -MBP-RsiW(73-118) in vitro within the RsiW transmembrane segment based on mass spectrometry analysis, demonstrating that RasP is an intramembrane protease. Surprisingly, purified RasP failed to cleave His 6 -MBP-FtsL(23-117). We propose that the lack of α-helix-breaking residues in the FtsL transmembrane segment creates a requirement for the membrane environment and/or an additional protein(s) in order for RasP to cleave FtsL. IMPORTANCE Intramembrane proteases govern important signaling pathways in nearly all organisms. In bacteria, they function in stress responses, cell division, pathogenesis, and other processes. Their membrane-associated substrates are

Characterization of diarrhoeagenic Escherichia coli isolates in Jordanian children.

Science.gov (United States)

Shehabi, Asem A; Bulos, Najawa-Kuri; Hajjaj, Kamal G

2003-01-01

In a prospective study carried out among Jordanian children in Amman, a total of 73/250 (29.2%) stool specimens were positive for 1 or more diarrhoeagenic Escherichia coli strains using a multiplex polymerase chain reaction method. This study indicated that diarrhoeagenic E. coli isolates were found frequently more in stools of children with diarrhoea (34%) than without diarrhoea (23.1%), but without any significant difference (p > 0.05). The predominant diarrhoeagenic E. coli strains associated with diarrhoea were enteropathogenic E. coli (11.3%), followed by enterotoxigenic E. coli (9.8%) and enteroaggrative E. coli (9%), whereas in the control group these were 4.3%, 11.1% and 6%, respectively. Enteroinvasive E. coli strains (2.9%) were found only in stools of children with diarrhoea. This study revealed the absence of enterohaemorrhagic E. coli in both diarrhoeal and control stools, and found that diarrhoeagenic E. coli isolates were highly resistance to tetracycline (55%), co-trimoxazole (60%) and ampicillin (89%), which are commonly used antibiotics in Jordan.

Functional participation of a nifH-arsA2 chimeric fusion gene in arsenic reduction by Escherichia coli

International Nuclear Information System (INIS)

Lahiri, Surobhi; Pulakat, Lakshmi; Gavini, Nara

2008-01-01

The NifH (dimer) and ArsA proteins are structural homologs and share common motifs like nucleotide-binding domains, signal transduction domains and also possible similar metal center ligands. Given the similarity between two proteins, we investigated if the NifH protein from Azotobacter vinelandii could functionally substitute for the ArsA1 half of the ArsA protein of Escherichia coli. The chimeric NifH-ArsA2 protein was expressed and detected in the E. coli strain by Western blotting. Growth comparisons of E. coli strains containing plasmids encoding for complete ArsA, partial ArsA (ArsA2) or chimeric ArsA (NifH-ArsA2) in media with increasing sodium arsenite concentrations (0-5 mM) showed that the chimeric NifH-ArsA2 could substitute for the ArsA. This functional complementation demonstrated the strong conservation of essential domains that have been maintained in NifH and ArsA even after their divergence to perform varied functions

Beam diagnostics

International Nuclear Information System (INIS)

Bogaty, J.; Clifft, B.E.; Zinkann, G.P.; Pardo, R.C.

1995-01-01

The ECR-PII injector beam line is operated at a fixed ion velocity. The platform high voltage is chosen so that all ions have a velocity of 0.0085c at the PII entrance. If a previous tune configuration for the linac is to be used, the beam arrival time must be matched to the previous tune as well. A nondestructive beam-phase pickup detector was developed and installed at the entrance to the PII linac. This device provides continuous phase and beam current information and allows quick optimization of the beam injected into PII. Bunches traverse a short tubular electrode thereby inducing displacement currents. These currents are brought outside the vacuum interface where a lumped inductance resonates electrode capacitance at one of the bunching harmonic frequencies. This configuration yields a basic sensitivity of a few hundred millivolts signal per microampere of beam current. Beam-induced radiofrequency signals are summed against an offset frequency generated by our master oscillator. The resulting kilohertz difference frequency conveys beam intensity and bunch phase information which is sent to separate processing channels. One channel utilizes a phase locked loop which stabilizes phase readings if beam is unstable. The other channel uses a linear full wave active rectifier circuit which converts kilohertz sine wave signal amplitude to a D.C. voltage representing beam current. A prototype set of electronics is now in use with the detector and we began to use the system in operation to set the arrival beam phase. A permanent version of the electronics system for the phase detector is now under construction. Additional nondestructive beam intensity and phase monitors at the open-quotes Boosterclose quotes and open-quotes ATLASclose quotes linac sections are planned as well as on some of the high-energy beam lines. Such a monitor will be particularly useful for FMA experiments where the primary beam hits one of the electric deflector plates

Current pathogenic Escherichia coli foodborne outbreak cases and therapy development.

Science.gov (United States)

Yang, Shih-Chun; Lin, Chih-Hung; Aljuffali, Ibrahim A; Fang, Jia-You

2017-08-01

Food contamination by pathogenic microorganisms has been a serious public health problem and a cause of huge economic losses worldwide. Foodborne pathogenic Escherichia coli (E. coli) contamination, such as that with E. coli O157 and O104, is very common, even in developed countries. Bacterial contamination may occur during any of the steps in the farm-to-table continuum from environmental, animal, or human sources and cause foodborne illness. To understand the causes of the foodborne outbreaks by E. coli and food-contamination prevention measures, we collected and investigated the past 10 years' worldwide reports of foodborne E. coli contamination cases. In the first half of this review article, we introduce the infection and symptoms of five major foodborne diarrheagenic E. coli pathotypes: enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli/enterohemorrhagic E. coli (STEC/EHEC), Shigella/enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), and enterotoxigenic E. coli (ETEC). In the second half of this review article, we introduce the foodborne outbreak cases caused by E. coli in natural foods and food products. Finally, we discuss current developments that can be applied to control and prevent bacterial food contamination.

Development and characterization of a magnetic bead-quantum dot nanoparticles based assay capable of Escherichia coli O157:H7 quantification

Energy Technology Data Exchange (ETDEWEB)

Kim, Gha-Young [Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Son, Ahjeong, E-mail: ason@auburn.edu [Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States)

2010-09-10

The development and characterization of a magnetic bead (MB)-quantum dot (QD) nanoparticles based assay capable of quantifying pathogenic bacteria is presented here. The MB-QD assay operates by having a capturing probe DNA selectively linked to the signaling probe DNA via the target genomic DNA (gDNA) during DNA hybridization. The signaling probe DNA is labeled with fluorescent QD{sub 565} which serves as a reporter. The capturing probe DNA is conjugated simultaneously to a MB and another QD{sub 655}, which serve as a carrier and an internal standard, respectively. Successfully captured target gDNA is separated using a magnetic field and is quantified via a spectrofluorometer. The use of QDs (i.e., QD{sub 565}/QD{sub 655}) as both a fluorescence label and an internal standard increased the sensitivity of the assay. The passivation effect and the molar ratio between QD and DNA were optimized. The MB-QD assay demonstrated a detection limit of 890 zeptomolar (i.e., 10{sup -21} mol L{sup -1}) concentration for the linear single stranded DNA (ssDNA). It also demonstrated a detection limit of 87 gene copies for double stranded DNA (dsDNA) eaeA gene extracted from pure Escherichia coli (E. coli) O157:H7 culture. Its corresponding dynamic range, sensitivity, and selectivity were also presented. Finally, the bacterial gDNA of E. coli O157:H7 was used to highlight the MB-QD assay's ability to detect below the minimum infective dose (i.e., 100 organisms) of E. coli O157:H7 in water environment.

Experimental induced avian E. coli salpingitis

DEFF Research Database (Denmark)

Olsen, Rikke Heidemann; Thøfner, Ida; Pors, Susanne Elisabeth

2016-01-01

Several types of Escherichia coli have been associated with extra-intestinal infections in poultry, however, they may vary significantly in their virulence potential. The aim of the present study was to investigate the virulence of five strains of E. coli obtained from different disease......) had a distinct ability to cause disease. Results of the study shows major differences in virulence of different strains of E. coli in ascending infections; however, there was no indication of tissue-specific adaptation, since strains obtained from lesions unrelated to the reproductive system were...... fully capable of causing experimental infection. In conclusion, the study provides evidence for the clinical outcome of infection with E. coli in poultry is largely influenced by the specific strain as well as individual host factors....

Inactivation and Gene Expression of a Virulent WastewaterEscherichia coliStrain and the Nonvirulent CommensalEscherichia coliDSM1103 Strain upon Solar Irradiation

KAUST Repository

Aljassim, Nada I.; Mantilla-Calderon, David; Wang, Tiannyu; Hong, Pei-Ying

2017-01-01

This study examined the decay kinetics and molecular responses of two Escherichia coli strains upon solar irradiation. The first is E. coli PI-7, a virulent and antibiotic-resistant strain that was isolated from wastewater and carries the emerging NDM-1 antibiotic resistance gene. The other strain, E. coli DSM1103, displayed lower virulence and antibiotic resistance than E. coli PI-7. In a buffer solution, E. coli PI-7 displayed a longer lag phase prior to decay and a longer half-life compared with E. coli DSM1103 (6.64 ± 0.63 h and 2.85 ± 0.46 min vs 1.33 ± 0.52 h and 2.04 ± 0.36 min). In wastewater, both E. coli strains decayed slower than they did in buffer. Although solar irradiation remained effective in reducing the numbers of both strains by more than 5-log10 in <24 h, comparative genomics and transcriptomics revealed differences in the genomes and overall regulation of genes between the two E. coli strains. A wider arsenal of genes related to oxidative stress, cellular repair and protective mechanisms were upregulated in E. coli PI-7. Subpopulations of E. coli PI-7 expressed genes related to dormancy and persister cell formation during the late decay phase, which may have accounted for its prolonged persistence. Upon prolonged solar irradiation, both E. coli strains displayed upregulation of genes related to horizontal gene transfer and antibiotic resistance. Virulence functions unique to E. coli PI-7 were also upregulated. Our findings collectively indicated that, whereas solar irradiation is able to reduce total cell numbers, viable E. coli remained and expressed genes that enable survival despite solar treatment. There remains a need for heightened levels of concern regarding risks arising from the dissemination of E. coli that may remain viable in wastewater after solar irradiation.

Inactivation and Gene Expression of a Virulent WastewaterEscherichia coliStrain and the Nonvirulent CommensalEscherichia coliDSM1103 Strain upon Solar Irradiation

KAUST Repository

Aljassim, Nada I.

2017-03-06

This study examined the decay kinetics and molecular responses of two Escherichia coli strains upon solar irradiation. The first is E. coli PI-7, a virulent and antibiotic-resistant strain that was isolated from wastewater and carries the emerging NDM-1 antibiotic resistance gene. The other strain, E. coli DSM1103, displayed lower virulence and antibiotic resistance than E. coli PI-7. In a buffer solution, E. coli PI-7 displayed a longer lag phase prior to decay and a longer half-life compared with E. coli DSM1103 (6.64 ± 0.63 h and 2.85 ± 0.46 min vs 1.33 ± 0.52 h and 2.04 ± 0.36 min). In wastewater, both E. coli strains decayed slower than they did in buffer. Although solar irradiation remained effective in reducing the numbers of both strains by more than 5-log10 in <24 h, comparative genomics and transcriptomics revealed differences in the genomes and overall regulation of genes between the two E. coli strains. A wider arsenal of genes related to oxidative stress, cellular repair and protective mechanisms were upregulated in E. coli PI-7. Subpopulations of E. coli PI-7 expressed genes related to dormancy and persister cell formation during the late decay phase, which may have accounted for its prolonged persistence. Upon prolonged solar irradiation, both E. coli strains displayed upregulation of genes related to horizontal gene transfer and antibiotic resistance. Virulence functions unique to E. coli PI-7 were also upregulated. Our findings collectively indicated that, whereas solar irradiation is able to reduce total cell numbers, viable E. coli remained and expressed genes that enable survival despite solar treatment. There remains a need for heightened levels of concern regarding risks arising from the dissemination of E. coli that may remain viable in wastewater after solar irradiation.

Treatment of inflammatory bowel disease associated E. coli with ciprofloxacin and E. coli Nissle in the streptomycin-treated mouse intestine

DEFF Research Database (Denmark)

Petersen, Andreas Munk; Schjørring, Susanne; Gerstrøm, Sarah Choi

2011-01-01

E. coli belonging to the phylogenetic group B2 are linked to Inflammatory Bowel Disease (IBD). Studies have shown that antimicrobials have some effect in the treatment of IBD, and it has been demonstrated that E. coli Nissle has prophylactic abilities comparable to 5-aminosalicylic acid (5-ASA......) therapy in ulcerative colitis. The objective of this study was to test if ciprofloxacin and/or E. coli Nissle could eradicate IBD associated E. coli in the streptomycin-treated mouse intestine....

Sequence features of E. coli mRNAs affect their degradation.

Directory of Open Access Journals (Sweden)

Gal Lenz

Full Text Available Degradation of mRNA in bacteria is a regulatory mechanism, providing an efficient way to fine-tune protein abundance in response to environmental changes. While the mechanisms responsible for initiation and subsequent propagation of mRNA degradation are well studied, the mRNA features that affect its stability are yet to be elucidated. We calculated three properties for each mRNA in the E. coli transcriptome: G+C content, tRNA adaptation index (tAI and folding energy. Each of these properties were then correlated with the experimental transcript half life measured for each transcript and detected significant correlations. A sliding window analysis identified the regions that displayed the maximal signal. The correlation between transcript half life and both G+C content and folding energy was strongest at the 5' termini of the mRNAs. Partial correlations showed that each of the parameters contributes separately to mRNA half life. Notably, mRNAs of recently-acquired genes in the E. coli genome, which have a distinct nucleotide composition, tend to be highly stable. This high stability may aid the evolutionary fixation of horizontally acquired genes.

Lipocalin 2 is protective against E. coli pneumonia

DEFF Research Database (Denmark)

Wu, Hong; Santoni-Rugiu, Eric; Ralfkiaer, Elisabeth

2010-01-01

Lipocalin 2 is a bacteriostatic protein that binds the siderophore enterobactin, an iron-chelating molecule produced by Escherichia coli (E. coli) that is required for bacterial growth. Infection of the lungs by E. coli is rare despite a frequent exposure to this commensal bacterium. Lipocalin 2...... is an effector molecule of the innate immune system and could therefore play a role in hindering growth of E. coli in the lungs....

PARTICIPATION OF TLR4 IN ENGULFMENT OF ESCHERICHIA COLI BY HUMAN BLOOD NEUTROPHILS IN PRESENCE OF LIPOPOLYSACCHARIDES

Directory of Open Access Journals (Sweden)

S. V. Zubova

2012-01-01

Full Text Available Abstract. TLR4 is a key player in signaling system of host cells. Possible role of TLR4 is actively discussed, e.g. its significance for phagocytosis. A capacity of neutrophils to engulf FITC-labeled E. coli bacteria upon activation with LPS of different origin was studied in presence of anti-TLR4 Mab’s (HTA125 clone. It was shown that, in whole blood, TLR4 does not play any essential role in engulfment of bacteria by the neutrophils. Phagocytic activity of neutrophils in blood increases increased after their priming with E. coli endotoxins. LPS from Rb. сapsulatus did not affect phagocytosis. In presence of endotoxins, the degree of TLR4 involvement in neutrophil phagocytosis depends on LPS structure.

FTIR nanobiosensors for Escherichia coli detection

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Stefania Mura

2012-07-01

Full Text Available Infections due to enterohaemorrhagic E. coli (Escherichia coli have a low incidence but can have severe and sometimes fatal health consequences, and thus represent some of the most serious diseases due to the contamination of water and food. New, fast and simple devices that monitor these pathogens are necessary to improve the safety of our food supply chain. In this work we report on mesoporous titania thin-film substrates as sensors to detect E. coli O157:H7. Titania films treated with APTES ((3-aminopropyltriethoxysilane and GA (glutaraldehyde were functionalized with specific antibodies and the absorption properties monitored. The film-based biosensors showed a detection limit for E. coli of 1 × 102 CFU/mL, constituting a simple and selective method for the effective screening of water samples.

Predictions for measuring the cross power spectrum of the HI 21-cm signal and the Lyman-α forest using OWFA

Science.gov (United States)

Sarkar, Anjan Kumar; Bharadwaj, Somnath; Guha Sarkar, Tapomoy

2018-05-01

We have studied the possibility of measuring the cross-correlation of the redshifted HI 21-cm signal and the Lyman-α forest using an upcoming radio-interferometric array OWFA and an spectroscopic observation like SDSS-IV. Our results shows that it is possible to have a 6 σ detection of the cross-correlation signal with OWFA PII using an observing time of 200 hrs each in Np = 25 independent fields-of-view. However, not much can be done beyond this using the cross-correlation signal for zc = 3.35 and B = 30 MHz. Apart from this, we have also envisaged a situation where observations are carried out at zc = 3.05 and 2.55 which lie closer to the peak of the quasar distribution at z = 2.25 and with a larger bandwidth of B = 60 MHz. We see that the SNR of the cross-correlation detection can be significantly enhanced to ~ 17 for zc = 2.55 and B = 60 MHz. It is then possible to measure βT and βF individually with an SNR >= 5 by combining the cross-correlation with the HI 21-cm auto-correlation measurements. We further find that a measurement of the binned cross-correlation power spectrum with SNR >= 5 is also possible in several bins at k <= 0.3 Mpc‑1.

Escherichia coli Probiotic Strain ED1a in Pigs Has a Limited Impact on the Gut Carriage of Extended-Spectrum-β-Lactamase-Producing E. coli

Science.gov (United States)

Mourand, G.; Paboeuf, F.; Fleury, M. A.; Jouy, E.; Bougeard, S.; Denamur, E.

2016-01-01

ABSTRACT Four trials were conducted to evaluate the impact of Escherichia coli probiotic strain ED1a administration to pigs on the gut carriage or survival in manure of extended-spectrum-β-lactamase-producing E. coli. Groups of pigs were orally inoculated with strain E. coli M63 carrying the blaCTX-M-1 gene (n = 84) or used as a control (n = 26). In the first two trials, 24 of 40 E. coli M63-inoculated pigs were given E. coli ED1a orally for 6 days starting 8 days after oral inoculation. In the third trial, 10 E. coli M63-inoculated pigs were given either E. coli ED1a or probiotic E. coli Nissle 1917 for 5 days. In the fourth trial, E. coli ED1a was given to a sow and its 12 piglets, and these 12 piglets plus 12 piglets that had not received E. coli ED1a were then inoculated with E. coli M63. Fecal shedding of cefotaxime-resistant Enterobacteriaceae (CTX-RE) was studied by culture, and blaCTX-M-1 genes were quantified by PCR. The persistence of CTX-RE in manure samples from inoculated pigs or manure samples inoculated in vitro with E. coli M63 with or without probiotics was studied. The results showed that E. coli M63 and ED1a were good gut colonizers. The reduction in the level of fecal excretion of CTX-RE in E. coli ED1a-treated pigs compared to that in nontreated pigs was usually less than 1 log10 CFU and was mainly observed during the probiotic administration period. The results obtained with E. coli Nissle 1917 did not differ significantly from those obtained with E. coli ED1a. CTX-RE survival did not differ significantly in manure samples with or without probiotic treatment. In conclusion, under our experimental conditions, E. coli ED1a and E. coli Nissle 1917 could not durably prevent CTX-RE colonization of the pig gut. PMID:27795372

Escherichia coli Probiotic Strain ED1a in Pigs Has a Limited Impact on the Gut Carriage of Extended-Spectrum-β-Lactamase-Producing E. coli.

Science.gov (United States)

Mourand, G; Paboeuf, F; Fleury, M A; Jouy, E; Bougeard, S; Denamur, E; Kempf, I

2017-01-01

Four trials were conducted to evaluate the impact of Escherichia coli probiotic strain ED1a administration to pigs on the gut carriage or survival in manure of extended-spectrum-β-lactamase-producing E. coli Groups of pigs were orally inoculated with strain E. coli M63 carrying the bla CTX-M-1 gene (n = 84) or used as a control (n = 26). In the first two trials, 24 of 40 E. coli M63-inoculated pigs were given E. coli ED1a orally for 6 days starting 8 days after oral inoculation. In the third trial, 10 E. coli M63-inoculated pigs were given either E. coli ED1a or probiotic E. coli Nissle 1917 for 5 days. In the fourth trial, E. coli ED1a was given to a sow and its 12 piglets, and these 12 piglets plus 12 piglets that had not received E. coli ED1a were then inoculated with E. coli M63. Fecal shedding of cefotaxime-resistant Enterobacteriaceae (CTX-RE) was studied by culture, and bla CTX-M-1 genes were quantified by PCR. The persistence of CTX-RE in manure samples from inoculated pigs or manure samples inoculated in vitro with E. coli M63 with or without probiotics was studied. The results showed that E. coli M63 and ED1a were good gut colonizers. The reduction in the level of fecal excretion of CTX-RE in E. coli ED1a-treated pigs compared to that in nontreated pigs was usually less than 1 log 10 CFU and was mainly observed during the probiotic administration period. The results obtained with E. coli Nissle 1917 did not differ significantly from those obtained with E. coli ED1a. CTX-RE survival did not differ significantly in manure samples with or without probiotic treatment. In conclusion, under our experimental conditions, E. coli ED1a and E. coli Nissle 1917 could not durably prevent CTX-RE colonization of the pig gut. Copyright © 2016 American Society for Microbiology.

Saccharomyces boulardii Preserves the Barrier Function and Modulates the Signal Transduction Pathway Induced in Enteropathogenic Escherichia coli-Infected T84 Cells

Science.gov (United States)

Czerucka, Dorota; Dahan, Stephanie; Mograbi, Baharia; Rossi, Bernard; Rampal, Patrick

2000-01-01

Use of the nonpathogenic yeast Saccharomyces boulardii in the treatment of infectious diarrhea has attracted growing interest. The present study designed to investigate the effect of this yeast on enteropathogenic Escherichia coli (EPEC)-associated disease demonstrates that S. boulardii abrogated the alterations induced by an EPEC strain on transepithelial resistance, [3H]inulin flux, and ZO-1 distribution in T84 cells. Moreover, EPEC-mediated apoptosis of epithelial cells was delayed in the presence of S. boulardii. The yeast did not modify the number of adherent bacteria but lowered by 50% the number of intracellular bacteria. Infection by EPEC induced tyrosine phosphorylation of several proteins in T84 cells, including p46 and p52 SHC isoforms, that was attenuated in the presence of S. boulardii. Similarly, EPEC-induced activation of the ERK1/2 mitogen-activated protein (MAP) kinase pathway was diminished in the presence of the yeast. Interestingly, inhibition of the ERK1/2 pathway with the specific inhibitor PD 98059 decreased EPEC internalization, suggesting that modulation of the ERK1/2 MAP pathway might account for the lowering of the number of intracellular bacteria observed in the presence of S. boulardii. Altogether, this study demonstrated that S. boulardii exerts a protective effect on epithelial cells after EPEC adhesion by modulating the signaling pathway induced by bacterial infection. PMID:10992512

Extracellular overexpression of recombinant Thermobifida fusca cutinase by alpha-hemolysin secretion system in E. coli BL21(DE3

Directory of Open Access Journals (Sweden)

Su Lingqia

2012-01-01

Full Text Available Abstract Background Extracellular expression of proteins has an absolute advantage in a large-scale industrial production. In our previous study, Thermobifida fusca cutinase, an enzyme mainly utilized in textile industry, was expressed via type II secretory system in Escherichia coli BL21(DE3, and it was found that parts of the expressed protein was accumulated in the periplasmic space. Due to the fact that alpha-hemolysin secretion system can export target proteins directly from cytoplasm across both cell membrane of E. coli to the culture medium, thus in the present study we investigated the expression of cutinase using this alpha-hemolysin secretion system. Results T. fusca cutinase was fused with the specific signal peptide of alpha-hemolysin scretion system and expressed in E. coli BL21(DE3. In addition, HlyB and HlyD, strain-specific translocation components of alpha-hemolysin secretion system, were coexpressed to facilitate the enzyme expression. The cultivation of this engineered cell showed that cutinase activity in the culture medium reached 334 U/ml, which is 2.5 times that from type II secretion pathway under the same culture condition. The recombinant cutinase was further purified. Biochemical characterization of purified enzyme, which had an α-hemolysin secretion pathway signal peptide attached, had substrate specificity, pH and temperature profile, as well as application capability in bioscouring similar to that of wild-type cutinase. Conclusions In the present study, T. fusca cutinase was successfully secreted to the culture media by α-hemolysin secretion system. This is the first report of cutinase being efficiently secreted by this pathway. Due to the limited cases of successful expression of industrial enzyme by E. coli α-hemolysin secretion system, our study further explored the utilization of this pathway in industrial enzymes.

WGS accurately predicts antimicrobial resistance in Escherichia coli

Science.gov (United States)

Objectives: To determine the effectiveness of whole-genome sequencing (WGS) in identifying resistance genotypes of multidrug-resistant Escherichia coli (E. coli) and whether these correlate with observed phenotypes. Methods: Seventy-six E. coli strains were isolated from farm cattle and measured f...

Profiling of Escherichia coli Chromosome database.

Science.gov (United States)

Yamazaki, Yukiko; Niki, Hironori; Kato, Jun-ichi

2008-01-01

The Profiling of Escherichia coli Chromosome (PEC) database (http://www.shigen.nig.ac.jp/ecoli/pec/) is designed to allow E. coli researchers to efficiently access information from functional genomics studies. The database contains two principal types of data: gene essentiality and a large collection of E. coli genetic research resources. The essentiality data are based on data compilation from published single-gene essentiality studies and on cell growth studies of large-deletion mutants. Using the circular and linear viewers for both whole genomes and the minimal genome, users can not only gain an overview of the genome structure but also retrieve information on contigs, gene products, mutants, deletions, and so forth. In particular, genome-wide exhaustive mutants are an essential resource for studying E. coli gene functions. Although the genomic database was constructed independently from the genetic resources database, users may seamlessly access both types of data. In addition to these data, the PEC database also provides a summary of homologous genes of other bacterial genomes and of protein structure information, with a comprehensive interface. The PEC is thus a convenient and useful platform for contemporary E. coli researchers.

Evaluation of Petrifilm™ Select E. coli Count Plate medium to discriminate antimicrobial resistant Escherichia coli

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Jensen Lars

2008-09-01

Full Text Available Abstract Background Screening and enumeration of antimicrobial resistant Escherichia coli directly from samples is needed to identify emerging resistant clones and obtain quantitative data for risk assessment. Aim of this study was to evaluate the performance of 3M™ Petrifilm™ Select E. coli Count Plate (SEC plate supplemented with antimicrobials to discriminate antimicrobial-resistant and non-resistant E. coli. Method A range of E. coli isolates were tested by agar dilution method comparing the Minimal Inhibitory Concentration (MIC for eight antimicrobials obtained by Mueller-Hinton II agar, MacConkey agar and SEC plates. Kappa statistics was used to assess the levels of agreement when classifying strains as resistant, intermediate or susceptible. Results SEC plate showed that 74% of all strains agreed within ± 1 log2 dilution when comparing MICs with Mueller-Hinton II media. High agreement levels were found for gentamicin, ampicillin, chloramphenicol and cefotaxime, resulting in a kappa value of 0.9 and 100% agreement within ± 1 log2 dilution. Significant variances were observed for oxytetracycline and sulphamethoxazole. Further tests showed that the observed discrepancy in classification of susceptibility to oxytetracycline by the two media could be overcome when a plate-dependent breakpoint of 64 mg/L was used for SEC plates. For sulphamethoxazole, SEC plates provided unacceptably high MICs. Conclusion SEC plates showed good agreement with Mueller-Hinton II agar in MIC studies and can be used to screen and discriminate resistant E. coli for ampicillin, cephalothin, streptomycin, chloramphenicol, cefotaxime and gentamicin using CLSI standardized breakpoints, but not for sulphamethoxazole. SEC plates can also be used to discriminate oxytetracycline-resistant E. coli if a plate-dependent breakpoint value of 64 mg/L is used.

Infectious endocarditis caused by Escherichia coli

DEFF Research Database (Denmark)

Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas

2011-01-01

Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad......-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra......-intestinal pathogenic E. coli (ExPEC) are able to colonize tissue outside the gastrointestinal tract and contain a variety of virulence factors that may enable the pathogens to invade and induce infections in the cardiac endothelia. In these cases echocardiography as the imaging technology is of paramount importance...

Infectious endocarditis caused by Escherichia coli

DEFF Research Database (Denmark)

Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas

2011-01-01

Although Escherichia coli is among the most common causes of Gram-negative bacteraemia, infectious endocarditis (IE) due to this pathogen is rare. A 67-y-old male without a previous medical history presented with a new mitral regurgitation murmur and persisting E. coli bacteraemia in spite of broad......-spectrum intravenous antibiotics. Transthoracic and transoesophageal echocardiography revealed a severe mitral endocarditis. E. coli DNA was identified from the mitral valve and the vegetation, and no other pathogen was found. The case was further complicated by spondylodiscitis and bilateral endophthalmitis. Extra...

Dynamic single-cell NAD(P)H measurement reveals oscillatory metabolism throughout the E. coli cell division cycle.

Science.gov (United States)

Zhang, Zheng; Milias-Argeitis, Andreas; Heinemann, Matthias

2018-02-01

Recent work has shown that metabolism between individual bacterial cells in an otherwise isogenetic population can be different. To investigate such heterogeneity, experimental methods to zoom into the metabolism of individual cells are required. To this end, the autofluoresence of the redox cofactors NADH and NADPH offers great potential for single-cell dynamic NAD(P)H measurements. However, NAD(P)H excitation requires UV light, which can cause cell damage. In this work, we developed a method for time-lapse NAD(P)H imaging in single E. coli cells. Our method combines a setup with reduced background emission, UV-enhanced microscopy equipment and optimized exposure settings, overall generating acceptable NAD(P)H signals from single cells, with minimal negative effect on cell growth. Through different experiments, in which we perturb E. coli's redox metabolism, we demonstrated that the acquired fluorescence signal indeed corresponds to NAD(P)H. Using this new method, for the first time, we report that intracellular NAD(P)H levels oscillate along the bacterial cell division cycle. The developed method for dynamic measurement of NAD(P)H in single bacterial cells will be an important tool to zoom into metabolism of individual cells.

Glucose uptake regulation in E. coli by the small RNA SgrS: comparative analysis of E. coli K-12 (JM109 and MG1655 and E. coli B (BL21

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Ng Weng-Ian

2010-09-01

Full Text Available Abstract Background The effect of high glucose concentration on the transcription levels of the small RNA SgrS and the messenger RNA ptsG, (encoding the glucose transporter IICBGlc, was studied in both E. coli K-12 (MG1655 and JM109 and E. coli B (BL21. It is known that the transcription level of sgrS increases when E. coli K-12 (MG1655 and JM109 is exposed to the non-metabolized glucose alpha methyl glucoside (αMG or when the bacteria with a defective glycolysis pathway is grown in presence of glucose. The increased level of sRNA SgrS reduces the level of the ptsG mRNA and consequently lowers the level of the glucose transporter IICBGlc. The suggested trigger for this action is the accumulation of the corresponding phospho-sugars. Results In the course of the described work, it was found that E. coli B (BL21 and E. coli K-12 (JM109 and MG1655 responded similarly to αMG: both strains increased SgrS transcription and reduced ptsG transcription. However, the two strains reacted differently to high glucose concentration (40 g/L. E. coli B (BL21 reacted by increasing sgrS transcription and reducing ptsG transcription while E. coli K-12 (JM109 and MG1655 did not respond to the high glucose concentration, and, therefore, transcription of sgrS was not detected and ptsG mRNA level was not affected. Conclusions The results suggest that E. coli B (BL21 tolerates high glucose concentration not only by its more efficient central carbon metabolism, but also by controlling the glucose transport into the cells regulated by the sRNA SgrS, which may suggest a way to control glucose consumption and increase its efficient utilization.

Whole-genome phylogeny of Escherichia coli/Shigella group by feature frequency profiles (FFPs)

Science.gov (United States)

Sims, Gregory E.; Kim, Sung-Hou

2011-01-01

A whole-genome phylogeny of the Escherichia coli/Shigella group was constructed by using the feature frequency profile (FFP) method. This alignment-free approach uses the frequencies of l-mer features of whole genomes to infer phylogenic distances. We present two phylogenies that accentuate different aspects of E. coli/Shigella genomic evolution: (i) one based on the compositions of all possible features of length l = 24 (∼8.4 million features), which are likely to reveal the phenetic grouping and relationship among the organisms and (ii) the other based on the compositions of core features with low frequency and low variability (∼0.56 million features), which account for ∼69% of all commonly shared features among 38 taxa examined and are likely to have genome-wide lineal evolutionary signal. Shigella appears as a single clade when all possible features are used without filtering of noncore features. However, results using core features show that Shigella consists of at least two distantly related subclades, implying that the subclades evolved into a single clade because of a high degree of convergence influenced by mobile genetic elements and niche adaptation. In both FFP trees, the basal group of the E. coli/Shigella phylogeny is the B2 phylogroup, which contains primarily uropathogenic strains, suggesting that the E. coli/Shigella ancestor was likely a facultative or opportunistic pathogen. The extant commensal strains diverged relatively late and appear to be the result of reductive evolution of genomes. We also identify clade distinguishing features and their associated genomic regions within each phylogroup. Such features may provide useful information for understanding evolution of the groups and for quick diagnostic identification of each phylogroup. PMID:21536867

Expression of the major outer membrane protein (MOMP) of Chlamydophila abortus, Chlamydophila pecorum, and Chlamydia suis in Escherichia coli using an arabinose-inducible plasmid vector.

Science.gov (United States)

Hoelzle, L E; Hoelzle, K; Wittenbrink, M M

2003-10-01

The ompA genes encoding the 40 kDa major outer membrane protein (MOMP) of Chlamydophila (Ch.) abortus, Ch. pecorum, and Chlamydia (C.) suis were cloned into the arabinose-inducible plasmid vector pBADMycHis, and recombinant MOMPs (rMOMP) from the three chlamydial species were expressed at high levels in Escherichia (E.) coli. The proteins lacking the 22 aa N-terminal signal peptide were expressed as insoluble cytoplasmic inclusion bodies which were readily purified using immobilized metal-affinity chromatography. The rMOMPs including the N-terminal signal peptide were expressed and translocated as a surface-exposed immunoaccessible protein into the outer membrane of E. coli. Transformants expressing this full-length rMOMP were significantly reduced in viability. Purified native elementary bodies (EB) and rMOMPs of the three chlamydial species purified from the E. coli cytoplasm were used for immunization of rabbits. The resulting sera were analysed for their ability to recognize homologous and heterologous rMOMP and native EB. When testing rMOMP antisera against rMOMP and EB antigens, marked cross-reactivities were detected between the three species. Using EB antisera and rMOMPs as antigens, a significant species-specific reactivity was measured.

Endogenous E. coli endophthalmitis.

Science.gov (United States)

Shammas, H F

1977-01-01

A case of Escherichia coli septicemia with associated metastatic en dophthalmitis and endocarditis is presented. The ocular signs and symptoms were the initial manifestations of sepsis. Irreversible damage to the eye occurred in less than 24 hours. The pattern of metastatic bacterial endophthalmitis has changed since the introduction of potent antimicrobial agents, with an increased incidence of Gram-negative bacillemia. E. coli endophthalmitis carries a poor prognosis. Early diagnosis and systemic treatment will prevent the life-threatening complications of sepsis.

Porphyromonas endodontalis lipopolysaccharides induce RANKL by mouse osteoblast in a way different from that of Escherichia coli lipopolysaccharide.

Science.gov (United States)

Tang, Yin; Sun, Feifei; Li, Xiaoting; Zhou, Yuan; Yin, Shihai; Zhou, Xuedong

2011-12-01

Porphyromonas endodontalis lipopolysaccharide (LPS) has been shown to have a high positive rate in infected root canals and symptomatic apical periodontitis. It may play an integral role as a potent stimulator of inflammatory cytokines involved in apical lesions. The receptor activator of nuclear factor-κB ligand (RANKL) has been proven to be the key regulator of bone remodeling. This study investigated P. endodontalis LPS-induced RANKL production and LPS signaling in mouse osteoblasts. LPS-induced RANKL production in mouse osteoblast MC3T3-E1 cells was measured by Western blot and real-time polymerase chain reaction, and the Toll-like receptors (TLRs) were determined by the blocking test using anti-TLRs antibodies. In addition, specific inhibitors were used to analyze the intracellular signaling pathways. Escherichia coli LPS was used as the control. Both of the anti-TLR2 and anti-TLR4 antibodies significantly (P endodontalis LPS; only anti-TLR2 antibody had a significant (P endodontalis LPS-infected osteoblasts (P endodontalis LPS has the ability to promote the expression of RANKL in mouse osteoblasts, and this induction was mainly through the TLR2/4-JNK signaling pathway, a situation quite different from that of typical bacterial endotoxin (E. coli LPS). Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Escherichia coli pyomyositis in an immunocompromised host.

Science.gov (United States)

Sharma, Umesh; Schwan, William R; Agger, William A

2011-08-01

Pyomyositis due to Escherichia coli (E. coil) is rarely reported in immunocompromised patients with hematological malignancy. We present a case report of a 34-year-old man who developed E. coli pyomyositis as a complication of acute myelogenous leukemia (AML). Magnetic resonance imaging (MRI) of the right hip suggested myofascial infection of the gluteal muscles, and a needle muscle aspiration grew E. coli phylogenetic group B2. The patient responded to intravenous piperacillin/tazobactam followed by prolonged oral levofloxacin. Pyomyositis should be suspected in all immunocompromised patients complaining of muscle pain and may exhibit signs of localized muscle infection. Appropriate antibiotic therapy targeting fluoroquinolone-resistant E. coli should be considered for initial empiric therapy of pyomyositis in immunocompromised patients.

Expression and purification of recombinant proteins in Escherichia coli tagged with the metal-binding protein CusF.

Science.gov (United States)

Cantu-Bustos, J Enrique; Vargas-Cortez, Teresa; Morones-Ramirez, Jose Ruben; Balderas-Renteria, Isaias; Galbraith, David W; McEvoy, Megan M; Zarate, Xristo

2016-05-01

Production of recombinant proteins in Escherichia coli has been improved considerably through the use of fusion proteins, because they increase protein solubility and facilitate purification via affinity chromatography. In this article, we propose the use of CusF as a new fusion partner for expression and purification of recombinant proteins in E. coli. Using a cell-free protein expression system, based on the E. coli S30 extract, Green Fluorescent Protein (GFP) was expressed with a series of different N-terminal tags, immobilized on self-assembled protein microarrays, and its fluorescence quantified. GFP tagged with CusF showed the highest fluorescence intensity, and this was greater than the intensities from corresponding GFP constructs that contained MBP or GST tags. Analysis of protein production in vivo showed that CusF produces large amounts of soluble protein with low levels of inclusion bodies. Furthermore, fusion proteins can be exported to the cellular periplasm, if CusF contains the signal sequence. Taking advantage of its ability to bind copper ions, recombinant proteins can be purified with readily available IMAC resins charged with this metal ion, producing pure proteins after purification and tag removal. We therefore recommend the use of CusF as a viable alternative to MBP or GST as a fusion protein/affinity tag for the production of soluble recombinant proteins in E. coli. Copyright © 2016 Elsevier Inc. All rights reserved.

Gene encoding virulence markers among Escherichia coli isolates ...

African Journals Online (AJOL)

River water sources and diarrhoeic stools of residents in the Venda Region, Limpopo Province of South Africa were analysed for the prevalence of Escherichia coli (E. coli) and the presence of virulence genes among the isolates. A control group of 100 nondiarrhoeic stool samples was included. Escherichia coli was ...

Genomic Comparative Study of Bovine Mastitis Escherichia coli.

Science.gov (United States)

Kempf, Florent; Slugocki, Cindy; Blum, Shlomo E; Leitner, Gabriel; Germon, Pierre

2016-01-01

Escherichia coli, one of the main causative agents of bovine mastitis, is responsible for significant losses on dairy farms. In order to better understand the pathogenicity of E. coli mastitis, an accurate characterization of E. coli strains isolated from mastitis cases is required. By using phylogenetic analyses and whole genome comparison of 5 currently available mastitis E. coli genome sequences, we searched for genotypic traits specific for mastitis isolates. Our data confirm that there is a bias in the distribution of mastitis isolates in the different phylogenetic groups of the E. coli species, with the majority of strains belonging to phylogenetic groups A and B1. An interesting feature is that clustering of strains based on their accessory genome is very similar to that obtained using the core genome. This finding illustrates the fact that phenotypic properties of strains from different phylogroups are likely to be different. As a consequence, it is possible that different strategies could be used by mastitis isolates of different phylogroups to trigger mastitis. Our results indicate that mastitis E. coli isolates analyzed in this study carry very few of the virulence genes described in other pathogenic E. coli strains. A more detailed analysis of the presence/absence of genes involved in LPS synthesis, iron acquisition and type 6 secretion systems did not uncover specific properties of mastitis isolates. Altogether, these results indicate that mastitis E. coli isolates are rather characterized by a lack of bona fide currently described virulence genes.

Fimbrial adhesins from extraintestinal Escherichia coli

DEFF Research Database (Denmark)

Klemm, Per; Hancock, Viktoria; Schembri, Mark A.

2010-01-01

Extraintestinal pathogenic Escherichia coli (ExPEC) represent an important subclass of E. coli that cause a wide spectrum of diseases in human and animal hosts. Fimbriae are key virulence factors of ExPEC strains. These long surface located rod-shaped organelles mediate receptor-specific attachment...

Enterohemorrhagic Escherichia coli senses low biotin status in the large intestine for colonization and infection

Science.gov (United States)

Yang, Bin; Feng, Lu; Wang, Fang; Wang, Lei

2015-01-01

Enterohemorrhagic Escherichia coli (EHEC) is an important foodborne pathogen that infects humans by colonizing the large intestine. Here we identify a virulence-regulating pathway in which the biotin protein ligase BirA signals to the global regulator Fur, which in turn activates LEE (locus of enterocyte effacement) genes to promote EHEC adherence in the low-biotin large intestine. LEE genes are repressed in the high-biotin small intestine, thus preventing adherence and ensuring selective colonization of the large intestine. The presence of this pathway in all nine EHEC serotypes tested indicates that it is an important evolutionary strategy for EHEC. The pathway is incomplete in closely related small-intestinal enteropathogenic E. coli due to the lack of the Fur response to BirA. Mice fed with a biotin-rich diet show significantly reduced EHEC adherence, indicating that biotin might be useful to prevent EHEC infection in humans. PMID:25791315

Role of Uropathogenic Escherichia coli Virulence Factors in Development of Urinary Tract Infection and Kidney Damage

Science.gov (United States)

Bien, Justyna; Sokolova, Olga; Bozko, Przemyslaw

2012-01-01

Uropathogenic Escherichia coli (UPEC) is a causative agent in the vast majority of urinary tract infections (UTIs), including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs. PMID:22506110

PATHOGENIC POTENTIALS OF ESCHERICHIA COLI ISOLATED ...

African Journals Online (AJOL)

Electrolyte and haematological parameters in rabbits infected with pathogenic isolates of Escherichia coli from rural water supplies in Rivers State, Nigeria, where monitored. Rabbits were orally infected with suspension containing 3x107 cfu /ml of Escherichia coli to induce diarrhoea, and the electrolyte (sodium, potassium ...

Recombinant dioscorins of the yam storage protein expressed in Escherichia coli exhibit antioxidant and immunomodulatory activities.

Science.gov (United States)

Jheng, Yi-Jyun; Tsai, Wei-Yi; Chen, Kuo-Hsuan; Lin, Kuo-Wei; Chyan, Chia-Lin; Yang, Ching-Chi; Lin, Kuo-Chih

2012-09-01

Dioscorins, the major storage proteins in yam tubers, exhibit biochemical and immunomodulatroy activities. To investigate the potential application of dioscorins in biomedical research, we expressed the dioscorin genes Dj-dioA3 and Dp-dioA2 from Dioscorea japonica and Dioscorea pseudojaponica, respectively, in E. coli and routinely obtained approximately 15 mg proteins per liter Escherichia coli culture (mg/L) to 30 mg/L of rDj-dioscorinA3 and 4 to 8 mg/L of rDp-dioscorinA2. Western blot analyses revealed that both recombinant dioscorins contained epitopes with similar antigenicities to those of the native dioscorins. Results from dithiothreitol (DTT) treatment followed by monobromobimane (mBBr) staining showed that both recombinant dioscorins, like the native dioscorins, contain an intramolecular disulfide bond between Cys(28) and Cys(187) residues. Circular dichroism spectroscopy findings indicated that the secondary structural contents of the recombinant dioscorins showed high similarity to those of their corresponding native dioscorins. Both recombinant dioscorins, like the native dioscorins, exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and Toll-like receptor 4 signaling activities, and stimulated the phagocytosis of E. coli by macrophage. Overall, our results indicated that substantial amounts of recombinant dioscorins can be purified easily from E. coli and that these recombinant dioscorins are appropriate for application in future investigations of the biomedical functions of dioscorins. Copyright © 2012 Elsevier Inc. All rights reserved.

Expression and purification of recombinant proteins in Escherichia coli tagged with a small metal-binding protein from Nitrosomonas europaea.

Science.gov (United States)

Vargas-Cortez, Teresa; Morones-Ramirez, Jose Ruben; Balderas-Renteria, Isaias; Zarate, Xristo

2016-02-01

Escherichia coli is still the preferred organism for large-scale production of recombinant proteins. The use of fusion proteins has helped considerably in enhancing the solubility of heterologous proteins and their purification with affinity chromatography. Here, the use of a small metal-binding protein (SmbP) from Nitrosomonas europaea is described as a new fusion protein for protein expression and purification in E. coli. Fluorescent proteins tagged at the N-terminal with SmbP showed high levels of solubility, compared with those of maltose-binding protein and glutathione S-transferase, and low formation of inclusion bodies. Using commercially available IMAC resins charged with Ni(II), highly pure recombinant proteins were obtained after just one chromatography step. Proteins may be purified from the periplasm of E. coli if SmbP contains the signal sequence at the N-terminal. After removal of the SmbP tag from the protein of interest, high-yields are obtained since SmbP is a protein of just 9.9 kDa. The results here obtained suggest that SmbP is a good alternative as a fusion protein/affinity tag for the production of soluble recombinant proteins in E. coli. Copyright © 2015 Elsevier Inc. All rights reserved.

Synergistic effects in mixed Escherichia coli biofilms

DEFF Research Database (Denmark)

Reisner, A.; Holler, B.M.; Molin, Søren

2006-01-01

Bacterial biofilms, often composed of multiple species and genetically distinct strains, develop under complex influences of cell-cell interactions. Although detailed knowledge about the mechanisms underlying formation of single-species laboratory biofilms has emerged, little is known about...... the pathways governing development of more complex heterogeneous communities. In this study, we established a laboratory model where biofilm-stimulating effects due to interactions between genetically diverse strains of Escherichia coli were monitored. Synergistic induction of biofilm formation resulting from...... the cocultivation of 403 undomesticated E. coli strains with a characterized E. coli K-12 strain was detected at a significant frequency. The survey suggests that different mechanisms underlie the observed stimulation, yet synergistic development of biofilm within the subset of E. coli isolates (n = 56) exhibiting...

Faecal Escherichia coli from patients with E. coli urinary tract infection and healthy controls who have never had a urinary tract infection

DEFF Research Database (Denmark)

Nielsen, Karen L; Dynesen, Pia; Larsen, Preben

2014-01-01

Urinary tract infections (UTIs) are primarily caused by Escherichia coli with the patient's own faecal flora acting as a reservoir for the infecting E. coli. Here we sought to characterize the E. coli faecal flora of UTI patients and healthy controls who had never had a UTI. Up to 20 E. coli...... colonies from each rectal swab were random amplified polymorphic DNA (RAPD) typed for clonality, dominance in the sample and correlation to the infecting UTI isolate in patients. Each distinct clone was phylotyped and tested for antimicrobial susceptibility. Eighty-seven per cent of the UTI patients...... carried the infecting strain in their faecal flora, and faecal clones causing UTI were more often dominant in the faecal flora. Patients had a larger diversity of E. coli in their gut flora by carrying more unique E. coli clones compared to controls, and patient faecal clones were more often associated...

77 FR 9888 - Shiga Toxin-Producing Escherichia coli

Science.gov (United States)

2012-02-21

... Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service... toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145). This new date..., that are contaminated with Shiga toxin-producing Escherichia coli (STEC) O26, O45, O103, O111, O121...

Effects of burn with and without Escherichia coli infection in rats on intestinal vs. splenic T-cell responses.

Science.gov (United States)

Ravindranath, T; Al-Ghoul, W; Namak, S; Fazal, N; Durazo-Arvizu, R; Choudhry, M; Sayeed, M M

2001-12-01

To evaluate the effect of burn injury with and without an Escherichia coliseptic complication on T-cell proliferation, interleukin-2 production, and Ca(2+) signaling responses in intestinal Peyer's patch and splenic T cells. Prospective, randomized, sham-controlled animal study. University medical center research laboratory. Adult male Sprague-Dawley rats. Rats were subjected to a 30% total body surface area, full skin thickness burn. Infection in rats was induced via intraperitoneal inoculation of E. coli, 10(9) colony forming units/kg, with or without a prior burn. Rat Peyer's patch and splenic T lymphocytes were isolated by using a nylon wool cell purification protocol. T-cell proliferation, interleukin-2 production, and Ca(2+) signaling responses were measured after stimulation of cells with the mitogen, concanavalin A. T-cell proliferation was determined by measuring incorporation of (3)H-thymidine into T-cell cultures. Interleukin-2 production by T-cell cultures was measured by using enzyme-linked immunosorbent assay. Intracellular T-cell Ca2(+ )concentration, [Ca(2+)](i), was measured by the use of Ca(2+)-specific fluorescent label, fura-2, and its fluorometric quantification. [Ca(2+)](i) was also evaluated by the use of digital video imaging of fura-2 loaded individual T cells. T-cell proliferation and interleukin-2 production were suppressed substantially in both Peyer's patch and splenic T cells 3 days after either the initial burn alone or burn followed by the E. coli inoculation at 24 hrs after the initial burn. There seemed to be no demonstrable additive effects of E. coli infection on the effects produced by burn injury alone. The T-cell proliferation and interleukin-2 production suppressions with burn or burn-plus-infection insults were correlated with attenuated Ca(2+) signaling. E. coli infection alone suppressed T-cell proliferation in Peyer's patch but not in splenic T cells at 2 days postbacterial inoculation; E. coli infection had no effect on

Synthesis of avenanthramides using engineered Escherichia coli.

Science.gov (United States)

Lee, Su Jin; Sim, Geun Young; Kang, Hyunook; Yeo, Won Seok; Kim, Bong-Gyu; Ahn, Joong-Hoon

2018-03-22

Hydroxycinnamoyl anthranilates, also known as avenanthramides (avns), are a group of phenolic alkaloids with anti-inflammatory, antioxidant, anti-itch, anti-irritant, and antiatherogenic activities. Some avenanthramides (avn A-H and avn K) are conjugates of hydroxycinnamic acids (HC), including p-coumaric acid, caffeic acid, and ferulic acid, and anthranilate derivatives, including anthranilate, 4-hydroxyanthranilate, and 5-hydroxyanthranilate. Avns are primarily found in oat grain, in which they were originally designated as phytoalexins. Knowledge of the avns biosynthesis pathway has now made it possible to synthesize avns through a genetic engineering strategy, which would help to further elucidate their properties and exploit their beneficial biological activities. The aim of the present study was to synthesize natural avns in Escherichia coli to serve as a valuable resource. We synthesized nine avns in E. coli. We first synthesized avn D from glucose in E. coli harboring tyrosine ammonia lyase (TAL), 4-coumarate:coenzyme A ligase (4CL), anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT), and anthranilate synthase (trpEG). A trpD deletion mutant was used to increase the amount of anthranilate in E. coli. After optimizing the incubation temperature and cell density, approximately 317.2 mg/L of avn D was synthesized. Avn E and avn F were then synthesized from avn D, using either E. coli harboring HpaBC and SOMT9 or E. coli harboring HapBC alone, respectively. Avn A and avn G were synthesized by feeding 5-hydroxyanthranilate or 4-hydroxyanthranilate to E. coli harboring TAL, 4CL, and HCBT. Avn B, avn C, avn H, and avn K were synthesized from avn A or avn G, using the same approach employed for the synthesis of avn E and avn F from avn D. Using different HCs, nine avns were synthesized, three of which (avn D, avn E, and avn F) were synthesized from glucose in E. coli. These diverse avns provide a strategy to synthesize both natural and unnatural avns

Distribution of Diverse Escherichia coli between Cattle and Pasture

OpenAIRE

NandaKafle, Gitanjali; Seale, Tarren; Flint, Toby; Nepal, Madhav; Venter, Stephanus N.; Brözel, Volker S.

2017-01-01

Escherichia coli is widely considered to not survive for extended periods outside the intestines of warm-blooded animals; however, recent studies demonstrated that E. coli strains maintain populations in soil and water without any known fecal contamination. The objective of this study was to investigate whether the niche partitioning of E. coli occurs between cattle and their pasture. We attempted to clarify whether E. coli from bovine feces differs phenotypically and genotypically from isola...

PART I. ESCHERICHIA COLI

Directory of Open Access Journals (Sweden)

Sanaa Mahdi Oraibi

2016-11-01

Full Text Available The presence of Escherichia coli in the air of facilities involved in management and composting of post-slaughter poultry wastes in selected plants of West Western Pomerania region was studied. Measurements were made on four dates in a variety of weather conditions during the year. The study was conducted at 5 objects that differ in the type of waste and the degree of preparation for composting. These were: chemical treatment and preliminary processing plant, liquid wastes reservoir, platform for preparation of materials for composting, storage of biological sediments, and composting facility. Measurement of bacteria count was carried out in accordance with the applicable procedures on selective chromogenic TBX medium. The assays revealed the presence of E. coli at all test objects, but not always on all measurement dates. It has been shown that the presence of E. coli was from 20 to 3047 CFU∙m-3 of air, although the largest quantities were most frequently detected in the air of the building for post-slaughter waste pre-treatment in chemical treatment plant.

Autoinducer-2 Quorum Sensing Contributes to Regulation of Microcin PDI in Escherichia coli

Directory of Open Access Journals (Sweden)

Shao-Yeh Lu

2017-12-01

Full Text Available The Escherichia coli quorum sensing (QS signal molecule, autoinducer-2 (AI-2, reaches its maximum concentration during mid-to-late growth phase after which it quickly degrades during stationary phase. This pattern of AI-2 concentration coincides with the up- then down-regulation of a recently described microcin PDI (mccPDI effector protein (McpM. To determine if there is a functional relationship between these systems, a prototypical mccPDI-expressing strain of E. coli 25 was used to generate ΔluxS, ΔlsrACDBFG (Δlsr, and ΔlsrR mutant strains that are deficient in AI-2 production, transportation, and AI-2 transport regulation, respectively. Trans-complementation, RT-qPCR, and western blot assays were used to detect changes of microcin expression and synthesis under co-culture and monoculture conditions. Compared to the wild-type strain, the AI-2-deficient strain (ΔluxS and -uptake negative strain (Δlsr were >1,000-fold less inhibitory to susceptible bacteria (P < 0.05. With in trans complementation of luxS, the AI-2 deficient mutant reduced the susceptible E. coli population by 4-log, which was within 1-log of the wild-type phenotype. RT-qPCR and western blot results for the AI-2 deficient E. coli 25 showed a 5-fold reduction in mcpM transcription with an average 2-h delay in McpM synthesis. Furthermore, overexpression of sRNA micC and micF (both involved in porin protein regulation was correlated with mcpM regulation, consistent with a possible link between QS and mcpM regulation. This is the direct first evidence that microcin regulation can be linked to quorum sensing in a Gram-negative bacterium.

Anal Canal Cancer: Management of Inguinal Nodes and Benefit of Prophylactic Inguinal Irradiation (CORS-03 Study)

International Nuclear Information System (INIS)

Ortholan, Cécile; Resbeut, Michel; Hannoun-Levi, Jean-Michel; Teissier, Eric; Gerard, Jean-Pierre; Ronchin, Philippe; Zaccariotto, Audrey; Minsat, Mathieu; Benezery, Karen; François, Eric; Salem, Naji; Ellis, Steve; Azria, David; Champetier, Cédric; Gross, Emmanuel; Cowen, Didier

2012-01-01

Purpose: To evaluate the benefit of prophylactic inguinal irradiation (PII) in anal canal squamous cell carcinoma (ASCC). Methods and Materials: This retrospective study analyzed the outcome of 208 patients presenting with ASCC treated between 2000 and 2004 in four cancer centers of the south of France. Results: The population study included 35 T1, 86 T2, 59 T3, 20 T4, and 8 T stage unknown patients. Twenty-seven patients presented with macroscopic inguinal node involvement. Of the 181 patients with uninvolved nodes at presentation, 75 received a PII to a total dose of 45–50 Gy (PII group) and 106 did not receive PII (no PII group). Compared with the no PII group, patients in the PII group were younger (60% vs. 41% of patients age 2 toxicity of the lower extremity was observed. Conclusion: PII with a dose of 45 Gy is safe and highly efficient to prevent inguinal recurrence and should be recommended for all T3-4 tumors. For early-stage tumors, PII should also be discussed, because the 5-year inguinal recurrence risk remains substantial when omitting PII (about 10%).

Immunomodulation of Host Chitinase 3-Like 1 During a Mammary Pathogenic Escherichia coli Infection

Directory of Open Access Journals (Sweden)

Koen Breyne

2018-05-01

Full Text Available Chitin is a N-acetyl-d-glucosamine biopolymer that can be recognized by chitin-binding proteins. Although mammals lack chitin synthase, they induce proteins responsible for detecting chitin in response to bacterial infections. Our aim was to investigate whether chitinase 3-like 1 (CHI3L1 has a potential role in the innate immunity of the Escherichia coli (E. coli infected mammary gland. CHI3L1 protein was found to be secreted in whey of naturally coliform-affected quarters compared to whey samples isolated from healthy udders. In addition, gene expression of CHI3L1 was confirmed in udder tissue of cows experimentally infected with a mammary pathogenic E. coli (MPEC strain. Despite the known anatomical differences, the bovine udders’ innate immune response was mimicked by applying an experimental mouse model using MPEC or non-MPEC isolates. The effect of CHI3L1 expression in the murine mammary gland in response to coliform bacteria was investigated through the use of CHI3L1−/− mice as well as through treatment with either a pan-caspase inhibitor or chitin particles in wild-type mice. The local induction of CHI3L1 postinfection with different E. coli strains was demonstrated to be independent of both bacterial growth and mammary interleukin (IL-8 levels. Indeed, CHI3L1 emerged as a regulator impacting on the transcytosis of Ly6G-positive cells from the interstitial space into the alveolar lumen of the mammary tissue. Furthermore, CHI3L1 was found to be upstream regulated by caspase activity and had a major downstream effect on the local pro-inflammatory cytokine profile, including IL-1beta, IL-6, and RANTES/CCL5. In conclusion, CHI3L1 was demonstrated to play a key role in the cytokine and caspase signaling during E. coli triggered inflammation of the mammary gland.

Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

NARCIS (Netherlands)

Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J.; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; van Minh, Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

2016-01-01

Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E.

Survival of pathogenic Escherichia coli on basil, lettuce, and spinach

Science.gov (United States)

The contamination of lettuce, spinach and basil with pathogenic E. coli has caused numerous illnesses over the past decade. E. coli O157:H7, E. coli O104:H4 and avian pathogenic E. coli (APECstx- and APECstx+) were inoculated on basil plants and in promix soiless substrate using drip and overhead ir...

Production of caffeoylmalic acid from glucose in engineered Escherichia coli.

Science.gov (United States)

Li, Tianzhen; Zhou, Wei; Bi, Huiping; Zhuang, Yibin; Zhang, Tongcun; Liu, Tao

2018-07-01

To achieve biosynthesis of caffeoylmalic acid from glucose in engineered Escherichia coli. We constructed the biosynthetic pathway of caffeoylmalic acid in E. coli by co-expression of heterologous genes RgTAL, HpaBC, At4CL2 and HCT2. To enhance the production of caffeoylmalic acid, we optimized the tyrosine metabolic pathway of E. coli to increase the supply of the substrate caffeic acid. Consequently, an E. coli-E. coli co-culture system was used for the efficient production of caffeoylmalic acid. The final titer of caffeoylmalic acid reached 570.1 mg/L. Microbial production of caffeoylmalic acid using glucose has application potential. In addition, microbial co-culture is an efficient tool for producing caffeic acid esters.

Characterization of Escherichia coli Phylogenetic Groups ...

African Journals Online (AJOL)

Background: Escherichia coli strains mainly fall into four phylogenetic groups (A, B1, B2, and D) and that virulent extra‑intestinal strains mainly belong to groups B2 and D. Aim: The aim was to determine the association between phylogenetic groups of E. coli causing extraintestinal infections (ExPEC) regarding the site of ...

Interaction of Escherichia coli with growing salad spinach plants.

Science.gov (United States)

Warriner, Keith; Ibrahim, Faozia; Dickinson, Matthew; Wright, Charles; Waites, William M

2003-10-01

In this study, the interaction of a bioluminescence-labeled Escherichia coli strain with growing spinach plants was assessed. Through bioluminescence profiles, the direct visualization of E. coli growing around the roots of developing seedlings was accomplished. Subsequent in situ glucuronidase (GUS) staining of seedlings confirmed that E. coli had become internalized within root tissue and, to a limited extent, within hypocotyls. When inoculated seeds were sown in soil microcosms and cultivated for 42 days, E. coli was recovered from the external surfaces of spinach roots and leaves as well as from surface-sterilized roots. When 20-day-old spinach seedlings (from uninoculated seeds) were transferred to soil inoculated with E. coli, the bacterium became established on the plant surface, but internalization into the inner root tissue was restricted. However, for seedlings transferred to a hydroponic system containing 10(2) or 10(3) CFU of E. coli per ml of the circulating nutrient solution, the bacterium was recovered from surface-sterilized roots, indicating that it had been internalized. Differences between E. coli interactions in the soil and those in the hydroponic system may be attributed to greater accessibility of the roots in the latter model. Alternatively, the presence of a competitive microflora in soil may have restricted root colonization by E. coli. The implications of this study's findings with regard to the microbiological safety of minimally processed vegetables are discussed.

A scoping study on the prevalence of Escherichia coli and ...

African Journals Online (AJOL)

In the Eastern Cape Province E. coli and enterococci were detected in 7 and 4 of the 15 RHRW tanks, respectively. Enterococci were detected only from one river whereas E. coli was detected in all three rivers; in spring water neither enterococci nor E. coli were detected. Samples from GRWH tanks were positive for E. coli ...

Vulnerability- and Diversity-Aware Anonymization of Personally Identifiable Information for Improving User Privacy and Utility of Publishing Data

Science.gov (United States)

Majeed, Abdul; Ullah, Farman; Lee, Sungchang

2017-01-01

Personally identifiable information (PII) affects individual privacy because PII combinations may yield unique identifications in published data. User PII such as age, race, gender, and zip code contain private information that may assist an adversary in determining the user to whom such information relates. Each item of user PII reveals identity differently, and some types of PII are highly identity vulnerable. More vulnerable types of PII enable unique identification more easily, and their presence in published data increases privacy risks. Existing privacy models treat all types of PII equally from an identity revelation point of view, and they mainly focus on hiding user PII in a crowd of other users. Ignoring the identity vulnerability of each type of PII during anonymization is not an effective method of protecting user privacy in a fine-grained manner. This paper proposes a new anonymization scheme that considers the identity vulnerability of PII to effectively protect user privacy. Data generalization is performed adaptively based on the identity vulnerability of PII as well as diversity to anonymize data. This adaptive generalization effectively enables anonymous data, which protects user identity and private information disclosures while maximizing the utility of data for performing analyses and building classification models. Additionally, the proposed scheme has low computational overheads. The simulation results show the effectiveness of the scheme and verify the aforementioned claims. PMID:28481298

Vulnerability- and Diversity-Aware Anonymization of Personally Identifiable Information for Improving User Privacy and Utility of Publishing Data

Directory of Open Access Journals (Sweden)

Abdul Majeed

2017-05-01

Full Text Available Personally identifiable information (PII affects individual privacy because PII combinations may yield unique identifications in published data. User PII such as age, race, gender, and zip code contain private information that may assist an adversary in determining the user to whom such information relates. Each item of user PII reveals identity differently, and some types of PII are highly identity vulnerable. More vulnerable types of PII enable unique identification more easily, and their presence in published data increases privacy risks. Existing privacy models treat all types of PII equally from an identity revelation point of view, and they mainly focus on hiding user PII in a crowd of other users. Ignoring the identity vulnerability of each type of PII during anonymization is not an effective method of protecting user privacy in a fine-grained manner. This paper proposes a new anonymization scheme that considers the identity vulnerability of PII to effectively protect user privacy. Data generalization is performed adaptively based on the identity vulnerability of PII as well as diversity to anonymize data. This adaptive generalization effectively enables anonymous data, which protects user identity and private information disclosures while maximizing the utility of data for performing analyses and building classification models. Additionally, the proposed scheme has low computational overheads. The simulation results show the effectiveness of the scheme and verify the aforementioned claims.

Asymptomatic bacteriuria Escherichia coli are live biotherapeutics for UTI.

Science.gov (United States)

Rudick, Charles N; Taylor, Aisha K; Yaggie, Ryan E; Schaeffer, Anthony J; Klumpp, David J

2014-01-01

Urinary tract infections (UTI) account for approximately 8 million clinic visits annually with symptoms that include acute pelvic pain, dysuria, and irritative voiding. Empiric UTI management with antimicrobials is complicated by increasing antimicrobial resistance among uropathogens, but live biotherapeutics products (LBPs), such as asymptomatic bacteriuria (ASB) strains of E. coli, offer the potential to circumvent antimicrobial resistance. Here we evaluated ASB E. coli as LBPs, relative to ciprofloxacin, for efficacy against infection and visceral pain in a murine UTI model. Visceral pain was quantified as tactile allodynia of the pelvic region in response to mechanical stimulation with von Frey filaments. Whereas ciprofloxacin promoted clearance of uropathogenic E. coli (UPEC), it did not reduce pelvic tactile allodynia, a measure of visceral pain. In contrast, ASB E. coli administered intravesically or intravaginally provided comparable reduction of allodynia similar to intravesical lidocaine. Moreover, ASB E. coli were similarly effective against UTI allodynia induced by Proteus mirabilis, Enterococccus faecalis and Klebsiella pneumoniae. Therefore, ASB E. coli have anti-infective activity comparable to the current standard of care yet also provide superior analgesia. These studies suggest that ASB E. coli represent novel LBPs for UTI symptoms.

Modeling the inactivation of Escherichia coli 0157:H7 and uropathogenic E.coli in ground chicken by high pressure processing and thymol

Science.gov (United States)

Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compare the resistance of iPEC (O157:H7) to UPEC in chicken meat using High Pressure Processing...

Modeling the inactivatin of Escherichia coli 0157:H7 and uropathogenic E. coli in ground beef by high pressure processing and citral

Science.gov (United States)

Disease causing Escherichia coli commonly found in meat and poultry include intestinal pathogenic E. coli (iPEC) as well as extraintestinal types such as the Uropathogenic E. coli (UPEC). In this study we compared the resistance of iPEC (O157:H7) to UPEC in ground beef using High Pressure Processing...

Complete Genome Sequence of Escherichia coli Strain WG5

DEFF Research Database (Denmark)

Imamovic, Lejla; Misiakou, Maria-Anna; van der Helm, Eric

2018-01-01

Escherichia coli strain WG5 is a widely used host for phage detection, including somatic coliphages employed as standard ISO method 10705-1 (2000). Here, we present the complete genome sequence of a commercial E. coli WG5 strain.......Escherichia coli strain WG5 is a widely used host for phage detection, including somatic coliphages employed as standard ISO method 10705-1 (2000). Here, we present the complete genome sequence of a commercial E. coli WG5 strain....

Environmental Escherichia coli: Ecology and public health implications - A review

Science.gov (United States)

Jang, Jeonghwan; Hur, Hor-Gil; Sadowsky, Michael J.; Byappanahalli, Muruleedhara; Yan, Tao; Ishii, Satoshi

2017-01-01

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed.

Expression optimization and biochemical characterization of a recombinant gamma-glutamyltranspeptidase from Escherichia coli novablue.

Science.gov (United States)

Yao, Ya-Feng; Weng, Yih-Ming; Hu, Hui-Yu; Ku, Kuo-Lung; Lin, Long-Liu

2006-09-01

A truncated Escherichia coli Novablue gamma-glutamyltranspeptidase (EcGGT) gene lacking the first 48-bp coding sequence for part of the signal sequence was amplified by polymerase chain reaction and cloned into expression vector pQE-30 to generate pQE-EcGGT. The maximum production of His(6)-tagged enzyme by E. coli M15 (pQE-EcGGT) was achieved with 0.1 mM IPTG induction for 12 h at 20 degrees C. The overexpressed enzyme was purified to homogeneity by nickel-chelate chromatography to a specific transpeptidase activity of 4.25 U/mg protein and a final yield of 83%. The molecular masses of the subunits of the purified enzyme were estimated to be 41 and 21 kDa respectively by SDS-PAGE, indicating EcGGT still undergoes the post-translational cleavage even in the truncation of signal sequence. The optimum temperature and pH for the recombinant enzyme were 40 degrees C and 9, respectively. The apparent K (m) and V (max) values for gamma-glutamyl-p-nitroanilide as gamma-glutamyl donor in the transpeptidation reaction were 37.9 microM and 53.7 x 10(-3) mM min(-1), respectively. The synthesis of L -theanine was performed in a reaction mixture containing 10 mM L -Gln, 40 mM ethylamine, and 1.04 U His(6)-tagged EcGGT/ml, pH 10, and a conversion rate of 45% was obtained.

Neonatal infections caused by Escherichia coli at the National ...

African Journals Online (AJOL)

Background: Escherichia coli (E.coli) has been implicated as a common cause of both early and late onset neonatal infections. The emergence of different strains of E.coli that are multiply resistant to commonly used antibiotics has made continuous antibiotics surveillance relevant. Knowledge about common infections ...

neonatal infections caused by escherichia coli at the national

African Journals Online (AJOL)

boaz

Background: Escherichia coli (E.coli) has been implicated as a common cause of both early and late onset neonatal infections. The emergence of different strains of E.coli that are multiply resistant to commonly used antibiotics has made continuous antibiotics surveillance relevant. Knowledge about common infections ...

Molecular prophage typing of avian pathogenic Escherichia coli.

Science.gov (United States)

Kwon, Hyuk-Joon; Seong, Won-Jin; Kim, Jae-Hong

2013-03-23

Escherichia coli prophages confer virulence and resistance to physico-chemical, nutritional, and antibiotic stresses on their hosts, and they enhance the evolution of E. coli. Thus, studies on profiles of E. coli prophages are valuable to understand the population structure and evolution of E. coli pathogenicity. Large terminase genes participate in phage genome packaging and are one of the cornerstones for the identification of prophages. Thus, we designed primers to detect 16 types of large terminase genes and analyzed the genomes of 48 E. coli and Shigella reference strains for the prophage markers. We also investigated the distribution of the 16 prophage markers among 92 avian pathogenic E. coli (APEC) strains. APEC strains were classified into 61 prophage types (PPTs). Each strain was different from the reference strains as measured by the PPTs and from the frequency of each prophage marker. Investigation of the distribution of prophage-related serum resistance (bor), toxin (stx1 and cdtI), and T3SS effector (lom, espK, sopE, nleB, and ospG) genes revealed the presence of bor (44.1%), lom (95.5%) and cdtI (9.1%) in APEC strains with related prophages. Therefore, the molecular prophage typing method may be useful to understand population structure and evolution of E. coli pathogenicity, and further studies on the mobility of the prophages and the roles of virulence genes in APEC pathogenicity may be valuable. Copyright © 2012 Elsevier B.V. All rights reserved.

Induced clustering of Escherichia coli by acoustic fields.

Science.gov (United States)

Gutiérrez-Ramos, Salomé; Hoyos, Mauricio; Ruiz-Suárez, J C

2018-03-16

Brownian or self-propelled particles in aqueous suspensions can be trapped by acoustic fields generated by piezoelectric transducers usually at frequencies in the megahertz. The obtained confinement allows the study of rich collective behaviours like clustering or spreading dynamics in microgravity-like conditions. The acoustic field induces the levitation of self-propelled particles and provides secondary lateral forces to capture them at nodal planes. Here, we give a step forward in the field of confined active matter, reporting levitation experiments of bacterial suspensions of Escherichia coli. Clustering of living bacteria is monitored as a function of time, where different behaviours are clearly distinguished. Upon the removal of the acoustic signal, bacteria rapidly spread, impelled by their own swimming. Nevertheless, long periods of confinement result in irreversible bacteria entanglements that could act as seeds for levitating bacterial aggregates.

Cryo-EM structure of the E. coli translating ribosome in complex with SRP and its receptor

Science.gov (United States)

Estrozi, Leandro F.; Boehringer, Daniel; Shan, Shu-ou; Ban, Nenad; Schaffitzel, Christiane

2013-01-01

We report the early conformation of the E. coli signal recognition particle (SRP) and its receptor FtsY bound to the translating ribosome by cryo-electron microscopy. FtsY binds to the tetraloop of the SRP RNA whereas the NG-domains of the SRP protein and FtsY interact weakly in this conformation. Our results suggest that optimal positioning of the SRP RNA tetraloop and the Ffh NG-domain leads to FtsY recruitment. PMID:21151118

Non-Escherichia coli versus Escherichia coli community-acquired urinary tract infections in children hospitalized in a tertiary center: relative frequency, risk factors, antimicrobial resistance and outcome.

Science.gov (United States)

Marcus, Nir; Ashkenazi, Shai; Yaari, Arnon; Samra, Zmira; Livni, Gilat

2005-07-01

Currently hospitalization for children with urinary tract infections (UTIs) is reserved for severe or complicated cases. Changes may have taken place in the characteristics and causative uropathogens of hospital-treated community-acquired UTI. To study children hospitalized in a tertiary center with community-acquired UTI, compare Escherichia coli and non-E. coli UTI, define predictors for non-E. coli UTI and elucidate the appropriate therapeutic approach. A prospective clinical and laboratory study from 2001 through 2002 in a tertiary pediatric medical center. Patients were divided by results of the urine culture into E. coli and non-E. coli UTI groups, which were compared. Of 175 episodes of culture-proved UTI, 70 (40%) were caused by non-E. coli pathogens. Non-E. coli UTI was more commonly found in children who were male (P = 0.005), who had underlying renal abnormalities (P = 0.0085) and who had received antibiotic therapy in the prior month (P = 0.0009). Non-E. coli uropathogens were often resistant to antibiotics usually recommended for initial therapy for UTI, including cephalosporins and aminoglycosides; 19% were initially treated with inappropriate empiric intravenous antibiotics (compared with 2% for E. coli UTI, P = 0.0001), with a longer hospitalization. Current treatment routines are often inappropriate for hospitalized children with non-E. coli UTI, which is relatively common in this population. The defined risk factors associated with non-E. coli UTIs and its antimicrobial resistance patterns should be considered to improve empiric antibiotic therapy for these infections.

Pulsed-Plasma Disinfection of Water Containing Escherichia coli

Science.gov (United States)

Satoh, Kohki; MacGregor, Scott J.; Anderson, John G.; Woolsey, Gerry A.; Fouracre, R. Anthony

2007-03-01

The disinfection of water containing the microorganism, Escherichia coli (E. coli) by exposure to a pulsed-discharge plasma generated above the water using a multineedle electrode (plasma-exposure treatment), and by sparging the off-gas of the pulsed plasma into the water (off-gas-sparging treatment), is performed in the ambient gases of air, oxygen, and nitrogen. For the off-gas-sparging treatment, bactericidal action is observed only when oxygen is used as the ambient gas, and ozone is found to generate the bactericidal action. For the plasma-exposure treatment, the density of E. coli bacteria decreases exponentially with plasma-exposure time for all the ambient gases. It may be concluded that the main contributors to E. coli inactivation are particle species produced by the pulsed plasma. For the ambient gases of air and nitrogen, the influence of acidification of the water in the system, as a result of pulsed-plasma exposure, may also contribute to the decay of E. coli density.

Graphene-interfaced electrical biosensor for label-free and sensitive detection of foodborne pathogenic E. coli O157:H7.

Science.gov (United States)

Pandey, Ashish; Gurbuz, Yasar; Ozguz, Volkan; Niazi, Javed H; Qureshi, Anjum

2017-05-15

E. coli O157:H7 is an enterohemorrhagic bacteria responsible for serious foodborne outbreaks that causes diarrhoea, fever and vomiting in humans. Recent foodborne E. coli outbreaks has left a serious concern to public health. Therefore, there is an increasing demand for a simple, rapid and sensitive method for pathogen detection in contaminated foods. In this study, we developed a label-free electrical biosensor interfaced with graphene for sensitive detection of pathogenic bacteria. This biosensor was fabricated by interfacing graphene with interdigitated microelectrodes of capacitors that were biofunctionalized with E. coli O157:H7 specific antibodies for sensitive pathogenic bacteria detection. Here, graphene nanostructures on the sensor surface provided superior chemical properties such as high carrier mobility and biocompatibility with antibodies and bacteria. The sensors transduced the signal based on changes in dielectric properties (capacitance) through (i) polarization of captured cell-surface charges, (ii) cells' internal bioactivity, (iii) cell-wall's electronegativity or dipole moment and their relaxation and (iv) charge carrier mobility of graphene that modulated the electrical properties once the pathogenic E. coli O157:H7 captured on the sensor surface. Sensitive capacitance changes thus observed with graphene based capacitors were specific to E. coli O157:H7 strain with a sensitivity as low as 10-100 cells/ml. The proposed graphene based electrical biosensor provided advantages of speed, sensitivity, specificity and in-situ bacterial detection with no chemical mediators, represents a versatile approach for detection of a wide variety of other pathogens. Copyright © 2016 Elsevier B.V. All rights reserved.

Increased multi-drug resistant Escherichia coli from hospitals in ...

African Journals Online (AJOL)

Background: Multidrug-resistant Escherichia coli (MDR E. coli) has become a major public health concern in Sudan and many countries, causing failure in treatment with consequent huge health burden. Objectives: To determine the prevalence and susceptibility of MDR E. coli isolated from patients in hospitals at Khartoum ...

Isolation, molecular cloning and expression of cellobiohydrolase B (CbhB) from Aspergillus niger in Escherichia coli

International Nuclear Information System (INIS)

Woon, J. S. K.; Murad, A. M. A.; Abu Bakar, F. D.

2015-01-01

A cellobiohydrolase B (CbhB) from Aspergillus niger ATCC 10574 was cloned and expressed in E. coli. CbhB has an open reading frame of 1611 bp encoding a putative polypeptide of 536 amino acids. Analysis of the encoded polypeptide predicted a molecular mass of 56.2 kDa, a cellulose binding module (CBM) and a catalytic module. In order to obtain the mRNA of cbhB, total RNA was extracted from A. niger cells induced by 1% Avicel. First strand cDNA was synthesized from total RNA via reverse transcription. The full length cDNA of cbhB was amplified by PCR and cloned into the cloning vector, pGEM-T Easy. A comparison between genomic DNA and cDNA sequences of cbhB revealed that the gene is intronless. Upon the removal of the signal peptide, the cDNA of cbhB was cloned into the expression vector pET-32b. However, the recombinant CbhB was expressed in Escherichia coli Origami DE3 as an insoluble protein. A homology model of CbhB predicted the presence of nine disulfide bonds in the protein structure which may have contributed to the improper folding of the protein and thus, resulting in inclusion bodies in E. coli

Isolation, molecular cloning and expression of cellobiohydrolase B (CbhB) from Aspergillus niger in Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Woon, J. S. K., E-mail: jameswoon@siswa.ukm.edu.my; Murad, A. M. A., E-mail: munir@ukm.edu.my; Abu Bakar, F. D., E-mail: fabyff@ukm.edu.my [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2015-09-25

A cellobiohydrolase B (CbhB) from Aspergillus niger ATCC 10574 was cloned and expressed in E. coli. CbhB has an open reading frame of 1611 bp encoding a putative polypeptide of 536 amino acids. Analysis of the encoded polypeptide predicted a molecular mass of 56.2 kDa, a cellulose binding module (CBM) and a catalytic module. In order to obtain the mRNA of cbhB, total RNA was extracted from A. niger cells induced by 1% Avicel. First strand cDNA was synthesized from total RNA via reverse transcription. The full length cDNA of cbhB was amplified by PCR and cloned into the cloning vector, pGEM-T Easy. A comparison between genomic DNA and cDNA sequences of cbhB revealed that the gene is intronless. Upon the removal of the signal peptide, the cDNA of cbhB was cloned into the expression vector pET-32b. However, the recombinant CbhB was expressed in Escherichia coli Origami DE3 as an insoluble protein. A homology model of CbhB predicted the presence of nine disulfide bonds in the protein structure which may have contributed to the improper folding of the protein and thus, resulting in inclusion bodies in E. coli.

Isolation, molecular cloning and expression of cellobiohydrolase B (CbhB) from Aspergillus niger in Escherichia coli

Science.gov (United States)

Woon, J. S. K.; Murad, A. M. A.; Abu Bakar, F. D.

2015-09-01

A cellobiohydrolase B (CbhB) from Aspergillus niger ATCC 10574 was cloned and expressed in E. coli. CbhB has an open reading frame of 1611 bp encoding a putative polypeptide of 536 amino acids. Analysis of the encoded polypeptide predicted a molecular mass of 56.2 kDa, a cellulose binding module (CBM) and a catalytic module. In order to obtain the mRNA of cbhB, total RNA was extracted from A. niger cells induced by 1% Avicel. First strand cDNA was synthesized from total RNA via reverse transcription. The full length cDNA of cbhB was amplified by PCR and cloned into the cloning vector, pGEM-T Easy. A comparison between genomic DNA and cDNA sequences of cbhB revealed that the gene is intronless. Upon the removal of the signal peptide, the cDNA of cbhB was cloned into the expression vector pET-32b. However, the recombinant CbhB was expressed in Escherichia coli Origami DE3 as an insoluble protein. A homology model of CbhB predicted the presence of nine disulfide bonds in the protein structure which may have contributed to the improper folding of the protein and thus, resulting in inclusion bodies in E. coli.

Insights into the evolution of pathogenicity of Escherichia coli from genomic analysis of intestinal E. coli of Marmota himalayana in Qinghai-Tibet plateau of China.

Science.gov (United States)

Lu, Shan; Jin, Dong; Wu, Shusheng; Yang, Jing; Lan, Ruiting; Bai, Xiangning; Liu, Sha; Meng, Qiong; Yuan, Xuejiao; Zhou, Juan; Pu, Ji; Chen, Qiang; Dai, Hang; Hu, Yuanyuan; Xiong, Yanwen; Ye, Changyun; Xu, Jianguo

2016-12-07

Escherichia coli is both of a widespread harmless gut commensal and a versatile pathogen of humans. Domestic animals are a well-known reservoir for pathogenic E. coli. However, studies of E. coli populations from wild animals that have been separated from human activities had been very limited. Here we obtained 580 isolates from intestinal contents of 116 wild Marmot Marmota himalayana from Qinghai-Tibet plateau, China, with five isolates per animal. We selected 125 (hereinafter referred to as strains) from the 580 isolates for genome sequencing, based on unique pulse field gel electrophoresis patterns and at least one isolate per animal. Whole genome sequence analysis revealed that all 125 strains carried at least one and the majority (79.2%) carried multiple virulence genes based on the analysis of 22 selected virulence genes. In particular, the majority of the strains carried virulence genes from different pathovars as potential 'hybrid pathogens'. The alleles of eight virulence genes from the Marmot E. coli were found to have diverged earlier than all known alleles from human and other animal E. coli. Phylogenetic analysis of the 125 Marmot E. coli genomes and 355 genomes selected from 1622 human and other E. coli strains identified two new phylogroups, G and H, both of which diverged earlier than the other phylogroups. Eight of the 12 well-known pathogenic E. coli lineages were found to share a most recent common ancestor with one or more Marmot E. coli strains. Our results suggested that the intestinal E. coli of the Marmots contained a diverse virulence gene pool and is potentially pathogenic to humans. These findings provided a new understanding of the evolutionary origin of pathogenic E. coli.

Ischemic colitis or melanosis coli: a case report

Directory of Open Access Journals (Sweden)

Nadeem Mohammed

2007-09-01

Full Text Available Abstract Background Melanosis Coli is described as black or brown discolouration of the mucosa of the colon. Its a benign condition, which arises from anthraquinone laxative abuse and has no symptoms of its own. The main importance of diagnosing Melanosis Coli correctly lies in the fact that if its extensive, there may be difficulty in differentiating it from ischemic colitis. Case presentation We present a case of extensive Melanosis Coli involving the whole of large bowel that appeared gangrenous. A sub total colectomy was performed on presumed diagnosis of ischemic bowel. Conclusion This report reminds the clinicians that extensive Melanosis Coli may mimic ischemic colitis and thus must be considered as a differential diagnosis.

The interaction of the protein lysozyme with bacteria E. coli observed using nanodiamond labelling

International Nuclear Information System (INIS)

Perevedentseva, Elena; Cheng, C-Y; Chung, P-H; Tu, J-S; Hsieh, Y-H; Cheng, C-L

2007-01-01

The application of a nanometre-sized diamond in Raman-detectable biolabelling is demonstrated in this study. The interaction of a lysozyme-nanodiamond complex with bacteria E. coli was observed via Raman mapping using the diamond Raman signal as the labelling marker. The results are compared with scanning electron microscope observations, and the adsorbed lysozyme's functionality is analysed. High antibacterial activity of lysozyme-nanodiamond complex was observed, equivalent to active lysozyme in solution. The results suggest that nanodiamond labelling can be effective and that it can be applied in ambient conditions without complicated sample pre-treatments

Escherichia Coli

Science.gov (United States)

Goodsell, David S.

2009-01-01

Diverse biological data may be used to create illustrations of molecules in their cellular context. I describe the scientific results that support a recent textbook illustration of an "Escherichia coli cell". The image magnifies a portion of the bacterium at one million times, showing the location and form of individual macromolecules. Results…

Transcriptomic analysis displays the effect of (-)-roemerine on the motility and nutrient uptake in Escherichia coli.

Science.gov (United States)

Ayyildiz, Dilara; Arga, Kazim Yalcin; Avci, Fatma Gizem; Altinisik, Fatma Ece; Gurer, Caglayan; Gulsoy Toplan, Gizem; Kazan, Dilek; Wozny, Katharina; Brügger, Britta; Mertoglu, Bulent; Sariyar Akbulut, Berna

2017-08-01

Among the different families of plant alkaloids, (-)-roemerine, an aporphine type, was recently shown to possess significant antibacterial activity in Escherichia coli. Based on the increasing demand for antibacterials with novel mechanisms of action, the present work investigates the potential of the plant-derived alkaloid (-)-roemerine as an antibacterial in E. coli cells using microarray technology. Analysis of the genome-wide transcriptional reprogramming in cells after 60 min treatment with 100 μg/mL (-)-roemerine showed significant changes in the expression of 241 genes (p value 2). Expression of selected genes was confirmed by qPCR. Differentially expressed genes were classified into functional categories to map biological processes and molecular pathways involved. Cellular activities with roles in carbohydrate transport and metabolism, energy production and conversion, lipid transport and metabolism, amino acid transport and metabolism, two-component signaling systems, and cell motility (in particular, the flagellar organization and motility) were among metabolic processes altered in the presence of (-)-roemerine. The down-regulation of the outer membrane proteins probably led to a decrease in carbohydrate uptake rate, which in turn results in nutrient limitation. Consequently, energy metabolism is slowed down. Interestingly, the majority of the expressional alterations were found in the flagellar system. This suggested reduction in motility and loss in the ability to form biofilms, thus affecting protection of E. coli against host cell defense mechanisms. In summary, our findings suggest that the antimicrobial action of (-)-roemerine in E. coli is linked to disturbances in motility and nutrient uptake.

Presence of non-O157 Shiga toxin-producing Escherichia coli, enterotoxigenic E. coli, enteropathogenic E. coli and Salmonella in fresh beetroot (Beta vulgaris L.) juice from public markets in Mexico.

Science.gov (United States)

Gómez-Aldapa, Carlos A; Rangel-Vargas, Esmeralda; Bautista-De León, Haydee; Castro-Rosas, Javier

2014-10-01

Unpasteurized juice has been associated with foodborne illness outbreaks for many years. Beetroot is a vegetable grown all over the world in temperate areas. In Mexico beetroot is consumed cooked in salads or raw as fresh unpasteurized juices. No data about the microbiological quality or safety of unpasteurized beetroot juices are available. Indicator bacteria, diarrheagenic Escherichia coli pathotypes (DEP) and Salmonella frequencies were determined for fresh unpasteurized beetroot juice from restaurants. One hundred unpasteurized beetroot juice samples were collected from public markets in Pachuca, Mexico. Frequencies in these samples were 100%, 75%, 53%, 9% and 4% of positive samples, for coliform bacteria, fecal coliforms, E. coli, DEP and Salmonella, respectively. Identified DEP included enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC) and non-O157 Shiga toxin-producing E. coli (STEC). Identified Salmonella serotypes included Typhimurium and Enteritidis. This is the first report of microbiological quality and atypical EPEC, ETEC, non-O157 STEC and Salmonella isolation from fresh raw beetroot juice in Mexico. Fresh raw beetroot juice from markets is very probably an important factor contributing to the endemicity of atypical EPEC, ETEC, non-O157 STEC and Salmonella-related gastroenteritis in Mexico. © 2014 Society of Chemical Industry.

Escherichia coli survival in waters: Temperature dependence

Science.gov (United States)

Knowing the survival rates of water-borne Escherichia coli is important in evaluating microbial contamination and making appropriate management decisions. E. coli survival rates are dependent on temperature, a dependency that is routinely expressed using an analogue of the Q10 mo...

Environmental Escherichia coli: ecology and public health implications-a review.

Science.gov (United States)

Jang, J; Hur, H-G; Sadowsky, M J; Byappanahalli, M N; Yan, T; Ishii, S

2017-09-01

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae. The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through faeces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent faecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extraintestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a faecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics revealed the diversity and complexity of E. coli strains in various environments, which are affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments with regard to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia. The impact of environmental E. coli on water quality and public health is also discussed. © 2017 The Society for Applied Microbiology.

Fecal colonization with P-fimbriated Escherichia coli in newborn children and relation to development of extraintestinal E. coli infections.

Science.gov (United States)

Tullus, K

1987-01-01

The incidence of E. coli pyelonephritis before the age of one year among the children born at Danderyd Hospital during a ten year period was studied. During the study period, 4 or 5 outbreaks of E. coli pyelonephritis occurred among the children who had previously been staying in the hospital's neonatal ward. These outbreaks seemed to have been caused by nosocomial spread of and fecal colonization with certain virulent E. coli strains among the children staying in the ward during certain periods of time. The strains that were spread in the ward seemed to belong to certain pyelonephritogenic E. coli clones of the serotypes O6:K5, O4:K3 and possibly O6:K2. Although the children became fecally colonized with the strains in the neonatal ward, most fell ill some time after they had left the ward. The mean age at the development of their first pyelonephritis was 3.4 months for the boys and 6.2 months for the girls, who had been cared for in this ward. A correlation between the number of infections and the bed occupancy of the ward could be found (p less than 0.01). The risk for a child staying in the ward during an outbreak to develop pyelonephritis was about 5-10%. There was a baseline incidence rate of 0.6-0.7% during non-epidemic periods. During one of the outbreaks there was also an increased incidence rate of E. coli septicemia among the children staying in the neonatal ward. The predictive value of fecal colonization with P-fimbriated E. coli for the later development of extraintestinal E. coli infections was studied in a 2.5 year prospective study. During this study period there was a baseline incidence rate of 10-20% fecal colonization with P-fimbriated E. coli among the children staying in both the neonatal and maternity wards, interrupted only by minor peaks of colonization with such strains. Length of stay in the neonatal ward and a high bed occupancy of the neonatal ward were statistically correlated to fecal colonization with P-fimbriated E. coli strains (p

Ontology-based literature mining of E. coli vaccine-associated gene interaction networks.

Science.gov (United States)

Hur, Junguk; Özgür, Arzucan; He, Yongqun

2017-03-14

Pathogenic Escherichia coli infections cause various diseases in humans and many animal species. However, with extensive E. coli vaccine research, we are still unable to fully protect ourselves against E. coli infections. To more rational development of effective and safe E. coli vaccine, it is important to better understand E. coli vaccine-associated gene interaction networks. In this study, we first extended the Vaccine Ontology (VO) to semantically represent various E. coli vaccines and genes used in the vaccine development. We also normalized E. coli gene names compiled from the annotations of various E. coli strains using a pan-genome-based annotation strategy. The Interaction Network Ontology (INO) includes a hierarchy of various interaction-related keywords useful for literature mining. Using VO, INO, and normalized E. coli gene names, we applied an ontology-based SciMiner literature mining strategy to mine all PubMed abstracts and retrieve E. coli vaccine-associated E. coli gene interactions. Four centrality metrics (i.e., degree, eigenvector, closeness, and betweenness) were calculated for identifying highly ranked genes and interaction types. Using vaccine-related PubMed abstracts, our study identified 11,350 sentences that contain 88 unique INO interactions types and 1,781 unique E. coli genes. Each sentence contained at least one interaction type and two unique E. coli genes. An E. coli gene interaction network of genes and INO interaction types was created. From this big network, a sub-network consisting of 5 E. coli vaccine genes, including carA, carB, fimH, fepA, and vat, and 62 other E. coli genes, and 25 INO interaction types was identified. While many interaction types represent direct interactions between two indicated genes, our study has also shown that many of these retrieved interaction types are indirect in that the two genes participated in the specified interaction process in a required but indirect process. Our centrality analysis of

Melanosis coli in patients with colon cancer

Directory of Open Access Journals (Sweden)

Dorota Biernacka-Wawrzonek

2016-12-01

Full Text Available Intoduction: Melanosis coli is a benign lesion affecting the mucosa of the large intestine. There is a relationship between the presence of melanosis and anthraquinone laxative use. Melanosis coli is also observed in patients with colon cancer, but there is doubt whether these two conditions are related. Aim : To analyze the correlation between melanosis and colon cancer. Material and methods: We analyzed retrospectively 436 patients undergoing colon cancer surgery. There were 246 women and 190 men. Patients were divided into three age groups: under 50 years, between 51 and 65 years, and over 66 years. We analyzed sections of the cancer and intestinal mucosa from the tumor’s proximal (2–5 cm and distal (8–10 cm zone. Results : Melanosis coli was present in 52 patients, which represents 11.9% of patients with colon cancer. More often it was present in women. The most common location of melanosis and colon cancer was the terminal part of the large intestine. In patients below 50 years of age in both sexes melanosis coli did not occur. In men, melanosis was more common in the age group over 66 years. Intensity of pigmentation was higher in the tumor’s distal zone. Conclusions : The incidence of melanosis coli increases with age, similar to that of colon cancer. Melanosis was not present inside tumors, in almost half of the cases it was not present in the proximal zone, and the degree of pigmentation increased in distal zone. The cause-effect relationship between melanosis coli and colon cancer remains uncertain.

No evidence for a bovine mastitis Escherichia coli pathotype.

Science.gov (United States)

Leimbach, Andreas; Poehlein, Anja; Vollmers, John; Görlich, Dennis; Daniel, Rolf; Dobrindt, Ulrich

2017-05-08

Escherichia coli bovine mastitis is a disease of significant economic importance in the dairy industry. Molecular characterization of mastitis-associated E. coli (MAEC) did not result in the identification of common traits. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype has been proposed suggesting virulence traits that differentiate MAEC from commensal E. coli. The present study was designed to investigate the MPEC pathotype hypothesis by comparing the genomes of MAEC and commensal bovine E. coli. We sequenced the genomes of eight E. coli isolated from bovine mastitis cases and six fecal commensal isolates from udder-healthy cows. We analyzed the phylogenetic history of bovine E. coli genomes by supplementing this strain panel with eleven bovine-associated E. coli from public databases. The majority of the isolates originate from phylogroups A and B1, but neither MAEC nor commensal strains could be unambiguously distinguished by phylogenetic lineage. The gene content of both MAEC and commensal strains is highly diverse and dominated by their phylogenetic background. Although individual strains carry some typical E. coli virulence-associated genes, no traits important for pathogenicity could be specifically attributed to MAEC. Instead, both commensal strains and MAEC have very few gene families enriched in either pathotype. Only the aerobactin siderophore gene cluster was enriched in commensal E. coli within our strain panel. This is the first characterization of a phylogenetically diverse strain panel including several MAEC and commensal isolates. With our comparative genomics approach we could not confirm previous studies that argue for a positive selection of specific traits enabling MAEC to elicit bovine mastitis. Instead, MAEC are facultative and opportunistic pathogens recruited from the highly diverse bovine gastrointestinal microbiota. Virulence-associated genes implicated in mastitis are a by-product of commensalism with the primary function

The role of Cra in regulating acetate excretion and osmotic tolerance in E. coli K-12 and E. coli B at high density growth.

Science.gov (United States)

Son, Young-Jin; Phue, Je-Nie; Trinh, Loc B; Lee, Sang Jun; Shiloach, Joseph

2011-06-30

E. coli B (BL21), unlike E.coli K-12 (JM109) is insensitive to glucose concentration and, therefore, grows faster and produces less acetate than E. coli K-12, especially when growing to high cell densities at high glucose concentration. By performing genomic analysis, it was demonstrated that the cause of this difference in sensitivity to the glucose concentration is the result of the differences in the central carbon metabolism activity. We hypothesized that the global transcription regulator Cra (FruR) is constitutively expressed in E. coli B and may be responsible for the different behaviour of the two strains. To investigate this possibility and better understand the function of Cra in the two strains, cra - negative E. coli B (BL21) and E. coli K-12 (JM109) were prepared and their growth behaviour and gene expression at high glucose were evaluated using microarray and real-time PCR. The deletion of the cra gene in E. coli B (BL21) minimally affected the growth and maximal acetate accumulation, while the deletion of the same gene in E.coli K-12 (JM109) caused the cells to stop growing as soon as acetate concentration reached 6.6 g/L and the media conductivity reached 21 mS/cm. ppsA (gluconeogenesis gene), aceBA (the glyoxylate shunt genes) and poxB (the acetate producing gene) were down-regulated in both strains, while acs (acetate uptake gene) was down-regulated only in E.coli B (BL21). These transcriptional differences had little effect on acetate and pyruvate production. Additionally, it was found that the lower growth of E. coli K-12 (JM109) strain was the result of transcription inhibition of the osmoprotectant producing bet operon (betABT). The transcriptional changes caused by the deletion of cra gene did not affect the activity of the central carbon metabolism, suggesting that Cra does not act alone; rather it interacts with other pleiotropic regulators to create a network of metabolic effects. An unexpected outcome of this work is the finding that cra

Comparison of 61 Sequenced Escherichia coli Genomes

DEFF Research Database (Denmark)

Lukjancenko, Oksana; Wassenaar, T. M.; Ussery, David

2010-01-01

Escherichia coli is an important component of the biosphere and is an ideal model for studies of processes involved in bacterial genome evolution. Sixty-one publically available E. coli and Shigella spp. sequenced genomes are compared, using basic methods to produce phylogenetic and proteomics...

lactamase in clinical isolates of Escherichia coli

African Journals Online (AJOL)

Jane

2011-08-22

Aug 22, 2011 ... The beta lactamase enzyme producing E. coli, resistant to β-lactam antibiotics, created many problems ... Key words: Escherichia coli, β-lactamase enzymes, TEM-type extended spectrum ... difficulties in treatment using antibiotics that are currently ... and chloramphenicol (30 µg) (Mast Diagnostics Ltd., UK).

Can Escherichia coli fly? The role of flies as transmitters of E. coli to food in an urban slum in Bangladesh.

Science.gov (United States)

Lindeberg, Yrja Lisa; Egedal, Karen; Hossain, Zenat Zebin; Phelps, Matthew; Tulsiani, Suhella; Farhana, Israt; Begum, Anowara; Jensen, Peter Kjaer Mackie

2018-01-01

To investigate the transmission of faecal bacteria by flies to food under natural settings. Over a period of 2 months, paired (exposed and non-exposed) containers with cooked rice were placed on the ground in kitchen areas in an urban slum area in Dhaka, Bangladesh, and the numbers of flies landing on the exposed rice were counted. Following exposure, the surface of the rice was microbiologically and molecularly analysed for the presence of Escherichia coli and genes of diarrhoeagenic E. coli and Shigella strains. Rice was at greater risk (P E. coli if flies landed on the rice than if no flies landed on the rice (odds ratio 5·4 (P 0·6 × 103 CFU. Genes of diarrhoeagenic E. coli and Shigella species were detected in 39 of 60 (65%) of exposed rice samples. Two fly species were identified: the common housefly (Musca domestica) and the oriental latrine fly (Chrysomya megacephala). Flies may transmit large quantities of E. coli to food under field settings. The findings highlight the importance of implementing control measures to minimise exposure of food to flies to ensure food safety. Fly control measures should be considered for the prevention of diarrhoeal diseases caused by E. coli. © 2017 John Wiley & Sons Ltd.

Photoreactivating enzyme from Escherichia coli

International Nuclear Information System (INIS)

Snapka, R.M.; Fuselier, C.O.

1977-01-01

Escherichia coli photoreactivating enzyme (PRE) has been purified in large amounts from an E.coli strain lysogenic for a defective lambda bacteriophage carrying the phr gene. The resulting enzyme had a pH optimum of 7.2 and an ionic strength optimum of 0.18. It consisted of an apoprotein and cofactor, both of which were necessary for catalytic activity. The apoprotein had a monomer molecular weight of 35,200 and showed stable aggregates under denaturing conditions. The amino acid analysis of the E.coli enzyme was very similar to that of the photoreactivating enzyme from orchid seedlings (Cattelya aurantiaca). Both had arginine at the amino terminus. The cofactor, like the holoenzyme, showed absorption, magnetic circular dichroism, and emission properties indicative of an adenine moiety. Although the isolated enzyme had an action spectrum which peaked at about 360 nm, neither the cofactor, apoenzyme nor holoenzyme showed any detectable absorption between 300 and 400 nm. (author)

Photoreactivating enzyme from Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Snapka, R M; Fuselier, C O [California Univ., Irvine (USA)

1977-05-01

Escherichia coli photoreactivating enzyme (PRE) has been purified in large amounts from an E.coli strain lysogenic for a defective lambda bacteriophage carrying the phr gene. The resulting enzyme had a pH optimum of 7.2 and an ionic strength optimum of 0.18. It consisted of an apoprotein and cofactor, both of which were necessary for catalytic activity. The apoprotein had a monomer molecular weight of 35,200 and showed stable aggregates under denaturing conditions. The amino acid analysis of the E.coli enzyme was very similar to that of the photoreactivating enzyme from orchid seedlings (Cattelya aurantiaca). Both had arginine at the amino terminus. The cofactor, like the holoenzyme, showed absorption, magnetic circular dichroism, and emission properties indicative of an adenine moiety. Although the isolated enzyme had an action spectrum which peaked at about 360 nm, neither the cofactor, apoenzyme nor holoenzyme showed any detectable absorption between 300 and 400 nm.

N-Acetylglucosamine Functions in Cell Signaling

Directory of Open Access Journals (Sweden)

James B. Konopka

2012-01-01

Full Text Available The amino sugar N-acetylglucosamine (GlcNAc is well known for the important structural roles that it plays at the cell surface. It is a key component of bacterial cell wall peptidoglycan, fungal cell wall chitin, and the extracellular matrix of animal cells. Interestingly, recent studies have also identified new roles for GlcNAc in cell signaling. For example, GlcNAc stimulates the human fungal pathogen Candida albicans to undergo changes in morphogenesis and expression of virulence genes. Pathogenic E. coli responds to GlcNAc by altering the expression of fimbriae and CURLI fibers that promote biofilm formation and GlcNAc stimulates soil bacteria to undergo changes in morphogenesis and production of antibiotics. Studies with animal cells have revealed that GlcNAc influences cell signaling through the posttranslational modification of proteins by glycosylation. O-linked attachment of GlcNAc to Ser and Thr residues regulates a variety of intracellular proteins, including transcription factors such as NFκB, c-myc, and p53. In addition, the specificity of Notch family receptors for different ligands is altered by GlcNAc attachment to fucose residues in the extracellular domain. GlcNAc also impacts signal transduction by altering the degree of branching of N-linked glycans, which influences cell surface signaling proteins. These emerging roles of GlcNAc as an activator and mediator of cellular signaling in fungi, animals, and bacteria will be the focus of this paper.

High temperature in combination with UV irradiation enhances horizontal transfer of stx2 gene from E. coli O157:H7 to non-pathogenic E. coli.

Directory of Open Access Journals (Sweden)

Wan-Fu Yue

Full Text Available Shiga toxin (stx genes have been transferred to numerous bacteria, one of which is E. coli O157:H7. It is a common belief that stx gene is transferred by bacteriophages, because stx genes are located on lambdoid prophages in the E. coli O157:H7 genome. Both E. coli O157:H7 and non-pathogenic E. coli are highly enriched in cattle feedlots. We hypothesized that strong UV radiation in combination with high temperature accelerates stx gene transfer into non-pathogenic E. coli in feedlots.E. coli O157:H7 EDL933 strain were subjected to different UV irradiation (0 or 0.5 kJ/m(2 combination with different temperature (22, 28, 30, 32, and 37 °C treatments, and the activation of lambdoid prophages was analyzed by plaque forming unit while induction of Stx2 prophages was quantified by quantitative real-time PCR. Data showed that lambdoid prophages in E. coli O157:H7, including phages carrying stx2, were activated under UV radiation, a process enhanced by elevated temperature. Consistently, western blotting analysis indicated that the production of Shiga toxin 2 was also dramatically increased by UV irradiation and high temperature. In situ colony hybridization screening indicated that these activated Stx2 prophages were capable of converting laboratory strain of E. coli K12 into new Shiga toxigenic E. coli, which were further confirmed by PCR and ELISA analysis.These data implicate that high environmental temperature in combination with UV irradiation accelerates the spread of stx genes through enhancing Stx prophage induction and Stx phage mediated gene transfer. Cattle feedlot sludge are teemed with E. coli O157:H7 and non-pathogenic E. coli, and is frequently exposed to UV radiation via sunlight, which may contribute to the rapid spread of stx gene to non-pathogenic E. coli and diversity of shiga toxin producing E. coli.

The presence of verotoxinogenic E. coli in some foods

Directory of Open Access Journals (Sweden)

Bostan K.

2005-01-01

Full Text Available In this study 30 samples each of ready-to-cook meatballs and white cheese as well as 96 samples of various ready-to-eat foods, obtained from different sales outlets in Istanbul, were analyzed for the presence of verotoxins (consequently vemtoxigenic E. coli E. coli with the aid of the enzyme immunoassay technique. Additionally, total coli-form and chromogenic E. coli count were determined by cultural methods for all food samples. E. coli growth was detected in all ready-to-cook meatballs (100%, in 27 of the white cheese samples (90% and in 69 of the other ready-to-eat food samples (71.9%. Verotoxins, however, could not be detected in any of the samples examined with the aid of the ELISA technique. The findings of this study indicate a low microbiological quality of the analyzed meatball, white cheese and ready-to-eat food samples; a considerable part of them did not conform to legal standards. However, within the sensitivity limits of the method applied no verotoxinogenic E. coli could be detected.

Lethality prediction for Escherichia coli 0157:H7 and Uropathogenic E. coli in ground chicken treated with high pressure processing and trans-cinnamaldehyde

Science.gov (United States)

Pathogenic Escherichia coli, intestinal (O157:H7) as well as extraintestinal types (Uropathogenic E. coli (UPEC)) are commonly found in many foods including chicken meat. In this study we compared the resistance of E. coli O157:H7 to UPEC in chicken meat under the stresses of high hydrostatic pressu...

Molecular epidemiology of extended-spectrum beta-lactamase-producing Escherichia coli

Directory of Open Access Journals (Sweden)

Catherine Ludden

2014-09-01

Full Text Available Objectives: E. coli O25b-ST131 has disseminated worldwide in hospitals and the community. The objective of this study was to determine the extent to which E. coli O25b-ST131 accounts for extended-spectrum beta-lactamase (ESBLproducing E. coli from clinical samples from all sources in this region. Methods: Between January and June 2010 ESBL-producing E. coli were collected from 94 routine samples including 47 from residents of 25 nursing homes, 15 categorized as hospital acquired and 32 others. PCR was performed for detection of bla CTX-M, bla OXA-1, bla TEM, bla SHV and for the identification of members of the E. coli O25b:ST131 clonal group. PFGE was carried out using Xba I in accordance with PulseNet protocols. Results: The majority (97% of isolates harbored a bla CTX-M gene.E. coli O25b-ST131 accounted for 87% of all ESBL-producing E. coliand for 96% of isolates from nursing home residents. Conclusion:The E. coli O25b-ST131 clonal group predominated in the collection of ESBL-producing E. coli, particularly in nursing home isolates. J Microbiol Infect Dis 2014; 4(3: 92-96

Third International E. coli genome meeting

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-12-31

Proceedings of the Third E. Coli Genome Meeting are provided. Presentations were divided into sessions entitled (1) Large Scale Sequencing, Sequence Analysis; (2) Databases; (3) Sequence Analysis; (4) Sequence Divergence in E. coli Strains; (5) Repeated Sequences and Regulatory Motifs; (6) Mutations, Rearrangements and Stress Responses; and (7) Origins of New Genes. The document provides a collection of abstracts of oral and poster presentations.

Impact of persistent and nonpersistent generic Escherichia coli and Salmonella sp. recovered from a beef packing plant on biofilm formation by E. coli O157.

Science.gov (United States)

Visvalingam, J; Ells, T C; Yang, X

2017-12-01

To examine the influence of meat plant Escherichia coli and Salmonella sp. isolates on E. coli O157 biofilm formation. Biofilm formation was quantified by crystal violet staining (A 570 nm ) and viable cell numbers for up to 6 days at 15°C. All five persistent E. coli genotypes formed strong biofilms when cultured alone or co-cultured with E. coli O157, with A 570 nm values reaching ≥4·8 at day 4, while only two of five nonpersistent genotypes formed such biofilms. For E. coli O157:H7 co-culture biofilms with E. coli genotypes 136 and 533, its numbers were ≥1·5 and ≥1 log CFU per peg lower than those observed for its mono-culture biofilm at days 2 and 4, respectively. The number of E. coli O157:NM in similar co-culture biofilms was 1 log CFU per peg lower than in its mono-culture biofilm at day 4 and 6, respectively. Salmonella sp. lowered the number of E. coli O157:NM by 0·5 log unit, once, at day 6. Generic E. coli may outcompete E. coli O157 strains while establishing biofilms. Findings advance knowledge regarding inter-strain competition for a similar ecological niche and may aid development of biocontrol strategies for E. coli O157 in food processing environments. © 2017 Her Majesty the Queen in Right of Canada. Journal of Applied Microbiology © 2017 The Society for Applied Microbiology Reproduced with the permission of the Minister of the Department of Agriculture and Agri-Food Canada.

Protection against an infectious disease by enterohaemorrhagic E. coli 0-157.

Science.gov (United States)

Ota, A

1999-07-01

Preventive measures against infection by enterohaemorrhagic E. coli 0-157 are described. Eating yoghurt and Kefir supposedly induces more bifid bacteria and lactic acid bacteria to colonize in the intestines, thereby protecting humans from infection by E. coli 0-157. Some foods, such as plum extract, act as a mild antibiotic and produce an acidic environment within the intestine, thus interfering with growth of the E. coli 0-157. The natural colonization of harmless E. coli or other bacteria that are more powerful than E. coli 0-157 can possibly protect against infection. A vaccination against E. coli 0-157 H7 may also be effective. In addition, it has been suggested that the correct levels of nitric oxide and calcium in the blood may activate immunity and protect against infection by E. coli 0-157.

Antimicrobial resistance among commensal Escherichia coli from ...

African Journals Online (AJOL)

Commensal bacteria contribute to the distribution and persistence of antimicrobial resistance in the environment. This study monitored antimicrobial resistance in commensal Escherichia coli from the faeces of on-farm and slaughter cattle and beef. A total of 342 (89.5%) E. coli isolates were obtained from 382 samples.

Antimicrobial resistance among commensal Escherichia coli from ...

African Journals Online (AJOL)

user1

2012-07-19

Jul 19, 2012 ... Commensal bacteria contribute to the distribution and persistence of antimicrobial resistance in the environment. This study monitored antimicrobial resistance in commensal Escherichia coli from the faeces of on-farm and slaughter cattle and beef. A total of 342 (89.5%) E. coli isolates were obtained.

Illegitimate WNT signaling promotes proliferation of multiple myeloma cells

Science.gov (United States)

Derksen, Patrick W. B.; Tjin, Esther; Meijer, Helen P.; Klok, Melanie D.; Mac Gillavry, Harold D.; van Oers, Marinus H. J.; Lokhorst, Henk M.; Bloem, Andries C.; Clevers, Hans; Nusse, Roel; van der Neut, Ronald; Spaargaren, Marcel; Pals, Steven T.

2004-01-01

The unrestrained growth of tumor cells is generally attributed to mutations in essential growth control genes, but tumor cells are also influenced by signals from the environment. In multiple myeloma (MM), the factors and signals coming from the bone marrow microenvironment are possibly even essential for the growth of the tumor cells. As targets for intervention, these signals may be equally important as mutated oncogenes. Given their oncogenic potential, WNT signals form a class of paracrine growth factors that could act to influence MM cell growth. In this paper, we report that MM cells have hallmarks of active WNT signaling, whereas the cells have not undergone detectable mutations in WNT signaling genes such as adenomatous polyposis coli and β-catenin (CTNNB1). We show that the malignant MM plasma cells overexpress β-catenin, including its N-terminally unphosphorylated form, suggesting active β-catenin/T cell factor-mediated transcription. Further accumulation and nuclear localization of β-catenin, and/or increased cell proliferation, was achieved by stimulation of WNT signaling with either Wnt3a, LiCl, or the constitutively active S33Y mutant of β-catenin. In contrast, by blocking WNT signaling by dominant-negative T cell factor, we can interfere with the growth of MM cells. We therefore suggest that MM cells are dependent on an active WNT signal, which may have important implications for the management of this incurable form of cancer. PMID:15067127

Enteroaggregative Escherichia coli is the predominant diarrheagenic E. coli pathotype among irrigation water and food sources in South Africa.

Science.gov (United States)

Aijuka, Matthew; Santiago, Araceli E; Girón, Jorge A; Nataro, James P; Buys, Elna M

2018-08-02

Diarrheagenic E. coli (DEC) has been implicated in foodborne outbreaks worldwide and have been associated with childhood stunting in the absence of diarrhoea. Infection is extraordinarily common, but the routes of transmission have not been determined. Therefore, determining the most prevalent pathotypes in food and environmental sources may help provide better guidance to various stakeholders in ensuring food safety and public health and advancing understanding of the epidemiology of enteric disease. We characterized 205 E. coli strains previously isolated from producer distributor bulk milk (PDBM)(118), irrigation water (48), irrigated lettuce (29) and street vendor coleslaw (10) in South Africa. Enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC) and diffusely adherent E. coli (DAEC) were sought. We used PCR and partial gene sequencing for all 205 strains while 46 out of 205 that showed poor resolution were subsequently characterized using cell adherence (HeLa cells). PCR and partial gene sequencing of aatA and/or aaiC genes confirmed EAEC (2%, 5 out of 205) as the only pathotype. Phylogenetic analysis of sequenced EAEC strains with E. coli strains in GenBank showing ≥80% nucleotide sequence similarity based on possession of aaiC and aatA generated distinct clusters of strains separated predominantly based on their source of isolation (food source or human stool) suggesting a potential role of virulence genes in source tracking. EAEC 24%, 11 out of 46 strains (PDBM = 15%, irrigation water = 7%, irrigated lettuce = 2%) was similarly the predominant pathotype followed by strains showing invasiveness to HeLa cells, 4%, 2 out of 46 (PDBM = 2%, irrigated lettuce = 2%), among stains characterized using cell adherence. Therefore, EAEC may be the leading cause of DEC associated food and water-borne enteric infection in South Africa. Additionally, solely using molecular based methods targeting virulence

Fluoroquinolone-resistant Escherichia coli carriage in long-term care facility.

Science.gov (United States)

Maslow, Joel N; Lee, Betsy; Lautenbach, Ebbing

2005-06-01

We conducted a cross-sectional study to determine the prevalence of, and risk factors for, colonization with fluoroquinolone (FQ)-resistant Escherichia coli in residents in a long-term care facility. FQ-resistant E. coli were identified from rectal swabs for 25 (51%) of 49 participants at study entry. On multivariable analyses, prior FQ use was the only independent risk factor for FQ-resistant E. coli carriage and was consistent for FQ exposures in the previous 3, 6, 9, or 12 months. Pulsed-field gel electrophoresis of FQ-resistant E. coli identified clonal spread of 1 strain among 16 residents. Loss (6 residents) or acquisition (7 residents) of FQ-resistant E. coli was documented and was associated with de novo colonization with genetically distinct strains. Unlike the case in the hospital setting, FQ-resistant E. coli carriage in long-term care facilities is associated with clonal spread.

Expression in E. coli systems

DEFF Research Database (Denmark)

Krogsdam, Anne-M; Kristiansen, Karsten; Nøhr, Jane

2003-01-01

intracellularly in soluble form. In E. coli, proteins containing disulfide bonds are best produced by secretion because the disulfide forming foldases reside in the periplasm. Likewise, a correct N-terminus is more likely to be obtained upon secretion. Moreover, potentially toxic proteins are more likely......Owing to cost advantage, speed of production, and often high product yield (up to 50% of total cell protein), expression in Escherichia coli is generally the first choice when attempting to express a recombinant protein. Expression systems exist to produce recombinant protein intracellularly...

Strategies for Protein Overproduction in Escherichia coli.

Science.gov (United States)

Mott, John E.

1984-01-01

Examines heterologous expression in Escherichia coli and the role of regulatory sequences which control gene expression at transcription resulting in abundant production of messenger RNA and regulatory sequences in mRNA which promote efficient translation. Also examines the role of E. coli cells in stabilizing mRNA and protein that is…

A novel fluorescence immunoassay for the sensitive detection of Escherichia coli O157:H7 in milk based on catalase-mediated fluorescence quenching of CdTe quantum dots.

Science.gov (United States)

Chen, Rui; Huang, Xiaolin; Li, Juan; Shan, Shan; Lai, Weihua; Xiong, Yonghua

2016-12-01

Immunoassay is a powerful tool for rapid detection of food borne pathogens in food safety monitoring. However, conventional immunoassay always suffers from low sensitivity when it employs enzyme-catalyzing chromogenic substrates to generate colored molecules as signal outputs. In the present study, we report a novel fluorescence immunoassay for the sensitive detection of E. coli O157:H7 through combination of the ultrahigh bioactivity of catalase to hydrogen peroxide (H 2 O 2 ) and H 2 O 2 -sensitive mercaptopropionic acid modified CdTe QDs (MPA-QDs) as a signal transduction. Various parameters, including the concentrations of anti-E. coli O157:H7 polyclonal antibody and biotinylated monoclonal antibody, the amounts of H 2 O 2 and streptavidin labeled catalase (CAT), the hydrolysis temperature and time of CAT to H 2 O 2 , as well as the incubation time between H 2 O 2 and MPA-QDs, were systematically investigated and optimized. With optimal conditions, the catalase-mediated fluorescence quenching immunoassay exhibits an excellent sensitivity for E. coli O157:H7 with a detection limit of 5 × 10 2  CFU/mL, which was approximately 140 times lower than that of horseradish peroxidase-based colorimetric immunoassay. The reliability of the proposed method was further evaluated using E. coli O157:H7 spiked milk samples. The average recoveries of E. coli O157:H7 concentrations from 1.18 × 10 3  CFU/mL to 1.18 × 10 6  CFU/mL were in the range of 65.88%-105.6%. In brief, the proposed immunoassay offers a great potential for rapid and sensitive detection of other pathogens in food quality control. Copyright © 2016 Elsevier B.V. All rights reserved.

Triglyceride kinetics in fasted and fed E.coli septic rats

International Nuclear Information System (INIS)

Lanza-Jacoby, S.; Tabares, A.

1990-01-01

The mechanism for the development of hypertriglyceridemia during gram-negative sepsis was studies by examining the liver production and clearance of very-low-density lipoprotein (VLDL) triglyceride (TG). To assess the liver output and peripheral clearance the kinetics of VLDL-TG were determined by a constant intravenous infusion of [2- 3 H] glycerol-labeled VLDL in fasted control, fasted E. coli-treated, fed control, and fed E.coli-treated rats. Lewis inbred rats, 275-300 g, were made septic with 8 x 10 7 live E.coli colonies per 100 g body weight. Twenty-four hours following E.coli injection serum TG of fasted E.coli-treated rats was elevated by 170% which was attributed to a 67% decrease in the clearance rate of VLDL-TG in fasted E.coli-treated rats compared with their fasted controls. The secretion of VLDL-TG declined by 31% in the livers of the fasted E.coli-treated rats which was accompanied by a 2-fold increase in the composition of liver TG. In a second series of experiments control and E.coli-treated rats were fed intragastrically (IG) a balanced solution containing glucose plus fat as the sources of nonprotein calories. Serum TG were 26% lower in the fed E.coli-treated rats because the clearance rate increased by 86%. The secretion of TG in the fed septic rats increased by 40% but this difference was not significant. In the septic rat the ability to clear triglycerides from the plasma depends upon the nutritional state

ECMDB: The E. coli Metabolome Database

OpenAIRE

Guo, An Chi; Jewison, Timothy; Wilson, Michael; Liu, Yifeng; Knox, Craig; Djoumbou, Yannick; Lo, Patrick; Mandal, Rupasri; Krishnamurthy, Ram; Wishart, David S.

2012-01-01

The Escherichia coli Metabolome Database (ECMDB, http://www.ecmdb.ca) is a comprehensively annotated metabolomic database containing detailed information about the metabolome of E. coli (K-12). Modelled closely on the Human and Yeast Metabolome Databases, the ECMDB contains >2600 metabolites with links to ?1500 different genes and proteins, including enzymes and transporters. The information in the ECMDB has been collected from dozens of textbooks, journal articles and electronic databases. E...

Metabolic Modeling of Common Escherichia coli Strains in Human Gut Microbiome

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Yue-Dong Gao

2014-01-01

Full Text Available The recent high-throughput sequencing has enabled the composition of Escherichia coli strains in the human microbial community to be profiled en masse. However, there are two challenges to address: (1 exploring the genetic differences between E. coli strains in human gut and (2 dynamic responses of E. coli to diverse stress conditions. As a result, we investigated the E. coli strains in human gut microbiome using deep sequencing data and reconstructed genome-wide metabolic networks for the three most common E. coli strains, including E. coli HS, UTI89, and CFT073. The metabolic models show obvious strain-specific characteristics, both in network contents and in behaviors. We predicted optimal biomass production for three models on four different carbon sources (acetate, ethanol, glucose, and succinate and found that these stress-associated genes were involved in host-microbial interactions and increased in human obesity. Besides, it shows that the growth rates are similar among the models, but the flux distributions are different, even in E. coli core reactions. The correlations between human diabetes-associated metabolic reactions in the E. coli models were also predicted. The study provides a systems perspective on E. coli strains in human gut microbiome and will be helpful in integrating diverse data sources in the following study.

Influence of medium components on the expression of recombinant lipoproteins in Escherichia coli.

Science.gov (United States)

Tseng, Chi-Ling; Leng, Chih-Hsiang

2012-02-01

Bacterial lipoproteins are crucial antigens for protective immunity against bacterial pathogens. Expression of exogenous lipoproteins in Escherichia coli at high levels is thought to be an extremely difficult endeavor because it frequently results in incomplete or absent lipid modification. Previously, we identified a fusion sequence (D1) from a Neisseria meningitidis lipoprotein that induced a non-lipidated protein, E3 (the domain III of the dengue virus envelope protein), to become lipidated. However, without optimizing the growth conditions, some of the D1-fusion proteins were not lipidated. Here, we report the influence of medium components on the expression of recombinant lipoproteins in E. coli. For high-level expression of mature lipoproteins in the C43 (DE3) strain, M9 medium was better than M63 and the rich medium. Furthermore, we analyzed the influence of other media factors (including nitrogen and carbon sources, phosphate, ferrous ions, calcium, magnesium, and pH) on the levels of lipoprotein expression. The results showed that excess nitrogen sources and phosphate in M9 medium could increase the amount of immature lipoproteins, and glucose was a better carbon source than glycerol for expressing mature lipoproteins. We also found that lipoproteins tended to be completely processed in the alkaline environment, even in the nutrient-rich medium. Additional constructs expressing different immunogens or lipid signal peptides as targets were also utilized, demonstrating that these targets could be expressed as completely mature lipoproteins in the M9 medium but not in the rich medium. Our results provide the useful information for expressing mature exogenous lipoproteins in E. coli.

Cloning and expression of pab gene of M. tuberculosis isolated from pulmonary TB patient in E.coli DH5α

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Tri Y. M. Raras

2011-11-01

Full Text Available Background: Mycobacterium tuberculosis antigen38 is a potent serodiagnostic agent containing two M. tuberculosisspecific B-cell epitopes. The high price of imported diagnostic agents hinders realization of fast clinical TB diagnosis in developing countries. Therefore, we produced recombinant antigen38 (recAg38M from M. tuberculosis local strain, which might be used to produce economical tuberculosis serodiagnostic kit.Methods: Pab gene that was isolated from pulmonary TB patient in Malang was cloned into a plasmid vector (pGEMTeasy to construct pMB38. The E.coli DH5α clone carrying pMb38 was selected on X-gal medium. The expression of pab was mediated using pPRoExHTc under the control of Trc promoter and E.coli DH5α as host.Results: Alignment of the pab sequence from the white E.coli DH5α clones with that of M. tuberculosis H37Rv showed 98% homology. The recombinant protein in which the signal peptide has been deleted to prevent the protein being secreted into medium was found in the cytoplasm.Conclusion: pab gene of M. tuberculosis isolated from a TB patient could be expressed in heterologous system in E.coliDH5α. (Med J Indones 2011; 20:247-54Keywords: Mycobacterium tuberculosis, Pab gene expression, recombinant antigen38

Plasmid-Mediated Quinolone Resistance Genes in Escherichia coli ...

African Journals Online (AJOL)

Erah

PMQR) genes and the prevalence of extended spectrum β-lactamase (ESBL) types in Escherichia coli clinical isolates. Methods: Sixty-one ESBL-producing urinary E. coli isolates were studied. An antibiotic susceptibility test was performed ...

Photoinactivation of mcr-1 positive Escherichia coli

Science.gov (United States)

Caires, C. S. A.; Leal, C. R. B.; Rodrigues, A. C. S.; Lima, A. R.; Silva, C. M.; Ramos, C. A. N.; Chang, M. R.; Arruda, E. J.; Oliveira, S. L.; Nascimento, V. A.; Caires, A. R. L.

2018-01-01

The emergence of plasmid-mediated colistin resistance in Enterobacteriaceae, mostly in Escherichia coli due to the mcr-1 gene, has revealed the need to develop alternative approaches in treating mcr-1 positive bacterial infections. This is because colistin is a broad-spectrum antibiotic and one of the ‘last-resort’ antibiotics for multidrug resistant bacteria. The present study evaluated for the first time, to the best of our knowledge, the efficacy of photoinactivation processes to kill a known mcr-1 positive E. coli strain. Eosin methylene-blue (EMB) was investigated as a photoantimicrobial agent for inhibiting the growth of a mcr-1 positive E. coli strain obtained from a patient with a diabetic foot infection. The photoantimicrobial activity of EMB was also tested in a non-multidrug resistant E. coli strain. The photoinactivation process was tested using light doses in the 30-45 J cm-2 range provided by a LED device emitting at 625 nm. Our findings demonstrate that a mcr-1 positive E. coli strain is susceptible to photoinactivation. The results show that the EMB was successfully photoactivated, regardless of the bacterial multidrug resistance; inactivating the bacterial growth by oxidizing the cells in accordance with the generation of the oxygen reactive species. Our results suggest that bacterial photoinactivation is an alternative and effective approach to kill mcr-1 positive bacteria.

Anti E. coli Activity of Herbal Medicines: a Review

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Nahid Rezaei

2017-12-01

Full Text Available Escherichia coli is the gram negative bacilli of Entrobacteriaceae family that commonly found in intestinal infections and many infections outside the intestine, like urinary tract infections (UTI, cholecystitis, wound infections, meningitis, septicemia, pulmonary infections, and many more. Plants are rich sources of bioactive compounds, hence they can be effective in a wide variety of diseases. The pandemic spread of multidrug-resistant (MDR bacteria (i.e., extended-spectrum b-lactamase-producing Enterobacteriaceae (ESBLPE, Carbapenemase-producing Enterobacteriaceae (CPE threaten healthcare Worldwide. The present review is a report of the most effective medicinal plants against E. coli. In this research, the required online database searches were conducted using the key words such as bacteria, E. coli and medicinal plants. Databases of Web of Science, PubMed, Scopus, Google Scholar, and ScienceDirect were explored to find and explore related articles. Since the incidence of E. coli is high, the aim of this study is to identify and report anti E. coli medicinal plants in Iran. The obtained results showed that there were 51 medicinal herbs that could be considered as the main medicinal plants capable of affecting E. coli.

Substrate overlap and functional competition between human nucleotide excision repair and Escherichia coli photolyase and (A)BC excision nuclease

International Nuclear Information System (INIS)

Sibghat-Ullah; Sancar, Z.

1990-01-01

Human cell free extract prepared by the method of Manley et al. carries out repair synthesis on UV-irradiated DNA. Removal of pyrimidine dimers by photoreactivation with DNA photolyase reduces repair synthesis by about 50%. With excess enzyme in the reaction mixture photolyase reduced the repair signal by the same amount even in the absence of photoreactivating light, presumably by binding to pyrimidine dimers and interfering with the binding of human damage recognition protein. Similarly, the UvrB subunit of Escherichia coli (A)BC excinuclease when loaded onto UV-irradiated or psoralen-adducted DNA inhibited repair synthesis by cell-free extract by 75-80%. The opposite was true also as HeLa cell free extract specifically inhibited the photorepair of a thymine dimer by DNA photolyase and its removal by (A)BC excinuclease. Cell-free extracts from xeroderma pigmentosum (XP) complementation groups A and C were equally effective in blocking the E. coli repair proteins, while extracts from complementation groups D and E were ineffective in blocking the E. coli enzyme. These results suggest that XP-D and XP-E cells are defective in the damage recognition subunits(s) of human excision nuclease

Biochemical and serological characterization of Escherichia coli ...

African Journals Online (AJOL)

This study was designed to determine the isolation rate, serotypes and biochemical profiles of E. coli from colibacillosis and dead-in-shell embryos in Zaria, Northern-Nigeria. The isolation rate of E. coli from hatcheries studied were 4.67% and 7.50% from farms of Simtu Agricultural Company and National Animal Production ...

Cytolysin a expressing E. coli a promising candidate for imageable therapeutic probe

International Nuclear Information System (INIS)

Nguyen, Vu Hong; Phan, Thuy Xuan; Hong, Yeoung Jin; Min, Jung Joon

2007-01-01

Using bacteria for cancer treatment has a long history. Discovery of optical reporter genes consisting of fluorescent and luminescent protein facilitates the monitor of bacteria in vivo, non-invasively and repeatedly. E. coli, the natural enteric bacteria possessing capacity of tumor-targeting ability, seems to be suitable candidate for cancer treatment. In this study, we established the strain light-emitting E. coli for diagnostic purpose and Cytolysin A (Cly A) expressing E. coli for therapeutic purpose. E. coli (MG1655, wild type strain) was transformed plasmid pUC19 carrying lux gene to create the light expressing bacteria and test the tumor targeting-capacity by injecting the bacteria into CT26-tumor bearing mice via tail vein. On the other hand, for therapeutic purpose, plasmid containing Cly A gene, which is encoded for a pore-forming protein toxin, was introduced into E. coli. The toxicity of Cly A was evaluated in vitro by inoculating the bacteria with various cultured cancer cell lines. On the other hand, to test the therapeutic effect, the bacteria were injected intratumorally and intravenously into s.c.CT26-bearing as well as CT26-lung metastasized Balb/c mice. In vivo imaging data showed that the E. coli strains selectively located in the tumor. The in vitro result showed that the number of death cells were significantly higher in the samples containing E. coli expressing Cly A (E. coli Cly A) compared with the samples containing wild type strain. The growth of tumors was repressed in mice injected with either E. coli Cly A (significantly) or wild type E. coli (mildly), while tumors in no treatment group still grew fast. Furthermore, the tumors inoculated with E. coli cly A were necrotized but not with wild type E. coli. In the CT26-lung metastasized mouse model, the life span of mice was elongated when inject E. coli and longer in the group injected with E. coli cly A. Cly A expressing E. coli can become an effective candidate for imageable

Transport proteins promoting Escherichia coli pathogenesis

Science.gov (United States)

Tang, Fengyi; Saier, Milton H.

2014-01-01

Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies. PMID:24747185

Transport proteins promoting Escherichia coli pathogenesis.

Science.gov (United States)

Tang, Fengyi; Saier, Milton H

2014-01-01

Escherichia coli is a genetically diverse species infecting hundreds of millions of people worldwide annually. We examined seven well-characterized E. coli pathogens causing urinary tract infections, gastroenteritis, pyelonephritis and haemorrhagic colitis. Their transport proteins were identified and compared with each other and a non-pathogenic E. coli K12 strain to identify transport proteins related to pathogenesis. Each pathogen possesses a unique set of protein secretion systems for export to the cell surface or for injecting effector proteins into host cells. Pathogens have increased numbers of iron siderophore receptors and ABC iron uptake transporters, but the numbers and types of low-affinity secondary iron carriers were uniform in all strains. The presence of outer membrane iron complex receptors and high-affinity ABC iron uptake systems correlated, suggesting co-evolution. Each pathovar encodes a different set of pore-forming toxins and virulence-related outer membrane proteins lacking in K12. Intracellular pathogens proved to have a characteristically distinctive set of nutrient uptake porters, different from those of extracellular pathogens. The results presented in this report provide information about transport systems relevant to various types of E. coli pathogenesis that can be exploited in future basic and applied studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

E.coli O157:H7

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Treor Francis Fernandez

2008-06-01

Full Text Available The serious nature of the symptoms of haemorrhagic colitis and HUS and the apparent low infectious dose (<100 cells of E.coli O157:H7 places this food borne pathogen a most serious of known food borne pathogens. Persuasive evidence suggests that healthy cattle are a reservoir of O157 and they can enter the food chain to provide a source of exposure for humans. A possible route of transmission of O157 VTEC may involve infections initially in calves that shed their organism into faecal slurry that may be used on grazing grass. This provides potential for infection of other animals from which the organism may contaminate milk or carcasses at slaughter. Possible sources of VTEC in healthy animals other E.coli O157:H7 than cattle and a wider range of foodstuffs require further investigation. Many features of E.coli O157:H7 strains remain poorly understood. It includes: (i Role of virulent genes in the animal, (ii Mechanism of evolution of the organism, (iii The progress of individual cases of E.coli O157:H7 infection, and (iv The difference in incidence of infection in different geographical areas. [Veterinary World 2008; 1(3.000: 83-87

Brote causado por Escherichia coli en Chalco, México Outbreak caused by Escherichia coli in Chalco, México

Directory of Open Access Journals (Sweden)

Iliana Alejandra Cortés-Ortiz

2002-07-01

Full Text Available Objetivo. Identificar el agente causal del brote de diarrea asociado con el desbordamiento del canal de aguas negras en Chalco. Material y métodos. Estudio retrospectivo y transversal, efectuado en el Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE, de la Secretaría de Salud, con 1 550 hisopos rectales para el aislamiento e identificación bioquímica de V. cholerae y enterobacterias, obtenidos de la población del Valle de Chalco, que presentó diarrea y vómito durante el desastre natural acontecido el 31 de mayo de 2000. El análisis de los resultados se efectuó por la diferencia entre las proporciones de dos poblaciones (prueba de Ji cuadrada. Las cepas de E. coli se hibridaron por "colony blot" para los grupos ETEC, EIEC, EPEC y EHEC. Resultados. El 0.45% correspondió a Salmonella: S. agona, S. infantis, S. enteritidis, S. muenchen, S. typhimurium; 0.06% a Shigella flexneri 3a, y 76.6% a E. coli: 62.2% a ETEC (44.6 % con LT, 11.2% con ST, y 44.1% con ambas sondas, 0.84% a EIEC (sonda ial, 0.84% a EPEC (sonda bundle-forming pilus BFP, 0.08% a E. coli enterohemorrágica no-O157:H7 (sonda pCVD419, y 36.02% no hibridó. No se encontró asociación entre E. coli patógena con la edad y género. Conclusiones. Escherichia coli podría ser responsable del brote de diarrea. Es importante conocer el agente etiológico del brote para encaminar las estrategias en el estudio y control sanitario del mismo.Objective. To identify the etiologic agent responsible for a disease outbreak following an overflow of sewage water in Valle de Chalco, Mexico. Material and Methods. A retrospective cross-sectional study was carried out. Rectal samples were collected from the population of Chalco valley, who suffered from diarrhea and vomiting during a natural disaster that took place on May 31, 2000. The Instituto de Diagnóstico y Referencia Epidemiológicos (Epidemic Reference and Diagnosis Institute, InDRE, Ministry of Health, received 1521 rectal

Toxicity mechanism of carbon nanotubes on Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Young, Yu-Fu [Department of Materials Science and Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Lee, Hui-Ju [Department of Life Science, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Shen, Yi-Shan; Tseng, Shih-Hao; Lee, Chi-Young [Department of Materials Science and Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Tai, Nyan-Hwa, E-mail: nhtai@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Chang, Hwan-You, E-mail: hychang@mx.nthu.edu.tw [Department of Life Science, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

2012-05-15

Highlights: Black-Right-Pointing-Pointer F-MWCNTs possess higher antibiotic performance than that of the F-SWCNTs. Black-Right-Pointing-Pointer E. coli cells were pierced when incubated with F-MWCNTs and trapped when incubated with F-SWCNTs. Black-Right-Pointing-Pointer The rigidity and moment of CNTs play important role on the antibiotic effect. - Abstract: The influences of carbon nanomaterials on bacteria were investigated using three types of dispersed and functionalized carbon nanomaterials (F-CNMs), viz. functionalized carbon nanopowder (F-CNP), functionalized single-walled carbon nanotubes (F-SWCNTs), and functionalized multi-walled carbon nanotubes (F-MWCNTs). F-CNMs with different aspect ratios were used to study the influence of material configuration on the viability of Escherichia coli (E. coli). Although these materials were functionalized to improve their dispersibility, the original morphologies and chemical properties of the materials were maintained. Traditional bacteria quantitative plating analysis was conducted, and the results of which revealed that the F-CNP and the F-SWCNTs showed a less significant effect on the viability of E. coli, while the F-MWCNTs obviously inhibited cell viability. A Fourier transform infrared spectroscopy and a scanning electron microscopy were used to verify the functionalization of the F-CNMs and to examine the interaction of F-CNMs with E. coli, respectively; in addition, we adopted chemiluminescence assays to measure the concentration of adenosine triphosphate (ATP) released from the damaged cells. The results showed that the ATP of the F-MWCNTs sample is two-fold higher than that of the control, indicating direct piercing of E. coli by F-MWCNTs leads to bacteria death. Furthermore, F-SWCNTs were concluded to have less influence on the viability of E. coli because ultra-long F-SWCNTs used in this study performed less rigidity to pierce the cells.

Toxicity mechanism of carbon nanotubes on Escherichia coli

International Nuclear Information System (INIS)

Young, Yu-Fu; Lee, Hui-Ju; Shen, Yi-Shan; Tseng, Shih-Hao; Lee, Chi-Young; Tai, Nyan-Hwa; Chang, Hwan-You

2012-01-01

Highlights: ► F-MWCNTs possess higher antibiotic performance than that of the F-SWCNTs. ► E. coli cells were pierced when incubated with F-MWCNTs and trapped when incubated with F-SWCNTs. ► The rigidity and moment of CNTs play important role on the antibiotic effect. - Abstract: The influences of carbon nanomaterials on bacteria were investigated using three types of dispersed and functionalized carbon nanomaterials (F-CNMs), viz. functionalized carbon nanopowder (F-CNP), functionalized single-walled carbon nanotubes (F-SWCNTs), and functionalized multi-walled carbon nanotubes (F-MWCNTs). F-CNMs with different aspect ratios were used to study the influence of material configuration on the viability of Escherichia coli (E. coli). Although these materials were functionalized to improve their dispersibility, the original morphologies and chemical properties of the materials were maintained. Traditional bacteria quantitative plating analysis was conducted, and the results of which revealed that the F-CNP and the F-SWCNTs showed a less significant effect on the viability of E. coli, while the F-MWCNTs obviously inhibited cell viability. A Fourier transform infrared spectroscopy and a scanning electron microscopy were used to verify the functionalization of the F-CNMs and to examine the interaction of F-CNMs with E. coli, respectively; in addition, we adopted chemiluminescence assays to measure the concentration of adenosine triphosphate (ATP) released from the damaged cells. The results showed that the ATP of the F-MWCNTs sample is two-fold higher than that of the control, indicating direct piercing of E. coli by F-MWCNTs leads to bacteria death. Furthermore, F-SWCNTs were concluded to have less influence on the viability of E. coli because ultra-long F-SWCNTs used in this study performed less rigidity to pierce the cells.

Vascular Endothelial Growth Factor Receptor 1 Contributes to Escherichia coli K1 Invasion of Human Brain Microvascular Endothelial Cells through the Phosphatidylinositol 3-Kinase/Akt Signaling Pathway▿ †

OpenAIRE

Zhao, Wei-Dong; Liu, Wei; Fang, Wen-Gang; Kim, Kwang Sik; Chen, Yu-Hua

2010-01-01

Escherichia coli is the most common Gram-negative organism causing neonatal meningitis. Previous studies demonstrated that E. coli K1 invasion of brain microvascular endothelial cells (BMEC) is required for penetration into the central nervous system, but the microbe-host interactions that are involved in this process remain incompletely understood. Here we report the involvement of vascular endothelial growth factor receptor 1 (VEGFR1) expressed on human brain microvascular endothelial cells...

Recent Advances in Understanding Enteric Pathogenic Escherichia coli

Science.gov (United States)

Croxen, Matthew A.; Law, Robyn J.; Scholz, Roland; Keeney, Kristie M.; Wlodarska, Marta

2013-01-01

SUMMARY Although Escherichia coli can be an innocuous resident of the gastrointestinal tract, it also has the pathogenic capacity to cause significant diarrheal and extraintestinal diseases. Pathogenic variants of E. coli (pathovars or pathotypes) cause much morbidity and mortality worldwide. Consequently, pathogenic E. coli is widely studied in humans, animals, food, and the environment. While there are many common features that these pathotypes employ to colonize the intestinal mucosa and cause disease, the course, onset, and complications vary significantly. Outbreaks are common in developed and developing countries, and they sometimes have fatal consequences. Many of these pathotypes are a major public health concern as they have low infectious doses and are transmitted through ubiquitous mediums, including food and water. The seriousness of pathogenic E. coli is exemplified by dedicated national and international surveillance programs that monitor and track outbreaks; unfortunately, this surveillance is often lacking in developing countries. While not all pathotypes carry the same public health profile, they all carry an enormous potential to cause disease and continue to present challenges to human health. This comprehensive review highlights recent advances in our understanding of the intestinal pathotypes of E. coli. PMID:24092857

Assessment of the efficiency of ColiSure™ for coliforms Escherichia coli enumeration in pasteurizad milk / Avaliação do desempenho do ColiSure™ na enumeração de coliformes totais e Escherichia coli em leite pasteurizado

Directory of Open Access Journals (Sweden)

Elsa Helena Walter de Santana

2000-12-01

Full Text Available In the dairy industry the coliforms detection can he used as indicative of hygiene production of the raw milk and the contamination after-pasteurization. The traditional methods for the enumeration of the total and faecal coliforms are laborious and needs an incubation time of 96 hours. Rapid methods for detection of these microorganisms have been developed and among them the ColsSuroit is a rapid method that gives results in 24 hours and involves defined substrates for simultaneous determination of total conforms and E. coli in water based in specific enzymatic reactions of these microorganisms. The objective of this study was to evaluate its utilization in milk. Ninety-five samples of pasteurized milk were collected from the markets in Londrina city, Parana and analyzed by the Most Probable Number (NMP enumeration using the Brilliant Green Bile Lactose Broth (BGBL and ColiSure™. There was a correlation of 0.80 betwee-n the mediums when the incubation time was 43 hours for total conforms. The low down occurrence of E. coffin the analyzed samples made impossible to comparate the performance of methods for this microorganism. Compfementary analysis showed a greater sensibility and especifity of the ColiSure™ in comparation with the BGBL. The CofiSure™ can be indicated as a substitute for the traditional method, with the advantage to be faster and easier.Na indústria láctea a detecção de microrganismos do grupo coliformes é utilizada como indicativo da higiene na produção do leite e de contaminação pós-pasteurizaçüo. Os métodos tradicionais para a enumeração de coliformes totais e fecais são trabalhosos, com tempo de incubação longo, de até 96 horas. Métodos rápidos para a detecção destes microrganismos têm sido desenvolvidos na área de microbiologia de alimentos. O ColiSure™ é um método rápido, que fornece resultados simultaneamente para a presença ou a ausência de coliformes totais e Escherichia coli em �

Escherichia Coli Removal from Water Using Electrophotocatalytic ...

African Journals Online (AJOL)

Michael Horsfall

inactivation of bacterial microorganisms in areas with low ... disinfection of water contaminated with fecal indicators such as E. coli ... media, brain heart infusion, sodium chloride, sodium hydroxide ... furnace at temperature 105 and 320°C f0r 60 min. For 2- and .... charge of E. coli logarithmic growth phase might affect the ...

The Escherichia coli transcriptome linked to growth fitness

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Bei-Wen Ying

2016-03-01

Full Text Available A series of Escherichia coli strains with varied genomic sequences were subjected to high-density microarray analyses to elucidate the fitness-correlated transcriptomes. Fitness, which is commonly evaluated by the growth rate during the exponential phase, is not only determined by the genome but is also linked to growth conditions, e.g., temperature. We previously reported genetic and environmental contributions to E. coli transcriptomes and evolutionary transcriptome changes in thermal adaptation. Here, we describe experimental details on how to prepare microarray samples that truly represent the growth fitness of the E. coli cells. A step-by-step record of sample preparation procedures that correspond to growing cells and transcriptome data sets that are deposited at the GEO database (GSE33212, GSE52770, GSE61739 are also provided for reference. Keywords: Transcriptome, Growth fitness, Escherichia coli, Microarray

Geographic relatedness and predictability of Escherichia coli along a peninsular beach complex of Lake Michigan

Science.gov (United States)

Nevers, M.B.; Shively, D.A.; Kleinheinz, G.T.; McDermott, C.M.; Schuster, W.; Chomeau, V.; Whitman, R.L.

2009-01-01

To determine more accurately the real-time concentration of fecal indicator bacteria (FIB) in beach water, predictive modeling has been applied in several locations around the Great Lakes to individual or small groups of similar beaches. Using 24 beaches in Door County, Wisconsin, we attempted to expand predictive models to multiple beaches of complex geography. We examined the importance of geographic location and independent variables and the consequential limitations for potential beach or beach group models. An analysis of Escherichia coli populations over 4 yr revealed a geographic gradient to the beaches, with mean E. coli concentrations decreasing with increasing distance from the city of Sturgeon Bay. Beaches grouped strongly by water type (lake, bay, Sturgeon Bay) and proximity to one another, followed by presence of a storm or creek outfall or amount of shoreline enclosure. Predictive models developed for beach groups commonly included wave height and cumulative 48-h rainfall but generally explained little E. coli variation (adj. R2 = 0.19-0.36). Generally low concentrations of E. coli at the beaches influenced the effectiveness of model results presumably because of low signal-to-noise ratios and the rarity of elevated concentrations. Our results highlight the importance of the sensitivity of regressors and the need for careful methods evaluation. Despite the attractiveness of predictive models as an alternative beach monitoring approach, it is likely that FIB fluctuations at some beaches defy simple prediction approaches. Regional, multi-beach, and individual beach predictive models should be explored alongside other techniques for improving monitoring reliability at Great Lakes beaches. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

The interaction of the protein lysozyme with bacteria E. coli observed using nanodiamond labelling

Energy Technology Data Exchange (ETDEWEB)

Perevedentseva, Elena; Cheng, C-Y; Chung, P-H; Tu, J-S; Hsieh, Y-H; Cheng, C-L [Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China)

2007-08-08

The application of a nanometre-sized diamond in Raman-detectable biolabelling is demonstrated in this study. The interaction of a lysozyme-nanodiamond complex with bacteria E. coli was observed via Raman mapping using the diamond Raman signal as the labelling marker. The results are compared with scanning electron microscope observations, and the adsorbed lysozyme's functionality is analysed. High antibacterial activity of lysozyme-nanodiamond complex was observed, equivalent to active lysozyme in solution. The results suggest that nanodiamond labelling can be effective and that it can be applied in ambient conditions without complicated sample pre-treatments.

E. coli Surface Properties Differ between Stream Water and Sediment Environments

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Xiao Liang

2016-11-01

Full Text Available The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10mM and 22˚C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity and extracellular polymeric substance (EPS composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli. A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli. Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli.

E. coli Surface Properties Differ between Stream Water and Sediment Environments.

Science.gov (United States)

Liang, Xiao; Liao, Chunyu; Thompson, Michael L; Soupir, Michelle L; Jarboe, Laura R; Dixon, Philip M

2016-01-01

The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water) under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10 mM and 22°C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity, and extracellular polymeric substance (EPS) composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli . A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli . Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG) 5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli .

Pathogenic Escherichia coli and food handlers in luxury hotels in Nairobi, Kenya.

Science.gov (United States)

Onyango, Abel O; Kenya, Eucharia U; Mbithi, John J N; Ng'ayo, Musa O

2009-11-01

The epidemiology and virulence properties of pathogenic Escherichia coli among food handlers in tourist destination hotels in Kenya are largely uncharacterized. This cross-sectional study among consenting 885 food handlers working in nine luxurious tourist hotels in Nairobi, Kenya determined the epidemiology, virulence properties, antibiotics susceptibility profiles and conjugation abilities of pathogenic Escherichia coli. Pathogenic Escherichia coli was detected among 39 (4.4%) subjects, including 1.8% enteroaggregative Escherichia coli (EAEC) harboring aggR genes, 1.2% enterotoxigenic Escherichia coli (ETEC) expressing both LT and STp toxins, 1.1% enteropathogenic Escherichia coli (EPEC) and 0.2% Shiga-like Escherichia coli (EHEC) both harboring eaeA and stx2 genes respectively. All the pathotypes had increased surface hydrophobicity. Using multivariate analyses, food handlers with loose stools were more likely to be infected with pathogenic Escherichia coli. Majority 53.8% of the pathotypes were resistant to tetracycline with 40.2% being multi-drug resistant. About 85.7% pathotypes trans-conjugated with Escherichia coli K12 F(-) NA(r) LA. The carriage of multi-drug resistant, toxin expressing pathogenic Escherichia coli by this population is of public health concern because exposure to low doses can result in infection. Screening food handlers and implementing public awareness programs is recommended as an intervention to control transmission of enteric pathogens.

Antimicrobial susceptibility patterns of E. coli from clinical sources in ...

African Journals Online (AJOL)

Background: Escherichia coli is the leading cause of urinary tract, ear, wound and other infections in humans. Increasing rates of antimicrobial resistance among E. coli is a growing concern worldwide. Objectives: The aim of this study was to determine the prevalence and antimicrobial susceptibility of E. coli from clinical ...

Incidence of Escherichia coli  - Glucuronidase Positive on Goat Milk

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Zorica Voşgan

2016-11-01

Full Text Available Papers on beta- glucuronidase sensitivity and specificity for identifying Escherichia coli in sources of environment, food, water, etc. have been published since 1976. In this study we conducted a review of the incidence of E. coli β- glucuronidase -positive in goat milk, obtained by hand milking throughout the lactation: spring, summer, autumn. The presence of E. coli in milk is considered both as a health indicator and a pathogenic factor capable of causing food poisoning. The determination of the E. coli β-glucuronidase-positive was carried using TBX medium by cultivating colonies typical blue at 440C. The absence of E. coli in milk yielded during the spring, when the animal milking is done three times a day, was found in the performed analyses; the same was observed during fall, when the milk production is lower and the milking is done once a day. The load of E. coli β-glucuronidase-positive was averaging 66.67 CFU/ml of goat milk, during the middle lactation period (July-August, in conditions of higher temperature. During this period, milking is done in the mountain zone, where the transhumance of animals takes place in summer. The presence of the species E. coli was also confirmed by microscopic examination. Attention should be paid to hygiene and milk should be immediately cooled, during hot weather, as E. coli can be a source of food poisoning.

Adsorption, sedimentation, and inactivation of E. coli within wastewater treatment wetlands.

Science.gov (United States)

Boutilier, L; Jamieson, R; Gordon, R; Lake, C; Hart, W

2009-09-01

Bacteria fate and transport within constructed wetlands must be understood if engineered wetlands are to become a reliable form of wastewater treatment. This study investigated the relative importance of microbial treatment mechanisms in constructed wetlands treating both domestic and agricultural wastewater. Escherichia coli (E. coli) inactivation, adsorption, and settling rates were measured in the lab within two types of wastewater (dairy wastewater lagoon effluent and domestic septic tank effluent). In situ E. coli inactivation was also measured within a domestic wastewater treatment wetland and the adsorption of E. coli was also measured within the wetland effluent. Inactivation of E. coli appears to be the most significant contributor to E. coli removal within the wastewaters and wetland environments examined in this study. E. coli survived longer within the dairy wastewater (DW) compared to the domestic wastewater treatment wetland water (WW). First order rate constants for E. coli inactivation within the WW in the lab ranged from 0.09 day(-1) (d(-1)) at 7.6 degrees C to 0.18d(-1) at 22.8 degrees C. The average in situ rate constant observed within the domestic wetland ranged from 0.02 d(-1) to 0.03 d(-1) at an average water temperature of 17 degrees C. First order rate constants for E. coli inactivation within the DW ranged from 0.01 d(-1) at 7.7 degrees C to 0.04 d(-1) at 24.6 degrees C. Calculated distribution coefficients (K(d)) were 19,000 mL g(-1), 324,000 mL g(-1), and 293 mL g(-1) for E. coli with domestic septic tank effluent (STE), treated wetland effluent (WLE), and DW, respectively. Approximately 50%, 20%, and 90% of E. coli were "free floating" or associated with particles 5 microm within both the STE and DW, settling did not appear to contribute to E. coli removal within sedimentation experiments, indicating that the particles the bacteria were associated with had very small settling velocities. The results of this study highlight the

Chromatin architecture and gene expression in Escherichia coli

DEFF Research Database (Denmark)

Willenbrock, Hanni; Ussery, David

2004-01-01

Two recent genome-scale analyses underscore the importance of DNA topology and chromatin structure in regulating transcription in Escherichia coli.......Two recent genome-scale analyses underscore the importance of DNA topology and chromatin structure in regulating transcription in Escherichia coli....

Epidemiology and clinical manifestations of enteroaggregative Escherichia coli

DEFF Research Database (Denmark)

Hebbelstrup Jensen, Betina; Olsen, Katharina E P; Struve, Carsten

2014-01-01

Enteroaggregative Escherichia coli (EAEC) represents a heterogeneous group of E. coli strains. The pathogenicity and clinical relevance of these bacteria are still controversial. In this review, we describe the clinical significance of EAEC regarding patterns of infection in humans, transmission...

Fosfomycin Resistance in Escherichia coli, Pennsylvania, USA.

Science.gov (United States)

Alrowais, Hind; McElheny, Christi L; Spychala, Caressa N; Sastry, Sangeeta; Guo, Qinglan; Butt, Adeel A; Doi, Yohei

2015-11-01

Fosfomycin resistance in Escherichia coli is rare in the United States. An extended-spectrum β-lactamase-producing E. coli clinical strain identified in Pennsylvania, USA, showed high-level fosfomycin resistance caused by the fosA3 gene. The IncFII plasmid carrying this gene had a structure similar to those found in China, where fosfomycin resistance is commonly described.

Escherichia coli in broiler chickens with airsacculitis

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Leandro S. Machado

2014-09-01

Full Text Available ABSTRACT. Machado L.S., do Nascimento E.R., Pereira V.L.A., Abreu D.L.C., Gouvea R. & Santos L.M.M. 2014. [Escherichia coli in broiler chickens with airsacculitis.] Escherichia coli em frangos de corte com aerossaculite. Revista Brasileira de Medicina Veterinária, 36(3:261-265, 2014. Departamento de Medicina Veterinária Preventiva e Saúde Pública, Faculdade de Veterinária, Universidade Federal Fluminense, Rua Dr. Vital Brazil Filho 64, Vital Brazil, Niterói, RJ 24230-340, Brazil. E-mail: leandromachadovet@yahoo.com.br The Brazilian poultry industry grows each year and becomes increasingly representative in the production and export of products. The health care with poultry have accompanied and favored this evolution, however, respiratory agents that affect the weight and carcass quality, continue to cause great damage to the poultry industry. Airsacculitis is considered the main cause of total and partial condemnation of carcasses of broilers, and has been attributed to Mycoplasmosis mostly caused by Mycoplasma gallisepticum (MG and Mycoplasma synoviae (MS and Escherichia coli. The aim of this study was to relate the positivity of MG / MS and E. coli detected by PCR as a risk factor for airsacculitis in condemnation of broilers in Health Inspection Service. We studied 30 broiler poultry slaughtered in a slaughterhouse under Federal Sanitary Inspection, located in the State of Rio de Janeiro. 30 chickens were randomly collected from different lots and tracheas obtained in each PCR. DNA was extracted by phenol-chloroform method and amplified using pairs of “primer”specific for MG, MS and E. coli. Of the 30 chickens analyzed by PCR, 30% (9/30 had lesions in air sacs. None of the birds showed infection with MG and/or MS PCR, however 33.3% (3/9 birds were positive for airsacculitis iss gene from E.coli. E.coli found in broiler chickens that were negative for mycoplasma airsacculitis, implying the presence of such bacteria may be sufficient

Recombinant L-Asparaginase from Zymomonas mobilis: A Potential New Antileukemic Agent Produced in Escherichia coli.

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Karen Einsfeldt

Full Text Available L-asparaginase is an enzyme used as a chemotherapeutic agent, mainly for treating acute lymphoblastic leukemia. In this study, the gene of L-asparaginase from Zymomonas mobilis was cloned in pET vectors, fused to a histidine tag, and had its codons optimized. The L-asparaginase was expressed extracellularly and intracellularly (cytoplasmically in Escherichia coli in far larger quantities than obtained from the microorganism of origin, and sufficient for initial cytotoxicity tests on leukemic cells. The in silico analysis of the protein from Z. mobilis indicated the presence of a signal peptide in the sequence, as well as high identity to other sequences of L-asparaginases with antileukemic activity. The protein was expressed in a bioreactor with a complex culture medium, yielding 0.13 IU/mL extracellular L-asparaginase and 3.6 IU/mL intracellular L-asparaginase after 4 h of induction with IPTG. The cytotoxicity results suggest that recombinant L-asparaginase from Z. mobilis expressed extracellularly in E.coli has a cytotoxic and cytostatic effect on leukemic cells.

Escherichia coli pathotypes in Pakistan from consecutive floods in 2010 and 2011.

Science.gov (United States)

Bokhari, Habib; Shah, Muhammad Ali; Asad, Saba; Akhtar, Sania; Akram, Muhammad; Wren, Brendan W

2013-03-01

This study compares Escherichia coli pathotypes circulating among children in Pakistan during the floods of 2010 and 2011 and from sporadic cases outside flood affected areas. Using multiplex polymerase chain reaction 115 of 205 stool samples (56.29%) were positive for diarrheagenic E. coli from specimens taken during the floods compared with 50 of 400 (12.5%) stool samples being positive for sporadic cases. The E. coli pathotypes were categorized as Enteropathogenic E. coli 33 (28.69%) and 13 (26%), Enterotoxigenic E. coli 29 (25.21%) and 15 (30%), Enteroaggregative E. coli 21 (18.2%) and 18 (36%), Enterohemorrhagic E. coli 5 (4.34%) and 1 (2%) from flood and sporadic cases, respectively. Furthermore, patients co-infected with more than one pathotype were 26 (22.60%) and 3 (6%) from flood and sporadic cases, respectively. The study shows an unexpectedly high rate of isolation of E. coli pathotypes suggesting Pakistan as an endemic region that requires active surveillance particularly during flood periods.

Experimental evolution of E. coli

Science.gov (United States)

Zhang, Mengshi

The evolution from unicellular to multicellular behavior is an essential step in the history of life. Our aim is to investigate the emergence of collective behavior in the model organism Escherichia coli (E. coli) and its selection advantages, such as better utilization of public goods. Our preliminary results suggest that the evolution of collective behavior may be a natural response to stressed conditions. Mailing address: Room 306 Science Centre North Block, The Chinese University of Hong Kong, Shatin, N.T. Hong Kong SAR. Phone: +852-3943-6354. Fax: +852-2603-5204. E-mail: mengshi0928@gmail.com.

Production and Purification Immunoglobulin against E. coli in Egg Yolk

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Mohammadreza Nassiri

2016-08-01

Full Text Available Introduction Chicken is the only avian species in which polyclonal antibodies, like IgG is transported from the hen to the egg yolk in a similar manner as the transport of mammalian IgG from the mother to the fetus. Immunoglobulin Y in the chicken is transported to the egg and accumulates in the egg yolk in large quantities. IgY is an egg yolk antibody that has been used widely for treatment and prevention of infections in humans and animal. IgY is used for passive protection of the pathogen infections such as Escherichia coli, bovine and human rotavirus, bovine coronavirus, salmonella, staphylococcus and Pseudomonas. IgY is a promising candidate as an alternative to antibiotics. Eschericha coli strains of serotype O157: H7 belongs to a family of pathogenic E. coli called enterohemorrhagic E. coli (EHEC strains responsible for hemorrhagic colitis, bloody or non-bloody diarrhea, and hemolytic uremic syndrome in humans. This strain of E. coli pathogenises by adhering to host intestinal epithelium and forming bacterial colonies. The purpose of this study was to produce and purify immunoglobulin Y against E. coli O157:H7 and develop specific polyclonal anti E. coli antibody in the egg yolk. Materials and Methods Sixteen-week-old laying hens (Mashhad, Iran were kept in individual cages with food and water ad libitum. Immunization of hens was performed by intramuscularly injecting killed E. coli O157: H7 with an equal volume of Freund’s complete adjuvant into two sides of chest area (Sigma, USA for the first immunization. Two booster immunizations followed up using complete and incomplete Freund’s adjuvants in two weeks interval. Freund’s adjuvant without antigen was injected to the control group. Two weeks after the last injection, the eggs were collected daily for eight weeks, marked and stored at 4 ºC. In order to IgY purification, eggs were collected. Purification of IgY from egg yolk was based on Polson and using PEG6000. Finally, the

Physicochemical Factors: Impact on Spermagglutination Induced by Escherichia coli

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Kiranjeet Kaur

2014-02-01

Full Text Available Motility is a sensitive parameter of sperm function which is predictive of its fertilization potential in vitro. The decrease in sperm motility may be associated with sperm agglutination and immobilization due to mere presence of bacteria or excretion of bacterial toxic products. Supplementation with various agents like sucrose, mannitol, calcium, and EDTA is well known to improve the sperm motility in vitro. The present study was designed to check any protective role exerted by the addition of different agents on spermatozoal motility against E. coli induced sperm agglutination. 52 semen specimens were screened for the presence of sperm-agglutinating strain of E. coli. Further, influence of various factors, namely, sugars, salts, and chelating agents was studied. Also, the impact of exposure to high temperature and alcohol on sperm-agglutinating efficiency of E. coli was observed. None of the factors could inhibit the sperm agglutination induced by E. coli, except high temperature suggesting the involvement of protein moiety. In addition, it was observed that agglutinating efficiency of E. coli was limited to spermatozoa and RBCs. It may be concluded that sperm-agglutinating property of E. coli is quite stable as various physicochemical factors tested did not show any negative effect on the same except high temperature.

Antibiotic resistance of Verotoxigenic Escherichia coli isolated from vegetables

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mojtaba boniadian

2017-01-01

Full Text Available Introduction: Human gastrointestinal disease caused by verotoxigenic Escherichia coli has been diagnosed for recent decades. Escherichia coli O157:H7 is the most important serotype of verotoxigenic Escherichia coli that cause hemolytic uremic syndrome and hemorrhagic colitis in humans. This study was conducted to determine the occurrence of verotoxigenic E. coli and antibiotic resistance of the isolates from vegetables. Materials and methods: A total of 500 fresh vegetable samples were collected randomly from retail shops in Shahrekord, Iran. E. coli was isolated and identified using bacteriological and biochemical tests. PCR method was used to identify the rbfE, stx1, stx2 and eae genes. Also, antibiotic resistance of the isolates was determined by disk diffusion method. Results: The results represented that among 25 isolates possess virulence genes, 40, 12 and 4% of the isolates contained eaeA, STx2, and both genes, respectively. But none of them contained H7, STx1, and rfbE genes. The antibiotic resistance pattern demonstrated that the isolates were highly resistant to Gentamycin and cefotoxime. Discussion and conclusion: The results of this study showed that the presence of verotoxigenic E.coli in vegetables; and high resistance of the isolates to antibiotics could be hazardous for public health.

Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

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Kwang-Ho Hur

Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

A sensitive biosensor using double-layer capillary based immunomagnetic separation and invertase-nanocluster based signal amplification for rapid detection of foodborne pathogen.

Science.gov (United States)

Huang, Fengchun; Zhang, Huilin; Wang, Lei; Lai, Weihua; Lin, Jianhan

2018-02-15

Combining double-layer capillary based high gradient immunomagnetic separation, invertase-nanocluster based signal amplification and glucose meter based signal detection, a novel biosensor was developed for sensitive and rapid detection of E. coli O157:H7 in this study. The streptavidin modified magnetic nanobeads (MNBs) were conjugated with the biotinylated polyclonal antibodies against E. coli O157:H7 to form the immune MNBs, which were captured by the high gradient magnetic field in the double-layer capillary to specifically separate and efficiently concentrate the target bacteria. Calcium chloride was used with the monoclonal antibodies against E. coli O157:H7 and the invertase to form the immune invertase-nanoclusters (INCs), which were used to react with the target bacteria to form the MNB-bacteria-INC complexes in the capillary. The sucrose was then injected into the capillary and catalyzed by the invertase on the complexes into the glucose, which was detected using the glucose meter to obtain the concentration of the glucose for final determination of the E. coli O157:H7 cells in the sample. A linear relationship between the readout of the glucose meter and the concentration of the E. coli O157:H7 cells (from 10 2 to 10 7 CFU/mL) was found and the lower detection limit of this biosensor was 79 CFU/mL. This biosensor might be extended for the detection of other foodborne pathogens by changing the antibodies and has shown the potential for the detection of foodborne pathogens in a large volume of sample to further increase the sensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Identifying subsurface detachment defects by acoustic tracing

Czech Academy of Sciences Publication Activity Database

Sklodowski, R.; Drdácký, Miloš; Sklodowski, M.

2013-01-01

Roč. 56, June (2013), s. 56-64 ISSN 0963-8695 R&D Projects: GA ČR(CZ) GBP105/12/G059 Institutional support: RVO:68378297 Keywords : acoustic excitation * plaster detachment defects * frequency response * inspection systems * signal processing Subject RIV: JN - Civil Engineering Impact factor: 1.717, year: 2013 http://www.sciencedirect.com/science/article/pii/S0963869513000303

Deuterium incorporation into Escherichia-coli proteins

DEFF Research Database (Denmark)

Lederer, H.; May, R. P.; Kjems, Jørgen

1986-01-01

Neutron small-angle scattering studies of single protein subunits in a protein-DNA complex require the adjustment of the neutron scattering-length densities of protein and DNA, which is attainable by specific deuteration of the protein. The neutron scattering densities of unlabelled DNA and DNA......-dependent RNA polymerase of Escherichia coli match when RNA polymerase is isolated from cells grown in a medium containing 46% D2O and unlabelled glucose as carbon source. Their contrasts vanish simultaneously in a dialysis buffer containing 65% D2O. An expression was evaluated which allows the calculation...... of the degree of deuteration and match point of any E. coli protein from the D2O content of the growth medium, taking the 2H incorporation into RNA polymerase amino acids to be representative for all amino acids in E. coli proteins. The small-angle scattering results, on which the calculation of the degree...

Comparative genetic screens in human cells reveal new regulatory mechanisms in WNT signaling

Science.gov (United States)

Lebensohn, Andres M; Dubey, Ramin; Neitzel, Leif R; Tacchelly-Benites, Ofelia; Yang, Eungi; Marceau, Caleb D; Davis, Eric M; Patel, Bhaven B; Bahrami-Nejad, Zahra; Travaglini, Kyle J; Ahmed, Yashi; Lee, Ethan; Carette, Jan E; Rohatgi, Rajat

2016-01-01

The comprehensive understanding of cellular signaling pathways remains a challenge due to multiple layers of regulation that may become evident only when the pathway is probed at different levels or critical nodes are eliminated. To discover regulatory mechanisms in canonical WNT signaling, we conducted a systematic forward genetic analysis through reporter-based screens in haploid human cells. Comparison of screens for negative, attenuating and positive regulators of WNT signaling, mediators of R-spondin-dependent signaling and suppressors of constitutive signaling induced by loss of the tumor suppressor adenomatous polyposis coli or casein kinase 1α uncovered new regulatory features at most levels of the pathway. These include a requirement for the transcription factor AP-4, a role for the DAX domain of AXIN2 in controlling β-catenin transcriptional activity, a contribution of glycophosphatidylinositol anchor biosynthesis and glypicans to R-spondin-potentiated WNT signaling, and two different mechanisms that regulate signaling when distinct components of the β-catenin destruction complex are lost. The conceptual and methodological framework we describe should enable the comprehensive understanding of other signaling systems. DOI: http://dx.doi.org/10.7554/eLife.21459.001 PMID:27996937

Rare Case of Polymicrobial Keratitis With Balantidium coli.

Science.gov (United States)

Hazarika, Manali; Pai H, Vijaya; Khanna, Vinay; Reddy, Harish; Tilak, Kriti; Chawla, Kiran

2016-12-01

To report a rare case of polymicrobial keratitis due to Balantidium coli and gram-negative bacteria, Pseudomonas aeruginosa and Klebsiella pneumoniae, in a soft contact lens (CL) wearer. We report a case of CL-related keratitis due to B. coli, P. aeruginosa, and K. pneumoniae. The culture of the corneal scrapings, the CL cleaning solution, and the CL revealed the growth of a rare ciliated parasite, B. coli, along with gram-negative bacteria, namely, P. aeruginosa and K. pneumoniae. The patient was successfully treated with topical broad-spectrum antibiotics and intravenous metronidazole. Polymicrobial keratitis has seldom been reported with B. coli as the causative agent. CL wear can be a risk factor for this infection. Treatment with topical antibiotics may not suffice, and the intravenous route of antiprotozoal drugs may be a useful adjunct. Increasing awareness, early diagnosis, and treatment may improve the final visual outcome.

Small regulatory RNAs control the multi-cellular adhesive lifestyle of Escherichia coli

DEFF Research Database (Denmark)

Jørgensen, Mikkel Girke; Nielsen, Jesper Sejrup; Boysen, Anders

2012-01-01

Small regulatory RNA molecules have recently been recognized as important regulatory elements of developmental processes in both eukaryotes and bacteria. We here describe a striking example in Escherichia coli that can switch between a single-cell motile lifestyle and a multi-cellular, sessile....... Our demonstration that basal expression of each of the three RNA species is sufficient to downregulate CsgD synthesis and prevent curli formation indicates that all play a prominent role in the curli regulatory network. Our findings provide the first clue as to how the Rcs signalling pathway...... negatively regulates curli synthesis and increase the number of small regulatory RNAs that act directly on the csgD mRNA to five....

Mathematical model of the SOS response regulation in wild-type Escherichia coli

International Nuclear Information System (INIS)

Aksenov, S.V.

1997-01-01

Regulation of the SOS response in Escherichia coli, which is a set of inducible cellular reactions introduced after DNA damage, is due to specific interaction of LexA and RecA proteins. LexA protein is a common repressor of the genes of the SOS system, and RecA protein, once transiently activated by the so-called SOS-inducing signal, promotes LexA protein destruction. We have described the SOS regulation by means of differential equations with regard to LexA and RecA concentrations elsewhere. The 'input' function for model equations is the level of the SOS-inducing signal against time. Here we present a means for calculating the concentration of single-stranded DNA (SOS-inducing signal) as a function of time in wild-type cells after ultraviolet irradiation. With model equations one can simulate kinetic curves of SOS regulatory proteins after DNA damage to survey the SOS response kinetics. Simulation of LexA protein kinetics agrees with experimental data. We compare simulated LexA kinetic curves in wild-type and uνr - mutant bacteria, which is useful in investigating the way uνrABC-dependent excision repair modulates the SOS response kinetics. Possible applications of the model to investigating various aspects of the SOS induction are discussed

Incidence of Escherichia coli O157:H7 in Thailand

International Nuclear Information System (INIS)

Sukhumungoon, P.

2015-01-01

Entero hemorrhagic Escherichia coli (EHEC) especially serotype O157:H7 is one of the important food-borne pathogens because it is able to produce crucial toxins Shiga. However, the outbreak of this organism in Thailand has not been reported. Antibody to O157 antigen was detected in some Thai populations and Shiga toxin-producing E. coli were detected in low numbers of clinical specimens. Interestingly, some E. coli that showed positive to O157 fimbriae probe and lack of virulence gene were isolated from certain patients and one isolate of E. coli O157:H7 which possessed stx1, stx2v was detected in a normal child. In addition, the incidence of E. coli O157:H7 strains were monitored by the samples from cattle and retail beef in Thailand although their inability to produce toxins or produce in a low concentration was demonstrated. This review discusses the incidences of E. coli O157 in clinical and environmental samples of Thailand including the transmission possibility of this bacterium across the Thai border through food trade. (author)

Reconstitution of active mycobacterial binuclear iron monooxygenase complex in Escherichia coli.

Science.gov (United States)

Furuya, Toshiki; Hayashi, Mika; Kino, Kuniki

2013-10-01

Bacterial binuclear iron monooxygenases play numerous physiological roles in oxidative metabolism. Monooxygenases of this type found in actinomycetes also catalyze various useful reactions and have attracted much attention as oxidation biocatalysts. However, difficulties in expressing these multicomponent monooxygenases in heterologous hosts, particularly in Escherichia coli, have hampered the development of engineered oxidation biocatalysts. Here, we describe a strategy to functionally express the mycobacterial binuclear iron monooxygenase MimABCD in Escherichia coli. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the mimABCD gene expression in E. coli revealed that the oxygenase components MimA and MimC were insoluble. Furthermore, although the reductase MimB was expressed at a low level in the soluble fraction of E. coli cells, a band corresponding to the coupling protein MimD was not evident. This situation rendered the transformed E. coli cells inactive. We found that the following factors are important for functional expression of MimABCD in E. coli: coexpression of the specific chaperonin MimG, which caused MimA and MimC to be soluble in E. coli cells, and the optimization of the mimD nucleotide sequence, which led to efficient expression of this gene product. These two remedies enabled this multicomponent monooxygenase to be actively expressed in E. coli. The strategy described here should be generally applicable to the E. coli expression of other actinomycetous binuclear iron monooxygenases and related enzymes and will accelerate the development of engineered oxidation biocatalysts for industrial processes.

[Virulence markers of Escherichia coli O1 strains].

Science.gov (United States)

Makarova, M A; Kaftyreva, L A; Grigor'eva, N S; Kicha, E V; Lipatova, L A

2011-01-01

To detect virulence genes in clinical isolates of Escherichia coli O1 using polymerase chain reaction (PCR). One hundred and twenty strains of E.coli O1 strains isolated from faeces of patients with acute diarrhea (n = 45) and healthy persons (n = 75) were studied. PCR with primers for rfb and fliC genes, which control synthesis of O- and H- antigens respectively, was used. Fourteen virulence genes (pap, aaf, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, st, and aer) were detected by PCR primers. K1-antigen was determined by Pastorex Meningo B/E. coli O1 kit (Bio-Rad). rfb gene controlling O-antigen synthesis in serogroup O1 as well as fliC gene controlling synthesis of H7 and K1 antigens were detected in all strains. Thus all E. coli strains had antigenic structure O1:K1 :H-:F7. Virulence genes aafl, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, and st were not detected. All strains owned pap and aer genes regardless of the presence of acute diarrhea symptoms. It was shown that E. coli O1:KI:H-:F7 strains do not have virulence genes which are characteristic for diarrhea-causing Escherichia. In accordance with the presence of pap and aer genes they could be attributed to uropathogenic Escherichia (UPEC) or avian-pathogenic Escherichia (APEC). It is necessary to detect virulence factors in order to determine E. coli as a cause of intestinal infection.

Pathogenic Potential to Humans of Bovine Escherichia coli O26, Scotland

Science.gov (United States)

Rosser, Tracy; Allison, Lesley J.; Courcier, Emily; Evans, Judith; McKendrick, Iain J.; Pearce, Michael C.; Handel, Ian; Caprioli, Alfredo; Karch, Helge; Hanson, Mary F.; Pollock, Kevin G.J.; Locking, Mary E.; Woolhouse, Mark E.J.; Matthews, Louise; Low, J. Chris; Gally, David L.

2012-01-01

Escherichia coli O26 and O157 have similar overall prevalences in cattle in Scotland, but in humans, Shiga toxin–producing E. coli O26 infections are fewer and clinically less severe than E. coli O157 infections. To investigate this discrepancy, we genotyped E. coli O26 isolates from cattle and humans in Scotland and continental Europe. The genetic background of some strains from Scotland was closely related to that of strains causing severe infections in Europe. Nonmetric multidimensional scaling found an association between hemolytic uremic syndrome (HUS) and multilocus sequence type 21 strains and confirmed the role of stx2 in severe human disease. Although the prevalences of E. coli O26 and O157 on cattle farms in Scotland are equivalent, prevalence of more virulent strains is low, reducing human infection risk. However, new data on E. coli O26–associated HUS in humans highlight the need for surveillance of non-O157 enterohemorrhagic E. coli and for understanding stx2 phage acquisition. PMID:22377426

Isolation and genomic characterization of Escherichia coli O157:NM ...

African Journals Online (AJOL)

Human diseases caused by Escherichia coli O157:NM and E. coli O157:H7 strains have been reported throughout the world. In developed countries, serotype O157:H7 represents the major cause of human diseases; however, there have been increasing reports of non-O157 Shiga toxin (Stx)-producing E. coli strains ...

77 FR 58091 - Risk-Based Sampling of Beef Manufacturing Trimmings for Escherichia coli (E. coli) O157:H7 and...

Science.gov (United States)

2012-09-19

... for exposure of carcasses and parts to any contamination or food safety hazard during the removal of... DEPARTMENT OF AGRICULTURE Food Safety and Inspection Service [Docket No. FSIS-2012-0020] Risk-Based Sampling of Beef Manufacturing Trimmings for Escherichia coli (E. coli) O157:H7 and Plans for Beef...

Nutrient transitions are a source of persisters in Escherichia coli biofilms.

Directory of Open Access Journals (Sweden)

Stephanie M Amato

Full Text Available Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.

Nutrient transitions are a source of persisters in Escherichia coli biofilms.

Science.gov (United States)

Amato, Stephanie M; Brynildsen, Mark P

2014-01-01

Chronic and recurrent infections have been attributed to persisters in biofilms, and despite this importance, the mechanisms of persister formation in biofilms remain unclear. The plethora of biofilm characteristics that could give rise to persisters, including slower growth, quorum signaling, oxidative stress, and nutrient heterogeneity, have complicated efforts to delineate formation pathways that generate persisters during biofilm development. Here we sought to specifically determine whether nutrient transitions, which are a common metabolic stress encountered within surface-attached communities, stimulate persister formation in biofilms and if so, to then identify the pathway. To accomplish this, we established an experimental methodology where nutrient availability to biofilm cells could be controlled exogenously, and then used that method to discover that diauxic carbon source transitions stimulated persister formation in Escherichia coli biofilms. Previously, we found that carbon source transitions stimulate persister formation in planktonic E. coli cultures, through a pathway that involved ppGpp and nucleoid-associated proteins, and therefore, tested the functionality of that pathway in biofilms. Biofilm persister formation was also found to be dependent on ppGpp and nucleoid-associated proteins, but the importance of specific proteins and enzymes between biofilm and planktonic lifestyles was significantly different. Data presented here support the increasingly appreciated role of ppGpp as a central mediator of bacterial persistence and demonstrate that nutrient transitions can be a source of persisters in biofilms.

Escherichia coli ST131, an Intriguing Clonal Group

Science.gov (United States)

Bertrand, Xavier; Madec, Jean-Yves

2014-01-01

SUMMARY In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum β-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131. PMID:24982321

Detection of Escherichia coli O157:H7 and Salmonella in ground beef by a bead-free quantum dot-facilitated isolation method.

Science.gov (United States)

Wang, Luxin; Wu, Chung-Shieh; Fan, Xudong; Mustapha, Azlin

2012-05-01

The aims of this study were to introduce a new immunological bead-free cell detection method using quantum dots (QDs) as reporter markers for foodborne pathogen detection. QDs are nanosized particles with long-term photostability, high quantum yield, broad absorption spectra, and narrow, symmetric emission and high signal-to-noise ratio. The chemical compound [(1-ethyl-3-3-dimethylaminopropyl) carbodiimide hydrochloride] (EDC) and protein A were used as crosslinkers for manufacturing QD-antibody conjugates. To minimize the inhibition of QD fluorescence by the magnetic beads, the beads were removed after the primary pathogen isolation and before fluorescence measurement. Detection signals were increased four-fold after employing the bead-free isolation method. With a 24-h enrichment, the bead-free QD-facilitated detection method was able to detect 10 CFU/g Escherichia coli O157:H7 and Salmonella from artificially contaminated ground beef. To our knowledge, this detection method is the first research that combined a new EDC-protein A QD-labeling technique and bead-free fluorescence measurement to detect E. coli O157:H7 and Salmonella in ground beef. Copyright © 2012 Elsevier B.V. All rights reserved.

Sign epistasis caused by hierarchy within signalling cascades.

Science.gov (United States)

Nghe, Philippe; Kogenaru, Manjunatha; Tans, Sander J

2018-04-13

Sign epistasis is a central evolutionary constraint, but its causal factors remain difficult to predict. Here we use the notion of parameterised optima to explain epistasis within a signalling cascade, and test these predictions in Escherichia coli. We show that sign epistasis arises from the benefit of tuning phenotypic parameters of cascade genes with respect to each other, rather than from their complex and incompletely known genetic bases. Specifically, sign epistasis requires only that the optimal phenotypic parameters of one gene depend on the phenotypic parameters of another, independent of other details, such as activating or repressing nature, position within the cascade, intra-genic pleiotropy or genotype. Mutational effects change sign more readily in downstream genes, indicating that optimising downstream genes is more constrained. The findings show that sign epistasis results from the inherent upstream-downstream hierarchy between signalling cascade genes, and can be addressed without exhaustive genotypic mapping.

The λ prophage induction in lysogens E.coli by exposure to ionizing radiation of different LET

International Nuclear Information System (INIS)

Bonev, M.N.; Kozubek, S.; Krasavin, E.A.; Cherevatenko, A.P.

1988-01-01

The dependence of λ prophage induction on the dose I(D) in lysogens of E.coli irradiated by ionizing radiation with different LET(L) has been investigated. The role of the balance of pleiotropic activities of RecA protein has been analysed. The expermental data were fitted by the function I(D)αD(1-exp(-D 0 -1 D))exp(-βD). The increase of induction potency α with increasing L was connected with increasing production of DNA lesions which are a signal for the SOS-system induction

Glycan-functionalized diamond nanoparticles as potent E. coli anti-adhesives

Science.gov (United States)

Barras, Alexandre; Martin, Fernando Ariel; Bande, Omprakash; Baumann, Jean-Sébastien; Ghigo, Jean-Marc; Boukherroub, Rabah; Beloin, Christophe; Siriwardena, Aloysius; Szunerits, Sabine

2013-02-01

Bacterial attachment and subsequent biofilm formation on biotic surfaces or medical devices is an increasing source of infections in clinical settings. A large proportion of these biofilm-related infections are caused by Escherichia coli, a major nosocomial pathogen, in which the major adhesion factor is the FimH adhesin located at the tip of type 1 fimbriae. Inhibition of FimH-mediated adhesion has been identified as an efficient antibiotic-alternative strategy to potentially reduce E. coli-related infections. In this article we demonstrate that nanodiamond particles, covently modified with mannose moieties by a ``click'' chemistry approach, are able to efficiently inhibit E. coli type 1 fimbriae-mediated adhesion to eukaryotic cells with relative inhibitory potency (RIP) of as high as 9259 (bladder cell adhesion assay), which is unprecedented when compared with RIP values previously reported for alternate multivalent mannose-functionalized nanostructures designed to inhibit E. coli adhesion. Also remarkable is that these novel mannose-modified NDs reduce E. coli biofilm formation, a property previously not observed for multivalent glyco-nanoparticles and rarely demonstrated for other multivalent or monovalent mannose glycans. This work sets the stage for the further evaluation of these novel NDs as an anti-adhesive therapeutic strategy against E. coli-derived infections.Bacterial attachment and subsequent biofilm formation on biotic surfaces or medical devices is an increasing source of infections in clinical settings. A large proportion of these biofilm-related infections are caused by Escherichia coli, a major nosocomial pathogen, in which the major adhesion factor is the FimH adhesin located at the tip of type 1 fimbriae. Inhibition of FimH-mediated adhesion has been identified as an efficient antibiotic-alternative strategy to potentially reduce E. coli-related infections. In this article we demonstrate that nanodiamond particles, covently modified with

High-density transcriptional initiation signals underline genomic islands in bacteria.

Directory of Open Access Journals (Sweden)

Qianli Huang

Full Text Available Genomic islands (GIs, frequently associated with the pathogenicity of bacteria and having a substantial influence on bacterial evolution, are groups of "alien" elements which probably undergo special temporal-spatial regulation in the host genome. Are there particular hallmark transcriptional signals for these "exotic" regions? We here explore the potential transcriptional signals that underline the GIs beyond the conventional views on basic sequence composition, such as codon usage and GC property bias. It showed that there is a significant enrichment of the transcription start positions (TSPs in the GI regions compared to the whole genome of Salmonella enterica and Escherichia coli. There was up to a four-fold increase for the 70% GIs, implying high-density TSPs profile can potentially differentiate the GI regions. Based on this feature, we developed a new sliding window method GIST, Genomic-island Identification by Signals of Transcription, to identify these regions. Subsequently, we compared the known GI-associated features of the GIs detected by GIST and by the existing method Islandviewer to those of the whole genome. Our method demonstrates high sensitivity in detecting GIs harboring genes with biased GI-like function, preferred subcellular localization, skewed GC property, shorter gene length and biased "non-optimal" codon usage. The special transcriptional signals discovered here may contribute to the coordinate expression regulation of foreign genes. Finally, by using GIST, we detected many interesting GIs in the 2011 German E. coli O104:H4 outbreak strain TY-2482, including the microcin H47 system and gene cluster ycgXEFZ-ymgABC that activates the production of biofilm matrix. The aforesaid findings highlight the power of GIST to predict GIs with distinct intrinsic features to the genome. The heterogeneity of cumulative TSPs profiles may not only be a better identity for "alien" regions, but also provide hints to the special

Antibiotic resistant Salmonella and Escherichia coli isolated from ...

African Journals Online (AJOL)

Results: A hundred and four indigenous chicken rectal swabs were analysed, of which 67.3% were contaminated with Escherichia coli and 12.5% with Salmonella typhimurium. Seventy Escherichia coli isolates showed resistance phenotypes to one, two or more antibiotics. The most common antimicrobial resistance pattern ...

Juvenile hormone signaling during reproduction and development of the linden bug, Pyrrhocoris apterus

Czech Academy of Sciences Publication Activity Database

Smýkal, Vlastimil; Bajgar, Adam; Provazník, Jan; Fexová, Silvie; Buřičová, Marcela; Takaki, Keiko; Hodková, Magdalena; Jindra, Marek; Doležel, David

2014-01-01

Roč. 45, č. 1 (2014), s. 69-76 ISSN 0965-1748 R&D Projects: GA ČR GAP502/10/1612; GA AV ČR IAA500960906 EU Projects: European Commission(XE) 316304 - MODBIOLIN Grant - others:INsecTIME(CZ) 316790; Marie Curie Fellowship Award(CZ) 276569 Program:FP7-PEOPLE Institutional support: RVO:60077344 Keywords : methoprene-tolerant * bHLH-PAS * diapuase Subject RIV: ED - Physiology Impact factor: 3.450, year: 2014 http://www.sciencedirect.com/science/article/pii/S0965174813002130#

Captive wild birds as reservoirs of enteropathogenic E. coli (EPEC) and Shiga-toxin producing E. coli (STEC).

Science.gov (United States)

Sanches, Lilian Aparecida; Gomes, Marcelo da Silva; Teixeira, Rodrigo Hidalgo Friciello; Cunha, Marcos Paulo Vieira; Oliveira, Maria Gabriela Xavier de; Vieira, Mônica Aparecida Midolli; Gomes, Tânia Aparecida Tardelli; Knobl, Terezinha

Psittacine birds have been identified as reservoirs of diarrheagenic Escherichia coli, a subset of pathogens associated with mortality of children in tropical countries. The role of other orders of birds as source of infection is unclear. The aim of this study was to perform the molecular diagnosis of infection with diarrheagenic E. coli in 10 different orders of captive wild birds in the state of São Paulo, Brazil. Fecal samples were analyzed from 516 birds belonging to 10 orders: Accipitriformes, Anseriformes, Columbiformes, Falconiformes, Galliformes, Passeriformes, Pelecaniformes, Piciformes, Psittaciformes and Strigiformes. After isolation, 401 E. coli strains were subjected to multiplex PCR system with amplification of genes eae and bfp (EPEC), stx1 and stx2 for STEC. The results of these tests revealed 23/401 (5.74%) positive strains for eae gene, 16/401 positive strains for the bfp gene (3.99%) and 3/401 positive for stx2 gene (0.75%) distributed among the orders of Psittaciformes, Strigiformes and Columbiformes. None of strains were positive for stx1 gene. These data reveal the infection by STEC, typical and atypical EPEC in captive birds. The frequency of these pathotypes is low and restricted to few orders, but the data suggest the potential public health risk that these birds represent as reservoirs of diarrheagenic E. coli. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Genome analysis of E. coli isolated from Crohn's disease patients.

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Rakitina, Daria V; Manolov, Alexander I; Kanygina, Alexandra V; Garushyants, Sofya K; Baikova, Julia P; Alexeev, Dmitry G; Ladygina, Valentina G; Kostryukova, Elena S; Larin, Andrei K; Semashko, Tatiana A; Karpova, Irina Y; Babenko, Vladislav V; Ismagilova, Ruzilya K; Malanin, Sergei Y; Gelfand, Mikhail S; Ilina, Elena N; Gorodnichev, Roman B; Lisitsyna, Eugenia S; Aleshkin, Gennady I; Scherbakov, Petr L; Khalif, Igor L; Shapina, Marina V; Maev, Igor V; Andreev, Dmitry N; Govorun, Vadim M

2017-07-19

Escherichia coli (E. coli) has been increasingly implicated in the pathogenesis of Crohn's disease (CD). The phylogeny of E. coli isolated from Crohn's disease patients (CDEC) was controversial, and while genotyping results suggested heterogeneity, the sequenced strains of E. coli from CD patients were closely related. We performed the shotgun genome sequencing of 28 E. coli isolates from ten CD patients and compared genomes from these isolates with already published genomes of CD strains and other pathogenic and non-pathogenic strains. CDEC was shown to belong to A, B1, B2 and D phylogenetic groups. The plasmid and several operons from the reference CD-associated E. coli strain LF82 were demonstrated to be more often present in CDEC genomes belonging to different phylogenetic groups than in genomes of commensal strains. The operons include carbon-source induced invasion GimA island, prophage I, iron uptake operons I and II, capsular assembly pathogenetic island IV and propanediol and galactitol utilization operons. Our findings suggest that CDEC are phylogenetically diverse. However, some strains isolated from independent sources possess highly similar chromosome or plasmids. Though no CD-specific genes or functional domains were present in all CD-associated strains, some genes and operons are more often found in the genomes of CDEC than in commensal E. coli. They are principally linked to gut colonization and utilization of propanediol and other sugar alcohols.

The propagation of Escherichia Coli and of conservative tracers. A comparison

International Nuclear Information System (INIS)

Alexander, I.; Seiler, K.P.

1982-01-01

The propagation of Escherichia Coli (ATCC 11229, Gelsenkirchen) is compared with that of conservative tracers in groundwater. The experiments were performed with injection quantities of 10 7 , 10 8 , 10 10 and 10 11 of Escherichia Coli. Both, bacteria and conservative tracers pass their maximum at the same instant in the observation gauges. With injection quantities of more than 10 8 , the propagation of the Escherichia Coli sets in at the same time as it begins with the dyes. When the quantities range below 10 8 , the propagation begins after that of conservative tracers, because Coli bacteria were measured with a lower degree of detecting sensitivity than the tracers. With Coli injection quantities ranging above 10 10 , an increased filtering of these bacteria can be observed. Coli bacteria propagate more laterally than conservative tracers, however it could not be proved that this lateral propagation depends on the bacteria concentration. (orig.) [de

Uropathogenic E. coli Exploit CEA to Promote Colonization of the Urogenital Tract Mucosa

Science.gov (United States)

Muenzner, Petra; Kengmo Tchoupa, Arnaud; Klauser, Benedikt; Brunner, Thomas; Putze, Johannes; Dobrindt, Ulrich; Hauck, Christof R.

2016-01-01

Attachment to the host mucosa is a key step in bacterial pathogenesis. On the apical surface of epithelial cells, members of the human carcinoembryonic antigen (CEA) family are abundant glycoproteins involved in cell-cell adhesion and modulation of cell signaling. Interestingly, several gram-negative bacterial pathogens target these receptors by specialized adhesins. The prototype of a CEACAM-binding pathogen, Neisseria gonorrhoeae, utilizes colony opacity associated (Opa) proteins to engage CEA, as well as the CEA-related cell adhesion molecules CEACAM1 and CEACAM6 on human epithelial cells. By heterologous expression of neisserial Opa proteins in non-pathogenic E. coli we find that the Opa protein-CEA interaction is sufficient to alter gene expression, to increase integrin activity and to promote matrix adhesion of infected cervical carcinoma cells and immortalized vaginal epithelial cells in vitro. These CEA-triggered events translate in suppression of exfoliation and improved colonization of the urogenital tract by Opa protein-expressing E. coli in CEA-transgenic compared to wildtype mice. Interestingly, uropathogenic E. coli expressing an unrelated CEACAM-binding protein of the Afa/Dr adhesin family recapitulate the in vitro and in vivo phenotype. In contrast, an isogenic strain lacking the CEACAM-binding adhesin shows reduced colonization and does not suppress epithelial exfoliation. These results demonstrate that engagement of human CEACAMs by distinct bacterial adhesins is sufficient to blunt exfoliation and to promote host infection. Our findings provide novel insight into mucosal colonization by a common UPEC pathotype and help to explain why human CEACAMs are a preferred epithelial target structure for diverse gram-negative bacteria to establish a foothold on the human mucosa. PMID:27171273

Impact of intramammary treatment on gene expression profiles in bovine Escherichia coli mastitis.

Science.gov (United States)

Sipka, Anja; Klaessig, Suzanne; Duhamel, Gerald E; Swinkels, Jantijn; Rainard, Pascal; Schukken, Ynte

2014-01-01

Clinical mastitis caused by E. coli accounts for significant production losses and animal welfare concerns on dairy farms worldwide. The benefits of therapeutic intervention in mild to moderate cases are incompletely understood. We investigated the effect of intramammary treatment with cefapirin alone or in combination with prednisolone on gene expression profiles in experimentally-induced E. coli mastitis in six mid-lactating Holstein Friesian cows. Cows were challenged with E. coli in 3 quarters and received 4 doses of 300 mg cefapirin in one quarter and 4 doses of 300 mg cefapirin together with 20 mg prednisolone in another quarter. At 24 h (n = 3) or 48 h (n = 3) post-challenge, tissue samples from control and treated quarters were collected for microarray analysis. Gene expression analysis of challenged, un-treated quarters revealed an up-regulation of transcripts associated with immune response functions compared to un-challenged quarters. Both treatments resulted in down-regulation of these transcripts compared to challenged, un-treated quarters most prominently for genes representing Chemokine and TLR-signaling pathways. Gene expression of Lipopolysaccharide Binding Protein (LBP), CCL2 and CXCL2 were only significantly down-regulated in cefapirin-prednisolone-treated quarters compared to un-treated controls. Down-regulation of chemokines was further confirmed on the basis of protein levels in milk whey for CXCL1, CXCL2 and CXCL8 in both treatments with a greater decrease in cefapirin-prednisolone-treated quarters. The data reveal a significant effect of treatment on cell recruitment with a more pronounced effect in cefapirin-prednisolone treated quarters. Provided a rapid bacteriological clearance, combination therapy may prevent neutrophil-induced tissue damage and promote recovery of the gland.

Drug Resistance Patterns of Escherichia coli in Ethiopia: A Meta-Analysis.

Science.gov (United States)

Tuem, Kald Beshir; Gebre, Abadi Kahsu; Atey, Tesfay Mehari; Bitew, Helen; Yimer, Ebrahim M; Berhe, Derbew Fikadu

2018-01-01

Antimicrobial drug resistance is a global threat for treatment of infectious diseases and costs life and money and threatens health delivery system's effectiveness. The resistance of E. coli to frequently utilized antimicrobial drugs is becoming a major challenge in Ethiopia. However, there is no inclusive countrywide study. Therefore, this study intended to assess the prevalence of E. coli resistance and antimicrobial-specific resistance pattern among E. coli clinical isolates in Ethiopia. Articles were retrieved from PubMed, Embase, and grey literature from 2007 to 2017. The main outcome measures were overall E. coli and drug-specific resistance patterns. A random-effects model was used to determine pooled prevalence with 95% confidence interval (CI), using DerSimonian and Laird method. In addition, subgroup analysis was conducted to improve the outcome. The study bias was assessed by Begg's funnel plot. This study was registered in PROSPERO as follows: PROSPERO 2017: CRD42017070106. Of 164 articles retrieved, 35 articles were included. A total of 19,235 study samples participated in the studies and 2,635 E. coli strains were isolated. Overall, E. coli antibacterial resistance was 45.38% (95% confidence interval (CI): 33.50 to 57.27). The resistance pattern ranges from 62.55% in Addis Ababa to 27.51% in Tigray region. The highest resistance of E. coli reported was to ampicillin (83.81%) and amoxicillin (75.79%), whereas only 13.55% of E. coli isolates showed resistance to nitrofurantoin. E. coli antimicrobial resistance remains high with disparities observed among regions. The bacterium was found to be highly resistant to aminopenicillins. The finding implies the need for effective prevention strategies for the E. coli drug resistance and calls for multifaceted approaches with full involvement of all stakeholders.

Immunopurification of adenomatous polyposis coli (APC) proteins

Science.gov (United States)

2013-01-01

Background The adenomatous polyposis coli (APC) tumour suppressor gene encodes a 2843 residue (310 kDa) protein. APC is a multifunctional protein involved in the regulation of β-catenin/Wnt signalling, cytoskeletal dynamics and cell adhesion. APC mutations occur in most colorectal cancers and typically result in truncation of the C-terminal half of the protein. Results In order to investigate the biophysical properties of APC, we have generated a set of monoclonal antibodies which enable purification of recombinant forms of APC. Here we describe the characterisation of these anti-APC monoclonal antibodies (APC-NT) that specifically recognise endogenous APC both in solution and in fixed cells. Full-length APC(1–2843) and cancer-associated, truncated APC proteins, APC(1–1638) and APC(1–1311) were produced in Sf9 insect cells. Conclusions Recombinant APC proteins were purified using a two-step affinity approach using our APC-NT antibodies. The purification of APC proteins provides the basis for detailed structure/function analyses of full-length, cancer-truncated and endogenous forms of the protein. PMID:24156781

Evaluation of Escherichia coli viability by flow cytometry: A method for determining bacterial responses to antibiotic exposure.

Science.gov (United States)

Boi, Paola; Manti, Anita; Pianetti, Anna; Sabatini, Luigia; Sisti, Davide; Rocchi, Marco Bruno; Bruscolini, Francesca; Galluzzi, Luca; Papa, Stefano

2015-01-01

In this study, we check for the presence of specific resistance genes by polymerase chain reaction (PCR) and then we used flow cytometry (FCM) to evaluate antibiotic-induced effects in different strains of Escherichia coli (E. coli). The presence of resistance genes was investigated by PCR in 10 strains of E. coli isolated from Foglia River. Bacterial responses to different antibiotics were also tested with FCM techniques by evaluating both the degree of decrease in viability and the light scatter changes in all of the strains. PCR revealed that only one strain exhibits the presence of one resistance gene. Despite this, analyses of strains using FCM evidenced the presence of viable subpopulations after antibiotic treatment. Furthermore, analyses of scatter signals revealed profound changes in the Forward Scatter and Side Scatter of the bacterial populations as a consequence of antibiotic exposure, confirming the viability and membrane potential data. The riverine strains were in general less sensitive to antibiotics than the reference strain (ATCC 25922). Antibiotic resistance is a widespread phenomena. The multiparametric approach based on FCM used in this study, providing results about different aspects (cell viability, membrane potential, light scatter changes), may overcome the limitation of PCR and could represent an adequate method for the evaluation of bacteria responses to antibiotic exposure. © 2014 International Clinical Cytometry Society.

Highly sensitive immunoassay based on E. coli with autodisplayed Z-domain

International Nuclear Information System (INIS)

Jose, Joachim; Park, Min; Pyun, Jae-Chul

2010-01-01

The Z-domain of protein A has been known to bind specifically to the F c region of antibodies (IgGs). In this work, the Z-domain of protein A was expressed on the outer membrane of Escherichia coli by using 'Autodisplay' technology as a fusion protein of autotransport domain. The E. coli with autodisplayed Z-domain was applied to the sandwich-type immunoassay as a solid-support of detection-antibodies against a target analyte. For the feasibility demonstration of the E. coli based immunoassay, C-reactive protein (CRP) assay was carried out by using E. coli with autodisplayed Z-domain. The limit of detection (LOD) and binding capacity of the E. coli based immunoassay were estimated to be far more sensitive than the conventional ELISA. Such a far higher sensitivity of E. coli based immunoassay than conventional ELISA was explained by the orientation control of immobilized antibodies and the mobility of E. coli in assay matrix. From the test results of 45 rheumatoid arthritis (RA) patients' serum and 15 healthy samples, a cut-off value was established to have optimal sensitivity and selectivity values for RA. The CRP test result of each individual sample was compared with ELISA which is the reference method for RA diagnosis. From this work, the E. coli with Z-domain was proved to be feasible for the medical diagnosis based on sandwich-type immunoassay.

Replication and Transcription of Eukaryotic DNA in Esherichia coli

Science.gov (United States)

Morrow, John F.; Cohen, Stanley N.; Chang, Annie C. Y.; Boyer, Herbert W.; Goodman, Howard M.; Helling, Robert B.

1974-01-01

Fragments of amplified Xenopus laevis DNA, coding for 18S and 28S ribosomal RNA and generated by EcoRI restriction endonuclease, have been linked in vitro to the bacterial plasmid pSC101; and the recombinant molecular species have been introduced into E. coli by transformation. These recombinant plasmids, containing both eukaryotic and prokaryotic DNA, replicate stably in E. coli. RNA isolated from E. coli minicells harboring the plasmids hybridizes to amplified X. laevis rDNA. Images PMID:4600264

Status of the uranium upgrade of ATLAS

International Nuclear Information System (INIS)

Bollinger, L.M.; Billquist, P.J.; Bogaty, J.M.; Clifft, B.E.; Markovich, P.; Munson, F.H.; Pardo, R.C.; Shepard, K.W.; Zinkann, G.P.

1991-01-01

The ATLAS Positive Ion Injector (PII) is designed to replace the tandem injector for the ATLAS heavy-ion facility. When the PII project is complete, ATLAS will be able to accelerate all ions through uranium to energies above the Coulomb barrier. PII consists of an ECR ion source on a 350 KV platform and a very low-velocity superconducting linac. The linac is composed of an independently-phased array of superconducting four-gap interdigital resonators which accelerate over a velocity range of .007c to .05c. the PII project is approximately 75% complete. Beam tests and experiments using the partially completed PII have demonstrated that the technical design goals are being met. The design, construction status, and results of recent operational experience using the PII will be discussed. 10 refs., 2 figs., 1 tab

Status of the uranium upgrade of ATLAS

Energy Technology Data Exchange (ETDEWEB)

Bollinger, L.M.; Billquist, P.J.; Bogaty, J.M.; Clifft, B.E.; Markovich, P.; Munson, F.H.; Pardo, R.C.; Shepard, K.W.; Zinkann, G.P.

1991-01-01

The ATLAS Positive Ion Injector (PII) is designed to replace the tandem injector for the ATLAS heavy-ion facility. When the PII project is complete, ATLAS will be able to accelerate all ions through uranium to energies above the Coulomb barrier. PII consists of an ECR ion source on a 350 KV platform and a very low-velocity superconducting linac. The linac is composed of an independently-phased array of superconducting four-gap interdigital resonators which accelerate over a velocity range of .007c to .05c. the PII project is approximately 75% complete. Beam tests and experiments using the partially completed PII have demonstrated that the technical design goals are being met. The design, construction status, and results of recent operational experience using the PII will be discussed. 10 refs., 2 figs., 1 tab.

Antibiotic Resistance and Virulence Properties in Escherichia coli ...

African Journals Online (AJOL)

This study determined E. coli resistance to commonly used antibiotics together with their virulence properties in Ile-Ife, Nigeria. A total of 137 E. coli isolates from cases of urinary tract infection were tested for their sensitivity to commonly used antibiotics and possession of virulence factors using standard methods.

The E. coli monothiol glutaredoxin GrxD forms homodimeric and heterodimeric FeS cluster containing complexes.

Science.gov (United States)

Yeung, N; Gold, B; Liu, N L; Prathapam, R; Sterling, H J; Willams, E R; Butland, G

2011-10-18

Monothiol glutaredoxins (mono-Grx) represent a highly evolutionarily conserved class of proteins present in organisms ranging from prokaryotes to humans. Mono-Grxs have been implicated in iron sulfur (FeS) cluster biosynthesis as potential scaffold proteins and in iron homeostasis via an FeS-containing complex with Fra2p (homologue of E. coli BolA) in yeast and are linked to signal transduction in mammalian systems. However, the function of the mono-Grx in prokaryotes and the nature of an interaction with BolA-like proteins have not been established. Recent genome-wide screens for E. coli genetic interactions reported the synthetic lethality (combination of mutations leading to cell death; mutation of only one of these genes does not) of a grxD mutation when combined with strains defective in FeS cluster biosynthesis (isc operon) functions [Butland, G., et al. (2008) Nature Methods 5, 789-795]. These data connected the only E. coli mono-Grx, GrxD to a potential role in FeS cluster biosynthesis. We investigated GrxD to uncover the molecular basis of this synthetic lethality and observed that GrxD can form FeS-bound homodimeric and BolA containing heterodimeric complexes. These complexes display substantially different spectroscopic and functional properties, including the ability to act as scaffold proteins for intact FeS cluster transfer to the model [2Fe-2S] acceptor protein E. coli apo-ferredoxin (Fdx), with the homodimer being significantly more efficient. In this work, we functionally dissect the potential cellular roles of GrxD as a component of both homodimeric and heterodimeric complexes to ultimately uncover if either of these complexes performs functions linked to FeS cluster biosynthesis. © 2011 American Chemical Society

Deactivation of Escherichia coli by the plasma needle

International Nuclear Information System (INIS)

Sladek, R E J; Stoffels, E

2005-01-01

In this paper we present a parameter study on deactivation of Escherichia coli (E. coli) by means of a non-thermal plasma (plasma needle). The plasma needle is a small-sized (1 mm) atmospheric glow sustained by radio-frequency excitation. This plasma will be used to disinfect heat-sensitive objects; one of the intended applications is in vivo deactivation of dental bacteria: destruction of plaque and treatment of caries. We use E. coli films plated on agar dishes as a model system to optimize the conditions for bacterial destruction. Plasma power, treatment time and needle-to-sample distance are varied. Plasma treatment of E. coli films results in formation of a bacteria-free void with a size up to 12 mm. 10 4 -10 5 colony forming units are already destroyed after 10 s of treatment. Prolongation of treatment time and usage of high powers do not significantly improve the destruction efficiency: short exposure at low plasma power is sufficient. Furthermore, we study the effects of temperature increase on the survival of E. coli and compare it with thermal effects of the plasma. The population of E. coli heated in a warm water bath starts to decrease at temperatures above 40 deg. C. Sample temperature during plasma treatment has been monitored. The temperature can reach up to 60 deg. C at high plasma powers and short needle-to-sample distances. However, thermal effects cannot account for bacterial destruction at low power conditions. For safe and efficient in vivo disinfection, the sample temperature should be kept low. Thus, plasma power and treatment time should not exceed 150 mW and 60 s, respectively

Deactivation of Escherichia coli by the plasma needle

Energy Technology Data Exchange (ETDEWEB)

Sladek, R E J; Stoffels, E [Department of Biomedical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

2005-06-07

In this paper we present a parameter study on deactivation of Escherichia coli (E. coli) by means of a non-thermal plasma (plasma needle). The plasma needle is a small-sized (1 mm) atmospheric glow sustained by radio-frequency excitation. This plasma will be used to disinfect heat-sensitive objects; one of the intended applications is in vivo deactivation of dental bacteria: destruction of plaque and treatment of caries. We use E. coli films plated on agar dishes as a model system to optimize the conditions for bacterial destruction. Plasma power, treatment time and needle-to-sample distance are varied. Plasma treatment of E. coli films results in formation of a bacteria-free void with a size up to 12 mm. 10{sup 4}-10{sup 5} colony forming units are already destroyed after 10 s of treatment. Prolongation of treatment time and usage of high powers do not significantly improve the destruction efficiency: short exposure at low plasma power is sufficient. Furthermore, we study the effects of temperature increase on the survival of E. coli and compare it with thermal effects of the plasma. The population of E. coli heated in a warm water bath starts to decrease at temperatures above 40 deg. C. Sample temperature during plasma treatment has been monitored. The temperature can reach up to 60 deg. C at high plasma powers and short needle-to-sample distances. However, thermal effects cannot account for bacterial destruction at low power conditions. For safe and efficient in vivo disinfection, the sample temperature should be kept low. Thus, plasma power and treatment time should not exceed 150 mW and 60 s, respectively.

Sucralose Increases Antimicrobial Resistance and Stimulates Recovery of Escherichia coli Mutants.

Science.gov (United States)

Qu, Yilin; Li, Rongyan; Jiang, Mingshan; Wang, Xiuhong

2017-07-01

Because of heavy use of antimicrobials, antimicrobial resistance in bacteria has become of great concern. The effect of some widely used food additives such as sucralose on bacteria in the gut and the environment has also drawn increasing attention. In this study, we investigated the interaction between antimicrobials and sucralose impacting antimicrobial resistance and mutation of Escherichia coli (E. coli). To examine antimicrobial resistance and mutation frequency, different subinhibitory concentrations of sucralose were added to cultures of E.coli BW25113 that were then treated with antimicrobials, oxolinic acid, or moxifloxacin. Then the E.coli were assayed for bacterial survival and recovery of mutants resistant to an unrelated antimicrobial, rifampicin. Pre-treatment of E.coli BW25113 with 1/2 minimal inhibitory concentration (MIC) of sucralose increased the survival rate in oxolinic acid or moxifloxacin. A 1/3 MIC of sucralose increased rifampicin-resistant mutation rate of E.coli BW25113 after 72 h, while rifampicin-resistant mutation rate was increased when co-treated with 1/8 MIC, 1/4 MIC, 1/3 MIC sucralose, and oxolinic acid after 24 h. Sucralose can increase the antimicrobial resistance and mutation frequency of E.coli to some antimicrobials.

Action of sodium deoxycholate on Escherichia coli

International Nuclear Information System (INIS)

D'Mello, A.; Yotis, W.W.

1987-01-01

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of [U- 14 C]glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order

Action of sodium deoxycholate on Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

D' Mello, A.; Yotis, W.W.

1987-08-01

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of (U-/sup 14/C)glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order.

Occurrence of Coliform and Escherichia coli Contamination and Absence of Escherichia coli O157:H7 on Romaine Lettuce from Retail Stores in the Upper Midwest.

Science.gov (United States)

Greve, Josephine D; Zietlow, Mark S; Miller, Kevin M; Ellingson, Jay L E

2015-09-01

A total of 720 whole, romaine lettuce heads were purchased from retail locations in the Upper Midwest and assessed for coliform and Escherichia coli contamination and for the presence of E. coli O157:H7. During a 16-month period (August 2010 through December 2011), coliform and E. coli counts were enumerated on Petrifilm, and the presence of E. coli O157:H7 and the virulence gene eae was evaluated by real-time PCR (qPCR). Over half (400 of 720) of the lettuce samples were processed with an immunomagnetic separation step before the qPCR assay. All retail lettuce samples were negative for E. coli O157:H7 when tested with the R.A.P.I.D. LT qPCR targeting a region of the O-antigen, and only two (0.28%) were positive for the eae gene when tested with LightCycler qPCR. On Petrifilm, coliform counts of most lettuce samples (96.4%) were between lettuce samples (98.2%) were lettuce heads. These results contribute to the limited recorded data and understanding of microbial contamination of whole romaine lettuce heads purchased from retail locations, specifically revealing the absence of E. coli O157:H7 and low levels of contamination with coliforms and other E. coli strains.

Altered Escherichia coli membrane protein assembly machinery allows proper membrane assembly of eukaryotic protein vitamin K epoxide reductase.

Science.gov (United States)

Hatahet, Feras; Blazyk, Jessica L; Martineau, Eugenie; Mandela, Eric; Zhao, Yongxin; Campbell, Robert E; Beckwith, Jonathan; Boyd, Dana

2015-12-08

Functional overexpression of polytopic membrane proteins, particularly when in a foreign host, is often a challenging task. Factors that negatively affect such processes are poorly understood. Using the mammalian membrane protein vitamin K epoxide reductase (VKORc1) as a reporter, we describe a genetic selection approach allowing the isolation of Escherichia coli mutants capable of functionally expressing this blood-coagulation enzyme. The isolated mutants map to components of membrane protein assembly and quality control proteins YidC and HslV. We show that changes in the VKORc1 sequence and in the YidC hydrophilic groove along with the inactivation of HslV promote VKORc1 activity and dramatically increase its expression level. We hypothesize that such changes correct for mismatches in the membrane topogenic signals between E. coli and eukaryotic cells guiding proper membrane integration. Furthermore, the obtained mutants allow the study of VKORc1 reaction mechanisms, inhibition by warfarin, and the high-throughput screening for potential anticoagulants.

Spontaneous Escherichia coli Meningitis Associated with Hemophagocytic Lymphohistiocytosis

Directory of Open Access Journals (Sweden)

Kuo-Hsuan Chang

2006-01-01

Full Text Available Spontaneous Escherichia coli meningitis has not been previously reported in association with hemophago-cytic lymphohistiocytosis (HLH. A previously healthy 72-year-old woman was admitted due to fever, nuchal rigidity, disturbed consciousness and splenomegaly. Anemia, thrombocytopenia and hyperfer-ritinemia developed on the 8th day of hospitalization. Cultures of cerebrospinal fluid and blood grew E. coli. Abundant macrophages overwhelmed erythrocytes in the bone marrow aspirate, confirming the presence of hemophagocytosis. E. coli meningitis was managed with a 40-day course of antibiotic treatment. However, the severity of anemia and thrombocytopenia progressed despite intensive transfusion therapy. The patient died of HLH on the 60th day of hospitalization.

Escherichia coli growth modeling using neural network | Shamsudin ...

African Journals Online (AJOL)

technique that has the ability to predict with efficient and good performance. Using NARX, a highly accurate model was developed to predict the growth of Escherichia coli (E. coli) based on pH water parameter. The multiparameter portable sensor and spectrophotometer data were used to build and train the neural network.

Structure of the P{sub II} signal transduction protein of Neisseria meningitidis at 1.85 Å resolution

Energy Technology Data Exchange (ETDEWEB)

Nichols, Charles E. [Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Sainsbury, Sarah; Berrow, Nick S.; Alderton, David [The Oxford Protein Production Facility, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Saunders, Nigel J. [The Bacterial Pathogenesis and Functional Genomics Group, The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE (United Kingdom); Stammers, David K. [Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); The Oxford Protein Production Facility, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Owens, Raymond J., E-mail: ray@strubi.ox.ac.uk [The Oxford Protein Production Facility, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Division of Structural Biology, Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom)

2006-06-01

The structure of the P{sub II} signal transduction protein of N. meningitidis at 1.85 Å resolution is described. The P{sub II} signal transduction proteins GlnB and GlnK are implicated in the regulation of nitrogen assimilation in Escherichia coli and other enteric bacteria. P{sub II}-like proteins are widely distributed in bacteria, archaea and plants. In contrast to other bacteria, Neisseria are limited to a single P{sub II} protein (NMB 1995), which shows a high level of sequence identity to GlnB and GlnK from Escherichia coli (73 and 62%, respectively). The structure of the P{sub II} protein from N. meningitidis (serotype B) has been solved by molecular replacement to a resolution of 1.85 Å. Comparison of the structure with those of other P{sub II} proteins shows that the overall fold is tightly conserved across the whole population of related proteins, in particular the positions of the residues implicated in ATP binding. It is proposed that the Neisseria P{sub II} protein shares functions with GlnB/GlnK of enteric bacteria.

Uropathogenic E. coli induce different immune response in testicular and peritoneal macrophages: implications for testicular immune privilege.

Directory of Open Access Journals (Sweden)

Sudhanshu Bhushan

Full Text Available Infertility affects one in seven couples and ascending bacterial infections of the male genitourinary tract by Escherichia coli are an important cause of male factor infertility. Thus understanding mechanisms by which immunocompetent cells such as testicular macrophages (TM respond to infection and how bacterial pathogens manipulate defense pathways is of importance. Whole genome expression profiling of TM and peritoneal macrophages (PM infected with uropathogenic E. coli (UPEC revealed major differences in regulated genes. However, a multitude of genes implicated in calcium signaling pathways was a common feature which indicated a role of calcium-dependent nuclear factor of activated T cells (NFAT signaling. UPEC-dependent NFAT activation was confirmed in both cultured TM and in TM in an in vivo UPEC infectious rat orchitis model. Elevated expression of NFATC2-regulated anti-inflammatory cytokines was found in TM (IL-4, IL-13 and PM (IL-3, IL-4, IL-13. NFATC2 is activated by rapid influx of calcium, an activity delineated to the pore forming toxin alpha-hemolysin by bacterial mutant analysis. Alpha-hemolysin suppressed IL-6 and TNF-α cytokine release from PM and caused differential activation of MAP kinase and AP-1 signaling pathways in TM and PM leading to reciprocal expression of key pro-inflammatory cytokines in PM (IL-1α, IL-1β, IL-6 downregulated and TM (IL-1β, IL-6 upregulated. In addition, unlike PM, LPS-treated TM were refractory to NFκB activation shown by the absence of degradation of IκBα and lack of pro-inflammatory cytokine secretion (IL-6, TNF-α. Taken together, these results suggest a mechanism to the conundrum by which TM initiate immune responses to bacteria, while maintaining testicular immune privilege with its ability to tolerate neo-autoantigens expressed on developing spermatogenic cells.

A novel fluorescence immunoassay for the sensitive detection of Escherichia coli O157:H7 in milk based on catalase-mediated fluorescence quenching of CdTe quantum dots

International Nuclear Information System (INIS)

Chen, Rui; Huang, Xiaolin; Li, Juan; Shan, Shan; Lai, Weihua; Xiong, Yonghua

2016-01-01

Immunoassay is a powerful tool for rapid detection of food borne pathogens in food safety monitoring. However, conventional immunoassay always suffers from low sensitivity when it employs enzyme-catalyzing chromogenic substrates to generate colored molecules as signal outputs. In the present study, we report a novel fluorescence immunoassay for the sensitive detection of E. coli O157:H7 through combination of the ultrahigh bioactivity of catalase to hydrogen peroxide (H_2O_2) and H_2O_2-sensitive mercaptopropionic acid modified CdTe QDs (MPA-QDs) as a signal transduction. Various parameters, including the concentrations of anti-E. coli O157:H7 polyclonal antibody and biotinylated monoclonal antibody, the amounts of H_2O_2 and streptavidin labeled catalase (CAT), the hydrolysis temperature and time of CAT to H_2O_2, as well as the incubation time between H_2O_2 and MPA-QDs, were systematically investigated and optimized. With optimal conditions, the catalase-mediated fluorescence quenching immunoassay exhibits an excellent sensitivity for E. coli O157:H7 with a detection limit of 5 × 10"2 CFU/mL, which was approximately 140 times lower than that of horseradish peroxidase-based colorimetric immunoassay. The reliability of the proposed method was further evaluated using E. coli O157:H7 spiked milk samples. The average recoveries of E. coli O157:H7 concentrations from 1.18 × 10"3 CFU/mL to 1.18 × 10"6 CFU/mL were in the range of 65.88%–105.6%. In brief, the proposed immunoassay offers a great potential for rapid and sensitive detection of other pathogens in food quality control. - Highlights: • A novel fluorescence immunoassay was developed for the ultrasensitive detection of E. coli O157:H7. • This detection was achieved through the combination of the high bioactivity of CAT and H_2O_2-sensitive QDs. • The activity of CAT to H_2O_2 is 1000 folds higher than that of the HRP to tetramethylbenzidine. • The limit of detection of the proposed method could

Engineering Escherichia coli for methanol conversion.

Science.gov (United States)

Müller, Jonas E N; Meyer, Fabian; Litsanov, Boris; Kiefer, Patrick; Potthoff, Eva; Heux, Stéphanie; Quax, Wim J; Wendisch, Volker F; Brautaset, Trygve; Portais, Jean-Charles; Vorholt, Julia A

2015-03-01

Methylotrophic bacteria utilize methanol and other reduced one-carbon compounds as their sole source of carbon and energy. For this purpose, these bacteria evolved a number of specialized enzymes and pathways. Here, we used a synthetic biology approach to select and introduce a set of "methylotrophy genes" into Escherichia coli based on in silico considerations and flux balance analysis to enable methanol dissimilation and assimilation. We determined that the most promising approach allowing the utilization of methanol was the implementation of NAD-dependent methanol dehydrogenase and the establishment of the ribulose monophosphate cycle by expressing the genes for hexulose-6-phosphate synthase (Hps) and 6-phospho-3-hexuloisomerase (Phi). To test for the best-performing enzymes in the heterologous host, a number of enzyme candidates from different donor organisms were selected and systematically analyzed for their in vitro and in vivo activities in E. coli. Among these, Mdh2, Hps and Phi originating from Bacillus methanolicus were found to be the most effective. Labeling experiments using (13)C methanol with E. coli producing these enzymes showed up to 40% incorporation of methanol into central metabolites. The presence of the endogenous glutathione-dependent formaldehyde oxidation pathway of E. coli did not adversely affect the methanol conversion rate. Taken together, the results of this study represent a major advancement towards establishing synthetic methylotrophs by gene transfer. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Diarrheagenic Escherichia coli and acute and persistent diarrhea in returned travelers

NARCIS (Netherlands)

Schultsz, C.; van den Ende, J.; Cobelens, F.; Vervoort, T.; van Gompel, A.; Wetsteyn, J. C.; Dankert, J.

2000-01-01

To determine the role of diarrheagenic Escherichia coli in acute and persistent diarrhea in returned travelers, a case control study was performed. Enterotoxigenic E. coli (ETEC) was detected in stool samples from 18 (10.7%) of 169 patients and 4 (3.7%) of 108 controls. Enteroaggregative E. coli

Recyclable Escherichia coli-Specific-Killing AuNP-Polymer (ESKAP) Nanocomposites.

Science.gov (United States)

Yuan, Yuqi; Liu, Feng; Xue, Lulu; Wang, Hongwei; Pan, Jingjing; Cui, Yuecheng; Chen, Hong; Yuan, Lin

2016-05-11

Escherichia coli plays a crucial role in various inflammatory diseases and infections that pose significant threats to both human health and the global environment. Specifically inhibiting the growth of pathogenic E. coli is of great and urgent concern. By modifying gold nanoparticles (AuNPs) with both poly[2-(methacrylamido)glucopyranose] (pMAG) and poly[2-(methacryloyloxy)ethyl trimethylammonium iodide] (pMETAI), a novel recyclable E. coli-specific-killing AuNP-polymer (ESKAP) nanocomposite is proposed in this study, which based on both the high affinity of glycopolymers toward E. coli pili and the merits of antibacterial quaternized polymers attached to gold nanoparticles. The properties of nanocomposites with different ratios of pMAG to pMETAI grafted onto AuNPs are studied. With a pMAG:pMETAI feed ratio of 1:3, the nanocomposite appeared to specifically adhere to E. coli and highly inhibit the bacterial cells. After addition of mannose, which possesses higher affinity for the lectin on bacterial pili and has a competitive advantage over pMAG for adhesion to pili, the nanocomposite was able to escape from dead E. coli cells, becoming available for repeat use. The recycled nanocomposite retained good antibacterial activity for at least three cycles. Thus, this novel ESKAP nanocomposite is a promising, highly effective, and readily recyclable antibacterial agent that specifically kills E. coli. This nanocomposite has potential applications in biological sensing, biomedical diagnostics, biomedical imaging, drug delivery, and therapeutics.

Human exposure assessment to antibiotic-resistant Escherichia coli through drinking water.

Science.gov (United States)

O'Flaherty, E; Borrego, C M; Balcázar, J L; Cummins, E

2018-03-01

Antibiotic-resistant bacteria (ARB) are a potential threat to human health through drinking water with strong evidence of ARB presence in post treated tap water around the world. This study examines potential human exposure to antibiotic-resistant (AR) Escherichia coli (E. coli) through drinking water, the effect of different drinking water treatments on AR E. coli and the concentration of AR E. coli required in the source water for the EU Drinking Water Directive (DWD) (Council Directive 98/83/EC, 0CFU/100ml of E. coli in drinking water) to be exceeded. A number of scenarios were evaluated to examine different water treatment combinations and to reflect site specific conditions at a study site in Europe. A literature search was carried out to collate data on the effect of environmental conditions on AR E. coli, the effect of different water treatments on AR E. coli and typical human consumption levels of tap water. A human exposure assessment model was developed with probability distributions used to characterise uncertainty and variability in the input data. Overall results show the mean adult human exposure to AR E. coli from tap water consumption ranged between 3.44×10 -7 and 2.95×10 -1 cfu/day for the scenarios tested and varied depending on the water treatments used. The level of AR E. coli required in the source water pre-treatment to exceed the DWD varied between 1 and 5logcfu/ml, depending on the water treatments used. This can be used to set possible monitoring criteria in pre-treated water for potential ARB exposure in drinking water. Copyright © 2017 Elsevier B.V. All rights reserved.

Genome-Wide Mapping of Transcriptional Regulation and Metabolism Describes Information-Processing Units in Escherichia coli

Directory of Open Access Journals (Sweden)

Daniela Ledezma-Tejeida

2017-08-01

Full Text Available In the face of changes in their environment, bacteria adjust gene expression levels and produce appropriate responses. The individual layers of this process have been widely studied: the transcriptional regulatory network describes the regulatory interactions that produce changes in the metabolic network, both of which are coordinated by the signaling network, but the interplay between them has never been described in a systematic fashion. Here, we formalize the process of detection and processing of environmental information mediated by individual transcription factors (TFs, utilizing a concept termed genetic sensory response units (GENSOR units, which are composed of four components: (1 a signal, (2 signal transduction, (3 genetic switch, and (4 a response. We used experimentally validated data sets from two databases to assemble a GENSOR unit for each of the 189 local TFs of Escherichia coli K-12 contained in the RegulonDB database. Further analysis suggested that feedback is a common occurrence in signal processing, and there is a gradient of functional complexity in the response mediated by each TF, as opposed to a one regulator/one pathway rule. Finally, we provide examples of other GENSOR unit applications, such as hypothesis generation, detailed description of cellular decision making, and elucidation of indirect regulatory mechanisms.

lactamases genes among0 Escherichia coli from patients with ...

African Journals Online (AJOL)

-lactamases (ESBLs) that mediate resistance to b-lactam drugs among Escherichia coli and other uropathogens have been reported worldwide. However, there is little information on the detection of ESBLs genes in E. coli from patients with ...

Characterization of Climical and Commensal Escherichia coli Isolates from an Integrated Turkey Operation

OpenAIRE

Altekruse, Sean Fitzgerald

2001-01-01

Pathogenic E. coli infections cause approximately one quarter of disease losses in commercial turkey flocks. A small subgroup of E. coli causes most infections. Epidemiologic studies of this disease have been hindered by a lack of reliable markers to discriminate between pathogenic and fecal E. coli and by the diversity of poultry strains. Reliance on antimicrobials to control E. coli infections has caused widespread antimicrobial resistance. One hundred five clinical E. coli were obtaine...

Variant innate immune responses of mammary epithelial cells to challenge by Staphylococcus aureus, Escherichia coli and the regulating effect of taurine on these bioprocesses.

Science.gov (United States)

Zheng, Liuhai; Xu, Yuanyuan; Lu, Jinye; Liu, Ming; Bin Dai; Miao, Jinfeng; Yin, Yulong

2016-07-01

taurine improved the antioxidant ability of cells. We conclude that taurine can regulate the inflammatory response during infection with E. coli and prevent cell damage by affecting the signaling pathways mediated by TLRs and by improving the antioxidant ability of cells. In S. aureus infections, taurine's antioxidant ability may be the primary means of resistance to inflammation. This study provides a better understanding of the inflammatory mechanisms of E. coli and S. aureus mastitis, and it provides a putative strategy for the prevention of this disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Uncomplicated E Coli Urinary Tract Infection in College Women: A Follow-Up Study of E Coli Sensitivities to Commonly Prescribed Antibiotics

Science.gov (United States)

Ansbach, Robert K.; Dybus, Karen; Bergeson, Rachel

2005-01-01

Treatment of uncomplicated urinary tract infections (UTIs) has changed in the past few years with researchers advocating empiric treatment for shorter periods of time without the use of cultures. Researchers report that antibiotic resistance of Escherichia coli (E coli) to commonly prescribed antibiotics in uncomplicated UTIs has been increasing.…

A direct detection of Escherichia coli genomic DNA using gold nanoprobes

Directory of Open Access Journals (Sweden)

Padmavathy

2012-02-01

Full Text Available Abstract Background In situation like diagnosis of clinical and forensic samples there exists a need for highly sensitive, rapid and specific DNA detection methods. Though conventional DNA amplification using PCR can provide fast results, it is not widely practised in diagnostic laboratories partially because it requires skilled personnel and expensive equipment. To overcome these limitations nanoparticles have been explored as signalling probes for ultrasensitive DNA detection that can be used in field applications. Among the nanomaterials, gold nanoparticles (AuNPs have been extensively used mainly because of its optical property and ability to get functionalized with a variety of biomolecules. Results We report a protocol for the use of gold nanoparticles functionalized with single stranded oligonucleotide (AuNP- oligo probe as visual detection probes for rapid and specific detection of Escherichia coli. The AuNP- oligo probe on hybridization with target DNA containing complementary sequences remains red whereas test samples without complementary DNA sequences to the probe turns purple due to acid induced aggregation of AuNP- oligo probes. The color change of the solution is observed visually by naked eye demonstrating direct and rapid detection of the pathogenic Escherichia coli from its genomic DNA without the need for PCR amplification. The limit of detection was ~54 ng for unamplified genomic DNA. The method requires less than 30 minutes to complete after genomic DNA extraction. However, by using unamplified enzymatic digested genomic DNA, the detection limit of 11.4 ng was attained. Results of UV-Vis spectroscopic measurement and AFM imaging further support the hypothesis of aggregation based visual discrimination. To elucidate its utility in medical diagnostic, the assay was validated on clinical strains of pathogenic Escherichia coli obtained from local hospitals and spiked urine samples. It was found to be 100% sensitive and proves to

High-level expression of Bacillus naganoensis pullulanase from recombinant Escherichia coli with auto-induction: effect of lac operator.

Directory of Open Access Journals (Sweden)

Yao Nie

Full Text Available Pullulanase plays an important role in specific hydrolysis of branch points in amylopectin and is generally employed as an important enzyme in starch-processing industry. So far, however, the production level of pullulanase is still somewhat low from wide-type strains and even heterologous expression systems. Here the gene encoding Bacillus naganoensis pullulanase was amplified and cloned. For expression of the protein, two recombinant systems, Escherichia coli BL21(DE3/pET-20b(+-pul and E. coli BL21(DE3/pET-22b(+-pul, were constructed, both bearing T7 promoter and signal peptide sequence, but different in the existance of lac operator and lacI gene encoding lac repressor. Recombinant pullulanase was initially expressed with the activity of up to 14 U/mL by E. coli BL21(DE3/pET-20b(+-pul with IPTG induction in LB medium, but its expression level reduced continually with the extension of cryopreservation time and basal expression was observed. However, E. coli BL21(DE3/pET-22b(+-pul , involving lac operator downstream of T7 promoter to regulate foreign gene transcription, exhibited pullulanase activity consistently without detected basal expression. By investigating the effect of lac operator, basal expression of foreign protein was found to cause expression instability and negative effect on production of target protein. Thus double-repression strategy was proposed that lac operators in both chromosome and plasmid were bound with lac repressor to repress T7 RNA polymerase synthesis and target protein expression before induction. Consequently, the total activity of pullulanase was remarkably increased to 580 U/mL with auto-induction by lac operator-involved E. coli BL21(DE3/pET-22b(+-pul. When adding 0.6% glycine in culture, the extracellular production of pullulanase was significantly improved with the extracellular activity of 502 U/mL, which is a relatively higher level achieved to date for extracellular production of pullulanase. The

Distribution of Diverse Escherichia coli between Cattle and Pasture.

Science.gov (United States)

NandaKafle, Gitanjali; Seale, Tarren; Flint, Toby; Nepal, Madhav; Venter, Stephanus N; Brözel, Volker S

2017-09-27

Escherichia coli is widely considered to not survive for extended periods outside the intestines of warm-blooded animals; however, recent studies demonstrated that E. coli strains maintain populations in soil and water without any known fecal contamination. The objective of this study was to investigate whether the niche partitioning of E. coli occurs between cattle and their pasture. We attempted to clarify whether E. coli from bovine feces differs phenotypically and genotypically from isolates maintaining a population in pasture soil over winter. Soil, bovine fecal, and run-off samples were collected before and after the introduction of cattle to the pasture. Isolates (363) were genotyped by uidA and mutS sequences and phylogrouping, and evaluated for curli formation (Rough, Dry, And Red, or RDAR). Three types of clusters emerged, viz. bovine-associated, clusters devoid of cattle isolates and representing isolates endemic to the pasture environment, and clusters with both. All isolates clustered with strains of E. coli sensu stricto, distinct from the cryptic species Clades I, III, IV, and V. Pasture soil endemic and bovine fecal populations had very different phylogroup distributions, indicating niche partitioning. The soil endemic population was largely comprised of phylogroup B1 and had a higher average RDAR score than other isolates. These results indicate the existence of environmental E. coli strains that are phylogenetically distinct from bovine fecal isolates, and that have the ability to maintain populations in the soil environment.

Temporal variations of Escherichia coli concentrations in a large Midwestern river

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Schilling, K.E.; Zhang, Y.-K.; Hill, D.R.; Jones, C.S.; Wolter, C.F.

2009-01-01

The Raccoon River used by the Des Moines Water Works to serve more than 400,000 people in central Iowa is threatened by contamination from Escherichia coli bacteria from point and nonpoint sources. The 9389 km2 watershed is highly agricultural, with 73% of the land in row crop production and widespread animal production. Results from 2155 grab samples from 1997 to 2005 for E. coli analysis were examined for temporal variations. E. coli concentrations were found to vary across years, seasons, and flow conditions, with a 9-year mean value of 1156 most probable number (MPN)/100 ml. Monthly concentrations exhibited clear seasonality with highest values in May through July. Although E. coli concentrations were higher during periods of greater discharge, the relation of log E. coli to log discharge was not particularly strong (r2 = 0.35). The variogram of E. coli concentrations showed temporal correlation within a span of 4 days suggesting that concentrations measured on 1 day may be related in time to concentrations measured up to 3 days later and beyond 4 days the concentrations vary randomly. The spectral analysis of the time series of E. coli was also carried out and was fitted well with the spectrum of an exponential covariance function. Deciphering temporal patterns and correlation of E. coli bacteria in streams may be useful for developing future monitoring strategies to track concentration patterns and loads. ?? 2008 Elsevier B.V. All rights reserved.

Isolation and evaluation of cocktail phages for the control of multidrug-resistant Escherichia coli serotype O104: H4 and E. coli O157: H7 isolates causing diarrhea.

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Safwat Mohamed, Doaa; Farouk Ahmed, Eman; Mohamed Mahmoud, Abobakr; Abd El-Baky, Rehab Mahmoud; John, James

2018-02-01

Escherichia coli serotype O157: H7 and E. coli O104: H4 are well known foodborne pathogens causing sever enteric illness. Using bacteriophages as biocontrol agents of some foodborne pathogens and multidrug-resistant (MDR) bacteria has a great attention nowadays. This study aims to test the effect of cocktail phages on the growth of some foodborne pathogens and MDR E. coli. Routine conventional PCR was used to confirm the identification of E. coli isolates. Double-layered culture technique was used to isolate phages from sewage water. Morphology of bacteriophage was described using transmission electron microscopy, and spot test was performed to determine host range of the phage cocktail. Phage cocktail of Siphoviridae and Podoviridae family infecting E. coli O157: H7, E. coli O104: H4 and untypeable E. coli (neither O157 nor O104) has been isolated from sewage water. Phage cocktail showed both lytic and lysogenic activity. Lytic activity was observed against E. coli O157: H7, E. coli O104: H4 isolates, Staphylococcus. aureus ATCC6538 and Pseudomonas aeruginosa ATCC 10145, while the lysogenic activity was observed against the untypeable strain. The tested phage cocktail showed a promising inhibitory action on E. coli O157: H7 and O104: H4, S. aureus ATCC6538 and P. aeruginosa ATCC 10145, suggesting the possibility of its use as a biocontrol tool or as natural food preservatives for many food products. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Alterations induced in Escherichia Coli cells by gamma radiation

International Nuclear Information System (INIS)

Kappke, J.; Schelin, H.R.; Paschuk, S.A.; Denyak, V.; Silva, E.R. da; Jesus, E.F.O. de; Lopes, R.T.; Carlin, N.; Toledo, E.S.

2007-01-01

Modifications occurred in Escherichia coli cells exposed to gamma radiation ( 60 Co source) were investigated. The irradiations were done at the LIN-COPPE laboratory of the UFRJ and the analysis at the Biology Department of the UTFPR. The E. coli cells were irradiated with 30, 60, 90, 120, 150, 180, 210, 240, 300, 480, 600 e 750 Gy doses. The samples were analyzed with Gram-stain, biochemical tests in EPM, MIO and Lysine Broth, Simmons Cytrate Medium and Rhamnose Broth, antibiogram and isolation of auxotrophic mutants. It was observed that for the received doses the E. coli did not show morphological alterations in the tests. Some E. Coli cells showed to be able to deaminade the L-tryptophan or they changed their sensibility for amoxillin and cephaloonine after the irradiation. The existence of aauxotrophic mutants after irradiation was also verified. (author)

Cognitive, personality, and social factors associated with adolescents' online personal information disclosure.

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Liu, Cong; Ang, Rebecca P; Lwin, May O

2013-08-01

The current study aims to understand the factors that influence adolescents' disclosure of personally identifiable information (PII) on social networking sites (SNSs). A survey was conducted among 780 adolescent participants (between 13 and 18) who were Facebook users. Structural equation modeling was used for analyzing the data and obtaining an overarching model that include cognitive, personality, and social factors that influence adolescents' PII disclosure. Results showed privacy concern as the cognitive factor reduces adolescents' PII disclosure and it serves as a potential mediator for personality and social factors. Amongst personality factors, narcissism was found to directly increase PII disclosure, and social anxiety indirectly decreases PII disclosure by increasing privacy concern. Amongst social factors, active parental mediation decreases PII disclosure directly and indirectly by increasing privacy concern. Restrictive parental mediation decreases PII disclosure only indirectly by increasing privacy concern. Implications of the findings to parents, educators, and policy makers were discussed. Copyright © 2013 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Stimulation of Escherichia coli F-18Col- Type-1 fimbriae synthesis by leuX

DEFF Research Database (Denmark)

Newman, Joseph V.; Burghoff, Robert L.; Pallesen, Lars

1994-01-01

Escherichia coli F-18, a normal human fecal isolate, is an excellent colonizer of the streptomycin-treated mouse large intestine. E. coli F-18Col-, a derivative of E. coli F-18 which no longer makes the E. coli F-18 colicin, colonizes the large intestine as well as E. coli F-18 when fed to mice...... alone but is eliminated when fed together with E. coli F-18. Recently we randomly cloned E. coli F-18 DNA into E. coli F-18Col- and let the mouse intestine select the best colonizer. In this way, we isolated a 6.5-kb E. coli F-18 DNA sequence that simultaneously stimulated synthesis of type 1 fimbriae...... and enhanced E. coli F-18Col- colonizing ability. In the present investigation we show that the gene responsible for stimulation of type 1 fimbriae synthesis appears to be leuX, which encodes a tRNA specific for the rare leucine codon UUG. Moreover, it appears that expression of leuX may be regulated by two...

Transferability of antimicrobial resistance from multidrug-resistant Escherichia coli isolated from cattle in the USA to E. coli and Salmonella Newport recipients

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The objective of this study was to evaluate conjugative transfer of cephalosporin resistance among (n=100) strains of multi-drug resistant Escherichia coli (MDRE) to Salmonella Newport and E. coli DH5-alpha recipients. To accomplish this, phenotypic and genotypic profiles were determined for MDRE, ...

Reproducible gene targeting in recalcitrant Escherichia coli isolates

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De Greve Henri

2011-06-01

Full Text Available Abstract Background A number of allele replacement methods can be used to mutate bacterial genes. For instance, the Red recombinase system of phage Lambda has been used very efficiently to inactivate chromosomal genes in E. coli K-12, through recombination between regions of homology. However, this method does not work reproducibly in some clinical E. coli isolates. Findings The procedure was modified by using longer homologous regions (85 bp and 500-600 bp, to inactivate genes in the uropathogenic E. coli strain UTI89. An lrhA regulator mutant, and deletions of the lac operon as well as the complete type 1 fimbrial gene cluster, were obtained reproducibly. The modified method is also functional in other recalcitrant E. coli, like the avian pathogenic E. coli strain APEC1. The lrhA regulator and lac operon deletion mutants of APEC1 were successfully constructed in the same way as the UTI89 mutants. In other avian pathogenic E. coli strains (APEC3E, APEC11A and APEC16A it was very difficult or impossible to construct these mutants, with the original Red recombinase-based method, with a Red recombinase-based method using longer (85 bp homologous regions or with our modified protocol, using 500 - 600 bp homologous regions. Conclusions The method using 500-600 bp homologous regions can be used reliably in some clinical isolates, to delete single genes or entire operons by homologous recombination. However, it does not invariably show a greater efficiency in obtaining mutants, when compared to the original Red-mediated gene targeting method or to the gene targeting method with 85 bp homologous regions. Therefore the length of the homology regions is not the only limiting factor for the construction of mutants in these recalcitrant strains.

Occurrence and characterization of Shiga toxin-producing Escherichia coli O157:H7 and other non-sorbitol-fermenting E. coli in cattle and humans in urban areas of Morogoro, Tanzania.

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Lupindu, Athumani M; Olsen, John E; Ngowi, Helena A; Msoffe, Peter L M; Mtambo, Madundo M; Scheutz, Flemming; Dalsgaard, Anders

2014-07-01

Escherichia coli strains such as Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli, enterotoxigenic, attaching, and effacing E. coli, and enteroinvasive E. coli cause diarrhea in humans. Although other serotypes exist, the most commonly reported STEC in outbreaks is O157:H7. A cross-sectional study was conducted to isolate and characterize non-sorbitol-fermenting (NSF) E. coli O157:H7 from urban and periurban livestock settings of Morogoro, Tanzania. Human stool, cattle feces, and soil and water samples were collected. Observations and questionnaire interview studies were used to gather information about cattle and manure management practices in the study area. E. coli were isolated on sorbitol MacConkey agar and characterized by conventional biochemical tests. Out of 1049 samples, 143 (13.7%) yielded NSF E. coli. Serological and antimicrobial tests and molecular typing were performed to NSF E. coli isolates. These procedures detected 10 (7%) pathogenic E. coli including STEC (n=7), enteropathogenic E. coli (EPEC) (n=2), and attaching and effacing E. coli (A/EEC) (n=1) strains. The STEC strains had the ability to produce VT1 and different VT2 toxin subtypes that caused cytopathic effects on Vero cells. The prevalence of STEC in cattle was 1.6%, out of which 0.9% was serotype O157:H7 and the overall prevalence of diarrheagenic E. coli in cattle was 2.2%. The serotypes O157:H7, O142:H34, O113:H21, O+:H-, O+:H16, and O25:H4 were identified. One ESBL-producing isolate showed the MLST type ST131. To our knowledge, this is the first finding in Tanzania of this recently emerged worldwide pandemic clonal group, causing widespread antimicrobial-resistant infections, and adds knowledge of the geographical distribution of ST131. Cattle manure was indiscriminately deposited within residential areas, and there was direct contact between humans and cattle feces during manure handling. Cattle and manure management practices expose humans, animals, and the environment

Escherichia coli O104 associated with human diarrhea, South Africa, 2004-2011.

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Tau, Nomsa P; Meidany, Parastu; Smith, Anthony M; Sooka, Arvinda; Keddy, Karen H

2012-08-01

To determine the origin of >4,000 suspected diarrheagenic Escherichia coli strains isolated during 2004-2011 in South Africa, we identified 7 isolates as serotype O104; 5 as enteroaggregative E. coli O104:H4, and 2 as enteropathogenic E. coli O104:non-H4. Pulsed-field gel electrophoresis showed that these isolates were unrelated to the 2011 E. coli O104:H4 outbreak strain from Germany.

Sigma factors in a thousand E. coli genomes

DEFF Research Database (Denmark)

Cook, Helen Victoria; Ussery, David

2013-01-01

, 2013), only less than half (983) are of sufficient quality to use in comparative genomic work. Unfortunately, even some of the ‘complete’ E. coli genomes are in pieces, and a few ‘draft’ genomes are good quality. Six of the seven known sigma factors in E. coli strain K‐12 are extremely well conserved...

Augmented Reality for Real-Time Detection and Interpretation of Colorimetric Signals Generated by Paper-Based Biosensors.

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Russell, Steven M; Doménech-Sánchez, Antonio; de la Rica, Roberto

2017-06-23

Colorimetric tests are becoming increasingly popular in point-of-need analyses due to the possibility of detecting the signal with the naked eye, which eliminates the utilization of bulky and costly instruments only available in laboratories. However, colorimetric tests may be interpreted incorrectly by nonspecialists due to disparities in color perception or a lack of training. Here we solve this issue with a method that not only detects colorimetric signals but also interprets them so that the test outcome is understandable for anyone. It consists of an augmented reality (AR) app that uses a camera to detect the colored signals generated by a nanoparticle-based immunoassay, and that yields a warning symbol or message when the concentration of analyte is higher than a certain threshold. The proposed method detected the model analyte mouse IgG with a limit of detection of 0.3 μg mL -1 , which was comparable to the limit of detection afforded by classical densitometry performed with a nonportable device. When adapted to the detection of E. coli, the app always yielded a "hazard" warning symbol when the concentration of E. coli in the sample was above the infective dose (10 6 cfu mL -1 or higher). The proposed method could help nonspecialists make a decision about drinking from a potentially contaminated water source by yielding an unambiguous message that is easily understood by anyone. The widespread availability of smartphones along with the inexpensive paper test that requires no enzymes to generate the signal makes the proposed assay promising for analyses in remote locations and developing countries.

Out of plane distortions of the heme b of Escherichia coli succinate dehydrogenase.

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Quang M Tran

Full Text Available The role of the heme b in Escherichia coli succinate dehydrogenase is highly ambiguous and its role in catalysis is questionable. To examine whether heme reduction is an essential step of the catalytic mechanism, we generated a series of site-directed mutations around the heme binding pocket, creating a library of variants with a stepwise decrease in the midpoint potential of the heme from the wild-type value of +20 mV down to -80 mV. This difference in midpoint potential is enough to alter the reactivity of the heme towards succinate and thus its redox state under turnover conditions. Our results show both the steady state succinate oxidase and fumarate reductase catalytic activity of the enzyme are not a function of the redox potential of the heme. As well, lower heme potential did not cause an increase in the rate of superoxide production both in vitro and in vivo. The electron paramagnetic resonance (EPR spectrum of the heme in the wild-type enzyme is a combination of two distinct signals. We link EPR spectra to structure, showing that one of the signals likely arises from an out-of-plane distortion of the heme, a saddled conformation, while the second signal originates from a more planar orientation of the porphyrin ring.

The Escherichia coli argW-dsdCXA genetic island is highly variable, and E. coli K1 strains commonly possess two copies of dsdCXA.

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Moritz, Rebecca L; Welch, Rodney A

2006-11-01

The genome sequences of Escherichia coli pathotypes reveal extensive genetic variability in the argW-dsdCXA island. Interestingly, the archetype E. coli K1 neonatal meningitis strain, strain RS218, has two copies of the dsdCXA genes for d-serine utilization at the argW and leuX islands. Because the human brain contains d-serine, an epidemiological study emphasizing K1 isolates surveyed the dsdCXA copy number and function. Forty of 41 (97.5%) independent E. coli K1 isolates could utilize d-serine. Southern blot hybridization revealed physical variability within the argW-dsdC region, even among 22 E. coli O18:K1:H7 isolates. In addition, 30 of 41 K1 strains, including 21 of 22 O18:K1:H7 isolates, had two dsdCXA loci. Mutational analysis indicated that each of the dsdA genes is functional in a rifampin-resistant mutant of RS218, mutant E44. The high percentage of K1 strains that can use d-serine is in striking contrast to our previous observation that only 4 of 74 (5%) isolates in the diarrheagenic E. coli (DEC) collection have this activity. The genome sequence of diarrheagenic E. coli isolates indicates that the csrRAKB genes for sucrose utilization are often substituted for dsdC and a portion of dsdX present at the argW-dsdCXA island of extraintestinal isolates. Among DEC isolates there is a reciprocal pattern of sucrose fermentation versus d-serine utilization. The ability to use d-serine is a trait strongly selected for among E. coli K1 strains, which have the ability to infect a wide range of extraintestinal sites. Conversely, diarrheagenic E. coli pathotypes appear to have substituted sucrose for d-serine as a potential nutrient.

Emergence and mechanism of carbapenem-resistant Escherichia coli in Henan, China, 2014

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Wen-juan Liang

2018-05-01

Full Text Available The emergence and dissemination of carbapenem-resistant Escherichia coli (E. coli strains is a main risk for global public health, but little is known of carbapenemase producing E. coli in Henan, China. The study was undertaken to investigate the prevalence and mechanism of carbapenem-resistant E. coli strains in a hospital in Xinxiang, Henan, China, 2014. A total of 5 carbapenemase-producing E. coli strains were screened from 1014 isolates. We found that they were all resistant to meropenem and imipenem. Amikacin showed the best sensitivity, with gentamicin coming up next. The positive rate of blaNDM was 80% (4/5. The sequencing results showed that two isolates belonged to blaNDM-1 whereas other 2 isolates carried the blaNDM-5. Other carbapenemase genes including blaIMP, blaVIM, blaKPC and blaOXA-48 were not detected. The blaCTX-M-15, blaTEM-1, sul2, aad, and aac(6”–Ib–cr were also detected. MLST analysis showed that NDM-producing E. coli were sporadic. Conjugation test indicated blaNDM could be transferred. In conclusion, the blaNDM was the principal resistance mechanism of carbapenem-resistant E. coli in the hospital, Henan, China. Keywords: blaNDM, Carbapenem-resistant, Escherichia coli

Occurrence and characterization of Shiga toxin-producing Escherichia coli O157:H7 and other non-sorbitol-fermenting E. coli in cattle and humans in urban areas of Morogoro, Tanzania

DEFF Research Database (Denmark)

Lupindu, Athumani M; Olsen, John Elmerdahl; Ngowi, Helena A

2014-01-01

Escherichia coli strains such as Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli, enterotoxigenic, attaching, and effacing E. coli, and enteroinvasive E. coli cause diarrhea in humans. Although other serotypes exist, the most commonly reported STEC in outbreaks is O157:H7. A cross-...

On-line detection of Escherichia coli intrusion in a pilot-scale drinking water distribution system.

Science.gov (United States)

Ikonen, Jenni; Pitkänen, Tarja; Kosse, Pascal; Ciszek, Robert; Kolehmainen, Mikko; Miettinen, Ilkka T

2017-08-01

Improvements in microbial drinking water quality monitoring are needed for the better control of drinking water distribution systems and for public health protection. Conventional water quality monitoring programmes are not always able to detect a microbial contamination of drinking water. In the drinking water production chain, in addition to the vulnerability of source waters, the distribution networks are prone to contamination. In this study, a pilot-scale drinking-water distribution network with an on-line monitoring system was utilized for detecting bacterial intrusion. During the experimental Escherichia coli intrusions, the contaminant was measured by applying a set of on-line sensors for electric conductivity (EC), pH, temperature (T), turbidity, UV-absorbance at 254 nm (UVAS SC) and with a device for particle counting. Monitored parameters were compared with the measured E. coli counts using the integral calculations of the detected peaks. EC measurement gave the strongest signal compared with the measured baseline during the E. coli intrusion. Integral calculations showed that the peaks in the EC, pH, T, turbidity and UVAS SC data were detected corresponding to the time predicted. However, the pH and temperature peaks detected were barely above the measured baseline and could easily be mixed with the background noise. The results indicate that on-line monitoring can be utilized for the rapid detection of microbial contaminants in the drinking water distribution system although the peak interpretation has to be performed carefully to avoid being mixed up with normal variations in the measurement data. Copyright © 2017 Elsevier Ltd. All rights reserved.

Escherichia coli Contamination of Lettuce Grown in Soils Amended with Animal Slurry

DEFF Research Database (Denmark)

Jensen, Annette Nygaard; Storm, Christina; Forslund, Anita

2013-01-01

A pilot study was conducted to assess the transfer of Escherichia coli from animal slurry fertilizer to lettuce, with E. coli serving as an indicator of fecal contamination and as an indicator for potential bacterial enteric pathogens. Animal slurry was applied as fertilizer to three Danish agric...... types between slurry, soil, and lettuce. The frequent finding of fecal-contaminated lettuce indicates that human pathogens such as Salmonella and Campylobacter can be present and represent food safety hazards.......A pilot study was conducted to assess the transfer of Escherichia coli from animal slurry fertilizer to lettuce, with E. coli serving as an indicator of fecal contamination and as an indicator for potential bacterial enteric pathogens. Animal slurry was applied as fertilizer to three Danish....... coli. A relatively higher frequency of E. coli in lettuce compared with the soil samples at harvest suggests environmental sources of fecal contamination, e.g., wildlife. The higher frequency was supported by the finding of 21 different PFGE types among the E. coli isolates, with only a few common PFGE...

Longitudinal study of transmission of Escherichia coli from broiler breeders to broilers

DEFF Research Database (Denmark)

Poulsen, Louise Ladefoged; Thoefner, Ida; Bisgaard, Magne

2017-01-01

of E. coli, isolated from broiler breeders with salpingitis, to the progeny and the possibility of subsequent first week mortality. Four parent flocks were followed during the whole production period (20-60 weeks) by post mortem and bacteriological examination of randomly selected dead birds. Newly...... selected for Pulsed-Field-Gel-Electrophoresis (PFGE) and Multi-Locus-Sequence-Typing (MLST) to determine their clonal relationships. E. coli was the main cause of both salpingitis in parents and first week mortality in broilers, and E. coli dominated the bacterial flora of the cloaca of newly hatched...... chickens. PFGE of E. coli showed identical band patterns in isolates from the three different sources indicating a transmission of E. coli from parent birds to chickens. In conclusion, E. coli isolated from salpingitis in broiler parents were found to be transmitted to broilers in which some sequence types...

Determination of the prevalence of subclinical endometritis and evaluation of molecular characterization of Escherichia coli (E-coli separated of them in mares repeat breeder in Yazd province

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Taktaz Hafshejani Taghi

2016-11-01

Full Text Available Escherichia coli are known as the most common cause of reproductive tract infection in mare. Due to the progressive process of antibiotics use and increasing prevalence of antibiotic resistance, the aim of this study is evaluate the prevalence of subclinical endometritis and antibiotic resistance genes in Escherichia coli isolated. In this study, 60 mares were used with infertility background. Diagnosis of endometritis was performed using history and ultrasonography. Cytology, culture, Antibiogram were done of samples and PCR test was used to examine the gene virulence and antibiotic resistance. E-coli bacteria was isolated 48/33 % from sample culture. In PCR test 66/21 % of bacteria had virulence gene. It was determined, the lowest resistance to chloramphenicol about 38/15% and greatest resistance into ampicillin, tetracycline and streptomycin with 23/69 percent, respectively. 93% samples cytology had neutrophil more than two and the agent of 50% showed E. coli. The cause of half of subclinical endometritis in infertile maresis E-coli bacteriaEscherichia coli are known as the most common cause of reproductive tract infection in mare. Due to the progressive process of antibiotics use and increasing prevalence of antibiotic resistance, the aim of this study is evaluate the prevalence of subclinical endometritis and antibiotic resistance genes in Escherichia coli isolated. In this study, 60 mares were used with infertility background. Diagnosis of endometritis was performed using history and ultrasonography. Cytology, culture, Antibiogram were done of samples and PCR test was used to examine the gene virulence and antibiotic resistance. E-coli bacteria was isolated 48/33 % from sample culture. In PCR test 66/21 % of bacteria had virulence gene. It was determined, the lowest resistance to chloramphenicol about 38/15% and greatest resistance into ampicillin, tetracycline and streptomycin with 23/69 percent, respectively. 93% samples cytology had

Antimicrobial susceptibilities of avian Escherichia coli isolates in ...

African Journals Online (AJOL)

Colibacillosis is a poultry disease of economic importance in Iran and all around the world. The aim of this study is to test the antibiotic sensitivity of Escherichia coli strains which were isolated in Tabriz. A total of 100 E. coli strains isolated from avian colibacillosis of 50 farms from 2008 to 2009 in Tabriz, were investigated for ...

Reduction of verotoxigenic Escherichia coli in production of fermented sausages.

Science.gov (United States)

Holck, Askild L; Axelsson, Lars; Rode, Tone Mari; Høy, Martin; Måge, Ingrid; Alvseike, Ole; L'abée-Lund, Trine M; Omer, Mohamed K; Granum, Per Einar; Heir, Even

2011-11-01

After a number of foodborne outbreaks of verotoxigenic Escherichia coli involving fermented sausages, some countries have imposed regulations on sausage production. For example, the US Food Safety and Inspection Service requires a 5 log(10) reduction of E. coli in fermented products. Such regulations have led to a number of studies on the inactivation of E. coli in fermented sausages by changing processing and post-processing conditions. Several factors influence the survival of E. coli such as pre-treatment of the meat, amount of NaCl, nitrite and lactic acid, water activity, pH, choice of starter cultures and addition of antimicrobial compounds. Also process variables like fermentation temperature and storage time play important roles. Though a large variety of different production processes of sausages exist, generally the reduction of E. coli caused by production is in the range 1-2 log(10). In many cases this may not be enough to ensure microbial food safety. By optimising ingredients and process parameters it is possible to increase E. coli reduction to some extent, but in some cases still other post process treatments may be required. Such treatments may be storage at ambient temperatures, specific heat treatments, high pressure processing or irradiation. HACCP analyses have identified the quality of the raw materials, low temperature in the batter when preparing the sausages and a rapid pH drop during fermentation as critical control points in sausage production. This review summarises the literature on the reduction verotoxigenic E. coli in production of fermented sausages. Copyright © 2011 Elsevier Ltd. All rights reserved.

Peptide nucleic acid (PNA) antisense effects in Escherichia coli

DEFF Research Database (Denmark)

Good, L; Nielsen, P E

1999-01-01

Antisense peptide nucleic acid (PNA) can be used to control cell growth, gene expression and growth phenotypes in the bacteria Escherichia coli. PNAs targeted to the RNA components of the ribosome can inhibit translation and cell growth, and PNAs targeted to mRNA can limit gene expression with gene...... and sequence specificity. In an E. coli cell extract, efficient inhibition is observed when using PNA concentrations in the nanomolar range, whereas micromolar concentrations are required for inhibition in growing cells. A mutant strain of E. coli that is more permeable to antibiotics also is more susceptible...... to antisense PNAs than the wild type. This chapter details methods for testing the antisense activities of PNA in E. coli. As an example of the specific antisense inhibition possible, we show the effects of an anti-beta-galactosidase PNA in comparison to control PNAs. With improvements in cell uptake...

Signaling and Adaptation Modulate the Dynamics of the Photosensoric Complex of Natronomonas pharaonis.

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Philipp S Orekhov

2015-10-01

Full Text Available Motile bacteria and archaea respond to chemical and physical stimuli seeking optimal conditions for survival. To this end transmembrane chemo- and photoreceptors organized in large arrays initiate signaling cascades and ultimately regulate the rotation of flagellar motors. To unravel the molecular mechanism of signaling in an archaeal phototaxis complex we performed coarse-grained molecular dynamics simulations of a trimer of receptor/transducer dimers, namely NpSRII/NpHtrII from Natronomonas pharaonis. Signaling is regulated by a reversible methylation mechanism called adaptation, which also influences the level of basal receptor activation. Mimicking two extreme methylation states in our simulations we found conformational changes for the transmembrane region of NpSRII/NpHtrII which resemble experimentally observed light-induced changes. Further downstream in the cytoplasmic domain of the transducer the signal propagates via distinct changes in the dynamics of HAMP1, HAMP2, the adaptation domain and the binding region for the kinase CheA, where conformational rearrangements were found to be subtle. Overall these observations suggest a signaling mechanism based on dynamic allostery resembling models previously proposed for E. coli chemoreceptors, indicating similar properties of signal transduction for archaeal photoreceptors and bacterial chemoreceptors.

Evaluation of the efficacy of an autogenous Escherichia coli vaccine in broiler breeders

DEFF Research Database (Denmark)

Li, Lili; Thøfner, Ida; Christensen, Jens Peter

2017-01-01

vaccine in broiler breeders. Three groups of 28 weeks old broiler breeders (unvaccinated, vaccinated once and twice, respectively) were challenged with a homologous E. coli strain (same strain as included in the vaccine) or a heterologous challenge strain in an experimental ascending model. The clinical...... infection, significant protection of an autogenous E. coli vaccine against neither a homologous nor a heterologous E. coli challenge could not be documented.......In poultry production Escherichia coli autogenous vaccines are often used. However, the efficacy of autogenous E. coli vaccinations has not been evaluated experimentally in chickens after start of lay. The aim of the present study was to evaluate the protective effect of an autogenous E. coli...

Transcriptome of E. coli K1 bound to human brain microvascular endothelial cells

OpenAIRE

Xie, Yi; Parthasarathy, Geetha; Di Cello, Francescopaolo; Teng, Ching-Hao; Paul-Satyaseela, Maneesh; Kim, Kwang Sik

2007-01-01

Escherichia coli K1 is the most common Gram-negative organism causing neonatal meningitis. Binding to human brain microvascdular endothelial cells (HBMEC) is an essential step for E. coli K1 traversal of the blood-brain barrier. In this study, we examined expression profiles of E. coli K1 strain RS218 during its binding to HBMEC. Comparison of HBMEC-bound E. coli K1 with collagen-bound E. coli revealed more than one hundred genes whose expression patterns were significantly changed in HBMEC-b...

[Cloning of Clostridium perfringens alpha-toxin gene and extracellular expression in Escherichia coli].

Science.gov (United States)

Inoue, Masaharu; Kikuchi, Maho; Komoriya, Tomoe; Watanabe, Kunitomo; Kouno, Hideki

2007-01-01

Clostridium perfringens (C. perfringens) is a Gram-positive bacterial pathogen that widely propagets in the soil and the gastrointestinal tract of human and animals. This bacteria causes food poisoning, gas gangrene and other various range of infectious diseases. But there is no standard diagnosis method of C. perfringens. In order to develop a new type of immunoassay for clinical purpose, we studied expression and extracellular secretion of recombinant alpha-toxin having enzyme activity in E. coli expression system. Cloning was carried out after PCR amplification from C. perfringens GAI 94074 which was clinical isolate. Three kinds of fragment were cloned using pET100/D-TOPO vector. These fragments coded for ribosome binding site, signal peptide, and alpha-toxin gene respectively. Recombinant pET100 plasmid transformed into TOP 10 cells and the obtained plasmids were transformed into BL21 (DE3) cells. Then, the transformants were induced expression with IPTG. In conclusion, we successfully cloned, expressed and exteracellular secreted C. perfringens alpha-toxin containing signal peptide. Biologically, the obtained recombinant protein was positive for phospholipase C activity.

Impact of intramammary treatment on gene expression profiles in bovine Escherichia coli mastitis.

Directory of Open Access Journals (Sweden)

Anja Sipka

Full Text Available Clinical mastitis caused by E. coli accounts for significant production losses and animal welfare concerns on dairy farms worldwide. The benefits of therapeutic intervention in mild to moderate cases are incompletely understood. We investigated the effect of intramammary treatment with cefapirin alone or in combination with prednisolone on gene expression profiles in experimentally-induced E. coli mastitis in six mid-lactating Holstein Friesian cows. Cows were challenged with E. coli in 3 quarters and received 4 doses of 300 mg cefapirin in one quarter and 4 doses of 300 mg cefapirin together with 20 mg prednisolone in another quarter. At 24 h (n = 3 or 48 h (n = 3 post-challenge, tissue samples from control and treated quarters were collected for microarray analysis. Gene expression analysis of challenged, un-treated quarters revealed an up-regulation of transcripts associated with immune response functions compared to un-challenged quarters. Both treatments resulted in down-regulation of these transcripts compared to challenged, un-treated quarters most prominently for genes representing Chemokine and TLR-signaling pathways. Gene expression of Lipopolysaccharide Binding Protein (LBP, CCL2 and CXCL2 were only significantly down-regulated in cefapirin-prednisolone-treated quarters compared to un-treated controls. Down-regulation of chemokines was further confirmed on the basis of protein levels in milk whey for CXCL1, CXCL2 and CXCL8 in both treatments with a greater decrease in cefapirin-prednisolone-treated quarters. The data reveal a significant effect of treatment on cell recruitment with a more pronounced effect in cefapirin-prednisolone treated quarters. Provided a rapid bacteriological clearance, combination therapy may prevent neutrophil-induced tissue damage and promote recovery of the gland.

Seroprevalence of Escherichia coli in traditional cheeses manufactured in Maragheh rural

Directory of Open Access Journals (Sweden)

S Mahdavi

2014-11-01

Full Text Available Coliforms and Escherichia coli are major microbial indicators in the accessing the quality of foodstuffs. The presence of these bacteria in foods is considered as an indication of fecal contamination. E. coli O157:H7 is the most pathogenic strain that is transmitted to human through animal-foods. This study was performed on 100 traditional cheese samples manufactured in Maragheh rural to determine the seroprevalence of E. coli. The samples were analyzed with standard microbiological methods followed by biochemical confirmatory tests. Afterwards, the isolates were assayed for the detection of O-serotypes using direct agglutination method. Among the 100 cheese samples, E. coli O157serotypewas not detected in any sample. However, other E. coli serotypes including 32 isolates of non-O157 serotypes were detected. Among the isolates, enteropathogenic, enterotoxigenic and enterohaemorhhagic serogruops was also detected.

Dialogue between E. coli free radical pathways and the mitochondria of C. elegans.

Science.gov (United States)

Govindan, J Amaranath; Jayamani, Elamparithi; Zhang, Xinrui; Mylonakis, Eleftherios; Ruvkun, Gary

2015-10-06

The microbial world presents a complex palette of opportunities and dangers to animals, which have developed surveillance and response strategies to hints of microbial intent. We show here that the mitochondrial homeostatic response pathway of the nematode Caenorhabditis elegans responds to Escherichia coli mutations that activate free radical detoxification pathways. Activation of C. elegans mitochondrial responses could be suppressed by additional mutations in E. coli, suggesting that C. elegans responds to products of E. coli to anticipate challenges to its mitochondrion. Out of 50 C. elegans gene inactivations known to mediate mitochondrial defense, we found that 7 genes were required for C. elegans response to a free radical producing E. coli mutant, including the bZip transcription factor atfs-1 (activating transcription factor associated with stress). An atfs-1 loss-of-function mutant was partially resistant to the effects of free radical-producing E. coli mutant, but a constitutively active atfs-1 mutant growing on wild-type E. coli inappropriately activated the pattern of mitochondrial responses normally induced by an E. coli free radical pathway mutant. Carbonylated proteins from free radical-producing E. coli mutant may directly activate the ATFS-1/bZIP transcription factor to induce mitochondrial stress response: feeding C. elegans with H2O2-treated E. coli induces the mitochondrial unfolded protein response, and inhibition of a gut peptide transporter partially suppressed C. elegans response to free radical damaged E. coli.

The population structure of Escherichia coli isolated from subtropical and temperate soils

Science.gov (United States)

Byappanahalli, Muruleedhara N.; Yan, Tao; Hamilton, Matthew J.; Ishii, Satoshi; Fujioka, Roger S.; Whitman, Richard L.; Sadowsky, Michael J.

2012-01-01

While genotypically-distinct naturalized Escherichia coli strains have been shown to occur in riparian soils of Lake Michigan and Lake Superior watersheds, comparative analyses of E. coli populations in diverse soils across a range of geographic and climatic conditions have not been investigated. The main objectives of this study were to: (a) examine the population structure and genetic relatedness of E. coli isolates collected from different soil types on a tropical island (Hawaii), and (b) determine if E. coli populations from Hawaii and temperate soils (Indiana, Minnesota) shared similar genotypes that may be reflective of biome-related soil conditions. DNA fingerprint and multivariate statistical analyses were used to examine the population structure and genotypic characteristics of the E. coli isolates. About 33% (98 of 293) of the E. coli from different soil types and locations on the island of Oahu, Hawaii, had unique DNA fingerprints, indicating that these bacteria were relatively diverse; the Shannon diversity index for the population was 4.03. Nearly 60% (171 of 293) of the E. coli isolates from Hawaii clustered into two major groups and the rest, with two or more isolates, fell into one of 22 smaller groups, or individual lineages. Multivariate analysis of variance of 89, 21, and 106 unique E. coli DNA fingerprints for Hawaii, Indiana, and Minnesota soils, respectively, showed that isolates formed tight cohesive groups, clustering mainly by location. However, there were several instances of clonal isolates being shared between geographically different locations. Thus, while nearly identical E. coli strains were shared between disparate climatologically- and geographically-distinct locations, a vast majority of the soil E. coli strains were genotypically diverse and were likely derived from separate lineages. This supports the hypothesis that these bacteria are not unique and multiple genotypes can readily adapt to become part of the soil autochthonous

Prodigiosin - A Multifaceted Escherichia coli Antimicrobial Agent.

Directory of Open Access Journals (Sweden)

Tjaša Danevčič

Full Text Available Despite a considerable interest in prodigiosin, the mechanism of its antibacterial activity is still poorly understood. In this work, Escherichia coli cells were treated with prodigiosin to determine its antimicrobial effect on bacterial physiology. The effect of prodigiosin was concentration dependent. In prodigiosin treated cells above MIC value no significant DNA damage or cytoplasmic membrane disintegration was observed. The outer membrane, however, becomes leaky. Cells had severely decreased respiration activity. In prodigiosin treated cells protein and RNA synthesis were inhibited, cells were elongated but could not divide. Pre-treatment with prodigiosin improved E. coli survival rate in media containing ampicillin, kanamycin and erythromycin but not phleomycin. The results suggest that prodigiosin acts as a bacteriostatic agent in E. coli cells. If prodigiosin was diluted, cells resumed growth. The results indicate that prodigiosin has distinct mode of antibacterial action in different bacteria.

Molecular detection and antimicrobial resistance of diarrheagenic Escherichia coli strains isolated from diarrheal cases

International Nuclear Information System (INIS)

Aslani, Mehdi M.; Salmanzadeh-Ahrabi, S.; Jafari, F.; Zali, Reza M.; Mani, M.; Alikhani, Yousef M.

2008-01-01

Objective was to identify and classify Iranian isolates of diarrheagenic Escherichia coli (E. coli) on the basis of presence of virulence genes and to determine antibiotic susceptibility of isolated strains. The current cross-sectional study was conducted in 2005 at the Pasteur Institute, Tehran, Iran. One hundred and ninety-three diarrheagenic E. coli isolated from diarrheal patients in different regions of Iran were included in current study. Virulence factors genees for diarrheagenic E. coli were detected by polymerase chain reaction. Of the 193 diarrheagenic E. coli detected by PCR, 86(44.5%) were Shiga toxin-producing E. coli (STEC), 74 (38.4%) enteropathogenic E. coli (EPEC), 19 (9.8%) enteroaggregative E. coli and 14 (7.3%) enterotoxigenic E. coli isolates. Susceptibility to 12 clinically important antimicrobial agents was determined for 193 strains of diarrhheagenic E. coli. A high incidence of resistance to tetracycline (63%), ampicillin (62%), streptomycin (56%), amoxicillin/clavulanic acid (44.5%), trimetoprim/sulphamethoxazole (39.5%) and cephalothin (37%) was observed. The STEC and EPEC strains with high resistance to tetracycline and ampicillin but highly susceptible to quinolones are among the most important causative agent of diarrhea in Iran. This study suggests that antimicrobial resistance is wide spread among E. coli strains colonizing Iranian patients. Guidelines for appropriate use of antibiotics in developing countries require updating. (author)

Thermal inactivation of Escherichia coli 0157:H7 (ECOH) and non-0157 Shiga toxin-producing E.coli (STEC)in mechanically tenderized veal

Science.gov (United States)

We quantified thermal destruction of Shiga toxin-producing Escherichia coli O157:H7 (ECOH) and Shiga toxin-producing non-O157 E. coli (STEC) cells within mechanically tenderized veal cutlets following cooking on an electric skillet. For each of five trials, flattened veal cutlets (ca. 71.6 g; ca. 1/...

In-depth characterization of the fluorescent signal of HyPer, a probe for hydrogen peroxide, in bacteria exposed to external oxidative stress.

Science.gov (United States)

Lim, Joseph B; Barker, Kimberly A; Huang, Beijing K; Sikes, Hadley D

2014-11-01

Genetically encoded, fluorescent biosensors have been developed to probe the activities of various signaling molecules inside cells ranging from changes in intracellular ion concentrations to dynamics of lipid second messengers. HyPer is a member of this class of biosensors and is the first to dynamically respond to hydrogen peroxide (H2O2), a reactive oxygen species that functions as a signaling molecule. However, detailed characterization of HyPer's signal is not currently available within the context of bacteria exposed to external oxidative stress, which occurs in the immunological response of higher organisms against invasive pathogenic bacteria. Here, we performed this characterization, specifically in Escherichia coli exposed to external H2O2. We found that the temporal behavior of the signal does not correspond exactly to peroxide concentration in the system as a function of time and expression of the sensor decreases the peroxide scavenging activity of the cell. We also determined the effects of cell number, both before and after normalization of externally added H2O2 to the number of cells. Finally, we report quantitative characteristics of HyPer's signal in this context, including the dynamic range of the signal, the signal-to-noise ratio, and the half saturation constant. These parameters show statistically meaningful differences in signal between two commonly used strains of E. coli, demonstrating how signal can vary with strain. Taken together, our results establish a systematic, quantitative framework for researchers seeking to better understand the role of H2O2 in the immunological response against bacteria, and for understanding potential differences in the details of HyPer's quantitative performance across studies. Copyright © 2014 Elsevier B.V. All rights reserved.

prevalence of escherichia coli 0157:h7 in fresh and roasted beef

African Journals Online (AJOL)

DR. AMINU

The prevalence of Enterohemorrhagic Escherichia coli 0157:H7 in 300 fresh beef and 150 roasted beef samples from ... likely cause of E. coli O157:H7 infection is undercooked ground beef. ..... coli O157:H7 in a sheep model. Appl. Environ.

Evaluation of mericon E. coli O157 Screen Plus and mericon E. coli STEC O-Type Pathogen Detection Assays in Select Foods: Collaborative Study, First Action 2017.05.

Science.gov (United States)

Bird, Patrick; Benzinger, M Joseph; Bastin, Benjamin; Crowley, Erin; Agin, James; Goins, David; Armstrong, Marcia

2018-05-01

QIAGEN mericon Escherichia coli O157 Screen Plus and mericon E. coli Shiga toxin-producing E. coli (STEC) O-Type Pathogen Detection Assays use Real-Time PCR technology for the rapid, accurate detection of E. coli O157 and the "big six" (O26, O45, O103, O111, O121, O145) (non-O157 STEC) in select food types. Using a paired study design, the assays were compared with the U.S. Department of Agriculture, Food Safety Inspection Service Microbiology Laboratory Guidebook Chapter 5.09 reference method for the detection of E. coli O157:H7 in raw ground beef. Both mericon assays were evaluated using the manual and an automated DNA extraction method. Thirteen technicians from five laboratories located within the continental United States participated in the collaborative study. Three levels of contamination were evaluated. Statistical analysis was conducted according to the probability of detection (POD) statistical model. Results obtained for the low-inoculum level test portions produced a difference between laboratories POD (dLPOD) value with a 95% confidence interval of 0.00 (-0.12, 0.12) for the mericon E. coli O157 Screen Plus with manual and automated extraction and mericon E. coli STEC O-Type with manual extraction and -0.01 (-0.13, 0.10) for the mericon E. coli STEC O-Type with automated extraction. The dLPOD results indicate equivalence between the candidate methods and the reference method.

Ecological and genetic determinants of plasmid distribution in Escherichia coli.

Science.gov (United States)

Medaney, Frances; Ellis, Richard J; Raymond, Ben

2016-11-01

Bacterial plasmids are important carriers of virulence and antibiotic resistance genes. Nevertheless, little is known of the determinants of plasmid distribution in bacterial populations. Here the factors affecting the diversity and distribution of the large plasmids of Escherichia coli were explored in cattle grazing on semi-natural grassland, a set of populations with low frequencies of antibiotic resistance genes. Critically, the population genetic structure of bacterial hosts was chararacterized. This revealed structured E. coli populations with high diversity between sites and individuals but low diversity within cattle hosts. Plasmid profiles, however, varied considerably within the same E. coli genotype. Both ecological and genetic factors affected plasmid distribution: plasmid profiles were affected by site, E. coli diversity, E. coli genotype and the presence of other large plasmids. Notably 3/26 E. coli serotypes accounted for half the observed plasmid-free isolates indicating that within species variation can substantially affect carriage of the major conjugative plasmids. The observed population structure suggest that most of the opportunities for within species plasmid transfer occur between different individuals of the same genotype and support recent experimental work indicating that plasmid-host coevolution, and epistatic interactions on fitness costs are likely to be important in determining occupancy. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

Meningitic Escherichia coli K1 penetration and neutrophil transmigration across the blood-brain barrier are modulated by alpha7 nicotinic receptor.

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Feng Chi

Full Text Available Alpha7 nicotinic acetylcholine receptor (nAChR, an essential regulator of inflammation, is abundantly expressed in hippocampal neurons, which are vulnerable to bacterial meningitis. However, it is unknown whether α7 nAChR contributes to the regulation of these events. In this report, an aggravating role of α7 nAChR in host defense against meningitic E. coli infection was demonstrated by using α7-deficient (α7(-/- mouse brain microvascular endothelial cells (BMEC and animal model systems. As shown in our in vitro and in vivo studies, E. coli K1 invasion and polymorphonuclear neutrophil (PMN transmigration across the blood-brain barrier (BBB were significantly reduced in α7(-/- BMEC and α7(-/- mice. Stimulation by nicotine was abolished in the α7(-/- cells and animals. The same blocking effect was achieved by methyllycaconitine (α7 antagonist. The tight junction molecules occludin and ZO-1 were significantly reduced in the brain cortex of wildtype mice infected with E. coli and treated with nicotine, compared to α7(-/- cells and animals. Decreased neuronal injury in the hippocampal dentate gyrus was observed in α7(-/- mice with meningitis. Proinflammatory cytokines (IL-1β, IL-6, TNFα, MCP-1, MIP-1alpha, and RANTES and adhesion molecules (CD44 and ICAM-1 were significantly reduced in the cerebrospinal fluids of the α7(-/- mice with E. coli meningitis. Furthermore, α7 nAChR is the major calcium channel for nicotine- and E. coli K1-increased intracellular calcium concentrations of mouse BMEC. Taken together, our data suggest that α7 nAChR plays a detrimental role in the host defense against meningitic infection by modulation of pathogen invasion, PMN recruitment, calcium signaling and neuronal inflammation.

Plasmid Conjugation in E. coli and Drug Resistance | Igwe ...

African Journals Online (AJOL)

This study aimed at determining the antibiotics susceptibility pattern of E. coli isolates claimed to be multidrug resistance using disc diffusion method. It also determined the presence of transferable resistance plasmids through conjugation and evaluated the medical significance of plasmid encoding E. coli and drug ...

Anthranoid self-medication causing rapid development of melanosis coli

NARCIS (Netherlands)

M. Willems; H.R. van Buuren (Henk); R.R. de Krijger (Ronald)

2003-01-01

textabstractIt is widely known that long-term use of anthranoid-containing laxatives is the cause of melanosis coli. We describe a case of melanosis coli, which occurred in a 39-year-old liver transplant patient who took an over-the-counter product containing aloe, rheum and

Molecular typing of uropathogenic E. coli strains by the ERIC-PCR method.

Science.gov (United States)

Ardakani, Maryam Afkhami; Ranjbar, Reza

2016-04-01

Escherichia coli (E. coli) is the most common cause of urinary infections in hospitals. The aim of this study was to evaluate the ERIC-PCR method for molecular typing of uropathogenic E. coli strains isolated from hospitalized patients. In a cross sectional study, 98 E. coli samples were collected from urine samples taken from patients admitted to Baqiyatallah Hospital from June 2014 to January 2015. The disk agar diffusion method was used to determine antibiotic sensitivity. DNA proliferation based on repetitive intergenic consensus was used to classify the E. coli strains. The products of proliferation were electrophoresed on 1.5% agarose gel, and their dendrograms were drawn. The data were analyzed by online Insillico software. The method used in this research proliferated numerous bands (4-17 bands), ranging from 100 to 3000 base pairs. The detected strains were classified into six clusters (E1-E6) with 70% similarity between them. In this study, uropathogenic E. coli strains belonged to different genotypic clusters. It was found that ERIC-PCR had good differentiation power for molecular typing of uropathogenic E. coli strains isolated from the patients in the study.

Identifying New Small Proteins in Escherichia coli.

Science.gov (United States)

VanOrsdel, Caitlin E; Kelly, John P; Burke, Brittany N; Lein, Christina D; Oufiero, Christopher E; Sanchez, Joseph F; Wimmers, Larry E; Hearn, David J; Abuikhdair, Fatimeh J; Barnhart, Kathryn R; Duley, Michelle L; Ernst, Sarah E G; Kenerson, Briana A; Serafin, Aubrey J; Hemm, Matthew R

2018-04-12

The number of small proteins (SPs) encoded in the Escherichia coli genome is unknown, as current bioinformatics and biochemical techniques make short gene and small protein identification challenging. One method of small protein identification involves adding an epitope tag to the 3' end of a short open reading frame (sORF) on the chromosome, with synthesis confirmed by immunoblot assays. In this study, this strategy was used to identify new E. coli small proteins, tagging 80 sORFs in the E. coli genome, and assayed for protein synthesis. The selected sORFs represent diverse sequence characteristics, including degrees of sORF conservation, predicted transmembrane domains, sORF direction with respect to flanking genes, ribosome binding site (RBS) prediction, and ribosome profiling results. Of 80 sORFs, 36 resulted in encoded synthesized proteins-a 45% success rate. Modeling of detected versus non-detected small proteins analysis showed predictions based on RBS prediction, transcription data, and ribosome profiling had statistically-significant correlation with protein synthesis; however, there was no correlation between current sORF annotation and protein synthesis. These results suggest substantial numbers of small proteins remain undiscovered in E. coli, and existing bioinformatics techniques must continue to improve to facilitate identification. © 2018 The Authors. Proteomics Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, Towson University.

The significance of E. coli treatment in perinatal period

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Ljubić Aleksandar D.

2016-01-01

Full Text Available Introduction: Bacteriuria of pregnancy is a common condition. Case report: Patient, 30-years, pregnant woman. During pregnancy, E. coli infection recurred in 4 times, applied Cephalexin and Ceftriaxone. The delivery was terminated by CS, GW 38; girl infant, AS 9. After the period of lactation: secretory status - the patient was a secretor of A and H blood type substance; ultrasonography and contrast radiography - presence of the third kidney. The therapy was added by vaccine UroVaxom, and there was no E. coli infection during 2 years follow up period. The Child is now 7 years old girl, having brilliant psychomotorical development. Possible child brain damage, lung damage, mental diseases are the reason for necessity E. coli infection treatment during pregnancy. Conclusion: All pregnant women should be screened for bacteriuria. E. coli is most commonly sensitive to group B antibiotics (cephalexin and amoxicillin, safe to be included in pregnancy. Long-term follow up of infants born from mothers having bacterial infection during pregnancy is necessary.

Treatment for bovine Escherichia coli mastitis - an evidence-based approach.

Science.gov (United States)

Suojala, L; Kaartinen, L; Pyörälä, S

2013-12-01

Bovine mastitis caused by Escherichia coli can range from being a subclinical infection of the mammary gland to a severe systemic disease. Cow-dependent factors such as lactation stage and age affect the severity of coliform mastitis. Evidence for the efficacy of antimicrobial treatment for E. coli mastitis is very limited. Antimicrobial resistance is generally not a limiting factor for treatment, but it should be monitored to detect changes in resistance profiles. The only antimicrobials for which there is some scientific evidence of beneficial effects in the treatment for E. coli mastitis are fluoroquinolones and cephalosporins. Both are critically important drugs, the use of which in animals destined for food should be limited to specific indications and should be based on bacteriological diagnosis. The suggested routine protocol in dairy herds could target the primary antimicrobial treatment for mastitis, specifically infections caused by gram-positive bacteria. In E. coli mastitis with mild to moderate clinical signs, a non-antimicrobial approach (anti-inflammatory treatment, frequent milking and fluid therapy) should be the first option. In cases of severe E. coli mastitis, parenteral administration of fluoroquinolones, or third- or fourth-generation cephalosporins, is recommended due to the risk of unlimited growth of bacteria in the mammary gland and ensuing bacteremia. Evidence for the efficacy of intramammary-administered antimicrobial treatment for E. coli mastitis is so limited that it cannot be recommended. Nonsteroidal anti-inflammatory drugs have documented the efficacy in the treatment for E. coli mastitis and are recommended for supportive treatment for clinical mastitis. © 2013 John Wiley & Sons Ltd.

Mechanisms of antibiotic resistance to enrofloxacin in uropathogenic Escherichia coli in dog

Science.gov (United States)

Escherichia coli (E. coli) urinary tract infections (UTIs) are becoming a serious problem both for pets and humans (zoonosis) due to the close contact and to the increasing resistance to antibiotics. Canine E. coli represents a good experimental model useful to study this pathology. Moreover, as des...

Type 1 fimbrial expression enhances Escherichia coli virulence for the urinary tract

DEFF Research Database (Denmark)

Connell, Hugh; Agace, William; Klemm, Per

1996-01-01

of Escherichia coli for the urinary tract by promoting bacterial persistence and enhancing the inflammatory responce to infection. In a clinical study, we observed that disease severity was greater in children infected with E. coli O1:K1:H7 isolates expressing type 1 fimbriae than in those infected with type 1...... negative isolates of the same serotype. The E. coli O1:K1:H7 isolates had the same electrophoretic type, were hemolysin-negative, expressed P fimbriae, and carried the fim DNA sequences. When tested in a mouse urinary tract infection model, the type 1-positive E. coli O1:K1:H7 isolates survived inhigher...... urinary tract infection model. E. coli CN1016 reconstituted with type 1 fimbriae had restored virulence similar to that of the wild-type parent strain. These results show that type 1 fimbriae in the genetic background of a uropathogenic strain contribute to the pathogenesis of E. coli in the urinary tract....

Vaginal Lactobacillus isolates inhibit uropathogenic Escherichia coli.

OpenAIRE

Atassi , Fabrice; Brassart , Dominique; Grob , Philipp; Graf , Federico; Servin , Alain ,

2006-01-01

The purpose of this study was to investigate the antibacterial activities of Lactobacillus jensenii KS119.1 and KS121.1, and Lactobacillus gasserii KS120.1 and KS124.3 strains isolated from the vaginal microflora of healthy women, against uropathogenic, diffusely adhering Afa/Dr Escherichia coli (Afa/Dr DAEC) strains IH11128 and 7372 involved in recurrent cystitis. We observed that some of the Lactobacillus isolates inhibited the growth and decreased the viability of E. coli IH11128 and 7372....

Removal of Escherichia coli via low frequency electromagnetic field in riverbank filtration system.

Science.gov (United States)

Selamat, Rossitah; Abustan, Ismail; Rizal Arshad, Mohd; Mokhtar Kamal, Nurul Hana

2018-04-01

The removal of Escherichia coli (E. coli) via low frequency of electromagnetic field (LF-EMF) with different magnetic field was studied. LF-EMF is known as a high magnetic susceptibility method, which could affect E. coli growth without the usage of chemicals. The aim of this study was to investigate the removal of E. coli by using LF-EMF in water abstraction for the riverbank filtration (RBF) application. The effect of LF-EMF with the intensity of 2 to 10mT and 50Hz on coiled column of 1mm copper wire at 1 to 6 hours was assessed. The removal of E. coli after exposing to LF-EMF on the column model was measured using most probable number (MPN/100mL) and colonies forming unit (CFU/100mL) methods. Water flows into the column were varied up to 6 hours and with flowrate of 100 mL/min. Experimental results demonstrate that 100% of E. coli was removed at 8mT after 6 hours exposure. The magnetic field at 10mT removed 100% of E. coli after 4 hours exposure. The results obtained in this study proved that the LF-EMF was efficient in E. coli removal from RBF system. These finding indicated that the LF-EMF intensities and time of exposure can affect the removal of E. coli.

Analysis of early-onset bloodstream infection due to Escherichia coli infection in premature babies

OpenAIRE

Chen, I-Lun; Huang, Hsin-Chun; Wu, Chih-Te; Ou-Yang, Mei-Chen; Chung, Mei-Yung; Chen, Chih-Cheng; Suen, Jau-Ling; Hung, Chih-Hsing

2017-01-01

Abstract In early-onset bacteremia among preterm neonates, Escherichia coli (E. coli) is the main pathogen and can cause a high mortality rate. Thus, the predictive factors of mortality and extended-spectrum ?-lactamase (ESBL)-producing E. coli in preterm babies with E. coli early-onset bacteremia were reported. We retrospectively reviewed preterm neonates who had E. coli bacteremia occurring within 3 days after birth between 2004 and 2015. Maternal and perinatal information were collected fr...

75 FR 14607 - Small Entity Compliance Guide: Bottled Water: Total Coliform and E. coli

Science.gov (United States)

2010-03-26

...] Small Entity Compliance Guide: Bottled Water: Total Coliform and E. coli; Availability AGENCY: Food and... the availability of a guidance for industry entitled ``Bottled Water: Total Coliform and E. coli... determine whether any of the coliform organisms are Escherichia coli (E. coli), an indicator of fecal...

Identification of genes important for growth of asymptomatic bacteriuria Escherichia coli in urine.

Science.gov (United States)

Vejborg, Rebecca M; de Evgrafov, Mari R; Phan, Minh Duy; Totsika, Makrina; Schembri, Mark A; Hancock, Viktoria

2012-09-01

Escherichia coli is the most important etiological agent of urinary tract infections (UTIs). Unlike uropathogenic E. coli, which causes symptomatic infections, asymptomatic bacteriuria (ABU) E. coli strains typically lack essential virulence factors and colonize the bladder in the absence of symptoms. While ABU E. coli can persist in the bladder for long periods of time, little is known about the genetic determinants required for its growth and fitness in urine. To identify such genes, we have employed a transposon mutagenesis approach using the prototypic ABU E. coli strain 83972 and the clinical ABU E. coli strain VR89. Six genes involved in the biosynthesis of various amino acids and nucleobases were identified (carB, argE, argC, purA, metE, and ilvC), and site-specific mutants were subsequently constructed in E. coli 83972 and E. coli VR89 for each of these genes. In all cases, these mutants exhibited reduced growth rates and final cell densities in human urine. The growth defects could be complemented in trans as well as by supplementation with the appropriate amino acid or nucleobase. When assessed in vivo in a mouse model, E. coli 83972carAB and 83972argC showed a significantly reduced competitive advantage in the bladder and/or kidney during coinoculation experiments with the parent strain, whereas 83972metE and 83972ilvC did not. Taken together, our data have identified several biosynthesis pathways as new important fitness factors associated with the growth of ABU E. coli in human urine.

Effect of high pressurized carbon dioxide on Escherichia coli ...

African Journals Online (AJOL)

Carbon dioxide at high pressure can retard microbial growth and sometimes kill microorganisms depending on values of applied pressure, temperature and exposure time. In this study the effect of high pressurised carbon dioxide (HPCD) on Escherichia coli was investigated. Culture of E. coli was subjected to high ...

Prevalence of Aeromonas species and Escherichia coli in stool ...

African Journals Online (AJOL)

Background: Diarrhoea is one of the main causes of mortality and morbidity in childhood. Bacterial diarrhoea is a common disorder. Aeromonas species and Escherichia coli (E. coli) are some of the aetiological agents associated with diarrhoea in children. Objective: To determine the prevalence of Aeromonas species and ...

Dietary N-Carbamylglutamate Supplementation Boosts Intestinal Mucosal Immunity in Escherichia coli Challenged Piglets.

Directory of Open Access Journals (Sweden)

Fengrui Zhang

Full Text Available N-carbamylglutamate (NCG has been shown to enhance performance in neonatal piglets. However, few studies have demonstrated the effect of NCG on the intestinal mucosal barrier. This study was conducted to determine the effects of dietary NCG supplementation on intestinal mucosal immunity in neonatal piglets after an Escherichia coli (E. coli challenge. New-born piglets (4 d old were assigned randomly to one of four treatments (n = 7, including (I sham challenge, (II sham challenge +50 mg/kg NCG, (III E. coli challenge, and (IV E. coli challenge +50 mg/kg NCG. On d 8, pigs in the E. coli challenge groups (III and IV were orally challenged with 5 mL of E. coli K88 (10(8 CFU/mL, whereas pigs in the sham challenge groups (I and II were orally dosed with an equal volume of water. On d 13, all piglets were sacrificed, and samples were collected and examined. The results show that average daily gain in the E. coli challenged piglets (III and IV was decreased (PE.coli<0.05. However, it tended to be higher in the NCG treated piglets (II and IV. Ileum secretory IgA, as well as IFN-γ, IL-2, IL-4 and IL-10 in ileal homogenates, were increased in E. coli challenged piglets (III and IV. Similarly, ileum SIgA and IL-10 levels, and CD4(+ percentage in NCG treated piglets (II and IV were higher than no-NCG treated piglets (PNCG<0.05. However, the IL-2 level was only decreased in the piglets of E. coli challenge + NCG group (IV compared with E. coli challenge group (III (P<0.05. No change in the IL-2 level of the sham challenged piglets (III was observed. In conclusion, dietary NCG supplementation has some beneficial effects on intestinal mucosal immunity in E. coli challenged piglets, which might be associated with stimulated lymphocyte proliferation and cytokine synthesis. Our findings have an important implication that NCG may be used to reduce diarrhea in neonatal piglets.

Genetic determinants of heat resistance in Escherichia coli

Directory of Open Access Journals (Sweden)

Ryan eMercer

2015-09-01

Full Text Available Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR. This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli.

Involvement of UV-inducible repair in pyrimidine dimer excision in Escherichia coli

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Masek, F.; Sedliakova, M.

1978-01-01

The influence of UV radiation on pyrimidine dimer excision in the cells of three excision-proficient E.coli strains was studied. For this purpose cells were irradiated with a first fluence of 300 ergs/mm 2 and at different time intervals with a second fluence of 500 ergs/mm 2 . After the second fluence dimer excision was found to be partly inhibited in E.coli B/r Hcr + and E.coli 15 555-7, but not in E.coli K12 SR20. (author)

Involvement of UV-inducible repair in pyrimidine dimer excision in Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Masek, F; Sedliakova, M [Slovenska Akademia Vied, Bratislava (Czechoslovakia)

1978-11-15

The influence of UV radiation on pyrimidine dimer excision in the cells of three excision-proficient E.coli strains was studied. For this purpose cells were irradiated with a first fluence of 300 ergs/mm/sup 2/ and at different time intervals with a second fluence of 500 ergs/mm/sup 2/. After the second fluence dimer excision was found to be partly inhibited in E.coli B/r Hcr/sup +/ and E.coli 15 555-7, but not in E.coli K12 SR20.

Heterologous expression of enterocin A, a bacteriocin from Enterococcus faecium, fused to a cellulose-binding domain in Escherichia coli results in a functional protein with inhibitory activity against Listeria.

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Klocke, Michael; Mundt, Kerstin; Idler, Frank; Jung, Sabrina; Backhausen, Jan E

2005-06-01

The genes for the bacteriocins enterocin A and B were isolated from Enterococcus faecium ATB 197a. Using the pET37b(+) vector, the enterocin genes were fused to an Escherichia coli specific export signal sequence, a cellulose-binding domain (CBD(cenA)) and a S-tag under the control of a T7lac promotor. The constructs were subsequently cloned into E. coli host cells. The expression of the recombinant enterocins had different effects on both the host cells and other Gram-positive bacteria. The expression of entA in Esc. coli led to the synthesis and secretion of functional active enterocin A fusion proteins, which were active against some Gram-positive indicator bacteria, but did not influence the viability of the host cells. In contrast, the expression of enterocin B fusion proteins led to a reduced viability of the host cells, indicating a misfolding of the protein or interference with the cellular metabolism of Esc. coli. Indicator strains of Gram-positive bacteria were not inhibited by purified enterocin B fusion proteins. However, recombinant enterocin B displayed inhibitory activity after the proteolytic cleavage of the fused peptides.

Factors affecting Escherichia coli concentrations at Lake Erie public bathing beaches

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Francy, Donna S.; Darner, Robert A.

1998-01-01

The environmental and water-quality factors that affect concentrations of Escherichia coli (E. coli) in water and sediment were investigated at three public bathing beachesEdgewater Park, Villa Angela, and Sims Parkin the Cleveland, Ohio metropolitan area. This study was done to aid in the determination of safe recreational use and to help water- resource managers assess more quickly and accurately the degradation of recreational water quality. Water and lake-bottom sediments were collected and ancillary environmental data were compiled for 41 days from May through September 1997. Water samples were analyzed for E. coli concentrations, suspended sediment concentrations, and turbidity. Lake- bottom sediment samples from the beach area were analyzed for E. coli concentrations and percent dry weight. Concentrations of E. coli were higher and more variable at Sims Park than at Villa Angela or Edgewater Park; concentrations were lowest at Edgewater Park. Time-series plots showed that short-term storage (less than one week) of E. coli in lake-bottom sediments may have occurred, although no evidence for long-term storage was found during the sampling period. E. coli concentrations in water were found to increase with increasing wave height, but the resuspension of E. coli from lake-bottom sediments by wave action could not be adequately assessed; higherwave heights were often associated with the discharge of sewage containing E. coli during or after a rainfall and wastewater-treatment plant overflow. Multiple linear regression (MLR) was used to develop models to predict recreational water quality at the in water. The related variables included turbidity, antecedent rainfall, antecedent weighted rainfall, volumes of wastewater-treatment plant overflows and metered outfalls (composed of storm-water runoff and combined-sewer overflows), a resuspension index, and wave heights. For the beaches in this study, wind speed, wind direction, water temperature, and the prswimmers

Predictors Of Non-Escherichia Coli Urinary Tract Infection.

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Shaikh, Nader; Wald, Ellen R; Keren, Ron; Gotman, Nathan; Ivanova, Anastasia; Carpenter, Myra A; Moxey-Mims, Marva; Hoberman, Alejandro

2016-11-01

We aimed to determine which children are prone to non-Escherichia coli urinary tract infection (UTIs). We included 769 children with UTI. We found that circumcised males, Hispanic children, children without fever and children with grades 3 and 4 vesicoureteral reflux were more likely to have a UTI caused by organisms other than E. coli. This information may guide clinicians in their choice of antimicrobial therapy.

[Current antibiotic resistance profile of uropathogenic Escherichia coli strains and therapeutic consequences].

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El Bouamri, M C; Arsalane, L; Kamouni, Y; Yahyaoui, H; Bennouar, N; Berraha, M; Zouhair, S

2014-12-01

Urinary tract infections (UTI) are a very common reason for consultation and prescription in current practice. Excessive or inappropriate use of antibiotics in treating urinary tract infections is responsible for the emergence and spread of multiresistant uropathogenic bacteria. To evaluate the isolation frequency and antibiotic resistance of uropathogenic Escherichia coli strains isolated at the Marrakech region. We conducted a retrospective study over a period of three years (from 1st January 2010 to 31 December 2012). It included all non-redundant uropathogenic E. coli strains isolated in the microbiology laboratory of the Avicenne hospital of Marrakech, Morocco. During this study, 1472 uropathogenic enterobacteriaceae were isolated including 924 non-repetitive E. coli strains, an overall isolation frequency of 63%. Antibiotic resistance of isolated E. coli strains showed resistance rates to amoxicillin (65%), sulfamethoxazole-triméthropime (55%), amoxicillin-clavulanic acid (43%), ciprofloxacin (22%), gentamicin (14%), nitrofurans (11%), amikacin (8%) and fosfomycin (7%). The number of E. coli strains resistant to C3G by ESBL production was 67, an average frequency of 4.5% of all isolated uropathogenic enterobacteria. The associated antibiotic resistance in the case of ESBL-producing E. coli were 82% for ciprofloxacin, 76% for sulfamethozole trimethoprim, 66% for gentamicin and 56% for amikacin. No resistance to imipenem was recorded for the isolated E. coli strains, which represents an imipenem sensitivity of 100%. Antibiotic resistance of uropathogenic E. coli strains limits treatment options and therefore constitutes a real public health problem. The regular updating of antibiotic susceptibility statistics of E. coli strains allows a better adaptation of the probabilistic antibiotic therapy to local epidemiological data. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Escherichia coli Sequence Type 131 H30 Is the Main Driver of Emerging Extended-Spectrum-β-Lactamase-Producing E. coli at a Tertiary Care Center.

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Johnson, James R; Johnston, Brian; Thuras, Paul; Launer, Bryn; Sokurenko, Evgeni V; Miller, Loren G

2016-01-01

The H 30 strain of Escherichia coli sequence type 131 (ST131- H 30) is a recently emerged, globally disseminated lineage associated with fluoroquinolone resistance and, via its H 30Rx subclone, the CTX-M-15 extended-spectrum beta-lactamase (ESBL). Here, we studied the clonal background and resistance characteristics of 109 consecutive recent E. coli clinical isolates (2015) and 41 historical ESBL-producing E. coli blood isolates (2004 to 2011) from a public tertiary care center in California with a rising prevalence of ESBL-producing E. coli isolates. Among the 2015 isolates, ST131, which was represented mainly by ST131- H 30, was the most common clonal lineage (23% overall). ST131- H 30 accounted for 47% (8/17) of ESBL-producing, 47% (14/30) of fluoroquinolone-resistant, and 33% (11/33) of multidrug-resistant isolates. ST131- H 30 also accounted for 53% (8/14) of dually fluoroquinolone-resistant, ESBL-producing isolates, with the remaining 47% comprised of diverse clonal groups that contributed a single isolate each. ST131- H 30Rx, with CTX-M-15, was the major ESBL producer (6/8) among ST131- H 30 isolates. ST131- H 30 and H 30Rx also dominated (46% and 37%, respectively) among the historical ESBL-producing isolates (2004 to 2011), without significant temporal shifts in relative prevalence. Thus, this medical center's recently emerging ESBL-producing E. coli strains, although multiclonal, are dominated by ST131- H 30 and H 30Rx, which are the only clonally expanded fluoroquinolone-resistant, ESBL-producing lineages. Measures to rapidly and effectively detect, treat, and control these highly successful lineages are needed. IMPORTANCE The ever-rising prevalence of resistance to first-line antibiotics among clinical Escherichia coli isolates leads to worse clinical outcomes and higher health care costs, thereby creating a need to discover its basis so that effective interventions can be developed. We found that the H 30 subset within E. coli sequence type 131

Changes in Escherichia coli resistance to co-trimoxazole in ...

African Journals Online (AJOL)

In Thyolo district, Malawi, an operational research study is being conducted on the efficacy and feasibility of co-trimoxazole prophylaxis in preventing deaths in HIV-positive patients with tuberculosis (TB). A series of cross-sectional studies were carried out to determine i) whether faecal Escherichia coli (E.coli) resistance to ...

Antibiotic Resistance of Escherichia coli Isolated from Healthy Food ...

African Journals Online (AJOL)

It was concluded from the study that healthy food animals form a reservoir of multiple resistant E. coli which may be transmitted to humans through the food chain. Thus, continued surveillance of E. coli obtained from food production continuum is merited to identify emerging antimicrobial-resistant phenotypes. The Kenya ...

Explaining and modeling the concentration and loading of Escherichia coli in a stream-A case study.

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Wang, Chaozi; Schneider, Rebecca L; Parlange, Jean-Yves; Dahlke, Helen E; Walter, M Todd

2018-09-01

Escherichia coli (E. coli) level in streams is a public health indicator. Therefore, being able to explain why E. coli levels are sometimes high and sometimes low is important. Using citizen science data from Fall Creek in central NY we found that complementarily using principal component analysis (PCA) and partial least squares (PLS) regression provided insights into the drivers of E. coli and a mechanism for predicting E. coli levels, respectively. We found that stormwater, temperature/season and shallow subsurface flow are the three dominant processes driving the fate and transport of E. coli. PLS regression modeling provided very good predictions under stormwater conditions (R 2  = 0.85 for log (E. coli concentration) and R 2  = 0.90 for log (E. coli loading)); predictions under baseflow conditions were less robust. But, in our case, both E. coli concentration and E. coli loading were significantly higher under stormwater condition, so it is probably more important to predict high-flow E. coli hazards than low-flow conditions. Besides previously reported good indicators of in-stream E. coli level, nitrate-/nitrite-nitrogen and soluble reactive phosphorus were also found to be good indicators of in-stream E. coli levels. These findings suggest management practices to reduce E. coli concentrations and loads in-streams and, eventually, reduce the risk of waterborne disease outbreak. Copyright © 2018. Published by Elsevier B.V.

The Impact of Media, Phylogenetic Classification, and E. coli Pathotypes on Biofilm Formation in Extraintestinal and Commensal E. coli From Humans and Animals.

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Nielsen, Daniel W; Klimavicz, James S; Cavender, Tia; Wannemuehler, Yvonne; Barbieri, Nicolle L; Nolan, Lisa K; Logue, Catherine M

2018-01-01

Extraintestinal pathogenic Escherichia coli (ExPEC) include avian pathogenic E. coli (APEC), neonatal meningitis E. coli (NMEC), and uropathogenic E. coli (UPEC) and are responsible for significant animal and human morbidity and mortality. This study sought to investigate if biofilm formation by ExPEC likely contributes to these losses since biofilms are associated with recurrent urinary tract infections, antibiotic resistance, and bacterial exchange of genetic material. Therefore, the goal of this study was to examine differences in biofilm formation among a collection of ExPEC and to ascertain if there is a relationship between their ability to produce biofilms and their assignment to phylogenetic groups in three media types - M63, diluted TSB, and BHI. Our results suggest that ExPEC produce relatively different levels of biofilm formation in the media tested as APEC (70.4%, p = 0.0064) and NMEC (84.4%, p = 0.0093) isolates were poor biofilm formers in minimal medium M63 while UPEC isolates produced significantly higher ODs under nutrient-limited conditions with 25% of strains producing strong biofilms in diluted TSB ( p = 0.0204). Additionally, E. coli phylogenetic assignment using Clermont's original and revised typing scheme demonstrated significant differences among the phylogenetic groups in the different media. When the original phylogenetic group isolates previously typed as group D were phylogenetically typed under the revised scheme and examined, they showed substantial variation in their ability to form biofilms, which may explain the significant values of revised phylogenetic groups E and F in M63 ( p = 0.0291, p = 0.0024). Our data indicates that biofilm formation is correlated with phylogenetic classification and subpathotype or commensal grouping of E. coli strains.

Development of a biosensor protein bullet as a fluorescent method for fast detection of Escherichia coli in drinking water.

Directory of Open Access Journals (Sweden)

Ignacio Gutiérrez-Del-Río

Full Text Available Drinking water can be exposed to different biological contaminants from the source, through the pipelines, until reaching the final consumer or industry. Some of these are pathogenic bacteria and viruses which may cause important gastrointestinal or systemic diseases. The microbiological quality of drinking water relies mainly in monitoring three indicator bacteria of faecal origin, Escherichia coli, Enterococcus faecalis and Clostridium perfringens, which serve as early sentinels of potential health hazards for the population. Here we describe the analysis of three chimeric fluorescent protein bullets as biosensor candidates for fast detection of E. coli in drinking water. Two of the chimeric proteins (based on GFP-hadrurin and GFP-pb5 chimera proteins failed with respect to specificity and/or sensitivity, but the GFP-colS4 chimera protein was able to carry out specific detection of E. coli in drinking water samples in a procedure encompassing about 8 min for final result and this biosensor protein was able to detect in a linear way between 20 and 103 CFU of this bacterium. Below 20 CFU, the system cannot differentiate presence or absence of the target bacterium. The fluorescence in this biosensor system is provided by the GFP subunit of the chimeric protein, which, in the case of the better performing sensor bullet, GFP-colS4 chimera, is covalently bound to a flexible peptide bridge and to a bacteriocin binding specifically to E. coli cells. Once bound to the target bacteria, the excitation step with 395 nm LED light causes emission of fluorescence from the GFP domain, which is amplified in a photomultiplier tube, and finally this signal is converted into an output voltage which can be associated with a CFU value and these data distributed along mobile phone networks, for example. This method, and the portable fluorimeter which has been developed for it, may contribute to reduce the analysis time for detecting E. coli presence in drinking

Development of a biosensor protein bullet as a fluorescent method for fast detection of Escherichia coli in drinking water.

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Gutiérrez-Del-Río, Ignacio; Marín, Laura; Fernández, Javier; Álvarez San Millán, María; Ferrero, Francisco Javier; Valledor, Marta; Campo, Juan Carlos; Cobián, Natalia; Méndez, Ignacio; Lombó, Felipe

2018-01-01

Drinking water can be exposed to different biological contaminants from the source, through the pipelines, until reaching the final consumer or industry. Some of these are pathogenic bacteria and viruses which may cause important gastrointestinal or systemic diseases. The microbiological quality of drinking water relies mainly in monitoring three indicator bacteria of faecal origin, Escherichia coli, Enterococcus faecalis and Clostridium perfringens, which serve as early sentinels of potential health hazards for the population. Here we describe the analysis of three chimeric fluorescent protein bullets as biosensor candidates for fast detection of E. coli in drinking water. Two of the chimeric proteins (based on GFP-hadrurin and GFP-pb5 chimera proteins) failed with respect to specificity and/or sensitivity, but the GFP-colS4 chimera protein was able to carry out specific detection of E. coli in drinking water samples in a procedure encompassing about 8 min for final result and this biosensor protein was able to detect in a linear way between 20 and 103 CFU of this bacterium. Below 20 CFU, the system cannot differentiate presence or absence of the target bacterium. The fluorescence in this biosensor system is provided by the GFP subunit of the chimeric protein, which, in the case of the better performing sensor bullet, GFP-colS4 chimera, is covalently bound to a flexible peptide bridge and to a bacteriocin binding specifically to E. coli cells. Once bound to the target bacteria, the excitation step with 395 nm LED light causes emission of fluorescence from the GFP domain, which is amplified in a photomultiplier tube, and finally this signal is converted into an output voltage which can be associated with a CFU value and these data distributed along mobile phone networks, for example. This method, and the portable fluorimeter which has been developed for it, may contribute to reduce the analysis time for detecting E. coli presence in drinking water.

The T cell STAT signaling network is reprogrammed within hours of bacteremia via secondary signals1

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Hotson, Andrew N.; Hardy, Jonathan W.; Hale, Matthew B.; Contag, Christopher H.; Nolan, Garry P.

2014-01-01

The delicate balance between protective immunity and inflammatory disease is challenged during sepsis, a pathologic state characterized by aspects of both a hyper-active immune response and immunosuppression. The events driven by systemic infection by bacterial pathogens on the T cell signaling network that likely control these responses have not been illustrated in great detail. We characterized how intracellular signaling within the immune compartment is reprogrammed at the single cell level when the host is challenged with a high levels of pathogen. To accomplish this, we applied flow cytometry to measure the phosphorylation potential of key signal transduction proteins during acute bacterial challenge. We modeled the onset of sepsis by intravenous administration of avirulent strains of Listeria and E. coli to mice. Within six hours of bacterial challenge, T cells were globally restricted in their ability to respond to specific cytokine stimulations as determined by assessing the extent of STAT protein phosphorylation. Mechanisms by which this negative feedback response occurred included SOCS1 and SOCS3 gene up regulation and IL-6 induced endocystosis of the IL-6 receptor. In addition, macrophages were partially tolerized in their ability to respond to TLR agonists. Thus, in contrast to the view that there is a wholesale immune activation during sepsis, one immediate host response to blood borne bacteria was induction of a refractory period during which leukocyte activation by specific stimulations was attenuated. PMID:19494279

The Detection Method of Escherichia coli in Water Resources: A Review

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Nurliyana, M. R.; Sahdan, M. Z.; Wibowo, K. M.; Muslihati, A.; Saim, H.; Ahmad, S. A.; Sari, Y.; Mansor, Z.

2018-04-01

This article reviews several approaches for Escherichia coli (E. coli) bacteria detection from conventional methods, emerging method and goes to biosensor-based techniques. Detection and enumeration of E. coli bacteria usually required long duration of time in obtaining the result since laboratory-based approach is normally used in its assessment. It requires 24 hours to 72 hours after sampling to process the culturing samples before results are available. Although faster technique for detecting E. coli in water such as Polymerase Chain Reaction (PCR) and Enzyme-Linked Immunosorbent Assay (ELISA) have been developed, it still required transporting the samples from water resources to the laboratory, high-cost, complicated equipment usage, complex procedures, as well as the requirement of skilled specialist to cope with the complexity which limit their wide spread practice in water quality detection. Recently, development of biosensor device that is easy to perform, portable, highly sensitive and selective becomes indispensable in detecting extremely lower consolidation of pathogenic E. coli bacteria in water samples.

A metabolic switch controls intestinal differentiation downstream of Adenomatous polyposis coli (APC).

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Sandoval, Imelda T; Delacruz, Richard Glenn C; Miller, Braden N; Hill, Shauna; Olson, Kristofor A; Gabriel, Ana E; Boyd, Kevin; Satterfield, Christeena; Remmen, Holly Van; Rutter, Jared; Jones, David A

2017-04-11

Elucidating signaling pathways that regulate cellular metabolism is essential for a better understanding of normal development and tumorigenesis. Recent studies have shown that mitochondrial pyruvate carrier 1 (MPC1) , a crucial player in pyruvate metabolism, is downregulated in colon adenocarcinomas. Utilizing zebrafish to examine the genetic relationship between MPC1 and Adenomatous polyposis coli (APC), a key tumor suppressor in colorectal cancer, we found that apc controls the levels of mpc1 and that knock down of mpc1 recapitulates phenotypes of impaired apc function including failed intestinal differentiation. Exogenous human MPC1 RNA rescued failed intestinal differentiation in zebrafish models of apc deficiency. Our data demonstrate a novel role for apc in pyruvate metabolism and that pyruvate metabolism dictates intestinal cell fate and differentiation decisions downstream of apc .

Hydrogen production by recombinant Escherichia coli strains

Science.gov (United States)

Maeda, Toshinari; Sanchez‐Torres, Viviana; Wood, Thomas K.

2012-01-01

Summary The production of hydrogen via microbial biotechnology is an active field of research. Given its ease of manipulation, the best‐studied bacterium Escherichia coli has become a workhorse for enhanced hydrogen production through metabolic engineering, heterologous gene expression, adaptive evolution, and protein engineering. Herein, the utility of E. coli strains to produce hydrogen, via native hydrogenases or heterologous ones, is reviewed. In addition, potential strategies for increasing hydrogen production are outlined and whole‐cell systems and cell‐free systems are compared. PMID:21895995

An evolutionary analysis of genome expansion and pathogenicity in Escherichia coli.

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Bohlin, Jon; Brynildsrud, Ola B; Sekse, Camilla; Snipen, Lars

2014-10-09

There are several studies describing loss of genes through reductive evolution in microbes, but how selective forces are associated with genome expansion due to horizontal gene transfer (HGT) has not received similar attention. The aim of this study was therefore to examine how selective pressures influence genome expansion in 53 fully sequenced and assembled Escherichia coli strains. We also explored potential connections between genome expansion and the attainment of virulence factors. This was performed using estimations of several genomic parameters such as AT content, genomic drift (measured using relative entropy), genome size and estimated HGT size, which were subsequently compared to analogous parameters computed from the core genome consisting of 1729 genes common to the 53 E. coli strains. Moreover, we analyzed how selective pressures (quantified using relative entropy and dN/dS), acting on the E. coli core genome, influenced lineage and phylogroup formation. Hierarchical clustering of dS and dN estimations from the E. coli core genome resulted in phylogenetic trees with topologies in agreement with known E. coli taxonomy and phylogroups. High values of dS, compared to dN, indicate that the E. coli core genome has been subjected to substantial purifying selection over time; significantly more than the non-core part of the genome (pcoli genome size correlated with estimated HGT size (pcoli are largely attained through HGT. No associations were found between selective pressures operating on the E. coli core genome, as estimated using relative entropy, and genome size (p~0.98). On a larger time frame, genome expansion in E. coli, which is significantly associated with the acquisition of virulence factors, appears to be independent of selective forces operating on the core genome.