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Sample records for modeling escherichia coli

  1. Escherichia coli growth under modeled reduced gravity

    Science.gov (United States)

    Baker, Paul W.; Meyer, Michelle L.; Leff, Laura G.

    2004-01-01

    Bacteria exhibit varying responses to modeled reduced gravity that can be simulated by clino-rotation. When Escherichia coli was subjected to different rotation speeds during clino-rotation, significant differences between modeled reduced gravity and normal gravity controls were observed only at higher speeds (30-50 rpm). There was no apparent affect of removing samples on the results obtained. When E. coli was grown in minimal medium (at 40 rpm), cell size was not affected by modeled reduced gravity and there were few differences in cell numbers. However, in higher nutrient conditions (i.e., dilute nutrient broth), total cell numbers were higher and cells were smaller under reduced gravity compared to normal gravity controls. Overall, the responses to modeled reduced gravity varied with nutrient conditions; larger surface to volume ratios may help compensate for the zone of nutrient depletion around the cells under modeled reduced gravity.

  2. 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…

  3. Modeling Surface Growth of Escherichia coli on Agar Plates

    OpenAIRE

    Fujikawa, Hiroshi; Morozumi, Satoshi

    2005-01-01

    Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34°C) were successfully described with the modified m...

  4. Modeling the pressure inactivation dynamics of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Yamamoto K.

    2005-01-01

    Full Text Available Escherichia coli, as a model microorganism, was treated in phosphate-buffered saline under high hydrostatic pressure between 100 and 300 MPa, and the inactivation dynamics was investigated from the viewpoint of predictive microbiology. Inactivation data were curve fitted by typical predictive models: logistic, Gompertz and Weibull functions. Weibull function described the inactivation curve the best. Two parameters of Weibull function were calculated for each holding pressure and their dependence on holding pressure was obtained by interpolation. With the interpolated parameters, inactivation curves were simulated and compared with the experimental data sets.

  5. Kinetic modelling of central carbon metabolism in Escherichia coli.

    Science.gov (United States)

    Peskov, Kirill; Mogilevskaya, Ekaterina; Demin, Oleg

    2012-09-01

    In the present study, we developed a detailed kinetic model of Escherichia coli central carbon metabolism. The main model assumptions were based on the results of metabolic and regulatory reconstruction of the system and thorough model verification with experimental data. The development and verification of the model included several stages, which allowed us to take into account both in vitro and in vivo experimental data and avoid the ambiguity that frequently occurs in detailed models of biochemical pathways. The choice of the level of detail for the mathematical description of enzymatic reaction rates and the evaluation of parameter values were based on available published data. Validation of the complete model of the metabolic pathway describing specific physiological states was based on fluxomics and metabolomics data. In particular, we developed a model that describes aerobic growth of E. coli in continuous culture with a limiting concentration of glucose. Such modification of the model was used to integrate experimental metabolomics data obtained in steady-state conditions for wild-type E. coli and genetically modified strains, e.g. knockout of the pyruvate kinase gene (pykA). Following analysis of the model behaviour, and comparison of the coincidence between predicted and experimental data, it was possible to investigate the functional and regulatory properties of E. coli central carbon metabolism. For example, a novel metabolic regulatory mechanism for 6-phosphogluconate dehydrogenase inhibition by phosphoenolpyruvate was hypothesized, and the flux ratios between the reactions catalysed by enzyme isoforms were predicted. The mathematical model described here has been submitted to the JWS Online Cellular Systems Modelling Database and can be accessed at http://jjj.biochem.sun.ac.za/database/peskov/index.html © 2012 The Authors Journal compilation © 2012 FEBS.

  6. A Murine Model for Escherichia coli Urinary Tract Infection.

    Science.gov (United States)

    Hannan, Thomas J; Hunstad, David A

    2016-01-01

    Urinary tract infections (UTI) are among the most common bacterial infections of humans. The mouse provides an excellent and tractable model system for cystitis and pyelonephritis caused by Escherichia coli and other uropathogens. Using a well-established model of experimental cystitis in which the bladders of female mice are infected via transurethral catheterization, the molecular details of the pathogenesis of bacterial cystitis have been substantially illuminated in the last decade. Uropathogenic E. coli attach to bladder epithelium (both in human and mouse) via adhesive type 1 pili, establish a replicative niche within epithelial cell cytoplasm, and form intracellular bacterial communities that are protected from antibiotic effects and immune clearance. The use of different inbred and mutant mouse strains offers the opportunity to study outcomes of infection, including resolution, formation of quiescent intracellular bacterial reservoirs, chronic bacterial cystitis, and recurrent infections. Urine, bladder, and kidney tissues can be analyzed by bacterial culture, histology, immunohistochemistry, immunofluorescent and confocal microscopy, electron microscopy, and flow cytometry, while a broad array of soluble markers (e.g., cytokines) can also be profiled in serum, urine, and tissue homogenates by ELISA, Western blotting, multiplex bead array, and other approaches. This model promises to afford continued opportunity for discovery of pathogenic mechanisms and evaluation of therapeutic and preventive strategies for acute, chronic, and recurrent UTI.

  7. Ensemble modeling for aromatic production in Escherichia coli.

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    Matthew L Rizk

    Full Text Available Ensemble Modeling (EM is a recently developed method for metabolic modeling, particularly for utilizing the effect of enzyme tuning data on the production of a specific compound to refine the model. This approach is used here to investigate the production of aromatic products in Escherichia coli. Instead of using dynamic metabolite data to fit a model, the EM approach uses phenotypic data (effects of enzyme overexpression or knockouts on the steady state production rate to screen possible models. These data are routinely generated during strain design. An ensemble of models is constructed that all reach the same steady state and are based on the same mechanistic framework at the elementary reaction level. The behavior of the models spans the kinetics allowable by thermodynamics. Then by using existing data from the literature for the overexpression of genes coding for transketolase (Tkt, transaldolase (Tal, and phosphoenolpyruvate synthase (Pps to screen the ensemble, we arrive at a set of models that properly describes the known enzyme overexpression phenotypes. This subset of models becomes more predictive as additional data are used to refine the models. The final ensemble of models demonstrates the characteristic of the cell that Tkt is the first rate controlling step, and correctly predicts that only after Tkt is overexpressed does an increase in Pps increase the production rate of aromatics. This work demonstrates that EM is able to capture the result of enzyme overexpression on aromatic producing bacteria by successfully utilizing routinely generated enzyme tuning data to guide model learning.

  8. Modeling surface growth of Escherichia coli on agar plates.

    Science.gov (United States)

    Fujikawa, Hiroshi; Morozumi, Satoshi

    2005-12-01

    Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34 degrees C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves.

  9. Escherichia coli Uropathogenesis In Vitro

    DEFF Research Database (Denmark)

    Andersen, Thomas E; Khandige, Surabhi; Madelung, Michelle

    2012-01-01

    Uropathogenic Escherichia coli (UPEC) strains are capable of invading bladder epithelial cells (BECs) on the bladder luminal surface. Based primarily on studies in mouse models, invasion is proposed to trigger an intracellular uropathogenic cascade involving intracellular bacterial proliferation...

  10. Taxonomy Icon Data: Escherichia coli [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available Escherichia coli Escherichia coli Escherichia_coli_L.png Escherichia_coli_NL.png Escherich...ia_coli_S.png Escherichia_coli_NS.png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Escherichia+co...li&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Escherichia+coli&t=NL http://biosciencedbc.jp/taxono...my_icon/icon.cgi?i=Escherichia+coli&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Escherichia+coli&t=NS ...

  11. PATHOGENIC ESCHERICHIA COLI

    Science.gov (United States)

    Escherichia coli is a bacterial species which inhabits the gastrointestinal tract of man and warm-blooded animals. Because of the ubiquity of this bacterium in the intestinal flora, it serves as an important indicator organism of fecal contamination. E. coli, aside from serving a...

  12. Diarrheagenic Escherichia coli.

    Science.gov (United States)

    Gomes, Tânia A T; Elias, Waldir P; Scaletsky, Isabel C A; Guth, Beatriz E C; Rodrigues, Juliana F; Piazza, Roxane M F; Ferreira, Luís C S; Martinez, Marina B

    2016-12-01

    Most Escherichia coli strains live harmlessly in the intestines and rarely cause disease in healthy individuals. Nonetheless, a number of pathogenic strains can cause diarrhea or extraintestinal diseases both in healthy and immunocompromised individuals. Diarrheal illnesses are a severe public health problem and a major cause of morbidity and mortality in infants and young children, especially in developing countries. E. coli strains that cause diarrhea have evolved by acquiring, through horizontal gene transfer, a particular set of characteristics that have successfully persisted in the host. According to the group of virulence determinants acquired, specific combinations were formed determining the currently known E. coli pathotypes, which are collectively known as diarrheagenic E. coli. In this review, we have gathered information on current definitions, serotypes, lineages, virulence mechanisms, epidemiology, and diagnosis of the major diarrheagenic E. coli pathotypes.

  13. Metabolic Modeling of Common Escherichia coli Strains in Human Gut Microbiome

    Directory of Open Access Journals (Sweden)

    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.

  14. Stationary-State Mutagenesis in Escherichia coli: a Model

    Indian Academy of Sciences (India)

    S. K. Mahajan; A. V. S. S. Narayana Rao; S. K. Bhattacharjee

    2000-04-01

    Stationary-phase mutagenesis in nondividing E. coli cells exposed to a nonlethal stress was, a few years ago, claimed to be a likely case of a Lamarckian mechanism capable of producing exclusively useful mutations in a directed manner. After a heated debate over the last decade it now appears to involve a Darwinian mechanism that generates a transient state of hypermutagenesis, operating on a large number of sites spread over the entire genome, at least in a proportion of the resting cells. Most of the studies that clarified this position were on the reversion of a frameshift mutation present in a lacI -- lacZ fusion in E. coli strain FC40. Several groups have extensively examined both the sequence changes associated with these reversions and the underlying genetic requirements. On the basis of our studies on the genomic sequence analysis, we recently proposed a model to explain the specific changes associated with the reversion hotspots. Here we propose a more detailed version of this model that also takes into account the observed genetic requirements of stationary-state mutagenesis. Briefly, G:T/U mismatches produced at methylatable cytosines are preferentially repaired in nondividing cells by the very short patch mismatch repair (VSPMR) mechanism which is itself mutagenic and can produce mutations in very short stretches located in the immediate vicinity of these cytosine methylation sites. This mechanism requires a homologous or homeologous strand invasion step and an error-prone DNA synthesis step and is dependent on RecA, RecBCD and a DNA polymerase. The process is initiated near sequences recognized by Dcm and Vsr enzymes and further stimulated if these sequences are a part of CHI or CHI-like sequences, but a double-strand-break-dependent recombination mediated by the RecBCD pathways proposed by others seems to be nonessential. The strand transfer step is proposed to depend on RecA, RuvA, RuvB and RuvC and is opposed by RecG and MutS. The model also gives

  15. Zoonotic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Wasteson Yngvild

    2002-03-01

    Full Text Available Escherichia coli is a normal inhabitant of the gastrointestinal tract of all warm-blooded animals, but variants of this species is also among the important etiological agents of enteritis and several extraintestinal diseases. The E. coli strains that cause diarrhoeal illness are categorised into pathogenicity groups based on virulence properties, mechanisms of pathogenicity, clinical symptoms and serology. The five main categories include enterotoxinogenic E. coli (ETEC, enteropathogenic E. coli (EPEC, enteroaggregative E. coli (EAggEC, enteroinvasive E. coli (EIEC and Shiga (Vero toxin-producing E. coli (STEC/VTEC. From a zoonotic point of view, STEC is the only E. coli pathogenicity group of major interest, as the shiga toxin-producing strains are able to cause severe disease in humans when being transmitted through the food chain from their animal reservoirs. The focus of this manuscript is therefore on STEC; pathogenicity factors, disease, the reservoirs and on-farm ecology, transmission into the food chain, growth and survival in food and in the environment, and the shiga toxin-encoding bacteriophages.

  16. Laboratory strains of Escherichia coli: model citizens or deceitful delinquents growing old disgracefully?

    Science.gov (United States)

    Hobman, Jon L; Penn, Charles W; Pallen, Mark J

    2007-05-01

    Escherichia coli stands unchallenged as biology's premier model organism. However, we propose, equipped with insights from the post-genomic era, a contrary view: that microbiology's chief idol has feet of clay. E. coli laboratory strains, particularly E. coli K-12, are far from model citizens, but instead degenerate and deceitful delinquents growing old disgracefully in our scientific institutions. E. coli K-12 is neither archetype nor ancestor. In addition, it has a far from optimal provenance for a model organism, with strong grounds for believing that current versions of the strain are quite distinct from any original wild-type free-living ancestor. In addition, it is usually studied under conditions far removed from its natural habitats and in ignorance of the selective pressures that have shaped its evolution. Fortunately, a flood of information from high-throughput genome sequencing, together with a new 'eco-evo' view of this model organism, promises to help put K-12 better into context.

  17. Complete Structural Model of Escherichia coli RNA Polymerase from a Hybrid Approach

    Energy Technology Data Exchange (ETDEWEB)

    Opalka, N.; Brown, J; Lane, W; Twist, K; Landick, R; Asturias, F; Darst, S

    2010-01-01

    The Escherichia coli transcription system is the best characterized from a biochemical and genetic point of view and has served as a model system. Nevertheless, a molecular understanding of the details of E. coli transcription and its regulation, and therefore its full exploitation as a model system, has been hampered by the absence of high-resolution structural information on E. coli RNA polymerase (RNAP). We use a combination of approaches, including high-resolution X-ray crystallography, ab initio structural prediction, homology modeling, and single-particle cryo-electron microscopy, to generate complete atomic models of E. coli core RNAP and an E. coli RNAP ternary elongation complex. The detailed and comprehensive structural descriptions can be used to help interpret previous biochemical and genetic data in a new light and provide a structural framework for designing experiments to understand the function of the E. coli lineage-specific insertions and their role in the E. coli transcription program. Transcription, or the synthesis of RNA from DNA, is one of the most important processes in the cell. The central enzyme of transcription is the DNA-dependent RNA polymerase (RNAP), a large, macromolecular assembly consisting of at least five subunits. Historically, much of our fundamental information on the process of transcription has come from genetic and biochemical studies of RNAP from the model bacterium Escherichia coli. More recently, major breakthroughs in our understanding of the mechanism of action of RNAP have come from high resolution crystal structures of various bacterial, archaebacterial, and eukaryotic enzymes. However, all of our high-resolution bacterial RNAP structures are of enzymes from the thermophiles Thermus aquaticus or T. thermophilus, organisms with poorly characterized transcription systems. It has thus far proven impossible to obtain a high-resolution structure of E. coli RNAP, which has made it difficult to relate the large collection

  18. Complete structural model of Escherichia coli RNA polymerase from a hybrid approach.

    Directory of Open Access Journals (Sweden)

    Natacha Opalka

    Full Text Available The Escherichia coli transcription system is the best characterized from a biochemical and genetic point of view and has served as a model system. Nevertheless, a molecular understanding of the details of E. coli transcription and its regulation, and therefore its full exploitation as a model system, has been hampered by the absence of high-resolution structural information on E. coli RNA polymerase (RNAP. We use a combination of approaches, including high-resolution X-ray crystallography, ab initio structural prediction, homology modeling, and single-particle cryo-electron microscopy, to generate complete atomic models of E. coli core RNAP and an E. coli RNAP ternary elongation complex. The detailed and comprehensive structural descriptions can be used to help interpret previous biochemical and genetic data in a new light and provide a structural framework for designing experiments to understand the function of the E. coli lineage-specific insertions and their role in the E. coli transcription program.

  19. Host Response to Porcine Strains of Escherichia coli in a Novel Pyelonephritis Model

    DEFF Research Database (Denmark)

    Isling, L. K.; Aalbæk, B.; Birck, M. M.

    2011-01-01

    The initial pathology and pathogenesis of pyelonephritis and the influence of different strains of Escherichia coli were investigated in a novel porcine model. Nine female pigs were divided into three groups (A, B and C) and inoculated repeatedly into one renal pelvis with porcine pyelonephritis E...... kidneys. Gross and microscopical lesions of acute pyelonephritis were demonstrated in all but one kidney inoculated with E. coli, but in none of the control kidneys. Renal parenchymal infiltration with both neutrophils and mononuclear cells, primarily CD3+ T lymphocytes, was observed at 6hpi. Most T...

  20. Modeling the release of Escherichia coli from soil into overland flow under raindrop impact

    Science.gov (United States)

    Wang, C.; Parlange, J.-Y.; Rasmussen, E. W.; Wang, X.; Chen, M.; Dahlke, H. E.; Walter, M. T.

    2017-08-01

    Pathogen transport through the environment is complicated, involving a variety of physical, chemical, and biological processes. This study considered the transfer of microorganisms from soil into overland flow under rain-splash conditions. Although microorganisms are colloidal particles, they are commonly quantified as colony-forming units (CFUs) per volume rather than as a mass or number of particles per volume, which poses a modeling challenge. However, for very small particles that essentially remain suspended after being ejected into ponded water and for which diffusion can be neglected, the Gao model, originally derived for solute transfer from soil, describes particle transfer into suspension and is identical to the Hairsine-Rose particle erosion model for this special application. Small-scale rainfall experiments were conducted in which an Escherichia coli (E. coli) suspension was mixed with a simple soil (9:1 sand-to-clay mass ratio). The model fit the experimental E. coli data. Although re-conceptualizing the Gao solute model as a particle suspension model was convenient for accommodating the unfortunate units of CFU ml-1, the Hairsine-Rose model is insensitive to assumptions about E. coli per CFU as long as the assumed initial mass concentration of E. coli is very small compared to that of the soil particle classes. Although they undoubtedly actively interact with their environment, this study shows that transport of microorganisms from soil into overland storm flows can be reasonably modeled using the same principles that have been applied to small mineral particles in previous studies.

  1. Pressure and temperature dependence of growth and morphology of Escherichia coli: experiments and stochastic model.

    Science.gov (United States)

    Kumar, Pradeep; Libchaber, Albert

    2013-08-06

    We have investigated the growth of Escherichia coli, a mesophilic bacterium, as a function of pressure (P) and temperature (T). Escherichia coli can grow and divide in a wide range of pressure (1-400 atm) and temperature (23-40°C). For T > 30°C, the doubling time of E. coli increases exponentially with pressure and exhibits a departure from exponential behavior at pressures between 250 and 400 atm for all the temperatures studied in our experiments. The sharp change in doubling time is followed by a sharp change in phenotypic transition of E. coli at high pressures where bacterial cells switch to an elongating cell type. We propose a model that this phenotypic change in bacteria at high pressures is an irreversible stochastic process, whereas the switching probability to elongating cell type increases with increasing pressure. The model fits well the experimental data. We discuss our experimental results in the light of structural and thus functional changes in proteins and membranes.

  2. Modelling of Escherichia coli Cultivations: Acetate Inhibition in a Fed-batch Culture

    Directory of Open Access Journals (Sweden)

    Stoyan Tzonkov

    2006-04-01

    Full Text Available A set of three competing, unstructured models has been proposed to model biomass growth, glucose utilization, acetate formation, dissolved oxygen consumption and carbon dioxide accumulation of a fed-batch cultivation process of Escherichia coli. The inhibiting effect of acetate on growth of E. coli cultures is included in the considered models. The model identification is carried out using experimental data from the cultivation process. Genetic algorithms are used for parameter estimation. The model discrimination is based on the four criteria, namely sum of square errors, Fisher criterion, Akaike information criterion and minimum description length criterion. The most suitable model is identified that reflects the state variables curves adequately by considering acetate inhibited growth according to the Jerusalimsky approach.

  3. Modeling to Predict Escherichia coli at Presque Isle Beach 2, City of Erie, Erie County, Pennsylvania

    Science.gov (United States)

    Zimmerman, Tammy M.

    2008-01-01

    The Lake Erie beaches in Pennsylvania are a valuable recreational resource for Erie County. Concentrations of Escherichia coli (E. coli) at monitored beaches in Presque Isle State Park in Erie, Pa., occasionally exceed the single-sample bathing-water standard of 235 colonies per 100 milliliters resulting in potentially unsafe swimming conditions and prompting beach managers to post public advisories or to close beaches to recreation. To supplement the current method for assessing recreational water quality (E. coli concentrations from the previous day), a predictive regression model for E. coli concentrations at Presque Isle Beach 2 was developed from data collected during the 2004 and 2005 recreational seasons. Model output included predicted E. coli concentrations and exceedance probabilities--the probability that E. coli concentrations would exceed the standard. For this study, E. coli concentrations and other water-quality and environmental data were collected during the 2006 recreational season at Presque Isle Beach 2. The data from 2006, an independent year, were used to test (validate) the 2004-2005 predictive regression model and compare the model performance to the current method. Using 2006 data, the 2004-2005 model yielded more correct responses and better predicted exceedances of the standard than the use of E. coli concentrations from the previous day. The differences were not pronounced, however, and more data are needed. For example, the model correctly predicted exceedances of the standard 11 percent of the time (1 out of 9 exceedances that occurred in 2006) whereas using the E. coli concentrations from the previous day did not result in any correctly predicted exceedances. After validation, new models were developed by adding the 2006 data to the 2004-2005 dataset and by analyzing the data in 2- and 3-year combinations. Results showed that excluding the 2004 data (using 2005 and 2006 data only) yielded the best model. Explanatory variables in the

  4. 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.

  5. Antibiotic selection of Escherichia coli sequence type 131 in a mouse intestinal colonization model.

    Science.gov (United States)

    Boetius Hertz, Frederik; Løbner-Olesen, Anders; Frimodt-Møller, Niels

    2014-10-01

    The ability of different antibiotics to select for extended-spectrum β-lactamase (ESBL)-producing Escherichia coli remains a topic of discussion. In a mouse intestinal colonization model, we evaluated the selective abilities of nine common antimicrobials (cefotaxime, cefuroxime, dicloxacillin, clindamycin, penicillin, ampicillin, meropenem, ciprofloxacin, and amdinocillin) against a CTX-M-15-producing E. coli sequence type 131 (ST131) isolate with a fluoroquinolone resistance phenotype. Mice (8 per group) were orogastrically administered 0.25 ml saline with 10(8) CFU/ml E. coli ST131. On that same day, antibiotic treatment was initiated and given subcutaneously once a day for three consecutive days. CFU of E. coli ST131, Bacteroides, and Gram-positive aerobic bacteria in fecal samples were studied, with intervals, until day 8. Bacteroides was used as an indicator organism for impact on the Gram-negative anaerobic population. For three antibiotics, prolonged colonization was investigated with additional fecal CFU counts determined on days 10 and 14 (cefotaxime, dicloxacillin, and clindamycin). Three antibiotics (cefotaxime, dicloxacillin, and clindamycin) promoted overgrowth of E. coli ST131 (P organisms. Only clindamycin treatment resulted in prolonged colonization. The remaining six antibiotics, including ciprofloxacin, did not promote overgrowth of E. coli ST131 (P > 0.95), nor did they suppress Bacteroides or Gram-positive organisms. The results showed that antimicrobials both with and without an impact on Gram-negative anaerobes can select for ESBL-producing E. coli, indicating that not only Gram-negative anaerobes have a role in upholding colonization resistance. Other, so-far-unknown bacterial populations must be of importance for preventing colonization by incoming E. coli.

  6. Predicting the minimal inhibitory concentration of fluoroquinolones for Escherichia coli using an accumulation model.

    Science.gov (United States)

    Zhang, Wen; Wang, Chenyin; Tam, Kin Y

    2014-01-01

    The objective of this study is to evaluate whether the accumulation model developed by Zarfl et al. (2008) could be used to predict the minimal inhibitory concentration (MIC) of a group of antibacterial fluoroquinolones (FQs) for Escherichia coli (E. coli). Our model, which is based on the "Fick-Nernst-Planck" equation and the permeability of the neutral and charged species as well as the physicochemical parameters of the FQs, could predict 1/MIC90 using a linear function. It is envisaged that in the drug development projects of new FQs, the accumulation model described in this study could be utilized as an effective tool to enable early assessment of MIC value using physiochemical parameters.

  7. Pressure and temperature dependence of growth and morphology of Escherichia coli: Experiments and Stochastic Model

    CERN Document Server

    Kumar, Pradeep

    2012-01-01

    We have investigated the growth of Escherichia coli E.coli, a mesophilic bacterium, as a function of pressure $P$ and temperature $T$. E.coli can grow and divide in a wide range of pressure (1-400atm) and temperature ($23-40^{\\circ}$C). For $T>30^{\\circ}$ C, the division time of E.coli increases exponentially with pressure and exhibit a departure from exponential behavior at pressures between 250-400 atm for all the temperatures studied in our experiments. For $T<30^{\\circ}$ C, the division time shows an anomalous dependence on pressure -- first decreases with increasing pressure and then increases upon further increase of pressure. The sharp change in division time is followed by a sharp change in phenotypic transition of E. Coli at high pressures where bacterial cells switch to an elongating cell type. We propose a model that this phenotypic changes in bacteria at high pressures is an irreversible stochastic process whereas the switching probability to elongating cell type increases with increasing press...

  8. Antimicrobial mechanism of flavonoids against Escherichia coli ATCC 25922 by model membrane study

    Energy Technology Data Exchange (ETDEWEB)

    He, Mengying; Wu, Ting; Pan, Siyi; Xu, Xiaoyun, E-mail: xiaoyunxu88@gmail.com

    2014-06-01

    Antimicrobial mechanism of four flavonoids (kaempferol, hesperitin, (+)-catechin hydrate, biochanin A) against Escherichia coli ATCC 25922 was investigated through cell membranes and a liposome model. The release of bacterial protein and images from transmission electron microscopy demonstrated damage to the E. coli ATCC 25922 membrane. A liposome model with dipalmitoylphosphatidylethanolamine (DPPE) (0.6 molar ratio) and dipalmitoylphosphatidylglycerol (DPPG) (0.4 molar ratio), representative of the phospholipid membrane of E. coli ATCC 25922, was used to specify the mode of action of four selected flavonoids through Raman spectroscopy and differential scanning calorimetry. It is suggested that for flavonoids, to be effective antimicrobials, interaction with the polar head-group of the model membrane followed by penetration into the hydrophobic regions must occur. The antimicrobial efficacies of the flavonoids were consistent with liposome interaction activities, kaempferol > hesperitin > (+)-catechin hydrate > biochanin A. This study provides a liposome model capable of mimicking the cell membrane of E. coli ATCC 25922. The findings are important in understanding the antibacterial mechanism on cell membranes.

  9. A population-level model from the microscopic dynamics in Escherichia coli chemotaxis via Langevin approximation

    Institute of Scientific and Technical Information of China (English)

    He Zhuo-Ran; Wu Tai-Lin; Ouyang Qi; Tu Yu-Hai

    2012-01-01

    Recent extensive studies of Escherichia coli (E.coli) chemotaxis have achieved a deep understanding of its microscopic control dynamics.As a result,various quantitatively predictive models have been developed to describe the chemotactic behavior of E.coli motion.However,a population-level partial differential equation (PDE) that rationally incorporates such microscopic dynamics is still insufficient.Apart from the traditional Keller-Segel (K-S) equation,many existing population-level models developed from the microscopic dynamics are integro-PDEs.The difficulty comes mainly from cell tumbles which yield a velocity jumping process.Here,we propose a Langevin approximation method that avoids such a difficulty without appreciable loss of precision.The resulting model not only quantitatively reproduces the results of pathway-based single-cell simulators,but also provides new inside information on the mechanism of E.coli chemotaxis.Our study demonstrates a possible alternative in establishing a simple population-level model that allows for the complex microscopic mechanisms in bacterial chemotaxis.

  10. Escherichia coli--a model system that benefits from and contributes to the evolution of proteomics.

    Science.gov (United States)

    Lee, Pat S; Lee, Kelvin H

    2003-12-30

    The large body of knowledge about Escherichia coli makes it a useful model organism for the expression of heterologous proteins. Proteomic studies have helped to elucidate the complex cellular responses of E. coli and facilitated its use in a variety of biotechnology applications. Knowledge of basic cellular processes provides the means for better control of heterologous protein expression. Beyond such important applications, E. coli is an ideal organism for testing new analytical technologies because of the extensive knowledge base available about the organism. For example, improved technology for characterization of unknown proteins using mass spectrometry has made two-dimensional electrophoresis (2DE) studies more useful and more rewarding, and much of the initial testing of novel protocols is based on well-studied samples derived from E. coli. These techniques have facilitated the construction of more accurate 2DE maps. In this review, we present work that led to the 2DE databases, including a new map based on tandem time-of-flight (TOF) mass spectrometry (MS); describe cellular responses relevant to biotechnology applications; and discuss some emerging proteomic techniques.

  11. Pharmacokinetic and pharmacodynamic integration and modeling of enrofloxacin in swine for Escherichia coli

    Directory of Open Access Journals (Sweden)

    Jianyi eWang

    2016-02-01

    Full Text Available The aim of this study was tooptimize the dose regimens of enrofloxacin to reduce the development of fluoroquinolone resistance in Escherichia coli (E.coli using pharmacokinetic/pharmacodynamic (PK/PD modeling approach. The single dose (2.5 mg/kg body weight of enrofloxacin was administered intramuscularly (IM to the healthy pigs. Using cannulation, the pharmacokinetic properties, including peak concentration (Cmax, time to reach Cmax (Tmax and area under the curve (AUC, were determined in plasma and ileum content. The Cmax, Tmax, and AUC in the plasma were 1.09 ± 0.11 μg/mL, 1.27 ± 0.35 h and 12.70 ± 2.72 µg•h/mL, respectively. While in ileum content, the Cmax, Tmax and AUC were 7.07 ± 0.26 μg/mL, 5.54 ± 0.42 h and 136.18 ± 12.50 µg•h/mL, respectively. Based on the minimum inhibitory concentration (MIC data of 918 E.coli isolates, an E.coli O101/K99 strain (enrofloxacin MIC = 0.25 μg/mL was selected for pharmacodynamic studies. The in vitro minimum bactericidal concentration (MBC, mutant prevention concentration (MPC and ex vivo time-killing curves for enrofloxacin in ileum content were established against the selected E.coli O101/K99 strain. Integrating the in vivo pharmacokinetic data and ex vivo pharmacodynamic data, a sigmoid Emax (Hill equation was established to provide values for ileum content of AUC24h/MIC producing, bactericidal activity (52.65 h and virtual eradication of bacteria (78.06 h. A dosage regimen of 1.96 mg/kg every 12 h for 3 days should be sufficient in the treatment of E.coli.

  12. Pharmacokinetic and Pharmacodynamic Integration and Modeling of Enrofloxacin in Swine for Escherichia coli.

    Science.gov (United States)

    Wang, Jianyi; Hao, Haihong; Huang, Lingli; Liu, Zhenli; Chen, Dongmei; Yuan, Zonghui

    2016-01-01

    The aim of this study was to optimize the dose regimens of enrofloxacin to reduce the development of fluoroquinolone resistance in Escherichia coli (E.coli) using pharmacokinetic/pharmacodynamic (PK/PD) modeling approach. The single dose (2.5 mg/kg body weight) of enrofloxacin was administered intramuscularly (IM) to the healthy pigs. Using cannulation, the pharmacokinetic properties, including peak concentration (C max), time to reach C max (T max), and area under the curve (AUC), were determined in plasma and ileum content. The C max, T max, and AUC in the plasma were 1.09 ± 0.11 μg/mL, 1.27 ± 0.35 h, and 12.70 ± 2.72 μg·h/mL, respectively. While in ileum content, the C max, T max, and AUC were 7.07 ± 0.26 μg/mL, 5.54 ± 0.42 h, and 136.18 ± 12.50 μg·h/mL, respectively. Based on the minimum inhibitory concentration (MIC) data of 918 E. coli isolates, an E. coli O101/K99 strain (enrofloxacin MIC = 0.25 μg/mL) was selected for pharmacodynamic studies. The in vitro minimum bactericidal concentration (MBC), mutant prevention concentration (MPC), and ex vivo time-killing curves for enrofloxacin in ileum content were established against the selected E. coli O101/K99 strain. Integrating the in vivo pharmacokinetic data and ex vivo pharmacodynamic data, a sigmoid E max (Hill) equation was established to provide values for ileum content of AUC24h/MIC producing, bactericidal activity (52.65 h), and virtual eradication of bacteria (78.06 h). A dosage regimen of 1.96 mg/kg every 12 h for 3 days should be sufficient in the treatment of E. coli.

  13. Model of Transcriptional Activation By MarA in Escherichia Coli

    Science.gov (United States)

    Wall, Michael E.; Markowitz, David A.; Rosner, Judah L.; Martin, Robert G.

    2010-01-01

    We have developed a mathematical model of transcriptional activation by MarA in Escherichia coli, and used the model to analyze measurements of MarA-dependent activity of the marRAB, sodA, and micF promoters in mar-rob- cells. The model rationalizes an unexpected poor correlation between the mid-point of in vivo promoter activity profiles and in vitro equilibrium constants for MarA binding to promoter sequences. Analysis of the promoter activity data using the model yielded the following predictions regarding activation mechanisms: (1) MarA activation of the marRAB, sodA, and micF promoters involves a net acceleration of the kinetics of transitions after RNA polymerase binding, up to and including promoter escape and message elongation; (2) RNA polymerase binds to these promoters with nearly unit occupancy in the absence of MarA, making recruitment of polymerase an insignificant factor in activation of these promoters; and (3) instead of recruitment, activation of the micF promoter might involve a repulsion of polymerase combined with a large acceleration of the kinetics of polymerase activity. These predictions are consistent with published chromatin immunoprecipitation assays of interactions between polymerase and the E. coli chromosome. A lack of recruitment in transcriptional activation represents an exception to the textbook description of activation of bacterial sigma-70 promoters. However, use of accelerated polymerase kinetics instead of recruitment might confer a competitive advantage to E. coli by decreasing latency in gene regulation.

  14. 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...

  15. 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...

  16. Agent-based modeling of oxygen-responsive transcription factors in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Hao Bai

    2014-04-01

    Full Text Available In the presence of oxygen (O2 the model bacterium Escherichia coli is able to conserve energy by aerobic respiration. Two major terminal oxidases are involved in this process - Cyo has a relatively low affinity for O2 but is able to pump protons and hence is energetically efficient; Cyd has a high affinity for O2 but does not pump protons. When E. coli encounters environments with different O2 availabilities, the expression of the genes encoding the alternative terminal oxidases, the cydAB and cyoABCDE operons, are regulated by two O2-responsive transcription factors, ArcA (an indirect O2 sensor and FNR (a direct O2 sensor. It has been suggested that O2-consumption by the terminal oxidases located at the cytoplasmic membrane significantly affects the activities of ArcA and FNR in the bacterial nucleoid. In this study, an agent-based modeling approach has been taken to spatially simulate the uptake and consumption of O2 by E. coli and the consequent modulation of ArcA and FNR activities based on experimental data obtained from highly controlled chemostat cultures. The molecules of O2, transcription factors and terminal oxidases are treated as individual agents and their behaviors and interactions are imitated in a simulated 3-D E. coli cell. The model implies that there are two barriers that dampen the response of FNR to O2, i.e. consumption of O2 at the membrane by the terminal oxidases and reaction of O2 with cytoplasmic FNR. Analysis of FNR variants suggested that the monomer-dimer transition is the key step in FNR-mediated repression of gene expression.

  17. Particle-based model of Min-protein oscillations in Escherichia coli

    Science.gov (United States)

    Berman, Adam; Huang, Kerwyn; Wingreen, Ned

    2007-03-01

    In Escherichia coli cells, the Min proteins, which are required for division site selection, oscillate from pole to pole via a Turing instability. During these oscillations, two of the Min proteins, MinD and MinE self-associate and co- associate on the bacterial inner membrane forming dynamic structures including a ring of MinE protein, compact polar zones of MinD, and zebra stripes in filamentous cells. Such rich behavior in a system with so few species has made the Min proteins a model system for applying computational methods to study intracellular dynamics in bacteria. Though mean-field computational models successfully reproduce the coarse-grained oscillatory dynamics in both rod-shaped and round E. coli cells and also predict that the Min-proteins actively detect cell shape, the mean-field models cannot address questions raised by the recent finding that MinD forms a small number of large polymers on the membrane. First, it is unclear how the intrinsic dynamics of polymer formation, namely polymer nucleation and growth, affect the pole-to-pole oscillations. Second, it is not understood how the oscillations influence the morphology of the MinD polymers. To study this coupling between MinD polymerization and pole-to-pole oscillation, we employ a particle-based computational model. In this talk, we will describe this model, which produces both large polymers and pole-to-pole oscillations.

  18. Robust growth of Escherichia coli.

    Science.gov (United States)

    Wang, Ping; Robert, Lydia; Pelletier, James; Dang, Wei Lien; Taddei, Francois; Wright, Andrew; Jun, Suckjoon

    2010-06-22

    The quantitative study of the cell growth has led to many fundamental insights in our understanding of a wide range of subjects, from the cell cycle to senescence. Of particular importance is the growth rate, whose constancy represents a physiological steady state of an organism. Recent studies, however, suggest that the rate of elongation during exponential growth of bacterial cells decreases cumulatively with replicative age for both asymmetrically and symmetrically dividing organisms, implying that a "steady-state" population consists of individual cells that are never in a steady state of growth. To resolve this seeming paradoxical observation, we studied the long-term growth and division patterns of Escherichia coli cells by employing a microfluidic device designed to follow steady-state growth and division of a large number of cells at a defined reproductive age. Our analysis of approximately 10(5) individual cells reveals a remarkable stability of growth whereby the mother cell inherits the same pole for hundreds of generations. We further show that death of E. coli is not purely stochastic but is the result of accumulating damages. We conclude that E. coli, unlike all other aging model systems studied to date, has a robust mechanism of growth that is decoupled from cell death.

  19. Pharmacodynamic modeling of in vitro activity of marbofloxacin against Escherichia coli strains.

    Science.gov (United States)

    Andraud, M; Chauvin, C; Sanders, P; Laurentie, M

    2011-02-01

    A mathematical pharmacodynamic model was developed to describe the bactericidal activity of marbofloxacin against Escherichia coli strains with reduced susceptibility levels (determined using MICs) under optimal and intestinal growth conditions. Model parameters were estimated using nonlinear least-square curve-fitting procedures for each E. coli strain. Parameters related to bactericidal activity were subsequently analyzed using a maximum-effect (E(max)) model adapted to account for a direct and a delayed effect. While net growth rates did not vary significantly with strain susceptibility, culture medium had a major effect. The bactericidal activity of marbofloxacin was closely associated with the concentration and the duration of exposure of the bacteria to the antimicrobial agent. The value of the concentration inducing a half-maximum effect (C(50)) was highly correlated with MIC values (R(2) = 0.87 and R(2) = 0.94 under intestinal and optimal conditions, respectively). Our model reproduced the time-kill kinetics with good accuracy (R(2) of >0.90) and helped explain observed regrowth.

  20. Model of transcriptional activation by MarA in escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Michael E [Los Alamos National Laboratory; Rosner, Judah L [NATIONAL INSTITUTE OF HEALTH; Martin, Robert G [NATIONAL INSTITUTE OF HEALTH

    2009-01-01

    The AraC family transcription factor MarA activates approximately 40 genes (the marA/soxS/rob regulon) of the Escherichia coli chromosome resulting in different levels of resistance to a wide array of antibiotics and to superoxides. Activation of marA/soxS/rob regulon promoters occurs in a well-defined order with respect to the level of MarA; however, the order of activation does not parallel the strength of MarA binding to promoter sequences. To understand this lack of correspondence, we developed a computational model of transcriptional activation in which a transcription factor either increases or decreases RNA polymerase binding, and either accelerates or retards post-binding events associated with transcription initiation. We used the model to analyze data characterizing MarA regulation of promoter activity. The model clearly explains the lack of correspondence between the order of activation and the MarA-DNA affinity and indicates that the order of activation can only be predicted using information about the strength of the full MarA-polymerase-DNA interaction. The analysis further suggests that MarA can activate without increasing polymerase binding and that activation can even involve a decrease in polymerase binding, which is opposite to the textbook model of activation by recruitment. These findings are consistent with published chromatin immunoprecipitation assays of interactions between polymerase and the E. coli chromosome. We find that activation involving decreased polymerase binding yields lower latency in gene regulation and therefore might confer a competitive advantage to cells. Our model yields insights into requirements for predicting the order of activation of a regulon and enables us to suggest that activation might involve a decrease in polymerase binding which we expect to be an important theme of gene regulation in E. coli and beyond.

  1. An Escherichia coli O157-Specific Engineered Pyocin Prevents and Ameliorates Infection by E. coli O157:H7 in an Animal Model of Diarrheal Disease▿†

    OpenAIRE

    2011-01-01

    AvR2-V10.3 is an engineered R-type pyocin that specifically kills Escherichia coli O157, an enteric pathogen that is a major cause of food-borne diarrheal disease. New therapeutics to counteract E. coli O157 are needed, as currently available antibiotics can exacerbate the consequences of infection. We show here that orogastric administration of AvR2-V10.3 can prevent or ameliorate E. coli O157:H7-induced diarrhea and intestinal inflammation in an infant rabbit model of infection when the com...

  2. Modeling the role of covalent enzyme modification in Escherichia coli nitrogen metabolism

    Science.gov (United States)

    Kidd, Philip B.; Wingreen, Ned S.

    2010-03-01

    In the bacterium Escherichia coli, the enzyme glutamine synthetase (GS) converts ammonium into the amino acid glutamine. GS is principally active when the cell is experiencing nitrogen limitation, and its activity is regulated by a bicyclic covalent modification cascade. The advantages of this bicyclic-cascade architecture are poorly understood. We analyze a simple model of the GS cascade in comparison to other regulatory schemes and conclude that the bicyclic cascade is suboptimal for maintaining metabolic homeostasis of the free glutamine pool. Instead, we argue that the lag inherent in the covalent modification of GS slows the response to an ammonium shock and thereby allows GS to transiently detoxify the cell, while maintaining homeostasis over longer times.

  3. A framework and model system to investigate linear system behavior in Escherichia coli

    Science.gov (United States)

    2011-01-01

    Background The ability to compose biological systems from smaller elements that act independently of the other upon assembly may help make the forward engineering of biological systems practical. Engineering biology in this manner is made difficult by the inherent nonlinear response of organisms to genetic devices. Devices are inevitably coupled to one another in the cell because they share the same transcriptional machinery for expression. Thus, new properties can emerge when devices that had been characterized in isolation are expressed concurrently. We show in this report that, similar to physical systems, the Escherichia coli (E. coli) transcriptional system can exhibit linear behavior under "small" perturbation conditions. This, in turn, allows devices to be treated as independent modules. Results We developed a framework and model system consisting of three devices to investigate linear system behavior in E. coli. Our framework employed the transfer curve concept to determine the amount of nonlinearity elicited by the E. coli transcriptional system in response to the devices. To this effect, the model system was quantitatively characterized using real-time quantitative PCR to produce device transfer curves (DTCs). Two of the devices encoded the bacterial neomycin phosphotransferase II (nptII) and chloramphenicol acetyl transferase (cat), while the third encoded the jellyfish-originating green fluorescent protein (gfp). The gfp device was the most nonlinear in our system, with nptII and cat devices eliciting linear responses. Superposition experiments verified these findings, with independence among the three devices having been lost when gfp was present at copy numbers above the lowest one used. Conclusions We show that linear system behavior is possible in E. coli. Elucidation of the mechanism underlying the nonlinearity observed in gfp may lead to design rules that ensure linear system behavior, enabling the accurate prediction of the quantitative behavior

  4. Model-driven evaluation of the production potential for growth-coupled products of Escherichia coli.

    Science.gov (United States)

    Feist, Adam M; Zielinski, Daniel C; Orth, Jeffrey D; Schellenberger, Jan; Herrgard, Markus J; Palsson, Bernhard Ø

    2010-05-01

    Integrated approaches utilizing in silico analyses will be necessary to successfully advance the field of metabolic engineering. Here, we present an integrated approach through a systematic model-driven evaluation of the production potential for the bacterial production organism Escherichia coli to produce multiple native products from different representative feedstocks through coupling metabolite production to growth rate. Designs were examined for 11 unique central metabolism and amino acid targets from three different substrates under aerobic and anaerobic conditions. Optimal strain designs were reported for designs which possess maximum yield, substrate-specific productivity, and strength of growth-coupling for up to 10 reaction eliminations (knockouts). In total, growth-coupled designs could be identified for 36 out of the total 54 conditions tested, corresponding to eight out of the 11 targets. There were 17 different substrate/target pairs for which over 80% of the theoretical maximum potential could be achieved. The developed method introduces a new concept of objective function tilting for strain design. This study provides specific metabolic interventions (strain designs) for production strains that can be experimentally implemented, characterizes the potential for E. coli to produce native compounds, and outlines a strain design pipeline that can be utilized to design production strains for additional organisms.

  5. Measuring and modelling straining of Escherichia coli in saturated porous media.

    Science.gov (United States)

    Foppen, Jan Willem; van Herwerden, Manon; Schijven, Jack

    2007-08-15

    Though coliform bacteria are used worldwide to indicate fecal pollution of groundwater, the parameters determining the transport of Escherichia coli in aquifers are relatively unknown. We evaluated the occurrence of both straining and attachment of E. coli ATCC25922 in columns of ultra-pure, angular, saturated quartz sand. The column experiments were conducted over a wide range of porous medium sizes, column heights, input concentrations, and pore water flow velocities. Straining and attachment were examined by modelling the breakthrough curves (with HYDRUS 1D). In addition, model output was compared with measured strained and attached bacteria via column extrusion experiments (in which sand was extruded from the column and placed in excess water) and flow reversal experiments (in which the pore water flow direction was reversed, thereby dislodging strained bacteria). Our model consisted of an attachment rate coefficient and a straining rate coefficient; both of these decreased with transport distance. The straining rate coefficient also decreased in a Langmuirian way, in response to the filling of available pore space, which in turn depended on influent bacteria concentration, quartz grain diameter, and transport distance. The maximum strained fraction was 25-30% of total bacteria mass applied to the column; the maximum attached fraction was 30-35%. The fit between modelled and measured (strained and attached) bacteria masses was acceptable, as was the sensitivity of the model output to fitted parameter values. Our results lead to a new description for the time-dependent mass balance of strained bacteria, which entails using three fitting parameters. The results also imply that column experiments in combination with retention profiles (or various column lengths) are not enough to explain the retention processes in a column. Column extrusion and flow reversal experiments provide vital additional information on the occurrence and magnitude of straining. Our

  6. Predictive models for Escherichia coli concentrations at inland lake beaches and relationship of model variables to pathogen detection

    Science.gov (United States)

    Francy, Donna S.; Stelzer, Erin A.; Duris, Joseph W.; Brady, Amie M.G.; Harrison, John H.; Johnson, Heather E.; Ware, Michael W.

    2013-01-01

    Predictive models, based on environmental and water quality variables, have been used to improve the timeliness and accuracy of recreational water quality assessments, but their effectiveness has not been studied in inland waters. Sampling at eight inland recreational lakes in Ohio was done in order to investigate using predictive models for Escherichia coli and to understand the links between E. coli concentrations, predictive variables, and pathogens. Based upon results from 21 beach sites, models were developed for 13 sites, and the most predictive variables were rainfall, wind direction and speed, turbidity, and water temperature. Models were not developed at sites where the E. coli standard was seldom exceeded. Models were validated at nine sites during an independent year. At three sites, the model resulted in increased correct responses, sensitivities, and specificities compared to use of the previous day's E. coli concentration (the current method). Drought conditions during the validation year precluded being able to adequately assess model performance at most of the other sites. Cryptosporidium, adenovirus, eaeA (E. coli), ipaH (Shigella), and spvC (Salmonella) were found in at least 20% of samples collected for pathogens at five sites. The presence or absence of the three bacterial genes was related to some of the model variables but was not consistently related to E. coli concentrations. Predictive models were not effective at all inland lake sites; however, their use at two lakes with high swimmer densities will provide better estimates of public health risk than current methods and will be a valuable resource for beach managers and the public.

  7. Biomimetic control based on a model of chemotaxis in Escherichia coli.

    Science.gov (United States)

    Tsuji, Toshio; Suzuki, Michiyo; Takiguchi, Noboru; Ohtake, Hisao

    2010-01-01

    In the field of molecular biology, extending now to the more comprehensive area of systems biology, the development of computer models for synthetic cell simulation has accelerated extensively and has begun to be used for various purposes, such as biochemical analysis. These models, describing the highly efficient environmental searching mechanisms and adaptability of living organisms, can be used as machine-control algorithms in the field of systems engineering. To realize this biomimetic intelligent control, we require a stripped-down model that expresses a series of information-processing tasks from stimulation input to movement. Here we selected the bacterium Escherichia coli as a target organism because it has a relatively simple molecular and organizational structure, which can be characterized using biochemical and genetic analyses. We particularly focused on a motility response known as chemotaxis and developed a computer model that includes not only intracellular information processing but also motor control. After confirming the effectiveness and validity of the proposed model by a series of computer simulations, we applied it to a mobile robot control problem. This is probably the first study showing that a bacterial model can be used as an autonomous control algorithm. Our results suggest that many excellent models proposed thus far for biochemical purposes can be applied to problems in other fields.

  8. Modeling of the pyruvate production with Escherichia coli in a fed-batch bioreactor.

    Science.gov (United States)

    Zelić, B; Vasić-Racki, D; Wandrey, C; Takors, R

    2004-07-01

    A family of 10 competing, unstructured models has been developed to model cell growth, substrate consumption, and product formation of the pyruvate producing strain Escherichia coli YYC202 ldhA::Kan strain used in fed-batch processes. The strain is completely blocked in its ability to convert pyruvate into acetyl-CoA or acetate (using glucose as the carbon source) resulting in an acetate auxotrophy during growth in glucose minimal medium. Parameter estimation was carried out using data from fed-batch fermentation performed at constant glucose feed rates of q(VG)=10 mL h(-1). Acetate was fed according to the previously developed feeding strategy. While the model identification was realized by least-square fit, the model discrimination was based on the model selection criterion (MSC). The validation of model parameters was performed applying data from two different fed-batch experiments with glucose feed rate q(VG)=20 and 30 mL h(-1), respectively. Consequently, the most suitable model was identified that reflected the pyruvate and biomass curves adequately by considering a pyruvate inhibited growth (Jerusalimsky approach) and pyruvate inhibited product formation (described by modified Luedeking-Piret/Levenspiel term).

  9. Synergistic effects in mixed Escherichia coli biofilms

    DEFF Research Database (Denmark)

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

    2006-01-01

    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...

  10. UV-induced mutagenesis in Escherichia coli SOS response: a quantitative model.

    Directory of Open Access Journals (Sweden)

    Sandeep Krishna

    2007-03-01

    Full Text Available Escherichia coli bacteria respond to DNA damage by a highly orchestrated series of events known as the SOS response, regulated by transcription factors, protein-protein binding, and active protein degradation. We present a dynamical model of the UV-induced SOS response, incorporating mutagenesis by the error-prone polymerase, Pol V. In our model, mutagenesis depends on a combination of two key processes: damage counting by the replication forks and a long-term memory associated with the accumulation of UmuD'. Together, these provide a tight regulation of mutagenesis, resulting, we show, in a "digital" turn-on and turn-off of Pol V. Our model provides a compact view of the topology and design of the SOS network, pinpointing the specific functional role of each of the regulatory processes. In particular, we suggest that the recently observed second peak in the activity of promoters in the SOS regulon (Friedman et al., 2005, PLoS Biology 3(7: e238 is the result of positive feedback from Pol V to RecA filaments.

  11. Quantitative modeling of Escherichia coli chemotactic motion in environments varying in space and time.

    Directory of Open Access Journals (Sweden)

    Lili Jiang

    2010-04-01

    Full Text Available Escherichia coli chemotactic motion in spatiotemporally varying environments is studied by using a computational model based on a coarse-grained description of the intracellular signaling pathway dynamics. We find that the cell's chemotaxis drift velocity v(d is a constant in an exponential attractant concentration gradient [L] proportional, variantexp(Gx. v(d depends linearly on the exponential gradient G before it saturates when G is larger than a critical value G(C. We find that G(C is determined by the intracellular adaptation rate k(R with a simple scaling law: G(C infinity k(1/2(R. The linear dependence of v(d on G = d(ln[L]/dx directly demonstrates E. coli's ability in sensing the derivative of the logarithmic attractant concentration. The existence of the limiting gradient G(C and its scaling with k(R are explained by the underlying intracellular adaptation dynamics and the flagellar motor response characteristics. For individual cells, we find that the overall average run length in an exponential gradient is longer than that in a homogeneous environment, which is caused by the constant kinase activity shift (decrease. The forward runs (up the gradient are longer than the backward runs, as expected; and depending on the exact gradient, the (shorter backward runs can be comparable to runs in a spatially homogeneous environment, consistent with previous experiments. In (spatial ligand gradients that also vary in time, the chemotaxis motion is damped as the frequency omega of the time-varying spatial gradient becomes faster than a critical value omega(c, which is controlled by the cell's chemotaxis adaptation rate k(R. Finally, our model, with no adjustable parameters, agrees quantitatively with the classical capillary assay experiments where the attractant concentration changes both in space and time. Our model can thus be used to study E. coli chemotaxis behavior in arbitrary spatiotemporally varying environments. Further experiments are

  12. Shiga Toxin Producing Escherichia coli.

    Science.gov (United States)

    Bryan, Allen; Youngster, Ilan; McAdam, Alexander J

    2015-06-01

    Shiga toxin-producing Escherichia coli (STEC) is among the common causes of foodborne gastroenteritis. STEC is defined by the production of specific toxins, but within this pathotype there is a diverse group of organisms. This diversity has important consequences for understanding the pathogenesis of the organism, as well as for selecting the optimum strategy for diagnostic testing in the clinical laboratory. This review includes discussions of the mechanisms of pathogenesis, the range of manifestations of infection, and the several different methods of laboratory detection of Shiga toxin-producing E coli.

  13. QSAR models for inhibitors of physiological impact of Escherichia coli that leads to diarrhea.

    Science.gov (United States)

    Toropov, Andrey A; Toropova, Alla P; Benfenati, Emilio; Gini, Giuseppina; Leszczynska, Danuta; Leszczynski, Jerzy; De Nucci, Gilberto

    2013-03-08

    Quantitative structure - activity relationships (QSARs) developed to evaluate percentage of inhibition of STa-stimulated (Escherichia coli) cGMP accumulation in T84 cells are calculated by the Monte Carlo method. This endpoint represents a measure of biological activity of a substance against diarrhea. Statistical quality of the developed models is quite good. The approach is tested using three random splits of data into the training and test sets. The statistical characteristics for three splits are the following: (1) n=20, r(2)=0.7208, q(2)=0.6583, s=16.9, F=46 (training set); n=11, r(2)=0.8986, s=14.6 (test set); (2) n=19, r(2)=0.6689, q(2)=0.5683, s=17.6, F=34 (training set); n=12, r(2)=0.8998, s=12.1 (test set); and (3) n=20, r(2)=0.7141, q(2)=0.6525, s=14.7, F=45 (training set); n=11, r(2)=0.8858, s=19.5 (test set). Based on the proposed here models hypothetical compounds which can be useful agents against diarrhea are suggested. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Structure of Escherichia coli tryptophanase.

    Science.gov (United States)

    Ku, Shao Yang; Yip, Patrick; Howell, P Lynne

    2006-07-01

    Pyridoxal 5'-phosphate (PLP) dependent tryptophanase has been isolated from Escherichia coli and its crystal structure has been determined. The structure shares the same fold with and has similar quaternary structure to Proteus vulgaris tryptophanase and tyrosine-phenol lyase, but is found in a closed conformation when compared with these two enzymes. The tryptophanase structure, solved in its apo form, does not have covalent PLP bound in the active site, but two sulfate ions. The sulfate ions occupy the phosphoryl-binding site of PLP and the binding site of the alpha-carboxyl of the natural substrate tryptophan. One of the sulfate ions makes extensive interactions with both the transferase and PLP-binding domains of the protein and appears to be responsible for holding the enzyme in its closed conformation. Based on the sulfate density and the structure of the P. vulgaris enzyme, PLP and the substrate tryptophan were modeled into the active site. The resulting model is consistent with the roles of Arg419 in orienting the substrate to PLP and acidifying the alpha-proton of the substrate for beta-elimination, Lys269 in the formation and decomposition of the PLP quinonoid intermediate, Arg230 in orienting the substrate-PLP intermediates in the optimal conformation for catalysis, and His463 and Tyr74 in determining substrate specificity and suggests that the closed conformation observed in the structure could be induced by substrate binding and that significant conformational changes occur during catalysis. A catalytic mechanism for tryptophanase is proposed. Since E. coli tryptophanase has resisted forming diffraction-quality crystals for many years, the molecular surface of tryptophanase has been analyzed in various crystal forms and it was rationalized that strong crystal contacts occur on the flat surface of the protein and that the size of crystal contact surface seems to correlate with the diffraction quality of the crystal.

  15. Structure of Escherichia Coli Tryptophanase

    Energy Technology Data Exchange (ETDEWEB)

    Ku,S.; Yip, P.; Howell, P.

    2006-01-01

    Pyridoxal 5'-phosphate (PLP) dependent tryptophanase has been isolated from Escherichia coli and its crystal structure has been determined. The structure shares the same fold with and has similar quaternary structure to Proteus vulgaris tryptophanase and tyrosine-phenol lyase, but is found in a closed conformation when compared with these two enzymes. The tryptophanase structure, solved in its apo form, does not have covalent PLP bound in the active site, but two sulfate ions. The sulfate ions occupy the phosphoryl-binding site of PLP and the binding site of the {alpha}-carboxyl of the natural substrate tryptophan. One of the sulfate ions makes extensive interactions with both the transferase and PLP-binding domains of the protein and appears to be responsible for holding the enzyme in its closed conformation. Based on the sulfate density and the structure of the P. vulgaris enzyme, PLP and the substrate tryptophan were modeled into the active site. The resulting model is consistent with the roles of Arg419 in orienting the substrate to PLP and acidifying the {alpha}-proton of the substrate for {beta}-elimination, Lys269 in the formation and decomposition of the PLP quinonoid intermediate, Arg230 in orienting the substrate-PLP intermediates in the optimal conformation for catalysis, and His463 and Tyr74 in determining substrate specificity and suggests that the closed conformation observed in the structure could be induced by substrate binding and that significant conformational changes occur during catalysis. A catalytic mechanism for tryptophanase is proposed. Since E. coli tryptophanase has resisted forming diffraction-quality crystals for many years, the molecular surface of tryptophanase has been analyzed in various crystal forms and it was rationalized that strong crystal contacts occur on the flat surface of the protein and that the size of crystal contact surface seems to correlate with the diffraction quality of the crystal.

  16. Escherichia coli transcriptional regulatory network

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    Agustino Martinez-Antonio

    2011-06-01

    Full Text Available Escherichia coli is the most well-know bacterial model about the function of its molecular components. In this review are presented several structural and functional aspects of their transcriptional regulatory network constituted by transcription factors and target genes. The network discussed here represent to 1531 genes and 3421 regulatory interactions. This network shows a power-law distribution with a few global regulators and most of genes poorly connected. 176 of genes in the network correspond to transcription factors, which form a sub-network of seven hierarchical layers where global regulators tend to be set in superior layers while local regulators are located in the lower ones. There is a small set of proteins know as nucleoid-associated proteins, which are in a high cellular concentrations and reshape the nucleoid structure to influence the running of global transcriptional programs, to this mode of regulation is named analog regulation. Specific signal effectors assist the activity of most of transcription factors in E. coli. These effectors switch and tune the activity of transcription factors. To this type of regulation, depending of environmental signals is named the digital-precise-regulation. The integration of regulatory programs have place in the promoter region of transcription units where it is common to observe co-regulation among global and local TFs as well as of TFs sensing exogenous and endogenous conditions. The mechanistic logic to understand the harmonious operation of regulatory programs in the network should consider the globalism of TFs, their signal perceived, coregulation, genome position, and cellular concentration. Finally, duplicated TFs and their horizontal transfer influence the evolvability of members of the network. The most duplicated and transferred TFs are located in the network periphery.

  17. Characterization of Escherichia coli MG1655 grown in a low-shear modeled microgravity environment

    Directory of Open Access Journals (Sweden)

    Pierson Duane L

    2007-03-01

    Full Text Available Abstract Background Extra-cellular shear force is an important environmental parameter that is significant both medically and in the space environment. Escherichia coli cells grown in a low-shear modeled microgravity (LSMMG environment produced in a high aspect rotating vessel (HARV were subjected to transcriptional and physiological analysis. Results Aerobic LSMMG cultures were grown in rich (LB and minimal (MOPS + glucose medium with a normal gravity vector HARV control. Reproducible changes in transcription were seen, but no specific LSMMG responsive genes were identified. Instead, absence of shear and a randomized gravity vector appears to cause local extra-cellular environmental changes, which elicit reproducible cellular responses. In minimal media, the majority of the significantly up- or down-regulated genes of known function were associated with the cell envelope. In rich medium, most LSMMG down-regulated genes were involved in translation. No observable changes in post-culture stress responses and antibiotic sensitivity were seen in cells immediately after exposure to LSMMG. Comparison with earlier studies of Salmonella enterica serovar Typhimurium conducted under similar growth conditions, revealed essentially no similarity in the genes that were significantly up- or down-regulated. Conclusion Comparison of these results to previous studies suggests that different organisms may dramatically differ in their responses to medically significant low-shear and space environments. Depending on their specific response, some organisms, such as Salmonella, may become preadapted in a manner that predisposes them to increased virulence.

  18. Reaction dynamics analysis of a reconstituted Escherichia coli protein translation system by computational modeling.

    Science.gov (United States)

    Matsuura, Tomoaki; Tanimura, Naoki; Hosoda, Kazufumi; Yomo, Tetsuya; Shimizu, Yoshihiro

    2017-02-21

    To elucidate the dynamic features of a biologically relevant large-scale reaction network, we constructed a computational model of minimal protein synthesis consisting of 241 components and 968 reactions that synthesize the Met-Gly-Gly (MGG) peptide based on an Escherichia coli-based reconstituted in vitro protein synthesis system. We performed a simulation using parameters collected primarily from the literature and found that the rate of MGG peptide synthesis becomes nearly constant in minutes, thus achieving a steady state similar to experimental observations. In addition, concentration changes to 70% of the components, including intermediates, reached a plateau in a few minutes. However, the concentration change of each component exhibits several temporal plateaus, or a quasi-stationary state (QSS), before reaching the final plateau. To understand these complex dynamics, we focused on whether the components reached a QSS, mapped the arrangement of components in a QSS in the entire reaction network structure, and investigated time-dependent changes. We found that components in a QSS form clusters that grow over time but not in a linear fashion, and that this process involves the collapse and regrowth of clusters before the formation of a final large single cluster. These observations might commonly occur in other large-scale biological reaction networks. This developed analysis might be useful for understanding large-scale biological reactions by visualizing complex dynamics, thereby extracting the characteristics of the reaction network, including phase transitions.

  19. Acute Lung Injury and Fibrosis in a Baboon Model of Escherichia coli Sepsis

    Science.gov (United States)

    Keshari, Ravi S.; Silasi-Mansat, Robert; Zhu, Hua; Popescu, Narcis I.; Peer, Glenn; Chaaban, Hala; Lambris, John D.; Polf, Holly; Lupu, Cristina; Kinasewitz, Gary

    2014-01-01

    Sepsis-induced inflammation of the lung leads to acute respiratory distress syndrome (ARDS), which may trigger persistent fibrosis. The pathology of ARDS is complex and poorly understood, and the therapeutic approaches are limited. We used a baboon model of Escherichia coli sepsis that mimics the complexity of human disease to study the pathophysiology of ARDS. We performed extensive biochemical, histological, and functional analyses to characterize the disease progression and the long-term effects of sepsis on the lung structure and function. Similar to humans, sepsis-induced ARDS in baboons displays an early inflammatory exudative phase, with extensive necrosis. This is followed by a regenerative phase dominated by proliferation of type 2 epithelial cells, expression of epithelial-to-mesenchymal transition markers, myofibroblast migration and proliferation, and collagen synthesis. Baboons that survived sepsis showed persistent inflammation and collagen deposition 6–27 months after the acute episodes. Long-term survivors had almost double the amount of collagen in the lung as compared with age-matched control animals. Immunostaining for procollagens showed persistent active collagen synthesis within the fibroblastic foci and interalveolar septa. Fibroblasts expressed markers of transforming growth factor-β and platelet-derived growth factor signaling, suggesting their potential role as mediators of myofibroblast migration and proliferation, and collagen deposition. In parallel, up-regulation of the inhibitors of extracellular proteases supports a deregulated matrix remodeling that may contribute to fibrosis. The primate model of sepsis-induced ARDS mimics the disease progression in humans, including chronic inflammation and long-lasting fibrosis. This model helps our understanding of the pathophysiology of fibrosis and the testing of new therapies. PMID:24066737

  20. An Escherichia coli O157-specific engineered pyocin prevents and ameliorates infection by E. coli O157:H7 in an animal model of diarrheal disease.

    Science.gov (United States)

    Ritchie, Jennifer M; Greenwich, Jennifer L; Davis, Brigid M; Bronson, Roderick T; Gebhart, Dana; Williams, Steven R; Martin, David; Scholl, Dean; Waldor, Matthew K

    2011-12-01

    AvR2-V10.3 is an engineered R-type pyocin that specifically kills Escherichia coli O157, an enteric pathogen that is a major cause of food-borne diarrheal disease. New therapeutics to counteract E. coli O157 are needed, as currently available antibiotics can exacerbate the consequences of infection. We show here that orogastric administration of AvR2-V10.3 can prevent or ameliorate E. coli O157:H7-induced diarrhea and intestinal inflammation in an infant rabbit model of infection when the compound is administered either in a postexposure prophylactic regimen or after the onset of symptoms. Notably, administration of AvR2-V10.3 also reduces bacterial carriage and fecal shedding of this pathogen. Our findings support the further development of pathogen-specific R-type pyocins as a way to treat enteric infections.

  1. Virulence variations in Shigella and enteroinvasive Escherichia coli using the Caenorhabditis elegans model.

    Science.gov (United States)

    Fung, Crystal Ching; Octavia, Sophie; Mooney, Anne-Marie; Lan, Ruiting

    2015-01-01

    Shigella species and enteroinvasive Escherichia coli (EIEC) belong to the same species genetically, with remarkable phenotypic and genomic similarities. Shigella is the main cause of bacillary dysentery with around 160 million annual cases, while EIEC generally induces a milder disease compared to Shigella. This study aimed to determine virulence variations between Shigella and EIEC using the nematode Caenorhabditis elegans as a model host. Caenorhabditis elegans killing- and bacterial colonization assays were performed to examine the potential difference in virulence between Shigella and EIEC strains. Statistically significant difference in the survival rates of nematodes was demonstrated, with Shigella causing death at 88.24 ± 1.20% and EIEC at 94.37 ± 0.70%. The intestinal load of bacteria in the nematodes was found to be 7.65 × 10(4) ± 8.83 × 10(3) and 2.92 × 10(4) ± 6.26 × 10(3) CFU ml(-1) per nematode for Shigella and EIEC, respectively. Shigella dysenteriae serotype 1 which carries the Shiga toxin showed the lowest nematode survival rate at 82.6 ± 3.97% and highest bacterial colonization of 1.75 × 10(5) ± 8.17 × 10(4) CFU ml(-1), whereas a virulence plasmid-negative Shigella strain demonstrated 100 ± 0% nematode survival and lowest bacterial accumulation of 1.02 × 10(4) ± 7.23 × 10(2) CFU ml(-1). This study demonstrates C. elegans as an effective model for examining and comparing Shigella and EIEC virulence variation.

  2. 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...

  3. 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...

  4. Modeling mutant distribution in a stressed Escherichia coli bacteria population using experimental data

    Science.gov (United States)

    Bazzani, Armando; Fani, Renato; Freguglia, Paolo

    2014-01-01

    In this paper we propose a statistical physics approach to experimental results on bacterial mutations (Escherichia coli). We get scaling laws that describe some generic traits and suggest some features of the underlying dynamical structure for the considered evolution process. Our main assumption is that the evolution dynamics could be visualized as a random walk on a fitness landscape whose topological structure is analogous to the structure of energy landscape potentials used in Physics and Chemistry. Then we relate the generic distribution of local minima attraction basins to the number of bacterial mutations and we discuss the comparison with experimental results.

  5. Immunomodulatory effects of Escherichia coli ATCC 25922 on allergic airway inflammation in a mouse model.

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    Wenhui Pang

    Full Text Available BACKGROUND: Hygiene hypothesis demonstrates that the lack of microbial exposure would promote the development of allergic airway disease (AAD. Therefore, the gut microbiota, including Escherichia coli (E. coli, would probably offer a potential strategy for AAD. OBJECTIVE: To investigate whether E. coli infection is able to suppress the induction of AAD and to elucidate the underlying mechanisms. METHODS: Nonpathogenic E. coli ATCC 25922 was infected by gavage before AAD phase in three patterns: 10(8 or 10(6 CFU in neonates or 10(8 CFU in adults. Then mice were sensitized and challenged with ovalbumin (OVA to induce allergic inflammation in both the upper and lower airways. Hallmarks of AAD, in terms of eosinophil infiltration and goblet cell metaplasia in subepithelial mucosa, Th2 skewing of the immune response, and levels of T regulate cells (Tregs, were examined by histological analysis, ELISA, and flow cytometry, respectively. RESULTS: E. coli, especially neonatally infected with an optimal dose, attenuated allergic responses, including a decrease in nasal rubbing and sneezing, a reduction in eosinophil inflammation and goblet cell metaplasia in subepithelial mucosa, decreased serum levels of OVA-specific IgE, and reduced Th2 (IL-4 cytokines. In contrast, this effect came with an increase of Th1 (IFN-r and IL-2 cytokines, and an enhancement of IL-10-secreting Tregs in paratracheal lymph nodes (PTLN. CONCLUSION: E. coli suppresses allergic responses in mice, probably via a shift from Th1 to Th2 and/or induction of Tregs. Moreover, this infection is age- and dose-dependent, which may open up novel possibilities for new therapeutic interventions.

  6. Escherichia coli pollution in a Baltic Sea lagoon: a model-based source and spatial risk assessment.

    Science.gov (United States)

    Schippmann, Bianca; Schernewski, Gerald; Gräwe, Ulf

    2013-07-01

    Tourism around the Oder (Szczecin) Lagoon, at the southern Baltic coast, has a long tradition, is an important source of income and shall be further developed. Insufficient bathing water quality and frequent beach closings, especially in the Oder river mouth, hamper tourism development. Monitoring data gives only an incomplete picture of Escherichia coli (E. coli) bacteria sources, spatial transport patterns, risks and does neither support an efficient bathing water quality management nor decision making. We apply a 3D ocean model and a Lagrangian particle tracking model to analyse pollution events and to obtain spatial E. coli pollution maps based on scenario simulations. Model results suggests that insufficient sewage treatment in the city of Szczecin is the major source of faecal pollution, even for beaches 20km downstream. E. coli mortality rate and emission intensity are key parameters for concentration levels downstream. Wind and river discharge play a modifying role. Prevailing southwestern wind conditions cause E. coli transport along the eastern coast and favour high concentration levels at the beaches. Our simulations indicate that beach closings in 2006 would not have been necessary according to the new EU-Bathing Water Quality Directive (2006/7/EC). The implementation of the new directive will, very likely, reduce the number of beach closings, but not the risk for summer tourists. Model results suggest, that a full sewage treatment in Szczecin would allow the establishment of new beaches closer to the city (north of Dabie lake). Copyright © 2013 Elsevier GmbH. All rights reserved.

  7. A simulation model of Escherichia coli osmoregulatory switch using E-CELL system

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    Krishnaswamy Sankaran

    2004-11-01

    Full Text Available Abstract Background Bacterial signal transduction mechanism referred to as a "two component regulatory systems" contributes to the overall adaptability of the bacteria by regulating the gene expression. Osmoregulation is one of the well-studied two component regulatory systems comprising of the sensor, EnvZ and the cognate response regulator, OmpR, which together control the expression of OmpC and OmpF porins in response to the osmolyte concentration. Results A quantitative model of the osmoregulatory switch operative in Escherichia coli was constructed by integrating the enzyme rate equations using E-CELL system. Using the substance reactor logic of the E-CELL system, a total of 28 reactions were defined from the injection of osmolyte till the regulated expression of porins by employing the experimental kinetic constants as reported in literature. In the case of low osmolarity, steady state production of OmpF and repression of OmpC was significant. In this model we show that the steady state – production of OmpF is dramatically reduced in the high osmolarity medium. The rate of OmpC production increased after sucrose addition, which is comparable with literature results. The relative porin production seems to be unaltered with changes in cell volume changes, ATP, EnvZ and OmpR at low and high osmolarity conditions. But the reach of saturation was rapid at high and low osmolarity with altered levels of the above components. Conclusions The E-CELL system allows us to perform virtual experiments on the bacterial osmoregulation model. This model does not take into account interaction with other networks in the cell. It suggests that the regulation of OmpF and OmpC is a direct consequence of the level of OmpRP in the cell and is dependent on the way in which OmpRP interacts with ompF and ompC regulatory regions. The preliminary simulation experiment indicates that both reaching steady state expression and saturation is delayed in the case of Omp

  8. Modeling the Survival of Escherichia coli O157:H7 During Fermentation, Drying, and Storage of a Soudjouk-Style Fermented Dry or Semi-Dry Sausage

    Science.gov (United States)

    Cases of foodborne illness have been linked to the consumption of fermented dry or semi-dry sausages (FDSS) contaminated with Escherichia coli O157:H7. The purpose of this study was to model the inactivation of E. coli O157:H7 during FDSS manufacturing and storage. Beef batter (20% fat) containing...

  9. Robust Parameter Identification to Perform the Modeling of pta and poxB Genes Deletion Effect on Escherichia Coli.

    Science.gov (United States)

    Guerrero-Torres, V; Rios-Lozano, M; Badillo-Corona, J A; Chairez, I; Garibay-Orijel, C

    2016-08-01

    The aim of this study was to design a robust parameter identification algorithm to characterize the effect of gene deletion on Escherichia coli (E. coli) MG1655. Two genes (pta and poxB) in the competitive pathways were deleted from this microorganism to inhibit pyruvate consumption. This condition deviated the E. coli metabolism toward the Krebs cycle. As a consequence, the biomass, substrate (glucose), lactic, and acetate acids as well as ethanol concentrations were modified. A hybrid model was proposed to consider the effect of gene deletion on the metabolism of E. coli. The model parameters were estimated by the application of a least mean square method based on the instrument variable technique. To evaluate the parametric identifier method, a set of robust exact differentiators, based on the super-twisting algorithm, was implemented. The hybrid model was successfully characterized by the parameters obtained from experimental information of E. coli MG1655. The significant difference between parameters obtained with wild-type strain and the modified (with deleted genes) justifies the application of the parametric identification algorithm. This characterization can be used to optimize the production of different byproducts of commercial interest.

  10. Monitoring and modeling to predict Escherichia coli at Presque Isle Beach 2, City of Erie, Erie County, Pennsylvania

    Science.gov (United States)

    Zimmerman, Tammy M.

    2006-01-01

    The Lake Erie shoreline in Pennsylvania spans nearly 40 miles and is a valuable recreational resource for Erie County. Nearly 7 miles of the Lake Erie shoreline lies within Presque Isle State Park in Erie, Pa. Concentrations of Escherichia coli (E. coli) bacteria at permitted Presque Isle beaches occasionally exceed the single-sample bathing-water standard, resulting in unsafe swimming conditions and closure of the beaches. E. coli concentrations and other water-quality and environmental data collected at Presque Isle Beach 2 during the 2004 and 2005 recreational seasons were used to develop models using tobit regression analyses to predict E. coli concentrations. All variables statistically related to E. coli concentrations were included in the initial regression analyses, and after several iterations, only those explanatory variables that made the models significantly better at predicting E. coli concentrations were included in the final models. Regression models were developed using data from 2004, 2005, and the combined 2-year dataset. Variables in the 2004 model and the combined 2004-2005 model were log10 turbidity, rain weight, wave height (calculated), and wind direction. Variables in the 2005 model were log10 turbidity and wind direction. Explanatory variables not included in the final models were water temperature, streamflow, wind speed, and current speed; model results indicated these variables did not meet significance criteria at the 95-percent confidence level (probabilities were greater than 0.05). The predicted E. coli concentrations produced by the models were used to develop probabilities that concentrations would exceed the single-sample bathing-water standard for E. coli of 235 colonies per 100 milliliters. Analysis of the exceedence probabilities helped determine a threshold probability for each model, chosen such that the correct number of exceedences and nonexceedences was maximized and the number of false positives and false negatives was

  11. Analysis and modeling of heat-labile enterotoxins of Escherichia coli suggests a novel space with insights into receptor preference.

    Science.gov (United States)

    Krishna Raja, M; Ghosh, Asit Ranjan; Vino, S; Sajitha Lulu, S

    2015-01-01

    Features of heat-labile enterotoxins of Escherichia coli which make them fit to use as novel receptors for antidiarrheals are not completely explored. Data-set of 14 different serovars of enterotoxigenic Escherichia coli producing heat-labile toxins were taken from NCBI Genbank database and used in the study. Sequence analysis showed mutations in different subunits and also at their interface residues. As these toxins lack crystallography structures, homology modeling using Modeller 9.11 led to the structural approximation for the E. coli producing heat-labile toxins. Interaction of modeled toxin subunits with proanthocyanidin, an antidiarrheal showed several strong hydrogen bonding interactions at the cost of minimized energy. The hits were subsequently characterized by molecular dynamics simulation studies to monitor their binding stabilities. This study looks into novel space where the ligand can choose the receptor preference not as a whole but as an individual subunit. Mutation at interface residues and interaction among subunits along with the binding of ligand to individual subunits would help to design a non-toxic labile toxin and also to improve the therapeutics.

  12. The evolution of the Escherichia coli phylogeny.

    Science.gov (United States)

    Chaudhuri, Roy R; Henderson, Ian R

    2012-03-01

    Escherichia coli is familiar to biologists as a classical model system, ubiquitous in molecular biology laboratories around the world. Outside of the laboratory, E. coli strains exist as an almost universal component of the lower-gut flora of humans and animals. Although usually a commensal, E. coli has an alter ego as a pathogen, and is associated with diarrhoeal disease and extra-intestinal infections. The study of E. coli diversity predates the availability of molecular data, with strains initially distinguished by serotyping and metabolic profiling, and genomic diversity illustrated by DNA hybridisation. The quantitative study of E. coli diversity began with the application of multi-locus enzyme electrophoresis (MLEE), and has progressed with the accumulation of nucleotide sequence data, from single genes through multi-locus sequence typing (MLST) to whole genome sequencing. Phylogenetic methods have shed light on the processes of genomic evolution in this extraordinarily diverse species, and revealed the origins of pathogenic E. coli strains, including members of the phylogenetically indistinguishable "genus"Shigella. In May and June 2011, an outbreak of haemorrhagic uraemic syndrome in Germany was linked to a strain of enterohaemorrhagic E. coli (EHEC) O104:H4. Application of high-throughput sequencing technologies allowed the genome and origins of the outbreak strain to be characterised in real time as the outbreak was in progress.

  13. A mechanism for precision-sensing via a gradient-sensing pathway: a model of Escherichia coli thermotaxis.

    Science.gov (United States)

    Jiang, Lili; Ouyang, Qi; Tu, Yuhai

    2009-07-01

    Thermotaxis is the phenomenon where an organism directs its movement toward its preferred temperature. So far, the molecular origin for this precision-sensing behavior remains a puzzle. We propose a model of Escherichia coli thermotaxis and show that the precision-sensing behavior in E. coli thermotaxis can be carried out by the gradient-sensing chemotaxis pathway under two general conditions. First, the thermosensor response to temperature is inverted by its internal adaptation state. For E. coli, chemoreceptor Tar changes from a warm sensor to a cold sensor on increase of its methylation level. Second, temperature directly affects the adaptation kinetics. The adapted activity in E. coli increases with temperature in contrast to the perfect adaptation to chemical stimuli. Given these two conditions, E. coli thermotaxis is achieved by the cryophilic and thermophilic responses for temperature above and below a critical temperature Tc, which is encoded by internal pathway parameters. Our model results are supported by both experiments with adaptation-disabled mutants and the recent temperature impulse response measurements for wild-type cells. Tc is predicted to decrease with the background attractant concentration. This mechanism for precision sensing in an adaptive gradient-sensing system may apply to other organisms, such as Dictyostelium discoideum and Caenorhabditis elegans.

  14. Quantifying exposure to vero-cytotoxigenic Escherichia coli O157 in milk sold as pasteurized: a model-based approach.

    Science.gov (United States)

    Clough, Helen E; Clancy, Damian; French, Nigel P

    2009-05-31

    Milk sold as pasteurized has historically been implicated in the UK and worldwide as a vehicle for outbreaks of food-borne gastrointestinal disease, with a number of causative pathogenic organisms. One such organism is verocytotoxigenic Escherichia coli, or E. coli, O157 (VTEC O157). We present a quantitative assessment of likely exposure to VTEC O157 via milk sold as pasteurized in the UK. Particular interest in our assessment concerns whether there is any differential risk between milk which is processed in on- and off-farm dairies. We model the milk production chain from the farm through to the point of retail and make a comparison between these two production environments. Our model is an example of the Modular Process Risk Modelling (MPRM) approach and represents uncertainty and variability in input parameters using probability distributions. We conclude that milk processed on farm poses the comparatively greater risk, although that risk is still small.

  15. Potential of the Cnidium monnieri fruits as an immune enhancer in Escherichia coli infection model.

    Science.gov (United States)

    Malla, Bindu; Chang, Bo Yoon; Kim, Seon Beom; Park, Hyun; Lee, Mi Kyeong; Kim, Sung Yeon

    2016-11-01

    The Cnidium monnieri fruits (CMF) were studied how they act on immune system as a novel immunostimulator against the infectious disease. Macrophages were treated with CMF, and nitric oxide (NO) and tumour necrosis factor-α (TNF-α) were measured, and phagocytosis of macrophages was detected using FITC-labelled Escherichia coli. The protective effect of CMF against E. coli infection in mice was examined. The survival rate was monitored daily for up to 5 days. And then the viable bacteria count of serum and the immunological mediator (NO, TNF-α, interleukin (IL)-12 and IL-6) of serum, splenocyte and peritoneal macrophages were analysed. The CMF significantly enhanced the concentrations of NO and TNF-α and the phagocytosis activity in macrophages. The oral administration of CMF for five consecutive days before infection prolonged the survival rate. Treatment with CMF significantly stimulated the phagocytosis of peritoneal macrophages and induced the immunological mediator of serum, splenocyte and peritoneal macrophages against the E. coli infection. The host-protective effects of CMF might be archived by improving immune response, and CMF could act to prevent pathogenic microbial infections with immunomodulation. © 2016 Royal Pharmaceutical Society.

  16. Pharmacodynamic modelling of in vitro activity of tetracycline against a representative, naturally occurring population of porcine Escherichia coli

    DEFF Research Database (Denmark)

    Ahmad, Amais; Zachariasen, Camilla; Christiansen, Lasse Engbo;

    2015-01-01

    text] between susceptible and resistant strains in the absence of a drug was not different. EC 50 increased linearly with MIC on a log-log scale, and γ was different between susceptible and resistant strains. The in vitro model parameters described the inhibition effect of tetracycline on E. coli when...... of Escherichia coli representative of those found in the Danish pig population, we compared the growth of 50 randomly selected strains. The observed net growth rates were used to describe the in vitro pharmacodynamic relationship between drug concentration and net growth rate based on E max model with three...... parameters: maximum net growth rate (α max ); concentration for a half-maximal response (E max ); and the Hill coefficient (γ). The net growth rate in the absence of antibiotic did not differ between susceptible and resistant isolates (P = 0.97). The net growth rate decreased with increasing tetracycline...

  17. Two distinct regions in the model protein Peb1 are critical for its heterologous transport out of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Laakkonen Liisa

    2010-12-01

    Full Text Available Abstract Background Escherichia coli is frequently the first-choice host organism in expression of heterologous recombinant proteins in basic research as well as in production of commercial, therapeutic polypeptides. Especially the secretion of proteins into the culture medium of E. coli is advantageous compared to intracellular production due to the ease in recovery of the recombinant protein. Since E. coli naturally is a poor secretor of proteins, a few strategies for optimization of extracellular secretion have been described. We have previously reported efficient secretion of the diagnostically interesting model protein Peb1 of Campylobacter jejuni into the growth medium of Escherichia coli strain MKS12 (ΔfliCfliD. To generate a more detailed understanding of the molecular mechanisms behind this interesting heterologous secretion system with biotechnological implications, we here analyzed further the transport of Peb1 in the E. coli host. Results When mature Peb1 was expressed without its SecA-YEG -dependent signal sequence and without the putative signal peptidase II recognition sequence in E. coli MKS111ΔHBB lacking the flagellar secretion complex, the protein was found in the periplasm and growth medium which indicated a flagellum-independent translocation. We assessed the Peb1 secretion proficiency by an exhaustive search for transport-affecting regions using a transposition-based scanning mutagenesis strategy. Strikingly, insertion mutagenesis of only two segments, called TAR1 (residues 42 and 43 and TAR2 (residues 173 to 180, prevented Peb1 secretion individually. We confirmed the importance of TAR regions by subsequent site-specific mutagenesis and verified that the secretion deficiency of Peb1 mutants was not due to insolubility or aggregation of the proteins in the cytoplasm. We found by cell fractionation that the mutant proteins were present in the periplasm as well as in the cytoplasm of MKS12. Hence, mutagenesis of TAR regions

  18. Modeling the fate of Escherichia coli O157:H7 and Salmonella enterica in the agricultural environment: current perspective.

    Science.gov (United States)

    Ongeng, Duncan; Haberbeck, Leticia U; Mauriello, Gianluigi; Ryckeboer, Jaak; Springael, Dirk; Geeraerd, Annemie H

    2014-04-01

    The significance of fresh vegetable consumption on human nutrition and health is well recognized. Human infections with Escherichia coli O157:H7 and Salmonella enterica linked to fresh vegetable consumption have become a serious public health problem inflicting a heavy economic burden. The use of contaminated livestock wastes such as manure and manure slurry in crop production is believed to be one of the principal routes of fresh vegetable contamination with E. coli O157:H7 and S. enterica at preharvest stage because both ruminant and nonruminant livestock are known carriers of E. coli O157:H7 and S. enterica in the environment. A number of challenge-testing studies have examined the fate of E. coli O157:H7 and S. enterica in the agricultural environment with the view of designing strategies for controlling vegetable contamination preharvest. In this review, we examined the mathematical modeling approaches that have been used to study the behavior of E. coli O157:H7 and S. enterica in the manure, manure-amended soil, and in manure-amended soil-plant ecosystem during cultivation of fresh vegetable crops. We focused on how the models have been applied to fit survivor curves, predict survival, and assess the risk of vegetable contamination preharvest. The inadequacies of the current modeling approaches are discussed and suggestions for improvements to enhance the applicability of the models as decision tools to control E. coli O157:H7 and S. enterica contamination of fresh vegetables during primary production are presented.

  19. Experimental electromagnetic effects on the model organism Escherichia coli and the bacteriophage T4

    Science.gov (United States)

    Lisiewski, Darlene Mildred

    This experimentally-based work was designed to answer the research question as to whether the phenomenon of nuclear magnetic resonance (NMR) can produce observable effects upon the bacterial virus activity of T4, with such activity demonstrated through the infection of its host bacterium Escherichia coli. The biological samples were placed for three hours within a coil antenna assembly propagating oscillating fields of radio frequency electromagnetic energy generated at the frequency of 5.6 MHz, and set at right angles within a magnetic field of 1450 gauss (recognizing such conditions are not set for the maximum effective resonance for hydrogen nuclei). The laboratory technique of plaque formation was the basis upon which the statistically tested data were compiled. Exposure of the bacterium alone exhibited an increase in viral activity over the control group (40--68% higher numbers of plaque formation), while exposure of T4 alone saw a decrease (approximately 23%) in infection rates. Depending on the protocol, placement of both T4 and E. coli into the coil assembly saw a decrease of either approximately 50% or 42% in infection rates. Future research must address identification of the effects being observed.

  20. Proteomic analysis of beryllium-induced genotoxicity in an Escherichia coli mutant model system.

    Science.gov (United States)

    Taylor-McCabe, Kirsten J; Wang, Zaolin; Sauer, Nancy N; Marrone, Babetta L

    2006-03-01

    Beryllium is the second lightest metal, has a high melting point and high strength-to-weight ratio, and is chemically stable. These unique chemical characteristics make beryllium metal an ideal choice as a component material for a wide variety of applications in aerospace, defense, nuclear weapons, and industry. However, inhalation of beryllium dust or fumes induces significant health effects, including chronic beryllium disease and lung cancer. In this study, the mutagenicity of beryllium sulfate (BeSO(4)) and the comutagenicity of beryllium with a known mutagen 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) were evaluated using a forward mutant detection system developed in Escherichia coli. In this system, BeSO(4) was shown to be weakly mutagenic alone and significantly enhanced the mutagenicity of MNNG up to 3.5-fold over MNNG alone. Based on these results a proteomic study was conducted to identify the proteins regulated by BeSO(4). Using the techniques of 2-DE and oMALDI-TOF MS, we successfully identified 32 proteins being differentially regulated by beryllium and/or MNNG in the E. coli test system. This is the first study to describe the proteins regulated by beryllium in vitro, and the results suggest several potential pathways for the focus of further research into the mechanisms underlying beryllium-induced genotoxicity.

  1. Utilization of evolutionary model, bioinformatics and heuristics for development of a multiplex Escherichia coli O157:H7 PCR assay

    Science.gov (United States)

    Introduction: Escherichia coli O157:H7 is a devastating foodborne pathogen causing many foodborne outbreaks worldwide with significant morbidity and mortality. The plasticity of the E. coli O157:H7 genome, inconsistent expression of surface antigens, and sharing of genetic elements with other non-...

  2. Pharmacokinetic-Pharmacodynamic modeling of enrofloxacin against Escherichia coli in broilers

    Directory of Open Access Journals (Sweden)

    Sang eKana

    2016-01-01

    Full Text Available The purpose of the present study was to establish a pharmacokinetic/pharmacodynamic (PK/PD modeling approach for the dosage schedule design and decreasing the emergence of drug-resistant bacteria. The minimal inhibitory concentration (MIC of 929 E. coli isolates from broilers to enrofloxacin and ciprofloxacin were determined following CLSI guidance. The MIC50 was calculated as the populational PD parameter for enrofloxacin against E. coli in broilers. The 101 E. coli strains with MIC closest to the MIC50 (0.05µg/mL were submitted for serotype identification. The 13 E. coli strains with O and K serotype were further utilitzed for determining pathogencity in mice. Of all the strains tested, the E. coli designated strain Anhui 112 was selected for establishing the disease model and PK/PD study. The pharmacokinetics (PKs of enrofloxacin after oral administration at the dose of 10mg/kg body weights (BW in healthy and infected broilers was evaluated with high-performance liquid chromatography (HPLC method. For intestinal contents after oral administration, the peak concentration (Cmax, the time when the maximum concentration reached (Tmax, and the area under the concentration-time curve (AUC were 21.69~31.69μg/mL, 1.13~1.23h, and 228.97~444.86μg.hr/mL, respectively. The MIC and minimal bactericidal concentration (MBC of enrofloxacin against E. coli (Anhui 112 in Mueller-Hinton (MH broth and intestinal contents were determined to be similar, 0.25μg/mL and 0.5μg/mL respectively. In this study, the sum of concentrations of enrofloxacin and its metabolite (ciprofloxacin was used for the PK/PD integration and modeling. The ex vivo growth inhibition data were fitted to the sigmoid Emax (Hill equation to provide values for intestinal contents of 24h area under concentration–time curve/MIC ratios (AUC0~24h/MIC producing, bacteriostasis (624.94h, bactericidal activity (1065.93h and bacterial eradication (1343.81h. PK/PD modeling was established to

  3. A Mathematical Model of Metabolism and Regulation Provides a Systems-Level View of How Escherichia coli Responds to Oxygen

    Directory of Open Access Journals (Sweden)

    Michael eEderer

    2014-03-01

    Full Text Available The efficient redesign of bacteria for biotechnological purposes, such as biofuel production, waste disposal or specific biocatalytic functions, requires a quantitative systems-level understanding of energy supply, carbon and redox metabolism. The measurement of transcript levels, metabolite concentrations and metabolic fluxes per se gives an incomplete picture. An appreciation of the interdependencies between the different measurement values is essential for systems-level understanding. Mathematical modeling has the potential to provide a coherent and quantitative description of the interplay between gene expression, metabolite concentrations and metabolic fluxes. Escherichia coli undergoes major adaptations in central metabolism when the availability of oxygen changes. Thus, an integrated description of the oxygen response provides a benchmark of our understanding of carbon, energy and redox metabolism. We present the first comprehensive model of the central metabolism of E. coli that describes steady-state metabolism at different levels of oxygen availability. Variables of the model are metabolite concentrations, gene expression levels, transcription factor activities, metabolic fluxes and biomass concentration. We analyze the model with respect to the production capabilities of central metabolism of E. coli. In particular, we predict how precursor and biomass concentration are affected by product formation.

  4. The chicken as a natural model for extraintestinal infections caused by avian pathogenic Escherichia coli (APEC).

    Science.gov (United States)

    Antão, Esther-Maria; Glodde, Susanne; Li, Ganwu; Sharifi, Reza; Homeier, Timo; Laturnus, Claudia; Diehl, Ines; Bethe, Astrid; Philipp, Hans-C; Preisinger, Rudolf; Wieler, Lothar H; Ewers, Christa

    2008-01-01

    E. coli infections in avian species have become an economic threat to the poultry industry worldwide. Several factors have been associated with the virulence of E. coli in avian hosts, but no specific virulence gene has been identified as being entirely responsible for the pathogenicity of avian pathogenic E. coli (APEC). Needless to say, the chicken would serve as the best model organism for unravelling the pathogenic mechanisms of APEC, an extraintestinal pathogen. Five-week-old white leghorn SPF chickens were infected intra-tracheally with a well characterized APEC field strain IMT5155 (O2:K1:H5) using different doses corresponding to the respective models of infection established, that is, the lung colonization model allowing re-isolation of bacteria only from the lung but not from other internal organs, and the systemic infection model. These two models represent the crucial steps in the pathogenesis of APEC infections, including the colonization of the lung epithelium and the spread of bacteria throughout the bloodstream. The read-out system includes a clinical score, pathomorphological changes and bacterial load determination. The lung colonization model has been established and described for the first time in this study, in addition to a comprehensive account of a systemic infection model which enables the study of severe extraintestinal pathogenic E. coli (ExPEC) infections. These in vivo models enable the application of various molecular approaches to study host-pathogen interactions more closely. The most important application of such genetic manipulation techniques is the identification of genes required for extraintestinal virulence, as well as host genes involved in immunity in vivo. The knowledge obtained from these studies serves the dual purpose of shedding light on the nature of virulence itself, as well as providing a route for rational attenuation of the pathogen for vaccine construction, a measure by which extraintestinal infections, including

  5. Modeling the microbial growth of two Escherichia coli strains in a multi-substrate environment

    OpenAIRE

    Poccia,M. E.; Beccaria, A. J.; R. G. Dondo

    2014-01-01

    The microbial growth in multi-substrate environments may be viewed as an optimal resources allocation problem. The optimization aims at maximizing some biological objective like the biomass growth. The models developed using this hypothesis are called “cybernetic” and they represent the complex cell structure as an optimizing function that regulates the intracellular enzymatic machinery. In this work, a cybernetic model was developed to represent the growth of two E. coli strains (JM 109 and ...

  6. EI of the Phosphotransferase System of Escherichia coli: Mathematical Modeling Approach to Analysis of Its Kinetic Properties

    Directory of Open Access Journals (Sweden)

    T. A. Karelina

    2011-01-01

    Full Text Available The mathematical model of the operation of the first enzyme of the Escherichia coli phosphotransferase system, EI, is proposed. Parameters of the kinetic model describing the operation of EI under different conditions are identified on the basis of a large amount of known experimental data. The verified model is employed to predict modes of operation of EI under both in vivo physiological conditions and in vitro nonphysiological conditions. The model predicts that under in vivo physiological conditions, the rate of phosphotransfer from EI to the second protein of the phosphotransferase system HPr by the dimer is much higher than by the monomer. A hypothesis is proposed on the basis of calculations that the transfer by a monomer plays a role in the regulation of chemotaxis. At submicromolar pyruvate concentration, the model predicts nonmonotonic dependence of the phosphotransfer rate on the substrate (PEP concentration.

  7. Modeling the Inactivation of Intestinal Pathogenic Escherichia coli O157:H7 and Uropathogenic E. coli in Ground Chicken by High Pressure Processing and Thymol.

    Science.gov (United States)

    Chien, Shih-Yung; Sheen, Shiowshuh; Sommers, Christopher H; Sheen, Lee-Yan

    2016-01-01

    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 chicken meat using High Pressure Processing (HPP) in with (the hurdle concept) and without thymol essential oil as a sensitizer. UPEC was found slightly more resistant than E. coli O157:H7 (iPEC O157:H7) at 450 and 500 MPa. A central composite experimental design was used to evaluate the effect of pressure (300-400 MPa), thymol concentration (100-200 ppm), and pressure-holding time (10-20 min) on the inactivation of iPEC O157:H7 and UPEC in ground chicken. The hurdle approach reduced the high pressure levels and thymol doses imposed on the food matrices and potentially decreased food quality damaged after treatment. The quadratic equations were developed to predict the impact (lethality) on iPEC O157:H7 (R (2) = 0.94) and UPEC (R (2) = 0.98), as well as dimensionless non-linear models [Pr > F (<0.0001)]. Both linear and non-linear models were validated with data obtained from separated experiment points. All models may predict the inactivation/lethality within the same order of accuracy. However, the dimensionless non-linear models showed potential applications with parameters outside the central composite design ranges. The results provide useful information of both iPEC O157:H7 and UPEC in regard to how they may survive HPP in the presence or absence of thymol. The models may further assist regulatory agencies and food industry to assess the potential risk of iPEC O157:H7 and UPEC in ground chicken.

  8. Draft genome sequences of three Escherichia coli strains with different In Vivo pathogenicities in an avian (Ascending) infection model of the oviduct

    DEFF Research Database (Denmark)

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

    2015-01-01

    Here, we present three draft genome sequences of Escherichia coli strains that experimentally were proven to possess low (strain D2-2), intermediate (Chronic_salp), or high virulence (Cp6salp3) in an avian (ascending) infection model of the oviduct.......Here, we present three draft genome sequences of Escherichia coli strains that experimentally were proven to possess low (strain D2-2), intermediate (Chronic_salp), or high virulence (Cp6salp3) in an avian (ascending) infection model of the oviduct....

  9. A comparative kinetic and thermodynamic perspective of the σ-competition model in Escherichia coli.

    Science.gov (United States)

    Ganguly, Abantika; Chatterji, Dipankar

    2012-09-19

    Transcription is the most fundamental step in gene expression in any living organism. Various environmental cues help in the maturation of core RNA polymerase (RNAP; α(2)ββ'ω) with different σ-factors, leading to the directed recruitment of RNAP to different promoter DNA sequences. Thus it is essential to determine the σ-factors that affect the preferential partitioning of core RNAP among various σ-actors, and the role of σ-switching in transcriptional gene regulation. Further, the macromolecular assembly of holo RNAP takes place in an extremely crowded environment within a cell, and thus far the kinetics and thermodynamics of this molecular recognition process have not been well addressed. In this study we used a site-directed bioaffinity immobilization method to evaluate the relative binding affinities of three different Escherichia coli σ-factors to the same core RNAP with variations in temperature and ionic strength while emulating the crowded cellular milieu. Our data indicate that the interaction of core RNAP-σ is susceptible to changes in external stimuli such as osmolytic and thermal stress, and the degree of susceptibility varies among different σ-factors. This allows for a reversible σ-switching from housekeeping factors to alternate σ-factors when the organism senses a change in its physiological conditions.

  10. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Schembri, Mark; Kjærgaard, K.; Klemm, Per

    2003-01-01

    in expression have no current defined function. These genes, as well as those induced by stresses relevant to biofilm growth such as oxygen and nutrient limitation, may be important factors that trigger enhanced resistance mechanisms of sessile communities to antibiotics and hydrodynamic shear forces.......It is now apparent that microorganisms undergo significant changes during the transition from planktonic to biofilm growth. These changes result in phenotypic adaptations that allow the formation of highly organized and structured sessile communities, which possess enhanced resistance...... to antimicrobial treatments and host immune defence responses. Escherichia coli has been used as a model organism to study the mechanisms of growth within adhered communities. In this study, we use DNA microarray technology to examine the global gene expression profile of E. coli during sessile growth compared...

  11. Reconstruction and Use of Microbial Metabolic Networks: the Core Escherichia coli Metabolic Model as an Educational Guide.

    Science.gov (United States)

    Orth, Jeffrey D; Fleming, R M T; Palsson, Bernhard Ø

    2010-09-01

    Biochemical network reconstructions have become popular tools in systems biology. Metabolicnetwork reconstructions are biochemically, genetically, and genomically (BiGG) structured databases of biochemical reactions and metabolites. They contain information such as exact reaction stoichiometry, reaction reversibility, and the relationships between genes, proteins, and reactions. Network reconstructions have been used extensively to study the phenotypic behavior of wild-type and mutant stains under a variety of conditions, linking genotypes with phenotypes. Such phenotypic simulations have allowed for the prediction of growth after genetic manipulations, prediction of growth phenotypes after adaptive evolution, and prediction of essential genes. Additionally, because network reconstructions are organism specific, they can be used to understand differences between organisms of species in a functional context.There are different types of reconstructions representing various types of biological networks (metabolic, regulatory, transcription/translation). This chapter serves as an introduction to metabolic and regulatory network reconstructions and models and gives a complete description of the core Escherichia coli metabolic model. This model can be analyzed in any computational format (such as MATLAB or Mathematica) based on the information given in this chapter. The core E. coli model is a small-scale model that can be used for educational purposes. It is meant to be used by senior undergraduate and first-year graduate students learning about constraint-based modeling and systems biology. This model has enough reactions and pathways to enable interesting and insightful calculations, but it is also simple enough that the results of such calculations can be understoodeasily.

  12. {sup 99m}Technetium labelled Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, S.O.F.; Cardoso, V.N. [Radioisotope Laboratory, Faculty of Pharmacy/UFMG, Belo Horizonte (Brazil); Resende, B.M.; Nunan, E.A. [Biological Control Laboratory, Faculty of Pharmacy/UFMG, Belo Horizonte (Brazil); Simal, C.J.R. [Laboratory Nuclear Medicine, Faculty of Medicine/UFMG, Belo Horizonte (Brazil)

    1999-07-01

    Samples of a culture of unlabeled Escherichia coli were incubated with different concentrations of stannous chloride for various time periods. {sup 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 {sup 99m}Tc-E. coli and E. coli did not show any statistical differences, these results demonstrate that labelling of E. coli with {sup 99m}Tc does not modify the bacterial viability, and the radiolabelled bacteria may be a good model to study bacterial translocation.

  13. Genes under positive selection in Escherichia coli

    DEFF Research Database (Denmark)

    Petersen, Lise; Bollback, J.P.; Dimmic, Matt

    2007-01-01

    We used a comparative genomics approach to identify genes that are under positive selection in six strains of Escherichia coli and Shigella flexneri, including five strains that are human pathogens. We find that positive selection targets a wide range of different functions in the E. coli genome...

  14. 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.

  15. 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...

  16. 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...

  17. Genes under positive selection in Escherichia coli

    DEFF Research Database (Denmark)

    Petersen, Lise; Bollback, J.P.; Dimmic, Matt

    2007-01-01

    We used a comparative genomics approach to identify genes that are under positive selection in six strains of Escherichia coli and Shigella flexneri, including five strains that are human pathogens. We find that positive selection targets a wide range of different functions in the E. coli genome...

  18. Prevalence of Escherichia coli O157

    NARCIS (Netherlands)

    Abdissa, Rosa; Haile, Woynshet; Fite, Akafete Teklu; Beyi, Ashenafi Feyisa; Agga, Getahun E.; Edao, Bedaso Mammo; Tadesse, Fanos; Korsa, Mesula Geloye; Beyene, Takele; Beyene, Tariku Jibat; Zutter, De Lieven; Cox, Eric; Goddeeris, Bruno Maria

    2017-01-01

    Background: There is paucity of information regarding the epidemiology of Escherichia coli O157: H7 in developing countries. In this study, we investigated the occurrence of E. coli O157: H7 associated with beef cattle at processing plants and at retail shops in Ethiopia. Methods: Various samples

  19. 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...

  20. 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…

  1. 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.

  2. 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.

  3. Escherichia coli removal from model substrates: Underlying mechanism based on nanofluid structural forces.

    Science.gov (United States)

    Shim, Jiyoung; Nikolov, Alex; Wasan, Darsh

    2017-07-15

    Understanding the interactions between bacteria and solid surfaces that result in bacterial adhesion and removal is of immense importance for reducing foodborne illness outbreaks. A nanofluid formulation comprised of a sodium dodecyl sulfate (SDS) micellar aqueous solution in the presence of an organic acid (as a pH controller) was used to test the E. coli K12 removal from two substrates, polyvinylchloride (PVC) and partially hydrophobic glass. We investigated the bacterial removal efficacy based on the combined effect of the nanofluid's structural forces and bacterial isoelectric point. To quantify the bacteria-PVC coverage, we used fluorescence microscope. The Langmuir isotherm at the low volume fraction was applied to estimate the adsorption energy of E. coli K12. We obtained a value of about 2.5±0.2kT. This value compared favorably with the value of 2.1kT reported previously for E. coli NCTC 9002 (Vanloosdrecht et al., 1989). We applied the dynamic light scattering method to estimate the radius of the gyration of E. coli K12. The radius of the gyration was used to estimate the limit of surface area covered by the bacterium and compared it to the surface area measured from the image taken with fluorescence microscope. We found that they are in good agreement with each other. We modeled the nanofluid oscillatory structural energy against the E. coli K12 adsorption energy by applying the statistical mechanics approach. Based on the model prediction, the oscillatory interaction energy was estimated at the vertex between a bacterium and the substrate (i.e., the wedge film's interaction energy at one particle layer). The evaluated film's repulsive energy due to the oscillatory structural forces (OSF) was about 15.6±4.4kT of the 0.02M SMNF (the SDS micellar nanofluid formulation) and several times higher than the bacterial adsorption energy, 2.5±0.2kT. The OSF of the 0.06M SMNF was measured by AFM (the oscillatory decay force curve). The period and number of

  4. Metabolic deficiences revealed in the biotechnologically important model bacterium Escherichia coli BL21(DE3.

    Directory of Open Access Journals (Sweden)

    Constanze Pinske

    Full Text Available The Escherichia coli B strain BL21(DE3 has had a profound impact on biotechnology through its use in the production of recombinant proteins. Little is understood, however, regarding the physiology of this important E. coli strain. We show here that BL21(DE3 totally lacks activity of the four [NiFe]-hydrogenases, the three molybdenum- and selenium-containing formate dehydrogenases and molybdenum-dependent nitrate reductase. Nevertheless, all of the structural genes necessary for the synthesis of the respective anaerobic metalloenzymes are present in the genome. However, the genes encoding the high-affinity molybdate transport system and the molybdenum-responsive transcriptional regulator ModE are absent from the genome. Moreover, BL21(DE3 has a nonsense mutation in the gene encoding the global oxygen-responsive transcriptional regulator FNR. The activities of the two hydrogen-oxidizing hydrogenases, therefore, could be restored to BL21(DE3 by supplementing the growth medium with high concentrations of Ni²⁺ (Ni²⁺-transport is FNR-dependent or by introducing a wild-type copy of the fnr gene. Only combined addition of plasmid-encoded fnr and high concentrations of MoO₄²⁻ ions could restore hydrogen production to BL21(DE3; however, to only 25-30% of a K-12 wildtype. We could show that limited hydrogen production from the enzyme complex responsible for formate-dependent hydrogen evolution was due solely to reduced activity of the formate dehydrogenase (FDH-H, not the hydrogenase component. The activity of the FNR-dependent formate dehydrogenase, FDH-N, could not be restored, even when the fnr gene and MoO₄²⁻ were supplied; however, nitrate reductase activity could be recovered by combined addition of MoO₄²⁻ and the fnr gene. This suggested that a further component specific for biosynthesis or activity of formate dehydrogenases H and N was missing. Re-introduction of the gene encoding ModE could only partially restore the

  5. Constraint-based modeling of heterologous pathways: application and experimental demonstration for overproduction of fatty acids in Escherichia coli.

    Science.gov (United States)

    Ip, Kuhn; Donoghue, Neil; Kim, Min Kyung; Lun, Desmond S

    2014-10-01

    Constraint-based modeling has been shown, in many instances, to be useful for metabolic engineering by allowing the prediction of the metabolic phenotype resulting from genetic manipulations. But the basic premise of constraint-based modeling-that of applying constraints to preclude certain behaviors-only makes sense for certain genetic manipulations (such as knockouts and knockdowns). In particular, when genes (such as those associated with a heterologous pathway) are introduced under artificial control, it is unclear how to predict the correct behavior. In this paper, we introduce a modeling method that we call proportional flux forcing (PFF) to model artificially induced enzymatic genes. The model modifications introduced by PFF can be transformed into a set of simple mass balance constraints, which allows computational methods for strain optimization based on flux balance analysis (FBA) to be utilized. We applied PFF to the metabolic engineering of Escherichia coli (E. coli) for free fatty acid (FFA) production-a metabolic engineering problem that has attracted significant attention because FFAs are a precursor to liquid transportation fuels such as biodiesel and biogasoline. We show that PFF used in conjunction with FBA-based computational strain optimization methods can yield non-obvious genetic manipulation strategies that significantly increase FFA production in E. coli. The two mutant strains constructed and successfully tested in this work had peak fatty acid (FA) yields of 0.050 g FA/g carbon source (17.4% theoretical yield) and 0.035 g FA/g carbon source (12.3% theoretical yield) when they were grown using a mixed carbon source of glucose and casamino acids in a ratio of 2-to-1. These yields represent increases of 5.4- and 3.8-fold, respectively, over the baseline strain.

  6. 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...

  7. Virulence of Escherichia coli B2 Isolates from Meat and Animals in a Murine Model of Ascending Urinary Tract Infection (UTI): Evidence that UTI Is a Zoonosis ▿

    Science.gov (United States)

    Jakobsen, Lotte; Hammerum, Anette M.; Frimodt-Møller, Niels

    2010-01-01

    In vivo evidence of a connection between urinary tract infections (UTI) and foods is lacking. The virulence of 13 Escherichia coli B2 isolates from healthy animals and fresh meat was investigated in a murine model of ascending UTI. All isolates produced positive bladder cultures (102 to 107 CFU), and nine isolates produced positive kidney cultures (102 to 105 CFU). PMID:20519476

  8. Inactivation and sublethal injury of Escherichia coli and Listeria innocua by high hydrostatic pressure in model suspensions and beetroot juice

    Science.gov (United States)

    Sokołowska, Barbara; Skąpska, Sylwia; Niezgoda, Jolanta; Rutkowska, Małgorzata; Dekowska, Agnieszka; Rzoska, Sylwester J.

    2014-01-01

    Cells exposed to different physical and chemical treatments, including high hydrostatic pressure (HHP), suffer from injuries that could be reversible in food materials when stored. Escherichia coli and Listeria innocua cells suspended in phosphate-buffered saline (PBS) (model suspensions), and acidified beetroot juice were subjected to a pressure of 400 MPa at a temperature of 20°C for up to 10 min. The difference between the viable and non-injured cells was used to estimate the number of injured survivors. The reduction in E. coli cell number was 3.4-4.1 log after 10 min pressurization in model suspensions and 6.2 log in beetroot juice. Sublethally injured cells in PBS accounted for up to 2.7 log after 10 min HHP treatment and 0.8 log in beetroot juice. The reduction in L. innocua cell number after 10 min pressure treatment reached from 3.8 to 4.8 log, depending on the initial concentration in model suspensions. Among the surviving L. innocua cells, even up to 100% were injured. L. innocua cells were completely inactivated after 1 min HHP treatment in beetroot juice.

  9. Application of a dual deposition mode model to evaluate transport of Escherichia coli D21 in porous media

    Science.gov (United States)

    Tufenkji, Nathalie

    2006-12-01

    Controlled laboratory-scale column deposition experiments were conducted using a well-characterized mutant of the Escherichia coli (E. coli) K12 strain to obtain insight into the mechanisms that give rise to the observed deviation from classical colloid filtration theory (CFT). Both the suspended effluent bacteria concentration and the spatial distribution of retained bacteria were systematically measured over a wide range of solution conditions using columns packed with spherical glass beads. Calculations of Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies based on measured cell zeta potentials indicated that the bacteria should experience considerable repulsive interaction forces when approaching the glass bead surface. In spite of these predictions, bacterial adhesion was observed even at the lowest solution ionic strength investigated (3 mM) and increased with solution salt concentration. Comparison of these results with measurements obtained using model colloidal particles (polystyrene latex microspheres) and a different microbe (Cryptosporidium parvum) suggested that another non-DLVO-type interaction may be contributing to the observed deposition behavior. Furthermore, predictions based on a discrete dual deposition mode (DDM) model disagreed with measured fractions of released cells. Taken together, the experimental and modeling results suggest that the deposition behavior of bacteria in saturated porous media is influenced by additional interaction mechanism(s) or factors not considered in classical DLVO theory, such as local charge heterogeneities of the cell membrane and surface biomolecule-specific interactions.

  10. Model Uracil-Rich RNAs and Membrane Protein mRNAs Interact Specifically with Cold Shock Proteins in Escherichia coli.

    Science.gov (United States)

    Benhalevy, Daniel; Bochkareva, Elena S; Biran, Ido; Bibi, Eitan

    2015-01-01

    Are integral membrane protein-encoding mRNAs (MPRs) different from other mRNAs such as those encoding cytosolic mRNAs (CPRs)? This is implied from the emerging concept that MPRs are specifically recognized and delivered to membrane-bound ribosomes in a translation-independent manner. MPRs might be recognized through uracil-rich segments that encode hydrophobic transmembrane helices. To investigate this hypothesis, we designed DNA sequences encoding model untranslatable transcripts that mimic MPRs or CPRs. By utilizing in vitro-synthesized biotinylated RNAs mixed with Escherichia coli extracts, we identified a highly specific interaction that takes place between transcripts that mimic MPRs and the cold shock proteins CspE and CspC, which are normally expressed under physiological conditions. Co-purification studies with E. coli expressing 6His-tagged CspE or CspC confirmed that the specific interaction occurs in vivo not only with the model uracil-rich untranslatable transcripts but also with endogenous MPRs. Our results suggest that the evolutionarily conserved cold shock proteins may have a role, possibly as promiscuous chaperons, in the biogenesis of MPRs.

  11. Ecology and modelling of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in cattle manure and soil

    NARCIS (Netherlands)

    Semenov, A.V.

    2008-01-01

    The number of food poisoning cases caused by enteropathogens has increased in recent years. A significant part of the outbreaks associated with the consumption of raw vegetables has been attributed to Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium. Bovine manure

  12. Hybrid dynamic modeling of Escherichia coli central metabolic network combining Michaelis-Menten and approximate kinetic equations.

    Science.gov (United States)

    Costa, Rafael S; Machado, Daniel; Rocha, Isabel; Ferreira, Eugénio C

    2010-05-01

    The construction of dynamic metabolic models at reaction network level requires the use of mechanistic enzymatic rate equations that comprise a large number of parameters. The lack of knowledge on these equations and the difficulty in the experimental identification of their associated parameters, represent nowadays the limiting factor in the construction of such models. In this study, we compare four alternative modeling approaches based on Michaelis-Menten kinetics for the bi-molecular reactions and different types of simplified rate equations for the remaining reactions (generalized mass action, convenience kinetics, lin-log and power-law). Using the mechanistic model for Escherichia coli central carbon metabolism as a benchmark, we investigate the alternative modeling approaches through comparative simulations analyses. The good dynamic behavior and the powerful predictive capabilities obtained using the hybrid model composed of Michaelis-Menten and the approximate lin-log kinetics indicate that this is a possible suitable approach to model complex large-scale networks where the exact rate laws are unknown. 2010 Elsevier Ireland Ltd. All rights reserved.

  13. Succinate overproduction: A case study of computational strain design using a comprehensive Escherichia coli kinetic model

    Directory of Open Access Journals (Sweden)

    Ali eKhodayari

    2015-01-01

    Full Text Available Computational strain design prediction accuracy has been the focus for many recent efforts through the selective integration of kinetic information into metabolic models. In general, kinetic model prediction quality is determined by the range and scope of genetic and/or environmental perturbations used during parameterization. In this effort, we apply the k-OptForce procedure on a kinetic model of E. coli core metabolism constructed using the Ensemble Modeling (EM method and parameterized using multiple mutant strains data under aerobic respiration with glucose as the carbon source. Minimal interventions are identified that improve succinate yield under both aerobic and anaerobic conditions to test the fidelity of model predictions under both genetic and environmental perturbations. Under aerobic condition, k-OptForce identifies interventions that match existing experimental strategies pointing at a number of unexplored flux redirections such as routing glyoxylate flux through the glycerate metabolism to improve succinate yield. Many of the identified interventions rely on the kinetic descriptions and would not be discoverable by a purely stoichiometric description. In contrast, under fermentative (anaerobic conditions, k-OptForce fails to identify key interventions including up-regulation of anaplerotic reactions and elimination of competitive fermentative products. This is due to the fact that the pathways activated under anaerobic conditions were not properly parameterized as only aerobic flux data were used in the model construction. This study shed light on the importance of condition-specific model parameterization and provides insight onto how to augment kinetic models so as to correctly respond to multiple environmental perturbations.

  14. Succinate Overproduction: A Case Study of Computational Strain Design Using a Comprehensive Escherichia coli Kinetic Model.

    Science.gov (United States)

    Khodayari, Ali; Chowdhury, Anupam; Maranas, Costas D

    2014-01-01

    Computational strain-design prediction accuracy has been the focus for many recent efforts through the selective integration of kinetic information into metabolic models. In general, kinetic model prediction quality is determined by the range and scope of genetic and/or environmental perturbations used during parameterization. In this effort, we apply the k-OptForce procedure on a kinetic model of E. coli core metabolism constructed using the Ensemble Modeling (EM) method and parameterized using multiple mutant strains data under aerobic respiration with glucose as the carbon source. Minimal interventions are identified that improve succinate yield under both aerobic and anaerobic conditions to test the fidelity of model predictions under both genetic and environmental perturbations. Under aerobic condition, k-OptForce identifies interventions that match existing experimental strategies while pointing at a number of unexplored flux re-directions such as routing glyoxylate flux through the glycerate metabolism to improve succinate yield. Many of the identified interventions rely on the kinetic descriptions that would not be discoverable by a purely stoichiometric description. In contrast, under fermentative (anaerobic) condition, k-OptForce fails to identify key interventions including up-regulation of anaplerotic reactions and elimination of competitive fermentative products. This is due to the fact that the pathways activated under anaerobic condition were not properly parameterized as only aerobic flux data were used in the model construction. This study shed light on the importance of condition-specific model parameterization and provides insight on how to augment kinetic models so as to correctly respond to multiple environmental perturbations.

  15. Analysis of L-glutamic acid fermentation by using a dynamic metabolic simulation model of Escherichia coli.

    Science.gov (United States)

    Nishio, Yousuke; Ogishima, Soichi; Ichikawa, Masao; Yamada, Yohei; Usuda, Yoshihiro; Masuda, Tadashi; Tanaka, Hiroshi

    2013-09-22

    Understanding the process of amino acid fermentation as a comprehensive system is a challenging task. Previously, we developed a literature-based dynamic simulation model, which included transcriptional regulation, transcription, translation, and enzymatic reactions related to glycolysis, the pentose phosphate pathway, the tricarboxylic acid (TCA) cycle, and the anaplerotic pathway of Escherichia coli. During simulation, cell growth was defined such as to reproduce the experimental cell growth profile of fed-batch cultivation in jar fermenters. However, to confirm the biological appropriateness of our model, sensitivity analysis and experimental validation were required. We constructed an L-glutamic acid fermentation simulation model by removing sucAB, a gene encoding α-ketoglutarate dehydrogenase. We then performed systematic sensitivity analysis for L-glutamic acid production; the results of this process corresponded with previous experimental data regarding L-glutamic acid fermentation. Furthermore, it allowed us to predicted the possibility that accumulation of 3-phosphoglycerate in the cell would regulate the carbon flux into the TCA cycle and lead to an increase in the yield of L-glutamic acid via fermentation. We validated this hypothesis through a fermentation experiment involving a model L-glutamic acid-production strain, E. coli MG1655 ΔsucA in which the phosphoglycerate kinase gene had been amplified to cause accumulation of 3-phosphoglycerate. The observed increase in L-glutamic acid production verified the biologically meaningful predictive power of our dynamic metabolic simulation model. In this study, dynamic simulation using a literature-based model was shown to be useful for elucidating the precise mechanisms involved in fermentation processes inside the cell. Further exhaustive sensitivity analysis will facilitate identification of novel factors involved in the metabolic regulation of amino acid fermentation.

  16. A pathoadaptive deletion in an enteroaggregative Escherichia coli outbreak strain enhances virulence in a Caenorhabditis elegans model.

    Science.gov (United States)

    Hwang, Jennifer; Mattei, Lisa M; VanArendonk, Laura G; Meneely, Philip M; Okeke, Iruka N

    2010-09-01

    Enteroaggregative Escherichia coli (EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulent E. coli subtypes of Shigella and enterohemorrhagic E. coli. To test the hypothesis that cad deletions might account for heterogeneity in EAEC virulence, we developed a Caenorhabditis elegans pathogenesis model. Well-characterized EAEC strains were shown to colonize and kill C. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysine in vitro due to deletions in cadA and cadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of the cadAB genes. Strain 101-1 was significantly more lethal to C. elegans than control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion of cad genes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.

  17. Modeling of Combined Processing Steps for Reducing Escherichia coli O157:H7 Populations in Apple Cider

    Science.gov (United States)

    Uljas, Heidi E.; Schaffner, Donald W.; Duffy, Siobain; Zhao, Lihui; Ingham, Steven C.

    2001-01-01

    Probabilistic models were used as a systematic approach to describe the response of Escherichia coli O157:H7 populations to combinations of commonly used preservation methods in unpasteurized apple cider. Using a complete factorial experimental design, the effect of pH (3.1 to 4.3), storage temperature and time (5 to 35°C for 0 to 6 h or 12 h), preservatives (0, 0.05, or 0.1% potassium sorbate or sodium benzoate), and freeze-thaw (F-T; −20°C, 48 h and 4°C, 4 h) treatment combinations (a total of 1,600 treatments) on the probability of achieving a 5-log10-unit reduction in a three-strain E. coli O157:H7 mixture in cider was determined. Using logistic regression techniques, pH, temperature, time, and concentration were modeled in separate segments of the data set, resulting in prediction equations for: (i) no preservatives, before F-T; (ii) no preservatives, after F-T; (iii) sorbate, before F-T; (iv) sorbate, after F-T; (v) benzoate, before F-T; and (vi) benzoate, after F-T. Statistical analysis revealed a highly significant (P cider pH being the most important, followed by temperature and time, and finally by preservative concentration. All models predicted 92 to 99% of the responses correctly. To ensure safety, use of the models is most appropriate at a 0.9 probability level, where the percentage of false positives, i.e., falsely predicting a 5-log10-unit reduction, is the lowest (0 to 4.4%). The present study demonstrates the applicability of logistic regression approaches to describing the effectiveness of multiple treatment combinations in pathogen control in cider making. The resulting models can serve as valuable tools in designing safe apple cider processes. PMID:11133437

  18. Modelo matemático predictivo del crecimiento de Escherichia coli O157 en carne vacuna Mathematical model to predict the growth of Escherichia coli O157 in beef

    Directory of Open Access Journals (Sweden)

    M.L Signorini

    2008-06-01

    Full Text Available El objetivo del estudio fue modelar el crecimiento microbiano de Escherichia coli O157 en carne vacuna (hamburguesas como parte de una evaluación cuantitativa de riesgos. Se seleccionaron artículos científicos que exponían de manera completa modelos predictivos de crecimiento del patógeno en carne en función de la temperatura y dos modelos predictivos terciarios. A partir de éstos se generaron datos sobre el tiempo de latencia (ë y tasa de crecimiento (μ en un rango de temperaturas (5°C a 34°C y pH (5,6 - 6,5, obteniéndose la relación lineal entre cada parámetro y temperatura. Se incluyeron las ecuaciones lineales en distribuciones de probabilidad para cada parámetro y se corrió un modelo para analizar el comportamiento de las ecuaciones lag-exponencial y Gompertz en la predicción del crecimiento de E. coli O157. La metodología expuesta permite incluir diferentes condiciones ambientales presentes en la carne a lo largo del proceso, considerando la variabilidad y las incertidumbres de los parámetros que caracterizan el crecimiento microbiano. Gompertz fue el modelo microbiológico que mejores resultados generó, ya que al considerar la concentración de bacterias que alcanzan la fase estacionaria de crecimiento, evita obtener valores extremadamente elevados.The aim of this study was modeled Escherichia coli O157 growth in beef hamburger as part of a quantitative risk assessment. Scientific articles that presented a complete pathogen growth model in meat depending on the temperature and two tertiary predictive models were selected. Since they were generated data of lag phase (ë and growth rate (μ in a range of temperatures (5 ° C to 34 ° C and pH (5.6 - 6.5, and were obtained the linear relationship between each parameter and temperature. Linear equations in probability distributions for each parameter were included and ran a model for analyzing the behavior of lag-exponential and Gompertz equations in predicting E. coli O

  19. Native valve Escherichia coli endocarditis following urosepsis.

    Science.gov (United States)

    Rangarajan, D; Ramakrishnan, S; Patro, K C; Devaraj, S; Krishnamurthy, V; Kothari, Y; Satyaki, N

    2013-05-01

    Gram-negative organisms are a rare cause of infective endocarditis. Escherichia coli, the most common cause of urinary tract infection and gram-negative septicemia involves endocardium rarely. In this case report, we describe infection of native mitral valve by E. coli following septicemia of urinary tract origin in a diabetic male; subsequently, he required prosthetic tissue valve replacement indicated by persistent sepsis and congestive cardiac failure.

  20. A model for the Escherichia coli FtsB/FtsL/FtsQ cell division complex

    Directory of Open Access Journals (Sweden)

    Lagos Rosalba

    2011-06-01

    Full Text Available Abstract Background Bacterial division is produced by the formation of a macromolecular complex in the middle of the cell, called the divisome, formed by more than 10 proteins. This process can be divided into two steps, in which the first is the polymerization of FtsZ to form the Z ring in the cytoplasm, and then the sequential addition of FtsA/ZipA to anchor the ring at the cytoplasmic membrane, a stage completed by FtsEX and FtsK. In the second step, the formation of the peptidoglycan synthesis machinery in the periplasm takes place, followed by cell division. The proteins involved in connecting both steps in cell division are FtsQ, FtsB and FtsL, and their interaction is a crucial and conserved event in the division of different bacteria. These components are small bitopic membrane proteins, and their specific function seems to be mainly structural. The purpose of this study was to obtain a structural model of the periplasmic part of the FtsB/FtsL/FtsQ complex, using bioinformatics tools and experimental data reported in the literature. Results Two oligomeric models for the periplasmic region of the FtsB/FtsL/FtsQ E. coli complex were obtained from bioinformatics analysis. The FtsB/FtsL subcomplex was modelled as a coiled-coil based on sequence information and several stoichiometric possibilities. The crystallographic structure of FtsQ was added to this complex, through protein-protein docking. Two final structurally-stable models, one trimeric and one hexameric, were obtained. The nature of the protein-protein contacts was energetically favourable in both models and the overall structures were in agreement with the experimental evidence reported. Conclusions The two models obtained for the FtsB/FtsL/FtsQ complex were stable and thus compatible with the in vivo periplasmic complex structure. Although the hexameric model 2:2:2 has features that indicate that this is the most plausible structure, the ternary complex 1:1:1 cannot be discarded

  1. Different responses to nitrate and nitrite by the model organism Escherichia coli and the human pathogen Neisseria gonorrhoeae.

    Science.gov (United States)

    Whitehead, R N; Cole, J A

    2006-02-01

    The ability of Escherichia coli to use both nitrate and nitrite as terminal electron acceptors during anaerobic growth is mediated by the dual-acting two-component regulatory systems NarX-NarL and NarQ-NarP. In contrast, Neisseria gonorrhoeae responds only to nitrite: it expresses only NarQ-NarP. We have shown that although N. gonorrhoeae NarQ can phosphorylate E. coli NarL and NarP, the N. gonorrhoeae NarP is unable to regulate gene expression in E. coli. Mutagenesis experiments have revealed residues in E. coli NarQ that are essential for nitrate and nitrite sensing. Chimaeric proteins revealed domains of NarQ that are important for ligand sensing.

  2. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Science.gov (United States)

    2012-02-21

    ... Food Safety and Inspection Service Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products... manufacturing trimmings for six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45..., non-intact product, that are contaminated with Shiga toxin-producing Escherichia coli (STEC) O26,...

  3. Independence of replisomes in Escherichia coli chromosomalreplication

    Energy Technology Data Exchange (ETDEWEB)

    Breier, Adam M.; Weier, Heinz-Ulrich G.; Cozzarelli, Nicholas R.

    2005-03-13

    In Escherichia coli DNA replication is carried out by the coordinated action of the proteins within a replisome. After replication initiation, the two bidirectionally oriented replisomes from a single origin are colocalized into higher-order structures termed replication factories. The factory model postulated that the two replisomes are also functionally coupled. We tested this hypothesis by using DNA combing and whole-genome microarrays. Nascent DNA surrounding oriC in single, combed chromosomes showed instead that one replisome, usually the leftward one, was significantly ahead of the other 70% of the time. We next used microarrays to follow replication throughout the genome by measuring DNA copy number. We found in multiple E. coli strains that the replisomes are independent, with the leftward replisome ahead of the rightward one. The size of the bias was strain-specific, varying from 50 to 130 kb in the array results. When we artificially blocked one replisome, the other continued unabated, again demonstrating independence. We suggest an improved version of the factory model that retains the advantages of threading DNA through colocalized replisomes at about equal rates, but allows the cell flexibility to overcome obstacles encountered during elongation.

  4. Control of Ribosome Synthesis in Escherichia coli

    DEFF Research Database (Denmark)

    Molin, Søren; Meyenburg, K. von; Måløe, O.

    1977-01-01

    The rate of ribosome synthesis and accumulation in Escherichia coli during the transition after an energy source shift-down was analyzed. The shift was imposed on cultures of stringent and relaxed strains growing in glucose minimal medium by the addition of the glucose analogue {alpha}-methylgluc...

  5. Escherichia Coli--Key to Modern Genetics.

    Science.gov (United States)

    Bregegere, Francois

    1982-01-01

    Mid-nineteenth century work by Mendel on plant hybrids and by Pasteur on fermentation gave birth by way of bacterial genetics to modern-day molecular biology. The bacterium Escherichia Coli has occupied a key position in genetic studies leading from early gene identification with DNA to current genetic engineering using recombinant DNA technology.…

  6. Progressive segregation of the Escherichia coli chromosome

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck; Youngren, Brenda; Hansen, Flemming G.

    2006-01-01

    We have followed the fate of 14 different loci around the Escherichia coli chromosome in living cells at slow growth rate using a highly efficient labelling system and automated measurements. Loci are segregated as they are replicated, but with a marked delay. Most markers segregate in a smooth...

  7. Leaner and meaner genomes in Escherichia coli

    DEFF Research Database (Denmark)

    Ussery, David

    2006-01-01

    A 'better' Escherichia coli K-12 genome has recently been engineered in which about 15% of the genome has been removed by planned deletions. Comparison with related bacterial genomes that have undergone a natural reduction in size suggests that there is plenty of scope for yet more deletions....

  8. Compaction of isolated Escherichia coli nucleoids

    NARCIS (Netherlands)

    Wegner, Anna S.; Wintraecken, Kathelijne; Spurio, Roberto; Woldringh, Conrad L.; Vries, de Renko; Odijk, Theo

    2016-01-01

    Escherichia coli nucleoids were compacted by the inert polymer polyethylene glycol (PEG) in the presence of the H-NS protein. The protein by itself appears to have little impact on the size of the nucleoids as determined by fluorescent microscopy. However, it has a significant impact on the nucle

  9. Host Response to Porcine Strains of Escherichia coli in a Novel Pyelonephritis Model

    DEFF Research Database (Denmark)

    Isling, L. K.; Aalbæk, B.; Birck, M. M.;

    2011-01-01

    . coli strain LK67 (P fimbriae PapGI), LK76 (type 1 fimbriae) or LK82 (type 1 fimbriae and P fimbriae PapGII/III), respectively. The contralateral kidneys were inoculated with saline and served as controls. Pigs were killed 6h post-inoculation (hpi). Differential leucocyte counts, serum biochemical...... kidneys. Gross and microscopical lesions of acute pyelonephritis were demonstrated in all but one kidney inoculated with E. coli, but in none of the control kidneys. Renal parenchymal infiltration with both neutrophils and mononuclear cells, primarily CD3+ T lymphocytes, was observed at 6hpi. Most T...... lymphocytes were CD8+. Pigs in group C had the highest mean pathology scores. Neutrophils were the dominant renal leucocyte in this group, while the number of mononuclear cells was at least equal to the number of neutrophils in the lesions of pigs from groups A and B. Kidneys with a high number of E. coli had...

  10. The extracellular RNA complement of Escherichia coli.

    Science.gov (United States)

    Ghosal, Anubrata; Upadhyaya, Bimal Babu; Fritz, Joëlle V; Heintz-Buschart, Anna; Desai, Mahesh S; Yusuf, Dilmurat; Huang, David; Baumuratov, Aidos; Wang, Kai; Galas, David; Wilmes, Paul

    2015-01-21

    The secretion of biomolecules into the extracellular milieu is a common and well-conserved phenomenon in biology. In bacteria, secreted biomolecules are not only involved in intra-species communication but they also play roles in inter-kingdom exchanges and pathogenicity. To date, released products, such as small molecules, DNA, peptides, and proteins, have been well studied in bacteria. However, the bacterial extracellular RNA complement has so far not been comprehensively characterized. Here, we have analyzed, using a combination of physical characterization and high-throughput sequencing, the extracellular RNA complement of both outer membrane vesicle (OMV)-associated and OMV-free RNA of the enteric Gram-negative model bacterium Escherichia coli K-12 substrain MG1655 and have compared it to its intracellular RNA complement. Our results demonstrate that a large part of the extracellular RNA complement is in the size range between 15 and 40 nucleotides and is derived from specific intracellular RNAs. Furthermore, RNA is associated with OMVs and the relative abundances of RNA biotypes in the intracellular, OMV and OMV-free fractions are distinct. Apart from rRNA fragments, a significant portion of the extracellular RNA complement is composed of specific cleavage products of functionally important structural noncoding RNAs, including tRNAs, 4.5S RNA, 6S RNA, and tmRNA. In addition, the extracellular RNA pool includes RNA biotypes from cryptic prophages, intergenic, and coding regions, of which some are so far uncharacterised, for example, transcripts mapping to the fimA-fimL and ves-spy intergenic regions. Our study provides the first detailed characterization of the extracellular RNA complement of the enteric model bacterium E. coli. Analogous to findings in eukaryotes, our results suggest the selective export of specific RNA biotypes by E. coli, which in turn indicates a potential role for extracellular bacterial RNAs in intercellular communication. © 2015 The

  11. Utilization of high temperature compost in space agriculture: the model compost kills Escherichia coli

    Science.gov (United States)

    Oshima, Tairo; Moriya, Toshiyuki; Yoshii, Takahiro

    The author and his colleagues have proposed the use of high temperature composting in space inhabitation. Composting has many advantages over burning in organic waste treatments. Composting is self-heating processes and needs no extra fuel. Composting requires no sophis-ticated equipment such as an incinerator. Composting emits no hazardous gases such as NOx, SOx and dioxines which are often produced by burning. The final product can be used as fer-tilizer in space farm land; resources recycling society can be constructed in space stations and space cities. In addition to these advantages, composting and compost soil may contribute to the environmental cleanup. During composting processes, harmful compounds to agricultural plants and animals can be destroyed. Seeds of weeds can be killed by high heat. Likewise pathogenic microbes in the waste can be eliminated during fermentation inside the composts. Recently we measured the survivability of E. coli in compost. E. coli was used as the represen-tative of the Gram-negative bacteria. Since many pathogenic strains belong to Gram-negative bacteria and Gram-negative bacteria are more resistant to antibiotics than gram-positive bac-teria. When E. coli cells were mixed in the compost pile of which inside temperature reaches up to 75oC, they died within a short period as expected. However, E. coli DNA was detected even after a day in high temperature compost. RNA has a shorter life-span than DNA, but was detected after incubation in compost for several hours. In addition to sterilizing effects due to high temperature, we found our compost soil has E. coli killing activity. When mixed with the compost soil at room temperature, E. coli died gradually. Extract of the compost soil also killed E. coli at room temperature, but it took a few days to eliminate E. coli completely. During the killing process, total number of living bacteria did not change, indicating that the killing activity is limited to some specific

  12. Escherichia coli in Europe: An Overview

    Directory of Open Access Journals (Sweden)

    Nerino Allocati

    2013-11-01

    Full Text Available Escherichia coli remains one of the most frequent causes of several common bacterial infections in humans and animals. E. coli is the prominent cause of enteritis, urinary tract infection, septicaemia and other clinical infections, such as neonatal meningitis. E. coli is also prominently associated with diarrhoea in pet and farm animals. The therapeutic treatment of E. coli infections is threatened by the emergence of antimicrobial resistance. The prevalence of multidrug-resistant E. coli strains is increasing worldwide principally due to the spread of mobile genetic elements, such as plasmids. The rise of multidrug-resistant strains of E. coli also occurs in Europe. Therefore, the spread of resistance in E. coli is an increasing public health concern in European countries. This paper summarizes the current status of E. coli strains clinically relevant in European countries. Furthermore, therapeutic interventions and strategies to prevent and control infections are presented and discussed. The article also provides an overview of the current knowledge concerning promising alternative therapies against E. coli diseases.

  13. Pathogenomics of uropathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    J Agarwal

    2012-01-01

    Full Text Available Subset of faecal E. coli that can enter, colonize urinary tract and cause infection are known as uropathogenic E. coli (UPEC. UPEC strains act as opportunistic intracellular pathogens taking advantage of host susceptibility using a diverse array of virulence factors. Presence of specific virulence associated genes on genomic/pathogenicity islands and involvement of horizontal gene transfer appears to account for evolution and diversity of UPEC. Recent success in large-scale genome sequencing and comparative genomics has helped in unravelling UPEC pathogenomics. Here we review recent findings regarding virulence characteristics of UPEC and mechanisms involved in pathogenesis of urinary tract infection.

  14. SoxS Increases the Expression of the Zinc Uptake System ZnuACB in an Escherichia coli Murine Pyelonephritis Model

    OpenAIRE

    Warner, Douglas M; Levy, Stuart B.

    2012-01-01

    Paralogous transcriptional regulators MarA, Rob, and SoxS act individually and together to control expression of more than 80 Escherichia coli genes. Deletion of marA, rob, and soxS from an E. coli clinical isolate prevents persistence beyond 2 days postinfection in a mouse model of pyelonephritis. We used microarray analysis to identify 242 genes differentially expressed between the triple deletion mutant and its parent strain at 2 days postinfection in the kidney. One of these, znuC of the ...

  15. Escherichia coli isolates from commercial chicken meat and eggs cause sepsis, meningitis and urinary tract infection in rodent models of human infections.

    Science.gov (United States)

    Mellata, M; Johnson, J R; Curtiss, R

    2017-07-13

    The zoonotic potential of Escherichia coli from chicken-source food products is important to define for public health purposes. Previously, genotypic and phenotypic screening of E. coli isolates from commercial chicken meat and shell eggs identified some E. coli strains that by molecular criteria resembled human-source extraintestinal pathogenic E. coli (ExPEC). Here, to clarify the zoonotic risk of such chicken-source E. coli, we compared selected E. coli isolates from chicken meat and eggs, stratified by molecularly defined ExPEC status, to human-source ExPEC and to laboratory E. coli for virulence in rodent models of sepsis, meningitis and UTI, and evaluated whether specific bacterial characteristics predict experimental virulence. Multiple chicken-source E. coli resembled human-source ExPEC in their ability to cause one or multiple different ExPEC-associated infections. Swimming ability corresponded with urovirulence, K1 capsule corresponded with ability to cause neonatal meningitis, and biofilm formation in urine corresponded with ability to cause sepsis. In contrast, molecularly defined ExPEC status and individual genotypic traits were uncorrelated with ability to cause sepsis, and neither complement sensitivity nor growth in human urine corresponded with virulence in any infection model. These findings establish that chicken-derived food products contain E. coli strains that, in rodent models of multiple human-associated ExPEC infections, are able to cause disease comparably to human-source E. coli clinical isolates, which suggests that they may pose a significant food safety threat. Further study is needed to define the level of risk they pose to human health, which if appreciable would justify efforts to monitor for and reduce or eliminate them. © 2017 Blackwell Verlag GmbH.

  16. Infektionen mit darmpathogenen Escherichia coli.

    NARCIS (Netherlands)

    Friedrich, Alexander; Stein, Jürgen; Dignass, Axel

    2001-01-01

    E. coli ist ein wesentlicher Bestandteil der physiologischen Darmflora des Menschen. Die üblicherweise im Darm vorkommenden Kolibakterien sind apathogen und für den Menschen eher nützlich (Sonnenborn u. Greinwald 1990). Allerdings kennen wir bei dieser Bakterienspezies auch ein breites Spektrum von

  17. Modelling the Survival of Escherichia coli O157:H7 on Raw Portioned Tomatoes, Inoculated with Aspergillus fumigatus and Emericella nidulans

    OpenAIRE

    2009-01-01

    The metabiotic interactions occurring among two fungi (Aspergillus fumigatus and Emericella nidulans) and Escherichia coli O157:H7 on raw portioned tomatoes were studied. Tomatoes, preinoculated with the moulds and inoculated with the pathogen, were packaged in air and stored at 4, 8 and 12C∘ for 9 days; pathogen cell number and pH were monitored throughout the storage and the data were modeled using three different equations (Geeraerd, Weibull, and modified Weibull), to assess the shoulder l...

  18. Modelling the epidemiology and transmission of Verocytotoxin-producing Escherichia coli serogroups O26 and O103 in two different calf cohorts

    OpenAIRE

    Liu, W-C; Shaw, D. J.; Matthews, L; Hoyle, Deborah; Pearce, M.C.; Yates, C M; Low, J. C.; Amyes, S G B; Gunn, G.J.; Woolhouse, M. E. J.

    2007-01-01

    Mathematical models are constructed to investigate the population dynamics of Verocytotoxin-producing Escherichia coli (VTEC) serogroups O26 and O103 in two different calf cohorts. We compare the epidemiological characteristics of these two serogroups within the same calf cohort as well as the same serogroups between the two calf cohorts. The sources of infection are quantified for both calf cohort studies. VTEC serogroups O26 and O103 mainly differ in the rate at which calves acquire infecti...

  19. Modeling functional changes to Escherichia coli thymidylate synthase upon single residue replacements: a structure-based approach

    Directory of Open Access Journals (Sweden)

    Majid Masso

    2015-01-01

    Full Text Available Escherichia coli thymidylate synthase (TS is an enzyme that is indispensable to DNA synthesis and cell division, as it provides the only de novo source of dTMP by catalyzing the reductive methylation of dUMP, thus making it a key target for chemotherapeutic agents. High resolution X-ray crystallographic structures are available for TS and, owing to its relatively small size, successful experimental mutagenesis studies have been conducted on the enzyme. In this study, an in silico mutagenesis technique is used to investigate the effects of single amino acid substitutions in TS on enzymatic activity, one that employs the TS protein structure as well as a knowledge-based, four-body statistical potential. For every single residue TS variant, this approach yields both a global structural perturbation score and a set of local environmental perturbation scores that characterize the mutated position as well as all structurally neighboring residues. Global scores for the TS variants are capable of uniquely characterizing groups of residue positions in the enzyme according to their physicochemical, functional, or structural properties. Additionally, these global scores elucidate a statistically significant structure–function relationship among a collection of 372 single residue TS variants whose activity levels have been experimentally determined. Predictive models of TS variant activity are subsequently trained on this dataset of experimental mutants, whose respective feature vectors encode information regarding the mutated position as well as its six nearest residue neighbors in the TS structure, including their environmental perturbation scores.

  20. Survival of Escherichia coli in stormwater biofilters.

    Science.gov (United States)

    Chandrasena, G I; Deletic, A; McCarthy, D T

    2014-04-01

    Biofilters are widely adopted in Australia for stormwater treatment, but the reported removal of common faecal indicators (such as Escherichia coli (E. coli)) varies from net removal to net leaching. Currently, the underlying mechanisms that govern the faecal microbial removal in the biofilters are poorly understood. Therefore, it is important to study retention and subsequent survival of faecal microorganisms in the biofilters under different biofilter designs and operational characteristics. The current study investigates how E. coli survival is influenced by temperature, moisture content, sunlight exposure and presence of other microorganisms in filter media and top surface sediment. Soil samples were taken from two different biofilters to investigate E. coli survival under controlled laboratory conditions. Results revealed that the presence of other microorganisms and temperature are vital stressors which govern the survival of E. coli captured either in the top surface sediment or filter media, while sunlight exposure and moisture content are important for the survival of E. coli captured in the top surface sediment compared to that of the filter media. Moreover, increased survival was found in the filter media compared to the top sediment, and sand filter media was found be more hostile than loamy sand filter media towards E. coli survival. Results also suggest that the contribution from the tested environmental stressors on E. coli survival in biofilters will be greatly affected by the seasonality and may vary from one site to another.

  1. An empirical approach for quantifying loop-mediated isothermal amplification (LAMP using Escherichia coli as a model system.

    Directory of Open Access Journals (Sweden)

    Sowmya Subramanian

    Full Text Available Loop mediated isothermal amplification (LAMP is a highly efficient, selective and rapid DNA amplification technique for genetic screening of pathogens. However, despite its popularity, there is yet no mathematical model to quantify the outcome and no well-defined metric for comparing results that are available. LAMP is intrinsically complex and involves multiple pathways for gene replication, making fundamental modelling nearly intractable. To circumvent this difficulty, an alternate, empirical model is introduced that will allow one to extract a set of parameters from the concentration versus time curves. A simple recipe to deduce the time to positive, Tp--a parameter analogous to the threshold cycling time in polymerase chain reaction (PCR, is also provided. These parameters can be regarded as objective and unambiguous indicators of LAMP amplification. The model is exemplified on Escherichia coli strains by using the two gene fragments responsible for vero-toxin (VT production and tested against VT-producing (O157 and O45 and non-VT producing (DH5 alpha strains. Selective amplification of appropriate target sequences was made using well established LAMP primers and protocols, and the concentrations of the amplicons were measured using a Qubit 2.0 fluorometer at specific intervals of time. The data is fitted to a generalized logistic function. Apart from providing precise screening indicators, representing the data with a small set of numbers offers significant advantages. It facilitates comparisons of LAMP reactions independently of the sampling technique. It also eliminates subjectivity in interpretation, simplifies data analysis, and allows easy data archival, retrieval and statistical analysis for large sample populations. To our knowledge this work represents a first attempt to quantitatively model LAMP and offer a standard method that could pave the way towards high throughput automated screening.

  2. Escherichia coli resistance in uncomplicated urinary tract infection: a model for determining when to change first-line empirical antibiotic choice.

    Science.gov (United States)

    Perfetto, Eleanor M; Gondek, Kathleen

    2002-06-01

    Escherichia coli is typically the causative organism in uncomplicated urinary tract infection (UTI). Resistance rates of E. coli to trimethoprim/sulfamethoxazole (TMP/SMX) are increasing, exceeding 10% in many communities. Guidelines recommend using alternative treatments in these areas. Providers must reevaluate policies to include considerations for E. coli resistance. A model was developed, with cases for illustration, to help organizations determine the resistance rate threshold, where TMP/SMX is no longer first-line therapy. Using published data, a 19% to 21% threshold was derived, supporting a previous report of 22%. The model can aid decision makers updating internal policies to conform with guidelines for the treatment of uncomplicated UTI and to improve care.

  3. 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

  4. Porcine intestinal epithelial cell lines as a new in vitro model for studying adherence and pathogenesis of enterotoxigenic Escherichia coli.

    Science.gov (United States)

    Koh, Seung Y; George, Sajan; Brözel, Volker; Moxley, Rodney; Francis, David; Kaushik, Radhey S

    2008-07-27

    Enterotoxigenic Escherichia coli (ETEC) infections result in large economic losses in the swine industry worldwide. The organism causes diarrhea by adhering to and colonizing enterocytes in the small intestines. While much progress has been made in understanding the pathogenesis of ETEC, no homologous intestinal epithelial cultures suitable for studying porcine ETEC pathogenesis have been described prior to this report. In the current study, we investigated the adherence of various porcine ETEC strains to two porcine (IPEC-1 and IPEC-J2) and one human (INT-407) small intestinal epithelial cell lines. Each cell line was assessed for its ability to support the adherence of E. coli expressing fimbrial adhesins K88ab, K88ac, K88ad, K99, F41, 987P, and F18. Wild-type ETEC expressing K88ab, K88ac, and K88ad efficiently bound to both IPEC-1 and IPEC-J2 cells. An ETEC strain expressing both K99 and F41 bound heavily to both porcine cell lines but an E. coli strain expressing only K99 bound very poorly to these cells. E. coli expressing F18 adhesin strongly bound to IPEC-1 cells but did not adhere to IPEC-J2 cells. The E. coli strains G58-1 and 711 which express no fimbrial adhesins and those that express 987P fimbriae failed to bind to either porcine cell line. Only strains B41 and K12:K99 bound in abundance to INT-407 cells. The binding of porcine ETEC to IPEC-J2, IPEC-1 and INT-407 with varying affinities, together with lack of binding of 987P ETEC and non-fimbriated E. coli strains, suggests strain-specific E. coli binding to these cell lines. These findings suggest the potential usefulness of porcine intestinal cell lines for studying ETEC pathogenesis.

  5. EcoCyc: Encyclopedia of Escherichia coli genes and metabolism.

    Science.gov (United States)

    Karp, P D; Riley, M; Paley, S M; Pellegrini-Toole, A; Krummenacker, M

    1998-01-01

    The encyclopedia of Escherichia coli genes and metabolism (EcoCyc) is a database that combines information about the genome and the intermediary metabolism of E.coli. The database describes 3030 genes of E.coli , 695 enzymes encoded by a subset of these genes, 595 metabolic reactions that occur in E.coli, and the organization of these reactions into 123 metabolic pathways. The EcoCyc graphical user interface allows scientists to query and explore the EcoCyc database using visualization tools such as genomic-map browsers and automatic layouts of metabolic pathways. EcoCyc can be thought of as an electronic review article because of its copious references to the primary literature, and as a (qualitative) computational model of E.coli metabolism. EcoCyc is available at URL http://ecocyc.PangeaSystems.com/ecocyc/

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Automatic tracking of Escherichia coli bacteria.

    Science.gov (United States)

    Xie, Jun; Khan, Shahid; Shah, Mubarak

    2008-01-01

    In this paper, we present an automatic method for estimating the trajectories of Escherichia coli bacteria from in vivo phase-contrast microscopy videos. To address the low-contrast boundaries in cellular images, an adaptive kernel-based technique is applied to detect cells in sequence of frames. Then a novel matching gain measure is introduced to cope with the challenges such as dramatic changes of cells' appearance and serious overlapping and occlusion. For multiple cell tracking, an optimal matching strategy is proposed to improve the handling of cell collision and broken trajectories. The results of successful tracking of Escherichia coli from various phase-contrast sequences are reported and compared with manually-determined trajectories, as well as those obtained from existing tracking methods. The stability of the algorithm with different parameter values is also analyzed and discussed.

  8. Escherichia coli necrotizing fasciitis in Hirschsprung's disease

    Directory of Open Access Journals (Sweden)

    Manal A. Alsaif

    2015-04-01

    Full Text Available Necrotizing fasciitis is a rare post-operative complication of Hirschsprung's disease. Very recently the only previous case of necrotizing fasciitis following a Soave procedure was reported with the etiologic agent being Pseudomonas aeruginosa. Here we are reporting the second case of necrotizing fasciitis following a Soave procedure caused by an extended spectrum beta lactamase harboring strain of Escherichia coli which is a rare pathogen in type II necrotizing fasciitis.

  9. Homology requirements for recombination in Escherichia coli.

    OpenAIRE

    Watt, V M; Ingles, C J; Urdea, M S; Rutter, W J

    1985-01-01

    The DNA sequence homology required for recombination in Escherichia coli has been determined by measuring the recombination frequency between insulin DNA in a miniplasmid pi VX and a homologous sequence in a bacteriophage lambda vector. A minimum of approximately equal to 20 base pairs in a completely homologous segment is required for significant recombination. There is an exponential increase in the frequency of recombination when the length of homologous DNA is increased from 20 base pairs...

  10. Experimental model of enterotoxigenic Escherichia coli infection in pigs: potential for an early recognition of colibacillosis by monitoring of behavior.

    Science.gov (United States)

    Krsnik, B; Yammine, R; Pavicić, Z; Balenović, T; Njari, B; Vrbanac, I; Valpotić, I

    1999-10-01

    The hypothesis that altered behavior is a sign for an early recognition of disease was tested. The experiment was conducted to evaluate the behavioral patterns of pigs in a model of postweaning colibacillosis. Twenty-five weaned pigs (from a herd that was previously found to be highly susceptible to F4+ Escherichia coli strains) were randomly assigned into 5 groups, kept in isolated pens under the controlled ambiental conditions. One day after weaning, the pigs from three groups were intragastrically inoculated (via orogastric tube) with either F4ac+ (1466 or 2407) or F4- (1467) nonenterotoxigenic E. coli (non-ETEC) strains, respectively. The pigs from the fourth group were inoculated with F4ac+ ETEC strain M1823 and the remaining 5 pigs that received broth containing 1.2% sodium bicarbonate were kept as noninoculated controls. The pigs were examined daily and the frequency and duration of their behavioral patterns, such as eating, drinking, lying, standing, urinating, defecating, rooting and playing were monitored for 300 h during a period of 10 days. In this model, three conditions were also observed in F4-susceptible pigs: (1) acute fatal diarrheal disease; (2) moderate diarrhea and weight loss and (3) no diarrhea and weight loss. The incidence (both frequency and duration) of defecating was significantly higher (P < 0.05) in pigs inoculated with F4ac+ ETEC strain M1823 as compared to that of noninoculated (control) pigs. Pigs inoculated with F4ac+ non-ETEC strain 1466 had a significantly lower frequency of eating (P < 0.05) and frequency/duration of drinking (P < 0.05) than did the controls. The 1466-inoculated pigs, had an increased diarrhea score, but frequency/duration of defecating was not significantly different. Pigs inoculated with F4ac+ non-ETEC strain 2407 spent more time in lying (P < 0.05) than did noninoculated pigs. Conversely, the pigs that received F4- non-ETEC strain 1467 laid shorter (P < 0.05) and ate/drank less frequently (P < 0.05) than the

  11. Enterohemorrhagic Escherichia coli induce attaching and effacing lesions and hemorrhagic colitis in human and bovine intestinal xenograft models

    Directory of Open Access Journals (Sweden)

    Lilach Golan

    2011-01-01

    Enterohemorrhagic Escherichia coli (EHEC O157:H7 is an important cause of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome in humans worldwide. The two major virulence determinants of EHEC are the Shiga toxins (Stx and the type III secretion system (T3SS, including the injected effectors. Lack of a good model system hinders the study of EHEC virulence. Here, we investigated whether bovine and human intestinal xenografts in SCID mice can be useful for studying EHEC and host tissue interactions. Fully developed, germ-free human and bovine small intestine and colon were established by subcutaneous transplantation of human and bovine fetal gut into SCID mice. Xenografts were allowed to develop for 3–4 months and thereafter were infected by direct intraluminal inoculation of Stx-negative derivatives of EHEC O157:H7, strain EDL933. The small intestine and colon xenografts closely mimicked the respective native tissues. Upon infection, EHEC induced formation of typical attaching and effacing lesions and tissue damage that resembled hemorrhagic colitis in colon xenografts. By contrast, xenografts infected with an EHEC mutant deficient in T3SS remained undamaged. Furthermore, EHEC did not attach to or damage the epithelium of small intestinal tissue, and these xenografts remained intact. EHEC damaged the colon in a T3SS-dependent manner, and this model is therefore useful for studying the molecular details of EHEC interactions with live human and bovine intestinal tissue. Furthermore, we demonstrate that Stx and gut microflora are not essential for EHEC virulence in the human gut.

  12. Multiplex PCR Assay for Identification of Human Diarrheagenic Escherichia coli

    OpenAIRE

    Toma, Claudia; Lu, Yan; Higa, Naomi; Nakasone, Noboru; Isabel CHINEN; 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.

  13. Multiplex PCR Assay for Identification of Human Diarrheagenic Escherichia coli

    OpenAIRE

    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.

  14. Nanotextile membranes for bacteria Escherichia coli capturing

    Directory of Open Access Journals (Sweden)

    Jaroslav Lev

    2010-01-01

    Full Text Available The article describes an experimental study dealing with the possibility of nanotextile materials usa­ge for microbiologically contaminated water filtration. The aim of the study is to verify filtration ability of different nanotextile materials and evaluate the possibilities of practical usage. Good detention ability of these materials in the air filtration is the presumption for nanotextile to be used for bacteria filtration from a liquid. High nanotextile porosity with the nanotextile pores dimensions smaller than a bacteria size predicates the possibility of a successful usage of these materials. For the experiment were used materials made from electrospinning nanofibres under the label PA612, PUR1, PUR2 s PUR3 on the supporting unwoven textiles (viscose and PP. As a model simulation of the microbial contamination, bacteria Escherichia coli was chosen. Contaminated water was filtered during the overpressure activity of 105Pa on the input side of the filter from the mentioned material. After three-day incubation on the nutrient medium, cultures found in the samples before and after filtration were compared. In the filtrated water, bacteria E. coli were indicated, which did not verify the theoretical presumptions about an absolut bacteria detention. However, used materials caught at least 94% of bacteria in case of material PUR1 and up to 99,996% in case of material PUR2. These results predict the possibility of producing effective nanotextile filters for microbiologically contaminated water filtration.Recommendation: For the production of materials with better filtrating qualities, experiments need to be done, enabling better understanding of the bacteria detention mechanisms on the nanotextile material, and parameters of the used materials that influence the filtrating abilities need to be verified.

  15. Novel application of the CORAL software to model cytotoxicity of metal oxide nanoparticles to bacteria Escherichia coli.

    Science.gov (United States)

    Toropov, Andrey A; Toropova, Alla P; Benfenati, Emilio; Gini, Giuseppina; Puzyn, Tomasz; Leszczynska, Danuta; Leszczynski, Jerzy

    2012-11-01

    Convenient to apply and available on the Internet software CORAL (http://www.insilico.eu/CORAL) has been used to build up quantitative structure-activity relationships (QSAR) for prediction of cytotoxicity of metal oxide nanoparticles to bacteria Escherichia coli (minus logarithm of concentration for 50% effect pEC50). In this study six random splits of the data into the training and test set were examined. It has been shown that the CORAL provides a reliable tool that could be used to build up a QSAR of the pEC50. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Assessing the effect of interventions on the risk of cattle and sheep carrying Escherichia coli O157:H7 to the abattoir using a stochastic model.

    Science.gov (United States)

    Stacey, K F; Parsons, D J; Christiansen, K H; Burton, C H

    2007-04-16

    Escherichia coli O157:H7 persists in being a threat to food safety. The mechanisms behind the spread of E. coli O157:H7 on the farm are complex and poorly understood. The objective of this study was to apply a Monte Carlo model, constructed to simulate the propagation of E. coli O157:H7 in cattle and sheep on the farm, to both test the effect of different interventions on the risk of animals carrying E. coli O157:H7 to the abattoir and to develop understanding of the underlying processes, including the identification of areas that could benefit from further research. An overview of the model including key assumptions is given. The output statistics from batches of 100 runs of the model were collected. From the model output, a cumulative frequency distribution of the prevalence and specific shedding level for the groups of cattle or sheep being sent to the abattoir were generated. Stochastic dominance was used to compare the results of the model outputs. Using the shorthand that "risk" means the likelihood of carrying E. coli O157:H7 to the abattoir, key conclusions from the study included: mixing sheep and cattle increases the risk in both groups; merging groups of animals of the same species into larger groups increases the risk substantially; increasing stocking density increases the risk independently of group size; decreasing the group size decreases the E. coli O157:H7 prevalence independently of stocking density; a very high level of barn hygiene reduces the risk; a shorter time between spreading farmyard manure and grazing and an increased background level of E. coli O157:H7 in the model increases the risk. The background level could be influenced by the presence of wild animals carrying the organism. The parameters to which the model is most sensitive are those related to transmission from grass and enclosures to animals, pathogen survival on grass, in slurry and in barns and contact between animals.

  17. Siderophore production by uropathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Vagrali Manjula

    2009-01-01

    Full Text Available Urinary tract infection (UTI is one of the most frequently encountered problems in ambulatory medicine. The present study was designed to determine siderophore production as the urovirulence factor of Escherichia coli isolated from the patients of UTI. A total of 160 strains of E. coli isolated from urine of patients with clinically diagnosed UTI were included in the study and 50 fecal isolates of E. coli, siderophore production was seen in 156 (97.5%. In 50 fecal isolates, siderophore production was seen in 2 (4%. Siderophore production has been shown to be more frequent in E. coli from patients with UTI, than in fecal isolates. The results suggest that siderophore production positive strains can be considered as UPEC. Thus, although a great deal has been learned regarding E. coli virulence mechanisms in UTI, much remains to be learned and the practical application of our growing understanding of E. coli virulence factors to the prevention and treatment of UTI has to be continued.

  18. Differentiation between Shigella, enteroinvasive Escherichia coli (EIEC) and noninvasive Escherichia coli.

    Science.gov (United States)

    van den Beld, M J C; Reubsaet, F A G

    2012-06-01

    Shigella causes bacillary dysentery and is classified into four species based on their antigen characteristics. This classification does not reflect genetic relatedness; in fact, Shigella species are so related to Escherichia coli , they should be classified as one distinctive species in the genus Escherichia. The differentiation of Shigella and E. coli is even more complicated with the description of enteroinvasive E. coli (EIEC). EIEC are strains that possess some of the biochemical characteristics of E. coli and have the ability to cause dysentery using the same method of invasion as Shigella does. Sequencing of multiple housekeeping genes indicates that EIEC is more related to Shigella than to non-invasive E. coli. Shigella and EIEC evolved from the same ancestor and form a single pathovar within E. coli. Shigella and EIEC could be separated from other E. coli by a PCR targeting the ipaH-gene; this is a multicopy gene exclusively found in all Shigella and EIEC. It is possible to differentiate Shigella and all E. coli, including EIEC, by using multiple tests, including ipaH-gene PCR, physiological and biochemical typing and serological typing. Based on literature study, a key is designed for daily use in diagnostic laboratories to identify Shigella and all E. coli.

  19. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    In this study we report on a novel structural phenotype in Escherichia coli biofilms: cellular chain formation. Biofilm chaining in E. coli K-12 was found to occur primarily by clonal expansion, but was not due to filamentous growth. Rather, chain formation was the result of intercellular......; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates......, including the prototypic asymptomatic bacteriuria strain, 83972, formed highly elaborate cellular chains during biofilm growth in human urine. Combined, these results illustrate the diversity of biofilm architectures that can be observed even within a single microbial species....

  20. Interaction between Escherichia coli and lunar fines

    Science.gov (United States)

    Johansson, K. R.

    1983-01-01

    A sample of mature lunar fines (10084.151) was solubilized to a high degree (about 17 percent) by the chelating agent salicylic acid (0.01. M). The neutralized (pH adjusted to 7.0) leachate was found to inhibit the growth of Escherichia coli (ATCC 259922) in a minimial mineral salts glucose medium; however, the inhibition was somewhat less than that caused by neutralized salicylic acid alone. The presence of lunar fines in the minimal medium was highly stimulatory to growth of E. coli following an early inhibitory response. The bacterium survived less well in the lunar leachate than in distilled water, no doubt because of the salicylate. It was concluded that the sample of lunar soil tested has nutritional value to E. coli and that certain products of fermentation helped to solubilize the lunar soil.

  1. Pathophysiology of enteroaggregative Escherichia coli infection: an experimental model utilizing transmission electron microscopy Fisiopatologia da infecção pela Escherichia coli enteroagregativa: um modelo experimental utilizando microscopia eletrônica de transmissão

    Directory of Open Access Journals (Sweden)

    Jacy Alves Braga de Andrade

    2010-09-01

    Full Text Available CONTEXT: Enteroaggregative Escherichia coli strains have been associated with persistent diarrhea in several developing countries. In vivo procedures with animal models as rat, rabbit and gnotobiotic piglets intestinal loops, in vitro assays with cellular lines like T84, Caco 2, HT29, HeLa e HEp-2 and in vitro organ culture with intestinal fragments have been applied to study these bacteria and their pathogenicity. OBJECTIVES: The present experimental research assessed the pathogenic interactions of three enteroaggregative Escherichia coli strains, using the in vitro organ culture, in order to observe and compare alterations in different regions of both, the ileal and the colonic mucosa. METHODS: This study applied intestinal fragments from terminal ileum and colon that were excised from pediatric and adult patients that underwent colonoscopic procedures. Tissue was fixed for transmission electron microscopic study. Each bacterium was tested with three intestinal fragments for each region. RESULTS: Enteroaggregative Escherichia coli strains colonized and provoked citotoxic effects in the ileal and colonic mucosa. Total or partial villi destruction, vacuolization of basal cytoplasm of the enterocytes, epithelium detachment, derangement of the structure and epithelial cell extrusion in ileal mucosa could explain the perpetuation of the diarrhea. Bacterial aggregates were seen in intestinal lumen associated with mucus and cellular debris and in the intercellular spaces of the destroyed epithelium, suggesting bacterial invasion that seemed to be secondary to the destruction of the tissue. CONCLUSIONS: Pathogenesis of persistent diarrhea should include alterations in the small bowel structures where the digestive-absorptive functions take place. In the colonic mucosa the inflammatory lesions could explain the occurrence of colitis.CONTEXTO: A Escherichia coli enteroagregativa está associada à diarréia persistente em vários países em

  2. Comparative evaluation of statistical and mechanistic models of Escherichia coli at beaches in southern Lake Michigan

    Science.gov (United States)

    Safaie, Ammar; Wendzel, Aaron; Ge, Zhongfu; Nevers, Meredith; Whitman, Richard L.; Corsi, Steven R.; Phanikumar, Mantha S.

    2016-01-01

    Statistical and mechanistic models are popular tools for predicting the levels of indicator bacteria at recreational beaches. Researchers tend to use one class of model or the other, and it is difficult to generalize statements about their relative performance due to differences in how the models are developed, tested, and used. We describe a cooperative modeling approach for freshwater beaches impacted by point sources in which insights derived from mechanistic modeling were used to further improve the statistical models and vice versa. The statistical models provided a basis for assessing the mechanistic models which were further improved using probability distributions to generate high-resolution time series data at the source, long-term “tracer” transport modeling based on observed electrical conductivity, better assimilation of meteorological data, and the use of unstructured-grids to better resolve nearshore features. This approach resulted in improved models of comparable performance for both classes including a parsimonious statistical model suitable for real-time predictions based on an easily measurable environmental variable (turbidity). The modeling approach outlined here can be used at other sites impacted by point sources and has the potential to improve water quality predictions resulting in more accurate estimates of beach closures.

  3. Evaluating Escherichia coli removal performance in stormwater biofilters: a preliminary modelling approach.

    Science.gov (United States)

    Chandrasena, G I; Deletic, A; McCarthy, D T

    2013-01-01

    Stormwater biofilters are not currently optimised for pathogen removal since the behaviour of these pollutants within the stormwater biofilters is poorly understood. Modelling is a common way of optimising these systems, which also provides a better understanding of the major processes that govern the pathogen removal. This paper provides an overview of a laboratory-scale study that investigated how different design and operational conditions impact pathogen removal in the stormwater biofilters. These data were then used to develop a modelling tool that can be used to optimise the design and operation of the stormwater biofilters. The model uses continuous simulations where adsorption and desorption were dominant during wet weather periods and first order die-off kinetics were significant in dry periods between the wet weather events. Relatively high Nash Sutcliffe Efficiencies (>0.5) indicate that the calibrated model is in good agreement with observed data and the optimised model parameters were comparable with values reported in the literature. The model's sensitivity is highest towards the adsorption process parameter followed by the die-off and desorption rate parameters, which implies that adsorption is the governing process of the model. Vegetation is found to have an impact on the wet weather processes since the adsorption and desorption parameters vary significantly with the different plant configurations. The model is yet to be tested against field data and needs to be improved to represent the effect of some other biofilter design configurations, such as the inclusion of the submerged zone.

  4. Temporal changes of oxidative stress markers in Escherichia coli K1-induced experimental meningitis in a neonatal rat model.

    Science.gov (United States)

    Giridharan, Vijayasree V; Simões, Lutiana R; Dagostin, Valdemira S; Generoso, Jaqueline S; Rezin, Gislaine T; Florentino, Drielly; Muniz, Jhonata P; Collodel, Allan; Petronilho, Fabricia; Quevedo, Joao; Barichello, Tatiana

    2017-07-13

    Despite advances in antimicrobial therapy and advanced critical care neonatal bacterial meningitis has a mortality rate of over 10% and induces neurological sequelae in 20-50% of cases. Escherichia coli K1 (E. coli K1) is the most common gram-negative organism causing neonatal meningitis and is the second most common cause behind group B streptococcus. We previously reported that an E. coli K1 experimental meningitis infection in neonatal rats resulted in habituation and aversive memory impairment and a significant increase in cytokine levels in adulthood. In this present study, we investigated the oxidative stress profile including malondialdehyde (MDA) levels, carbonyl protein formation, myeloperoxidase activity (MPO) activity, superoxide dismutase (SOD) activity and catalase (CAT) activity 6, 12, 24, 48, 72 and 96h after E. coli K1 experimental meningitis infection. In addition, sulfhydryl groups, nitrite and nitrate levels and activity of the mitochondrial respiratory chain enzymes were also measured in the frontal cortex and hippocampus of neonatal rats. The results from this study demonstrated a significant increase in MDA, protein carbonyls and MPO activity and a simultaneous decrease in SOD activity in the hippocampus of the neonatal meningitis survivors but the same was not observed in frontal cortex. In addition, we also observed a significant increase in complex IV activity in the hippocampus and frontal cortex of meningitis survivor rats. Thus, the results from this study reaffirmed the possible role of oxidative stress, nitric oxide and its related compounds in the complex pathophysiology of E. coli K1-induced bacterial meningitis. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Model-driven discovery of underground metabolic functions in Escherichia coli

    DEFF Research Database (Denmark)

    Guzmán, Gabriela I.; Utrilla, José; Nurk, Sergey

    2015-01-01

    of unknown underground pathways stemming from enzymatic cross-reactivity. We demonstrate a workflow that couples constraint-based modeling and bioinformatic tools with KO strain analysis and adaptive laboratory evolution for the purpose of predicting promiscuity at the genome scale. Three cases of genes......E, and gltA and prpC. This study demonstrates how a targeted model-driven approach to discovery can systematically fill knowledge gaps, characterize underground metabolism, and elucidate regulatory mechanisms of adaptation in response to gene KO perturbations....

  6. EcoCyc: Enyclopedia of Escherichia coli Genes and Metabolism.

    Science.gov (United States)

    Karp, P D; Riley, M; Paley, S M; Pellegrini-Toole, A; Krummenacker, M

    1997-01-01

    The Encyclopedia of Genes and Metabolism (EcoCyc) is a database that combines information about the genome and the intermediary metabolism of Escherichia coli. It describes 2970 genes of E.coli, 547 enzymes encoded by these genes, 702 metabolic reactions that occur in E.coli and the organization of these reactions into 107 metabolic pathways. The EcoCyc graphical user interface allows scientists to query and explore the EcoCyc database using visualization tools such as genomic-map browsers and automatic layouts of metabolic pathways. EcoCyc spans the space from sequence to function to allow scientists to investigate an unusually broad range of questions. EcoCyc can be thought of as both an electronic review article because of its copious references to the primary literature, and as an in silicio model of E.coli metabolism that can be probed and analyzed through computational means.

  7. Effects of the Probiotic Enterococcus faecium and Pathogenic Escherichia coli Strains in a Pig and Human Epithelial Intestinal Cell Model

    Directory of Open Access Journals (Sweden)

    Ulrike Lodemann

    2015-01-01

    Full Text Available The aim of this study has been to elucidate the effect of the probiotic Enterococcus faecium NCIMB 10415 on epithelial integrity in intestinal epithelial cells and whether pre- and coincubation with this strain can reproducibly prevent damage induced by enterotoxigenic (ETEC and enteropathogenic Escherichia coli (EPEC. Porcine (IPEC-J2 and human (Caco-2 intestinal epithelial cells were incubated with bacterial strains and epithelial integrity was assessed by measuring transepithelial electrical resistance (TEER and mannitol flux rates. E. faecium alone increased TEER of Caco-2 cells without affecting mannitol fluxes whereas the E. coli strains decreased TEER and concomitantly increased mannitol flux rates in both cell lines. Preincubation with E. faecium had no effect on the TEER decrease induced by E. coli in preliminary experiments. However, in a second set of experiments using a slightly different protocol, E. faecium ameliorated the TEER decrease induced by ETEC at 4 h in IPEC-J2 and at 2, 4, and 6 h in Caco-2 cells. We conclude that E. faecium positively affected epithelial integrity in monoinfected Caco-2 cells and could ameliorate the damage on TEER induced by an ETEC strain. Reproducibility of the results is, however, limited when experiments are performed with living bacteria over longer periods.

  8. 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...

  9. A kinetic model of thiamine biosynthesis in Escherichia coli

    DEFF Research Database (Denmark)

    Matos, Marta; Herrgard, Markus; Andersen, Mikael Rørdam

    2014-01-01

    Thiamine can only be synthesized by prokaryotes and some eukaryotes, humans for example get it through their diet. Yet, it is key for the correct functioning of the carbohydrate and amino acid metabolism, and thiamine deficiency in humans can cause beriberi, which can result in muscle weakness...... or cardiovascular problems, among other symptoms. Nowadays it is common to add thiamine to commercial foods. Thus, it is important to produce it in a sustainable and efficient way. One approach to produce thiamine in a sustainable way is to use cell factories, and modeling of the metabolic network can be used...

  10. Antibacterial behavior of diamond nanoparticles against Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Beranova, Jana; Seydlova, Gabriela [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 16200 Prague (Czech Republic); Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, 12844 Prague (Czech Republic); Kozak, Halyna; Potocky, Stepan; Kromka, Alexander [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 16200 Prague (Czech Republic); Konopasek, Ivo [Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, 12844 Prague (Czech Republic)

    2012-12-15

    In this study, we investigated the potential antibacterial properties of nanocrystalline diamond. In particular, we tested the effect of diamond nanoparticles (DNPs) on growth of the model gram-negative bacterium Escherichia coli on solid, nutrient-rich growth medium. We found that the presence of DNPs on agar plates significantly reduced the colony forming ability of E. coli. The antibacterial effect occurred in a concentration dependent manner and was conditional on the specific ratio of DNPs to the number of bacterial cells. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Modeling transfer of Escherichia coli O157:H7 and Listeria monocytogenes during preparation of fresh-cut salads: impact of cutting and shredding practices.

    Science.gov (United States)

    Zilelidou, Evangelia A; Tsourou, Virginia; Poimenidou, Sofia; Loukou, Anneza; Skandamis, Panagiotis N

    2015-02-01

    Cutting and shredding of leafy vegetables increases the risk of cross contamination in household settings. The distribution of Escherichia coli O157:H7 and Listeria monocytogenes transfer rates (Tr) between cutting knives and lettuce leaves was investigated and a semi-mechanistic model describing the bacterial transfer during consecutive cuts of leafy vegetables was developed. For both pathogens the distribution of log10Trs from lettuce to knife was towards low values. Conversely log10Trs from knife to lettuce ranged from -2.1 to -0.1 for E. coli O157:H7 and -2.0 to 0 for L. monocytogenes, and indicated a more variable phenomenon. Regarding consecutive cuts, a rapid initial transfer was followed by an asymptotic tail at low populations moving to lettuce or residing on knife. E. coli O157:H7 was transferred at slower rates than L. monocytogenes. These trends were sufficiently described by the transfer-model, with RMSE values of 0.426-0.613 and 0.531-0.908 for L. monocytogenes and E. coli O157:H7, respectively. The model showed good performance in validation trials but underestimated bacterial transfer during extrapolation experiments. The results of the study can provide information regarding cross contamination events in a common household. The constructed model could be a useful tool for the risk-assessment during preparation of leafy-green salads.

  12. Intramammary challenge with Escherichia coli following immunization with a curli-producing Escherichia coli.

    Science.gov (United States)

    Todhunter, D A; Smith, K L; Hogan, J S; Nelson, L

    1991-03-01

    Holstein and Jersey cattle were immunized with a curli-producing strain of Escherichia coli (pCRL65/A012) or a noncurli-producing strain (pUC18/HB101) to determine differences in resistance to establishment of experimental intramammary infection. Cows (n = 6 per group) were immunized at 14 d prior to drying off, 7 d of involution, and at calving with 3 x 10(10) E. coli in Freund's Incomplete Adjuvant. At 30 d of lactation, one mammary quarter of each cow was infused with a wild strain of E. coli (727). Escherichia coli 727 was isolated from a naturally occurring intramammary infection and produced curli. All challenged quarters became infected, and all cows developed acute clinical mastitis. Geometric mean duration of intramammary infections was 6 d for both immunization groups. All infections were spontaneously eliminated within 10 d. No differences occurred between immunization groups in blood selenium and glutathione peroxidase activity, plasma selenium, number of E. coli 727 isolated from secretion after challenge, rectal temperature and SCC response, clinical status of mammary quarters, or DMI. Reduction in milk production after challenge was greater for cows immunized with E. coli pCRL65/A012. Immunization of dairy cattle with a curli-producing strain of E. coli did not protect against experimental intramammary challenge during lactation.

  13. Ethanol production by Escherichia coli KO11; Producao de etanol por Escherichia coli KO11

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Katia Gianni de Carvalho [Sao Paulo Univ., SP (Brazil). Faculdade de Ciencias Farmaceuticas. Lab. de Microbiologia de Alimentos]. E-mail: gianni@usp.br; Takahashi, Caroline Maki; Alterthum, Flavio [Sao Paulo Univ., SP (Brazil). Inst. de Ciencias Biomedicas. Dept. de Microbiologia

    2002-08-01

    This paper discusses the potential use of Escherichia coli KO11 in production of ethanol, based on observation that this organism can efficiently metabolize sugar complex moistures obtained from the acid hydrolysis of lignocellulose materials such as sugar-cane bagasse, corncob, corn husk, Pinus sp and oak wood.

  14. Modeling the dispersion of viable and total Escherichia coli cells in the artificial semi-enclosed bathing area of Santa Marinella (Latium, Italy).

    Science.gov (United States)

    Bonamano, S; Madonia, A; Borsellino, C; Stefanì, C; Caruso, G; De Pasquale, F; Piermattei, V; Zappalà, G; Marcelli, M

    2015-06-15

    Coastal areas are strongly affected by episodes of fecal contamination due to polluted water inflows from inadequately treated sewages. The present study aims to investigate the dispersion of Escherichia coli in the artificial semi-enclosed bathing area of Santa Marinella (Latium, Italy) through in situ samplings carried out in summer 2012 and the application of a dynamic model. Collected samples were analyzed by the Culture-Based technique and the Fluorescent Antibody method in order to estimate both the viable culturable cells and the total E. coli population, respectively. The in situ datasets were used to test the proposed modeling approach and simulate the behavior of bacteria as particles subjected, or not, to decay. Next, the flushing time and the computation of the Microbiological Potential Risk Area allowed the evaluation of the contribution of physical and biological processes to coliform dispersion and the related potential risk for bathers.

  15. Enteropathogenic Escherichia coli: foe or innocent bystander?

    Science.gov (United States)

    Hu, J; Torres, A G

    2015-08-01

    Enteropathogenic Escherichia coli (EPEC) remain one the most important pathogens infecting children and they are one of the main causes of persistent diarrhoea worldwide. Historically, typical EPEC (tEPEC), defined as those isolates with the attaching and effacement (A/E) genotype (eae(+)), which possess bfpA(+) and lack the stx(-) genes are found strongly associated with diarrhoeal cases. However, occurrence of atypical EPEC (aEPEC; eae(+)bfpA(-)stx(-)) in diarrhoeal and asymptomatic hosts has made investigators question the role of these pathogens in human disease. Current epidemiological data are helping to answer the question of whether EPEC is mainly a foe or an innocent bystander during infection.

  16. Escherichia coli fliAZY operon.

    OpenAIRE

    Mytelka, D S; Chamberlin, M J

    1996-01-01

    We have cloned the Escherichia coli fliAZY operon, which contains the fliA gene (the alternative sigma factor sigma F) and two novel genes, fliZ and fliY. Transcriptional mapping of this operon shows two start sites, one of which is preceded by a canonical E sigma F-dependent consensus and is dependent on sigma F for expression in vivo and in vitro. We have overexpressed and purified sigma F and demonstrated that it can direct core polymerase to E sigma F-dependent promoters. FliZ and FliY ar...

  17. Genes under positive selection in Escherichia coli

    DEFF Research Database (Denmark)

    Petersen, Lise; Bollback, Jonathan P; Dimmic, Matt

    2007-01-01

    We used a comparative genomics approach to identify genes that are under positive selection in six strains of Escherichia coli and Shigella flexneri, including five strains that are human pathogens. We find that positive selection targets a wide range of different functions in the E. coli genome......, including cell surface proteins such as beta barrel porins, presumably because of the involvement of these genes in evolutionary arms races with other bacteria, phages, and/or the host immune system. Structural mapping of positively selected sites on trans-membrane beta barrel porins reveals...... that the residues under positive selection occur almost exclusively in the extracellular region of the proteins that are enriched with sites known to be targets of phages, colicins, or the host immune system. More surprisingly, we also find a number of other categories of genes that show very strong evidence...

  18. Production of recombinant avidin in Escherichia coli.

    Science.gov (United States)

    Airenne, K J; Sarkkinen, P; Punnonen, E L; Kulomaa, M S

    1994-06-24

    A recombinant avidin (re-Avd), containing amino acids (aa) 1-123 of the native chicken egg-white Avd, was produced in Escherichia coli. When cells were grown at 37 degrees C production was over 1 microgram/ml, due to altering the codon preference of the first ten codons. The re-Avd was recovered as a soluble protein from cells grown at 25 or 30 degrees C, whereas at 37 degrees C it was mostly insoluble in inclusion bodies. Our results indicated that, despite the potentially harmful biotin-binding activity of Avd, it is possible to produce biologically active Avd in E. coli which then can easily be purified by affinity chromatography on a biotin column in a single step.

  19. Escherichia coli O157:H7.

    Science.gov (United States)

    Mead, P S; Griffin, P M

    1998-10-10

    Escherichia coli O157 was first identified as a human pathogen in 1982. One of several Shiga toxin-producing serotypes known to cause human illness, the organism probably evolved through horizontal acquisition of genes for Shiga toxins and other virulence factors. E. coli O157 is found regularly in the faeces of healthy cattle, and is transmitted to humans through contaminated food, water, and direct contact with infected people or animals. Human infection is associated with a wide range of clinical illness, including asymptomatic shedding, non-bloody diarrhoea, haemorrhagic colitis, haemolytic uraemic syndrome, and death. Since laboratory practices vary, physicians need to know whether laboratories in their area routinely test for E. coli O157 in stool specimens. Treatment with antimicrobial agents remains controversial: some studies suggest that treatment may precipitate haemolytic uraemic syndrome, and other studies suggest no effect or even a protective effect. Physicians can help to prevent E. coli O157 infections by counselling patients about the hazards of consuming undercooked ground meat or unpasteurised milk products and juices, and about the importance of handwashing to prevent the spread of diarrhoeal illness, and by informing public-health authorities when they see unusual numbers of cases of bloody diarrhoea or haemolytic uraemic syndrome.

  20. 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.

  1. Escherichia coli as a bioreporter in ecotoxicology.

    Science.gov (United States)

    Robbens, Johan; Dardenne, Freddy; Devriese, Lisa; De Coen, Wim; Blust, Ronny

    2010-11-01

    Ecotoxicological assessment relies to a large extent on the information gathered with surrogate species and the extrapolation of test results across species and different levels of biological organisation. Bacteria have long been used as a bioreporter for genotoxic testing and general toxicity. Today, it is clear that bacteria have the potential for screening of other toxicological endpoints. Escherichia coli has been studied for years; in-depth knowledge of its biochemistry and genetics makes it the most proficient prokaryote for the development of new toxicological assays. Several assays have been designed with E. coli as a bioreporter, and the recent trend to develop novel, better advanced reporters makes bioreporter development one of the most dynamic in ecotoxicology. Based on in-depth knowledge of E. coli, new assays are being developed or existing ones redesigned, thanks to the availability of new reporter genes and new or improved substrates. The technological evolution towards easier and more sensitive detection of different gene products is another important aspect. Often, this requires the redesign of the bacterium to make it compatible with the novel measuring tests. Recent advances in surface chemistry and nanoelectronics open the perspective for advanced reporter based on novel measuring platforms and with an online potential. In this article, we will discuss the use of E. coli-based bioreporters in ecotoxicological applications as well as some innovative sensors awaited for the future.

  2. Comparison of virulence factors and expression of specific genes between uropathogenic Escherichia coli and avian pathogenic E. coli in a murine urinary tract infection model and a chicken challenge model.

    Science.gov (United States)

    Zhao, Lixiang; Gao, Song; Huan, Haixia; Xu, Xiaojing; Zhu, Xiaoping; Yang, Weixia; Gao, Qingqing; Liu, Xiufan

    2009-05-01

    Avian pathogenic Escherichia coli (APEC) and uropathogenic E. coli (UPEC) establish infections in extraintestinal habitats of different hosts. As the diversity, epidemiological sources and evolutionary origins of extraintestinal pathogenic E. coli (ExPEC) are so far only partially defined, in the present study,100 APEC isolates and 202 UPEC isolates were compared by their content of virulence genes and phylogenetic groups. The two groups showed substantial overlap in terms of their serogroups, phylogenetic groups and virulence genotypes, including their possession of certain genes associated with large transmissible plasmids of APEC. In a chicken challenge model, both UPEC U17 and APEC E058 had similar LD(50), demonstrating that UPEC U17 had the potential to cause significant disease in poultry. To gain further information about the similarities between UPEC and APEC, the in vivo expression of 152 specific genes of UPEC U17 and APEC E058 in both a murine urinary tract infection (UTI) model and a chicken challenge model was compared with that of these strains grown statically to exponential phase in rich medium. It was found that in the same model (murine UTI or chicken challenge), various genes of UPEC U17 and APEC E058 showed a similar tendency of expression. Several iron-related genes were upregulated in the UTI model and/or chicken challenge model, indicating that iron acquisition is important for E. coli to survive in blood or the urinary tract. Based on these results, the potential for APEC to act as human UPEC or as a reservoir of virulence genes for UPEC should be considered. Further, this study compared the transcriptional profile of virulence genes among APEC and UPEC in vivo.

  3. ANTIMICIROBIAL SUSCEPTIBILITY PATTERNS OF Escherichia coli ...

    African Journals Online (AJOL)

    DR. AMINU

    aetiological agents of diarrhoea diseases of humans in developing ... Pathogenic organisms have developed a number of elaborate .... reported that E.coli isolated from animals haboured plasmids .... coil 0157:H7 as a model of entry of a new.

  4. Biogenesis of inner membrane proteins in Escherichia coli.

    Science.gov (United States)

    Luirink, Joen; Yu, Zhong; Wagner, Samuel; de Gier, Jan-Willem

    2012-06-01

    The inner membrane proteome of the model organism Escherichia coli is composed of inner membrane proteins, lipoproteins and peripherally attached soluble proteins. Our knowledge of the biogenesis of inner membrane proteins is rapidly increasing. This is in particular true for the early steps of biogenesis - protein targeting to and insertion into the membrane. However, our knowledge of inner membrane protein folding and quality control is still fragmentary. Furthering our knowledge in these areas will bring us closer to understand the biogenesis of individual inner membrane proteins in the context of the biogenesis of the inner membrane proteome of Escherichia coli as a whole. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.

  5. Risk assessment modelling of fecal shedding caused by extended-spectrum cephalosporin-resistant Escherichia coli transmitted through waste milk fed to dairy pre-weaned calves.

    Science.gov (United States)

    Awosile, Babafela B; Smith, Ben A

    2017-10-04

    Waste milk feeding is a common practice in dairy operations. Regardless of the benefits of this practice to the dairy farmers, concerns from the potential dissemination of antimicrobial-resistant bacteria through the gut and subsequent shedding by calves into the environment are increasing. In this study, we employed Monte Carlo simulation to assess the risk of shedding extended-spectrum cephalosporin-resistant Escherichia coli (ESC-R E. coli) caused by waste milk feeding in pre-weaned calves using an exponential dose-response model fit to data for E. coli O157:H7 in cattle. Data from pertinent studies were included in our model to predict the risk of shedding. The median (5th and 95th percentiles) for the daily risk of shedding ESC-R E. coli by calves fed only contaminated waste milk was predicted to be 2.9 × 10(-3) (2.1 × 10(-3), 3.7 × 10(-3)), representing a median daily risk of 29 out of 10,000 calves shedding ESC-R E. coli due to exclusive feeding of waste milk containing ESC-R E. coli. This median value was reduced by 94% when accounting for the proportion of waste milk that does not contain ESC-R E. coli. The overall risk of shedding ESC-R E. coli through the pre-weaning period for farms that feed waste milk to calves was 5.7 × 10(-3) (2.4 × 10(-3), 1.1 × 10(-2)), representing 57 out of 10,000 calves. When accounting for the proportion of farms that do not feed waste milk, the pre-weaning period risk was reduced by 23%. By varying the prevalence of ESC-R E. coli in waste milk using values of 3, 1.5, and 1%, the daily risk of shedding decreased by factors of 50, 65, and 82%, respectively, which supports the reduction of contamination or discontinuation of feeding waste milk containing ESC-R E. coli as major mitigation measures to reduce the risk of shedding caused by ingestion of resistant bacteria. It is anticipated that the effects of antimicrobial residues in waste milk, which was not considered herein due to lack of data, would further increase

  6. 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....

  7. Escherichia coli O157 infections and unpasteurised milk

    NARCIS (Netherlands)

    Allerberger, F; Wagner, M; Schweiger, P; Rammer, H P; Resch, A; Dierich, M P; Friedrich, A W; Karch, H

    2001-01-01

    We report on two children with Escherichia coli O157 infection, one of whom developed haemolytic uraemic syndrome (HUS). Both had drunk raw cows or goats milk in the week before their illness. Molecular subtyping identified a sorbitol fermenting Escherichia coli O157:H isolate from a dairy cow. This

  8. Escherichia coli O157 infections and unpasteurised milk

    NARCIS (Netherlands)

    Allerberger, F; Wagner, M; Schweiger, P; Rammer, H P; Resch, A; Dierich, M P; Friedrich, A W; Karch, H

    2001-01-01

    We report on two children with Escherichia coli O157 infection, one of whom developed haemolytic uraemic syndrome (HUS). Both had drunk raw cows or goats milk in the week before their illness. Molecular subtyping identified a sorbitol fermenting Escherichia coli O157:H isolate from a dairy cow. This

  9. Production of glycoprotein vaccines in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Ihssen Julian

    2010-08-01

    Full Text Available Abstract Background Conjugate vaccines in which polysaccharide antigens are covalently linked to carrier proteins belong to the most effective and safest vaccines against bacterial pathogens. State-of-the art production of conjugate vaccines using chemical methods is a laborious, multi-step process. In vivo enzymatic coupling using the general glycosylation pathway of Campylobacter jejuni in recombinant Escherichia coli has been suggested as a simpler method for producing conjugate vaccines. In this study we describe the in vivo biosynthesis of two novel conjugate vaccine candidates against Shigella dysenteriae type 1, an important bacterial pathogen causing severe gastro-intestinal disease states mainly in developing countries. Results Two different periplasmic carrier proteins, AcrA from C. jejuni and a toxoid form of Pseudomonas aeruginosa exotoxin were glycosylated with Shigella O antigens in E. coli. Starting from shake flask cultivation in standard complex medium a lab-scale fed-batch process was developed for glycoconjugate production. It was found that efficiency of glycosylation but not carrier protein expression was highly susceptible to the physiological state at induction. After induction glycoconjugates generally appeared later than unglycosylated carrier protein, suggesting that glycosylation was the rate-limiting step for synthesis of conjugate vaccines in E. coli. Glycoconjugate synthesis, in particular expression of oligosaccharyltransferase PglB, strongly inhibited growth of E. coli cells after induction, making it necessary to separate biomass growth and recombinant protein expression phases. With a simple pulse and linear feed strategy and the use of semi-defined glycerol medium, volumetric glycoconjugate yield was increased 30 to 50-fold. Conclusions The presented data demonstrate that glycosylated proteins can be produced in recombinant E. coli at a larger scale. The described methodologies constitute an important step

  10. Synergistic effects in mixed Escherichia coli biofilms

    DEFF Research Database (Denmark)

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

    2006-01-01

    the strongest effects was most often linked to conjugative transmission of natural plasmids carried by the E. coli isolates (70%). Thus, the capacity of an isolate to promote the biofilm through cocultivation was (i) transferable to the K-12 strain, (ii) was linked with the acquisition of conjugation genes...... promotion in this system is not dependent on the laboratory strain and that the described model system could provide relevant insights on mechanisms of biofilm development in natural E. coli populations....

  11. Prevalence of diarrheagenic Escherichia coli in suckling rabbits

    OpenAIRE

    2016-01-01

    Diarrheagenic Escherichia coli (E. coli) in suckling rabbit causes collibacillosis, which is characterized by sever yellow diarrhea, poor growth and high mortalities. This study was undertaken to investigate the prevalence of diarrheagenic E. coli in suckling rabbits in Egypt. Additionally, expression of some virulence-associated genes in the isolated E. coli serotypes were examined using the polymerase chain reaction. Finally, antibiogram of the identified E. coli serotypes was also investig...

  12. Methane production from kitchen waste using Escherichia coli.

    Science.gov (United States)

    Jayalakshmi, S; Joseph, Kurian; Sukumaran, V

    2007-04-01

    Escherichia coli (E. coli) strain isolated from biogas plant sludge was examined for its ability to enhance biogas from kitchen waste during solid phase anaerobic digestion. The laboratory experiments were conducted for total solid concentrations of 20% and 22%. Kitchen waste was characterized for physico-chemical parameters and laboratory experiments were conducted with and without E. coli strain. It was found that the reactor with E. coli produced 17% more biogas than the reactors that are operated without E. coli strain.

  13. Validation of a disease model in Japanese quail (Coturnix coturnix japonica) with the use of Escherichia coli serogroup O2 isolated from a turkey.

    Science.gov (United States)

    Nain, Sukhbir; Smits, Judit E G

    2011-07-01

    This study established a disease model and protocol for bacterial challenge with Escherichia coli serogroup O2 strain EC317 in Japanese quail. Five groups of 10 birds each were injected subcutaneously in the breast with 200 μL of a brain-heart infusion (BHI) culture containing 1 × 10(8), 1 × 10(7), 1 × 10(6), 1 × 10(5), or 1 × 10(4) colony-forming units/mL of the test organism, which had been isolated from a turkey with cellulitis and septicemia. Birds in a 6th group were controls that received sterile BHI alone. Localized lesions of cellulitis developed in all of the birds that received E. coli. The morbidity and mortality rates were highest (100%) in the birds receiving the highest dose of E. coli and decreased linearly with decreasing dose (P coli. These findings indicate that this disease challenge protocol can be used to study disease resistance and immunologic consequences of contaminant exposure or other stressors in birds.

  14. Long term effects of Escherichia coli mastitis.

    Science.gov (United States)

    Blum, Shlomo E; Heller, Elimelech D; Leitner, Gabriel

    2014-07-01

    Escherichia coli is one of the most frequently diagnosed causes of bovine mastitis, and is typically associated with acute, clinical mastitis. The objective of the present study was to evaluate the long term effects of intramammary infections by E. coli on milk yield and quality, especially milk coagulation. Twenty-four Israeli Holstein cows diagnosed with clinical mastitis due to intramammary infection by E. coli were used in this study. Mean lactation number, days in milk (DIM) and daily milk yield (DMY) at the time of infection was 3.3 ± 1.3, 131.7 days ± 78.6 and 45.7 L ± 8.4, respectively. DMY, milk constituents, somatic cells count (SCC), differential leukocytes count and coagulation parameters were subsequently assessed. Two patterns of inflammation were identified: 'short inflammation', characterized by 15% decrease in DMY and >30 days to reach a new maximum DMY (n = 19). The estimated mean loss of marketable milk during the study was 200 L/cow for 'short inflammation' cases, and 1,500 L/cow for 'long inflammation' ones. Significant differences between 'short' and 'long inflammation' effects were found in almost all parameters studied. Long-term detrimental effects on milk quality were found regardless of clinical or bacteriological cure of affected glands.

  15. Cyclomodulins in urosepsis strains of Escherichia coli.

    Science.gov (United States)

    Dubois, Damien; Delmas, Julien; Cady, Anne; Robin, Frédéric; Sivignon, Adeline; Oswald, Eric; Bonnet, Richard

    2010-06-01

    Determinants of urosepsis in Escherichia coli remain incompletely defined. Cyclomodulins (CMs) are a growing functional family of toxins that hijack the eukaryotic cell cycle. Four cyclomodulin types are actually known in E. coli: cytotoxic necrotizing factors (CNFs), cycle-inhibiting factor (Cif), cytolethal distending toxins (CDTs), and the pks-encoded toxin. In the present study, the distribution of CM-encoding genes and the functionality of these toxins were investigated in 197 E. coli strains isolated from patients with community-acquired urosepsis (n = 146) and from uninfected subjects (n = 51). This distribution was analyzed in relation to the phylogenetic background, clinical origin, and antibiotic resistance of the strains. It emerged from this study that strains harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, urosepsis origin (P, urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks- or cnf1-harboring strains were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all strains harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin.

  16. Escherichia coli enteroagregativa como agente provocador de diarreia persistente: modelo experimental utilizando microscopia óptica de luz Escherichia coli enteroagregativa como agente provocador de diarrea persistente: modelo experimental utilizando microscopia óptica de luz Enteroaggregative Escherichia coli as a cause of persistent diarrhea: an experimental model using light microscopy

    Directory of Open Access Journals (Sweden)

    Jacy Alves B. de Andrade

    2011-03-01

    Full Text Available OBJETIVO: Avaliar interações de amostras de Escherichia coli enteroagregativa com tecido intestinal humano, a fim de documentar potenciais alterações em diferentes regiões do trato digestivo. MÉTODOS: Amostras de Escherichia coli enteroagregativa isoladas das fezes de crianças com diarreia persistente e a amostra protótipo 042, isolada de uma criança com diarreia em Lima, no Peru (controle positivo, foram analisadas por microscopia óptica de luz após semeadura em cultura de orgão in vitro de fragmentos de mucosa ileal e colônica. Foram analisadas as interações entre as diferentes cepas de Escherichia coli enteroagregativa e as mucosas ileal e colônica. RESULTADOS: A análise por microscopia óptica de luz indicou associação destes micro-organismos com o epitélio, provocando alterações. As cepas estudadas aderiram a ambas as regiões avaliadas (intestino delgado distal e grosso e causaram alterações, especialmente naquelas áreas onde interagiram diretamente com o epitélio. No íleo, algumas regiões mostraram internalização secundária. CONCLUSÕES: Esses agentes podem causar diarreia persistente por meio de alterações no intestino delgado, no qual ocorrem as funções digestivo-absortivas. As lesões inflamatórias descritas na mucosa colônica poderiam explicar a colite mostrada em algumas crianças infectadas por Escherichia coli enteroagregativa.OBJETIVO: Evaluar interacciones de muestras de Escherichia coli enteroagregativa (EAEC con tejido intestinal humano, a fin de documentar potenciales alteraciones en distintas regiones del tracto digestivo (intestino delgado distal e intestino grueso y definir, con eso, su rol en la persistencia del proceso diarreico. MÉTODOS: Muestras de EAEC aislada de las heces de niños con diarrea persistente y la muestra prototipo 042, aislada de un niño con diarrea en Lima, Perú (control positivo fueron analizadas por microscopía óptica de luz (ML después de siembra en cultura

  17. Measuring Escherichia coli Gene Expression during Human Urinary Tract Infections

    Science.gov (United States)

    Mobley, Harry L. T.

    2016-01-01

    Extraintestinal Escherichia coli (E. coli) evolved by acquisition of pathogenicity islands, phage, plasmids, and DNA segments by horizontal gene transfer. Strains are heterogeneous but virulent uropathogenic isolates more often have specific fimbriae, toxins, and iron receptors than commensal strains. One may ask whether it is the virulence factors alone that are required to establish infection. While these virulence factors clearly contribute strongly to pathogenesis, bacteria must survive by metabolizing nutrients available to them. By constructing mutants in all major metabolic pathways and co-challenging mice transurethrally with each mutant and the wild type strain, we identified which major metabolic pathways are required to infect the urinary tract. We must also ask what else is E. coli doing in vivo? To answer this question, we examined the transcriptome of E. coli CFT073 in the murine model of urinary tract infection (UTI) as well as for E. coli strains collected and analyzed directly from the urine of patients attending either a urology clinic or a university health clinic for symptoms of UTI. Using microarrays and RNA-seq, we measured in vivo gene expression for these uropathogenic E. coli strains, identifying genes upregulated during murine and human UTI. Our findings allow us to propose a new definition of bacterial virulence. PMID:26784237

  18. Transport of Escherichia coli in saturated porous media

    NARCIS (Netherlands)

    Foppen, J.W.A.

    2007-01-01

    Over de manier waarop de bacterie en tevens meest bekende fecale indicator soort Escherichia coli getransporteerd wordt in grondwater is relatief weinig bekend. In deze studie wordt de verwijdering van E. coli uit grondwater ten gevolge van E. coli - sediment interacties bestudeerd en modelmatig

  19. Transport of Escherichia coli in saturated porous media

    NARCIS (Netherlands)

    Foppen, J.W.A.

    2007-01-01

    Over de manier waarop de bacterie en tevens meest bekende fecale indicator soort Escherichia coli getransporteerd wordt in grondwater is relatief weinig bekend. In deze studie wordt de verwijdering van E. coli uit grondwater ten gevolge van E. coli - sediment interacties bestudeerd en modelmatig ge

  20. 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...

  1. Transport of Escherichia coli in saturated porous media

    NARCIS (Netherlands)

    Foppen, J.W.A.

    2007-01-01

    Over de manier waarop de bacterie en tevens meest bekende fecale indicator soort Escherichia coli getransporteerd wordt in grondwater is relatief weinig bekend. In deze studie wordt de verwijdering van E. coli uit grondwater ten gevolge van E. coli - sediment interacties bestudeerd en modelmatig ge

  2. 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.

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

    OpenAIRE

    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.

  4. Growth model of Escherichia coli O157:H7 at various storage temperatures on kale treated by thermosonication combined with slightly acidic electrolyzed water.

    Science.gov (United States)

    Mansur, Ahmad Rois; Wang, Jun; Park, Myeong-Su; Oh, Deog-Hwan

    2014-01-01

    This study was conducted to investigate the disinfection efficacy of hurdle treatments (thermosonication plus slightly acidic electrolyzed water [SAcEW]) and to develop a model for describing the effect of storage temperatures (4, 10, 15, 20, 25, 30, and 35°C) on the growth of Escherichia coli O157:H7 on fresh-cut kale treated with or without (control) thermosonication combined with SAcEW. The hurdle treatments of thermosonication plus SAcEW had strong bactericidal effects against E. coli O157:H7 on kale, with approximately 3.3-log reductions. A modified Gompertz model was used to describe growth parameters such as specific growth rate (SGR) and lag time (LT) as a function of storage temperature, with high coefficients of determination (R(2) > 0.98). SGR increased and LT declined with rising temperatures in all samples. A significant difference was found between the SGR values obtained from treated and untreated samples. Secondary models were established for SGR and LT to evaluate the effects of storage temperature on the growth kinetics of E. coli O157:H7 in treated and untreated kale. Statistical evaluation was carried out to validate the performance of the developed models, based on the additional experimental data not used for the model development. The validation step indicated that the overall predictions were inside the acceptable prediction zone and had lower standard errors, indicating that this new growth model can be used to assess the risk of E. coli O157:H7 contamination on kale.

  5. Levofloxacin plus metronidazole administered once daily versus moxifloxacin monotherapy against a mixed infection of Escherichia coli and Bacteroides fragilis in an in vitro pharmacodynamic model.

    Science.gov (United States)

    Hermsen, Elizabeth D; Hovde, Laurie B; Sprandel, Kelly A; Rodvold, Keith A; Rotschafer, John C

    2005-02-01

    Moxifloxacin has been suggested as an option for monotherapy of intra-abdominal infections. Recent data support the use of a once-daily metronidazole regimen. The purpose of this study was to investigate the activity of levofloxacin (750 mg every 24 h [q24h]) plus metronidazole (1,500 mg q24h) compared with that of moxifloxacin (400 mg q24h) monotherapy in a mixed-infection model. By using an in vitro pharmacodynamic model in duplicate, Escherichia coli and Bacteroides fragilis were exposed to peak concentrations of 8.5 mg of levofloxacin/liter q24h, 32 mg of metronidazole/liter q24h, and 2 mg for moxifloxacin/liter q24h for 24 h. The activities of levofloxacin, metronidazole, moxifloxacin, and levofloxacin plus metronidazole were evaluated against E. coli, B. fragilis, and E. coli plus B. fragilis. The targeted half-lives of levofloxacin, metronidazole, and moxifloxacin were 8, 8, and 12 h, respectively. Time-kill curves were analyzed for time to 3-log killing, slope, and regrowth. Pre- and postexposure MICs were determined. The preexposure levofloxacin, metronidazole, and moxifloxacin MICs for E. coli and B. fragilis were 0.5 and 1, >64 and 0.5, and 1 and 0.25 mg/liter, respectively. Levofloxacin and moxifloxacin achieved a 3-log killing against E. coli and B. fragilis in all experiments, as did metronidazole against B. fragilis. Metronidazole did not decrease the starting inoculum of E. coli. The area under the concentration-time curve/MIC ratios for E. coli and B. fragilis were 171.7 and 85.9, respectively, for levofloxacin and 26 and 103.9, respectively, for moxifloxacin. Levofloxacin plus metronidazole exhibited the fastest rates of killing. The levofloxacin and moxifloxacin MICs for B. fragilis increased 8- to 16-fold after the organism was exposed to moxifloxacin. No other changes in the postexposure MICs were found. Levofloxacin plus metronidazole administered once daily exhibited activity similar to that of moxifloxacin against the mixed E. coli and B

  6. Initiation of Replication in Escherichia coli

    DEFF Research Database (Denmark)

    Frimodt-Møller, Jakob

    The circular chromosome of Escherichia coli is replicated by two replisomes assembled at the unique origin and moving in the opposite direction until they meet in the less well defined terminus. The key protein in initiation of replication, DnaA, facilitates the unwinding of double-stranded DNA...... to single-stranded DNA in oriC. Although DnaA is able to bind both ADP and ATP, DnaA is only active in initiation when bound to ATP. Although initiation of replication, and the regulation of this, is thoroughly investigated it is still not fully understood. The overall aim of the thesis was to investigate...... the regulation of initiation, the effect on the cell when regulation fails, and if regulation was interlinked to chromosomal organization. This thesis uncovers that there exists a subtle balance between chromosome replication and reactive oxygen species (ROS) inflicted DNA damage. Thus, failure in regulation...

  7. The eclipse period of Escherichia coli

    DEFF Research Database (Denmark)

    von Freiesleben, Ulrik; Krekling, Martin A.; Hansen, Flemming G.

    2000-01-01

    The minimal time between successive initiations on the same origin (the eclipse) in Escherichia coli was determined to be approximately 25-30 min. An inverse relationship was found between the length of the eclipse and the amount of Dam methyltransferase in the cell, indicating that the eclipse...... corresponds to the period of origin hemimethylation. The SeqA protein was absolutely required for the eclipse, and DnaA titration studies suggested that the SeqA protein prevented the binding of multiple DnaA molecules on oriC (initial complex formation). No correlation between the amount of SeqA and eclipse...... length was revealed, but increased SeqA levels affected chromosome partitioning and/or cell division. This was corroborated further by an aberrant nucleoid distribution in SeqA-deficient cells. We suggest that the SeqA protein's role in maintaining the eclipse is tied to a function in chromosome...

  8. The pangenome structure of Escherichia coli: comparative genomic analysis of E. coli commensal and pathogenic isolates.

    Science.gov (United States)

    Rasko, David A; Rosovitz, M J; Myers, Garry S A; Mongodin, Emmanuel F; Fricke, W Florian; Gajer, Pawel; Crabtree, Jonathan; Sebaihia, Mohammed; Thomson, Nicholas R; Chaudhuri, Roy; Henderson, Ian R; Sperandio, Vanessa; Ravel, Jacques

    2008-10-01

    Whole-genome sequencing has been skewed toward bacterial pathogens as a consequence of the prioritization of medical and veterinary diseases. However, it is becoming clear that in order to accurately measure genetic variation within and between pathogenic groups, multiple isolates, as well as commensal species, must be sequenced. This study examined the pangenomic content of Escherichia coli. Six distinct E. coli pathovars can be distinguished using molecular or phenotypic markers, but only two of the six pathovars have been subjected to any genome sequencing previously. Thus, this report provides a seminal description of the genomic contents and unique features of three unsequenced pathovars, enterotoxigenic E. coli, enteropathogenic E. coli, and enteroaggregative E. coli. We also determined the first genome sequence of a human commensal E. coli isolate, E. coli HS, which will undoubtedly provide a new baseline from which workers can examine the evolution of pathogenic E. coli. Comparison of 17 E. coli genomes, 8 of which are new, resulted in identification of approximately 2,200 genes conserved in all isolates. We were also able to identify genes that were isolate and pathovar specific. Fewer pathovar-specific genes were identified than anticipated, suggesting that each isolate may have independently developed virulence capabilities. Pangenome calculations indicate that E. coli genomic diversity represents an open pangenome model containing a reservoir of more than 13,000 genes, many of which may be uncharacterized but important virulence factors. This comparative study of the species E. coli, while descriptive, should provide the basis for future functional work on this important group of pathogens.

  9. Use of model super-shedders to define the role of pen floor and hide contamination in the transmission of Escherichia coli O157:H7.

    Science.gov (United States)

    Stanford, K; Stephens, T P; McAllister, T A

    2011-01-01

    Super-shedders, cattle shedding at least 10(4) cfu of Escherichia coli O157:H7 per gram of feces, increase the risks of contaminating the food chain and disseminating the organism through cattle populations. Because detecting super-shedders in cattle populations is laborious and time-consuming, a study was conducted to evaluate the role of hide and pen-floor contamination by model super shedders (MSS) in transmission of E. coli O157:H7. Steers (n = 48) negative for E. coli O157:H7 were allocated to 6 pens, with 2 replicate pens per treatment. Treatment A consisted of 3,000 g of feces inoculated with 10(6) cfu/g of a 5-strain mixture of nalidixic acid-resistant E. coli O157:H7 and spread in simulated fecal pats on the pen floor for d 0 through 4 and d 14 through 18. For treatment B, 100 g of the feces per day was spread on the perineum of 1 MSS per pen, and the remaining feces was placed on the pen floor as fecal pats similar to treatment A. Treatment C differed from B in that 50 g of feces was spread on the perineum and 50 g on the brisket of the MSS steer. Fecal samples, perineal swabs (500-cm(2) area around the anus), freshly voided fecal pats and manila rope samples were collected during a 56-d experimental period. More positive rope samples were found in treatments B and C compared with A (P = 0.05), and steers within treatments B and C were 1.3 times more likely (P = 0.05) to shed E. coli O157:H7 in their feces than steers in treatment A. Even though the number of E. coli O157:H7 introduced into pens was similar, results indicate an increased importance of hide compared with pen-floor contamination for transmission of this organism to cattle. Because cattle within treatment B were persistently colonized with E. coli O157:H7, this design should prove suitable for future studies investigating the role of super-shedders in the transmission of E. coli O157:H7.

  10. Ciprofloxacin Treatment Failure in a Murine Model of Pyelonephritis Due to an AAC(6′)-Ib-cr-Producing Escherichia coli Strain Susceptible to Ciprofloxacin In Vitro

    Science.gov (United States)

    Guillard, T.; Cambau, E.; Chau, F.; Massias, L.; de Champs, C.

    2013-01-01

    AAC(6′)-Ib-cr is a plasmid-mediated quinolone resistance mechanism described worldwide for Escherichia coli. Since it confers in vitro only a low level of resistance to ciprofloxacin, we evaluated its impact on the in vivo activity of ciprofloxacin. Isogenic strains were obtained by transferring plasmid p449, harboring aac(6′)-Ib-cr, into the quinolone-susceptible strain E. coli CFT073-RR and its D87G gyrA mutant. MICs were 0.015, 0.06, 0.25, and 0.5 μg/ml against E. coli strains CFT073-RR, CFT073-RR/p449, CFT073-RR GyrAr, and CFT073-RR GyrAr/p449, respectively. Bactericidal activity was reduced at 1× the MIC for the three resistant derivatives, while at a fixed concentration of 0.5 μg/ml, 99.9% killing was observed for all strains except E. coli CFT073-RR GyrAr/p449. In the murine model of pyelonephritis, an optimal regimen of ciprofloxacin (10 mg/kg of body weight twice a day [b.i.d.]) significantly decreased the bacterial count in the kidneys of mice infected with E. coli CFT073 (1.6 versus 4.3 log10 CFU/g of kidney compared to untreated controls; P = 0.0001), while no significant decrease was observed for E. coli CFT073-RR/p449 (2.7 versus 3.1 log10 CFU/g; P = 0.84), E. coli CFT073-RR GyrAr (4.2 versus 4.1 log10 CFU/g; P = 0.35), or E. coli CFT073-RR GyrAr/p449 (2.9 versus 3.6 log10 CFU/g; P = 0.47). While pharmacokinetic and pharmacodynamic (PK/PD) parameters accounted for ciprofloxacin failure against gyrA-containing mutants, this was not the case for the aac(6′)-Ib-cr-containing strains, suggesting an in situ hydrolysis of ciprofloxacin in the latter case. PMID:24018262

  11. Oral-derived bacterial flora defends its domain by recognizing and killing intruders--a molecular analysis using Escherichia coli as a model intestinal bacterium.

    Science.gov (United States)

    He, Xuesong; Tian, Yan; Guo, Lihong; Lux, Renate; Zusman, David R; Shi, Wenyuan

    2010-10-01

    Within the same human gastrointestinal tract, substantial differences in the bacterial species that inhabit oral cavity and intestinal tract have been noted. Previous research primarily attributed the differences to the influences of host environments and nutritional availabilities ("host habitat" effect). Our recent study indicated that, other than the host habitat effect, an existing microbial community could impose a selective pressure on incoming foreign bacterial species independent of host-mediated selection ("community selection" effect). In this study, we employed in vitro microbial floras representing microorganisms that inhabit the oral cavities and intestinal tract of mice in combination with Escherichia coli as a model intestinal bacterium and demonstrated that E. coli displays a striking community preference. It thrived when introduced into the intestinal microbial community and survived poorly in the microbial flora of foreign origin (oral community). A more detailed examination of this phenomenon showed that the oral community produced oxygen-free radicals in the presence of wild-type E. coli while mutants deficient in lipopolysaccharides (LPS) did not trigger significant production of these cell-damaging agents. Furthermore, mutants of E. coli defective in the oxidative stress response experienced a more drastic reduction in viability when cocultivated with the oral flora, while the exogenous addition of the antioxidant vitamin C was able to rescue it. We concluded that the oral-derived microbial community senses the E. coli LPS and kills the bacterium with oxygen-free radicals. This study reveals a new mechanism of community invasion resistance employed by established microflora to defend their domains.

  12. Escherichia coli in chronic inflammatory bowel diseases: An update on adherent invasive Escherichia coli pathogenicity

    Institute of Scientific and Technical Information of China (English)

    Margarita; Martinez-Medina; Librado; Jesus; Garcia-Gil

    2014-01-01

    Escherichia coli(E. coli), and particularly the adherent invasive E. coli(AIEC) pathotype, has been increasingly implicated in the ethiopathogenesis of Crohn’s disease(CD). E. coli strains with similar pathogenic features to AIEC have been associated with other intestinal disorders such as ulcerative colitis, colorectal cancer, and coeliac disease, but AIEC prevalence in these diseases remains largely unexplored. Since AIEC was described one decade ago, substantial progress has been made in deciphering its mechanisms of pathogenicity. However, the molecular bases that characterize the phenotypic properties of this pathotype are still not well resolved. A review of studies focused on E. coli populations in inflammatory bowel disease(IBD) is presented here and we discuss about the putative role of this species on each IBD subtype. Given the relevance of AIEC in CD pathogenesis, we present the latest research findings concerning AIEC host-microbe interactions and pathogenicity. We also review the existing data regarding the prevalence and abundance of AIEC in CD and its association with other intestinal diseases from humans and animals, in order to discuss the AIEC disease- and hostspecificity. Finally, we highlight the fact that dietarycomponents frequently found in industrialized countries may enhance AIEC colonization in the gut, which merits further investigation and the implementation of preventative measures.

  13. The genetic basis of Escherichia coli pathoadaptation to macrophages.

    Directory of Open Access Journals (Sweden)

    Migla Miskinyte

    Full Text Available Antagonistic interactions are likely important driving forces of the evolutionary process underlying bacterial genome complexity and diversity. We hypothesized that the ability of evolved bacteria to escape specific components of host innate immunity, such as phagocytosis and killing by macrophages (MΦ, is a critical trait relevant in the acquisition of bacterial virulence. Here, we used a combination of experimental evolution, phenotypic characterization, genome sequencing and mathematical modeling to address how fast, and through how many adaptive steps, a commensal Escherichia coli (E. coli acquire this virulence trait. We show that when maintained in vitro under the selective pressure of host MΦ commensal E. coli can evolve, in less than 500 generations, virulent clones that escape phagocytosis and MΦ killing in vitro, while increasing their pathogenicity in vivo, as assessed in mice. This pathoadaptive process is driven by a mechanism involving the insertion of a single transposable element into the promoter region of the E. coli yrfF gene. Moreover, transposition of the IS186 element into the promoter of Lon gene, encoding an ATP-dependent serine protease, is likely to accelerate this pathoadaptive process. Competition between clones carrying distinct beneficial mutations dominates the dynamics of the pathoadaptive process, as suggested from a mathematical model, which reproduces the observed experimental dynamics of E. coli evolution towards virulence. In conclusion, we reveal a molecular mechanism explaining how a specific component of host innate immunity can modulate microbial evolution towards pathogenicity.

  14. Escherichia coli biofilms: Accepting the therapeutic challenges

    Directory of Open Access Journals (Sweden)

    Trupti Bajpai

    2016-01-01

    Full Text Available Background: Urinary tract infections (UTI′s are a major public health concern globally. Recurrent UTI′s that are predominantly caused by uropathogenic Escherichia coli′s forms biofilm that is an intracellular, structured bacterial community, enclosed in a self-produced matrix, adherent to an inert, or living surface. Biofilm physiology is characterized by increased tolerance to stress, antibiotics, and immunological defenses, which is at the origin of their resilience in most medical and industrial settings. Materials and Methods: The present prospective study was carried out from December 2013 to May 2014 in the Department of Microbiology of a Teaching Tertiary Care hospital located in central India. A total of 100 consecutive, nonrepetitive E. coli isolates were subjected to biofilm formation study by Christensen′s tube adherence method. All the isolates were also subjected to antimicrobial susceptibility testing by Kirby-Bauer disc diffusion method in accordance with the Clinical Laboratory Standard Institute 2013 guidelines. Results and Discussion: Out of the 100 E. coli isolates studied, 62 (62% were positive for biofilm formation. High percentage of resistance was detected in isolates among the male inpatient group. Overall drug resistance was found to be very high among both biofilm as well as nonbiofilm forming isolates indicating excessive drug resistance among both community and hospital organisms. Conclusion: A greater understanding of the nature of biofilm organisms in chronic UTI′s would help in the development of novel and more effective treatments for these problematic diseases.

  15. Expanding ester biosynthesis in Escherichia coli.

    Science.gov (United States)

    Rodriguez, Gabriel M; Tashiro, Yohei; Atsumi, Shota

    2014-04-01

    To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l(-1)). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.

  16. The crystal structure Escherichia coli Spy.

    Science.gov (United States)

    Kwon, Eunju; Kim, Dong Young; Gross, Carol A; Gross, John D; Kim, Kyeong Kyu

    2010-11-01

    Escherichia coli spheroplast protein y (EcSpy) is a small periplasmic protein that is homologous with CpxP, an inhibitor of the extracytoplasmic stress response. Stress conditions such as spheroplast formation induce the expression of Spy via the Cpx or the Bae two-component systems in E. coli, though the function of Spy is unknown. Here, we report the crystal structure of EcSpy, which reveals a long kinked hairpin-like structure of four α-helices that form an antiparallel dimer. The dimer contains a curved oval shape with a highly positively charged concave surface that may function as a ligand binding site. Sequence analysis reveals that Spy is highly conserved over the Enterobacteriaceae family. Notably, three conserved regions that contain identical residues and two LTxxQ motifs are placed at the horizontal end of the dimer structure, stabilizing the overall fold. CpxP also contains the conserved sequence motifs and has a predicted secondary structure similar to Spy, suggesting that Spy and CpxP likely share the same fold.

  17. Biosynthesis of ethylene glycol in Escherichia coli.

    Science.gov (United States)

    Liu, Huaiwei; Ramos, Kristine Rose M; Valdehuesa, Kris Niño G; Nisola, Grace M; Lee, Won-Keun; Chung, Wook-Jin

    2013-04-01

    Ethylene glycol (EG) is an important platform chemical with steadily expanding global demand. Its commercial production is currently limited to fossil resources; no biosynthesis route has been delineated. Herein, a biosynthesis route for EG production from D-xylose is reported. This route consists of four steps: D-xylose → D-xylonate → 2-dehydro-3-deoxy-D-pentonate → glycoaldehyde → EG. Respective enzymes, D-xylose dehydrogenase, D-xylonate dehydratase, 2-dehydro-3-deoxy-D-pentonate aldolase, and glycoaldehyde reductase, were assembled. The route was implemented in a metabolically engineered Escherichia coli, in which the D-xylose → D-xylulose reaction was prevented by disrupting the D-xylose isomerase gene. The most efficient construct produced 11.7 g L(-1) of EG from 40.0 g L(-1) of D-xylose. Glycolate is a carbon-competing by-product during EG production in E. coli; blockage of glycoaldehyde → glycolate reaction was also performed by disrupting the gene encoding aldehyde dehydrogenase, but from this approach, EG productivity was not improved but rather led to D-xylonate accumulation. To channel more carbon flux towards EG than the glycolate pathway, further systematic metabolic engineering and fermentation optimization studies are still required to improve EG productivity.

  18. Escherichia coli Pathotypes Occupy Distinct Niches in the Mouse Intestine

    OpenAIRE

    Jessica P Meador; Caldwell, Matthew E.; Cohen, Paul S.; Conway, Tyrrell

    2014-01-01

    Since the first step of the infection process is colonization of the host, it is important to understand how Escherichia coli pathogens successfully colonize the intestine. We previously showed that enterohemorrhagic O157:H7 strain E. coli EDL933 colonizes a niche in the streptomycin-treated mouse intestine that is distinct from that of human commensal strains, which explains how E. coli EDL933 overcomes colonization resistance imparted by some, but not all, commensal E. coli strains. Here we...

  19. Construction and Experimental Validation of a Quantitative Kinetic Model of Nitric Oxide Stress in Enterohemorrhagic Escherichia coli O157:H7

    Directory of Open Access Journals (Sweden)

    Jonathan L. Robinson

    2016-02-01

    Full Text Available Enterohemorrhagic Escherichia coli (EHEC are responsible for large outbreaks of hemorrhagic colitis, which can progress to life-threatening hemolytic uremic syndrome (HUS due to the release of Shiga-like toxins (Stx. The presence of a functional nitric oxide (NO· reductase (NorV, which protects EHEC from NO· produced by immune cells, was previously found to correlate with high HUS incidence, and it was shown that NorV activity enabled prolonged EHEC survival and increased Stx production within macrophages. To enable quantitative study of EHEC NO· defenses and facilitate the development of NO·-potentiating therapeutics, we translated an existing kinetic model of the E. coli K-12 NO· response to an EHEC O157:H7 strain. To do this, we trained uncertain model parameters on measurements of [NO·] and [O2] in EHEC cultures, assessed parametric and prediction uncertainty with the use of a Markov chain Monte Carlo approach, and confirmed the predictive accuracy of the model with experimental data from genetic mutants lacking NorV or Hmp (NO· dioxygenase. Collectively, these results establish a methodology for the translation of quantitative models of NO· stress in model organisms to pathogenic sub-species, which is a critical step toward the application of these models for the study of infectious disease.

  20. Modelling the survival of Escherichia coli O157:H7 on raw portioned tomatoes, inoculated with Aspergillus fumigatus and Emericella nidulans.

    Science.gov (United States)

    Cardillo, Daniela; Bevilacqua, Antonio; Cibelli, Francesca; Altieri, Clelia; Sinigaglia, Milena

    2009-01-01

    The metabiotic interactions occurring among two fungi (Aspergillus fumigatus and Emericella nidulans) and Escherichia coli O157:H7 on raw portioned tomatoes were studied. Tomatoes, preinoculated with the moulds and inoculated with the pathogen, were packaged in air and stored at 4, 8 and 12( composite function)C for 9 days; pathogen cell number and pH were monitored throughout the storage and the data were modeled using three different equations (Geeraerd, Weibull, and modified Weibull), to assess the shoulder length, the 1-log reduction time, and the death time. Both A. fumigatus and E. nidulans increased the survival of E. coli O157:H7 through the prolongation of the shoulder length; in contrast, the death time was significantly increased. The results of this paper suggested that the metabiotic interactions aspergilli/E. coli O 157:H7 could be of public concern, as the consumption of tomatoes (or other fruits and vegetables) contaminated both by the moulds and the pathogen is a possible scenario.

  1. Attachment of Escherichia coli and enterococci to particles in runoff.

    Science.gov (United States)

    Soupir, Michelle L; Mostaghimi, Saied; Dillaha, Theo

    2010-01-01

    Association of Escherichia coli and enterococci with particulates present in runoff from erodible soils has important implications for modeling the fate and transport of bacteria from agricultural sources and in the selection of management practices to reduce bacterial movement to surface waters. Three soils with different textures were collected from the Ap horizon (silty loam, silty clay loam, and loamy fine sand), placed in portable box plots, treated with standard cowpats, and placed under a rainfall simulator. Rainfall was applied to the plots until saturation-excess flow occurred for 30 min, and samples were collected 10, 20, and 30 min after initiation of the runoff event. The attachment of E. coli and enterococci to particles present in runoff was determined by a screen filtration and centrifugation procedure. Percentage of E. coli and enterococci attached to particulates in runoff ranged from 28 to 49%, with few statistically significant differences in attachment among the three soils. Similar partitioning release patterns were observed between E. coli and enterococci from the silty loam (r = 0.57) and silty clay loam soils (r = 0.60). At least 60% of all attached E. coli and enterococci were associated particles within an 8- to 62-microm particle size category. The results indicate that the majority of fecal bacteria attach to and are transported with manure colloids in sediment-laden flow regardless of the soil texture.

  2. A new kinetic model for thermal inactivation of microorganisms: development and validation using Escherichia coli O157:H7 as a test organism.

    Science.gov (United States)

    Huang, L; Juneja, V K

    2001-12-01

    A new kinetic model has been proposed to simulate the nonlinear behavior of survivor curves frequently observed in thermal inactivation of microorganisms. This model incorporates a time component into the first-order inactivation kinetics and is capable of describing the linear, convex, and concave survivor curves. The model was validated using Escherichia coli O157:H7 as a test microorganism. Ground beef (93% lean) samples inoculated to 10(7) to 10(8) CFU/g of meat were subjected to immersion heating at 55, 57.5, 60, 62.5, and 65 degrees C, respectively, in a water bath. All the survivor curves in this study showed upward concavity. Linear and nonlinear regressions were used to fit the survivor curves to the linear first-order inactivation kinetics and the proposed model. Analyses showed that the new kinetic model provides a much better estimate of the thermal inactivation behavior of E. coli O157:H7 in ground beef.

  3. Application of the Vertex Exchange Method to estimate a semi-parametric mixture model for the MIC density of Escherichia coli isolates tested for susceptibility against ampicillin.

    Science.gov (United States)

    Jaspers, Stijn; Verbeke, Geert; Böhning, Dankmar; Aerts, Marc

    2016-01-01

    In the last decades, considerable attention has been paid to the collection of antimicrobial resistance data, with the aim of monitoring non-wild-type isolates. This monitoring is performed based on minimum inhibition concentration (MIC) values, which are collected through dilution experiments. We present a semi-parametric mixture model to estimate the entire MIC density on the continuous scale. The parametric first component is extended with a non-parametric second component and a new back-fitting algorithm, based on the Vertex Exchange Method, is proposed. Our data example shows how to estimate the MIC density for Escherichia coli tested for ampicillin and how to use this estimate for model-based classification. A simulation study was performed, showing the promising behavior of the new method, both in terms of density estimation as well as classification.

  4. Kinetic Modeling of Ethanol Batch Fermentation by Escherichia Coli FBWHR Using Hot-Water Sugar Maple Wood Extract Hydrolyzate as Substrate

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2014-12-01

    Full Text Available A recombinant strain of Escherichia coli FBWHR was used for ethanol fermentation from hot-water sugar maple wood extract hydrolyzate in batch experiments. Kinetic studies of cell growth, sugar utilization and ethanol production were investigated at different initial total sugar concentrations of wood extract hydrolyzate. The highest ethanol concentration of 24.05 g/L was obtained using an initial total sugar concentration of 70.30 g/L. Unstructured models were developed to describe cell growth, sugar utilization and ethanol production and validated by comparing the predictions of model and experimental data. The results from this study could be expected to provide insights into the process performance, optimize the process and aid in the design of processes for large-scale production of ethanol fermentation from woody biomass.

  5. MarA, SoxS and Rob function as virulence factors in an Escherichia coli murine model of ascending pyelonephritis.

    Science.gov (United States)

    Casaz, Paul; Garrity-Ryan, Lynne K; McKenney, David; Jackson, Caroline; Levy, Stuart B; Tanaka, S Ken; Alekshun, Michael N

    2006-12-01

    MarA, SoxS and Rob are transcription factors belonging to the AraC family. While these proteins have been associated historically with control of multiple antibiotic resistance, and tolerance to oxidative stress agents and organic solvents, only a paucity of experimental data support a role in regulating virulence. Clinical Escherichia coli isolates, and isogenic strains lacking marA, soxS and rob, were studied in a murine model of ascending pyelonephritis, which is a clinically relevant model of urinary tract infection. Organisms lacking all three transcription factors (triple knockouts) were significantly less virulent than parental strains, and complementation studies demonstrated that the addition of marA, soxS and rob individually restored wild-type virulence in the triple-knockout strain. Deletion of soxS or rob alone was more detrimental than the removal of marA. Thus, all three proteins contribute to virulence in vivo.

  6. General considerations regarding the infections with the Escherichia coli pathogen

    Directory of Open Access Journals (Sweden)

    Marius Necşulescu

    2017-04-01

    Full Text Available Escherichia coli is the species of the genus Escherichia with the greatest epidemiological impact. Escherichia coli infections are found mainly in places with poor hygiene; the infants with ages between 1 and 3 years old are included in the category with the highest risk. It is a "fecal-oral" transmission mechanism as a result of consumption of contaminated food or water, or by "dirty hands". The foods most commonly implicated in the transmission of the infection are unpasteurized milk and milk products, beef, especially the one insufficiently cooked, unpasteurized fruit juice, lettuce and insufficiently washed vegetables. The disease has been reported worldwide, being described numerous episodes of infection with Escherichia coli that caused multiple illnesses and deaths. Escherichia coli has three types of antigens: antigen "O" (somatic, antigen "H" (flagella and antigen "K" (capsular. Clinical manifestations are present in the form of non-specific diarrhea, a dysentery form of enteritis, choleriform enteritis, hemorrhagic colitis and hemolytic uremic syndrome (HUS. The Escherichia coli infection diagnosis is made by identifying the etiologic agent and/or by highlighting the VTI toxin in the feces. The treatment consists in precautionary antibiotherapy, hydrodynamics and electrolyte rebalancing, blood transfusions and dialysis, if in the case of renal failure. The prevention of infections with Escherichia coli is achieved by personal hygiene, food hygiene and work hygiene.

  7. Efficacy of amoxycillin-clavulanate in an experimental model of murine pneumonia caused by AmpC-non-hyperproducing clinical isolates of Escherichia coli resistant to cefoxitin.

    Science.gov (United States)

    Docobo-Pérez, F; Fernández-Cuenca, F; Pachón-Ibáñez, M E; Pascual, A; Pichardo, C; Martínez-Martínez, L; Pachón, J

    2008-06-01

    The algorithms included in most automated systems used for antimicrobial susceptibility testing (e.g., Vitek 2) consider that Escherichia coli isolates resistant to cefoxitin are AmpC-hyperproducers and, consequently, resistant also to amoxycillin-clavulanate. However, a recent study revealed that 30% of E. coli clinical isolates resistant to cefoxitin remained susceptible in vitro to amoxycillin-clavulanate. The aim of the present study was to evaluate the in-vivo efficacy of amoxycillin-clavulanate in the treatment of an experimental model of pneumonia, using two clonally related isolates (with identical repetitive extragenic palindromic sequence (REP)-PCR patterns) of AmpC-non-hyperproducing and OmpF-lacking E. coli (Ec985 and Ec571) that were resistant to cefoxitin and susceptible to cefotaxime and amoxycillin-clavulanate. MICs were determined using a microdilution technique, and in-vitro bactericidal activity was tested using time-kill assays. The in-vivo efficacy of amoxycillin, amoxycillin-clavulanate and cefotaxime against both isolates was tested in a murine pneumonia model using immunocompetent C57BL/6 mice. Ec571 (a TEM-1/2 producer) was resistant to amoxycillin, whereas Ec985 (a TEM-1/2 non-producer) was susceptible. Amoxycillin, amoxycillin-clavulanate and cefotaxime were bactericidal for Ec985, and amoxycillin-clavulanate and cefotaxime were bactericidal for Ec571 at different concentrations and time-points, as determined using time-kill assays. Treatment with amoxycillin, amoxycillin-clavulanate and cefotaxime reduced the bacterial lung concentration of Ec985 compared with non-treated controls (p AmpC-non-hyperproducing strains of E. coli resistant to cefoxitin.

  8. Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck; Youngren, Brenda; Hansen, Flemming G.

    2007-01-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division...

  9. The incidence and antibiotics susceptibility of Escherichia coli O157 ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-02-22

    Feb 22, 2010 ... The incidence of Escherichia coli 0157: H7 was assessed in meat samples from .... of this product resulting from contamination with STEC, a zoonotic .... Adak GK, Longs SM, O'Briens SJ (2002) Trends in indigenous forborne.

  10. mcr-1 identified in Avian Pathogenic Escherichia coli (APEC)

    National Research Council Canada - National Science Library

    Nicolle Lima Barbieri; Daniel W Nielsen; Yvonne Wannemuehler; Tia Cavender; Ashraf Hussein; Shi-gan Yan; Lisa K Nolan; Catherine M Logue

    2017-01-01

    .... Here, we examined a collection (n = 980) of Avian Pathogenic Escherichia coli (APEC) isolated from poultry with colibacillosis from the US and internationally for the presence of mcr-1 and mcr-2, genes known to encode colistin resistance...

  11. Overexpression of vsr in Escherichia coli is mutagenic.

    Science.gov (United States)

    Doiron, K M; Viau, S; Koutroumanis, M; Cupples, C G

    1996-01-01

    Overexpression of vsr in Escherichia coli stimulates transition and frameshift mutations. The pattern of mutations suggests that mutagenesis is due to saturation or inactivation of dam-directed mismatch repair. PMID:8763960

  12. Norfloxacin resistance in a clinical isolate of Escherichia coli.

    OpenAIRE

    Aoyama, H; Sato, K; Kato, T.; Hirai, K; Mitsuhashi, S.

    1987-01-01

    Analysis of DNA gyrase supercoiling and of norfloxacin uptake in Escherichia coli GN14176, a moderately norfloxacin-resistant clinical isolate, indicated that resistance was associated with both an altered drug target and a reduction in drug uptake.

  13. Shigella strains are not clones of Escherichia coli but sister species in the genus Escherichia.

    Science.gov (United States)

    Zuo, Guanghong; Xu, Zhao; Hao, Bailin

    2013-02-01

    Shigella species and Escherichia coli are closely related organisms. Early phenotyping experiments and several recent molecular studies put Shigella within the species E. coli. However, the whole-genome-based, alignment-free and parameter-free CVTree approach shows convincingly that four established Shigella species, Shigella boydii, Shigella sonnei, Shigella felxneri and Shigella dysenteriae, are distinct from E. coli strains, and form sister species to E. coli within the genus Escherichia. In view of the overall success and high resolution power of the CVTree approach, this result should be taken seriously. We hope that the present report may promote further in-depth study of the Shigella-E. coli relationship.

  14. Persistence of Escherichia coli in batch and continuous vermicomposting systems.

    Science.gov (United States)

    Hénault-Ethier, Louise; Martin, Vincent J J; Gélinas, Yves

    2016-10-01

    Vermicomposting is a biooxidation process in which epigeicearthworms act in synergy with microbial populations to degrade organic matter. Vermicomposting does not go through a thermophilic stage as required by North American legislations for pathogen eradication. We examined the survival of a Green Fluorescent Protein (GFP) labeled Escherichia coli MG1655 as a model for the survival of pathogenic bacteria in both small-scale batch and medium-scale continuously-operated systems to discern the influence of the earthworm Eisenia fetida, nutrient content and the indigenous vermicompost microbial community on pathogen abundance. In batch systems, the microbial community had the greatest influence on the rapid decline of E. coli populations, and the effect of earthworms was only visible in microbially-impoverishedvermicomposts. No significant earthworm density-dependent relationship was observed on E. coli survival under continuous operation. E. coli numbers decreased below the US EPA compost sanitation guidelines of 10(3)Colony Forming Units (CFU)/g (dry weight) within 18-21days for both the small-scale batch and medium-scale continuous systems, but it took up to 51days without earthworms and with an impoverished microbial community to reach the legal limit. Nutrient replenishment (i.e. organic carbon) provided by continuous feed input did not appear to extend E. coli survival. In fact, longer survival of E. coli was noticed in treatments where less total and labile sugars were available, suggesting that sugars may support potentially antagonist bacteria in the vermicompost. Total N, pH and humidity did not appear to affect E. coli survival. Several opportunistic human pathogens may be found in vermicompost, and their populations are likely kept in check by antagonists.

  15. Use of the D-R model to define trends in the emergence of Ceftazidime-resistant Escherichia coli in China.

    Directory of Open Access Journals (Sweden)

    Fan Ding

    Full Text Available OBJECTIVE: To assess the efficacy of the D-R model for defining trends in the appearance of Ceftazidime-resistant Escherichia coli. METHODS: Actual data related to the manifestation of Ceftazidime-resistant E. coli spanning years 1996-2009 were collected from the China National Knowledge Internet. These data originated from 430 publications encompassing 1004 citations of resistance. The GM(1,1 and the novel D-R models were used to fit current data and from this, predict trends in the appearance of the drug-resistant phenotype. The results were evaluated by Relative Standard Error (RSE, Mean Absolute Deviation (MAD and Mean Absolute Error (MAE. RESULTS: Results from the D-R model showed a rapid increase in the appearance of Ceftazidime-resistant E. coli in this region of the world. These results were considered accurate based upon the minor values calculated for RSE, MAD and MAE, and were equivalent to or better than those generated by the GM(1,1 model. CONCLUSION: The D-R model which was originally created to define trends in the transmission of swine viral diseases can be adapted to evaluating trends in the appearance of Ceftazidime-resistant E. coli. Using only a limited amount of data to initiate the study, our predictions closely mirrored the changes in drug resistance rates which showed a steady increase through 2005, a decrease between 2005 and 2008, and a dramatic inflection point and abrupt increase beginning in 2008. This is consistent with a resistance profile where changes in drug intervention temporarily delayed the upward trend in the appearance of the resistant phenotype; however, resistance quickly resumed its upward momentum in 2008 and this change was better predicted using the D-R model. Additional work is needed to determine if this pattern of "increase-control-increase" is indicative of Ceftazidime-resistant E. coli or can be generally ascribed to bacteria acquiring resistance to drugs in the absence of alternative

  16. ENERGY REQUIREMENT FOR THYMINELESS DEATH IN CELLS OF ESCHERICHIA COLI.

    Science.gov (United States)

    FREIFELDER, D; MAALOE, O

    1964-10-01

    Freifelder, David (University of California, Berkeley), and Ole Maaløe. Energy requirement for thymineless death in cells of Escherichia coli. J. Bacteriol. 88:987-990. 1964.-Thymineless death in thymine-requiring Escherichia coli is arrested immediately and reversibly by nitrogenation if the bacterial population is growing in a medium containing a carbon source that can only be metabolized aerobically. The mechanism of death, therefore, involves a metabolic process.

  17. Variations in virulence of avian pathogenic Escherichia coli demonstrated by the use of a new in vivo infection model

    DEFF Research Database (Denmark)

    Pors, Susanne Elisabeth; Olsen, Rikke Heidemann; Christensen, Jens Peter

    2014-01-01

    Salpingitis and peritonitis are common pathological manifestations observed in egg-laying hens. To improve methods to study these conditions, a surgical model was developed. Initially, eighteen white layers underwent laparotomy with subsequent inoculation of ink, bacteria or sterile broth directly...... into the oviduct. Eight birds inoculated with 0.1 ml blue ink were euthanized immediately after inoculation and the specific site of inoculation was assessed. In all birds, ink was injected into the oviduct between five and seven cm cranial to the isthmus. To demonstrate the use of this approach to cause infection...... of the oviduct, five birds were inoculated with 8.6 × 10(6)CFU of a clinical Escherichia coli isolate. Five control birds received broth with no bacteria. Both infected and control birds were euthanized after 48 h followed by a post mortem examination. Infected birds showed diffuse fibrino-purulent peritonitis...

  18. Engineering Escherichia coli Cell Factories for n-Butanol Production.

    Science.gov (United States)

    Dong, Hongjun; Zhao, Chunhua; Zhang, Tianrui; Lin, Zhao; Li, Yin; Zhang, Yanping

    2016-01-01

    The production of n-butanol, as a widely applied solvent and potential fuel, is attracting much attention. The fermentative production of butanol coupled with the production of acetone and ethanol by Clostridium (ABE fermentation) was once one of the oldest biotechnological processes, ranking second in scale behind ethanol fermentation. However, there remain problems with butanol production by Clostridium, especially the difficulty in genetically manipulating clostridial strains. In recent years, many efforts have been made to produce butanol using non-native strains. Until now, the most advanced effort was the engineering of the user-friendly and widely studied Escherichia coli for butanol production. This paper reviews the current progress and problems relating to butanol production by engineered E. coli in terms of prediction using mathematical models, pathway construction, novel enzyme replacement, butanol toxicity, and tolerance engineering strategies.

  19. Biosensing Vibrio cholerae with Genetically Engineered Escherichia coli.

    Science.gov (United States)

    Holowko, Maciej B; Wang, Huijuan; Jayaraman, Premkumar; Poh, Chueh Loo

    2016-11-18

    Cholera is a potentially mortal, infectious disease caused by Vibrio cholerae bacterium. Current treatment methods of cholera still have limitations. Beneficial microbes that could sense and kill the V. cholerae could offer potential alternative to preventing and treating cholera. However, such V. cholerae targeting microbe is still not available. This microbe requires a sensing system to be able to detect the presence of V. cholera bacterium. To this end, we designed and created a synthetic genetic sensing system using nonpathogenic Escherichia coli as the host. To achieve the system, we have moved proteins used by V. cholerae for quorum sensing into E. coli. These sensor proteins have been further layered with a genetic inverter based on CRISPRi technology. Our design process was aided by computer models simulating in vivo behavior of the system. Our sensor shows high sensitivity to presence of V. cholerae supernatant with tight control of expression of output GFP protein.

  20. Substrate specificity engineering of Escherichia coli derived fructosamine 6-kinase.

    Science.gov (United States)

    Kojima, Katsuhiro; Mikami-Sakaguchi, Akane; Kameya, Miho; Miyamoto, Yusuke; Ferri, Stefano; Tsugawa, Wakako; Sode, Koji

    2013-02-01

    A three-dimensional structural model of Escherichia coli fructosamine 6-kinase (FN6K), an enzyme that phosphorylates fructosamines at C6 and catalyzes the production of the fructosamine 6-phosphate stable intermediate, was generated using the crystal structure of 2-keto-3-deoxygluconate kinase isolated from Thermus thermophilus as template. The putative active site region was then investigated by site-directed mutagenesis to reveal several amino acid residues that likely play important roles in the enzyme reaction. Met220 was identified as a residue that plays a role in substrate recognition when compared to Bacillus subtilis derived FN6K, which shows different substrate specificity from the E. coli FN6K. Among the various Met220-substituted mutant enzymes, Met220Leu, which corresponded to the B. subtilis residue, resulted in an increased activity of fructosyl-valine and decreased activity of fructosyl-lysine, thus increasing the specificity for fructosyl-valine by 40-fold.

  1. A stochastic model for transmission, extinction and outbreak of Escherichia coli O157:H7 in cattle as affected by ambient temperature and cleaning practices

    KAUST Repository

    Wang, Xueying

    2013-07-18

    Many infectious agents transmitting through a contaminated environment are able to persist in the environment depending on the temperature and sanitation determined rates of their replication and clearance, respectively. There is a need to elucidate the effect of these factors on the infection transmission dynamics in terms of infection outbreaks and extinction while accounting for the random nature of the process. Also, it is important to distinguish between the true and apparent extinction, where the former means pathogen extinction in both the host and the environment while the latter means extinction only in the host population. This study proposes a stochastic-differential equation model as an approximation to a Markov jump process model, using Escherichia coli O157:H7 in cattle as a model system. In the model, the host population infection dynamics are described using the standard susceptible-infected-susceptible framework, and the E. coli O157:H7 population in the environment is represented by an additional variable. The backward Kolmogorov equations that determine the probability distribution and the expectation of the first passage time are provided in a general setting. The outbreak and apparent extinction of infection are investigated by numerically solving the Kolmogorov equations for the probability density function of the associated process and the expectation of the associated stopping time. The results provide insight into E. coli O157:H7 transmission and apparent extinction, and suggest ways for controlling the spread of infection in a cattle herd. Specifically, this study highlights the importance of ambient temperature and sanitation, especially during summer. © 2013 Springer-Verlag Berlin Heidelberg.

  2. Modelling growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to commercial process conditions: chlorine washing and modified atmosphere packaging.

    Science.gov (United States)

    Posada-Izquierdo, Guiomar D; Pérez-Rodríguez, Fernando; López-Gálvez, Francisco; Allende, Ana; Selma, María V; Gil, María I; Zurera, Gonzalo

    2013-04-01

    Fresh-cut iceberg lettuce inoculated with Escherichia coli O157:H7 was submitted to chlorine washing (150 mg/mL) and modified atmosphere packaging on laboratory scale. Populations of E. coli O157:H7 were assessed in fresh-cut lettuce stored at 4, 8, 13 and 16 °C using 6-8 replicates in each analysis point in order to capture experimental variability. The pathogen was able to grow at temperatures ≥8 °C, although at low temperatures, growth data presented a high variability between replicates. Indeed, at 8 °C after 15 days, some replicates did not show growth while other replicates did present an increase. A growth primary model was fitted to the raw growth data to estimate lag time and maximum growth rate. The prediction and confidence bands for the fitted growth models were estimated based on Monte-Carlo method. The estimated maximum growth rates (log cfu/day) corresponded to 0.14 (95% CI: 0.06-0.31), 0.55 (95% CI: 0.17-1.20) and 1.43 (95% CI: 0.82-2.15) for 8, 13 and 16 °C, respectively. A square-root secondary model was satisfactorily derived from the estimated growth rates (R(2) > 0.80; Bf = 0.97; Af = 1.46). Predictive models and data obtained in this study are intended to improve quantitative risk assessment studies for E. coli O157:H7 in leafy green products. Copyright © 2012. Published by Elsevier Ltd.

  3. An in vitro model to study interactions between Escherichia coli and lactic acid bacterial inoculants for silage in rumen fluid.

    Science.gov (United States)

    Weinberg, Z G; Chen, Y; Volchinski, V; Sela, S; Ogunade, I M; Adesogan, A

    2016-07-01

    Previous studies have shown that silages treated with lactic acid bacteria (LAB) inoculants enhance ruminants' performance. The objective of the current experiments was to develop an in vitro model to study interactions between LAB silage inoculants and inoculated silages and Escherichia coli (EC) in rumen fluid (RF). Our hypothesis was that some inoculants inhibit EC in RF. For that purpose buffered RF was incubated under anaerobic conditions at 39°C with commercial strains of LAB silage inoculants or with laboratory corn and wheat silages treated with these LAB, an EC strain and with various ruminant feed ingredients. The EC strain was originally isolated from cattle manure and tagged with a plasmid expressing the green fluorescence protein and kanamycin and streptomycin resistance. Results indicate that the LAB or the treated silages did not suppress EC numbers in the RF. When the pH of the RF decreased below 5·0 the EC disappeared. We conclude that both LAB inoculants for silage and EC survived in RF for several days; however, the inoculants and silages treated with such inoculants did not inhibit EC in RF in vitro. Forage crops, silage and hay are initial stages of the food chain for humans. Cattle harbours and sheds enterobacteria regularly, some strains of which are pathogens. These can contaminate forage crops through field fertilization with cattle manure. The objective of this study was to develop an in vitro model to test whether lactic acid bacteria, which are used in silage inoculants, alone or in treated silages can inhibit Escherichia coli in rumen fluid. This study presents safety aspects and it is also part of a broad research effort aimed at finding out how LAB silage inoculants and inoculated silages enhance ruminant performance or exert probiotic effects in ruminants. © 2016 The Society for Applied Microbiology.

  4. Annual Surveillance Summary: Escherichia coli (E. coli) Infections in the Military Health System (MHS), 2016

    Science.gov (United States)

    2017-06-30

    Annual Surveillance Summary: Escherichia coli (E. coli) Infections in the Military Health System (MHS...and prevalence among all beneficiaries seeking care within the Military Health System (MHS). This report describes demographics, clinical...linked to assess descriptive and clinical factors related to E. coli. Health Level 7 (HL7)-formatted Composite Health Care System (CHCS) microbiology data

  5. Completion of DNA replication in Escherichia coli.

    Science.gov (United States)

    Wendel, Brian M; Courcelle, Charmain T; Courcelle, Justin

    2014-11-18

    The mechanism by which cells recognize and complete replicated regions at their precise doubling point must be remarkably efficient, occurring thousands of times per cell division along the chromosomes of humans. However, this process remains poorly understood. Here we show that, in Escherichia coli, the completion of replication involves an enzymatic system that effectively counts pairs and limits cellular replication to its doubling point by allowing converging replication forks to transiently continue through the doubling point before the excess, over-replicated regions are incised, resected, and joined. Completion requires RecBCD and involves several proteins associated with repairing double-strand breaks including, ExoI, SbcDC, and RecG. However, unlike double-strand break repair, completion occurs independently of homologous recombination and RecA. In some bacterial viruses, the completion mechanism is specifically targeted for inactivation to allow over-replication to occur during lytic replication. The results suggest that a primary cause of genomic instabilities in many double-strand-break-repair mutants arises from an impaired ability to complete replication, independent from DNA damage.

  6. (ESBL)-producing Escherichia coli isolated from cl

    African Journals Online (AJOL)

    spectrum beta-lactamase (ESBL)-producing Escherichia coli isolated from clinical ... Methods: A total of 127 E. coli were collected from clinical samples in Kerman hospitals. The antibiotic ..... in Mexico and 26.1 % in Turkey [23,24]. These.

  7. Efficient expression of the yeast metallothionein gene in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Berka, T.; Shatzman, A.; Zimmerman, J.; Strickler, J.; Rosenberg, M.

    1988-01-01

    The yeast metallothionein gene CUP1 was cloned into a bacterial expression system to achieve efficient, controlled expression of the stable, unprocessed protein product. The Escherichia coli-synthesized yeast metallothionein bound copper, cadmium, zinc, indicating that the protein was functional. Furthermore, E. coli cells expressing CUP1 acquired a new, inducible ability to selectively sequester heavy metal ions from the growth medium.

  8. Antimicrobial activity of peptidomimetics against multidrug-resistant Escherichia coli

    DEFF Research Database (Denmark)

    Jahnsen, Rasmus D; Frimodt-Møller, Niels; Franzyk, Henrik

    2012-01-01

    -lactamase-producing Escherichia coli was assessed by testing an array comprising different types of cationic peptidomimetics obtained by a general monomer-based solid-phase synthesis protocol. Most of the peptidomimetics possessed high to moderate activity toward multidrug-resistant E. coli as opposed to the corresponding...

  9. Characterization of enterohemorrhagic Escherichia coli on veal hides and carcasses

    Science.gov (United States)

    Enterohemorrhagic E. coli (EHEC) are Shiga toxin–producing Escherichia coli (STEC) associated with the most severe forms of foodborne illnesses. The United States Department of Agriculture (USDA) Food Safety Inspection Service (FSIS) has identified a higher percentage of non-O157 EHEC compared to E....

  10. Escherichia coli Eyelid Abscess in a Patient with Alcoholic Cirrhosis

    Directory of Open Access Journals (Sweden)

    Matthew Stratton

    2015-01-01

    Full Text Available Escherichia coli (E. coli is a rare cause of ocular infections and has not yet been reported as a cause of an ocular abscess. We describe the case of a 47-year-old woman with a history of alcoholic cirrhosis who presented with painful left lower eyelid swelling that did not improve with oral antibiotics. The abscess was drained and cultures were positive for E. coli. Patients with cirrhosis are at increased risk for developing E. coli bacterial infections, but to our knowledge this is the first case of an E. coli eyelid abscess reported in the literature.

  11. In vivo and in vitro effects of tea extracts on enterotoxigenic Escherichia coli-induced intestinal fluid loss in animal models

    NARCIS (Netherlands)

    Bruins, M.J.; Cermak, R.; Kiers, J.L.; Meulen, van der J.; Amelsvoort, van J.M.M.; Klinken, B.J.

    2006-01-01

    OBJECTIVES: Enterotoxigenic Escherichia coli (ETEC) infection is a major cause of dehydrating diarrhoea in infants and early-weaned piglets living under subhygienic conditions. We studied the effect of different tea types and subfractions on the intestinal fluid and electrolyte losses involved in ET

  12. Modeling the contamination of lettuce with Escherichia coli 157:H7 from manure-amended soil and the effect of intervention strategies

    NARCIS (Netherlands)

    Franz, E.; Semenov, A.V.; Bruggen, van A.H.C.

    2008-01-01

    Aims: A growing number of foodborne illnesses has been associated with the consumption of fresh produce. In this study, the probability of lettuce contamination with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies was determined. Methods and Results: Patho

  13. Accumulation and efflux of polychlorinated biphenyls in Escherichia coli.

    Science.gov (United States)

    Geng, Shen; Fang, Jun; Turner, Kendrick B; Daunert, Sylvia; Wei, Yinan

    2012-06-01

    Polychlorinated biphenyls (PCBs) are environmental pollutants that have been associated with numerous adverse health effects in human and animals. Hydroxylated PCBs (HPCBs) are the product of the oxidative metabolism of PCBs. The presence of hydroxyl groups in HPCBs makes these compounds more hydrophilic than the parent PCBs. One of the best approaches to break down and remove these contaminants is bioremediation; an environmentally friendly process that uses microorganisms to degrade hazardous chemicals into non-toxic ones. In this study, we investigated the cellular accumulation and toxicity of selected PCBs and HPCBs in Gram-negative bacteria, using Escherichia coli as a model organism. We found that none of the five PCBs tested were toxic to E. coli, presumably due to their limited bioavailability. Nevertheless, different HPCBs tested showed different levels of toxicity. Furthermore, we demonstrated that the primary multidrug efflux system in E. coli, AcrAB-TolC, facilitated the efflux of HPCBs out of the cell. Since AcrAB-TolC is constitutively expressed in E. coli and is conserved in all sequenced Gram-negative bacterial genomes, our results suggest that the efflux activities of multidrug resistant pumps may affect the accumulation and degradation of PCBs in Gram-negative bacteria.

  14. Insights into the biology of Escherichia coli through structural proteomics.

    Science.gov (United States)

    Matte, Allan; Jia, Zongchao; Sunita, S; Sivaraman, J; Cygler, Miroslaw

    2007-09-01

    Escherichia coli has historically been an important organism for understanding a multitude of biological processes, and represents a model system as we attempt to simulate the workings of living cells. Many E. coli strains are also important human and animal pathogens for which new therapeutic strategies are required. For both reasons, a more complete and comprehensive understanding of the protein structure complement of E. coli is needed at the genome level. Here, we provide examples of insights into the mechanism and function of bacterial proteins that we have gained through the Bacterial Structural Genomics Initiative (BSGI), focused on medium-throughput structure determination of proteins from E. coli. We describe the structural characterization of several enzymes from the histidine biosynthetic pathway, the structures of three pseudouridine synthases, enzymes that synthesize one of the most abundant modified bases in RNA, as well as the combined use of protein structure and focused functional analysis to decipher functions for hypothetical proteins. Together, these results illustrate the power of structural genomics to contribute to a deeper biological understanding of bacterial processes.

  15. Characterizing the Final Steps of Chromosomal Replication at the Single-molecule Level in the Model System Escherichia coli

    KAUST Repository

    Elshenawy, Mohamed M.

    2015-12-01

    In the circular Escherichia coli chromosome, two replisomes are assembled at the unique origin of replication and drive DNA synthesis in opposite directions until they meet in the terminus region across from the origin. Despite the difference in rates of the two replisomes, their arrival at the terminus is synchronized through a highly specialized system consisting of the terminator protein (Tus) bound to the termination sites (Ter). This synchronicity is mediated by the polarity of the Tus−Ter complex that stops replisomes from one direction (non-permissive face) but not the other (permissive face). Two oppositely oriented clusters of five Tus–Ters that each block one of the two replisomes create a “replication fork trap” for the first arriving replisome while waiting for the late arriving one. Despite extensive biochemical and structural studies, the molecular mechanism behind Tus−Ter polar arrest activity remained controversial. Moreover, none of the previous work provided answers for the long-standing discrepancy between the ability of Tus−Ter to permanently stop replisomes in vitro and its low efficiency in vivo. Here, I spearheaded a collaborative project that combined single-molecule DNA replication assays, X-ray crystallography and binding studies to provide a true molecular-level understanding of the underlying mechanism of Tus−Ter polar arrest activity. We showed that efficiency of Tus−Ter is determined by a head-to-head kinetic competition between rate of strand separation by the replisome and rate of rearrangement of Tus−Ter interactions during the melting of the first 6 base pairs of Ter. This rearrangement maintains Tus’s strong grip on the DNA and stops the advancing replisome from breaking into Tus−Ter central interactions, but only transiently. We further showed how this kinetic competition functions within the context of two mechanisms to impose permanent fork stoppage. The rate-dependent fork arrest activity of Tus

  16. A structural view of the dissociation of Escherichia coli tryptophanase.

    Science.gov (United States)

    Green, Keren; Qasim, Nasrin; Gdaelvsky, Garik; Kogan, Anna; Goldgur, Yehuda; Parola, Abraham H; Lotan, Ofra; Almog, Orna

    2015-12-01

    Tryptophanase (Trpase) is a pyridoxal 5'-phosphate (PLP)-dependent homotetrameric enzyme which catalyzes the degradation of L-tryptophan. Trpase is also known for its cold lability, which is a reversible loss of activity at low temperature (2°C) that is associated with the dissociation of the tetramer. Escherichia coli Trpase dissociates into dimers, while Proteus vulgaris Trpase dissociates into monomers. As such, this enzyme is an appropriate model to study the protein-protein interactions and quaternary structure of proteins. The aim of the present study was to understand the differences in the mode of dissociation between the E. coli and P. vulgaris Trpases. In particular, the effect of mutations along the molecular axes of homotetrameric Trpase on its dissociation was studied. To answer this question, two groups of mutants of the E. coli enzyme were created to resemble the amino-acid sequence of P. vulgaris Trpase. In one group, residues 15 and 59 that are located along the molecular axis R (also termed the noncatalytic axis) were mutated. The second group included a mutation at position 298, located along the molecular axis Q (also termed the catalytic axis). Replacing amino-acid residues along the R axis resulted in dissociation of the tetramers into monomers, similar to the P. vulgaris Trpase, while replacing amino-acid residues along the Q axis resulted in dissociation into dimers only. The crystal structure of the V59M mutant of E. coli Trpase was also determined in its apo form and was found to be similar to that of the wild type. This study suggests that in E. coli Trpase hydrophobic interactions along the R axis hold the two monomers together more strongly, preventing the dissociation of the dimers into monomers. Mutation of position 298 along the Q axis to a charged residue resulted in tetramers that are less susceptible to dissociation. Thus, the results indicate that dissociation of E. coli Trpase into dimers occurs along the molecular Q axis.

  17. 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.

  18. Molecular Evolutionary Relationships of Enteroinvasive Escherichia coli and Shigella spp.

    OpenAIRE

    Lan, Ruiting; Alles, M. Chehani; Donohoe, Kathy; Marina B Martinez; Reeves, Peter R.

    2004-01-01

    Enteroinvasive Escherichia coli (EIEC), a distinctive pathogenic form of E. coli causing dysentery, is similar in many properties to bacteria placed in the four species of Shigella. Shigella has been separated as a genus but in fact comprises several clones of E. coli. The evolutionary relationships of 32 EIEC strains of 12 serotypes have been determined by sequencing of four housekeeping genes and two plasmid genes which were used previously to determine the relationships of Shigella strains...

  19. Escherichia coli bacteria detection by using graphene-based biosensor.

    Science.gov (United States)

    Akbari, Elnaz; Buntat, Zolkafle; Afroozeh, Abdolkarim; Zeinalinezhad, Alireza; Nikoukar, Ali

    2015-10-01

    Graphene is an allotrope of carbon with two-dimensional (2D) monolayer honeycombs. A larger detection area and higher sensitivity can be provided by graphene-based nanosenor because of its 2D structure. In addition, owing to its special characteristics, including electrical, optical and physical properties, graphene is known as a more suitable candidate compared to other materials used in the sensor application. A novel model employing a field-effect transistor structure using graphene is proposed and the current-voltage (I-V) characteristics of graphene are employed to model the sensing mechanism. This biosensor can detect Escherichia coli (E. coli) bacteria, providing high levels of sensitivity. It is observed that the graphene device experiences a drastic increase in conductance when exposed to E. coli bacteria at 0-10(5) cfu/ml concentration. The simple, fast response and high sensitivity of this nanoelectronic biosensor make it a suitable device in screening and functional studies of antibacterial drugs and an ideal high-throughput platform which can detect any pathogenic bacteria. Artificial neural network and support vector regression algorithms have also been used to provide other models for the I-V characteristic. A satisfactory agreement has been presented by comparison between the proposed models with the experimental data.

  20. Distinct Renal Pathology and a Chemotactic Phenotype after Enterohemorrhagic Escherichia coli Shiga Toxins in Non-Human Primate Models of Hemolytic Uremic Syndrome

    Science.gov (United States)

    Stearns-Kurosawa, Deborah J.; Oh, Sun-Young; Cherla, Rama P.; Lee, Moo-Seung; Tesh, Vernon L.; Papin, James; Henderson, Joel; Kurosawa, Shinichiro

    2014-01-01

    Enterohemorrhagic Escherichia coli cause approximately 1.5 million infections globally with 176,000 cases occurring in the United States annually from ingesting contaminated food, most frequently E. coli O157:H7 in ground beef or fresh produce. In severe cases, the painful prodromal hemorrhagic colitis is complicated by potentially lethal hemolytic uremic syndrome (HUS), particularly in children. Bacterial Shiga-like toxins (Stx1, Stx2) are primarily responsible for HUS and the kidney and neurologic damage that ensue. Small animal models are hampered by the inability to reproduce HUS with thrombotic microangiopathy, hemolytic anemia, and acute kidney injury. Earlier, we showed that nonhuman primates (Papio) recapitulated clinical HUS after Stx challenge and that novel therapeutic intervention rescued the animals. Here, we present detailed light and electron microscopic pathology examination of the kidneys from these Stx studies. Stx1 challenge resulted in more severe glomerular endothelial injury, whereas the glomerular injury after Stx2 also included prominent mesangiolysis and an eosinophilic inflammatory infiltration. Both toxins induced glomerular platelet-rich thrombi, interstitial hemorrhage, and tubular injury. Analysis of kidney and other organs for inflammation biomarkers showed a striking chemotactic profile, with extremely high mRNA levels for IL-8, monocyte chemoattractant protein 1, and macrophage inflammatory protein 1α and elevated urine chemokines at 48 hours after challenge. These observations give unique insight into the pathologic consequences of each toxin in a near human setting and present potential pathways for therapeutic intervention. PMID:23402998

  1. Recombinant expression of Bacillus anthracis lethal toxin components of Indian isolate in Escherichia coli and determination of its acute toxicity level in mouse model.

    Science.gov (United States)

    Nagendra, Suryanarayana; Vanlalhmuaka; Verma, Sarika; Tuteja, Urmil; Thavachelvam, Kulanthaivel

    2015-12-15

    Bacillus anthracis lethal toxin (LeTx) is the principle factor responsible for toxaemia and anthrax related death. Lethal toxin consist of two proteins viz protective antigen (PA) and lethal factor which combines in a typical fashion similar to other toxins belonging to A-B toxin super family. The amount of LeTx required to kill a particular organism generally differs among strains owing to their geographical distributions and genetic variation. In the present study, we have cloned PA and LF genes from B. anthracis clinical isolate of Indian origin and expressed them in soluble form employing Escherichia coli expression system. Both the proteins were purified to near homogeneity level using Immobilized metal ion affinity chromatography (IMAC). Further we have used equal ratio of both the proteins to form LeTx and determined its acute toxicity level in Balb/c mice by graphical method of Miller and Tainter. The LD50 value of LeTx by intravenous (i.v) route was found to be 0.97 ± 0.634 mg kg(-1) Balb/c mice. This study highlights the expression of recombinant LeTx from E. coli and assessing its acute toxicity level in experimental mouse model.

  2. Response of Fe-S cluster assembly machinery of Escherichia coli to mechanical stress in a model of amino-acid crystal fermentation.

    Science.gov (United States)

    Okutani, Satoshi; Iwai, Takayoshi; Iwatani, Shintaro; Matsuno, Kiyoshi; Takahashi, Yasuhiro; Hase, Toshiharu

    2015-09-01

    During amino-acid crystal fermentation, mechanical stress on bacterial cells caused by crystal collision often impacts negatively on bacterial growth and amino-acid production. When Escherichia coli cells were cultivated under mechanical stress of polyvinyl chloride particles as a model of the crystal fermentation, activities of iron-sulfur (Fe-S) cluster-containing enzymes were apparently decreased. Based on an assumption that function of Fe-S cluster assembly machinery would be elevated to recover the enzyme activities in such stressed cells, we analyzed levels of various components of Fe-S cluster assembly machinery by western blotting. It was found that the expression of HscA, a chaperon component of the machinery, was up-regulated and that shorter forms of HscA with the N-terminal region truncated were accumulated, suggesting an important role of HscA against the mechanical stress. An overexpression of HscA gene in E. coli cells gave a positive effect on rescue of the stress-induced decrease of the activity of Fe-S cluster-containing enzyme. These results may provide a new strategy to alleviate the mechanical stress during the amino-acid crystal fermentation.

  3. Findings of Escherichia coli and Enterococcus spp. in homemade cheese

    Directory of Open Access Journals (Sweden)

    Tambur Zoran

    2007-01-01

    Full Text Available During the period from February until March 2004, 108 samples of soft cheese originating from markets of Pancevo, Subotica and Belgrade were examined. Microbiological analyses of the cheese samples to the presence of Escherichia coli was performed using methods described in the Regulations on methods for performing microbiological analyses and super analyses of consumer articles, while the presence of bacteria Enteroccocus spp. was performed on the dexter agar. From 108 samples of soft cheese from the territories of Pancevo, Belgrade and Subotica were isolated: Enterococcus spp. from 96% and Escherichia coli from 69%, cheese samples. Verocytotoxic E.coli was not isolated from any of the taken cheese samples.

  4. 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|info:eu-repo/dai/nl/126613354; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    BACKGROUND: 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

  5. 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; Minh, Van Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    Background: 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

  6. 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; Minh, Van Pham; Wagenaar, Jaap A.; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

    2016-01-01

    Background: 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 ou

  7. Free RNA polymerase in Escherichia coli.

    Science.gov (United States)

    Patrick, Michael; Dennis, Patrick P; Ehrenberg, Mans; Bremer, Hans

    2015-12-01

    The frequencies of transcription initiation of regulated and constitutive genes depend on the concentration of free RNA polymerase holoenzyme [Rf] near their promoters. Although RNA polymerase is largely confined to the nucleoid, it is difficult to determine absolute concentrations of [Rf] at particular locations within the nucleoid structure. However, relative concentrations of free RNA polymerase at different growth rates, [Rf]rel, can be estimated from the activities of constitutive promoters. Previous studies indicated that the rrnB P2 promoter is constitutive and that [Rf]rel in the vicinity of rrnB P2 increases with increasing growth rate. Recently it has become possible to directly visualize Rf in growing Escherichia coli cells. Here we examine some of the important issues relating to gene expression based on these new observations. We conclude that: (i) At a growth rate of 2 doublings/h, there are about 1000 free and 2350 non-specifically DNA-bound RNA polymerase molecules per average cell (12 and 28%, respectively, of 8400 total) which are in rapid equilibrium. (ii) The reversibility of the non-specific binding generates more than 1000 free RNA polymerase molecules every second in the immediate vicinity of the DNA. Of these, most rebind non-specifically to the DNA within a few ms; the frequency of non-specific binding is at least two orders of magnitude greater than specific binding and transcript initiation. (iii) At a given amount of RNA polymerase per cell, [Rf] and the density of non-specifically DNA-bound RNA polymerase molecules along the DNA both vary reciprocally with the amount of DNA in the cell. (iv) At 2 doublings/h an E. coli cell contains, on the average, about 1 non-specifically bound RNA polymerase per 9 kbp of DNA and 1 free RNA polymerase per 20 kbp of DNA. However some DNA regions (i.e. near active rRNA operons) may have significantly higher than average [Rf].

  8. Antibiotic selection of Escherichia coli sequence type 131 in a mouse intestinal colonization model

    DEFF Research Database (Denmark)

    Hertz, Frederik Boetius; Løbner-Olesen, Anders; Frimodt-Møller, Niels

    2014-01-01

    , clindamycin, penicillin, ampicillin, meropenem, ciprofloxacin, and amdinocillin) against a CTX-M-15-producing E. coli sequence type 131 (ST131) isolate with a fluoroquinolone resistance phenotype. Mice (8 per group) were orogastrically administered 0.25 ml saline with 10(8) CFU/ml E. coli ST131. On that same...

  9. Cefotaxime and Amoxicillin-Clavulanate Synergism against Extended-Spectrum-β-Lactamase-Producing Escherichia coli in a Murine Model of Urinary Tract Infection.

    Science.gov (United States)

    Rossi, B; Soubirou, J F; Chau, F; Massias, L; Dion, S; Lepeule, R; Fantin, B; Lefort, A

    2015-11-02

    We investigated the efficacies of cefotaxime (CTX) and amoxicillin (AMX)-clavulanate (CLA) (AMC) against extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli in vitro and in a murine model of urinary tract infection (UTI). MICs, the checkerboard dilution method, and time-kill curves were used to explore the in vitro synergism between cefotaxime and amoxicillin-clavulanate against two isogenic E. coli strains-CFT073-RR and its transconjugant, CFT073-RR Tc bla(CTX-M-15)-harboring a bla(CTX-M-15) plasmid and a bla(OXA-1) plasmid. For in vivo experiments, mice were separately infected with each strain and treated with cefotaxime, amoxicillin, and clavulanate, alone or in combination, or imipenem, using therapeutic regimens reproducing time of free-drug concentrations above the MIC (fT≥MIC) values close to that obtained in humans. MICs of amoxicillin, cefotaxime, and imipenem were 4/>1,024, 0.125/1,024, and 0.5/0.5 mg/liter, for CFT073-RR and CFT073-RR Tc bla(CTX-M-15), respectively. The addition of 2 mg/liter of clavulanate (CLA) restored the susceptibility of CFT073-RR Tc bla(CTX-M-15) to CTX (MICs of the CTX-CLA combination, 0.125 mg/liter). The checkerboard dilution method and time-kill curves confirmed an in vitro synergy between amoxicillin-clavulanate and cefotaxime against CFT073-RR Tc bla(CTX-M-15). In vivo, this antibiotic combination was similarly active against both strains and as effective as imipenem. In conclusion, the cefotaxime and amoxicillin-clavulanate combination appear to be an effective, easy, and already available alternative to carbapenems for the treatment of UTI due to CTX-M-producing E. coli strains.

  10. Integrated signaling pathway and gene expression regulatory model to dissect dynamics of Escherichia coli challenged mammary epithelial cells.

    Science.gov (United States)

    den Breems, Nicoline Y; Nguyen, Lan K; Kulasiri, Don

    2014-12-01

    Cells transform external stimuli, through the activation of signaling pathways, which in turn activate gene regulatory networks, in gene expression. As more omics data are generated from experiments, eliciting the integrated relationship between the external stimuli, the signaling process in the cell and the subsequent gene expression is a major challenge in systems biology. The complex system of non-linear dynamic protein interactions in signaling pathways and gene networks regulates gene expression. The complexity and non-linear aspects have resulted in the study of the signaling pathway or the gene network regulation in isolation. However, this limits the analysis of the interaction between the two components and the identification of the source of the mechanism differentiating the gene expression profiles. Here, we present a study of a model of the combined signaling pathway and gene network to highlight the importance of integrated modeling. Based on the experimental findings we developed a compartmental model and conducted several simulation experiments. The model simulates the mRNA expression of three different cytokines (RANTES, IL8 and TNFα) regulated by the transcription factor NFκB in mammary epithelial cells challenged with E. coli. The analysis of the gene network regulation identifies a lack of robustness and therefore sensitivity for the transcription factor regulation. However, analysis of the integrated signaling and gene network regulation model reveals distinctly different underlying mechanisms in the signaling pathway responsible for the variation between the three cytokine's mRNA expression levels. Our key findings reveal the importance of integrating the signaling pathway and gene expression dynamics in modeling. Modeling infers valid research questions which need to be verified experimentally and can assist in the design of future biological experiments.

  11. Predictive models for Escherichia coli concentrations at inland lake beaches and relationship of model variables to pathogen detection

    Science.gov (United States)

    Methods are needed improve the timeliness and accuracy of recreational water‐quality assessments. Traditional culture methods require 18–24 h to obtain results and may not reflect current conditions. Predictive models, based on environmental and water quality variables, have been...

  12. Ex Vivo Bioluminescence Imaging of Late Gestation Ewes Following Intra-uterine Inoculation With Lux-modified Escherichia coli

    Science.gov (United States)

    Our objectives were to develop an ovine model for Escherichia coli-induced preterm delivery, and monitor E. coli (lux modified for photonic detection) invasion of the fetal environment—ewes (124 ± 18 d of gestation) received intrauterine inoculations using E. coli-lux as follows: control (n = 5), 1....

  13. The versatile strategies of Escherichia coli pathotypes: a mini review

    Directory of Open Access Journals (Sweden)

    C. P. Sousa

    2006-01-01

    Full Text Available The widespread species Escherichia coli includes a broad variety of different types, ranging from highly pathogenic strains to avirulent isolates. Few microorganisms are as versatile as E. coli. Pathogenic strains remain a leading cause of severe and persistent infant diarrhea in developing countries. They may be limited to colonization of a mucosal surface or can disseminate throughout the body and have been implicated in urinary tract infection, sepsis/meningitis and gastrointestinal infection. The human gastrointestinal tract is susceptible to diarrheagenic E. coli infections. Escherichia coli have effectively managed to subvert the host cytoskeleton for their own purposes causing substantial diarrheal disease, a major public health problem worldwide. This review deals with the different strategies regarding E. coli as a pathogen and the virulence traits of its pathotypes highlighting the species as a commensal, opportunistic and specialized pathogen.

  14. Escherichia coli Chromosomal Loci Segregate from Midcell with Universal Dynamics.

    Science.gov (United States)

    Cass, Julie A; Kuwada, Nathan J; Traxler, Beth; Wiggins, Paul A

    2016-06-21

    The structure of the Escherichia coli chromosome is inherently dynamic over the duration of the cell cycle. Genetic loci undergo both stochastic motion around their initial positions and directed motion to opposite poles of the rod-shaped cell during segregation. We developed a quantitative method to characterize cell-cycle dynamics of the E. coli chromosome to probe the chromosomal steady-state mobility and segregation process. By tracking fluorescently labeled chromosomal loci in thousands of cells throughout the entire cell cycle, our method allows for the statistical analysis of locus position and motion, the step-size distribution for movement during segregation, and the locus drift velocity. The robust statistics of our detailed analysis of the wild-type E. coli nucleoid allow us to observe loci moving toward midcell before segregation occurs, consistent with a replication factory model. Then, as segregation initiates, we perform a detailed characterization of the average segregation velocity of loci. Contrary to origin-centric models of segregation, which predict distinct dynamics for oriC-proximal versus oriC-distal loci, we find that the dynamics of loci were universal and independent of genetic position.

  15. The potential of random forest and neural networks for biomass and recombinant protein modeling in Escherichia coli fed-batch fermentations.

    Science.gov (United States)

    Melcher, Michael; Scharl, Theresa; Spangl, Bernhard; Luchner, Markus; Cserjan, Monika; Bayer, Karl; Leisch, Friedrich; Striedner, Gerald

    2015-09-01

    Product quality assurance strategies in production of biopharmaceuticals currently undergo a transformation from empirical "quality by testing" to rational, knowledge-based "quality by design" approaches. The major challenges in this context are the fragmentary understanding of bioprocesses and the severely limited real-time access to process variables related to product quality and quantity. Data driven modeling of process variables in combination with model predictive process control concepts represent a potential solution to these problems. The selection of statistical techniques best qualified for bioprocess data analysis and modeling is a key criterion. In this work a series of recombinant Escherichia coli fed-batch production processes with varying cultivation conditions employing a comprehensive on- and offline process monitoring platform was conducted. The applicability of two machine learning methods, random forest and neural networks, for the prediction of cell dry mass and recombinant protein based on online available process parameters and two-dimensional multi-wavelength fluorescence spectroscopy is investigated. Models solely based on routinely measured process variables give a satisfying prediction accuracy of about ± 4% for the cell dry mass, while additional spectroscopic information allows for an estimation of the protein concentration within ± 12%. The results clearly argue for a combined approach: neural networks as modeling technique and random forest as variable selection tool.

  16. 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.

  17. Rapid Sterilization of Escherichia coli by Solution Plasma Process

    Science.gov (United States)

    Andreeva, Nina; Ishizaki, Takahiro; Baroch, Pavel; Saito, Nagahiro

    2012-12-01

    Solution plasma (SP), which is a discharge in the liquid phase, has the potential for rapid sterilization of water without chemical agents. The discharge showed a strong sterilization performance against Escherichia coli bacteria. The decimal value (D value) of the reduction time for E. coli by this system with an electrode distance of 1.0 mm was estimated to be approximately 1.0 min. Our discharge system in the liquid phase caused no physical damage to the E. coli and only a small increase in the temperature of the aqueous solution. The UV light generated by the discharge was an important factor in the sterilization of E. coli.

  18. Detection of Escherichia coli in wastewater based on enzyme immunoassay

    Institute of Scientific and Technical Information of China (English)

    XI Haiyan; CAI Qiang; HE Miao; SHI Hanchang

    2007-01-01

    This research describes a fast detection method on the basis of enzyme-linked immunosorbent assay (ELISA)for Escherichia coli in drainage of wastewater treatment plants.Optimized conditions such as the reaction format(sandwich or direct),the concentrations of diluted horseradish peroxidase (HRP)-E.coli conjugate,and anti-HPR antibody and pretreatment of E.coli were studied.Those results showed that the linear range of detection for E.coli was 10 cfu/mL-6×104 cfu/mL.Compared with conventional methods,it is a convenient and sensitive detection method with low cost.

  19. Fluorogenic assay for rapid detection of Escherichia coli in food.

    OpenAIRE

    1985-01-01

    An assay procedure to screen for Escherichia coli in foods by using 4-methylumbelliferyl-beta-D-glucuronide (MUG) incorporated into lauryl tryptose (LST) broth was evaluated. The beta-glucuronidase produced by E. coli cleaves the MUG substrate to yield a fluorescent end product. E. coli-negative samples can be identified by lack of fluorescence in LST-MUG within 24 h. MUG was not inhibitory to coliforms and E. coli. Over 1,400 food and dairy samples were tested to compare the standard three-t...

  20. Escherichia coli lipoprotein binds human plasminogen via an intramolecular domain

    Directory of Open Access Journals (Sweden)

    Tammy eGonzalez

    2015-10-01

    Full Text Available Escherichia coli lipoprotein (Lpp is a major cellular component that exists in two distinct states, bound-form and free-form. Bound-form Lpp is known to interact with the periplasmic bacterial cell wall, while free-form Lpp is localized to the bacterial cell surface. A function for surface-exposed Lpp has yet to be determined. We hypothesized that the presence of C-terminal lysines in the surface-exposed region of Lpp would facilitate binding to the host zymogen plasminogen, a protease commandeered by a number of clinically important bacteria. Recombinant Lpp was synthesized and the binding of Lpp to plasminogen, the effect of various inhibitors on this binding, and the effects of various mutations of Lpp on Lpp-plasminogen interactions were examined. Additionally, the ability of Lpp-bound plasminogen to be converted to active plasmin was analyzed. We determined that Lpp binds plasminogen via an atypical domain located near the center of mature Lpp that may not be exposed on the surface of intact E. coli according to the current localization model. Finally, we found that plasminogen bound by Lpp can be converted to active plasmin. While the consequences of Lpp binding plasminogen are unclear, these results prompt further investigation of the ability of surface exposed Lpp to interact with host molecules such as extracellular matrix components and complement regulators, and the role of these interactions in infections caused by E. coli and other bacteria.

  1. Thermal impulse response and the temperature preference of Escherichia coli

    Science.gov (United States)

    Ryu, William

    2010-03-01

    From a broad perspective, exposure to environmental temperature changes is a universal condition of living organisms. Escherichia coli is a powerful model system to study how a biochemical network measures and processes thermal information to produce adaptive changes in behavior. E. coli performs thermotaxis, directing its movements to a preferred temperature in spatial thermal gradients. How does the system perform thermotaxis? Where biologically is this analog value of thermal preference stored? Previous studies using populations of cells have shown that E.coli accumulate in spatial thermal gradients, but these experiments did not cleanly separate thermal responses from chemotactic responses. Here we have isolated the thermal behavior by studying the thermal impulse response of single, tethered cells. The motor output of cells was measured in response to small, impulsive increases in temperature, delivered by an infrared laser, over a range of ambient temperature (23 to 43 degrees C). The thermal impulse response at temperatures 31 degrees C, some cells show an inverted response, switching from warm- to cold-seeking behavior. The fraction of inverted responses increases nonlinearly with temperature, switching steeply at the preferred temperature of 37 degrees C.

  2. Global functional atlas of Escherichia coli encompassing previously uncharacterized proteins.

    Directory of Open Access Journals (Sweden)

    Pingzhao Hu

    2009-04-01

    Full Text Available One-third of the 4,225 protein-coding genes of Escherichia coli K-12 remain functionally unannotated (orphans. Many map to distant clades such as Archaea, suggesting involvement in basic prokaryotic traits, whereas others appear restricted to E. coli, including pathogenic strains. To elucidate the orphans' biological roles, we performed an extensive proteomic survey using affinity-tagged E. coli strains and generated comprehensive genomic context inferences to derive a high-confidence compendium for virtually the entire proteome consisting of 5,993 putative physical interactions and 74,776 putative functional associations, most of which are novel. Clustering of the respective probabilistic networks revealed putative orphan membership in discrete multiprotein complexes and functional modules together with annotated gene products, whereas a machine-learning strategy based on network integration implicated the orphans in specific biological processes. We provide additional experimental evidence supporting orphan participation in protein synthesis, amino acid metabolism, biofilm formation, motility, and assembly of the bacterial cell envelope. This resource provides a "systems-wide" functional blueprint of a model microbe, with insights into the biological and evolutionary significance of previously uncharacterized proteins.

  3. Modeling and simulation of the main metabolism in Escherichia coli and its several single-gene knockout mutants with experimental verification

    Directory of Open Access Journals (Sweden)

    McFadden Johnjoe

    2010-11-01

    Full Text Available Abstract Background It is quite important to simulate the metabolic changes of a cell in response to the change in culture environment and/or specific gene knockouts particularly for the purpose of application in industry. If this could be done, the cell design can be made without conducting exhaustive experiments, and one can screen out the promising candidates, proceeded by experimental verification of a select few of particular interest. Although several models have so far been proposed, most of them focus on the specific metabolic pathways. It is preferred to model the whole of the main metabolic pathways in Escherichia coli, allowing for the estimation of energy generation and cell synthesis, based on intracellular fluxes and that may be used to characterize phenotypic growth. Results In the present study, we considered the simulation of the main metabolic pathways such as glycolysis, TCA cycle, pentose phosphate (PP pathway, and the anapleorotic pathways using enzymatic reaction models of E. coli. Once intracellular fluxes were computed by this model, the specific ATP production rate, the specific CO2 production rate, and the specific NADPH production rate could be estimated. The specific ATP production rate thus computed was used for the estimation of the specific growth rate. The CO2 production rate could be used to estimate cell yield, and the specific NADPH production rate could be used to determine the flux of the oxidative PP pathway. The batch and continuous cultivations were simulated where the changing patterns of extracellular and intra-cellular metabolite concentrations were compared with experimental data. Moreover, the effects of the knockout of such pathways as Ppc, Pck and Pyk on the metabolism were simulated. It was shown to be difficult for the cell to grow in Ppc mutant due to low concentration of OAA, while Pck mutant does not necessarily show this phenomenon. The slower growth rate of the Ppc mutant was properly

  4. 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 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...

  5. Establishment of disseminated intravascular coagulation (DIC model by a single iv administration of Escherichia coli-derived lipopolysaccharide (LPS to cynomolgus monkeys and evaluation of its pathophysiological status

    Directory of Open Access Journals (Sweden)

    Hirofumi Minomo

    2017-02-01

    Full Text Available We prepared a DIC model by administrating LPS to cynomolgus monkeys, and investigated its potential for evaluations of new medicines for DIC therapy. Peripheral blood mononuclear cells (PBMC collected from cynomolgus monkeys were incubated with LPS (8 types, and TNF-α levels in the media were measured. LPS from Escherichia coli (K-235 was most appropriate in terms of larger increases and smaller variation in TNF-α levels. PBMC from rats, cynomolgus monkeys or humans were incubated with LPS (K-235, and the TNF-α response to LPS was investigated. The response was comparable between cynomolgus monkeys and humans but small in rats. In an in vivo experiment, LPS (K-235 was administered once intravenously to cynomolgus monkeys with or without recombinant human thrombomodulin (rhTM to investigate any changes in coagulation and fibrinolysis biomarkers and the suppressive effect of rhTM. The liver, kidney, and lung were examined histopathologically. Almost all of the changes resembled the pathophysiological status of human DIC and were suppressed by co-administration of rhTM. The DIC model resembling human DIC was established by LPS (K-235 treatment in cynomolgus monkeys, and therapeutic effect of rhTM was noted, suggesting that this model is useful in evaluations of the efficacy of new medicines for DIC therapy.

  6. Protein abundance profiling of the Escherichia coli cytosol

    DEFF Research Database (Denmark)

    Ishihama, Y.; Schmidt, T.; Rappsilber, J.

    2008-01-01

    Background: Knowledge about the abundance of molecular components is an important prerequisite for building quantitative predictive models of cellular behavior. Proteins are central components of these models, since they carry out most of the fundamental processes in the cell. Thus far, protein...... sample. Using a combination of LC-MS/MS approaches with protein and peptide fractionation steps we identified 1103 proteins from the cytosolic fraction of the Escherichia coli strain MC4100. A measure of abundance is presented for each of the identified proteins, based on the recently developed em......PAI approach which takes into account the number of sequenced peptides per protein. The values of abundance are within a broad range and accurately reflect independently measured copy numbers per cell. As expected, the most abundant proteins were those involved in protein synthesis, most notably ribosomal...

  7. LHON/MELAS overlap mutation in ND1 subunit of mitochondrial complex I affects ubiquinone binding as revealed by modeling in Escherichia coli NDH-1.

    Science.gov (United States)

    Pätsi, Jukka; Maliniemi, Pilvi; Pakanen, Salla; Hinttala, Reetta; Uusimaa, Johanna; Majamaa, Kari; Nyström, Thomas; Kervinen, Marko; Hassinen, Ilmo E

    2012-02-01

    Defects in complex I due to mutations in mitochondrial DNA are associated with clinical features ranging from single organ manifestation like Leber hereditary optic neuropathy (LHON) to multiorgan disorders like mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome. Specific mutations cause overlap syndromes combining several phenotypes, but the mechanisms of their biochemical effects are largely unknown. The m.3376G>A transition leading to p.E24K substitution in ND1 with LHON/MELAS phenotype was modeled here in a homologous position (NuoH-E36K) in the Escherichia coli enzyme and it almost totally abolished complex I activity. The more conservative mutation NuoH-E36Q resulted in higher apparent K(m) for ubiquinone and diminished inhibitor sensitivity. A NuoH homolog of the m.3865A>G transition, which has been found concomitantly in the overlap syndrome patient with the m.3376G>A, had only a minor effect. Consequences of a primary LHON-mutation m.3460G>A affecting the same extramembrane loop as the m.3376G>A substitution were also studied in the E. coli model and were found to be mild. The results indicate that the overlap syndrome-associated m.3376G>A transition in MTND1 is the pathogenic mutation and m.3865A>G transition has minor, if any, effect on presentation of the disease. The kinetic effects of the NuoH-E36Q mutation suggest its proximity to the putative ubiquinone binding domain in 49kD/PSST subunits. In all, m.3376G>A perturbs ubiquinone binding, a phenomenon found in LHON, and decreases the activity of fully assembled complex I as in MELAS.

  8. Pattern formation in Escherichia coli: A model for the pole-to-pole oscillations of Min proteins and the localization of the division site

    OpenAIRE

    2001-01-01

    Proper cell division requires an accurate definition of the division plane. In bacteria, this plane is determined by a polymeric ring of the FtsZ protein. The site of Z ring assembly in turn is controlled by the Min system, which suppresses FtsZ polymerization at noncentral membrane sites. The Min proteins in Escherichia coli undergo a highly dynamic localization cycle, during which they oscillate between the membrane of both cell halves. By using computer simulati...

  9. 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...

  10. Roles of iron acquisition systems in virulence of extraintestinal pathogenic Escherichia coli: salmochelin and aerobactin contribute more to virulence than heme in a chicken infection model

    Directory of Open Access Journals (Sweden)

    Gao Qingqing

    2012-07-01

    Full Text Available Abstract Background Avian pathogenic Escherichia coli (APEC and uropathogenic E. coli (UPEC are the two main subsets of extraintestinal pathogenic E. coli (ExPEC. Both types have multiple iron acquisition systems, including heme and siderophores. Although iron transport systems involved in the pathogenesis of APEC or UPEC have been documented individually in corresponding animal models, the contribution of these systems during simultaneous APEC and UPEC infection is not well described. To determine the contribution of each individual iron acquisition system to the virulence of APEC and UPEC, isogenic mutants affecting iron uptake in APEC E058 and UPEC U17 were constructed and compared in a chicken challenge model. Results Salmochelin-defective mutants E058ΔiroD and U17ΔiroD showed significantly decreased pathogenicity compared to the wild-type strains. Aerobactin defective mutants E058ΔiucD and U17ΔiucD demonstrated reduced colonization in several internal organs, whereas the heme defective mutants E058ΔchuT and U17ΔchuT colonized internal organs to the same extent as their wild-type strains. The triple mutant ΔchuTΔiroDΔiucD in both E058 and U17 showed decreased pathogenicity compared to each of the single mutants. The histopathological lesions in visceral organs of birds challenged with the wild-type strains were more severe than those from birds challenged with ΔiroD, ΔiucD or the triple mutants. Conversely, chickens inoculated with the ΔchuT mutants had lesions comparable to those in chickens inoculated with the wild-type strains. However, no significant differences were observed between the mutants and the wild-type strains in resistance to serum, cellular invasion and intracellular survival in HD-11, and growth in iron-rich or iron-restricted medium. Conclusions Results indicated that APEC and UPEC utilize similar iron acquisition mechanisms in chickens. Both salmochelin and aerobactin systems appeared to be important in APEC

  11. Recurrent Hemolytic and Uremic Syndrome Induced by Escherichia Coli

    Science.gov (United States)

    Commereuc, Morgane; Weill, Francois-Xavier; Loukiadis, Estelle; Gouali, Malika; Gleizal, Audrey; Kormann, Raphaël; Ridel, Christophe; Frémeaux-Bacchi, Véronique; Rondeau, Eric; Hertig, Alexandre

    2016-01-01

    Abstract A widespread belief is that typical hemolytic and uremic syndrome (HUS) does not recur. We report the case of a patient infected twice with raw milk taken from his own cow and containing a Shiga toxin–producing Escherichia coli O174:H21 that induced recurrent HUS causing severe renal and cerebral disorders. A genomic comparison of the human and bovine Shiga toxin–producing Escherichia coli O174:H21 isolates revealed that they were identical. Typical HUS may recur. Since milk from this animal was occasionally distributed locally, thereby posing a serious threat for the whole village, this particular cow was destroyed. PMID:26735524

  12. Obscured phylogeny and possible recombinational dormancy in Escherichia coli

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    Sawyer Stanley A

    2011-06-01

    Full Text Available Abstract Background Escherichia coli is one of the best studied organisms in all of biology, but its phylogenetic structure has been difficult to resolve with current data and analytical techniques. We analyzed single nucleotide polymorphisms in chromosomes of representative strains to reconstruct the topology of its emergence. Results The phylogeny of E. coli varies according to the segment of chromosome analyzed. Recombination between extant E. coli groups is largely limited to only three intergroup pairings. Conclusions Segment-dependent phylogenies most likely are legacies of a complex recombination history. However, E. coli are now in an epoch in which they no longer broadly share DNA. Using the definition of species as organisms that freely exchange genetic material, this recombinational dormancy could reflect either the end of E. coli as a species, or herald the coalescence of E. coli groups into new species.

  13. Modulation of Membrane Influx and Efflux in Escherichia coli Sequence Type 131 Has an Impact on Bacterial Motility, Biofilm Formation, and Virulence in a Caenorhabditis elegans Model

    Science.gov (United States)

    Pantel, Alix; Dunyach-Remy, Catherine; Ngba Essebe, Christelle; Mesureur, Jennifer; Sotto, Albert; Nicolas-Chanoine, Marie-Hélène

    2016-01-01

    Energy-dependent efflux overexpression and altered outer membrane permeability (influx) can promote multidrug resistance (MDR). The present study clarifies the regulatory pathways that control membrane permeability in the pandemic clone Escherichia coli sequence type 131 (ST131) and evaluates the impact of efflux and influx modulations on biofilm formation, motility, and virulence in the Caenorhabditis elegans model. Mutants of two uropathogenic E. coli (UPEC) strains, MECB5 (ST131; H30-Rx) and CFT073 (ST73), as well as a fecal strain, S250 (ST131; H22), were in vitro selected using continuous subculture in subinhibitory concentrations of ertapenem (ETP), chloramphenicol (CMP), and cefoxitin (FOX). Mutations in genes known to control permeability were shown for the two UPEC strains: MECB5-FOX (deletion of 127 bp in marR; deletion of 1 bp and insertion of an IS1 element in acrR) and CFT073-CMP (a 1-bp deletion causing a premature stop in marR). We also demonstrated that efflux phenotypes in the mutants selected with CMP and FOX were related to the AcrAB-TolC pump, but also to other efflux systems. Alteration of membrane permeability, caused by underexpression of the two major porins, OmpF and OmpC, was shown in MECB5-ETP and mutants selected with FOX. Lastly, our findings suggest that efflux pump-overproducing isolates (CMP mutants) pose a serious threat in terms of virulence (significant reduction in worm median survival) and host colonization. Lack of porins (ETP and FOX mutants) led to a high level of antibiotic resistance in an H30-Rx subclone. Nevertheless, this adaptation created a physiological disadvantage (decreased motility and ability to form biofilm) associated with a low potential for virulence. PMID:26926643

  14. Arginine Catabolism and the Arginine Succinyltransferase Pathway in Escherichia coli

    OpenAIRE

    Schneider, Barbara L.; Kiupakis, Alexandros K.; Reitzer, Lawrence J.

    1998-01-01

    Arginine catabolism produces ammonia without transferring nitrogen to another compound, yet the only known pathway of arginine catabolism in Escherichia coli (through arginine decarboxylase) does not produce ammonia. Our aims were to find the ammonia-producing pathway of arginine catabolism in E. coli and to examine its function. We showed that the only previously described pathway of arginine catabolism, which does not produce ammonia, accounted for only 3% of the arginine consumed. A search...

  15. Probability of recovering pathogenic Escherichia coli from foods.

    OpenAIRE

    Hill, W E; Ferreira, J. L; Payne, W L; Jones, V.M.

    1985-01-01

    The probability of recovering pathogenic Escherichia coli from food by the Bacteriological Analytical Manual method was determined by the effects of several factors: the number of strains per food, the ability of pathogenic strains to survive enrichment, and the frequency of plasmid loss during enrichment. Biochemical patterns indicated the presence of about six E. coli strains per food sample. About half of the strains isolated from humans did not survive enrichment. Among those which grew, ...

  16. Engineered biosynthesis of bacterial aromatic polyketides in Escherichia coli

    OpenAIRE

    Zhang, Wenjun; Li, Yanran; Tang, Yi

    2008-01-01

    Bacterial aromatic polyketides are important therapeutic compounds including front line antibiotics and anticancer drugs. It is one of the last remaining major classes of natural products of which the biosynthesis has not been reconstituted in the genetically superior host Escherichia coli. Here, we demonstrate the engineered biosynthesis of bacterial aromatic polyketides in E. coli by using a dissected and reassembled fungal polyketide synthase (PKS). The minimal PKS of the megasynthase PKS4...

  17. Osmoprotection of Escherichia coli by ectoine: uptake and accumulation characteristics.

    OpenAIRE

    Jebbar, M; Talibart, R; Gloux, K; Bernard, T.; BLANCO, C.

    1992-01-01

    Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a cyclic amino acid, identified as a compatible solute in moderately halophilic bacteria. Exogenously provided ectoine was found to stimulate growth of Escherichia coli in media of inhibitory osmotic strength. The stimulation was independent of any specific solute, electrolyte or nonelectrolyte. It is accumulated in E. coli cells proportionally to the osmotic strength of the medium, and it is not metabolized. Its osmoprotect...

  18. The comprehensive updated regulatory network of Escherichia coli K-12

    Directory of Open Access Journals (Sweden)

    Karp Peter D

    2006-01-01

    Full Text Available Abstract Background Escherichia coli is the model organism for which our knowledge of its regulatory network is the most extensive. Over the last few years, our project has been collecting and curating the literature concerning E. coli transcription initiation and operons, providing in both the RegulonDB and EcoCyc databases the largest electronically encoded network available. A paper published recently by Ma et al. (2004 showed several differences in the versions of the network present in these two databases. Discrepancies have been corrected, annotations from this and other groups (Shen-Orr et al., 2002 have been added, making the RegulonDB and EcoCyc databases the largest comprehensive and constantly curated regulatory network of E. coli K-12. Results Several groups have been using these curated data as part of their bioinformatics and systems biology projects, in combination with external data obtained from other sources, thus enlarging the dataset initially obtained from either RegulonDB or EcoCyc of the E. coli K12 regulatory network. We kindly obtained from the groups of Uri Alon and Hong-Wu Ma the interactions they have added to enrich their public versions of the E. coli regulatory network. These were used to search for original references and curate them with the same standards we use regularly, adding in several cases the original references (instead of reviews or missing references, as well as adding the corresponding experimental evidence codes. We also corrected all discrepancies in the two databases available as explained below. Conclusion One hundred and fifty new interactions have been added to our databases as a result of this specific curation effort, in addition to those added as a result of our continuous curation work. RegulonDB gene names are now based on those of EcoCyc to avoid confusion due to gene names and synonyms, and the public releases of RegulonDB and EcoCyc are henceforth synchronized to avoid confusion due to

  19. Combined ozone and ultraviolet inactivation of Escherichia coli.

    Science.gov (United States)

    Magbanua, Benjamin S; Savant, Gaurav; Truax, Dennis D

    2006-01-01

    The kinetics of Escherichia coli inactivation using ozone and ultraviolet (UV) radiation, separately and simultaneously, was evaluated at 25 degrees C in buffered (pH 6.0, 7.0 and 8.0), demand-free media. While ozone was found to be a stronger disinfectant than UV radiation, using both simultaneously was more effective than using them individually. Inactivation kinetics was pseudo first-order for the three treatment processes, while the disinfection rate was a linear function of the disinfectant dose. The synergism observed in microbial inactivation when the disinfectant processes were combined was illustrated by estimates of kinetic model parameters. This synergy was attributed to the generation of hydroxyl radicals via ozone photolysis. Subsequently, dosage calculations, as based on disinfectant level and exposure time, indicated that the simultaneous use of UV and ozone could substantially reduce their individual doses.

  20. Failed Escape: Solid Surfaces Prevent Tumbling of Escherichia coli

    Science.gov (United States)

    Molaei, Mehdi; Barry, Michael; Stocker, Roman; Sheng, Jian

    2014-08-01

    Understanding how bacteria move close to surfaces is crucial for a broad range of microbial processes including biofilm formation, bacterial dispersion, and pathogenic infections. We used digital holographic microscopy to capture a large number (>103) of three-dimensional Escherichia coli trajectories near and far from a surface. We found that within 20 μm from a surface tumbles are suppressed by 50% and reorientations are largely confined to surface-parallel directions, preventing escape of bacteria from the near-surface region. A hydrodynamic model indicates that the tumble suppression is likely due to a surface-induced reduction in the hydrodynamic force responsible for the flagellar unbundling that causes tumbling. These findings imply that tumbling does not provide an effective means to escape trapping near surfaces.

  1. Escherichia coli strain Nissle 1917 ameliorates experimental colitis by modulating intestinal permeability, the inflammatory response and clinical signs in a faecal transplantation model.

    Science.gov (United States)

    Souza, Éricka L; Elian, Samir D; Paula, Laís M; Garcia, Cristiana C; Vieira, Angélica T; Teixeira, Mauro M; Arantes, Rosa M; Nicoli, Jacques R; Martins, Flaviano S

    2016-03-01

    Inflammatory bowel diseases (IBDs) are a group of inflammatory conditions of the gut that include ulcerative colitis and Crohn's disease. Probiotics are live micro-organisms that may be used as adjuvant therapy for patients with IBD. The aim of this study was to evaluate the effect of prophylactic ingestion of Escherichia coli strain Nissle 1917 (EcN) in a murine model of colitis. For induction of colitis, mice were given a 3.5% dextran sodium sulfate (DSS) solution for 7 days in drinking water. EcN administration to mice subjected to DSS-induced colitis resulted in significant reduction in clinical and histopathological signs of disease and preservation of intestinal permeability. We observed reduced inflammation, as assessed by reduced levels of neutrophils, eosinophils, chemokines and cytokines. We observed an increase in the number of regulatory T-cells in Peyer's patches. Germ-free mice received faecal content from control or EcN-treated mice and were then subjected to DSS-induced colitis. We observed protection from colitis in animals that were colonized with faecal content from EcN-treated mice. These results suggest that preventative oral administration of EcN or faecal microbiota transplantation with EcN-containing microbiota ameliorates DSS-induced colitis by modifying inflammatory responsiveness to DSS.

  2. Anti-inflammatory effects of insulin regular and flunixin meglumine on endotoxemia experimentally induced by Escherichia coli serotype O55:B5 in an ovine model.

    Science.gov (United States)

    Chalmeh, Aliasghar; Badiei, Khalil; Pourjafar, Mehrdad; Nazifi, Saeed

    2013-01-01

    Endotoxemia is a major cause of mortality in large animals and there are several therapeutic regimens for the treatment of endotoxemia. Recent studies have suggested the anti-inflammatory effects of insulin in endotoxemic human and laboratory animal models but to the best of our knowledge there is no report on the possible therapeutic effect of insulin in large animal endotoxemia. This experiment was conducted to evaluate the anti-inflammatory effects of insulin regular compared with flunixin meglumine on the treatment of endotoxemia in sheep. Lipopolysaccharide from Escherichia coli was administered intravenously to ewes. Anti-inflammatory effects of flunixin meglumine (at 2.2 mg/kg) and insulin regular (at 1.5 and 3 IU/kg) were evaluated by determination of serum concentrations of acute phase proteins, inflammatory cytokines and oxidative stress biomarkers. Insulin regular at 3 IU/kg controlled the acute phase response following endotoxemia induction. The anti-inflammatory potency of insulin regular at 3 IU/kg was significantly higher than at 1.5 IU/kg and of flunixin meglumine at 2.2 mg/kg (P < 0.05). Insulin regular induces its anti-inflammatory effects in a dose-dependent manner. Intravenous use of insulin regular can be a potential new therapeutic regimen for endotoxemia in large animal medicine.

  3. Detection of virulence factors of Uropathoigenic Escherichia coli isolates from infertile women high vaginal swabs

    Directory of Open Access Journals (Sweden)

    Farhad Safarpourdehkourdi

    2014-03-01

    Conclusion: The high vaginal Escherichia coli harbored certain virulence genes of uropathogenic Escherichia coli strains. The urinary tract infections should be treated well to diminish its upstream transfer into vagina. Some more investigation should be perform for identifying the epidemiological aspects of uropathogenic Escherichia coli in high vaginal part of infertile women.

  4. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Science.gov (United States)

    2011-11-23

    ... Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service... methods for controlling non-O157 Shiga toxin-producing Escherichia coli in raw, intact and non-intact beef... Escherichia coli in raw, intact and non-intact beef products and product components on or before December...

  5. [The clinical characteristics analysis of Escherichia coli bloodstream infection].

    Science.gov (United States)

    Zhang, M; Huang, J A; Chen, Y B

    2016-05-17

    To explore the clinical features of Escherichia coli bloodstream infection. The clinical data of underlying diseases, antimicrobial susceptibility, temperature at blood sampling, results of routine blood tests, venous catheterization, therapy and prognosis of Escherichia coli bloodstream infection in the First Affiliated Hospital of Soochow University from January 2007 to December 2014 were analyzed retrospectively. The pathogens were routinely isolated and identified. Susceptibilities against antimicrobial agents were determined by Kirby-Bauer methods. All patients had at least one underlying disease. Most of the basic diseases were hematological malignancies, malignant solid tumors, pneumonia and so on. Body temperature was normal in 40 patients (6.4%), fever in 587 patients (93.5%) and low temperature in 1 patient. There were 252 patients with leukopenia (40.1%), 237 patients with granulocytopenia (37.7%) and 216 patients with agranulocytosis. The resistance rate to imipenem was 3.3%, which was the lowest among the total antimicrobial susceptibilities of 628 Escherichia Coli. The extended-spectrum-β-lactamase (ESBL)-producing strains accounted for 53.8% among the total patients. The resistance rates of ESBLs-producing-Escherichia coli for the Sulfamethoxazole, Ampicillin, Gentamicin, Cefazolin, Cefuroxime, Cefotaxime, Ceftriaxone, Cefepime, Ceftazidime, Cefoperazone, Piperacillin and Ciprofloxacin were 80.2%, 100.0%, 62.4%, 99.1%, 99.1%, 98.8%, 98.2%, 48.5%, 50.6%, 95.0%, 98.2%, 79.6%, respectively, which were higher than that of non-ESBLs-producing-Escherichia coli (67.9%, 79.7%, 47.6%, 50.0%, 47.2%, 41.0%, 40.3%, 27.2%, 24.1%, 40.0%, 56.2%, 58.3%, respectively), the differences were significant statistically (χ(2)=12.33, 75.90, 13.92, 209.00, 224.94, 259.25, 256.59, 27.79, 46.19, 222.85, 165.08, 33.59, all PEscherichia coli bloodstream infection. The antimicrobial resistance rate of ESBLs-producing-Escherichia coli is higher than that of none-ESBLs-producing-Escherichia

  6. Cervical celullitis in broiler chickens for Escherichia coli/ Celulite cervical em frangos de corte causada por Escherichia coli

    Directory of Open Access Journals (Sweden)

    Ivens Gomes Guimarães

    2002-05-01

    Full Text Available In this paper was report the isolation of Escherichia coli in broiler chickens with cellulitis in the cervical region. It was carried through the isolation of E. coli of the lesion of cellulitis from broilers and carried through histopathological examination of skin that had characterized the lesion. Focal ulcerations of epidermis, fibrin in dermis and difuse infiltrated by lymphocytes and heterophils on subcutaneous tissues.Neste trabalho, relata-se o isolamento de Escherichia coli em frangos de corte apresentando lesão de celulite na região cervical. Foi realizado o isolamento de E. coli da lesão de celulite e realizado exames histopatológicos que caracterizaram a lesão. Na epiderme foram verificadas lesões ulcerativas, presença de fibrina na derme e infiltração difusa de linfócitos e heterófilos no tecido subcutâneo.

  7. Release factor one is nonessential in Escherichia coli.

    Science.gov (United States)

    Johnson, David B F; Wang, Chong; Xu, Jianfeng; Schultz, Matthew D; Schmitz, Robert J; Ecker, Joseph R; Wang, Lei

    2012-08-17

    Recoding a stop codon to an amino acid may afford orthogonal genetic systems for biosynthesizing new protein and organism properties. Although reassignment of stop codons has been found in extant organisms, a model organism is lacking to investigate the reassignment process and to direct code evolution. Complete reassignment of a stop codon is precluded by release factors (RFs), which recognize stop codons to terminate translation. Here we discovered that RF1 could be unconditionally knocked out from various Escherichia coli stains, demonstrating that the reportedly essential RF1 is generally dispensable for the E. coli species. The apparent essentiality of RF1 was found to be caused by the inefficiency of a mutant RF2 in terminating all UAA stop codons; a wild type RF2 was sufficient for RF1 knockout. The RF1-knockout strains were autonomous and unambiguously reassigned UAG to encode natural or unnatural amino acids (Uaas) at multiple sites, affording a previously unavailable model for studying code evolution and a unique host for exploiting Uaas to evolve new biological functions.

  8. Solvent effects on catalysis by Escherichia coli dihydrofolate reductase.

    Science.gov (United States)

    Loveridge, E Joel; Tey, Lai-Hock; Allemann, Rudolf K

    2010-01-27

    Hydride transfer catalyzed by dihydrofolate reductase (DHFR) has been described previously within an environmentally coupled model of hydrogen tunneling, where protein motions control binding of substrate and cofactor to generate a tunneling ready conformation and modulate the width of the activation barrier and hence the reaction rate. Changes to the composition of the reaction medium are known to perturb protein motions. We have measured kinetic parameters of the reaction catalyzed by DHFR from Escherichia coli in the presence of various cosolvents and cosolutes and show that the dielectric constant, but not the viscosity, of the reaction medium affects the rate of reaction. Neither the primary kinetic isotope effect on the reaction nor its temperature dependence were affected by changes to the bulk solvent properties. These results are in agreement with our previous report on the effect of solvent composition on catalysis by DHFR from the hyperthermophile Thermotoga maritima. However, the effect of solvent on the temperature dependence of the kinetic isotope effect on hydride transfer catalyzed by E. coli DHFR is difficult to explain within a model, in which long-range motions couple to the chemical step of the reaction, but may indicate the existence of a short-range promoting vibration or the presence of multiple nearly isoenergetic conformational substates of enzymes with similar but distinct catalytic properties.

  9. YeeO from Escherichia coli exports flavins.

    Science.gov (United States)

    McAnulty, Michael J; Wood, Thomas K

    2014-01-01

    Multidrug and toxic compound extrusion (MATE) proteins help maintain cellular homeostasis by secreting metabolic wastes. Flavins may occur as cellular waste products, with their production and secretion providing potential benefit for industrial applications related to biofuel cells. Here we find that MATE protein YeeO from Escherichia coli exports both flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Significant amounts of flavins were trapped intracellularly when YeeO was produced indicating transport limits secretion of flavins. Wild-type E. coli secreted 3 flavins (riboflavin, FMN, and FAD), so E. coli likely produces additional flavin transporters.

  10. Escherichia coli O26 IN RAW BUFFALO MILK: PRELIMINARY RESULTS

    Directory of Open Access Journals (Sweden)

    A. Rella

    2013-02-01

    Full Text Available Escherichia coli O26 is considered to be one of the most important food-borne pathogen. In this study, 120 buffalo milk samples collected in Lazio and in Apulia regions were tested for the presence of E. coli O26. One buffalo milk sample (0,8% tested positive for E. coli O26; the isolate was positive at the verocytotoxicity test and it showed resistance properties to different antimicrobial classes. These preliminary results highlight the need to monitor the foods of animal origin used for production and eaten by a wide range of persons, respect VTEC organism.

  11. antimicrobial susceptibility and plasmids from escherichia coli ...

    African Journals Online (AJOL)

    2001-10-10

    Oct 10, 2001 ... transmission to humans of E. coli containing antibiotic resistance plasmids ... resistant micro-organisms, which may in turn transfer resistance to .... cells were washed with sterile normal saline to remove leached. Я-lactamase ...

  12. Antibiotic treatment of verocytotoxin-producing Escherichia coli (VTEC) infection

    DEFF Research Database (Denmark)

    Agger, Morten; Scheutz, Flemming; Villumsen, Steen;

    2015-01-01

    OBJECTIVES: A consensus has existed on not to treat verocytotoxin-producing Escherichia coli (VTEC)-infected individuals with antibiotics because of possible subsequent increased risk of developing haemolytic uraemic syndrome (HUS). The aim of this systematic review is to clarify the risk...

  13. Escherichia coli mutants with a temperature-sensitive alcohol dehydrogenase.

    OpenAIRE

    Lorowitz, W; Clark, D.

    1982-01-01

    Mutants of Escherichia coli resistant to allyl alcohol were selected. Such mutants were found to lack alcohol dehydrogenase. In addition, mutants with temperature-sensitive alcohol dehydrogenase activity were obtained. These mutations, designated adhE, are all located at the previously described adh regulatory locus. Most adhE mutants were also defective in acetaldehyde dehydrogenase activity.

  14. New types of Escherichia coli recombination-deficient mutants.

    Science.gov (United States)

    Freifelder, D

    1976-11-01

    A set of Escherichia coli mutants deficient in intramolecular recombination and different from those previously found is described. All have temperature-sensitive lethal mutations. The mutants have been characterized with respect to the following properties: the Pap phenotype, deoxyribonucleic acid synthesis, sensitivity to ultraviolet light, ability to support the growth of phage lambda, filament formation, and mutation frequency.

  15. Escherichia coli and virus isolated from ''sticky kits''

    DEFF Research Database (Denmark)

    Jørgensen, M.; Scheutz, F.; Strandbygaard, Bertel

    1996-01-01

    A total of 121 Escherichia coli strains isolated from 3-week-old mink kits were serotyped and examined for virulence factors. 56 strains were isolated from healthy kits while 65 were from ''sticky kits''. Among these, 34 different serotypes were detected. No difference in serotypes or the presenc...

  16. armA and aminoglycoside resistance in Escherichia coli.

    Science.gov (United States)

    González-Zorn, Bruno; Teshager, Tirushet; Casas, María; Porrero, María C; Moreno, Miguel A; Courvalin, Patrice; Domínguez, Lucas

    2005-06-01

    We report armA in an Escherichia coli pig isolate from Spain. The resistance gene was borne by self-transferable IncN plasmid pMUR050. Molecular analysis of the plasmid and of the armA locus confirmed the spread of this resistance determinant.

  17. armA and Aminoglycoside Resistance in Escherichia coli

    OpenAIRE

    González-Zorn, Bruno; Teshager, Tirushet; Casas, María; Porrero, María C.; Moreno, Miguel A.; Courvalin, Patrice; Domínguez, Lucas

    2005-01-01

    We report armA in an Escherichia coli pig isolate from Spain. The resistance gene was borne by self-transferable IncN plasmid pMUR050. Molecular analysis of the plasmid and of the armA locus confirmed the spread of this resistance determinant.

  18. Combating enteropathogenic Escherichia coli (EPEC) infections: the way forward

    OpenAIRE

    Michael S Donnenberg; Finlay, B. Brett

    2013-01-01

    Enteropathogenic Escherichia coli (EPEC) strains continue to cause severe and sometimes fatal infantile diarrhea, particularly in Africa. Increased efforts at diagnosis, defining the clinical spectrum of disease, understanding pathogenic mechanisms, and delineating immune responses are desperately needed to develop new strategies to combat EPEC.

  19. Characterization of Escherichia coli nucleoids released by osmotic shock.

    NARCIS (Netherlands)

    Wegner, A.S.; Alexeeva, S.; Odijk, T.; Woldringh, C.L.

    2012-01-01

    Nucleoids were isolated by osmotic shock from Escherichia coli spheroplasts at relatively low salt concentrations and in the absence of detergents. Sucrose-protected cells, made osmotically sensitive by growth in the presence of ampicillin or by digestion with low lysozyme concentrations (50-5 μg/ml

  20. Characterization of Escherichia coli nucleoids released by osmotic shock

    NARCIS (Netherlands)

    Wegner, S.; Alexeeva, S.V.; Odijk, T.; Woldringh, C.L.

    2012-01-01

    Nucleoids were isolated by osmotic shock from Escherichia coli spheroplasts at relatively low salt concentrations and in the absence of detergents. Sucrose-protected cells, made osmotically sensitive by growth in the presence of ampicillin or by digestion with low lysozyme concentrations (50–5 µg/ml

  1. Immunologic Control of Diarrheal Disease Due to Enterotoxigenic Escherichia coli

    Science.gov (United States)

    1984-01-01

    Classical Enteropathogenic (Serotyped) Escherichia coli Strains of Proven Pathogenicity. Infect. Immun. 38:798-801, 1982. 8. Levine, M.M. Vacunas Contra...Microbiol., 18:808-815, 1983. 8 15. Levine, M.M., Lanata, C. Progresos en Vacunas Contra Diarrea Bacteriana. Adelantos Microbiol. Enferm. Inf., 2:67-117

  2. Sequencing of Escherichia coli that cause persistent and transient Mastitis

    Science.gov (United States)

    The genomes of two strains of Escherichia coli that cause bovine mastitis were sequenced. These strains are known to be associated with persistent and transient mastitis: strain ECA-B causes a transient infection, and ECC-M leads to a persistent infection....

  3. Comparative Genomics of Escherichia coli Strains Causing Urinary Tract Infections

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Hancock, Viktoria; Schembri, Mark A.

    2011-01-01

    The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range...

  4. Inactivation of Escherichia coli by titanium dioxide photocatalytic oxidation.

    Science.gov (United States)

    Titanium dioxide in the anatase crystalline form was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed on pure cultures of Escherichia coli in dechlorinated tap water and a surface water sample to evaluate the disinfe...

  5. Chromosomal replication incompatibility in Dam methyltransferase deficient Escherichia coli cells

    DEFF Research Database (Denmark)

    Freiesleben, Ulrik Von

    1996-01-01

    Dam methyltransferase deficient Escherichia coli cells containing minichromosomes were constructed. Free plasmid DNA could not be detected in these cells and the minichromosomes were found to be integrated in multiple copies in the origin of replication (oriC) region of the host chromosome...

  6. FimH-mediated autoaggregation of Escherichia coli

    DEFF Research Database (Denmark)

    Schembri, Mark; Christiansen, G.; Klemm, Per

    2001-01-01

    Autoaggregation is a phenomenon thought to contribute to colonization of mammalian hosts by pathogenic bacteria. Type 1 fimbriae are surface organelles of Escherichia coli that mediate D-mannose-sensitive binding to various host surfaces. This binding is conferred by the minor fimbrial component...

  7. DNA supercoiling depends on the phosphorylation potential in Escherichia coli

    DEFF Research Database (Denmark)

    Van Workum, M.; van Dooren, S.J.M; Oldenburg, N

    1996-01-01

    ATP/ADP ratios were varied in different ways and the degree of negative supercoiling was determined in Escherichia coli. Independent of whether the ATP/ADP ratio was reduced by a shift to anaerobic conditions, by addition of protonophore (dinitrophenol) or by potassium cyanide addition, DNA...

  8. Novel Aggregative Adherence Fimbria Variant of Enteroaggregative Escherichia coli

    DEFF Research Database (Denmark)

    Jønsson, Rie; Struve, Carsten; Boisen, Nadia

    2015-01-01

    Enteroaggregative Escherichia coli (EAEC) organisms belong to a diarrheagenic pathotype known to cause diarrhea and can be characterized by distinct aggregative adherence (AA) in a stacked-brick pattern to cultured epithelial cells. In this study, we investigated 118 EAEC strains isolated from...

  9. 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...

  10. Suppressors of DnaAATP imposed overinitiation in Escherichia coli

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Riber, Leise; Cohen, Malene

    2011-01-01

    Chromosome replication in Escherichia coli is limited by the supply of DnaA associated with ATP. Cells deficient in RIDA (Regulatory Inactivation of DnaA) due to a deletion of the hda gene accumulate suppressor mutations (hsm) to counteract the overinitiation caused by an elevated DnaAATP level...

  11. Differential expression of the Escherichia coli autoaggregation factor antigen 43

    DEFF Research Database (Denmark)

    Schembri, Mark; Hjerrild, Louise; Gjermansen, Morten

    2003-01-01

    Antigen 43 (Ag43) is a self-recognizing surface adhesin found in most Escherichia coli strains. Due to its excellent cell-to-cell aggregation characteristics, Ag43 expression confers clumping and fluffing of cells and promotes biofilm formation. Ag43 expression is repressed by the cellular redox...

  12. Molecular characterization of the Escherichia coli asymptomatic bacteriuria strain 83972

    DEFF Research Database (Denmark)

    Klemm, Per; Hancock, Viktoria; Ulett, G.C.

    2006-01-01

    Escherichia coli 83972 is a clinical asymptomatia bacteriuric isolate that is able to colonize the human urinary bladder without inducing an immune response. Here we demonstrate that one of the mechanisms by which this strain has become attenuated is through the mutation of its genes encoding type...

  13. Binding of divalent magnesium by Escherichia coli phosphoribosyl diphosphate synthetase

    DEFF Research Database (Denmark)

    Willemoës, Martin; Hove-Jensen, Bjarne

    1997-01-01

    The mechanism of binding of the substrates Mg x ATP and ribose 5-phosphate as well as Mg2+ to the enzyme 5-phospho-D-ribosyl (alpha-1-diphosphate synthetase from Escherichia coli has been analyzed. By use of the competive inhibitors of ATP and ribose 5-phosphate binding, alpha,beta-methylene ATP ...

  14. A rapid differentiation method for enteroinvasive Escherichia coli.

    Science.gov (United States)

    Aribam, Swarmistha Devi; Hirota, Jiro; Kusumoto, Masahiro; Harada, Tomoyuki; Shiraiwa, Kazumasa; Ogawa, Yohsuke; Shimoji, Yoshihiro; Eguchi, Masahiro

    2014-03-01

    Enteroinvasive Escherichia coli (EIEC) comprise 21 major serotypes defined by the presence of O and H antigens, and diagnosis depends on determining its invasive potential. Using HEp-2 cells infected with an EIEC strain, we developed a simple growth-dependent assay that differentiated EIEC strain from non-invasive strains 6 h after infection.

  15. Kwantitatief gevoeligheidsonderzoek met intra- en extramurale isolaten van Escherichia coli

    NARCIS (Netherlands)

    de Neeling AJ; de Jong J; Overbeek BP; de Bruin RW; Dessens-Kroon M; van Klingeren B

    1990-01-01

    Three Dutch laboratories for medical microbiology collected a total number of 1432 strains of Escherichia coli. Of these 995 were obtained from routine samples taken in clinic and policlinic, 290 had been sent spontaneously by general practitioners for microbiological examination and 147 had been i

  16. Molecular characterization of the Escherichia coli asymptomatic bacteriuria strain 83972

    DEFF Research Database (Denmark)

    Klemm, Per; Hancock, Viktoria; Ulett, G.C.

    2006-01-01

    Escherichia coli 83972 is a clinical asymptomatia bacteriuric isolate that is able to colonize the human urinary bladder without inducing an immune response. Here we demonstrate that one of the mechanisms by which this strain has become attenuated is through the mutation of its genes encoding typ...

  17. Fragility of the permeability barrier of Escherichia coli

    NARCIS (Netherlands)

    Haest, C.W.M.; Gier, J. de; Es, G.A. van; Verkleij, A.J.; Deenen, L.L.M. van

    1972-01-01

    An unsaturated fatty acid requiring auxotroph of Escherichia coli was grown with addition of various unsaturated fatty acids. The permeability of the cells for erythritol appeared to be strongly dependent on the fatty acid incorporated in the membrane lipid. Below certain temperatures, depending on

  18. Stringent control of FLP recombinase in Escherichia coli.

    Science.gov (United States)

    Bowden, Steven D; Palani, Nagendra P; Libourel, Igor G L

    2017-02-01

    Site specific recombinases are invaluable tools in molecular biology, and are emerging as powerful recorders of cellular events in synthetic biology. We have developed a stringently controlled FLP recombinase system in Escherichia coli using an arabinose inducible promoter combined with a weak ribosome binding site.

  19. Escherichia coli and other Enterobacteriaceae: Food poisoning and health effects

    Science.gov (United States)

    The family Enterobactericeae consists of rod-shaped, Gram-negative, facultatively anaerobic, non-spore forming bacteria and also includes the food-borne pathogens, Cronobacter spp., Escherichia coli, Salmonella enterica, Shigella spp., and Yersinia spp. Illness caused by these pathogens is acquired...

  20. Escherichia coli as other Enterobacteriaceae: food poisoning and health effects

    Science.gov (United States)

    Many Escherichia coli strains are harmless, and they are an important commensal in the intestinal microflora; however, pathogenic strains also exist. The pathogenic strains can be divided into diarrhea-inducing strains and strains that reside in the intestines but only cause disease in bodily sites...

  1. Plasmid cloning vehicle for Haemophilus influenzae and Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, D.; Clayton, N.L.; Setlow, J.K.

    1982-09-01

    A new plasmid cloning vehicle (pDM2) was used to introduce a library of Haemophilus influenzae chromosomal fragments into H. influenzae. Transformants of the higly recombination-defective rec-1 mutant were more likely to contain exclusively recombinant plasmids after exposure to ligated DNA mixtures than was the wild type. pDM2 could replicate in Escherichia coli K-12.

  2. Norfloxacin resistance in a clinical isolate of Escherichia coli.

    Science.gov (United States)

    Aoyama, H; Sato, K; Kato, T; Hirai, K; Mitsuhashi, S

    1987-01-01

    Analysis of DNA gyrase supercoiling and of norfloxacin uptake in Escherichia coli GN14176, a moderately norfloxacin-resistant clinical isolate, indicated that resistance was associated with both an altered drug target and a reduction in drug uptake. Images PMID:2829712

  3. Kwantitatief gevoeligheidsonderzoek met intra- en extramurale isolaten van Escherichia coli

    NARCIS (Netherlands)

    de Neeling AJ; de Jong J; Overbeek BP; de Bruin RW; Dessens-Kroon M; van Klingeren B

    1990-01-01

    Three Dutch laboratories for medical microbiology collected a total number of 1432 strains of Escherichia coli. Of these 995 were obtained from routine samples taken in clinic and policlinic, 290 had been sent spontaneously by general practitioners for microbiological examination and 147 had been

  4. Escherichia coli bacteria density in relation to turbidity, streamflow characteristics, and season in the Chattahoochee River near Atlanta, Georgia, October 2000 through September 2008—Description, statistical analysis, and predictive modeling

    Science.gov (United States)

    Lawrence, Stephen J.

    2012-01-01

    Water-based recreation—such as rafting, canoeing, and fishing—is popular among visitors to the Chattahoochee River National Recreation Area (CRNRA) in north Georgia. The CRNRA is a 48-mile reach of the Chattahoochee River upstream from Atlanta, Georgia, managed by the National Park Service (NPS). Historically, high densities of fecal-indicator bacteria have been documented in the Chattahoochee River and its tributaries at levels that commonly exceeded Georgia water-quality standards. In October 2000, the NPS partnered with the U.S. Geological Survey (USGS), State and local agencies, and non-governmental organizations to monitor Escherichia coli bacteria (E. coli) density and develop a system to alert river users when E. coli densities exceeded the U.S. Environmental Protection Agency (USEPA) single-sample beach criterion of 235 colonies (most probable number) per 100 milliliters (MPN/100 mL) of water. This program, called BacteriALERT, monitors E. coli density, turbidity, and water temperature at two sites on the Chattahoochee River upstream from Atlanta, Georgia. This report summarizes E. coli bacteria density and turbidity values in water samples collected between 2000 and 2008 as part of the BacteriALERT program; describes the relations between E. coli density and turbidity, streamflow characteristics, and season; and describes the regression analyses used to develop predictive models that estimate E. coli density in real time at both sampling sites.

  5. IDENTIFICATION OF UROVIRULENT MARKERS IN UROPATHOGE NIC ESCHERICHIA COLI.

    Directory of Open Access Journals (Sweden)

    Padmaja

    2012-10-01

    Full Text Available The present study was conducted in the Department o f Microbiology, Konaseema Institute of Medical Sciences, Amalapuram, East Goda vari District from August 2011 to January 2012. Fifty Escherichia coli (E.coli strains isola ted from urine samples of different clinical entities and 25 feacal isolates were studied for th e detection of virulence markers of E.coli. There are 27 uropathogenic E.coli (UPEC isolates fr om 50 E.coli & 5 UPEC from 25 controls. Among isolates tested the most common virulent mark er is haemolysin 21 (42%, followed by Mannose resistant haemagglutination 16 (32%, cell surface hydrophobicity 13 (26%. In this, there are 14 cases with only one virulence marker, 8 with 2 marker combinations and 15 cases with combination of 3 markers.

  6. Phylogenetic Group Determination of Escherichia coli Isolated from Animals Samples

    Directory of Open Access Journals (Sweden)

    Fernanda Morcatti Coura

    2015-01-01

    Full Text Available This study analyzes the occurrence and distribution of phylogenetic groups of 391 strains of Escherichia coli isolated from poultry, cattle, and water buffalo. The frequency of the phylogroups was A = 19%, B1 = 57%, B2 = 2.3%, C = 4.6%, D = 2.8%, E = 11%, and F = 3.3%. Phylogroups A (P<0.001 and F (P=0.018 were associated with E. coli strains isolated from poultry, phylogroups B1 (P<0.001 and E (P=0.002 were associated with E. coli isolated from cattle, and phylogroups B2 (P=0.003 and D (P=0.017 were associated with E. coli isolated from water buffalo. This report demonstrated that some phylogroups are associated with the host analyzed and the results provide knowledge of the phylogenetic composition of E. coli from domestic animals.

  7. Lack of the RNA chaperone hfq attenuates pathogenicity of several Escherichia coli pathotypes towards Caenorhabditis elegans

    DEFF Research Database (Denmark)

    Bojer, Martin Saxtorph; Jakobsen, Henrik; Struve, Carsten;

    2012-01-01

    as a model for virulence characterization and screening for novel antimicrobial entities. Several E. coli human pathotypes are also pathogenic towards C. elegans, and we show here that lack of the RNA chaperone Hfq significantly reduces pathogenicity of VTEC, EAEC, and UPEC in the nematode model. Thus, Hfq...... is intrinsically essential to pathogenic E. coli for survival and virulence exerted in the C. elegans host.......Escherichia coli is an important agent of Gram-negative bacterial infections worldwide, being one of the leading causes of diarrhoea and urinary tract infections. Strategies to understand pathogenesis and develop therapeutic compounds include the use of the nematode Caenorhabditis elegans...

  8. MODELING THE SURVIVAL OF ESCHERICHIA COLI O157:H7, LISTERIA MONOCYTOGENES AND SALMONELLA TYPHIMURIUM DURING FERMENTATION, DRYING, AND STORAGE OF SOUDJOUK-STYLE FEREMENTED SAUSAGE

    Science.gov (United States)

    Outbreaks of foodborne illnesses have been linked to the consumption of fermented dry and semi-dry sausage (FDDS) contaminated with E. coli O157:H7 and Salmonella spp. This study quantified and modeled the survival of E. coli O157:H7, L. monocytogenes and S. typhimurium in soudjouk-style sausage ...

  9. Invariant distribution of promoter activities in Escherichia coli.

    Science.gov (United States)

    Zaslaver, Alon; Kaplan, Shai; Bren, Anat; Jinich, Adrian; Mayo, Avi; Dekel, Erez; Alon, Uri; Itzkovitz, Shalev

    2009-10-01

    Cells need to allocate their limited resources to express a wide range of genes. To understand how Escherichia coli partitions its transcriptional resources between its different promoters, we employ a robotic assay using a comprehensive reporter strain library for E. coli to measure promoter activity on a genomic scale at high-temporal resolution and accuracy. This allows continuous tracking of promoter activity as cells change their growth rate from exponential to stationary phase in different media. We find a heavy-tailed distribution of promoter activities, with promoter activities spanning several orders of magnitude. While the shape of the distribution is almost completely independent of the growth conditions, the identity of the promoters expressed at different levels does depend on them. Translation machinery genes, however, keep the same relative expression levels in the distribution across conditions, and their fractional promoter activity tracks growth rate tightly. We present a simple optimization model for resource allocation which suggests that the observed invariant distributions might maximize growth rate. These invariant features of the distribution of promoter activities may suggest design constraints that shape the allocation of transcriptional resources.

  10. Invariant distribution of promoter activities in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Alon Zaslaver

    2009-10-01

    Full Text Available Cells need to allocate their limited resources to express a wide range of genes. To understand how Escherichia coli partitions its transcriptional resources between its different promoters, we employ a robotic assay using a comprehensive reporter strain library for E. coli to measure promoter activity on a genomic scale at high-temporal resolution and accuracy. This allows continuous tracking of promoter activity as cells change their growth rate from exponential to stationary phase in different media. We find a heavy-tailed distribution of promoter activities, with promoter activities spanning several orders of magnitude. While the shape of the distribution is almost completely independent of the growth conditions, the identity of the promoters expressed at different levels does depend on them. Translation machinery genes, however, keep the same relative expression levels in the distribution across conditions, and their fractional promoter activity tracks growth rate tightly. We present a simple optimization model for resource allocation which suggests that the observed invariant distributions might maximize growth rate. These invariant features of the distribution of promoter activities may suggest design constraints that shape the allocation of transcriptional resources.

  11. Subversion of Host Innate Immunity by Uropathogenic Escherichia coli.

    Science.gov (United States)

    Olson, Patrick D; Hunstad, David A

    2016-01-04

    Uropathogenic Escherichia coli (UPEC) cause the majority of community-onset urinary tract infections (UTI) and represent a major etiologic agent of healthcare-associated UTI. Introduction of UPEC into the mammalian urinary tract evokes a well-described inflammatory response, comprising pro-inflammatory cytokines and chemokines as well as cellular elements (neutrophils and macrophages). In human UTI, this inflammatory response contributes to symptomatology and provides means for diagnosis by standard clinical testing. Early in acute cystitis, as demonstrated in murine models, UPEC gains access to an intracellular niche that protects a population of replicating bacteria from arriving phagocytes. To ensure the establishment of this protected niche, UPEC employ multiple strategies to attenuate and delay the initiation of host inflammatory components, including epithelial secretion of chemoattractants. Recent work has also revealed novel mechanisms by which UPEC blunts neutrophil migration across infected uroepithelium. Taken together, these attributes distinguish UPEC from commensal and nonpathogenic E. coli strains. This review highlights the unique immune evasion and suppression strategies of this bacterial pathogen and offers directions for further study; molecular understanding of these mechanisms will inform the development of adjunctive, anti-virulence therapeutics for UTI.

  12. Evolution of the iss gene in Escherichia coli.

    Science.gov (United States)

    Johnson, Timothy J; Wannemuehler, Yvonne M; Nolan, Lisa K

    2008-04-01

    The increased serum survival gene iss has long been recognized for its role in extraintestinal pathogenic Escherichia coli (ExPEC) virulence. iss has been identified as a distinguishing trait of avian ExPEC but not of human ExPEC. This gene has been localized to large virulence plasmids and shares strong similarities with the bor gene from bacteriophage lambda. Here, we demonstrate that three alleles of iss occur among E. coli isolates that appear to have evolved from a common lambda bor precursor. In addition to the occurrence of iss on the ColV/BM virulence plasmids, at least two iss alleles occur within the E. coli chromosome. One of these alleles (designated type 3) was found to occur in the genomes of all currently sequenced ExPEC strains on a similar prophage element that also harbors the Sit iron and manganese transport system. When the prevalence of the three iss types was examined among 487 E. coli isolates, the iss type 3 gene was found to occur at a high frequency among ExPEC isolates, irrespective of the host source. The plasmid-borne iss allele (designated type 1) was highly prevalent among avian pathogenic E. coli and neonatal meningitis-associated E. coli isolates but not among uropathogenic E. coli isolates. This study demonstrates the evolution of iss in E. coli and provides an additional tool for discriminating among E. coli pathotypes through the differentiation of the three iss allele types and bor.

  13. 重要的模式生物-大肠杆菌%Escherichia coli, an important model microorganism

    Institute of Scientific and Technical Information of China (English)

    王瀚

    2008-01-01

    大肠杆菌(Escherichia coli)是寄生于人或其他哺乳动物肠道内的细菌,属肠细菌科(Enterobacteriaceas),格兰氏阴性,为需氧或兼性厌氧菌,不形成芽孢或荚膜,在琼脂培养基上形成圆形、光滑、白色的菌落。由于它取材广泛,分裂增殖能力强、发育周期短以及结构简单等特点,已作为一种重要的模式生物在近现代生命科学研究尤其在分子遗传学及生物工程领域起着异常重要的作用。

  14. Mathematical modeling and numerical analysis of the growth of non-O157 Shiga toxin-producing Escherichia coli in spinach leaves.

    Science.gov (United States)

    Huang, Lihan

    2012-11-01

    This study was conducted to investigate the growth of non-O157 Shiga toxin-producing Escherichia coli (STEC) in spinach leaves and to develop kinetic models to describe the bacterial growth. Six serogroups of non-O157 STEC, including O26, O45, O103, O111, O121, and O145, were used in the growth studies conducted isothermally at 4, 8, 15, 20, 25, 30, and 35 °C. Both STEC and background microflora were enumerated to develop kinetic models. Growth of STEC in spinach leaves was observed at elevated temperatures (15-35 °C), but not at 4 and 8 °C. This study considered the dynamic interactions between the STEC cells and the background microflora. A modified Lotka-Volterra and logistic equation was used to simulate the bacterial growth. In combination with an unconstrained optimization procedure, the differential growth equations were solved numerically to evaluate the dynamic interactions between the STEC cells and the background microflora, and to determine the kinetic parameters by fitting each growth curve to the growth equations. A close agreement between the experimental growth curves and the numerical analysis results was obtained. The analytical results showed that the growth of STEC in spinach leaves was unhindered when the population was low, but the growth was suppressed by the background microflora as the STEC population approached the maximum population density. The effect of temperature on the growth of both STEC and background microflora was also evaluated. Secondary models, evaluating the effect of temperature on growth rates, were also developed. The estimated apparent minimum growth temperature for STEC was 11 °C in commercial spinach leaves. The methodology and results of this study can be used to examine the dynamic interactions and growth between different bacteria in foods, and to conduct risk assessments of STEC in spinach leaves. Published by Elsevier B.V.

  15. Real-Time Observation of Antimicrobial Polycation Effects on Escherichia coli: Adapting the Carpet Model for Membrane Disruption to Quaternary Copolyoxetanes.

    Science.gov (United States)

    Wang, Congzhou; Zolotarskaya, Olga Y; Nair, Sithara S; Ehrhardt, Christopher J; Ohman, Dennis E; Wynne, Kenneth J; Yadavalli, Vamsi K

    2016-03-29

    Real-time atomic force microscopy (AFM) was used for analyzing effects of the antimicrobial polycation copolyoxetane P[(C12)-(ME2Ox)-50/50], C12-50 on the membrane of a model bacterium, Escherichia coli (ATCC# 35218). AFM imaging showed cell membrane changes with increasing C12-50 concentration and time including nanopore formation and bulges associated with outer bacterial membrane disruption. A macroscale bactericidal concentration study for C12-50 showed a 4 log kill at 15 μg/mL with conditions paralleling imaging (1 h, 1x PBS, physiological pH, 25 °C). The dramatic changes from the control image to 1 h after introducing 15 μg/mL C12-50 are therefore reasonably attributed to cell death. At the highest concentration (60 μg/mL) further cell membrane disruption results in leakage of cytoplasm driven by detergent-like action. The sequence of processes for initial membrane disruption by the synthetic polycation C12-50 follows the carpet model posited for antimicrobial peptides (AMPs). However, the nanoscale details are distinctly different as C12-50 is a synthetic, water-soluble copolycation that is best modeled as a random coil. In a complementary AFM study, chemical force microscopy shows that incubating cells with C12-50 decreased the hydrophobicity across the entire cell surface at an early stage. This finding provides additional evidence indicating that C12-50 polycations initially bind with the cell membrane in a carpet-like fashion. Taken together, real time AFM imaging elucidates the mechanism of antimicrobial action for copolyoxetane C12-50 at the single cell level. In future work this approach will provide important insights into structure-property relationships and improved antimicrobial effectiveness for synthetic amphiphilic polycations.

  16. Adhesive threads of extraintestinal pathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Antão Esther-Maria

    2009-12-01

    Full Text Available Abstract The ability to adhere to host surfaces is by far the most vital step in the successful colonization by microbial pathogens. Colonization begins with the attachment of the bacterium to receptors expressed by cells forming the lining of the mucosa. Long hair like extracellular appendages called fimbriae, produced by most Gram-negative pathogens, mediate specific attachment to the epithelial cell surface. Associated with the fimbriae is a protein called an adhesin, which directs high-affinity binding to specific cell surface components. In the last couple of years, an enormous amount of research has been undertaken that deals with understanding how bacterial pathogens adhere to host cells. E. coli in all probability is one of the best studied free-living organisms. A group of E. coli called Extraintestinal pathogenic E. coli (ExPEC including both human and animal pathogens like Uropathogenic E. coli (UPEC, Newborn meningitic E. coli (NMEC and Avian pathogenic E. coli (APEC, have been found to harbour many fimbriae including Type 1 fimbriae, P fimbriae, curli fibres, S fimbriae, F1C fimbriae, Dr fimbriae, afimbrial adhesins, temperature-sensitive haemagglutinin and many novel adhesin gene clusters that have not yet been characterized. Each of these adhesins is unique due to the recognition of an adhesin-specific receptor, though as a group these adhesins share common genomic organization. A newly identified putative adhesin temporarily termed ExPEC Adhesin I, encoded by gene yqi, has been recently found to play a significant role in the pathogenesis of APEC infection, thus making it an interesting candidate for future research. The aim of this review is to describe the role of ExPEC adhesins during extraintestinal infections known till date, and to suggest the idea of investigating their potential role in the colonization of the host gut which is said to be a reservoir for ExPEC.

  17. 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...... 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...

  18. 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...... 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...

  19. Experiments on the bacterial nucleoid of Escherichia coli viewed as a physical entity

    NARCIS (Netherlands)

    Cunha, S.M.

    2004-01-01

    In this thesis we focus on the compaction of DNA within Escherichia coli and aim to gain some understanding of the physical mechanism behind its spatial organization in the cell. Chapter I is a brief review of the current knowledge of nucleoid structure. We discuss a model for DNA compaction in the

  20. Carrageenan Gum and Adherent Invasive Escherichia coli in a Piglet Model of Inflammatory Bowel Disease: Impact on Intestinal Mucosa-associated Microbiota

    Science.gov (United States)

    Munyaka, Peris M.; Sepehri, Shadi; Ghia, Jean-Eric; Khafipour, Ehsan

    2016-01-01

    Inflammatory bowel diseases (IBD) including Crohn's disease (CD), and ulcerative colitis (UC), are chronic conditions characterized by chronic intestinal inflammation. Adherent invasive Escherichia coli (AIEC) pathotype has been increasingly implicated in the etiopathogenesis of IBD. In a 21-day study, we investigated the effects of AIEC strain UM146 inoculation on microbiota profile of the ileal, cecal, ascending and descending colon in a pig model of experimental colitis. Carrageenan gum (CG) was used to induce colitis in weaner piglets whereas AIEC strain UM146 previously isolated from a CD patient was included to investigate a cause or consequence effect in IBD. Treatments were: (1) control; (2) CG; (3) AIEC strain UM146; and (4) CG+UM146. Pigs in groups 2 and 4 received 1% CG in drinking water from day 1 of the study while pigs in groups 3 and 4 were inoculated with UM146 on day 8. Following euthanization on day 21, tissue mucosal scrapings were collected and used for DNA extraction. The V4 region of bacterial 16S rRNA gene was then subjected to Illumina sequencing. Microbial diversity, composition, and the predicted functional metagenome were determined in addition to short chain fatty acids profiles in the digesta and inflammatory cytokines in the intestinal tissue. CG-induced colitis decreased bacterial species richness and shifted community composition. At the phylum level, an increase in Proteobacteria and Deferribacteres and a decrease in Firmicutes, Actinobacteria, and Bacteroidetes were observed in CG and CGUM146 compared to control and UM146. The metabolic capacity of the microbiome was also altered in CG and CGUM146 compared to UM146 and control in the colon. We demonstrated that CG resulted in bacterial dysbiosis and shifted community composition similar to what has been previously observed in IBD patients. However, AIEC strain UM146 alone did not cause any clear changes compared to CG or control in our experimental IBD pig model. PMID:27092122

  1. Carrageenan gum and adherent invasive Escherichia coli in a piglet model of inflammatory bowel disease: impact on intestinal mucosa-associated microbiota

    Directory of Open Access Journals (Sweden)

    Peris Mumbi Munyaka

    2016-04-01

    Full Text Available Inflammatory bowel diseases (IBD including Crohn’s disease (CD and ulcerative colitis (UC, are chronic conditions characterized by chronic intestinal inflammation. Adherent invasive Escherichia coli (AIEC pathotype has been increasingly implicated in the etiopathogenesis of IBD. In a 21-day study, we investigated the effects of AIEC strain UM146 colonization on the microbiota profile of the ileal, cecal, ascending and descending colon in a pig model of experimental colitis. Carrageenan gum (CG was used to induce colitis in weaner piglets whereas AIEC strain UM146 previously isolated from a CD patient was included to investigate a cause or consequence effect in IBD. Treatments were: 1 control; 2 CG; 3 AIEC strain UM146; and 4 CG+UM146. Pigs in groups 2 and 4 received 1% CG in drinking water from day 1 while pigs in groups 3 and 4 were inoculated with UM146 on day 8. Following euthanization on day 21, tissue mucosal scrapings were collected and used for DNA extraction. The V4 region of bacterial 16S rRNA gene was then subjected to Illumina sequencing. Microbial diversity, composition and the predicted functional genome were determined in addition to short chain fatty acids profiles in the digesta and inflammatory cytokines in the intestinal tissue. CG-induced colitis decreased bacterial species richness and shifted community composition. At the phylum level, an increase in Proteobacteria and Deferribacteres and a decrease in Firmicutes, Actinobacteria and Bacteroidetes were observed in CG and CGUM146 compared to control and UM146. The metabolic capacity of the microbiome was also altered in CG and CGUM146 compared to UM146 and control in the colon. We demonstrated that CG resulted in bacterial dysbiosis and shifted community composition similar to what has been previously observed in IBD patients. However, AIEC strain UM146 alone did not cause any clear changes compared to CG or control in our experimental IBD pig model.

  2. Modeling Stochastic Variability in the Numbers of Surviving Salmonella enterica, Enterohemorrhagic Escherichia coli, and Listeria monocytogenes Cells at the Single-Cell Level in a Desiccated Environment.

    Science.gov (United States)

    Koyama, Kento; Hokunan, Hidekazu; Hasegawa, Mayumi; Kawamura, Shuso; Koseki, Shigenobu

    2017-02-15

    Despite effective inactivation procedures, small numbers of bacterial cells may still remain in food samples. The risk that bacteria will survive these procedures has not been estimated precisely because deterministic models cannot be used to describe the uncertain behavior of bacterial populations. We used the Poisson distribution as a representative probability distribution to estimate the variability in bacterial numbers during the inactivation process. Strains of four serotypes of Salmonella enterica, three serotypes of enterohemorrhagic Escherichia coli, and one serotype of Listeria monocytogenes were evaluated for survival. We prepared bacterial cell numbers following a Poisson distribution (indicated by the parameter λ, which was equal to 2) and plated the cells in 96-well microplates, which were stored in a desiccated environment at 10% to 20% relative humidity and at 5, 15, and 25°C. The survival or death of the bacterial cells in each well was confirmed by adding tryptic soy broth as an enrichment culture. Changes in the Poisson distribution parameter during the inactivation process, which represent the variability in the numbers of surviving bacteria, were described by nonlinear regression with an exponential function based on a Weibull distribution. We also examined random changes in the number of surviving bacteria using a random number generator and computer simulations to determine whether the number of surviving bacteria followed a Poisson distribution during the bacterial death process by use of the Poisson process. For small initial cell numbers, more than 80% of the simulated distributions (λ = 2 or 10) followed a Poisson distribution. The results demonstrate that variability in the number of surviving bacteria can be described as a Poisson distribution by use of the model developed by use of the Poisson process.

  3. Evaluation of the Weibull and log normal distribution functions as survival models of Escherichia coli under isothermal and non isothermal conditions.

    Science.gov (United States)

    Aragao, Glaucia M F; Corradini, Maria G; Normand, Mark D; Peleg, Micha

    2007-11-01

    Published survival curves of Escherichia coli in two growth media, with and without the presence of salt, at various temperatures and in a Greek eggplant salad having various levels of essential oil, all had a characteristic downward concavity when plotted on semi logarithmic coordinates. Some also exhibited what appeared as a 'shoulder' of considerable length. Regardless of whether a shoulder was noticed, the survival pattern could be considered as a manifestation of an underlying unimodal distribution of the cells' death times. Mathematically, the data could be described equally well by the Weibull and log normal distribution functions, which had similar modes, means, standard deviations and coefficients of skewness. When plotted in their probability density function (PDF) form, the curves also appeared very similar visually. This enabled us to quantify and compare the effect of temperature or essential oil concentration on the organism's survival in terms of these temporal distributions' characteristics. Increased lethality was generally expressed in a shorter mean and mode, a smaller standard deviation and increased overall symmetry as judged by the distributions' degree of skewness. The 'shoulder', as expected, simply indicated that the distribution's standard deviation was much smaller than its mode. Rate models based on the two distribution functions could be used to predict non isothermal survival patterns. They were derived on the assumption that the momentary inactivation rate is the isothermal rate at the momentary temperature at a time that corresponds to the momentary survival ratio. In this application, however, the Weibullian model with a fixed power was not only simpler and more convenient mathematically than the one based on the log normal distribution, but it also provided more accurate estimates of the dynamic inactivation patterns.

  4. Infectious endocarditis caused by Escherichia coli

    DEFF Research Database (Denmark)

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

    2011-01-01

    -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...

  5. Escherichia coli O157:H7动态生长反响应面方程的扩展%Response surface models for the growth of escherichia coli O157:H7

    Institute of Scientific and Technical Information of China (English)

    李柏林; 郭剑飞; 欧杰

    2006-01-01

    以反应响应面方程分析Escherichia coli动态生长数据,并建立数学模型描述培养温度、初始pH值以及NaCl浓度对大肠杆菌的需氧、厌氧生长的影响.主要探讨通过响应面方程找出环境因素(培养温度、初始pH值以及NaCl浓度)与Escherichia coli生长参数LPD和GT之间的关系,并建立数学模型.

  6. 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. PMID:26809117

  7. 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.

  8. Contribution of siderophore systems to growth and urinary tract colonization of asymptomatic bacteriuria Escherichia coli

    DEFF Research Database (Denmark)

    Watts, Rebecca E; Totsika, Makrina; Challinor, Victoria L

    2012-01-01

    The molecular mechanisms that define asymptomatic bacteriuria (ABU) Escherichia coli colonization of the human urinary tract remain to be properly elucidated. Here, we utilize ABU E. coli strain 83972 as a model to dissect the contribution of siderophores to iron acquisition, growth, fitness......, and colonization of the urinary tract. We show that E. coli 83972 produces enterobactin, salmochelin, aerobactin, and yersiniabactin and examine the role of these systems using mutants defective in siderophore biosynthesis and uptake. Enterobactin and aerobactin contributed most to total siderophore activity...

  9. 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.

  10. Alterations induced in Escherichia Coli cells by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kappke, J.; Schelin, H.R.; Paschuk, S.A.; Denyak, V.; Silva, E.R. da [Federal University of Technology of Parana (CPGEI/UTFPR), Curitiba, PR (Brazil)]. E-mails: jaquekap@yahoo.com.br; schelin@cpgei.cefetpr.br; sergei@utfpr.edu.br; Jesus, E.F.O. de; Lopes, R.T. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Instrumentacao Nuclear]. E-mails: ricardo@lin.ufrj.br; edgar@lin.ufrj.br; Carlin, N.; Toledo, E.S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica]. E-mail: nelson.carlin@dfn.if.usp.br

    2007-07-01

    Modifications occurred in Escherichia coli cells exposed to gamma radiation ({sup 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)

  11. Is Escherichia coli urinary tract infection a zoonosis?

    DEFF Research Database (Denmark)

    Jacobsen, L.; Garneau, P.; Bruant, G.

    2012-01-01

    and kidney cultures. Further, isolates with the same gene profile also yielded similar bacterial counts in urine, bladder and kidneys. This study showed a clonal link between E. coli from meat and humans, providing solid evidence that UTI is zoonosis. The close relationship between community-dwelling human......Recently, it has been suggested that the Escherichia coli causing urinary tract infection (UTI) may come from meat and animals. The purpose was to investigate if a clonal link existed between E. coli from animals, meat and UTI patients. Twenty-two geographically and temporally matched B2 E. coli...... from UTI patients, community-dwelling humans, broiler chicken meat, pork, and broiler chicken, previously identified to exhibit eight virulence genotypes by microarraydetection of approximately 300 genes, were investigated for clonal relatedness by PFGE. Nine isolates were selected and tested...

  12. Occurrence of pathogenic and faecal Escherichia coli in layer hens

    Directory of Open Access Journals (Sweden)

    Silvia Tagliabue

    2010-01-01

    Full Text Available A total of 117 Escherichia coli from colibacillosis affected (APEC and clinically healthy birds (AFEC were serotyped and tested for the presence of virulence genes: iss, tsh, cva. A total of 54.5% E. Coli were typeable and 15 different serogroups were identified. The most common serogroups among APEC strains were O78, O2 and O128, whereas O139 was predominant in faecal strains from healthy birds. Iss, tsh e cva were more frequently detected among the septicaemic E. coli strains. The association of virulence genes was observed. Particularly, the pathotype iss-tsh-cva was present in 46.5% of APEC strains. Referring to serogroups, E. coli O78 and O2 originating from colibacillosis affected birds were always isstsh- cva positive but did not share virulence genes when they came from healthy birds.

  13. Escherichia coli control in a surface flow treatment wetland.

    Science.gov (United States)

    MacIntyre, M E; Warner, B G; Slawson, R M

    2006-06-01

    A field experiment showed that numbers of Escherichia coli declined significantly when floating Lemna spp. plants were removed to create open water areas in a typical newly constructed surface flow treatment wetland in southern Ontario. It is suggested that E. coli declined immediately after Lemna removal because the Lemna was shading the water column from penetration by natural UV radiation, it was providing favourable attachment sites for the E. coli, and it was not allowing effective free exchange of oxygen from surface winds to the water column to maintain high enough dissolved oxygen supplies for predator zooplankton populations. Operators of wetland systems must have the specialized skills required to recognize the cause and the appropriate maintenance requirements to maintain efficient operation of such unconventional systems should E. coli numbers increase during the course of operation.

  14. Engineered synthetic pathway for isopropanol production in Escherichia coli.

    Science.gov (United States)

    Hanai, T; Atsumi, S; Liao, J C

    2007-12-01

    A synthetic pathway was engineered in Escherichia coli to produce isopropanol by expressing various combinations of genes from Clostridium acetobutylicum ATCC 824, E. coli K-12 MG1655, Clostridium beijerinckii NRRL B593, and Thermoanaerobacter brockii HTD4. The strain with the combination of C. acetobutylicum thl (acetyl-coenzyme A [CoA] acetyltransferase), E. coli atoAD (acetoacetyl-CoA transferase), C. acetobutylicum adc (acetoacetate decarboxylase), and C. beijerinckii adh (secondary alcohol dehydrogenase) achieved the highest titer. This strain produced 81.6 mM isopropanol in shake flasks with a yield of 43.5% (mol/mol) in the production phase. To our knowledge, this work is the first to produce isopropanol in E. coli, and the titer exceeded that from the native producers.

  15. Biosynthesis of Two Flavones, Apigenin and Genkwanin, in Escherichia coli.

    Science.gov (United States)

    Lee, Hyejin; Kim, Bong Gyu; Kim, Mihyang; Ahn, Joong-Hoon

    2015-09-01

    The flavonoid apigenin and its O-methyl derivative, genkwanin, have various biological activities and can be sourced from some vegetables and fruits. Microorganisms are an alternative for the synthesis of flavonoids. Here, to synthesize genkwanin from tyrosine, we first synthesized apigenin from p-coumaric acid using four genes (4CL, CHS, CHI, and FNS) in Escherichia coli. After optimization of different combinations of constructs, the yield of apigenin was increased from 13 mg/l to 30 mg/l. By introducing two additional genes (TAL and POMT7) into an apigenin-producing E. coli strain, we were able to synthesize 7-O-methyl apigenin (genkwanin) from tyrosine. In addition, the tyrosine content in E. coli was modulated by overexpressing aroG and tyrA. The engineered E. coli strain synthesized approximately 41 mg/l genkwanin.

  16. Yeast DNA sequences initiating gene expression in Escherichia coli.

    Science.gov (United States)

    Lewin, Astrid; Tran, Thi Tuyen; Jacob, Daniela; Mayer, Martin; Freytag, Barbara; Appel, Bernd

    2004-01-01

    DNA transfer between pro- and eukaryotes occurs either during natural horizontal gene transfer or as a result of the employment of gene technology. We analysed the capacity of DNA sequences from a eukaryotic donor organism (Saccharomyces cerevisiae) to serve as promoter region in a prokaryotic recipient (Escherichia coli) by creating fusions between promoterless luxAB genes from Vibrio harveyi and random DNA sequences from S. cerevisiae and measuring the luminescence of transformed E. coli. Fifty-four out of 100 randomly analysed S. cerevisiae DNA sequences caused considerable gene expression in E. coli. Determination of transcription start sites within six selected yeast sequences in E. coli confirmed the existence of bacterial -10 and -35 consensus sequences at appropriate distances upstream from transcription initiation sites. Our results demonstrate that the probability of transcription of transferred eukaryotic DNA in bacteria is extremely high and does not require the insertion of the transferred DNA behind a promoter of the recipient genome.

  17. Food-borne origins of Escherichia coli causing extraintestinal infections.

    Science.gov (United States)

    Manges, Amee R; Johnson, James R

    2012-09-01

    Most human extraintestinal Escherichia coli infections, including those involving antimicrobial resistant strains, are caused by the members of a limited number of distinctive E. coli lineages, termed extraintestinal pathogenic E. coli (ExPEC), that have a special ability to cause disease at extraintestinal sites when they exit their usual reservoir in the host's intestinal tract. Multiple lines of evidence suggest that many of the ExPEC strains encountered in humans with urinary tract infection, sepsis, and other extraintestinal infections, especially the most extensively antimicrobial-resistant strains, may have a food animal source, and may be transmitted to humans via the food supply. This review summarizes the evidence that food-borne organisms are a significant cause of extraintestinal E. coli infections in humans.

  18. Effect of Genetic Database Comprehensiveness on Fractional Proteomics of Escherichia coli O157:H7

    Science.gov (United States)

    2014-01-01

    EFFECT OF GENETIC DATABASE COMPREHENSIVENESS ON FRACTIONAL PROTEOMICS OF ESCHERICHIA COLI O157:H7 ECBC-TR-1154...Database Comprehensiveness on Fractional Proteomics of Escherichia coli O157:H7 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...are characterizing the extracellular, fimbriae, and whole cell proteins produced by the pathogenic Gram-negative bacterium Escherichia coli (E. coli

  19. A standardised challenge model with an enterotoxigenic F4+ Escherichia coli strain in piglets assessing clinical traits and faecal shedding of fae and est-II toxin genes.

    Science.gov (United States)

    Spitzer, Franz; Vahjen, Wilfried; Pieper, Robert; Martinez-Vallespin, Beatriz; Zentek, Jürgen

    2014-12-01

    This study evaluated the effect of five feed additives on post weaning diarrhoea (PWD) in piglets challenged 3 d after weaning with an enterotoxigenic Escherichia coli strain (ETEC). In three experimental runs, a total of 84 piglets was weaned at 21 days of age and randomly assigned to seven treatments. As dietary treatment, piglets were fed a basal diet or diets with addition of bovine colostrum (0.2%), pineapple stem extract containing bromelain (0.2%), an autolysed yeast preparation (Saccharomyces cerevisiae) (0.1%), a combination of organic acids (0.7%) and a phytogenic product with thyme essential oil (0.015%). A porcine ETEC, serotype O149:K91:K88ac was given twice via oral infection on day 3 after weaning at 10(10) colony forming units/animal. One group of piglets was fed the basal diet without ETEC challenge. Traits included clinical sores, body temperature, faecal scoring and determination of faecal dry matter and the shedding of fae and est-II ETEC toxin genes. After weaning, non-challenged control piglets did not show signs of diarrhoea or impaired health, while the majority of infected piglets had a drop in body temperature, signs of diarrhoea and impaired general health. Mortality, the decrease of faecal dry matter and shedding of the toxin genes fae and est-II were not affected by the different additives. In conclusion, the ETEC challenge model induced distinct clinical signs of PWD in piglets, but the tested feed additives had no preventive effect under these conditions.

  20. Viabilidad de Escherichia coli en presencia De diferentes contaminantes

    OpenAIRE

    Antonio Rivera T,; Edith Chávez B.; Gisela Rendón A.; Silvia Giono C

    2006-01-01

    La contaminación en ríos condiciona la presencia de microorganismos adaptados al ecosistema entre ellos a pató-genos de importancia en salud pública. Objetivo: Determinar la viabilidad de Escherichia coli en presencia de nitrato de plata, carbonato de amonio, fenol y formaldehído. Materiales y métodos: Se tomaron muestras de agua del río Alseseca, que luego se sembró en medios de cultivo selectivos para enterobacterias, seleccionándose las colonias del género Escherichia, las cuales fueron se...

  1. Escherichia coli and the French School of Molecular Biology.

    Science.gov (United States)

    Ullmann, Agnes

    2010-09-01

    André Lwoff, Jacques Monod, and François Jacob, the leaders of the French school of molecular biology, greatly contributed between 1937 and 1965 to its development and triumph. The main discovery of Lwoff was the elucidation of the mechanism of bacteriophage induction, the phenomenon of lysogeny, that led to the model of genetic regulation uncovered later by Jacob and Monod. Working on bacterial growth, Monod discovered in 1941 the phenomenon of diauxy and uncovered the nature of enzyme induction. By combining genetic and biochemical approaches, Monod brought to light the structure and functions of the Escherichia coli lactose system, comprising the genes necessary for lactose metabolism, i.e., β-galactosidase and lactose permease, a pump responsible for accumulation of galactosides into the cells. An additional genetic factor (the i gene) determines the inducibility and constitutivity of enzyme synthesis. Around the same time, François Jacob and Elie Wollman dissected the main events of bacterial conjugation that enabled them to construct a map of the E. coli chromosome and to demonstrate its circularity. The genetic analysis of the lactose system led Monod and Jacob to elucidate the mechanism of the regulation of gene expression and to propose the operon model: a unit of coordinate transcription. One of the new concepts that emerged from the operon model was messenger RNA. In 1963, Monod developed one of the most elegant concepts of molecular biology, the theory of allostery. In 1965, Lwoff, Monod and Jacob were awarded the Nobel Prize in Physiology or Medicine.

  2. Nearshore hydrodynamics as loading and forcing factors for Escherichia coli contamination at an embayed beach

    Science.gov (United States)

    Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.; Byappanahalli, Muruleedhara N.

    2012-01-01

    Numerical simulations of the transport and fate of Escherichia coli were conducted at Chicago's 63rd Street Beach, an embayed beach that had the highest mean E. coli concentration among 23 similar Lake Michigan beaches during summer months of 2000-2005, in order to find the cause for the high bacterial contamination. The numerical model was based on the transport of E. coli by current circulation patterns in the embayment driven by longshore main currents and the loss of E. coli in the water column, taking settling as well as bacterial dark- and solar-related decay into account. Two E. coli loading scenarios were considered: one from the open boundary north of the embayment and the other from the shallow water near the beachfront. Simulations showed that the embayed beach behaves as a sink for E. coli in that it generally receives E. coli more efficiently than it releases them. This is a result of the significantly different hydrodynamic forcing factors between the inside of the embayment and the main coastal flow outside. The settled E. coli inside the embayment can be a potential source of contamination during subsequent sediment resuspension events, suggesting that deposition-resuspension cycles of E. coli have resulted in excessive bacterial contamination of beach water. A further hypothetical case with a breakwater shortened to half its original length, which was anticipated to enhance the current circulation in the embayment, showed a reduction in E. coli concentrations of nearly 20%.

  3. Circular dimers of lambda DNA in infected, nonlysogenic Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Freifelder, D.; Baran, N.; Folkmanis, A.; Freifelder, D.L.R.

    1977-09-01

    Covalently closed circular dimerss of phage lambda DNA have been found in Escherichia coli infected with lambda. These dimers can be formed by either the lambda Red or Int systems, by a nonrecombinational replicative mechanism requiring the activity of the lambda O and P genes or by joining of the cohesive ends. Dimers mediated by the E. coli Rec system have not been observed. Those formed by the Int system often result from recombination between different DNA molecules; however, the Red-mediated dimer may be a result of replicative extension of a single DNA molecule. Trimers have also been observed but studied only briefly.

  4. Enteropathogenic Escherichia coli Serotypes and Endemic Diarrhea in Infants

    OpenAIRE

    M. Regina F. Toledo; Alvariza, M. do Carmo B.; Murahovschi, Jayme; Sonia R.T.S. RAMOS; Trabulsi, Luiz R.

    1983-01-01

    Enteropathogenic Escherichia coli serotypes were searched for in feces of 550 children with endemic diarrhea and in 129 controls, in São Paulo, in 1978 and 1979; serotypes O111ab:H−, O111ab:H2, and O119:H6 were significantly associated with diarrhea in children 0 to 5 months old and were the most frequent agents of diarrhea in this age group as compared with enterotoxigenic and enteroinvasive E. coli, Salmonella sp., Shigella sp., and Yersinia enterocolitica. It is concluded that various ente...

  5. Sedimentation and gravitational instability of Escherichia coli Suspension

    Science.gov (United States)

    Douarche, Carine; Salin, Dominique; Collaboration between Laboratory FAST; LPS Collaboration

    2016-11-01

    The successive run and tumble of Escherichia coli bacteria provides an active matter suspension of rod-like particles with a large swimming diffusion. As opposed to inactive elongated particles, this diffusion prevents clustering and instability in the gravity field. We measure the time dependent E . coli concentration profile during their sedimentation. After some hours, due to the dioxygen consumption, a motile / non-motile front forms leading to a Rayleigh-Taylor type gravitational instability. Analyzing both sedimentation and instability in the framework of active particle suspensions, we can measure the relevant bacteria hydrodynamic characteristics such as its single particle sedimentation velocity and its hindrance volume.

  6. [Drug resistance of Escherichia coli strains isolated from poultry].

    Science.gov (United States)

    Giurov, B; Korudzhiĭski, N; Bineva, I

    1981-01-01

    Studied was the sensitivity of a total of 143 strains of Escherichia coli, isolated from young birds and broilers died from coli septicaemia, to antibiotics and chemotherapeutics. The following descending order was established: gentamycin, carbenicillin, ampicillin, furazolidon, borgal, kanamycin, strep tomycin, chloramphenicol, neomycin sulphathiazole, and tetracycline. Markers of resistance were established with all strains with regard to the therapeutic agents in current and prospective use in industrial poultry farming. It is stated that a preliminary antibiogram is indispensable in order to obtain dependable results in the treatment of animals affected with colibacteriosis. An alternative is to apply directly those drugs to which the strains have shown highest sensitivity.

  7. Inducible repair of oxidative DNA damage in Escherichia coli.

    Science.gov (United States)

    Demple, B; Halbrook, J

    Hydrogen peroxide is lethal to many cell types, including the bacterium Escherichia coli. Peroxides yield transient radical species that can damage DNA and cause mutations. Such partially reduced oxygen species are occasionally released during cellular respiration and are generated by lethal and mutagenic ionizing radiation. Because cells live in an environment where the threat of oxidative DNA damage is continual, cellular mechanisms may have evolved to avoid and repair this damage. Enzymes are known which evidently perform these functions. We report here that resistance to hydrogen peroxide toxicity can be induced in E. coli, that this novel induction is specific and occurs, in part, at the level of DNA repair.

  8. Suppression of Escherichia coli O157:H7 by Dung Beetles (Coleoptera: Scarabaeidae using the lowbush blueberry agroecosystem as a model system.

    Directory of Open Access Journals (Sweden)

    Matthew S Jones

    Full Text Available Wildlife as a source of microbial contamination is a food safety concern. Deer feces (scat have been determined as a point source for Escherichia coli O157:H7 contamination of fresh produce. The ecological role of the scooped scarab (Onthophagus hecate (Panzer, a generalist dung beetle species common in Maine blueberry fields, was explored as a biological control agent and alternatively as a pathogen vector between deer scat and food. A large-scale field survey of wildlife scat indicated that pathogenic E. coli O157:H7 was present, albeit at a low prevalence (1.9% of samples, n = 318, in the Maine lowbush blueberry agroecosystem. A manipulative field experiment verified that, should contact occur between deer scat and blueberry plants and fruit during the summer, contamination with E. coli O157:H7 can occur and persist for more than 72 h. For both the positive control and an experimental scat inoculation treatment, the levels of the bacterial population decreased over time, but at different rates (treatment x time interaction: F (1.9,18.8 = 358.486, P < 0.0001. The positive control inoculation, which resulted in a higher initial E. coli level on fruit, decayed at a faster rate than inoculation of fruit via scat in the experimental treatment. We conducted 2 laboratory studies to elucidate aspects of dung beetle feeding ecology as it relates to suppression of E. coli O157:H7 from deer scat to lowbush blueberry fruit. In both experiments, dung beetles buried the same amount of scat whether or not the scat was inoculated with the pathogen (F(1,6 = 0.001; P = 0.999 and (F (2,17 = 4.10, P = 0.147. Beetles feeding on E. coli inoculated deer scat were not found to vector the pathogen to fruit. In two studies, beetles lowered the amount of pathogenic E. coli persisting in soils compared to soils without beetles (F (2,9 = 7.757; P = 0.05 and F (2,17 = 8.0621, P = 0.004. Our study suggests that the dung beetle species, Onthophagus hecate, has the potential

  9. Hybrid dynamic modeling of Escherichia coli central metabolic network combining Michaelis–Menten and approximate kinetic equations

    DEFF Research Database (Denmark)

    Costa, Rafael S.; Machado, Daniel; Rocha, Isabel

    2010-01-01

    , represent nowadays the limiting factor in the construction of such models. In this study, we compare four alternative modeling approaches based on Michaelis–Menten kinetics for the bi-molecular reactions and different types of simplified rate equations for the remaining reactions (generalized mass action...... using the hybrid model composed of Michaelis–Menten and the approximate lin-log kinetics indicate that this is a possible suitable approach to model complex large-scale networks where the exact rate laws are unknown....

  10. ESCHERICHIA COLI: AN IMPORTANT PATHOGEN IN PATIENTS WITH HEMATOLOGIC MALIGNANCIES

    Directory of Open Access Journals (Sweden)

    Daniel Olson

    2014-08-01

    Full Text Available Abstract Background Escherichia coli (E. coli is a pathogen of great concern in immunosuppressed patients.  While antimicrobial prophylactic therapy has become the standard, the emergence of resistant pathogens has some questioning its use.  This study describes our experience with E.coli as a pathogen in neutropenic patients with a hematologic malignancy, and addresses future directions of treatment for this patient population. Methods A retrospective chart review of 245 E.coli bacteremia patients at Moffitt Cancer Center from 05/18/02 – 05/15/12 was conducted. Patients were identified via microbiology laboratory computerized records. Results The included patients experienced clinically significant E.coli bacteremia resulting in a median hospital stay of 14.7 days.  Several patients developed severe sepsis requiring the use of pressor and ventilator therapy. Conclusions E.coli is a major pathogen in these patient populations resulting in extended hospital stays and specialized treatment to overcome their E.coli bacteremia. The data supports the use of fluoroquinolone prophylactic therapy, however, earlier detection and treatment of neutropenic infection is needed.

  11. Gentamicin resistance among Escherichia coli strains isolated in neonatal sepsis.

    Science.gov (United States)

    Hasvold, J; Bradford, L; Nelson, C; Harrison, C; Attar, M; Stillwell, T

    2013-01-01

    Neonatal sepsis is a significant cause of morbidity and mortality among term and preterm infants. Ampicillin and gentamicin are standard empiric therapy for early onset sepsis. Four cases of neonatal sepsis secondary to Escherichia coli (E. coli) found to be gentamicin resistant occurred within a five week period in one neonatal intensive care unit (NICU). To determine whether these cases could be tied to a single vector of transmission, and to more broadly evaluate the incidence of gentamicin resistant strains of E. coli in the neonatal population at our institution compared to other centers, we reviewed the charts of the four neonates (Infants A through D) and their mothers. The E. coli isolates were sent for Pulse Field Gel Electrophoresis (PFGE) to evaluate for genetic similarity between strains. We also reviewed all positive E. coli cultures from one NICU over a two year period. Infants A and B had genetically indistinguishable strains which matched that of urine and placental cultures of Infant B's mother. Infant C had a genetically distinct organism. Infant D, the identical twin of Infant C, did not have typing performed. Review of all cultures positive for E. coli at our institution showed a 12.9 percent incidence of gentamicin-resistance. A review of other studies showed that rates of resistance vary considerably by institution. We conclude that gentamicin-resistant E. coli is a relatively uncommon cause of neonatal sepsis, but should remain a consideration in patients who deteriorate despite initiation of empiric antibiotics.

  12. Modeling Stochastic Variability in the Numbers of Surviving Salmonella enterica, Enterohemorrhagic Escherichia coli, and Listeria monocytogenes Cells at the Single-Cell Level in a Desiccated Environment

    Science.gov (United States)

    Koyama, Kento; Hokunan, Hidekazu; Hasegawa, Mayumi; Kawamura, Shuso

    2016-01-01

    ABSTRACT Despite effective inactivation procedures, small numbers of bacterial cells may still remain in food samples. The risk that bacteria will survive these procedures has not been estimated precisely because deterministic models cannot be used to describe the uncertain behavior of bacterial populations. We used the Poisson distribution as a representative probability distribution to estimate the variability in bacterial numbers during the inactivation process. Strains of four serotypes of Salmonella enterica, three serotypes of enterohemorrhagic Escherichia coli, and one serotype of Listeria monocytogenes were evaluated for survival. We prepared bacterial cell numbers following a Poisson distribution (indicated by the parameter λ, which was equal to 2) and plated the cells in 96-well microplates, which were stored in a desiccated environment at 10% to 20% relative humidity and at 5, 15, and 25°C. The survival or death of the bacterial cells in each well was confirmed by adding tryptic soy broth as an enrichment culture. Changes in the Poisson distribution parameter during the inactivation process, which represent the variability in the numbers of surviving bacteria, were described by nonlinear regression with an exponential function based on a Weibull distribution. We also examined random changes in the number of surviving bacteria using a random number generator and computer simulations to determine whether the number of surviving bacteria followed a Poisson distribution during the bacterial death process by use of the Poisson process. For small initial cell numbers, more than 80% of the simulated distributions (λ = 2 or 10) followed a Poisson distribution. The results demonstrate that variability in the number of surviving bacteria can be described as a Poisson distribution by use of the model developed by use of the Poisson process. IMPORTANCE We developed a model to enable the quantitative assessment of bacterial survivors of inactivation procedures

  13. EFFECT OF VISIBLE RANGE ELECTROMAGNETIC RADIATIONS ON ESCHERICHIA COLI.

    Science.gov (United States)

    Azeemi, Samina T Yousuf; Shaukat, Saleem Farooq; Azeemi, Khawaja Shamsuddin; Khan, Idrees; Mahmood, Khalid; Naz, Farah

    2017-01-01

    Escherichia coli is the agent responsible for a range of clinical diseases. With emerging antimicrobial resistance, other treatment options including solar/photo-therapy are becoming increasingly common. Visible Range Radiation Therapy/Colour Therapy is an emerging technique in the field of energy/vibrational medicine that uses visible spectrum of Electromagnetic Radiations to cure different diseases. In this study, our goal was to understand the effect of Visible Range Electromagnetic Radiations on E. coli (in vitro) and therefore find out the most appropriate visible range radiation for the treatment of diseases caused by E. coli. A total of 6 non-repetitive E. coli isolates were obtained from urine samples obtained from hospitalized patients with UTI. Single colony of E. coli was inoculated in 3 ml of Lysogeny Broth (LB) and 40 μl of this E. coli suspension was poured into each of the plastic tubes which were then irradiated with six different wavelengths in the visible region (Table. 1) after 18 hours with one acting as a control. The Optical Densities of these irradiated samples were then measured. Furthermore, scanning electron microscopy (TEFCAN ZEGA3) was carried out. The analysis of the microscopic and SEM images of irradiated E. coli samples with six different visible range radiations is representative of The fact that E. coli responded differently to every applied radiation in the visible region and the most profound inhibitory effects were that of 538nm Visible Range Radiation (Green) which proved to be bactericidal and 590nm Visible Range Radiation (yellow) which was bacteriostatic. The enhanced growth of E. coli with varying degrees was clearly observed in 610nm (orange), 644nm (red), 464nm (Purple) and 453nm (blue). It can be concluded that 538nm (Green) and 590nm (Yellow) can effectively be used for treating E. coli borne diseases.

  14. Dose-related selection of fluoroquinolone-resistant Escherichia coli.

    Science.gov (United States)

    Olofsson, Sara K; Marcusson, Linda L; Strömbäck, Ann; Hughes, Diarmaid; Cars, Otto

    2007-10-01

    To investigate the effects of clinically used doses of norfloxacin, ciprofloxacin and moxifloxacin on survival and selection in Escherichia coli populations containing fluoroquinolone-resistant subpopulations and to measure the value of the pharmacodynamic index AUC/mutant prevention concentration (MPC) that prevents the growth of pre-existing resistant mutants. Mixed cultures of susceptible wild-type and isogenic single (gyrA S83L) or double (gyrA S83L, Delta marR) fluoroquinolone-resistant mutants were exposed to fluoroquinolones for 24 h in an in vitro kinetic model. Antibiotic concentrations modelled pharmacokinetics attained with clinical doses. All tested doses eradicated the susceptible wild-type strain. Norfloxacin 200 mg administered twice daily selected for both single and double mutants. Ciprofloxacin 250 mg administered twice daily eradicated the single mutant, but not the double mutant. For that, 750 mg administered twice daily was required. Moxifloxacin 400 mg once daily eliminated the single mutant, but did not completely remove the double mutant. The MPC of ciprofloxacin was determined and based on those dose simulations that eradicated mutant subpopulations, an AUC/MPC(wild-type) of 35 prevented selection of the single mutant, whereas an AUC/MPC(single mutant) of 14 (equivalent to an AUC/MPC(wild-type) of 105) prevented selection of the double mutant. All tested clinical dosing regimens were effective in eradicating susceptible bacteria, but ciprofloxacin 750 mg twice daily was the only dose that prevented the selection of single- and double-resistant E. coli mutants. Thus, among approved fluoroquinolone dosing regimens, some are significantly more effective than others in exceeding the mutant selection window and preventing the enrichment of resistant mutants.

  15. 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 a...

  16. Comparison of 61 Sequenced Escherichia coli Genomes

    DEFF Research Database (Denmark)

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

    2010-01-01

    MLST was performed, many of the various strains appear jumbled and less well resolved. The predicted pan-genome comprises 15,741 gene families, and only 993 (6%) of the families are represented in every genome, comprising the core genome. The variable or 'accessory' genes thus make up more than 90......% of the pan-genome and about 80% of a typical genome; some of these variable genes tend to be co-localized on genomic islands. The diversity within the species E. coli, and the overlap in gene content between this and related species, suggests a continuum rather than sharp species borders in this group...

  17. Tranformasi Fragmen Dna Kromosom Xanthomonas Campestris ke dalam Escherichia Coli

    Directory of Open Access Journals (Sweden)

    Wibowo Mangunwardoyo

    2002-04-01

    Full Text Available Research on DNA transformation of Xanthomonas campestris into Escherichia coli DH5αα using plasmid vector Escherichia coli (pUC19. was carried out. DNA chromosome was isolated using CTAB method, alkali lysis method was used to isolate DNA plasmid. Both of DNA plasmid and chromosome were digested using restriction enzyme EcoRI. Competent cell was prepared with CaCl2 and heat shock method for transformation procedure. The result revealed transformation obtain 5 white colonies, with transformation frequency was 1,22 x 10-8 colony/competent cell. Electrophoresis analysis showed the DNA fragment (insert in range 0.5 – 7,5 kb. Further research should be carried out to prepare the genomic library to obtain better result of transformant.

  18. Mechanobiology of Antimicrobial Resistant Escherichia coli and Listeria innocua.

    Science.gov (United States)

    Tajkarimi, Mehrdad; Harrison, Scott H; Hung, Albert M; Graves, Joseph L

    2016-01-01

    A majority of antibiotic-resistant bacterial infections in the United States are associated with biofilms. Nanoscale biophysical measures are increasingly revealing that adhesive and viscoelastic properties of bacteria play essential roles across multiple stages of biofilm development. Atomic Force Microscopy (AFM) applied to strains with variation in antimicrobial resistance enables new opportunities for investigating the function of adhesive forces (stickiness) in biofilm formation. AFM force spectroscopy analysis of a field strain of Listeria innocua and the strain Escherichia coli K-12 MG1655 revealed differing adhesive forces between antimicrobial resistant and nonresistant strains. Significant increases in stickiness were found at the nanonewton level for strains of Listeria innocua and Escherichia coli in association with benzalkonium chloride and silver nanoparticle resistance respectively. This advancement in the usage of AFM provides for a fast and reliable avenue for analyzing antimicrobial resistant cells and the molecular dynamics of biofilm formation as a protective mechanism.

  19. Specific mistranslation in hisT mutants of Escherichia coli.

    Science.gov (United States)

    Parker, J

    1982-01-01

    Certain strains of Escherichia coli mistranslate at very high frequencies when starved for asparagine or histidine. This mistranslation is the result of misreading events on the ribosome. The introduction of a hisT mutation into such a strain decreases the frequency of mistranslation during histidine starvation but not during asparagine starvation. The most likely explanation is that the replacement of the pseudouridine residue in the anticodon loop of glutamine specific transfer ribonucleic acid by uridine in hisT mutants leads to an increase in fidelity of transfer ribonucleic acid function. The hisT gene in Escherichia coli has also been more accurately mapped, giving the gene order purF-hisT-aroC-fadL-dsdA.

  20. A new model for the three-dimensional folding of Escherichia coli 16 S ribosomal RNA. II. The RNA-protein interaction data.

    Science.gov (United States)

    Mueller, F; Brimacombe, R

    1997-08-29

    The map of the mass centres of the 21 proteins from the Escherichia coli 30 S ribosomal subunit, as determined by neutron scattering, was fitted to a cryoelectron microscopic (cryo-EM) model at a resolution of 20 A of 70 S ribosomes in the pre-translocational state, carrying tRNA molecules at the A and P sites. The fit to the 30 S moiety of the 70 S particles was accomplished with the help of the well-known distribution of the ribosomal proteins in the head, body and side lobe regions of the 30 S subunit, as determined by immuno electron microscopy (IEM). Most of the protein mass centres were found to lie close to the surface (or even outside) of the cryo-EM contour of the 30 S subunit, supporting the idea that the ribosomal proteins are arranged peripherally around the rRNA. The ribosomal protein distribution was then compared with the corresponding model for the 16 S rRNA, fitted to the same EM contour (described in an accompanying paper), in order to analyse the mutual compatibility of the arrangement of proteins and rRNA in terms of the available RNA-protein interaction data. The information taken into account included the hydroxyl radical and base foot-printing data from Noller's laboratory, and our own in situ cross-linking results. Proteins S1 and S14 were not considered, due to the lack of RNA-protein data. Among the 19 proteins analysed, 12 (namely S2, S4, S5, S7, S8, S9, S10, S11, S12, S15, S17 and S21) showed a fit to the rRNA model that varied from being excellent to at least acceptable. Of the remaining 7, S3 and S13 showed a rather poor fit, as did S18 (which is considered in combination with S6 in the foot-printing experiments). S16 was difficult to evaluate, as the foot-print data for this protein cover a large area of the rRNA. S19 and S20 showed a bad fit in terms of the neutron map, but their foot-print and cross-link sites were clustered into compact groups in the rRNA model in those regions of the 30 S subunit where these proteins have

  1. Shear alters motility of Escherichia coli

    Science.gov (United States)

    Molaei, Mehdi; Jalali, Maryam; Sheng, Jian

    2013-11-01

    Understanding of locomotion of microorganisms in shear flows drew a wide range of interests in microbial related topics such as biological process including pathogenic infection and biophysical interactions like biofilm formation on engineering surfaces. We employed microfluidics and digital holography microscopy to study motility of E. coli in shear flows. We controlled the shear flow in three different shear rates: 0.28 s-1, 2.8 s-1, and 28 s-1 in a straight channel with the depth of 200 μm. Magnified holograms, recorded at 15 fps with a CCD camera over more than 20 minutes, are analyzed to obtain 3D swimming trajectories and subsequently used to extract shear responses of E.coli. Thousands of 3-D bacterial trajectories are tracked. The change of bacteria swimming characteristics including swimming velocity, reorientation, and dispersion coefficient are computed directly for individual trajectory and ensemble averaged over thousands of realizations. The results show that shear suppresses the bacterial dispersions in bulk but promote dispersions near the surface contrary to those in quiescent flow condition. Ongoing analyses are focusing to quantify effect of shear rates on tumbling frequency and reorientation of cell body, and its implication in locating the hydrodynamic mechanisms for shear enhanced angular scattering. NIH, NSF, GoMRI.

  2. 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.

  3. Plasmolysis during the division cycle of Escherichia coli.

    OpenAIRE

    Olijhoek, A J; Eden, C G; Trueba, F J; Pas, E; Nanninga, N

    1982-01-01

    Cells of Escherichia coli were plasmolyzed with sucrose. They were classified according to length by way of electron micrographs taken from samples prepared by agar filtration. The percentage of plasmolyzed cells increased about two- and threefold between mean cell sizes of newborn and separating cells. However, dividing cells were less frequently plasmolyzed than nondividing cells of the same length class. Analysis of cell halves (prospective daughters) in dividing cells showed that they beh...

  4. Role for the female in bacterial conjugation in Escherichia coli.

    Science.gov (United States)

    Freifelder, D

    1967-08-01

    Hfr and F' Lac male strains of Escherichia coli were mated with purine-requiring females which had been starved for purine. These females formed mating pairs with the males. However, a mating in the absence of purine markedly reduced the yield of recombinants. Transfer of F' Lac or of lambda prophage also occurred infrequently. It was concluded that deoxyribonucleic acid transfer from male to female requires some, as yet unknown, function of the female.

  5. Maturation of the Escherichia coli divisome occurs in two steps.

    NARCIS (Netherlands)

    Aarsman, M.E.G.; Piette, A.; Fraipont, C.; Vinkenvleugel, T.M.F.; Nguyen-Distèche, M.; den Blaauwen, T.

    2005-01-01

    Cell division proteins FtsZ (FtsA, ZipA, ZapA), FtsE/X, FtsK, FtsQ, FtsL/B, FtsW, PBP3, FtsN and AmiC localize at mid cell in Escherichia coli in an interdependent order as listed. To investigate whether this reflects a time dependent maturation of the divisome, the average cell age at which FtsZ,

  6. Complementation analysis of eleven tryptophanase mutations in Escherichia coli.

    Science.gov (United States)

    White, M K; Yudkin, M D

    1979-10-01

    Nine independent mutants deficient in tryptophanase activity were isolated. Each mutation was transferred to a specialized transducing phage that carries the tryptophanase region of the Escherichia coli chromosome. The nine phages thus produced, and a tenth carrying a previously characterized tryptophanase mutation, were used to lysogenize a bacterial strain harbouring a mutation in the tryptophanase structural gene and also a suppressor of polarity. In no case was complementation observed; we conclude that there is no closely linked positive regulatory gene for tryptophanase.

  7. DNA microarray analysis of fim mutations in Escherichia coli

    DEFF Research Database (Denmark)

    Schembri, Mark; Ussery, David; Workman, Christopher

    2002-01-01

    Bacterial adhesion is often mediated by complex polymeric surface structures referred to as fimbriae. Type I fimbriae of Escherichia coli represent the archetypical and best characterised fimbrial system. These adhesive organelles mediate binding to D-mannose and are directly associated with viru...... the number of fimbriae expressed on the cell surface. The use of high-resolution oligonucleotide arrays for defining points of transcription initiation and termination is also demonstrated....

  8. Characterization of Aspergillus oryzae aspartyl aminopeptidase expressed in Escherichia coli.

    Science.gov (United States)

    Watanabe, Jun; Tanaka, Hisaki; Akagawa, Takumi; Mogi, Yoshinobu; Yamazaki, Tatsuo

    2007-10-01

    To characterize aspartyl aminopeptidase from Aspergillus oryzae, the recombinant enzyme was expressed in Escherichia coli. The enzyme cleaves N-terminal acidic amino acids. About 30% activity was retained in 20% NaCl. Digestion of defatted soybean by the enzyme resulted in an increase in the glutamic acid content, suggesting that the enzyme is potentially responsible for the release of glutamic acid in soy sauce mash.

  9. Escherichia coli and virus isolated from ''sticky kits''

    DEFF Research Database (Denmark)

    Jørgensen, M.; Scheutz, F.; Strandbygaard, Bertel

    1996-01-01

    A total of 121 Escherichia coli strains isolated from 3-week-old mink kits were serotyped and examined for virulence factors. 56 strains were isolated from healthy kits while 65 were from ''sticky kits''. Among these, 34 different serotypes were detected. No difference in serotypes or the presenc...... of virulence factors could be detected between healthy and diseased kits. By electron microscopy of faecal samples corona-, rota-, and calicivirus were demonstrated among healthy as well as diseased kits....

  10. Two Tales of Prokaryotic Genomic Diversity: Escherichia coli and Halophiles

    Directory of Open Access Journals (Sweden)

    Lejla Pašić

    2014-01-01

    Full Text Available Prokaryotes are generally characterized by vast genomic diversity that has been shaped by mutations, horizontal gene transfer, bacteriocins and phage predation. Enormous genetic diversity has developed as a result of stresses imposed in harsh environments and the ability of microorganisms to adapt. Two examples of prokaryotic diversity are presented: on intraspecies level, exemplified by Escherichia coli, and the diversity of the hypersaline environment, with the discussion of food-related health issues and biotechnological potential.

  11. Current perspectivesin pathogenesis and antimicrobial resistance of enteroaggregative Escherichia coli.

    Science.gov (United States)

    Kong, Haishen; Hong, Xiaoping; Li, Xuefen

    2015-08-01

    Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes acute and persistent diarrhea in children and adults. While the pathogenic mechanisms of EAEC intestinal colonization have been uncovered (including bacterial adhesion, enterotoxin and cytotoxin secretion, and stimulation of mucosal inflammation), those of severe extraintestinal infections remain largely unknown. The recent emergence of multidrug resistant EAEC represents an alarming public health threat and clinical challenge, and research on the molecular mechanisms of resistance is urgently needed.

  12. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation

    OpenAIRE

    Majtan, Tomas; Frerman, Frank E.; Kraus, Jan P.

    2010-01-01

    Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound c...

  13. Maturation of the Escherichia coli divisome occurs in two steps.

    NARCIS (Netherlands)

    Aarsman, M.E.G.; Piette, A.; Fraipont, C.; Vinkenvleugel, T.M.F.; Nguyen-Distèche, M.; den Blaauwen, T.

    2005-01-01

    Cell division proteins FtsZ (FtsA, ZipA, ZapA), FtsE/X, FtsK, FtsQ, FtsL/B, FtsW, PBP3, FtsN and AmiC localize at mid cell in Escherichia coli in an interdependent order as listed. To investigate whether this reflects a time dependent maturation of the divisome, the average cell age at which FtsZ, F

  14. Multiple defects in Escherichia coli mutants lacking HU protein.

    OpenAIRE

    Huisman, O; Faelen, M; Girard, D; Jaffé, A; Toussaint, A; Rouvière-Yaniv, J

    1989-01-01

    The HU protein isolated from Escherichia coli, composed of two partially homologous subunits, alpha and beta, shares some of the properties of eucaryotic histones and is a major constituent of the bacterial nucleoid. We report here the construction of double mutants totally lacking both subunits of HU protein. These mutants exhibited poor growth and a perturbation of cell division, resulting in the formation of anucleate cells. In the absence of HU, phage Mu was unable to grow, to lysogenize,...

  15. Condition-dependent cell volume and concentration of Escherichia coli to facilitate data conversion for systems biology modeling

    NARCIS (Netherlands)

    Volkmer, Benjamin; Heinemann, Matthias

    2011-01-01

    Systems biology modeling typically requires quantitative experimental data such as intracellular concentrations or copy numbers per cell. In order to convert population-averaging omics measurement data to intracellular concentrations or cellular copy numbers, the total cell volume and number of cell

  16. Protein abundance profiling of the Escherichia coli cytosol

    Directory of Open Access Journals (Sweden)

    Mann Matthias

    2008-02-01

    Full Text Available Abstract Background Knowledge about the abundance of molecular components is an important prerequisite for building quantitative predictive models of cellular behavior. Proteins are central components of these models, since they carry out most of the fundamental processes in the cell. Thus far, protein concentrations have been difficult to measure on a large scale, but proteomic technologies have now advanced to a stage where this information becomes readily accessible. Results Here, we describe an experimental scheme to maximize the coverage of proteins identified by mass spectrometry of a complex biological sample. Using a combination of LC-MS/MS approaches with protein and peptide fractionation steps we identified 1103 proteins from the cytosolic fraction of the Escherichia coli strain MC4100. A measure of abundance is presented for each of the identified proteins, based on the recently developed emPAI approach which takes into account the number of sequenced peptides per protein. The values of abundance are within a broad range and accurately reflect independently measured copy numbers per cell. As expected, the most abundant proteins were those involved in protein synthesis, most notably ribosomal proteins. Proteins involved in energy metabolism as well as those with binding function were also found in high copy number while proteins annotated with the terms metabolism, transcription, transport, and cellular organization were rare. The barrel-sandwich fold was found to be the structural fold with the highest abundance. Highly abundant proteins are predicted to be less prone to aggregation based on their length, pI values, and occurrence patterns of hydrophobic stretches. We also find that abundant proteins tend to be predominantly essential. Additionally we observe a significant correlation between protein and mRNA abundance in E. coli cells. Conclusion Abundance measurements for more than 1000 E. coli proteins presented in this work

  17. Noise characteristics of the Escherichia coli rotary motor

    Directory of Open Access Journals (Sweden)

    Clausznitzer Diana

    2011-09-01

    Full Text Available Abstract Background The chemotaxis pathway in the bacterium Escherichia coli allows cells to detect changes in external ligand concentration (e.g. nutrients. The pathway regulates the flagellated rotary motors and hence the cells' swimming behaviour, steering them towards more favourable environments. While the molecular components are well characterised, the motor behaviour measured by tethered cell experiments has been difficult to interpret. Results We study the effects of sensing and signalling noise on the motor behaviour. Specifically, we consider fluctuations stemming from ligand concentration, receptor switching between their signalling states, adaptation, modification of proteins by phosphorylation, and motor switching between its two rotational states. We develop a model which includes all signalling steps in the pathway, and discuss a simplified version, which captures the essential features of the full model. We find that the noise characteristics of the motor contain signatures from all these processes, albeit with varying magnitudes. Conclusions Our analysis allows us to address how cell-to-cell variation affects motor behaviour and the question of optimal pathway design. A similar comprehensive analysis can be applied to other two-component signalling pathways.

  18. PROFILE OF RESISTANCE OF Escherichia coli ISOLATED FROM CANINE PYOMETRA

    Directory of Open Access Journals (Sweden)

    Fernanda Santana Oliveira

    2016-10-01

    Full Text Available The endothelial pyometra is a disease that affects more frequently reproductively active adult females. Characterized by inflammation and accumulation of exudate in the uterine cavity, generally associated with bacterial infections. The present study aimed to evaluate the resistance profile of Escherichia coli isolates from 42 female dogs diagnosed with pyometra, seen at the Department of Small Animal Surgery, Hospital of Veterinary Medicine, Federal University of Bahia. To perform the bacteriological analysis, a sample of the contents of the uterus was obtained immediately after surgery of ovariosalpingohisterectomy therapy (OSH and sent to the laboratory. Microbiological analysis showed a predominance of the bacterium Escherichia coli in 40.5% (15/37. Strains of Escherichia coli isolates showed higher rates of resistance to antimicrobial erythromycin (93.3 %, azithromycin (80 %, ampicillin, amoxicillin, and cephalothin (40% each. This study reinforces the need to perform the microbiological examination for epidemiological purposes and the correct therapeutic application, thereby avoiding the indiscriminate use of antimicrobials and the potential emergence of multidrug-resistant  strains. Keywords: bacteria; multiresistant;  uterus.

  19. Vaginal Escherichia coli share common virulence factor profiles, serotypes and phylogeny with other extraintestinal E. coli

    National Research Council Canada - National Science Library

    Obata-Yasuoka, Mana; Ba-Thein, William; Tsukamoto, Teizo; Yoshikawa, Hiroyuki; Hayashi, Hideo

    2002-01-01

    ...: William Ba-Thein. Tel: +81 298 53 3354. Fax: +81 298 53 3354. e-mail: bathein{at}md.tsukuba.ac.jp Characteristics of Escherichia coli residing in the vagina and their role in extraintestinal infections are largely unknown...

  20. Part I. Cobalt thiolate complexes modeling the active site of cobalt nitrile hydratase. Part II. Formation of inorganic nanoparticles on protein scaffolding in Escherichia coli glutamine synthetase

    Science.gov (United States)

    Kung, Irene Yuk Man

    Part I. A series of novel cobalt dithiolate complexes with mixed imine/amine ligand systems is presented here as electronic and structural models for the active site in the bacterial enzyme class, nitrile hydratase (NHase). Pentadentate cobalt(II) complexes with S2N 3 ligand environments are first studied as precursors to the more relevant cobalt(III) complexes. Adjustment of the backbone length by removal of a methylene group increases the reactivity of the system; whereas reduction of the two backbone imine bonds to allow free rotation about those bonds may decrease reactivity. Reactivity change due to the replacement of the backbone amine proton with a more sterically challenging methyl group is not yet clear. Upon oxidation, the monocationic pentadentate cobalt(III) complex, 1b, shows promising reactivity similar to that of NHase. The metal's open coordination site allows reversible binding of the endogenous, monoanionic ligands, N 3- and NCS-. Oxygenation of the thiolate sulfur atoms by exposure to O2 and H2O 2 produces sulfenate and sulfinate ligands in complex 8, which resembles the crystal structure of "deactivated" Fe NHase. However, its lack of reactivity argues against the oxygenated enzyme structure as the active form. Six-coordinate cobalt(III) complexes with S2N4 amine/amine ligand systems are also presented as analogues of previously reported iron(III) compounds, which mimic the spectroscopic properties of Fe NHase. The cobalt complexes do not seem to similarly model Co NHase. However, the S = 0 cobalt(III) center can be spectroscopically silent and difficult to detect, making comparison with synthetic models using common techniques hard. Part II. Dodecameric Escherichia coli glutamine synthetase mutant, E165C, stacks along its six-fold axis to produce tubular nanostructures in the presence of some divalent metal ions, as does the wild type enzyme. The centrally located, engineered Cys-165 residues appear to bind to various species and may serve as

  1. 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...

  2. Heterogeneous distributions of Escherichia coli O157 within naturally infected bovine faecal pats.

    Science.gov (United States)

    Robinson, Susan E; Brown, Patrick E; John Wright, E; Bennett, Malcolm; Hart, C Anthony; French, Nigel P

    2005-03-15

    Escherichia coli O157 is an important human pathogen for which cattle are considered a reservoir. This paper describes and models the variation in counts of E. coli O157 that exists within individual bovine faecal pats. The presence and concentration of E. coli O157 in faecal samples was determined using a combination of direct spiral plating followed by a more sensitive isolation procedure. The data were modelled using multilevel random effect models, in which the random effects were allowed to be correlated to allow for the fact that pooled and individual samples come from the same pat. Up to a two log difference in the concentration of E. coli O157 was demonstrated in samples from different areas within a faecal pat. Pooling of individual samples from throughout the faecal pat and processing it as one composite sample allows this heterogeneity to be overcome.

  3. Prevalence of Escherichia coli in apple cider manufactured in Connecticut.

    Science.gov (United States)

    Dingman, D W

    1999-06-01

    Cider samples obtained from 11 cider mills operating in Connecticut during the 1997 to 1998 production season were tested for the presence of Escherichia coli. Cider production began in mid August and continued through March, with peak production in September and October. Of 314 cider samples tested, 11 (4%) were found to contain E. coli. Of the 11 mills, 6 (55%) tested positive for E. coli in the cider at least once during the production year. E. coli was first observed in cider samples produced in mid to late October and was not detected in samples made after January. A trend was observed for cider to decrease in acidity and increase in Brix (soluble sugars) throughout the production season. No correlation between pH and soluble sugars of cider and the presence of E. coli was detected. Eight mills used both dropped apples and tree-picked apples, whereas three mills used tree-picked apples only. The use of dropped apples in cider production began 5 weeks before the first detection of E. coli in cider. E. coli was isolated from cider samples produced using dropped apples and from samples produced using only tree-picked apples. No direct correlation between the use of dropped apples or tree-picked apples and the presence of E. coli in the cider was observed. An association between the time of apple harvest and the appearance of E. coli in cider was noted. For mills providing adequate records, all contaminated cider was produced from apples harvested between mid October and mid November.

  4. Dynamics of chromosome segregation in Escherichia coli

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck

    2007-01-01

    in the cell by labeling specific parts of it. Later the dynamics of chromosome segregation was included. Investigating chromosome organization by labeling of specific loci was already a widely used technique when I started on this thesis, but the data acquisition and treatment was slow and generally poorly......, and it is obvious that structured cellular actions are required to unpack it, as required for its replication, and refold the two daughter chromosomes separately without getting them entangled in the process each generation. The intention of the study was initially to find out how the chromosome is organized....... Adding the results of the thesis together with known data results in the following description of the chromosome dynamics of slowly growing E.coli cells: The chromosome of slow growing cells is organized with the origin at the cell center when it is newborn. It has one chromosomal arm on one side...

  5. A sense of balance: Experimental investigation and modeling of a malonyl-CoA sensor in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Tamas eFeher

    2015-04-01

    Full Text Available Production of value-added chemicals in microorganisms is regarded as a viable alternative to chemical synthesis. In the past decade, several engineered pathways producing such chemicals, including plant secondary metabolites in microorganisms have been reported; upscaling their production yields, however, was often challenging. Here, we analyze a modular device designed for sensing malonyl-CoA, a common precursor for both fatty acid and flavonoid biosynthesis. The sensor can be used either for high-throughput pathway screening in synthetic biology applications or for introducing a feedback circuit to regulate production of the desired chemical. Here, we used the sensor to compare the performance of several predicted malonyl-CoA producing pathways, and validated the utility of malonyl-CoA reductase and malonate-CoA transferase for malonyl-CoA biosynthesis. We generated a second-order dynamic linear model describing the relation of the fluorescence generated by the sensor to the biomass of the host cell representing a filter/amplifier with a gain that correlates with the level of induction. We found the time constants describing filter dynamics to be independent of the level of induction but distinctively clustered for each of the production pathways, indicating the robustness of the sensor. Moreover, by monitoring the effect of the copy-number of the production plasmid on the dose-response curve of the sensor, we managed to coarse-tune the level of pathway expression to maximize malonyl-CoA synthesis. In addition, we provide an example of the sensor’s use in analyzing the effect of inducer or substrate concentrations on production levels. The rational development of models describing sensors, supplemented with the power of high-throughput optimization provide a promising potential for engineering feedback loops regulating enzyme levels to maximize productivity yields of synthetic metabolic pathways.

  6. Fluorogenic assay for rapid detection of Escherichia coli in food.

    Science.gov (United States)

    Moberg, L J

    1985-12-01

    An assay procedure to screen for Escherichia coli in foods by using 4-methylumbelliferyl-beta-D-glucuronide (MUG) incorporated into lauryl tryptose (LST) broth was evaluated. The beta-glucuronidase produced by E. coli cleaves the MUG substrate to yield a fluorescent end product. E. coli-negative samples can be identified by lack of fluorescence in LST-MUG within 24 h. MUG was not inhibitory to coliforms and E. coli. Over 1,400 food and dairy samples were tested to compare the standard three-tube most-probable-number procedure with the MUG-containing or non-MUG-containing LST procedure. LST-MUG testing detected a greater number of E. coli, with a lower false-positive rate (1.4%) and in a shorter time, than did the standard procedure. All false-positive results in the LST-MUG testing were attributable to beta-glucuronidase-producing staphylococci. No false-negative result was encountered. Use of MUG in LST broth obviates the EC broth step, allowing a 2.5-day procedure to a completed E. coli test versus the present 4- to 6-day standard most-probable-number method.

  7. Examination of uropathogenic Escherichia coli strains conferring large plasmids

    Directory of Open Access Journals (Sweden)

    SUHARTONO

    2010-04-01

    Full Text Available Suhartono (2010 Examination of uropathogenic Escherichia coli strains conferring large plasmids. Biodiversitas 11: 59-64. Of major uropathogens, Escherichia coli has been widely known as a main pathogen of UTIs globally and has considerable medical and financial consequences. A strain of UPEC, namely E. coli ST131, confers a large plasmid encoding cephalosporinases (class C β-lactamase or AmpC that may be disseminated through horizontal transfer among bacterial populations. Therefore, it is worth examining such large plasmids by isolating, purifying, and digesting the plasmid with restriction enzymes. The examination of the large plasmids was conducted by isolating plasmid DNA visualized by agarose gel electrophoresis as well as by PFGE. The relationship of plasmids among isolates was carried out by HpaI restriction enzyme digestion. Of 36 isolates of E. coli ST 131, eight isolates possessed large plasmids, namely isolates 3, 9, 10, 12, 17, 18, 26 and 30 with the largest molecular size confirmed by agarose gel electrophoresis and PFGE was ~42kb and ~118kb respectively. Restriction enzyme analysis revealed that isolates 9, 10, 12, 17 and 18 have the common restriction patterns and those isolates might be closely related.

  8. Production of isopropanol by metabolically engineered Escherichia coli.

    Science.gov (United States)

    Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki

    2008-01-01

    A genetically engineered strain of Escherichia coli JM109 harboring the isopropanol-producing pathway consisting of five genes encoding four enzymes, thiolase, coenzyme A (CoA) transferase, acetoacetate decarboxylase from Clostridium acetobutylicum ATCC 824, and primary-secondary alcohol dehydrogenase from C. beijerinckii NRRL B593, produced up to 227 mM of isopropanol from glucose under aerobic fed-batch culture conditions. Acetate production by the engineered strain was approximately one sixth that produced by a control E. coli strain bearing an expression vector without the clostridial genes. These results demonstrate a functional isopropanol-producing pathway in E. coli and consequently carbon flux from acetyl-CoA directed to isopropanol instead of acetate. This is the first report on isopropanol production by genetically engineered microorganism under aerobic culture conditions.

  9. Protein abundance profiling of the Escherichia coli cytosol

    DEFF Research Database (Denmark)

    Ishihama, Y.; Schmidt, T.; Rappsilber, J.

    2008-01-01

    PAI approach which takes into account the number of sequenced peptides per protein. The values of abundance are within a broad range and accurately reflect independently measured copy numbers per cell. As expected, the most abundant proteins were those involved in protein synthesis, most notably ribosomal...... sample. Using a combination of LC-MS/MS approaches with protein and peptide fractionation steps we identified 1103 proteins from the cytosolic fraction of the Escherichia coli strain MC4100. A measure of abundance is presented for each of the identified proteins, based on the recently developed em...... protein and mRNA abundance in E. coli cells. Conclusion: Abundance measurements for more than 1000 E. coli proteins presented in this work represent the most complete study of protein abundance in a bacterial cell so far. We show significant associations between the abundance of a protein and its...

  10. The Escherichia coli transcriptome linked to growth fitness

    Directory of Open Access Journals (Sweden)

    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.

  11. Pulsed ultra-violet inactivation spectrum of Escherichia coli.

    Science.gov (United States)

    Wang, T; Macgregor, S J; Anderson, J G; Woolsey, G A

    2005-08-01

    Inactivation of Escherichia coli is examined using ultra-violet (UV) radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV content. The flashlamp provides high-energy UV output using a small number of short-duration pulses (30 micros). The flashlamp is used with a monochromator to investigate the wavelength sensitivity of E. coli to inactivation by the pulsed UV light. Using 8 nm wide pulses of UV radiation, the most efficient inactivation is found to occur at around 270 nm and no inactivation is observed above 300 nm. A pyroelectric detector allows the energy dose to be determined at each wavelength, and a peak value for E. coli population reduction of 0.43 log per mJ/cm(2) is measured at 270 nm. The results are compared with the published data available for continuous UV light sources.

  12. OxyR contributes to the virulence of a Clonal Group A Escherichia coli strain (O17:K+:H18) in animal models of urinary tract infection, subcutaneous infection, and systemic sepsis.

    Science.gov (United States)

    Johnson, James R; Russo, Thomas A; Drawz, Sarah M; Clabots, Connie; Olson, Ruth; Kuskowski, Michael A; Rosen, Henry

    2013-11-01

    The oxidative stress response regulator OxyR was assessed as both a urinary and extra-urinary virulence factor in Escherichia coli strain UCB34 (O17:K+:H18), a representative of the emergent Clonal Group A (CGA). Compared to UCB34, the isogenic oxyR mutant exhibited increased H2O2 sensitivity, indistinguishable in vitro growth, and attenuated virulence in rodent models of urinary tract, subcutaneous infection, and systemic sepsis. Complemented mutants showed virulence levels comparable to parent strains in all models. These findings uniquely fulfill molecular Koch's postulates for a putative virulence factor of CGA, provide experimental evidence of an extra-urinary virulence promoting trait in CGA, and document a role for OxyR in local and systemic extra-urinary E. coli infections. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Escherichia coli portador de betalactamasas de espectro extendido: resistencia

    Directory of Open Access Journals (Sweden)

    Mª C. Miranda García

    2013-12-01

    Full Text Available Introducción: Escherichia coli es el microorganismo que con más frecuencia se encuentra implicado en infecciones nosocomiales y comunitarias, patógeno responsable en la etiología de infecciones de vías respiratorias altas, infecciones del tracto urinario, heridas quirúrgicas, sangre o gastroenteritis. En los últimos años ha experimentado importantes cambios encontrándose un aumento de infecciones por cepas de éstos microorganismos productores de betalactamasas de espectro extendido. Objetivos: Se decide hacer este estudio retrospectivo de las muestras procesadas en el Laboratorio de Microbiología del Hospital Básico de la Defensa San Carlos (San Fernando, para conocer la frecuencia y el patrón de sensibilidad en nuestra población por gérmenes productores de betalactamasas de espectro extendido en este caso por Escherichia coli, dada la importancia de las infecciones causadas por esta bacteria y la repercusión que tiene por todo el mundo los mecanismos de resistencia. Material y Método: Se recogieron los datos de resultados obtenidos en las muestras procesadas en el Laboratorio de Microbiología durante 36 meses (Enero 2009 a Diciembre 2011, en las que se hubieran identificado cepas de Escherichia coli y de éstas las productoras de betalactamasas de espectro extendido. Resultados: Se aislaron 34 cepas de Escherichia coli productoras de betalactamasas de espectro extendido lo que supone una tasa del 5,10%. Se encontró una frecuencia mayor en el año 2010 (6,9% que en el 2009 (2,61%, pero similar al 2011 (5,98%. Conclusión: La frecuencia de cepas Escherichia coli con betalactamasas de espectro extendido encontrada es similar a la de otros estudios realizados en España, pero la tasa de resistencia de algunos antimicrobianos como Amoxicilina/clavulánico, Cotrimoxazol y Fluorquinolonas en nuestra población es elevada.

  14. Dissecting the stochastic transcription initiation process in live Escherichia coli.

    Science.gov (United States)

    Lloyd-Price, Jason; Startceva, Sofia; Kandavalli, Vinodh; Chandraseelan, Jerome G; Goncalves, Nadia; Oliveira, Samuel M D; Häkkinen, Antti; Ribeiro, Andre S

    2016-06-01

    We investigate the hypothesis that, in Escherichia coli, while the concentration of RNA polymerases differs in different growth conditions, the fraction of RNA polymerases free for transcription remains approximately constant within a certain range of these conditions. After establishing this, we apply a standard model-fitting procedure to fully characterize the in vivo kinetics of the rate-limiting steps in transcription initiation of the Plac/ara-1 promoter from distributions of intervals between transcription events in cells with different RNA polymerase concentrations. We find that, under full induction, the closed complex lasts ∼788 s while subsequent steps last ∼193 s, on average. We then establish that the closed complex formation usually occurs multiple times prior to each successful initiation event. Furthermore, the promoter intermittently switches to an inactive state that, on average, lasts ∼87 s. This is shown to arise from the intermittent repression of the promoter by LacI. The methods employed here should be of use to resolve the rate-limiting steps governing the in vivo dynamics of initiation of prokaryotic promoters, similar to established steady-state assays to resolve the in vitro dynamics. © The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

  15. Forced resurgence and targeting of intracellular uropathogenic Escherichia coli reservoirs.

    Directory of Open Access Journals (Sweden)

    Matthew G Blango

    Full Text Available Intracellular quiescent reservoirs of uropathogenic Escherichia coli (UPEC, which can seed the bladder mucosa during the acute phase of a urinary tract infection (UTI, are protected from antibiotic treatments and are extremely difficult to eliminate. These reservoirs are a potential source for recurrent UTIs that affect millions annually. Here, using murine infection models and the bladder cell exfoliant chitosan, we demonstrate that intracellular UPEC populations shift within the stratified layers of the urothelium during the course of a UTI. Following invasion of the terminally differentiated superficial layer of epithelial cells that line the bladder lumen, UPEC can multiply and disseminate, eventually establishing reservoirs within underlying immature host cells. If given access, UPEC can invade the superficial and immature bladder cells equally well. As infected immature host cells differentiate and migrate towards the apical surface of the bladder, UPEC can reinitiate growth and discharge into the bladder lumen. By inducing the exfoliation of the superficial layers of the urothelium, chitosan stimulates rapid regenerative processes and the reactivation and efflux of quiescent intracellular UPEC reservoirs. When combined with antibiotics, chitosan treatment significantly reduces bacterial loads within the bladder and may therefore be of therapeutic value to individuals with chronic, recurrent UTIs.

  16. Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Po-Han Chan

    Full Text Available Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs. The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm. The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6 cells/mL.

  17. Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli.

    Science.gov (United States)

    Chan, Po-Han; Ghosh, Bhaswati; Lai, Hong-Zheng; Peng, Hwei-Ling; Mong, Kwok Kong Tony; Chen, Yu-Chie

    2013-01-01

    Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs). The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann) were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH) was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm). The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6) cells/mL.

  18. Virulence and Fitness Determinants of Uropathogenic Escherichia coli.

    Science.gov (United States)

    Subashchandrabose, Sargurunathan; Mobley, Harry L T

    2015-08-01

    Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is a major global public health concern. Increasing antibiotic resistance found in clinical UPEC isolates underscores the immediate need for development of novel therapeutics against this pathogen. Better understanding of the fitness and virulence mechanisms that are integral to the pathogenesis of UTI will facilitate identification of novel strategies to prevent and treat infection with UPEC. Working towards that goal, the global UPEC research community has made great strides at unraveling various virulence and fitness genes. Here, we summarize major findings on virulence and fitness determinants that enable UPEC to successfully survive and colonize the urinary tract of mammalian hosts. Major sections of this chapter are devoted to the role of iron acquisition systems, metabolic pathways, fimbriae, flagella, toxins, biofilm formation, capsule, and strain-specific genes in the initiation and progression of UTIs. Transcriptomes of UPEC during experimental UTI in a murine model and naturally occurring UTI in women are compared to elucidate virulence mechanisms specifically involved in human UTI. Capitalizing on the advances in molecular pathogenesis research by translating these findings will help develop better clinical strategies for prevention and management of UTIs.

  19. Evidence for a human-specific Escherichia coli clone.

    Science.gov (United States)

    Clermont, Olivier; Lescat, Mathilde; O'Brien, Claire L; Gordon, David M; Tenaillon, Olivier; Denamur, Erick

    2008-04-01

    Escherichia coli is a widespread commensal of the vertebrate intestinal tract. Until recently, no strong association between a particular clone and a given host species has been found. However, members of the B2 subgroup VIII clone with an O81 serotype appear to be human host specific. To determine the degree of host specificity exhibited by this clone, a PCR-based assay was used to screen 723 faecal and clinical isolates from humans, and 904 faecal isolates from animals. This clone was not detected among the animal isolates, but was discovered in people living in Africa, Europe and South America. The clone is rarely isolated from people suffering from intestinal or extraintestinal disease and is avirulent in a mouse model of extraintestinal infection. Fine-scale epidemiological analysis suggests that this clone is competitively dominant relative to other members of the B2 phylogenetic group and that it has increased in frequency over the past 20 years. This clone appears to be a good candidate for use as a probiotic, and may be suitable as an indicator of human faecal contamination in microbial source tracking studies.

  20. In Vivo Efficacy of Trovafloxacin against Bacteroides fragilis in Mixed Infection with either Escherichia coli or a Vancomycin-Resistant Strain of Enterococcus faecium in an Established-Abscess Murine Model

    OpenAIRE

    2001-01-01

    The pharmacodynamic and pharmacokinetic properties of trovafloxacin were studied in a standardized murine model of established subcutaneous abscesses. Daily dosing regimens of 37.5 to 300 mg/kg every 8 h (q8h) or every 24 h (q24h) were started 3 days after inoculation with mixtures containing either Bacteroides fragilis-Escherichia coli-autoclaved cecal contents (ACC) or B. fragilis–vancomycin-resistant Enterococcus faecium (VREF)–ACC. Treatment was continued for 3 or 5 days. The efficacy of ...

  1. Transcriptional effects of CRP* expression in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Ghosh Debashis

    2009-08-01

    Full Text Available Abstract Background Escherichia coli exhibits diauxic growth in sugar mixtures due to CRP-mediated catabolite repression and inducer exclusion related to phosphotransferase system enzyme activity. Replacement of the native crp gene with a catabolite repression mutant (referred to as crp* enables co-utilization of glucose and other sugars in E. coli. While previous studies have examined the effects of expressing CRP* mutants on the expression of specific catabolic genes, little is known about the global transcriptional effects of CRP* expression. In this study, we compare the transcriptome of E. coli W3110 (expressing wild-type CRP to that of mutant strain PC05 (expressing CRP* in the presence and absence of glucose. Results The glucose effect is significantly suppressed in strain PC05 relative to strain W3110. The expression levels of glucose-sensitive genes are generally not altered by glucose to the same extent in strain PCO5 as compared to W3110. Only 23 of the 80 genes showing significant differential expression in the presence of glucose for strain PC05 are present among the 418 genes believed to be directly regulated by CRP. Genes involved in central carbon metabolism (including several TCA cycle genes and amino acid biosynthesis, as well as genes encoding nutrient transport systems are among those whose transcript levels are most significantly affected by CRP* expression. We present a detailed transcription analysis and relate these results to phenotypic differences between strains expressing wild-type CRP and CRP*. Notably, CRP* expression in the presence of glucose results in an elevated intracellular NADPH concentration and reduced NADH concentration relative to wild-type CRP. Meanwhile, a more drastic decrease in the NADPH/NADP+ ratio is observed for the case of CRP* expression in strains engineered to reduce xylose to xylitol via a heterologously expressed, NADPH-dependent xylose reductase. Altered expression levels of

  2. Quorum sensing in the probiotic bacterium Escherichia coli Nissle 1917 (Mutaflor – evidence that furanosyl borate diester (AI-2 is influencing the cytokine expression in the DSS colitis mouse model

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    Jacobi Christoph A

    2012-08-01

    Full Text Available Abstract Background “Quorum sensing” (QS is the phenomenon which allows single bacterial cells to measure the concentration of bacterial signal molecules. Two principle different QS systems are known, the Autoinducer 1 system (AI-1 for the intraspecies communication using different Acyl-homoserine lactones (AHL and AI-2 for the interspecies communication. Aim of this study was to investigate QS of Escherichia coli Nissle 1917 (Mutaflor. Results While E. coli Nissle is producing AI-2 in a density dependent manner, no AI-1 was produced. To study the effect of AI-2 in the DSS (dextran sulphate sodium induced mouse model of acute colitis, we silenced the corresponding gene luxS by intron insertion. The mutant bacterium E. coli Nissle::luxS was equally effective in colonizing the colon and the mutation turned out to be 100% stable during the course of the experiment. Isolating RNA from the colon mucosa and performing semiquantitative RT PCR, we were able to show that the expression of the pro-inflammatory cytokine IFN-y was suppressed in mice being infected with the E. coli Nissle wild type. Mice infected with the E. coli Nissle::luxS mutant showed a suppressed expression of IL-10 compared to uninfected mice, while the expression of the pro-inflammatory cytokines IL-6 and TNF-α was higher in these mice. The expression of mBD-1 was suppressed in mice being infected with the mutant in comparison to the mice not infected or infected with the wild type. No differences were seen in the histological examination of the colon sections in the different groups of mice. Conclusions E. coli Nissle is producing AI-2 molecules, which are influencing the expression of cytokines in the mucosa of the colon in the DSS mice. However, if QS has a direct influence on the probiotic properties of E. coli Nissle remains to be elucidated.

  3. 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

    2017-10-03

    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

  4. The EcoCyc database: reflecting new knowledge about Escherichia coli K-12

    Science.gov (United States)

    Keseler, Ingrid M.; Mackie, Amanda; Santos-Zavaleta, Alberto; Billington, Richard; Bonavides-Martínez, César; Caspi, Ron; Fulcher, Carol; Gama-Castro, Socorro; Kothari, Anamika; Krummenacker, Markus; Latendresse, Mario; Muñiz-Rascado, Luis; Ong, Quang; Paley, Suzanne; Peralta-Gil, Martin; Subhraveti, Pallavi; Velázquez-Ramírez, David A.; Weaver, Daniel; Collado-Vides, Julio; Paulsen, Ian; Karp, Peter D.

    2017-01-01

    EcoCyc (EcoCyc.org) is a freely accessible, comprehensive database that collects and summarizes experimental data for Escherichia coli K-12, the best-studied bacterial model organism. New experimental discoveries about gene products, their function and regulation, new metabolic pathways, enzymes and cofactors are regularly added to EcoCyc. New SmartTable tools allow users to browse collections of related EcoCyc content. SmartTables can also serve as repositories for user- or curator-generated lists. EcoCyc now supports running and modifying E. coli metabolic models directly on the EcoCyc website. PMID:27899573

  5. Estimating Escherichia coli loads in streams based on various physical, chemical, and biological factors.

    Science.gov (United States)

    Dwivedi, Dipankar; Mohanty, Binayak P; Lesikar, Bruce J

    2013-05-01

    Microbes have been identified as a major contaminant of water resources. Escherichia coli (E. coli) is a commonly used indicator organism. It is well recognized that the fate of E. coli in surface water systems is governed by multiple physical, chemical, and biological factors. The aim of this work is to provide insight into the physical, chemical, and biological factors along with their interactions that are critical in the estimation of E. coli loads in surface streams. There are various models to predict E. coli loads in streams, but they tend to be system or site specific or overly complex without enhancing our understanding of these factors. Hence, based on available data, a Bayesian Neural Network (BNN) is presented for estimating E. coli loads based on physical, chemical, and biological factors in streams. The BNN has the dual advantage of overcoming the absence of quality data (with regards to consistency in data) and determination of mechanistic model parameters by employing a probabilistic framework. This study evaluates whether the BNN model can be an effective alternative tool to mechanistic models for E. coli loads estimation in streams. For this purpose, a comparison with a traditional model (LOADEST, USGS) is conducted. The models are compared for estimated E. coli loads based on available water quality data in Plum Creek, Texas. All the model efficiency measures suggest that overall E. coli loads estimations by the BNN model are better than the E. coli loads estimations by the LOADEST model on all the three occasions (three-fold cross validation). Thirteen factors were used for estimating E. coli loads with the exhaustive feature selection technique, which indicated that six of thirteen factors are important for estimating E. coli loads. Physical factors included temperature and dissolved oxygen; chemical factors include phosphate and ammonia; biological factors include suspended solids and chlorophyll. The results highlight that the LOADEST model

  6. Evaluation of Five Jet Fuels in the Salmonella-Escherichia coli / Microsome Plate Incorporation Assay

    Science.gov (United States)

    2010-09-01

    AFRL-RH-WP-TR-2010-0138 Evaluation of Five Jet Fuels in the Salmonella-Escherichia coli / Microsome Plate Incorporation Assay Edward S...31 Jul 2010 4. TITLE AND SUBTITLE Evaluation of Five Jet Fuels in the Salmonella-Escherichia coli / Microsome Plate Incorporation Assay 5a...the Salmonella typhimurium-Escherichia coli/ microsome plate incorporation assay. The assay was performed using the plate incorporation procedure

  7. High temporal variability in commensal Escherichia coli strain communities of a herbivorous marsupial.

    Science.gov (United States)

    Blyton, Michaela D J; Banks, Sam C; Peakall, Rod; Gordon, David M

    2013-08-01

    Although Escherichia coli is an important model organism for bacterial research, few studies have explored the nature of temporal variation in E. coli strains within the intestinal tracts of host individuals. In this study the E. coli strains of 54 mountain brushtail possums were sampled on four occasions during a year. This allowed temporal changes to be quantified both at the host population level and within individuals. Escherichia coli strains were identified using a combination of rep-PCR profiles from two primers (CGG and ERIC) and phylogenetic group assigned by quadruplex PCR. The study revealed considerable changes in community structure within individuals among all time periods. In fact, temporal variation within individuals accounted for more of the variation in E. coli community structure than differences between animals. In contrast to the within-host dynamics, there were no significant differences among the time periods at the host population level. It was also found that there was no effect of host age or sex on strain community structure within host individuals. These findings highlight the importance of temporal variation in the ecology of E. coli, while the methods applied in this study may serve as a foundation for further work in this area.

  8. Autogenous regulation of Escherichia coli polynucleotide phosphorylase expression revisited.

    Science.gov (United States)

    Carzaniga, Thomas; Briani, Federica; Zangrossi, Sandro; Merlino, Giuseppe; Marchi, Paolo; Dehò, Gianni

    2009-03-01

    The Escherichia coli polynucleotide phosphorylase (PNPase; encoded by pnp), a phosphorolytic exoribonuclease, posttranscriptionally regulates its own expression at the level of mRNA stability and translation. Its primary transcript is very efficiently processed by RNase III, an endonuclease that makes a staggered double-strand cleavage about in the middle of a long stem-loop in the 5'-untranslated region. The processed pnp mRNA is then rapidly degraded in a PNPase-dependent manner. Two non-mutually exclusive models have been proposed to explain PNPase autogenous regulation. The earlier one suggested that PNPase impedes translation of the RNase III-processed pnp mRNA, thus exposing the transcript to degradative pathways. More recently, this has been replaced by the current model, which maintains that PNPase would simply degrade the promoter proximal small RNA generated by the RNase III endonucleolytic cleavage, thus destroying the double-stranded structure at the 5' end that otherwise stabilizes the pnp mRNA. In our opinion, however, the first model was not completely ruled out. Moreover, the RNA decay pathway acting upon the pnp mRNA after disruption of the 5' double-stranded structure remained to be determined. Here we provide additional support to the current model and show that the RNase III-processed pnp mRNA devoid of the double-stranded structure at its 5' end is not translatable and is degraded by RNase E in a PNPase-independent manner. Thus, the role of PNPase in autoregulation is simply to remove, in concert with RNase III, the 5' fragment of the cleaved structure that both allows translation and prevents the RNase E-mediated PNPase-independent degradation of the pnp transcript.

  9. Autogenous Regulation of Escherichia coli Polynucleotide Phosphorylase Expression Revisited▿ †

    Science.gov (United States)

    Carzaniga, Thomas; Briani, Federica; Zangrossi, Sandro; Merlino, Giuseppe; Marchi, Paolo; Dehò, Gianni

    2009-01-01

    The Escherichia coli polynucleotide phosphorylase (PNPase; encoded by pnp), a phosphorolytic exoribonuclease, posttranscriptionally regulates its own expression at the level of mRNA stability and translation. Its primary transcript is very efficiently processed by RNase III, an endonuclease that makes a staggered double-strand cleavage about in the middle of a long stem-loop in the 5′-untranslated region. The processed pnp mRNA is then rapidly degraded in a PNPase-dependent manner. Two non-mutually exclusive models have been proposed to explain PNPase autogenous regulation. The earlier one suggested that PNPase impedes translation of the RNase III-processed pnp mRNA, thus exposing the transcript to degradative pathways. More recently, this has been replaced by the current model, which maintains that PNPase would simply degrade the promoter proximal small RNA generated by the RNase III endonucleolytic cleavage, thus destroying the double-stranded structure at the 5′ end that otherwise stabilizes the pnp mRNA. In our opinion, however, the first model was not completely ruled out. Moreover, the RNA decay pathway acting upon the pnp mRNA after disruption of the 5′ double-stranded structure remained to be determined. Here we provide additional support to the current model and show that the RNase III-processed pnp mRNA devoid of the double-stranded structure at its 5′ end is not translatable and is degraded by RNase E in a PNPase-independent manner. Thus, the role of PNPase in autoregulation is simply to remove, in concert with RNase III, the 5′ fragment of the cleaved structure that both allows translation and prevents the RNase E-mediated PNPase-independent degradation of the pnp transcript. PMID:19136586

  10. Multiple antimicrobial resistance among Avian Escherichia coli strains in Albania

    Directory of Open Access Journals (Sweden)

    Antonio Camarda

    2010-01-01

    Full Text Available In this study, 101 Escherichia (E. coli isolates from broilers, laying hens and turkeys which had died from colibacillosis, collected from 37 intensive and rural farms in Albania, were tested for antimicrobial susceptibility toward 12 different molecules. The highest levels of resistance were observed for Erythromycin (E (100% Amoxicillin (AMX (99.1%, Tetracycline (TE 30 (96.07%, Streptomycin (STR (93.07% and Neomycin (N30 (85.15%. Considerable resistance was also detected for fluoroquinolones. Moreover, 73.33% of E. coli resistant to at least one fluoroquinolone were also resistant to the two other fluoroquinolones checked. No evident differences were found between the E. coli from intensive and from rural farms. Multiple antibiotic resistance was expressed by all the E. coli tested. 23.63% and 17.39% of E. coli isolated from intensive and rural farms, respectively, were resistant towards all the drugs tested. These data would seem to indicate incorrect use of antibiotics on poultry farms in Albania.

  11. Escherichia coli exports cyclic AMP via TolC.

    Science.gov (United States)

    Hantke, Klaus; Winkler, Karin; Schultz, Joachim E

    2011-03-01

    In Escherichia coli more than 180 genes are regulated by the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex. However, more than 90% of cAMP that is made by intracellular adenylyl cyclases is found in the culture medium. How is cAMP exported from E. coli? In a tolC mutant, 0.03 mM IPTG (isopropyl-β-d-thiogalactopyranoside) was sufficient to induce β-galactosidase compared to 0.1 mM IPTG in the parent strain. In a cya mutant unable to produce cAMP about 1 mM extracellular cAMP was required to induce β-galactosidase, whereas in a cya tolC mutant 0.1 mM cAMP was sufficient. When cAMP in E. coli cya was generated intracellularly by a recombinant, weakly active adenylyl cyclase from Corynebacterium glutamicum, the critical level of cAMP necessary for induction of maltose degradation was only achieved in a tolC mutant and not in the parent strain. Deletion of a putative cAMP phosphodiesterase of E. coli, CpdA, resulted in a slightly similar, yet more diffuse phenotype. The data demonstrate that export of cAMP via TolC is a most efficient way of E. coli to lower high concentrations of cAMP in the cell and maintain its sensitivity in changing metabolic environments.

  12. Phylogenetic analysis of Escherichia coli strains isolated from human samples

    Directory of Open Access Journals (Sweden)

    Abdollah Derakhshandeh

    2013-12-01

    Full Text Available Escherichia coli (E. coli is a normal inhabitant of the gastrointestinal tract of vertebrates, including humans. Phylogenetic analysis has shown that E. coli is composed of four main phylogenetic groups (A, B1, B2 and D. Group A and B1 are generally associated with commensals, whereas group B2 is associated with extra-intestinal pathotypes. Most enteropathogenic isolates, however, are assigned to group D. In the present study, a total of 102 E. coli strains, isolated from human samples, were used. Phylogenetic grouping was done based on the Clermont triplex PCR method using primers targeted at three genetic markers, chuA, yjaA and TspE4.C2. Group A contained the majority of the collected isolates (69 isolates, 67.64%, followed by group B2 (18 isolates, 17.64% and D (15 isolates, 14.7% and no strains were found to belong to group B1. The distribution of phylogenetic groups in our study suggests that although the majority of strains were commensals, the prevalence of enteropathogenic and extra-intestinal pathotypes was noteworthy. Therefore, the role of E. coli in human infections including diarrhea, urinary tract infections and meningitis should be considered.

  13. Role of peripheral pooling in porcine Escherichia coli sepsis

    Energy Technology Data Exchange (ETDEWEB)

    Teule, G.J.; von Lingen, A.; Verwey von Vught, M.A.; Kester, A.D.; Mackaay, R.C.; Bezemer, P.D.; Heidenal, G.A.; Thijs, L.G.

    1984-01-01

    In anesthesized pigs the effects of E. coli (2 X 10(8)/kg) on hemodynamics and red cell distribution were studied. After injection of 99m-Tc red cells (15 mCi), regional radioactivity was followed during 3 hours. Gated bloodpool studies were performed to measure end-diastolic volumes (EDV). Escherichia coli E. coli was infused in 14 pigs, while 7 animals served as controls. E. coli resulted in an early increase in pulmonary arterial pressure. Systemic arterial pressure decreased gradually, while cardiac output did not change significantly. The gated studies revealed that especially left ventricular end-diastolic volume (LVEDV) declined, to 50% of the basal value. Regional radioactivity did not change over lungs, liver and abdomen. Splenic activity declined markedly. Over the hindlimb a significant increase (29 +/- 8%) was observed. It is concluded that E. coli infusion in pigs induces a hemodynamic pattern similar to human sepsis. The decrease in LVEDV is probably related to peripheral pooling and a change in right ventricle (RV) performance.

  14. Unusual "flesh-eating" strains of Escherichia coli.

    Science.gov (United States)

    Shaked, Hila; Samra, Zmira; Paul, Michal; Madar-Shapiro, Liora; Cohen, Jonathan; Pitlik, Silvio; Bishara, Jihad

    2012-12-01

    Monomicrobial necrotizing fasciitis (type II) is typically caused by group A streptococcus alone or in combination with Staphylococcus aureus. Escherichia coli has been isolated from polymicrobial or Fournier's gangrene but has rarely been reported in monomicrobial necrotizing fasciitis. We describe the clinical characteristics and outcomes of seven cases of monomicrobial E. coli necrotizing fasciitis and/or severe soft tissue infection diagnosed at a single institution during an 18-month period. Four isolates from three patients and two isolates from two patients with type I polymicrobial severe soft tissue infection (controls) were assayed by the randomly amplified polymorphic DNA (RAPD) analysis for fingerprinting and PCR amplification of primers in order to detect cytotoxic necrotizing factor 1 and 2 (cnf1 and cnf2) genes. All patients had some type of immune suppression. The limb was the most commonly involved organ. In all cases, E. coli was isolated as a monomicrobial pathogen from blood, fascia, or both. All patients died during hospitalization, three within the first 48 h. The RAPD amplification assay showed a high degree of genetic diversity among the "flesh-eating" strains and controls. The cnf1 toxin gene was identified in two out of three cases, but not in the controls. cnf2 was not detected in any of the patients. E. coli may be responsible for life-threatening necrotizing fasciitis. Further research is needed to reveal relevant risk factors, reservoirs, and modes of transmission of cnf1 E. coli.

  15. 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

  16. Nonthermal atmospheric argon plasma jet effects on Escherichia coli biomacromolecules.

    Science.gov (United States)

    Hosseinzadeh Colagar, Abasalt; Memariani, Hamed; Sohbatzadeh, Farshad; Valinataj Omran, Azadeh

    2013-12-01

    Nonthermal atmospheric plasma jet, a promising technology based on ionized gas at low temperatures, can be applied for disinfection of contaminated surfaces. In this study, Escherichia coli cells and their macromolecules were exposed to the nonthermal atmospheric argon plasma jet for different time durations. Total protein, genomic DNA, and malondialdehyde (MDA) levels of E. coli were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining; agarose gel electrophoresis; and measurement of absorbance at 534 nm, respectively. After exposure, the spectroscopic results of liquid samples indicated that the survival reduction of E. coli can reach to 100 % in an exposure time of 600 s. Moreover, inactivation zones of E. coli, DNA degradation, and MDA levels were significantly increased. Additionally, banding patterns of total protein were changed and amino acid concentrations increased following ninhydrin test. The experimental results suggest that the nonthermal plasma could serve as an effective instrument for both sterilizing E. coli and degrading macromolecules from the surface of the objects being sterilized.

  17. Paper-based ELISA to rapidly detect Escherichia coli.

    Science.gov (United States)

    Shih, Cheng-Min; Chang, Chia-Ling; Hsu, Min-Yen; Lin, Jyun-Yu; Kuan, Chen-Meng; Wang, Hsi-Kai; Huang, Chun-Te; Chung, Mu-Chi; Huang, Kui-Chou; Hsu, Cheng-En; Wang, Chun-Yuan; Shen, Ying-Cheng; Cheng, Chao-Min

    2015-12-01

    Escherichia coli is a generic indicator of fecal contamination, and certain serotypes cause food- and water-borne illness such as O157:H7. In the clinic, detection of bacteriuria, which is often due to E. coli, is critical before certain surgical procedures or in cases of nosocomial infection to prevent further adverse events such as postoperative infection or sepsis. In low- and middle-income countries, where insufficient equipment and facilities preclude modern methods of detection, a simple, low-cost diagnostic device to detect E. coli in water and in the clinic will have significant impact. We have developed a simple paper-based colorimetric platform to detect E. coli contamination in 5h. On this platform, the mean color intensity for samples with 10(5)cells/mL is 0.118±0.002 (n=4), and 0.0145±0.003 (Ppaper-based ELISA is an innovative point-of-care diagnostic tool to rapidly detect E. coli, and possibly other pathogens when customized as appropriate, especially in areas that lack advanced clinical equipment.

  18. 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.

  19. Escherichia coli mediated urinary tract infections: are there distinct uropathogenic E. coli (UPEC) pathotypes?

    Science.gov (United States)

    Marrs, Carl F; Zhang, Lixin; Foxman, Betsy

    2005-11-15

    A variety of virulence genes are associated with Escherichia coli mediated urinary tract infections. Particular sets of virulence factors shared by bacterial strains directing them through a particular pathogenesis process are called a "pathotype." Comparison of co-occurrence of potential urinary tract infection (UTI) virulence genes among different E. coli isolates from fecal and UTI collections provides evidence for multiple pathotypes of uropathogenic E. coli, but current understanding of critical genetic differences defining the pathotypes is limited. Discovery of additional E. coli genes involved in uropathogenesis and determination of their distribution and co-occurrences will further define UPEC pathotypes and allow for a more detailed analysis of how these pathotypes might differ in how they cause disease.

  20. The Escherichia coli Acid Stress Response and Its Significance for Pathogenesis.

    Science.gov (United States)

    De Biase, Daniela; Lund, Peter A

    2015-01-01

    Escherichia coli has a remarkable ability to survive low pH and possesses a number of different genetic systems that enable it to do this. These may be expressed constitutively, typically in stationary phase, or induced by growth under a variety of conditions. The activities of these systems have been implicated in the ability of E. coli to pass the acidic barrier of the stomach and to become established in the gastrointestinal tract, something causing serious infections. However, much of the work characterizing these systems has been done on standard laboratory strains of E. coli and under conditions which do not closely resemble those found in the human gut. Here we review what is known about acid resistance in E. coli as a model laboratory organism and in the context of its lifestyle as an inhabitant-sometimes an unwelcome one-of the human gut.

  1. Responses of Escherichia coli bacteria to two opposing chemoattractant gradients depend on the chemoreceptor ratio.

    Science.gov (United States)

    Kalinin, Yevgeniy; Neumann, Silke; Sourjik, Victor; Wu, Mingming

    2010-04-01

    Escherichia coli chemotaxis has long served as a simple model of environmental signal processing, and bacterial responses to single chemical gradients are relatively well understood. Less is known about the chemotactic behavior of E. coli in multiple chemical gradients. In their native environment, cells are often exposed to multiple chemical stimuli. Using a recently developed microfluidic chemotaxis device, we exposed E. coli cells to two opposing but equally potent gradients of major attractants, methyl-aspartate and serine. The responses of E. coli cells demonstrated that chemotactic decisions depended on the ratio of the respective receptor number of Tar/Tsr. In addition, the ratio of Tar to Tsr was found to vary with cells' growth conditions, whereby it depended on the culture density but not on the growth duration. These results provide biological insights into the decision-making processes of chemotactic bacteria that are subjected to multiple chemical stimuli and demonstrate the importance of the cellular microenvironment in determining phenotypic behavior.

  2. EcoCyc: an encyclopedia of Escherichia coli genes and metabolism.

    Science.gov (United States)

    Karp, P D; Riley, M; Paley, S M; Pelligrini-Toole, A

    1996-01-01

    The encyclopedia of Escherichia coli genes and metabolism (EcoCyc) is a database that combines information about the genome and the intermediary metabolism of E.coli. It describes 2034 genes, 306 enzymes encoded by these genes, 580 metabolic reactions that occur in E.coli and the organization of these reactions into 100 metabolic pathways. The EcoCyc graphical user interface allows query and exploration of the EcoCyc database using visualization tools such as genomic map browsers and automatic layouts of metabolic pathways. EcoCyc spans the space from sequence to function to allow investigation of an unusually broad range of questions. EcoCyc can be thought of as both an electronic review article, because of its copious references to the primary literature, and as an in silico model of E.coli that can be probed and analyzed through computational means.

  3. Pathogenicity of Escherichia coli O123 from Rex Rabbit on White Mice

    Institute of Scientific and Technical Information of China (English)

    Wang; Yanping; Guo; Shijin; Yang; Limei; Dong; Lin; Xu; Qianqian; Shen; Zhiqiang

    2014-01-01

    [Objective]The paper was to analyze the pathogenesis of Escherichia coli O123 from rex rabbit. [Method]E. coli O123 isolated from rabbit liver with diarrhea symptom in scale rex rabbit farm was intraperitoneally injected into 18- 22 g Kunming mice,and its pathogenicity was determined by clinical symptoms and pathological examination. [Result]When the inoculation concentration was about 8. 5 × 107 CFU /mL,Kunming mice appeared the clinical symptoms of drooping spirit,diarrhea and gathering,and the mortality reached 50%. Anatomical examination found that intestinal wall was thinning and intestinal mucosa was bleeding. [Conclusion]E. coli from rex rabbit has strong pathogenicity,and establishing animal model with Kunming mice to study its pathogenesis is of great reference significance for diagnosis and prevention of E. coli disease of rex rabbit.

  4. Viabilidad de Escherichia coli en presencia de diferentes contaminantes

    Directory of Open Access Journals (Sweden)

    Antonio Rivera T

    2006-04-01

    Full Text Available La contaminación en ríos condiciona la presencia de microorganismos adaptados al ecosistema entre ellos a patógenos de importancia en salud pública. Objetivo: Determinar la viabilidad de Escherichia coli en presencia de nitrato de plata, carbonato de amonio, fenol y formaldehído. Materiales y métodos: Se tomaron muestras de agua del río Alseseca, que luego se sembró en medios de cultivo selectivos para enterobacterias, seleccionándose las colonias del género Escherichia, las cuales fueron sembradas en el medio de orientación CHROMagar ECC. Las muestras de E. coli se evaluaron en presencia de nitrato de plata, carbonato de amonio, fenol y formaldehído. Resultados: El grupo experimental presentó viabilidad en presencia de los cuatro compuestos, el grupo control positivo presentó nula viabilidad, la comparación entre los grupos mostró diferencia significativa (p< 0,05. Conclusión: Los aislamientos de E. coli mostraron viabilidad, implicando riesgos para el ecosistemas y la salud, ya que el río Alseseca atraviesa por el municipio de Puebla donde existen núcleos poblacionales importantes.

  5. Overexpression and export of Vibrio anguillarum metalloprotease in Escherichia coli

    Institute of Scientific and Technical Information of China (English)

    Zhang Fengli; Chi Zhenming; Chen Jixiang; Wu Longfei; Liang Likun

    2007-01-01

    Vibrio anguillarum metalloprotease, an extracellular zinc metalloprotease involved in the virulence mechanism of Vibrio anguillarum, is synthesized from the empA gene as a 611-residue precursor and naturally secreted via Sec secretion pathway in Vibrio anguillarum. In this study, heterologous expression of the empA gene encoding metallopmtease and export of the recombinant metalloprotease in Escherichia coliwere examined. The empA gene was subcloned into pBAD24 with arabinose promoter and sequenced. The sequence encoded a polypeptide(611 amino acids)consisting of four domains: a signal peptide, an Nterminal propeptide, a mature region and a C-terminal propeptide. The empA gene inserted in plasmid pBAD24 was overexpressed in TOP10 strain of E. Coli after arabinose induction. The 36kDa polypeptide of the recombinant metalloprotease as the mature protease was further confirmed by SDS-PAGE and immunoblotting. It was found that recombinant metalloprotease with the EmpA activity and antigenicity wasexported into the periplasm of Escherichia coli cells via Sec translocation pathway, whereas it was secreted into extracellular environments in V. Anguillarum. The results imply that the expression, export and processing mechanism of the protein in E. Coli are similar to those in V. Anguillarum.

  6. 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.

  7. Genome Sequence of the Enterohemorrhagic Escherichia coli Bacteriophage UFV-AREG1

    Science.gov (United States)

    Batalha, Laís Silva; Albino, Luiz Augusto A.; Boggione, Delaine Meireles Gouveia; Gontijo, Marco Tulio Pardini; Bazzolli, Denise M. Soares; Mendonca, Regina C. Santos

    2016-01-01

    Here, we present the genome sequence of the Escherichia coli bacteriophage UFV-AREG1. This phage was isolated from cowshed wastewater and showed specificity for enterohemorrhagic E. coli O157:H7 (ATCC 43895), E. coli 0111 (CDC O11ab) and E. coli (ATCC 23229). PMID:27738021

  8. Multiplex PCR for Diagnosis of Enteric Infections Associated with Diarrheagenic Escherichia coli

    Science.gov (United States)

    Vidal, Roberto; Vidal, Maricel; Lagos, Rossana; Levine, Myron; Prado, Valeria

    2004-01-01

    A multiplex PCR for detection of three categories of diarrheagenic Escherichia coli was developed. With this method, enterohemorrhagic E. coli, enteropathogenic E. coli, and enterotoxigenic E. coli were identified in fecal samples from patients with hemorrhagic colitis, watery diarrhea, or hemolytic-uremic syndrome and from food-borne outbreaks. PMID:15071051

  9. Diarrhea, Urosepsis and Hemolytic Uremic Syndrome Caused by the Same Heteropathogenic Escherichia coli Strain.

    Science.gov (United States)

    Ang, C Wim; Bouts, Antonia H M; Rossen, John W A; Van der Kuip, Martijn; Van Heerde, Marc; Bökenkamp, Arend

    2016-09-01

    We describe an 8-month-old girl with diarrhea, urosepsis and hemolytic uremic syndrome caused by Escherichia coli. Typing of cultured E. coli strains from urine and blood revealed the presence of virulence factors from multiple pathotypes of E. coli. This case exemplifies the genome plasticity of E. coli and the resulting heteropathogenic strains.

  10. A putative, novel coli surface antigen 8B (CS8B) of enterotoxigenic Escherichia coli.

    Science.gov (United States)

    Njoroge, Samuel M; Boinett, Christine J; Madé, Laure F; Ouko, Tom T; Fèvre, Eric M; Thomson, Nicholas R; Kariuki, Samuel

    2015-10-01

    Enterotoxigenic Escherichia coli (ETEC) strains harbor multiple fimbriae and pili to mediate host colonization, including the type IVb pilus, colonization factor antigen III (CFA/III). Not all colonization factors are well characterized or known in toxin positive ETEC isolates, which may have an impact identifying ETEC isolates based on molecular screening of these biomarkers. We describe a novel coli surface antigen (CS) 8 subtype B (CS8B), a family of CFA/III pilus, in a toxin producing ETEC isolate from a Kenyan collection. In highlighting the existence of this putative CS, we provide the sequence and specific primers, which can be used alongside other ETEC primers previously described.

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

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, R.; Schalen, C.; Tranberg, K.G. (Department of Surgery, Lund University, Lund (Sweden))

    1991-06-01

    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.

  12. Posttranslational Modifications of Ribosomal Proteins in Escherichia coli.

    Science.gov (United States)

    Nesterchuk, M V; Sergiev, P V; Dontsova, O A

    2011-04-01

    А number of ribosomal proteins inEscherichia coliundergo posttranslational modifications. Six ribosomal proteins are methylated (S11, L3, L11, L7/L12, L16, and L33), three proteins are acetylated (S5, S18, and L7), and protein S12 is methylthiolated. Extra amino acid residues are added to protein S6. С-terminal amino acid residues are partially removed from protein L31. The functional significance of these modifications has remained unclear. These modifications are not vital to the cells, and it is likely that they have regulatory functions. This paper reviews all the known posttranslational modifications of ribosomal proteins inEscherichia coli. Certain enzymes responsible for the modifications and mechanisms of enzymatic reactions are also discussed.

  13. RNase III-Independent Autogenous Regulation of Escherichia coli Polynucleotide Phosphorylase via Translational Repression

    OpenAIRE

    Carzaniga, T.; Dehò, G; Briani, F.

    2015-01-01

    The complex posttranscriptional regulation mechanism of the Escherichia coli pnp gene, which encodes the phosphorolytic exoribonuclease polynucleotide phosphorylase (PNPase), involves two endoribonucleases, namely, RNase III and RNase E, and PNPase itself, which thus autoregulates its own expression. The models proposed for pnp autoregulation posit that the target of PNPase is a mature pnp mRNA previously processed at its 5′ end by RNase III, rather than the primary pnp transcript (RNase I...

  14. Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus

    OpenAIRE

    2008-01-01

    Chitosan has been reported to be a non-toxic, biodegradable antibacterial agent. The aim of this work was to elucidate the relationship between the molecular weight of chitosan and its antimicrobial activity upon two model microorganisms, one Gram-positive (Staphylococcus aureus) and one Gramnegative (Escherichia coli). Atomic force microscopy (AFM) imaging was used to obtain high-resolution images of the effect of chitosans on the bacterial morphology. The AFM measurements were correlated...

  15. The Genome-Wide Interaction Network of Nutrient Stress Genes in Escherichia coli

    OpenAIRE

    Jean-Philippe Côtôé; Shawn French; Gehrke, Sebastian S.; MacNair, Craig R.; Mangat, Chand S.; Amrita Bharat; Brown, Eric D.

    2016-01-01

    ABSTRACT Conventional efforts to describe essential genes in bacteria have typically emphasized nutrient-rich growth conditions. Of note, however, are the set of genes that become essential when bacteria are grown under nutrient stress. For example, more than 100 genes become indispensable when the model bacterium Escherichia coli is grown on nutrient-limited media, and many of these nutrient stress genes have also been shown to be important for the growth of various bacterial pathogens in vi...

  16. The morphogenetic MreBCD proteins of Escherichia coli form an essential membrane-bound complex

    DEFF Research Database (Denmark)

    Kruse, Thomas; Bork-Jensen, Jette; Gerdes, Kenn

    2005-01-01

    MreB proteins of Escherichia coli, Bacillus subtilis and Caulobacter crescentus form actin-like cables lying beneath the cell surface. The cables are required to guide longitudinal cell wall synthesis and their absence leads to merodiploid spherical and inflated cells prone to cell lysis. In B...... on these and other observations we propose a model in which the membrane-associated MreBCD complex directs longitudinal cell wall synthesis in a process essential to maintain cell morphology....

  17. CRISPR adaptation in Escherichia coli subtypeI-E system.

    Science.gov (United States)

    Kiro, Ruth; Goren, Moran G; Yosef, Ido; Qimron, Udi

    2013-12-01

    The CRISPRs (clustered regularly interspaced short palindromic repeats) and their associated Cas (CRISPR-associated) proteins are a prokaryotic adaptive defence system against foreign nucleic acids. The CRISPR array comprises short repeats flanking short segments, called 'spacers', which are derived from foreign nucleic acids. The process of spacer insertion into the CRISPR array is termed 'adaptation'. Adaptation allows the system to rapidly evolve against emerging threats. In the present article, we review the most recent studies on the adaptation process, and focus primarily on the subtype I-E CRISPR-Cas system of Escherichia coli.

  18. Composition of cardiolipin molecular species in Escherichia coli.

    OpenAIRE

    Yokota, K; Kanamoto, R.; Kito, M

    1980-01-01

    The composition of the molecular species of acidic phospholipids in Escherichia coli B during the late exponential growth phase at 37 degrees C was determined. Two phosphatidyl groups of cardiolipin, the 3-(3-sn-phosphatidyl) and 1-(3-sn-phosphatidyl) moieties of cardiolipin, were isolated by limited hydrolysis with phospholipase C. No significant difference in the composition of the molecular species was found between the 3-(3-sn-phosphatidyl) and 1-(3-sn-phosphatidyl) moieties. On the other...

  19. Pengujian Bakteri Escherichia Coli Pada Air Sumur Di Medan Johor

    OpenAIRE

    Mahardhika, Diah

    2013-01-01

    Water is an essential material in life. Water is a means to improve public health. The spread of water borne diseases can be. Water pollution can be caused due to the entry of human and animal waste, but it can also be caused directly or through a leak or where ground soil cracks. This test aims to determine the number most likely Most Probable Number (MPN) Escherichia coli bacteria that contaminate well water located in Medan Johor still meet water quality requirements or not. The samplin...

  20. Modulation of allele leakiness and adaptive mutability in Escherichia coli

    Indian Academy of Sciences (India)

    R. Jayaraman

    2000-08-01

    It is shown that partial phenotypic suppression of two ochre mutations (argE3 and lacZU118) and an amber mutation (in argE) by sublethal concentrations of streptomycin in an rpsL+ (streptomycin-sensitive) derivative of the Escherichia coli strain AB1157 greatly enhances their adaptive mutability under selection. Streptomycin also increases adaptive mutability brought about by the ppm mutation described earlier. Inactivation of recA affects neither phenotypic suppression by streptomycin nor replication-associated mutagenesis but abolishes adaptive mutagenesis. These results indicate a causal relationship between allele leakiness and adaptive mutability.

  1. Precursor for elongation factor Tu from Escherichia coli.

    OpenAIRE

    1986-01-01

    The tufA gene, one of two genes in Escherichia coli encoding elongation factor Tu (EF-Tu), was cloned into a ColE1-derived plasmid downstream of the lac promoter-operator. In cells carrying this plasmid, the synthesis of EF-Tu was increased four- to fivefold upon the addition of isopropyl-beta-D-thiogalactopyranoside (an inducer of the lac promoter). This condition led to the synthesis of a novel protein, called pTu, which comigrated with EF-Tu on a sodium dodecyl sulfate-polyacrylamide gel b...

  2. Interactions between Phage-Shock Proteins in Escherichia coli

    OpenAIRE

    Adams, Hendrik; Teertstra, Wieke; Demmers, Jeroen; Boesten, Rolf; Tommassen, Jan

    2003-01-01

    Expression of the pspABCDE operon of Escherichia coli is induced upon infection by filamentous phage and by many other stress conditions, including defects in protein export. Expression of the operon requires the alternative sigma factor σ54 and the transcriptional activator PspF. In addition, PspA plays a negative regulatory role, and the integral-membrane proteins PspB and PspC play a positive one. In this study, we investigated whether the suggested protein-protein interactions implicated ...

  3. PspA can form large scaffolds in Escherichia coli.

    Science.gov (United States)

    Standar, Kerstin; Mehner, Denise; Osadnik, Hendrik; Berthelmann, Felix; Hause, Gerd; Lünsdorf, Heinrich; Brüser, Thomas

    2008-10-29

    The phage shock protein A (PspA) of Escherichia coli stabilizes the cytoplasmic membrane under stress conditions. Here we demonstrate that PspA can form hollow spherical or prolate spheroidal particles of about 30-40nm diameter with a scaffold-like arrangement of protein subunits at the surface. The 'PspA-scaffold' is the basic structure that is common to all particles. The PspA-scaffold may be of fundamental importance, as it could allow PspA to stabilize the integrity of membranes through numerous contact points over a large surface area.

  4. PspA can form large scaffolds in Escherichia coli.

    OpenAIRE

    Standar, Kerstin; Mehner, Denise; Osadnik, Hendrik; Berthelmann, Felix; Hause, Gerd; Lünsdorf, Heinrich; Brüser, Thomas

    2008-01-01

    The phage shock protein A (PspA) of Escherichia coli stabilizes the cytoplasmic membrane under stress conditions. Here we demonstrate that PspA can form hollow spherical or prolate spheroidal particles of about 30-40nm diameter with a scaffold-like arrangement of protein subunits at the surface. The 'PspA-scaffold' is the basic structure that is common to all particles. The PspA-scaffold may be of fundamental importance, as it could allow PspA to stabilize the integrity of membranes through n...

  5. Isolation and mapping of phosphotransferase mutants in Escherichia coli.

    Science.gov (United States)

    Epstein, W; Jewett, S; Fox, C F

    1970-11-01

    Mutants of Escherichia coli K-12 defective in enzyme I or Hpr, the two common components of the phosphoenolpyruvate-dependent phosphotransferase system, were isolated by a simple, direct method. The ptsI locus, the structural gene for enzyme I, and the ptsH locus, the site of mutations leading to loss of Hpr activity, are adjacent genes and could be part of a single operon. These two genes lie between the purC and supN markers in the order: strA... guaB-purC-ptsI-ptsH-supN-dsdA... his.

  6. Penicillin-binding site on the Escherichia coli cell envelope.

    OpenAIRE

    Amaral, L; Lee, Y.; Schwarz, U.; Lorian, V

    1986-01-01

    The binding of 35S-labeled penicillin to distinct penicillin-binding proteins (PBPs) of the "cell envelope" obtained from the sonication of Escherichia coli was studied at different pHs ranging from 4 to 11. At low pH, PBPs 1b, 1c, 2, and 3 demonstrated the greatest amount of binding. At high pH, these PBPs bound the least amount of penicillin. PBPs 1a and 5/6 exhibited the greatest amount of binding at pH 10 and the least amount at pH 4. With the exception of PBP 5/6, the effect of pH on the...

  7. [Hemolytic uremic syndrome caused by enterohaemorrhagic Escherichia coli].

    Science.gov (United States)

    Ibarra, Cristina; Goldstein, Jorge; Silberstein, Claudia; Zotta, Elsa; Belardo, Marcela; Repetto, Horacio A

    2008-10-01

    Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolytic anemia, plaquetopenia and kidney damage. It is the leading cause of acute renal failure in pediatric age and the second for chronic renal failure. Shiga toxin-producing Escherichia coli (STEC) is the first etiologic agent of HUS being its main reservoir cattle and transmitted via contaminated food. At present, there is no specific treatment to reduce the progression of HUS. The study of the mechanisms by which STEC infects and Shiga toxin induces HUS can help to find new strategies to prevent this disease.

  8. Resistencia a biocidas de diferentes cepas de escherichia coli

    OpenAIRE

    López Aguayo, M. Carmen; Grande Burgos, M. José; Lucas López, R.; Gálvez-del-Postigo-Ruiz, Antonio

    2010-01-01

    Los biocidas son herramientas de gran importancia para controlar la transmisión de microorganismos patógenos a través de la cadena alimentaria. En el presente estudio se ha determinado la resistencia a siete biocidas en una colección de nueve cepas de Escherichia coli, incluyendo cepas verotoxigénicas y cepas portadoras de resistencia a beta-lactámicos. Los biocidas más eficaces fueron triclosan, hexadecilpiridinio y cetrimida, seguido del cloruro de benzalconio. No se encon...

  9. Genome-scale genetic engineering in Escherichia coli.

    Science.gov (United States)

    Jeong, Jaehwan; Cho, Namjin; Jung, Daehee; Bang, Duhee

    2013-11-01

    Genome engineering has been developed to create useful strains for biological studies and industrial uses. However, a continuous challenge remained in the field: technical limitations in high-throughput screening and precise manipulation of strains. Today, technical improvements have made genome engineering more rapid and efficient. This review introduces recent advances in genome engineering technologies applied to Escherichia coli as well as multiplex automated genome engineering (MAGE), a recent technique proposed as a powerful toolkit due to its straightforward process, rapid experimental procedures, and highly efficient properties.

  10. 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......, reservoirs, and symptoms. Manifestations associated with EAEC infection include watery diarrhea, mucoid diarrhea, low-grade fever, nausea, tenesmus, and borborygmi. In early studies, EAEC was considered to be an opportunistic pathogen associated with diarrhea in HIV patients and in malnourished children...... in developing countries. In recent studies, associations with traveler's diarrhea, the occurrence of diarrhea cases in industrialized countries, and outbreaks of diarrhea in Europe and Asia have been reported. In the spring of 2011, a large outbreak of hemolytic-uremic syndrome (HUS) and hemorrhagic colitis...

  11. Production and purification of active snowdrop lectin in Escherichia coli.

    Science.gov (United States)

    Longstaff, M; Powell, K S; Gatehouse, J A; Raemaekers, R; Newell, C A; Hamilton, W D

    1998-02-15

    Recombinant snowdrop lectin was produced in Escherichia coli from a cDNA clone encoding mature Galanthus nivalis agglutinin. After induction with isopropylthio-beta-D-galactoside, inclusion bodies from E. coli were solubilised and the G. nivalis agglutinin purified by metal-affinity chromatography using a carboxy-terminal hexahistidine tag. The protein was refolded on the metal-affinity column prior to elution. After purification, the recombinant G. nivalis agglutinin agglutinated rabbit erythrocytes to a dilution similar to that determined for 'native' lectin purified from snowdrop, and showed similar specific binding to mannose. The toxicity of the recombinant G. nivalis agglutinin towards rice brown planthopper (Nilaparvata lugens) was shown to be similar to that of 'native' G. nivalis agglutinin when incorporated into an artificial diet. The recombinant G. nivalis agglutinin is thus functionally similar to 'native' snowdrop lectin.

  12. Probability of recovering pathogenic Escherichia coli from foods.

    Science.gov (United States)

    Hill, W E; Ferreira, J L; Payne, W L; Jones, V M

    1985-01-01

    The probability of recovering pathogenic Escherichia coli from food by the Bacteriological Analytical Manual method was determined by the effects of several factors: the number of strains per food, the ability of pathogenic strains to survive enrichment, and the frequency of plasmid loss during enrichment. Biochemical patterns indicated the presence of about six E. coli strains per food sample. About half of the strains isolated from humans did not survive enrichment. Among those which grew, plasmid loss, as determined by gel electrophoresis and DNA colony hybridization, ranged from 20 to 95%. The combined effects of failure to survive enrichment and plasmid loss decreased the relative numbers of these strains and reduced the chance of detecting pathogens. To counteract this tendency and obtain a 90 to 95% probability off recovering a given pathogenic strain, 40 to 50 colonies per food sample should be picked during the routine testing of foods. PMID:3893320

  13. Bleomycin sensitivity in Escherichia coli is medium-dependent.

    Directory of Open Access Journals (Sweden)

    Tao Xu

    Full Text Available Bleomycin (BLM is a glycopeptide antibiotic and anti-tumor agent that targets primarily the furanose rings of DNA and in the presence of ferrous ions produces oxidative damage and DNA strand breaks. Escherichia coli cells growing in broth medium and exposed to low concentrations of BLM contain double-strand breaks and require homologous recombination to survive. To a lesser extent, the cells also require the abasic (AP endonucleases associated with base excision repair, presumably to repair oxidative damage. As expected, there is strong induction of the SOS system in treated cells. In contrast, E. coli cells growing in glucose or glycerol minimal medium are resistant to the lethal action of BLM and do not require either homologous recombination functions or AP-endonucleases for survival. DNA ligase activity, however, is needed for cells growing in minimal medium to resist the lethal effects of BLM. There is weak SOS induction in such treated cells.

  14. Rotational tumbling of Escherichia coli aggregates under shear

    CERN Document Server

    Portela, R; Almeida, P L; Sobral, R G; Franco, J M; Leal, C R

    2016-01-01

    Growing living cultures of Escherichia coli bacteria were investigated using real-time in situ rheology and rheo-imaging measurements. In the early stages of growth (lag phase), and when subjected to a constant stationary shear, the viscosity slowly increases with the cell's population. As the bacteria reach the exponential phase of growth, the viscosity increases rapidly, with sudden and temporary abrupt decreases and recoveries. At a certain stage, corresponding grossly to the late phase of growth, when the population stabilises, the viscosity also keeps its maximum constant value, with drops and recoveries, for a long period of time. This complex rheological behaviour, which was observed to be shear strain dependent, is a consequence of two coupled effects: the cell density continuous increase and its changing interacting properties. Particular attention was given to the late phase of growth of E. coli populations under shear. Rheo-imaging measurements revealed, near the static plate, a rotational motion o...

  15. In Vivo study of naturally deformed Escherichia coli bacteria.

    Science.gov (United States)

    Tavaddod, Sharareh; Naderi-Manesh, Hossein

    2016-06-01

    A combination of light-microscopy and image processing has been applied to study naturally deformed Escherichia coli under in vivo condition and at the order of sub-pixel high-resolution accuracy. To classify deflagellated non-dividing E. coli cells to the rod-shape and bent-shape, a geometrical approach has been applied. From the analysis of the geometrical data which were obtained of image processing, we estimated the required effective energy for shaping a rod-shape to a bent-shape with the same size. We evaluated the energy of deformation in the naturally deformed bacteria with minimum cell manipulation, under in vivo condition, and with minimum influence of any external force, torque and pressure. Finally, we have also elaborated on the possible scenario to explain how naturally deformed bacteria are formed from initial to final-stage.

  16. Engineering Escherichia coli for improved ethanol production from gluconate.

    Science.gov (United States)

    Hildebrand, Amanda; Schlacta, Theresa; Warmack, Rebeccah; Kasuga, Takao; Fan, Zhiliang

    2013-10-10

    We report on engineering Escherichia coli to produce ethanol at high yield from gluconic acid (gluconate). Knocking out genes encoding for the competing pathways (l-lactate dehydrogenase and pyruvate formate lyase A) in E. coli KO11 eliminated lactate production, lowered the carbon flow toward acetate production, and improved the ethanol yield from 87.5% to 97.5% of the theoretical maximum, while the growth rate of the mutant strain was about 70% of the wild type. The corresponding genetic modifications led to a small improvement of ethanol yield from 101.5% to 106.0% on glucose. Deletion of the pyruvate dehydrogenase gene (pdh) alone improved the ethanol yield from 87.5% to 90.4% when gluconate was a substrate. The growth rate of the mutant strain was identical to that of the wild type. The corresponding genetic modification led to no improvements on ethanol yield on glucose.

  17. Metabolite essentiality elucidates robustness of Escherichia coli metabolism

    CERN Document Server

    Kim, Pan-Jun; Kim, Tae Yong; Lee, Kwang Ho; Jeong, Hawoong; Lee, Sang Yup; Park, Sunwon

    2007-01-01

    Complex biological systems are very robust to genetic and environmental changes at all levels of organization. Many biological functions of Escherichia coli metabolism can be sustained against single-gene or even multiple-gene mutations by using redundant or alternative pathways. Thus, only a limited number of genes have been identified to be lethal to the cell. In this regard, the reaction-centric gene deletion study has a limitation in understanding the metabolic robustness. Here, we report the use of flux-sum, which is the summation of all incoming or outgoing fluxes around a particular metabolite under pseudo-steady state conditions, as a good conserved property for elucidating such robustness of E. coli from the metabolite point of view. The functional behavior, as well as the structural and evolutionary properties of metabolites essential to the cell survival, was investigated by means of a constraints-based flux analysis under perturbed conditions. The essential metabolites are capable of maintaining a...

  18. SILVER NANOPARTICLES-DISK DIFFUSION TEST AGAINST Escherichia coli ISOLATES

    Science.gov (United States)

    CUNHA, Francisco Afrânio; MAIA, Kamila Rocha; MALLMAN, Eduardo José Jucá; CUNHA, Maria da Conceição dos Santos Oliveira; MACIEL, Antonio Auberson Martins; de SOUZA, Ieda Pereira; MENEZES, Everardo Albuquerque; FECHINE, Pierre Basílio Almeida

    2016-01-01

    SUMMARY Nanotechnology can be a valuable ally in the treatment of infections. Silver nanoparticles (AgNPs) are structures that have antimicrobial activity. The aim of this study was to produce AgNPs by green methods, characterize these structures, and assess their antimicrobial activity against Escherichia coli associated with the antibiotic ciprofloxacin. AgNPs were characterized by spectroscopic and microscopic techniques. Antimicrobial activity was evaluated by the disk diffusion method against 10 strains of E. coli. The synthesized AgNPs showed a spherical shape and a size of 85.07 ± 12.86 nm (mean ± SD). AgNPs increased the activity of ciprofloxacin by 40% and may represent a new therapeutic option for the treatment of bacterial infections. PMID:27680178

  19. The action of beta-galactosidase (Escherichia coli) on allolactose.

    Science.gov (United States)

    Huber, R E; Wallenfels, K; Kurz, G

    1975-09-01

    The parameters involved in the action of beta-galactosidase (EC 3.2.1.23) (Escherichia coli) on allolactose, the natural inducer of lac operon in E. coli, were studied. At low allolactose concentrations only galactose and glucose were formed, while at high allolactose concentrations transgalactolytic oligosaccharides were also produced. Detectable amounts of lactose were not formed. The V and Km values (49.6 U/mg and 0.00120 M, respectively) indicated that allolactose is as good if not a better substrate of beta-galactosidase as lactose. The pH optimum with allolactose (7.8-7.9) as well as its activation by K+ (as compared to activation by Na+) were similar to the case with lactose as substrate. The alpha-anomer of allolactose was hydrolyzed about two times as rapidly as was the beta-anomer.

  20. Mutational analysis of UMP kinase from Escherichia coli.

    Science.gov (United States)

    Bucurenci, N; Serina, L; Zaharia, C; Landais, S; Danchin, A; Bârzu, O

    1998-02-01

    UMP kinase from Escherichia coli is one of the four regulatory enzymes involved in the de novo biosynthetic pathway of pyrimidine nucleotides. This homohexamer, with no counterpart in eukarya, might serve as a target for new antibacterial drugs. Although the bacterial enzyme does not show sequence similarity with any other known nucleoside monophosphate kinase, two segments between amino acids 35 to 78 and 145 to 194 exhibit 28% identity with phosphoglycerate kinase and 30% identity with aspartokinase, respectively. Based on these similarities, a number of residues of E. coli UMP kinase were selected for site-directed mutagenesis experiments. Biochemical, kinetic, and spectroscopic analysis of the modified proteins identified residues essential for catalysis (Asp146), binding of UMP (Asp174), and interaction with the allosteric effectors, GTP and UTP (Arg62 and Asp77).