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Sample records for bioluminescent escherichia coli

  1. Metabolic self-organization of bioluminescent Escherichia coli.

    PubMed

    Simkus, Remigijus; Baronas, Romas

    2011-01-01

    A possible reason for the complexity of the signals produced by bioluminescent biosensors might be self-organization of the cells. In order to verify this possibility, bioluminescence images of cultures of lux gene reporter Escherichia coli were recorded for several hours after being placed into 8-10 mm diameter cylindrical containers. It was found that luminous cells distribute near the three-phase contact line, forming irregular azimuthal waves. As we show, space-time plots of quasi-one-dimensional bioluminescence measured along the contact line can be simulated by reaction-diffusion-chemotaxis equations, in which the reaction term for the cells is a logistic (autocatalytic) growth function. It was found that the growth rate of the luminous cells (~0.02 s(-1)) is >100 times higher than the growth rate of E. coli. We provide an explanation for this result by assuming that E. coli exhibits considerable respiratory flexibility (the ability of oxygen-induced switching from one metabolic pathway to another). According to the simple two-state model presented here, the number of oxic (luminous) cells grows at the expense of anoxic (dark) cells, whereas the total number of (oxic and anoxic) cells remains unchanged. It is conjectured that the corresponding reaction-diffusion-chemotaxis model for bioluminescence pattern formation can be considered as a model for the energy-taxis and metabolic self-organization in the population of the metabolically flexible bacteria under hypoxic conditions. PMID:21538795

  2. Antioxidant assay using genetically engineered bioluminescent Escherichia coli

    NASA Astrophysics Data System (ADS)

    Bartolome, Amelita; Macalino, Bernadette; Pastoral, Ian Lemuel; Sevilla, Fortunato, III

    2006-02-01

    A new antioxidant activity assay based on the reactive oxygen species (ROS)-inducible bacterial strain (E. coli DPD2511) is described. The strain harbors the plasmid pKatG::luxCDABE and responds to hydrogen peroxide treatment by increasing light emission at 490 nm. Antioxidant capacity is evaluated through the ability of an agent to inhibit the hydrogen peroxide-induced bioluminescence of E. coli DPD2511. Applicability of the developed assay in detecting levels of antioxidants in various aqueous plant extracts is demonstrated. The assay was validated against 2,2-diphenylpicrylhydrazyl (DPPH) assay, a known antioxidant assay.

  3. Multiplexed amino acid array utilizing bioluminescent Escherichia coli auxotrophs.

    PubMed

    Kim, Moon Il; Yu, Byung Jo; Woo, Min-Ah; Cho, Daeyeon; Dordick, Jonathan S; Cho, June Hyoung; Choi, Byung-Ok; Park, Hyun Gyu

    2010-05-15

    We describe a novel multiplex "amino acid array" for simultaneously quantifying different amino acids based on the rapid growth of amino acid auxotrophic E. coli. First, we constructed genetically engineered amino acid auxotrophs of E. coli containing a bioluminescence reporter gene, yielding concomitant luminescence as a response to cell growth, and then immobilized the reporter cells within individual agarose of respective wells in a 96-well plate serving as a mimic of a biochip. Using the amino acid array, we were able to determine quantitatively the concentrations of 16 amino acids in biological fluid by simply measuring bioluminescent signals from the immobilized cells within 4 h without pre- and post-treatment. The clinical utility of this method was verified by quantifying different amino acids in dried blood spot specimens from clinical samples for the diagnosis of metabolic diseases of newborn babies. This method serves as a convenient route to the rapid and simultaneous analysis of multiple amino acids from complex biological fluids and represents a new analytical paradigm that can replace conventional, yet laborious methods currently in use. PMID:20405822

  4. Effect of cosmic-ray shielding on the ultraweak bioluminescence emitted by cultures of Escherichia coli

    SciTech Connect

    Tilbury, R.N.; Quickenden, T.I.

    1987-11-01

    Neither the growth of Escherichia coli nor its associated luminescence was significantly affected when cultures were shielded from the soft component of cosmic rays. The study included experiments in which the cultures were shielded intermittently during their two periods of luminescence emission and experiments in which the cultures were continuously shielded throughout their entire growth cycle. These results do not support previous suggestions that the ultraweak bioluminescences from living organisms might be cosmic-ray-excited fluorescences induced in certain biological molecules synthesized during the various stages of growth.

  5. Escherichia coli (E. coli)

    MedlinePLUS

    ... Asked Questions Expand All Collapse All What are Escherichia coli ? Escherichia coli (abbreviated as E. coli ) are a large and ... When you hear news reports about outbreaks of “ E. coli ” infections, they are usually talking about E. coli O157. ...

  6. Biological toxicity of cellulose nanocrystals (CNCs) against the luxCDABE-based bioluminescent bioreporter Escherichia coli 652T7.

    PubMed

    Du, Liyu; Arnholt, Kelly; Ripp, Steven; Sayler, Gary; Wang, Siqun; Liang, Chenghua; Wang, Jingkuan; Zhuang, Jie

    2015-12-01

    The aim of this study was to evaluate the biological toxicity of cellulose nanocrystals (CNCs) using the constitutively bioluminescent luxCDABE-based bioreporter Escherichia coli 652T7. The effects of CNCs on E. c oli 652T7 biotoxicity were investigated at different CNC concentrations, reaction times, and IC50 values. CNC toxicity was also compared with and without ultrasonic dispersion to establish dispersibility effects. The results demonstrated that CNCs were not significantly toxic at concentrations at or below 250 mg/L. At concentrations higher than 300 mg/L, toxicity increased linearly as CNC concentrations increased up to 2000 mg/L. IC50 calculations demonstrated an increase in cytotoxicity as CNC exposure times increased, and elevated dispersibility of the CNCs were shown to increase cytotoxicity effects. These results suggest that CNCs can impact microbial populations if elevated concentration thresholds are met. PMID:26419245

  7. Stress-activated bioluminescent Escherichia coli sensors for antimicrobial agents detection.

    PubMed

    Shapiro, Elyse; Baneyx, François

    2007-12-01

    A DNA cartridge encoding Photinus pyralis luciferase (luc), lacZ homology extensions and an excisable marker was constructed to facilitate the conversion of Escherichia coli lacZ fusions to luc fusions by lambda Red-mediated recombination. This tool was used to transform a cspA::lacZ strain into a luminescent biosensor for C-group translational inhibitors. Comparison of cspA::lacZ and cspA::luc cells showed native firefly luciferase to be a more rapid and sensitive reporter than beta-galactosidase for chloramphenicol detection. To evaluate the usefulness of a red-shifted variant of P. pyralis luciferase (LucR1) for biosensor development, a single copy translational fusion between the SOS-inducible sulA promoter and the lucR1 gene was inserted at the malP site of the E. coli chromosome. The sulA::lucR1 fusion allowed high signal detection of the quinolone ofloxacin to levels as low as 15% of the minimum inhibitory concentration and could be combined with a cspA::lacZ fusion to yield a biosensor suitable for the independent and dual detection of chloramphenicol and ofloxacin. PMID:17897748

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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....

  9. Escherichia Coli

    ERIC Educational Resources Information Center

    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…

  10. Bioluminescent Imaging Reveals Novel Patterns of Colonization and Invasion in Systemic Escherichia coli K1 Experimental Infection in the Neonatal Rat.

    PubMed

    Witcomb, Luci A; Collins, James W; McCarthy, Alex J; Frankel, Gadi; Taylor, Peter W

    2015-12-01

    Key features of Escherichia coli K1-mediated neonatal sepsis and meningitis, such as a strong age dependency and development along the gut-mesentery-blood-brain course of infection, can be replicated in the newborn rat. We examined temporal and spatial aspects of E. coli K1 infection following initiation of gastrointestinal colonization in 2-day-old (P2) rats after oral administration of E. coli K1 strain A192PP and a virulent bioluminescent derivative, E. coli A192PP-lux2. A combination of bacterial enumeration in the major organs, two-dimensional bioluminescence imaging, and three-dimensional diffuse light imaging tomography with integrated micro-computed tomography indicated multiple sites of colonization within the alimentary canal; these included the tongue, esophagus, and stomach in addition to the small intestine and colon. After invasion of the blood compartment, the bacteria entered the central nervous system, with restricted colonization of the brain, and also invaded the major organs, in line with increases in the severity of symptoms of infection. Both keratinized and nonkeratinized surfaces of esophagi were colonized to a considerably greater extent in susceptible P2 neonates than in corresponding tissues from infection-resistant 9-day-old rat pups; the bacteria appeared to damage and penetrate the nonkeratinized esophageal epithelium of infection-susceptible P2 animals, suggesting the esophagus represents a portal of entry for E. coli K1 into the systemic circulation. Thus, multimodality imaging of experimental systemic infections in real time indicates complex dynamic patterns of colonization and dissemination that provide new insights into the E. coli K1 infection of the neonatal rat. PMID:26351276

  11. Diarrheagenic Escherichia coli

    PubMed Central

    Nataro, James P.; Kaper, James B.

    1998-01-01

    Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler’s diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (enteropathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens. PMID:9457432

  12. PATHOGENIC ESCHERICHIA COLI

    EPA Science Inventory

    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...

  13. Escherichia coli biofilms

    PubMed Central

    Beloin, Christophe; Roux, Agnès; Ghigo, Jean-Marc

    2008-01-01

    Escherichia coli is a predominant species among facultative anaerobic bacteria of the gastrointestinal tract. Both its frequent community lifestyle and the availability of a wide array of genetic tools contributed to establish E. coli as a relevant model organism for the study of surface colonization. Several key factors, including different extracellular appendages, are implicated in E. coli surface colonization and their expression and activity are finely regulated, both in space and time, to ensure productive events leading to mature biofilm formation. This chapter will present known molecular mechanisms underlying biofilm development in both commensal and pathogenic E. coli. PMID:18453280

  14. 76 FR 20542 - Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ... AGENCY 40 CFR Part 180 Escherichia coli O157:H7 Specific Bacteriophages; Temporary Exemption From the... bacteriophages that are specific to Escherichia coli O157:H7, sequence negative for shiga toxins I and II, and... residues of lytic bacteriophages that are specific to Escherichia coli O157:H7, sequence negative for...

  15. Genetic recombination. [Escherichia coli

    SciTech Connect

    Stahl, F.W.

    1987-02-01

    The molecular pathways of gene recombination are explored and compared in studies of the model organisms, Escherichia coli and phase lambda. In the discussion of data from these studies it seems that recombination varies with the genetic idiosyncrasies of the organism and may also vary within a single organism.

  16. Escherichia coli virulence factors.

    PubMed

    Mainil, Jacques

    2013-03-15

    Escherichia coli was described in 1885 by a German pediatrician, Theodor Escherich, in the faeces of a child suffering diarrhoea. In 1893, a Danish veterinarian postulated that the E. coli species comprises different strains, some being pathogens, others not. Today the E. coli species is subdivided into several pathogenic strains causing different intestinal, urinary tract or internal infections and pathologies, in animal species and in humans. Since this congress topic is the interaction between E. coli and the mucosal immune system, the purpose of this manuscript is to present different classes of adhesins (fimbrial adhesins, afimbrial adhesins and outer membrane proteins), the type 3 secretion system, and some toxins (oligopeptide, AB, and RTX pore-forming toxins) produced by E. coli, that can directly interact with the epithelial cells of the intestinal, respiratory and urinary tracts. PMID:23083938

  17. PATHOGENIC ESCHERICHIA COLI IN FOODS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pathogenic Escherichia coli are defined as those E. coli strains that are capable of causing diarrhoeal disease in humans. Subdivision of the pathogenic forms is made on the basis of the mechanism underlying the illness. Presently, four types of pathogenic E. coli have been implicated in foodborne...

  18. Enterohemorrhagic Escherichia coli Adhesins.

    PubMed

    McWilliams, Brian D; Torres, Alfredo G

    2014-06-01

    Adhesins are a group of proteins in enterohemorrhagic Escherichia coli (EHEC) that are involved in the attachment or colonization of this pathogen to abiotic (plastic or steel) and biological surfaces, such as those found in bovine and human intestines. This review provides the most up-to-date information on these essential adhesion factors, summarizing important historical discoveries and analyzing the current and future state of this research. In doing so, the proteins intimin and Tir are discussed in depth, especially regarding their role in the development of attaching and effacing lesions and in EHEC virulence. Further, a series of fimbrial proteins (Lpf1, Lpf2, curli, ECP, F9, ELF, Sfp, HCP, and type 1 fimbria) are also described, emphasizing their various contributions to adherence and colonization of different surfaces and their potential use as genetic markers in detection and classification of different EHEC serotypes. This review also discusses the role of several autotransporter proteins (EhaA-D, EspP, Saa and Sab, and Cah), as well as other proteins associated with adherence, such as flagella, EibG, Iha, and OmpA. While these proteins have all been studied to varying degrees, all of the adhesins summarized in this article have been linked to different stages of the EHEC life cycle, making them good targets for the development of more effective diagnostics and therapeutics. PMID:26103974

  19. ORIGINAL ARTICLE Competitive interactions in Escherichia coli

    E-print Network

    Riley, Margaret

    ORIGINAL ARTICLE Competitive interactions in Escherichia coli populations: the role of bacteriocins Escherichia coli strains were generated, each carrying a DNA-degrading bacteriocin (colicins E2 and E7). Using exclusion; Escherichia coli; bacteriocin; structured environment Introduction Without question, bacteriocins

  20. EXTRAINTESTINAL PATHOGENIC ESCHERICHIA COLI (EXPEC)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extraintestinal pathogenic Escherichia coli (ExPEC) possess virulence traits that allow them to invade, colonize, and induce disease in bodily sites outside of the gastrointestinal tract. Human diseases caused by ExPEC include urinary tract infections, neonatal meningitis, sepsis, pneumonia, surgic...

  1. ORIGINAL RESEARCH Shigella Strains Are Not Clones of Escherichia coli

    E-print Network

    Hao, Bailin

    ORIGINAL RESEARCH Shigella Strains Are Not Clones of Escherichia coli but Sister Species Available online 29 December 2012 KEYWORDS Shigella; Escherichia coli; Prokaryote phylogeny and taxonomy; Composition vector; CVTree Abstract Shigella species and Escherichia coli are closely related organisms. Early

  2. The Escherichia coli Peripheral Inner Membrane Proteome*S

    E-print Network

    Economou, Tassos

    The Escherichia coli Peripheral Inner Membrane Proteome*S Malvina Papanastasiou, Georgia Escherichia coli using a multidisciplinary approach. Initially, we extensively re-an- notated the theoretical- romolecular complexes, and modification and degradation of poplypeptides. Escherichia coli, a model organism

  3. GENOMICS AND PROTEOMICS Temporal regulation of enterohemorrhagic Escherichia coli

    E-print Network

    Wood, Thomas K.

    GENOMICS AND PROTEOMICS Temporal regulation of enterohemorrhagic Escherichia coli virulence Escherichia coli (EHEC) infections. AI-2 attracted EHEC in agarose plug chemotaxis assays and also increased). However, the introduction of pathogens, such as enterohemorrhagic Escherichia coli (EHEC), into the GI

  4. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 false Escherichia coli serological reagents. 866.3255 ...Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices...

  5. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 false Escherichia coli serological reagents. 866.3255 ...Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices...

  6. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 2010-04-01 false Escherichia coli serological reagents. 866.3255 ...Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices...

  7. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Escherichia coli serological reagents. 866.3255 ...Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices...

  8. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 false Escherichia coli serological reagents. 866.3255 ...Serological Reagents § 866.3255 Escherichia coli serological reagents. (a) Identification. Escherichia coli serological reagents are devices...

  9. Proteomic Applications for Engineering Escherichia coli for Biofuel Production

    E-print Network

    Rutherford, Becky Joanna Gail

    2011-01-01

    E. Isaacson. 2002. Identification of Escherichia coli GenesIdentification of a major facilitator protein from Escherichia coliIdentification and molecular characterization of csrA, a pleiotropic gene from Escherichia coli

  10. SEROLOGICAL CROSS-REACTIONS BETWEEN ESCHERICHIA COLI 0157 AND OTHER SPECIES OF THE GENUS ESCHERICHIA

    EPA Science Inventory

    Escherichia hermannii, a sorbitol-negative species of the genus Escherichia, has been reported to be agglutinated by Escherichia coli 0157 and four sorbitol-negative species of the genus Escherichia: . hermannii (24 isolates), Escherichia fergusonii (12 isolates), Escherichia vul...

  11. Negative chemotaxis in Escherichia coli.

    PubMed

    Tso, W W; Adler, J

    1974-05-01

    Several methods for detecting or measuring negative chemotaxis are described. Using these, we have surveyed a number of chemicals for their ability to repel Escherichia coli. Although most of the repellents are harmful compounds, harmfulness is neither necessary nor sufficient to make a compound a repellent. The repellents can be grouped into at least nine classes according to (i) competition experiments, (ii) mutants lacking certain of the negative taxes, and (iii) their chemical structure. The specificity of each class was studied. It is suggested that each class corresponds to a distinct chemoreceptor. Generally, non-chemotactic mutants lack both positive and negative chemotaxis, and l-methionine is required for both kinds of taxis. Repellents at very low concentrations are not attractants, and attractants at very high concentrations are not repellents. PMID:4597449

  12. Bioluminescence.

    ERIC Educational Resources Information Center

    Jones, M. Gail

    1993-01-01

    Describes bioluminescence and the chemistry of how it occurs. Presents information for conducting the following classroom activities: (1) firefly mimic; (2) modeling deep-sea fish; (3) sea fireflies; and (4) the chemistry of light. (PR)

  13. Chemical Organizations in the Central Sugar Metabolism of Escherichia Coli

    E-print Network

    Dittrich, Peter

    1 Chemical Organizations in the Central Sugar Metabolism of Escherichia Coli Florian Centler, network analysis, stoichiometry, systems biology, sugar metabolism, Escherichia coli 1.1 Introduction in E. coli including gene expression, signal transduction, and enzymatic activities, some organizations

  14. Starvation and outgrowth response in Escherichia coli 

    E-print Network

    Holland, Jill Diane

    1999-01-01

    In order to better understand the mechanisms that graphics. enable Escherichia coli to survive periods of starvation and then resume growth upon addition of nutrients, different aspects of starvation and recovery have been ...

  15. Recombinant collagen production optimization in Escherichia coli

    E-print Network

    Whittemore, Brett A

    2005-01-01

    An Escherichia coli-based collagen-production process was used to investigate several process optimization objectives for use at the industrial scale. The effect of cooling on fermentation growth kinetics was studied, with ...

  16. Determination of Cellular Pathways that Lead to Spontaneous and Induced Mutagenesis in Escherichia coli

    E-print Network

    Becket, Elinne

    2012-01-01

    Identification of the second chromophore of Escherichia coliIdentification of mutator genes and mutational pathways in Escherichia coliEscherichia coli: mapping, cloning, sequencing, and identification

  17. Structure of Escherichia Coli Tryptophanase

    SciTech Connect

    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.

  18. Escherichia coli survival in waters: Temperature dependence

    EPA Science Inventory

    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...

  19. Strategies for Protein Overproduction in Escherichia coli.

    ERIC Educational Resources Information Center

    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…

  20. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  1. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  2. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  3. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

  4. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Code of Federal Regulations, 2010 CFR

    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...

  5. Preconcentration and detection of mercury with bioluminescent bioreporter E. coli ARL1.

    PubMed

    Solovyev, Andrey I; Koštejn, Martin; Kuncova, Gabriela; Dostálek, Pavel; Rohovec, Jan; Navrátil, Tomáš

    2015-10-01

    Cell wall envelopes treated with sodium hydroxide and spray-dried were used as mercury sorbents. The sorbent having sorption capacity 17.7?±?0.1 ?mol/g determined was employed for preconcentration of mercury containing 1-10 ng/L. After preconcentration, bioavailable mercury was detected in samples of soil, stream, and tap water via induction of bioluminescence of E. coli ARL1. Iron and manganese at concentrations of tenth microgram per liter interfered bioluminescence detection of mercury. In tap water was detected semiquantitatively 0.127?±?0.1 nmol/L by the induction of bioluminescence of E. coli ARL1 in medium with tryptone after preconcentration using a method of standard addition. PMID:26099333

  6. In-stream Escherichia coli Modeling

    NASA Astrophysics Data System (ADS)

    Pandey, P.; Soupir, M.

    2013-12-01

    Elevated levels of pathogenic bacteria indicators such as Escherichia coli (E. coli) in streams are a serious concern. Controlling E. coli levels in streams requires improving our existing understanding of fate and transport of E. coli at watershed scale. In-stream E. coli concentrations are potentially linked to non-point pollution sources (i.e., agricultural land). Water of a natural stream can receive E. coli by either through overland flow (via runoff from cropland) or resuspension from the streambed to the water column. Calculating in-stream total E. coli loads requires estimation of particle attached bacteria as well free floating E. coli transport. Currently water quality models commonly used for predicting E. coli levels in stream water have limited capability for predicting E. coli levels in the water column as well as in the streambed sediment. The challenges in calculating in-stream E. coli levels include difficulties in modeling the complex interactions between sediment particles and E. coli. Here we have developed a watershed scale model (integrated with Soil and Water Assessment Tool (SWAT)), which involves calculation of particle attached E. coli, to predict in-stream E. coli concentrations. The proposed model predicts E. coli levels in streambed bed sediment as well as in the water column. An extensive in-stream E. coli monitoring was carried out to verify the model predictions, and results indicate that the model performed well. The study proposed here will improve understanding on in-stream bacterial contamination, and help improving existing water quality models for predicting pathogenic bacteria levels in ambient water bodies.

  7. Fosfomycin Resistance in Escherichia coli, Pennsylvania, USA

    PubMed Central

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

    2015-01-01

    Fosfomycin resistance in Escherichia coli is rare in the United States. An extended-spectrum ?-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. PMID:26488485

  8. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ... Safety and Inspection Service Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY... 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,...

  9. Four products from Escherichia coli pseudogenes increase hydrogen production q

    E-print Network

    Wood, Thomas K.

    Four products from Escherichia coli pseudogenes increase hydrogen production q Mohd Zulkhairi Mohd Escherichia coli pseudogene ydfW ypdJ yqiG ylcE a b s t r a c t Pseudogenes are considered to be nonfunctional genes that lack a physiological role. By screening 3985 Escherichia coli mutants using chemochromic

  10. Secretory Production of Human Leptin in Escherichia coli

    E-print Network

    Secretory Production of Human Leptin in Escherichia coli Ki Jun Jeong, Sang Yup Lee Department homeostasis. In this study, human leptin was pro- duced and secreted efficiently in Escherichia coli using peptide; secre- tion; DsbA; Escherichia coli; protein production INTRODUCTION Human leptin, the product

  11. Miniseries: Illustrating the Machinery of Life Escherichia coli*

    E-print Network

    Economou, Tassos

    Miniseries: Illustrating the Machinery of Life Escherichia coli* Received for publication, August that support a recent textbook illustration of an Escherichia coli cell. The image magnifies a portion of life.'' This is how I began my 1991 article that presented several illustrations of Escherichia coli [1

  12. Influence of Escherichia coli hydrogenases on hydrogen fermentation from glycerol

    E-print Network

    Wood, Thomas K.

    Influence of Escherichia coli hydrogenases on hydrogen fermentation from glycerol Viviana Sanchez xxx Keywords: Hydrogen Glycerol metabolism Fermentation Hydrogenases Escherichia coli a b s t r a c t Since the actual role of Escherichia coli hydrogenases on fermentation from glycerol has not been clear

  13. EcoCyc: a comprehensive database resource for Escherichia coli

    E-print Network

    Bansal, Manju

    EcoCyc: a comprehensive database resource for Escherichia coli Ingrid M. Keseler, Julio Collado://EcoCyc.org/) is a com- prehensivesourceofinformationonthebiologyofthe prototypical model organism Escherichia coli K12 investigations, Escherichia coli remains the best-studied bacterium and the primary reference organism

  14. |Research Focus In search of the minimal Escherichia coli genome

    E-print Network

    Conway, Tyrrell

    |Research Focus In search of the minimal Escherichia coli genome Darren J. Smalley, Marvin Whiteley-0245, USA Recent plans announced for the systematic cataloging of the minimal Escherichia coli gene set out the essence of the biology of why or how Escherichia coli colonizes the bowel as a commensal' (Bio

  15. ORIGINAL ARTICLE Escherichia coli transcription factor YncC

    E-print Network

    Wood, Thomas K.

    ORIGINAL ARTICLE Escherichia coli transcription factor YncC (McbR) regulates colanic acid, USA Quorum-sensing signal autoinducer 2 (AI-2) stimulates Escherichia coli biofilm formation through Escherichia coli biofilm development is a complex process with at least five developmental stages; initial

  16. Poly(3-hydroxybutyrate) production from xylose by recombinant Escherichia coli

    E-print Network

    Poly(3-hydroxybutyrate) production from xylose by recombinant Escherichia coli Sang Yup Lee Abstract Several recombinant Escherichia coli strains harboring the Alcaligenes eutrophus and methods 2.1 Bacterial strains and plasmids Escherichia coli strains used were B (ATCC 11303), B (DSM 499

  17. Research Note--Prevalence of Pathogenic Escherichia coli in the

    E-print Network

    Singer, Randall

    Research Note-- Prevalence of Pathogenic Escherichia coli in the Broiler House Environment J. S sampling of Escherichia coli from broiler house litter and bird lesions of either cellulitis´n--Prevalencia de Escherichia coli pato´geno en el medio ambiente de los galpones de pollo de engorde. Se tomaron

  18. COMMUNICATION TO THE EDITOR The Inhibition of Escherichia coli lac

    E-print Network

    Relue, Patricia

    COMMUNICATION TO THE EDITOR The Inhibition of Escherichia coli lac Operon Gene Expression to quantitatively describe the inhibition of the Escherichia coli lac operon gene expression by triplex 70: 467­472, 2000 Keywords: genetically structured model; Escherichia coli lac operon; gene

  19. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-21

    ...FSIS-2010-0023] Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food...non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103...with Shiga toxin-producing Escherichia coli (STEC) O26, O45, O103, O111,...

  20. Pathogenic potential of escherichia coli O26 and sorbitol-fermenting escherichia coli O157:NM 

    E-print Network

    Rosser, Tracy

    2010-01-01

    Verocytotoxin-producing Escherichia coli (VTEC) are important human pathogens that may cause diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome (HUS). Worldwide, non-sorbitol-fermenting (NSF) VTEC O157:H7 is ...

  1. Escherichia Coli--Key to Modern Genetics.

    ERIC Educational Resources Information Center

    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.…

  2. Escherichia coli and Sudden Infant Death Syndrome

    PubMed Central

    Bettelheim, Karl A.; Goldwater, Paul N.

    2015-01-01

    This review examines the association of strains of Escherichia coli with sudden infant death syndrome (SIDS) and the possible role these bacteria play in this enigmatic condition. The review addresses evidence for E. coli in SIDS infants, potential sources of E. coli in the environment, colonization by commensal and pathogenic strains, the variety of currently accepted pathotypes, and how these pathotypes could compromise intestinal integrity and induce inflammation. Both intestinal and extraintestinal pathotypes are compared in relation to the apparent liability in which virulence traits can be gained or lost by strains of E. coli. The way in which E. coli infections fit with current views on infant sleeping position and other SIDS risk factors is highlighted. PMID:26191064

  3. 76 FR 20542 - Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ...and in foods such as ground beef, pork sausage, chicken, oysters, cheese, fresh mushrooms, and lettuce. In addition...coli and coliphages were found in chicken, fresh pork, fresh oyster, fresh mushrooms, lettuce, chicken pot pie, biscuit...

  4. Escherichia coli Capsule Bacteriophages II. Morphology

    PubMed Central

    Stirm, Stephan; Freund-Mölbert, Elisabeth

    1971-01-01

    The Escherichia coli capsule bacteriophages (K phages) described herein are specific for certain capsular strains of E. coli, all of them test strains for different E. coli K antigens. The phages are not adsorbed to the acapsular mutants of their host organisms nor to similar strains with serologically and chemically different capsular polysaccharides. Thirteen E. coli (and one Klebsiella) K phages were visualized in the electron microscope. Most viruses are similar to P22 and thus belong to Bradley group C; however, one each of group A (long, contractile tail) and group B (long, noncontractile tail) was also found. All K phages were seen to carry spikes but no tail fibers were detected. These results suggest that the structures responsible for the recognition of the thick (about 400 nm or more) capsular polysaccharide gels are located in these spikes. Images PMID:4107543

  5. Pathogenic Escherichia coli and One Health implications.

    PubMed

    Fegan, Narelle; Gobius, Kari S

    2013-01-01

    Escherichia coli are common inhabitants in the intestinal tracts of warm blooded animals where they generally cause no harm to the host, although there are some types of E. coli which are able to cause disease. The most significant of these are enterohaemorrhagic E. coli (EHEC) which can cause severe human disease that can result in death. EHEC have an animal reservoir, particularly cattle, and are considered to be an important zoonotic pathogen having significant impact for One Health. EHEC can be transmitted from animals into humans, either from consumption of foods made from these animals, or from contact with foods which may have become contaminated directly or indirectly from animal wastes. Increasingly, EHEC have also been associated with uncooked leafy green vegetables and sprouts. Several large outbreaks of E. coli have highlighted the importance for addressing these organisms in a One Health perspective. PMID:22918674

  6. Influence of autoinducer 2 (ai-2) and ai-2-like inhibitors generated from ground beef on escherichia coli o157:h7 protein expression 

    E-print Network

    Soni, Kamleshkumar A.

    2009-05-15

    contains compounds that can interfere with AI-2-mediated bioluminescence expression in Vibrio. harveyi. The underlying hypothesis of this work was that AI-2 molecules affect the protein expression in Escherichia coli O157:H7 and AI-2 inhibitory molecules...

  7. Hydrogen production by recombinant Escherichia coli strains

    PubMed Central

    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

  8. Controlling biological systems: the lactose regulation system of Escherichia coli

    E-print Network

    Pappas, George J.

    Controlling biological systems: the lactose regulation system of Escherichia coli A. Agung Julius, namely, the lactose regulation system of the Escherichia coli bacteria. The conceptual idea behind hybrid model of the lactose regulation system of E. coli bacteria that capture important phenomena which

  9. Genetic architecture of thermal adaptation in Escherichia coli

    E-print Network

    Bennett, Albert F.

    Genetic architecture of thermal adaptation in Escherichia coli Michelle M. Riehle*, Albert F make genomewide surveys more tractable. Six lines of Escherichia coli adapted for 2,000 generations events. Three of the duplications were at 2.85 Mb of the E. coli chromo- some, providing evidence

  10. Shiga toxin-producing Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In United States, it is estimated that non-O157 Shiga toxin-producing Escherichia coli (STEC) cause more illnesses than STEC O157:H7, and the majority of cases of non-O157 STEC infections is due to serogroups O26, O45, O103, O111, O121, and O145, referred to as the top six non-O157 STEC. The diseas...

  11. Escherichia coli proteomics and bioinformatics 

    E-print Network

    Niu, Lili

    2009-05-15

    and proteomics. Chapter VI describes conclusions of this dissertation. 13 Table 1.1. E. coli web-based databases. Name URL References ASAP https://asap.ahabs.wisc.edu/asap/home.php (Glasner et al., 2003) AlignACE http://arep.med.harvard.edu/ecoli...; Karp et al., 1997, 1998; Karp et al., 2000; Karp et al., 2002; Keseler et al., 2005; Paley and Karp, 1996) EcoGene http://bmb.med.miami.edu/EcoGene/EcoWeb/ (Rudd, 2000) EchoBase http://ecoli-york.org/ (Misra et al., 2005) GenProtEC http...

  12. Dissolution of Silver Nanowires and Nanospheres Dictates Their Toxicity to Escherichia coli

    PubMed Central

    Künnis-Beres, Kai; Kahru, Anne; Ivask, Angela

    2013-01-01

    Silver nanoparticles are extensively used in antibacterial applications. However, the mechanisms of their antibacterial action are not yet fully explored. We studied the solubility-driven toxicity of 100 × 6100?nm (mean primary diameter × length) silver nanowires (NWs) to recombinant bioluminescent Escherichia coli as a target representative of enteric pathogens. The bacteria were exposed to silver nanostructures in water to exclude the speciation-driven alterations. Spherical silver nanoparticles (83?nm mean primary size) were used as a control for the effect of NPs shape. Toxicity of both Ag NWs and spheres to E. coli was observed at similar nominal concentrations: the 4h EC50 values, calculated on the basis of inhibition of bacterial bioluminescence, were 0.42?±?0.06 and 0.68?±?0.01?mg Ag/L, respectively. Dissolution and bioavailability of Ag from NWs and nanospheres, analyzed with AAS or Ag-sensor bacteria, respectively, suggested that the toxic effects were caused by solubilized Ag+ ions. Moreover, the antibacterial activities of Ag NWs suspension and its ultracentrifuged particle-free supernatant were equal. The latter indicated that the toxic effects of ~80–100?nm Ag nanostructures to Escherichia coli were solely dependent on their dissolution and no shape-induced/related effects were observed. Yet, additional nanospecific effects could come into play in case of smaller nanosilver particles. PMID:24024212

  13. Biodegradation of Aromatic Compounds by Escherichia coli

    PubMed Central

    Díaz, Eduardo; Ferrández, Abel; Prieto, María A.; García, José L.

    2001-01-01

    Although Escherichia coli has long been recognized as the best-understood living organism, little was known about its abilities to use aromatic compounds as sole carbon and energy sources. This review gives an extensive overview of the current knowledge of the catabolism of aromatic compounds by E. coli. After giving a general overview of the aromatic compounds that E. coli strains encounter and mineralize in the different habitats that they colonize, we provide an up-to-date status report on the genes and proteins involved in the catabolism of such compounds, namely, several aromatic acids (phenylacetic acid, 3- and 4-hydroxyphenylacetic acid, phenylpropionic acid, 3-hydroxyphenylpropionic acid, and 3-hydroxycinnamic acid) and amines (phenylethylamine, tyramine, and dopamine). Other enzymatic activities acting on aromatic compounds in E. coli are also reviewed and evaluated. The review also reflects the present impact of genomic research and how the analysis of the whole E. coli genome reveals novel aromatic catabolic functions. Moreover, evolutionary considerations derived from sequence comparisons between the aromatic catabolic clusters of E. coli and homologous clusters from an increasing number of bacteria are also discussed. The recent progress in the understanding of the fundamentals that govern the degradation of aromatic compounds in E. coli makes this bacterium a very useful model system to decipher biochemical, genetic, evolutionary, and ecological aspects of the catabolism of such compounds. In the last part of the review, we discuss strategies and concepts to metabolically engineer E. coli to suit specific needs for biodegradation and biotransformation of aromatics and we provide several examples based on selected studies. Finally, conclusions derived from this review may serve as a lead for future research and applications. PMID:11729263

  14. Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance

    E-print Network

    Collins, James J.

    Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance Nicole Salmonella typhimurium increases its antibiotic toler- ance in response to indole, even though S. typhimurium

  15. Profiling of Escherichia coli Chromosome database.

    PubMed

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

    2008-01-01

    The Profiling of Escherichia coli Chromosome (PEC) database (http://www.shigen.nig.ac.jp/ecoli/pec/) is designed to allow E. coli researchers to efficiently access information from functional genomics studies. The database contains two principal types of data: gene essentiality and a large collection of E. coli genetic research resources. The essentiality data are based on data compilation from published single-gene essentiality studies and on cell growth studies of large-deletion mutants. Using the circular and linear viewers for both whole genomes and the minimal genome, users can not only gain an overview of the genome structure but also retrieve information on contigs, gene products, mutants, deletions, and so forth. In particular, genome-wide exhaustive mutants are an essential resource for studying E. coli gene functions. Although the genomic database was constructed independently from the genetic resources database, users may seamlessly access both types of data. In addition to these data, the PEC database also provides a summary of homologous genes of other bacterial genomes and of protein structure information, with a comprehensive interface. The PEC is thus a convenient and useful platform for contemporary E. coli researchers. PMID:18392982

  16. Insights on Escherichia coli biofilm formation and inhibition from whole-transcriptome profiling

    E-print Network

    Wood, Thomas K.

    Minireview Insights on Escherichia coli biofilm formation and inhibition from whole with the best- characterized strain, Escherichia coli. Investigations of biofilm formation and inhibition). Escherichia coli biofilm development is a complex process that leads to beautiful structures (Fig. 1

  17. Engineering a responsive, heterologous mevalonate pathway in Escherichia coli using microarrays

    E-print Network

    Dahl II, Robert Harlan

    2011-01-01

    component system in Escherichia coli K-12: identification ofIdentification and molecular characterization of the Mg2+ stimulon of Escherichia coli.identification of changes that contribute to ethanol tolerance in ethanologenic Escherichia coli:

  18. Survival of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi in Vembanadu

    E-print Network

    Mazumder, Asit

    Survival of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi the survival response of multi-drug resistant enteropathogenic Escherichia coli and Salmonella paratyphi- otypes of Escherichia coli, Salmonella enterica typhi and paratyphi are highly endemic to India

  19. ELECTROPHORETIC MOBILITIES OF ESCHERICHIA COLI 0157:H7 AND WILD-TYPE ESCHERICHIA COLI STRAINS

    EPA Science Inventory

    The electrophoretic mobility (EPM) of a number of human-virulent and "wild-type" Escherichia coli strains in phosphate buffered water was measured. The impact of pH, ionic strength, cation type (valence) and concentration, and bacterial strain on the EPM was investigated. Resul...

  20. Transient fluorescence in synchronously dividing Escherichia coli.

    PubMed Central

    Layne, S P; Bigio, I J; Scott, A C; Lomdahl, P S

    1985-01-01

    Using a spectrometer equipped with an optical multichannel analyzer as the detector, we observed the Stokes laser-Raman spectra of metabolically synchronous Escherichia coli from 100 to 2100 cm-1. After more than 400 separate recordings, at cell concentrations of 10(7)-10(8) per ml, no Raman lines attributable to the metabolic process nor to the cells themselves were found. However, we did find that synchronous E. coli cultures become more fluorescent during a limited phase of the division cycle. This transient increase in fluorescence may be ascribed to a variation in the redox state of a chemical species within the bacteria or to a variation of the intracellular optical field. The effect is reproducible in synchronous cultures and it is not seen in asynchronous ones. The results suggest that spectral features seen in previous laser-Raman spectra of synchronous bacteria (taken with scanning monochromators) are due to a time-dependent variation in bacterial fluorescence. PMID:3906649

  1. Escherichia coli growth under modeled reduced gravity

    NASA Technical Reports Server (NTRS)

    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. Gas signatures from Escherichia coli and Escherichia coli-inoculated human whole blood

    PubMed Central

    2013-01-01

    Background The gaseous headspace above naïve Escherichia Coli (E. coli) cultures and whole human blood inoculated with E. coli were collected and analyzed for the presence of trace gases that may have the potential to be used as novel, non-invasive markers of infectious disease. Methods The naïve E. coli culture, LB broth, and human whole blood or E. coli inoculated whole blood were incubated in hermetically sealable glass bioreactors at 37°C for 24 hrs. LB broth and whole human blood were used as controls for background volatile organic compounds (VOCs). The headspace gases were collected after incubation and analyzed using a gas chromatographic system with multiple column/detector combinations. Results Six VOCs were observed to be produced by E. coli-infected whole blood while there existed nearly zero to relatively negligible amounts of these gases in the whole blood alone, LB broth, or E. coli-inoculated LB broth. These VOCs included dimethyl sulfide (DMS), carbon disulfide (CS2), ethanol, acetaldehyde, methyl butanoate, and an unidentified gas S. In contrast, there were several VOCs significantly elevated in the headspace above the E. coli in LB broth, but not present in the E. coli/blood mixture. These VOCs included dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), methyl propanoate, 1-propanol, methylcyclohexane, and unidentified gases R2 and Q. Conclusions This study demonstrates 1) that cultivated E. coli in LB broth produce distinct gas profiles, 2) for the first time, the ability to modify E. coli-specific gas profiles by the addition of whole human blood, and 3) that E. coli-human whole blood interactions present different gas emission profiles that have the potential to be used as non-invasive volatile biomarkers of E. coli infection. PMID:23842518

  3. Transport proteins promoting Escherichia coli pathogenesis

    PubMed Central

    Tang, Fengyi; Saier, Milton H.

    2014-01-01

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

  4. Inactivation of Escherichia coli by ultrasonic irradiation.

    PubMed

    Furuta, M; Yamaguchi, M; Tsukamoto, T; Yim, B; Stavarache, C E; Hasiba, K; Maeda, Y

    2004-04-01

    Ultrasonic inactivation of Escherichia coli XL1-Blue has been investigated by high-intensity ultrasonic waves from horn type sonicator (27.5 kHz) utilizing the "squeeze-film effect". The amplitude of the vibration face contacting the sample solution was used as an indication of the ultrasonic power intensity. The inactivation of the E. coli cells by ultrasonic irradiation shows pseudo first-order behavior. The inactivation rate constant gradually increased with increasing amplitude of the vibration face and showed rapid increase above 3 microm (p-p). In contrast, the H2O2 formation was not observed below 3 microm (p-p), indicating that the ultrasonic shock wave might be more important than indirect effect of OH radicals formed by ultrasonic cavitation in this system. The optimal thickness of the squeeze film was determined as 2 mm for the E. coli inactivation. More than 99% of E. coli cells was inactivated within 180-s sonication at the amplitude of 3 microm (p-p) and 2 mm of the thickness of the squeeze film. PMID:15030780

  5. 76 FR 58157 - Shiga Toxin-Producing Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service, USDA... and other raw ground beef product components, to ensure control of both Escherichia coli O157:H7 (E... illness. FSIS issued a policy statement (64 FR 2803; Jan. 19, 1999) that stated, ``* * * iven the...

  6. Budget Analysis of Escherichia coli at a Southern Lake Michigan

    E-print Network

    Budget Analysis of Escherichia coli at a Southern Lake Michigan Beach P R A M O D T H U P A K I and the Environment, University of Michigan, Ann Arbor, Michigan, NOAA Great Lakes Environmental Research Laboratory bacteria such as Escherichia coli (EC) and enterococci (1). Coastal water quality has a significant

  7. Arabidopsis alternative oxidase sustains Escherichia coli respiration.

    PubMed

    Kumar, A M; Söll, D

    1992-11-15

    Glutamyl-tRNA reductase, encoded by the hemA gene, is the first enzyme in porphyrin biosynthesis in many organisms. Hemes, important porphyrin derivatives, are essential components of redox enzymes, such as cytochromes. Thus a hemA Escherichia coli strain (SASX41B) is deficient in cytochrome-mediated aerobic respiration. Upon complementation of this strain with an Arabidopsis thaliana cDNA library, we isolated a clone which permitted the SASX41B strain to grow aerobically. The clone encodes the gene for Arabidopsis alternative oxidase, whose deduced amino acid sequence was found to have 71% identity with that of the enzyme from the voodoo lily, Sauromatum guttatum. The Arabidopsis protein is expressed as a 31-kDa protein in E. coli and confers on this organism cyanide-resistant growth, which in turn is sensitive to salicylhydroxamate. This implies that a single polypeptide is sufficient for alternative oxidase activity. Based on these observations we propose that a cyanide-insensitive respiratory pathway operates in the transformed E. coli hemA strain. Introduction of this pathway now opens the way to genetic/molecular biological investigations of alternative oxidase and its cofactor. PMID:1438286

  8. Regulation of alcohol fermentation by Escherichia coli

    SciTech Connect

    Clark, D.P.

    1990-01-01

    The purpose of this project is to elucidate the way in which the synthesis of ethanol and related fermentation products are regulated in the facultative anaerobe Escherichia coli. We are also investigating the control of other genes required for anaerobic growth. We have isolated both structural and regulatory mutations affecting the expression of alcohol dehydrogenase, the enzyme responsible for the final step in alcohol synthesis. Some of these regulatory mutations also affect other anaerobically induced genes. The adh gene has been cloned and sequenced. The ADH protein is one of the largest highly expressed proteins in E. coli and requires approximately 2700bp of DNA for its coding sequence. We have also isolated mutations affecting the fermentative lactate dehydrogenase and have recently cloned the ldh gene. In consequence it is now possible to construct E. coli strains defective in the production of any one or more of their normal fermentation products (i.e. formate, acetate, lactate, ethanol and succinate). The factors affecting ratio of fermentation products are being investigated by in vivo NMR spectroscopy.

  9. Regulation of alcohol fermentation by Escherichia coli

    SciTech Connect

    Clark, D.P.

    1989-01-01

    The purpose of this project is to elucidate the way in which the fermentative synthesis of ethanol is regulated in the facultative anaerobe Escherichia coli. We are also investigating the control of other genes required for fermentation and anaerobic growth. We have isolated both structural and regulatory mutations affecting the expression of alcohol dehydrogenase, the enzyme responsible for the final step in alcohol synthesis. Some of these regulatory mutations also affect other anaerobically induced genes. The adh gene has been cloned and sequenced. The ADH protein is one of the largest highly expressed proteins in E. coli and requires approximately 2700bp of DNA for its cloning sequence. We have also isolated mutations affecting the fermentative lactate dehydrogenase. In consequence it is now possible to construct E. coli strains defective in the production of any one or more of their normal fermentation products (i.e. formate, acetate, lactate, ethanol and succinate). The factors affecting the ratio of fermentation products are being investigated by in vivo NMR spectroscopy.

  10. Cells of Escherichia coli are protected against severe chemical stress by co-habiting cell aggregates formed by Pseudomonas aeruginosa.

    PubMed

    Jagmann, Nina; Henke, Sebastian Franz; Philipp, Bodo

    2015-10-01

    Bacterial cells within biofilms and cell aggregates show increased resistance against chemical stress compared with suspended cells. It is not known whether bacteria that co-habit biofilms formed by other bacteria also acquire such resistance. This scenario was investigated in a proof-of-principle experiment with Pseudomonas aeruginosa strain PAO1 as cell aggregate-forming bacterium and Escherichia coli strain MG1655 as potential co-habiting bacterium equipped with an inducible bioluminescence system. Cell aggregation of strain PAO1 can be induced by the toxic detergent sodium dodecyl sulfate (SDS). In single cultures of strain MG1655, bioluminescence was inhibited by the protonophor carbonylcyanide-m-chlorophenylhydrazone (CCCP) but the cells were still viable. By applying CCCP and SDS together, cells of strain MG1655 lost their bioluminescence and viability indicating the importance of energy-dependent resistance mechanisms against SDS. In co-suspensions with strain PAO1, bioluminescence of strain MG1655 was sustained in the presence of SDS and CCCP. Image analysis showed that bioluminescent cells were located in cell aggregates formed by strain PAO1. Thus, cells of strain MG1655 that co-habited cell aggregates formed by strain PAO1 were protected against a severe chemical stress that was lethal to them in single cultures. Co-habiting could lead to increased survival of pathogens in clinical settings and could be employed in biotechnological applications involving toxic milieus. PMID:26066844

  11. Non-O157 Shiga toxin-producing Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli (STEC), also known as verocytotoxin-producing E. coli, are important food-borne pathogens responsible for outbreaks of hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). STEC that cause HC and HUS are also referred to as enterohemorrhagic E. coli (E...

  12. CONFINEMENT BY BIASED VELOCITY JUMPS: AGGREGATION OF ESCHERICHIA COLI

    E-print Network

    Schmeiser, Christian

    CONFINEMENT BY BIASED VELOCITY JUMPS: AGGREGATION OF ESCHERICHIA COLI VINCENT CALVEZ, GA¨EL RAOUL-attractors. The prototypical example is the bacterium Escheria coli, whose swimming pattern has been described as run, this stochastic process is biased upwards the gradient, although E. coli is too small to reliably measure

  13. Efficient production of indigoidine in Escherichia coli.

    PubMed

    Xu, Fuchao; Gage, David; Zhan, Jixun

    2015-08-01

    Indigoidine is a bacterial natural product with antioxidant and antimicrobial activities. Its bright blue color resembles the industrial dye indigo, thus representing a new natural blue dye that may find uses in industry. In our previous study, an indigoidine synthetase Sc-IndC and an associated helper protein Sc-IndB were identified from Streptomyces chromofuscus ATCC 49982 and successfully expressed in Escherichia coli BAP1 to produce the blue pigment at 3.93 g/l. To further improve the production of indigoidine, in this work, the direct biosynthetic precursor L-glutamine was fed into the fermentation broth of the engineered E. coli strain harboring Sc-IndC and Sc-IndB. The highest titer of indigoidine reached 8.81 ± 0.21 g/l at 1.46 g/l L-glutamine. Given the relatively high price of L-glutamine, a metabolic engineering technique was used to directly enhance the in situ supply of this precursor. A glutamine synthetase gene (glnA) was amplified from E. coli and co-expressed with Sc-indC and Sc-indB in E. coli BAP1, leading to the production of indigoidine at 5.75 ± 0.09 g/l. Because a nitrogen source is required for amino acid biosynthesis, we then tested the effect of different nitrogen-containing salts on the supply of L-glutamine and subsequent indigoidine production. Among the four tested salts including (NH4)2SO4, NH4Cl, (NH4)2HPO4 and KNO3, (NH4)2HPO4 showed the best effect on improving the titer of indigoidine. Different concentrations of (NH4)2HPO4 were added to the fermentation broths of E. coli BAP1/Sc-IndC+Sc-IndB+GlnA, and the titer reached the highest (7.08 ± 0.11 g/l) at 2.5 mM (NH4)2HPO4. This work provides two efficient methods for the production of this promising blue pigment in E. coli. PMID:26109508

  14. Metabolic engineering of Escherichia coli for the production of medium-chain-length polyhydroxyalkanoates

    E-print Network

    Metabolic engineering of Escherichia coli for the production of medium published online 12 August 2002 Abstract The Escherichia coli fabGEc gene and the Pseudomonas aeruginosa rhl protein reductase; Escherichia coli FabG; Pseudomonas aeruginosa RhlG; Escherichia coli 1. Introduction

  15. Animal models of enteroaggregative Escherichia coli infection

    PubMed Central

    Philipson, Casandra W.; Bassaganya-Riera, Josep; Hontecillas, Raquel

    2013-01-01

    Enteroaggregative Escherichia coli (EAEC) has been acknowledged as an emerging cause of gastroenteritis worldwide for over two decades. Epidemiologists are revealing the role of EAEC in diarrheal outbreaks as a more common occurrence than ever suggested before. EAEC induced diarrhea is most commonly associated with travelers, children and immunocompromised individuals however its afflictions are not limited to any particular demographic. Many attributes have been discovered and characterized surrounding the capability of EAEC to provoke a potent pro-inflammatory immune response, however cellular and molecular mechanisms underlying initiation, progression and outcomes are largely unknown. This limited understanding can be attributed to heterogeneity in strains and the lack of adequate animal models. This review aims to summarize current knowledge about EAEC etiology, pathogenesis and clinical manifestation. Additionally, current animal models and their limitations will be discussed along with the value of applying systems-wide approaches such as computational modeling to study host-EAEC interactions. PMID:23680797

  16. Dispensability of Escherichia coli's latent pathways

    E-print Network

    Cornelius, Sean P; Motter, Adilson E; 10.1073/pnas.1009772108

    2011-01-01

    Gene-knockout experiments on single-cell organisms have established that expression of a substantial fraction of genes is not needed for optimal growth. This problem acquired a new dimension with the recent discovery that environmental and genetic perturbations of the bacterium Escherichia coli are followed by the temporary activation of a large number of latent metabolic pathways, which suggests the hypothesis that temporarily activated reactions impact growth and hence facilitate adaptation in the presence of perturbations. Here we test this hypothesis computationally and find, surprisingly, that the availability of latent pathways consistently offers no growth advantage, and tends in fact to inhibit growth after genetic perturbations. This is shown to be true even for latent pathways with a known function in alternate conditions, thus extending the significance of this adverse effect beyond apparently nonessential genes. These findings raise the possibility that latent pathway activation is in fact derivat...

  17. Escherichia coli with two linear chromosomes.

    PubMed

    Liang, Xiquan; Baek, Chang-Ho; Katzen, Federico

    2013-12-20

    A number of attempts have been made to simplify the synthesis of whole chromosomes to generate artificial microorganisms. However, the sheer size of the average bacterial genome makes the task virtually impracticable. A major limitation is the maximum assembly DNA size imposed by the current available technologies. We propose to fragment the bacterial chromosome into autonomous replicating units so that (i) each episome becomes small enough to be assembled in its entirety within an assembly host and (ii) the complete episome set should be able to generate a viable cell. In this work, we used the telN/tos system of bacteriophage N1 to show that the circular genome of Escherichia coli can be split into two linear chromosomes that complement each other to produce viable cells. PMID:24160891

  18. Escherichia coli photoreactivating enzyme: purification and properties

    SciTech Connect

    Snapka, R.M.; Sutherland, B.M.

    1980-01-01

    Researchers have purified large quantities of Escherichia coli photoreactivating enzyme to apparent homogeneity and have studied its physical and chemical properties. The enzyme has a molecular weight of 36,800 and a S/sub 20,w//sup 0/ of 3.72 S. Amino acid analysis revealed an apparent absence of tryptophan, a low content of aromatic residues, and the presence of no unusual amino acids. The N terminus is arginine. The purified enzyme contained up to 13% carbohydrate by weight. The carbohydrate was composed of mannose, galactose, glucose, and N-acetylglucosamine. The enzyme is also associated with RNA containing uracil, adenine, guanine, and cytosine with no unusual bases detected.

  19. Phosphoglucomutase Mutants of Escherichia coli K-12

    PubMed Central

    Adhya, Sankar; Schwartz, Maxime

    1971-01-01

    Bacteria with strongly depressed phosphoglucomutase (EC 2.7.5.1) activity are found among the mutants of Escherichia coli which, when grown on maltose, accumulate sufficient amylose to be detectable by iodine staining. These pgm mutants grow poorly on galactose but also accumulate amylose on this carbon source. Growth on lactose does not produce high amylose but, instead, results in the induction of the enzymes of maltose metabolism, presumably by accumulation of maltose. These facts suggest that the catabolism of glucose-1-phosphate is strongly depressed in pgm mutants, although not completely abolished. Anabolism of glucose-1-phosphate is also strongly depressed, since amino acid- or glucose-grown pgm mutants are sensitive to phage C21, indicating a deficiency in the biosynthesis of uridine diphosphoglucose or uridine diphosphogalactose, or both. All pgm mutations isolated map at about 16 min on the genetic map, between purE and the gal operon. PMID:4942754

  20. Independence of replisomes in Escherichia coli chromosomalreplication

    SciTech Connect

    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.

  1. Nucleotide excision repair in Escherichia coli.

    PubMed Central

    Van Houten, B

    1990-01-01

    One of the best-studied DNA repair pathways is nucleotide excision repair, a process consisting of DNA damage recognition, incision, excision, repair resynthesis, and DNA ligation. Escherichia coli has served as a model organism for the study of this process. Recently, many of the proteins that mediate E. coli nucleotide excision have been purified to homogeneity; this had led to a molecular description of this repair pathway. One of the key repair enzymes of this pathway is the UvrABC nuclease complex. The individual subunits of this enzyme cooperate in a complex series of partial reactions to bind to and incise the DNA near a damaged nucleotide. The UvrABC complex displays a remarkable substrate diversity. Defining the structural features of DNA lesions that provide the specificity for damage recognition by the UvrABC complex is of great importance, since it represents a unique form of protein-DNA interaction. Using a number of in vitro assays, researchers have been able to elucidate the action mechanism of the UvrABC nuclease complex. Current research is devoted to understanding how these complex events are mediated within the living cell. PMID:2181258

  2. PfkA locus of Escherichia coli.

    PubMed Central

    Vinopal, R T; Clifton, D; Fraenkel, D G

    1975-01-01

    pfkA was know, on the basis of three mutants, as the likely locus of phosphofructokinase in Escherichia coli, and the unlinked pfkB1 mutation suppressed these mutations by restoring some enzyme activity (Morrissey and Fraenkel, 1972). We now report a new search for the complete inactivation of pfkA (e.g., by deletion or amber mutation), done to assess whether the pfkB1 suppression is by an independent enzyme, phosphofructokinase activity 2 (Fraenkel, Kotlarz, and Buc, 1973). Ten new phosphofructokinase mutants all were at pfkA, rather than at pfkB or pfkC. One of them (pfkA9) gave temperature-sensitive reverants with heat-labile enzyme. Another (pfkA11) proved genetically to be a nonsense mutation, but showed no restored activity when suppressed by supF. However, even unsuppressed it was found to contain an enzyme related to phosphofructokinase activity 1 kinetically (more allosteric), physically (almot identical subunit), and antigenically. All the pfkA mutants apparently contained cross-reacting material to activity 1. All (including pfkA11) were suppressed by the pfkB1 mutation. Several results support the idea that pfkA is the structural gene for the main phosphofructokinase of E. coli (activity 1), but that there is some restriction to its complete inactivation. Images PMID:125265

  3. Uropathogenic Escherichia coli induces chronic pelvic pain.

    PubMed

    Rudick, Charles N; Berry, Ruth E; Johnson, James R; Johnston, Brian; Klumpp, David J; Schaeffer, Anthony J; Thumbikat, Praveen

    2011-02-01

    Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a debilitating syndrome of unknown etiology often postulated, but not proven, to be associated with microbial infection of the prostate gland. We hypothesized that infection of the prostate by clinically relevant uropathogenic Escherichia coli (UPEC) can initiate and establish chronic pain. We utilized an E. coli strain newly isolated from a patient with CP/CPPS (strain CP1) and examined its molecular pathogenesis in cell culture and in a murine model of bacterial prostatitis. We found that CP1 is an atypical isolate distinct from most UPEC in its phylotype and virulence factor profile. CP1 adhered to, invaded, and proliferated within prostate epithelia and colonized the prostate and bladder of NOD and C57BL/6J mice. Using behavioral measures of pelvic pain, we showed that CP1 induced and sustained chronic pelvic pain in NOD mice, an attribute not exhibited by a clinical cystitis strain. Furthermore, pain was observed to persist even after bacterial clearance from genitourinary tissues. CP1 induced pelvic pain behavior exclusively in NOD mice and not in C57BL/6J mice, despite comparable levels of colonization and inflammation. Microbial infections can thus serve as initiating agents for chronic pelvic pain through mechanisms that are dependent on both the virulence of the bacterial strain and the genetic background of the host. PMID:21078846

  4. Expanding ester biosynthesis in Escherichia coli

    PubMed Central

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

    2015-01-01

    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. PMID:24609358

  5. Arginine biosynthesis in Escherichia coli: experimental perturbation and mathematical modeling

    E-print Network

    Goldbeter, Albert

    1 Arginine biosynthesis in Escherichia coli: experimental perturbation and mathematical modeling , Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium. Running title: Modeling arginine, the arginine and pyrimidine biosynthetic pathways are connected through a common metabolite provided

  6. Regulation of type III secretion in enterohaemorrhagic Escherichia coli 

    E-print Network

    Xu, Xuefang

    2011-11-25

    Enterohaemorrhagic Escherichia coli (EHEC) strains are associated with gastrointestinal and severe systemic disease in humans. EHEC O157:H7 is the most common serotype causing human infections in North America and the ...

  7. Y-family DNA polymerases in Escherichia coli

    E-print Network

    Jarosz, Daniel F.

    The observation that mutations in the Escherichia coli genes umuC+ and umuD+ abolish mutagenesis induced by UV light strongly supported the counterintuitive notion that such mutagenesis is an active rather than passive ...

  8. TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI

    EPA Science Inventory

    Sewage samples from seven locations in the United States were analyzed for Escherichia coli isolates which were resistant to trimethoprim-sulfamethoxazole (SXT). The prevalence rate of SXT resistant organisms varied between the different geographical locales. The majority of th...

  9. Persistence, dissipation, and activity of Escherichia coli O157:H7 within sand and seawater environments.

    PubMed

    Williams, A Prysor; Avery, Lisa M; Killham, Ken; Jones, David L

    2007-04-01

    Runoff from agricultural land into watercourses may transport and deposit animal-derived waste contaminated with Escherichia coli O157:H7 onto beaches, which may in turn lead to human infection. To simulate contamination, freshwater mixed with cattle slurry containing E. coli O157:H7 was added to sand from three recreational beaches. The sand was then maintained in a dry state (nontidal) or subjected to a repeated seawater tidal simulation. The pathogen could still be recovered from all sands by day 5. Although survival of the pathogen did not statistically vary between sands of different origin under nontidal conditions, significant differences in numbers occurred between sands when subject to tidal simulation. In the tidal simulations, a considerable proportion of the E. coli O157:H7 rapidly dissipated from sand into the seawater. In a separate experiment, the activity of bioluminescent (lux-marked) E. coli O157:H7 cells was monitored in various mixtures of contaminated runoff water and seawater over 5 days. Pathogen activity declined with increasing seawater concentration; however, cells remained viable in all treatments over the 5-day period. The addition of nutrients to water rapidly increased pathogen activity in all treatments. Our findings highlight the resilience of E. coli O157:H7 in aquatic and marine environments. PMID:17250753

  10. Influence of carbon-based nanomaterials on lux-bioreporter Escherichia coli.

    PubMed

    Jia, Kun; Marks, Robert S; Ionescu, Rodica E

    2014-08-01

    The cytotoxic effects of carbon-based nanomaterials are evaluated via the induction of luminescent genetically engineered Escherichia coli bacterial cells. Specifically, two engineered E. coli bacteria strains of DPD2794 and TV1061 were incubated with aqueous dispersion of three carbon allotropes (multi-wall carbon nanotubes (MWCNTs), graphene nanosheets and carbon black nanopowders) with different concentrations and the resulting bioluminescence was recorded at 30°C and 25°C, respectively. The corresponding optical density changes of bacterial cells in the presence of various carbon nanomaterials were recorded as well. Based on these results, E. coli DPD2794 bacterial induction responds to a greater degree than E. coli TV1061 bacteria when exposed to various carbon-based nanomaterials. Finally, the surface morphology of E. coli DPD2794 bacteria cells before and after carbon-based nanomaterials treatment was observed using a field emission scanning electron microscope (FESEM), from which morphological changes from the presence of carbon-based nanomaterials were observed and discussed. PMID:24881555

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2011-12-01

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

  13. The Escherichia coli Peripheral Inner Membrane Proteome*

    PubMed Central

    Papanastasiou, Malvina; Orfanoudaki, Georgia; Koukaki, Marina; Kountourakis, Nikos; Sardis, Marios Frantzeskos; Aivaliotis, Michalis; Karamanou, Spyridoula; Economou, Anastassios

    2013-01-01

    Biological membranes are essential for cell viability. Their functional characteristics strongly depend on their protein content, which consists of transmembrane (integral) and peripherally associated membrane proteins. Both integral and peripheral inner membrane proteins mediate a plethora of biological processes. Whereas transmembrane proteins have characteristic hydrophobic stretches and can be predicted using bioinformatics approaches, peripheral inner membrane proteins are hydrophilic, exist in equilibria with soluble pools, and carry no discernible membrane targeting signals. We experimentally determined the cytoplasmic peripheral inner membrane proteome of the model organism Escherichia coli using a multidisciplinary approach. Initially, we extensively re-annotated the theoretical proteome regarding subcellular localization using literature searches, manual curation, and multi-combinatorial bioinformatics searches of the available databases. Next we used sequential biochemical fractionations coupled to direct identification of individual proteins and protein complexes using high resolution mass spectrometry. We determined that the proposed cytoplasmic peripheral inner membrane proteome occupies a previously unsuspected ?19% of the basic E. coli BL21(DE3) proteome, and the detected peripheral inner membrane proteome occupies ?25% of the estimated expressed proteome of this cell grown in LB medium to mid-log phase. This value might increase when fleeting interactions, not studied here, are taken into account. Several proteins previously regarded as exclusively cytoplasmic bind membranes avidly. Many of these proteins are organized in functional or/and structural oligomeric complexes that bind to the membrane with multiple interactions. Identified proteins cover the full spectrum of biological activities, and more than half of them are essential. Our data suggest that the cytoplasmic proteome displays remarkably dynamic and extensive communication with biological membrane surfaces that we are only beginning to decipher. PMID:23230279

  14. Microdiesel: Escherichia coli engineered for fuel production.

    PubMed

    Kalscheuer, Rainer; Stölting, Torsten; Steinbüchel, Alexander

    2006-09-01

    Biodiesel is an alternative energy source and a substitute for petroleum-based diesel fuel. It is produced from renewable biomass by transesterification of triacylglycerols from plant oils, yielding monoalkyl esters of long-chain fatty acids with short-chain alcohols such as fatty acid methyl esters and fatty acid ethyl esters (FAEEs). Despite numerous environmental benefits, a broader use of biodiesel is hampered by the extensive acreage required for sufficient production of oilseed crops. Therefore, processes are urgently needed to enable biodiesel production from more readily available bulk plant materials like sugars or cellulose. Toward this goal, the authors established biosynthesis of biodiesel-adequate FAEEs, referred to as Microdiesel, in metabolically engineered Escherichia coli. This was achieved by heterologous expression in E. coli of the Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase and the unspecific acyltransferase from Acinetobacter baylyi strain ADP1. By this approach, ethanol formation was combined with subsequent esterification of the ethanol with the acyl moieties of coenzyme A thioesters of fatty acids if the cells were cultivated under aerobic conditions in the presence of glucose and oleic acid. Ethyl oleate was the major constituent of these FAEEs, with minor amounts of ethyl palmitate and ethyl palmitoleate. FAEE concentrations of 1.28 g l(-1) and a FAEE content of the cells of 26 % of the cellular dry mass were achieved by fed-batch fermentation using renewable carbon sources. This novel approach might pave the way for industrial production of biodiesel equivalents from renewable resources by employing engineered micro-organisms, enabling a broader use of biodiesel-like fuels in the future. PMID:16946248

  15. The N-degradome of Escherichia coli

    PubMed Central

    Humbard, Matthew A.; Surkov, Serhiy; De Donatis, Gian Marco; Jenkins, Lisa M.; Maurizi, Michael R.

    2013-01-01

    The N-end rule is a conserved mechanism found in Gram-negative bacteria and eukaryotes for marking proteins to be degraded by ATP-dependent proteases. Specific N-terminal amino acids (N-degrons) are sufficient to target a protein to the degradation machinery. In Escherichia coli, the adaptor ClpS binds an N-degron and delivers the protein to ClpAP for degradation. As ClpS recognizes N-terminal Phe, Trp, Tyr, and Leu, which are not found at the N terminus of proteins translated and processed by the canonical pathway, proteins must be post-translationally modified to expose an N-degron. One modification is catalyzed by Aat, an enzyme that adds leucine or phenylalanine to proteins with N-terminal lysine or arginine; however, such proteins are also not generated by the canonical protein synthesis pathway. Thus, the mechanisms producing N-degrons in proteins and the frequency of their occurrence largely remain a mystery. To address these issues, we used a ClpS affinity column to isolate interacting proteins from E. coli cell lysates under non-denaturing conditions. We identified more than 100 proteins that differentially bound to a column charged with wild-type ClpS and eluted with a peptide bearing an N-degron. Thirty-two of 37 determined N-terminal peptides had N-degrons. Most of the proteins were N-terminally truncated by endoproteases or exopeptidases, and many were further modified by Aat. The identities of the proteins point to possible physiological roles for the N-end rule in cell division, translation, transcription, and DNA replication and reveal widespread proteolytic processing of cellular proteins to generate N-end rule substrates. PMID:23960079

  16. RAPID GLUTAMATE DECARBOXYLASE ASSAY FOR THE DETECTION OF ESCHERICHIA COLI

    EPA Science Inventory

    A rapid test procedure for the enzyme glutamate decarboxylase was developed for the detection of Escherichia coli. he assay procedure was able to confirm the presence of E. coli in enteric broth cultures with a 95 percent specificity for both pure cultures and environmental sampl...

  17. Response of Escherichia coli growth rate to osmotic shock

    E-print Network

    Das, Rhiju

    - and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rateResponse of Escherichia coli growth rate to osmotic shock Enrique Rojasa,b,c , Julie A. Theriotb

  18. Molecular Serotyping of Escherichia coli O111:H8

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate Escherichia coli serotyping is critical for pathogen diagnosis and surveillance of non-O157 shiga-toxigenic strains, however, few laboratories have this capacity. The molecular serotyping protocol described in this paper targets the somatic and flagellar antigens of E. coli O111:H8 used in...

  19. Complete Genome Sequence of Enterotoxigenic Escherichia coli Myophage Murica

    PubMed Central

    Wilder, Joseph N.; Lancaster, Jacob C.; Cahill, Jesse L.; Rasche, Eric S.

    2015-01-01

    Murica is an rv5-like myophage that infects enterotoxigenic Escherichia coli. Pathogenic E. coli strains are responsible for many intestinal diseases, and phages that infect these bacteria may prove useful in preventing severe health issues. The following is a report of the complete genome sequence of Murica and its important features. PMID:26430048

  20. Properties and Transport Behavior among 12 Different Environmental Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli is a commonly used indicator organism for detecting the presence of fecal-borne pathogenic microorganisms in water supplies. The importance of E. coli as an indicator organism has led to numerous studies looking at cell properties and transport behavior of this microorganism. In man...

  1. Escherichia coli with Resistance Factors in Vegetarians, Babies, and Nonvegetarians

    PubMed Central

    Guinée, P.; Ugueto, N.; van Leeuwen, N.

    1970-01-01

    The prevalence of Escherichia coli carrying resistance factors (R factors) was examined in meat-consuming individuals and in those not consuming meat (vegetarians and babies below the age of 6 months). Assuming that the transport of resistant E. coli from animals through meat and meat products to the human consumer is most important, with regard to the incidence of resistant E. coli in man, we expected a significant difference in the proportions of people with resistant E. coli between the two groups. However, the percentage with resistant E. coli was larger in the group of vegetarians and babies than in the group of meat-eating individuals. PMID:4926439

  2. Oligosaccharide Binding in Escherichia coli Glycogen Synthase

    SciTech Connect

    Sheng, Fang; Yep, Alejandra; Feng, Lei; Preiss, Jack; Geiger, James H.

    2010-11-17

    Glycogen/starch synthase elongates glucan chains and is the key enzyme in the synthesis of glycogen in bacteria and starch in plants. Cocrystallization of Escherichia coli wild-type glycogen synthase (GS) with substrate ADPGlc and the glucan acceptor mimic HEPPSO produced a closed form of GS and suggests that domain-domain closure accompanies glycogen synthesis. Cocrystallization of the inactive GS mutant E377A with substrate ADPGlc and oligosaccharide results in the first oligosaccharide-bound glycogen synthase structure. Four bound oligosaccharides are observed, one in the interdomain cleft (G6a) and three on the N-terminal domain surface (G6b, G6c, and G6d). Extending from the center of the enzyme to the interdomain cleft opening, G6a mostly interacts with the highly conserved N-terminal domain residues lining the cleft of GS. The surface-bound oligosaccharides G6c and G6d have less interaction with enzyme and exhibit a more curled, helixlike structural arrangement. The observation that oligosaccharides bind only to the N-terminal domain of GS suggests that glycogen in vivo probably binds to only one side of the enzyme to ensure unencumbered interdomain movement, which is required for efficient, continuous glucan-chain synthesis.

  3. Iron transport and signaling in Escherichia coli.

    PubMed

    Braun, Volkmar; Braun, Michael

    2002-10-01

    Bacteria solve the iron supply problem caused by the insolubility of Fe(3+) by synthesizing iron-complexing compounds, called siderophores, and by using iron sources of their hosts, such as heme and iron bound to transferrin and lactoferrin. Escherichia coli, as an example of Gram-negative bacteria, forms sophisticated Fe(3+)-siderophore and heme transport systems across the outer membrane. The crystal structures of three outer membrane transport proteins now allow insights into energy-coupled transport mechanisms. These involve large long-range structural transitions in the transport proteins in response to substrate binding, including substrate gating. Energy is provided by the proton motive force of the cytoplasmic membrane through the activity of a protein complex that is inserted in the cytoplasmic membrane and that contacts the outer membrane transporters. Certain transport proteins also function in siderophore-mediated signaling cascades that start at the cell surface and flow to the cytoplasm to initiate transcription of genes encoding proteins for transport and siderophore biosynthesis. PMID:12354617

  4. Shiga toxin-producing Escherichia coli

    PubMed Central

    Etcheverría, Analía Inés; Padola, Nora Lía

    2013-01-01

    Shiga toxin-producing Escherichia coli (STEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in humans. Outbreaks are linked to bovine food sources. STEC O157:H7 has been responsible for the most severe outbreaks worldwide. However, non-O157 serotypes have emerged as important enteric pathogens in several countries. The main virulence factor of STEC is the production of Shiga toxins 1 and 2. Additional virulence markers are a plasmid-encoded enterohemolysin (ehxA), an autoagglutinating adhesin (Saa), a catalase-peroxidase (katP), an extracellular serine protease (espP), a zinc metalloprotease (stcE), a subtilase cytotoxin (subAB), among others. Other virulence factors are intimin and adhesins that had a roll in the adherence of STEC to bovine colon. This review focuses on the virulence traits of STEC and especially on those related to the adhesion to bovine colon. The known of the interaction between STEC and the bovine host is crucial to develop strategies to control cattle colonization. PMID:23624795

  5. Biochemistry of homologous recombination in Escherichia coli.

    PubMed Central

    Kowalczykowski, S C; Dixon, D A; Eggleston, A K; Lauder, S D; Rehrauer, W M

    1994-01-01

    Homologous recombination is a fundamental biological process. Biochemical understanding of this process is most advanced for Escherichia coli. At least 25 gene products are involved in promoting genetic exchange. At present, this includes the RecA, RecBCD (exonuclease V), RecE (exonuclease VIII), RecF, RecG, RecJ, RecN, RecOR, RecQ, RecT, RuvAB, RuvC, SbcCD, and SSB proteins, as well as DNA polymerase I, DNA gyrase, DNA topoisomerase I, DNA ligase, and DNA helicases. The activities displayed by these enzymes include homologous DNA pairing and strand exchange, helicase, branch migration, Holliday junction binding and cleavage, nuclease, ATPase, topoisomerase, DNA binding, ATP binding, polymerase, and ligase, and, collectively, they define biochemical events that are essential for efficient recombination. In addition to these needed proteins, a cis-acting recombination hot spot known as Chi (chi: 5'-GCTGGTGG-3') plays a crucial regulatory function. The biochemical steps that comprise homologous recombination can be formally divided into four parts: (i) processing of DNA molecules into suitable recombination substrates, (ii) homologous pairing of the DNA partners and the exchange of DNA strands, (iii) extension of the nascent DNA heteroduplex; and (iv) resolution of the resulting crossover structure. This review focuses on the biochemical mechanisms underlying these steps, with particular emphases on the activities of the proteins involved and on the integration of these activities into likely biochemical pathways for recombination. Images PMID:7968921

  6. Regulation of alcohol fermentation by Escherichia coli

    SciTech Connect

    Clark, D.P.

    1986-03-01

    The purpose of this project is to elucidate the way in which the fermentative synthesis of ethanol is regulated in the facultative anaerobe Escherichia coli. Focus is on the two final steps in alcohol synthesis, which are catalyzed by alcohol dehydrogenase and acetaldehyde CoA dehydrogenase. We have isolated a series of mutations affecting the expression of these enzymes. Some of these mutations are in the structural genes for these enzymes; others affect the regulation of the adh operon. We have recently cloned the genes coding for these enzymes and are now studying the effect of multiple copies of the adh gene on fermentative growth and its regulation. A recently invented technique, proton suicide has allowed the selection of a variety of novel mutants affecting fermentation which are presently being characterized. We have isolated a comprehensive collection of operon fusions in which the lacZ structural gene is fused to promoters that are inactive aerobically but active anaerobically. Although these genes (like adh) are only expressed under anaerobic conditions, the level of induction varies from two-fold to nearly 100-fold. The nitrogen source, medium pH, nature of the buffer, presence of alternative electron acceptors (e.g., nitrate), and other factors exert a great effect on the expression of many of these genes. In the near future we will investigate control mechanisms common to the adh operon and other anaerobically regulated genes.

  7. Elasticity of the sacculus of Escherichia coli.

    PubMed Central

    Koch, A L; Woeste, S

    1992-01-01

    Preparations of purified peptidoglycan of Escherichia coli (i.e., sacculi) were studied by low-angle laser light scattering. Control experiments and theoretical calculations based on the Rayleigh-Gans theory showed that the mean sacculus surface area could be accurately inferred from measurements with our apparatus by using computer routines developed previously. Large changes in the mean saccular surface area resulted from alterations in the stress caused by varying the net charge on the sacculi. The net charge was affected by altering the suspending medium pH, causing carboxyl and amino groups in the peptidoglycan to gain or lose protons, or by acetylation or succinylation of the amino groups. A preponderance of either plus or minus charges caused an expansion of the mean sacculus surface area. The largest increase in area probably represents the elastic limit of the peptidoglycan and was 300% above the area of isoionic sacculi. This degree of expansion is consistent with possible conformations of the intact peptidoglycan structure without necessitating rupture of the wall fabric. Our findings concerning saccular elasticity provide support for the surface stress theory. It provides a mechanism so that bacteria can grow and divide while maintaining turgor pressure, without the necessity of having and using proteins to do the mechanical work. PMID:1624468

  8. Physical Properties of Escherichia coli Spheroplast Membranes

    PubMed Central

    Sun, Yen; Sun, Tzu-Lin; Huang, Huey W.

    2014-01-01

    We investigated the physical properties of bacterial cytoplasmic membranes by applying the method of micropipette aspiration to Escherichia coli spheroplasts. We found that the properties of spheroplast membranes are significantly different from that of laboratory-prepared lipid vesicles or that of previously investigated animal cells. The spheroplasts can adjust their internal osmolality by increasing their volumes more than three times upon osmotic downshift. Until the spheroplasts are swollen to their volume limit, their membranes are tensionless. At constant external osmolality, aspiration increases the surface area of the membrane and creates tension. What distinguishes spheroplast membranes from lipid bilayers is that the area change of a spheroplast membrane by tension is a relaxation process. No such time dependence is observed in lipid bilayers. The equilibrium tension-area relation is reversible. The apparent area stretching moduli are several times smaller than that of stretching a lipid bilayer. We conclude that spheroplasts maintain a minimum surface area without tension by a membrane reservoir that removes the excessive membranes from the minimum surface area. Volume expansion eventually exhausts the membrane reservoir; then the membrane behaves like a lipid bilayer with a comparable stretching modulus. Interestingly, the membranes cease to refold when spheroplasts lost viability, implying that the membrane reservoir is metabolically maintained. PMID:25418093

  9. 77 FR 31975 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-31

    ... Service 9 CFR Parts 416, 417, and 430 Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products... toxin-producing Escherichia coli (STEC), in addition to E. coli O157:H7, in raw beef manufacturing... toxin-producing Escherichia coli (STEC) O26, O45, O103, O111, O121, and O145 are adulterated within...

  10. Involvement of Escherichia coli DNA polymerase IV in tolerance of cytotoxic alkylating DNA lesions in vivo

    E-print Network

    1 Involvement of Escherichia coli DNA polymerase IV in tolerance of cytotoxic alkylating DNA coli DNA polymerase IV Key words: Escherichia coli, dinB, alkylation damage, DNA repair Corresponding Escherichia coli PolIV, a DNA polymerase capable to catalyze synthesis past replication- blocking DNA lesions

  11. Evolution of transcription factors and the gene regulatory network in Escherichia coli

    E-print Network

    Babu, M. Madan

    Evolution of transcription factors and the gene regulatory network in Escherichia coli M. Madan Escherichia coli. In order to gain insight into the evolution of the E.coli regula- tory network, we analysed-dimensional structures. Theoretical analyses of transcription factors in Escherichia coli have focused on their sequence

  12. Predicting non-coding RNA genes in Escherichia coli with boosted genetic programming

    E-print Network

    Fernandez, Thomas

    Predicting non-coding RNA genes in Escherichia coli with boosted genetic programming Pa°l Sætrom Several methods exist for predicting non-coding RNA (ncRNA) genes in Escherichia coli (E.coli important roles beyond protein synthesis (rRNA and tRNA) (1­5). In Escherichia coli, the number

  13. Soil solarization reduces Escherichia coli O157:H7 and total Escherichia coli on cattle feedlot pen surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Feedlot pen soils are a source for transmission of Escherichia coli O157:H7, and therefore a target for preharvest strategies to reduce this pathogen in cattle. The objective of this study was to determine the ability of soil solarization to reduce E. coli O157:H7 in feedlot surface material (FSM)....

  14. Transcription of the Escherichia coli fliC gene is regulated by metal ions

    SciTech Connect

    Guzzo, A.; Diorio, C.; DuBow, M.S. )

    1991-08-01

    luxAB gene fusions in the Escherichia coli genome were used to screen for clones displaying transcriptional changes in the presence of aluminum. One clone was found that contained a luciferase gene fusion in which transcription was increased in the presence of aluminum and which was subsequently shown to be induced by copper, iron, and nickel. Cloning of the metal-regulated gene, hybridization to the ordered phage {lambda} bank of the E. coli chromosome, and sequencing of DNA adjacent to the luxAB fusion revealed that the insertion occurred within the fliC (hag) gene of E. coli. This gene encodes flagellin the filament subunit of the bacterial motility organ, and is under the control of several regulatory cascades. These results suggest that environmental metals may play a role in the regulation of the motility potential of E. coli and that this bioluminescent gene fusion clone (or derivatives thereof) may be used to prepare a biosensor for the rapid detection of metal contamination in water samples.

  15. Very slow growth of Escherichia coli.

    PubMed Central

    Chesbro, W; Evans, T; Eifert, R

    1979-01-01

    A recycling fermentor (a chemostat with 100% biomass feedback) was used to study glucose-limited behavior of Escherichia coli B. The expectation from mass transfer analysis that growth would asymptotically approach a limit mass determined by the glucose provision rate (GPR) and the culture's maintenance requirement was not met. Instead, growth proceeded at progressively lower rates through three distinct phases. After the fermentor was seeded, but before glucose became limiting, growth followed the usual, exponential path (phase 1). About 12 h postseeding, residual glucose in the fermentor fell below 1 microgram . ml-1 and the growth rate (dx/dt) became constant and a linear function of GPR (phase 2). The specific growth rate, mu, therefore fell continuously throughout the phase. Biomass yield and glucose assimilation (13%) were near the level for exponential growth, however, and independent of GPR over a broad range. At a critical specific growth rate (0.04 h-1 for this strain), phase 2 ended abruptly and phase 3 commenced. In phase 3, the growth rate was again constant, although lower than in phase 2, so that mu continued to fall, but growth rates and yields were praboloid functions of GPR. They were never zero, however, at any positive value of GPR. By inference, the fraction of metabolic energy used for maintenance functions is constant for a given GPR, although different for phases 2 and 3, and independent of biomass. In both phases 2 and 3, orcinol, diphenylamine, and Lowry reactive materials were secreted at near-constant rates such that over 50% as much biosynthetic mass was secreted as was retained by the cells. Images PMID:378981

  16. Rapid Sterilization of Escherichia coli by Solution Plasma Process

    NASA Astrophysics Data System (ADS)

    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.

  17. Toxicity of Graphene Shells, Graphene Oxide, and Graphene Oxide Paper Evaluated with Escherichia coli Biotests

    PubMed Central

    Efremova, Ludmila V.; Vasilchenko, Alexey S.; Rakov, Eduard G.; Deryabin, Dmitry G.

    2015-01-01

    The plate-like graphene shells (GS) produced by an original methane pyrolysis method and their derivatives graphene oxide (GO) and graphene oxide paper (GO-P) were evaluated with luminescent Escherichia coli biotests and additional bacterial-based assays which together revealed the graphene-family nanomaterials' toxicity and bioactivity mechanisms. Bioluminescence inhibition assay, fluorescent two-component staining to evaluate cell membrane permeability, and atomic force microscopy data showed GO expressed bioactivity in aqueous suspension, whereas GS suspensions and the GO-P surface were assessed as nontoxic materials. The mechanism of toxicity of GO was shown not to be associated with oxidative stress in the targeted soxS::lux and katG::lux reporter cells; also, GO did not lead to significant mechanical disruption of treated bacteria with the release of intracellular DNA contents into the environment. The well-coordinated time- and dose-dependent surface charge neutralization and transport and energetic disorders in the Escherichia coli cells suggest direct membrane interaction, internalization, and perturbation (i.e., “membrane stress”) as a clue to graphene oxide's mechanism of toxicity. PMID:26221608

  18. Photodynamic inactivation of Escherichia coli with cationic ammonium Zn(II) phthalocyanines.

    PubMed

    Rocha, Deisy M G C; Venkatramaiah, N; Gomes, Maria C; Almeida, Adelaide; Faustino, Maria A F; Almeida Paz, Filipe A; Cunha, Ângela; Tomé, João P C

    2015-10-01

    The aim of this work was the development of a family of novel water soluble Zinc(II) phthalocyanines (Pc) for the photodynamic inactivation of Gram-negative bacteria. Pc derivatives 1a, 2a and 3a containing trimethylammonium groups with varied number and nature of the groups at peripheral positions were synthesized by cyclotetramerization of dimethyl amino substituted phthalonitriles in the presence of zinc powder, using 1-chloronaphthalene as a solvent, followed by cationization using dimethyl sulfate. The solubility, singlet oxygen generation ((1)O2) and stability/photostability of each Pc were evaluated as well as the affinity to bacterial cells and their photosensitizing potential against a recombinant bioluminescent Escherichia coli strain, used as a biological model for Gram negative bacteria. The efficiency of photodynamic inactivation was assessed under white and red light at an irradiance of 150 mW cm(-2). All Pc were soluble in phosphate buffer saline and in dimethyl sulfoxide and demonstrated good stability/photostability. The photochemical parameters reveal that Pc 2a and 3a are more efficient singlet oxygen producers than Pc 1a, for which singlet oxygen generation could not be demonstrated. Pc 2a and 3a caused photosensitization in E. coli. The inactivation factors attained with red light were, however, generally higher than those with white light. Under red light Pc 3a and 2a caused, respectively, 5.6 and 4.9?log reduction in the bioluminescence of the E. coli while, with white light, the corresponding inactivation factors were 2.5 and 0.5?log. The order of the PDI efficiency (3a > 2a ? 1a) was determined by the combined effect of solubility, singlet oxygen generation ability and affinity to bacterial cells. Ammonium phthalocyanines with eight charges or containing halogen atoms such as chlorine, when irradiated with red light can, therefore, be regarded as promising photosensitizers for the inactivation of Gram-negative bacteria. PMID:26222379

  19. The Biology of the Escherichia coli Extracellular Matrix

    PubMed Central

    Hufnagel, David A.; DePas, William H.; Chapman, Matthew R.

    2015-01-01

    Chapter Summary Escherichia coli (E. coli) is one of the world’s best-characterized organisms, as it has been extensively studied for over a century. However, most of this work has focused on E. coli grown under laboratory conditions that do not faithfully simulate its natural environments. Therefore, the historical perspectives on E. coli physiology and life cycle are somewhat skewed toward experimental systems that feature E. coli growing logarithmically in a test tube. Typically a commensal bacterium, E. coli resides in the lower intestines of a slew of animals. Outside of the lower intestine, E. coli can adapt and survive in a very different set of environmental conditions. Biofilm formation allows E. coli to survive, and even thrive, in environments that do not support the growth of planktonic populations. E. coli can form biofilms virtually everywhere; in the bladder during a urinary tract infection, on in-dwelling medical devices, and outside of the host on plants and in the soil. The E. coli extracellular matrix, primarily composed of the protein polymer named curli and the polysaccharide cellulose, promotes adherence to organic and inorganic surfaces, and resistance to desiccation, the host immune system and other antimicrobials. The pathways that govern E. coli biofilm formation, cellulose production, and curli biogenesis will be discussed in this book chapter, which concludes with insights into the future of E. coli biofilm research and potential therapies. PMID:26185090

  20. The Evolution and Structural Anatomy of the Small Molecule Metabolic Pathways in Escherichia coli

    E-print Network

    Gough, Julian

    The Evolution and Structural Anatomy of the Small Molecule Metabolic Pathways in Escherichia coli The 106 small molecule metabolic (SMM) pathways in Escherichia coli are formed by the protein products

  1. Recent advances in adherence and invasion of pathogenic Escherichia coli

    PubMed Central

    Kalita, Anjana; Hu, Jia; Torres, Alfredo G.

    2014-01-01

    Purpose of review Colonization of the host epithelia by pathogenic Escherichia coli is influenced by the ability of the bacteria to interact with host surfaces. Because the initial step of an E. coli infection is to adhere, invade, and persist within host cells, some strategies used by intestinal and extra-intestinal E. coli to infect host cell are presented. Recent findings This review highlights recent progress understanding how extra-intestinal pathogenic E. coli strains express specific adhesins/invasins that allow colonization of the urinary tract or the meninges, while intestinal E. coli strains are able to colonize different regions of the intestinal tract using other specialized adhesins/invasins. Finally, evaluation of, different diets and environmental conditions regulating the colonization of these pathogens is discussed. Summary Discovery of new interactions between pathogenic E. coli and the host epithelial cells unravels the need of more mechanistic studies that can provide new clues in how to combat these infections. PMID:25023740

  2. The Biology of the Escherichia coli Extracellular Matrix.

    PubMed

    Hufnagel, David A; Depas, William H; Chapman, Matthew R

    2015-06-01

    Escherichia coli is one of the world's best-characterized organisms, because it has been extensively studied for over a century. However, most of this work has focused on E. coli grown under laboratory conditions that do not faithfully simulate its natural environments. Therefore, the historical perspectives on E. coli physiology and life cycle are somewhat skewed toward experimental systems that feature E. coli growing logarithmically in a test tube. Typically a commensal bacterium, E. coli resides in the lower intestines of a slew of animals. Outside of the lower intestine, E. coli can adapt and survive in a very different set of environmental conditions. Biofilm formation allows E. coli to survive, and even thrive, in environments that do not support the growth of planktonic populations. E. coli can form biofilms virtually everywhere: in the bladder during a urinary tract infection, on in-dwelling medical devices, and outside of the host on plants and in the soil. The E. coli extracellular matrix (ECM), primarily composed of the protein polymer named curli and the polysaccharide cellulose, promotes adherence to organic and inorganic surfaces and resistance to desiccation, the host immune system, and other antimicrobials. The pathways that govern E. coli biofilm formation, cellulose production, and curli biogenesis will be discussed in this article, which concludes with insights into the future of E. coli biofilm research and potential therapies. PMID:26185090

  3. Pathogenomics of the Virulence Plasmids of Escherichia coli

    PubMed Central

    Johnson, Timothy J.; Nolan, Lisa K.

    2009-01-01

    Summary: Bacterial plasmids are self-replicating, extrachromosomal elements that are key agents of change in microbial populations. They promote the dissemination of a variety of traits, including virulence, enhanced fitness, resistance to antimicrobial agents, and metabolism of rare substances. Escherichia coli, perhaps the most studied of microorganisms, has been found to possess a variety of plasmid types. Included among these are plasmids associated with virulence. Several types of E. coli virulence plasmids exist, including those essential for the virulence of enterotoxigenic E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterohemorrhagic E. coli, enteroaggregative E. coli, and extraintestinal pathogenic E. coli. Despite their diversity, these plasmids belong to a few plasmid backbones that present themselves in a conserved and syntenic manner. Thanks to some recent research, including sequence analysis of several representative plasmid genomes and molecular pathogenesis studies, the evolution of these virulence plasmids and the implications of their acquisition by E. coli are now better understood and appreciated. Here, work involving each of the E. coli virulence plasmid types is summarized, with the available plasmid genomic sequences for several E. coli pathotypes being compared in an effort to understand the evolution of these plasmid types and define their core and accessory components. PMID:19946140

  4. Genes and proteins of Escherichia coli K-12.

    PubMed

    Riley, M

    1998-01-01

    GenProtEC is a database of Escherichia coli genes and their gene products, classified by type of function and physiological role and with citations to the literature for each. Also present are data on sequence similarities among E.coli proteins, representing groups of paralogous genes, with PAM values, percent identity of amino acids, length of alignment and percent aligned. GenProtEC can be accessed at the URL http://www.mbl.edu/html/ecoli.html PMID:9399799

  5. Edinburgh Research Explorer Adaptation of anaerobic cultures of Escherichia coli K-12 in

    E-print Network

    Millar, Andrew J.

    Edinburgh Research Explorer Adaptation of anaerobic cultures of Escherichia coli K-12 in response, G, Poole, RK & Green, J 2015, 'Adaptation of anaerobic cultures of Escherichia coli K-12 in response cultures of Escherichia coli K-12 in response to environmental trimethylamine-N-oxide Katie J. Denby,1

  6. Chemosensing in Escherichia coli: Two regimes of two-state receptors

    E-print Network

    Meir, Yigal

    Chemosensing in Escherichia coli: Two regimes of two-state receptors Juan E. Keymer* , Robert G, 2005 (received for review August 26, 2005) The chemotaxis network in Escherichia coli is remarkable The chemotaxis network in Escherichia coli is the best studied signal-transduction network of any living organism

  7. Selection Footprint in the FimH Adhesin Shows Pathoadaptive Niche Differentiation in Escherichia coli

    E-print Network

    Chattopadhyay, Sujay

    -adaptive, or pathoadaptive, mutations in the Escherichia coli gene encoding FimH--the major, mannose-sensitive adhesin protein of Escherichia coli, mutations in which are pathoadaptive for uropatho- genic E. coli clonesSelection Footprint in the FimH Adhesin Shows Pathoadaptive Niche Differentiation in Escherichia

  8. Author's personal copy Improving cellular malonyl-CoA level in Escherichia coli

    E-print Network

    Zhao, Huimin

    Author's personal copy Improving cellular malonyl-CoA level in Escherichia coli via metabolic a b s t r a c t Escherichia coli only maintains a small amount of cellular malonyl-CoA, impeding its, Escherichia coli has become an attractive host for natural product manufac- ture, owing to its genetic

  9. Natural DNA Uptake by Escherichia coli Sunita Sinha*, Rosemary J. Redfield

    E-print Network

    Redfield, Rosemary J. "Rosie"

    Natural DNA Uptake by Escherichia coli Sunita Sinha*, Rosemary J. Redfield Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada Abstract Escherichia coli has homologues by Escherichia coli. PLoS ONE 7(4): e35620. doi:10.1371/journal.pone.0035620 Editor: Anthony R. Poteete

  10. Proteome analysis of factor for inversion stimulation (Fis) overproduction in Escherichia coli

    E-print Network

    Chen, Wilfred

    Proteome analysis of factor for inversion stimulation (Fis) overproduction in Escherichia coli The factor-for-inversion stimulation protein (Fis) is a global regulatory protein in Escherichia coli protein precursor, and ketol-acid reductoisomerase. Keywords: Proteome analysis / Fis / Escherichia coli

  11. Understanding and Harnessing the Microaerobic Metabolism of Glycerol in Escherichia coli

    E-print Network

    Alvarez, Pedro J.

    ARTICLE Understanding and Harnessing the Microaerobic Metabolism of Glycerol in Escherichia coli by Escherichia coli could be an excellent platform for this purpose but it requires expensive nutrients­161. ß 2008 Wiley Periodicals, Inc. KEYWORDS: glycerol metabolism; Escherichia coli; meta- bolic

  12. Uncharacterized Escherichia coli proteins YdjA and YhjY are related to biohydrogen production

    E-print Network

    Wood, Thomas K.

    Uncharacterized Escherichia coli proteins YdjA and YhjY are related to biohydrogen production Mohd: Biohydrogen Escherichia coli ydjA yhjY FHL inactivation a b s t r a c t Biohydrogen has gained importance and efficiency of biohydrogen production from various microorganisms and substrates. Here, Escherichia coli

  13. An Experimental and Theoretical Study of the Inhibition of Escherichia coli lac

    E-print Network

    Relue, Patricia

    An Experimental and Theoretical Study of the Inhibition of Escherichia coli lac Operon Gene the inhibition of Escherichia coli lac operon gene expression by anti- gene oligos. Our model predicted 74: 220­229, 2001. Keywords: Escherichia coli lac operon; antigene oligo- nucleotide; triplex

  14. DNA modication and functional delivery into human cells using Escherichia coli DH10B

    E-print Network

    Warburton, Peter E.

    DNA modi®cation and functional delivery into human cells using Escherichia coli DH10B Kumaran report a novel comprehen- sive Escherichia coli-based vector system for the modi®cation, propagation in recombination- de®cient Escherichia coli DH10B imparts greater stability to the large BAC clones but has made

  15. Metabolism and evolution of Haemophilus influenzae deduced from a whole-genome comparison with Escherichia coli

    E-print Network

    Fernando, Chrisantha

    with Escherichia coli Roman L.Tatusov*§, Arcady R. Mushegian*§, Peer Bork, Nigel P. Brown, William S. Hayes, Mark recently reported. Approximately 75 % of the 4.7 Mb genome sequence of Escherichia coli is also available by Fleischmann et al. [1]. Approximately 75 % of the 4.7 Mb genome sequence of Escherichia coli is also available

  16. 612 Biophysical Journal Volume 85 July 2003 612622 Why the Phosphotransferase System of Escherichia coli Escapes

    E-print Network

    Peletier, Mark

    of Escherichia coli Escapes Diffusion Limitation Christof Francke,*y Pieter W. Postma,* Hans V. Westerhoff:glucose phosphotransferase system (glucose-PTS) of Escherichia coli in silicon cells of various magnitudes. For a cell eukaryotic cells. A typical Escherichia coli B/r cell has dimensions of ;1 3 3 mm (Nanninga, 1998), whereas

  17. Motility of Escherichia coli cells in clusters formed by chemotactic aggregation

    E-print Network

    van Oudenaarden, Alexander

    Motility of Escherichia coli cells in clusters formed by chemotactic aggregation Nikhil Mittal of Escherichia coli under conditions of certain cellular stresses excrete attractants. Cells of chemotactic Escherichia coli and Salmonella spp., have been studied in great detail (1­3). For our purposes, the following

  18. Dynamic Receptor Team Formation Can Explain the High Signal Transduction Gain in Escherichia coli

    E-print Network

    Othmer, Hans

    Dynamic Receptor Team Formation Can Explain the High Signal Transduction Gain in Escherichia coli in the peritrichous bacterium Escherichia coli, which has four helical flagella distributed over the cell surface explain this observation. INTRODUCTION Escherichia coli has five receptor types, but most is known about

  19. Escherichia coli in disguise: molecular origins of Shigella Ruiting Lan 1

    E-print Network

    Lan, Ruiting

    Review Escherichia coli in disguise: molecular origins of Shigella Ruiting Lan 1 , Peter R. Reeves belongs to the extremely diverse species Escherichia coli. There are several lineages of Shigella strains. All rights reserved. Keywords: Shigella; Escherichia coli; Evolution; Classification 1. Introduction

  20. ORIGINAL ARTICLE Identification of stress-related proteins in Escherichia coli

    E-print Network

    Wood, Thomas K.

    ORIGINAL ARTICLE Identification of stress-related proteins in Escherichia coli using the pollutant observed in Escherichia coli; for example, a rapid shift from low to high temperatures induces biofilm formation has also been demonstrated Keywords cis-dichloroethylene, Escherichia coli, hydrogen

  1. Effects of Discontinuities in the DNA Template on Abortive Initiation and Promoter Escape by Escherichia coli

    E-print Network

    Tullius, Thomas D.

    by Escherichia coli RNA Polymerase* Received for publication,March 22, 2007, and in revised form, July 20, 2007 related to the process of transcription initiation by Escherichia coli RNA polymerase, confirming transcribing complexes (ITCs)2 of Escherichia coli RNA polymerase bearing 5­8-nt transcripts revealed

  2. Finite state abstraction of a stochastic model of the lactose regulation system of Escherichia coli

    E-print Network

    Pappas, George J.

    Finite state abstraction of a stochastic model of the lactose regulation system of Escherichia coli on the lactose regulation system in Escherichia coli bacteria, one of the most extensively studied examples hybrid model for the lactose regulation system in the Escherichia coli bacteria. The lactose operon [10

  3. Cross-reaction of chalcone synthase and stilbene synthase overexpressed in Escherichia coli

    E-print Network

    Suh, Dae-Yeon

    Cross-reaction of chalcone synthase and stilbene synthase overexpressed in Escherichia coli Toshio STS overexpressed in Escherichia coli, bisnoryangonin (BNY, the derailed lactone after two that was overexpressed in Escherichia coli, we have detected bisnoryangonin (BNY, the derailed lactone after two

  4. Prevalence of Escherichia coli O157:H7 and Salmonella spp. in surface waters of southern

    E-print Network

    Selinger, Brent

    Prevalence of Escherichia coli O157:H7 and Salmonella spp. in surface waters of southern Alberta. To address these concerns, we conducted a 2-year study to estimate the prevalence of Escherichia coli O157:H7 afin d'évaluer la prévalence de Escherichia coli O157:H7 et de Salmonella spp. dans les eaux de surface

  5. Synonymous Codon Usage in Escherichia coli: Selection for Translational Nina Stoletzki* and Adam Eyre-Walker

    E-print Network

    Eyre-Walker, Adam

    Synonymous Codon Usage in Escherichia coli: Selection for Translational Accuracy Nina Stoletzki use in Escherichia coli is biased to reduce the costs of both missense and nonsense translational for this is two-fold. First, in several organisms, including Escherichia coli, Saccharomyces cerevisiae

  6. Imaging whole Escherichia coli bacteria by using single-particle x-ray diffraction

    E-print Network

    Miao, Jianwei "John"

    Imaging whole Escherichia coli bacteria by using single-particle x-ray diffraction Jianwei Miao Escherichia coli bacteria using coherent x-rays with a wavelength of 2 Å. By using the oversam- pling phasing successful experiment, to our knowledge, of imaging Escherichia coli bacteria at 30-nm resolution by using

  7. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ...FSIS-2010-0023] Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food...non-O157 Shiga toxin-producing Escherichia coli in raw, intact and non-intact beef products...non-O157 Shiga toxin-producing Escherichia coli in raw, intact and non-intact beef...

  8. Identification of oligonucleotide sequences that direct the movement of the Escherichia coli FtsK translocase

    E-print Network

    Gore, Jeff

    Identification of oligonucleotide sequences that direct the movement of the Escherichia coli Fts, October 13, 2005 FtsK from Escherichia coli is a fast and sequence-directed DNA translocase with roles where they then carry out a specific action (1). In contrast, the Escherichia coli DNA translocase Fts

  9. Comparison of the PhoPQ Regulon in Escherichia coli and Salmonella typhimurium

    E-print Network

    Comparison of the PhoPQ Regulon in Escherichia coli and Salmonella typhimurium Pieter Monsieurs,1 as a transcriptional regulator that responds to Mg2+ starvation both in Escherichia coli and Salmonella typhimurium.g., pathogenesis in S. typhimurium). Key words: PhoPQ regulon -- Escherichia coli -- Salmonella typhimirium

  10. An integrated database to support research on Escherichia coli

    SciTech Connect

    Baehr, A.; Dunham, G.; Matsuda, Hideo; Michaels, G.; Taylor, R.; Overbeek, R.; Rudd, K.E.; Ginsburg, A.; Joerg, D.; Kazic, T.; Hagstrom, R.; Zawada, D.; Smith, C.; Yoshida, Kaoru

    1992-01-01

    We have used logic programming to design and implement a prototype database of genomic information for the model bacterial organism Escherichia coli. This report presents the fundamental database primitives that can be used to access and manipulate data relating to the E. coli genome. The present system, combined with a tutorial manual, provides immediate access to the integrated knowledge base for E. coli chromosome data. It also serves as the foundation for development of more user-friendly interfaces that have the same retrieval power and high-level tools to analyze complex chromosome organization.

  11. Sources of Escherichia coli in a Coastal Subtropical Environment

    PubMed Central

    Solo-Gabriele, Helena M.; Wolfert, Melinda A.; Desmarais, Timothy R.; Palmer, Carol J.

    2000-01-01

    Sources of Escherichia coli in a coastal waterway located in Ft. Lauderdale, Fla., were evaluated. The study consisted of an extensive program of field measurements designed to capture spatial and temporal variations in E. coli concentrations as well as experiments conducted under laboratory-controlled conditions. E. coli from environmental samples was enumerated by using a defined substrate technology (Colilert-18). Field sampling tasks included sampling the length of the North Fork to identify the river reach contributing high E. coli levels, autosampler experiments at two locations, and spatially intense sampling efforts at hot spots. Laboratory experiments were designed to simulate tidal conditions within the riverbank soils. The results showed that E. coli entered the river in a large pulse during storm conditions. After the storm, E. coli levels returned to baseline levels and varied in a cyclical pattern which correlated with tidal cycles. The highest concentrations were observed during high tide, whereas the lowest were observed at low tide. This peculiar pattern of E. coli concentrations between storm events was caused by the growth of E. coli within riverbank soils which were subsequently washed in during high tide. Laboratory analysis of soil collected from the riverbanks showed increases of several orders of magnitude in soil E. coli concentrations. The ability of E. coli to multiply in the soil was found to be a function of soil moisture content, presumably due to the ability of E. coli to outcompete predators in relatively dry soil. The importance of soil moisture in regulating the multiplication of E. coli was found to be critical in tidally influenced areas due to periodic wetting and drying of soils in contact with water bodies. Given the potential for growth in such systems, E. coli concentrations can be artificially elevated above that expected from fecal impacts alone. Such results challenge the use of E. coli as a suitable indicator of water quality in tidally influenced areas located within tropical and subtropical environments. PMID:10618229

  12. Identification and quantification of toxic chemicals by use of Escherichia coli carrying lux genes fused to stress promoters

    SciTech Connect

    Ben-Israel, O.; Ben-Israel, H.; Ulitzur, S.

    1998-11-01

    The luxCDABE bioluminescence genes of the Vibrio fischeri lux system have been used as a reporter system for different stress and regulatory promoters of Escherichia coli. Selected E. coli strains carrying lux genes fused to different promoters were exposed to various toxic chemicals, and the recorded luminescence was used for the characterization of the biologic signature of each compound. Analysis of these data with the aid of a proper algorithm allowed quantitative and qualitative assessment of toxic chemicals. Of the 25 tested chemicals, 23 were identified by this novel strategy in a 3-h procedure. This system can also be adapted for the identification of simple mixtures of toxic agents when the biologic signatures of the individual compounds are known. This biologic recognition strategy also provides a tool for evaluating the degree of similarity between the modes of action of different toxic agents.

  13. Analyzing the Escherichia coli Gene Expression Data by a Multilayer Adjusted Tree Organizing Map

    E-print Network

    Gruenwald, Le

    1 Analyzing the Escherichia coli Gene Expression Data by a Multilayer Adjusted Tree Organizing Map on biological data, none of them has examined the Escherichia coli (E. coli) gene expression data. This paper. coli gene expression data. In a semi-supervised manner, MATOM constructs a multilayer map

  14. 76 FR 58157 - Shiga Toxin-Producing Escherichia coli

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...1), under which a meat or meat food product is adulterated if...feasibility of testing ground beef and milk for Shiga-like toxin- producing...Escherichia coli in Ground Beef and Milk by Commercial Enzyme Immunoassay...of Agriculture From American Meat Institute In an August 18,...

  15. Anaerobic Growth Yields of Aerobacter cloacae and Escherichia coli

    PubMed Central

    Hernandez, Eovaldo; Johnson, Marvin J.

    1967-01-01

    Aerobacter cloacae UW-C83 and Escherichia coli K-12 were grown under various anaerobic environments. Yatp values were calculated by determination of cell weights and analyses for fermentation products. These Yatp values are compared with others reported in the literature. Limitation of growth by factors other than adenosine triphosphate supply is discussed. PMID:4963790

  16. Transformation in Escherichia coli: cryogenic preservation of competent cells.

    PubMed Central

    Morrison, D A

    1977-01-01

    Escherichia coli cells prepared for transformation by treatment with cold 0.1 M CaCl2 remained viable and competent after storage at -82 degrees C in 15% glycerol; thawed-cell samples yielded up to 10(6) transformants per microgram of plasmid deoxyribonucleic acid. PMID:334731

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

    EPA Science Inventory

    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...

  18. TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI

    EPA Science Inventory

    The increase in resistance rates to trimehtoprim-sulfamethoxazole (TMP/SMX) in isolates of Escherichia coli has become a matter of increasing concern. This has been particularly true in reference to community acquired urinary tract infections (UTI). This study utilized sewage i...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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. Genome Sequence of Enterotoxigenic Escherichia coli Strain B2C.

    PubMed

    Madhavan, T P Vipin; Steen, Jason A; Hugenholtz, Philip; Sakellaris, Harry

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease around the globe, causing an estimated 380,000 deaths annually. The disease is caused by a wide variety of strains. Here, we report the genome sequence of ETEC strain B2C, which was isolated from an American soldier in Vietnam. PMID:24723709

  1. Genome Sequence of Enterotoxigenic Escherichia coli Strain B2C

    PubMed Central

    Vipin Madhavan, T. P.; Steen, Jason A.; Hugenholtz, Philip

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease around the globe, causing an estimated 380,000 deaths annually. The disease is caused by a wide variety of strains. Here, we report the genome sequence of ETEC strain B2C, which was isolated from an American soldier in Vietnam. PMID:24723709

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

    PubMed Central

    Morcatti Coura, Fernanda; Diniz, Soraia de Araújo; Silva, Marcos Xavier; Mussi, Jamili Maria Suhet; Barbosa, Silvia Minharro; Lage, Andrey Pereira; Heinemann, Marcos Bryan

    2015-01-01

    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. PMID:26421310

  3. Expression of Enteropathogenic Escherichia coli Map Is Significantly Different than That of Other Type III Secreted Effectors In Vivo

    PubMed Central

    Nguyen, Mai; Rizvi, Jason

    2014-01-01

    The enteropathogenic Escherichia coli (EPEC) locus of enterocyte effacement (LEE)-encoded effectors EspF and Map are multifunctional and have an impact on the tight junction barrier while the non-LEE-encoded proteins NleH1 and NleH2 possess significant anti-inflammatory activity. In order to address the temporal expression of these important genes in vivo, their promoters were cloned upstream of the luxCDABE operon, and luciferase expression was measured in EPEC-infected mice by bioluminescence using an in vivo imaging system (IVIS). Bioluminescent images of living mice, of excised whole intestines, and of whole intestines longitudinally opened and washed were assessed. The majority of bioluminescent bacteria localized in the cecum by 3 h postinfection, indicating that the cecum is not only a major colonization site of EPEC but also a site of EPEC effector gene expression in mice. espF, nleH1, and nleH2 were abundantly expressed over the course of infection. In contrast, map expression was suppressed at 2 days postinfection, and at 4 days postinfection it was totally abolished. After 2 to 4 days postinfection, when map is suppressed, EPEC colonization is significantly reduced, indicating that map may be one of the factors required to maintain EPEC colonization. This was confirmed in a competitive colonization study and in two models of chronic infection, repeated exposure to ketamine and Citrobacter rodentium infection. Our data suggest that map expression contributes to the maintenance of EPEC colonization. PMID:25312947

  4. Estimation of Escherichia coli in raw ground beef.

    PubMed

    Stiles, M E; Ng, L K

    1980-08-01

    This study was undertaken to establish and evaluate more rapid methods of estimating Escherichia coli in ground beef than the standard most probable number (MPN) technique. Direct inoculation of and modifications to EC medium gave unreliable estimates of the presumptive E. coli count. Solid media incubated at an elevated temperature were compared to the MPN technique. Anderson and Baird-Parker's tryptone bile agar (TBA) method and prepoured plates of Endo, Levine eosin methylene blue (EMB), and violet red bile (VRBA) agars incubated at 44 degree C gave equivalent counts to the standard MPN method. Anderson and Baird-Parker TBA was the most selective solid medium for E. coli estimation, but all selective media incubated at elevated temperature reduced apparent E. coli counts by as much as 50%. Indole-producing and lactose-fermenting Enterobacteriaceae, capable of growth at elevated temperature, were tested for their growth on TBA, EMB, and VRBA at elevated temperature. TBA was selective for E. coli biotype I compared to other Enterobacteriaceae that predominate in meats. VRBA and EMB incubated at elevated temperature were not as selective as TBA, but differences in colonies could be observed between typical E. coli colonies and other Enterobacteriaceae on these media. Therefore, VRBA incubated at elevated temperature is proposed as a quality assurance screening test for presumptive E. coli in ground meat. Resuscitation techniques and prepoured plates with VRBA increased recovery levels of presumptive E. coli, but, under the conditions of this study, not to levels that represented a significant practical difference. PMID:7008695

  5. Comparison of the transient responses of Escherichia coli to a glucose pulse of various intensities.

    PubMed

    Sunya, Sirichai; Delvigne, Frank; Uribelarrea, Jean-Louis; Molina-Jouve, Carole; Gorret, Nathalie

    2012-08-01

    Dynamic stimulus-responses of Escherichia coli DPD2085, yciG::LuxCDABE reporter strain, to glucose pulses of different intensities (0.08, 0.4 and 1 g?L(-1)) were compared using glucose-limited chemostat cultures at dilution rate close to 0.15 h(-1). After at least five residence times, the steady-state cultures were disturbed by a pulse of glucose, engendering conditions of glucose excess with concomitant oxygen limitation. In all conditions, glucose consumption, acetate and formate accumulations followed a linear relationship with time. The resulting specific uptake and production rates as well as respiratory rates were rapidly increased within the first seconds, which revealed a high ability of E. coli strain to modulate its metabolism to a new environment. For transition from glucose-excess to glucose-limited conditions, the cells rapidly re-established its pseudo-steady state. The dynamics of transient responses at the macroscopic viewpoint were shown to be independent on the glucose pulse intensity in the tested range. On the contrary, the E. coli biosensor yciG::luxCDABE revealed a transcriptional induction of yciG gene promoter depending on the quantities of the glucose added, through in situ and online monitoring of the bioluminescence emitted by the cells. Despite many studies describing the dynamics of the transient response of E. coli to glucose perturbations, it is the first time that a direct comparison is reported, using the same experimental design (strain, medium and experimental set up), to study the impact of the glucose pulse intensity on the dynamics of microbial behaviour regarding growth, respiration and metabolite productions. PMID:22370947

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

    PubMed

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

    2015-09-28

    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. PMID:25975614

  7. Evidence that Escherichia coli accumulates glycine betaine from marine sediments.

    PubMed Central

    Ghoul, M; Bernard, T; Cormier, M

    1990-01-01

    Escherichia coli grew faster in autoclaved marine sediment than in seawater alone. When E. coli was cultivated in sediment diluted with minimal medium M63 at 0.6 M NaCl, supplemented or not supplemented with glucose or with seawater, the osmoprotector glycine betaine was accumulated in the cells. The best growth occurred on glucose. Accumulation of glycine betaine was not observed with E. coli was grown in sterile seawater alone. The fact that E. coli grew better in the sediments than in seawater is attributed somewhat to the high content of organic matter in the sediment but mainly to the accumulation of glycine betaine. Thus, osmoprotection should be considered to be an additional factor in bacterial survival in estuarine sediments. PMID:2407188

  8. Effects of green tea on Escherichia coli as a uropathogen

    PubMed Central

    Noormandi, Afsaneh; Dabaghzadeh, Fatemeh

    2014-01-01

    Escherichia coli is the most common cause of urinary tract infections. The development of antibiotic resistance in E. coli is an important problem. Finding alternative antimicrobial agents from plant extracts has received growing interest. Camellia sinensis is a safe, nontoxic, cheap beverage that has been reported to have antimicrobial effects against various pathogenic bacteria including E. coli. Polyphenolic components of green tea (?? l? chá) have antibacterial activity. Catechins also have synergistic effect with antibiotics such as chloramphenicol, amoxicillin, sulfamethoxazole, azithromycin, levofloxacin, gentamycin, methicillin, naldixic acid, and, especially ciprofloxacin. In this review, all experimental studies that evaluated the effect of green tea on E. coli were collected. Data from in vitro studies on the antimicrobial effects of green tea are promising, but human data are currently lacking. In vivo studies on antibacterial effects of green tea and evaluating the efficacy of its catechins in the treatment of urinary tract infection are needed. PMID:26151004

  9. Effects of green tea on Escherichia coli as a uropathogen.

    PubMed

    Noormandi, Afsaneh; Dabaghzadeh, Fatemeh

    2015-01-01

    Escherichia coli is the most common cause of urinary tract infections. The development of antibiotic resistance in E. coli is an important problem. Finding alternative antimicrobial agents from plant extracts has received growing interest. Camellia sinensis is a safe, nontoxic, cheap beverage that has been reported to have antimicrobial effects against various pathogenic bacteria including E. coli. Polyphenolic components of green tea ( l? chá) have antibacterial activity. Catechins also have synergistic effect with antibiotics such as chloramphenicol, amoxicillin, sulfamethoxazole, azithromycin, levofloxacin, gentamycin, methicillin, naldixic acid, and, especially ciprofloxacin. In this review, all experimental studies that evaluated the effect of green tea on E. coli were collected. Data from in vitro studies on the antimicrobial effects of green tea are promising, but human data are currently lacking. In vivo studies on antibacterial effects of green tea and evaluating the efficacy of its catechins in the treatment of urinary tract infection are needed. PMID:26151004

  10. Isolation of the Bacteriophage Lambda Receptor from Escherichia coli

    PubMed Central

    Randall-Hazelbauer, L.; Schwartz, M.

    1973-01-01

    A factor which inactivates the phage lambda can be extracted from Escherichia coli. This factor is a protein and is located in the outer membrane of the bacterial envelope. It is found in extracts of strains which are sensitive to phage lambda, but not in extracts of strains specifically resistant to this phage. We conclude that this factor is the lambda receptor, responsible for the specific adsorption of the phage lambda to E. coli cells. A partial purification of the lambda receptor is described. Inactivation of the phage by purified receptor is shown to be accompanied by the release of deoxyribonucleic acid from the phage. Images PMID:4201774

  11. Escherichia coli as a model active colloid: a practical introduction

    E-print Network

    Schwarz-Linek, Jana; Jepson, Alys; Dawson, Angela; Vissers, Teun; Miroli, Dario; Pilizota, Teuta; Martinez, Vincent A; Poon, Wilson C K

    2015-01-01

    The flagellated bacterium Escherichia coli is increasingly used experimentally as a self-propelled swimmer. To obtain meaningful, quantitative results that are comparable between different laboratories, reproducible protocols are needed to control, `tune' and monitor the swimming behaviour of these motile cells. We critically review the knowledge needed to do so, explain methods for characterising the colloidal and motile properties of E.coli, cells, and propose a protocol for keeping them swimming at constant speed at finite bulk concentrations. In the process of establishing this protocol, we use motility as a high-throughput probe of aspects of cellular physiology via the coupling between swimming speed and the proton motive force.

  12. Genes and proteins of Escherichia coli (GenProtEc).

    PubMed

    Riley, M; Space, D B

    1996-01-01

    GenProtEc is a database of Escherichia coli genes and their gene products, classified by type of function and physiological role and with citations to the literature for each. Also present are data on sequence similarities among E.coli proteins with PAM values, percent identity of amino acids, length of alignment and percent aligned. The database is available as a PKZip file by ftp from mbl.edu/pub/ecoli.exe. The program runs under MS-DOS on IMB-compatible machines. GenProtEc can also be accessed through the World Wide Web at URL http://mbl.edu/html/ecoli.html. PMID:8594596

  13. Escherichia coli as a model active colloid: a practical introduction

    E-print Network

    Jana Schwarz-Linek; Jochen Arlt; Alys Jepson; Angela Dawson; Teun Vissers; Dario Miroli; Teuta Pilizota; Vincent A. Martinez; Wilson C. K. Poon

    2015-06-15

    The flagellated bacterium Escherichia coli is increasingly used experimentally as a self-propelled swimmer. To obtain meaningful, quantitative results that are comparable between different laboratories, reproducible protocols are needed to control, `tune' and monitor the swimming behaviour of these motile cells. We critically review the knowledge needed to do so, explain methods for characterising the colloidal and motile properties of E.coli, cells, and propose a protocol for keeping them swimming at constant speed at finite bulk concentrations. In the process of establishing this protocol, we use motility as a high-throughput probe of aspects of cellular physiology via the coupling between swimming speed and the proton motive force.

  14. Escherichia coli as a model active colloid: A practical introduction.

    PubMed

    Schwarz-Linek, Jana; Arlt, Jochen; Jepson, Alys; Dawson, Angela; Vissers, Teun; Miroli, Dario; Pilizota, Teuta; Martinez, Vincent A; Poon, Wilson C K

    2016-01-01

    The flagellated bacterium Escherichia coli is increasingly used experimentally as a self-propelled swimmer. To obtain meaningful, quantitative results that are comparable between different laboratories, reproducible protocols are needed to control, 'tune' and monitor the swimming behaviour of these motile cells. We critically review the knowledge needed to do so, explain methods for characterising the colloidal and motile properties of E. coli cells, and propose a protocol for keeping them swimming at constant speed at finite bulk concentrations. In the process of establishing this protocol, we use motility as a high-throughput probe of aspects of cellular physiology via the coupling between swimming speed and the proton motive force. PMID:26310235

  15. Bacterial self-defence: how Escherichia coli evades serum killing.

    PubMed

    Miajlovic, Helen; Smith, Stephen G

    2014-05-01

    The ability to survive the bactericidal action of serum is advantageous to extraintestinal pathogenic Escherichia coli that gain access to the bloodstream. Evasion of the innate defences present in serum, including complement and antimicrobial peptides, involves multiple factors. Serum resistance mechanisms utilized by E. coli include the production of protective extracellular polysaccharide capsules and expression of factors that inhibit or interfere with the complement cascade. Recent studies have also highlighted the importance of structural integrity of the cell envelope in serum survival. These survival strategies are outlined in this review with particular attention to novel findings and recent insights into well-established resistance mechanisms. PMID:24617921

  16. Recombinant protein expression in Escherichia coli: advances and challenges

    PubMed Central

    Rosano, Germán L.; Ceccarelli, Eduardo A.

    2014-01-01

    Escherichia coli is one of the organisms of choice for the production of recombinant proteins. Its use as a cell factory is well-established and it has become the most popular expression platform. For this reason, there are many molecular tools and protocols at hand for the high-level production of heterologous proteins, such as a vast catalog of expression plasmids, a great number of engineered strains and many cultivation strategies. We review the different approaches for the synthesis of recombinant proteins in E. coli and discuss recent progress in this ever-growing field. PMID:24860555

  17. Short-term dynamic behavior of Escherichia coli in response to successive glucose pulses on glucose-limited chemostat cultures.

    PubMed

    Sunya, Sirichai; Bideaux, Carine; Molina-Jouve, Carole; Gorret, Nathalie

    2013-04-15

    The effect of repeated glucose perturbations on dynamic behavior of Escherichia coli DPD2085, yciG::LuxCDABE reporter strain, was studied and characterized on a short-time scale using glucose-limited chemostat cultures at dilution rates close to 0.18h(-1). The substrate disturbances were applied on independent steady-state cultures, firstly using a single glucose pulse under different aeration conditions and secondly using repeated glucose pulses under fully aerobic condition. The dynamic responses of E. coli to a single glucose pulse of different intensities (0.25 and 0.6gL(-1)) were significantly similar at macroscopic level, revealing the independency of the macroscopic microbial behavior to the perturbation intensity in the range of tested glucose concentrations. The dynamic responses of E. coli to repeated glucose pulses to simulate fluctuating environments between glucose-limited and glucose-excess conditions were quantified; similar behavior regarding respiration and by-product formations was observed, except for the first perturbation denoted by an overshoot of the specific oxygen uptake rate in the first minutes after the pulse. In addition, transcriptional induction of yciG promoter gene involved in general stress response, ?(S), was monitored through the bioluminescent E. coli strain. This study aims to provide and compare short-term quantitative kinetics data describing the dynamic behavior of E. coli facing repeated transient substrate conditions. PMID:23376621

  18. Dexamethazone protects against Escherichia coli induced sickness behavior in rats.

    PubMed

    Hanaa-Mansour, A; Hassan, Wedad A; Georgy, Gehan S

    2016-01-01

    Systemic bacterial infection results in systemic inflammatory response syndrome due to the release of lipopolysaccharide (LPS) in blood that can lead to multiple organ failure, shock, and potentially death. Other impact, LPS exposure produces robust increase in anxiety-like behavior, suppression of locomotor, exploratory activity, and reduced social behavior. The therapeutic use of glucocorticoids in septic shock remains one of the first-aid approaches for their anti-inflammatory properties. The aim of this study was to evaluate the possible protective effect of dexamethazone (DEX), the most commonly used corticosteroid, against Escherichia coli (E. coli) immunohistochemical changes and neurobehavioral dysfunction. To this end, male Sprague-Dawley rats were divided into four groups; (1) Control group (2) E. coli infected group, where animals received 0.2ml of 24h growth of E. coli suspension in nutrient broth containing approximately 1.8×10(8)cfu/ml i.p for once, 48h before sacrificing (3) DEX (20mg/kg, i.p, 3 days) treated group (4) DEX and E. coli treated group. The results revealed that DEX significantly protected animals against most E. coli-induced behavioral deficits, reduced signs of cognitive impairment. DEX also reduced the LPS-evoked rise in C-reactive protein (CRP), Interferon gamma (IF?), as well as, expression of Caspase-3. In conclusion, DEX provides neuroprotection against E. coli-associated neurobehavioral and immunological changes via its anti-inflammatory and immunomodulatory effects. PMID:26541583

  19. Escherichia Coli: an Important Pathogen in Patients with Hematologic Malignancies

    PubMed Central

    Olson, Daniel; Yacoub, Abraham T.; Gjini, Anita D.; Domingo, Gelenis; Greene, John N.

    2014-01-01

    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. Out of 245 patients, 169 did not meet the criteria due to non-neutropenic status, or not diagnosed with a hematologic malignancy, or due to having insufficient medical records. Thus, they were excluded from the study. As a result, 76 patients were involved in this study. 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. PMID:25408854

  20. A Novel Methyltransferase Catalyzes the Methyl Esterification of trans-Aconitate in Escherichia coli*

    E-print Network

    Clarke, Steven

    -adenosyl-L-methi- onine-dependent methyltransferase in the cytosol of Escherichia coli that is expressed in early). In the bacterium Escherichia coli, this enzyme is required for optimal survival of stationary phase cells againstA Novel Methyltransferase Catalyzes the Methyl Esterification of trans-Aconitate in Escherichia

  1. In vivo translation rates can substantially delay the cotranslational folding of the Escherichia coli

    E-print Network

    Morimoto, Richard

    results indicate that, at in vivo translation rates, about one-third of the Escherichia coli cytosolic in Escherichia coli's proteome. systems biology | synonymous codons | chemical kinetics | chaperone | aggregationIn vivo translation rates can substantially delay the cotranslational folding of the Escherichia

  2. An Experimental Evolutionary Study on Adaptation to Temporally Fluctuating pH in Escherichia coli

    E-print Network

    Bennett, Albert F.

    Published 5/2/2007 ABSTRACT In this study, we use the bacterium Escherichia coli to examine evolutionary because of the importance of this environmental stressor to enteric bac- teria such as Escherichia coli406 An Experimental Evolutionary Study on Adaptation to Temporally Fluctuating pH in Escherichia

  3. Enterotoxigenic Escherichia coli infection in captive black-footed ferrets.

    PubMed

    Bradley, G A; Orr, K; Reggiardo, C; Glock, R D

    2001-07-01

    Enterotoxigenic Escherichia coli with genes for heat stabile toxins Sta and STb was isolated from the gastrointestinal tract and multiple visceral organs of three adult and three juvenile black-footed ferrets (Mustela nigripes) that died in a captive breeding colony between 24 May 1998 and 2 July 1998. Similar isolates were obtained from rectal swabs of one adult and one juvenile that were clinically ill. All were fed a diet composed of mink chow, raw rabbit meat, beef liver powder, blood meal and lard. Escherichia coli of the same toxin genotype was isolated from the mixed ration. Clinical signs included sudden death, dehydration, anorexia and diarrhea. Necropsy lesions included acute enteritis with large numbers of rod shaped bacteria microscopically visible on intestinal villi. PMID:11504237

  4. Comparison of the Small Molecule Metabolic Enzymes of Escherichia coli and Saccharomyces cerevisiae

    E-print Network

    Gough, Julian

    Comparison of the Small Molecule Metabolic Enzymes of Escherichia coli and Saccharomyces cerevisiae pathways in Escherichia coli and Saccharomyces cerevisiae (yeast) shows that 271 enzymes are common to both organisms. These common enzymes involve 384 gene products in E. coli and 390 in yeast, which are between one

  5. Visualizing Escherichia coli Sub-Cellular Structure Using Sparse Deconvolution Spatial Light Interference

    E-print Network

    Do, Minh N.

    Visualizing Escherichia coli Sub-Cellular Structure Using Sparse Deconvolution Spatial Light MN, Golding I, et al. (2012) Visualizing Escherichia coli Sub-Cellular Structure Using Sparse coiled sub-cellular structures in E. coli cells which are most likely the cytoskeletal MreB protein

  6. Is there a Liquid State Machine in the Bacterium Escherichia Coli?

    E-print Network

    Fernando, Chrisantha

    Is there a Liquid State Machine in the Bacterium Escherichia Coli? Ben Jones, Dov Stekelo, Jon Rowe, UK Email: C.T.Fernando@cs.bham.ac.uk Abstract-- The bacterium Escherichia coli has the capacity, E.Coli's capacity for perceptual categorization, especially for discrimination between complex

  7. Design and Diversity in Bacterial Chemotaxis: A Comparative Study in Escherichia coli

    E-print Network

    Fernando, Chrisantha

    Design and Diversity in Bacterial Chemotaxis: A Comparative Study in Escherichia coli and Bacillus such as Escherichia coli and Bacillus subtilis, swimming alternates between smooth runs and reorientating tumbles, in particular the feedback control structure, is also conserved. The bacterial chemotaxis pathways in E. coli

  8. The Roles of Specific Template Nucleosides in the Formation of Stable Transcription Complexes by Escherichia coli

    E-print Network

    Tullius, Thomas D.

    by Escherichia coli RNA Polymerase* (Received for publication, September 13, 1999, and in revised form, December/or initiation. The initiation of transcription by Escherichia coli RNA po- lymerase involves not only DNA nucleosides on promoter escape by Esche- richia coli RNA polymerase in vitro. The ability of DNA templates

  9. Evaluating Representations for the Shine-Dalgarno Site in Escherichia coli

    E-print Network

    Kibler, Dennis F.

    Evaluating Representations for the Shine-Dalgarno Site in Escherichia coli Steven Hampson & Dennis 10) are applied to the pooled Upstream Regions (USR) of all 4289 Escherichia coli ORFs. Instances) but most genes in E. coli have an identifiable SD sequence in the expected location. On the other hand, up

  10. Antimicrobial properties of the Escherichia coli R1 plasmid host killing peptide

    E-print Network

    Wood, Thomas K.

    Antimicrobial properties of the Escherichia coli R1 plasmid host killing peptide Douglas C. Pecota-segregational killer system of the Escherichia coli plasmid R1 was synthesized using Fmoc (9-fluorenylmethoxycarbonyl. coli cells showed a dramatic reduction (100 000-fold) in the number of cells transformed with plasmid

  11. Shotgun Optical Maps of the Whole Escherichia coli O157:H7 Genome

    E-print Network

    Mishra, Bud

    Shotgun Optical Maps of the Whole Escherichia coli O157:H7 Genome Alex Lim,1,2 Eileen T. Dimalanta of Escherichia coli O157:H7 solely from genomic DNA molecules to provide a uniquely valuable scaffold for contig closure and sequence validation. E. coli O157:H7 is a common pathogen found in contaminated food and water

  12. Antibacterial efficacy of silver nanoparticles against Escherichia coli

    NASA Astrophysics Data System (ADS)

    Pattabi, Rani M.; Thilipan, G. Arun Kumar; Bhat, Vinayachandra; Sridhar, K. R.; Pattabi, Manjunatha

    2013-02-01

    Silver nanoparticles (AgNPs) synthesized by subjecting an aqueous solution of AgNO3 and polyvinyl alcohol to irradiation from an UV lamp has been studied for its antibacterial potential against Gram-negative bacteria (Escherichia coli). The diameter of the zone of inhibition is found to depend on both the irradiation time and the nanoparticle concentration. As the synthesis method adopted uses no toxic reagents, these particles may serve as promising candidates in the search for better antibacterial agents.

  13. Electric field induced bacterial flocculation of enteroaggregative Escherichia coli 042

    NASA Astrophysics Data System (ADS)

    Kumar, Aloke; Mortensen, Ninell P.; Mukherjee, Partha P.; Retterer, Scott T.; Doktycz, Mitchel J.

    2011-06-01

    A response of the aggregation dynamics of enteroaggregative Escherichia coli under low magnitude steady and oscillating electric fields is presented. The presence of uniform electric fields hampered microbial adhesion and biofilm formation on a transverse glass surface, but instead promoted the formation of flocs. Extremely heterogenous distribution of live and dead cells was observed among the flocs. Moreover, floc formation was largely observed to be independent of the frequency of alternating electric fields.

  14. Electric field induced bacterial flocculation of Enteroaggregative Escherichia coli 042

    SciTech Connect

    Kumar, Aloke; Mortensen, Ninell P; Mukherjee, Partha P; Retterer, Scott T; Doktycz, Mitchel John

    2011-01-01

    A response of the aggregation dynamics of enteroaggregative Escherichia coli under low magnitude steady and oscillating electric fields is presented. The presence of uniform electric fields hampered microbial adhesion and biofilm formation on a transverse glass surface, but instead promoted the formation of flocs. Extremely heterogeneous distribution of live and dead cells was observed among the flocs. Moreover, floc formation was largely observed to be independent of the frequency of alternating electric fields.

  15. Production and characterization of human gamma interferon from Escherichia coli.

    PubMed

    Perez, L; Vega, J; Chuay, C; Menendez, A; Ubieta, R; Montero, M; Padron, G; Silva, A; Santizo, C; Besada, V

    1990-07-01

    The production of human gamma interferon as intracellular inclusion bodies in Escherichia coli, which simplified the purification process, is described. An expression plasmid carrying lipoprotein and the tryptophane promoters in tandem was used. Preparation of highly pure interferon was achieved using high resolution chromatography after denaturation and renaturation steps. Structural characteristics of this protein were verified by mass spectrometric analysis. Additional control tests have shown the suitability of the final product for clinical purposes. PMID:1367470

  16. Escherichia coli and Salmonella 2000: the View From Here

    PubMed Central

    Schaechter, Moselio

    2001-01-01

    Five years after the publication of the second edition of the reference book Escherichia coli and Salmonella: Cellular and Molecular Biology, and on the eve of launching a successor venture, the editors and colleagues examine where we stand in our quest for an understanding of these organisms. The main areas selected for this brief inquiry are genomics, evolution, molecular multifunctionality, functional backups, regulation of gene expression, cell biology, sensing of the environment, and ecology. PMID:11238988

  17. Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation

    PubMed Central

    Laverty, Garry; Gorman, Sean P.; Gilmore, Brendan F.

    2014-01-01

    Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl), pellicle Formation (Pel) and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides) that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation. PMID:25438014

  18. Escherichia coli heme oxygenase modulates host innate immune responses

    PubMed Central

    Maharshak, Nitsan; Ryu, Hyungjin Sally; Fan, Ting-Jia; Onyiah, Joseph C.; Schulz, Stephanie; Otterbein, Sherrie L.; Wong, Ron; Hansen, Jonathan; Otterbein, Leo E; Carroll, Ian; Plevy, Scott E.

    2015-01-01

    Induction of mammalian heme oxygenase-1 and exposure of animals to carbon monoxide ameliorates experimental colitis. When enteric bacteria, including Escherichia coli, are exposed to low iron conditions, they express an heme oxygenase-like enzyme, chuS, and metabolize heme into iron, biliverdin and carbon monoxide. Given the abundance of enteric bacteria residing in the intestinal lumen, we hypothesized that commensal intestinal bacteria may be a significant source of carbon monoxide, with the consequence that enteric bacteria expressing chuS and other heme oxygenase -like molecules suppress inflammatory immune responses through release of carbon monoxide. Carbon monoxide exposed mice have altered enteric bacterial composition and increased E. coli 16S and chuS DNA by real-time PCR. Moreover, severity of experimental colitis correlates with increased E. coli chuS expression in IL-10 deficient mice. To explore functional roles, E. coli were genetically modified to overexpress chuS or the chuS gene was deleted. Co-culture of chuS-overexpressing E. coli with bone marrow derived macrophages results in decreased IL-12 p40 and increased IL-10 secretion compared to wild-type or chuS-deficient E. coli. Mice infected with chuS-overexpressing E. coli have increased levels of hepatic carbon monoxide and decreased serum IL-12 p40 compared to mice infected with chuS-deficient E. coli. Thus, carbon monoxide alters the composition of the commensal intestinal microbiota and expands E. coli populations harboring the chuS gene. These bacteria are capable of attenuating innate immune responses through expression of chuS. Bacterial heme oxygenase -like molecules and bacterial-derived carbon monoxide may represent novel targets for therapeutic intervention in inflammatory conditions. PMID:26146866

  19. Shear alters motility of Escherichia coli

    NASA Astrophysics Data System (ADS)

    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 ?m. 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.

  20. Interaction of Escherichia coli and soil particles in runoff.

    PubMed

    Muirhead, Richard William; Collins, Robert Peter; Bremer, Philip James

    2006-05-01

    A laboratory-scale model system was developed to investigate the transport mechanisms involved in the horizontal movement of bacteria in overland flow across saturated soils. A suspension of Escherichia coli and bromide tracer was added to the model system, and the bromide concentration and number of attached and unattached E. coli cells in the overland flow were measured over time. Analysis of the breakthrough curves indicated that the E. coli and bromide were transported together, presumably by the same mechanism. This implied that the E. coli was transported by advection with the flowing water. Overland-flow transport of E. coli could be significantly reduced if the cells were preattached to large soil particles (> 45 microm). However, when unattached cells were inoculated into the system, the E. coli appeared to attach predominantly to small particles (< 2 microm) and hence remained unattenuated during transport. These results imply that in runoff generated by saturation-excess conditions, bacteria are rapidly transported across the surface and have little opportunity to interact with the soil matrix. PMID:16672484

  1. Identification of Escherichia coli genes associated with urinary tract infections.

    PubMed

    Mao, Bin-Hsu; Chang, Yung-Fu; Scaria, Joy; Chang, Chih-Ching; Chou, Li-Wei; Tien, Ni; Wu, Jiunn-Jong; Tseng, Chin-Chung; Wang, Ming-Cheng; Chang, Chao-Chin; Hsu, Yuan-Man; Teng, Ching-Hao

    2012-02-01

    Escherichia coli is the most common cause of urinary tract infections (UTIs). E. coli genes epidemiologically associated with UTIs are potentially valuable in developing strategies for treating and/or preventing such infections as well as differentiating uropathogenic E. coli from nonuropathogenic E. coli. To identify E. coli genes associated with UTIs in humans, we combined microarray-based and PCR-based analyses to investigate different E. coli source groups derived from feces of healthy humans and from patients with cystitis, pyelonephritis, or urosepsis. The cjrABC-senB gene cluster, sivH, sisA, sisB, eco274, and fbpB, were identified to be associated with UTIs. Of these, cjrABC-senB, sisA, sisB, and fbpB are known to be involved in urovirulence in the mouse model of ascending UTI. Our results provide evidence to support their roles as urovirulence factors in human UTIs. In addition, the newly identified UTI-associated genes were mainly found in members of phylogenetic groups B2 and/or D. PMID:22075599

  2. Incidence of Escherichia coli in Black Walnut Meats

    PubMed Central

    Meyer, Melvin T.; Vaughn, Reese H.

    1969-01-01

    Examination of commercially shelled black walnut meats showed inconsistent numbers of total aerobic bacteria, coliforms, and Escherichia coli; variation occurred among different meat sizes and within each meat size. The incidence of E. coli on meats of commercially hulled black walnuts depended on the physical condition of the nuts. Apparently tightly sealed ones contained only a few or none, whereas those with visibly separated sutures and spoiled meats yielded the most. This contamination was in part correlated to a hulling operation. Large numbers of E. coli on the husk of the walnuts contaminated the hulling water, subsequently also contaminating the meats by way of separated sutures. Chlorination of the hulling wash water was ineffective. Attempts were made to decontaminate the walnut meats without subsequent deleterious changes in flavor or texture. A treatment in coconut oil at 100 C followed by removal of excess surface oil by centrifugation was best. PMID:4905608

  3. Functions of the gene products of Escherichia coli.

    PubMed Central

    Riley, M

    1993-01-01

    A list of currently identified gene products of Escherichia coli is given, together with a bibliography that provides pointers to the literature on each gene product. A scheme to categorize cellular functions is used to classify the gene products of E. coli so far identified. A count shows that the numbers of genes concerned with small-molecule metabolism are on the same order as the numbers concerned with macromolecule biosynthesis and degradation. One large category is the category of tRNAs and their synthetases. Another is the category of transport elements. The categories of cell structure and cellular processes other than metabolism are smaller. Other subjects discussed are the occurrence in the E. coli genome of redundant pairs and groups of genes of identical or closely similar function, as well as variation in the degree of density of genetic information in different parts of the genome. PMID:7508076

  4. Engineering Escherichia coli K12 MG1655 to use starch

    PubMed Central

    2014-01-01

    Background To attain a sustainable bioeconomy, fuel, or valuable product, production must use biomass as substrate. Starch is one of the most abundant biomass resources and is present as waste or as a food and agroindustry by-product. Unfortunately, Escherichia coli, one of the most widely used microorganisms in biotechnological processes, cannot use starch as a carbon source. Results We engineered an E. coli strain capable of using starch as a substrate. The genetic design employed the native capability of the bacterium to use maltodextrins as a carbon source plus expression and secretion of its endogenous ?-amylase, AmyA, in an adapted background. Biomass production improved using 35% dissolved oxygen and pH 7.2 in a controlled bioreactor. Conclusion The engineered E. coli strain can use starch from the milieu and open the possibility of optimize the process to use agroindustrial wastes to produce biofuels and other valuable chemicals. PMID:24886307

  5. A preliminary study of Salmonella, verocytotoxigenic Escherichia coli/Escherichia coli O157 and Campylobacter on four mixed farms.

    PubMed

    Bolton, D J; O'Neill, C J; Fanning, S

    2012-05-01

    The aims of this study were to investigate the incidence of Salmonella, verocytotoxigenic Escherichia coli (VTEC)/Escherichia coli O157 and Campylobacter on four mixed farms and to characterize the isolates in terms of a range of virulence factors. Eighty-nine composite (five different samples from the same animal species combined) faecal [cattle (24), pigs (14), sheep (4), poultry (4), horses (7), deer (4), dogs (9), rodents (2) and wild birds (20)] samples, 16 composite soil samples plus 35 individual water samples were screened using culture-based, immunomagnetic separation and molecular methods. Salmonella was detected in bovine faeces, cattle and poultry house water. Salmonella serotypes/phage types included Dublin, Kiel and Typhimurium DT193, and most isolates were spvC, invA and rck positive. The pefA and rck genes were found exclusively in the non-Typhimurium strains, while Salmonella Dublin and Salmonella Kiel strains carried Salmonella genomic island I marker(s). VTEC/E. coli O157 were found in deer and dog faeces only. The E. coli O157 isolate was an enteroinvasive E. coli, while the VTEC isolate was untypable but carried the vt1, eaeA, hlyA, tir and eptD genes. This article reports the first confirmed carriage of E. coli O157 in Irish deer. Campylobacter species were not detected over the course of this study. It was concluded that [1] Salmonella, VTEC and Campylobacter have low (<5%) prevalence or are absent on the farms in this study; [2] water was an important source of bacterial pathogens; [3] both dogs and deer may act as a source of pathogenic E. coli and [4] key virulence and resistance determinants are widespread in farm Salmonella strains. This study highlights the need to control water as a source of pathogens and suggests that the domestic pets and deer should be considered in any farm risk assessment. PMID:21951421

  6. Steady-State Chemotaxis in Escherichia coli

    NASA Astrophysics Data System (ADS)

    Kafri, Yariv; da Silveira, Rava Azeredo

    2008-06-01

    The bacterium E. coli maneuvers itself to regions with high chemoattractant concentrations by performing two stereotypical moves: “runs,” in which it moves in near-straight lines, and “tumbles,” in which it does not advance but changes direction randomly. The duration of each move is stochastic and depends upon the chemoattractant concentration experienced in the recent past. We relate this stochastic behavior to the steady-state density of a bacterium population, and we derive the latter as a function of chemoattractant concentration. In contrast to earlier treatments, here we account for the effects of temporal correlations and variable tumbling durations. A range of behaviors is obtained that depends subtly upon several aspects of the system—memory, correlation, and tumbling stochasticity, in particular.

  7. Preparation of Soluble Proteins from Escherichia coli

    PubMed Central

    Wingfield, Paul T.

    2014-01-01

    Purification of human IL-1? is used in this unit as an example of the preparation of soluble proteins from E. coli. Bacteria containing IL-1? are lysed, and IL-1 ? in the resulting supernatant is purified by anion-exchange chromatography, salt precipitation and cation-exchange chromatography, and then concentrated. Finally, the IL-1 ? protein is applied to a gel-filtration column to separate it from remaining higher- and lower-molecular-weight contaminants, the purified protein is stored frozen or is lyophilized. The purification protocol described is typical for a protein that is expressed in fairly high abundance (i.e., >5% total protein) and accumulates in a soluble state. Also, the purification procedure serves as an example of how use classical protein purifications methods which may also be used in conjunction with the affinity-based methods now more commonly used. PMID:25367009

  8. Effect of tannins on the in viro growth of Escherichia coli O157:H7 and in vivo growth of generic Escherichia coli excreted from steers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement o...

  9. Defining the Genome Features of Escherichia albertii, an Emerging Enteropathogen Closely Related to Escherichia coli

    PubMed Central

    Ooka, Tadasuke; Ogura, Yoshitoshi; Katsura, Keisuke; Seto, Kazuko; Kobayashi, Hideki; Kawano, Kimiko; Tokuoka, Eisuke; Furukawa, Masato; Harada, Seiya; Yoshino, Shuji; Seto, Junji; Ikeda, Tetsuya; Yamaguchi, Keiji; Murase, Kazunori; Gotoh, Yasuhiro; Imuta, Naoko; Nishi, Junichiro; Gomes, Tânia A.; Beutin, Lothar; Hayashi, Tetsuya

    2015-01-01

    Escherichia albertii is a recently recognized close relative of Escherichia coli. This emerging enteropathogen possesses a type III secretion system (T3SS) encoded by the locus of enterocyte effacement, similar to enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC). Shiga toxin-producing strains have also been identified. The genomic features of E. albertii, particularly differences from other Escherichia species, have not yet been well clarified. Here, we sequenced the genome of 29 E. albertii strains (3 complete and 26 draft sequences) isolated from multiple sources and performed intraspecies and intragenus genomic comparisons. The sizes of the E. albertii genomes range from 4.5 to 5.1 Mb, smaller than those of E. coli strains. Intraspecies genomic comparisons identified five phylogroups of E. albertii. Intragenus genomic comparison revealed that the possible core genome of E. albertii comprises 3,250 genes, whereas that of the genus Escherichia comprises 1,345 genes. Our analysis further revealed several unique or notable genetic features of E. albertii, including those responsible for known biochemical features and virulence factors and a possibly active second T3SS known as ETT2 (E. coli T3SS 2) that is inactivated in E. coli. Although this organism has been observed to be nonmotile in vitro, genes for flagellar biosynthesis are fully conserved; chemotaxis-related genes have been selectively deleted. Based on these results, we have developed a nested polymerase chain reaction system to directly detect E. albertii. Our data define the genomic features of E. albertii and provide a valuable basis for future studies of this important emerging enteropathogen. PMID:26537224

  10. Catalysis of disulfide bond formation and isomerization in the Escherichia coli periplasm

    E-print Network

    Bardwell, James

    Review Catalysis of disulfide bond formation and isomerization in the Escherichia coli periplasm configuration. These disulfide isomerization reactions are sustained by a constant supply of reducing power

  11. Analysis of O-island deletions in Escherichia coli O157:H7 

    E-print Network

    Flockhart, Allen Forrest

    2012-11-30

    Escherichia coli (E. coli) are a diverse species of bacteria that reside, often harmoniously and beneficially, in the gastrointestinal tracts of humans and other mammals. However, some strains are associated with serious ...

  12. Use of Evolutionary Factor Analysis in the Spectroelectrochemistry of Escherichia coli Sulfite

    E-print Network

    Reid, Scott A.

    Use of Evolutionary Factor Analysis in the Spectroelectrochemistry of Escherichia coli Sulfite and chronoabsorptometry in a thin-layer cell. The first system was the reduction of E. coli sulfite reductase hemoprotein

  13. Assessing Avian Contribution of Escherichia coli and Nutrient Loads to Watersheds 

    E-print Network

    Telesford-Checkley, Judlyn Merium

    2014-11-19

    The impairment of waterways by pathogens as indicated by the detection of high Escherichia coli (E. coli) levels continues to be a problem in Texas. Almost half of the assessed waterbodies designated for contact recreation in Texas are impaired...

  14. Escherichia coli O157 and other Shiga toxin producting E. coli: detection by immunomagnetic particle-based assays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli (STEC), including E. coli O157:H7 and non-O157 STEC cause hemorrhagic colitis and hemolytic uremic syndrome and are important food-borne pathogens that can contaminate various types of food. The USDA Food Safety and Inspection Service declared E. coli O157:H7 a...

  15. Diarrhea, bacteremia and multiorgan dysfunction due to an extraintestinal pathogenic Escherichia coli strain with enteropathogenic E. coli genes

    PubMed Central

    Kessler, Robert; Nisa, Shahista; Hazen, Tracy H.; Horneman, Amy; Amoroso, Anthony; Rasko, David A.; Donnenberg, Michael S.

    2015-01-01

    A 55-year-old man with well-controlled HIV had severe diarrhea for 3 weeks and developed multiorgan dysfunction and bacteremia due to Escherichia coli. The genome of the patient's isolate had features characteristic of extraintestinal pathogenic E. coli and genes distantly related to those defining enteropathogenic E. coli. PMID:26410828

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

    PubMed

    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. PMID:20400597

  17. Recent Advances in Understanding Enteric Pathogenic Escherichia coli

    PubMed Central

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

    2013-01-01

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

  18. The Escherichia coli Proteome: Past, Present, and Future Prospects†

    PubMed Central

    Han, Mee-Jung; Lee, Sang Yup

    2006-01-01

    Proteomics has emerged as an indispensable methodology for large-scale protein analysis in functional genomics. The Escherichia coli proteome has been extensively studied and is well defined in terms of biochemical, biological, and biotechnological data. Even before the entire E. coli proteome was fully elucidated, the largest available data set had been integrated to decipher regulatory circuits and metabolic pathways, providing valuable insights into global cellular physiology and the development of metabolic and cellular engineering strategies. With the recent advent of advanced proteomic technologies, the E. coli proteome has been used for the validation of new technologies and methodologies such as sample prefractionation, protein enrichment, two-dimensional gel electrophoresis, protein detection, mass spectrometry (MS), combinatorial assays with n-dimensional chromatographies and MS, and image analysis software. These important technologies will not only provide a great amount of additional information on the E. coli proteome but also synergistically contribute to other proteomic studies. Here, we review the past development and current status of E. coli proteome research in terms of its biological, biotechnological, and methodological significance and suggest future prospects. PMID:16760308

  19. Parallel evolution of virulence in pathogenic Escherichia coli.

    PubMed

    Reid, S D; Herbelin, C J; Bumbaugh, A C; Selander, R K; Whittam, T S

    2000-07-01

    The mechanisms underlying the evolution and emergence of new bacterial pathogens are not well understood. To elucidate the evolution of pathogenic Escherichia coli strains, here we sequenced seven housekeeping genes to build a phylogenetic tree and trace the history of the acquisition of virulence genes. Compatibility analysis indicates that more than 70% of the informative sites agree with a single phylogeny, suggesting that recombination has not completely obscured the remnants of ancestral chromosomes. On the basis of the rate of synonymous substitution for E. coli and Salmonella enterica (4.7 x 10(-9) per site per year), the radiation of clones began about 9 million years ago and the highly virulent pathogen responsible for epidemics of food poisoning, E. coli O157:H7, separated from a common ancestor of E. coli K-12 as long as 4.5 million years ago. Phylogenetic analysis reveals that old lineages of E. coli have acquired the same virulence factors in parallel, including a pathogenicity island involved in intestinal adhesion, a plasmid-borne haemolysin, and phage-encoded Shiga toxins. Such parallel evolution indicates that natural selection has favoured an ordered acquisition of genes and the progressive build-up of molecular mechanisms that increase virulence. PMID:10894541

  20. Escherichia coli ST131, an Intriguing Clonal Group

    PubMed Central

    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 ?-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

  1. Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance

    PubMed Central

    Vega, Nicole M.; Allison, Kyle R.; Samuels, Amanda N.; Klempner, Mark S.; Collins, James J.

    2013-01-01

    Bacterial communication plays an important role in many population-based phenotypes and interspecies interactions, including those in host environments. These interspecies interactions may prove critical to some infectious diseases, and it follows that communication between pathogenic bacteria and commensal bacteria is a subject of growing interest. Recent studies have shown that Escherichia coli uses the signaling molecule indole to increase antibiotic tolerance throughout its population. Here, we show that the intestinal pathogen Salmonella typhimurium increases its antibiotic tolerance in response to indole, even though S. typhimurium does not natively produce indole. Increased antibiotic tolerance can be induced in S. typhimurium by both exogenous indole added to clonal S. typhimurium populations and indole produced by E. coli in mixed-microbial communities. Our data show that indole-induced tolerance in S. typhimurium is mediated primarily by the oxidative stress response and, to a lesser extent, by the phage shock response, which were previously shown to mediate indole-induced tolerance in E. coli. Further, we find that indole signaling by E. coli induces S. typhimurium antibiotic tolerance in a Caenorhabditis elegans model for gastrointestinal infection. These results suggest that the intestinal pathogen S. typhimurium can intercept indole signaling from the commensal bacterium E. coli to enhance its antibiotic tolerance in the host intestine. PMID:23946425

  2. Paper-based ELISA to rapidly detect Escherichia coli.

    PubMed

    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 (P<0.01??) for uncontaminated samples. This technique is less time-consuming, easier to perform, and less expensive than conventional methods. Thus, paper-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. PMID:26459436

  3. The Genetic Basis of Escherichia coli Pathoadaptation to Macrophages

    PubMed Central

    Miskinyte, Migla; Sousa, Ana; Ramiro, Ricardo S.; de Sousa, Jorge A. Moura; Kotlinowski, Jerzy; Caramalho, Iris; Magalhães, Sara; Soares, Miguel P.; Gordo, Isabel

    2013-01-01

    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 (M?), 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 M? commensal E. coli can evolve, in less than 500 generations, virulent clones that escape phagocytosis and M? 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. PMID:24348252

  4. Locating Escherichia coli contamination in a rural South Carolina watershed.

    PubMed

    Kloot, Robin W

    2007-06-01

    One of the problems associated with the use of ambient water quality standards in surface water regulation is the difficulty of identifying and regulating nonpoint source pollution, making such standards unenforceable, especially at the local level. We used the Escherichia coli indicator to locate the most contaminated reaches in rural South Carolina's Bush River watershed (297 km(2), 186 stream-km). We divided the watershed into 20 smaller reaches and sampled each reach multiple times, but restricted each sampling round to one day. We located four low order creek reaches, representing just nine stream-km, where we observed geometric mean E. coli densities of over 1250 E. coli/100 mL; in each case, the source of the contamination (riparian grazing of cattle) was easily identifiable. On the Bush River itself, we observed a step change in one reach where geometric means increased from 106 E. coli/100 mL to 565 E. coli/100 mL over the reach's 10 km length. In this case, the sources of contamination were not as obvious as in the lower order streams; in this case, more advanced Microbial Source Tracking techniques will be required to identify the sources. Nevertheless, this sampling protocol helped locate polluted reaches and provided decision-makers with reasonable justifications for concrete action in deciding where (or where not) to install conservation practices and where more sophisticated (and expensive) MST techniques were warranted. PMID:16814453

  5. Genetic determinants of heat resistance in Escherichia coli

    PubMed Central

    Mercer, Ryan G.; Zheng, Jinshui; Garcia-Hernandez, Rigoberto; Ruan, Lifang; Gänzle, Michael G.; McMullen, Lynn M.

    2015-01-01

    Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR). This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of ?- and ?-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7?pHR1 and DH5?. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the ?- and ?-proteobacteria and is a reliable indicator of high heat resistance in E. coli. PMID:26441869

  6. Multiplex PCR for Diagnosis of Enteric Infections Associated with Diarrheagenic Escherichia coli

    PubMed Central

    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

  7. Non-O157 Shiga toxin-producing Escherichia coli: detection and characterization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli strains that produce Shiga toxins, referred to as Shiga toxin-producing E. coli (STEC) or verotoxigenic E. coli (VTEC) are important food-borne pathogens that cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). E. coli O157:H7 is a common cause of STEC infection; ho...

  8. An evaluation of diarrheagenic Escherichia coli survival after ingestion by Tetrahymena sp. and Helicobacter pylori's fate after ingestion by Tetrahymena sp. and Acanthamoeba polyphaga

    E-print Network

    Smith, Charlotte Dery

    2012-01-01

    et al. Confirmational identification of Escherichia coli, aassay for identification of escherichia coli by the definedIdentification of uidA gene sequences in beta-d-glucuronidase- negative Escherichia coli.

  9. In Situ Measurement of Bioluminescence and Fluorescence in an Integrated

    E-print Network

    Sinskey, Anthony J.

    In Situ Measurement of Bioluminescence and Fluorescence in an Integrated Microbioreactor Andrea of bioluminescence and fluorescence from bacterial cultures grown in 50 mL instrumented microbioreactors. Results measurements; bioluminescence; fluorescence; instrumented microbioreactors; Escheri- chia coli; luxCDABE; gfp

  10. Widespread antibiotic resistance of diarrheagenic Escherichia coli and Shigella species

    PubMed Central

    Sadeghabadi, Azam Fatahi; Ajami, Ali; Fadaei, Reza; Zandieh, Masoud; Heidari, Elham; Sadeghi, Mahmoud; Ataei, Behrooz; Hoseini, Shervin Ghaffari

    2014-01-01

    Background: Antibiotic resistance of enteric pathogens particularly Shigella species, is a critical world-wide problem and monitoring their resistant pattern is essential, because the choice of antibiotics is absolutely dependent on regional antibiotic susceptibility patterns. During summer 2013, an unusual increase in number of diarrheal diseases was noticed in Isfahan, a central province of Iran. Therefore, the antibiotic resistance of diarrheagenic Escherichia coli and Shigella species isolated were evaluated. Materials and Methods: According to the guideline on National Surveillance System for Foodborn Diseases, random samples from patients with acute diarrhea were examined in local laboratories of health centers and samples suspicious of Shigella spp. were further assessed in referral laboratory. Isolated pathogens were identified by standard biochemical and serologic tests and antibiotic susceptibility testing was carried out by disc diffusion method. Results: A total of 1086 specimens were obtained and 58 samples suspicious of Shigella were specifically evaluated. The most prevalent isolated pathogen was Shigella sonnei (26/58) followed by E. coli (25/58) and Shigella flexneri (3/58). A large number of isolated bacteria were resistant to co-trimoxazole (Shigella spp: 100%, E. coli: 80%), azithromycin (Shigella spp: 70.4%, E. coli: 44.0%), ceftriaxone (Shigella spp: 88.9%, E. coli: 56.0%) and cefixime (Shigella spp: 85.2%, E. coli: 68.0%). About88.3% of S. sonnei isolates, one S. flexneri isolate, and 56% of E. coli strains were resistant to at least three antibiotic classes (multidrug resistant). Conclusion: Due to high levels of resistance to recommended and commonly used antibiotics for diarrhea, continuous monitoring of antibiotic resistance seems essential for determining best options of empirical therapy. PMID:25002896

  11. A putative, novel coli surface antigen 8B (CS8B) of enterotoxigenic Escherichia coli

    PubMed Central

    Njoroge, Samuel M.; Boinett, Christine J.; Madé, Laure F.; Ouko, Tom T.; Fèvre, Eric M.; Thomson, Nicholas R.; Kariuki, Samuel

    2015-01-01

    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. PMID:26187892

  12. A putative, novel coli surface antigen 8B (CS8B) of enterotoxigenic Escherichia coli

    PubMed Central

    Njoroge, Samuel M.; Boinett, Christine J.; Madé, Laure F.; Ouko, Tom T.; Fèvre, Eric M.; Thomson, Nicholas R.; Kariuki, Samuel

    2015-01-01

    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.

  13. Expression and purification of Zantedeschia aethiopica agglutinin in Escherichia coli.

    PubMed

    Lin, Ling; Liu, Xue-Fen; Hu, Ling-Chuan; Zhou, Yin; Sun, Xiao-Fen; Tang, Ke-Xuan

    2009-03-01

    Recombinant Zantedeschia aethiopica agglutinin (ZAA) was expressed in Escherichia coli as N-terminal His-tagged fusion. After induction with isopropylthio-beta-D-galactoside (IPTG), the recombinant ZAA was purified by metal-affinity chromatography. The purified ZAA protein was applied in anti-fungal assay and the result showed that recombinant ZAA had anti-fungal activity towards leaf mold (Fulvia fulva), one of the most serious phytopathogenic fungi causing significant yield loss of crops. This study suggests that ZAA could be an effective candidate in genetic engineering of plants for the control of leaf mold. PMID:18080841

  14. Causes, prevention and treatment of Escherichia coli infections.

    PubMed

    Gould, Dinah

    Escherichia coli is a normal inhabitant of the human gastrointestinal tract and can cause healthcare-associated infections. The organism is most frequently responsible for urinary tract infections and it is the bacterium most often implicated in the cause of diarrhoea in people travelling overseas. In recent years, a strain called Ecoli O157 has gained notoriety for causing foodborne infection, which can have severe health consequences, especially in young children. This article describes the range of different infections caused by Ecoli in healthcare settings and the community and discusses the characteristics of the different strains of the bacteria that explain variations in their pathogenicity. PMID:20441035

  15. Determinants that increase the serum resistance of Escherichia coli.

    PubMed Central

    Taylor, P W; Robinson, M K

    1980-01-01

    The rfb locus, determining biosynthesis of O8-specific lipopolysaccharide side chains, was transferred to a rough mutant of Escherichia coli; recombinants producing a complete lipopolysaccharide were more resistant to the complement-mediated bactericidal action of human serum than the rough recipient. Inheritance of the his-linked genes for K27 antigen production did not alter the response to serum. The serum resistance of strains carrying O8 side chains, but not of strains with incomplete lipopolysaccharides, was further increased by inheritance of plasmids R1 and NR1.20 PMID:6995340

  16. Origin and Dissemination of Antimicrobial Resistance among Uropathogenic Escherichia coli.

    PubMed

    Nolan, Lisa K; Li, Ganwu; Logue, Catherine M

    2015-10-01

    Antimicrobial agents of various types have important bearing on the outcomes of microbial infections. These agents may be bacteriostatic or -cidal, exert their impact via various means, originate from a living organism or a laboratory, and appropriately be used in or on living tissue or not. Though the primary focus of this chapter is on resistance to the antimicrobial agents used to treat uropathogenic Escherichia coli (UPEC)-caused urinary tract infections (UTIs), some attention will be given to UPEC's resistance to silver-containing antiseptics, which may be incorporated into catheters to prevent foreign body-associated UTIs. PMID:26542043

  17. Crystal structure of GnsA from Escherichia coli.

    PubMed

    Wei, Yong; Zhan, Lihong; Gao, Zengqiang; Privé, Gilbert G; Dong, Yuhui

    2015-06-19

    Escherichia Coli GnsA is a regulator of phosphatidylethanolamine synthesis and functions as a suppressor of both a secG null mutation and fabA6 mutations. GnsA may also be a toxin with the cognate antitoxin YmcE. Here we report the crystal structure of GnsA to 1.8 Å. GnsA forms a V shaped hairpin structure that is tightly associated into a homodimer. Our comprehensive structural study suggests that GnsA is structurally similar to an outer membrane protein, suggesting a function of protein binding. PMID:25839658

  18. Improved generation of recombinant baculovirus genomes in Escherichia coli

    PubMed Central

    Airenne, Kari J.; Peltomaa, Erik; Hytönen, Vesa P.; Laitinen, Olli H.; Ylä-Herttuala, Seppo

    2003-01-01

    An improved method for the generation of recombinant baculoviruses by Tn7-mediated transposition is described. The method is based on the modified donor vector (pBVboost) and an improved selection scheme of the baculovirus bacmids in Escherichia coli with a mutated SacB gene. Recombinant bacmids can be generated at a frequency of ?107/µg of donor vector with a negligible background. This easy-to-use and efficient pBVboost system provides the basis for a high-throughput generation of recombinant baculoviruses as well as a more convenient way to produce single viruses. The introduced selection scheme is also useful for the construction of other vectors by transposition in E.coli. PMID:12930975

  19. Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli

    PubMed Central

    Mills, Tirzah Y; Sandoval, Nicholas R; Gill, Ryan T

    2009-01-01

    The sustainable production of biofuels will require the efficient utilization of lignocellulosic biomass. A key barrier involves the creation of growth-inhibitory compounds by chemical pretreatment steps, which ultimately reduce the efficiency of fermentative microbial biocatalysts. The primary toxins include organic acids, furan derivatives, and phenolic compounds. Weak acids enter the cell and dissociate, resulting in a drop in intracellular pH as well as various anion-specific effects on metabolism. Furan derivatives, dehydration products of hexose and pentose sugars, have been shown to hinder fermentative enzyme function. Phenolic compounds, formed from lignin, can disrupt membranes and are hypothesized to interfere with the function of intracellular hydrophobic targets. This review covers mechanisms of toxicity and tolerance for these compounds with a specific focus on the important industrial organism Escherichia coli. Recent efforts to engineer E. coli for improved tolerance to these toxins are also discussed. PMID:19832972

  20. Global Analysis of Extracytoplasmic Stress Signaling in Escherichia coli

    PubMed Central

    Bury-Moné, Stéphanie; Nomane, Yanoura; Reymond, Nancie; Barbet, Romain; Jacquet, Eric; Imbeaud, Sandrine; Jacq, Annick; Bouloc, Philippe

    2009-01-01

    The Bae, Cpx, Psp, Rcs, and ?E pathways constitute the Escherichia coli signaling systems that detect and respond to alterations of the bacterial envelope. Contributions of these systems to stress response have previously been examined individually; however, the possible interconnections between these pathways are unknown. Here we investigate the dynamics between the five stress response pathways by determining the specificities of each system with respect to signal-inducing conditions, and monitoring global transcriptional changes in response to transient overexpression of each of the effectors. Our studies show that different extracytoplasmic stress conditions elicit a combined response of these pathways. Involvement of the five pathways in the various tested stress conditions is explained by our unexpected finding that transcriptional responses induced by the individual systems show little overlap. The extracytoplasmic stress signaling pathways in E. coli thus regulate mainly complementary functions whose discrete contributions are integrated to mount the full adaptive response. PMID:19763168

  1. Nanomechanical motion of Escherichia coli adhered to a surface

    PubMed Central

    Lissandrello, C.; Inci, F.; Francom, M.; Paul, M. R.; Demirci, U.; Ekinci, K. L.

    2014-01-01

    Nanomechanical motion of bacteria adhered to a chemically functionalized silicon surface is studied by means of a microcantilever. A non-specific binding agent is used to attach Escherichia coli (E. coli) to the surface of a silicon microcantilever. The microcantilever is kept in a liquid medium, and its nanomechanical fluctuations are monitored using an optical displacement transducer. The motion of the bacteria couples efficiently to the microcantilever well below its resonance frequency, causing a measurable increase in the microcantilever fluctuations. In the time domain, the fluctuations exhibit large-amplitude low-frequency oscillations. In corresponding frequency-domain measurements, it is observed that the mechanical energy is focused at low frequencies with a 1/f?-type power law. A basic physical model is used for explaining the observed spectral distribution of the mechanical energy. These results lay the groundwork for understanding the motion of microorganisms adhered to surfaces and for developing micromechanical sensors for bacteria. PMID:25316924

  2. The complete genome sequence of Escherichia coli K-12.

    PubMed

    Blattner, F R; Plunkett, G; Bloch, C A; Perna, N T; Burland, V; Riley, M; Collado-Vides, J; Glasner, J D; Rode, C K; Mayhew, G F; Gregor, J; Davis, N W; Kirkpatrick, H A; Goeden, M A; Rose, D J; Mau, B; Shao, Y

    1997-09-01

    The 4,639,221-base pair sequence of Escherichia coli K-12 is presented. Of 4288 protein-coding genes annotated, 38 percent have no attributed function. Comparison with five other sequenced microbes reveals ubiquitous as well as narrowly distributed gene families; many families of similar genes within E. coli are also evident. The largest family of paralogous proteins contains 80 ABC transporters. The genome as a whole is strikingly organized with respect to the local direction of replication; guanines, oligonucleotides possibly related to replication and recombination, and most genes are so oriented. The genome also contains insertion sequence (IS) elements, phage remnants, and many other patches of unusual composition indicating genome plasticity through horizontal transfer. PMID:9278503

  3. Mounting of Escherichia coli spheroplasts for AFM imaging.

    SciTech Connect

    Sullivan, Claretta J; Morrell-Falvey, Jennifer L; Allison, David P; Doktycz, Mitchel John

    2005-11-01

    The cytoplasmic membrane of Escherichia coli (E. coli) is the location of numerous, chemically specific transporters and recognition elements. Investigation of this membrane in vivo by atomic force microscopy (AFM) requires removal of the cell wall and stable immobilization of the spheroplast. AFM images demonstrate that spheroplasts can be secured with warm gelatin applied to the mica substrate just before the addition of a spheroplast suspension. The resulting preparation can be repeatedly imaged by AFM over the course of several hours. Confocal fluorescence imaging confirms the association of the spheroplasts with the gelatin layer. Gelatin molecules are known to reorder into a network after heating. Entrapment within this gelatin network is believed to be responsible for the immobilization of spheroplasts on mica.

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

    PubMed

    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. PMID:26627645

  5. Modeling Escherichia coli removal in constructed wetlands under pulse loading.

    PubMed

    Hamaamin, Yaseen A; Adhikari, Umesh; Nejadhashemi, A Pouyan; Harrigan, Timothy; Reinhold, Dawn M

    2014-03-01

    Manure-borne pathogens are a threat to water quality and have resulted in disease outbreaks globally. Land application of livestock manure to croplands may result in pathogen transport through surface runoff and tile drains, eventually entering water bodies such as rivers and wetlands. The goal of this study was to develop a robust model for estimating the pathogen removal in surface flow wetlands under pulse loading conditions. A new modeling approach was used to describe Escherichia coli removal in pulse-loaded constructed wetlands using adaptive neuro-fuzzy inference systems (ANFIS). Several ANFIS models were developed and validated using experimental data under pulse loading over two seasons (winter and summer). In addition to ANFIS, a mechanistic fecal coliform removal model was validated using the same sets of experimental data. The results showed that the ANFIS model significantly improved the ability to describe the dynamics of E. coli removal under pulse loading. The mechanistic model performed poorly as demonstrated by lower coefficient of determination and higher root mean squared error compared to the ANFIS models. The E. coli concentrations corresponding to the inflection points on the tracer study were keys to improving the predictability of the E. coli removal model. PMID:24231031

  6. Extracellular superoxide provokes glutathione efflux from Escherichia coli cells.

    PubMed

    Smirnova, Galina V; Muzyka, Nadezda G; Ushakov, Vadim Y; Tyulenev, Aleksey V; Oktyabrsky, Oleg N

    2015-10-01

    The aim of the study was to elucidate a possible relationship between transmembrane cycling of glutathione and changes in levels of external superoxide. Exposure of growing Escherichia coli to exogenous reactive oxygen species (ROS) generated by xanthine and xanthine oxidase (XO) stimulates reversible glutathione (GSH) efflux from the cells that is considerably lowered under phosphate starvation. This GSH efflux is prevented by exogenous SOD, partially inhibited by catalase, and is not dependent on the GSH exporter CydDC. The ?-glutamyl transpeptidase (GGT) deficiency completely prevents a return of GSH to the cytoplasm. In contrast to wild-type E. coli, mutants devoid of GGT and glutathione reductase (GOR) show enhanced accumulation of oxidized glutathione in the medium after exposure to xanthine and XO. Under these conditions, sodC, ggt and especially gshA mutants reveal more intensive and prolonged inhibition of growth than wild-type cells. Treatment with XO does not influence E. coli viability, but somewhat increases the number of cells with lost membrane potential. In summary, data obtained here indicate that transmembrane cycling of GSH may be involved in E. coli protection against extracellular ROS and may promote rapid growth recovery. PMID:26257303

  7. Low intensity infrared laser induces filamentation in Escherichia coli cells

    NASA Astrophysics Data System (ADS)

    Fonseca, A. S.; Presta, G. A.; Geller, M.; Paoli, F.

    2011-10-01

    Low intensity continuous wave and pulsed emission modes laser is used in treating many diseases and the resulting biostimulative effect on tissues has been described, yet the photobiological basis is not well understood. The aim of this wok was to evaluate, using bacterial filamentation assay, effects of laser on Escherichia coli cultures in exponential and stationary growth phase. E. coli cultures, proficient and deficient on DNA repair, in exponential and stationary growth phase, were exposed to low intensity infrared laser, aliquots were spread onto microscopic slides, stained by Gram method, visualized by optical microscopy, photographed and percentage of bacterial filamentation were determined. Low intensity infrared laser with therapeutic fluencies and different emission modes can induce bacterial filamentation in cultures of E. coli wild type, fpg/ mutM, endonuclease III and exonuclease III mutants in exponential and stationary growth phase. This study showed induction of bacterial, filamentation in E. coli cultures expose to low intensity infrared laser and attention to laser therapy protocols, which should take into account fluencies, wavelengths, tissue conditions, and genetic characteristics of cells before beginning treatment.

  8. Resistance patterns of Escherichia coli causing urinary tract infection

    PubMed Central

    Ferdosi-Shahandashti, Elaheh; Javanian, Mostafa; Moradian-Kouchaksaraei, Masoomeh; Yeganeh, Babak; Bijani, Ali; Motevaseli, Elahe; Moradian- Kouchaksaraei, Fatemeh

    2015-01-01

    Background: Urinary tract infection (UTI) is one of the most prevalent infectious diseases and Escherichia coli is its common cause. The aim of this study was to assess the resistance patterns of E.coli in urinary tract infections and to determine the susceptibility of E.coli to commonly used antimicrobials and also to evaluate the options for empirical treatment of UTI. Methods: This study was conducted in the Ayatollah Rouhani Teaching Hospital of Babol Medical Sciences University in North of Iran. Between January of 2013 to December 2013, antimicrobial susceptibility tests were done by disk diffusion and microdilution method. Growth of >=105 cfu/ml was considered as positive urine test. Ten commonly used antibiotics were examined for susceptibility test. Data and the results were collected and analyzed. Results: E.coli grew in 57 urine samples. Imipenem, ofloxacin, ciprofloxacin were the most sensitive antibiotics at 87.7%, 87.7% and 78.9% respectively. Whereas, cotrimoxazole, cefexime, cefotaxcime and ceftriaxone were the most resistant antibiotics. Antibiotic sensitivity of disk diffusion compared minimum inhibitory concentration (MIC) detected by microdilution had the sensitivity, specificity, positive predictive value and negative predictive value of 82%, 98%, 99% and 74%, respectively. Conclusion: Imipenem, ofloxacin and ciprofloxacin should be used in empirical therapy of UTI.

  9. Magnetically-Actuated Escherichia coli System for Micro Lithography

    NASA Astrophysics Data System (ADS)

    Lauback, S.; Brown, E.; Pérez-Guzman, L.; Peace, C.; Pierce, C.; Lower, B. H.; Lower, S. K.; Sooryakumar, R.

    2015-03-01

    Technologies that control matter at the nano- and micro-scale are crucial for developing new engineered materials and devices. While the more traditional approaches for such manipulations often depend on lithographic fabrication, they can be expanded upon by taking advantage of the biological systems within a living cell which also operate on the nano- and micro- scale. In this study, a system is being developed to functionalize a targeted location on the surface of a chip with the protein AmCyan from transformed Escherichia coli cells. Using established methods in molecular biology where a plasmid with the amcyan gene sequence is inserted into the cell, E. coli are engineered to express the AmCyan protein on their outer surface. In order to transport the cells to the targeted location, the transformed E. coli are labeled with superparamagnetic micro-beads which exert directed forces on the cells in an external field. Preliminary results of the protein expression on E. coli, the transport of the cell through weak magnetic fields to targeted locations and the potential to transfer protein from the cell to the chip surface will be presented.

  10. A biologically active lectin of enteroaggregative Escherichia coli.

    PubMed

    Basu, Sulagna; Ghosh, Sujata; Ganguly, N K; Majumdar, S

    2004-01-01

    The pathogenesis of enteroaggregative Escherichia coli, a major contributor to paediatric diarrhoea, is still not clearly understood. A complex carbohydrate specific lectin was identified from the culture supernatant of an enteroaggregative E. coli strain. The lectin was purified to 660-fold by a combination of sequential saturated ammonium sulphate precipitation and gel filtration chromatography in the FPLC system. The homogeneity of the purified lectin was established by analytical isoelectrofocusing [pI 6.75]. Hemagglutination of rabbit erythrocytes by the purified lectin was best inhibited by fetuin. The N-terminal sequence of the 41.7 kDa subunit showed homology to the outermembrane porins and the 23.4 kDa subunit showed homology to a hypothetical protein of Yersinia pestis and secreted Hcp protein. This protein could induce extensive morphological changes in HEp-2 cells and significant amount of fluid accumulation in rabbit ileal loop. GM1 showed maximum binding to the lectin among all other gangliosides. This purified protein showed cross-reactivity to the binding subunit of cholera toxin in western immunoblot. The presence of this toxin in some of the clinical isolates of enteroaggregative E. coli was also observed. The structural and functional characteristics of the toxin revealed that it is a novel virulence determinant of aggregative E. coli. PMID:15556276

  11. Escherichia coli from clinical mastitis: serotypes and virulence factors.

    PubMed

    Fernandes, José Benedito C; Zanardo, Larissa G; Galvão, Newton N; Carvalho, Isabel A; Nero, Luis Augusto; Moreira, Maria Aparecida S

    2011-11-01

    In the current study, the virulence factors in Escherichia coli isolates from bovine mastitis were investigated, and the connection between these factors and infection was evaluated using phenotypic and genotypic analyses. Twenty-seven E. coli isolates were analyzed, and 2 were shown to produce verotoxin. All isolates had the ability to produce biofilms, although at different levels. One isolate was found to be sensitive to the bactericidal activity of bovine serum, 11 were intermediate, and 15 were resistant. Some isolates showed resistance to trimethoprim sulfa (9) and ampicillin (4), intermediate resistance to neomycin (1) and trimethoprim sulfa (5), and simultaneous resistance to ampicillin and trimethoprim sulfa (4). The fimH gene was found in all isolates and was associated with other virulence markers: pap (1), stb (8), cs31a (3), stb and vt2 (2), cs31a and stb (3), east1 and kps (1), stb and east1 (1), cs31a and east1 (1), and cs31a, stb, pap, and iucD (1). Serogroups were determined for 3 isolates: O93:H4, O83:H19, and O15:H11. Phylogenetic analysis showed that 23 isolates belonged to group A and 4 belonged to B1. The findings revealed that these E. coli isolates are opportunistic pathogens with different virulence factors. The results indicate that the pathogenicity route of E. coli in bovine mastitis is not a consequence of 1 specific virulence factor. PMID:22362795

  12. Influence of antibiotic pressure on bacterial bioluminescence, with emphasis on Staphylococcus aureus.

    PubMed

    Daghighi, Seyedmojtaba; Sjollema, Jelmer; Harapanahalli, Akshay; Dijkstra, Rene J B; van der Mei, Henny C; Busscher, Henk J

    2015-12-01

    Bioluminescence imaging is used for longitudinal evaluation of bacteria in live animals. Clear relations exist between bacterial numbers and their bioluminescence. However, bioluminescence images of Staphylococcus aureus Xen29, S. aureus Xen36 and Escherichia coli Xen14 grown on tryptone soy agar in Etests demonstrated increased bioluminescence at sub-MICs of different antibiotics. This study aimed to further evaluate the influence of antibiotic pressure on bioluminescence in S. aureus Xen29. Bioluminescence of S. aureus Xen29, grown planktonically in tryptone soy broth, was quantified in the absence and presence of different concentrations of vancomycin, ciprofloxacin, erythromycin or chloramphenicol and was related to expression of the luxA gene under antibiotic pressure measured using real-time PCR. In the absence of antibiotics, staphylococcal bioluminescence increased over time until a maximum after ca. 6h of growth, and subsequently decreased to the detection threshold after 24h of growth owing to reduced bacterial metabolic activity. Up to MICs of the antibiotics, bioluminescence increased according to a similar pattern up to 6h of growth, but after 24h bioluminescence was higher than in the absence of antibiotics. Contrary to expectations, bioluminescence per organism (CFU) after different growth periods in the absence and at MICs of different antibiotics decreased with increasing expression of luxA. Summarising, antibiotic pressure impacts the relation between CFU and bioluminescence. Under antibiotic pressure, bioluminescence is not controlled by luxA expression but by co-factors impacting the bacterial metabolic activity. This conclusion is of utmost importance when evaluating antibiotic efficacy in live animals using bioluminescent bacterial strains. PMID:26526893

  13. [Investigation of pathogenic Escherichia coli strains in patients with diarrhea].

    PubMed

    Ayd?n Tutak, Gülten; Tu?rul, Hamdi Murat

    2015-01-01

    The role of certain serogroups and serotypes of Escherichia coli in the etiology of gastroenteritis is increasingly appreciated. It is important to detect the virulence factors of diarrheagenic E.coli strains that differentiate them from nonpathogenic members of normal intestinal flora for the diagnosis and treatment. The aims of this study were to determine the serotypes of E.coli isolates that cause gastroenteritis and to investigate the presence of virulence genes by polymerase chain reaction (PCR). A total of 202 watery, bloody or mucoid stool samples sent to microbiology laboratory collected from patients with diarrhea who were admitted to outpatient clinics of Trakya University Health Research and Application Hospital between February to October 2009, were included in the study. A total of 254 predominantly grown E.coli strains have been isolated and identified with conventional methods from the cultures of those 202 samples. All strains were tested by slide agglutination (SA) that includes 6 units of O serogroups polyvalent antisera of enteropathogenic E.coli (EPEC), enterotoxigenic E.coli (ETEC) and enteroinvasive E.coli (EIEC). The samples which yielded positive results with SA test and the same number of negative samples selected with mapping method as controls were studied for the presence of virulence genes belonging EPEC, ETEC and EIEC by conventional PCR. In the study, 14.3% (29/202) of the samples were serogrouped with SA, of them 13 (6.4%) were identified as EPEC, 11 (5.4%) as EIEC and five (2.4%) as ETEC. Only five isolates belonging to EPEC serogroup could be defined by monovalent antiserum and they were all in O1 serogroup. Out of 29 pathogenic E.coli serotyped, 3 (10.3%) of them harbored the virulence genes of diarrheagenic strains. One sample which was positive for eaeA gene of EPEC, did not harbor bfpA and stx genes and was defined as atypical EPEC. Out of other two samples, one was positive for estA gene of ETEC and the other one for ial gene of EIEC. One strain serotyped as EPEC detected to carry estA gene of ETEC with PCR. All of the 29 control isolates that give negative results with polyvalent antisera were also negative for the presence of virulence genes. In conclusion, since serotyping and conventional PCR methods did not reveal similar results for the identification of pathogenic E.coli, multicenter and large-scaled studies performed with standardized methods are needed. PMID:25706738

  14. Translocation and thermal inactivation of Shiga-toxin producing Escherichia coli in non-intact beef

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We compared translocation of genetically-marked strains of serotype O157:H7 Escherichia coli (ECOH) to non-O157:H7 Shiga-Toxin producing Escherichia coli (STEC) following blade tenderization of beef subprimals and the subsequent lethality of these pathogens following cooking of steaks prepared from ...

  15. Nano-optical Trapping of Rayleigh Particles and Escherichia coli Bacteria

    E-print Network

    Nano-optical Trapping of Rayleigh Particles and Escherichia coli Bacteria with Resonant Optical demonstrate a novel optical trapping scheme that allows us to hold living Escherichia coli bacteria bacteria are trapped simultaneously with their orientation fixed by the asymmetry of the antennas

  16. Crystal Structure of the Acid-Induced Arginine Decarboxylase from Escherichia coli: Reversible Decamer Assembly Controls

    E-print Network

    Palmer, Tracy

    Crystal Structure of the Acid-Induced Arginine Decarboxylase from Escherichia coli: Reversible: The acid-induced arginine decarboxylase is part of an enzymatic system in Escherichia coli that contributes to making this organism acid resistant. The arginine decarboxylase is a vitamin B6-dependent enzyme

  17. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ...-Producing Escherichia coli in Certain Raw Beef Products AGENCY: Food Safety and Inspection Service, USDA... for controlling non-O157 Shiga toxin-producing Escherichia coli in raw, intact and non-intact beef... September 20, 2011, document announcing these plans and methods (76 FR 58157), FSIS asked for comments on...

  18. Tunable Stochastic Pulsing in the Escherichia coli Multiple Antibiotic Resistance Network from Interlinked

    E-print Network

    Dunlop, Mary

    Tunable Stochastic Pulsing in the Escherichia coli Multiple Antibiotic Resistance Network from a stochastic model of the multiple antibiotic resistance network of Escherichia coli and show that it can Multiple Antibiotic Resistance Network from Interlinked Positive and Negative Feedback Loops. PLoS Comput

  19. Self-Organization of the Escherichia coli Chemotaxis Network Imaged with Super-Resolution Light Microscopy

    E-print Network

    Self-Organization of the Escherichia coli Chemotaxis Network Imaged with Super-Resolution Light of California Berkeley, Berkeley, California, United States of America Abstract The Escherichia coli chemotaxis, it remains unclear how chemotaxis clusters form, what controls cluster size and density, and how the cellular

  20. Single-molecule studies of fork dynamics in Escherichia coli DNA replication

    E-print Network

    Single-molecule studies of fork dynamics in Escherichia coli DNA replication Nathan A Tanner1,4 & Antoine M van Oijen1 We present single-molecule studies of the Escherichia coli replication machinery. We and leading-strand synthesis. When coupled to the replicative helicase DnaB, Pol III mediates leading

  1. Inhibition of the ATPase activity of Escherichia coli ATP synthase by magnesium fluoride

    E-print Network

    Zulfiqar Ahmad

    Inhibition of the ATPase activity of Escherichia coli ATP synthase by magnesium fluoride Zulfiqar activity of Escherichia coli ATP synthase by magnesium fluoride (MgFx) was studied. Wild-type F1-ATPase synthesis mechanism; Magnesium fluoride; ATPase inhibition; Transition state analog 1. Introduction ATP

  2. Global RNA Half-Life Analysis in Escherichia coli Reveals Positional Patterns of Transcript Degradation

    E-print Network

    Church, George M.

    to study global RNA degradation in wild-type Escherichia coli MG1655. RNA chemical half-lives were measuredGlobal RNA Half-Life Analysis in Escherichia coli Reveals Positional Patterns of TranscriptRNA was 6.8 min under the conditions tested. We also observed significant relationships between gene

  3. In situ bioprocess monitoring of Escherichia coli bioreactions using Raman spectroscopy

    E-print Network

    Sinskey, Anthony J.

    In situ bioprocess monitoring of Escherichia coli bioreactions using Raman spectroscopy Harry L from in situ measured Raman spectra in Escherichia coli bioreactions. Attenuation due to light for early identification of poor growth conditions, increasing overall experimental throughput. In all cases

  4. Evaluating the role of sediment-bacteria interactions on Escherichia coli concentrations at beaches in southern Lake Michigan

    E-print Network

    Evaluating the role of sediment-bacteria interactions on Escherichia coli concentrations at beaches- bacteria interactions on Escherichia coli (EC) levels at beaches in southern Lake Michigan using three indicate that a majority of the fecal indicator bacteria (FIB) such as Escherichia coli (EC) are associated

  5. The 2B domain of the Escherichia coli Rep protein is not required for DNA helicase activity

    E-print Network

    Lohman, Timothy M.

    The 2B domain of the Escherichia coli Rep protein is not required for DNA helicase activity Wei, and approved October 9, 2002 (received for review August 8, 2002) The Escherichia coli Rep protein is a 3 to 5. The Escherichia coli Rep protein is a 3 to 5 SF1 superfamily DNA helicase that has been characterized both

  6. A Theoretical Interpretation of the Transient Sialic Acid Toxicity of a nanR Mutant of Escherichia coli

    E-print Network

    Kent, University of

    Available online 7 November 2007 This article reports on experimental evidence that an Escherichia coli nan rights reserved. Edited by J. Kam Keywords: Escherichia coli; N-Acetylneuraminic acid; GlcNAc-6P toxicity bacteria that colonize animal hosts, even though some, such as Escherichia coli, lack a sialidase and hence

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

    E-print Network

    Gini, Giuseppina

    to bacteria Escherichia coli Andrey A. Toropov a, , Alla P. Toropova a , Emilio Benfenati a , Giuseppina Gini Keywords: QSAR CORAL software Cytotoxicity to bacterium Escherichia coli Metal oxide nanoparticle a b s t r of cytotoxicity of metal oxide nanoparticles to bacteria Escherichia coli (minus logarithm of concentration for 50

  8. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Escherichia coli O157:H7 specific... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1301 Escherichia coli O157:H7 specific... Escherichia coli O157:H7, sequence negative for shiga toxins I and II, and grown on atoxigenic host...

  9. Escherichia coli RecX Inhibits RecA Recombinase and Coprotease Activities in Vitro and in Vivo*

    E-print Network

    Kowalczykowski, Stephen C.

    Escherichia coli RecX Inhibits RecA Recombinase and Coprotease Activities in Vitro and in Vivo and Development, University of California, Davis, California 95616 In Escherichia coli the RecA protein playsA recombinase and coprotease activities. The Escherichia coli RecA protein plays a central role in homologous

  10. The diffusive influx and carrier efflux have a strong effect on the bistability of the lac operon in Escherichia coli

    E-print Network

    Pilyugin, Sergei S.

    in Escherichia coli Jason T. Noel a , Sergei S. Pilyugin b , Atul Narang c,Ã a Department of Chemical Engineering of Escherichia coli exhibits bistability. Most models in the literature assume that the inducer enters the cell of lac bistability during growth of Escherichia coli K12 MG1655 on TMG and succinate/glucose. To this end

  11. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Escherichia coli O157:H7 specific... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1301 Escherichia coli O157:H7 specific... Escherichia coli O157:H7, sequence negative for shiga toxins I and II, and grown on atoxigenic host...

  12. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Escherichia coli O157:H7 specific... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1301 Escherichia coli O157:H7 specific... Escherichia coli O157:H7, sequence negative for shiga toxins I and II, and grown on atoxigenic host...

  13. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Escherichia coli O157:H7 specific... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1301 Escherichia coli O157:H7 specific... Escherichia coli O157:H7, sequence negative for shiga toxins I and II, and grown on atoxigenic host...

  14. Dynamic structures in Escherichia coli: Spontaneous formation of MinE rings and MinD polar zones

    E-print Network

    Meir, Yigal

    Dynamic structures in Escherichia coli: Spontaneous formation of MinE rings and MinD polar zones, 2003 (received for review June 26, 2003) In Escherichia coli, division site selection is regulated role in proper chromosome and plasmid partitioning. In Escherichia coli, two systems are known

  15. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 2011-07-01 false Escherichia coli O157:H7 specific bacteriophages; temporary...Tolerances § 180.1301 Escherichia coli O157:H7 specific bacteriophages...bacteriophages that are specific to Escherichia coli O157:H7, sequence negative...

  16. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Escherichia coli O157:H7 specific bacteriophages; temporary...Tolerances § 180.1301 Escherichia coli O157:H7 specific bacteriophages...bacteriophages that are specific to Escherichia coli O157:H7, sequence negative...

  17. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Escherichia coli O157:H7 specific bacteriophages; temporary...Tolerances § 180.1301 Escherichia coli O157:H7 specific bacteriophages...bacteriophages that are specific to Escherichia coli O157:H7, sequence negative...

  18. 40 CFR 180.1301 - Escherichia coli O157:H7 specific bacteriophages; temporary exemption from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Escherichia coli O157:H7 specific bacteriophages; temporary...Tolerances § 180.1301 Escherichia coli O157:H7 specific bacteriophages...bacteriophages that are specific to Escherichia coli O157:H7, sequence negative...

  19. Insertion sequence 5 at various upstream locations of the flhDC operon causes Escherichia coli hyper motility

    E-print Network

    Wang, Jing

    2010-01-01

    Identification and molecular characterization of csrA, a pleiotropic gene from Escherichia coliIdentification of additional genes belonging to the LexA regulon in Escherichia coli.Identification of high affinity binding sites for LexA which define new DNA damage-inducible genes in Escherichia coli.

  20. VECTOR/PATHOGEN/HOST INTERACTION, TRANSMISSION Persistence of Escherichia coli in Immature House Fly and Stable Fly

    E-print Network

    Selinger, Brent

    ARE asymptomatic carriers of Escherichia coli O157:H7 (Zhao et al. 1995), and are the primary reservoirsVECTOR/PATHOGEN/HOST INTERACTION, TRANSMISSION Persistence of Escherichia coli in Immature House of Escherichia coli in artiÞcially fed larvae was examined for up to 48 h after ingestion by house ßies, Musca

  1. Significant Escherichia coli attenuation by vegetative buffers on annual grasslands.

    PubMed

    Tate, Kenneth W; Atwill, Edward R; Bartolome, James W; Nader, Glenn

    2006-01-01

    A study was conducted to estimate the retention efficiency of vegetative buffers for Escherichia coli deposited on grasslands in cattle fecal deposits and subject to natural rainfall-runoff conditions. The study was conducted on annual grasslands in California's northern Sierra Nevada foothills, a region with a distinct wet-dry season Mediterranean climate. We used 48, 2.0- by 3.0-m runoff plots to examine the efficacy of 0.1-, 1.1-, and 2.1-m buffers at three land slopes (5, 20, and 35%) and four dry vegetation matter levels (225, 560, 900, and 4500 kg/ha) across 27 rainfall-runoff events during two rainfall seasons. Buffer width treatments were implemented by placement of cattle fecal material containing known loads of E. coli 0.1, 1.1, or 2.1 m upslope of the plot runoff collector. Mean total runoff to total rainfall ratio per plot ranged from 0.014:1 to 0.019:1 and reflected the high infiltration capacity of these soils. Approximately 94.8 to 99.995% of total E. coli load applied to each plot appears to be either retained in the fecal pat and/or attenuated within 0.1 m downslope of the fecal pat, irrespective of the presence of a wider vegetated buffer. Relative to a 0.1-m buffer, we found 0.3 to 3.1 log10 reduction in E. coli discharge per additional meter of vegetative buffer across the range of residual dry vegetation matter levels, land slope, and rainfall and runoff conditions experienced during this project. Buffer efficiency was significantly reduced as runoff increased. These results support the assertion that grassland buffers are an effective method for reducing animal agricultural inputs of waterborne E. coli into surface waters. PMID:16585622

  2. Codon Optimisation Is Key for Pernisine Expression in Escherichia coli

    PubMed Central

    Šnajder, Marko; Miheli?, Marko; Turk, Dušan; Ulrih, Nataša Poklar

    2015-01-01

    Background Pernisine is an extracellular serine protease from the hyperthermophilic Archaeon Aeropyrum pernix K1. Low yields from the natural host and expression problems in heterologous hosts have limited the potential applications of pernisine in industry. Methodology/ Principal Findings The challenges of pernisine overexpression in Escherichia coli were overcome by codon preference optimisation and de-novo DNA synthesis. The following forms of the pernisine gene were cloned into the pMCSGx series of vectors and expressed in E. coli cells: wild-type (pernisinewt), codon-optimised (pernisineco), and codon-optimised with a S355A mutation of a predicted active site (pernisineS355Aco). The fusion-tagged pernisines were purified using fast protein liquid chromatography equipped with Ni2+ chelate and gel filtration chromatography columns. The identities of the resultant proteins were confirmed with N-terminal sequencing, tandem mass spectrometry analysis, and immunodetection. Pernisinewt was not expressed in E. coli at detectable levels, while pernisineco and pernisineS355Aco were expressed and purified as 55-kDa proforms with yields of around 10 mg per litre E. coli culture. After heat activation of purified pernisine, the proteolytic activity of the mature pernisineco was confirmed using zymography, at a molecular weight of 36 kDa, while the mutant pernisineS355Aco remained inactive. Enzymatic performances of pernisine evaluated under different temperatures and pHs demonstrate that the optimal enzymatic activity of the recombinant pernisine is ca. 100°C and pH 7.0, respectively. Conclusions/ Significance These data demonstrate that codon optimisation is crucial for pernisine overexpression in E. coli, and that the proposed catalytic Ser355 has an important role in pernisine activity, but not in its activation process. Pernisine is activated by autoproteolytical cleavage of its N-terminal proregion. We have also confirmed that the recombinant pernisine retains the characteristics of native pernisine, as a calcium modulated thermostable serine protease. PMID:25856104

  3. Genomic and Phenomic Study of Mammary Pathogenic Escherichia coli.

    PubMed

    Blum, Shlomo E; Heller, Elimelech D; Sela, Shlomo; Elad, Daniel; Edery, Nir; Leitner, Gabriel

    2015-01-01

    Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to acute mastitis and causing great economic losses in dairy production worldwide. Particular strains cause persistent IMI, leading to recurrent mastitis. Virulence factors of mammary pathogenic E. coli (MPEC) involved pathogenesis of mastitis as well as those differentiating strains causing acute or persistent mastitis are largely unknown. This study aimed to identify virulence markers in MPEC through whole genome and phenome comparative analysis. MPEC strains causing acute (VL2874 and P4) or persistent (VL2732) mastitis were compared to an environmental strain (K71) and to the genomes of strains representing different E. coli pathotypes. Intra-mammary challenge in mice confirmed experimentally that the strains studied here have different pathogenic potential, and that the environmental strain K71 is non-pathogenic in the mammary gland. Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes. Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism. Features associated with cytotoxicity or intra-cellular survival were found specifically in the genomes of strains from severe and acute (VL2874) or persistent (VL2732) mastitis, respectively. MPEC genomes were relatively similar to strain K-12, which was subsequently shown here to be possibly pathogenic in the mammary gland. Phenome analysis showed that the persistent MPEC was the most versatile in terms of nutrients metabolized and acute MPEC the least. Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism. This study reveals virulence factors and phenotypic characteristics of MPEC that may play a role in pathogenesis of E. coli mastitis. PMID:26327312

  4. Genomic and Phenomic Study of Mammary Pathogenic Escherichia coli

    PubMed Central

    Blum, Shlomo E.; Heller, Elimelech D.; Sela, Shlomo; Elad, Daniel; Edery, Nir; Leitner, Gabriel

    2015-01-01

    Escherichia coli is a major etiological agent of intra-mammary infections (IMI) in cows, leading to acute mastitis and causing great economic losses in dairy production worldwide. Particular strains cause persistent IMI, leading to recurrent mastitis. Virulence factors of mammary pathogenic E. coli (MPEC) involved pathogenesis of mastitis as well as those differentiating strains causing acute or persistent mastitis are largely unknown. This study aimed to identify virulence markers in MPEC through whole genome and phenome comparative analysis. MPEC strains causing acute (VL2874 and P4) or persistent (VL2732) mastitis were compared to an environmental strain (K71) and to the genomes of strains representing different E. coli pathotypes. Intra-mammary challenge in mice confirmed experimentally that the strains studied here have different pathogenic potential, and that the environmental strain K71 is non-pathogenic in the mammary gland. Analysis of whole genome sequences and predicted proteomes revealed high similarity among MPEC, whereas MPEC significantly differed from the non-mammary pathogenic strain K71, and from E. coli genomes from other pathotypes. Functional features identified in MPEC genomes and lacking in the non-mammary pathogenic strain were associated with synthesis of lipopolysaccharide and other membrane antigens, ferric-dicitrate iron acquisition and sugars metabolism. Features associated with cytotoxicity or intra-cellular survival were found specifically in the genomes of strains from severe and acute (VL2874) or persistent (VL2732) mastitis, respectively. MPEC genomes were relatively similar to strain K-12, which was subsequently shown here to be possibly pathogenic in the mammary gland. Phenome analysis showed that the persistent MPEC was the most versatile in terms of nutrients metabolized and acute MPEC the least. Among phenotypes unique to MPEC compared to the non-mammary pathogenic strain were uric acid and D-serine metabolism. This study reveals virulence factors and phenotypic characteristics of MPEC that may play a role in pathogenesis of E. coli mastitis. PMID:26327312

  5. Metabolic engineering of Escherichia coli to produce zeaxanthin.

    PubMed

    Li, Xi-Ran; Tian, Gui-Qiao; Shen, Hong-Jie; Liu, Jian-Zhong

    2015-04-01

    Zeaxanthin is a high-value carotenoid that is used in nutraceuticals, cosmetics, food, and animal feed industries. Zeaxanthin is chemically synthesized or purified from microorganisms as a natural product; however, increasing demand requires development of alternative sources such as heterologous biosynthesis by recombinant bacteria. For this purpose, we molecularly engineered Escherichia coli to optimize the synthesis of zeaxanthin from lycopene using fusion protein-mediated substrate channeling as well as by the introduction of tunable intergenic regions. The tunable intergenic regions approach was more efficient compared with protein fusion for coordinating expression of lycopene ?-cyclase gene crtY and ?-carotene 3-hydroxylase gene crtZ. The influence of the substrate channeling effect suggests that the reaction catalyzed by CrtZ is the rate-limiting step in zeaxanthin biosynthesis. Then Pantoea ananatis, Pantoea agglomerans and Haematococcus pluvialis crtZ were compared. Because P. ananatis crtZ is superior to that of P. agglomerans or H. pluvialis for zeaxanthin production, we used it to generate a recombinant strain of E. coli BETA-1 containing pZSPBA-2(P37-crtZPAN) that produced higher amounts of zeaxanthin (11.95 ± 0.21 mg/g dry cell weight) than other engineered E. coli strains described in the literature. PMID:25533633

  6. Characterization of the YdeO Regulon in Escherichia coli

    PubMed Central

    Yamanaka, Yuki; Oshima, Taku; Ishihama, Akira; Yamamoto, Kaneyoshi

    2014-01-01

    Enterobacteria are able to survive under stressful conditions within animals, such as acidic conditions in the stomach, bile salts during transfer to the intestine and anaerobic conditions within the intestine. The glutamate-dependent (GAD) system plays a major role in acid resistance in Escherichia coli, and expression of the GAD system is controlled by the regulatory cascade consisting of EvgAS > YdeO > GadE. To understand the YdeO regulon in vivo, we used ChIP-chip to interrogate the E. coli genome for candidate YdeO binding sites. All of the seven operons identified by ChIP-chip as being potentially regulated by YdeO were confirmed as being under the direct control of YdeO using RT-qPCR, EMSA, DNaseI-footprinting and reporter assays. Within this YdeO regulon, we identified four stress-response transcription factors, DctR, NhaR, GadE, and GadW and enzymes for anaerobic respiration. Both GadE and GadW are involved in regulation of the GAD system and NhaR is an activator for the sodium/proton antiporter gene. In conjunction with co-transcribed Slp, DctR is involved in protection against metabolic endoproducts under acidic conditions. Taken all together, we suggest that YdeO is a key regulator of E. coli survival in both acidic and anaerobic conditions. PMID:25375160

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

    PubMed

    Hu, Pingzhao; Janga, Sarath Chandra; Babu, Mohan; Díaz-Mejía, J Javier; Butland, Gareth; Yang, Wenhong; Pogoutse, Oxana; Guo, Xinghua; Phanse, Sadhna; Wong, Peter; Chandran, Shamanta; Christopoulos, Constantine; Nazarians-Armavil, Anaies; Nasseri, Negin Karimi; Musso, Gabriel; Ali, Mehrab; Nazemof, Nazila; Eroukova, Veronika; Golshani, Ashkan; Paccanaro, Alberto; Greenblatt, Jack F; Moreno-Hagelsieb, Gabriel; Emili, Andrew

    2009-04-28

    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. PMID:19402753

  8. Colibri: a functional data base for the Escherichia coli genome.

    PubMed Central

    Médigue, C; Viari, A; Hénaut, A; Danchin, A

    1993-01-01

    Several data libraries have been created to organize all the data obtained worldwide about the Escherichia coli genome. Because the known data now amount to more than 40% of the whole genome sequence, it has become necessary to organize the data in such a way that appropriate procedures can associate knowledge produced by experiments about each gene to its position on the chromosome and its relation to other relevant genes, for example. In addition, global properties of genes, affected by the introduction of new entries, should be present as appropriate description fields. A data base, implemented on Macintosh by using the data base management system 4th Dimension, is described. It is constructed around a core constituted by known contigs of E. coli sequences and links data collected in general libraries (unmodified) to data associated with evolving knowledge (with modifiable fields). Biologically significant results obtained through the coupling of appropriate procedures (learning or statistical data analysis) are presented. The data base is available through a 4th Dimension runtime and through FTP on Internet. It has been regularly updated and will be systematically linked to other E. coli data bases (M. Kroger, R. Wahl, G. Schachtel, and P. Rice, Nucleic Acids Res. 20(Suppl.):2119-2144, 1992; K. E. Rudd, W. Miller, C. Werner, J. Ostell, C. Tolstoshev, and S. G. Satterfield, Nucleic Acids Res. 19:637-647, 1991) in the near future. Images PMID:8246843

  9. Rapid Method for Escherichia coli in the Cuyahoga River

    USGS Publications Warehouse

    Brady, Amie M.G.

    2007-01-01

    This study is a continuation of a previous U.S. Geological Survey (USGS) project in cooperation with the National Park Service at Cuyahoga Valley National Park in Brecksville, Ohio. A rapid (1-hour) method for detecting Escherichia coli (E. coli) in water was tested and compared to the standard (24-hour) method for determining E. coli concentrations. Environmental data were collected to determine turbidity, rainfall, and streamflow at the time of sampling. In the previous study (2004-5), data collected were used to develop predictive models to determine recreational water quality in the river at two sites within the park. Data collected during this continued study (2006) were used to test these models. At Jaite, a centrally located site within the park, the model correctly predicted exceedances or nonexceedances of the Ohio Environmental Protection Agency maximum for recreational water quality in 80 percent of samples. At Old Portage, a site near the upstream boundary of the park, the model correctly predicted recreational water quality in 58 percent of samples. All of the data collected in 2004-6 will be used to develop more accurate models for use in future studies. Analysis and discussion of model results are scheduled to be included in an upcoming USGS Scientific Investigations Report.

  10. Instability of Pathogenicity Islands in Uropathogenic Escherichia coli 536

    PubMed Central

    Middendorf, Barbara; Hochhut, Bianca; Leipold, Kristina; Dobrindt, Ulrich; Blum-Oehler, Gabriele; Hacker, Jörg

    2004-01-01

    The uropathogenic Escherichia coli strain 536 carries at least five genetic elements on its chromosome that meet all criteria characteristic of pathogenicity islands (PAIs). One main feature of these distinct DNA regions is their instability. We applied the so-called island-probing approach and individually labeled all five PAIs of E. coli 536 with the counterselectable marker sacB to evaluate the frequency of PAI-negative colonies under the influence of different environmental conditions. Furthermore, we investigated the boundaries of these PAIs. According to our experiments, PAI II536 and PAI III536 were the most unstable islands followed by PAI I536 and PAI V536, whereas PAI IV536 was stable. In addition, we found that deletion of PAI II536 and PAI III536 was induced by several environmental stimuli. Whereas excision of PAI I536, PAI II536, and PAI V536 was based on site-specific recombination between short direct repeat sequences at their boundaries, PAI III536 was deleted either by site-specific recombination or by homologous recombination between two IS100-specific sequences. In all cases, deletion is thought to lead to the formation of nonreplicative circular intermediates. Such extrachromosomal derivatives of PAI II536 and PAI III536 were detected by a specific PCR assay. Our data indicate that the genome content of uropathogenic E. coli can be modulated by deletion of PAIs. PMID:15126470

  11. K antigen and serum sensitivity of rough Escherichia coli.

    PubMed Central

    Opal, S; Cross, A; Gemski, P

    1982-01-01

    We prepared bacterial hybrids which express both K1 and K27 antigens and examined the relative contributions of these capsules to serum resistance. Escherichia coli Hfr strain F639 (rough, K27+, serum sensitive) was conjugated with E. coli recipient strain E412 (rough, K1+, His- Trp- Strr, serum resistant). Transconjugants which inherited both the his and trp linked genes for K27 antigen synthesis were analyzed. These hybrids retained and expressed the K1 antigen since the K1 locus is nonallelic with K27 gene loci. Hybrid strains which express both K1 and K27 antigens exhibit serum resistance, but not at the level of the K1+ parental strain. An isogenic K1 derivative of a hybrid which expressed only K27 antigen was serum sensitive (greater than 99% kill, 60 min). These findings indicate that the presence of the K1 capsular antigen can protect some rough strains of E. coli from serum bactericidal activity, whereas K27 and perhaps other K antigens fail to provide such a protective effect. PMID:6752031

  12. Identification of phosphatidylserylglutamate: a novel minor lipid in Escherichia coli

    PubMed Central

    Garrett, Teresa A.; Raetz, Christian R. H.; Richardson, Travis; Kordestani, Reza; Son, Jennifer D.; Rose, Rebecca L.

    2009-01-01

    Advances in mass spectrometry have facilitated the identification of novel lipid structures. In this work, we fractionated the lipids of Escherichia coli B and analyzed the fractions using negative-ion electrospray ionization mass spectrometry to reveal unknown lipid structures. Analysis of a fraction eluting with high salt from DEAE cellulose revealed a series of ions not corresponding to any of the known lipids of E. coli. The ions, with m/z 861.5, 875.5, 887.5, 889.5, and 915.5, were analyzed using collision-induced dissociation mass spectrometry (MS/MS) and yielded related fragmentation patterns consistent with a novel diacylated glycerophospholipid. Product ions arising by neutral loss of 216 mass units were observed with all of the unknowns. A corresponding negative product ion was also observed at m/z 215.0. Additional ions at m/z 197.0, 171.0, 146.0, and 128.0 were used to propose the novel structure phosphatidylserylglutamate (PSE). The hypothesized structure was confirmed by comparison with the MS/MS spectrum of a synthetic standard. Normal phase liquid chromatography-mass spectrometry analysis further showed that the endogenous PSE and synthetic PSE eluted with the same retention times. PSE was also observed in the equivalent anion exchange fractions of total lipids extracted from the wild-type E. coli K-12 strain MG1655. PMID:19096047

  13. Identification of Diarrheagenic Escherichia coli Strains from Avian Organic Fertilizers

    PubMed Central

    Puño-Sarmiento, Juan; Gazal, Luis Eduardo; Medeiros, Leonardo P.; Nishio, Erick K.; Kobayashi, Renata K. T.; Nakazato, Gerson

    2014-01-01

    The Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family. The objective of this study was to detect the presence of diarrheagenic Escherichia coli (DEC) strains in avian organic fertilizer, and assess the potential damage they can cause in humans due to antimicrobial resistance. The presence of DEC pathotypes and phylogenetic groups were detected by multiplex-PCR. Phenotypic assays, such as tests for adhesion, cytotoxicity activity, biofilm formation and especially antimicrobial susceptibility, were performed. Fifteen DEC strains from 64 E. coli were isolated. Among these, four strains were classified as enteropathogenic (EPEC; 6.2%), three strains as Shiga toxin-producing (STEC; 4.7%), 10 strains as enteroaggregative (EAEC; 12.5%), but two of these harbored the eaeA gene too. The low number of isolated strains was most likely due to the composting process, which reduces the number of microorganisms. These strains were able to adhere to HEp-2 and HeLa cells and produce Shiga-toxins and biofilms; in addition, some of the strains showed antimicrobial resistance, which indicates a risk of the transfer of resistance genes to human E. coli. These results showed that DEC strains isolated from avian organic fertilizers can cause human infections. PMID:25170683

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

    NASA Astrophysics Data System (ADS)

    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 is similar to the chemotactic impulse response: both follow a similar time course, share the same directionality, and show biphasic characteristics. 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.

  15. Operons in Escherichia coli: genomic analyses and predictions.

    PubMed

    Salgado, H; Moreno-Hagelsieb, G; Smith, T F; Collado-Vides, J

    2000-06-01

    The rich knowledge of operon organization in Escherichia coli, together with the completed chromosomal sequence of this bacterium, enabled us to perform an analysis of distances between genes and of functional relationships of adjacent genes in the same operon, as opposed to adjacent genes in different transcription units. We measured and demonstrated the expected tendencies of genes within operons to have much shorter intergenic distances than genes at the borders of transcription units. A clear peak at short distances between genes in the same operon contrasts with a flat frequency distribution of genes at the borders of transcription units. Also, genes in the same operon tend to have the same physiological functional class. The results of these analyses were used to implement a method to predict the genomic organization of genes into transcription units. The method has a maximum accuracy of 88% correct identification of pairs of adjacent genes to be in an operon, or at the borders of transcription units, and correctly identifies around 75% of the known transcription units when used to predict the transcription unit organization of the E. coli genome. Based on the frequency distance distributions, we estimated a total of 630 to 700 operons in E. coli. This step opens the possibility of predicting operon organization in other bacteria whose genome sequences have been finished. PMID:10823905

  16. Operons in Escherichia coli: Genomic analyses and predictions

    PubMed Central

    Salgado, Heladia; Moreno-Hagelsieb, Gabriel; Smith, Temple F.; Collado-Vides, Julio

    2000-01-01

    The rich knowledge of operon organization in Escherichia coli, together with the completed chromosomal sequence of this bacterium, enabled us to perform an analysis of distances between genes and of functional relationships of adjacent genes in the same operon, as opposed to adjacent genes in different transcription units. We measured and demonstrated the expected tendencies of genes within operons to have much shorter intergenic distances than genes at the borders of transcription units. A clear peak at short distances between genes in the same operon contrasts with a flat frequency distribution of genes at the borders of transcription units. Also, genes in the same operon tend to have the same physiological functional class. The results of these analyses were used to implement a method to predict the genomic organization of genes into transcription units. The method has a maximum accuracy of 88% correct identification of pairs of adjacent genes to be in an operon, or at the borders of transcription units, and correctly identifies around 75% of the known transcription units when used to predict the transcription unit organization of the E. coli genome. Based on the frequency distance distributions, we estimated a total of 630 to 700 operons in E. coli. This step opens the possibility of predicting operon organization in other bacteria whose genome sequences have been finished. PMID:10823905

  17. Structure of Escherichia coli After Freeze-Etching

    PubMed Central

    Bayer, M. E.; Remsen, C. C.

    1970-01-01

    Survival of Escherichia coli, quick-frozen under conditions similar to those employed for freeze-etching, is close to 100%. For determination of cell shrinkage, the diameters of freeze-etched E. coli cells (average, 0.99 ?m) were compared with those of preparations after negative staining and after ultrathin sectioning. Negatively stained cells measured from 0.65 to 1.0 ?m in diameter, and ultrathin sections showed average cell diameters of 0.70 ?m. Freeze-etched replicas of logarithmically growing, as well as stationary, E. coli B cells revealed a smooth, finely pitted cell surface in contrast to cell surfaces seen with other preparative methods. The frozen cell wall may cleave in two planes, exposing (i) a smooth fracture face within the lipid layer and (ii) in rare instances an ill-defined particulate layer. Most frequently, however, cleavage of the envelope occurred between wall and protoplasmic membrane; large areas of the membrane were then exposed and showed a surface studded with predominantly spherical particles, an appearance which did not significantly change when the cells were fixed in formaldehyde and osmium tetroxide before freeze-etching. The distribution of these particles differed between logarithmically growing cells and stationary cells. Images PMID:4189229

  18. Metabolic Engineering of Escherichia coli for the Production of Xylonate

    PubMed Central

    Cao, Yujin; Xian, Mo; Zou, Huibin; Zhang, Haibo

    2013-01-01

    Xylonate is a valuable chemical for versatile applications. Although the chemical synthesis route and microbial conversion pathway were established decades ago, no commercial production of xylonate has been obtained so far. In this study, the industrially important microorganism Escherichia coli was engineered to produce xylonate from xylose. Through the coexpression of a xylose dehydrogenase (xdh) and a xylonolactonase (xylC) from Caulobacter crescentus, the recombinant strain could convert 1 g/L xylose to 0.84 g/L xylonate and 0.10 g/L xylonolactone after being induced for 12 h. Furthermore, the competitive pathway for xylose catabolism in E. coli was blocked by disrupting two genes (xylA and xylB) encoding xylose isomerase and xylulose kinase. Under fed-batch conditions, the finally engineered strain produced up to 27.3 g/L xylonate and 1.7 g/L xylonolactone from 30 g/L xylose, about 88% of the theoretical yield. These results suggest that the engineered E. coli strain has a promising perspective for large-scale production of xylonate. PMID:23861757

  19. Identification of diarrheagenic Escherichia coli strains from avian organic fertilizers.

    PubMed

    Puño-Sarmiento, Juan; Gazal, Luis Eduardo; Medeiros, Leonardo P; Nishio, Erick K; Kobayashi, Renata K T; Nakazato, Gerson

    2014-09-01

    The Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family. The objective of this study was to detect the presence of diarrheagenic Escherichia coli (DEC) strains in avian organic fertilizer, and assess the potential damage they can cause in humans due to antimicrobial resistance. The presence of DEC pathotypes and phylogenetic groups were detected by multiplex-PCR. Phenotypic assays, such as tests for adhesion, cytotoxicity activity, biofilm formation and especially antimicrobial susceptibility, were performed. Fifteen DEC strains from 64 E. coli were isolated. Among these, four strains were classified as enteropathogenic (EPEC; 6.2%), three strains as Shiga toxin-producing (STEC; 4.7%), 10 strains as enteroaggregative (EAEC; 12.5%), but two of these harbored the eaeA gene too. The low number of isolated strains was most likely due to the composting process, which reduces the number of microorganisms. These strains were able to adhere to HEp-2 and HeLa cells and produce Shiga-toxins and biofilms; in addition, some of the strains showed antimicrobial resistance, which indicates a risk of the transfer of resistance genes to human E. coli. These results showed that DEC strains isolated from avian organic fertilizers can cause human infections. PMID:25170683

  20. Structural interconversions modulate activity of Escherichia coli ribonucleotide reductase.

    PubMed

    Ando, Nozomi; Brignole, Edward J; Zimanyi, Christina M; Funk, Michael A; Yokoyama, Kenichi; Asturias, Francisco J; Stubbe, Joanne; Drennan, Catherine L

    2011-12-27

    Essential for DNA biosynthesis and repair, ribonucleotide reductases (RNRs) convert ribonucleotides to deoxyribonucleotides via radical-based chemistry. Although long known that allosteric regulation of RNR activity is vital for cell health, the molecular basis of this regulation has been enigmatic, largely due to a lack of structural information about how the catalytic subunit (?(2)) and the radical-generation subunit (?(2)) interact. Here we present the first structure of a complex between ?(2) and ?(2) subunits for the prototypic RNR from Escherichia coli. Using four techniques (small-angle X-ray scattering, X-ray crystallography, electron microscopy, and analytical ultracentrifugation), we describe an unprecedented ?(4)?(4) ring-like structure in the presence of the negative activity effector dATP and provide structural support for an active ?(2)?(2) configuration. We demonstrate that, under physiological conditions, E. coli RNR exists as a mixture of transient ?(2)?(2) and ?(4)?(4) species whose distributions are modulated by allosteric effectors. We further show that this interconversion between ?(2)?(2) and ?(4)?(4) entails dramatic subunit rearrangements, providing a stunning molecular explanation for the allosteric regulation of RNR activity in E. coli. PMID:22160671

  1. Structural interconversions modulate activity of Escherichia coli ribonucleotide reductase

    PubMed Central

    Ando, Nozomi; Brignole, Edward J.; Zimanyi, Christina M.; Funk, Michael A.; Yokoyama, Kenichi; Asturias, Francisco J.; Stubbe, JoAnne; Drennan, Catherine L.

    2011-01-01

    Essential for DNA biosynthesis and repair, ribonucleotide reductases (RNRs) convert ribonucleotides to deoxyribonucleotides via radical-based chemistry. Although long known that allosteric regulation of RNR activity is vital for cell health, the molecular basis of this regulation has been enigmatic, largely due to a lack of structural information about how the catalytic subunit (?2) and the radical-generation subunit (?2) interact. Here we present the first structure of a complex between ?2 and ?2 subunits for the prototypic RNR from Escherichia coli. Using four techniques (small-angle X-ray scattering, X-ray crystallography, electron microscopy, and analytical ultracentrifugation), we describe an unprecedented ?4?4 ring-like structure in the presence of the negative activity effector dATP and provide structural support for an active ?2?2 configuration. We demonstrate that, under physiological conditions, E. coli RNR exists as a mixture of transient ?2?2 and ?4?4 species whose distributions are modulated by allosteric effectors. We further show that this interconversion between ?2?2 and ?4?4 entails dramatic subunit rearrangements, providing a stunning molecular explanation for the allosteric regulation of RNR activity in E. coli. PMID:22160671

  2. Dissecting the Escherichia coli periplasmic chaperone network using differential proteomics

    PubMed Central

    Vertommen, Didier; Silhavy, Thomas J.; Collet, Jean-Francois

    2013-01-01

    ?-barrel proteins, or outer membrane proteins (OMPs), perform many essential functions in Gram-negative bacteria, but questions remain about the mechanism by which they are assembled into the outer membrane (OM). In Escherichia coli, ?-barrels are escorted across the periplasm by chaperones, most notably SurA and Skp. However, the contributions of these two chaperones to the assembly of the OM proteome remained unclear. We used differential proteomics to determine how the elimination of Skp and SurA affects the assembly of many OMPs. We have shown that removal of Skp has no impact on the levels of the 63 identified OM proteins. However, depletion of SurA in the skp strain has a marked impact on the OM proteome, diminishing the levels of almost all ?-barrel proteins. Our results are consistent with a model in which SurA plays a primary chaperone role in E. coli. Furthermore, they suggest that while no OMPs prefer the Skp chaperone pathway in wild-type cells, most can use Skp efficiently when SurA is absent. Our data, which provide a unique glimpse into the protein content of the non-viable surA skp mutant, clarify the roles of the periplasmic chaperones in E. coli. PMID:22589188

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

    PubMed Central

    Gonzalez, Tammy; Gaultney, Robert A.; Floden, Angela M.; Brissette, Catherine A.

    2015-01-01

    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 lysinses in the surface-exposed region of Lpp would facilitate binding to the host zymogen plasminogen (Plg), a protease commandeered by a number of clinically important bacteria. Recombinant Lpp was synthesized and the binding of Lpp to Plg, the effect of various inhibitors on this binding, and the effects of various mutations of Lpp on Lpp–Plg interactions were examined. Additionally, the ability of Lpp-bound Plg to be converted to active plasmin was analyzed. We determined that Lpp binds Plg 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 Plg bound by Lpp can be converted to active plasmin. While the consequences of Lpp binding Plg 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. PMID:26500634

  4. Temperature Control of Phospholipid Biosynthesis in Escherichia coli

    PubMed Central

    Sinensky, Michael

    1971-01-01

    The higher the growth temperature of Escherichia coli cultures the greater is the proportion of saturated fatty acids in the bacterial phospholipids. When fatty acids are exogenously supplied to E. coli, higher growth temperatures will likewise increase the relative incorporation of saturated fatty acids into phospholipids. One of the steps in the utilization of fatty acids for phospholipid biosynthesis is, therefore, temperature-controlled. The temperature effect observed in vivo with mixtures of 3H-oleate and 14C-palmitate is demonstrable in vitro by using mixtures of the coenzyme A derivative of these fatty acids for the acylation of ?-glycerol phosphate to lysophosphatidic and phosphatidic acids. In E. coli extracts, the relative rates of transacylation of palmityl and oleyl coenzyme A vary as a function of incubation temperature in a manner which mimics the temperature control observed in vivo. The phosphatidic acid synthesized in vitro shows a striking enrichment of oleate at the ? position analogous to the positional specificity observed in phospholipids synthesized in vivo. PMID:4324806

  5. Microaerobic Conversion of Glycerol to Ethanol in Escherichia coli

    PubMed Central

    Wong, Matthew S.; Li, Mai; Black, Ryan W.; Le, Thao Q.; Puthli, Sharon; Campbell, Paul

    2014-01-01

    Glycerol has become a desirable feedstock for the production of fuels and chemicals due to its availability and low price, but many barriers to commercialization remain. Previous investigators have made significant improvements in the yield of ethanol from glycerol. We have developed a fermentation process for the efficient microaerobic conversion of glycerol to ethanol by Escherichia coli that presents solutions to several other barriers to commercialization: rate, titer, specific productivity, use of inducers, use of antibiotics, and safety. To increase the rate, titer, and specific productivity to commercially relevant levels, we constructed a plasmid that overexpressed glycerol uptake genes dhaKLM, gldA, and glpK, as well as the ethanol pathway gene adhE. To eliminate the cost of inducers and antibiotics from the fermentation, we used the adhE and icd promoters from E. coli in our plasmid, and we implemented glycerol addiction to retain the plasmid. To address the safety issue of off-gas flammability, we optimized the fermentation process with reduced-oxygen sparge gas to ensure that the off-gas remained nonflammable. These advances represent significant progress toward the commercialization of an E. coli-based glycerol-to-ethanol process. PMID:24584248

  6. Diet, Escherichia coli O157:H7, and cattle: A review after 10 years

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli are commensal bacteria that can account for up to 1% of the bacterial population of the gut. Ruminant animals are reservoirs of the pathogenic bacteria E. coli O157:H7, and approximately 30% of feedlot cattle shed E. coli O157:H7. Feedlot and high-producing dairy cattle are fed hi...

  7. Diet, fecal microbiome and Escherichia coli O157:H7 shedding in beef Cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga-toxigenic Escherichia coli, such as E. coli O157:H7, are foodborne zoonotic pathogens that can cause severe illness and death in humans. The gastrointestinal tract of ruminant animals has been identified as a primary habitat for E. coli O157:H7, and in cattle the terminal gastrointestinal tra...

  8. Persistence of Escherichia coli O157 and non-O157 strains in agricultural soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin producing Escherichia coli O157 and non-O157 serogroups are known to cause serious diseases in human. However, research on the persistence of E. coli non-O157 serogroups in preharvest environment is limited. In the current study, we compared the survival behavior of E. coli O157 to that ...

  9. Comparison of whole genome sequences from human and non-human Escherichia coli O26 strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli (STEC) O26 is the second leading E. coli serogroup responsible for human illness outbreaks behind E. coli O157:H7. Recent outbreaks have been linked to emerging pathogenic O26:H11 strains harboring stx2 only. Cattle have been recognized as an important reserv...

  10. Mouse in vivo neutralization of Escherichia coli Shiga toxin 2 with monoclonal antibodies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli (E. coli) food contaminations pose serious health and food safety concerns, and have been the subject of massive food recalls. Shiga toxin 2 (Stx2)-producing E. coli has been identified as the major cause of hemorrhagic colitis and hemolytic uremic syndrome (HUS), the most severe di...

  11. Complete Genome Sequences of Escherichia coli Strains 1303 and ECC-1470 Isolated from Bovine Mastitis

    PubMed Central

    Leimbach, Andreas; Poehlein, Anja; Witten, Anika; Scheutz, Flemming; Schukken, Ynte; Daniel, Rolf

    2015-01-01

    Escherichia coli is the leading causative agent of acute bovine mastitis. Here, we report the complete genome sequence of E. coli O70:H32 strain 1303, isolated from an acute case of bovine mastitis, and E. coli Ont:Hnt strain ECC-1470, isolated from a persistent infection. PMID:25814601

  12. A homolog of an Escherichia coli phosphate-binding protein gene from Xanthomonas oryzae pv. oryzae

    NASA Technical Reports Server (NTRS)

    Hopkins, C. M.; White, F. F.; Heaton, L. A.; Guikema, J. A.; Leach, J. E.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    A Xanthomonas oryzae pv. oryzae gene with sequence similarity to an Escherichia coli phosphate-binding protein gene (phoS) produces a periplasmic protein of apparent M(r) 35,000 when expressed in E. coli. Amino terminal sequencing revealed that a signal peptide is removed during transport to the periplasm in E. coli.

  13. Detection of Escherichia Coli O157:H7 in Fecal Samples in Meat Goats

    ERIC Educational Resources Information Center

    Mobley, Ray; Madden, Uford; Brooks-Walter, Alexis

    2004-01-01

    Studies have reported the isolation of Escherichia coli (E. coli)O157:H7 from pork, lamb and poultry products, and from other animals including deer, horses, dogs, birds and humans. There is limited or no information on the presence of the organism in goats. The objectives of this study were to determine if E. coli O157:H7 was naturally occurring…

  14. Investigation of an Escherichia coli 0157:H7 Outbreak Associated with Dole Pre-Packaged Spinach

    E-print Network

    Investigation of an Escherichia coli 0157:H7 Outbreak Associated with Dole Pre-Packaged Spinach Attachment 11 CDC Addendum Report, "Irrigation Water Issues Potentially Related to 2006 E. coli 0157:H7 in Spinach Outbreak" #12;Irrigation Water Issues Potentially Related to 2006 E. coli 0157:H7 in Spinach

  15. Proteomic differences between Escherichia coli strains that cause transient versus persistent intramammary infections [abstract

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli is a leading cause of bacterial mastitis in dairy cattle. Typically this infection is transient in nature and lasts 2-3 days. However, in a minority of cases, E. coli can cause a persistent intramammary infection. The mechanisms that enable certain strains of E. coli to cause a p...

  16. RESEARCH ARTICLE Open Access Hierarchy of non-glucose sugars in Escherichia coli

    E-print Network

    RESEARCH ARTICLE Open Access Hierarchy of non-glucose sugars in Escherichia coli Guy Aidelberg in systems biology. To address this, we study the decisions made by E. coli on which genes to express when presented with two different sugars. It is well-known that glucose, E. coli's preferred carbon source

  17. SENSITIVE DETECTION OF ESCHERICHIA COLI 0157:H7 BY THE USE OF IMMUNOMAGNETIC AND FLUORESCENT BEADS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To meet the needs of food safety, a rapid and sensitive fluorescent sandwich method for the detection of Escherichia coli O157:H7 in ground beef was developed. Immunomagnetic beads (IMBs) coated with anti-E. coli O157:H7 antibodies were used to capture and concentrate E. coli O157:H7 present in gro...

  18. Dietary interactions and interventions affecting Escherichia coli 0157 colonization and shedding in cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli O157 is an important foodborne pathogen affecting human health and the beef cattle industry. Contamination of carcasses at slaughter is correlated to the prevalence of E. coli O157 in cattle feces. Many associations have been made between dietary factors and E. coli O157 prevalenc...

  19. A glimpse of Escherichia coli O157:H7 survival in soils from eastern China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli O157:H7 (E. coli O157:H7) is an important food-borne pathogen, which continues to be a major public health concern worldwide. It is known that E. coli O157:H7 survive in soil environment might result in the contamination of fresh produce or water source. To investigate how the soils...

  20. Quantification of persistence of Escherichia coli O157:H7 in contrasting soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Persistence of Escherichia coli (E. coli) O157:H7 in the environment is a major concern to vegetable and fruit growers where farms and livestock production are in close proximity. The objectives were to determine the effects of preplant fumigation treatment on the survival of E. coli O157:H7 in two ...

  1. Mechanisms of antibiotic resistance to enrofloxacin in uropathogenic Escherichia coli in dog

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  2. Resistance of various shiga toxin-producing Escherichia coli to electrolyzed oxidizing water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The resistance of thirty two strains of Escherichia coli O157:H7 and six major serotypes of non-O157 Shiga toxin- producing E. coli (STEC) plus E. coli O104 was tested against Electrolyzed oxidizing (EO) water using two different methods; modified AOAC 955.16 sequential inoculation method and minim...

  3. SURVIVAL OF ESCHERICHIA COLI 0157:H7 IN DAIRY CATTLE FEED WATER

    EPA Science Inventory

    Cattle feed waters from two dairy farms were used in a study to determine the survival characteristics of the bacterial pathogen Escherichia coli )157:H7 and wild-type E. coli. The E. coli 0157:H7 inoculum consisted of a consortium of isolates obtained from dairy cattle. Fresh ma...

  4. Escherichia coli O157:H7, diet, and fecal microbiome in beef cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga-toxigenic Escherichia coli, such as E. coli O157:H7, are foodborne zoonotic pathogens that can cause severe illness and death in humans. The gastrointestinal tract of ruminant animals has been identified as a primary habitat for E. coli O157:H7, and in cattle the terminal gastrointestinal tra...

  5. SURVIVAL OF ESCHERICHIA COLI O157:H7 IN SOIL AND ON LETTUCE AFTER FUMIGATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long term persistence of Escherichia coli (E. coli) O157:H7 in soil and in the rhizosphere of many crops is relatively unknown. Many groups have voiced concerns about the safety of land application of manure and the potential for food and water contamination by E. coli O157:H7 from agricultural runo...

  6. Validating tyrosinase homologue melA as a photoacoustic reporter gene for imaging Escherichia coli

    NASA Astrophysics Data System (ADS)

    Paproski, Robert J.; Li, Yan; Barber, Quinn; Lewis, John D.; Campbell, Robert E.; Zemp, Roger

    2015-10-01

    To understand the pathogenic processes for infectious bacteria, appropriate research tools are required for replicating and characterizing infections. Fluorescence and bioluminescence imaging have primarily been used to image infections in animal models, but optical scattering in tissue significantly limits imaging depth and resolution. Photoacoustic imaging, which has improved depth-to-resolution ratio compared to conventional optical imaging, could be useful for visualizing melA-expressing bacteria since melA is a bacterial tyrosinase homologue which produces melanin. Escherichia coli-expressing melA was visibly dark in liquid culture. When melA-expressing bacteria in tubes were imaged with a VisualSonics Vevo LAZR system, the signal-to-noise ratio of a 9× dilution sample was 55, suggesting that ˜20 bacteria cells could be detected with our system. Multispectral (680, 700, 750, 800, 850, and 900 nm) analysis of the photoacoustic signal allowed unmixing of melA-expressing bacteria from blood. To compare photoacoustic reporter gene melA (using Vevo system) with luminescent and fluorescent reporter gene Nano-lantern (using Bruker Xtreme In-Vivo system), tubes of bacteria expressing melA or Nano-lantern were submerged 10 mm in 1% Intralipid, spaced between <1 and 20 mm apart from each other, and imaged with the appropriate imaging modality. Photoacoustic imaging could resolve the two tubes of melA-expressing bacteria even when the tubes were less than 1 mm from each other, while bioluminescence and fluorescence imaging could not resolve the two tubes of Nano-lantern-expressing bacteria even when the tubes were spaced 10 mm from each other. After injecting 100-?L of melA-expressing bacteria in the back flank of a chicken embryo, photoacoustic imaging allowed visualization of melA-expressing bacteria up to 10-mm deep into the embryo. Photoacoustic signal from melA could also be separated from deoxy- and oxy-hemoglobin signal observed within the embryo and chorioallantoic membrane. Our results suggest that melA is a useful photoacoustic reporter gene for visualizing bacteria, and further work incorporating photoacoustic reporters into infectious bacterial strains is warranted.

  7. Inactivation kinetics of Escherichia coli by pulsed electron beam.

    PubMed

    Chalise, P R; Hotta, E; Matak, K E; Jaczynski, J

    2007-09-01

    A novel and compact low-energy (keV) high-power pulsed electron beam (e-beam) that utilizes a secondary emission electron gun (SEEG) was designed and constructed. Escherichia coli JM 109 at a concentration of 10(6) CFU/mL was spread-plated on Luria-Bertani (LB) medium and subjected to the SEEG e-beam. The e-beam was administered as 1 or 5 pulses. The duration of a single pulse was constant at 5 micros, e-beam current density was constant at 25 mA/cm2, and e-beam energy varied between 60 and 82.5 keV. Following treatment with the SEEG e-beam, survivors of the irradiated E. coli samples were enumerated by a standard 10-fold dilution and spread-plated. The survivor curves were plotted on logarithmic scale as a function of e-beam dose. The D10-values were calculated as a negative reciprocal of the slope of the survivor curves. The D10-values for E. coli inactivated with 1- and 5-pulse SEEG e-beam were 0.0026 and 0.0217 Gy, respectively. These D10-values were considerably lower than published D10-values for E. coli inactivated with conventional high-energy continuous e-beam, likely due to shorter exposure time (t), greater current density (J), and a pulse mode of the SEEG e-beam. The SEEG e-beam showed promising results for microbial inactivation in a nonthermal manner; however, due to low energy of the SEEG e-beam, current applications are limited to surface decontamination. The SEEG e-beam may be an efficient processing step for surface inactivation of food-borne pathogens on ready-to-eat products, including fresh and leafy vegetables. PMID:17995653

  8. Specific electromagnetic effects of microwave radiation on Escherichia coli.

    PubMed

    Shamis, Yury; Taube, Alex; Mitik-Dineva, Natasa; Croft, Rodney; Crawford, Russell J; Ivanova, Elena P

    2011-05-01

    The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m(3), and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control, E. coli cells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that the E. coli cells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposing E. coli cells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane. PMID:21378041

  9. SILAC-based comparative analysis of pathogenic Escherichia coli secretomes.

    PubMed

    Boysen, Anders; Borch, Jonas; Krogh, Thøger Jensen; Hjernø, Karin; Møller-Jensen, Jakob

    2015-09-01

    Comparative studies of pathogenic bacteria and their non-pathogenic counterparts has led to the discovery of important virulence factors thereby generating insight into mechanisms of pathogenesis. Protein-based antigens for vaccine development are primarily selected among unique virulence-related factors produced by the pathogen of interest. However, recent work indicates that proteins that are not unique to the pathogen but instead selectively expressed compared to its non-pathogenic counterpart could also be vaccine candidates or targets for drug development. Modern methods in quantitative proteome analysis have the potential to discover both classes of proteins and hence form an important tool for discovering therapeutic targets. Adherent-invasive Escherichia coli (AIEC) and Enterotoxigenic E. coli (ETEC) are pathogenic variants of E. coli which cause intestinal disease in humans. AIEC is associated with Crohn's disease (CD), a chronic inflammatory condition of the gastrointestinal tract whereas ETEC is the major cause of human diarrhea which affects hundreds of millions annually. In spite of the disease burden associated with these pathogens, effective vaccines conferring long-term protection are still needed. In order to identify proteins with therapeutic potential, we have used mass spectrometry-based Stable Isotope Labeling with Amino acids in Cell culture (SILAC) quantitative proteomics method which allows us to compare the proteomes of pathogenic strains to commensal E. coli. In this study, we grew the pathogenic strains ETEC H10407, AIEC LF82 and the non-pathogenic reference strain E. coli K-12 MG1655 in parallel and used SILAC to compare protein levels in OMVs and culture supernatant. We have identified well-known virulence factors from both AIEC and ETEC, thus validating our experimental approach. In addition we find proteins that are not unique to the pathogenic strains but expressed at levels different from the commensal strain, including the colonization factor YghJ and the surface adhesin antigen 43, which is involved in pathogenesis of other Gram-negative bacteria. The described method provides a framework for further understanding E. coli pathogenesis but can also be applied to interrogate relative protein expression levels of other pathogens that have non-pathogenic counterparts thereby facilitating the discovery of new vaccine targets. PMID:26143086

  10. Antibacterial Mode of Action of Cinnamomum verum Bark Essential Oil, Alone and in Combination with Piperacillin, Against a Multi-Drug-Resistant Escherichia coli Strain.

    PubMed

    Yap, Polly Soo Xi; Krishnan, Thiba; Chan, Kok-Gan; Lim, Swee Hua Erin

    2015-08-01

    This study aimed to investigate the mechanism of action of the cinnamon bark essential oil (CB), when used singly and also in combination with piperacillin, for its antimicrobial and synergistic activity against beta-lactamase TEM-1 plasmid-conferred Escherichia coli J53 R1. Viable count of this combination showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis on the stability of treated cultures for cell membrane permeability by CB when tested against sodium dodecyl sulfate revealed that the bacterial cell membrane was disrupted by the essential oils. Scanning electron microscopy observation and bacterial surface charge measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed reduction, indicating the possibility of the presence of quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%), and eugenol (6.57%) were the major components in the essential oil. From this study, CB has the potential to reverse E. coli J53 R1 resistance to piperacillin through two pathways; modification in the permeability of the outer membrane or bacterial QS inhibition. PMID:25381741

  11. Development of a latex agglutination test for rapid identification of Escherichia coli.

    PubMed

    Huang, Y H; Chang, H C; Chang, T C

    2001-02-01

    Escherichia coli, one of the most important human pathogens, is usually identified by a battery of biochemical tests that require overnight incubation. For rapid identification of Escherichia coli, a latex agglutination test (LAT) was developed. Rabbits were immunized with cell-surface antigens extracted from Escherichia coli CCRC 15481 with 4 M urea, and the affinity-purified antibodies were used to coat latex particles for the identification of the bacterium. The following gram-negative bacteria were used to evaluate the LAT: Escherichia coli (n = 761), Enterobacteriaceae other than Escherichia coli (n = 632), Aeromonas spp. (n = 21), Pseudomonas spp. (n = 75), Vibrio spp. (n = 18), and other bacteria (n = 64). The LAT had a sensitivity and specificity of 99.2 and 93.3%, respectively. If the LAT was used in conjunction with the tests of indole production or lactose fermentation, the specificity values for the identification of Escherichia coli increased from 93.3 to 98.8 and 98.7%, respectively. If the LAT, indole production, and lactose fermentation were used together for the identification of Escherichia coli, the sensitivity and specificity were 94 and 99.7%, respectively. Lactose fermentation could be detected by observing the colonies grown on selective media (e.g. MacConkey agar), and indole production could be analyzed simply by the spot indole test. Strains producing negative reactions (i.e. not identified as Escherichia coli) should be processed by the conventional procedures for identification. The present protocol integrating the LAT, indole production, and lactose fermentation for the identification of Escherichia coli offers considerable savings of time, manpower, and cost. PMID:11305479

  12. High-resolution structure of the Escherichia coli ribosome

    PubMed Central

    Noeske, Jonas; Wasserman, Michael R.; Terry, Daniel S.; Altman, Roger B.; Blanchard, Scott C.; Cate, Jamie H. D.

    2015-01-01

    Protein synthesis by the ribosome is highly dependent on the ionic conditions in the cellular environment, but the roles of ribosome solvation remain poorly understood. Moreover, the function of modifications to ribosomal RNA and ribosomal proteins are unclear. Here we present the structure of the Escherichia coli 70S ribosome to 2.4 Å resolution. The structure reveals details of the ribosomal subunit interface that are conserved in all domains of life, and suggest how solvation contributes to ribosome integrity and function. The structure also suggests how the conformation of ribosomal protein uS12 likely impacts its contribution to messenger RNA decoding. This structure helps to explain the phylogenetic conservation of key elements of the ribosome, including posttranscriptional and posttranslational modifications and should serve as a basis for future antibiotic development. PMID:25775265

  13. Structure of the Cyclomodulin Cif from Pathogenic Escherichia coli

    SciTech Connect

    Hsu, Y.; Jubelin, G; Taieb, F; Nougayrède, J; Oswald, E; Stebbins, C

    2008-01-01

    Bacterial pathogens have evolved a sophisticated arsenal of virulence factors to modulate host cell biology. Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) use a type III protein secretion system (T3SS) to inject microbial proteins into host cells. The T3SS effector cycle inhibiting factor (Cif) produced by EPEC and EHEC is able to block host eukaryotic cell-cycle progression. We present here a crystal structure of Cif, revealing it to be a divergent member of the superfamily of enzymes including cysteine proteases and acetyltransferases that share a common catalytic triad. Mutation of these conserved active site residues abolishes the ability of Cif to block cell-cycle progression. Finally, we demonstrate that irreversible cysteine protease inhibitors do not abolish the Cif cytopathic effect, suggesting that another enzymatic activity may underlie the biological activity of this virulence factor.

  14. Phenotypic bistability in Escherichia coli's central carbon metabolism

    PubMed Central

    Kotte, Oliver; Volkmer, Benjamin; Radzikowski, Jakub L; Heinemann, Matthias

    2014-01-01

    Fluctuations in intracellular molecule abundance can lead to distinct, coexisting phenotypes in isogenic populations. Although metabolism continuously adapts to unpredictable environmental changes, and although bistability was found in certain substrate-uptake pathways, central carbon metabolism is thought to operate deterministically. Here, we combine experiment and theory to demonstrate that a clonal Escherichia coli population splits into two stochastically generated phenotypic subpopulations after glucose-gluconeogenic substrate shifts. Most cells refrain from growth, entering a dormant persister state that manifests as a lag phase in the population growth curve. The subpopulation-generating mechanism resides at the metabolic core, overarches the metabolic and transcriptional networks, and only allows the growth of cells initially achieving sufficiently high gluconeogenic flux. Thus, central metabolism does not ensure the gluconeogenic growth of individual cells, but uses a population-level adaptation resulting in responsive diversification upon nutrient changes. PMID:24987115

  15. Sensitivity of Escherichia coli to cephaloridine at different growth rates.

    PubMed Central

    Mathys, E; Van Gool, A

    1979-01-01

    Steady-state populations of Escherichia coli B/r were treated with cephaloridine at minimal inhibitory concentrations. The antibiotic sensitivity of the cells and the localization of spheroplast emergence along the cell surface were examined as a function of cell length and growth rate. In fast-growing populations (greater than 1 division per h) the sites of cephaloridine interaction occurred preferentially at the cell pole in the smaller cells and at the cell center in dividing cells. At decreasing growth rates the cells became more resistant to cephaloridine, and a gradual shift from the cell pole toward the cell center was observed for the sphere position. A similar growth rate-dependent change in localization was found for sucrose-induced plasmolysis vacuoles. PMID:35527

  16. Plasmolysis during the division cycle of Escherichia coli.

    PubMed Central

    Olijhoek, A J; Van 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 behaved as independent cellular units with respect to plasmolysis. The results indicate that compressibility of the protoplast (given a certain plasmolysis space) is inversely related to cell size. That a dividing cell does not react as one osmotic compartment to osmotic stress may suggest that cell size-dependent strength of the cell membrane-cell wall association, rather than variation in turgor, plays a role during the cell division cycle. Images PMID:6749814

  17. Nucleoside triphosphate pools in synchronous cultures of Escherichia coli.

    PubMed

    Huzyk, L; Clark, D J

    1971-10-01

    Endogenous nucleoside triphosphate pools in synchronized cultures of Escherichia coli B/r/1 oscillate as a function of age. Purine nucleoside triphosphates show a gradual 50% increase from zero age to the time of subsequent division, immediately prior to division. In contrast, pyrimidine nucleoside triphosphates undergo a dramatic change of about 50% in the first half of the generation at a time coincident with the termination of a round of deoxyribonucleic acid replication. A 50 to 70% increase starts at the initiation of the next round of deoxyribonucleic acid replication and continues until cell division, in parallel with the purine nucleotides. The fluctuation of pyrimidines between zero age and the middle of the division cycle suggests a functional relationship for pyrimidine metabolism and the regulation of cell division. PMID:4941576

  18. Overflow metabolism in Escherichia coli results from efficient proteome allocation.

    PubMed

    Basan, Markus; Hui, Sheng; Okano, Hiroyuki; Zhang, Zhongge; Shen, Yang; Williamson, James R; Hwa, Terence

    2015-12-01

    Overflow metabolism refers to the seemingly wasteful strategy in which cells use fermentation instead of the more efficient respiration to generate energy, despite the availability of oxygen. Known as the Warburg effect in the context of cancer growth, this phenomenon occurs ubiquitously for fast-growing cells, including bacteria, fungi and mammalian cells, but its origin has remained unclear despite decades of research. Here we study metabolic overflow in Escherichia coli, and show that it is a global physiological response used to cope with changing proteomic demands of energy biogenesis and biomass synthesis under different growth conditions. A simple model of proteomic resource allocation can quantitatively account for all of the observed behaviours, and accurately predict responses to new perturbations. The key hypothesis of the model, that the proteome cost of energy biogenesis by respiration exceeds that by fermentation, is quantitatively confirmed by direct measurement of protein abundances via quantitative mass spectrometry. PMID:26632588

  19. Programming a Pavlovian-like conditioning circuit in Escherichia coli

    NASA Astrophysics Data System (ADS)

    Zhang, Haoqian; Lin, Min; Shi, Handuo; Ji, Weiyue; Huang, Longwen; Zhang, Xiaomeng; Shen, Shan; Gao, Rencheng; Wu, Shuke; Tian, Chengzhe; Yang, Zhenglin; Zhang, Guosheng; He, Siheng; Wang, Hao; Saw, Tiffany; Chen, Yiwei; Ouyang, Qi

    2014-01-01

    Synthetic genetic circuits are programmed in living cells to perform predetermined cellular functions. However, designing higher-order genetic circuits for sophisticated cellular activities remains a substantial challenge. Here we program a genetic circuit that executes Pavlovian-like conditioning, an archetypical sequential-logic function, in Escherichia coli. The circuit design is first specified by the subfunctions that are necessary for the single simultaneous conditioning, and is further genetically implemented using four function modules. During this process, quantitative analysis is applied to the optimization of the modules and fine-tuning of the interconnections. Analogous to classical Pavlovian conditioning, the resultant circuit enables the cells to respond to a certain stimulus only after a conditioning process. We show that, although the conditioning is digital in single cells, a dynamically progressive conditioning process emerges at the population level. This circuit, together with its rational design strategy, is a key step towards the implementation of more sophisticated cellular computing.

  20. Escherichia coli activity characterization using a laser dynamic speckle technique

    E-print Network

    Ramírez-Miquet, Evelio E; Contreras-Alarcón, Orestes R

    2012-01-01

    The results of applying a laser dynamic speckle technique to characterize bacterial activity are presented. The speckle activity was detected in two-compartment Petri dishes. One compartment was inoculated and the other one was left as a control blank. The speckled images were processed by the recently reported temporal difference method. Three inoculums of 0.3, 0.5, and 0.7 McFarland units of cell concentration were tested; each inoculum was tested twice for a total of six experiments. The dependences on time of the mean activity, the standard deviation of activity and other descriptors of the speckle pattern evolution were calculated for both the inoculated compartment and the blank. In conclusion the proposed dynamic speckle technique allows characterizing the activity of Escherichia coli bacteria in solid medium.

  1. Dissection and engineering of the Escherichia coli formate hydrogenlyase complex.

    PubMed

    McDowall, Jennifer S; Hjersing, M Charlotte; Palmer, Tracy; Sargent, Frank

    2015-10-01

    The Escherichia coli formate hydrogenlyase (FHL) complex is produced under fermentative conditions and couples formate oxidation to hydrogen production. In this work, the architecture of FHL has been probed by analysing affinity-tagged complexes from various genetic backgrounds. In a successful attempt to stabilize the complex, a strain encoding a fusion between FdhF and HycB has been engineered and characterised. Finally, site-directed mutagenesis of the hycG gene was performed, which is predicted to encode a hydrogenase subunit important for regulating sensitivity to oxygen. This work helps to define the core components of FHL and provides solutions to improving the stability of the enzyme. PMID:26358294

  2. Theoretical Prediction of Disrupted Min Oscillation in Flattened Escherichia coli

    PubMed Central

    Schulte, Jeff B.; Zeto, Rene W.; Roundy, David

    2015-01-01

    The dynamics of the Min-protein system help Escherichia coli regulate the process of cell division by identifying the center of the cell. While this system exhibits robust bipolar oscillations in wild-type cell shapes, recent experiments have shown that when the cells are mechanically deformed into wide, flattened out, irregular shapes, the spatial regularity of these oscillations breaks down. We employ widely used stochastic and deterministic models of the Min system to simulate cells with flattened shapes. The deterministic model predicts strong bipolar oscillations, in contradiction with the experimentally observed behavior, while the stochastic model, which is based on the same reaction-diffusion equations, predicts more spatially irregular oscillations. We further report simulations of flattened but more symmetric shapes, which suggest that the flattening and lateral expansion may contribute as much to the irregular oscillation behavior as the asymmetry of the cell shapes. PMID:26457805

  3. Effect of Phosphorus on Survival of Escherichia coli in Drinking Water Biofilms?

    PubMed Central

    Juhna, Talis; Birzniece, Dagne; Rubulis, Janis

    2007-01-01

    The effect of phosphorus addition on survival of Escherichia coli in an experimental drinking water distribution system was investigated. Higher phosphorus concentrations prolonged the survival of culturable E. coli in water and biofilms. Although phosphorus addition did not affect viable but not culturable (VBNC) E. coli in biofilms, these structures could act as a reservoir of VBNC forms of E. coli in drinking water distribution systems. PMID:17416695

  4. Structure of CFA/I fimbriae from enterotoxigenic Escherichia coli

    SciTech Connect

    Li, Yong-Fu; Poole, Steven; Nishio, Kazuya; Jang, Ken; Rasulova, Fatima; McVeigh, Annette; Savarino, Stephen J.; Xia, Di; Bullitt, Esther

    2009-10-21

    Adhesion pili (fimbriae) play a critical role in initiating the events that lead to intestinal colonization and diarrheal disease by enterotoxigenic Escherichia coli (ETEC), an E. coli pathotype that inflicts an enormous global disease burden. We elucidate atomic structures of an ETEC major pilin subunit, CfaB, from colonization factor antigen I (CFA/I) fimbriae. These data are used to construct models for 2 morphological forms of CFA/I fimbriae that are both observed in vivo: the helical filament into which it is typically assembled, and an extended, unwound conformation. Modeling and corroborative mutational data indicate that proline isomerization is involved in the conversion between these helical and extended forms. Our findings affirm the strong structural similarities seen between class 5 fimbriae (from bacteria primarily causing gastrointestinal disease) and class 1 pili (from bacteria that cause urinary, respiratory, and other infections) in the absence of significant primary sequence similarity. They also suggest that morphological and biochemical differences between fimbrial types, regardless of class, provide structural specialization that facilitates survival of each bacterial pathotype in its preferred host microenvironment. Last, we present structural evidence for bacterial use of antigenic variation to evade host immune responses, in that residues occupying the predicted surface-exposed face of CfaB and related class 5 pilins show much higher genetic sequence variability than the remainder of the pilin protein.

  5. High prevalence iron receptor genes of avian pathogenic Escherichia coli.

    PubMed

    Ons, Ellen; Bleyen, Nele; Tuntufye, Huruma Nelwike; Vandemaele, Fréderic; Goddeeris, Bruno Maria

    2007-10-01

    Avian pathogenic Escherichia coli are known to cause significant losses in the poultry industry worldwide. Although prophylactic measures based on vaccination are advisable, until now no full heterologous protection against colibacillosis has been achieved. Since iron is an essential nutrient to these bacteria, the aim of this study was to investigate the prevalence of 12 outer-membrane iron receptor genes in 239 pathogenic strains isolated from clinical cases of colibacillosis in chickens. Five multiplex polymerase chain reactions were developed as a tool for efficient screening. Among the 239 avian E. coli isolates, 100% were positive for fhuE and fepA, 96.2% for fiu, 92.9% for cir, 92.5% for iroN, 87.4% for iutA, 63.2% for fecA, 53.1% for fyuA, 46.9% for fhuA, 45.6% for ireA, 41.8% for chuA and 4.6% for iha. PMID:17899466

  6. Escherichia Coli Xona (Sbcb) Mutants Enhance Illegitimate Recombination

    PubMed Central

    Allgood, N. D.; Silhavy, T. J.

    1991-01-01

    Mutations of Escherichia coli K-12 were isolated that increase the frequency of deletion formation. Three of these mutations map to the gene sbcB at 43.5 min on the E. coli chromosome. Two types of mutations at sbcB have been previously defined: sbcB-type that suppress both the UV sensitivity and recombination deficiency of recBC mutants, and xonA-type that suppress only the UV sensitivity. Both types are defective for production of exonuclease I activity. The mutations isolated here were similar to xonA alleles of sbcB because they suppressed the UV sensitivity of recBC mutants but did not restore recombination proficiency. Indeed, two previously characterized xonA alleles were shown to increase the frequency of deletion formation, although an sbcB allele did not. This result demonstrates that loss of exonuclease I activity is not sufficient to confer a high deletion phenotype, rather, the product of the sbcB gene possesses some other function that is important for deletion formation. Because deletion formation in this system is recA independent and does not require extensive DNA homology, these mutations affect a pathway of illegitimate recombination. PMID:2029968

  7. Mutants of Escherichia coli deficient in the fermentative lactate dehydrogenase

    SciTech Connect

    Mat-Jan, F.; Alam, K.Y.; Clark, D.P. )

    1989-01-01

    Mutants of Escherichia coli deficient in the fermentative NAD-linked lactate dehydrogenase (ldh) have been isolated. These mutants showed no growth defects under anaerobic conditions unless present together with a defect in pyruvate formate lyase (pfl). Double mutants (pfl ldh) were unable to grow anaerobically on glucose or other sugars even when supplemented with acetate, whereas pfl mutants can do so. The ldh mutation was found to map at 30.5 min on the E. coli chromosome. The ldh mutant FMJ39 showed no detectable lactate dehydrogenase activity and produced no lactic acid from glucose under anaerobic conditions as estimated by in vivo nuclear magnetic resonance measurements. We also found that in wild-type strains the fermentative lactate dehydrogenase was conjointly induced by anaerobic conditions and an acidic pH. Despite previous findings that phosphate concentrations affect the proportion of lactic acid produced during fermentation, we were unable to find any intrinsic effect of phosphate on lactate dehydrogenase activity, apart from the buffering effect of this ion.

  8. Beneficial knockouts in Escherichia coli for producing hydrogen from glycerol.

    PubMed

    Tran, Kien Trung; Maeda, Toshinari; Sanchez-Torres, Viviana; Wood, Thomas K

    2015-03-01

    Glycerol is an inexpensive and abundant source for biofuel production on a large scale. Escherichia coli is a robust bacterium for producing hydrogen; however, its hydrogen productivity from glycerol is low. In this study, we conducted random transposon mutagenesis to identify uncharacterized genes whose inactivation is beneficial for hydrogen production from glycerol. Through screening, four mutant strains were found that are able to have from 1.3- to 1.6-fold higher hydrogen productivity (?mol H2/mg protein) than that of their parent strain (p?coli, AroM is predicted to be involved in the shikimate pathway, GatZ is tagatose-1,6-bisphosphate aldolase 2 which converts dihydroxyacetone phosphate to 1,6-biphosphate, and YcgR acts as a molecular brake limiting the swimming speed and ATP consumption. So far, the function of YfgI in general and in hydrogen production in particular remains unknown. PMID:25567513

  9. In vivo immobilization of D-hydantoinase in Escherichia coli.

    PubMed

    Chen, Shan-Yu; Chien, Yi-Wen; Chao, Yun-Peng

    2014-07-01

    D-P-Hydroxyphenylglycine (D-HPG) is a precursor required for the synthesis of semi-synthetic antibiotics. This unnatural amino acid can be produced by a transformation reaction mediated by D-hydantoinase (D-HDT) and d-amidohydrolase. In this study, a method was developed to integrate production and immobilization of recombinant D-HDT in vivo. This was approached by first fusion of the gene encoding D-HDT with phaP (encoding phasin) of Ralstonia eutropha H16. The fusion gene was then expressed in the Escherichia coli strain that carried a heterologous synthetic pathway for polyhydroxyalkanoate (PHA). As a result, d-HDT was found to associate with isolated PHA granules. Further characterization illustrated that D-HDT immobilized on PHA exhibited the maximum activity at pH 9 and 60°C and had a half-life of 95 h at 40°C. Moreover, PHA-bound d-HDT could be reused for 8 times with the conversion yield exceeding 90%. Overall, it illustrates the feasibility of this approach to facilitate in vivo immobilization of enzymes in heterologous E. coli strain, which may open a new avenue of enzyme application in industry. PMID:24508023

  10. Recombinational Repair of DNA Damage in Escherichia coli and Bacteriophage ?

    PubMed Central

    Kuzminov, Andrei

    1999-01-01

    Although homologous recombination and DNA repair phenomena in bacteria were initially extensively studied without regard to any relationship between the two, it is now appreciated that DNA repair and homologous recombination are related through DNA replication. In Escherichia coli, two-strand DNA damage, generated mostly during replication on a template DNA containing one-strand damage, is repaired by recombination with a homologous intact duplex, usually the sister chromosome. The two major types of two-strand DNA lesions are channeled into two distinct pathways of recombinational repair: daughter-strand gaps are closed by the RecF pathway, while disintegrated replication forks are reestablished by the RecBCD pathway. The phage ? recombination system is simpler in that its major reaction is to link two double-stranded DNA ends by using overlapping homologous sequences. The remarkable progress in understanding the mechanisms of recombinational repair in E. coli over the last decade is due to the in vitro characterization of the activities of individual recombination proteins. Putting our knowledge about recombinational repair in the broader context of DNA replication will guide future experimentation. PMID:10585965

  11. Escherichia coli genes expressed preferentially in an aquatic environment.

    PubMed

    Espinosa-Urgel, M; Kolter, R

    1998-04-01

    Enteric bacteria are frequently found in aquatic environments, where they may pose a risk to human health. Although bacterial survival and persistence in such habitats has been studied extensively, there is almost no information about bacterial adaptation to these conditions at the level of changes in gene expression. As a first exploration of this field, we have carried out a screen designed to identify Escherichia coli genes that show increased expression in an aquatic environment. The screen was performed by subtractive hybridization on a genomic library and led to the identification of several RNA species more abundant in cells inoculated in this medium than in stationary-phase cultures after growth in rich medium. The genes identified include specific tRNA operons and a gene of unknown function, gapC, with similarities to glyceraldehyde-3-phosphate dehydrogenases. E. coli K-12 strains appear to have accumulated mutations in gapC, which may impede its translation, whereas natural isolates have an intact gapC gene. Sequence comparison of gapC with related genes suggests its acquisition by horizontal gene transfer from gram-positive bacteria. PMID:9622357

  12. Composite analysis for Escherichia coli at coastal beaches

    USGS Publications Warehouse

    Bertke, E.E.

    2007-01-01

    At some coastal beaches, concentrations of fecal-indicator bacteria can differ substantially between multiple points at the same beach at the same time. Because of this spatial variability, the recreational water quality at beaches is sometimes determined by stratifying a beach into several areas and collecting a sample from each area to analyze for the concentration of fecal-indicator bacteria. The average concentration of bacteria from those points is often used to compare to the recreational standard for advisory postings. Alternatively, if funds are limited, a single sample is collected to represent the beach. Compositing the samples collected from each section of the beach may yield equally accurate data as averaging concentrations from multiple points, at a reduced cost. In the study described herein, water samples were collected at multiple points from three Lake Erie beaches and analyzed for Escherichia coli on modified mTEC agar (EPA Method 1603). From the multiple-point samples, a composite sample (n = 116) was formed at each beach by combining equal aliquots of well-mixed water from each point. Results from this study indicate that E. coli concentrations from the arithmetic average of multiple-point samples and from composited samples are not significantly different (t = 1.59, p = 0.1139) and yield similar measures of recreational water quality; additionally, composite samples could result in a significant cost savings.

  13. Structure and Biochemical Activities of Escherichia coli MgsA

    SciTech Connect

    Page, Asher N.; George, Nicholas P.; Marceau, Aimee H.; Cox, Michael M.; Keck, James L.

    2012-02-27

    Bacterial 'maintenance of genome stability protein A' (MgsA) and related eukaryotic enzymes play important roles in cellular responses to stalled DNA replication processes. Sequence information identifies MgsA enzymes as members of the clamp loader clade of AAA{sup +} proteins, but structural information defining the family has been limited. Here, the x-ray crystal structure of Escherichia coli MgsA is described, revealing a homotetrameric arrangement for the protein that distinguishes it from other clamp loader clade AAA{sup +} proteins. Each MgsA protomer is composed of three elements as follows: ATP-binding and helical lid domains (conserved among AAA{sup +} proteins) and a tetramerization domain. Although the tetramerization domains bury the greatest amount of surface area in the MgsA oligomer, each of the domains participates in oligomerization to form a highly intertwined quaternary structure. Phosphate is bound at each AAA{sup +} ATP-binding site, but the active sites do not appear to be in a catalytically competent conformation due to displacement of Arg finger residues. E. coli MgsA is also shown to form a complex with the single-stranded DNA-binding protein through co-purification and biochemical studies. MgsA DNA-dependent ATPase activity is inhibited by single-stranded DNA-binding protein. Together, these structural and biochemical observations provide insights into the mechanisms of MgsA family AAA{sup +} proteins.

  14. Light induced DEP for immobilizing and orienting Escherichia coli bacteria

    NASA Astrophysics Data System (ADS)

    Miccio, Lisa; Marchesano, Valentina; Mugnano, Martina; Grilli, Simonetta; Ferraro, Pietro

    2016-01-01

    Manipulating bacteria and understanding their behavior when interacting with different substrates are of fundamental importance for patterning, detection, and any other topics related to health-care, food-enterprise, etc. Here, we adopt an innovative dielectrophoretic (DEP) approach based on electrode-free DEP for investigating smart but simple strategies for immobilization and orientation of bacteria. Escherichia coli DH5-alpha strain has been selected as subject of the study. The light induced DEP is achieved through ferroelectric iron-doped lithium niobate crystals used as substrates. Due to the photorefractive (PR) property of such material, suitable light patterns allow writing spatial-charges-distribution inside its volume and the resultant electric fields are able to immobilize E. coli on the surface. The experiments showed that, after laser irradiation, about 80% of bacteria is blocked and oriented along a particular direction on the crystals within an area of few square centimeters. The investigation presented here could open the way for detection or patterning applications based on a new driving mechanism. Future perspectives also include the possibility to actively switch by light the DEP forces, through the writing/erasing characteristic of PR fields, to dynamically control biofilm spatial structure and arrangement.

  15. Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca

    SciTech Connect

    Dr. David Nunn

    2010-09-30

    The current Verenium cellulosic ethanol process is based on the dilute-acid pretreatment of a biomass feedstock, followed by a two-stage fermentation of the pentose sugar-containing hydrolysate by a genetically modified ethanologenic Escherichia coli strain and a separate simultaneous saccharification-fermentation (SSF) of the cellulosic fraction by a genetically modified ethanologenic Klebsiella oxytoca strain and a fungal enzyme cocktail. In order to reduce unit operations and produce a fermentation beer with higher ethanol concentrations to reduce distillation costs, we have proposed to develop a simultaneous saccharification co-fermentation (SScF) process, where the fermentation of the pentose-containing hydrolysate and cellulosic fraction occurs within the same fermentation vessel. In order to accomplish this goal, improvements in the ethanologens must be made to address a number of issues that arise, including improved hydrolysate tolerance, co-fermentation of the pentose and hexose sugars and increased ethanol tolerance. Using a variety of approaches, including transcriptomics, strain adaptation, metagenomics and directed evolution, this work describes the efforts of a team of scientists from Verenium, University of Florida, Massachusetts Institute of Technology and Genomatica to improve the E. coli and K. oxytoca ethanologens to meet these requirements.

  16. GATC sequence and mismatch repair in Escherichia coli.

    PubMed Central

    Laengle-Rouault, F; Maenhaut-Michel, G; Radman, M

    1986-01-01

    The Escherichia coli mismatch repair system greatly improves DNA replication fidelity by repairing single mispaired and unpaired bases in newly synthesized DNA strands. Transient undermethylation of the GATC sequences makes the newly synthesized strands susceptible to mismatch repair enzymes. The role of unmethylated GATC sequences in mismatch repair was tested in transfection experiments with heteroduplex DNA of phage phi 174 without any GATC sequence or with two GATC sequences, containing in addition either a G:T mismatch (Eam+/Eam3) or a G:A mismatch (Bam+/Bam16). It appears that only DNA containing GATC sequences is subject to efficient mismatch repair dependent on E. coli mutH, mutL, mutS and mutU genes; however, also in the absence of GATC sequence some mut-dependent mismatch repair can be observed. These observations suggest that the mismatch repair enzymes recognize both the mismatch and the unmethylated GATC sequence in DNA over long distances. The presence of GATC sequence(s) in the substrate appears to be required for full mismatch repair activity and not only for its strand specificity according to the GATC methylation state. PMID:3019677

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

    PubMed

    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. PMID:26468108

  18. Epidemiology and Clinical Manifestations of Enteroaggregative Escherichia coli

    PubMed Central

    Hebbelstrup Jensen, Betina; Olsen, Katharina E. P.; Struve, Carsten; Petersen, Andreas Munk

    2014-01-01

    SUMMARY 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 occurred in Germany due to an EAEC O104:H4 strain, causing 54 deaths and 855 cases of HUS. This strain produces the potent Shiga toxin along with the aggregative fimbriae. An outbreak of urinary tract infection associated with EAEC in Copenhagen, Denmark, occurred in 1991; this involved extensive production of biofilm, an important characteristic of the pathogenicity of EAEC. However, the heterogeneity of EAEC continues to complicate diagnostics and also our understanding of pathogenicity. PMID:24982324

  19. Nutrient dependence of RNase E essentiality in Escherichia coli.

    PubMed

    Tamura, Masaru; Moore, Christopher J; Cohen, Stanley N

    2013-03-01

    Escherichia coli cells normally require RNase E activity to form colonies (colony-forming ability [CFA]). The CFA-defective phenotype of cells lacking RNase E is partly reversed by overexpression of the related endoribonuclease RNase G or by mutation of the gene encoding the RNA helicase DeaD. We found that the carbon source utilization by rne deaD doubly mutant bacteria differs from that of rne(+) cells and from that of cells mutated in deaD alone and that the loss of rne function in these bacteria limits conversion of the glycolytic pathway product phosphoenolpyruvate to the tricarboxylic acid (TCA) cycle intermediate oxaloacetic acid. We show that the mechanism underlying this effect is reduced production of the enzyme phosphoenolpyruvate carboxylase (PPC) and that adventitious overexpression of PPC, which facilitates phosphoenolpyruvate utilization and connects the glycolytic pathway with the TCA cycle, restored CFA to rne deaD mutant bacteria cultured on carbon sources that otherwise were unable to sustain growth. We further show that bacteria producing full-length RNase E, which allows formation of degradosomes, have nutritional requirements different from those of cells supplied with only the N-terminal catalytic region of RNase E and that mitigation of RNase E deficiency by overexpression of a related RNase, RNase G, is also affected by carbon source. Our results reveal previously unsuspected effects of RNase E deficiency and degradosome formation on nutrient utilization by E. coli cells. PMID:23275245

  20. Proteomic adaptations to starvation prepare Escherichia coli for disinfection tolerance.

    PubMed

    Du, Zhe; Nandakumar, Renu; Nickerson, Kenneth W; Li, Xu

    2015-02-01

    Despite the low nutrient level and constant presence of secondary disinfectants, bacterial re-growth still occurs in drinking water distribution systems. The molecular mechanisms that starved bacteria use to survive low-level chlorine-based disinfectants are not well understood. The objective of this study is to investigate these molecular mechanisms at the protein level that prepare starved cells for disinfection tolerance. Two commonly used secondary disinfectants chlorine and monochloramine, both at 1 mg/L, were used in this study. The proteomes of normal and starved Escherichia coli (K12 MG1655) cells were studied using quantitative proteomics. Over 60-min disinfection, starved cells showed significantly higher disinfection tolerance than normal cells based on the inactivation curves for both chlorine and monochloramine. Proteomic analyses suggest that starvation may prepare cells for the oxidative stress that chlorine-based disinfection will cause by affecting glutathione metabolism. In addition, proteins involved in stress regulation and stress responses were among the ones up-regulated under both starvation and chlorine/monochloramine disinfection. By comparing the fold changes under different conditions, it is suggested that starvation prepares E. coli for disinfection tolerance by increasing the expression of enzymes that can help cells survive chlorine/monochloramine disinfection. Protein co-expression analyses show that proteins in glycolysis and pentose phosphate pathway that were up-regulated under starvation are also involved in disinfection tolerance. Finally, the production and detoxification of methylglyoxal may be involved in the chlorine-based disinfection and cell defense mechanisms. PMID:25463932

  1. Three Mutations in Escherichia coli That Generate Transformable Functional Flagella

    PubMed Central

    Wang, Wenjing; Jiang, Zhengzeng; Westermann, Martin

    2012-01-01

    Hydrodynamics predicts that swimming bacteria generate a propulsion force when a helical flagellum rotates because rotating helices necessarily translate at a low Reynolds number. It is generally believed that the flagella of motile bacteria are semirigid helices with a fixed pitch determined by hydrodynamic principles. Here, we report the characterization of three mutations in laboratory strains of Escherichia coli that produce different steady-state flagella without losing cell motility. E. coli flagella rotate counterclockwise during forward swimming, and the normal form of the flagella is a left-handed helix. A single amino acid exchange A45G and a double mutation of A48S and S110A change the resting flagella to right-handed helices. The stationary flagella of the triple mutant were often straight or slightly curved at neutral pH. Deprotonation facilitates the helix formation of it. The helical and curved flagella can be transformed to the normal form by torsion upon rotation and thus propel the cell. These mutations arose in the long-term laboratory cultivation. However, flagella are under strong selection pressure as extracellular appendages, and similar transformable flagella would be common in natural environments. PMID:22923592

  2. Enhanced Deletion Formation by Aberrant DNA Replication in Escherichia Coli

    PubMed Central

    Saveson, C. J.; Lovett, S. T.

    1997-01-01

    Repeated genes and sequences are prone to genetic rearrangements including deletions. We have investigated deletion formation in Escherichia coli strains mutant for various replication functions. Deletion was selected between 787 base pair tandem repeats carried either on a ColE1-derived plasmid or on the E. coli chromosome. Only mutations in functions associated with DNA Polymerase III elevated deletion rates in our assays. Especially large increases were observed in strains mutant in dnaQ, the ? editing subunit of Pol III, and dnaB, the replication fork helicase. Mutations in several other functions also altered deletion formation: the ? polymerase (dnaE), the ? clamp loader complex (holC, dnaX), and the ? clamp (dnaN) subunits of Pol III and the primosomal proteins, dnaC and priA. Aberrant replication stimulated deletions through several pathways. Whereas the elevation in dnaB strains was mostly recA- and lexA-dependent, that in dnaQ strains was mostly recA- and lexA-independent. Deletion product analysis suggested that slipped mispairing, producing monomeric replicon products, may be preferentially increased in a dnaQ mutant and sister-strand exchange, producing dimeric replicon products, may be elevated in dnaE mutants. We conclude that aberrant Polymerase III replication can stimulate deletion events through several mechanisms of deletion and via both recA-dependent and independent pathways. PMID:9177997

  3. Protein antigen expression in Escherichia coli for antibody production.

    PubMed

    Rancour, David M; Backues, Steven K; Bednarek, Sebastian Y

    2010-01-01

    Escherichia coli is a frequently used expression system for the generation of protein encoded by genes from diverse kingdoms and, thus, it is well suited for the production of protein antigens for antibody generation. It is a system of choice for many due to factors such as (1) the commercial availability of a vast array of reagents and materials needed for cloning, expression, and purification and (2) the potential high protein yields that can be acquired in a timely and cost-effective manner. This chapter will focus on (1) the general principles to keep in mind when choosing an antigen to express and (2) the use of a modified pGEX vector system (Rancour et al., J. Biol. Chem. 279:54264-54274, 2004) to use in its expression. Simplified protocols are provided for (1) assessing the expression of your protein, (2) testing whether your protein is or is not expressed as a soluble product, (3) performing bulk purifications of soluble or insoluble E. coli-expressed protein to acquire enough to be used for a complete immunization protocol, and (4) an optional procedure for epitope tag removal from your expressed protein of interest in order to avoid the unnecessary and sometimes unwanted production of antibodies against the fusion protein affinity chromatography tag. These four procedures have been used extensively and successfully in our lab as a basis for the production of recombinant protein and subsequent antibody production. PMID:20602203

  4. Engineering Escherichia coli for high-level production of propionate.

    PubMed

    Akawi, Lamees; Srirangan, Kajan; Liu, Xuejia; Moo-Young, Murray; Perry Chou, C

    2015-07-01

    Mounting environmental concerns associated with the use of petroleum-based chemical manufacturing practices has generated significant interest in the development of biological alternatives for the production of propionate. However, biological platforms for propionate production have been limited to strict anaerobes, such as Propionibacteria and select Clostridia. In this work, we demonstrated high-level heterologous production of propionate under microaerobic conditions in engineered Escherichia coli. Activation of the native Sleeping beauty mutase (Sbm) operon not only transformed E. coli to be propionogenic (i.e., propionate-producing) but also introduced an intracellular "flux competition" between the traditional C2-fermentative pathway and the novel C3-fermentative pathway. Dissimilation of the major carbon source of glycerol was identified to critically affect such "flux competition" and, therefore, propionate synthesis. As a result, the propionogenic E. coli was further engineered by inactivation or overexpression of various genes involved in the glycerol dissimilation pathways and their individual genetic effects on propionate production were investigated. Generally, knocking out genes involved in glycerol dissimilation (except glpA) can minimize levels of solventogenesis and shift more dissimilated carbon flux toward the C3-fermentative pathway. For optimal propionate production with high C3:C2-fermentative product ratios, glycerol dissimilation should be channeled through the respiratory pathway and, upon suppressed solventogenesis with minimal production of highly reduced alcohols, the alternative NADH-consuming route associated with propionate synthesis can be critical for more flexible redox balancing. With the implementation of various biochemical and genetic strategies, high propionate titers of more than 11 g/L with high yields up to 0.4 g-propionate/g-glycerol (accounting for ~50 % of dissimilated glycerol) were achieved, demonstrating the potential for industrial application. To our knowledge, this represents the most effective engineered microbial system for propionate production with titers and yields comparable to those achieved by anaerobic batch cultivation of various native propionate-producing strains of Propionibacteria. PMID:25948049

  5. Response of Escherichia coli growth rate to osmotic shock.

    PubMed

    Rojas, Enrique; Theriot, Julie A; Huang, Kerwyn Casey

    2014-05-27

    It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless "stored" growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan. PMID:24821776

  6. Mutual Enhancement of Virulence by Enterotoxigenic and Enteropathogenic Escherichia coli

    PubMed Central

    Crane, John K.; Choudhari, Shilpa S.; Naeher, Tonniele M.; Duffey, Michael E.

    2006-01-01

    Enterotoxigenic Escherichia coli (ETEC) and enteropathogenic E. coli (EPEC) are common causes of diarrhea in children in developing countries. Dual infections with both pathogens have been noted fairly frequently in studies of diarrhea around the world. In previous laboratory work, we noted that cholera toxin and forskolin markedly potentiated EPEC-induced ATP release from the host cell, and this potentiated release was found to be mediated by the cystic fibrosis transmembrane conductance regulator. In this study, we examined whether the ETEC heat-labile toxin (LT) or the heat-stable toxin (STa, also known as ST) potentiated EPEC-induced ATP release. We found that crude ETEC culture filtrates, as well as purified ETEC toxins, did potentiate EPEC-induced ATP release in cultured T84 cells. Coinfection of T84 cells with live ETEC plus EPEC bacteria also resulted in enhanced ATP release compared to EPEC alone. In Ussing chamber studies of chloride secretion, adenine nucleotides released from the host by EPEC also significantly enhanced the chloride secretory responses that were triggered by crude ETEC filtrates, purified STa, and the peptide hormone guanylin. In addition, adenosine and LT had additive or synergistic effects in inducing vacuole formation in T84 cells. Therefore, ETEC toxins and EPEC-induced damage to the host cell both enhance the virulence of the other type of E. coli. Our in vitro data demonstrate a molecular basis for a microbial interaction, which could result in increased severity of disease in vivo in individuals who are coinfected with ETEC and EPEC. PMID:16495521

  7. Biosynthesis of odd-chain fatty alcohols in Escherichia coli.

    PubMed

    Cao, Ying-Xiu; Xiao, Wen-Hai; Liu, Duo; Zhang, Jin-Lai; Ding, Ming-Zhu; Yuan, Ying-Jin

    2015-05-01

    Engineered microbes offer the opportunity to design and implement artificial molecular pathways for renewable production of tailored chemical commodities. Targeted biosynthesis of odd-chain fatty alcohols is very challenging in microbe, due to the specificity of fatty acids synthase for two-carbon unit elongation. Here, we developed a novel strategy to directly tailor carbon number in fatty aldehydes formation step by incorporating ?-dioxygenase (?DOX) from Oryza sativa (rice) into Escherichia coli ?DOX oxidizes Cn fatty acids (even-chain) to form Cn-1 fatty aldehydes (odd-chain). Through combining ?DOX with fatty acyl-acyl carrier protein (-ACP) thioesterase (TE) and aldehyde reductase (AHR), the medium odd-chain fatty alcohols profile (C11, C13, C15) was firstly established in E. coli. Also, medium even-chain alkanes (C12, C14) were obtained by substitution of AHR to aldehyde decarbonylase (AD). The titer of odd-chain fatty alcohols was improved from 7.4mg/L to 101.5mg/L in tube cultivation by means of fine-tuning endogenous fatty acyl-ACP TE (TesA'), ?DOX, AHRs and the genes involved in fatty acids metabolism pathway. Through high cell density fed-batch fermentation, a titer of 1.95g/L odd-chain fatty alcohols was achieved, which was the highest reported titer in E. coli. Our system has greatly expanded the current microbial fatty alcohols profile that provides a new brand solution for producing complex and desired molecules in microbes. PMID:25773521

  8. Use of Miniaturized Protein Arrays for Escherichia coli O Serotyping

    PubMed Central

    Anjum, Muna F.; Tucker, James D.; Sprigings, Katherine A.; Woodward, Martin J.; Ehricht, Ralf

    2006-01-01

    Serological typing of Escherichia coli O antigens is a well-established method used for differentiation and identification of O serotypes commonly associated with disease. In this feasibility study, we have developed a novel somatic antibody-based miniaturized microarray chip, using 17 antisera, which can be used to detect bound whole-cell E. coli antigen with its corresponding immobilized antibody, to assess the feasibility of this approach. The chip was tested using the related 17 control strains, and the O types found by the microarray chip showed 100% correlation with the O types found by conventional typing. A blind trial was performed in which 100 E. coli isolates that had been O serotyped previously by the conventional assay were tested by the array approach. Overall, the O serotypes of 88% of isolates were correctly identified by the microarray method. For several isolates, ambiguity of O-type designation by microarray arose due to increased sensitivity of this method, allowing signal intensities of cross-reactions to be quantified. Investigation of discrepancies between conventional and microarray O serotyping indicated that some isolates upon storage had become untypeable and, therefore, gave poor signal intensity when tested by the microarray or retested by conventional means. For all 20 serotype O26 and O157 isolates, the apparent discrepancy in O serotyping was analyzed further by a third independent test, which confirmed the microarray results. Therefore, the use of miniaturized protein arrays increases the speed and efficiency of O serotyping in a cost-effective manner, and these preliminary findings suggest the microarray approach may have a higher accuracy than those of traditional O-serotyping methods. PMID:16682477

  9. Genomic Islands of Uropathogenic Escherichia coli Contribute to Virulence? †

    PubMed Central

    Lloyd, Amanda L.; Henderson, Tiffany A.; Vigil, Patrick D.; Mobley, Harry L. T.

    2009-01-01

    Uropathogenic Escherichia coli (UPEC) strain CFT073 contains 13 large genomic islands ranging in size from 32 kb to 123 kb. Eleven of these genomic islands were individually deleted from the genome, and nine isogenic mutants were tested for their ability to colonize the CBA/J mouse model of ascending urinary tract infection. Three genomic island mutants (?PAI-aspV, ?PAI-metV, and ?PAI-asnT) were significantly outcompeted by wild-type CFT073 in the bladders and/or kidneys following transurethral cochallenge (P ? 0.0139). The PAI-metV mutant also showed significant attenuation in the ability to independently colonize the kidneys (P = 0.0011). Specific genes within these islands contributed to the observed phenotype, including a previously uncharacterized iron acquisition cluster, fbpABCD (c0294 to c0297 [c0294-97]), autotransporter, picU (c0350), and RTX family exoprotein, tosA (c0363) in the PAI-aspV island. The double deletion mutant with deletions in both copies of the fbp iron acquisition operon (?c0294-97 ?c2518-15) was significantly outcompeted by wild-type CFT073 in cochallenge. Strains with mutations in a type VI secretion system within the PAI-metV island did not show attenuation. The attenuation of the PAI-metV island was localized to genes c3405-10, encoding a putative phosphotransferase transport system, which is common to UPEC and avian pathogenic E. coli strains but absent from E. coli K-12. We have shown that, in addition to encoding virulence genes, genomic islands contribute to the overall fitness of UPEC strain CFT073 in vivo. PMID:19329634

  10. Improving microbial biogasoline production in Escherichia coli using tolerance engineering

    DOE PAGESBeta

    Foo, Jee Loon; Jensen, Heather M.; Dahl, Robert H.; George, Kevin; Keasling, Jay D.; Lee, Taek Soon; Leong, Susanna; Mukhopadhyay, Aindrila

    2014-11-04

    Engineering microbial hosts for the production of fungible fuels requires mitigation of limitations posed on the production capacity. One such limitation arises from the inherent toxicity of solvent-like biofuel compounds to production strains, such as Escherichia coli. Here we show the importance of host engineering for the production of short-chain alcohols by studying the overexpression of genes upregulated in response to exogenous isopentenol. Using systems biology data, we selected 40 genes that were upregulated following isopentenol exposure and subsequently overexpressed them in E. coli. Overexpression of several of these candidates improved tolerance to exogenously added isopentenol. Genes conferring isopentenol tolerancemore »phenotypes belonged to diverse functional groups, such as oxidative stress response (soxS, fpr, and nrdH), general stress response (metR, yqhD, and gidB), heat shock-related response (ibpA), and transport (mdlB). To determine if these genes could also improve isopentenol production, we coexpressed the tolerance-enhancing genes individually with an isopentenol production pathway. Our data show that expression of 6 of the 8 candidates improved the production of isopentenol in E. coli, with the methionine biosynthesis regulator MetR improving the titer for isopentenol production by 55%. Additionally, expression of MdlB, an ABC transporter, facilitated a 12% improvement in isopentenol production. To our knowledge, MdlB is the first example of a transporter that can be used to improve production of a short-chain alcohol and provides a valuable new avenue for host engineering in biogasoline production.« less

  11. Genetic Basis of Persister Tolerance to Aminoglycosides in Escherichia coli

    PubMed Central

    Shan, Yue; Lazinski, David; Rowe, Sarah; Camilli, Andrew

    2015-01-01

    ABSTRACT Persisters are dormant variants that form a subpopulation of drug-tolerant cells largely responsible for the recalcitrance of chronic infections. However, our understanding of the genetic basis of antibiotic tolerance remains incomplete. In this study, we applied transposon sequencing (Tn-Seq) to systematically investigate the mechanism of aminoglycoside tolerance in Escherichia coli. We constructed a highly saturated transposon library that covered the majority of E. coli genes and promoter regions and exposed a stationary-phase culture to a lethal dose of gentamicin. Tn-Seq was performed to evaluate the survival of each mutant to gentamicin exposure. We found that the disruption of several distinct pathways affected gentamicin tolerance. We identified 105 disrupted gene/promoter regions with a more than 5-fold reduction in gentamicin tolerance and 37 genes with a more than 5-fold increased tolerance. Functional cluster analysis suggests that deficiency in motility and amino acid synthesis significantly diminished persisters tolerant to gentamicin, without changing the MIC. Amino acid auxotrophs, including serine, threonine, glutamine, and tryptophan auxotrophs, exhibit strongly decreased tolerance to gentamicin, which cannot be restored by supplying the corresponding amino acids to the culture. Interestingly, supplying these amino acids to wild-type E. coli sensitizes stationary-phase cells to gentamicin, possibly through the inhibition of amino acid synthesis. In addition, we found that the deletion of amino acid synthesis genes significantly increases gentamicin uptake in stationary phase, while the deletion of flagellar genes does not affect gentamicin uptake. We conclude that activation of motility and amino acid biosynthesis contributes to the formation of persisters tolerant to gentamicin. PMID:25852159

  12. Optimizing Escherichia coli's metabolism for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Nieves, Ismael U.

    In the last few years there have been many publications about applications that center on the generation of electrons from bacterial cells. These applications take advantage of the catabolic diversity of microbes to generate electrical power. The practicality of these applications depends on the microorganism's ability to effectively donate electrons, either directly to the electrode or indirectly through the use of a mediator. After establishing the limitations of electrical output in microbial fuel cells (MFCs) imposed by the bacterial cells, a spectrophotometric assay measuring the indirect reduction of the electronophore neutral red via iron reduction was used to measure electron production from Escherichia coli resting cells. Using this assay I identified NADH dehydrogenase I as a likely site of neutral red reduction. The only previously reported site of interaction between E. coli cells and NR is at the hydrogenases. Although we cannot rule out the possibility that NR is reduced by soluble hydrogenases in the cytoplasm, this previous report indicated that hydrogenase activity does not account for all of the NR reduction activity. Supporting this, data in this thesis suggest that the hydrogenases play a small role in NR reduction. It seems that NR reduction is largely taking place within the cytoplasmic membrane of the bacterial cells, serving as a substrate of enzymes that typically reduce quinones. Furthermore, it seems that under the experimental conditions used here, E. coli's catabolism of glucose is rather inefficient. Instead of using the complete TCA cycle, the bacterial cells are carrying out fermentation, leading to incomplete oxidation of the fuel and low yields of electrons. The results obtained from the TC31 strain suggest that eliminating fermentation pathways to improve NR reduction was the correct approach. Following up on this a new strain was created, KN02, which, in addition to the mutations on strain TC31, lacks acetate kinase activity.

  13. Virulence factors in Escherichia coli urinary tract infection.

    PubMed Central

    Johnson, J R

    1991-01-01

    Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans. Images PMID:1672263

  14. Response of Escherichia coli growth rate to osmotic shock

    PubMed Central

    Rojas, Enrique; Theriot, Julie A.; Huang, Kerwyn Casey

    2014-01-01

    It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless “stored” growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan. PMID:24821776

  15. Isolation of Escherichia coli O157 from pigs with colibacillosis in Canada and the United States.

    PubMed

    Glantz, P J; Gyles, C L; Greenfield, J; Otskov, F

    1973-04-01

    Cultures of Escherichia coli isolated from colibacillosis in pigs in Canada and the U.S.A. and previously identified as unclassified E. coli OX36 were found to belong to a new E. coli O group 157. Strains of E. coli V145, GIRI, C308 and V17 which had a weak relationship to E. coli O116 also were found to belong to O157. The increased incidence of E. coli O157 in colibacillosis of swine stresses the inclusion of this O group among those enteropathogenic for swine. PMID:4266701

  16. Transformation of serum-susceptible Escherichia coli O111 with p16Slux plasmid to allow for real-time monitoring of complement-based inactivation of bacterial growth in bovine milk.

    PubMed

    Maye, S; Stanton, C; Fitzgerald, G F; Kelly, P M

    2016-01-01

    Complement activity has only recently been characterized in raw bovine milk. However, the activity of this component of the innate immune system was found to diminish as milk was subjected to heat or partitioning during cream separation. Detection of complement in milk relies on a bactericidal assay. This assay exploits the specific growth susceptibility of Escherichia coli O111 to the presence of complement. Practical application of the assay was demonstrated when a reduction in complement activity was recorded in the case of pasteurized and reduced-fat milks. This presented an opportunity to improve the functionality of the bactericidal assay by incorporating bioluminescence capability into the target organism. Following some adaptation, the strain was transformed by correctly integrating the p16Slux plasmid. Growth properties of the transformed strain of E. coli O111 were unaffected by the modification. The efficacy of the strain adaptation was correlated using the LINEST function analysis [r=0.966; standard error of prediction (SEy)=0.957] bioluminescence with that of bactericidal assay total plate counts within the range of 7.5 to 9.2 log cfu/mL using a combination of raw and processed milk samples. Importantly, the transformed E. coli O111 p16Slux strain could be identified in milk and broth samples using bioluminescence measurement, thus enabling the bactericidal assay-viability test to be monitored in real time throughout incubation. PMID:26585477

  17. Selective synthesis of plasmid-coded proteins by Escherichia coli during recovery from chloramphenicol treatment.

    PubMed Central

    Neidhardt, F C; Wirth, R; Smith, M W; Van Bogelen, R

    1980-01-01

    Protein products of recombinant ColE1 plasmids are preferentially synthesized and can easily be identified in Escherichia coli cells recovering from prolonged treatment with chloramphenicol. Images PMID:6995449

  18. DETOXIFICATION OF ORGANOPHOSPHATE PESTICIDES BY IMMOBILIZED ESCHERICHIA COLI EXPRESSING ORGANOPHOSPHORUS HYDROLASE ON CELL SURFACE. (R823663)

    EPA Science Inventory

    An improved whole-cell technology for detoxifying organophosphate nerve agents was recently developed based on genetically engineered Escherichia coli with organophosphorus hydrolase anchored on the surface. This article reports the immobilization of these novel biocatalys...

  19. Genome Sequences of Two Bovine Mastitis-Causing Escherichia coli Strains

    PubMed Central

    Kempf, Florent; Loux, Valentin

    2015-01-01

    Escherichia coli is one of the main pathogenic agents causing inflammatory infections in the bovine udder. Here, we report the draft genome sequences of two strains isolated from different cases of clinical mastitis. PMID:25858841

  20. Analysis of antimicrobial resistance genes and plasmids from commensal Escherichia coli

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Escherichia coli are commonly associated with various animal and environmental sources. They often acquire antimicrobial resistance (AR) to classes of drugs that are used to treat Gram-negative infections such as aminoglycosides, cephalosporins, fluoroquinolones and sulfonamides. Plasmi...

  1. An active dimanganese(III)-tyrosyl radical cofactor in Escherichia coli class Ib ribonucleotide reductase

    E-print Network

    Cotruvo, Joseph A.

    Escherichia coli class Ib ribonucleotide reductase (RNR) converts nucleoside 5?-diphosphates to deoxynucleoside 5?-diphosphates and is expressed under iron-limited and oxidative stress conditions. This RNR is composed of ...

  2. Prevalence and antimicrobial resistance in Escherichia coli from food and animals in Lagos, Nigeria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background Foodborne bacteria are often associated with human infections; these infections can become more complicated to treat if the bacteria are also resistant to antimicrobials. In this study, prevalence, antimicrobial resistance, and genetic relatedness of Escherichia coli among food producing ...

  3. Novel function and regulation of mutagenic DNA polymerases in Escherichia coli

    E-print Network

    Jarosz, Daniel F

    2007-01-01

    The observation that mutations in the Escherichia coli genes umuC+ and umuD+ abolish mutagenesis induced by UV-light strongly supported the counterintuitive notion that such mutagenesis is an active rather than passive ...

  4. Enterococcus and Escherichia coli fecal source apportionment with microbial source tracking genetic markers - is it feasible?

    EPA Science Inventory

    Fecal pollution is measured in surface waters using culture-based measurements of enterococci and Escherichia coli bacteria. Source apportionment of these two fecal indicator bacteria is an urgent need for prioritizing remediation efforts and quantifying health risks associated...

  5. Engineered Escherichia coli Silver-Binding Periplasmic Protein That Promotes Silver Tolerance

    E-print Network

    Sedlak, Ruth Hall; Hnilova, Marketa; Grosh, Carolynn; Fong, Hanson; Baneyx, Francois; Schwartz, Dan; Sarikaya, Mehmet; Tamerler, Candan; Traxler, Beth

    2012-01-27

    as pathogens but, alternatively, could be potentially useful in nanomaterial-manufacturing applications. While naturally adapted isolates typically utilize efflux pumps to achieve metal resistance, we have engineered a silver-tolerant Escherichia coli strain...

  6. THE ENTEROHEMORRHAGIC ESCHERICHIA COLI EFFECTOR PROTEIN NLEF BINDS MAMMALIAN HOST PROTEINS

    E-print Network

    Olsen, Rachel Lee

    2012-12-31

    The extracellular human pathogens enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) and the related mouse pathogen Citrobacter rodentium inject type III secretion system (T3SS) effector proteins to promote their replication...

  7. RpoS proteolysis is controlled directly by ATP levels in Escherichia coli

    E-print Network

    Peterson, Celeste N.

    The master regulator of stationary phase in Escherichia coli, RpoS, responds to carbon availability through changes in stability, but the individual steps in the pathway are unknown. Here we systematically block key steps ...

  8. Differential decay of Enterococci and Escherichia coli originating from two fecal pollution sources

    EPA Science Inventory

    Using in situ subtropical aquatic mesocosms, fecal source (cattle manure versus sewage) was shown to be the most important contributor to differential loss in viability of fecal indicator bacteria (FIB), specifically enterococci in freshwater and Escherichia coli in marine habita...

  9. COMPARISON OF ESCHERICHIA COLI, TOTAL COLIFORM, AND FECAL COLIFORM POPULATIONS AS INDICATORS OF WASTEWATER TREATMENT EFFICIENCY

    EPA Science Inventory

    Escherichia coli, total coliform, and fecal coliform data were collected from two wastewater treatment facilities, a subsurface constructed wetlands, and the receiving stream. Results are presented from individual wastewater treatment process streams, final effluent and river sit...

  10. Adaptive evolution of the lactose utilization network in experimentally evolved populations of Escherichia coli

    E-print Network

    Quan, Selwyn; Kwota, Zakari; Duong, Trang; Balazsi, Gabor; Cooper, Tim F.; Monds, Russell D.; Ray, J. Christian J.

    2012-01-12

    . To this end, we have focused on understanding both how and why the lactose utilization network has evolved in replicate populations of Escherichia coli. We found that lac operon regulation became strikingly variable, including changes in the mode...

  11. Lactic Acid Bacteria as an Intervention Against Shiga Toxin-Producing Escherichia coli in Beef 

    E-print Network

    Kirsch, Katie Rose

    2015-08-07

    Shiga toxin-producing Escherichia coli (STEC) are Gram-negative bacteria that are able to cause disease in humans and animals. Beef is a significant transmission vehicle of foodborne outbreaks of STEC, which are commensal inhabitants...

  12. Escherichia coli class Ib ribonucleotide reductase contains a dimanganese(III)-tyrosyl radical cofactor in vivo

    E-print Network

    Cotruvo, Joseph A.

    Escherichia coli class Ib ribonucleotide reductase (RNR) converts nucleoside 5?-diphosphates to deoxynucleoside 5?-diphosphates in iron-limited and oxidative stress conditions. We have recently demonstrated in vitro that ...

  13. Characterization of a Novel Pyranopyridine Inhibitor of the AcrAB Efflux Pump of Escherichia coli

    E-print Network

    Opperman, Timothy J.

    Members of the resistance-nodulation-division (RND) family of efflux pumps, such as AcrAB-TolC of Escherichia coli, play major roles in multidrug resistance (MDR) in Gram-negative bacteria. A strategy for combating MDR is ...

  14. Production of acetol from glycerol using engineered Escherichia coli Hongliang Zhu a

    E-print Network

    Wood, Thomas K.

    : Acetol Glycerol Methylglyoxal a b s t r a c t Escherichia coli Lin43 is a strain which has some mutations to glycerol, it quickly accumulates lethal levels of methylglyoxal, which is a precursor of acetol; acetol

  15. Crystal structure of the CRISPR RNA-guided surveillance complex from Escherichia coli

    E-print Network

    Jackson, Ryan N.; Golden, Sarah M.; van Erp, Paul B. G.; Carter, Joshua; Westra, Edze R.; Brouns, Stan J. J.; van der Oost, John; Terwilliger, Thomas C.; Read, Randy J.; Wiedenheft, Blake

    2014-08-07

    Clustered regularly interspaced short palindromic repeats (CRISPRs) are essential components of RNA-guided adaptive immune systems that protect bacteria and archaea from viruses and plasmids. In Escherichia coli, short CRISPR-derived RNAs (cr...

  16. Surface Characteristics and Adhesion Behavior of Escherichia coli O157:H7: Role of Extracellular Macromolecules

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface macromolecule cleavage experiments were conducted on enterohaemorrhagic Escherichia coli O157:H7 cells to investigate the influence of these macromolecules on cell surface properties. Electrophoretic mobility, hydrophobicity, and titration experiments were carried out on proteinase K treate...

  17. Draft Genome Sequence of Enterotoxigenic Escherichia coli Strain W25K

    PubMed Central

    Ren, Wenkai; Liu, Gang; Yin, Jie; Chen, Shuai; Li, Tiejun; Kong, Xiangfeng; Peng, Yuanyi; Hardwidge, Philip R.

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease in humans and newly weaned pigs. Here, we report the draft genome sequence of ETEC strain W25K, which causes diarrhea in piglets. PMID:24970825

  18. Importance of the Maintenance Pathway in the Regulation of the Activity of Escherichia coli Ribonucleotide Reductase

    E-print Network

    Hristova, Daniela

    Ribonucleotide reductases (RNRs) catalyze the conversion of nucleotides to deoxynucleotides in all organisms. The Escherichia coli class Ia RNR is composed of ? and ? subunits that form an ?[subscript 2]?[subscript 2] ...

  19. Antibacterial activity of ?-terpineol may induce morphostructural alterations in Escherichia coli

    PubMed Central

    Li, Li; Shi, Chaofeng; Yin, Zhongqiong; Jia, Renyong; Peng, Lianci; Kang, Shuai; Li, Zhengwen

    2014-01-01

    The antibacterial effect of ?-terpineol from Cinnamomum longepaniculatum (Gamble) N. Chao leaf essential oils were studied with special reference to the mechanism of inhibiting the standard strain of Escherichia coli (CMCC (B) 44102) growth at ultrastructural level. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) and time-kill curves of ?-terpineol were determined; Escherichia coli was treated with ?-terpineol and observed under a transmission electron microscope. The MIC and MBC values of ?-terpineol were all 0.78 ?L/mL, and time-kill curves showed the concentration-dependent. Under the transmission electron microscopy (TEM), Escherichia coli exposed to MIC levels of ?-terpineol exhibited decreased cell size and irregular cell shape, cell wall and cell membrane were ruptured, nucleus cytoplasm was reduced and nuclear area gathered aside. Results suggest that ?-terpineol has excellent antibacterial activity and could induce morphological changes of Escherichia coli. PMID:25763048

  20. Stringency of substrate specificity of Escherichia coli malate dehydrogenase.

    SciTech Connect

    Boernke, W. E.; Millard, C. S.; Stevens, P. W.; Kakar, S. N.; Stevens, F. J.; Donnelly, M. I.; Nebraska Wesleyan Univ.

    1995-09-10

    Malate dehydrogenase and lactate dehydrogenase are members of the structurally and functionally homologous family of 2-ketoacid dehydrogenases. Both enzymes display high specificity for their respective keto substrates, oxaloacetate and pyruvate. Closer analysis of their specificity, however, reveals that the specificity of malate dehydrogenase is much stricter and less malleable than that of lactate dehydrogenase. Site-specific mutagenesis of the two enzymes in an attempt to reverse their specificity has met with contrary results. Conversion of a specific active-site glutamine to arginine in lactate dehydrogenase from Bacillus stearothermophilus generated an enzyme that displayed activity toward oxaloacetate equal to that of the native enzyme toward pyruvate (H. M. Wilks et al. (1988) Science 242, 1541-1544). We have constructed a series of mutants in the mobile, active site loop of the Escherichia coli malate dehydrogenase that incorporate the complementary change, conversion of arginine 81 to glutamine, to evaluate the role of charge distribution and conformational flexibility within this loop in defining the substrate specificity of these enzymes. Mutants incorporating the change R81Q all had reversed specificity, displaying much higher activity toward pyruvate than to the natural substrate, oxaloacetate. In contrast to the mutated lactate dehydrogenase, these reversed-specificity mutants were much less active than the native enzyme. Secondary mutations within the loop of the E. coli enzyme (A80N, A80P, A80P/M85E/D86T) had either no or only moderately beneficial effects on the activity of the mutant enzyme toward pyruvate. The mutation A80P, which can be expected to reduce the overall flexibility of the loop, modestly improved activity toward pyruvate. The possible physiological relevance of the stringent specificity of malate dehydrogenase was investigated. In normal strains of E. coli, fermentative metabolism was not affected by expression of the mutant malate dehydrogenase. However, when expressed in a strain of E. coli unable to ferment glucose, the mutant enzyme restored growth and produced lactic acid as the sole fermentation product.

  1. Scalable production of biliverdin IX? by Escherichia coli

    PubMed Central

    2012-01-01

    Background Biliverdin IX? is produced when heme undergoes reductive ring cleavage at the ?-methene bridge catalyzed by heme oxygenase. It is subsequently reduced by biliverdin reductase to bilirubin IX? which is a potent endogenous antioxidant. Biliverdin IX?, through interaction with biliverdin reductase, also initiates signaling pathways leading to anti-inflammatory responses and suppression of cellular pro-inflammatory events. The use of biliverdin IX? as a cytoprotective therapeutic has been suggested, but its clinical development and use is currently limited by insufficient quantity, uncertain purity, and derivation from mammalian materials. To address these limitations, methods to produce, recover and purify biliverdin IX? from bacterial cultures of Escherichia coli were investigated and developed. Results Recombinant E. coli strains BL21(HO1) and BL21(mHO1) expressing cyanobacterial heme oxygenase gene ho1 and a sequence modified version (mho1) optimized for E. coli expression, respectively, were constructed and shown to produce biliverdin IX? in batch and fed-batch bioreactor cultures. Strain BL21(mHO1) produced roughly twice the amount of biliverdin IX? than did strain BL21(HO1). Lactose either alone or in combination with glycerol supported consistent biliverdin IX? production by strain BL21(mHO1) (up to an average of 23. 5mg L-1 culture) in fed-batch mode and production by strain BL21 (HO1) in batch-mode was scalable to 100L bioreactor culture volumes. Synthesis of the modified ho1 gene protein product was determined, and identity of the enzyme reaction product as biliverdin IX? was confirmed by spectroscopic and chromatographic analyses and its ability to serve as a substrate for human biliverdin reductase A. Conclusions Methods for the scalable production, recovery, and purification of biliverdin IX? by E. coli were developed based on expression of a cyanobacterial ho1 gene. The purity of the produced biliverdin IX? and its ability to serve as substrate for human biliverdin reductase A suggest its potential as a clinically useful therapeutic. PMID:23176158

  2. Identification of Amino Acid Residues Contributing to the Mechanism of Cooperativity in Escherichia coli D-3-Phosphoglycerate Dehydrogenase

    E-print Network

    Grant, Gregory

    Identification of Amino Acid Residues Contributing to the Mechanism of Cooperativity in EscherichiaVised Manuscript ReceiVed October 25, 2005 ABSTRACT: L-Serine inhibits the catalytic activity of Escherichia coli D of the regulatory mechanism of the ACT domain in general. Escherichia coli D-3-phosphoglycerate dehydrogenase (PGDH

  3. Low intensity infrared laser effects on Escherichia coli cultures and plasmid DNA

    NASA Astrophysics Data System (ADS)

    Fonseca, A. S.; Teixeira, A. F.; Presta, G. A.; Geller, M.; Valença, S. S.; Paoli, F.

    2012-10-01

    Biostimulative effect of low intensity laser in tissues has been described on a photobiological basis and clinical protocols are recommended for treatment of various diseases. The aim of this work was to evaluate effects of laser exposure on the survival of Escherichia coli cultures and plasmid topological forms. Escherichia coli cultures and plasmids were exposed to infrared laser to study bacterial survival and electrophoretic profile, respectively. Data indicate low intensity infrared laser: (i) had no effect on E. coli wild type, endonuclease IV, exonuclease III, formamidopyrimidine DNA glycosylase/MutM protein and endonuclease III deficient cultures, but decreased the survival of E. coli UvrA protein deficient cultures; (ii) there was no alteration in the electrophoretic profile of plasmids. Exposure to low intensity infrared laser decreases survival of Escherichia coli cultures deficient in nucleotide excision repair of DNA and this effect could depend on fluences, wavelength and tissues conditions.

  4. OmpA influences Escherichia coli biofilm formation by repressing cellulose production through the CpxRA

    E-print Network

    Wood, Thomas K.

    OmpA influences Escherichia coli biofilm formation by repressing cellulose production through Previously we discovered that OmpA of Escherichia coli increases biofilm formation on polystyrene sur- faces coli in a complex manner. For example, flagella and type 1 pili are required for biofilm formation

  5. Escherichia coli Cell Surface Perturbation and Disruption Induced by Antimicrobial Peptides BP100 and pepR*

    E-print Network

    Pompeu Fabra, Universitat

    Escherichia coli Cell Surface Perturbation and Disruption Induced by Antimicrobial Peptides BP100. In this study, the mech- anisms adopted by two AMPs in disrupting the Gram-negative Escherichia coli bacterial capsid protein. Both BP100 and pepR were found to inhibit the growth of E. coli at micromolar

  6. Characterization of the role that alternative ribonucleotide reductases play in restoring replication in the presence of hydroxyurea in Escherichia coli

    E-print Network

    Courcelle, Justin

    replication in the presence of hydroxyurea in Escherichia coli by Michael Sadek Abstract: DNA replication radical (3). Escherichia coli contain three ribonucleotide reductases that each function under different replication. However, recent studies in E. coli have shown that following an initial period of inhibition, DNA

  7. 77 FR 26725 - Changes to FSIS Traceback, Recall Procedures for Escherichia coli O157:H7 Positive Raw Beef...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... Food Safety and Inspection Service Changes to FSIS Traceback, Recall Procedures for Escherichia coli... find raw ground beef presumptive positive for Escherichia coli (E. coli) O157:H7. This methodology will... Flexibility Analysis of the Proposed Rules to Ensure the Safety of Juice and Juice Products'' (63 FR...

  8. Importance of the C-Terminal Helix to the Stability and Enzymatic Activity of Escherichia coli Ribonuclease H

    E-print Network

    Raschke, Tanya M.

    Importance of the C-Terminal Helix to the Stability and Enzymatic Activity of Escherichia coli Escherichia coli is the best-characterized member of the family and serves as a model for structure stable than the E. coli homolog. The HIV domain also shows increased disorder in its C-terminal regions

  9. Comparative analysis of Staphylococcus aureus and Escherichia coli microcalorimetric growth

    PubMed Central

    2013-01-01

    Background Microcalorimetric bacterial growth studies have illustrated that thermograms differ significantly with both culture media and strain. The present contribution examines the possibility of discriminating between certain bacterial strains by microcalorimetry and the qualitative and quantitative contribution of the sample volume to the observed thermograms. Growth patterns of samples of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) were analyzed. Certain features of the thermograms that may serve to distinguish between these bacterial strains were identified. Results The thermograms of the two bacterial strains with sample volumes ranging from 0.3 to 0.7 ml and same initial bacterial concentration were analyzed. Both strains exhibit a roughly 2-peak shape that differs by peak amplitude and position along the time scale. Seven parameters corresponding to the thermogram key points related to time and heat flow values were proposed and statistically analyzed. The most relevant parameters appear to be the time to reach a heat flow of 0.05 mW (1.67?±?0.46 h in E. coli vs. 2.99?±?0.53 h in S. aureus, p?coli vs. 2.87?±?0.65 h in S. aureus, p?Escherichia coli display, under similar experimental conditions, distinct thermal growth patterns. The two strains can be easily differentiated using a selection of the proposed parameters. The presented Peakfit analysis of the complex thermal signal provides the necessary means for establishing the optimal growth conditions of various bacterial strains. These conditions are needed for the standardization of the isothermal microcalorimetry method in view of its further use in qualitative and quantitative estimation of bacterial growth. PMID:23879872

  10. Symmetry and asymmetry inthe function of Escherichia coli integration host factor: implications for target

    E-print Network

    Clore, G. Marius

    Symmetry and asymmetry inthe function of Escherichia coli integration host factor: implications for target identification by DNA-binding proteins Milton H. Werner, G. Marius Clore, Angela M. Gronenborn of Health, Bethesda, Maryland 20892, USA. Background: Escherichia coil integration host factor (IHF

  11. Cytoplasmic protein mobility in osmotically stressed Escherichia coli.

    PubMed

    Konopka, Michael C; Sochacki, Kem A; Bratton, Benjamin P; Shkel, Irina A; Record, M Thomas; Weisshaar, James C

    2009-01-01

    Facile diffusion of globular proteins within a cytoplasm that is dense with biopolymers is essential to normal cellular biochemical activity and growth. Remarkably, Escherichia coli grows in minimal medium over a wide range of external osmolalities (0.03 to 1.8 osmol). The mean cytoplasmic biopolymer volume fraction ((phi)) for such adapted cells ranges from 0.16 at 0.10 osmol to 0.36 at 1.45 osmol. For cells grown at 0.28 osmol, a similar phi range is obtained by plasmolysis (sudden osmotic upshift) using NaCl or sucrose as the external osmolyte, after which the only available cellular response is passive loss of cytoplasmic water. Here we measure the effective axial diffusion coefficient of green fluorescent protein (D(GFP)) in the cytoplasm of E. coli cells as a function of (phi) for both plasmolyzed and adapted cells. For plasmolyzed cells, the median D(GFP) (D(GFP)(m)) decreases by a factor of 70 as (phi) increases from 0.16 to 0.33. In sharp contrast, for adapted cells, D(GFP)(m) decreases only by a factor of 2.1 as (phi) increases from 0.16 to 0.36. Clearly, GFP diffusion is not determined by (phi) alone. By comparison with quantitative models, we show that the data cannot be explained by crowding theory. We suggest possible underlying causes of this surprising effect and further experiments that will help choose among competing hypotheses. Recovery of the ability of proteins to diffuse in the cytoplasm after plasmolysis may well be a key determinant of the time scale of the recovery of growth. PMID:18952804

  12. Uroporphyrin-accumulating mutant of Escherichia coli K-12.

    PubMed Central

    S?s?rman, A; Chartrand, P; Proschek, R; Desrochers, M; Tardif, D; Lapointe, C

    1975-01-01

    An uroporphyrin III-accumulating mutant of Escherichia coli K-12 was isolated by neomycin. The mutant, designated SASQ85, was catalase deficient and formed dwarf colonies on usual media. Comparative extraction by cyclohexanone and ethyl acetate showed the superiority of the former for the extraction of the uroporphyrin accumulated by the mutant. Cell-free extracts of SASQ85 were able to convert 5-aminolevulinic acid and porphobilinogen to uroporphyrinogen, but not to copro- or protoporphyrinogen. Under the same conditions cell-free extracts of the parent strain converted 5-aminolevulinic to uroporphyringen, coproporphyrinogen, and protoporphyrinogen. The conversion of porphobilinogen to uroporphyrinogen by cell-free extracts of the mutant was inhibited 98 and 95%, respectively, by p-chloromercuribenzoate and p-chloromercuriphenyl-sulfonate, indicating the presence of uroporphyrinogen synthetase activity in the extracts. Spontaneous transformation of porphobilinogen to uroporphyrin was not detectable under the experimental conditions used [4 h at 37 C in tris(hydroxymethyl)aminomethane-potassium phosphate buffer, pH 8.2]. The results indicate a deficient uroporphyrinogen decarboxylase activity of SASQ85 which is thus the first uroporphyrinogen decarboxylase-deficient mutant isolated in E. coli K-12. Mapping of the corresponding locus by P1-mediated transduction revealed the frequent joint transduction of hemE and thiA markers (frequency of co-transduction, 41 to 44%). The results of the genetic analysis suggest the gene order rif, hemE, thiA, metA; however, they do not totally exclude the gene order rif, thiA, hemE, metA. PMID:1104578

  13. Exchange of Spacer Regions between Rrna Operons in Escherichia Coli

    PubMed Central

    Harvey, S.; Hill, C. W.

    1990-01-01

    The Escherichia coli rRNA operons each have one of two types of spacer separating the 16S and 23S coding regions. The spacers of four operons encode tRNA(Glu2) and the other three encode both tRNA(Ile) and tRNA(Ala 1 B). We have prepared a series of mutants in which the spacer region of a particular rrn operon has been replaced by the opposite type. Included among these were a mutant retaining only a single copy of the tRNA(Glu2) spacer (at rrnG) and another retaining only a single copy of the tRNA(Ile)-tRNA(Ala 1 B) spacer (at rrnA). While both mutants grew more slowly than controls, the mutant deficient in tRNA(Glu2) spacers was more severely affected. At a frequency of 6 X 10(-5), these mutants phenotypically reverted to faster growing types by increasing the copy number of the deficient spacer. In most of these phenotypic revertants, the deficient spacer type appeared in a rrn operon which previously contained the surplus type, bringing the ratio of spacer types closer to normal. In a few cases, these spacer changes were accompanied by an inversion of the chromosomal material between the donor and recipient rrn operons. Two examples of inversion of one-half of the E. coli chromosome between rrnG and rrnH were observed. The correlation of spacer change with inversion indicated that, in these particular cases, the change was due to an intrachromatid gene conversion event accompanied by a reciprocal crossover rather than reciprocal exchange between sister chromatids. PMID:2168847

  14. Isolation of Escherichia coli mutants defective in uptake of molybdate.

    PubMed Central

    Hemschemeier, S; Grund, M; Keuntje, B; Eichenlaub, R

    1991-01-01

    For the study of molybdenum uptake by Escherichia coli, we generated Tn5lac transposition mutants, which were screened for the pleiotropic loss of molybdoenzyme activities. Three mutants A1, A4, and M22 were finally selected for further analysis. Even in the presence of 100 microM molybdate in the growth medium, no active nitrate reductase, formate dehydrogenase, and trimethylamine-N-oxide reductase were detected in these mutants, indicating that the intracellular supply of molybdenum was not sufficient. This was also supported by the observation that introduction of plasmid pWK225 carrying the complete nif regulon of Klebsiella pneumoniae did not lead to a functional expression of nitrogenase. Finally, molybdenum determination by induced coupled plasma mass spectroscopy confirmed a significant reduction of cell-bound molybdenum in the mutants compared with that in wild-type E. coli, even at high molybdate concentrations in the medium. A genomic library established with the plasmid mini-F-derived cop(ts) vector pJE258 allowed the isolation of cosmid pBK229 complementing the molybdate uptake deficiency of the chlD mutant and the Tn5lac-induced mutants. Certain subfragments of pBK229 which do not contain the chlD gene are still able to complement the Tn5lac mutants. Mapping experiments showed that the Tn5lac insertions did not occur within the chromosomal region present in pBK229 but did occur very close to that region. We assume that the Tn5lac insertions have a polar effect, thus preventing the expression of transport genes, or that a positively acting regulatory element was inactivated. Images FIG. 5 PMID:1655715

  15. A domain sequence approach to pangenomics: applications to Escherichia coli

    PubMed Central

    Snipen, Lars-Gustav

    2013-01-01

    The study of microbial pangenomes relies on the computation of gene families, i.e. the clustering of coding sequences into groups of essentially similar genes. There is no standard approach to obtain such gene families. Ideally, the gene family computations should be robust against errors in the annotation of genes in various genomes. In an attempt to achieve this robustness, we propose to cluster sequences by their domain sequence, i.e. the ordered sequence of domains in their protein sequence. In a study of 347 genomes from Escherichia coli we find on average around 4500 proteins having hits in Pfam-A in every genome, clustering into around 2500 distinct domain sequence families in each genome. Across all genomes we find a total of 5724 such families. A binomial mixture model approach indicates this is around 95% of all domain sequences we would expect to see in E. coli in the future. A Heaps law analysis indicates the population of domain sequences is larger, but this analysis is also very sensitive to smaller changes in the computation procedure. The resolution between strains is good despite the coarse grouping obtained by domain sequence families. Clustering sequences by their ordered domain content give us domain sequence families, who are robust to errors in the gene prediction step. The computational load of the procedure scales linearly with the number of genomes, which is needed for the future explosion in the number of re-sequenced strains. The use of domain sequence families for a functional classification of strains clearly has some potential to be explored. PMID:24555018

  16. CRISPR Content Correlates with the Pathogenic Potential of Escherichia coli

    PubMed Central

    García-Gutiérrez, Enriqueta; Almendros, Cristóbal; Mojica, Francisco J. M.; Guzmán, Noemí M.; García-Martínez, Jesús

    2015-01-01

    Guide RNA molecules (crRNA) produced from clustered regularly interspaced short palindromic repeat (CRISPR) arrays, altogether with effector proteins (Cas) encoded by cognate cas (CRISPR associated) genes, mount an interference mechanism (CRISPR-Cas) that limits acquisition of foreign DNA in Bacteria and Archaea. The specificity of this action is provided by the repeat intervening spacer carried in the crRNA, which upon hybridization with complementary sequences enables their degradation by a Cas endonuclease. Moreover, CRISPR arrays are dynamic landscapes that may gain new spacers from infecting elements or lose them for example during genome replication. Thus, the spacer content of a strain determines the diversity of sequences that can be targeted by the corresponding CRISPR-Cas system reflecting its functionality. Most Escherichia coli strains possess either type I-E or I-F CRISPR-Cas systems. To evaluate their impact on the pathogenicity of the species, we inferred the pathotype and pathogenic potential of 126 strains of this and other closely related species and analyzed their repeat content. Our results revealed a negative correlation between the number of I-E CRISPR units in this system and the presence of pathogenicity traits: the median number of repeats was 2.5-fold higher for commensal isolates (with 29.5 units, range 0–53) than for pathogenic ones (12.0, range 0–42). Moreover, the higher the number of virulence factors within a strain, the lower the repeat content. Additionally, pathogenic strains of distinct ecological niches (i.e., intestinal or extraintestinal) differ in repeat counts. Altogether, these findings support an evolutionary connection between CRISPR and pathogenicity in E. coli. PMID:26136211

  17. Localization of Anionic Phospholipids in Escherichia coli Cells

    PubMed Central

    Oliver, Piercen M.; Crooks, John A.; Leidl, Mathias; Yoon, Earl J.; Saghatelian, Alan

    2014-01-01

    Cardiolipin (CL) is an anionic phospholipid with a characteristically large curvature and is of growing interest for two primary reasons: (i) it binds to and regulates many peripheral membrane proteins in bacteria and mitochondria, and (ii) it is distributed asymmetrically in rod-shaped cells and is concentrated at the poles and division septum. Despite the growing number of studies of CL, its function in bacteria remains unknown. 10-N-Nonyl acridine orange (NAO) is widely used to image CL in bacteria and mitochondria, as its interaction with CL is reported to produce a characteristic red-shifted fluorescence emission. Using a suite of biophysical techniques, we quantitatively studied the interaction of NAO with anionic phospholipids under physiologically relevant conditions. We found that NAO is promiscuous in its binding and has photophysical properties that are largely insensitive to the structure of diverse anionic phospholipids to which it binds. Being unable to rely solely on NAO to characterize the localization of CL in Escherichia coli cells, we instead used quantitative fluorescence microscopy, mass spectrometry, and mutants deficient in specific classes of anionic phospholipids. We found CL and phosphatidylglycerol (PG) concentrated in the polar regions of E. coli cell membranes; depletion of CL by genetic approaches increased the concentration of PG at the poles. Previous studies suggested that some CL-binding proteins also have a high affinity for PG and display a pattern of cellular localization that is not influenced by depletion of CL. Framed within the context of these previous experiments, our results suggest that PG may play an essential role in bacterial physiology by maintaining the anionic character of polar membranes. PMID:25002539

  18. Kinetics of Escherichia coli destruction by microwave irradiation

    SciTech Connect

    Fujikawa, Hiroshi; Ushioda, Hiroshi; Kudo, Yasuo )

    1992-03-01

    The kinetics of destruction of Escherichia coli cells suspended in a solution by microwave irradiation with a microwave oven were studied. During radiation at several powers, the temperature of 0.01 M phosphate buffer (PB), pH 7.0, in a glass beaker increased linearly at a rate of A (degrees Centigrade per second) according to exposure time. When E. coli cells suspended in PB were exposed in the same beaker, the number of viable cells decreased according to the exposure time and the power used. The survival curve was approximated to a set of three linear parts. For each part, a rate constant of destruction (k) and an extrapolated starting temperature (T{sub 0}) at several powers were estimated. Thereafter, the relationships between A and k and between A and T{sub 0} were studied. When a flat petri dish was used, the A value of exposed PB was lower and bacterial destruction was inhibited; the survival curve was similar to a curve predicted from the A value by using the relationships between the parameters. As the concentration of salt in the solution increased (from 0 to 1.35 M), the A value decreased and bacterial destruction was more suppressed. No remarkable difference between the destruction profiles for microwave exposure and conventional heating, which had the potential to generate an equal A value, was detected. These results showed that the parameter A of an irradiated solution is essential when kinetics of bacterial destruction by microwave exposure are studied and that the destruction profile can be interpreted mostly by means of thermal effects.

  19. Fungal ?-1,3-Glucan Increases Ofloxacin Tolerance of Escherichia coli in a Polymicrobial E. coli/Candida albicans Biofilm

    PubMed Central

    De Brucker, Katrijn; Tan, Yulong; Vints, Katlijn; De Cremer, Kaat; Braem, Annabel; Verstraeten, Natalie; Michiels, Jan; Vleugels, Jef; Thevissen, Karin

    2015-01-01

    In the past, biofilm-related research has focused mainly on axenic biofilms. However, in nature, biofilms are often composed of multiple species, and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study, we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm compared to its tolerance in an axenic E. coli biofilm. The increased ofloxacin tolerance of E. coli is mainly biofilm specific, as ofloxacin tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the ?-1,3-glucan-degrading enzyme lyticase. In line with a role for ?-1,3-glucan in mediating ofloxacin tolerance of E. coli in a biofilm, we found that ofloxacin tolerance of E. coli increased even more in E. coli/C. albicans biofilms consisting of a high-?-1,3-glucan-producing C. albicans mutant. In addition, exogenous addition of laminarin, a polysaccharide composed mainly of poly-?-1,3-glucan, to an E. coli biofilm also resulted in increased ofloxacin tolerance. All these data indicate that ?-1,3-glucan from C. albicans increases ofloxacin tolerance of E. coli in an E. coli/C. albicans biofilm. PMID:25753645

  20. Macromolecule Mediated Transport and Retention of Escherichia coli O157:H7 in Saturated Porous Media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The role of extracellular macromolecules on Escherichia coli O157:H7 transport and retention was investigated in saturated porous media. To compare the relative transport and retention of E. coli cells that are macromolecule rich and deficient, macromolecules were partially cleaved using a proteolyt...

  1. Perspectives on super-shedding of Escherichia coli O157:H7 by cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli O157:H7 is a foodborne pathogen that causes illness in humans worldwide. Cattle are the primary reservoir of this bacterium with the concentration and frequency of E. coli O157:H7 shedding varying greatly among individuals. The term “supershedder” has been applied to cattle that sh...

  2. Metabolite profiling of foodborne disease significance – case study Escherichia coli O157

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the United States, Escherichia coli (E. coli) O157 infection, associated with the consumption of contaminated ground beef, has resulted in an unnecessary burden for both the meat industry and the health care system, with meat recalls and often fatal human disease. Cattle, the primary reservoirs f...

  3. R-PLASMID TRANSFER TO AND FROM 'ESCHERICHIA COLI' STRAINS ISOLATED FROM HUMAN FECAL SAMPLES

    EPA Science Inventory

    Strains of Escherichia coli recently isolated from human feces were examined for the frequency with which they accept and R factor (Ri) from a derepressed fi+ strain of E. coli K-12 and transfer it to fecal and laboratory strains. Colicins produced by some of the isolates rapidly...

  4. Variability of Surface Characteristics and Transport Behavior of Escherichia coli Isolates from Different Host

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli is a commonly used indicator organism for detecting the presence of fecal-borne pathogenic microorganisms in water supplies. The importance of E. coli as an indicator organism has led to numerous studies looking at surface characteristics and transport behavior of this important mic...

  5. SURVIVAL OF CAMPYLOBACTER JEJUNI AND ESCHERICHIA COLI IN GROUNDWATER DURING PROLONGED EXPOSURE TO LOW TEMPERATURES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laboratory microcosm experiments were performed to compare the survival behavior of Campylobacter jejuni (C. jejuni), a leading cause of human gastroenteritis worldwide, and Escherichia coli (E. coli), a commonly used bacterial indicator of fecal contamination. Survival studies were carried out by i...

  6. Detection and Recovery of Shiga Toxins and Escherichia Coli O157

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli (STEC) are among the most costly foodborne pathogens. In the United States, recent annual cost estimates for acute care ranged from $1 to $2 billion. These were based on the assumption that E. coli O157:H7 led to 73,000 illnesses and 61 deaths each year. The pa...

  7. Quantification of survival of Escherichia coli 0157:H7 on Plants affected by Contaminated Irrigation Water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Enterohemorrhagic E. coli O157: H7 (EHEC) is a major foodborne pathogen capable of causing diarrhea and vomiting, with further complications such as hemolytic-uremic syndrome (HUS). The aim of this study was to use real-time PCR method to quantify the survival of Escherichia coli O157:H7/pGFP in phy...

  8. Comparative efficacy of five different rep-PCR methods to discriminate Escherichia coli populations in aquatic

    E-print Network

    Mazumder, Asit

    words | DNA fingerprinting, Escherichia coli, (GTG)5-PCR, microbial source tracking, molecular typing-PCR genomic fingerprints of 271 E. coli isolates yielded an average rate of correct classification (watershed; Carson et al. 2003; Johnson et al. 2004; Mohapatra et al. 2007). Rep-PCR is a genotypic fingerprinting

  9. Proliferation of Escherichia coli O157:H7 in soil and hydroponic microgreen production systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Radish (Raphanus sativus var. longipinnatus) microgreens were produced from seeds inoculated with Escherichia coli O157: H7 using soil substitute and hydroponic production systems. E. coli populations on the edible and inedible parts of harvested microgreen plants and in growth medium were examined....

  10. Characterization of Escherichia coli 0157:H7 strains isolated from supershedding cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous reports have indicated that a small proportion of cattle shedding high levels of Escherichia coli O157:H7 is the main source for transmission of this organism between animals. Cattle achieving a fecal shedding status of 10**4 CFU of E. coli O157: H7/gram or greater are now referred to as su...

  11. Escherichia coli Regrowth and Macroinvertebrate Health in Urban and Rural Streams 

    E-print Network

    McCrary, Kathryn Jordan

    2012-07-16

    of indicator bacteria, Escherichia coli. This study collected data on the recovery and regrowth of E. coli by collecting ultraviolet light treated effluent from the Carters Creek WWTP and spiked it with three different concentrations of DOC derived from a leaf...

  12. THE WIDESPREAD OCCURRENCE OF THE ENTEROHEMOLYSIN GENE EHLYA AMONG ENVIRONMENTAL STRAINS OF ESCHERICHIA COLI

    EPA Science Inventory

    The putative virulence factor enterohemolysin, encoded for by the ehlyA gene, has been closely associated with the pathogenic enterohemorrhagic Escherichia coli (EHEC) group. E. coli isolates from effluents from seven geographically dispersed municipal ...

  13. ESCHERICHIA COLI AND TOTAL COLIFORMS IN WATER AND SEDIMENTS AT LAKE MARINAS

    EPA Science Inventory

    Escherichia coli, a fecal coliform, and total coliforms were monitored between September 1999 to October 2001 in five marinas on Lake Texoma, located on the Oklahoma and Texas border. General trend was that densities of E. coli were lower in the summer season due to the lower ...

  14. Evaluation of Select Sensors for Real-Time Monitoring of Escherichia coli in Water Distribution Systems?

    PubMed Central

    Miles, Syreeta L.; Sinclair, Ryan G.; Riley, Mark R.; Pepper, Ian L.

    2011-01-01

    This study evaluated real-time sensing of Escherichia coli as a microbial contaminant in water distribution systems. Most sensors responded to increased E. coli concentrations, showing that select sensors can detect microbial water quality changes and be utilized as part of a contaminant warning system. PMID:21357435

  15. Identification of Escherichia coli O157 by Using a Novel Colorimetric Detection Method with DNA Microarrays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxin-producing Escherichia coli O157:H7 is a leading cause of foodborne illness worldwide. To evaluate better methods to rapidly detect and genotype E. coli O157 strains, the present study evaluated the use of ampliPHOX, a novel colorimetric detection method based on photopolymerization, for...

  16. Efficacy of supercritical carbon dioxide for nonthermal inactivation of Escherichia coli K12 in apple cider

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the efficacy of a supercritical carbon dioxide (SCCO2) system with a gas-liquid porous metal contactor for eliminating Escherichia coli K12 in apple cider. Pasteurized, preservative-free apple cider was inoculated with E. coli K12 and processed using the SCCO2 system at CO2 conc...

  17. Diversity of Cell Properties and Transport Behavior Among 12 Enviromental Escherichia Coli Isolates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli is a commonly used indicator organism for detecting the presence of fecal-borne pathogenic microorganisms in water supplies. The importance of E. coli as an indicator organism has led to numerous studies looking at surface characteristics and transport behavior of this important mi...

  18. Supplementary Information Metabolic engineering of Escherichia coli using synthetic small regulatory RNAs

    E-print Network

    1 Supplementary Information Metabolic engineering of Escherichia coli using synthetic small Supplementary Figure S1: Process for selecting candidate scaffolds from E. coli sRNAs Note Figure .....3 .....3 #12;2 Supplementary Figure S14: Proof-of-concept experiments for the large-scale identification

  19. DETECTION OF ESCHERICHIA COLI IN WATER USING A COLORIMETRIC GENE PROBE ASSAY

    EPA Science Inventory

    A commercially available DNA hydribization assay (Gene-trak , Framingham, MA. USA) was compared with the EC-MUG procedure for the detection of Escherichia coli in water. The gene probe gave positive responses for pure cultures of E. coli 0157:H7, E. fergusonii, Shigella sonnei, S...

  20. ON-CHIP PARALLEL DETECTION OF SHIGA TOXIN PRODUCING ESCHERICHIA COLI USING

    E-print Network

    Bashir, Rashid

    63. Figure1. 6x6 array for on-chip detection of E.coli O157:H7 using LAMP amplification targeting eae and notorious STEC serotype is O157:H7 but other serotypes, like O104:H4 responsible for May 2011 HUS outbreakON-CHIP PARALLEL DETECTION OF SHIGA TOXIN PRODUCING ESCHERICHIA COLI USING LOOP-MEDIATED ISOTHERMAL

  1. Effects of media on recovery of Escherichia coli 0157:H7 and Pseudomonas fluorescens from spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of post-harvest contamination of leafy greens by Escherichia coli O157:H7 is important for food safety. Efficient recovery and enumeration of E. coli O157:H7 and the biocontrol microbe Pseudomonas fluorescens (non-pectolytic and non-plant pathogenic) from produce is crucial for assessment of...

  2. Effects of intravenous Escherichia coli dose on the pathophysiological response of colostrum-fed Jersey calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objectives of the present study were to characterize the dose dependency of an intravenous Escherichia coli (E. coli) challenge in colostrum-fed Jersey calves and to identify biochemical markers indicative of septicemia. Eighteen 3-wk old colostrum-fed Jersey calves were completely randomized to 1 o...

  3. B R I E F R E P O R T Escherichia coli Dysbiosis Correlates

    E-print Network

    Borenstein, Elhanan

    in Children With Cystic Fibrosis Lucas R. Hoffman,1,2,6 Christopher E. Pope,1 Hillary S. Hayden,2 Sonya, suggesting that E. coli could con- tribute to cystic fibrosis gastrointestinal dysfunction. Keywords. cystic fibrosis; microbiota; Escherichia coli; in- flammation; malabsorption. The genetic disease cystic fibrosis

  4. Proteomic analysis reveals protein expression differences in Escherichia coli strains associated with persistent versus transient mastitis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli is a leading cause of bacterial mastitis in dairy cattle. Typically this infection is transient in nature, causing an infection that lasts 2-3 days. However, in a minority of cases, E. coli has been shown to cause a persistent intramammary infection. The mechanisms that allow for...

  5. Effects of media on recovery of Escherichia coli 0157:H7 and Pseudomonas fluorescens from spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control the post-harvest contamination of leafy greens by Escherichia coli O157:H7 is important for food safety. Efficient recovery and enumeration of E. coli O157:H7 and the biocontrol microbe Pseudomonas fluorescens from produce is crucial for assessment of biocontrol efficacy. Sensitive and effec...

  6. FACTORS AFFECTING ATTACHMENT OF ESCHERICHIA COLI O157:H7 TO APPLE TISSUES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Attachment of Escherichia coli O157:H7 and fluorescent microspheres to the stem, calyx sepals, russet and discontinuities on the skin of Golden Delicious apples was investigated. Attachment of the E. coli cells to the stems resulted in their removal from the inoculum solution over time where the ce...

  7. PERSISTENCE OF ESCHERICHIA COLI O157:H7 IN SOIL AFTER FUMIGATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long term persistence of Escherichia coli O157:H7 in soil and in the rhizosphere of many crops is relatively unknown. Many groups have voiced concerns about the safety of land application of manure and the potential for food and water contamination by E. coli O157:H7 from agricultural runoffs. Multi...

  8. Complete Genome Sequences of Two Escherichia coli O145:H28 Outbreak Strains of Food Origin.

    PubMed

    Cooper, Kerry K; Mandrell, Robert E; Louie, Jacqueline W; Korlach, Jonas; Clark, Tyson A; Parker, Craig T; Huynh, Steven; Chain, Patrick S G; Ahmed, Sanaa; Carter, Michelle Qiu

    2014-01-01

    Escherichia coli O145:H28 strain RM12581 was isolated from bagged romaine lettuce during a 2010 U.S. lettuce-associated outbreak. E. coli O145:H28 strain RM12761 was isolated from ice cream during a 2007 ice cream-associated outbreak in Belgium. Here we report the complete genome sequences and annotation of both strains. PMID:24855308

  9. Role of wild birds as carriers of multi-drug resistant Escherichia coli and Escherichia vulneris

    PubMed Central

    Shobrak, Mohammed Y.; Abo-Amer, Aly E.

    2014-01-01

    Emergence and distribution of multi-drug resistant (MDR) bacteria in environments pose a risk to human and animal health. A total of 82 isolates of Escherichia spp. were recovered from cloacal swabs of migrating and non-migrating wild birds. All bacterial isolates were identified and characterized morphologically and biochemically. 72% and 50% of isolates recovered from non-migrating and migrating birds, respectively, showed positive congo red dye binding (a virulence factor). Also, hemolysin production (a virulence factor) was showed in 8% of isolates recovered from non-migrating birds and 75% of isolates recovered from migrating birds. All isolates recovered from non-migrating birds were found resistant to Oxacillin while all isolates recovered from migrating birds demonstrated resistance to Oxacillin, Chloramphenicol, Oxytetracycline and Lincomycin. Some bacterial isolates recovered from non-migrating birds and migrating birds exhibited MDR phenotype. The MDR isolates were further characterized by API 20E and 16S rRNA as E. coli and E. vulneris. MDR Escherichia isolates contain ~1–5 plasmids of high-molecular weights. Accordingly, wild birds could create a potential threat to human and animal health by transmitting MDR bacteria to water streams and other environmental sources through their faecal residues, and to remote regions by migration. PMID:25763023

  10. Torque generated by the flagellar motor of Escherichia coli.

    PubMed Central

    Berg, H C; Turner, L

    1993-01-01

    Cells of the bacterium Escherichia coli were tethered and spun in a high-frequency rotating electric field at a series of discrete field strengths. This was done first at low field strengths, then at field strengths generating speeds high enough to disrupt motor function, and finally at low field strengths. Comparison of the initial and final speed versus applied-torque plots yielded relative motor torque. For backward rotation, motor torque rose steeply at speeds close to zero, peaking, on average, at about 2.2 times the stall torque. For forward rotation, motor torque remained approximately constant up to speeds of about 60% of the zero-torque speed. Then the torque dropped linearly with speed, crossed zero, and reached a minimum, on average, at about -1.7 times the stall torque. The zero-torque speed increased with temperature (about 90 Hz at 11 degrees C, 140 Hz at 16 degrees C, and 290 Hz at 23 degrees C), while other parameters remained approximately constant. Sometimes the motor slipped at either extreme (delivered constant torque over a range of speeds), but eventually it broke. Similar results were obtained whether motors broke catastrophically (suddenly and completely) or progressively or were de-energized by brief treatment with an uncoupler. These results are consistent with a tightly coupled ratchet mechanism, provided that elastic deformation of force-generating elements is limited by a stop and that mechanical components yield at high applied torques. PMID:8298044

  11. Improving heterologous polyketide production in Escherichia coli by transporter engineering.

    PubMed

    Yang, Jingya; Xiong, Zhi-Qiang; Song, Shu-Jie; Wang, Jian-Feng; Lv, Hua-Jun; Wang, Yong

    2015-10-01

    Expelling heterologous compounds out of hosts by transporters is a potential strategy to enhance product titers in microbial cell factories. In this work, to increase heterologous polyketide 6-deoxyerythronolide B (6dEB, erythromycin precursor) production, tripartite multidrug efflux pumps MacAB-TolC, AcrAB-TolC, MdtEF-TolC, and MexAB-OprM were modulated in a 6dEB production strain. Compared with the control, overexpression of a single component of efflux pumps (except oprM) repressed 6dEB production, but modulation of two components MacA and MacB or the complete pumps MacAB-TolC and MdtEF-TolC significantly improved 6dEB titer by 100 ± 11, 118 ± 54, and 98 ± 12 %, respectively. In addition, to avoid the challenging fine-tuning components of pumps, the transcriptional regulators of efflux pumps were modulated to improve the 6dEB production. Overexpression of RpoH (activator of MdtEF-TolC) and EvgA (activator of EmrKY-TolC and AcrAD-TolC) strongly increased 6dEB titer by 152 ± 54 and 142 ± 85 %, respectively. This is the first report of transporter engineering for improving heterologous polyketide production in Escherichia coli. Our results provide an effective strategy for improving the yield of the heterologous products in chassis cell. PMID:26062534

  12. Importance of Multiple Methylation Sites in Escherichia coli Chemotaxis

    PubMed Central

    Sourjik, Victor

    2015-01-01

    Bacteria navigate within inhomogeneous environments by temporally comparing concentrations of chemoeffectors over the course of a few seconds and biasing their rate of reorientations accordingly, thereby drifting towards more favorable conditions. This navigation requires a short-term memory achieved through the sequential methylations and demethylations of several specific glutamate residues on the chemotaxis receptors, which progressively adjusts the receptors’ activity to track the levels of stimulation encountered by the cell with a delay. Such adaptation also tunes the receptors’ sensitivity according to the background ligand concentration, enabling the cells to respond to fractional rather than absolute concentration changes, i.e. to perform logarithmic sensing. Despite the adaptation system being principally well understood, the need for a specific number of methylation sites remains relatively unclear. Here we systematically substituted the four glutamate residues of the Tar receptor of Escherichia coli by non-methylated alanine, creating a set of 16 modified receptors with a varying number of available methylation sites and explored the effect of these substitutions on the performance of the chemotaxis system. Alanine substitutions were found to desensitize the receptors, similarly but to a lesser extent than glutamate methylation, and to affect the methylation and demethylation rates of the remaining sites in a site-specific manner. Each substitution reduces the dynamic range of chemotaxis, by one order of magnitude on average. The substitution of up to two sites could be partly compensated by the adaptation system, but the full set of methylation sites was necessary to achieve efficient logarithmic sensing. PMID:26683829

  13. Massive Diversification in Aging Colonies of Escherichia coli

    PubMed Central

    Saint-Ruf, Claude; Garfa-Traoré, Meriem; Collin, Valérie; Cordier, Corinne; Franceschi, Christine

    2014-01-01

    The evolutionary success of bacteria depends greatly on their capacity to continually generate phenotypic diversity. Structured environments are particularly favorable for diversification because of attenuated clonal interference, which renders selective sweeps nearly impossible and enhances opportunities for adaptive radiation. We examined at the microscale level the emergence and the spatial and temporal dynamics of phenotypic diversity and their underlying causes in Escherichia coli colonies. An important dynamic heterogeneity in the growth, metabolic activity, morphology, gene expression patterns, stress response induction, and death patterns among cells within colonies was observed. Genetic analysis indicated that the phenotypic variation resulted mostly from mutations and that indole production, oxidative stress, and the RpoS-regulated general stress response played an important role in the generation of diversity. We observed the emergence and persistence of phenotypic variants within single colonies that exhibited variable fitness compared to the parental strain. Some variants showed improved capacity to produce biofilms, whereas others were able to use different nutrients or to tolerate antibiotics or oxidative stress. Taken together, our data show that bacterial colonies provide an ecological opportunity for the generation and maintenance of vast phenotypic diversity, which may increase the probability of population survival in unpredictable environments. PMID:24982303

  14. Metabolic engineering of Escherichia coli to improve recombinant protein production.

    PubMed

    Liu, Min; Feng, Xinjun; Ding, Yamei; Zhao, Guang; Liu, Huizhou; Xian, Mo

    2015-12-01

    Escherichia coli is one of the most widely used strains for recombinant protein production. However, obstacles also exist in both academic researches and industrial applications, such as the metabolic burden, the carbon source waste, and the cells' physiological deterioration. This article reviews recent approaches for improving recombinant protein production in metabolic engineering, including workhorse selection, stress factor application, and carbon flux regulation. Selecting a suitable host is the first key point for recombinant protein production. In general, it all depends on characteristics of the strains and the target proteins. It will be triggered cells physiological deterioration when the medium is significantly different from the cell's natural environment. Coexpression of stress factors can help proteins to fold into their native conformation. Carbon flux regulation is a direct approach for redirecting more carbon flux toward the desirable pathways and products. However, some undesirable consequences are usually found in metabolic engineering, such as glucose transport inhibition, cell growth retardation, and useless metabolite accumulation. More efficient regulators and platform cell factories should be explored to meet a variety of production demands. PMID:26399416

  15. Swimming patterns and dynamics of simulated Escherichia coli bacteria

    PubMed Central

    Zonia, Laura; Bray, Dennis

    2009-01-01

    A spatially and temporally realistic simulation of Escherichia coli chemotaxis was used to investigate the swimming patterns of wild-type and mutant bacteria within a rectangular arena in response to chemoattractant gradients. Swimming dynamics were analysed during long time series with phase-space trajectories, power spectra and estimations of fractal dimensions (FDs). Cell movement displayed complex trajectories in the phase space owing to interaction of multiple attractors that captured runs and tumbles. Deletion of enzymes responsible for adaptation (CheR and CheB) restricted the pattern of bacterial swimming in the absence of a gradient. In the presence of a gradient, there was a strong increase in trajectories arising from runs and attenuation of those arising from tumbles. Similar dynamics were observed for mutants lacking CheY, which are unable to tumble. The deletion of CheR, CheB and CheY also caused significant shifts in chemotaxis spectral frequencies. Rescaled range analysis and estimation of FD suggest that wild-type bacteria display characteristics of fractional Brownian motion with positive correlation between past and future events. These results reveal an underlying order in bacterial swimming dynamics, which enables a chemotactic search strategy conforming to a fractal walk. PMID:19324687

  16. Biosynthesis of novel thermoplastic polythioesters by engineered Escherichia coli

    NASA Astrophysics Data System (ADS)

    Lütke-Eversloh, Tina; Fischer, Andreas; Remminghorst, Uwe; Kawada, Jumpei; Marchessault, Robert H.; Bögershausen, Ansgar; Kalwei, Martin; Eckert, Hellmut; Reichelt, Rudolf; Liu, Shuang-Jiang; Steinbüchel, Alexander

    2002-12-01

    The development of non-petrochemical sources for the plastics industry continues to progress as large multinationals focus on renewable resources to replace fossil carbon. Many bacteria are known to accumulate polyoxoesters as water-insoluble granules in the cytoplasm. The thermoplastic and/or elastomeric behaviour of these biodegradable polymers holds promise for the development of various technological applications. Here, we report the synthesis and characterization of microbial polythioesters (PTEs), a novel class of biopolymers of general technological relevance. Biosynthesis of PTE homopolymers was achieved using a recombinant strain of Escherichia coli that expressed a non-natural pathway consisting of a butyrate kinase, a phosphotransbutyrylase, and a PHA synthase. Different homopolymers were produced, consisting of either 3-mercaptopropionate, 3-mercaptobutyrate, or 3-mercaptovalerate repeating units, if the respective mercaptoalkanoic acids were provided as precursor substrates to the fermentative process. The PTEs contributed up to 30% (w/w) of the cellular dry weight and were identified as hydrophobic inclusions in the cytoplasm. The chemical and stereochemical homogeneity of the purified PTEs were identified by different methods, and the estimated physical properties were compared to the oxypolyester equivalents, revealing low crystalline order and, for the poly(3-mercaptopropionate) improved thermal stability. The ability to produce PTEs through a biosynthetic route opens up new avenues in the field of biomaterials.

  17. Production of fusion mussel adhesive fp-353 in Escherichia coli.

    PubMed

    Gim, Youngsoo; Hwang, Dong Soo; Lim, Seonghye; Song, Young Hoon; Cha, Hyung Joon

    2008-01-01

    Mussel adhesive proteins (MAPs) have a potential as environmentally friendly adhesives for use under aqueous conditions. MAPs maybe of particular value in medical applications. We previously reported the functional expression of recombinant foot protein type 5 (fp-5) and foot protein type 3A (fp-3A), both of which have significant adhesion abilities, in Escherichia coli. However, these proteins were produced at low levels because of post-induction cell growth inhibition, and the proteins showed poor post-purification solubility. Here, we design and produce a new type of recombinant MAP, fp-353, that is a fusion protein with fp-3A at each terminus of fp-5. Because fp-353 formed inclusion bodies, host cell growth inhibition did not occur. In addition, the solubility of MAP fp-353 after purification was significantly enhanced, permitting the preparation of a viscous concentrated glue solution for large-scale adhesion strength measurements. Together with large-scale cowhide adhesion measurements and cell-adhesion analyses, we successfully demonstrated that fusion mussel protein fp-353 has potential as a practical alternative bioadhesive. PMID:19194941

  18. Expression of enterotoxigenic Escherichia coli colonization factors in Vibrio cholerae.

    PubMed

    Favre, Didier; Lüdi, Stefan; Stoffel, Michael; Frey, Joachim; Horn, Michael P; Dietrich, Guido; Spreng, Simone; Viret, Jean-François

    2006-05-15

    As a first step towards a vaccine against diarrhoeal disease caused by enterotoxigenic Escherichia coli (ETEC), we have studied the expression of several ETEC antigens in the live attenuated Vibrio cholerae vaccine strain CVD 103-HgR. Colonization factors (CF) CFA/I, CS3, and CS6 were expressed at the surface of V. cholerae CVD 103-HgR. Both CFA/I and CS3 required the co-expression of a positive regulator for expression, while CS6 was expressed without regulation. Up-regulation of CF expression in V. cholerae was very efficient, so that high amounts of CFA/I and CS3 similar to those in wild-type ETEC were synthesized from chromosomally integrated CF and positive regulator loci. Increasing either the operon and/or the positive regulator gene dosage resulted in only a small increase in CFA/I and CS3 expression. In contrast, the level of expression of the non-regulated CS6 fimbriae appeared to be more dependent on gene dosage. While CF expression in wild-type ETEC is known to be tightly thermoregulated and medium dependent, it seems to be less stringent in V. cholerae. Finally, co-expression of two or three CFs in the same strain was efficient even under the control of one single regulator gene. PMID:16581160

  19. The Transcription Unit Architecture of the Escherichia Coli Genome

    SciTech Connect

    Cho, Byung-Kwan; Zengler, Karsten; Qiu, Yu; Park, Young S.; Knight, Eric M.; Barrett, Christian; Gao, Yuan; Palsson, Bernhard O.

    2009-11-30

    Under EMSL User Proposal 25660, the authors reported that bacterial genomes are organized by structural and functional elements, including promoters, transcription start and termination sites, open reading frames, regulatory noncoding regions, untranslated regions and transcription units. Here, we iteratively integrate high-throughput, genome-wide measurements of RNA polymerase binding locations and mRNA transcript abundance, 5? sequences and translation into proteins to determine the organizational structure of the Escherichia coli K-12 MG1655 genome. Integration of the organizational elements provides an experimentally annotated transcription unit architecture, including alternative transcription start sites, 5? untranslated region, boundaries and open reading frames of each transcription unit. A total of 4,661 transcription units were identified, representing an increase of >530% over current knowledge. This comprehensive transcription unit architecture allows for the elucidation of condition-specific uses of alternative sigma factors at the genome scale. Furthermore, the transcription unit architecture provides a foundation on which to construct genome-scale transcriptional and translational regulatory networks.

  20. Poly-3-hydroxybutyrate Synthase from the Periplasm of Escherichia coli

    PubMed Central

    Dai, Dongsheng; Reusch, Rosetta N.

    2010-01-01

    This is the first report of a poly-3-hydroxybutyrate (PHB) synthase in Escherichia coli. The enzyme was isolated from the periplasm using ammonium sulfate fractionation, hydrophobic, and size-exclusion chromatography and identified by LC/MS/MS as YdcS, a component of a putative ABC transporter. Green Fluorescent Protein-tagged ydcS, purified by 2D native gel electrophoresis, also exhibited PHB synthase activity. Optimal conditions for enzyme activity were 37 °C, pH 6.8–7.5, 100 mM KCl. Km was 0.14 mM and Vmax was 18.7 nmol/mg protein/min. The periplasms of deletion mutants displayed <25% of the activity of the parent strain. Deletion mutants exhibited ~25% less growth in M9 medium, glucose, and contained ~30% less PHB complexed to proteins (cPHB) in the outer membranes, but the same concentration of chloroform-extractable PHB as wild-type cells. The primary sequence of YdcS suggests it may belong to the alpha/beta hydrolase superfamily which includes polyhydroxybutyrate (PHB) synthases, lipases and esterases. PMID:18640095

  1. Expression of fully functional tetrameric human hemoglobin in Escherichia coli

    SciTech Connect

    Hoffman, S.J.; Looker, D.L.; Roehrich, J.M.; Cozart, P.E.; Durfee, S.L.; Tedesco, J.L.; Stetler, G.L. )

    1990-11-01

    Synthesis genes encoding the human {alpha}- and {beta}-globin polypeptides have been expressed from a single operon in Escherichia coli. The {alpha}- and {beta}-globin polypeptides associate into soluble tetramers, incorporate heme, and accumulate to >5% of the total cellular protein. Purified recombinant hemoglobin has the correct stoichiometry of {alpha}- and {beta}-globin chains and contains a full complement of heme. Each globin chain also contains an additional methionine as an extension to the amino terminus. The recombinant hemoglobin has a C{sub 4} reversed-phase HPLC profile essentially identical to that of human hemoglobin A{sub 0} and comigrates with hemoglobin A{sub 0} on SDS/PAGE. The visible spectrum and oxygen affinity are similar to that of native human hemoglobin A{sub 0}. The authors have also expressed the {alpha}- and {beta}-globin genes separately and found that the expression of the {alpha}-globin gene alone results in a marked decrease in the accumulation of {alpha}-globin in the cell. Separate expression of the {beta}-globin gene results in high levels of insoluble {beta}-globin. These observations suggest that the presence of {alpha}- and {beta}-globin in the same cell stabilizes {alpha}-globin and aids the correct folding of {beta}-globin. This system provides a simple method for expressing large quantities of recombinant hemoglobin and allows facile manipulation of the genes encoding hemoglobin to produce functionally altered forms of this protein.

  2. Production of salidroside in metabolically engineered Escherichia coli

    PubMed Central

    Bai, Yanfen; Bi, Huiping; Zhuang, Yibin; Liu, Chang; Cai, Tao; Liu, Xiaonan; Zhang, Xueli; Liu, Tao; Ma, Yanhe

    2014-01-01

    Salidroside (1) is the most important bioactive component of Rhodiola (also called as “Tibetan Ginseng”), which is a valuable medicinal herb exhibiting several adaptogenic properties. Due to the inefficiency of plant extraction and chemical synthesis, the supply of salidroside (1) is currently limited. Herein, we achieved unprecedented biosynthesis of salidroside (1) from glucose in a microorganism. First, the pyruvate decarboxylase ARO10 and endogenous alcohol dehydrogenases were recruited to convert 4-hydroxyphenylpyruvate (2), an intermediate of L-tyrosine pathway, to tyrosol (3) in Escherichia coli. Subsequently, tyrosol production was improved by overexpressing the pathway genes, and by eliminating competing pathways and feedback inhibition. Finally, by introducing Rhodiola-derived glycosyltransferase UGT73B6 into the above-mentioned recombinant strain, salidroside (1) was produced with a titer of 56.9?mg/L. Interestingly, the Rhodiola-derived glycosyltransferase, UGT73B6, also catalyzed the attachment of glucose to the phenol position of tyrosol (3) to form icariside D2 (4), which was not reported in any previous literatures. PMID:25323006

  3. Functioning of a metabolic flux sensor in Escherichia coli.

    PubMed

    Kochanowski, Karl; Volkmer, Benjamin; Gerosa, Luca; Haverkorn van Rijsewijk, Bart R; Schmidt, Alexander; Heinemann, Matthias

    2013-01-15

    Regulation of metabolic operation in response to extracellular cues is crucial for cells' survival. Next to the canonical nutrient sensors, which measure the concentration of nutrients, recently intracellular "metabolic flux" was proposed as a novel impetus for metabolic regulation. According to this concept, cells would have molecular systems ("flux sensors") in place that regulate metabolism as a function of the actually occurring metabolic fluxes. Although this resembles an appealing concept, we have not had any experimental evidence for the existence of flux sensors and also we have not known how these flux sensors would work in detail. Here, we show experimental evidence that supports the hypothesis that Escherichia coli is indeed able to measure its glycolytic flux and uses this signal for metabolic regulation. Combining experiment and theory, we show how this flux-sensing function could emerge from an aggregate of several molecular mechanisms: First, the system of reactions of lower glycolysis and the feedforward activation of fructose-1,6-bisphosphate on pyruvate kinase translate flux information into the concentration of the metabolite fructose-1,6-bisphosphate. The interaction of this "flux-signaling metabolite" with the transcription factor Cra then leads to flux-dependent regulation. By responding to glycolytic flux, rather than to the concentration of individual carbon sources, the cell may minimize sensing and regulatory expenses. PMID:23277571

  4. An Integrated System for Precise Genome Modification in Escherichia coli

    PubMed Central

    Tas, Huseyin; Nguyen, Cac T.; Patel, Ravish; Kim, Neil H.; Kuhlman, Thomas E.

    2015-01-01

    We describe an optimized system for the easy, effective, and precise modification of the Escherichia coli genome. Genome changes are introduced first through the integration of a 1.3 kbp Landing Pad consisting of a gene conferring resistance to tetracycline (tetA) or the ability to metabolize the sugar galactose (galK). The Landing Pad is then excised as a result of double-strand breaks by the homing endonuclease I-SceI, and replaced with DNA fragments bearing the desired change via ?-Red mediated homologous recombination. Repair of the double strand breaks and counterselection against the Landing Pad (using NiCl2 for tetA or 2-deoxy-galactose for galK) allows the isolation of modified bacteria without the use of additional antibiotic selection. We demonstrate the power of this method to make a variety of genome modifications: the exact integration, without any extraneous sequence, of the lac operon (~6.5 kbp) to any desired location in the genome and without the integration of antibiotic markers; the scarless deletion of ribosomal rrn operons (~6 kbp) through either intrachromosomal or oligonucleotide recombination; and the in situ fusion of native genes to fluorescent reporter genes without additional perturbation. PMID:26332675

  5. Spectrum of cisplatin-induced mutations in Escherichia coli

    SciTech Connect

    Burnouf, D.; Duane, M.; Fuchs, R.P.

    1987-06-01

    Using a forward-mutation assay based on the inactivation of the tetracycline-resistance gene located on plasmid pBR322, we have determined the mutation spectrum induced in Escherichia coli by cisplatin (cis-diamminedichloroplatinum(II)), a widely used antitumor drug. Cisplatin is known to form mainly intrastrand diadducts at ApG and GpG sites. We found that cisplatin efficiently induces mutations in an SOS-dependent way (i.e., dependent upon UV irradiation of the host bacteria). More than 90% of the mutations are single-base-pair substitutions occurring at the potential sites of cisplatin adducts (ApG and GpG). Taking into account the relative proportions of ApG and GpG adducts, we found that the ApG adducts are at least 5 times more mutagenic than the GpG adducts. Moreover, a strong mutation specificity was seen at the 5' side of the ApG adducts (A X T----T X A transversions). The observation that most mutations occur at the 5' end of the adduct at both ApG and GpG sites is discussed in relation to recent structural data.

  6. Iron induces bimodal population development by Escherichia coli

    PubMed Central

    DePas, William H.; Hufnagel, David A.; Lee, John S.; Blanco, Luz P.; Bernstein, Hans C.; Fisher, Steve T.; James, Garth A.; Stewart, Philip S.; Chapman, Matthew R.

    2013-01-01

    Bacterial biofilm formation is a complex developmental process involving cellular differentiation and the formation of intricate 3D structures. Here we demonstrate that exposure to ferric chloride triggers rugose biofilm formation by the uropathogenic Escherichia coli strain UTI89 and by enteric bacteria Citrobacter koseri and Salmonella enterica serovar typhimurium. Two unique and separable cellular populations emerge in iron-triggered, rugose biofilms. Bacteria at the air–biofilm interface express high levels of the biofilm regulator csgD, the cellulose activator adrA, and the curli subunit operon csgBAC. Bacteria in the interior of rugose biofilms express low levels of csgD and undetectable levels of matrix components curli and cellulose. Iron activation of rugose biofilms is linked to oxidative stress. Superoxide generation, either through addition of phenazine methosulfate or by deletion of sodA and sodB, stimulates rugose biofilm formation in the absence of high iron. Additionally, overexpression of Mn-superoxide dismutase, which can mitigate iron-derived reactive oxygen stress, decreases biofilm formation in a WT strain upon iron exposure. Not only does reactive oxygen stress promote rugose biofilm formation, but bacteria in the rugose biofilms display increased resistance to H2O2 toxicity. Altogether, we demonstrate that iron and superoxide stress trigger rugose biofilm formation in UTI89. Rugose biofilm development involves the elaboration of two distinct bacterial populations and increased resistance to oxidative stress. PMID:23359678

  7. Iron induces bimodal population development by Escherichia coli.

    PubMed

    DePas, William H; Hufnagel, David A; Lee, John S; Blanco, Luz P; Bernstein, Hans C; Fisher, Steve T; James, Garth A; Stewart, Philip S; Chapman, Matthew R

    2013-02-12

    Bacterial biofilm formation is a complex developmental process involving cellular differentiation and the formation of intricate 3D structures. Here we demonstrate that exposure to ferric chloride triggers rugose biofilm formation by the uropathogenic Escherichia coli strain UTI89 and by enteric bacteria Citrobacter koseri and Salmonella enterica serovar typhimurium. Two unique and separable cellular populations emerge in iron-triggered, rugose biofilms. Bacteria at the air-biofilm interface express high levels of the biofilm regulator csgD, the cellulose activator adrA, and the curli subunit operon csgBAC. Bacteria in the interior of rugose biofilms express low levels of csgD and undetectable levels of matrix components curli and cellulose. Iron activation of rugose biofilms is linked to oxidative stress. Superoxide generation, either through addition of phenazine methosulfate or by deletion of sodA and sodB, stimulates rugose biofilm formation in the absence of high iron. Additionally, overexpression of Mn-superoxide dismutase, which can mitigate iron-derived reactive oxygen stress, decreases biofilm formation in a WT strain upon iron exposure. Not only does reactive oxygen stress promote rugose biofilm formation, but bacteria in the rugose biofilms display increased resistance to H(2)O(2) toxicity. Altogether, we demonstrate that iron and superoxide stress trigger rugose biofilm formation in UTI89. Rugose biofilm development involves the elaboration of two distinct bacterial populations and increased resistance to oxidative stress. PMID:23359678

  8. Chromosome Structuring Limits Genome Plasticity in Escherichia coli

    PubMed Central

    Espéli, Olivier; Boccard, Frédéric

    2007-01-01

    Chromosome organizations of related bacterial genera are well conserved despite a very long divergence period. We have assessed the forces limiting bacterial genome plasticity in Escherichia coli by measuring the respective effect of altering different parameters, including DNA replication, compositional skew of replichores, coordination of gene expression with DNA replication, replication-associated gene dosage, and chromosome organization into macrodomains. Chromosomes were rearranged by large inversions. Changes in the compositional skew of replichores, in the coordination of gene expression with DNA replication or in the replication-associated gene dosage have only a moderate effect on cell physiology because large rearrangements inverting the orientation of several hundred genes inside a replichore are only slightly detrimental. By contrast, changing the balance between the two replication arms has a more drastic effect, and the recombinational rescue of replication forks is required for cell viability when one of the chromosome arms is less than half than the other one. Macrodomain organization also appears to be a major factor restricting chromosome plasticity, and two types of inverted configurations severely affect the cell cycle. First, the disruption of the Ter macrodomain with replication forks merging far from the normal replichore junction provoked chromosome segregation defects. The second major problematic configurations resulted from inversions between Ori and Right macrodomains, which perturb nucleoid distribution and early steps of cytokinesis. Consequences for the control of the bacterial cell cycle and for the evolution of bacterial chromosome configuration are discussed. PMID:18085828

  9. Control site location and transcriptional regulation in Escherichia coli.

    PubMed Central

    Collado-Vides, J; Magasanik, B; Gralla, J D

    1991-01-01

    The regulatory regions for 119 Escherichia coli promoters have been analyzed, and the locations of the regulatory sites have been cataloged. The following observations emerge. (i) More than 95% of promoters are coregulated with at least one other promoter. (ii) Virtually all sigma 70 promoters contain at least one regulatory site in a proximal position, touching at least position -65 with respect to the start point of transcription. There are not yet clear examples of upstream regulation in the absence of a proximal site. (iii) Operators within regulons appear in very variable proximal positions. By contrast, the proximal activation sites of regulons are much more fixed. (iv) There is a forbidden zone for activation elements downstream from approximately position -20 with respect to the start of transcription. By contrast, operators can occur throughout the proximal region. When activation elements appear in the forbidden zone, they repress. These latter examples usually involve autoregulation. (v) Approximately 40% of repressible promoters contain operator duplications. These occur either in certain regulons where duplication appears to be a requirement for repressor action or in promoters subject to complex regulation. (vi) Remote operator duplications occur in approximately 10% of repressible promoters. They generally appear when a multiple promoter region is coregulated by cyclic AMP receptor protein. (vii) Sigma 54 promoters do not require proximal or precisely positioned activator elements and are not generally subject to negative regulation. Rationales are presented for all of the above observations. PMID:1943993

  10. Influence of DNA geometry on transcriptional activation in Escherichia coli.

    PubMed Central

    Déthiollaz, S; Eichenberger, P; Geiselmann, J

    1996-01-01

    Transcription from many Escherichia coli promoters can be activated by the cAMP-CRP complex bound at different locations upstream of the promoter. At some locations the mechanism of activation involves direct protein-protein contacts between CRP and the RNA polymerase. We positioned the CRP binding site at various distances from the transcription start site of the malT promoter and measured the in vivo activities of these promoter variants. From the activation profiles we deduce that the protein-protein interactions involved in transcriptional activation are rather rigid. A heterologous protein (IHF) that bends the DNA to a similar degree as does CRP activates transcription when bound at sites equivalent to activating positions for CRP. DNA geometry makes a major contribution to the process of transcriptional activation and DNA upstream of the activator binding site participates in this process. Removal of this DNA decreases the capacity of the malT promoter to be activated by CRP in vitro. We conclude that both DNA topology and direct protein-protein contacts contribute to transcriptional activation and that the relative importance of these two modes of activation depends on the nature of the activator and on the location of the activator binding site. Images PMID:8895588

  11. Expression of the Escherichia coli dnaX gene.

    PubMed Central

    Chen, K S; Saxena, P; Walker, J R

    1993-01-01

    The Escherichia coli dnaX gene encodes both the tau and gamma subunits of DNA polymerase III. This gene is located immediately downstream of the adenine salvage gene apt and upstream of orf12-recR, htpG, and adk. The last three are involved in recombination, heat shock, and nucleotide biosynthesis, respectively. apt, dnaX, and orf12-recR all have separate promoters, and the first two are expressed predominantly from those separate promoters. However, use of an RNase E temperature-sensitive mutant allowed the detection of lesser amounts of polycistronic messengers extending from both the apt and dnaX promoters through htpG. Interestingly, transcription of the weak dnaX promoter is stimulated 4- to 10-fold by a sequence contained entirely within the dnaX reading frame. This region has been localized; at least a portion of the sequence (and perhaps the entire sequence) is located within a 31-bp region downstream of the dnaX promoter. Images PMID:7691799

  12. Adenylate Energy Charge in Escherichia coli During Growth and Starvation

    PubMed Central

    Chapman, Astrid G.; Fall, Lana; Atkinson, Daniel E.

    1971-01-01

    The value of the adenylate energy charge, [(adenosine triphosphate) + ½ (adenosine diphosphate)]/[(adenosine triphosphate) + (adenosine diphosphate) + (adenosine monophosphate)], in Escherichia coli cells during growth is about 0.8. During the stationary phase after cessation of growth, or during starvation in carbon-limited cultures, the energy charge declines slowly to a value of about 0.5, and then falls more rapidly. During the slow decline in energy charge, all the cells are capable of forming colonies, but a rapid fall in viability coincides with the steep drop in energy charge. These results suggest that growth can occur only at energy charge values above about 0.8, that viability is maintained at values between 0.8 and 0.5, and that cells die at values below 0.5. Tabulation of adenylate concentrations previously reported for various organisms and tissues supports the prediction, based on enzyme kinetic observations in vitro, that the energy charge is stabilized near 0.85 in intact metabolizing cells of a wide variety of types. PMID:4333317

  13. Characterization of avian pathogenic Escherichia coli isolated in eastern China.

    PubMed

    Dou, Xinhong; Gong, Jiansen; Han, Xiangan; Xu, Ming; Shen, Haiyu; Zhang, Di; Zhuang, Linlin; Liu, Jiasheng; Zou, Jianmin

    2016-01-15

    In order to investigate the biological characteristics of avian pathogenic Escherichia coli (APEC) isolated in eastern China, a total of 243 isolates were isolated from diseased poultry on different farms during the period from 2007 to 2014. These isolates were characterized for serogroups (polymerase chain reaction and agglutination), the presence of virulence-associated genes (fimC, iss, ompA, fyuA, stx2f, iroC, iucD, hlyE, tsh, cvaC, irp2, and papC) and class I integrons (polymerase chain reaction), drug susceptibilities (disk diffusion method) and the biofilm-forming abilities (semi-quantitative method). The results showed that the most predominant serogroups were O78 (87 isolates, 35.8%) and O2 (35 isolates, 14.4%). Gene profiling found that fimC and ompA were frequently distributed among the isolates and that 77.4% of the isolates were positive for class 1 integrons. Overall, isolates displayed resistance to tetracycline (97.5%), nalidixic acid (82.3%), ampicillin (81.1%), sulphafurazole (80.7%), streptomycin (79.0%), trimethoprim (78.2%) and cotrimoxazole (78.2%). Multiple-drug resistance was exhibited in 80.3% of the isolates, and the presence of class 1 integrons is associated with multidrug resistance. Finally, 151 isolates had the ability to form biofilms in vitro, and drug resistance seemed relative to biofilm-forming abilities. PMID:26475938

  14. Complex patterns formed by motile cells of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Budrene, Elena O.; Berg, Howard C.

    1991-02-01

    WHEN chemotactic strains of the bacterium Escherichia coli are inoculated on semi-solid agar containing mixtures of amino acids or sugars, the cells swarm outwards in a series of concentric rings: they respond to spatial gradients of attractants generated by uptake and catabolism1-3. Cells also drift up gradients generated artificially, for example by diffusion from the tip of a capillary tube4 or by mixing5. Here we describe conditions under which cells aggregate in response to gradients of attractant which they excrete themselves. When cells are grown in semi-solid agar on intermediates of the tricarboxylic acid cycle, they form symmetrical arrays of spots or stripes that arise sequentially. When cells in a thin layer of liquid culture are exposed to these compounds, spots appear synchronously, more randomly arrayed. In either case, the patterns are stationary. The attractant is a chemical sensed by the aspartate receptor. Its excretion can be triggered by oxidative stress. As oxygen is limiting at high cell densities, aggregation might serve as a mechanism for collective defence.

  15. Transcription induces gyration of the DNA template in Escherichia coli.

    PubMed Central

    Figueroa, N; Bossi, L

    1988-01-01

    We show that transcription modulation of a plasmid sequence in exponentially growing Escherichia coli cells leads to a rapid change in the linking number of plasmid DNA. Activation of transcription is accompanied by an increase in the plasmid's level of negative supercoiling. The added superhelical turns, whose number is proportional to the strength of the promoter and to the length of the transcript, are promptly removed when transcription is turned off. The transcription-induced increase of template supercoiling can still be detected in the presence of an inhibitor of ATP-dependent DNA gyrase [DNA topoisomerase (ATP-hydrolyzing), EC 5.99.1.3]. Altogether, our results indicate that, in addition to being under a general control, DNA superhelicity can be modulated locally in response to the topological perturbations associated with DNA tracking processes. We discuss a model in which supercoiling changes are produced by differential swiveling activities on the opposite sides of a transcriptional flow during transcriptional modulation. Images PMID:2849103

  16. Penicillin-binding site on the Escherichia coli cell envelope

    SciTech Connect

    Amaral, L.; Lee, Y.; Schwarz, U.; Lorian, V.

    1986-08-01

    The binding of /sup 35/S-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. Experiments distinguishing the effect of pH on penicillin binding by PBP 5/6 from its effect on beta-lactamase activity indicated that although substantial binding occurred at the lowest pH, the amount of binding increased with pH, reaching a maximum at pH 10. Based on earlier studies, it is proposed that the binding at high pH involves the formation of a covalent bond between the C-7 of penicillin and free epsilon amino groups of the PBPs. At pHs ranging from 4 to 8, position 1 of penicillin, occupied by sulfur, is considered to be the site that establishes a covalent bond with the sulfhydryl groups of PBP 5. The use of specific blockers of free epsilon amino groups or sulfhydryl groups indicated that wherever the presence of each had little or no effect on the binding of penicillin by PBP 5, the presence of both completely prevented binding. The specific blocker of the hydroxyl group of serine did not affect the binding of penicillin.

  17. Conformational Dynamics of DNA Repair by Escherichia coli Endonuclease III.

    PubMed

    Kuznetsov, Nikita A; Kladova, Olga A; Kuznetsova, Alexandra A; Ishchenko, Alexander A; Saparbaev, Murat K; Zharkov, Dmitry O; Fedorova, Olga S

    2015-06-01

    Escherichia coli endonuclease III (Endo III or Nth) is a DNA glycosylase with a broad substrate specificity for oxidized or reduced pyrimidine bases. Endo III possesses two types of activities: N-glycosylase (hydrolysis of the N-glycosidic bond) and AP lyase (elimination of the 3'-phosphate of the AP-site). We report a pre-steady-state kinetic analysis of structural rearrangements of the DNA substrates and uncleavable ligands during their interaction with Endo III. Oligonucleotide duplexes containing 5,6-dihydrouracil, a natural abasic site, its tetrahydrofuran analog, and undamaged duplexes carried fluorescent DNA base analogs 2-aminopurine and 1,3-diaza-2-oxophenoxazine as environment-sensitive reporter groups. The results suggest that Endo III induces several fast sequential conformational changes in DNA during binding, lesion recognition, and adjustment to a catalytically competent conformation. A comparison of two fluorophores allowed us to distinguish between the events occurring in the damaged and undamaged DNA strand. Combining our data with the available structures of Endo III, we conclude that this glycosylase uses a multistep mechanism of damage recognition, which likely involves Gln(41) and Leu(81) as DNA lesion sensors. PMID:25869130

  18. Escherichia coli mutants resistant to inactivation by high hydrostatic pressure.

    PubMed Central

    Hauben, K J; Bartlett, D H; Soontjens, C C; Cornelis, K; Wuytack, E Y; Michiels, C W

    1997-01-01

    Alternating cycles of exposure to high pressure and outgrowth of surviving populations were used to select for highly pressure-resistant mutants of Escherichia coli MG1655. Three barotolerant mutants (LMM1010, LMM1020, and LMM1030) were isolated independently by using outgrowth temperatures of 30, 37, and 42 degrees C, respectively. Survival of these mutants after pressure treatment for 15 min at ambient temperature was 40 to 85% at 220 MPa and 0.5 to 1.5% at 800 MPa, while survival of the parent strain, MG1655, decreased from 15% at 220 MPa to 2 x 10(-8)% at 700 MPa. Heat resistance of mutants LMM1020 and LMM1030 was also altered, as evident by higher D values at 58 and 60 degrees C and reduced z values compared to those for the parent strain. D and z values for mutant LMM1010 were not significantly different from those for the parent strain. Pressure sensitivity of the mutants increased from 10 to 50 degrees C, as opposed to the parent strain, which showed a minimum around 40 degrees C. The ability of the mutants to grow at moderately elevated pressure (50 MPa) was reduced at temperatures above 37 degrees C, indicating that resistance to pressure inactivation is unrelated to barotolerant growth. The development of high levels of barotolerance as demonstrated in this work should cause concern about the safety of high-pressure food processing. PMID:9055412

  19. Engineering modular ester fermentative pathways in Escherichia coli.

    PubMed

    Layton, Donovan S; Trinh, Cong T

    2014-11-01

    Sensation profiles are observed all around us and are made up of many different molecules, such as esters. These profiles can be mimicked in everyday items for their uses in foods, beverages, cosmetics, perfumes, solvents, and biofuels. Here, we developed a systematic 'natural' way to derive these products via fermentative biosynthesis. Each ester fermentative pathway was designed as an exchangeable ester production module for generating two precursors- alcohols and acyl-CoAs that were condensed by an alcohol acyltransferase to produce a combinatorial library of unique esters. As a proof-of-principle, we coupled these ester modules with an engineered, modular, Escherichia coli chassis in a plug-and-play fashion to create microbial cell factories for enhanced anaerobic production of a butyrate ester library. We demonstrated tight coupling between the modular chassis and ester modules for enhanced product biosynthesis, an engineered phenotype useful for directed metabolic pathway evolution. Compared to the wildtype, the engineered cell factories yielded up to 48 fold increase in butyrate ester production from glucose. PMID:25281839

  20. Virulence and Fitness Determinants of Uropathogenic Escherichia coli

    PubMed Central

    Subashchandrabose, Sargurunathan; Mobley, Harry L T.

    2015-01-01

    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. PMID:26350328