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Sample records for escherichia coli specifically

  1. Binding specificity of Escherichia coli trigger factor

    Science.gov (United States)

    Patzelt, Holger; Rüdiger, Stefan; Brehmer, Dirk; Kramer, Günter; Vorderwülbecke, Sonja; Schaffitzel, Elke; Waitz, Andreas; Hesterkamp, Thomas; Dong, Liying; Schneider-Mergener, Jens; Bukau, Bernd; Deuerling, Elke

    2001-01-01

    The ribosome-associated chaperone trigger factor (TF) assists the folding of newly synthesized cytosolic proteins in Escherichia coli. Here, we determined the substrate specificity of TF by examining its binding to 2842 membrane-coupled 13meric peptides. The binding motif of TF was identified as a stretch of eight amino acids, enriched in basic and aromatic residues and with a positive net charge. Fluorescence spectroscopy verified that TF exhibited a comparable substrate specificity for peptides in solution. The affinity to peptides in solution was low, indicating that TF requires ribosome association to create high local concentrations of nascent polypeptide substrates for productive interaction in vivo. Binding to membrane-coupled peptides occurred through the central peptidyl-prolyl-cis/trans isomerase (PPIase) domain of TF, however, independently of prolyl residues. Crosslinking experiments showed that a TF fragment containing the PPIase domain linked to the ribosome via the N-terminal domain is sufficient for interaction with nascent polypeptide substrates. Homology modeling of the PPIase domain revealed a conserved FKBP(FK506-binding protein)-like binding pocket composed of exposed aromatic residues embedded in a groove with negative surface charge. The features of this groove complement well the determined substrate specificity of TF. Moreover, a mutation (E178V) in this putative substrate binding groove known to enhance PPIase activity also enhanced TF's association with a prolyl-free model peptide in solution and with nascent polypeptides. This result suggests that both prolyl-independent binding of peptide substrates and peptidyl-prolyl isomerization involve the same binding site. PMID:11724963

  2. Escherichia coli

    Science.gov (United States)

    Alizade, Hesam

    2018-01-01

    Escherichia coli is the most prominent cause of infectious diseases that span from the gastrointestinal tract to extra-intestinal sites such as urinary tract infection, septicaemia, and neonatal meningitis. The emergence and spread of antibiotic resistance in E. coli is an increasing public health concern across the world. Rising resistance in E. coli isolates is also observed in Iran. This review summarizes the status of antibiotic resistance of E. coli isolates in Iran from 2007 to 2016. The data of the prevalence of E. coli antibiotic resistance were collected from databases such as Web of Science, PubMed, Scopus, Embase, Cochrane Library, Google Scholar and Scientific Information Database. Antibiotic resistance in E. coli is on the rise. Prevalence of antibiotic resistance of E. coli varies from region to region in Iran.

  3. Proteome reallocation in Escherichia coli with increasing specific growth rate.

    Science.gov (United States)

    Peebo, Karl; Valgepea, Kaspar; Maser, Andres; Nahku, Ranno; Adamberg, Kaarel; Vilu, Raivo

    2015-04-01

    Cells usually respond to changing growth conditions with a change in the specific growth rate (μ) and adjustment of their proteome to adapt and maintain metabolic efficiency. Description of the principles behind proteome resource allocation is important for understanding metabolic regulation in response to changing μ. Thus, we analysed the proteome resource allocation dynamics of Escherichia coli into different metabolic processes in response to changing μ. E. coli was grown on minimal and defined rich media in steady state continuous cultures at different μ and characterised combining two LC-MS/MS-based proteomics methods: stable isotope labelling by amino acids in cell culture (SILAC) and intensity based label-free absolute quantification. We detected slowly growing cells investing more proteome resources in energy generation and carbohydrate transport and metabolism whereas for achieving faster growth cells needed to devote most resources to translation and processes closely related to the protein synthesis pipeline. Furthermore, down-regulation of energy generation and carbohydrate metabolism proteins with faster growth displayed very similar expression dynamics with the global transcriptional regulator CRP (cyclic AMP receptor protein), pointing to a dominant protein resource allocating role of this protein. Our data also suggest that acetate overflow may be the result of global proteome resource optimisation as cells saved proteome resources by switching from fully respiratory to respiro-fermentative growth. The presented results give a quantitative overview of how E. coli adjusts its proteome to achieve faster growth and in future could contribute to the design of more efficient cell factories through proteome optimisation.

  4. Escherichia Coli

    Science.gov (United States)

    Goodsell, David S.

    2009-01-01

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

  5. DFI-seq identification of environment-specific gene expression in uropathogenic Escherichia coli

    DEFF Research Database (Denmark)

    Madelung, Michelle; Kronborg, Tina; Doktor, Thomas Koed

    2017-01-01

    BACKGROUND: During infection of the urinary tract, uropathogenic Escherichia coli (UPEC) are exposed to different environments, such as human urine and the intracellular environments of bladder epithelial cells. Each environment elicits a distinct bacterial environment-specific transcriptional...

  6. Escherichia coli

    Science.gov (United States)

    Qian, Cunzhong; Hou, Jiafa

    2017-10-01

    The present study aimed to investigate whether Escherichia coli virulence affects the roles of sex hormone receptors in female dogs with simulated pyometra. A total of 33 healthy, nulliparous, crossbred female dogs were divided into four groups, with 10 dogs in each of the three experimental groups and 3 dogs in the control group. Estradiol was administrated to female dogs in group 1 continuously at 0.6-4.8 mg/kg twice daily for 12 days (the dose doubled every three days), followed by intramuscular injection of 0.2-1.8 mg/kg progesterone. The progesterone was administrated with an initial dose of 0.2 µg/kg and increased 0.2 mg/kg every three days, twice daily until the maximum of 1.8 mg/kg for 24 days and maintained at 1.8 mg/kg for 19 days. Progesterone only was administrated at 1.8 mg/kg in group 2 (twice daily) for 55 continuous days and only estradiol was administered with an initial dose of 0.6 µg/kg (dose doubled every 3 days for 12 days) in group 3 twice daily and maintained at 4.8 mg/kg for the following 43 days. A strongly virulent E. coli strain, nau-b, and a weakly virulent strain, nau-i, were screened. On the 12th day of diestrus, 5 female dogs in each of the experimental groups were inoculated with E. coli nau-i strain, while the other five in each group were inoculated with nau-b strain. Histopathological changes of uterine tissues were microscopically observed 50 days after E. coli inoculation and hormone receptor expression levels were detected by quantitative polymerase chain reaction. Simulated pyometra was observed in dogs administrated with progesterone alone or progesterone combined with estradiol. The clinical symptoms and histopathological observation demonstrated that inoculation with strongly virulent E. coli strain, nau-b, caused earlier onset of pyometra symptoms and more severe pyometra symptoms compared with the weakly virulent E. coli strain, nau-i. Furthermore, estrogen and progesterone receptor levels in dogs with pyometra

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

    Science.gov (United States)

    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.

  8. Specificity of the Escherichia coli proline transport system.

    Science.gov (United States)

    Rowland, I; Tristram, H

    1975-09-01

    The presence of both the carbonyl portion of the carboxyl group at position 2 of the pyrrolidine ring and a secondary amine was essential for uptake of a compound by the proline permease of Escherichia coli. The permease possessed a high affinity for azetidine-2-carboxylic acid and for compounds with ring structures smaller than the pyrrolidine ring. Pipecolic acid, the higher homologue of proline, and its derivatives were not transported. Cis- and trans-3,4-methano-prolines, also six-membered ring structures, behaved anomolously in that they possessed a high affinity for the permease. The difference between the methano-prolines and other six-membered ring structures probably resides in the fact that the former exist in the "boat" configuration whereas the latter possess the "chair" configuration. In general, substituted prolines in the cis configuration displayed a higher affinity for the permease than did corresponding trans isomers, though the affinity for substituted prolines was influenced by the position, size, and polar or nonpolar nature of the substituent group. At O C many analogues with affinity for proline permease exchanged with intracellular proline, but some analogues, notably trans-3-methyl- and trans-4-methyl-L-prolines, though possessing high affinity for the permease, showed an almost complete inability to exchange with intracellular proline.

  9. Escherichia coli-mediated impairment of ureteric contractility is uropathogenic E. coli specific.

    Science.gov (United States)

    Floyd, Rachel V; Upton, Mathew; Hultgren, Scott J; Wray, Susan; Burdyga, Theodor V; Winstanley, Craig

    2012-11-15

    Ureters are fundamental for keeping kidneys free from uropathogenic Escherichia coli (UPEC), but we have shown that 2 strains (J96 and 536) can subvert this role and reduce ureteric contractility. To determine whether this is (1) a widespread feature of UPEC, (2) exhibited only by UPEC, and (3) dependent upon type 1 fimbriae, we analyzed strains representing epidemiologically important multilocus sequence types ST131, ST73, and ST95 and non-UPEC E. coli. Contractility and calcium transients in intact rat ureters were compared between strains. Mannose and fim mutants were used to investigate the role of type 1 fimbriae. Non-UPEC had no significant effect on contractility, with a mean decrease after 8 hours of 8.8%, compared with 8.8% in controls. UPEC effects on contractility were strain specific, with decreases from 9.47% to 96.7%. Mannose inhibited the effects of the most potent strains (CFT073 and UTI89) but had variable effects among other UPEC strains. Mutation and complementation studies showed that the effects of the UTI89 cystitis isolate were fimH dependent. We find that (1) non-UPEC do not affect ureteric contractility, (2) impairment of contractility is a common feature of UPEC, and (3) the mechanism varies between strains, but for the most potent UPEC type 1 fimbriae are involved.

  10. Specificity for field enumeration of Escherichia coli in tropical surface waters

    DEFF Research Database (Denmark)

    Jensen, Peter Kjær Mackie; Aalbaek, B; Aslam, R

    2001-01-01

    In remote rural areas in developing countries, bacteriological monitoring often depends on the use of commercial field media. This paper evaluates a commercial field medium used for the enumeration of Escherichia coli in different surface waters under primitive field conditions in rural Pakistan....... In order to verify the field kit, 117 presumptive E. coli isolates have been tested, finding a specificity of only 40%. By excluding some strains based on colony colours, the calculated specificity could be increased to 65%. Thus, it is suggested that prior to use in a tropical environment, the specificity...... of any commercial medium used should be tested with representative tropical isolates, in order to increase the specificity....

  11. Diarrheagenic Escherichia coli.

    Science.gov (United States)

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

    2016-12-01

    Most Escherichia coli strains live harmlessly in the intestines and rarely cause disease in healthy individuals. Nonetheless, a number of pathogenic strains can cause diarrhea or extraintestinal diseases both in healthy and immunocompromised individuals. Diarrheal illnesses are a severe public health problem and a major cause of morbidity and mortality in infants and young children, especially in developing countries. E. coli strains that cause diarrhea have evolved by acquiring, through horizontal gene transfer, a particular set of characteristics that have successfully persisted in the host. According to the group of virulence determinants acquired, specific combinations were formed determining the currently known E. coli pathotypes, which are collectively known as diarrheagenic E. coli. In this review, we have gathered information on current definitions, serotypes, lineages, virulence mechanisms, epidemiology, and diagnosis of the major diarrheagenic E. coli pathotypes. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

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

    Science.gov (United States)

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

    2016-05-11

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

  13. Escherichia coli pathotypes

    Science.gov (United States)

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

  14. PCR approach for rapid detection of Escherichia coli in tempe using a specific primer

    Directory of Open Access Journals (Sweden)

    Siti Harnina Bintari

    2014-12-01

    Full Text Available Tempe known as a traditional fermented food originated from Indonesia. It has a unique flavour and texture. It also contains high protein and usually serves to substitute meat, fish, or egg as a complement to rice. The manufacture process of Tempe is quite complex and mostly, the traditional process has not employed the hygienic standard. In the process of Tempe making, there are two critical stages of the whole process; i.e. soaking of soybeans and solid state fermentation by Rhizopus sp. During the process, foodborne pathogen bacteria such as Escherichia coli could contaminate the product of Tempe. The bacterial contamination could be revealed through culture dependent methods which is costly, laborious, and time consuming. Therefore, the culture-independent method such as polymerase chain reaction using a specific primer could be applied to detect target microorganism to save time and labour. In this study, thirty-one Tempe samples collected from different manufacturers in Semarang, Central Java, Indonesia were analysed by PCR. In order to obtain the bacterial genomic DNA, a modified Chelex 100-Microwave method was employed. The results of DNA extraction showed that the method was an applicable method. It gave high quantity and quality of DNA; therefore, it could be applied in the PCR reaction. The DNA samples were employed in PCR for detection of Escherichia coli using Ecoli706F/R. It was found that 27 out of 31 samples were detected having Escherichia coli contamination showed by the presence of the amplified product size 706 bp. The application of this method could significantly reduce costs and time of analysis in the laboratory. Further response after E. coli were detected could be employed, including investigation of the critical factors in Tempe manufacturing process which allowed E. coli contamination.

  15. Escherichia coli Infections.

    Science.gov (United States)

    Makvana, Sejal; Krilov, Leonard R

    2015-04-01

    Virulent strains of Escherichia coli are responsible for most diarrheal infections, meningitis, septicemia, and urinary tract infections in children worldwide. Clinicians must learn to recognize, treat, and prevent these infections. After completing this article, readers should be able to: 1. Describe the epidemiology of E coli infections. 2. Recognize the clinical features of E coli infections, including the O157: H7 strain. 3. Appropriately treat children with various types of E coli infections. 4. Understand ways to prevent E coli infections.

  16. Taxonomy Icon Data: Escherichia coli [Taxonomy Icon

    Lifescience Database Archive (English)

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

  17. Amperometric quantification of total coliforms and specific detection of Escherichia coli.

    Science.gov (United States)

    Mittelmann, Adrian Schwartz; Ron, Eliora Z; Rishpon, Judith

    2002-02-15

    The quantitative determination of total and fecal coliforms, as indicators of fecal pollution, is essential for water quality control. We developed a sensitive, inexpensive amperometric enzyme biosensor based on the electrochemical detection of beta-galactosidase activity, using p-amino-phenyl-beta-D-galactopyranoside as substrate, for determining the density of coliforms, represented by Escherichia coli and Klebsiella pneumoniae. The specific detection of E. coli was achieved using an antibody-coated electrode that specifically binds the target bacteria. Amperometric detection enabled the determination of 1000 colony-forming units/mL within 60-75 min. Preincubation for 5-6 h further increased the sensitivity more than 100-fold. The present experimental setup allowed the simultaneous analysis of up to eight samples, using disposable screen-printed electrodes.

  18. Cloud-enabled microscopy and droplet microfluidic platform for specific detection of Escherichia coli in water.

    Directory of Open Access Journals (Sweden)

    Alexander Golberg

    Full Text Available We report an all-in-one platform - ScanDrop - for the rapid and specific capture, detection, and identification of bacteria in drinking water. The ScanDrop platform integrates droplet microfluidics, a portable imaging system, and cloud-based control software and data storage. The cloud-based control software and data storage enables robotic image acquisition, remote image processing, and rapid data sharing. These features form a "cloud" network for water quality monitoring. We have demonstrated the capability of ScanDrop to perform water quality monitoring via the detection of an indicator coliform bacterium, Escherichia coli, in drinking water contaminated with feces. Magnetic beads conjugated with antibodies to E. coli antigen were used to selectively capture and isolate specific bacteria from water samples. The bead-captured bacteria were co-encapsulated in pico-liter droplets with fluorescently-labeled anti-E. coli antibodies, and imaged with an automated custom designed fluorescence microscope. The entire water quality diagnostic process required 8 hours from sample collection to online-accessible results compared with 2-4 days for other currently available standard detection methods.

  19. Rapid and Specific Detection of the Escherichia coli Sequence Type 648 Complex within Phylogroup F.

    Science.gov (United States)

    Johnson, James R; Johnston, Brian D; Gordon, David M

    2017-04-01

    The Escherichia coli sequence type 648 complex (STc648) is an emerging lineage within phylogroup F-formerly included within phylogroup D-that is associated with multidrug resistance. Here, we designed and validated a novel multiplex PCR-based assay for STc648 that took advantage of (i) four distinctive single-nucleotide polymorphisms in icd allele 96 and gyrB allele 87, two of the multilocus sequence typing alleles that define ST648; and (ii) the typical absence within STc648 of uidA, an E. coli-specific gene encoding β-glucuronidase. Within a diverse 212-strain validation set that included 109 STs other than STc648, from phylogroups A, B1, B2, C, D, E, and F, the assay exhibited 100% sensitivity (95% confidence interval [CI], 82% to 100%) and specificity (95% CI, 98% to 100%). It functioned similarly well in two distant laboratories that used boiled lysates or DNAzol-purified DNA as the template DNA. Thus, this novel multiplex PCR-based assay should enable any laboratory equipped for diagnostic PCR to rapidly, accurately, and economically screen E. coli isolates for membership in STc648. Copyright © 2017 American Society for Microbiology.

  20. Characterization of the specific pyruvate transport system in Escherichia coli K-12.

    Science.gov (United States)

    Lang, V J; Leystra-Lantz, C; Cook, R A

    1987-01-01

    A mutant of Escherichia coli K-12 lacking pyruvate dehydrogenase and phosphoenolpyruvate synthase was used to study the transport of pyruvate by whole cells. Uptake of pyruvate was maximal in mid-log phase cells, with a Michaelis constant for transport of 20 microM. Pretreatment of the cells with respiratory chain poisons or uncouplers, except for arsenate, inhibited transport up to 95%. Lactate and alanine were competitive inhibitors, but at nonphysiological concentrations. The synthetic analogs 3-bromopyruvate and pyruvic acid methyl ester inhibited competitively. The uptake of pyruvate was also characterized in membrane vesicles from wild-type E. coli K-12. Transport required an artificial electron donor system, phenazine methosulfate and sodium ascorbate. Pyruvate was concentrated in vesicles 7- to 10-fold over the external concentration, with a Michaelis constant of 15 microM. Energy poisons, except arsenate, inhibited the transport of pyruvate. Synthetic analogs such as 3-bromopyruvate were competitive inhibitors of transport. Lactate initially appeared to be a competitive inhibitor of pyruvate transport in vesicles, but this was a result of oxidation of lactate to pyruvate. The results indicate that uptake of pyruvate in E. coli is via a specific active transport system.

  1. The Escherichia coli Tus-Ter replication fork barrier causes site-specific DNA replication perturbation in yeast

    DEFF Research Database (Denmark)

    Larsen, Nicolai B; Sass, Ehud; Suski, Catherine

    2014-01-01

    Replication fork (RF) pausing occurs at both 'programmed' sites and non-physiological barriers (for example, DNA adducts). Programmed RF pausing is required for site-specific DNA replication termination in Escherichia coli, and this process requires the binding of the polar terminator protein, Tus...... as a versatile, site-specific, heterologous DNA replication-perturbing system, with a variety of potential applications....

  2. ESBL-Producing Escherichia coli

    DEFF Research Database (Denmark)

    Hertz, Frederik Boetius

    Urinary tract infection (UTI) is one the most common bacterial infections and is regularly treated in primary health care. The most common cause of UTI is extraintestinal pathogenic Escherichia coli (ExPEC) already present in the intestinal microflora, often as the dominating strain. Resistance...... in E.coli is increasing and especially isolates producing Extended-Spectrum Beta-Lactamases (ESBL) have been reported worldwide. Treatment of UTI is usually initiated by the general practitioners and a significant proportion of clinical isolates are now resistant to first line antibiotics. The global...... dissemination of resistant E.coli has in particular been driven by the spread of a few specific E.coli-lineages and it seems that there is a difference between the sequence types found among resistant E.coli, ESBL-producing E.coli and antibiotic susceptible E.coli. The overall objectives of this thesis were...

  3. Tunable translational control using site-specific unnatural amino acid incorporation in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Yusuke Kato

    2015-04-01

    Full Text Available Translation of target gene transcripts in Escherichia coli harboring UAG amber stop codons can be switched on by the amber-codon-specific incorporation of an exogenously supplied unnatural amino acid, 3-iodo-L-tyrosine. Here, we report that this translational switch can control the translational efficiency at any intermediate magnitude by adjustment of the 3-iodo-L-tyrosine concentration in the medium, as a tunable translational controller. The translational efficiency of a target gene reached maximum levels with 10−5 M 3-iodo-L-tyrosine, and intermediate levels were observed with suboptimal concentrations (approximately spanning a 2-log10 concentration range, 10−7–10−5 M. Such intermediate-level expression was also confirmed in individual bacteria.

  4. Caracemide, a site-specific irreversible inhibitor of protein R1 of Escherichia coli ribonucleotide reductase

    DEFF Research Database (Denmark)

    Larsen, I. K.; Cornett, Claus; Karlsson, M.

    1992-01-01

    The anticancer drug caracemide, N-acetyl-N,O-di(methylcarbamoyl)hydroxylamine, and one of its degradation products, N-acetyl-O-methylcarbamoyl-hydroxylamine, were found to inhibit the enzyme ribonucleotide reductase of Escherichia coli by specific interaction with its larger component protein R1....... No effect on the smaller protein R2 was observed. The effect of the degradation product was about 30 times lower than that of caracemide itself. The caracemide inactivation of R1 is irreversible, with an apparent second-order rate constant of 150 M-1 s-1. The R1R2 holoenzyme was approximately 30 times more...... inactivation. These results indicate that caracemide inactivates R1 by covalent modification at the substrate-binding site. By analogy with the known interaction between caracemide and acetylcholinesterase or choline acetyltransferase, we propose that the modification of R1 occurs at an activated cysteine...

  5. Peptide ligands specific to the oxidized form of escherichia coli thioredoxin.

    Energy Technology Data Exchange (ETDEWEB)

    Scholle, M. D.; Banach, B. S.; Hamdan, S. M.; Richardson, C. C.; Kay, B. K.; Biosciences Division; Amunix, Inc.; Univ. of Illinois at Chicago; Harvard Medical School

    2008-11-01

    Thioredoxin (Trx) is a highly conserved redox protein involved in several essential cellular processes. In this study, our goal was to isolate peptide ligands to Escherichia coli Trx that mimic protein-protein interactions, specifically the T7 polymerase-Trx interaction. To do this, we subjected Trx to affinity selection against a panel of linear and cysteine-constrained peptides using M13 phage display. A novel cyclized conserved peptide sequence, with a motif of C(D/N/S/T/G)D(S/T)-hydrophobic-C-X-hydrophobic-P, was isolated to Trx. These peptides bound specifically to the E. coli Trx when compared to the human and spirulina homologs. An alanine substitution of the active site cysteines (CGPC) resulted in a significant loss of peptide binding affinity to the Cys-32 mutant. The peptides were also characterized in the context of Trx's role as a processivity factor of the T7 DNA polymerase (gp5). As the interaction between gp5 and Trx normally takes place under reducing conditions, which might interfere with the conformation of the disulfide-bridged peptides, we made use of a 22 residue deletion mutant of gp5 in the thioredoxin binding domain (gp5{Delta}22) that bypassed the requirements of reducing conditions to interact with Trx. A competition study revealed that the peptide selectively inhibits the interaction of gp5{Delta}22 with Trx, under oxidizing conditions, with an IC50 of {approx} 10 {micro}M.

  6. Biotinylation of environmentally isolated Shiga toxin-producing Escherichia coli (STEC) – specific bacteriophages for biosensor and biocontrol applications

    Science.gov (United States)

    Like common bacteriophages, Shiga toxin-producing Escherichia coli (STEC) bacteriophages are viruses that recognize and bind to specific bacterial host (STEC) for propagation. They co-exist with STEC hosts, which cause epidemic food and waterborne illnesses, but may act as host populations limiting ...

  7. Host-specific induction of Escherichia coli fitness genes during human urinary tract infection.

    Science.gov (United States)

    Subashchandrabose, Sargurunathan; Hazen, Tracy H; Brumbaugh, Ariel R; Himpsl, Stephanie D; Smith, Sara N; Ernst, Robert D; Rasko, David A; Mobley, Harry L T

    2014-12-23

    Uropathogenic Escherichia coli (UPEC) is the predominant etiological agent of uncomplicated urinary tract infection (UTI), manifested by inflammation of the urinary bladder, in humans and is a major global public health concern. Molecular pathogenesis of UPEC has been primarily examined using murine models of UTI. Translational research to develop novel therapeutics against this major pathogen, which is becoming increasingly antibiotic resistant, requires a thorough understanding of mechanisms involved in pathogenesis during human UTIs. Total RNA-sequencing (RNA-seq) and comparative transcriptional analysis of UTI samples to the UPEC isolates cultured in human urine and laboratory medium were used to identify novel fitness genes that were specifically expressed during human infection. Evidence for UPEC genes involved in ion transport, including copper efflux, nickel and potassium import systems, as key fitness factors in uropathogenesis were generated using an experimental model of UTI. Translational application of this study was investigated by targeting Cus, a bacterial copper efflux system. Copper supplementation in drinking water reduces E. coli colonization in the urinary bladder of mice. Additionally, our results suggest that anaerobic processes in UPEC are involved in promoting fitness during UTI in humans. In summary, RNA-seq was used to establish the transcriptional signature in UPEC during naturally occurring, community acquired UTI in women and multiple novel fitness genes used by UPEC during human infection were identified. The repertoire of UPEC genes involved in UTI presented here will facilitate further translational studies to develop innovative strategies against UTI caused by UPEC.

  8. Specific structural probing of plasmid-coded ribosomal RNAs from Escherichia coli

    DEFF Research Database (Denmark)

    Aagaard, C; Rosendahl, G; Dam, M

    1991-01-01

    The preferred method for construction and in vivo expression of mutagenised Escherichia coli ribosomal RNAs (rRNAs) is via high copy number plasmids. Transcription of wild-type rRNA from the seven chromosomal rrn operons in strains harbouring plasmid-coded mutant rRNAs leads to a heterogeneous ri...

  9. Investigating specific bacterial resistance to AMPs by using a magainin I-resistant Escherichia coli model.

    Science.gov (United States)

    de Almeida, Keyla C; Lima, Thais B; Motta, Dielle O; Silva, Osmar N; Magalhães, Beatriz S; Dias, Simoni C; Franco, Octávio L

    2014-10-01

    Antimicrobial peptides (AMPs) are multifunctional compounds that may show antimicrobial and immunomodulatory activities. With the rapid increase in the incidence of multidrug-resistant bacteria, there is an enormous interest in AMPs as templates for the production of new antibiotics. However, there are concerns that the therapeutic administration of AMPs can select resistant strains. In order to distinguish between resistant and non-resistant strains and verify resistance specificity to AMPs, in this study a magainin I-resistant Escherichia coli model was used. First, the identity of all strains was confirmed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)-MS, VITEK 2 and MicroScan, and the susceptible and magainin-resistant strains were successfully differentiated by MALDI-TOF-MS analysis. Furthermore, cross-resistances to a broad spectrum of antibiotics were evaluated, showing that all E. coli strains are susceptible to the drugs tested, suggesting that the resistance seems to be specific to AMPs. Finally, the specific resistance to magainin I compared with other AMPs was checked by microdilution. This experiment showed that the magainin MICs were 62 and 104 μM for susceptible and resistant strains, respectively. The other AMPs MICs were 3.4 μM to proline-arginine-rich 39-amino-acid peptide, 43 μM to porcine myeloid antimicrobial 23-amino-acid peptide-23 and 1.2 μM to cecropin P1 for all strains, demonstrating any additional resistance to peptides here evaluated, confirming that the resistance seems to be essentially specific to magainin I. In summary, the data reported here reinforce the proposal that magainin I seems not to be merely a membrane disruptor, probably showing additional molecular targets in pathogenic bacteria.

  10. ANIMAL ENTEROTOXIGENIC ESCHERICHIA COLI

    Science.gov (United States)

    Dubreuil, J. Daniel; Isaacson, Richard E.; Schifferli, Dieter M.

    2016-01-01

    Enterotoxigenic Escherichia coli (ETEC) is the most common cause of E. coli diarrhea in farm animals. ETEC are characterized by the ability to produce two types of virulence factors; adhesins that promote binding to specific enterocyte receptors for intestinal colonization and enterotoxins responsible for fluid secretion. The best-characterized adhesins are expressed in the context of fimbriae, such as the F4 (also designated K88), F5 (K99), F6 (987P), F17 and F18 fimbriae. Once established in the animal small intestine, ETEC produces enterotoxin(s) that lead to diarrhea. The enterotoxins belong to two major classes; heat-labile toxin that consist of one active and five binding subunits (LT), and heat-stable toxins that are small polypeptides (STa, STb, and EAST1). This chapter describes the disease and pathogenesis of animal ETEC, the corresponding virulence genes and protein products of these bacteria, their regulation and targets in animal hosts, as well as mechanisms of action. Furthermore, vaccines, inhibitors, probiotics and the identification of potential new targets identified by genomics are presented in the context of animal ETEC. PMID:27735786

  11. Development of Escherichia coli and Mycobacterium smegmatis recombinants expressing major Mycobacterium tuberculosis-specific antigenic proteins.

    Science.gov (United States)

    Amoudy, Hanady A; Safar, Hussain A; Mustafa, Abu S

    2016-12-01

    Mycobacterium tuberculosis is an obligate pathogenic bacterial species in the family Mycobacteriaceae and the causative agent of most tuberculosis (TB) cases. Until today, the only approved TB vaccine is Bacille Calmette Guerin (BCG), which has been used since 1921. While BCG provides fairly effective protection for infants and young children, its efficacy in adults is variable around the world. This could be due to several parameters including strains of the vaccine and exposure of individuals to different environmental bacterial infections. The situation is complicated by the emergence of multidrug resistant strains of M. tuberculosis. This urged the demand to develop new improved vaccines and immunotherapies against TB. Development of nonpathogenic recombinant constructs delivering M. tuberculosis-specific antigenic proteins provides the chance to evaluate candidates to be included in diagnostic tools and preventive vaccines. In our study, we are introducing some of the major M. tuberculosis genes in Escherichia coli and Mycobacterium smegmatis. DNA corresponding to the genes Rv3891, Rv3020, Rv0287, Rv3875, Rv3874, Rv3872, Rv2346c, and Rv3619 were PCR-amplified from M. tuberculosis genomic DNA and visualized on gel electrophoresis at the expected DNA size. Products were subsequently ligated to the plasmid pGEMTeasy and used to transform TOP10 E. coli. Transformed colonies were selected on appropriate media. At the second stage, genes-DNA were subcultured in expression vectors pDE22 and pGESTH1; the recombinant plasmids were finally used to transform. M. smegmatis and E. coli, respectively. Expression of proteins in E. coli was confirmed by Western blotting and in M. smegmatis by reverse transcriptase polymerase chain reaction (RT-PCR). Amplified genes were successfully cloned and transformed in E. coli and M. smegmatis. Colonies of recombinant bacteria were detected on appropriate media. Western blotting and RT-PCR confirmed the expression of our corresponding

  12. Examination of the polypeptide substrate specificity for Escherichia coli ClpA.

    Science.gov (United States)

    Li, Tao; Lucius, Aaron L

    2013-07-23

    Enzyme-catalyzed protein unfolding is essential for a large array of biological functions, including microtubule severing, membrane fusion, morphogenesis and trafficking of endosomes, protein disaggregation, and ATP-dependent proteolysis. These enzymes are all members of the ATPases associated with various cellular activity (AAA+) superfamily of proteins. Escherichia coli ClpA is a hexameric ring ATPase responsible for enzyme-catalyzed protein unfolding and translocation of a polypeptide chain into the central cavity of the tetradecameric E. coli ClpP serine protease for proteolytic degradation. Further, ClpA also uses its protein unfolding activity to catalyze protein remodeling reactions in the absence of ClpP. ClpA recognizes and binds a variety of protein tags displayed on proteins targeted for degradation. In addition, ClpA binds unstructured or poorly structured proteins containing no specific tag sequence. Despite this, a quantitative description of the relative binding affinities for these different substrates is not available. Here we show that ClpA binds to the 11-amino acid SsrA tag with an affinity of 200 ± 30 nM. However, when the SsrA sequence is incorporated at the carboxy terminus of a 30-50-amino acid substrate exhibiting little secondary structure, the affinity constant decreases to 3-5 nM. These results indicate that additional contacts beyond the SsrA sequence are required for maximal binding affinity. Moreover, ClpA binds to various lengths of the intrinsically unstructured protein, α-casein, with an affinity of ∼30 nM. Thus, ClpA does exhibit modest specificity for SsrA when incorporated into an unstructured protein. Moreover, incorporating these results with the known structural information suggests that SsrA makes direct contact with the domain 2 loop in the axial channel and additional substrate length is required for additional contacts within domain 1.

  13. Specific binding of lactoferrin to Escherichia coli isolated from human intestinal infections

    Energy Technology Data Exchange (ETDEWEB)

    Naidu, S.S.; Erdei, J.; Forsgren, A.; Naidu, A.S. (Departments of Medical Microbiology, Malmoe General Hospital (Sweden)); Czirok, E.; Gado, I. (National Institute of Hygiene, Budapest (Hungary)); Kalfas, S. (School of Dentistry, University of Lund, Malmoe (Sweden)); Thoren, A. (Infectious Diseases, Malmoe General Hospital (Sweden))

    1991-01-01

    The degrees of human lactoferrin (HLf) and bovine lactoferrin (BLf) binding in 169 Escherichia coli strains isolated from human intestinal infections, and in an additional 68 strains isolated from healthy individuals, were examined in a {sup 125}I-labelled protein binding assay. The binding was expressed as a percentage calculated from the total labelled ligand added to bacteria. The HLf and BLf binding to E. coli was in the range 3.7 to 73.4% and 4.8 to 61.6%, respectively. Enterotoxigenic strains demonstrated a significantly higher HLf binding (median = 19%) than enteropathogenic, enteroinvasive, enterohaemorrhagic strains or normal intestinal E. coli isolates (medians 6 to 9). Enteropathogenic strains belonging to serotypes O44 and O127 demonstrated significantly higher HLf binding compared to O26, O55, O111, O119 and O126. No significant differences in the degree of HLf or BLf binding were found between aerobactin-producing and non-producing strains. The interaction was further characterized in a high Lf-binging EPEC strain, E34663 (serotype O127). The binding was stable in the pH range 4.0 to 7.5, did not dissociate in the presence of 2M NaCl or 2M urea, and reached saturation within two h. Unlabelled HLf and BLf displaced the {sup 125}I-HLf binding to E34663 in a dose-dependent manner. Apo- and iron-saturated forms of Lf demonstrated similar binding to E34663. Among various unlabelled subephithelial matrix proteins and carbohydrates tested (in 10{sup 4}-fold excess) only fibronectin and fibrinogen caused a moderate inhibition of {sup 125}I-HLf binding. According to Scatchard plot analysis, 5,400 HLf-binding sites/cell, with an affinity constant (K{sub a}) of 1.4 x 10{sup -7} M, were estimated in strain E34663. These data establish the presence of a specific Lf-binding mechanism in E. coli. (au).

  14. Allosteric Control of Substrate Specificity of the Escherichia coli ADP-Glucose Pyrophosphorylase

    Directory of Open Access Journals (Sweden)

    Ana C. Ebrecht

    2017-06-01

    Full Text Available The substrate specificity of enzymes is crucial to control the fate of metabolites to different pathways. However, there is growing evidence that many enzymes can catalyze alternative reactions. This promiscuous behavior has important implications in protein evolution and the acquisition of new functions. The question is how the undesirable outcomes of in vivo promiscuity can be prevented. ADP-glucose pyrophosphorylase from Escherichia coli is an example of an enzyme that needs to select the correct substrate from a broad spectrum of alternatives. This selection will guide the flow of carbohydrate metabolism toward the synthesis of reserve polysaccharides. Here, we show that the allosteric activator fructose-1,6-bisphosphate plays a role in such selection by increasing the catalytic efficiency of the enzyme toward the use of ATP rather than other nucleotides. In the presence of fructose-1,6-bisphosphate, the kcat/S0.5 for ATP was near ~600-fold higher that other nucleotides, whereas in the absence of activator was only ~3-fold higher. We propose that the allosteric regulation of certain enzymes is an evolutionary mechanism of adaptation for the selection of specific substrates.

  15. Allosteric Control of Substrate Specificity of the Escherichia coli ADP-glucose Pyrophosphorylase

    Science.gov (United States)

    Ebrecht, Ana C.; Solamen, Ligin; Hill, Benjamin L.; Iglesias, Alberto A.; Olsen, Kenneth W.; Ballicora, Miguel A.

    2017-06-01

    The substrate specificity of enzymes is crucial to control the fate of metabolites to different pathways. However, there is growing evidence that many enzymes can catalyze alternative reactions. This promiscuous behavior has important implications in protein evolution and the acquisition of new functions. The question is how the undesirable outcomes of in vivo promiscuity can be prevented. ADP-glucose pyrophosphorylase from Escherichia coli is an example of an enzyme that needs to select the correct substrate from a broad spectrum of alternatives. This selection will guide the flow of carbohydrate metabolism towards the synthesis of reserve polysaccharides. Here, we show that the allosteric activator fructose-1,6-bisphosphate plays a role in such selection by increasing the catalytic efficiency of the enzyme towards the use of ATP rather than other nucleotides. In the presence of fructose-1,6-bisphosphate, the kcat/S0.5 for ATP was near 600-fold higher that other nucleotides, whereas in the absence of activator was only 3-fold higher. We propose that the allosteric regulation of certain enzymes is an evolutionary mechanism of adaptation for the selection of specific substrates.

  16. Enterohemorrhagic Escherichia coli (EHEC

    Directory of Open Access Journals (Sweden)

    Abdullah Kilic

    2011-08-01

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

  17. Characterization of the specific pyruvate transport system in Escherichia coli K-12.

    OpenAIRE

    Lang, V J; Leystra-Lantz, C; Cook, R A

    1987-01-01

    A mutant of Escherichia coli K-12 lacking pyruvate dehydrogenase and phosphoenolpyruvate synthase was used to study the transport of pyruvate by whole cells. Uptake of pyruvate was maximal in mid-log phase cells, with a Michaelis constant for transport of 20 microM. Pretreatment of the cells with respiratory chain poisons or uncouplers, except for arsenate, inhibited transport up to 95%. Lactate and alanine were competitive inhibitors, but at nonphysiological concentrations. The synthetic ana...

  18. Cyclophosphamide-induced bacterial translocation in Escherichia coli C25-monoassociated specific pathogen-free mice.

    Science.gov (United States)

    Nakayama, M; Itoh, K; Takahashi, E

    1997-01-01

    The kinetics of bacterial translocation (BTL) from the intestine to the mesenteric lymph nodes (MLN) and the number of peripheral white blood cells (WBC), macrophages in Peyer's patches (PP) and M-cells on the surface of cecal PP after cyclophosphamide (CY) injection were examined in penicillin-G and streptomycin sulfate decontaminated and Escherichia coli C25-monoassociated specific pathogen-free mice. WBC are counted to confirm the immunological state of the mice. Until 8 days after CY injection, the number of WBC, bacteria in MLN and macrophages in PP decreased, but then significantly increased on day 14. The levels again decreased to the control levels on day 16. Although the number of M-cells decreased up to day 8, it did not return to the control level on day 16. These results indicate that BTL is stimulated in an immunopotentiated state after CY injection, and this phenomenon may be closely related to the number of macrophages in the blood and PP.

  19. Aglycone specificity of Escherichia coli alpha-xylosidase investigated by transxylosylation.

    Science.gov (United States)

    Kang, Min-Sun; Okuyama, Masayuki; Yaoi, Katsuro; Mitsuishi, Yasushi; Kim, Young-Min; Mori, Haruhide; Kim, Doman; Kimura, Atsuo

    2007-12-01

    The specificity of the aglycone-binding site of Escherichia coli alpha-xylosidase (YicI), which belongs to glycoside hydrolase family 31, was characterized by examining the enzyme's transxylosylation-catalyzing property. Acceptor specificity and regioselectivity were investigated using various sugars as acceptor substrates and alpha-xylosyl fluoride as the donor substrate. Comparison of the rate of formation of the glycosyl-enzyme intermediate and the transfer product yield using various acceptor substrates showed that glucose is the best complementary acceptor at the aglycone-binding site. YicI preferred aldopyranosyl sugars with an equatorial 4-OH as the acceptor substrate, such as glucose, mannose, and allose, resulting in transfer products. This observation suggests that 4-OH in the acceptor sugar ring made an essential contribution to transxylosylation catalysis. Fructose was also acceptable in the aglycone-binding site, producing two regioisomer transfer products. The percentage yields of transxylosylation products from glucose, mannose, fructose, and allose were 57, 44, 27, and 21%, respectively. The disaccharide transfer products formed by YicI, alpha-D-Xylp-(1-->6)-D-Manp, alpha-D-Xylp-(1-->6)-D-Fruf, and alpha-d-Xylp-(1-->3)-D-Frup, are novel oligosaccharides that have not been reported previously. In the transxylosylation to cello-oligosaccharides, YicI transferred a xylosyl moiety exclusively to a nonreducing terminal glucose residue by alpha-1,6-xylosidic linkages. Of the transxylosylation products, alpha-d-Xylp-(1-->6)-D-Manp and alpha-d-Xylp-(1-->6)-D-Fruf inhibited intestinal alpha-glucosidases.

  20. Development of a serogroup-specific DNA microarray for identification of Escherichia coli strains associated with bovine septicemia and diarrhea.

    Science.gov (United States)

    Liu, Bin; Wu, Fan; Li, Dan; Beutin, Lothar; Chen, Min; Cao, Boyang; Wang, Lei

    2010-05-19

    Escherichia coli strains belonging to serogroups O8, O9, O15, O26, O35, O78, O86, O101, O115 and O119 are commonly associated with septicemia or diarrhea in calves and pose a significant threat to the cattle industry worldwide. In this study, a microarray detection system targeting O-antigen-specific genes was developed for the identification of those serogroups. By testing against 186 E. coli and Shigella O-serogroup reference strains, 36 E. coli clinical isolates, and 9 representative strains of other closely related bacterial species, the microarray was shown to be specific and reproducible. The detection sensitivity was determined to be 50 ng genomic DNA. The microarray assay developed here is suitable for the detection and identification of relevant strains from environmental and/or clinical samples, and is especially useful for epidemiologic studies. Copyright 2009 Elsevier B.V. All rights reserved.

  1. DFI-seq identification of environment-specific gene expression in uropathogenic Escherichia coli.

    Science.gov (United States)

    Madelung, Michelle; Kronborg, Tina; Doktor, Thomas Koed; Struve, Carsten; Krogfelt, Karen Angeliki; Møller-Jensen, Jakob

    2017-04-24

    During infection of the urinary tract, uropathogenic Escherichia coli (UPEC) are exposed to different environments, such as human urine and the intracellular environments of bladder epithelial cells. Each environment elicits a distinct bacterial environment-specific transcriptional response. We combined differential fluorescence induction (DFI) with next-generation sequencing, collectively termed DFI-seq, to identify differentially expressed genes in UPEC strain UTI89 during growth in human urine and bladder cells. DFI-seq eliminates the need for iterative cell sorting of the bacterial library and yields a genome-wide view of gene expression. By analysing the gene expression of UPEC in human urine we found that genes involved in amino acid biosynthesis were upregulated. Deletion mutants lacking genes involved in arginine biosynthesis were outcompeted by the wild type during growth in human urine and inhibited in their ability to invade or proliferate in the J82 bladder epithelial cell line. Furthermore, DFI-seq was used to identify genes involved in invasion of J82 bladder epithelial cells. 56 genes were identified to be differentially expressed of which almost 60% encoded hypothetical proteins. One such gene UTI89_C5139, displayed increased adhesion and invasion of J82 cells when deleted from UPEC strain UTI89. We demonstrate the usefulness of DFI-seq for identification of genes required for optimal growth of UPEC in human urine, as well as potential virulence genes upregulated during infection of bladder cell culture. DFI-seq holds potential for the study of bacterial gene expression in live-animal infection systems. By linking fitness genes, such as those genes involved in amino acid biosynthesis, to virulence, this study contributes to our understanding of UPEC pathophysiology.

  2. Tumor-specific colonization, tissue distribution, and gene induction by probiotic Escherichia coli Nissle 1917 in live mice.

    Science.gov (United States)

    Stritzker, Jochen; Weibel, Stephanie; Hill, Philip J; Oelschlaeger, Tobias A; Goebel, Werner; Szalay, Aladar A

    2007-06-01

    Systemic administration of microorganisms into tumor-bearing mice revealed preferential accumulation in tumors in comparison to clearance in organs such as spleen and liver. Here we compared the efficiency of tumor-specific colonization of pathogenic Salmonella typhimurium strains 14028 and SL1344 to the enteroinvasive Escherichia coli 4608-58 strain and to the attenuated Salmonella flexneri 2a SC602 strain, as well as to the uropathogenic E. coli CFT073, the non-pathogenic E. coli Top10, and the probiotic E. coli Nissle 1917 strain. All strains colonized and replicated in tumors efficiently each resulting in more than 1 x 10(8) colony-forming units per gram tumor tissue. Colonization of spleen and liver were significantly lower when E. coli strains were used in comparison to S. typhimurium and the non-pathogenic strains did not colonize those organs at all. Further investigation of E. coli Nissle 1917 showed that no drastic differences in colonization and amplification were seen when immunocompetent and immunocompromised animals were used, and we were able to show that E. coli Nissle 1917 replicates at the border of live and necrotic tumor tissue. We also demonstrated exogenously applied L-arabinose-dependent gene activation in colonized tumors in live mice. These findings will prepare the way for bacterium-mediated controlled protein delivery to solid tumors.

  3. Specific selection for virulent urinary tract infectious Escherichia coli strains during catheter-associated biofilm formation

    DEFF Research Database (Denmark)

    Ferrieres, Lionel; Hancock, Viktoria; Klemm, Per

    2007-01-01

    Biofilm-associated bacterial infections have a major impact on artificial implants such as urinary catheters, often with devastating consequences. The capacity of a microorganism to form a biofilm on a surface depends on the nature of the surface and its conditioning. When a urinary catheter...... microorganisms can attach. Urinary tract infectious (UTI) Escherichia coli range in pathogenicity and the damage they cause - from benign asymptomatic bacteriuria (ABU) strains, which inflict no or few problems to the host, to uropathogenic E. coli (UPEC) strains, which are virulent and often cause severe...... symptoms and complications. We have found that whereas ABU strains produce better biofilms on polystyrene and glass, UPEC strains have a clear competitive advantage during biofilm growth on catheter surfaces. Our results indicate that some silicone and silicone-latex catheters actually select...

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

    Science.gov (United States)

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

    2016-08-01

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

  5. High Prevalence of Virulence Genes in Specific Genotypes of Atypical Enteropathogenic Escherichia coli.

    Science.gov (United States)

    Xu, Yanmei; Bai, Xiangning; Jin, Yujuan; Hu, Bin; Wang, Hong; Sun, Hui; Fan, Ruyue; Fu, Shanshan; Xiong, Yanwen

    2017-01-01

    Atypical enteropathogenic Escherichia coli (aEPEC) strains are emerging enteropathogens that have been detected worldwide. A collection of 228 aEPEC strains (121 from diarrheal patients, 27 from healthy carriers, 47 from animals and 33 from raw meats) were investigated for serotypes, virulence gene profiles and phylogenetic relationships. Sixty-six O serogroups were identified. Serogroup O51 was the most prevalent, followed by O119, O26 and O76. For the 20 virulence genes detected, statistically significant differences were observed in the overall prevalence of efa1 (lifA), nleB, nleE, set/ent, paa, and ehxA genes among strains from diarrheal patients, healthy carriers, animals and raw meats, respectively. Strains from diarrheal patients had significantly higher levels of efa1 (lifA) (29.8 vs. 0%, P = 0.0002), nleB (41.3 vs. 7.4%, P = 0.0004), nleE (43.8 vs. 7.4%, P = 0.0002) and set/ent (41.3 vs. 7.4%, P = 0.0004) genes than strains obtained from healthy carriers. The paa gene was identified more often in isolates from raw meats (63.6 vs. 14.8%, P < 0.0001), animals (42.6 vs. 14.8%, P < 0.0122), and diarrheal patients (36.4 vs. 14.8%, P < 0.0225) than in strains obtained from healthy carriers. The ehxA gene was detected more frequently in strains from raw meats than in strains from diarrheal patients (27.3 vs. 2.5%, P = 0.0000) and healthy carriers (27.3 vs. 7.4%, P = 0.0474). The phylogenetic marker, yjaA, was more frequently observed in strains among healthy carriers than in diarrheal patient strains. Among the 228 aEPEC strains, 79 sequence types (STs) were identified. The prominent STs, which comprised strains carrying the four OI-122 genes and lpfA, were ST40, ST328, and ST29. Overall, the results indicate that aEPEC strains isolated in China are highly heterogeneous. aEPEC strains that are potentially more pathogenic appear to be related to specific STs or clonal complexes and serotypes. The high prevalence of diarrhea-associated genes in animal or raw meat

  6. PART I. ESCHERICHIA COLI

    Directory of Open Access Journals (Sweden)

    Sanaa Mahdi Oraibi

    2016-11-01

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

  7. The changing pattern of antimicrobial resistance within 42,033 Escherichia coli isolates from nosocomial, community and urology patient-specific urinary tract infections, Dublin, 1999-2009.

    LENUS (Irish Health Repository)

    Cullen, Ivor M

    2012-04-01

    To investigate the changing pattern of antimicrobial resistance in Escherichia coli urinary tract infection over an eleven year period, and to determine whether E. coli antibiotic resistance rates vary depending on whether the UTI represents a nosocomial, community acquired or urology patient specific infection.

  8. Fimbrial adhesins from extraintestinal Escherichia coli

    DEFF Research Database (Denmark)

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

    2010-01-01

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

  9. Biosynthesis of plant-specific stilbene polyketides in metabolically engineered Escherichia coli

    Directory of Open Access Journals (Sweden)

    Schmidt-Dannert Claudia

    2006-03-01

    Full Text Available Abstract Background Phenylpropanoids are the precursors to a range of important plant metabolites such as the cell wall constituent lignin and the secondary metabolites belonging to the flavonoid/stilbene class of compounds. The latter class of plant natural products has been shown to function in a wide range of biological activities. During the last few years an increasing number of health benefits have been associated with these compounds. In particular, they demonstrate potent antioxidant activity and the ability to selectively inhibit certain tyrosine kinases. Biosynthesis of many medicinally important plant secondary metabolites, including stilbenes, is frequently not very well understood and under tight spatial and temporal control, limiting their availability from plant sources. As an alternative, we sought to develop an approach for the biosynthesis of diverse stilbenes by engineered recombinant microbial cells. Results A pathway for stilbene biosynthesis was constructed in Escherichia coli with 4-coumaroyl CoA ligase 1 4CL1 from Arabidopsis thaliana and stilbene synthase (STS cloned from Arachis hypogaea. E. coli cultures expressing these enzymes together converted the phenylpropionic acid precursor 4-coumaric acid, added to the growth medium, to the stilbene resveratrol (>100 mg/L. Caffeic acid, added in the same way, resulted in the production of the expected dihydroxylated stilbene, piceatannol (>10 mg/L. Ferulic acid, however, was not converted to the expected stilbene product, isorhapontigenin. Substitution of 4CL1 with a homologous enzyme, 4CL4, with a preference for ferulic acid over 4-coumaric acid, had no effect on the conversion of ferulic acid. Accumulation of tri- and tetraketide lactones from ferulic acid, regardless of the CoA-ligase expressed in E. coli, suggests that STS cannot properly accommodate and fold the tetraketide intermediate to the corresponding stilbene structure. Conclusion Phenylpropionic acids, such as 4

  10. A highly specific Escherichia coli qPCR and its comparison with existing methods for environmental waters.

    Science.gov (United States)

    Walker, David I; McQuillan, Jonathan; Taiwo, Michael; Parks, Rachel; Stenton, Craig A; Morgan, Hywel; Mowlem, Matthew C; Lees, David N

    2017-12-01

    The presence of Escherichia coli in environmental waters is considered as evidence of faecal contamination and is therefore commonly used as an indicator in both water quality and food safety analysis. The long period of time between sample collection and obtaining results from existing culture based methods means that contamination events may already impact public health by the time they are detected. The adoption of molecular based methods for E. coli could significantly reduce the time to detection. A new quantitative real-time PCR (qPCR) assay was developed to detect the ybbW gene sequence, which was found to be 100% exclusive and inclusive (specific and sensitive) for E. coli and directly compared for its ability to quantify E. coli in environmental waters against colony counts, quantitative real-time NASBA (qNASBA) targeting clpB and qPCR targeting uidA. Of the 87 E. coli strains tested, 100% were found to be ybbW positive, 94.2% were culture positive, 100% were clpB positive and 98.9% were uidA positive. The qPCR assays had a linear range of quantification over several orders of magnitude, and had high amplification efficiencies when using single isolates as a template. This compared favourably with qNASBA which showed poor linearity and amplification efficiency. When the assays were applied to environmental water samples, qNASBA was unable to reliably quantify E. coli while both qPCR assays were capable of predicting E. coli concentrations in environmental waters. This study highlights the inability of qNASBA targeting mRNA to quantify E. coli in environmental waters, and presents the first E. coli qPCR assay with 100% target exclusivity. The application of a highly exclusive and inclusive qPCR assay has the potential to allow water quality managers to reliably and rapidly detect and quantify E. coli and therefore take appropriate measures to reduce the risk to public health posed by faecal contamination. Crown Copyright © 2017. Published by

  11. Characterization of a ViI-like Phage Specific to Escherichia coli O157:H7

    Directory of Open Access Journals (Sweden)

    Kropinski Andrew M

    2011-09-01

    Full Text Available Abstract Phage vB_EcoM_CBA120 (CBA120, isolated against Escherichia coli O157:H7 from a cattle feedlot, is morphologically very similar to the classic phage ViI of Salmonella enterica serovar Typhi. Until recently, little was known genetically or physiologically about the ViI-like phages, and none targeting E. coli have been described in the literature. The genome of CBA120 has been fully sequenced and is highly similar to those of both ViI and the Shigella phage AG3. The core set of structural and replication-related proteins of CBA120 are homologous to those from T-even phages, but generally are more closely related to those from T4-like phages of Vibrio, Aeromonas and cyanobacteria than those of the Enterobacteriaceae. The baseplate and method of adhesion to the host are, however, very different from those of either T4 or the cyanophages. None of the outer baseplate proteins are conserved. Instead of T4's long and short tail fibers, CBA120, like ViI, encodes tail spikes related to those normally seen on podoviruses. The 158 kb genome, like that of T4, is circularly permuted and terminally redundant, but unlike T4 CBA120 does not substitute hmdCyt for cytosine in its DNA. However, in contrast to other coliphages, CBA120 and related coliphages we have isolated cannot incorporate 3H-thymidine (3H-dThd into their DNA. Protein sequence comparisons cluster the putative "thymidylate synthase" of CBA120, ViI and AG3 much more closely with those of Delftia phage φW-14, Bacillus subtilis phage SPO1, and Pseudomonas phage YuA, all known to produce and incorporate hydroxymethyluracil (hmdUra.

  12. Escherichia coli Uropathogenesis In Vitro

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  13. Development of goose- and duck-specific DNA markers to determine sources of Escherichia coli in waterways.

    Science.gov (United States)

    Hamilton, Matthew J; Yan, Tao; Sadowsky, Michael J

    2006-06-01

    The contamination of waterways with fecal material is a persistent threat to public health. Identification of the sources of fecal contamination is a vital component for abatement strategies and for determination of total maximum daily loads. While phenotypic and genotypic techniques have been used to determine potential sources of fecal bacteria in surface waters, most methods require construction of large known-source libraries, and they often fail to adequately differentiate among environmental isolates originating from different animal sources. In this study, we used pooled genomic tester and driver DNAs in suppression subtractive hybridizations to enrich for host source-specific DNA markers for Escherichia coli originating from locally isolated geese. Seven markers were identified. When used as probes in colony hybridization studies, the combined marker DNAs identified 76% of the goose isolates tested and cross-hybridized, on average, with 5% of the human E. coli strains and with less than 10% of the strains obtained from other animal hosts. In addition, the combined probes identified 73% of the duck isolates examined, suggesting that they may be useful for determining the contribution of waterfowl to fecal contamination. However, the hybridization probes reacted mainly with E. coli isolates obtained from geese in the upper midwestern United States, indicating that there is regional specificity of the markers identified. Coupled with high-throughput, automated macro- and microarray screening, these markers may provide a quantitative, cost-effective, and accurate library-independent method for determining the sources of genetically diverse E. coli strains for use in source-tracking studies. However, future efforts to generate DNA markers specific for E. coli must include isolates obtained from geographically diverse animal hosts.

  14. Dissemination of Cephalosporin Resistance Genes between Escherichia coli Strains from Farm Animals and Humans by Specific Plasmid Lineages

    NARCIS (Netherlands)

    de Been, Mark; Lanza, Val F.; de Toro, María; Scharringa, Jelle; Dohmen, Wietske|info:eu-repo/dai/nl/333690451; Du, Yu; Hu, Juan; Lei, Ying; Li, Ning; Tooming-Klunderud, Ave; Heederik, Dick J J|info:eu-repo/dai/nl/072910542; Fluit, Ad C.; Bonten, Marc J M; Willems, Rob J L; de la Cruz, Fernando; van Schaik, Willem

    2014-01-01

    Third-generation cephalosporins are a class of β-lactam antibiotics that are often used for the treatment of human infections caused by Gram-negative bacteria, especially Escherichia coli. Worryingly, the incidence of human infections caused by third-generation cephalosporin-resistant E. coli is

  15. Biochemical construction and selection of hybrid plasmids containing specific segments of the Escherichia coli genome.

    Science.gov (United States)

    Clarke, L; Carbon, J

    1975-11-01

    Using a poly(dA-dT) "connector" method, a population of annealed hybrid circular DNAs was constructed in vitro; each hybrid DNA circle containing one full-length molecule of poly(dT)-tailed DNA from E1 colicinogenic factor (Col E1) fragmented by EcoRI endonuclease annealed to any one of a collection of poly(dA)-tailed linear DNA fragments of the entire E. coli genome. This annealed, but unligated, hybrid DNA was used to transform several different auxotrophic mutants of E. coli, and by direct selection, bacterial clones were isolated which contained specific hybrid plasmids. In this manner, bacterial strains containing Col E1 hybrid plasmids carrying the entire tryptophan operon or the arabinsoe and leucine operons were isolated. The methods described should allow the molecular cloning of any portion of the E. coli genome by selection from a pool of DNA molecules containing at least several hundred different hybrids representing the entire bacterial genome.

  16. PATHOGENIC POTENTIALS OF ESCHERICHIA COLI

    African Journals Online (AJOL)

    Electrolyte and haematological parameters in rabbits infected with pathogenic isolates of Escherichia coli from rural water supplies ... rabbits not infected with E. coli. ..... Basic pathology. 4lh ed. ' ' Saunders W.B Company London. Ppl75. Tillman, S.M.M.C. Conover and AG. Tilkian. 1979. Blood Chemistry Electrolytes. In:.

  17. Serogroup-specific risk factors for Shiga toxin-producing Escherichia coli infection in Australia.

    Science.gov (United States)

    McPherson, Michelle; Lalor, Karin; Combs, Barry; Raupach, Jane; Stafford, Russell; Kirk, Martyn D

    2009-07-15

    Shiga toxin-producing Escherichia coli (STEC) is an important cause of foodborne illness. In Australia, risk factors for STEC infection have not been examined at a national level. We conducted a case-control study in 6 Australian jurisdictions from 2003 through 2007. A case patient was defined as a person from whom STEC was isolated or toxin production genes were detected in stool. Case patients were recruited from notifiable disease registers, and 3 control subjects frequency matched by age were selected from databases of controls. Using structured questionnaires, interviewers collected data on clinical illness, foods consumed, and exposures to potential environmental sources. We recruited 43 case patients infected with STEC serogroup O157, 71 case patients infected with non-O157 serogroups, and 304 control subjects. One patient infected with serogroup O157 and 7 infected with non-O157 serogroups developed hemolytic uremic syndrome. Compared with control subjects, case patients infected with STEC O157 were more likely to eat hamburgers, visit restaurants, have previously used antibiotics, or have family occupational exposure to red meat. Case patients infected with non-O157 STEC were more likely to eat sliced chicken meat or corned beef from a delicatessen, camp in the bush, eat catered meals, or have family occupational exposure to animals. Negative associations were observed for certain foods, particularly homegrown vegetables, fruits, or herbs. This study of risk factors for STEC infection by serogroup highlights risks associated with eating hamburgers and occupational handling of raw meat. To prevent infection, hamburgers must be cooked thoroughly, and people handling raw meat or who have close contact with animals must ensure adequate hygiene.

  18. Patchy promiscuity: machine learning applied to predict the host specificity ofSalmonella entericaandEscherichia coli.

    Science.gov (United States)

    Lupolova, Nadejda; Dallman, Tim J; Holden, Nicola J; Gally, David L

    2017-10-01

    Salmonella enterica and Escherichia coli are bacterial species that colonize different animal hosts with sub-types that can cause life-threatening infections in humans. Source attribution of zoonoses is an important goal for infection control as is identification of isolates in reservoir hosts that represent a threat to human health. In this study, host specificity and zoonotic potential were predicted using machine learning in which Support Vector Machine (SVM) classifiers were built based on predicted proteins from whole genome sequences. Analysis of over 1000 S. enterica genomes allowed the correct prediction (67 -90 % accuracy) of the source host for S . Typhimurium isolates and the same classifier could then differentiate the source host for alternative serovars such as S . Dublin. A key finding from both phylogeny and SVM methods was that the majority of isolates were assigned to host-specific sub-clusters and had high host-specific SVM scores. Moreover, only a minor subset of isolates had high probability scores for multiple hosts, indicating generalists with genetic content that may facilitate transition between hosts. The same approach correctly identified human versus bovine E. coli isolates (83 % accuracy) and the potential of the classifier to predict a zoonotic threat was demonstrated using E. coli O157. This research indicates marked host restriction for both S. enterica and E. coli , with only limited isolate subsets exhibiting host promiscuity by gene content. Machine learning can be successfully applied to interrogate source attribution of bacterial isolates and has the capacity to predict zoonotic potential.

  19. Common and specific genomic sequences of avian and human extraintestinal pathogenic Escherichia coli as determined by genomic subtractive hybridization

    Directory of Open Access Journals (Sweden)

    Nolan Lisa K

    2007-08-01

    Full Text Available Abstract Background Suppression subtractive hybridization (SSH strategy was used with extraintestinal pathogenic Escherichia coli (EXPEC that cause avian colibacillosis (avian pathogenic E. coli or APEC and human urinary tract infections (uropathogenic E. coli or UPEC to determine if they possessed genes that were host and/or niche specific. Both APEC and UPEC isolates were used as tester and driver strains in 4 different SSHs in order to obtain APEC- and UPEC-specific subtraction fragments (SFs. Results These procedures yielded a total of 136 tester-specific SFs of which 85 were APEC-derived and 51 were UPEC-derived. Most of the APEC-derived SFs were associated with plasmids; whereas, the majority of UPEC-derived sequences matched to the bacterial chromosome. We further determined the distribution of these tester-derived sequences in a collection of UPEC and APEC isolates using polymerase chain reaction techniques. Plasmid-borne, APEC-derived sequences (tsh, cvaB, traR, traC and sopB were predominantly present in APEC, as compared to UPEC. Of the UPEC-derived SFs, those encoding hemolysin D and F1C major and minor fimbrial subunits were present only in UPEC. However, two UPEC-derived SFs that showed strong similarity to the uropathgenic-specific protein gene (usp occurred in APEC, demonstrating that usp is not specific to UPEC. Conclusion This study provides evidence of the genetic variability of ExPEC as well as genomic similarities between UPEC and APEC; it did not identify any single marker that would dictate host and/or niche specificity in APEC or UPEC. However, further studies on the genes that encode putative or hypothetical proteins might offer important insight into the pathogenesis of disease, as caused by these two ExPEC.

  20. The Escherichia coli azoreductase AzoR Is involved in resistance to thiol-specific stress caused by electrophilic quinones.

    Science.gov (United States)

    Liu, Guangfei; Zhou, Jiti; Fu, Q Shiang; Wang, Jing

    2009-10-01

    The physiological role of Escherichia coli azoreductase AzoR was studied. It was found that AzoR was capable of reducing several benzo-, naphtho-, and anthraquinone compounds, which were better substrates for AzoR than the model azo substrate methyl red. The DeltaazoR mutant displayed reduced viability when exposed to electrophilic quinones, which are capable of depleting cellular reduced glutathione (GSH). Externally added GSH can partially restore the impaired growth of the DeltaazoR mutant caused by 2-methylhydroquinone. The transcription of azoR was induced by electrophiles, including 2-methylhydroquinone, catechol, menadione, and diamide. A transcription start point was identified 44 bp upstream from the translation start point. These data indicated that AzoR is a quinone reductase providing resistance to thiol-specific stress caused by electrophilic quinones.

  1. Specificity of ATP-dependent and GTP-dependent protein kinases with respect to ribosomal proteins of Escherichia coli

    DEFF Research Database (Denmark)

    Issinger, O G; Kiefer, M C; Traut, R R

    1975-01-01

    of the small ribosomal subunit, and to a lesser extent proteins L7 and L12 or the large subunit. Evidence is presented showing different phosphorylation patterns when either whole subunits or the extracted proteins were used as substrate for the protein kinase. Kinetic studies showed proteins S1 and S4......Two protein kinases differing in substrate specificity were used to phosphorylate the 30-S and the 50-S ribosomal subunits of Escherichia coli. The catalytic subunit from the rabbit skeletal muscle protein kinase phosphorylates proteins S1, S4, S9, S13 and S18 of the 30-S subunit and proteins L2, L......4, L5, L16, L18 and L23 of the 50-S subunit with (gamma-32P)ATP as phosphoryl donor. A second protein kinase isolated from rabbit reticulocytes, formerly shown to phosphorylate preferentially acidic proteins and to use GTP as well as ATP, strongly phosphorylated protein S6, an acidic protein...

  2. Genome-scale metabolic reconstructions of multiple Escherichia coli strains highlight strain-specific adaptations to nutritional environments.

    Science.gov (United States)

    Monk, Jonathan M; Charusanti, Pep; Aziz, Ramy K; Lerman, Joshua A; Premyodhin, Ned; Orth, Jeffrey D; Feist, Adam M; Palsson, Bernhard Ø

    2013-12-10

    Genome-scale models (GEMs) of metabolism were constructed for 55 fully sequenced Escherichia coli and Shigella strains. The GEMs enable a systems approach to characterizing the pan and core metabolic capabilities of the E. coli species. The majority of pan metabolic content was found to consist of alternate catabolic pathways for unique nutrient sources. The GEMs were then used to systematically analyze growth capabilities in more than 650 different growth-supporting environments. The results show that unique strain-specific metabolic capabilities correspond to pathotypes and environmental niches. Twelve of the GEMs were used to predict growth on six differentiating nutrients, and the predictions were found to agree with 80% of experimental outcomes. Additionally, GEMs were used to predict strain-specific auxotrophies. Twelve of the strains modeled were predicted to be auxotrophic for vitamins niacin (vitamin B3), thiamin (vitamin B1), or folate (vitamin B9). Six of the strains modeled have lost biosynthetic pathways for essential amino acids methionine, tryptophan, or leucine. Genome-scale analysis of multiple strains of a species can thus be used to define the metabolic essence of a microbial species and delineate growth differences that shed light on the adaptation process to a particular microenvironment.

  3. Enteroaggregative Escherichia coli in Daycare

    DEFF Research Database (Denmark)

    Hebbelstrup Jensen, Betina; Stensvold, Christen R.; Struve, Carsten

    2016-01-01

    Enteroaggregative Escherichia coli (EAEC) has been associated with persistent diarrhea, reduced growth acceleration, and failure to thrive in children living in developing countries and with childhood diarrhea in general in industrialized countries. The clinical implications of an EAEC carrier-st...... heterogeneity of this pathotype. EAEC was highly prevalent (n = 25, 14%) in Danish children in daycare centers and was accompanied by gastrointestinal symptoms in 56% of the infected children. No serotype or phylogenetic group was specifically linked to children with disease....... and 2013. This is the first investigation of the incidence and pathological significance of EAEC in Danish children attending daycare facilities. Conventional microbiological detection of enteric pathogens was performed at Statens Serum Institute, Copenhagen, Denmark, and at Hvidovre Hospital, Copenhagen...

  4. Structural and mutational analysis of amino acid residues involved in ATP specificity of Escherichia coli acetate kinase.

    Science.gov (United States)

    Yoshioka, Aya; Murata, Kousaku; Kawai, Shigeyuki

    2014-11-01

    Acetate kinase (AK) generally utilizes ATP as a phosphoryl donor, but AK from Entamoeba histolytica (PPi-ehiAK) uses pyrophosphate (PPi), not ATP, and is PPi-specific. The determinants of the phosphoryl donor specificity are unknown. Here, we inferred 5 candidate amino acid residues associated with this specificity, based on structural information. Each candidate residue in Escherichia coli ATP-specific AK (ATP-ecoAK), which is unable to use PPi, was substituted with the respective PPi-ehiAK amino acid residue. Each variant ATP-ecoAK had an increased Km for ATP, indicating that the 5 residues are the determinants for the specificity to ATP in ATP-ecoAK. Moreover, Asn-337 of ATP-ecoAK was shown to be particularly significant for the specificity to ATP. The 5 residues are highly conserved in 2625 PPi-ehiAK homologs, implying that almost all organisms have ATP-dependent, rather than PPi-dependent, AK. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  5. The precursor form of the rat liver non-specific lipid-transfer protein, expressed in Escherichia coli, has lipid transfer activity

    NARCIS (Netherlands)

    Ossendorp, B. C.; Geijtenbeek, T. B.; Wirtz, K. W.

    1992-01-01

    The cDNA encoding the precursor form of non-specific lipid-transfer protein (pre-nsL-TP) from rat liver was cloned into the expression vector pET3d. The resulting plasmid was transformed to the Escherichia coli strain BL21(DE3). After induction of the bacteria with

  6. Escherichia coli ASKA Clone Library Harboring tRNA-Specific Adenosine Deaminase (tadA Reveals Resistance towards Xanthorrhizol

    Directory of Open Access Journals (Sweden)

    Yogiara

    2015-09-01

    Full Text Available Xanthorrhizol is a potent antimicrobial compound isolated from the rhizome of Curcuma xanthorrhiza. However, the mechanism of xanthorrhizol action is unknown. To screen for probable target(s, we introduced the ASKA pooled-plasmid library into Escherichia coli W3110 imp4213 and enriched the library for resistant clones with increasing concentrations of xanthorrhizol. After three rounds of enrichment, we found nine genes that increased xanthorrhizol resistance. The resistant clones were able to grow in LB medium containing 256 µg/mL xanthorrhizol, representing a 16-fold increase in the minimum inhibitory concentration. Subsequent DNA sequence analysis revealed that overexpression of tadA, galU, fucU, ydeA, ydaC, soxS, nrdH, yiiD, and mltF genes conferred increased resistance towards xanthorrhizol. Among these nine genes, tadA is the only essential gene. tadA encodes a tRNA-specific adenosine deaminase. Overexpression of E. coli W3110 imp4213 (pCA24N-tadA conferred resistance to xanthorrhizol up to 128 µg/mL. Moreover, overexpression of two tadA mutant enzymes (A143V and F149G led to a twofold increase in the MIC. These results suggest that the targets of xanthorrhizol may include tadA, which has never before been explored as an antibiotic target.

  7. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  8. Peptidoglycan Hydrolases of Escherichia coli

    Science.gov (United States)

    van Heijenoort, Jean

    2011-01-01

    Summary: The review summarizes the abundant information on the 35 identified peptidoglycan (PG) hydrolases of Escherichia coli classified into 12 distinct families, including mainly glycosidases, peptidases, and amidases. An attempt is also made to critically assess their functions in PG maturation, turnover, elongation, septation, and recycling as well as in cell autolysis. There is at least one hydrolytic activity for each bond linking PG components, and most hydrolase genes were identified. Few hydrolases appear to be individually essential. The crystal structures and reaction mechanisms of certain hydrolases having defined functions were investigated. However, our knowledge of the biochemical properties of most hydrolases still remains fragmentary, and that of their cellular functions remains elusive. Owing to redundancy, PG hydrolases far outnumber the enzymes of PG biosynthesis. The presence of the two sets of enzymes acting on the PG bonds raises the question of their functional correlations. It is difficult to understand why E. coli keeps such a large set of PG hydrolases. The subtle differences in substrate specificities between the isoenzymes of each family certainly reflect a variety of as-yet-unidentified physiological functions. Their study will be a far more difficult challenge than that of the steps of the PG biosynthesis pathway. PMID:22126997

  9. Quantitative analysis of commensal Escherichia coli populations reveals host-specific enterotypes at the intra-species level.

    Science.gov (United States)

    Smati, Mounira; Clermont, Olivier; Bleibtreu, Alexandre; Fourreau, Frédéric; David, Anthony; Daubié, Anne-Sophie; Hignard, Cécile; Loison, Odile; Picard, Bertrand; Denamur, Erick

    2015-08-01

    The primary habitat of the Escherichia coli species is the gut of warm-blooded vertebrates. The E. coli species is structured into four main phylogenetic groups A, B1, B2, and D. We estimated the relative proportions of these phylogroups in the feces of 137 wild and domesticated animals with various diets living in the Ile de France (Paris) region by real-time PCR. We distinguished three main clusters characterized by a particular abundance of two or more phylogroups within the E. coli animal commensal populations, which we called "enterocolitypes" by analogy with the enterotypes defined in the human gut microbiota at the genus level. These enterocolitypes were characterized by a dominant (>50%) B2, B1, or A phylogroup and were associated with different host species, diets, and habitats: wild and herbivorous species (wild rabbits and deer), domesticated herbivorous species (domesticated rabbits, horses, sheep, and cows), and omnivorous species (boar, pigs, and chickens), respectively. By analyzing retrospectively the data obtained using the same approach from 98 healthy humans living in Ile de France (Smati et al. 2013, Appl. Environ. Microbiol. 79, 5005-5012), we identified a specific human enterocolitype characterized by the dominant and/or exclusive (>90%) presence of phylogroup B2. We then compared B2 strains isolated from animals and humans, and revealed that human and animal strains differ regarding O-type and B2 subgroup. Moreover, two genes, sfa/foc and clbQ, were associated with the exclusive character of strains, observed only in humans. In conclusion, a complex network of interactions exists at several levels (genus and intra-species) within the intestinal microbiota. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  10. Conjugal Pairing in Escherichia Coli

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 8. Conjugal Pairing in Escherichia Coli. Joshua Lederberg. Classics Volume 13 Issue 8 August 2008 pp 793-794. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/013/08/0793-0794 ...

  11. The Escherichia coli Tus-Ter replication fork barrier causes site-specific DNA replication perturbation in yeast.

    Science.gov (United States)

    Larsen, Nicolai B; Sass, Ehud; Suski, Catherine; Mankouri, Hocine W; Hickson, Ian D

    2014-04-07

    Replication fork (RF) pausing occurs at both 'programmed' sites and non-physiological barriers (for example, DNA adducts). Programmed RF pausing is required for site-specific DNA replication termination in Escherichia coli, and this process requires the binding of the polar terminator protein, Tus, to specific DNA sequences called Ter. Here, we demonstrate that Tus-Ter modules also induce polar RF pausing when engineered into the Saccharomyces cerevisiae genome. This heterologous RF barrier is distinct from a number of previously characterized, protein-mediated, RF pause sites in yeast, as it is neither Tof1-dependent nor counteracted by the Rrm3 helicase. Although the yeast replisome can overcome RF pausing at Tus-Ter modules, this event triggers site-specific homologous recombination that requires the RecQ helicase, Sgs1, for its timely resolution. We propose that Tus-Ter can be utilized as a versatile, site-specific, heterologous DNA replication-perturbing system, with a variety of potential applications.

  12. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    In this study we report on a novel structural phenotype in Escherichia coli biofilms: cellular chain formation. Biofilm chaining in E. coli K-12 was found to occur primarily by clonal expansion, but was not due to filamentous growth. Rather, chain formation was the result of intercellular......; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates...

  13. Structure of putrescine aminotransferase from Escherichia coli provides insights into the substrate specificity among class III aminotransferases.

    Science.gov (United States)

    Cha, Hyung Jin; Jeong, Jae-Hee; Rojviriya, Catleya; Kim, Yeon-Gil

    2014-01-01

    YgjG is a putrescine aminotransferase enzyme that transfers amino groups from compounds with terminal primary amines to compounds with an aldehyde group using pyridoxal-5'-phosphate (PLP) as a cofactor. Previous biochemical data show that the enzyme prefers primary diamines, such as putrescine, over ornithine as a substrate. To better understand the enzyme's substrate specificity, crystal structures of YgjG from Escherichia coli were determined at 2.3 and 2.1 Å resolutions for the free and putrescine-bound enzymes, respectively. Sequence and structural analyses revealed that YgjG forms a dimer that adopts a class III PLP-dependent aminotransferase fold. A structural comparison between YgjG and other class III aminotransferases revealed that their structures are similar. However, YgjG has an additional N-terminal helical structure that partially contributes to a dimeric interaction with the other subunit via a helix-helix interaction. Interestingly, the YgjG substrate-binding site entrance size and charge distribution are smaller and more hydrophobic than other class III aminotransferases, which suggest that YgjG has a unique substrate binding site that could accommodate primary aliphatic diamine substrates, including putrescine. The YgjG crystal structures provide structural clues to putrescine aminotransferase substrate specificity and binding.

  14. SrmB, a DEAD-box helicase involved in Escherichia coli ribosome assembly, is specifically targeted to 23S rRNA in vivo

    OpenAIRE

    Trubetskoy, Dmitrii; Proux, Florence; Allemand, Fr?d?ric; Dreyfus, Marc; Iost, Isabelle

    2009-01-01

    DEAD-box proteins play specific roles in remodeling RNA or ribonucleoprotein complexes. Yet, in vitro, they generally behave as nonspecific RNA-dependent ATPases, raising the question of what determines their specificity in vivo. SrmB, one of the five Escherichia coli DEAD-box proteins, participates in the assembly of the large ribosomal subunit. Moreover, when overexpressed, it compensates for a mutation in L24, the ribosomal protein (r-protein) thought to initiate assembly. Here, using the ...

  15. Structural and mutational analysis of Escherichia coli AlkB provides insight into substrate specificity and DNA damage searching.

    Directory of Open Access Journals (Sweden)

    Paul J Holland

    Full Text Available BACKGROUND: In Escherichia coli, cytotoxic DNA methyl lesions on the N1 position of purines and N3 position of pyrimidines are primarily repaired by the 2-oxoglutarate (2-OG iron(II dependent dioxygenase, AlkB. AlkB repairs 1-methyladenine (1-meA and 3-methylcytosine (3-meC lesions, but it also repairs 1-methylguanine (1-meG and 3-methylthymine (3-meT at a much less efficient rate. How the AlkB enzyme is able to locate and identify methylated bases in ssDNA has remained an open question. METHODOLOGY/PRINCIPAL FINDINGS: We determined the crystal structures of the E. coli AlkB protein holoenzyme and the AlkB-ssDNA complex containing a 1-meG lesion. We coupled this to site-directed mutagenesis of amino acids in and around the active site, and tested the effects of these mutations on the ability of the protein to bind both damaged and undamaged DNA, as well as catalyze repair of a methylated substrate. CONCLUSIONS/SIGNIFICANCE: A comparison of our substrate-bound AlkB-ssDNA complex with our unliganded holoenzyme reveals conformational changes of residues within the active site that are important for binding damaged bases. Site-directed mutagenesis of these residues reveals novel insight into their roles in DNA damage recognition and repair. Our data support a model that the AlkB protein utilizes at least two distinct conformations in searching and binding methylated bases within DNA: a "searching" mode and "repair" mode. Moreover, we are able to functionally separate these modes through mutagenesis of residues that affect one or the other binding state. Finally, our mutagenesis experiments show that amino acid D135 of AlkB participates in both substrate specificity and catalysis.

  16. Improved production of L-lysine by disruption of stationary phase-specific rmf gene in Escherichia coli.

    Science.gov (United States)

    Imaizumi, Akira; Takikawa, Rie; Koseki, Chie; Usuda, Yoshihiro; Yasueda, Hisashi; Kojima, Hiroyuki; Matsui, Kazuhiko; Sugimoto, Shin-Ichi

    2005-04-20

    Growth and rate, at which fermentation products are formed in cells, generally decreases during the stationary phase as a result of changes in gene expression. We focused on the rmf gene, which encodes the ribosome modulation factor protein, as a target for strain modification in order to improve the rate of L-lysine production in Escherichia coli. Increased expression of the rmf gene during the stationary phase was confirmed under various cultivation conditions using DNA macroarray analysis. Mutants with disrupted rmf were then generated from an L-lysine-producing E. coli strain. The rates of L-lysine accumulation and production were significantly increased in disruptants that were cultivated with excess phosphate. By contrast, a higher biomass was generated in disruptants that were grown under limited phosphate conditions. These results demonstrate that disruption of the rmf gene significantly affects L-lysine production and growth in E. coli.

  17. The structure and specificity of Escherichia coli maltose acetyltransferase give new insight into the LacA family of acyltransferases.

    Science.gov (United States)

    Lo Leggio, Leila; Dal Degan, Florence; Poulsen, Peter; Andersen, Søren Møller; Larsen, Sine

    2003-05-13

    The crystallographic three-dimensional structure of the Escherichia coli maa gene product, previously identified as a maltose O-acetyltransferase (MAT) [Brand, B., and Boos, W. (1991) J. Biol. Chem. 266, 14113-14118] has been determined to 2.15 A resolution by the single anomalous dispersion method using data from a crystal cocrystallized with trimethyllead acetate. It is shown here that MAT acetylates glucose exclusively at the C6 position and maltose at the C6 position of the nonreducing end glucosyl moiety. Furthermore, MAT shows higher affinity toward artificial substrates containing an alkyl or hydrophobic chain as well as a glucosyl unit. The presence of a long hydrophobic patch near the acceptor site provides the structural explanation for this preference. The three-dimensional structure reveals the expected trimeric left-handed parallel beta-helix structure found in all other known hexapeptide repeat enzymes. In particular, the structure shows similarities both overall and at the putative active site to the recently determined structure of galactoside acetyltransferase (GAT), the lacA gene product [Wang, X.-G., Olsen, L. R., and Roderick, S. L. (2002) Structure 10, 581-588]. The structure, together with the new biochemical data, suggests that GAT and MAT are more closely related than previously thought and might have similar cellular functions. However, while GAT is specific for acetylation of galactosyl units, MAT is specific for glucosyl units and is able to acetylate maltooligosaccharides, an important property for biotechnological applications. Structural differences at the acceptor site reflect the differences in substrate specificity.

  18. Day-to-Day Dynamics of Commensal Escherichia coli in Zimbabwean Cows Evidence Temporal Fluctuations within a Host-Specific Population Structure

    Science.gov (United States)

    Massot, Méril; Couffignal, Camille; Clermont, Olivier; D'Humières, Camille; Chatel, Jérémie; Plault, Nicolas; Andremont, Antoine; Mentré, France

    2017-01-01

    ABSTRACT To get insights into the temporal pattern of commensal Escherichia coli populations, we sampled the feces of four healthy cows from the same herd in the Hwange District of Zimbabwe daily over 25 days. The cows had not received antibiotic treatment during the previous 3 months. We performed viable E. coli counts and characterized the 326 isolates originating from the 98 stool samples at a clonal level, screened them for stx and eae genes, and tested them for their antibiotic susceptibilities. We observed that E. coli counts and dominant clones were different among cows, and very few clones were shared. No clone was shared by three or four cows. Clone richness and evenness were not different between cows. Within each host, the variability in the E. coli count was evidenced between days, and no clone was found to be dominant during the entire sampling period, suggesting the existence of clonal interference. Dominant clones tended to persist longer than subdominant ones and were mainly from phylogenetic groups A and B1. Five E. coli clones were found to contain both the stx1 and stx2 genes, representing 6.3% of the studied isolates. All cows harbored at least one Shiga toxin-producing E. coli (STEC) strain. Resistance to tetracycline, penicillins, trimethoprim, and sulfonamides was rare and observed in three clones that were shed at low levels in two cows. This study highlights the fact that the commensal E. coli population, including the STEC population, is host specific, is highly dynamic over a short time frame, and rarely carries antibiotic resistance determinants in the absence of antibiotic treatment. IMPORTANCE The literature about the dynamics of commensal Escherichia coli populations is very scarce. Over 25 days, we followed the total E. coli counts daily and characterized the sampled clones in the feces of four cows from the same herd living in the Hwange District of Zimbabwe. This study deals with the day-to-day dynamics of both quantitative and

  19. Day-to-Day Dynamics of Commensal Escherichia coli in Zimbabwean Cows Evidence Temporal Fluctuations within a Host-Specific Population Structure.

    Science.gov (United States)

    Massot, Méril; Couffignal, Camille; Clermont, Olivier; D'Humières, Camille; Chatel, Jérémie; Plault, Nicolas; Andremont, Antoine; Caron, Alexandre; Mentré, France; Denamur, Erick

    2017-07-01

    To get insights into the temporal pattern of commensal Escherichia coli populations, we sampled the feces of four healthy cows from the same herd in the Hwange District of Zimbabwe daily over 25 days. The cows had not received antibiotic treatment during the previous 3 months. We performed viable E. coli counts and characterized the 326 isolates originating from the 98 stool samples at a clonal level, screened them for stx and eae genes, and tested them for their antibiotic susceptibilities. We observed that E. coli counts and dominant clones were different among cows, and very few clones were shared. No clone was shared by three or four cows. Clone richness and evenness were not different between cows. Within each host, the variability in the E. coli count was evidenced between days, and no clone was found to be dominant during the entire sampling period, suggesting the existence of clonal interference. Dominant clones tended to persist longer than subdominant ones and were mainly from phylogenetic groups A and B1. Five E. coli clones were found to contain both the stx 1 and stx 2 genes, representing 6.3% of the studied isolates. All cows harbored at least one Shiga toxin-producing E. coli (STEC) strain. Resistance to tetracycline, penicillins, trimethoprim, and sulfonamides was rare and observed in three clones that were shed at low levels in two cows. This study highlights the fact that the commensal E. coli population, including the STEC population, is host specific, is highly dynamic over a short time frame, and rarely carries antibiotic resistance determinants in the absence of antibiotic treatment. IMPORTANCE The literature about the dynamics of commensal Escherichia coli populations is very scarce. Over 25 days, we followed the total E. coli counts daily and characterized the sampled clones in the feces of four cows from the same herd living in the Hwange District of Zimbabwe. This study deals with the day-to-day dynamics of both quantitative and

  20. FTIR nanobiosensors for Escherichia coli detection

    Directory of Open Access Journals (Sweden)

    Stefania Mura

    2012-07-01

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

  1. FTIR nanobiosensors for Escherichia coli detection

    Science.gov (United States)

    Greppi, Gianfranco; Marongiu, Maria Laura; Roggero, Pier Paolo; Ravindranath, Sandeep P; Mauer, Lisa J; Schibeci, Nicoletta; Perria, Francesco; Piccinini, Massimo; Innocenzi, Plinio; Irudayaraj, Joseph

    2012-01-01

    Summary Infections due to enterohaemorrhagic E. coli (Escherichia coli) have a low incidence but can have severe and sometimes fatal health consequences, and thus represent some of the most serious diseases due to the contamination of water and food. New, fast and simple devices that monitor these pathogens are necessary to improve the safety of our food supply chain. In this work we report on mesoporous titania thin-film substrates as sensors to detect E. coli O157:H7. Titania films treated with APTES ((3-aminopropyl)triethoxysilane) and GA (glutaraldehyde) were functionalized with specific antibodies and the absorption properties monitored. The film-based biosensors showed a detection limit for E. coli of 1 × 102 CFU/mL, constituting a simple and selective method for the effective screening of water samples. PMID:23019542

  2. Site-Specific Cleavage of Ribosomal RNA in Escherichia coli-Based Cell-Free Protein Synthesis Systems.

    Directory of Open Access Journals (Sweden)

    Jurek Failmezger

    Full Text Available Cell-free protein synthesis, which mimics the biological protein production system, allows rapid expression of proteins without the need to maintain a viable cell. Nevertheless, cell-free protein expression relies on active in vivo translation machinery including ribosomes and translation factors. Here, we examined the integrity of the protein synthesis machinery, namely the functionality of ribosomes, during (i the cell-free extract preparation and (ii the performance of in vitro protein synthesis by analyzing crucial components involved in translation. Monitoring the 16S rRNA, 23S rRNA, elongation factors and ribosomal protein S1, we show that processing of a cell-free extract results in no substantial alteration of the translation machinery. Moreover, we reveal that the 16S rRNA is specifically cleaved at helix 44 during in vitro translation reactions, resulting in the removal of the anti-Shine-Dalgarno sequence. These defective ribosomes accumulate in the cell-free system. We demonstrate that the specific cleavage of the 16S rRNA is triggered by the decreased concentrations of Mg2+. In addition, we provide evidence that helix 44 of the 30S ribosomal subunit serves as a point-of-entry for ribosome degradation in Escherichia coli. Our results suggest that Mg2+ homeostasis is fundamental to preserving functional ribosomes in cell-free protein synthesis systems, which is of major importance for cell-free protein synthesis at preparative scale, in order to create highly efficient technical in vitro systems.

  3. The specific effect of gallic acid on Escherichia coli biofilm formation by regulating pgaABCD genes expression.

    Science.gov (United States)

    Kang, Jiamu; Li, Qianqian; Liu, Liu; Jin, Wenyuan; Wang, Jingfan; Sun, Yuyang

    2018-02-01

    Escherichia coli (E. coli) is associated with an array of health-threatening contaminations, some of which are related to biofilm states. The pgaABCD-encoded poly-beta-1,6-N-acetyl-D-glucosamine (PGA) polymer plays an important role in biofilm formation. This study was conducted to determine the inhibitory effect of gallic acid (GA) against E. coli biofilm formation. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of GA against planktonic E. coli were 0.5 and 4 mg/mL, and minimal biofilm inhibitory concentration and minimal biofilm eradication concentration values of GA against E. coli in biofilms were 2 and 8 mg/mL, respectively. Quantitative crystal violet staining of biofilms and ESEM images clearly indicate that GA effectively, dose-dependently inhibited biofilm formation. CFU counting and confocal laser scanning microscopy measurements showed that GA significantly reduced viable bacteria in the biofilm. The contents of polysaccharide slime, protein, and DNA in the E. coli biofilm also decreased. qRT-PCR data showed that at the sub-MIC level of GA (0.25 mg/mL) and expression of pgaABC genes was downregulated, while pgaD gene expression was upregulated. The sub-MBC level of GA (2 mg/mL) significantly suppressed the pgaABCD genes. Our results altogether demonstrate that GA inhibited viable bacteria and E. coli biofilm formation, marking a novel approach to the prevention and treatment of biofilm-related infections in the food industry.

  4. [Avian pathogenic Escherichia coli (APEC)].

    Science.gov (United States)

    Ewers, Christa; Janssen, Traute; Wieler, Lothar H

    2003-01-01

    Infections with avian pathogenic Escherichia coli (APEC) cause colibacillosis, an acute and mostly systemic disease resulting in significant economic losses in poultry industry worldwide. Avian colibacillosis is a complex syndrome characterized by multiple organ lesions with airsacculitis and associated pericarditis, perihepatitis and peritonitis being most typical. Environmental factors as well as the constitution of poultry or initial viral infections influence the outcome of APEC-infections. However, several challenge experiments in chickens proofed the role of virulent APEC strains as the single aetiological agent. Currently serotypes O1:K1, O2:K1 and O78:K80 are recognized as the most prevalent, however the number of published serotypes is increasing. In addition, single APEC isolates vary profoundly in virulence, and knowledge about the molecular basis of this variability is still scarce. Known virulence factors of APEC are adhesins (F1- and P-fimbriae), iron acquisition systems (aerobactin and yersiniabactin), hemolysins (hemolysinE and temperaturesensitive hemagglutinin), resistance to the bactericidal effects of serum and phagocytosis (outer membrane protein, iss protein, lipopolysaccharide, K/1)-capsule and colilcin production) as well as toxins and cytotoxins (heat stable toxin, cyto-/verotoxin and flagella toxin). Esperimental studies have shown that the respiratory tract, principally the gas-exchange region of the lung and the interstitium of the air sacs are the most important sites of entry for avian pathogenic E. coli. APEC strains adhere to the epithelial cells of air sacs presumably through F1-fimbriae. After colonization and multiplication the bacteria enter the bloodstream, and the temperature-sensitive hemagglutinin (tsh) seems to be important int his step. After invading the bloodstream APEC cause a septicemia resulting in massive lesins in multiple internal organs and in sudden death of the birds. The ability of the bacteria to acquire iron

  5. Escherichia coli bactofection using Lipofectamine.

    Science.gov (United States)

    Narayanan, Kumaran; Lee, Choon Weng; Radu, Aurelian; Sim, Edmund Ui Hang

    2013-08-15

    Successful gene delivery into mammalian cells using bactofection requires entry of the bacterial vector via cell surface integrin receptors followed by release of plasmid DNA into the cellular environment. We show, for the first time, that addition of the DNA transfection reagent Lipofectamine improves entry of invasive Escherichia coli into HeLa cells and enhances up to 2.8-fold green fluorescent protein (GFP) expression from a reporter plasmid. The addition of Lipofectamine may be applicable to other bacterial vectors to increase their DNA delivery efficiency into mammalian cells. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Determinants of Cofactor Specificity for the Glucose-6-Phosphate Dehydrogenase from Escherichia coli: Simulation, Kinetics and Evolutionary Studies.

    Science.gov (United States)

    Fuentealba, Matias; Muñoz, Rodrigo; Maturana, Pablo; Krapp, Adriana; Cabrera, Ricardo

    2016-01-01

    Glucose 6-Phosphate Dehydrogenases (G6PDHs) from different sources show varying specificities towards NAD+ and NADP+ as cofactors. However, it is not known to what extent structural determinants of cofactor preference are conserved in the G6PDH family. In this work, molecular simulations, kinetic characterization of site-directed mutants and phylogenetic analyses were used to study the structural basis for the strong preference towards NADP+ shown by the G6PDH from Escherichia coli. Molecular Dynamics trajectories of homology models showed a highly favorable binding energy for residues K18 and R50 when interacting with the 2'-phosphate of NADP+, but the same residues formed no observable interactions in the case of NAD+. Alanine mutants of both residues were kinetically characterized and analyzed with respect to the binding energy of the transition state, according to the kcat/KM value determined for each cofactor. Whereas both residues contribute to the binding energy of NADP+, only R50 makes a contribution (about -1 kcal/mol) to NAD+ binding. In the absence of both positive charges the enzyme was unable to discriminate NADP+ from NAD+. Although kinetic data is sparse, the observed distribution of cofactor preferences within the phylogenetic tree is sufficient to rule out the possibility that the known NADP+-specific G6PDHs form a monophyletic group. While the β1-α1 loop shows no strict conservation of K18, (rather, S and T seem to be more frequent), in the case of the β2-α2 loop, different degrees of conservation are observed for R50. Noteworthy is the fact that a K18T mutant is indistinguishable from K18A in terms of cofactor preference. We conclude that the structural determinants for the strict discrimination against NAD+ in the case of the NADP+-specific enzymes have evolved independently through different means during the evolution of the G6PDH family. We further suggest that other regions in the cofactor binding pocket, besides the β1-α1 and β2-α2

  7. PATHOGENIC POTENTIALS OF ESCHERICHIA COLI ISOLATED ...

    African Journals Online (AJOL)

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

  8. Development of an Escherichia coli K12-specific quantitative polymerase chain reaction assay and DNA isolation suited to biofilms associated with iron drinking water pipe corrosion products.

    Science.gov (United States)

    Lu, Jingrang; Gerke, Tammie L; Buse, Helen Y; Ashbolt, Nicholas J

    2014-12-01

    A quantitative polymerase chain reaction assay (115 bp amplicon) specific to Escherichia coli K12 with an ABI(TM) internal control was developed based on sequence data encoding the rfb gene cluster. Assay specificity was evaluated using three E. coli K12 strains (ATCC W3110, MG1655 & DH1), 24 non-K12 E. coli and 23 bacterial genera. The biofilm detection limit was 10(3) colony-forming units (CFU) E. coli K12 mL(-1), but required a modified protocol, which included a bio-blocker Pseudomonas aeruginosa with ethylenediaminetetraacetic acid buffered to pH 5 prior to cell lysis/DNA extraction. The novel protocol yielded the same sensitivity for drinking water biofilms associated with Fe3O4 (magnetite)-coated SiO2 (quartz) grains and biofilm-surface iron corrosion products from a drinking water distribution system. The novel DNA extraction protocol and specific E. coli K12 assay are sensitive and robust enough for detection and quantification within iron drinking water pipe biofilms, and are particularly well suited for studying enteric bacterial interactions within biofilms.

  9. Dissemination of cephalosporin resistance genes between Escherichia coli strains from farm animals and humans by specific plasmid lineages.

    Directory of Open Access Journals (Sweden)

    Mark de Been

    2014-12-01

    Full Text Available Third-generation cephalosporins are a class of β-lactam antibiotics that are often used for the treatment of human infections caused by Gram-negative bacteria, especially Escherichia coli. Worryingly, the incidence of human infections caused by third-generation cephalosporin-resistant E. coli is increasing worldwide. Recent studies have suggested that these E. coli strains, and their antibiotic resistance genes, can spread from food-producing animals, via the food-chain, to humans. However, these studies used traditional typing methods, which may not have provided sufficient resolution to reliably assess the relatedness of these strains. We therefore used whole-genome sequencing (WGS to study the relatedness of cephalosporin-resistant E. coli from humans, chicken meat, poultry and pigs. One strain collection included pairs of human and poultry-associated strains that had previously been considered to be identical based on Multi-Locus Sequence Typing, plasmid typing and antibiotic resistance gene sequencing. The second collection included isolates from farmers and their pigs. WGS analysis revealed considerable heterogeneity between human and poultry-associated isolates. The most closely related pairs of strains from both sources carried 1263 Single-Nucleotide Polymorphisms (SNPs per Mbp core genome. In contrast, epidemiologically linked strains from humans and pigs differed by only 1.8 SNPs per Mbp core genome. WGS-based plasmid reconstructions revealed three distinct plasmid lineages (IncI1- and IncK-type that carried cephalosporin resistance genes of the Extended-Spectrum Beta-Lactamase (ESBL- and AmpC-types. The plasmid backbones within each lineage were virtually identical and were shared by genetically unrelated human and animal isolates. Plasmid reconstructions from short-read sequencing data were validated by long-read DNA sequencing for two strains. Our findings failed to demonstrate evidence for recent clonal transmission of

  10. Pathogenomics of uropathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    J Agarwal

    2012-01-01

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

  11. Use of specific antibody to demonstrate glycocalyx, K99 pili, and the spatial relationships of K99+ enterotoxigenic Escherichia coli in the ileum of colostrum-fed calves.

    OpenAIRE

    Chan, R.; Acres, S. D.; Costerton, J W

    1982-01-01

    The attachment of enterotoxigenic Escherichia coli (ETEC) strain B44 (O9:K30:K99:F41:H-) to the ileal epithelium of newborn colostrum-fed calves was studied by electron microscopy. Stabilization of the bacterial glycocalyx (K30) and pili (K99) by fixation of tissue sections in specific antibody and staining with ruthenium red were used so that the bacterial surface structures could be clearly visualized and their spatial relationship to the intestinal brush border defined. When sections of il...

  12. Comparison of clinical categories for Escherichia coli harboring specific qnr and chromosomal-mediated fluoroquinolone resistance determinants according to CLSI and EUCAST.

    Science.gov (United States)

    Machuca, Jesús; Briales, Alejandra; Díaz-de-Alba, Paula; Martínez-Martínez, Luis; Rodríguez-Martínez, José-Manuel; Pascual, Álvaro

    2016-03-01

    EUCAST breakpoints are more restrictive than those defined by CLSI. This study highlights the discrepancies between CLSI and EUCAST in a well characterized isogenic Escherichia coli collection and their correlations with specific quinolone resistance mechanisms. The greatest number of discrepancies was observed in strains containing 2-4 resistance mechanisms (MIC values on the borderline of clinical resistance). Bearing in mind that quinolones are concentration dependent antimicrobial agents, small changes in MIC may have relevant consequences for treatment outcomes. Copyright © 2015 Elsevier España, S.L.U. y Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  13. Current Interventions for Controlling Pathogenic Escherichia coli.

    Science.gov (United States)

    Kim, Nam Hee; Cho, Tae Jin; Rhee, Min Suk

    2017-01-01

    This review examined scientific reports and articles published from 2007 to 2016 regarding the major environmental sources of pathogenic Escherichia coli and the routes by which they enter the human gastrointestinal tract. The literature describes novel techniques used to combat pathogenic E. coli transmitted to humans from livestock and agricultural products, food-contact surfaces in processing environments, and food products themselves. Although prevention before contamination is always the best "intervention," many studies aim to identify novel chemical, physical, and biological techniques that inactivate or eliminate pathogenic E. coli cells from breeding livestock, growing crops, and manufactured food products. Such intervention strategies target each stage of the food chain from the perspective of "Farm to Table food safety" and aim to manage major reservoirs of pathogenic E. coli throughout the entire process. Issues related to, and recent trends in, food production must address not only the safety of the food itself but also the safety of those who consume it. Thus, research aims to discover new "natural" antimicrobial agents and to develop "multiple hurdle technology" or other novel technologies that preserve food quality. In addition, this review examines the practical application of recent technologies from the perspective of product quality and safety. It provides comprehensive insight into intervention measures used to ensure food safety, specifically those aimed at pathogenic E. coli. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Escherichia coli in broiler chickens with airsacculitis

    Directory of Open Access Journals (Sweden)

    Leandro S. Machado

    2014-09-01

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

  15. Avian pathogenic Escherichia coli (APEC).

    Science.gov (United States)

    Dho-Moulin, M; Fairbrother, J M

    1999-01-01

    Avian pathogenic Escherichia coli (APEC) cause aerosacculitis, polyserositis, septicemia and other mainly extraintestinal diseases in chickens, turkeys and other avian species. APEC are found in the intestinal microflora of healthy birds and most of the diseases associated with them are secondary to environmental and host predisposing factors. APEC isolates commonly belong to certain serogroups, O1, O2 and O78, and to a restricted number of clones. Several experimental models have been developed, permitting a more reliable evaluation of the pathogenicity of E. coli for chickens and turkeys. Hence, virulence factors identified on APEC are adhesins such as the F1 and P fimbriae, and curli, the aerobactin iron sequestering system, K1 capsule, temperature-sensitive hemagglutinin (Tsh), resistance to the bactericidal effects of serum and cytotoxic effects. Experimental infection studies have shown that the air-exchange regions of the lung and the airsacs are important sites of entry of E. coli into the bloodstream of birds during the initial stages of infection and that resistance to phagocytosis may be an important mechanism in the development of the disease. They have also demonstrated that F1 fimbriae are expressed in the respiratory tract, whereas P fimbriae are expressed in the internal organs of infected chickens. The role of these fimbrial adhesins in the development of disease is not yet, however, fully understood. The more recent use of genetic approaches for the identification of new virulence factors will greatly enhance our knowledge of APEC pathogenic mechanisms. Diagnosis of APEC infections is based on the clinical picture, lesions and isolation of E. coli. This may be strengthened by serotyping and identification of virulence factors using immunological or molecular methods such as DNA probes and PCR. Approaches for the prevention and control of APEC infections include the control of environmental contamination and environmental parameters such as

  16. Development of an Escherichia coli K12-specific quantitative polymerase chain reaction assay and DNA isolation suited to biofilms associated with iron drinking water pipe corrosion products

    Science.gov (United States)

    Escherichia coli is one of the most commonly used fecal indicator organisms for drinking water and groundwater systems. In order to understand various biogeochemical and biophysical factors affecting its interactions with biofilms, E. coli K12 was chosen as a model organism. A Ta...

  17. Antimicrobial resistance among commensal Escherichia coli from ...

    African Journals Online (AJOL)

    user1

    2012-07-19

    Jul 19, 2012 ... This study monitored antimicrobial resistance in commensal Escherichia coli from the faeces of on-farm .... sterile tryptic soy broth (TSB) (Oxoid, Basingstoke, UK) in universal bottles. 10 g of ... Figure 1. Rates of antimicrobial resistance in E. coli isolates from the faeces of cattle and beef in Ibadan, Nigeria.

  18. escherichia coli serotypes confirmed in experimental mammary ...

    African Journals Online (AJOL)

    DJFLEX

    SEROTYPES CONFIRMED IN EXPERIMENTAL MAMMARY GLAND. INFECTIONS. P. A. AKPAN AND ... 037, 02a and 109) in mammary glands of experimental cows (cow 105, 107 and 102 respectively). Pathogenicity of the E. coli which ..... Akpan, P. A and Ikpeme, E. U., 2005. pathology of. Experimental Escherichia Coli ...

  19. Prevalence of Escherichia coli O157

    NARCIS (Netherlands)

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

    2017-01-01

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

  20. Genes under positive selection in Escherichia coli

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  1. Characterization of Escherichia coli Phylogenetic Groups ...

    African Journals Online (AJOL)

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

  2. Escherichia coli survival in waters: Temperature dependence

    Science.gov (United States)

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

  3. ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli ANALISIS CEMARAN BAKTERI Escherichia coli

    OpenAIRE

    ANGGREINI, RAHAYU

    2015-01-01

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

  4. Metabolic erosion primarily through mutation accumulation, and not tradeoffs, drives limited evolution of substrate specificity in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Nicholas Leiby

    2014-02-01

    Full Text Available Evolutionary adaptation to a constant environment is often accompanied by specialization and a reduction of fitness in other environments. We assayed the ability of the Lenski Escherichia coli populations to grow on a range of carbon sources after 50,000 generations of adaptation on glucose. Using direct measurements of growth rates, we demonstrated that declines in performance were much less widespread than suggested by previous results from Biolog assays of cellular respiration. Surprisingly, there were many performance increases on a variety of substrates. In addition to the now famous example of citrate, we observed several other novel gains of function for organic acids that the ancestral strain only marginally utilized. Quantitative growth data also showed that strains with a higher mutation rate exhibited significantly more declines, suggesting that most metabolic erosion was driven by mutation accumulation and not by physiological tradeoffs. These reductions in growth by mutator strains were ameliorated by growth at lower temperature, consistent with the hypothesis that this metabolic erosion is largely caused by destabilizing mutations to the associated enzymes. We further hypothesized that reductions in growth rate would be greatest for substrates used most differently from glucose, and we used flux balance analysis to formulate this question quantitatively. To our surprise, we found no significant relationship between decreases in growth and dissimilarity to glucose metabolism. Taken as a whole, these data suggest that in a single resource environment, specialization does not mainly result as an inevitable consequence of adaptive tradeoffs, but rather due to the gradual accumulation of disabling mutations in unused portions of the genome.

  5. Metabolic erosion primarily through mutation accumulation, and not tradeoffs, drives limited evolution of substrate specificity in Escherichia coli.

    Science.gov (United States)

    Leiby, Nicholas; Marx, Christopher J

    2014-02-01

    Evolutionary adaptation to a constant environment is often accompanied by specialization and a reduction of fitness in other environments. We assayed the ability of the Lenski Escherichia coli populations to grow on a range of carbon sources after 50,000 generations of adaptation on glucose. Using direct measurements of growth rates, we demonstrated that declines in performance were much less widespread than suggested by previous results from Biolog assays of cellular respiration. Surprisingly, there were many performance increases on a variety of substrates. In addition to the now famous example of citrate, we observed several other novel gains of function for organic acids that the ancestral strain only marginally utilized. Quantitative growth data also showed that strains with a higher mutation rate exhibited significantly more declines, suggesting that most metabolic erosion was driven by mutation accumulation and not by physiological tradeoffs. These reductions in growth by mutator strains were ameliorated by growth at lower temperature, consistent with the hypothesis that this metabolic erosion is largely caused by destabilizing mutations to the associated enzymes. We further hypothesized that reductions in growth rate would be greatest for substrates used most differently from glucose, and we used flux balance analysis to formulate this question quantitatively. To our surprise, we found no significant relationship between decreases in growth and dissimilarity to glucose metabolism. Taken as a whole, these data suggest that in a single resource environment, specialization does not mainly result as an inevitable consequence of adaptive tradeoffs, but rather due to the gradual accumulation of disabling mutations in unused portions of the genome.

  6. 21 CFR 866.3255 - Escherichia coli serological reagents.

    Science.gov (United States)

    2010-04-01

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

  7. Characterization of thimet- and neurolysin-like activities in Escherichia coli M 3 A peptidases and description of a specific substrate.

    Science.gov (United States)

    Paschoalin, Thaysa; Carmona, Adriana K; Oliveira, Vitor; Juliano, Luiz; Travassos, Luiz R

    2005-09-01

    M 3 A oligopeptidases from Escherichia coli, with hydrolytic properties similar to Zn-dependent mammalian thimet oligopeptidase (EP 24.15) and neurolysin (EP 24.16), were studied aiming at identification of comparative enzyme and substrate specificity, hydrolytic products, and susceptibility to inhibitors. Fluorescent peptides, neurotensin (NT) and bradykinin (BK), were used as substrates for bacterial lysates. Bacterial enzymes were totally inhibited by o-phenanthrolin, JA-2 and partially by Pro-Ile, but not by leupeptin, PMSF, E-64, and Z-Pro-Prolinal, using internally quenched Abz-GFSPFRQ-EDDnp as substrate. The molecular mass of the bacterial oligopeptidase activity (77--78 kDa) was determined by gel filtration, and the effect of inhibitors, including captopril, suggested that it results from a combination of oligopeptidase A (OpdA) and peptidyl dipeptidase Dcp (77.1 and 77.5 kDa, respectively). Recombinant OpdA cloned from the same E. coli strain entirely reproduced the primary cleavage of fluorescent peptides, NT and BK, by the bacterial lysate. Genes encoding these M 3 A enzymes were those recognized in E. coli genome, bearing identity at the amino acid level (25--31%) with mammalian Zn-dependent oligopeptidases. We also describe a substrate, Abz-GFSPFRQ-EDDnp, that differentiates bacterial and mammalian oligopeptidases.

  8. Suppression subtractive hybridization identifies an autotransporter adhesin gene of E. coli IMT5155 specifically associated with avian pathogenic Escherichia coli (APEC).

    Science.gov (United States)

    Dai, Jianjun; Wang, Shaohui; Guerlebeck, Doreen; Laturnus, Claudia; Guenther, Sebastian; Shi, Zhenyu; Lu, Chengping; Ewers, Christa

    2010-09-09

    Extraintestinal pathogenic E. coli (ExPEC) represent a phylogenetically diverse group of bacteria which are implicated in a large range of infections in humans and animals. Although subgroups of different ExPEC pathotypes, including uropathogenic, newborn meningitis causing, and avian pathogenic E. coli (APEC) share a number of virulence features, there still might be factors specifically contributing to the pathogenesis of a certain subset of strains or a distinct pathotype. Thus, we made use of suppression subtractive hybridization and compared APEC strain IMT5155 (O2:K1:H5; sequence type complex 95) with human uropathogenic E. coli strain CFT073 (O6:K2:H5; sequence type complex 73) to identify factors which may complete the currently existing model of APEC pathogenicity and further elucidate the position of this avian pathotype within the whole ExPEC group. Twenty-eight different genomic loci were identified, which are present in IMT5155 but not in CFT073. One of these loci contained a gene encoding a putative autotransporter adhesin. The open reading frame of the gene spans a 3,498 bp region leading to a putative 124-kDa adhesive protein. A specific antibody was raised against this protein and expression of the adhesin was shown under laboratory conditions. Adherence and adherence inhibition assays demonstrated a role for the corresponding protein in adhesion to DF-1 chicken fibroblasts. Sequence analyses revealed that the flanking regions of the chromosomally located gene contained sequences of mobile genetic elements, indicating a probable spread among different strains by horizontal gene transfer. In accordance with this hypothesis, the adhesin was found to be present not only in different phylogenetic groups of extraintestinal pathogenic but also of commensal E. coli strains, yielding a significant association with strains of avian origin. We identified a chromosomally located autotransporter gene in a highly virulent APEC strain which confers increased

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

    Science.gov (United States)

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

    2017-01-01

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

  10. Site-specifically located 8-amino-2′-deoxyguanosine: thermodynamic stability and mutagenic properties in Escherichia coli

    Science.gov (United States)

    Venkatarangan, Lata; Sivaprasad, A.; Johnson, Francis; Basu, Ashis K.

    2001-01-01

    2-Nitropropane (2-NP), an important industrial solvent and a component of cigarette smoke, is mutagenic in bacteria and carcinogenic in rats. 8-Amino-2′-deoxyguanosine (8-amino-dG) is one of the types of DNA damage found in liver, the target organ in 2-NP-treated rats. To investigate the thermodynamic properties of 8-amino-dG opposite each of the four DNA bases, we have synthesized an 11mer, d(CCATCG*CTACC), in which G* represents the modified base. By annealing a complementary DNA strand to this modified 11mer, four sets of duplexes were generated each containing one of the four DNA bases opposite the lesion. Circular dichroism studies indicated that 8-amino-dG did not alter the global helical properties of natural right-handed B-DNA. The thermal stability of each duplex was examined by UV melting measurements and compared with its unmodified counterpart. For the unmodified 11mer, the relative stability of the complementary DNA bases opposite G was in the order C > T > G > A, as determined from their –ΔG° values. The free energy change of each modified duplex was lower than its unmodified counterpart, except for the G*:G pair that exhibited a higher melting transition and a larger –ΔG° than the G:G duplex. Nevertheless, the stability of the modified 11mer duplex also followed the order C > T > G > A when placed opposite 8-amino-dG. To explore if 8-amino-dG opposite another 8-amino-dG has any advantage in base pairing, a G*:G* duplex was evaluated, which showed that the stability of this duplex was similar to the G*:G duplex. Mutagenesis of 8-amino-dG in this sequence context was studied in Escherichia coli, which showed that the lesion is weakly mutagenic (mutation frequency ∼10–3) but still can induce a variety of targeted and semi-targeted mutations. PMID:11266546

  11. The Escherichia coli Azoreductase AzoR Is Involved in Resistance to Thiol-Specific Stress Caused by Electrophilic Quinones ▿

    Science.gov (United States)

    Liu, Guangfei; Zhou, Jiti; Fu, Q. Shiang; Wang, Jing

    2009-01-01

    The physiological role of Escherichia coli azoreductase AzoR was studied. It was found that AzoR was capable of reducing several benzo-, naphtho-, and anthraquinone compounds, which were better substrates for AzoR than the model azo substrate methyl red. The ΔazoR mutant displayed reduced viability when exposed to electrophilic quinones, which are capable of depleting cellular reduced glutathione (GSH). Externally added GSH can partially restore the impaired growth of the ΔazoR mutant caused by 2-methylhydroquinone. The transcription of azoR was induced by electrophiles, including 2-methylhydroquinone, catechol, menadione, and diamide. A transcription start point was identified 44 bp upstream from the translation start point. These data indicated that AzoR is a quinone reductase providing resistance to thiol-specific stress caused by electrophilic quinones. PMID:19666717

  12. Multiplex polymerase chain reaction for identification of Escherichia coli, Escherichia albertii and Escherichia fergusonii.

    Science.gov (United States)

    Lindsey, Rebecca L; Garcia-Toledo, L; Fasulo, D; Gladney, L M; Strockbine, N

    2017-09-01

    Escherichia coli, Escherichia albertii, and Escherichia fergusonii are closely related bacteria that can cause illness in humans, such as bacteremia, urinary tract infections and diarrhea. Current identification strategies for these three species vary in complexity and typically rely on the use of multiple phenotypic and genetic tests. To facilitate their rapid identification, we developed a multiplex PCR assay targeting conserved, species-specific genes. We used the Daydreamer™ (Pattern Genomics, USA) software platform to concurrently analyze whole genome sequence assemblies (WGS) from 150 Enterobacteriaceae genomes (107 E. coli, 5 Shigella spp., 21 E. albertii, 12 E. fergusonii and 5 other species) and design primers for the following species-specific regions: a 212bp region of the cyclic di-GMP regulator gene (cdgR, AW869_22935 from genome K-12 MG1655, CP014225) for E. coli/Shigella; a 393bp region of the DNA-binding transcriptional activator of cysteine biosynthesis gene (EAKF1_ch4033 from genome KF1, CP007025) for E. albertii; and a 575bp region of the palmitoleoyl-acyl carrier protein (ACP)-dependent acyltransferase (EFER_0790 from genome ATCC 35469, CU928158) for E. fergusonii. We incorporated the species-specific primers into a conventional multiplex PCR assay and assessed its performance with a collection of 97 Enterobacteriaceae strains. The assay was 100% sensitive and specific for detecting the expected species and offers a quick and accurate strategy for identifying E. coli, E. albertii, and E. fergusonii in either a single reaction or by in silico PCR with sequence assemblies. Published by Elsevier B.V.

  13. Differences in the binding specificities of Pseudomonas aeruginosa M35 and Escherichia coli C600 for lipid-linked oligosaccharides with lactose-related core regions.

    Science.gov (United States)

    Rosenstein, I J; Yuen, C T; Stoll, M S; Feizi, T

    1992-01-01

    Membrane glycolipids contain the lactose sequence (galactose linked to glucose), and the oligosaccharide is variously extended such that there is a cell-type-specific repertoire. In this study, binding of Pseudomonas aeruginosa M35 to lipid-linked lactose (Gal beta 1-4Glc [structure 1]), lacto-N-neotetraose (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc [structure 2]), lacto-N-tetraose (Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc [structure 3]), and asialo GM1 (Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc [structure 4]) was evaluated and compared with binding of Escherichia coli C600 to these compounds. Oligosaccharides were linked to the lipid phosphatidylethanolamine dipalmitoate, and the resulting neoglycolipids were resolved on thin-layer chromatograms or coated onto plastic microtiter wells. Lipid-linked structures 1 to 4 were bound by P. aeruginosa and E. coli in the chromatogram assay, but only structure 4 was bound in the microtiter well assay. As shown previously for E. coli binding to lipid-linked structures 1 to 3, binding to lipid-linked structure 4 was not inhibited with oligosaccharide, indicating a requirement for lipid and oligosaccharide. With few exceptions, sialylation and fucosylation of structures 1 to 4 resulted in impaired or abolished binding. Comparisons of binding intensities in the chromatogram assay indicated that recognition by P. aeruginosa and recognition by E. coli are not identical. Presence of the additional disaccharide unit, as in structure 2, resulted in enhanced binding of P. aeruginosa but diminished binding of E. coli relative to lactose binding; fucosylation at galactose of lactose resulted in markedly diminished binding of P. aeruginosa only. In the microtiter well assay, binding of E. coli to asialo GM1 was much weaker than P. aeruginosa binding. The saccharide-plus-lipid-dependent adhesion may be an important factor in increased susceptibility to infection of epithelia already damaged by microbial and chemical agents; the

  14. Escherichia coli fimbriae recognizing sialyl galactosides.

    OpenAIRE

    Korhonen, T K; Väisänen-Rhen, V; Rhen, M; Pere, A; Parkkinen, J; Finne, J

    1984-01-01

    Fimbriae recognizing sialyl galactosides (S fimbriae) were purified from an Escherichia coli strain. The S fimbriae were morphologically identical to type 1 and P fimbriae of E. coli and showed a hemagglutination that was abolished when erythrocytes were treated with neuraminidase. Hemagglutination by the purified fimbriae was inhibited by orosomucoid but not by its desialylated derivative. Of the oligosaccharides tested, sialyl-(alpha 2-3)-lactose and sialyl-(alpha 2-3)-N-acetyllactosamine h...

  15. Investigation of ’Escherichia coli’ Enterotoxins

    Science.gov (United States)

    1978-05-01

    creases substantially when certain strains of E. coli are grown in the presence of the antibiotic, chloramphenicol (10). Using the skin test to assay for...8. antigens. Somewhat unexpectedly, it was observed that the combined ant- igens exhibited synergism : when administered together, they elicited...Escherichia coli in the presence of chloramphenicol . J. Bacteriol. 110:667-676, (continued) 12. 11. Levner, M.H., Wiener, F.P., Rubin, B.A. Induction of

  16. Native valve Escherichia coli endocarditis following urosepsis

    Directory of Open Access Journals (Sweden)

    D Rangarajan

    2013-01-01

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

  17. Native valve Escherichia coli endocarditis following urosepsis

    OpenAIRE

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

    2013-01-01

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

  18. Whole-Transcriptome Analysis of Verocytotoxigenic Escherichia coli O157:H7 (Sakai) Suggests Plant-Species-Specific Metabolic Responses on Exposure to Spinach and Lettuce Extracts

    Science.gov (United States)

    Crozier, Louise; Hedley, Pete E.; Morris, Jenny; Wagstaff, Carol; Andrews, Simon C.; Toth, Ian; Jackson, Robert W.; Holden, Nicola J.

    2016-01-01

    Verocytotoxigenic Escherichia coli (VTEC) can contaminate crop plants, potentially using them as secondary hosts, which can lead to food-borne infection. Currently, little is known about the influence of the specific plant species on the success of bacterial colonization. As such, we compared the ability of the VTEC strain, E. coli O157:H7 ‘Sakai,’ to colonize the roots and leaves of four leafy vegetables: spinach (Spinacia oleracea), lettuce (Lactuca sativa), vining green pea (Pisum sativum), and prickly lettuce (Lactuca serriola), a wild relative of domesticated lettuce. Also, to determine the drivers of the initial response on interaction with plant tissue, the whole transcriptome of E. coli O157:H7 Sakai was analyzed following exposure to plant extracts of varying complexity (spinach leaf lysates or root exudates, and leaf cell wall polysaccharides from spinach or lettuce). Plant extracts were used to reduce heterogeneity inherent in plant–microbe interactions and remove the effect of plant immunity. This dual approach provided information on the initial adaptive response of E. coli O157:H7 Sakai to the plant environment together with the influence of the living plant during bacterial establishment and colonization. Results showed that both the plant tissue type and the plant species strongly influence the short-term (1 h) transcriptional response to extracts as well as longer-term (10 days) plant colonization or persistence. We show that propagation temperature (37 vs. 18°C) has a major impact on the expression profile and therefore pre-adaptation of bacteria to a plant-relevant temperature is necessary to avoid misleading temperature-dependent wholescale gene-expression changes in response to plant material. For each of the plant extracts tested, the largest group of (annotated) differentially regulated genes were associated with metabolism. However, large-scale differences in the metabolic and biosynthetic pathways between treatment types indicate

  19. Whole-transcriptome analysis of verocytotoxigenic Escherichia coli O157:H7 (Sakai suggests plant-species-specific metabolic responses on exposure to spinach and lettuce extracts.

    Directory of Open Access Journals (Sweden)

    Louise Crozier

    2016-07-01

    Full Text Available Verocytotoxigenic Escherichia coli (VTEC can contaminate crop plants, potentially using them as secondary hosts, which can lead to food-borne infection. Currently, little is known about the influence of the specific plant species on the success of bacterial colonisation. As such, we compared the ability of the VTEC strain, E. coli O157:H7 ‘Sakai’, to colonise the roots and leaves of four leafy vegetables: spinach (Spinacia oleracea, lettuce (Lactuca sativa, vining green pea (Pisum sativum and prickly lettuce (L. serriola, a wild relative of domesticated lettuce. Also, to determine the drivers of the initial response on interaction with plant tissue, the whole transcriptome of E. coli O157:H7 Sakai was analysed following exposure to plant extracts of varying complexity (spinach leaf lysates or root exudates, and leaf cell wall polysaccharides from spinach or lettuce. Plant extracts were used to reduce heterogeneity inherent in plant-microbe interactions and remove the effect of plant immunity. This dual approach provided information on the initial adaptive response of E. coli O157:H7 Sakai to the plant environment together with the influence of the living plant during bacterial establishment and colonisation. Results showed that both the plant tissue type and the plant species strongly influence the short-term (1 hour transcriptional response to extracts as well as longer-term (10 days plant colonisation or persistence. We show that propagation temperature (37 versus 18 oC has a major impact on the expression profile and therefore pre-adaptation of bacteria to a plant-relevant temperature is necessary to avoid misleading temperature-dependent wholescale gene-expression changes in response to plant material. For each of the plant extracts tested, the largest group of (annotated differentially regulated genes were associated with metabolism. However, large-scale differences in the metabolic and biosynthetic pathways between treatment types

  20. Syntheses and Immunologic Properties of Escherichia coli O157 O-Specific Polysaccharide and Shiga Toxin 1 B Subunit Conjugates in Mice

    Science.gov (United States)

    Konadu, Edward; Donohue-Rolfe, Arthur; Calderwood, Stephen B.; Pozsgay, Vince; Shiloach, Joseph; Robbins, John B.; Szu, Shousun C.

    1999-01-01

    Escherichia coli O157 is the major cause of diarrhea-associated hemolytic uremic syndrome (HUS). Strains causing HUS contain either Shiga toxin 1 (Stx1) or Stx2, or both. In adult volunteers, conjugate vaccines of detoxified lipopolysaccharide (LPS) elicited bactericidal antibodies to E. coli O157. Here, the detoxified LPS was conjugated with improved schemes to the nontoxic B subunit of Stx1. Mice injected with these bivalent conjugates elicited both bactericidal antibodies to E. coli O157 and neutralization antibodies to Stx1. PMID:10531288

  1. 77 FR 9888 - Shiga Toxin-Producing Escherichia coli

    Science.gov (United States)

    2012-02-21

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

  2. Association of Escherichia coli J5-Specific Serum Antibody Responses with Clinical Mastitis Outcome for J5 Vaccinate and Control Dairy Cattle ▿

    Science.gov (United States)

    Wilson, David J.; Mallard, Bonnie A.; Burton, Jeanne L.; Schukken, Ynte H.; Grohn, Yrjo T.

    2009-01-01

    Dairy cattle in two commercial Holstein herds were randomly selected to be vaccinated twice with J5, at approximately 60 days and 28 days before the expected calving date, or to be untreated controls. Based on whether milk production changed following clinical mastitis or whether cows were culled or died within 30 days after onset, 51 mastitis cases were classified as severe or mild. J5-specific antibody responses were evaluated by enzyme-linked immunosorbent assay of all 32 severe and 19 mild cases. The amounts of J5-specific immunoglobulin M (IgM), IgG1, and IgG2 antibodies in sera from the 27 J5 vaccinates were compared with those of the 24 controls. At drying off (before J5 vaccination), all cows had similar amounts of J5-specific antibody. Immediately after calving (approximately 28 days after the second vaccination), J5 vaccinates had significantly higher production of J5-specific IgG1 and IgG2 than controls. When cows were tested following clinical mastitis, none of the three antibody classes differed significantly between the controls and the vaccinates. Vaccinates that contracted Escherichia coli mastitis had 75% less milk loss than controls. The cows that contracted clinical mastitis later in lactation, the unvaccinated controls, and those infected with E. coli had more milk loss following mastitis. The hazards of being culled for all reasons and of being culled for mastitis were significantly lower for J5 vaccinates. Vaccination with J5 was associated with protection against milk production loss and culling following clinical mastitis, and it was also significantly associated with changes in J5-specific IgM, IgG1, and IgG2 antibodies in sera of vaccinated cows. PMID:19052158

  3. Association of Escherichia coli J5-specific serum antibody responses with clinical mastitis outcome for J5 vaccinate and control dairy cattle.

    Science.gov (United States)

    Wilson, David J; Mallard, Bonnie A; Burton, Jeanne L; Schukken, Ynte H; Grohn, Yrjo T

    2009-02-01

    Dairy cattle in two commercial Holstein herds were randomly selected to be vaccinated twice with J5, at approximately 60 days and 28 days before the expected calving date, or to be untreated controls. Based on whether milk production changed following clinical mastitis or whether cows were culled or died within 30 days after onset, 51 mastitis cases were classified as severe or mild. J5-specific antibody responses were evaluated by enzyme-linked immunosorbent assay of all 32 severe and 19 mild cases. The amounts of J5-specific immunoglobulin M (IgM), IgG1, and IgG2 antibodies in sera from the 27 J5 vaccinates were compared with those of the 24 controls. At drying off (before J5 vaccination), all cows had similar amounts of J5-specific antibody. Immediately after calving (approximately 28 days after the second vaccination), J5 vaccinates had significantly higher production of J5-specific IgG1 and IgG2 than controls. When cows were tested following clinical mastitis, none of the three antibody classes differed significantly between the controls and the vaccinates. Vaccinates that contracted Escherichia coli mastitis had 75% less milk loss than controls. The cows that contracted clinical mastitis later in lactation, the unvaccinated controls, and those infected with E. coli had more milk loss following mastitis. The hazards of being culled for all reasons and of being culled for mastitis were significantly lower for J5 vaccinates. Vaccination with J5 was associated with protection against milk production loss and culling following clinical mastitis, and it was also significantly associated with changes in J5-specific IgM, IgG1, and IgG2 antibodies in sera of vaccinated cows.

  4. Prevalence and antibiogram of Escherichia coli O157 isolated from ...

    African Journals Online (AJOL)

    Safty and immunogenic- ity of Escherichia coli O157 O-specific polysacaride conjugate. Christopher, A., Mshana, S. E, Kidenya, B. R, Hokororo, A. and Morona, D. 2013. Bac- teremia and resistant gram-negative pathogens among under-fives in Tanzania. Ital. J. Pediatr., 39, 27-34. Carney, E., O'Brien, S. B., Sheridan, J. J., ...

  5. Prevalence of Escherichia coli virulence genes in patients with ...

    African Journals Online (AJOL)

    In this study, we investigated the prevalence of the virulence genes specific for five major pathogroups of diarrheagenic Escherichia coli (DEC) in primary cultures from diarrhoeagenic patients in Burkina Faso. Methodology: From September 2016 to Mars 2017, a total of 211 faecal samples from diarrhoeagenic patients from ...

  6. Escherichia coli F4 fimbriae specific lama single-domain antibody fragments effectively inhibit bacterial adhesion in vitro but poorly protect against diarrhea

    NARCIS (Netherlands)

    Harmsen, M.M.; Solt, van C.B.; Hoogendoorn, A.; Zijderveld, van F.G.; Niewold, T.A.; Meulen, van der J.

    2005-01-01

    Oral administration of polyclonal antibodies directed against enterotoxigenic Escherichia coli (ETEC) F4 fimbriae is used to protect against piglet post-weaning diarrhoea. For cost reasons, we aim to replace these polyclonal antibodies by recombinant llama single-domain antibody fragments (VHHs)

  7. Cell Shape Dynamics in Escherichia coli

    OpenAIRE

    Reshes, Galina; Vanounou, Sharon; Fishov, Itzhak; Feingold, Mario

    2007-01-01

    Bacteria are the simplest living organisms. In particular, Escherichia coli has been extensively studied and it has become one of the standard model systems in microbiology. However, optical microscopy studies of single E. coli have been limited by its small size, ∼1 × 3 μm, not much larger than the optical resolution, ∼0.25 μm. As a result, not enough quantitative dynamical information on the life cycle of single E. coli is presently available. We suggest that, by careful analysis of images ...

  8. Whole Genome Epidemiological Typing of Escherichia coli

    OpenAIRE

    Kaas, Rolf Sommer; Aarestrup, Frank Møller; Ussery, David; Lund, Ole

    2014-01-01

    Escherichia coli (E. coli) spiller en vigtig rolle i den globale sundhed både grundet dennes rolle som kommensal bakterie, der lever i dennes vært og som patogen bakterie, der er skyld i millioner af infektioner hvert eneste år. Infektionerne er både sporadiske eller som udbrud med tusindvis af smittede i visse tilfælde. For at mindske antallet af infektioner er det vigtigt at overvåge patogene E. coli med henblik på hurtigt opdagelse af udbrud og sporing af kilden til disse. Effektiviteten a...

  9. Independence of replisomes in Escherichia coli chromosomalreplication

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-03-13

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

  10. Antibiotic resistance properties of uropathogenic Escherichia coli ...

    African Journals Online (AJOL)

    Purpose: To investigate the antibiotic resistance pattern of uropathogenic Escherichia coli (UPEC) ... UPEC strains showed the highest levels of resistance ... These changes, along with an already short urethra and difficulty with hygiene due to a distended pregnant belly, increase the frequency of urinary tract infections.

  11. Escherichia Coli Removal from Water Using Electrophotocatalytic ...

    African Journals Online (AJOL)

    Optimal removal (MPN: 0) was obtained at pH 8, time of electrolysis: 5 minutes, 2 layer of nano ZnO, and voltage of 10 V. This result offers that this method is an efficient method for water disinfection. @JASEM Keywords: Escherichia Coli , Water disinfection, Electrophotocatalytic, UV- A J. Appl. Sci. Environ. Manage. Sept ...

  12. lactamase in clinical isolates of Escherichia coli

    African Journals Online (AJOL)

    Jane

    2011-08-22

    Aug 22, 2011 ... ... Kolayli F, Karadenizli A, Demirdag K, Gunaydin. M, Altindis M, Caylan R, Ucmak H (2007) .Extended-spectrum beta- lactamases in ceftazidime resistant Escherichia coli and Klebsiella pneumoniae isolates in Turkish hospitals. Indian. J. Med. Microbiol. 25(4):346-350. Mammeri H, Gilly L, Laurans G,Vedel ...

  13. antimicrobial susceptibility and plasmids from escherichia coli

    African Journals Online (AJOL)

    2001-10-02

    Oct 2, 2001 ... 78 No. IO October 200]. ANTIMICROBIAL SUSCEPTIBILITY AND PLASMIDS FROM ESCHERICHIA COLI ISOLATED FROM RATS. FM. Gakuya, BVM, MSc, Field Veterinarian, Kenya Wildlife Services, M.N. Kyule, BVM, ... Request for reprints to: Dr FM. ... profile index (API) 20E strips (Bio Merieux, Marcy~l?

  14. Optimization of plasmid electrotransformation into Escherichia coli ...

    African Journals Online (AJOL)

    Application of statistical methods to determine the appropriate processes have been suggested for genetic engineering and biotechnology technique such as electroporation. This study explains the use of Taguchi statistical method to optimize the conditions for efficient plasmid transformation into Escherichia coli via ...

  15. Inhibition of Escherichia Coli, Salmonella and Staphylococcus ...

    African Journals Online (AJOL)

    Escherichia coli O157:H7, Salmonella typhimurium and Staphylococcus. aureus are of great concern to the food industry, especially in foods stored under refrigerated conditions where, unlike most food-borne pathogens are able to multiply. This investigation was conducted to study the inhibitory effect of some spice ...

  16. Antimicrobial Resistance in Escherichia Coli, Klebsiella ...

    African Journals Online (AJOL)

    Antimicrobial Resistance in Escherichia Coli, Klebsiella pneumoniae and Pseudomonas Aeruginosa Isolated from Milk of Dairy Cows in Three Nigerian Cities. ... The results demonstrated wide variation of in the susceptibility patterns for the various organisms from different regions of Nigeria. The three organisms displayed ...

  17. Compaction of isolated Escherichia coli nucleoids

    NARCIS (Netherlands)

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

    2016-01-01

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

  18. Tuning Escherichia coli for membrane protein overexpression

    NARCIS (Netherlands)

    Wagner, Samuel; Klepsch, Mirjam M.; Schlegel, Susan; Appel, Ansgar; Draheim, Roger; Tarry, Michael; Hogbom, Martin; van Wijk, Klaas J.; Slotboom, Dirk J.; Persson, Jan O.; de Gier, Jan-Willem; Högbom, Martin

    2008-01-01

    A simple generic method for optimizing membrane protein overexpression in Escherichia coli is still lacking. We have studied the physiological response of the widely used "Walker strains" C41(DE3) and C43(DE3), which are derived from BL21(DE3), to membrane protein overexpression. For unknown

  19. Biosensors for the detection of Escherichia coli

    African Journals Online (AJOL)

    Although Escherichia coli is still considered the best indicator of water quality, cell numbers may be below detection limits, or the cells may ..... ring between chemical reactions (chemical energy) and trans- duce these changes into .... dissolved oxygen and produce hydrogen peroxide (De Corcuera and Cavalieri, 2010) in a ...

  20. Antibiotic resistance properties of uropathogenic Escherichia coli ...

    African Journals Online (AJOL)

    Antibiotic resistance properties of uropathogenic Escherichia coli isolated from pregnant women with history of recurrent urinary tract infections. ... of infected pregnant women with imipenem, mezlocillin and nitrofurantoin would be effective for the prevention and management of vaginal infections in pregnant women.

  1. Escherichia Coli--Key to Modern Genetics.

    Science.gov (United States)

    Bregegere, Francois

    1982-01-01

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

  2. (ESBL) producing Escherichia coli and Klebsiella pneumoniae

    African Journals Online (AJOL)

    Emerging antibiotic resistance due to extended spectrum β-lactamase (ESBL) production limited the use of β-lactam antibiotics against Escherichia coli and Klebsiella pneumoniae. This observational study was conducted at the Microbiology department of the Children's Hospital, Lahore Pakistan, from June, 2009 to ...

  3. escherichia coli, klebsiella pneumoniae and proteus vulgaris

    African Journals Online (AJOL)

    DR. AMINU

    2010-06-01

    Jun 1, 2010 ... ABSTRACT. Psidium guajava (L.) leaves powder was extracted with ethanol and methanol using percolation method. The extracts were tested for antimicrobial activity against clinical isolates of confirmed extended spectrum β-lactamase producing Escherichia coli, Klebsiella pneumoniae and Proteus.

  4. Shiga toxin-producing Escherichia coli

    DEFF Research Database (Denmark)

    Pedersen, Rune Micha; Nielsen, Marc Trunjer Kusk; Möller, Sören

    2018-01-01

    OBJECTIVES: Shiga toxin-producing Escherichia coli (STEC) causes diarrhoeal disease, bloody diarrhoea and haemolytic uraemic syndrome. The aim of this study was to describe the incidence of STEC and the clinical features of STEC patients from a well-defined Danish population in which all fecal...

  5. Multiplex Genome Editing in Escherichia coli

    DEFF Research Database (Denmark)

    Ingemann Jensen, Sheila; Nielsen, Alex Toftgaard

    2018-01-01

    Lambda Red recombineering is an easy and efficient method for generating genetic modifications in Escherichia coli. For gene deletions, lambda Red recombineering is combined with the use of selectable markers, which are removed through the action of, e.g., flippase (Flp) recombinase. This PCR...

  6. Control of Ribosome Synthesis in Escherichia coli

    DEFF Research Database (Denmark)

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

    1977-01-01

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

  7. The eclipse period of Escherichia coli

    DEFF Research Database (Denmark)

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

    2000-01-01

    The minimal time between successive initiations on the same origin (the eclipse) in Escherichia coli was determined to be approximately 25-30 min. An inverse relationship was found between the length of the eclipse and the amount of Dam methyltransferase in the cell, indicating that the eclipse...

  8. Leaner and meaner genomes in Escherichia coli

    DEFF Research Database (Denmark)

    Ussery, David

    2006-01-01

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

  9. Emergence of Quinolone Resistance amongst Escherichia coli ...

    African Journals Online (AJOL)

    Two hundred and seventy three isolates of Escherichia coli obtained from 7 hospitals in Lagos were screened for Fluoroquinolone resistance (FQR). Rate of resistance was 22.3% showing an increase in quinolone resistance when compared with resistant rates between 1994 and 1999 which ranged from 0 – 2% then.

  10. Synergistic effects in mixed Escherichia coli biofilms

    DEFF Research Database (Denmark)

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

    2006-01-01

    the pathways governing development of more complex heterogeneous communities. In this study, we established a laboratory model where biofilm-stimulating effects due to interactions between genetically diverse strains of Escherichia coli were monitored. Synergistic induction of biofilm formation resulting from...... the cocultivation of 403 undomesticated E. coli strains with a characterized E. coli K-12 strain was detected at a significant frequency. The survey suggests that different mechanisms underlie the observed stimulation, yet synergistic development of biofilm within the subset of E. coli isolates (n = 56) exhibiting...... the strongest effects was most often linked to conjugative transmission of natural plasmids carried by the E. coli isolates (70%). Thus, the capacity of an isolate to promote the biofilm through cocultivation was (i) transferable to the K-12 strain, (ii) was linked with the acquisition of conjugation genes...

  11. Whole Genome Epidemiological Typing of Escherichia coli

    DEFF Research Database (Denmark)

    Kaas, Rolf Sommer

    Escherichia coli (E. coli) is of huge importance in global health both as a commensal organism living within its host or as a pathogen causing millions of infections each year. Infections occur both sporadic and as outbreaks with sometimes up to thousands of infected people. To limit the number...... of infections it is important to monitor pathogenic E. coli in order to detect outbreaks as quickly as possible and find the source of the outbreak. The effectiveness of monitoring and tracking of pathogens is very dependent on the typing methods that are employed. Classical typing methods employed for E. coli......D thesis attempts to take the first steps toward such a method. In Kaas I all publicly available E. coli genomes sequenced (186) are analyzed. 1,702 core genes were found in all genomes. 3,051 genes were found in 95% of the genomes. The pan genome was found to consist of 16,373 genes. The overall phylogeny...

  12. Escherichia coli and Sudden Infant Death Syndrome.

    Science.gov (United States)

    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.

  13. Escherichia coli and Sudden Infant Death Syndrome

    Directory of Open Access Journals (Sweden)

    Paul Nathan Goldwater

    2015-07-01

    Full Text Available This review examines the association of strains of Escherichia coli with Sudden Infant Death Syndrome (SIDS and the possible role of 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, colonisation 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 lability 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.

  14. Synthesis of rosmarinic acid analogues in Escherichia coli.

    Science.gov (United States)

    Zhuang, Yibin; Jiang, Jingjie; Bi, Huiping; Yin, Hua; Liu, Shaowei; Liu, Tao

    2016-04-01

    To produce rosmarinic acid analogues in the recombinant Escherichia coli BLRA1, harboring a 4-coumarate: CoA ligase from Arabidopsis thaliana (At4CL) and a rosmarinic acid synthase from Coleus blumei (CbRAS). Incubation of the recombinant E. coli strain BLRA1 with exogenously supplied phenyllactic acid (PL) and analogues as acceptor substrates, and coumaric acid and analogues as donor substrates led to production of 18 compounds, including 13 unnatural RA analogues. This work demonstrates the viability of synthesizing a broad range of rosmarinic acid analogues in E. coli, and sheds new light on the substrate specificity of CbRAS.

  15. RNA-Seq analysis of isolate- and growth phase-specific differences in the global transcriptomes of enteropathogenic Escherichia coli prototype isolates

    Science.gov (United States)

    Hazen, Tracy H.; Daugherty, Sean C.; Shetty, Amol; Mahurkar, Anup A.; White, Owen; Kaper, James B.; Rasko, David A.

    2015-01-01

    Enteropathogenic Escherichia coli (EPEC) are a leading cause of diarrheal illness among infants in developing countries. E. coli isolates classified as typical EPEC are identified by the presence of the locus of enterocyte effacement (LEE) and the bundle-forming pilus (BFP), and absence of the Shiga-toxin genes, while the atypical EPEC also encode LEE but do not encode BFP or Shiga-toxin. Comparative genomic analyses have demonstrated that EPEC isolates belong to diverse evolutionary lineages and possess lineage- and isolate-specific genomic content. To investigate whether this genomic diversity results in significant differences in global gene expression, we used an RNA sequencing (RNA-Seq) approach to characterize the global transcriptomes of the prototype typical EPEC isolates E2348/69, B171, C581-05, and the prototype atypical EPEC isolate E110019. The global transcriptomes were characterized during laboratory growth in two different media and three different growth phases, as well as during adherence of the EPEC isolates to human cells using in vitro tissue culture assays. Comparison of the global transcriptomes during these conditions was used to identify isolate- and growth phase-specific differences in EPEC gene expression. These analyses resulted in the identification of genes that encode proteins involved in survival and metabolism that were coordinately expressed with virulence factors. These findings demonstrate there are isolate- and growth phase-specific differences in the global transcriptomes of EPEC prototype isolates, and highlight the utility of comparative transcriptomics for identifying additional factors that are directly or indirectly involved in EPEC pathogenesis. PMID:26124752

  16. Escherichia coli survival in waters: temperature dependence.

    Science.gov (United States)

    Blaustein, R A; Pachepsky, Y; Hill, R L; Shelton, D R; Whelan, G

    2013-02-01

    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 model. This suggestion was made 34 years ago based on 20 survival curves taken from published literature, but has not been revisited since then. The objective of this study was to re-evaluate the accuracy of the Q₁₀ equation, utilizing data accumulated since 1978. We assembled a database of 450 E. coli survival datasets from 70 peer-reviewed papers. We then focused on the 170 curves taken from experiments that were performed in the laboratory under dark conditions to exclude the effects of sunlight and other field factors that could cause additional variability in results. All datasets were tabulated dependencies "log concentration vs. time." There were three major patterns of inactivation: about half of the datasets had a section of fast log-linear inactivation followed by a section of slow log-linear inactivation; about a quarter of the datasets had a lag period followed by log-linear inactivation; and the remaining quarter were approximately linear throughout. First-order inactivation rate constants were calculated from the linear sections of all survival curves and the data grouped by water sources, including waters of agricultural origin, pristine water sources, groundwater and wells, lakes and reservoirs, rivers and streams, estuaries and seawater, and wastewater. Dependency of E. coli inactivation rates on temperature varied among the water sources. There was a significant difference in inactivation rate values at the reference temperature between rivers and agricultural waters, wastewaters and agricultural waters, rivers and lakes, and wastewater and lakes. At specific sites, the Q₁₀ equation was more accurate in rivers and coastal waters than in lakes making the value of

  17. Infektionen mit darmpathogenen Escherichia coli.

    NARCIS (Netherlands)

    Friedrich, Alexander; Stein, Jürgen; Dignass, Axel

    2001-01-01

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

  18. Robust Growth of Escherichia coli

    National Research Council Canada - National Science Library

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

    2010-01-01

    ... 1 A). We measured the timescale of nutrient uptake by E. coli by using the fluorescent glucose analog (2-NBDG) and found that diffusion into the channels is much faster (∼1 s) than the timescale of nutrient uptake (∼2–3 min; Supplemental Experimental Procedures , available online), ensuring steady-state conditions for all cells. The cell at...

  19. Infectious endocarditis caused by Escherichia coli

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  20. Infectious endocarditis caused by Escherichia coli.

    Science.gov (United States)

    Lauridsen, Trine Kiilerich; Arpi, Magnus; Fritz-Hansen, Thomas; Frimodt-Møller, Niels; Bruun, Niels Eske

    2011-07-01

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

  1. Infectious endocarditis caused by Escherichia coli

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  2. Genetic Diversity of the fliC Genes Encoding the Flagellar Antigen H19 of Escherichia coli and Application to the Specific Identification of Enterohemorrhagic E. coli O121:H19

    Science.gov (United States)

    Beutin, Lothar; Delannoy, Sabine

    2015-01-01

    Enterohemorrhagic Escherichia coli (EHEC) O121:H19 belong to a specific clonal type distinct from other classical EHEC and major enteropathogenic E. coli groups and is regarded as one of the major EHEC serogroups involved in severe infections in humans. Sequencing of the fliC genes associated with the flagellar antigen H19 (fliCH19) revealed the genetic diversity of the fliCH19 gene sequences in E. coli. A cluster analysis of 12 fliCH19 sequences, 4 from O121 and 8 from non-O121 E. coli strains, revealed five different genotypes. All O121:H19 strains fell into one cluster, whereas a second cluster was formed by five non-O121:H19 strains. Cluster 1 and cluster 2 strains differ by 27 single nucleotide exchanges in their fliCH19 genes (98.5% homology). Based on allele discrimination of the fliCH19 genes, a real-time PCR test was designed for specific identification of EHEC O121:H19. The O121 fliCH19 PCR tested negative in 73 E. coli H19 strains that belonged to serogroups other than O121, including 28 different O groups, O-nontypeable H19, and O-rough:H19 strains. The O121 fliCH19 PCR reacted with all 16 tested O121:H19 strains and 1 O-rough:H19 strain which was positive for the O121 wzx gene. A cross-reaction was observed only with E. coli H32 strains which share sequence similarities in the target region of the O121 fliCH19 PCR. The combined use of O-antigen genotyping (O121 wzx) and the detection of O121 fliCH19 allele type contributes to improving the identification and molecular serotyping of EHEC O121:H19 motile and nonmotile strains and variants of these strains lacking stx genes. PMID:25862232

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

    Science.gov (United States)

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

    2009-05-01

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

  4. Human Meningitis-Associated Escherichia coli

    Science.gov (United States)

    KIM, KWANG SIK

    2016-01-01

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

  5. Hydrogen production by recombinant Escherichia coli strains

    Science.gov (United States)

    Maeda, Toshinari; Sanchez‐Torres, Viviana; Wood, Thomas K.

    2012-01-01

    Summary The production of hydrogen via microbial biotechnology is an active field of research. Given its ease of manipulation, the best‐studied bacterium Escherichia coli has become a workhorse for enhanced hydrogen production through metabolic engineering, heterologous gene expression, adaptive evolution, and protein engineering. Herein, the utility of E. coli strains to produce hydrogen, via native hydrogenases or heterologous ones, is reviewed. In addition, potential strategies for increasing hydrogen production are outlined and whole‐cell systems and cell‐free systems are compared. PMID:21895995

  6. Peptide nucleic acid (PNA) antisense effects in Escherichia coli

    DEFF Research Database (Denmark)

    Good, L; Nielsen, P E

    1999-01-01

    Antisense peptide nucleic acid (PNA) can be used to control cell growth, gene expression and growth phenotypes in the bacteria Escherichia coli. PNAs targeted to the RNA components of the ribosome can inhibit translation and cell growth, and PNAs targeted to mRNA can limit gene expression with gene...... and sequence specificity. In an E. coli cell extract, efficient inhibition is observed when using PNA concentrations in the nanomolar range, whereas micromolar concentrations are required for inhibition in growing cells. A mutant strain of E. coli that is more permeable to antibiotics also is more susceptible...... to antisense PNAs than the wild type. This chapter details methods for testing the antisense activities of PNA in E. coli. As an example of the specific antisense inhibition possible, we show the effects of an anti-beta-galactosidase PNA in comparison to control PNAs. With improvements in cell uptake...

  7. Cross-modulation of pathogen-specific pathways enhances malnutrition during enteric co-infection with Giardia lamblia and enteroaggregative Escherichia coli.

    Science.gov (United States)

    Bartelt, Luther A; Bolick, David T; Mayneris-Perxachs, Jordi; Kolling, Glynis L; Medlock, Gregory L; Zaenker, Edna I; Donowitz, Jeffery; Thomas-Beckett, Rose Viguna; Rogala, Allison; Carroll, Ian M; Singer, Steven M; Papin, Jason; Swann, Jonathan R; Guerrant, Richard L

    2017-07-01

    Diverse enteropathogen exposures associate with childhood malnutrition. To elucidate mechanistic pathways whereby enteric microbes interact during malnutrition, we used protein deficiency in mice to develop a new model of co-enteropathogen enteropathy. Focusing on common enteropathogens in malnourished children, Giardia lamblia and enteroaggregative Escherichia coli (EAEC), we provide new insights into intersecting pathogen-specific mechanisms that enhance malnutrition. We show for the first time that during protein malnutrition, the intestinal microbiota permits persistent Giardia colonization and simultaneously contributes to growth impairment. Despite signals of intestinal injury, such as IL1α, Giardia-infected mice lack pro-inflammatory intestinal responses, similar to endemic pediatric Giardia infections. Rather, Giardia perturbs microbial host co-metabolites of proteolysis during growth impairment, whereas host nicotinamide utilization adaptations that correspond with growth recovery increase. EAEC promotes intestinal inflammation and markers of myeloid cell activation. During co-infection, intestinal inflammatory signaling and cellular recruitment responses to EAEC are preserved together with a Giardia-mediated diminishment in myeloid cell activation. Conversely, EAEC extinguishes markers of host energy expenditure regulatory responses to Giardia, as host metabolic adaptations appear exhausted. Integrating immunologic and metabolic profiles during co-pathogen infection and malnutrition, we develop a working mechanistic model of how cumulative diet-induced and pathogen-triggered microbial perturbations result in an increasingly wasted host.

  8. Cross-modulation of pathogen-specific pathways enhances malnutrition during enteric co-infection with Giardia lamblia and enteroaggregative Escherichia coli

    Science.gov (United States)

    Bartelt, Luther A.; Bolick, David T.; Zaenker, Edna I.; Donowitz, Jeffery; Thomas-Beckett, Rose Viguna; Rogala, Allison; Carroll, Ian M.; Swann, Jonathan R.; Guerrant, Richard L.

    2017-01-01

    Diverse enteropathogen exposures associate with childhood malnutrition. To elucidate mechanistic pathways whereby enteric microbes interact during malnutrition, we used protein deficiency in mice to develop a new model of co-enteropathogen enteropathy. Focusing on common enteropathogens in malnourished children, Giardia lamblia and enteroaggregative Escherichia coli (EAEC), we provide new insights into intersecting pathogen-specific mechanisms that enhance malnutrition. We show for the first time that during protein malnutrition, the intestinal microbiota permits persistent Giardia colonization and simultaneously contributes to growth impairment. Despite signals of intestinal injury, such as IL1α, Giardia-infected mice lack pro-inflammatory intestinal responses, similar to endemic pediatric Giardia infections. Rather, Giardia perturbs microbial host co-metabolites of proteolysis during growth impairment, whereas host nicotinamide utilization adaptations that correspond with growth recovery increase. EAEC promotes intestinal inflammation and markers of myeloid cell activation. During co-infection, intestinal inflammatory signaling and cellular recruitment responses to EAEC are preserved together with a Giardia-mediated diminishment in myeloid cell activation. Conversely, EAEC extinguishes markers of host energy expenditure regulatory responses to Giardia, as host metabolic adaptations appear exhausted. Integrating immunologic and metabolic profiles during co-pathogen infection and malnutrition, we develop a working mechanistic model of how cumulative diet-induced and pathogen-triggered microbial perturbations result in an increasingly wasted host. PMID:28750066

  9. Intestinal Colonization by Enterotoxigenic Escherichia coli.

    Science.gov (United States)

    1980-09-01

    piotective antigens for the development of vaccines to protect by active immunization . I’ DD I Fr 1473 EDITION OF NOV 65IS 0O’.OL ET K ( / / SECURITY...enterotoxin immunity presented by the existence of non-antigenic heat-stable types of enterotoxin. Preliminary efforts to protect by oral vaccination...SUMHARY -. Pregnant gilts were vaccinated orally with Escherichia coli that S- produce pilus antigens K99 or 987P. The vaccines were live or dead

  10. Gene encoding virulence markers among Escherichia coli isolates ...

    African Journals Online (AJOL)

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

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

    OpenAIRE

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

    2003-01-01

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

  12. Genomic Comparative Study of Bovine Mastitis Escherichia coli

    Science.gov (United States)

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

    2016-01-01

    Escherichia coli, one of the main causative agents of bovine mastitis, is responsible for significant losses on dairy farms. In order to better understand the pathogenicity of E. coli mastitis, an accurate characterization of E. coli strains isolated from mastitis cases is required. By using phylogenetic analyses and whole genome comparison of 5 currently available mastitis E. coli genome sequences, we searched for genotypic traits specific for mastitis isolates. Our data confirm that there is a bias in the distribution of mastitis isolates in the different phylogenetic groups of the E. coli species, with the majority of strains belonging to phylogenetic groups A and B1. An interesting feature is that clustering of strains based on their accessory genome is very similar to that obtained using the core genome. This finding illustrates the fact that phenotypic properties of strains from different phylogroups are likely to be different. As a consequence, it is possible that different strategies could be used by mastitis isolates of different phylogroups to trigger mastitis. Our results indicate that mastitis E. coli isolates analyzed in this study carry very few of the virulence genes described in other pathogenic E. coli strains. A more detailed analysis of the presence/absence of genes involved in LPS synthesis, iron acquisition and type 6 secretion systems did not uncover specific properties of mastitis isolates. Altogether, these results indicate that mastitis E. coli isolates are rather characterized by a lack of bona fide currently described virulence genes. PMID:26809117

  13. Completion of DNA replication in Escherichia coli.

    Science.gov (United States)

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

    2014-11-18

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

  14. Escherichia coli: a brief review of diarrheagenic pathotypes and their role in diarrheal diseases in Iran

    Science.gov (United States)

    Jafari, A; Aslani, MM; Bouzari, S

    2012-01-01

    Diarrheagenic Escherichia coli have developed different strategies for establishment of infection in their host. Understanding these pathogenic mechanisms has led to the development of specific diagnostic tools for identification and categorization of E. coli strains into different pathotypes. This review aims to provide an overview of the various categories of diarrheagenic Escherichia coli and the data obtained in Iran pertaining to these pathotypes. PMID:23066484

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

    Science.gov (United States)

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

    2012-06-01

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

  16. Systems Metabolic Engineering of Escherichia coli.

    Science.gov (United States)

    Choi, Kyeong Rok; Shin, Jae Ho; Cho, Jae Sung; Yang, Dongsoo; Lee, Sang Yup

    2016-05-01

    Systems metabolic engineering, which recently emerged as metabolic engineering integrated with systems biology, synthetic biology, and evolutionary engineering, allows engineering of microorganisms on a systemic level for the production of valuable chemicals far beyond its native capabilities. Here, we review the strategies for systems metabolic engineering and particularly its applications in Escherichia coli. First, we cover the various tools developed for genetic manipulation in E. coli to increase the production titers of desired chemicals. Next, we detail the strategies for systems metabolic engineering in E. coli, covering the engineering of the native metabolism, the expansion of metabolism with synthetic pathways, and the process engineering aspects undertaken to achieve higher production titers of desired chemicals. Finally, we examine a couple of notable products as case studies produced in E. coli strains developed by systems metabolic engineering. The large portfolio of chemical products successfully produced by engineered E. coli listed here demonstrates the sheer capacity of what can be envisioned and achieved with respect to microbial production of chemicals. Systems metabolic engineering is no longer in its infancy; it is now widely employed and is also positioned to further embrace next-generation interdisciplinary principles and innovation for its upgrade. Systems metabolic engineering will play increasingly important roles in developing industrial strains including E. coli that are capable of efficiently producing natural and nonnatural chemicals and materials from renewable nonfood biomass.

  17. Biofilm formation and binding specificities of CFA/I, CFA/II and CS2 adhesions of enterotoxigenic Escherichia coli and Cfae-R181A mutant.

    Science.gov (United States)

    Liaqat, Iram; Sakellaris, Harry

    2012-07-01

    Enterotoxigenic Escherichia coli (ETEC) strains are leading causes of childhood diarrhea in developing countries. Adhesion is the first step in pathogenesis of ETEC infections and ETEC pili designated colonization factor antigens (CFAs) are believed to be important in the biofim formation, colonization and host cell adhesions. As a first step, we have determined the biofilm capability of ETEC expressing various types of pili (CFA/I, CfaE-R181A mutant/CfaE tip mutant, CFA/II and CS2). Further, enzyme-linked immunosorbent assay (ELISA) assay were developed to compare the binding specificity of CFA/I, CFA/II (CS1 - CS3) and CS2 of ETEC, using extracted pili and piliated bacteria. CFA/II strain (E24377a) as well as extracted pili exhibited significantly higher binding both in biofilm and ELISA assays compared to non piliated wild type E24377a, CFA/I and CS2 strains. This indicates that co-expression of two or more CS2 in same strain is more efficient in increasing adherence. Significant decrease in binding specificity of DH5αF'lacI (q)/∆cotD (CS2) strain and MC4100/pEU2124 (CfaE-R181A) mutant strain indicated the important contribution of tip proteins in adherence assays. However, CS2 tip mutant strain (DH5αF'lacI (q)/pEU5881) showed that this specific residue may not be important as adhesions in these strains. In summary, our data suggest that pili, their minor subunits are important for biofilm formation and adherence mechanisms. Overall, the functional reactivity of strains co expressing various antigens, particularly minor subunit antigen observed in this study suggest that fewer antibodies may be required to elicit immunity to ETEC expressing a wider array of related pili.

  18. Structure of NADP+-dependent glutamate dehydrogenase from Escherichia coli - reflections on the basis of coenzyme specificity in the family of glutamate dehydrogenases

    Energy Technology Data Exchange (ETDEWEB)

    Sharkey, Michael A.; Oliveira, Tânia F.; Engel, Paul C.; Khan, Amir R. [Trinity; (FCT/UNL); (UC-Dublin)

    2013-09-05

    Glutamate dehydrogenases catalyse the oxidative deamination of L-glutamate to α-ketoglutarate, using NAD+ and/or NADP+ as a cofactor. Subunits of homo-hexameric bacterial enzymes comprise a substrate-binding domain I followed by a nucleotide-binding domain II. The reaction occurs in a catalytic cleft between the two domains. Although conserved residues in the nucleotide-binding domains of various dehydrogenases have been linked to cofactor preferences, the structural basis for specificity in the GDH family remains poorly understood. Here, the refined crystal structure of Escherichia coli GDH in the absence of reactants is described at 2.5-Å resolution. Modelling of NADP+ in domain II reveals the potential contribution of positively charged residues from a neighbouring α-helical hairpin to phosphate recognition. In addition, a serine that follows the P7 aspartate is presumed to form a hydrogen bond with the 2'-phosphate. Mutagenesis and kinetic analysis confirms the importance of these residues in NADP+ recognition. Surprisingly, one of the positively charged residues is conserved in all sequences of NAD+-dependent enzymes, but the conformations adopted by the corresponding regions in proteins whose structure has been solved preclude their contribution to the coordination of the 2'-ribose phosphate of NADP+. These studies clarify the sequence–structure relationships in bacterial GDHs, revealing that identical residues may specify different coenzyme preferences, depending on the structural context. Primary sequence alone is therefore not a reliable guide for predicting coenzyme specificity. We also consider how it is possible for a single sequence to accommodate both coenzymes in the dual-specificity GDHs of animals.

  19. Biofilm formation and binding specificities of CFA/I, CFA/II and CS2 adhesions of enterotoxigenic Escherichia coli and Cfae-R181A mutant

    Science.gov (United States)

    Liaqat, Iram; Sakellaris, Harry

    2012-01-01

    Enterotoxigenic Escherichia coli (ETEC) strains are leading causes of childhood diarrhea in developing countries. Adhesion is the first step in pathogenesis of ETEC infections and ETEC pili designated colonization factor antigens (CFAs) are believed to be important in the biofim formation, colonization and host cell adhesions. As a first step, we have determined the biofilm capability of ETEC expressing various types of pili (CFA/I, CfaE-R181A mutant/CfaE tip mutant, CFA/II and CS2). Further, enzyme-linked immunosorbent assay (ELISA) assay were developed to compare the binding specificity of CFA/I, CFA/II (CS1 - CS3) and CS2 of ETEC, using extracted pili and piliated bacteria. CFA/II strain (E24377a) as well as extracted pili exhibited significantly higher binding both in biofilm and ELISA assays compared to non piliated wild type E24377a, CFA/I and CS2 strains. This indicates that co-expression of two or more CS2 in same strain is more efficient in increasing adherence. Significant decrease in binding specificity of DH5αF’lacIq/∆cotD (CS2) strain and MC4100/pEU2124 (CfaE-R181A) mutant strain indicated the important contribution of tip proteins in adherence assays. However, CS2 tip mutant strain (DH5αF’lacIq/pEU5881) showed that this specific residue may not be important as adhesions in these strains. In summary, our data suggest that pili, their minor subunits are important for biofilm formation and adherence mechanisms. Overall, the functional reactivity of strains co expressing various antigens, particularly minor subunit antigen observed in this study suggest that fewer antibodies may be required to elicit immunity to ETEC expressing a wider array of related pili. PMID:24031915

  20. Reduction of quinones and nitroaromatic compounds by Escherichia coli nitroreductase A (NfsA): Characterization of kinetics and substrate specificity.

    Science.gov (United States)

    Valiauga, Benjaminas; Williams, Elsie M; Ackerley, David F; Čėnas, Narimantas

    2017-01-15

    NfsA, a major FMN-associated nitroreductase of E. coli, reduces nitroaromatic compounds via consecutive two-electron transfers. NfsA has potential applications in the biodegradation of nitroaromatic environment pollutants, e.g. explosives, and is also of interest for the anticancer strategy gene-directed enzyme prodrug therapy. However, the catalytic mechanism of NfsA is poorly characterized. Here we examined the NADPH-dependent reduction of quinones (n = 16) and nitroaromatic compounds (n = 12) by NfsA. We confirmed a general "ping-pong" reaction scheme, and preliminary rapid reaction studies of the enzyme reduction by NADPH showed that this step is much faster than the steady-state turnover number, i.e., the enzyme turnover is limited by the oxidative half-reaction. The reactivity of nitroaromatic compounds (log kcat/Km) followed a linear dependence on their single-electron reduction potential (E17), indicating a limited role for compound structure or active site flexibility in their reactivity. The reactivity of quinones was lower than that of nitroaromatics having similar E17 values, except for the significantly enhanced reactivity of 2-OH-1,4-naphthoquinones, consistent with observations previously made for the group B nitroreductase of Enterobacter cloacae. We present evidence that the reduction of quinones by NfsA is most consistent with a single-step (H-) hydride transfer mechanism. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Characterization of Salmonella enterica and detection of the virulence genes specific to diarrheagenic Escherichia coli from poultry carcasses in Ouagadougou, Burkina Faso.

    Science.gov (United States)

    Kagambèga, Assèta; Barro, Nicolas; Traoré, Alfred S; Siitonen, Anja; Haukka, Kaisa

    2012-07-01

    One hundred chicken carcasses purchased from three markets selling poultry in Ouagadougou, Burkina Faso, between June 2010 and October 2010 were examined for their microbiological quality. The presence of Salmonella was investigated using standard bacteriological procedures, and the isolates obtained were serotyped and tested for antimicrobial susceptibility. The presence of virulence-associated genes of the five main pathogroups of diarrheagenic Escherichia coli-Shiga toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enterotoxigenic E. coli, and enteroinvasive E. coli-was investigated using 16-plex polymerase chain reaction (PCR) on the mixed bacterial cultures from the poultry samples. Of the 100 chicken carcasses studied, 57 were contaminated by Salmonella; 16 different serotypes were identified, the most frequent being Salmonella Derby, found in 28 samples. Four Salmonella strains were resistant to tetracycline, and two were resistant to streptomycin. Based on the PCR detection of the virulence genes, in total, 45 carcasses were contaminated by three pathogroups of E. coli: STEC, EPEC, or EAEC. The STEC and EPEC virulence genes were detected on six and 39 carcasses, respectively. EAEC virulence genes were only detected in combination with those of EPEC (on 11 carcasses) or STEC (on two carcasses). The STEC-positive carcasses contained the genes stx(1), stx(2), eaeA, escV, and ent in different combinations. None of the EPEC-positive carcasses contained the bfp gene, indicating that only atypical EPEC was present. EAEC virulence genes detected were aggR and/or pic. The high proportion of chicken carcasses contaminated by Salmonella and diarrheagenic E. coli indicates a potential food safety risk for consumers and highlights the necessity of public awareness of these pathogens.

  2. Incidence of Escherichia coli  - Glucuronidase Positive on Goat Milk

    Directory of Open Access Journals (Sweden)

    Zorica Voşgan

    2016-11-01

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

  3. Optimizing the feeding operation of recombinant Escherichia coli ...

    African Journals Online (AJOL)

    Recombinant Escherichia coli BL21 was used to produce human-like collagen in fed-batch culture. After building and analyzing the kinetic models of fed-batch cultures, the maximum specific growth rate, Yx/s and Yp/s were 0.411 h-1 , 0.428 g·g-1 and 0.0716 g/g, respectively. The square error of cell growth models, glucose ...

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

    African Journals Online (AJOL)

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

  5. Genetic diversity of Escherichia coli isolated from commercial swine ...

    African Journals Online (AJOL)

    PCR) for the analysis of genetic diversity among Escherichia coli strains isolated from commercial swine farms in Sichuan province of China. Thirty four strains of E. coli were selected by selective medium and conventional biochemical test from ...

  6. Epidemiology and clinical manifestations of enteroaggregative Escherichia coli

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  7. Kinetics and Subunit Interaction of the Mannitol-Specific Enzyme II of the Escherichia coli Phosphoenolpyruvate-Dependent Phosphotransferase System

    NARCIS (Netherlands)

    Roossien, F.F.; Blaauw, Mieke; Robillard, G.T.

    1984-01-01

    Purified mannitol-specific enzyme II (EIImtl), in the presence of the detergent Lubrol, catalyzes the phosphorylation of mannitol from P-HPr via a classical ping-pong mechanism involving the participation of a phosphorylated EIImtl intermediate. This intermediate has been demonstrated by using

  8. [Transformation of phosphotransferase system in Escherichia coli].

    Science.gov (United States)

    Xiao, Mengrong; Zhang, Liang; Liu, Shuangping; Shi, Guiyang

    2014-10-01

    We constructed several recombinant Escherichia coli strains to transform phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS system) and compared the characteristics of growth and metabolism of the mutants. We knocked-out the key genes ptsI and ptsG in PTS system by using Red homologous recombination in E. coli and meanwhile we also knocked-in the glucose facilitator gene glf from Zymomonas mobilis in the E. coli chromosome. Recombinant E. coli strains were constructed and the effects of cell growth, glucose consumption and acetic acid accumulation were also evaluated in all recombinant strains. The deletion of gene ptsG and ptsI inactivated some PTS system functions and inhibited the growth ability of the cell. Expressing the gene glf can help recombinant E. coli strains re-absorb the glucose through Glf-Glk (glucose facilitator-glucokinase) pathway as it can use ATP to phosphorylate glucose and transport into cell. This pathway can improve the availability of glucose and also reduce the accumulation of acetic acid; it can also broaden the carbon flux in the metabolism pathway.

  9. Escherichia coli fimbriae recognizing sialyl galactosides.

    Science.gov (United States)

    Korhonen, T K; Väisänen-Rhen, V; Rhen, M; Pere, A; Parkkinen, J; Finne, J

    1984-08-01

    Fimbriae recognizing sialyl galactosides (S fimbriae) were purified from an Escherichia coli strain. The S fimbriae were morphologically identical to type 1 and P fimbriae of E. coli and showed a hemagglutination that was abolished when erythrocytes were treated with neuraminidase. Hemagglutination by the purified fimbriae was inhibited by orosomucoid but not by its desialylated derivative. Of the oligosaccharides tested, sialyl-(alpha 2-3)-lactose and sialyl-(alpha 2-3)-N-acetyllactosamine had the strongest inhibitory activities. It was concluded that S fimbriae have the strongest affinity for (alpha 2-3)-linked sialyl galactosides. In the enzyme-linked immunosorbent assay, the hyperimmune serum to the S fimbriae reacted strongly with the homologous antigen but not with type 1, P, or nonhemagglutinating KS71C fimbriae of E. coli. Analogously, the hyperimmune sera to the other E. coli fimbriae did not react with the purified S fimbriae. The immunoprecipitation assay showed that S fimbriae on different E. coli serotypes shared immunological cross-reactivity.

  10. Photoinactivation of mcr-1 positive Escherichia coli

    Science.gov (United States)

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

    2018-01-01

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

  11. Structural insights into the substrate specificity and function of Escherichia coli K12 YgjK, a glucosidase belonging to the glycoside hydrolase family 63.

    Science.gov (United States)

    Kurakata, Yuma; Uechi, Akiko; Yoshida, Hiromi; Kamitori, Shigehiro; Sakano, Yoshiyuki; Nishikawa, Atsushi; Tonozuka, Takashi

    2008-08-01

    Proteins belonging to the glycoside hydrolase family 63 (GH63) are found in bacteria, archaea, and eukaryotes. Eukaryotic GH63 proteins are processing *-glucosidase I enzymes that hydrolyze an oligosaccharide precursor of eukaryotic N-linked glycoproteins. In contrast, the functions of the bacterial and archaeal GH63 proteins are unclear. Here we determined the crystal structure of a bacterial GH63 enzyme, Escherichia coli K12 YgjK, at 1.78 A resolution and investigated some properties of the enzyme. YgjK consists of the N-domain and the A-domain, joined by a linker region. The N-domain is composed of 18 antiparallel beta-strands and is classified as a super-beta-sandwich. The A-domain contains 16 *-helices, 12 of which form an (*/*)(6)-barrel; the remaining 4 *-helices are found in an extra structural unit that we designated as the A'-region. YgjK, a member of the glycoside hydrolase clan GH-G, shares structural similarity with glucoamylase (GH15) and chitobiose phosphorylase (GH94) [corrected] both of which belong to clan GH-L or GH-L-like [corrected] In crystal structures of YgjK in complex with glucose, mannose, and galactose, all of the glucose, mannose, and galactose units were located in the catalytic cleft. YgjK showed the highest activity for the *-1,3-glucosidic linkage of nigerose, but also hydrolyzed trehalose, kojibiose, and maltooligosaccharides from maltose to maltoheptaose, although the activities were low. These findings suggest that YgjK is a glucosidase with relaxed specificity for sugars.

  12. Translational coupling in Escherichia coli of a heterologous Bacillus subtilis-Escherichia coli gene fusion.

    OpenAIRE

    Zaghloul, T I; Doi, R H

    1986-01-01

    The efficient expression in Escherichia coli of the Tn9-derived chloramphenicol acetyltransferase (EC 2.3.1.28) gene fused distal to the promoter and N terminus of the Bacillus subtilis aprA gene was dependent on the initiation of translation from the ribosome-binding site in the aprA gene.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-08-01

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

  14. Genetic relationship of diarrheagenic Escherichia coli pathotypes among the enteropathogenic Escherichia coli O serogroup

    Directory of Open Access Journals (Sweden)

    Silvia Y Bando

    2007-03-01

    Full Text Available The genetic relationship among the Escherichia coli pathotypes was investigated. We used random amplified polymorphic DNA (RAPD data for constructing a dendrogram of 73 strains of diarrheagenic E. coli. A phylogenetic tree encompassing 15 serotypes from different pathotypes was constructed using multilocus sequence typing data. Phylogram clusters were used for validating RAPD data on the clonality of enteropathogenic E. coli (EPEC O serogroup strains. Both analyses showed very similar topologies, characterized by the presence of two major groups: group A includes EPEC H6 and H34 strains and group B contains the other EPEC strains plus all serotypes belonging to atypical EPEC, enteroaggregative E. coli (EAEC and enterohemorrhagic E. coli (EHEC. These results confirm the existence of two evolutionary divergent groups in EPEC: one is genetically and serologically very homogeneous whereas the other harbors EPEC and non-EPEC serotypes. The same situation was found for EAEC and EHEC.

  15. Progressive segregation of the Escherichia coli chromosome

    DEFF Research Database (Denmark)

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

    2006-01-01

    We have followed the fate of 14 different loci around the Escherichia coli chromosome in living cells at slow growth rate using a highly efficient labelling system and automated measurements. Loci are segregated as they are replicated, but with a marked delay. Most markers segregate in a smooth...... temporal progression from origin to terminus. Thus, the overall pattern is one of continuous segregation during replication and is not consistent with recently published models invoking extensive sister chromosome cohesion followed by simultaneous segregation of the bulk of the chromosome. The terminus...

  16. Incomplete flagellar structures in Escherichia coli mutants.

    OpenAIRE

    Suzuki, T; Komeda, Y

    1981-01-01

    Escherichia coli mutants with defects in 29 flagellar genes identified so far were examined by electron microscopy for possession of incomplete flagellar structures in membrane-associated fractions. The results are discussed in consideration of the known transcriptional interaction of flagellar genes. Hook-basal body structures were detected in flaD, flaS, flaT, flbC, and hag mutants. The flaE mutant had a polyhook-basal body structure. An intact basal body appeared in flaK mutants. Putative ...

  17. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

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

    2003-01-01

    It is now apparent that microorganisms undergo significant changes during the transition from planktonic to biofilm growth. These changes result in phenotypic adaptations that allow the formation of highly organized and structured sessile communities, which possess enhanced resistance...... to antimicrobial treatments and host immune defence responses. Escherichia coli has been used as a model organism to study the mechanisms of growth within adhered communities. In this study, we use DNA microarray technology to examine the global gene expression profile of E. coli during sessile growth compared...... the transition to biofilm growth, and these included genes expressed under oxygen-limiting conditions, genes encoding (putative) transport proteins, putative oxidoreductases and genes associated with enhanced heavy metal resistance. Of particular interest was the observation that many of the genes altered...

  18. Natural DNA uptake by Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Sunita Sinha

    Full Text Available Escherichia coli has homologues of the competence genes other species use for DNA uptake and processing, but natural competence and transformation have never been detected. Although we previously showed that these genes are induced by the competence regulator Sxy as in other gamma-proteobacteria, no conditions are known that naturally induce sxy expression. We have now tested whether the competence gene homologues encode a functional DNA uptake machinery and whether DNA uptake leads to recombination, by investigating the effects of plasmid-borne sxy expression on natural competence in a wide variety of E. coli strains. High- and low-level sxy expression alone did not induce transformation in any of the strains tested, despite varying the transforming DNA, its concentration, and the incubation conditions used. Direct measurements of uptake of radiolabelled DNA were below the limit of detection, however transformants were readily detected when recombination functions were provided by the lambda Red recombinase. This is the first demonstration that E. coli sxy expression can induce natural DNA uptake and that E. coli's competence genes do encode a functional uptake machinery. However, the amount of transformation cells undergo is limited both by low levels of DNA uptake and by inefficient DNA processing/recombination.

  19. Engineering Escherichia coli for methanol conversion.

    Science.gov (United States)

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

    2015-03-01

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

  20. Chromatin architecture and gene expression in Escherichia coli

    DEFF Research Database (Denmark)

    Willenbrock, Hanni; Ussery, David

    2004-01-01

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

  1. Multiple antimicrobial resistance of Escherichia coli and Salmonella ...

    African Journals Online (AJOL)

    ADEYEYE

    2017-07-11

    Jul 11, 2017 ... verocytotoxin-producing Escherichia coli. O157 from slaughter pigs and poultry. International Journal of Food Microbiology,. 52(1 – 2): 67 – 75. Huang TM, Lin TL & Wu CC (2009). Antimicrobial susceptibility and resistance of chicken. Escherichia coli, Salmonella spp., and. Pasteurella multocida isolates.

  2. Escherichia coli O157 infections and unpasteurised milk

    NARCIS (Netherlands)

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

    2001-01-01

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

  3. Prevalence of Escherichia coli some public water sources in Gusau ...

    African Journals Online (AJOL)

    This study investigated the presence of Escherichia coli from some public water sources in Gusau municipal, north- western Nigeria. This was done by determining the total coliform counts and the presence of Escherichia coli and its antibiotic susceptibility profile. A total of 180 well 60 tap and 60 packaged water samples ...

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

    Science.gov (United States)

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

    2014-07-18

    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.

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

    Directory of Open Access Journals (Sweden)

    Garry Laverty

    2014-07-01

    Full Text Available 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.

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

    Science.gov (United States)

    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

  7. CRISPR-spacer integration reporter plasmids reveal distinct genuine acquisition specificities among CRISPR-Cas I-E variants of Escherichia coli

    Science.gov (United States)

    Díez-Villaseñor, César; Guzmán, Noemí M.; Almendros, Cristóbal; García-Martínez, Jesús; Mojica, Francisco J.M.

    2013-01-01

    Prokaryotes immunize themselves against transmissible genetic elements by the integration (acquisition) in clustered regularly interspaced short palindromic repeats (CRISPR) loci of spacers homologous to invader nucleic acids, defined as protospacers. Following acquisition, mono-spacer CRISPR RNAs (termed crRNAs) guide CRISPR-associated (Cas) proteins to degrade (interference) protospacers flanked by an adjacent motif in extrachomosomal DNA. During acquisition, selection of spacer-precursors adjoining the protospacer motif and proper orientation of the integrated fragment with respect to the leader (sequence leading transcription of the flanking CRISPR array) grant efficient interference by at least some CRISPR-Cas systems. This adaptive stage of the CRISPR action is poorly characterized, mainly due to the lack of appropriate genetic strategies to address its study and, at least in Escherichia coli, the need of Cas overproduction for insertion detection. In this work, we describe the development and application in Escherichia coli strains of an interference-independent assay based on engineered selectable CRISPR-spacer integration reporter plasmids. By using this tool without the constraint of interference or cas overexpression, we confirmed fundamental aspects of this process such as the critical requirement of Cas1 and Cas2 and the identity of the CTT protospacer motif for the E. coli K12 system. In addition, we defined the CWT motif for a non-K12 CRISPR-Cas variant, and obtained data supporting the implication of the leader in spacer orientation, the preferred acquisition from plasmids harboring cas genes and the occurrence of a sequential cleavage at the insertion site by a ruler mechanism. PMID:23445770

  8. In silico design and construction of metal-binding hybrid proteins for specific removal of cadmium based on CS3 pili display on the surface of Escherichia coli.

    Science.gov (United States)

    Eskandari, Vajiheh; Yakhchali, Bagher; Sadeghi, Mehdi; Karkhane, Ali Asghar

    2013-01-01

    In this study, through a combination of bioinformatics and genetic engineering procedures, high-affinity metal-binding peptides were designed and expressed on the surface of Escherichia coli for selective Cd(2+) adsorption. Putative cadmium-binding motifs were identified by searches against the Prosite database and permissive sites in the major subunit (CstH) of the enterotoxigenic E. coli pili were predicted based on the data derived from modeling of 3D structures, secondary structure prediction and assignment, inspection of protein hydropathy and exposed regions, and also protein interaction sites. The metal-binding motifs were inserted into one permissive site of the CstH (amino acid 38) with the aid of the SOEing PCR technique. The capacity and selectivity of the recombinant bacteria displaying hybrid pili to adsorb cadmium were evaluated with the atomic absorption procedure. The levels of Cd(2+) accumulation in the recombinant E. coli strains were 13.9- and 11.33-fold higher than those in the control strain. Cd(2+) was selectively absorbed from a solution containing equal concentrations of four metals, resulting in more than 90% of the total adsorbed metals being Cd(2+) , showing a relatively high affinity for Cd(2+) over other coexisting metal ions. © 2013 International Union of Biochemistry and Molecular Biology, Inc.

  9. Inactivation of Escherichia coli by citral.

    Science.gov (United States)

    Somolinos, M; García, D; Condón, S; Mackey, B; Pagán, R

    2010-06-01

    The aim was to evaluate (i) the resistance of Escherichia coli BJ4 to citral in a buffer system as a function of citral concentration, treatment medium pH, storage time and initial inoculum size, (ii) the role of the sigma factor RpoS on citral resistance of E. coli, (iii) the role of the cell envelope damage in the mechanism of microbial inactivation by citral and (iiii) possible synergistic effects of mild heat treatment and pulsed electric fields (PEF) treatment combined with citral. The initial inoculum size greatly affected the efficacy of citral against E. coli cells. Exposure to 200 microl l(-1) of citral at pH 4.0 for 24 h at 20 degrees C caused the inactivation of more than 5 log(10) cycles of cells starting at an inoculum size of 10(6) or 10(7) CFU ml(-1), whereas increasing the cell concentration to 10(9) CFU ml(-1) caused citral at pH 4.0 than pH 7.0. The rpoS null mutant strain E. coli BJ4L1 was less resistant to citral than the wild-type strain. Occurrence of sublethal injury to both the cytoplasmic and outer membranes was demonstrated by adding sodium chloride or bile salts to the recovery media. The majority of sublethally injured cells by citral required energy and lipid synthesis for repair. A strongly synergistic lethal effect was shown by mild heat treatment combined with citral but the presence of citral during the application of a PEF treatment did not show any advantage. This work confirms that cell envelope damage is an important event in citral inactivation of bacteria, and it describes the key factors on the inactivation of E. coli cells by citral. Knowledge about the mechanism of microbial inactivation by citral helps establish successful combined preservation treatments.

  10. Production of glycoprotein vaccines in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Ihssen Julian

    2010-08-01

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

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

    Science.gov (United States)

    Vahjen, W; Cuisiniere, T; Zentek, J

    2017-10-13

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

  12. [Population genomic researches of Escherichia coli].

    Science.gov (United States)

    Wu, Y R; Yang, R F; Cui, Y J

    2016-06-01

    Population genomics, an interdiscipline of genomics and population genetics, is booming in recent years with the rapid growth number of deciphered genomes and revolutionizes the understanding of bacterial population diversity and evolution dynamics. It also largely improves the prevention and control of infectious disease through providing more accurate genotyping and source-tracing results and more comprehensive characteristics of emerging pathogens. In this review, taking one of the best characterized bacteria, Escherichia coli, as model, we reviewed the phylogenetic relationship across its five major populations (designated A, B1, B2, D and E); and summarized researches on molecular mutation rate, selection signals, and patterns of adaptive evolution. We also described the application of population genomics in responding against large-scale outbreaks of E. coli O157:H7 and E. coli O104:H4. These results indicated that, although being a novel discipline, population genomics has played an important role in deciphering bacterial population structures, exploring evolutionary patterns and combating emerging infectious diseases.

  13. Isolation of Enteropathogenic Escherichia coli from lettuce samples in Tehran

    OpenAIRE

    Mazaheri, Somayeh; Salmanzadeh-Ahrabi, Siavosh; Falsafi, Tahereh; Aslani, Mohammad-Mehdi

    2014-01-01

    Aim The purpose of this study was to find the isolation rate of enteropathogenic Escherichia coli (EPEC) from lettuce samples collected in Tehran. Background During the last decade, the prevalence of infectious diarrheal diseases due to consumption of contaminated food especially raw vegetable has been increasingly reported. Enteropathogenic Escherichia coli strains are an important group of diarrheagenic E. coli that can cause infant diarrhea especially in the developing world. Material and ...

  14. Inhibition of Antigen-Specific and Nonspecific Stimulation of Bovine T and B Cells by Lymphostatin from Attaching and Effacing Escherichia coli.

    Science.gov (United States)

    Cassady-Cain, Robin L; Blackburn, Elizabeth A; Bell, Charlotte R; Elshina, Elizaveta; Hope, Jayne C; Stevens, Mark P

    2017-02-01

    Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) are enteric bacterial pathogens of worldwide importance. Most EPEC and non-O157 EHEC strains express lymphostatin (also known as LifA), a chromosomally encoded 365-kDa protein. We previously demonstrated that lymphostatin is a putative glycosyltransferase that is important in intestinal colonization of cattle by EHEC serogroup O5, O111, and O26 strains. However, the nature and consequences of the interaction between lymphostatin and immune cells from the bovine host are ill defined. Using purified recombinant protein, we demonstrated that lymphostatin inhibits mitogen-activated proliferation of bovine T cells and, to a lesser extent, proliferation of cytokine-stimulated B cells, but not NK cells. It broadly affected the T cell compartment, inhibiting all cell subsets (CD4, CD8, WC-1, and γδ T cell receptor [γδ-TCR]) and cytokines examined (interleukin 2 [IL-2], IL-4, IL-10, IL-17A, and gamma interferon [IFN-γ]) and rendered T cells refractory to mitogen for a least 18 h after transient exposure. Lymphostatin was also able to inhibit proliferation of T cells stimulated by IL-2 and by antigen presentation using a Theileria-transformed cell line and autologous T cells from Theileria-infected cattle. We conclude that lymphostatin is likely to act early in T cell activation, as stimulation of T cells with concanavalin A, but not phorbol 12-myristate 13-acetate combined with ionomycin, was inhibited. Finally, a homologue of lymphostatin from E. coli O157:H7 (ToxB; L7095) was also found to possess comparable inhibitory activity against T cells, indicating a potentially conserved strategy for interference in adaptive responses by attaching and effacing E. coli. Copyright © 2017 Cassady-Cain et al.

  15. Attribution of human infections with Shiga toxin-producing Escherichia coli (STEC) to livestock sources and identification of source-specific risk factors, The Netherlands (2010-2014).

    Science.gov (United States)

    Mughini-Gras, L; van Pelt, W; van der Voort, M; Heck, M; Friesema, I; Franz, E

    2018-02-01

    Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen of public health concern whose sources and transmission routes are difficult to trace. Using a combined source attribution and case-control analysis, we determined the relative contributions of four putative livestock sources (cattle, small ruminants, pigs, poultry) to human STEC infections and their associated dietary, animal contact, temporal and socio-econo-demographic risk factors in the Netherlands in 2010/2011-2014. Dutch source data were supplemented with those from other European countries with similar STEC epidemiology. Human STEC infections were attributed to sources using both the modified Dutch model (mDM) and the modified Hald model (mHM) supplied with the same O-serotyping data. Cattle accounted for 48.6% (mDM) and 53.1% (mHM) of the 1,183 human cases attributed, followed by small ruminants (mDM: 23.5%; mHM: 25.4%), pigs (mDM: 12.5%; mHM: 5.7%) and poultry (mDM: 2.7%; mHM: 3.1%), whereas the sources of the remaining 12.8% of cases could not be attributed. Of the top five O-serotypes infecting humans, O157, O26, O91 and O103 were mainly attributed to cattle (61%-75%) and O146 to small ruminants (71%-77%). Significant risk factors for human STEC infection as a whole were the consumption of beef, raw/undercooked meat or cured meat/cold cuts. For cattle-attributed STEC infections, specific risk factors were consuming raw meat spreads and beef. Consuming raw/undercooked or minced meat were risk factors for STEC infections attributed to small ruminants. For STEC infections attributed to pigs, only consuming raw/undercooked meat was significant. Consuming minced meat, raw/undercooked meat or cured meat/cold cuts were associated with poultry-attributed STEC infections. Consuming raw vegetables was protective for all STEC infections. We concluded that domestic ruminants account for approximately three-quarters of reported human STEC infections, whereas pigs and poultry play a minor role and

  16. Structural Basis for Substrate Specificity in Phosphate Binding (beta/alpha)8-Barrels: D-Allulose 6-Phosphate 3-Epimerase from Escherichia coli K-12

    Energy Technology Data Exchange (ETDEWEB)

    Chan,K.; Fedorov, A.; Almo, S.; Gerlt, J.

    2008-01-01

    Enzymes that share the ({beta}/{alpha})8-barrel fold catalyze a diverse range of reactions. Many utilize phosphorylated substrates and share a conserved C-terminal ({beta}/a)2-quarter barrel subdomain that provides a binding motif for the dianionic phosphate group. We recently reported functional and structural studies of d-ribulose 5-phosphate 3-epimerase (RPE) from Streptococcus pyogenes that catalyzes the equilibration of the pentulose 5-phosphates d-ribulose 5-phosphate and d-xylulose 5-phosphate in the pentose phosphate pathway [J. Akana, A. A. Fedorov, E. Fedorov, W. R. P. Novack, P. C. Babbitt, S. C. Almo, and J. A. Gerlt (2006) Biochemistry 45, 2493-2503]. We now report functional and structural studies of d-allulose 6-phosphate 3-epimerase (ALSE) from Escherichia coli K-12 that catalyzes the equilibration of the hexulose 6-phosphates d-allulose 6-phosphate and d-fructose 6-phosphate in a catabolic pathway for d-allose. ALSE and RPE prefer their physiological substrates but are promiscuous for each other's substrate. The active sites (RPE complexed with d-xylitol 5-phosphate and ALSE complexed with d-glucitol 6-phosphate) are superimposable (as expected from their 39% sequence identity), with the exception of the phosphate binding motif. The loop following the eighth {beta}-strand in ALSE is one residue longer than the homologous loop in RPE, so the binding site for the hexulose 6-phosphate substrate/product in ALSE is elongated relative to that for the pentulose 5-phosphate substrate/product in RPE. We constructed three single-residue deletion mutants of the loop in ALSE, ?T196, ?S197 and ?G198, to investigate the structural bases for the differing substrate specificities; for each, the promiscuity is altered so that d-ribulose 5-phosphate is the preferred substrate. The changes in kcat/Km are dominated by changes in kcat, suggesting that substrate discrimination results from differential transition state stabilization. In both ALSE and RPE, the

  17. Recombinant Protein Expression in Escherichia coli (E.coli): What We Need to Know.

    Science.gov (United States)

    Hayat, Seyed Mohammad Gheibi; Farahani, Najmeh; Golichenari, Behrouz; Sahebkar, Amir Hosein

    2018-01-31

    Host, vector, and culture conditions (including cultivation media) are considered among the three main elements contributing to a successful production of recombinant proteins. Accordingly, one of the most common hosts to produce recombinant therapeutic proteins is Escherichia coli. A comprehensive literature review was performed to identify important factors affecting production of recombinant proteins in Escherichia coli. Escherichia coli is taken into account as the easiest, quickest, and cheapest host with a fully known genome. Thus, numerous modifications have been carried out on Escherichia coli to optimize it as a good candidate for protein expression and; as a result, several engineered strains of Escherichia coli have been designed. In general; host strain, vector, and cultivation parameters are recognized as crucial ones determining success of recombinant protein expression in Escherichia coli. In this review, the role of host, vector, and culture conditions along with current pros and cons of different types of these factors leading to success of recombinant protein expression in Escherichia coli were discussed. Successful protein expression in Escherichia coli necessitates a broad knowledge about physicochemical properties of recombinant proteins, selection among common strains of Escherichia coli and vectors, as well as factors related to media including time, temperature, and inducer. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  18. Changes in Escherichia coli resistance to co-trimoxazole in ...

    African Journals Online (AJOL)

    Escherichia coli (E.coli) resistance to co-trimoxazole in TB patients changed with time and ii) whether the resistance pattern was different in HIV positive TB patients who were taking co-trimoxazole prophylaxis. Co-trimoxazole resist- ance among E.coli isolates in TB patients at the time of reg- istration was 60% in 1999 and ...

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

    African Journals Online (AJOL)

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

  20. Isolation and Antibiotics Susceptibility Patterns of Escherichia Coli ...

    African Journals Online (AJOL)

    Escherichia coli 0157.H7 were confirmed serologically using latex agglutination kits (OxoidR UK). The isolates were tested for susceptibility to five commonly used antimicrobial agents and plasmid transfer was also carried out using E. coli K12 356 recipient. Out of the 61 non-Sorbitol fermenting (NSF) E. coli isolated from ...

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

    African Journals Online (AJOL)

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

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

    African Journals Online (AJOL)

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

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

    OpenAIRE

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

    2010-01-01

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

  4. Adhesive threads of extraintestinal pathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Antão Esther-Maria

    2009-12-01

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

  5. Dynamics of chromosome segregation in Escherichia coli

    DEFF Research Database (Denmark)

    Nielsen, Henrik Jørck

    2007-01-01

    Since the 1960’es the conformation and segregation of the chromosome in Escherichia coli has been a subject of interest for many scientists. However, after 40 years of research, we still know incredibly little about how the chromosome is organized inside the cell, how it manages to duplicate...... this incredibly big molecule and separate the two daughter chromosomes and how it makes sure that the daughter cells receives one copy each. The fully extended chromosome is two orders of magnitude larger than the cell in which it is contained. Hence the chromosome is heavily compacted in the cell......, and it is obvious that structured cellular actions are required to unpack it, as required for its replication, and refold the two daughter chromosomes separately without getting them entangled in the process each generation. The intention of the study was initially to find out how the chromosome is organized...

  6. Engineering membrane protein overproduction in Escherichia coli

    Science.gov (United States)

    Molina, Daniel Martinez; Cornvik, Tobias; Eshaghi, Said; Haeggström, Jesper Z.; Nordlund, Pär; Sabet, Marina Ignatushchenko

    2008-01-01

    Membrane proteins play a fundamental role in human disease and therapy, but suffer from a lack of structural and functional information compared to their soluble counterparts. The paucity of membrane protein structures is primarily due to the unparalleled difficulties in obtaining detergent-solubilized membrane proteins at sufficient levels and quality. We have developed an in vitro evolution strategy for optimizing the levels of detergent-solubilized membrane protein that can be overexpressed and purified from recombinant Escherichia coli. Libraries of random mutants for nine membrane proteins were screened for expression using a novel implementation of the colony filtration blot. In only one cycle of directed evolution were significant improvements of membrane protein yield obtained for five out of nine proteins. In one case, the yield of detergent-solubilized membrane protein was increased 40-fold. PMID:18305199

  7. Initiation of Replication in Escherichia coli

    DEFF Research Database (Denmark)

    Frimodt-Møller, Jakob

    of initiation, which leads to hyperinitiation, results in double-strand breaks when replication forks encounters single-stranded DNA lesions generated while removing oxidized bases, primarily 8-oxoG, from the DNA. Thus, the number of replication forks can only increase when ROS formation is reduced or when......The circular chromosome of Escherichia coli is replicated by two replisomes assembled at the unique origin and moving in the opposite direction until they meet in the less well defined terminus. The key protein in initiation of replication, DnaA, facilitates the unwinding of double-stranded DNA...... to single-stranded DNA in oriC. Although DnaA is able to bind both ADP and ATP, DnaA is only active in initiation when bound to ATP. Although initiation of replication, and the regulation of this, is thoroughly investigated it is still not fully understood. The overall aim of the thesis was to investigate...

  8. Association of clustered regularly interspaced short palindromic repeat (CRISPR) elements with specific serotypes and virulence potential of shiga toxin-producing Escherichia coli.

    Science.gov (United States)

    Toro, Magaly; Cao, Guojie; Ju, Wenting; Allard, Marc; Barrangou, Rodolphe; Zhao, Shaohua; Brown, Eric; Meng, Jianghong

    2014-02-01

    Shiga toxin-producing Escherichia coli (STEC) strains (n = 194) representing 43 serotypes and E. coli K-12 were examined for clustered regularly interspaced short palindromic repeat (CRISPR) arrays to study genetic relatedness among STEC serotypes. A subset of the strains (n = 81) was further analyzed for subtype I-E cas and virulence genes to determine a possible association of CRISPR elements with potential virulence. Four types of CRISPR arrays were identified. CRISPR1 and CRISPR2 were present in all strains tested; 1 strain also had both CRISPR3 and CRISPR4, whereas 193 strains displayed a short, combined array, CRISPR3-4. A total of 3,353 spacers were identified, representing 528 distinct spacers. The average length of a spacer was 32 bp. Approximately one-half of the spacers (54%) were unique and found mostly in strains of less common serotypes. Overall, CRISPR spacer contents correlated well with STEC serotypes, and identical arrays were shared between strains with the same H type (O26:H11, O103:H11, and O111:H11). There was no association identified between the presence of subtype I-E cas and virulence genes, but the total number of spacers had a negative correlation with potential pathogenicity (P CRISPR-cas system and potential virulence needs to be determined on a broader scale, and the biological link will need to be established.

  9. Escherichia coli enterotoxin. Purification and partial characterization.

    Science.gov (United States)

    Dorner, F

    1975-11-25

    Enterotoxin, a diarrheagenic protein elaborated by pathogenic Escherichia coli strains has been isolated from the supernatant of fermenter cultures of E. coli strain P263, a porcine enteropathogen. Purification steps involving Bio-Gel agarose A-5m, Sephadex G-75 chromatography, and preparative isotachophoresis were used in the isolation. The resulting product appears to be pure according to immunoelectrophoretic, disc electrophoretic, ultracentrifugal, and immunologic criteria. The entertoxin has an apparent molecular weight of 102,000 as judged by gel filtration and sodium dodecyl sulfate polyacrylamide gel electrophoresis, and its isoelectric point is 6.90. The isolated product is highly active in inducing experimental diarrhea in adult rabbits and piglets. It also elicits, in small dosage, a marked increase in adenylate cyclase activity in broken cell preparations of cat heart tissue. The enterotoxin activity is acid-labile and is destroyed by heating at 65 degrees for 30 min. It is suggested that the heat-stable enterotoxin material is derived from heat-labile enterotoxin by forming a complex with endotoxin or capsular material present in the culture supernatant.

  10. Cloning and expression of Pseudomonas aeruginosa flagellin in Escherichia coli.

    OpenAIRE

    Kelly-Wintenberg, K; Montie, T. C.

    1989-01-01

    The flagellin gene was isolated from a Pseudomonas aeruginosa PAO1 genomic bank by conjugation into a PA103 Fla- strain. Flagellin DNA was transferred from motile recipient PA103 Fla+ cells by transformation into Escherichia coli. We show that transformed E. coli expresses flagellin protein. Export of flagellin to the E. coli cell surface was suggested by positive colony blots of unlysed cells and by isolation of flagellin protein from E. coli supernatants.

  11. The host response to the probiotic Escherichia coli strain Nissle 1917: Specific up-regulation of the proinflammatory chemokine MCP-1

    Directory of Open Access Journals (Sweden)

    Ukena Sya N

    2005-12-01

    Full Text Available Abstract Background The use of live microorganisms to influence positively the course of intestinal disorders such as infectious diarrhea or chronic inflammatory conditions has recently gained increasing interest as a therapeutic alternative. In vitro and in vivo investigations have demonstrated that probiotic-host eukaryotic cell interactions evoke a large number of responses potentially responsible for the effects of probiotics. The aim of this study was to improve our understanding of the E. coli Nissle 1917-host interaction by analyzing the gene expression pattern initiated by this probiotic in human intestinal epithelial cells. Methods Gene expression profiles of Caco-2 cells treated with E. coli Nissle 1917 were analyzed with microarrays. A second human intestinal cell line and also pieces of small intestine from BALB/c mice were used to confirm regulatory data of selected genes by real-time RT-PCR and cytometric bead array (CBA to detect secretion of corresponding proteins. Results Whole genome expression analysis revealed 126 genes specifically regulated after treatment of confluent Caco-2 cells with E. coli Nissle 1917. Among others, expression of genes encoding the proinflammatory molecules monocyte chemoattractant protein-1 ligand 2 (MCP-1, macrophage inflammatory protein-2 alpha (MIP-2α and macrophage inflammatory protein-2 beta (MIP-2β was increased up to 10 fold. Caco-2 cells cocultured with E. coli Nissle 1917 also secreted high amounts of MCP-1 protein. Elevated levels of MCP-1 and MIP-2α mRNA could be confirmed with Lovo cells. MCP-1 gene expression was also up-regulated in mouse intestinal tissue. Conclusion Thus, probiotic E. coli Nissle 1917 specifically upregulates expression of proinflammatory genes and proteins in human and mouse intestinal epithelial cells.

  12. Complete Genome Sequence of Escherichia coli Strain WG5

    DEFF Research Database (Denmark)

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

    2018-01-01

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

  13. Culture confirmation of Escherichia coli serotype O157:H7 by direct immunofluorescence.

    OpenAIRE

    Tison, D L

    1990-01-01

    An evaluation of a fluorescein-labeled, polyclonal, affinity-purified goat antibody to Escherichia coli serotype O157:H7 (Kirkegaard & Perry Laboratories Inc., Gaithersburg, Md.) was conducted to determine the efficacy of this research reagent for the rapid direct immunofluorescence identification of E. coli O157:H7 isolated from fecal specimens cultured on sorbitol-MacConkey (SMAC) agar. The E. coli O157:H7 fluorescent-antibody conjugate proved to be 100% sensitive and specific for the rapid...

  14. Escherichia coli as an indicator of bacteriological quality of water: an overview

    OpenAIRE

    Stephen T. Odonkor; Joseph K. Ampofo

    2013-01-01

    Monitoring the microbiological quality of drinking water relies largely on examination of indicator bacteria such as coliforms, Escherichia coli, and Pseudomonas aeruginosa. E. coli is a member of the faecal coliform group and is a more specific indicator of faecal pollution than other faecal coliforms. Two key factors have led to the trend toward the use of E. coli as the preferred indicator for the detection of faecal contamination, not only in drinking water, but also in other matrices as ...

  15. Immunogenic Domains and Secondary Structure of Escherichia coli Recombinant Secreted Protein Escherichia coli-Secreted Protein B.

    Science.gov (United States)

    Caetano, Bruna Alves; Rocha, Letícia Barboza; Carvalho, Eneas; Piazza, Roxane Maria Fontes; Luz, Daniela

    2017-01-01

    Several pathogenic bacteria are able to induce the attaching and effacing (A/E) lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB), responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein. Herein, we describe the production of a hybrid recombinant EspB toxin that comprises all known variants of this protein. This recombinant protein could be useful as an antigen for the production of antibodies with broad-range detection of EspB-bearing bacteria, or as an antigen that could be used in vaccine formulation to generate antibodies against different EspB variants, thereby increasing immunization potential. In addition, the recombinant protein allowed us to analyze its secondary structure, to propose the immunogenic regions of EspB variants, and also to characterize anti-EspB antibodies. Our results suggest that this hybrid protein or a protein composed of the conserved immunogenic regions could be used for a variety of clinical applications.

  16. Immunogenic Domains and Secondary Structure of Escherichia coli Recombinant Secreted Protein Escherichia coli-Secreted Protein B

    Science.gov (United States)

    Caetano, Bruna Alves; Rocha, Letícia Barboza; Carvalho, Eneas; Piazza, Roxane Maria Fontes; Luz, Daniela

    2017-01-01

    Several pathogenic bacteria are able to induce the attaching and effacing (A/E) lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB), responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein. Herein, we describe the production of a hybrid recombinant EspB toxin that comprises all known variants of this protein. This recombinant protein could be useful as an antigen for the production of antibodies with broad-range detection of EspB-bearing bacteria, or as an antigen that could be used in vaccine formulation to generate antibodies against different EspB variants, thereby increasing immunization potential. In addition, the recombinant protein allowed us to analyze its secondary structure, to propose the immunogenic regions of EspB variants, and also to characterize anti-EspB antibodies. Our results suggest that this hybrid protein or a protein composed of the conserved immunogenic regions could be used for a variety of clinical applications. PMID:28484467

  17. Immunogenic Domains and Secondary Structure of Escherichia coli Recombinant Secreted Protein Escherichia coli-Secreted Protein B

    Directory of Open Access Journals (Sweden)

    Roxane Maria Fontes Piazza

    2017-04-01

    Full Text Available Several pathogenic bacteria are able to induce the attaching and effacing (A/E lesion. The A/E lesion is caused by effector proteins, such as Escherichia coli-secreted protein B (EspB, responsible together with Escherichia coli-secreted protein D for forming a pore structure on the host cell, which allows the translocation of effector proteins. Different variants of this protein can be found in E. coli strains, and during natural infection or when this protein is injected, this leads to variant-specific production of antibodies, which may not be able to recognize other variants of this bacterial protein. Herein, we describe the production of a hybrid recombinant EspB toxin that comprises all known variants of this protein. This recombinant protein could be useful as an antigen for the production of antibodies with broad-range detection of EspB-bearing bacteria, or as an antigen that could be used in vaccine formulation to generate antibodies against different EspB variants, thereby increasing immunization potential. In addition, the recombinant protein allowed us to analyze its secondary structure, to propose the immunogenic regions of EspB variants, and also to characterize anti-EspB antibodies. Our results suggest that this hybrid protein or a protein composed of the conserved immunogenic regions could be used for a variety of clinical applications.

  18. Role of recBC nuclease in Escherichia coli transformation.

    OpenAIRE

    Hoekstra, W P; Bergmans, J E; Zuidweg, E M

    1980-01-01

    In Escherichia coli transformation with linear donor deoxyribonucleic acid, the recBC pathway is functional, but genetic analysis shows that the recBC nuclease is deleterious to linear deoxyribonucleic acid.

  19. WGS accurately predicts antimicrobial resistance in Escherichia coli

    National Research Council Canada - National Science Library

    Tyson, Gregory H; McDermott, Patrick F; Li, Cong; Chen, Yuansha; Tadesse, Daniel A; Mukherjee, Sampa; Bodeis-Jones, Sonya; Kabera, Claudine; Gaines, Stuart A; Loneragan, Guy H; Edrington, Tom S; Torrence, Mary; Harhay, Dayna M; Zhao, Shaohua

    2015-01-01

    The objective of this study was to determine the effectiveness of WGS in identifying resistance genotypes of MDR Escherichia coli and whether these correlate with observed phenotypes. Seventy-six E...

  20. Antibiotic resistance of Escherichia coli, Listeria and Salmonella ...

    African Journals Online (AJOL)

    Antibiotic resistance of Escherichia coli, Listeria and Salmonella isolates from retail ... Antibiotics sensitivity test was assayed on thirty (30) isolates (10 each for ... their way into human population through food chain and occupational exposure.

  1. Switchable gene expression in Escherichia coli using a miniaturized photobioreactor

    National Research Council Canada - National Science Library

    Lee, Jae Myung; Lee, Junhyeong; Kim, Taesung; Lee, Sung Kuk

    2013-01-01

    We present a light-switchable gene expression system for both inducible and switchable control of gene expression at a single cell level in Escherichia coli using a previously constructed light-sensing system. The λ...

  2. The Prevalence of Enterhaemorrhagic Escherichia Coli in children ...

    African Journals Online (AJOL)

    EHEC), the pathogenicity of other strains of Escherichia coli and other organisms in children presenting with and without diarrhoea in the hospital. Subjects and Methods: A total of 247 stool samples collected from children aged 1 month to 7 ...

  3. Nanotextile membranes for bacteria Escherichia coli capturing

    Directory of Open Access Journals (Sweden)

    Jaroslav Lev

    2010-01-01

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

  4. Strain-dependent carotenoid productions in metabolically engineered Escherichia coli.

    Science.gov (United States)

    Chae, Han Seung; Kim, Kong-Hwan; Kim, Sun Chang; Lee, Pyung Cheon

    2010-12-01

    Seven Escherichia coli strains, which were metabolically engineered with carotenoid biosynthetic pathways, were systematically compared in order to investigate the strain-specific formation of carotenoids of structural diversity. C30 acyclic carotenoids, diaponeurosporene and diapolycopene were well produced in all E. coli strains tested. However, the C30 monocyclic diapotorulene formation was strongly strain dependent. Reduced diapotorulene formation was observed in the E. coli strain Top10, MG1655, and MDS42 while better formation was observed in the E. coli strain JM109, SURE, DH5a, and XL1-Blue. Interestingly, C40 carotenoids, which have longer backbones than C30 carotenoids, also showed strain dependency as C30 diapotorulene did. Quantitative analysis showed that the SURE strain was the best producer for C40 acyclic lycopene, C40 dicyclic β-carotene, and C30 monocyclic diapotorulene. Of the seven strains examined, the highest volumetric productivity for most of the carotenoids structures was observed in the recombinant SURE strain. In conclusion, we showed that recombinant hosts and carotenoid structures influenced carotenoid productions significantly, and this information can serve as the basis for the subsequent development of microorganisms for carotenoids of interest.

  5. The contribution of the C5 protein subunit of Escherichia coli ribonuclease P to specificity for precursor tRNA is modulated by proximal 5' leader sequences.

    Science.gov (United States)

    Niland, Courtney N; Anderson, David R; Jankowsky, Eckhard; Harris, Michael E

    2017-10-01

    Recognition of RNA by RNA processing enzymes and RNA binding proteins often involves cooperation between multiple subunits. However, the interdependent contributions of RNA and protein subunits to molecular recognition by ribonucleoproteins are relatively unexplored. RNase P is an endonuclease that removes 5' leaders from precursor tRNAs and functions in bacteria as a dimer formed by a catalytic RNA subunit (P RNA) and a protein subunit (C5 in E. coli). The P RNA subunit contacts the tRNA body and proximal 5' leader sequences [N(-1) and N(-2)] while C5 binds distal 5' leader sequences [N(-3) to N(-6)]. To determine whether the contacts formed by P RNA and C5 contribute independently to specificity or exhibit cooperativity or anti-cooperativity, we compared the relative kcat/Km values for all possible combinations of the six proximal 5' leader nucleotides (n = 4096) for processing by the E. coli P RNA subunit alone and by the RNase P holoenzyme. We observed that while the P RNA subunit shows specificity for 5' leader nucleotides N(-2) and N(-1), the presence of the C5 protein reduces the contribution of P RNA to specificity, but changes specificity at N(-2) and N(-3). The results reveal that the contribution of C5 protein to RNase P processing is controlled by the identity of N(-2) in the pre-tRNA 5' leader. The data also clearly show that pairing of the 5' leader with the 3' ACCA of tRNA acts as an anti-determinant for RNase P cleavage. Comparative analysis of genomically encoded E. coli tRNAs reveals that both anti-determinants are subject to negative selection in vivo. © 2017 Niland et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  6. Escherichia coli challenge in newborn pigs.

    Science.gov (United States)

    Jensen, M L; Cilieborg, M S; Østergaard, M V; Bering, S B; Jørgensen, C B; Sangild, P T

    2012-12-01

    Escherichia coli F18 is a common porcine enteric pathogen causing diarrhea and edema in weaned pigs. An essential step in the pathogenesis of this enteric colibacillosis is a fimbria-receptor interaction in the small intestine, involving the α(1,2)-fucosyltransferase gene (FUT1) enzyme for bacterial receptor binding to the epithelium. Enzyme expression is genetically determined and increases after weaning at 3 to5 wk, probably due to age- and/or diet-related intestinal maturation. We hypothesized that artificially reared piglets, deprived of sow's milk from birth, show susceptibility to F18 already in the neonatal period. First we verified the intestinal expression of FUT1 in preterm, term, and weaned pigs by quantitative real-time polymerase chain reaction. Then age-related F18 susceptibility (degree of diarrhea) was evaluated in 3-, 10-, and 20-d-old pigs after inoculation of 10(10) cfu E. coli F18 per day for 12 d. Finally, F18 susceptibility was evaluated in caesarean-delivered 0- to 7-d-old piglets inoculated daily with F18 as above. For all pigs, their sows were genotyped to ensure expression of the FUT1 enzyme. FUT1 expression was detected in the proximal and distal small intestine with no apparent differences in levels among preterm, term, and weaned pigs. No consistent F18-induced diarrhea was detected in any of the 3 groups of 3- to 20-d-old pigs. In contrast, 0- to 7-d-old caesarean-delivered pigs showed a higher score of diarrhea in pigs inoculated with F18 compared with controls (2.4 ± 0.1 vs. 1.8 ± 0.1 respectively; P sow milk are highly susceptible to diarrhea induced by E. coli F18. Lack of the protective effects of birth colonization and sow milk may contribute to high intestinal F18 sensitivity. The newborn pig may be a useful model to investigate factors in maternal milk that protect against F18 diarrhea.

  7. Characterization of pyruvate uptake in Escherichia coli K-12.

    Directory of Open Access Journals (Sweden)

    Jens Kreth

    Full Text Available The monocarboxylate pyruvate is an important metabolite and can serve as sole carbon source for Escherichia coli. Although specific pyruvate transporters have been identified in two bacterial species, pyruvate transport is not well understood in E. coli. In the present study, pyruvate transport was investigated under different growth conditions. The transport of pyruvate shows specific activities depending on the growth substrate used as sole carbon source, suggesting the existence of at least two systems for pyruvate uptake: i one inducible system and probably highly specific for pyruvate and ii one system active under non-induced conditions. Using the toxic pyruvate analog 3-fluoropyruvate, a mutant was isolated unable to grow on and transport pyruvate. Further investigation revealed that a revertant selected for growth on pyruvate regained the inducible pyruvate transport activity. Characterization of pyruvate excretion showed that the pyruvate transport negative mutant accumulated pyruvate in the growth medium suggesting an additional transport system for pyruvate excretion. The here presented data give valuable insight into the pyruvate metabolism and transport of E. coli suggesting the presence of at least two uptake systems and one excretion system to balance the intracellular level of pyruvate.

  8. The Escherichia coli divisome: born to divide.

    Science.gov (United States)

    Natale, Paolo; Pazos, Manuel; Vicente, Miguel

    2013-12-01

    Septation in Escherichia coli involves complex molecular mechanisms that contribute to the accuracy of bacterial division. The proto-ring, a complex made up by the FtsZ, FtsA and ZipA proteins, forms at the beginning of the process and directs the assembly of the full divisome. Central to this complex is the FtsZ protein, a GTPase able to assemble into a ring-like structure that responds to several modulatory inputs including mechanisms to position the septum at midcell. The connection with the cell wall synthesising machinery stabilizes the constriction of the cytoplasmic membrane. Although a substantial amount of evidence supports this description, many details on how individual divisome elements are structured or how they function are subjected to controversial interpretations. We discuss these discrepancies arising from incomplete data and from technical difficulties imposed by the small size of bacteria. Future work, including more powerful imaging and reconstruction technologies, will help to clarify the missing details on the architecture and function of the bacterial division machinery. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. Oligosaccharide Binding in Escherichia coli Glycogen Synthase

    Energy Technology Data Exchange (ETDEWEB)

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

    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.

  10. Genotoxicity of Graphene in Escherichia coli

    Science.gov (United States)

    Sharma, Ananya

    Rapid advances in nanotechnology necessitate assessment of the safety of nanomaterials in the resulting products and applications. One key nanomaterial attracting much interest in many areas of science and technology is graphene. Graphene is a one atom thick carbon allotrope arranged in a two-dimensional honeycomb lattice. In addition to being extremely thin, graphene has several extraordinary physical properties such as its exceptional mechanical strength, thermal stability, and high electrical conductivity. Graphene itself is relatively chemically inert and therefore pristine graphene must undergo a process called functionalization, which is combination of chemical and physical treatments that change the properties of graphene, to make it chemically active. Functionalization of graphene is of crucial importance as the end application of graphene depends on proper functionalization. In the field of medicine, graphene is currently a nanomaterial of high interest for building biosensors, DNA transistors, and probes for cancer detection. Despite the promising applications of graphene in several areas of biomedicine, there have been only few studies in recent years that focus on evaluating cytotoxicity of graphene on cells, and almost no studies that investigate how graphene exposure affects cellular genetic material. Therefore, in this study we used a novel approach to evaluate the genotoxicity, i.e., the effects of graphene on DNA, using Escherichia coli as a prokaryotic model organism.

  11. Changes in Escherichia coli resistance to co-trimoxazole in ...

    African Journals Online (AJOL)

    In Thyolo district, Malawi, an operational research study is being conducted on the efficacy and feasibility of co-trimoxazole prophylaxis in preventing deaths in HIV-positive patients with tuberculosis (TB). A series of cross-sectional studies were carried out to determine i) whether faecal Escherichia coli (E.coli) resistance to ...

  12. Enterotoxigenic Escherichia coli Multilocus Sequence Types in Guatemala and Mexico

    Science.gov (United States)

    Klena, John; Rodas, Claudia; Bourgeois, August Louis; Torres, Olga; Svennerholm, Ann-Mari; Sjöling, Åsa

    2010-01-01

    The genetic backgrounds of 24 enterotoxigenic Escherichia coli (ETEC) strains from Mexico and Guatemala expressing heat-stable toxin (ST) and coli surface antigen 6 (CS6) were analyzed. US travelers to these countries and resident children in Guatemala were infected by ETEC strains of sequence type 398, expressing STp and carrying genetically identical CS6 sequences. PMID:20031063

  13. Multiple antimicrobial resistance of Escherichia coli and Salmonella ...

    African Journals Online (AJOL)

    Pathogenic Escherichia coli and Salmonella species are the causative agents of various disease complexes in poultry such as colibacillosis, fowl typhoid, pullorum disease and salmonellosis. Some strains of E. coli and Salmonella spp. have been shown to be resistant to multiple antibiotics. We carried out a bacteriological ...

  14. Glucuronidase activity of Escherichia coli isolated from chicken carcasses

    OpenAIRE

    Perin,Luana Martins; Yamazi,Anderson Keizo; Moraes,Paula Mendonça; Cossi,Marcus Vinícius Coutinho; Pinto,Paulo Sérgio de Arruda; Nero,Luís Augusto

    2010-01-01

    To identify Escherichia coli through the production of β-D-glucuronidase (GUD), 622 suspect cultures were isolated from chicken carcasses and plated in PetrifilmTM EC. Of these cultures, only 44 (7.1%) failed to produce GUD. This result indicates the usefulness of GUD production for estimating E. coli populations in chicken.

  15. ANTIBACTERIAL ACTIVITY OF FRUIT AN Against Escherichia coli ...

    African Journals Online (AJOL)

    userpc

    ABSTRACT. The preliminary antibacterial activity of f evaluated against Escherichia coli and S method. The bioactive components of the aqueous, ethanol and acetone solvents. The effective at different concentrations of 6. ranging between 6.0±2.5mm-20.0±4.5mm f coli. Aqueous extract at 6.25mg/ml.

  16. Expression of green fluorescent protein (GFPuv) in Escherichia coli ...

    African Journals Online (AJOL)

    The recombinant green fluorescent protein (GFPuv) was expressed by transformed cells of Escherichia coli DH5-α grown in LB/amp broth at 37oC, for 8 h and 24 h. To evaluate the effectiveness of different parameters to improve the expression of GFPuv by E. coli, four variable culturing conditions were set up for assays by ...

  17. Effect of high pressurized carbon dioxide on Escherichia coli ...

    African Journals Online (AJOL)

    Carbon dioxide at high pressure can retard microbial growth and sometimes kill microorganisms depending on values of applied pressure, temperature and exposure time. In this study the effect of high pressurised carbon dioxide (HPCD) on Escherichia coli was investigated. Culture of E. coli was subjected to high ...

  18. Adsorption of Escherichia coli Using Bone Char | Rezaee | Journal ...

    African Journals Online (AJOL)

    The aim of study was providing a novel adsorbent for the removal of Escherichia coli (E.coli) as a microbial model from contaminated air especially in hospital units using bone char (BC). The BC was prepared from cattle animal bone by pyrolysis in a furnace at 450°C for 2 h. The characteristics of BC have been determined ...

  19. Antimicrobial resistance of non-clinical Escherichia coli strains from ...

    African Journals Online (AJOL)

    This study was carried out to determine resistance profiles of Escherichia coli strains isolated from clinically healthy chickens in Nsukka, southeast Nigeria. A total of 324 E. coli strains isolated from cloaca swabs from 390 chickens were tested against 16 antimicrobial agents using the disc diffusion method. The antibiotics ...

  20. Prevalence of Aeromonas species and Escherichia coli in stool ...

    African Journals Online (AJOL)

    Background: Diarrhoea is one of the main causes of mortality and morbidity in childhood. Bacterial diarrhoea is a common disorder. Aeromonas species and Escherichia coli (E. coli) are some of the aetiological agents associated with diarrhoea in children. Objective: To determine the prevalence of Aeromonas species and ...

  1. Growth responses of Escherichia coli and Myxococcus xanthus on ...

    African Journals Online (AJOL)

    We investigated the growth kinetics of wild-type Escherichia coli, non-motile E. coli, and Myxococcus xanthus, cultured on semi-solid agar substrates containing different amounts of nutrient and agar. We found that substrate stiffness, which was controlled by agar concentration, modulates the growth of motile bacteria, such ...

  2. Antimicrobial susceptibilities of avian Escherichia coli isolates in ...

    African Journals Online (AJOL)

    Yomi

    2012-03-06

    Mar 6, 2012 ... Colibacillosis is a poultry disease of economic importance in Iran and all around the world. The aim of this study is to test the antibiotic sensitivity of Escherichia coli strains which were isolated in Tabriz. A total of 100 E. coli strains isolated from avian colibacillosis of 50 farms from 2008 to 2009 in Tabriz,.

  3. Growth modeling of uropathogenic Escherichia coli in ground chicken meat

    Science.gov (United States)

    Extraintestinal Pathogenic Escherichia coli (ExPEC), including Uropathogenic E. coli (UPEC), are common contaminants in poultry meat, and are a major pathogen associated with inflammatory bowel disease, ulcerative colitis, sepsis, and urinary tract infections. The purpose of this study was to determ...

  4. Screening of verotoxin-producing Escherichia coli (VETC) O104 ...

    African Journals Online (AJOL)

    Escherichia coli strains are important causes of diarrheal disease in the world and remain a major public health problem of animals and human. Sixty seven samples from different kind of food, water, soil and composit were screened for the detection of verotoxin-producing E.coli (VTEC) in the Egyptian markets from different ...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  6. Prevalence of Antibiotic-Resistant Strains of Escherichia coli in ...

    African Journals Online (AJOL)

    A measured Escherichia coli level in drinking water is perhaps the most popular means of determining human health risks globally. Water samples from wells, boreholes and sachet water, the 3 predominant sources of drinking water in the study area were evaluated for the presence of bacteria, particularly E coli. Bacteria ...

  7. Antimicrobial susceptibilities of avian Escherichia coli isolates in ...

    African Journals Online (AJOL)

    Colibacillosis is a poultry disease of economic importance in Iran and all around the world. The aim of this study is to test the antibiotic sensitivity of Escherichia coli strains which were isolated in Tabriz. A total of 100 E. coli strains isolated from avian colibacillosis of 50 farms from 2008 to 2009 in Tabriz, were investigated for ...

  8. Enterotoxigenic Escherichia coli multilocus sequence types in Guatemala and Mexico.

    Science.gov (United States)

    Nicklasson, Matilda; Klena, John; Rodas, Claudia; Bourgeois, August Louis; Torres, Olga; Svennerholm, Ann Mari; Sjoling, Asa

    2010-01-01

    The genetic backgrounds of 24 enterotoxigenic Escherichia coli (ETEC) strains from Mexico and Guatemala expressing heat-stable toxin (ST) and coli surface antigen 6 (CS6) were analyzed. US travelers to these countries and resident children in Guatemala were infected by ETEC strains of sequence type 398, expressing STp and carrying genetically identical CS6 sequences.

  9. Enterotoxigenic Escherichia coli Multilocus Sequence Types in Guatemala and Mexico

    OpenAIRE

    Nicklasson, Matilda; Klena, John; Rodas, Claudia; Bourgeois, August Louis; Torres, Olga; Svennerholm, Ann-Mari; Sj?ling, ?sa

    2010-01-01

    The genetic backgrounds of 24 enterotoxigenic Escherichia coli (ETEC) strains from Mexico and Guatemala expressing heat-stable toxin (ST) and coli surface antigen 6 (CS6) were analyzed. US travelers to these countries and resident children in Guatemala were infected by ETEC strains of sequence type 398, expressing STp and carrying genetically identical CS6 sequences.

  10. Septicemia caused by cysteine-dependent Escherichia coli.

    OpenAIRE

    Yuen, K Y; Seto, W H; Tsui, K H; Hui, W T

    1990-01-01

    A case of septicemia and urinary tract infection caused by cysteine-dependent Escherichia coli in a 70-year-old woman with bilateral staghorn calculi is described. This is the second report of a cysteine-dependent E. coli bacteremia. The bacterium was falsely susceptible to ampicillin and co-trimoxazole when tested on a medium without cysteine supplement.

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

    Science.gov (United States)

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

    2014-01-01

    Since the first step of the infection process is colonization of the host, it is important to understand how Escherichia coli pathogens successfully colonize the intestine. We previously showed that enterohemorrhagic O157:H7 strain E. coli EDL933 colonizes a niche in the streptomycin-treated mouse intestine that is distinct from that of human commensal strains, which explains how E. coli EDL933 overcomes colonization resistance imparted by some, but not all, commensal E. coli strains. Here we sought to determine if other E. coli pathogens use a similar strategy. We found that uropathogenic E. coli CFT073 and enteropathogenic E. coli E2348/69 occupy intestinal niches that are distinct from that of E. coli EDL933. In contrast, two enterohemorrhagic strains, E. coli EDL933 and E. coli Sakai, occupy the same niche, suggesting that strategies to prevent colonization by a given pathotype should be effective against other strains of the same pathotype. However, we found that a combination of commensal E. coli strains that can prevent colonization by E. coli EDL933 did not prevent colonization by E. coli CFT073 or E. coli E2348/69. Our results indicate that development of probiotics to target multiple E. coli pathotypes will be problematic, as the factors that govern niche occupation and hence stable colonization vary significantly among strains. PMID:24566621

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

    Directory of Open Access Journals (Sweden)

    Tambur Zoran

    2007-01-01

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

  13. Novel phage-based bio-processing of pathogenic Escherichia coli and its biofilms.

    Science.gov (United States)

    Jassim, S A A; Abdulamir, A S; Abu Bakar, F

    2012-01-01

    To explore new approaches of phage-based bio-process of specifically pathogenic Escherichia coli bacteria in food products within a short period. One hundred and forty highly lytic designed coliphages were used. Escherichia coli naturally contaminated and Enterohemorrhagic Escherichia coli experimentally inoculated samples of lettuce, cabbage, meat, and egg were used. In addition, experimentally produced biofilms of E. coli were tested. A phage concentration of 10(3) PFU/ml was used for food products immersion, and for spraying of food products, 10(5) PFU/ml of a phage cocktail was used by applying a 20-s optimal dipping time in a phage cocktail. Food samples were cut into pieces and were either sprayed with or held in a bag immersed in lambda buffer containing a cocktail of 140 phages. Phage bio-processing was successful in eliminating completely E. coli in all processed samples after 48 h storage at 4°C. Partial elimination of E. coli was observed in earlier storage periods (7 and 18 h) at 24° and 37°C. Moreover, E. coli biofilms were reduced >3 log cycles upon using the current phage bio-processing. The use of a phage cocktail of 140 highly lytic designed phages proved highly effective in suppressing E. coli contaminating food products. Proper decontamination/prevention methods of pathogenic E. coli achieved in this study can replace the current chemically less effective decontamination methods.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

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

    NARCIS (Netherlands)

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

    2016-01-01

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

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  17. Sequence periodicity of Escherichia coli is concentrated in intergenic regions

    Directory of Open Access Journals (Sweden)

    Trifonov Edward N

    2004-08-01

    Full Text Available Abstract Background Sequence periodicity with a period close to the DNA helical repeat is a very basic genomic property. This genomic feature was demonstrated for many prokaryotic genomes. The Escherichia coli sequences display the period close to 11 base pairs. Results Here we demonstrate that practically only ApA/TpT dinucleotides contribute to overall dinucleotide periodicity in Escherichia coli. The noncoding sequences reveal this periodicity much more prominently compared to protein-coding sequences. The sequence periodicity of ApC/GpT, ApT and GpC dinucleotides along the Escherichia coli K-12 is found to be located as well mainly within the intergenic regions. Conclusions The observed concentration of the dinucleotide sequence periodicity in the intergenic regions of E. coli suggests that the periodicity is a typical property of prokaryotic intergenic regions. We suppose that this preferential distribution of dinucleotide periodicity serves many biological functions; first of all, the regulation of transcription.

  18. Enterohemorrhagic Escherichia coli specific enterohemolysin induced IL-1β in human macrophages and EHEC-induced IL-1β required activation of NLRP3 inflammasome.

    Science.gov (United States)

    Zhang, Xiaoai; Cheng, Yuli; Xiong, Yanwen; Ye, Changyun; Zheng, Han; Sun, Hui; Zhao, Hongqing; Ren, Zhihong; Xu, Jianguo

    2012-01-01

    Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major foodborne pathogen causing hemorrhagic colitis and hemolytic-uremic syndrome. The role of EHEC O157:H7-enterohemolysin (Ehx) in the pathogenesis of infections remains poorly defined. In this study, we used gene deletion and complement methods to confirm its putative functions. Results demonstrated that, in THP-1 cells, EHEC O157:H7-Ehx is associated with greater production of extracellular interleukin (IL)-1β than other cytokines. The data also showed that EHEC O157:H7-Ehx contributed to cytotoxicity in THP-1 cells, causing the release of lactate dehydrogenase (LDH). Although we observed a positive correlation between IL-1β production and cytotoxicity in THP-1 cells infected with different EHEC O157:H7 strains, our immunoblot results showed that the majority of IL-1β in the supernatant was mature IL-1β and not the pro-IL-1β that can be released after cell death. However, EHEC O157:H7-Ehx had no detectable effect on biologically inactive pro-IL-1β at the mRNA or protein synthesis levels. Neither did it affect the expression of apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, or NOD-like receptor family pyrin domain containing 3 (NLRP3). RNA interference experiments showed that EHEC O157:H7-induced IL-1β production required the involvement of ASC, caspase-1, and NLRP3 expression in THP-1 cells. Our results demonstrate that Ehx plays a crucial role in EHEC O157:H7-induced IL-1β production and its cytotoxicity to THP-1 cells. NLRP3 inflammasome activation is also involved in EHEC O157:H7-stimulated IL-1β release.

  19. Crystal Structures of Covalent Complexes of [beta]-Lactam Antibiotics with Escherichia coli Penicillin-Binding Protein 5: Toward an Understanding of Antibiotic Specificity

    Energy Technology Data Exchange (ETDEWEB)

    Nicola, George; Tomberg, Joshua; Pratt, R.F.; Nicholas, Robert A.; Davies, Christopher (SC); (UNC); (Wesleyan)

    2010-12-07

    Penicillin-binding proteins (PBPs) are the molecular targets for the widely used {beta}-lactam class of antibiotics, but how these compounds act at the molecular level is not fully understood. We have determined crystal structures of Escherichia coli PBP 5 as covalent complexes with imipenem, cloxacillin, and cefoxitin. These antibiotics exhibit very different second-order rates of acylation for the enzyme. In all three structures, there is excellent electron density for the central portion of the {beta}-lactam, but weak or absent density for the R1 or R2 side chains. Areas of contact between the antibiotics and PBP 5 do not correlate with the rates of acylation. The same is true for conformational changes, because although a shift of a loop leading to an electrostatic interaction between Arg248 and the {beta}-lactam carboxylate, which occurs completely with cefoxitin and partially with imipenem and is absent with cloxacillin, is consistent with the different rates of acylation, mutagenesis of Arg248 decreased the level of cefoxitin acylation only 2-fold. Together, these data suggest that structures of postcovalent complexes of PBP 5 are unlikely to be useful vehicles for the design of new covalent inhibitors of PBPs. Finally, superimposition of the imipenem-acylated complex with PBP 5 in complex with a boronic acid peptidomimetic shows that the position corresponding to the hydrolytic water molecule is occluded by the ring nitrogen of the {beta}-lactam. Because the ring nitrogen occupies a similar position in all three complexes, this supports the hypothesis that deacylation is blocked by the continued presence of the leaving group after opening of the {beta}-lactam ring.

  20. Enterohemorrhagic Escherichia coli Specific Enterohemolysin Induced IL-1β in Human Macrophages and EHEC-Induced IL-1β Required Activation of NLRP3 Inflammasome

    Science.gov (United States)

    Xiong, Yanwen; Ye, Changyun; Zheng, Han; Sun, Hui; Zhao, Hongqing; Ren, Zhihong; Xu, Jianguo

    2012-01-01

    Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major foodborne pathogen causing hemorrhagic colitis and hemolytic-uremic syndrome. The role of EHEC O157:H7-enterohemolysin (Ehx) in the pathogenesis of infections remains poorly defined. In this study, we used gene deletion and complement methods to confirm its putative functions. Results demonstrated that, in THP-1 cells, EHEC O157:H7-Ehx is associated with greater production of extracellular interleukin (IL)-1β than other cytokines. The data also showed that EHEC O157:H7-Ehx contributed to cytotoxicity in THP-1 cells, causing the release of lactate dehydrogenase (LDH). Although we observed a positive correlation between IL-1β production and cytotoxicity in THP-1 cells infected with different EHEC O157:H7 strains, our immunoblot results showed that the majority of IL-1β in the supernatant was mature IL-1β and not the pro-IL-1β that can be released after cell death. However, EHEC O157:H7-Ehx had no detectable effect on biologically inactive pro-IL-1β at the mRNA or protein synthesis levels. Neither did it affect the expression of apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, or NOD-like receptor family pyrin domain containing 3 (NLRP3). RNA interference experiments showed that EHEC O157:H7-induced IL-1β production required the involvement of ASC, caspase-1, and NLRP3 expression in THP-1 cells. Our results demonstrate that Ehx plays a crucial role in EHEC O157:H7-induced IL-1β production and its cytotoxicity to THP-1 cells. NLRP3 inflammasome activation is also involved in EHEC O157:H7-stimulated IL-1β release. PMID:23209696

  1. Genomic and Phenomic Study of Mammary Pathogenic Escherichia coli

    Science.gov (United States)

    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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Escherichia coli causing infection outside the gastrointestinal system are referred to as extra-intestinal pathogenic E. coli. Avian pathogenic E. coli is a subgroup of extra-intestinal pathogenic E. coli and infections due to avian pathogenic E. coli have major impact on poultry production economy...... sequences, 12 predicated genomic islands, three prophage-related sequences, and two clustered regularly interspaced short palindromic repeats regions on the chromosome, suggesting the possible occurrence of horizontal gene transfer in this strain. The wildtype strain of E. coli APEC_O2 is resistant towards...

  3. Current pathogenic Escherichia coli foodborne outbreak cases and therapy development.

    Science.gov (United States)

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

    2017-08-01

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

  4. Butyrate production under aerobic growth conditions by engineered Escherichia coli.

    Science.gov (United States)

    Kataoka, Naoya; Vangnai, Alisa S; Pongtharangkul, Thunyarat; Yakushi, Toshiharu; Matsushita, Kazunobu

    2017-05-01

    Butyrate is an important industrial platform chemical. Although several groups have reported butyrate production under oxygen-limited conditions by a native producer, Clostridium tyrobutylicum, and by a metabolically engineered Escherichia coli, efforts to produce butyrate under aerobic growth conditions have met limited success. Here, we constructed a novel butyrate synthetic pathway that functions under aerobic growth conditions in E. coli, by modifying the 1-butanol synthetic pathway reported previously. The pathway consists of phaA (acetyltransferase) and phaB (NADPH-dependent acetoacetyl-CoA reductase) from Ralstonia eutropha, phaJ ((R)-specific enoyl-CoA hydratase) from Aeromonas caviae, ter (trans-enoyl-CoA reductase) from Treponema denticola, and endogenous thioesterase(s) of E. coli. To evaluate the potential of this pathway for butyrate production, culture conditions, including pH, oxygen supply, and concentration of inorganic nitrogen sources, were optimized in a mini-jar fermentor. Under the optimal conditions, butyrate was produced at a concentration of up to 140 mM (12.3 g/L in terms of butyric acid) after 54 h of fed-batch culture. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Pingzhao Hu

    2009-04-01

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

  6. Mechanism of Sperm Immobilization by Escherichia coli

    Directory of Open Access Journals (Sweden)

    Vijay Prabha

    2010-01-01

    Conclusion. In conclusion, these results have shown immobilization of spermatozoa by E. coli and demonstrate a factor (SIF produced and secreted by E. coli which causes variable structural damage as probable morphological correlates of immobilization.

  7. Serogroups of Escherichia coli from drinking water.

    Science.gov (United States)

    Ramteke, P W; Tewari, Suman

    2007-07-01

    Fifty seven isolates of thermotolerant E. coli were recovered from 188 drinking water sources, 45 (78.9%) were typable of which 15 (26.3%) were pathogenic serotypes. Pathogenic serogroup obtained were 04 (Uropathogenic E. coli, UPEC), 025 (Enterotoxigenic E. coli, ETEC), 086 (Enteropathogenic E. coli, EPEC), 0103 (Shiga-toxin producing E. coli, STEC), 0157 (Shiga-toxin producing E. coli, STEC), 08 (Enterotoxigenic E. coli, ETEC) and 0113 (Shiga-toxin producing E. coli, STEC). All the pathogenic serotypes showed resistance to bacitracin and multiple heavy metal ions. Resistance to streptomycin and cotrimazole was detected in two strains whereas resistance to cephaloridine, polymixin-B and ampicillin was detected in one strain each. Transfer of resistances to drugs and metallic ions was observed in 9 out of 12 strains studied. Resistances to bacitracin were transferred in all nine strains. Among heavy metals resistance to As(3+) followed by Cr(6+) were transferred more frequently.

  8. Is Escherichia coli urinary tract infection a zoonosis?

    DEFF Research Database (Denmark)

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

    2012-01-01

    Recently, it has been suggested that the Escherichia coli causing urinary tract infection (UTI) may come from meat and animals. The purpose was to investigate if a clonal link existed between E. coli from animals, meat and UTI patients. Twenty-two geographically and temporally matched B2 E. coli...... and kidney cultures. Further, isolates with the same gene profile also yielded similar bacterial counts in urine, bladder and kidneys. This study showed a clonal link between E. coli from meat and humans, providing solid evidence that UTI is zoonosis. The close relationship between community-dwelling human...

  9. Rapid Sterilization of Escherichia coli by Solution Plasma Process

    Science.gov (United States)

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

    2012-12-01

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

  10. The Biology of the Escherichia coli Extracellular Matrix

    Science.gov (United States)

    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

  11. Characterization of bioreaction processes: aerobic Escherichia coli cultures.

    Science.gov (United States)

    Guardia Alba, M J; García Calvo, E

    2001-11-30

    The simulation of a microbial transformation course is an important tool for the optimal design or characterization of industrial processes. Usually, models are developed to describe a specific part of the culture such as microbial growth and most of the time ignore the influence of physical and chemical environment on growth dynamics of the microorganism. In this work we propose a method which combines the description of the evolution of components involved in the bioprocess including biomass and the physical environment generated mainly by the bioreactor characteristics and operational conditions. Stoichiometric, kinetic, fluid dynamics and mass transfer models are linked to predict the course of the Escherichia coli culture under the influence of different experimental conditions and types of bioreactors. A set of 22 kinetic and physical parameters obtained from independent experiments and from literature are used in order to predict glucose, biomass, acetate, dissolved oxygen and CO(2) concentrations in airlift and stirred tank bioreactors.

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

    OpenAIRE

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

    2016-01-01

    Background Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in ?backyard? farms in south-east Asia. Results Faecal samples collected...

  13. Carumonam enhances reactivity of Escherichia coli with mono- and polyclonal antisera to rough Escherichia coli J5.

    OpenAIRE

    Overbeek, B P; Schellekens, J F; Lippe, W; Dekker, B A; Verhoef, J

    1987-01-01

    Escherichia coli O111 reacts only slightly with antiserum to its rough mutant E. coli J5 in an enzyme-linked immunosorbent assay. When E. coli O111 was grown in the presence of sub-MICs of the monocyclic beta-lactam antibiotic carumonam, however, the enzyme-linked immunosorbent assay titer increased from 1,280 to 81,920. When the bacteria were grown in the presence of carumonam, the titer that was obtained with antiserum against E. coli O111 was not affected. This reaction was abolished after...

  14. Targeted cleavage of mRNA in vitro by RNase P from Escherichia coli.

    OpenAIRE

    Li, Y; Guerrier-Takada, C; Altman, S

    1992-01-01

    External guide sequences (EGSs) complementary to mRNAs that encode beta-galactosidase from Escherichia coli and nuclease A from Staphylococcus aureus can target these RNAs for cleavage in vitro by RNase P from E. coli. Specific cleavage occurs at locations predicted by the nucleotide sequences of the EGSs. EGSs with regions complementary to the mRNAs that are as short as 13 nucleotides function efficiently and turn over slowly during incubation with the target substrate and the enzyme. EGSs c...

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

    Science.gov (United States)

    Peskov, Kirill; Mogilevskaya, Ekaterina; Demin, Oleg

    2012-09-01

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

  16. Engineering an Escherichia coli platform to synthesize designer biodiesels.

    Science.gov (United States)

    Wierzbicki, Michael; Niraula, Narayan; Yarrabothula, Akshitha; Layton, Donovan S; Trinh, Cong T

    2016-04-20

    Biodiesels, fatty acid esters (FAEs), can be synthesized by condensation of fatty acid acyl CoAs and alcohols via a wax ester synthase in living cells. Biodiesels have advantageous characteristics over petrodiesels such as biodegradability, a higher flash point, and less emission. Controlling fatty acid and alcohol moieties are critical to produce designer biodiesels with desirable physiochemical properties (e.g., high cetane number, low kinematic viscosity, high oxidative stability, and low cloud point). Here, we developed a flexible framework to engineer Escherichia coli cell factories to synthesize designer biodiesels directly from fermentable sugars. In this framework, we designed each FAE pathway as a biodiesel exchangeable production module consisting of acyl CoA, alcohol, and wax ester synthase submodules. By inserting the FAE modules in an engineered E. coli modular chassis cell, we generated E. coli cell factories to produce targeted biodiesels (e.g., fatty acid ethyl (FAEE) and isobutyl (FAIbE) esters) with tunable and controllable short-chain alcohol moieties. The engineered E. coli chassis carrying the FAIbE production module produced 54mg/L FAIbEs with high specificity, accounting for>90% of the total synthesized FAEs and ∼4.7 fold increase in FAIbE production compared to the wildtype. Fed-batch cultures further improved FAIbE production up to 165mg/L. By mixing ethanol and isobutanol submodules, we demonstrated controllable production of mixed FAEEs and FAIbEs. We envision the developed framework offers a flexible, alternative route to engineer designer biodiesels with tunable and controllable properties using biomass-derived fermentable sugars. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Definition of Additional Flagellar Genes in ESCHERICHIA COLI K12

    OpenAIRE

    Komeda, Yoshibumi; Kutsukake, Kazuhiro; Iino, Tetsuo

    1980-01-01

    Twenty-nine flagellar genes in Escherichia coli K12 have previously been assigned to three regions of the genome. Flagellar region I is located between pyrC and ptsG, region II between aroD and uvrC, and region III between uvrC and his. In this study, flagellar mutants in Escherichia coli K12 were obtained by selection for resistance to the flagellotropic phage, χ. They were analyzed in complementation tests using P1 phage-mediated transduction. In addition to the fla genes already described,...

  18. Obscured phylogeny and possible recombinational dormancy in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Sawyer Stanley A

    2011-06-01

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

  19. Metabolic and Transcriptional Response to Cofactor Perturbations in Escherichia coli

    DEFF Research Database (Denmark)

    Holm, Anders Koefoed; Blank, L.M.; Oldiges, M.

    2010-01-01

    Metabolic cofactors such as NADH and ATP play important roles in a large number of cellular reactions, and it is of great interest to dissect the role of these cofactors in different aspects of metabolism. Toward this goal, we overexpressed NADH oxidase and the soluble F1-ATPase in Escherichia coli...... of redox and energy metabolism and should help in developing metabolic engineering strategies in E. coli....

  20. Engineering Escherichia coli for autoinducible production of n-butanol

    OpenAIRE

    Qinglong Wang; Yi ding; Li Liu; Jiping Shi; Junsong Sun; Yongchang Xue

    2015-01-01

    Background: Escherichia coli does not produce n-butanol naturally, but can be butanologenic when related enzymes were expressed using inducible elements on plasmids. In this study we attempted to confer E. coli strain capability of automatic excretion of the chemical by employing a native anaerobic promoter. Also, a novel DNA kit was designed for PCR preparation of linear DNA fragments to perform strain modification. The kit is primarily composed of two mother vectors, co-transformation of li...

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

    DEFF Research Database (Denmark)

    Schembri, Mark; Hjerrild, Louise; Gjermansen, Morten

    2003-01-01

    Antigen 43 (Ag43) is a self-recognizing surface adhesin found in most Escherichia coli strains. Due to its excellent cell-to-cell aggregation characteristics, Ag43 expression confers clumping and fluffing of cells and promotes biofilm formation. Ag43 expression is repressed by the cellular redox......-forming potential of E. coli. Finally, we demonstrated that Ag43-mediated cell aggregation confers significant protection against hydrogen peroxide killing....

  2. Genotypic Characterization of Egypt Enterotoxigenic Escherichia coli Isolates Expressing Coli Surface Antigen 6

    Science.gov (United States)

    2013-02-01

    USA Abstract Introduction: One approach to control enterotoxigenic Escherichia coli (ETEC) infections has been to develop vaccines focused on...results show a lack of clonality among Egypt CS6 E. coli isolates and supports the use and the further research on vaccines targeting this cell surface...organisms must colonize the mucosal epithelium; this process utilizes fimbrial and non-fimbrial colonization factors, also referred to as coli surface

  3. Seasonal influence of environmental variables and artificial aeration on Escherichia coli in small urban lakes.

    Science.gov (United States)

    Durham, Bart W; Porter, Lucy; Webb, Allie; Thomas, Joshua

    2016-12-01

    This study investigated patterns of Escherichia coli in urban lakes in Lubbock, Texas. Specific objectives were to (1) document seasonal patterns in abundance of E. coli over a 3-year period, (2) identify environmental factors, including effects of migratory geese and artificial aeration devices that may influence E. coli abundance, and (3) determine if E. coli abundance over time was similar for individual lakes. Water samples were collected monthly for 36 months from six lakes, three of which contained artificial aeration devices (fountains). Regression models were constructed to determine which environmental variables most influence E. coli abundance in summer and winter seasons. Escherichia coli is present in the lakes of Lubbock, Texas year-round and typically exceeds established bacterial thresholds for recreational waters. Models most frequently contained pH and dissolved oxygen as predictor variables and explained from 17.4% to 92.4% of total variation in E. coli. Lakes with fountains had a higher oxygen concentration during summer and contained consistently less E. coli. We conclude that solar irradiation in synergy with pH and dissolved oxygen is the primary control mechanism for E. coli in study lakes, and that fountains help control abundance of fecal bacteria within these systems.

  4. antimicrobial susceptibility and plasmids from escherichia coli

    African Journals Online (AJOL)

    2001-10-02

    Oct 2, 2001 ... shown to occur among different animal species, between humans, and from animals to humans and vice versa(5,6). Antibiotic resistant E. coli may be passed from animals to humans through contact with faecal material or faecally contaminated food sources. Normal E. coli flora acquire resistance plasmids ...

  5. Characterization of Escherichia coli Phylogenetic Groups ...

    African Journals Online (AJOL)

    infection, and neonatal meningitis.[1] Phylogenetic analysis has shown that E. coli strains fall into four main groups. (A, B1, B2, and D). It has been found that pathogenic E. coli strains causing extraintestinal infections mainly belong to group B2 and a lesser extent to group D whereas commensal strains belong to group A ...

  6. ANTIMICIROBIAL SUSCEPTIBILITY PATTERNS OF Escherichia coli ...

    African Journals Online (AJOL)

    DR. AMINU

    ABSTRACT. A total of 56 and 24 strains of E. coli and Shigella sp. isolated from children less than five years with diarrhoea attending 3 different hospitals in South South Nigeria were screened for their antibiotic resistance patterns. Approximately 80% of E. coli and 70% of Shigella isolates were resistant to tetracycline.

  7. Biochemical and serological characterization of Escherichia coli ...

    African Journals Online (AJOL)

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

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

    Directory of Open Access Journals (Sweden)

    Karp Peter D

    2006-01-01

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

  9. The carbon storage regulator (Csr) system exerts a nutrient-specific control over central metabolism in Escherichia coli strain Nissle 1917.

    Science.gov (United States)

    Revelles, Olga; Millard, Pierre; Nougayrède, Jean-Philippe; Dobrindt, Ulrich; Oswald, Eric; Létisse, Fabien; Portais, Jean-Charles

    2013-01-01

    The role of the post-transcriptional carbon storage regulator (Csr) system in nutrient utilization and in the control of the central metabolism in E. coli reference commensal strain Nissle 1917 was investigated. Analysis of the growth capabilities of mutants altered for various components of the Csr system (csrA51, csrB, csrC and csrD mutations) showed that only the protein CsrA - the key component of the system - exerts a marked role in carbon nutrition. Attenuation of CsrA activity in the csrA51 mutant affects the growth efficiency on a broad range of physiologically relevant carbon sources, including compounds utilized by the Entner-Doudoroff (ED) pathway. Detailed investigations of the metabolomes and fluxomes of mutants and wild-type cells grown on carbon sources representative of glycolysis and of the ED pathway (glucose and gluconate, respectively), revealed significant re-adjusting of central carbon metabolism for both compounds in the csrA51 mutant. However, the metabolic re-adjusting observed on gluconate was strikingly different from that observed on glucose, indicating a nutrient-specific control of metabolism by the Csr system.

  10. Characterisation of commensal Escherichia coli isolated from apparently healthy cattle and their attendants in Tanzania

    DEFF Research Database (Denmark)

    Madoshi, Balichene; Kudirkiene, Egle; Mtambo, Madundo

    2016-01-01

    While pathogenic types of Escherichia coli are well characterized, relatively little is known about the commensal E. coli flora. In the current study, antimicrobial resistance in commensal E. coli and distribution of ERIC-PCR genotypes among isolates of such bacteria from cattle and cattle...... attendants on cattle farms in Tanzania were investigated. Seventeen E. coli genomes representing different ERIC-PCR types of commensal E. coli were sequenced in order to determine their possible importance as a reservoir for both antimicrobial resistance genes and virulence factors. Both human and cattle...... specific. The most frequent plasmids replicon genes found in strains from both hosts were of IncF type, which are commonly associated with carriage of antimicrobial and virulence genes. Commensal E. coli from cattle and attendants were found to share same genotypes and to carry antimicrobial resistance...

  11. A new membrane filtration medium for simultaneous detection and enumeration of Escherichia coli and total coliforms.

    Science.gov (United States)

    Grant, M A

    1997-09-01

    Recovery of total coliforms and Escherichia coli on a new membrane filtration (MF) medium was evaluated with 25 water samples from seven states. Testing of the new medium, m-ColiBlue24 broth, was conducted according to a U.S. Environmental Protection Agency protocol. For comparison, this same protocol was used to measure recovery of total coliforms and E. coli with two standard MF media, m-Endo broth and mTEC broth. E. coli recovery on the new medium was also compared to recovery on nutrient agar supplemented with 4-methylumbelliferyl-beta-D-glucuronide. Comparison of specificity, sensitivity, false positive error, undetected target error, and overall agreement indicated E. coli recovery on m-ColiBlue24 was superior to recovery on mTEC for all five parameters. Recovery of total coliforms on the new medium was comparable to recovery on m-Endo.

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

    Science.gov (United States)

    Zuo, Guanghong; Xu, Zhao; Hao, Bailin

    2013-02-01

    Shigella species and Escherichia coli are closely related organisms. Early phenotyping experiments and several recent molecular studies put Shigella within the species E. coli. However, the whole-genome-based, alignment-free and parameter-free CVTree approach shows convincingly that four established Shigella species, Shigella boydii, Shigella sonnei, Shigella felxneri and Shigella dysenteriae, are distinct from E. coli strains, and form sister species to E. coli within the genus Escherichia. In view of the overall success and high resolution power of the CVTree approach, this result should be taken seriously. We hope that the present report may promote further in-depth study of the Shigella-E. coli relationship. Copyright © 2013. Production and hosting by Elsevier Ltd.

  13. Differential Decay of Enterococci and Escherichia coli Originating from Two Fecal Pollution Sources

    OpenAIRE

    Korajkic, Asja; McMinn, Brian R.; Harwood, Valerie J.; Shanks, Orin C.; Fout, G. Shay; Ashbolt, Nicholas J.

    2013-01-01

    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 habitats. In this study, sunlight exposure and indigenous aquatic microbiota were also important contributors, whose effects on FIB also differed between water types.

  14. The Escherichia coli antiterminator protein BglG stabilizes the 5 ...

    Indian Academy of Sciences (India)

    Unknown

    The β-glucoside utilization (bgl) genes of Escherichia coli are positively regulated by the product of the bglG gene, which functions as an antiterminator by binding to specific sequences present within the bgl mRNA. ..... experiment carried out in the presence of active BglG using the plasmid pAG-G transformed in JF201.

  15. Protein acetylation affects acetate metabolism, motility and acid stress response in Escherichia coli

    NARCIS (Netherlands)

    Castano-Cerezo, Sara|info:eu-repo/dai/nl/371746698; Bernal, Vicente; Post, Harm|info:eu-repo/dai/nl/341667374; Fuhrer, Tobias; Cappadona, Salvatore|info:eu-repo/dai/nl/341539031; Sanchez-Diaz, Nerea C.; Sauer, Uwe; Heck, Albert J. R.|info:eu-repo/dai/nl/105189332; Altelaar, A. F. Maarten|info:eu-repo/dai/nl/304833517; Canovas, Manuel

    2014-01-01

    Although protein acetylation is widely observed, it has been associated with few specific regulatory functions making it poorly understood. To interrogate its functionality, we analyzed the acetylome in Escherichia coli knockout mutants of cobB, the only known sirtuin-like deacetylase, and patZ, the

  16. Phylogeny and disease association of Shiga toxin-producing Escherichia coli O91

    NARCIS (Netherlands)

    Mellmann, Alexander; Fruth, Angelika; Friedrich, Alexander W; Wieler, Lothar H; Harmsen, Dag; Werber, Dirk; Middendorf, Barbara; Bielaszewska, Martina; Karch, Helge

    The diversity and relatedness of 100 Shiga toxin-producing Escherichia coli O91 isolates from different patients were examined by multilocus sequence typing. We identified 10 specific sequence types (ST) and 4 distinct clonal groups. ST442 was significantly associated with hemolytic uremic syndrome.

  17. Integrons in Escherichia coli from food-producing animals in The Netherlands

    NARCIS (Netherlands)

    Box, A.T.; Mevius, D.J.; Schellen, P.; Verhoef, J.; Fluit, A.C.

    2005-01-01

    The presence and character of class 1 integrons in multidrug-resistant Escherichia coli from slaughter animals and meat was determined by integrase-specific PCR and conserved segment PCR-restriction fragment length polymorphism (RFLP). At least five different class 1 integron types were found and

  18. A phosphoethanolamine transferase specific for the outer 3-deoxy-D-manno-octulosonic acid residue of Escherichia coli lipopolysaccharide. Identification of the eptB gene and Ca2+ hypersensitivity of an eptB deletion mutant

    National Research Council Canada - National Science Library

    Reynolds, C Michael; Kalb, Suzanne R; Cotter, Robert J; Raetz, Christian R H

    2005-01-01

    ...) residue of lipopolysaccharide (LPS) in WBB06, a heptose-deficient Escherichia coli mutant, occurs when cells are grown in 5-50 mM CaCl2 (Kanipes, M. I., Lin, S., Cotter, R. J., and Raetz, C. R. H. (2001) J. Biol. Chem. 276, 1156-1163). A Ca2...

  19. The Pai-associated leuX specific tRNA5(Leu) affects type 1fimbriation in pathogenic Escherichia coli by control of FimB recombinase expression

    DEFF Research Database (Denmark)

    Ritter, A.; Gally, D.; Olsen, Peter Bjarke

    1997-01-01

    The uropathogenic Escherichia coli strain 536 (06:K15:H31) carries two large chromosomalpathogenicity islands (Pais). Both Pais are flanked by tRNA genes. Spontaneous deletion of Pai IIresults in truncation of the leuX tRNA5Leu gene. This tRNA is required for the expression of type 1fimbriae (Fim...

  20. The Stress Response of Escherichia coli under Microgravity.

    Science.gov (United States)

    Lynch, S.; Matin, A.

    At the onset of adverse environmental conditions, bacteria induce a controlled stress response to enable survival. Escherichia coli induces stress-specific reactions in response to a variety of environmental strains. A family of proteins termed sigma (s) factors is pivotal to the regulation of stress responses in bacteria. In particular Sigma S (ss) regulates several stress responses in E. coli and serves as an important global stress regulatory protein. Under optimal growth conditions, levels of ss are maintained at low cellular concentrations primarily via a proteolytic regulatory mechanism. At the onset of stress, ss levels increase due to increased stability of the molecule, facilitating transcriptional initiation and up regulation of specific stress related proteins. Concentrations of ss can therefore be indicative of cellular stress levels. Recent work by Kendrick et al demonstrated that Salmonella species grown under conditions of simulated microgravity display increased virulence - a stress-related phenotype. Using E. coli as a model system we aim to investigate the stress response elicited by the organism under conditions of simulated microgravity (SMG). SMG is generated in specially constructed rotary cell culture systems termed HARVs (High Aspect Ratio Vessels- Synthecon Inc.). By rotating at constant velocity around a vertical axis an environment is produced in which the gravitational vectors are randomized over the surface of the cell, resulting in an overall-time-averaged gravitational vector of 10-2 x g (4). E. coli cultures grown in HARVs under conditions of normal gravity (NG) and SMG repeatedly display slower growth kinetics under SMG. Western analysis of cells at exponential and stationary phase of growth from both cultures reveal similar levels of ss exist in exponential phase under both SMG and NG conditions. However, during stationary phase, levels of ss are at least 2-fold higher under conditions of SMG as compared to NG. Translational fusion

  1. An integrated database to support research on Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Baehr, A.; Dunham, G.; Matsuda, Hideo; Michaels, G.; Taylor, R.; Overbeek, R.; Rudd, K.E. (National Inst. of Mental Health, Bethesda, MD (United States)); Ginsburg, A.; Joerg, D.; Kazic, T. (Washington Univ., St. Louis, MO (United States). Dept. of Genetics); Hagstrom, R.; Zawada, D. (Argonne National Lab., IL (United States)); Smith, C.; Yoshida, Kaoru (Lawrence Berkeley Lab., CA (United States))

    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.

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

    Directory of Open Access Journals (Sweden)

    A. Rella

    2013-02-01

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

  3. Spontaneous Escherichia coli Meningitis Associated with Hemophagocytic Lymphohistiocytosis

    Directory of Open Access Journals (Sweden)

    Kuo-Hsuan Chang

    2006-01-01

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

  4. Experimental Escherichia coli O157:H7 carriage in calves.

    OpenAIRE

    Brown, C A; Harmon, B G; Zhao, T; Doyle, M P

    1997-01-01

    Nine weaned calves (6 to 8 weeks of age) were given 10(10) CFU of a five-strain mixture of enterohemorrhagic Escherichia coli O157:H7 by oral-gastric intubation. After an initial brief period of pyrexia in three calves and transient mild diarrhea in five calves, calves were clinically normal throughout the 13- to 27-day study. The population of E. coli O157:H7 in the faces decreased dramatically in all calves during the first 2 weeks after inoculation. Thereafter, small populations of E. coli...

  5. Escherichia coli is naturally transformable in a novel transformation system.

    Science.gov (United States)

    Sun, Dongchang; Zhang, Yanmei; Mei, Yunjun; Jiang, Hui; Xie, Zhixiong; Liu, Huihui; Chen, Xiangdong; Shen, Ping

    2006-12-01

    A novel transformation system, in which neither a nonphysiological concentration of Ca2+ and temperature shifts nor electronic shocks were required, was developed to determine whether Escherichia coli is naturally transformable. In the new protocol, E. coli was cultured normally to the stationary phase and then cultured statically at 37 degrees C in Luria-Bertani broth. After static culture, transformation occurred in bacteria spread on Luria-Bertani plates. The protein synthesis inhibitor chloramphenicol inhibited this transformation process. The need for protein synthesis in plated bacteria suggests that the transformation of E. coli in this new system is regulated physiologically.

  6. Bacteriophages with the Ability to Degrade Uropathogenic Escherichia Coli Biofilms

    Directory of Open Access Journals (Sweden)

    Amee Manges

    2012-04-01

    Full Text Available Escherichia coli-associated urinary tract infections (UTIs are among the most common bacterial infections in humans. UTIs are usually managed with antibiotic therapy, but over the years, antibiotic-resistant strains of uropathogenic E. coli (UPEC have emerged. The formation of biofilms further complicates the treatment of these infections by making them resistant to killing by the host immune system as well as by antibiotics. This has encouraged research into therapy using bacteriophages (phages as a supplement or substitute for antibiotics. In this study we characterized 253 UPEC in terms of their biofilm-forming capabilities, serotype, and antimicrobial resistance. Three phages were then isolated (vB_EcoP_ACG-C91, vB_EcoM_ACG-C40 and vB_EcoS_ACG-M12 which were able to lyse 80.5% of a subset (42 of the UPEC strains able to form biofilms. Correlation was established between phage sensitivity and specific serotypes of the UPEC strains. The phages’ genome sequences were determined and resulted in classification of vB_EcoP_ACG-C91 as a SP6likevirus, vB_EcoM_ACG-C40 as a T4likevirus and vB_EcoS_ACG-M12 as T1likevirus. We assessed the ability of the three phages to eradicate the established biofilm of one of the UPEC strains used in the study. All phages significantly reduced the biofilm within 2–12 h of incubation.

  7. Expression of a soluble truncated Vargula luciferase in Escherichia coli.

    Science.gov (United States)

    Hunt, Eric A; Moutsiopoulou, Angeliki; Broyles, David; Head, Trajen; Dikici, Emre; Daunert, Sylvia; Deo, Sapna K

    2017-04-01

    Marine luciferases are regularly employed as useful reporter molecules across a range of various applications. However, attempts to transition expression from their native eukaryotic environment into a more economical prokaryotic, i.e. bacterial, expression system often presents several challenges. Specifically, bacterial protein expression inherently lacks chaperone proteins to aid in the folding process, while Escherichia coli presents a reducing cytoplasmic environment in. These conditions contribute to the inhibition of proper folding of cysteine-rich proteins, leading to incorrect tertiary structure and ultimately inactive and potentially insoluble protein. Vargula luciferase (Vluc) is a cysteine-rich marine luciferase that exhibits glow-type bioluminescence through a reaction between its unique native substrate and molecular oxygen. Because most other commonly used bioluminescent proteins exhibit flash-type emission kinetics, this emission characteristic of Vluc is desirable for high-throughput applications where stability of emission is required for the duration of data collection. A truncated form of Vluc that retains considerable bioluminescence activity (55%) compared to the native full-length protein has been reported in the literature. However, expression and purification of this luciferase from bacterial systems has proven difficult. Herein, we demonstrate the expression and purification of a truncated form of Vluc from E. coli. This truncated Vluc (tVluc) was subsequently characterized in terms of both its biophysical and bioluminescence properties. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2017-01-01

    Antimicrobial resistance associated with colistin has emerged as a significant concern worldwide threatening the use of one of the most important antimicrobials for treating human disease. Here, we examined a collection (n = 980) of Avian Pathogenic Escherichia coli (APEC) isolated from poultry with colibacillosis from the US and internationally for the presence of mcr-1 and mcr-2, genes known to encode colistin resistance. Included in the analysis was an additional set of avian fecal E. coli (AFEC) (n = 220) isolates from healthy birds for comparative analysis. The mcr-1 gene was detected in a total of 12 isolates recovered from diseased production birds from China and Egypt. No mcr genes were detected in the healthy fecal isolates. The full mcr-1 gene from positive isolates was sequenced using specifically designed primers and were compared with sequences currently described in NCBI. mcr-1 positive isolates were also assessed for phenotypic colistin resistance and extended spectrum beta lactam phenotypes and genotypes. This study has identified mcr-1 in APEC isolates dating back to at least 2010 and suggests that animal husbandry practices could result in a potential source of resistance to the human food chain in countries where application of colistin in animal health is practiced.

  9. Expression of recombinant alkaline phosphatase conjugates in Escherichia coli.

    Science.gov (United States)

    Boulain, Jean-Claude; Ducancel, Frédéric

    2004-01-01

    The methods described in this article are relative to the use of a positive cloning/screening recombinant system for the generation in Escherichia coli of foreign proteins fused to a highly active bacterial alkaline phosphatase (PhoA) variant as reporter enzyme. Appropriate insertion of the DNA encoding the foreign peptides, proteic domains, or proteins between codons +6 and +7 of the phoa gene restores the initial frame of the phoa gene in the vector. Consequently, only recombinant clones appear as blue colonies when plating onto an agar medium containing a chromogenic substrate for PhoA. The presence of an intact PhoA signal peptide yields to a systematic secretion of the fusion proteins into the periplasm where the PhoA dimerises to its active form, and disulfides can be formed if necessary. The resultant PhoA-tagged proteins are particularly convenient novel tools that can be used in a wide range of applications, including expression, epitope mapping, histochemistry, immunoblotting, mutant analysis, and competition or sandwich ELISAs. Expression of an scFv antibody fragment derived from an IgG2a/kappa immunoglobulin specific for curaremimetic toxins from snake (named M-alpha2-3), will be used to illustrate the methods utilized for its cloning, expression in E.coli, extraction, and functional characterization.

  10. Single Multiplex PCR Assay To Identify Simultaneously the Six Categories of Diarrheagenic Escherichia coli Associated with Enteric Infections

    Science.gov (United States)

    Vidal, Maricel; Kruger, Eileen; Durán, Claudia; Lagos, Rosanna; Levine, Myron; Prado, Valeria; Toro, Cecilia; Vidal, Roberto

    2005-01-01

    We designed a multiplex PCR for the detection of all categories of diarrheagenic Escherichia coli. This method proved to be specific and rapid in detecting virulence genes from Shiga toxin-producing (stx1, stx2, and eae), enteropathogenic (eae and bfp), enterotoxigenic (stII and lt), enteroinvasive (virF and ipaH), enteroaggregative (aafII), and diffuse adherent (daaE) Escherichia coli in stool samples. PMID:16208019

  11. Enhanced gentamicin killing of Escherichia coli by tet gene expression.

    OpenAIRE

    Merlin, T L; Corvo, D L; Gill, J H; Griffith, J K

    1989-01-01

    Time-kill studies were performed to determine the effect of tetracycline resistance (tet) gene expression on gentamicin killing of Escherichia coli. Expression of tet increased gentamicin killing in laboratory strains and clinical isolates. A role for tetracycline in inducing tet expression and increasing the bactericidal activity of aminoglycosides is suggested.

  12. Expression and purification of recombinant hemoglobin in Escherichia coli

    DEFF Research Database (Denmark)

    Natarajan, Chandrasekhar; Jiang, Xiaoben; Fago, Angela

    2011-01-01

    BACKGROUND: Recombinant DNA technologies have played a pivotal role in the elucidation of structure-function relationships in hemoglobin (Hb) and other globin proteins. Here we describe the development of a plasmid expression system to synthesize recombinant Hbs in Escherichia coli, and we describe...

  13. Stabilization of Escherichia coli uridine phosphorylase by evolution and immobilization

    CSIR Research Space (South Africa)

    Visser, Daniel F

    2010-08-01

    Full Text Available Uridine phosphorylase from Escherichia coli was evolved by iterative saturation mutagenesis. The best mutant showed a temperature optimum of 60C and a half-life of 17.3 h at 60C. The mutant enzyme, as well as a purine nucleoside phosphorylase from...

  14. Fragility of the permeability barrier of Escherichia coli

    NARCIS (Netherlands)

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

    1972-01-01

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

  15. Novel roles for the AIDA adhesin from diarrheagenic Escherichia coli:

    DEFF Research Database (Denmark)

    Sherlock, Orla; Schembri, Mark; Reisner, A.

    2004-01-01

    Diarrhea-causing Escherichia coli strains are responsible for numerous cases of gastrointestinal disease and constitute a serious health problem throughout the world. The ability to recognize and attach to host intestinal surfaces is an essential step in the pathogenesis of such strains. AIDA is ...

  16. Antibiotic resistance profile of Escherichia coli isolated from five ...

    African Journals Online (AJOL)

    Information on the resistance profiles of clinical and non clinical human bacteria isolates in the developing countries can serve as important means of understanding the human pathogens drug resistance interactions in the zone. Escherichia coli isolated from five geopolitical zones of Nigeria were screened for anti-microbial ...

  17. Search for Enterohaemorrhagic Escherichia coli O157:H7 and ...

    African Journals Online (AJOL)

    Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 and Salmonella enterica are important zoonotic bacteria responsible for enteric infections in humans. The present study investigated the possible role of kittens in the zoonotic transmission of antimicrobial resistant EHEC O157 and Salmonella enterica to human using ...

  18. Antibiotic Resistance in Salmonella sp and Escherichia coli Isolated ...

    African Journals Online (AJOL)

    From the lactose and non lactose fermenters isolated, 16 Salmonella sp and 45 Escherichia coli isolates were identified by colonial morphology on agars, Gram staining, and biochemical tests. The highest mean total aerobic counts of the organism population isolated were obtained from farms C (6.52±0.17logcfu/ml) and D ...

  19. Antibiotic Resistant Salmonella And Escherichia Coli Isolated From ...

    African Journals Online (AJOL)

    Our investigation revealed that Escherichia coli and Salmonella organisms were isolated in the outbreaks. A pattern of antibiotic resistance that seems to be increasing was also found. Considering the role of chickens and its products in the human food chain in Nigeria; and the close interaction between poultry and man, ...

  20. Mutators and hypermutability in bacteria: the Escherichia coli ...

    Indian Academy of Sciences (India)

    Being a mutator is advantageous to the organism when adapting to environmental changes or stressful situations, such as moving from one habitat to another, ... mismatch repair, oxidative DNA damage, mistranslation etc., as well as phenomena associated with these processes, using Escherichia coli as a paradigmatic ...

  1. Escherichia coli bacteraemia in patients with and without haematological malignancies

    DEFF Research Database (Denmark)

    Olesen, B; Kolmos, H J; Orskov, F

    1998-01-01

    We compared serotypes, virulence factors and susceptibility to antibiotics of Escherichia coli strains isolated from 282 patients with bacteraemia. Thirty-five of these were neutropenic patients with haematological malignancy and 247 were patients with a normal or raised total white blood cell co...

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

    Science.gov (United States)

    1984-01-01

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

  3. Carbon and energy metabolism of atp mutants of Escherichia coli

    DEFF Research Database (Denmark)

    Jensen, Peter Ruhdal; Michelsen, Ole

    1992-01-01

    The membrane-bound H+-ATPase plays a key role in free-energy transduction of biological systems. We report how the carbon and energy metabolism of Escherichia coli changes in response to deletion of the atp operon that encodes this enzyme. Compared with the isogenic wild-type strain, the growth...

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

    African Journals Online (AJOL)

    2015-07-04

    Jul 4, 2015 ... ... quality of roof-harvested rainwater was assessed by monitoring the concentrations of Escherichia coli, enterococci, Clostridium perfringens, and Bacteroides spp. in rainwater obtained from tanks in Southeast Queensland,. Australia. Samples were also tested using real-time PCR (with. SYBR Green I dye.

  5. Binding of Divalent Magnesium by Escherichia coli Phosphoribosyl Diphosphate Synthetase

    DEFF Research Database (Denmark)

    Willemoës, Martin; Hove-Jensen, Bjarne

    1997-01-01

    The mechanism of binding of the substrates MgATP and ribose 5-phosphate as well as Mg2+ to the enzyme 5-phospho-d-ribosyl a-1-diphosphate synthetase from Escherichia coli has been analyzed. By use of the competive inhibitors of ATP and ribose 5-phosphate binding, a,ß-methylene ATP and (+)-1-a,2-a...

  6. prevalence and antibiotic resistance patterns of escherichia coli

    African Journals Online (AJOL)

    2014-06-01

    Jun 1, 2014 ... 91 No. 6 June 2014. PREVALENCE AND ANTIBIOTIC RESISTANCE PATTERNS OF ESCHERICHIA COLI AMONG HOSPITALISED ... inpatients at Thika District Hospital (TDH) and to determine antimicrobial resistance patterns to β-lactams .... The World Health Organization (WHO) guidelines recommend ...

  7. Antibacterial effects of zinc oxide nanoparticles on Escherichia coli ...

    African Journals Online (AJOL)

    This study was conducted to evaluate the antibacterial effects of zinc oxide nanoparticles in vitro. Escherichia coli K88 was chosen as an indicator of pathogenic bacteria, because it could cause diarrhea in both children and in early-weaned piglets. In this study, the characterization of the nanoparticles was examined.

  8. Inhibition of respiration of Escherichia coli by thioglycerol.

    OpenAIRE

    Javor, G T

    1983-01-01

    Anaerobic growth on glucose significantly protected Escherichia coli from growth inhibition by thioglycerol. Methionine and anaerobiosis completely overcame growth inhibition by 2 to 90 mM thioglycerol. The respiration of aerobically growing cells was partially inhibited by 20 to 90 mM thioglycerol.

  9. Antibiotic Sensitivity Profile of Escherichia coli Isolated from Poultry ...

    African Journals Online (AJOL)

    A cross sectional study involving 300 cloaca swabs from apparently healthy birds from 8 small-medium scale poultry farms in Ibadan Oyo State was carried out. A total of 201 (67%) Escherichia coli isolates were recovered from the birds and they were subjected to in-vitro antibiotic sensitivity test by agar gel diffusion method.

  10. Modelling nitrogen assimilation of Escherichia coli at low ammonium concentration.

    NARCIS (Netherlands)

    Ma, H.; Boogerd, F.C.; Goryanin, I.

    2009-01-01

    Modelling is an important methodology in systems biology research. In this paper, we presented a kinetic model for the complex ammonium assimilation regulation system of Escherichia coli. Based on a previously published model, the new model included AmtB mediated ammonium transport and AmtB

  11. Effect of visible range electromagnetic radiations on Escherichia coli ...

    African Journals Online (AJOL)

    Background: Escherichia coli is the agent responsible for a range of clinical diseases. With emerging antimicrobial resistance, other treatment options including solar/photo-therapy are becoming increasingly common. Visible Range Radiation Therapy/Colour Therapy is an emerging technique in the field of ...

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  13. Multiple-Resistant Commensal Escherichia Coli from Nigerian ...

    African Journals Online (AJOL)

    Purpose: The antimicrobial susceptibility and virulence traits of 150 strains of Escherichia coli characterized as commensals recovered from faecal samples from pre-school age children in Ile-Ife, Nigeria were evaluated in order to determine their potentials for pathogenicity and their contribution to antibiotic resistance in the ...

  14. Enterohaemorrhagic Escherichia coli O157: a current threat ...

    African Journals Online (AJOL)

    Enterohaemorrhagic. Escherichia coli O157: a survey of dairy cattle in. Tripoli, Libya' (1). The Libyan data presented by Ghen- ghesh et al. in the 1990s were based on the analysis of stool specimens from pediatric patients aged between only a ...

  15. [Mycotic coronary aneurysm with Escherichia coli sepsis: a case report].

    Science.gov (United States)

    Lemoine, J; Popovic, B; Amrein, D; Lemoine, S; Angioi, M; Moulin, F; Ethevenot, G; Aliot, E; Brembilla Perrot, B

    2007-06-01

    We report the case of a patient who was admitted for acute coronary syndrom associated with fever originating from urinary tract. Coronary arteriography revealed a huge coronary aneurysm which ruptured a short time after diagnosis. After surgery, it was proven to be mycotic aneurysm related to Escherichia Coli sepsis.

  16. Gene encoding virulence markers among Escherichia coli isolates ...

    African Journals Online (AJOL)

    driniev

    diarrhoeic stool samples was included. Escherichia coli was isolated and identified by standard cultural and biochemical methods. ... Apart from protozoans such as Giardia lamblia, Enta- moeba histolytica, Cryptosporidium .... Briefly, an overnight bacterial culture was suspended in sterile distilled water and heated at 94°C ...

  17. Glucose transport in Salmonella typhimurium and Escherichia coli

    NARCIS (Netherlands)

    Postma, P. W.; Neyssel, O. M.; van Ree, R.

    1982-01-01

    We have investigated the claim by Schweiger and coworkers [Eur. J. Biochem. 102(1979)231-236] that glucose transport in Escherichia coli is catalyzed mainly by an ATP-dependent transport system instead of the phosphoenolpyruvate:sugar phosphotransferase system. A major argument was the differential

  18. DNA microarray analysis of fim mutations in Escherichia coli

    DEFF Research Database (Denmark)

    Schembri, Mark; Ussery, David; Workman, Christopher

    2002-01-01

    Bacterial adhesion is often mediated by complex polymeric surface structures referred to as fimbriae. Type I fimbriae of Escherichia coli represent the archetypical and best characterised fimbrial system. These adhesive organelles mediate binding to D-mannose and are directly associated with viru...

  19. armA and aminoglycoside resistance in Escherichia coli.

    Science.gov (United States)

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

    2005-06-01

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

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

    OpenAIRE

    Lorowitz, W; CLARK, D.

    1982-01-01

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

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

    Science.gov (United States)

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

  2. Effect of phytoplankton on Escherichia coli survival in laboratory microcosms

    Science.gov (United States)

    Fecal contamination of water sources is an important water quality issue for agricultural irrigation ponds. Escherichia coli is a common microbial indicator used to evaluate recreational and irrigation water quality. Nuisance algae commonly grow in low- or no-flow irrigation water source The objecti...

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

    Science.gov (United States)

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

  4. Characterization of Escherichia coli nucleoids released by osmotic shock

    NARCIS (Netherlands)

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

    2012-01-01

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

  5. Antibiotic Resistance of Escherichia coli Isolated from Healthy Food ...

    African Journals Online (AJOL)

    The antimicrobial resistance profile of 204 Escherichia coli isolates of bovine, swine and poultry origin to eight (8) antimicrobial agents was studied. Antimicrobial susceptibility tests were determined using the disk diffusion technique. Full sensitivity to all the eight antimicrobial agents in the test panel was observed in 46 % of ...

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

    DEFF Research Database (Denmark)

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

    1996-01-01

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

  7. Suppressors of DnaAATP imposed overinitiation in Escherichia coli

    DEFF Research Database (Denmark)

    Charbon, Godefroid; Riber, Leise; Cohen, Malene

    2011-01-01

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

  8. Occurrence of Escherichia coli in Brassica rapa L. chinensis ...

    African Journals Online (AJOL)

    Low quality water has become valuable resource with restricted or unrestricted use in food production depending on its quality. This study has quantified the occurrence of Escherichia coli in Brassica rapa L. chinensis (Chinese cabbage) vegetables and low quality irrigation water. A total of 106 samples including Chinese ...

  9. Multiple-Resistant Commensal Escherichia Coli from Nigerian ...

    African Journals Online (AJOL)

    Purpose: The antimicrobial susceptibility and virulence traits of 150 strains of Escherichia coli characterized as commensals recovered from faecal samples from pre-school age children in Ile-Ife,. Nigeria were evaluated in order to determine their potentials for pathogenicity and their contribution to antibiotic resistance in the ...

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

    DEFF Research Database (Denmark)

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

    1996-01-01

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

  11. Antibiotic resistance status of Escherichia coli isolated from healthy ...

    African Journals Online (AJOL)

    Antibiotic resistance status of Escherichia coli isolated from healthy pigs from some piggery farms in Ibadan, Nigeria. ... tetracycline, ampicillin, kanamycin, streptomycin and nalidixic acid (all obtained from SIGMA-ALDRICH, USA) according to standard methods specified by Clinical Laboratory Standards Institute.

  12. Enterohaemorrhagic Escherichia coli O157: a survey of dairy cattle ...

    African Journals Online (AJOL)

    The zoonotic potential of enterohaemorrhagic. Escherichia coli (EHEC) subtype O157 represents a serious food-borne threat to human health. (1Б3). A common animal vector of this pathogen is cattle, and human cases of infection are frequently caused by ingesting food products contaminated with bacteria shed in the ...

  13. Escherichia Coli Removal from Water Using Electrophotocatalytic ...

    African Journals Online (AJOL)

    Michael Horsfall

    -40). The findings showed the ... nanoparticles stabilized on zinc. As safe drinking water should not contain E. coli, this organism was studied as the model organism and an indicator in this study. ..... performance paint coatings. Asian J. Exp.

  14. Heterologous biosynthesis of triterpenoid ambrein in engineered Escherichia coli.

    Science.gov (United States)

    Ke, Di; Caiyin, Qinggele; Zhao, Fanglong; Liu, Ting; Lu, Wenyu

    2018-02-01

    To genetically engineer Escherichia coli for the heterologous biosynthesis of triterpenoid, ambrein, the main bioactive component of ambergris, by constituting a novel squalene-derived ambrein biosynthetic pathway in E. coli. The ScERG9 gene encoding the squalene synthase (SS) was integrated into the E. coli genome to generate a squalene-producing strain that supplied the central precursor squalene for the formation of cyclic triterpenoids. The mutated squalene-hopene synthase (D377C SHC) and the tetraprenyl-β-curcumene cyclase (BmeTC) were co-expressed with SS to construct a novel ambrein biosynthetic pathway in E. coli. Ambrein was produced at 2.6 mg l -1 . An E. coli chassis for ambrein production was constructed by combining the squalene synthesis module with the downstream cyclization module.

  15. Association of cytolethal distending toxin-II gene-positive Escherichia coli with Escherichia albertii, an emerging enteropathogen.

    Science.gov (United States)

    Hinenoya, Atsushi; Yasuda, Noritomo; Mukaizawa, Natsuko; Sheikh, Sikander; Niwa, Yuko; Awasthi, Sharda Prasad; Asakura, Masahiro; Tsukamoto, Teizo; Nagita, Akira; Albert, M John; Yamasaki, Shinji

    2017-12-01

    Cytolethal distending toxin (CDT)-producing Escherichia coli have been isolated from patients with diarrhea, sepsis and urinary tract infection. CDT of E. coli is divided into five types (CDT-I through CDT-V) based on differences in amino acid sequences and its genomic location. However, in our recent studies, a few strains of cdt-II gene-positive bacteria, initially identified as atypical E. coli, were re-identified as Escherichia albertii, an emerging enteropathogen, by extensive characterization including multilocus sequence (MLS) analysis and sugar utilization tests. This finding prompted us to investigate if bacteria previously identified as cdt-II gene-positive E. coli might be E. albertii. In the present study, we therefore re-examined the identity of 20 cdt-II gene-positive bacteria isolated from children with diarrhea, which were initially identified as atypical E. coli. By extensive sugar utilization tests, these bacteria showed a closer relatedness to E. albertii than E. coli, because they did not ferment any of the tested sugars including dulcitol, lactose, d-melibiose, l-rhamnose and d-xylose. Further, both phylogenetic analyses based on nucleotide sequences of 7 housekeeping genes (MLS analysis) and rpoB gene showed that all the cdt-II gene-positive bacteria belonged to a distinct lineage of E. albertii from those of E. coli and Shigella boydii. They were also positive by an E. albertii-specific PCR. Taken together, these data suggest that cdt-II gene-positive bacteria previously identified as E. coli are actually E. albertii. Therefore, we suggest a new definition for cdt-II gene-positive E. coli as E. albertii with the inclusion of CDT-II in E. albertii CDT. Copyright © 2017 Elsevier GmbH. All rights reserved.

  16. WGS accurately predicts antimicrobial resistance in Escherichia coli.

    Science.gov (United States)

    Tyson, Gregory H; McDermott, Patrick F; Li, Cong; Chen, Yuansha; Tadesse, Daniel A; Mukherjee, Sampa; Bodeis-Jones, Sonya; Kabera, Claudine; Gaines, Stuart A; Loneragan, Guy H; Edrington, Tom S; Torrence, Mary; Harhay, Dayna M; Zhao, Shaohua

    2015-10-01

    The objective of this study was to determine the effectiveness of WGS in identifying resistance genotypes of MDR Escherichia coli and whether these correlate with observed phenotypes. Seventy-six E. coli strains were isolated from farm cattle and measured for phenotypic resistance to 15 antimicrobials with the Sensititre(®) system. Isolates with resistance to at least four antimicrobials in three classes were selected for WGS using an Illumina MiSeq. Genotypic analysis was conducted with in-house Perl scripts using BLAST analysis to identify known genes and mutations associated with clinical resistance. Over 30 resistance genes and a number of resistance mutations were identified among the E. coli isolates. Resistance genotypes correlated with 97.8% specificity and 99.6% sensitivity to the identified phenotypes. The majority of discordant results were attributable to the aminoglycoside streptomycin, whereas there was a perfect genotype-phenotype correlation for most antibiotic classes such as tetracyclines, quinolones and phenicols. WGS also revealed information about rare resistance mechanisms, such as structural mutations in chromosomal copies of ampC conferring third-generation cephalosporin resistance. WGS can provide comprehensive resistance genotypes and is capable of accurately predicting resistance phenotypes, making it a valuable tool for surveillance. Moreover, the data presented here showing the ability to accurately predict resistance suggest that WGS may be used as a screening tool in selecting anti-infective therapy, especially as costs drop and methods improve. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  17. Binding of collagens to an enterotoxigenic strain of Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Visai, L.; Speziale, P.; Bozzini, S. (Univ. of Pavia (Italy))

    1990-02-01

    An enterotoxigenic strain of Escherichia coli, B34289c, has been shown to bind the N-terminal region of fibronectin with high affinity. We now report that this strain also binds collagen. The binding of 125I-labeled type II collagen to bacteria was time dependent and reversible. Bacteria expressed a limited number of collagen receptors (2.2 x 10(4) per cell) and bound collagen with a Kd of 20 nM. All collagen types tested (I to V) as well as all tested cyanogen bromide-generated peptides (alpha 1(I)CB2, alpha 1(I)CB3, alpha 1(I)CB7, alpha 1(I)CB8, and alpha 2(I)CB4) were recognized by bacterial receptors, as demonstrated by the ability of these proteins to inhibit the binding of 125I-labeled collagen to bacteria. Of several unlabeled proteins tested in competition experiments, fibronectin and its N-terminal region strongly inhibited binding of the radiolabeled collagen to E. coli cells. Conversely, collagen competed with an 125I-labeled 28-kilodalton fibronectin fragment for bacterial binding. Collagen bound to bacteria could be displaced by excess amounts of either unlabeled fibronectin or its N-terminal fragment. Similarly, collagen could displace 125I-labeled N-terminal peptide of fibronectin bound to the bacterial cell surface. Bacteria grown at 41 degrees C or in the presence of glucose did not express collagen or fibronectin receptors. These results indicate the presence of specific binding sites for collagen on the surface of E. coli cells and furthermore that the collagen and fibronectin binding sites are located in close proximity, possibly on the same structure.

  18. Carbon nanoparticles in lateral flow methods to detect genes encoding virulence factors of Shiga toxin-producing Escherichia coli

    NARCIS (Netherlands)

    Noguera, P.; Posthuma-Trumpie, G.A.; Tuil, van M.; Wal, van der F.J.; Boer, de A.; Moers, A.P.H.A.; Amerongen, van A.

    2011-01-01

    The use of carbon nanoparticles is shown for the detection and identification of different Shiga toxin-producing Escherichia coli virulence factors (vt1, vt2, eae and ehxA) and a 16S control (specific for E. coli) based on the use of lateral flow strips (nucleic acid lateral flow immunoassay,

  19. The orphan gene ybjN conveys pleiotropic effects on multicellular behavior and survival of Escherichia coli

    Science.gov (United States)

    YbjN, an enterobacteria-specific protein, is a multicopy suppressor of ts9 temperature sensitivity in Escherichia coli. In this study, we further explored the roles of ybjN, an orphan gene in E. coli. First, we demonstrated that ybjN gene was down-regulated about 10-fold in ts9 strain compared to th...

  20. Differentiating enteric Escherichia coli from environmental bacteria through the putative glucosyltransferase gene (ycjM).

    Science.gov (United States)

    Deng, Daiyong; Zhang, Ning; Mustapha, Azlin; Xu, Dong; Wuliji, Tumen; Farley, Mary; Yang, John; Hua, Bin; Liu, Fengjing; Zheng, Guolu

    2014-09-15

    This study is to tackle the challenge posed by the "naturalized" Escherichia coli population against the worldwide practice of E. coli-based water quality monitoring. In the literature, the putative glucosyltransferase gene (ycjM) of E. coli has been identified in silico to be one of the 114 genes specific to enteric E. coli. Based on the sequence of E. coli K-12 MG1655, a PCR assay (ycjPCR) targeting ycjM was developed in this study. As demonstrated by the ycjPCR assay using 367 E. coli strains isolated from animal feces, 97.2% of the isolates carried the ycjM with variations from 93.9% to 100% among nine different host sources, but none of the 17 strains of non-E. coli bacteria and only 23.0% of the environment-isolated cryptic Escherichia strains contained the ycjM. These data experimentally confirmed ycjM to be enteric specific. Our study also showed that the ycjPCR assay was superior to the commonly used tuf- or uidA-based PCR methods in differentiating enteric E. coli from ß-D-glucuronidase-positive environmental bacteria. Furthermore, study on 190 E. coli isolates from water samples, using EPA Method 1603 followed by bacterial identification with Biolog MicroStation™ and ycjPCR assay, indicated that the prevalence of ycjM in the E. coli water isolates had a significant (p < 0.05, odds ratio ) spatial variation from 69.6% to 93.8%. These data suggest that E. coli profile using EPA Method 1603 or other ß-D-glucuronidase-activity-based methods may need further analysis using the ycjM profile to accurately determinate fecal pollution in water. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Tellurite-mediated thiol oxidation in Escherichia coli.

    Science.gov (United States)

    Turner, R J; Weiner, J H; Taylor, D E

    1999-09-01

    The oxyanion of tellurium, tellurite (TeO3(2-)), is toxic to most micro-organisms, particularly gram-negative bacteria. The mechanism of tellurite toxicity is presently unknown. Many heavy metals and oxyanions, including tellurite, interact with reduced thiols (RSH). To determine if tellurite interaction with RSH groups is involved in the toxicity mechanism, the RSH content of Escherichia coli cultures was assayed. After exposure to tellurite, cells were harvested and lysed in the presence of the RSH-specific reagent 5,5'-dithiobis(2-nitrobenzoic acid). Upon exposure of tellurite-susceptible cells to TeO3(2-), the RSH content decreased markedly. Resistance to potassium tellurite (Te(r)) in gram-negative bacteria is encoded by plasmids of incompatibility groups IncFI, IncP alpha, IncHI2, IncHI3 and IncHII, as well as the tehAtehB operon from the E. coli chromosome. When cells harbouring a Te(r) determinant were exposed to TeO3(2-), only a small fraction of the RSH content became oxidized. In addition to tellurite-dependent thiol oxidation, the resistance of E. coli mutants affected in proteins involved in disulfide-bond formation (dsb) was investigated. Mutant strains of dsbA and dsbB were found to be hypersensitive to tellurite (MIC 0.008-0.015 microg K2TeO3 ml(-1) compared to wild-type E. coli with MICs of 1-2 microg K2TeO3 ml(-1)). In contrast, dsbC and dsbD mutants showed no hypersensitivity. The results suggest that hypersensitivity to tellurite is reliant on the presence of an isomerase activity and not the thiol oxidase activity of the Dsb proteins. The results establish that the Te(r) determinants play an important role in maintaining homeostasis of the intracellular reducing environment within gram-negative cells through specific reactions with either TeO3(2-) or thiol:tellurium products.

  2. Uji Antibakteri Ekstak Daun Sirsak (Annonamuricata Linn) terhadap Bakteri Escherichia coli dan Staphylococcusaureus

    OpenAIRE

    Pradikta, Rina

    2015-01-01

    Antibacterial activity of methanol extract soursop leaf (Annona muricata Linn) toEscherichia coli, and Staphylococcus aureus with diffusionmethod has been done. Result showed soursop leaf methanol extract (Annona muricata Linn) has activity as antibacterial. at concentration of 10 % to Escherichia coli and Staphylococcus aureus with resistancediameter of 10 mm to Escherichia coli, and 8,52 mm to Staphylococcus aureus each. While in the water solvent resistent diameter for bacteria Escherichia...

  3. Stimulation of Escherichia coli F-18Col- Type-1 fimbriae synthesis by leuX

    DEFF Research Database (Denmark)

    Newman, Joseph V.; Burghoff, Robert L.; Pallesen, Lars

    1994-01-01

    Escherichia coli F-18, a normal human fecal isolate, is an excellent colonizer of the streptomycin-treated mouse large intestine. E. coli F-18Col-, a derivative of E. coli F-18 which no longer makes the E. coli F-18 colicin, colonizes the large intestine as well as E. coli F-18 when fed to mice...... alone but is eliminated when fed together with E. coli F-18. Recently we randomly cloned E. coli F-18 DNA into E. coli F-18Col- and let the mouse intestine select the best colonizer. In this way, we isolated a 6.5-kb E. coli F-18 DNA sequence that simultaneously stimulated synthesis of type 1 fimbriae...... and enhanced E. coli F-18Col- colonizing ability. In the present investigation we show that the gene responsible for stimulation of type 1 fimbriae synthesis appears to be leuX, which encodes a tRNA specific for the rare leucine codon UUG. Moreover, it appears that expression of leuX may be regulated by two...

  4. Enterohemorrhagic Escherichia coli O157 in Libya

    African Journals Online (AJOL)

    zation of diarrheagenic E. coli from diarrheic Libyan children, clearly stated that EHEC was not detected in the stool specimens examined. However, a study from Tunisia examined 212 stool samples from diarrheic and non-diarrheic children and adults for EHEC using PCR-based techniques (2). They observed 11 isolates ...

  5. Genetic characterization of commensal Escherichia coli isolated from laboratory rodents.

    Science.gov (United States)

    Loong, Shih Keng; Mahfodz, Nur Hidayana; Che Mat Seri, Nurul Asma Anati; Mohamad Wali, Haryanti Azura; Abd Gani, Syahar Amir; Wong, Pooi-Fong; AbuBakar, Sazaly

    2016-01-01

    Escherichia coli, a commensal in the intestines of vertebrates, is capable of colonizing many different hosts and the environment. Commensal E. coli strains are believed to be the precursor of pathogenic strains by means of acquisition of antimicrobial resistant and virulence genes. Laboratory rodents are inherently susceptible to numerous known infectious agents, which could transfer virulence determinants to commensal E. coli. Hence, in this study, the genetic structure of commensal E. coli found in laboratory rodents and their antimicrobial resistance profiles were investigated. E. coli strains belonging to phylogroup A were the predominant strain obtained from the animals used in the study. Four novel sequence types (ST746, ST747, ST748 and ST749) were discovered using the multi locus sequence typing, together with one common ST357 in the gastrointestinal tract, liver and, the trachea and lung. Serotyping demonstrated that these commensal E. coli strains were non-Shiga toxin-producers. Phenotypic and genotypic analyses of extended spectrum beta lactamases were also negative. These findings implied that the E. coli strains recovered from the laboratory rodents were truly commensal in nature. Further study is required to investigate the possible influence of gender on the susceptibility of hosts to E. coli colonization in laboratory rodents.

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

    Science.gov (United States)

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

    2017-01-01

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

  7. A cheap, simple high throughput method for screening native Helicobacter pylori urease inhibitors using a recombinant Escherichia coli, its validation and demonstration of Pistacia atlantica methanolic extract effectivity and specificity.

    Science.gov (United States)

    Amar, Natalie; Peretz, Avi; Gerchman, Yoram

    2017-02-01

    Helicobacter pylori is the most frequent and persistent bacterial infection worldwide, and a risk factor for active gastritis, peptic ulcers, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. Although combined antibiotics treatment is effective cases of antibiotic resistance are reported at an alarming rate. The H. pylori urease enzyme is essential for the bacteria establishment in the gastric mucosa, resulting urease inhibitors being sought after as effective and specific anti- H. pylori treatment. To-date, screening assays are based mostly on the analog plant urease enzyme but difference in properties of the plant and bacterial enzymes hamper these efforts. We have developed a screening assay based on recombinant Escherichia coli expressing native H. pylori urease, and validated this assay using thiourea and a methanolic extract of Pistacia atlantica. The assay demonstrated the thiourea and the extract to be potent urease inhibitors, with the extract having strong bacteriostatic activity against clinical isolates of H. pylori, including such with antibiotic resistance. The extract was also found to be neutral toward common probiotic bacteria, supporting its specificity and compatibility with digestive system desired microflora and suggesting it could be a good source for anti-H. pylori compounds. The assay has proven to be cheap, simple and native alternative to the plant enzyme based assay and could allow for high throughput screening for new urease inhibitors and could expedite screening and development of novel, better H. pylori remedies helping us to combat this infection. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    1997-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Silvia Tagliabue

    2010-01-01

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

  10. Biosynthetic pathway for poly(3-hydroxypropionate) in recombinant Escherichia coli.

    Science.gov (United States)

    Wang, Qi; Liu, Changshui; Xian, Mo; Zhang, Yongguang; Zhao, Guang

    2012-08-01

    Poly(3-hydroxypropionate) (P3HP) is a biodegradable and biocompatible thermoplastic. In this study, we engineered a P3HP biosynthetic pathway in recombinant Escherichia coli. The genes for malonyl-CoA reductase (mcr, from Chloroflexus aurantiacus), propionyl-CoA synthetase (prpE, from E. coli), and polyhydroxyalkanoate synthase (phaC1, from Ralstonia eutropha) were cloned and expressed in E. coli. The E. coli genes accABCD encoding acetyl-CoA carboxylase were used to channel the carbon into the P3HP pathway. Using glucose as a sole carbon source, the cell yield and P3HP content were 1.32 g/L and 0.98% (wt/wt [cell dry weight]), respectively. Although the yield is relatively low, our study shows the feasibility of engineering a P3HP biosynthetic pathway using a structurally unrelated carbon source in bacteria.

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

    Science.gov (United States)

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

    2015-09-01

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

  12. Detection of diarrheagenic Escherichia coli from children with and without diarrhea in Salvador, Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Vanessa Bueris

    2007-11-01

    Full Text Available We identified different diarrheagenic (DEC Escherichia coli pathotypes isolated from 1,207 children with and without acute endemic diarrhea in Salvador, Bahia, Brazil collected as part of a case-control study. Since the identification of DEC cannot be based on only biochemical and culture criteria, we used a multiplex polymerase chain reaction developed by combining five specific primer pairs for Enteropathogenic Escherichia coli (EPEC, Shiga toxin-producing E. coli/ Enterohaemorrhagic E. coli (STEC/EHEC, Enterotoxigenic E. coli (ETEC and Enteroaggregative E. coli (EAEC to detect these pathotypes simultaneously in a single-step reaction. In order to distinguish typical and atypical EPEC strains, these were tested for the presence of EAF plasmid. The prevalence of diarrheagenic E. coli in this sample of a global case-control study was 25.4% (259 patients and 18.7% (35 patients in the diarrhea group (1,020 patients and the control group (187 patients, respectively. The most frequently isolated pathotype was EAEC (10.7%, followed by atypical EPEC (9.4%, ETEC (3.7%, and STEC (0.6%. Typical EPEC was detected only in one sample. The prevalence of the pathotypes studied in children with diarrhea was not significantly different from that in children without diarrhea.

  13. Penicillin-binding site on the Escherichia coli cell envelope

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Virulence and Fitness Determinants of Uropathogenic Escherichia coli

    Science.gov (United States)

    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

  15. Escherichia coli expression, refolding and characterization of human laforin.

    Science.gov (United States)

    Castanheira, Pedro; Moreira, Susana; Gama, Miguel; Faro, Carlos

    2010-06-01

    Laforin is a unique human dual-specificity phosphatase as it contains an amino terminal carbohydrate binding module (CBM). Laforin gene mutations lead to Lafora disease, a progressive myoclonus epilepsy with an early fatal issue. Previous attempts to produce recombinant laforin faced various difficulties, namely the appearance of protein inclusion bodies, the contamination with bacterial proteins and a high tendency of the protein to aggregate, despite the use of fusion tags to improve solubility and ease the purification process. In this work, we have expressed human laforin in Escherichia coli in the form of inclusion bodies devoid of any fusion tags. After a rapid dilution refolding step, the protein was purified by two chromatographic steps, yielding 5-7mg of purified protein per liter of bacterial culture. The purified protein was shown to have the kinetic characteristics of a dual-specificity phosphatase, and a functional carbohydrate binding module. With this protocol, we were able for the first time, to produce and purify laforin without fusion tags in the amounts traditionally needed for the crystallographic structural studies paving the way to the understanding of the molecular mechanisms of laforin activity and to the development of novel therapies for Lafora disease.

  16. Resistance and virulence factors of Escherichia coli isolated from chicken.

    Science.gov (United States)

    Pavlickova, Silvie; Dolezalova, Magda; Holko, Ivan

    2015-01-01

    Chicken meat has become an important part of the human diet and besides contamination by pathogenic Escherichia coli there is a risk of antibiotic resistance spreading via the food chain. The purpose of this study was to examine the prevalence of resistance against eight antibiotics and the presence of 14 virulence factors among 75 Escherichia coli strains isolated from chicken meat in the Czech Republic after classification into phylogenetic groups by the multiplex PCR method. More than half of strains belonged to A phylogroup, next frequently represented was B1 phylogroup, which suggests the commensal strains. The other strains were classified into phylogroups B2 and D, which had more virulence factors. Almost half of all E. coli strains were resistant to at least one of eight-tested antibiotics. A multidrug resistance was observed in 13% of strains. The most prevalent virulence genes were iucD, iss and tsh. None of genes encoding toxins was detected. Most of E. coli strains isolated from chicken meat can be considered as nonpathogenic on the basis of analysis of virulence factors, antibiotic resistance and phylogroups assignment. It can provide a useful tool for prediction of a potential risk from food contaminated by E. coli.

  17. Novel Aggregative Adherence Fimbria Variant of Enteroaggregative Escherichia coli

    DEFF Research Database (Denmark)

    Jønsson, Rie; Struve, Carsten; Boisen, Nadia

    2015-01-01

    Enteroaggregative Escherichia coli (EAEC) organisms belong to a diarrheagenic pathotype known to cause diarrhea and can be characterized by distinct aggregative adherence (AA) in a stacked-brick pattern to cultured epithelial cells. In this study, we investigated 118 EAEC strains isolated from....... Transformation to a nonadherent E. coli HB101 and complementation of the nonadherent C338-14 mutant with the complete gene cluster restored the AA adhesion. Overall, we found the agg5A gene in 12% of the 118 strains isolated from Denmark, suggesting that this novel adhesin represents an important variant....

  18. FimH-mediated autoaggregation of Escherichia coli

    DEFF Research Database (Denmark)

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

    2001-01-01

    Autoaggregation is a phenomenon thought to contribute to colonization of mammalian hosts by pathogenic bacteria. Type 1 fimbriae are surface organelles of Escherichia coli that mediate D-mannose-sensitive binding to various host surfaces. This binding is conferred by the minor fimbrial component...... FimH. In this study, we have used random mutagenesis to identify variants of the FimH adhesin that confer the ability of E. coli to autoaggregate and settle from liquid cultures. Three separate autoaggregating clones were identified, all of which contained multiple amino acid changes located within...

  19. Gentamicin resistance among Escherichia coli strains isolated in neonatal sepsis.

    Science.gov (United States)

    Hasvold, J; Bradford, L; Nelson, C; Harrison, C; Attar, M; Stillwell, T

    2013-01-01

    Neonatal sepsis is a significant cause of morbidity and mortality among term and preterm infants. Ampicillin and gentamicin are standard empiric therapy for early onset sepsis. Four cases of neonatal sepsis secondary to Escherichia coli (E. coli) found to be gentamicin resistant occurred within a five week period in one neonatal intensive care unit (NICU). To determine whether these cases could be tied to a single vector of transmission, and to more broadly evaluate the incidence of gentamicin resistant strains of E. coli in the neonatal population at our institution compared to other centers, we reviewed the charts of the four neonates (Infants A through D) and their mothers. The E. coli isolates were sent for Pulse Field Gel Electrophoresis (PFGE) to evaluate for genetic similarity between strains. We also reviewed all positive E. coli cultures from one NICU over a two year period. Infants A and B had genetically indistinguishable strains which matched that of urine and placental cultures of Infant B's mother. Infant C had a genetically distinct organism. Infant D, the identical twin of Infant C, did not have typing performed. Review of all cultures positive for E. coli at our institution showed a 12.9 percent incidence of gentamicin-resistance. A review of other studies showed that rates of resistance vary considerably by institution. We conclude that gentamicin-resistant E. coli is a relatively uncommon cause of neonatal sepsis, but should remain a consideration in patients who deteriorate despite initiation of empiric antibiotics.

  20. NleB/SseK effectors from Citrobacter rodentium, Escherichia coli, and Salmonella enterica display distinct differences in host substrate specificity

    DEFF Research Database (Denmark)

    El Qaidi, Samir; Chen, Kangming; Halim, Adnan

    2017-01-01

    proteins with N-acetyl-D-glucosamine to inhibit antibacterial and inflammatory host responses. NleB is conserved among the attaching/effacing pathogens enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), and Citrobacter rodentium. Moreover, Salmonella enterica strains encode up to three Nle...... of these effectors. SseK1, SseK3, EHEC NleB1, EPEC NleB1, and C. rodentium NleB blocked TNF-mediated NF-κB pathway activation, whereas SseK2 and NleB2 did not. C. rodentium NleB, EHEC NleB1, and SseK1 glycosylated host glyceraldehyde 3-phosphate dehydrogenase (GAPDH). C. rodentium NleB, EHEC NleB1, EPEC NleB1......, and SseK2 glycosylated the Fas-associated death domain protein (FADD). SseK3 and NleB2 were not active against either substrate. We also found that EHEC NleB1 glycosylated two GAPDH arginine residues, R197 and R200 and that these two residues were essential for GAPDH-mediated activation of tumor necrosis...

  1. Molecular genotyping of Escherichia coli O-serogroups

    Science.gov (United States)

    O-antigens present on the surface of E. coli, provide antigenic specificity for the strain and are the main components for O-serogroup designation. Serotyping using O-group-specific antisera for the identification of E. coli O-serogroups has been traditionally the gold-standard for distinguishing E...

  2. TRYPTOPHANASE-TRYPTOPHAN SYNTHETASE SYSTEMS IN ESCHERICHIA COLI III.

    Science.gov (United States)

    Freundlich, Martin; Lichstein, Herman C.

    1962-01-01

    Freundlich, Martin (University of Minnesota, Minneapolis) and Herman C. Lichstein. Tryptophanase-tryptophan synthetase systems in Escherichia coli. III. Requirements for enzyme synthesis. J. Bacteriol. 84:996–1006. 1962.—The requirements for the formation of tryptophanase and tryptophan synthetase in Escherichia coli during repression release were studied. The kinetics of the formation of tryptophan synthetase differed in the two strains examined; this was attributed to differences in the endogenous level of tryptophan in the bacterial cells. The formation of both enzymes was inhibited by chloramphenicol, and by the absence of arginine in an arginine-requiring mutant. These results are indicative of a requirement for protein synthesis for enzyme formation. Requirements for nucleic acid synthesis were examined by use of a uracil- and thymine-requiring mutant, and with purine and pyrimidine analogues. The results obtained suggest that some type of ribonucleic acid synthesis was necessary for the formation of tryptophanase and tryptophan synthetase. PMID:13959620

  3. Tranformasi Fragmen Dna Kromosom Xanthomonas Campestris ke dalam Escherichia Coli

    Directory of Open Access Journals (Sweden)

    Wibowo Mangunwardoyo

    2002-04-01

    Full Text Available Research on DNA transformation of Xanthomonas campestris into Escherichia coli DH5αα using plasmid vector Escherichia coli (pUC19. was carried out. DNA chromosome was isolated using CTAB method, alkali lysis method was used to isolate DNA plasmid. Both of DNA plasmid and chromosome were digested using restriction enzyme EcoRI. Competent cell was prepared with CaCl2 and heat shock method for transformation procedure. The result revealed transformation obtain 5 white colonies, with transformation frequency was 1,22 x 10-8 colony/competent cell. Electrophoresis analysis showed the DNA fragment (insert in range 0.5 – 7,5 kb. Further research should be carried out to prepare the genomic library to obtain better result of transformant.

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

    Directory of Open Access Journals (Sweden)

    Yue-Dong Gao

    2014-01-01

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

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

    Science.gov (United States)

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

    2017-09-01

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

  6. Studies of the Escherichia coli Rsd-sigma70 complex.

    Science.gov (United States)

    Westblade, Lars F; Ilag, Leopold L; Powell, Andrew K; Kolb, Annie; Robinson, Carol V; Busby, Stephen J W

    2004-01-16

    Escherichia coli Rsd protein was previously identified on the basis of its binding to the RNA polymerase sigma(70) subunit. The Rsd-sigma(70) complex has been studied using different methods. Our data show that Rsd associates with sigma(70) to form a complex with a stoichiometry of 1:1. Alanine scanning and deletion mutagenesis were used to locate regions of sigma(70) that are required for the formation of the Rsd-sigma(70) complex.

  7. Sequence elements in the Escherichia coli araFGH promoter.

    OpenAIRE

    Hendrickson, W; Flaherty, C.; Molz, L

    1992-01-01

    The Escherichia coli araFGH operon codes for proteins involved in the L-arabinose high-affinity transport system. Transcriptional regulation of the operon was studied by creating point mutations and deletions in the control region cloned into a GalK expression vector. The transcription start site was confirmed by RNA sequencing of transcripts. The sequences essential for polymerase function were localized by deletions and point mutations. Surprisingly, only a weak -10 consensus sequence, and ...

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

    African Journals Online (AJOL)

    Ann Lab Med 2014; 34(2): 139-144. 24. Fuentes Arriaga R, Talavera Rojas M, Vázquez. Navarrete J, Soriano Vargas E, Gutiérrez Castillo A. Presencia de integrones clase I en Escherichia coli aislada de productos cárnicos en plantas Tipo. Inspección Federal (TIF) en el Estado de México. Vet. Mexico 2013; 44(1): 23-30.

  9. Spurious hydrogen sulfide production by Providencia and Escherichia coli species.

    OpenAIRE

    Treleaven, B E; Diallo, A A; Renshaw, E C

    1980-01-01

    Hydrogen sulfide production was noted in two Escherichia coli strands and one Provaidenica alcalifaciens (Proteus inconstans A) strain isolated from clinical stool specimens durin the summer of 1979. An investigation into this phenomenon revealed the predence of Eubacterium lentum, an anaerobe, growing in synergism with the Enterobacteriaceae and producing H2s. The implications of this association are discssed with reference to clinical microbiology laboratory practice.

  10. Two Tales of Prokaryotic Genomic Diversity: Escherichia coli and Halophiles

    Directory of Open Access Journals (Sweden)

    Lejla Pašić

    2014-01-01

    Full Text Available Prokaryotes are generally characterized by vast genomic diversity that has been shaped by mutations, horizontal gene transfer, bacteriocins and phage predation. Enormous genetic diversity has developed as a result of stresses imposed in harsh environments and the ability of microorganisms to adapt. Two examples of prokaryotic diversity are presented: on intraspecies level, exemplified by Escherichia coli, and the diversity of the hypersaline environment, with the discussion of food-related health issues and biotechnological potential.

  11. Removal of Escherichia coli from biological effluents using natural ...

    African Journals Online (AJOL)

    Ability for disinfecting sterile biological effluents inoculated with Escherichia coli ATCC 25922 at concentrations of 105 CFU/m., using a natural mineral aggregate (NMA) and artificial mineral aggregates (AMAfs) consisting of individual oxides as Fe2O3, Cu2O y Ag2O and combined oxides as Fe2O3-Cu2O, Fe2O3-Ag2O, ...

  12. flu, a metastable gene controlling surface properties of Escherichia coli.

    OpenAIRE

    Diderichsen, B

    1980-01-01

    flu, a gene of Escherichia coli K-12, was discovered and mapped between his and shiA. It is shown that flu is a metastable gene that changes frequently between the flu+ and flu states. flu+ variants give stable homogeneous suspensions, are piliated, and form glossy colonies. flu variants aggregate, fluff and sediment from suspensions, are nonpiliated, and form frizzy colonies. flu+ and flu variants can be isolated from most strains. Implications of these observations are discussed, and it is ...

  13. The effect of spatial structure on adaptation in Escherichia coli

    OpenAIRE

    Perfeito, Lilia; Pereira, M. Inês; Campos, Paulo R. A.; Gordo, Isabel

    2007-01-01

    Populations of organisms are generally organized in a given spatial structure. However, the vast majority of population genetic studies are based on populations in which every individual competes globally. Here we use experimental evolution in Escherichia coli to directly test a recently made prediction that spatial structure slows down adaptation and that this cost increases with the mutation rate. This was studied by comparing populations of different mutation rates adapting to a liquid (un...

  14. Aging in Escherichia coli: stochasticity, individual heterogeneity and mortality plateaus

    DEFF Research Database (Denmark)

    Steiner, Uli

    2014-01-01

    are suggested to be involved in aging and senescence, but no mechanism or factor has been unambiguously identified. Here, we report on surprising patterns of aging and senescence from isogenic individual Escherichia coli bacteria grown under identical environmental conditions in a microfluidic device....... Such simple organisms are expected to show senescence because of asymmetric division of accumulated damage among mother and daughter cells, accumulation of late acting deleterious mutations, or antagonistic pleiotropic effects....

  15. Identification and Functional Analysis of Escherichia coli Cysteine Desulfhydrases

    OpenAIRE

    Awano, Naoki; WADA, Masaru; Mori, Hirotada; Nakamori, Shigeru; Takagi, Hiroshi

    2005-01-01

    In Escherichia coli, three additional proteins having l-cysteine desulfhydrase activity were identified as O-acetylserine sulfhydrylase-A, O-acetylserine sulfhydrylase-B, and MalY protein, in addition to tryptophanase and cystathionine β-lyase, which have been reported previously. The gene disruption for each protein was significantly effective for overproduction of l-cysteine and l-cystine. Growth phenotype and transcriptional analyses suggest that tryptophanase contributes primarily to l-cy...

  16. Uji Aktivitas Antibakteri Ekstrak Herbal Terhadap Bakteri Escherichia Coli

    OpenAIRE

    Rahmawati, Nurina; Sudjarwo, Edhy; Widodo, Eko

    2014-01-01

    Several herbs have been evaluated as feed additive for chicken, namely tumeric, white tumeric, javanese ginger and black ginger. The purpose of the research was to examine antibacterial activity (inhibition diameter zone and minimum inhibition concentration test) on several herbs extract toward Escherichia coli. In the experiment, there were 6 treatments namely aquadest 100% (A0), antibiotic tetracycline (A1), tumeric extract (A2), white tumeric extract (A3), javanese ginger extract (A4) and ...

  17. Simple, rapid, and reliable detection of Escherichia coli O26 using immunochromatography.

    Science.gov (United States)

    Yonekita, Taro; Fujimura, Tatsuya; Morishita, Naoki; Matsumoto, Takashi; Morimatsu, Fumiki

    2013-05-01

    Shiga toxin-producing Escherichia coli (STEC) O26 has been increasingly associated with diarrheal disease all over the world. We developed an immunochromatographic (ic) strip for the rapid detection of E. coli O26 in food samples. To determine the specificity of the IC strip, pure cultures of 67 E. coli and 22 non-E. coli strains were tested with the IC strip. The IC strip could detect all (18 of 18) E. coli O26 strains tested and did not react with strains of any other E. coli serogroup or non-E. coli strains tested (0 of 71). The minimum detection limits for E. coli O26 were 2.2 × 10(3) to 1.0 × 10(5) cfu/ml. To evaluate the ability of the IC strip to detect E. coli O26 in food, 25-g food samples (ground beef, beef liver, ground chicken, alfalfa sprout, radish sprout, spinach, natural cheese, and apple juice) were spiked with E. coli O26. The IC strip was able to detect E. coli O26 at very low levels (approximately 1 cfu/25 g of food samples) after an 18-h enrichment, and the IC strip results were in 100% agreement with the results of the culture method and pcr assay. When 115 meat samples purchased from supermarkets were tested, 5 were positive for E. coli O26 with the IC strip; these results were confirmed with a pcr assay. These results suggest that the IC strip is a useful tool for detecting E. coli O26 in food samples.

  18. PROFILE OF RESISTANCE OF Escherichia coli ISOLATED FROM CANINE PYOMETRA

    Directory of Open Access Journals (Sweden)

    Fernanda Santana Oliveira

    2016-10-01

    Full Text Available The endothelial pyometra is a disease that affects more frequently reproductively active adult females. Characterized by inflammation and accumulation of exudate in the uterine cavity, generally associated with bacterial infections. The present study aimed to evaluate the resistance profile of Escherichia coli isolates from 42 female dogs diagnosed with pyometra, seen at the Department of Small Animal Surgery, Hospital of Veterinary Medicine, Federal University of Bahia. To perform the bacteriological analysis, a sample of the contents of the uterus was obtained immediately after surgery of ovariosalpingohisterectomy therapy (OSH and sent to the laboratory. Microbiological analysis showed a predominance of the bacterium Escherichia coli in 40.5% (15/37. Strains of Escherichia coli isolates showed higher rates of resistance to antimicrobial erythromycin (93.3 %, azithromycin (80 %, ampicillin, amoxicillin, and cephalothin (40% each. This study reinforces the need to perform the microbiological examination for epidemiological purposes and the correct therapeutic application, thereby avoiding the indiscriminate use of antimicrobials and the potential emergence of multidrug-resistant  strains. Keywords: bacteria; multiresistant;  uterus.

  19. [Integration and expression of sdh gene in Escherichia coli].

    Science.gov (United States)

    Gao, Shu-ying; Zhang, Wei-cai; Wang, Jian-hua; Guo, Ai-guang

    2005-02-01

    The chloramphenicol-resistant cassette with short shared sequences of ptsG gene on both ends was PCR-generated from plasmid pKF3 and ligated to pMD18-T to construct pMD18-PC. The sdh gene for sorbose dehydrogenase was generated from plasmid pQE60-SDH and inserted into pMD18-PC, then pMD18-PC-SDH was constructed. It was digested with Pvu II and the target fragment ptsG1-cat-sdh-ptsG2 was recovered and electroporated into Escherichia coli JM109/pKD46. Homologous-recombination between linear DNA cassettes and Escherichia coli chromosomes took place by Red recombination. The detection result showed that the integron JM109s was of sorbose dehydrogenase activity. The PCR products assay using the upstream and downstream sequences of ptsG gene as primers and JM109s genomic DNA as template, indicated that sdh gene had been integrated at the ptsG gene site in Escherichia coli.

  20. Occurrence of toxigenic Escherichia coli in raw milk cheese in Brazil Ocorrência de Escherichia coli toxigênica em queijo-de-minas frescal no Brasil

    OpenAIRE

    Paneto, B.R. [UNESP; Schocken-Iturrino, R.P.; Macedo,C.; Santo, E.; J.M. Marin

    2007-01-01

    The occurrence of toxigenic Escherichia coli in raw milk cheese was surveyed in Middle Western Brazil. Fifty samples of cheese from different supermarkets were analyzed for E.coli. The isolates were serotyped and screened for the presence of verotoxigenic E. coli (VTEC) and enterotoxigenic E. coli (ETEC) by Polymerase Chain Reaction (PCR). The susceptibility to thirteen antimicrobial agents was evaluated by the disk diffusion method. E.coli were recovered from 48 (96.0%) of the samples. The s...

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  2. Ferritinophagy drives uropathogenic Escherichia coli persistence in bladder epithelial cells.

    Science.gov (United States)

    Bauckman, Kyle A; Mysorekar, Indira U

    2016-05-03

    Autophagy is a cellular recycling pathway, which in many cases, protects host cells from infections by degrading pathogens. However, uropathogenic Escherichia coli (UPEC), the predominant cause of urinary tract infections (UTIs), persist within the urinary tract epithelium (urothelium) by forming reservoirs within autophagosomes. Iron is a critical nutrient for both host and pathogen, and regulation of iron availability is a key host defense against pathogens. Iron homeostasis depends on the shuttling of iron-bound ferritin to the lysosome for recycling, a process termed ferritinophagy (a form of selective autophagy). Here, we demonstrate for the first time that UPEC shuttles with ferritin-bound iron into the autophagosomal and lysosomal compartments within the urothelium. Iron overload in urothelial cells induces ferritinophagy in an NCOA4-dependent manner causing increased iron availability for UPEC, triggering bacterial overproliferation and host cell death. Addition of even moderate levels of iron is sufficient to increase and prolong bacterial burden. Furthermore, we show that lysosomal damage due to iron overload is the specific mechanism causing host cell death. Significantly, we demonstrate that host cell death and bacterial burden can be reversed by inhibition of autophagy or inhibition of iron-regulatory proteins, or chelation of iron. Together, our findings suggest that UPEC persist in host cells by taking advantage of ferritinophagy. Thus, modulation of iron levels in the bladder may provide a therapeutic avenue to controlling UPEC persistence, epithelial cell death, and recurrent UTIs.

  3. Metabolic engineering of anthocyanin biosynthesis in Escherichia coli.

    Science.gov (United States)

    Yan, Yajun; Chemler, Joseph; Huang, Lixuan; Martens, Stefan; Koffas, Mattheos A G

    2005-07-01

    Anthocyanins are red, purple, or blue plant pigments that belong to the family of polyphenolic compounds collectively called flavonoids. Their demonstrated antioxidant properties and economic importance to the dye, fruit, and cut-flower industries have driven intensive research into their metabolic biosynthetic pathways. In order to produce stable, glycosylated anthocyanins from colorless flavanones such as naringenin and eriodictyol, a four-step metabolic pathway was constructed that contained plant genes from heterologous origins: flavanone 3beta-hydroxylase from Malus domestica, dihydroflavonol 4-reductase from Anthurium andraeanum, anthocyanidin synthase (ANS) also from M. domestica, and UDP-glucose:flavonoid 3-O-glucosyltransferase from Petunia hybrida. Using two rounds of PCR, each one of the four genes was first placed under the control of the trc promoter and its own bacterial ribosome-binding site and then cloned sequentially into vector pK184. Escherichia coli cells containing the recombinant plant pathway were able to take up either naringenin or eriodictyol and convert it to the corresponding glycosylated anthocyanin, pelargonidin 3-O-glucoside or cyanidin 3-O-glucoside. The produced anthocyanins were present at low concentrations, while most of the metabolites detected corresponded to their dihydroflavonol precursors, as well as the corresponding flavonols. The presence of side product flavonols is at least partly due to an alternate reaction catalyzed by ANS. This is the first time plant-specific anthocyanins have been produced from a microorganism and opens up the possibility of further production improvement by protein and pathway engineering.

  4. Ensemble modeling for aromatic production in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Matthew L Rizk

    2009-09-01

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

  5. Vanillin production by recombinant strains of Escherichia coli Produção de vanilina por linhagens recombinantes de Escherichia coli

    Directory of Open Access Journals (Sweden)

    Attilio Converti

    2003-11-01

    Full Text Available Vanillin production from ferulate was studied using different recombinant strains of Escherichia coli. To prevent the occurrence of aerobic conditions and then possible product oxidation, tests were performed in Erlenmeyer flasks under mild mixing (150 rpm. Among other transformants, E. coli JM109(pBB1 appeared to be the best vanillin producer, being able to convert no less than 95% of starting ferulate to the product within 1h. This yield decreased down to 72% after 72h, likely because of a non-specific oxidase activity responsible for vanillin oxidation to vanillate.A produção de vanilina a partir de ácido ferúlico foi estudada utilizando-se diferentes linhagens recombinantes de Escherichia coli. Para prevenir a ocorrência de condições de aerobiose e a possível oxidação do produto, os ensaios foram realizados em frascos Erlenmeyer sob agitação moderada (150 rpm. E. coli JM109 (pBBI mostrou-se o melhor produtor de vanilina entre os demais agentes transformantes, sendo capaz de converter 95% do ácido ferúlico inicial em produto após 1h, rendimento este que decresceu para 72% após 72h, provavelmente devido à atividade de uma oxidase não-específica responsável pela oxidação de vanilina a ácido vanílico.

  6. Ecological and genetic determinants of plasmid distribution in Escherichia coli.

    Science.gov (United States)

    Medaney, Frances; Ellis, Richard J; Raymond, Ben

    2016-11-01

    Bacterial plasmids are important carriers of virulence and antibiotic resistance genes. Nevertheless, little is known of the determinants of plasmid distribution in bacterial populations. Here the factors affecting the diversity and distribution of the large plasmids of Escherichia coli were explored in cattle grazing on semi-natural grassland, a set of populations with low frequencies of antibiotic resistance genes. Critically, the population genetic structure of bacterial hosts was chararacterized. This revealed structured E. coli populations with high diversity between sites and individuals but low diversity within cattle hosts. Plasmid profiles, however, varied considerably within the same E. coli genotype. Both ecological and genetic factors affected plasmid distribution: plasmid profiles were affected by site, E. coli diversity, E. coli genotype and the presence of other large plasmids. Notably 3/26 E. coli serotypes accounted for half the observed plasmid-free isolates indicating that within species variation can substantially affect carriage of the major conjugative plasmids. The observed population structure suggest that most of the opportunities for within species plasmid transfer occur between different individuals of the same genotype and support recent experimental work indicating that plasmid-host coevolution, and epistatic interactions on fitness costs are likely to be important in determining occupancy. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  7. Transformation of Escherichia coli and protein expression using lipoplex mimicry.

    Science.gov (United States)

    Yun, Chul-Ho; Bae, Chun-Sik; Ahn, Taeho

    2016-11-01

    We investigated a "one-step" method for transformation of and protein expression in Escherichia coli (E. coli) using a complex of n-stearylamine, a cationic lipid, and plasmid DNA, which mimics lipoplex-based approaches. When E. coli cells were treated with the cationic lipid-plasmid complex, the transformation efficiencies were in the range of approximately 2-3 × 10(6) colony-forming units. Further increase in the efficiency was obtained by co-treatment with calcium chloride (or rubidium chloride) and the complexes. Moreover, after DNA transfer, E. coli cells successfully expressed plasmid-encoded proteins such as cytochrome P450s and glutathione-S-transferase without overnight incubation of the cells to form colonies, an indispensable step in other bacterial transformation methods. In this study, we provide a simple method for E. coli transformation, which does not require the preparation of competent cells. The present method also shortens the overall procedures for transformation and gene expression in E. coli by omitting the colony-forming step. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Production of 3-O-xylosyl quercetin in Escherichia coli

    DEFF Research Database (Denmark)

    Pandey, Ramesh Prasad; Malla, Sailesh; Simkhada, Dinesh

    2013-01-01

    Quercetin, a flavonol aglycone, is one of the most abundant flavonoids with high medicinal value. The bioavailability and pharmacokinetic properties of quercetin are influenced by the type of sugars attached to the molecule. To efficiently diversify the therapeutic uses of quercetin, Escherichia...... coli was harnessed as a production factory by the installation of various plant and bacterial UDP-xylose sugar biosynthetic genes. The genes encoding for the UDP-xylose pathway enzymes phosphoglucomutase (nfa44530), glucose-1-phosphate uridylyltransferase (galU), UDP-glucose dehydrogenase (calS8......), and UDP-glucuronic acid decarboxylase (calS9) were overexpressed in E. coli BL21 (DE3) along with a glycosyltransferase (arGt-3) from Arabidopsis thaliana. Furthermore, E. coli BL21(DE3)/∆pgi, E. coli BL21(DE3)/∆zwf, E. coli BL21(DE3)/∆pgi∆zwf, and E. coli BL21(DE3)/∆pgi∆zwf∆ushA mutants carrying...

  9. Bactericidal activity of ciprofloxacin upon Escherichia coli and Acinetobacter baumanni.

    Science.gov (United States)

    Zemelman, R; Vejar, C; Bello, H; Domínguez, M; González, G

    1992-01-01

    The mechanisms of bactericidal activity of ciprofloxacin (mechanisms A and B) upon cells of a strain of Escherichia coli and one strain of Acinetobacter baumannii were investigated under different conditions. The killing of E. coli cells by ciprofloxacin was significantly reduced by chloramphenicol, but this antibiotic showed almost no activity upon killing of A. baumannii cells by this quinolone. Similar results were obtained when rifampicin was added to ciprofloxacin. Bactericidal activity of ciprofloxacin upon nondividing cells of E. coli was lower and that upon non-dividing cells of A. baumannii was not affected when compared with activity of ciprofloxacin upon dividing cells of both microorganisms. These results demonstrate that the antibacterial activity of ciprofloxacin upon A. baumannii is independent of protein and ARN synthesis, a fact which suggests that this quinolone exerts only bactericidal mechanism B upon A. baumannii. This finding might explain, at least in part, the lower susceptibility of this microorganism to ciprofloxacin.

  10. The Escherichia coli transcriptome linked to growth fitness

    Directory of Open Access Journals (Sweden)

    Bei-Wen Ying

    2016-03-01

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

  11. A stochastic killing system for biological containment of Escherichia coli

    DEFF Research Database (Denmark)

    Klemm, P.; Jensen, Lars Bogø; Molin, Søren

    1995-01-01

    Bacteria with a stochastic conditional lethal containment system have been constructed. The invertible switch promoter located upstream of the fimA gene from Escherichia coli was inserted as expression cassette in front of the Lethal gef gene deleted of its own natural promoter. The resulting...... fusion was placed on a plasmid and transformed to E. coli. The phenotype connected with the presence of such a plasmid was to reduce the population growth rate with increasing significance as the cell growth rate was reduced. In very fast growing cells, there was no measurable effect on growth rate. When...... a culture of E. coli harboring the plasmid comprising the containment system is left as stationary cells in suspension without nutrients, viability drops exponentially over a period of several days, in contrast to the control cells, which maintain viability nearly unaffected during the same period of time...

  12. Reassessing Escherichia coli as a cell factory for biofuel production.

    Science.gov (United States)

    Wang, Chonglong; Pfleger, Brian F; Kim, Seon-Won

    2017-06-01

    Via metabolic engineering, industrial microorganisms have the potential to convert renewable substrates into a wide range of biofuels that can address energy security and environmental challenges associated with current fossil fuels. The user-friendly bacterium, Escherichia coli, remains one of the most frequently used hosts for demonstrating production of biofuel candidates including alcohol-, fatty acid- and terpenoid-based biofuels. In this review, we summarize the metabolic pathways for synthesis of these biofuels and assess enabling technologies that assist in regulating biofuel synthesis pathways and rapidly assembling novel E. coli strains. These advances maintain E. coli's position as a prominent host for developing cell factories for biofuel production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. EcoProDB: the Escherichia coli protein database.

    Science.gov (United States)

    Yun, Hongseok; Lee, Jeong Wook; Jeong, Joonwoo; Chung, Jaesung; Park, Jong Myoung; Myoung, Han Na; Lee, Sang Yup

    2007-09-15

    EcoProDB is a web-based database for comparative proteomics of Escherichia coli. The database contains information on E. coli proteins identified on 2D gels along with other resources collected from various databases and published literature, with a special feature of showing the expression levels of E. coli proteins under different genetic and environmental conditions. It also provides comparative information of subcellular localization, theoretical 2D map, experimental 2D map and integrated protein information via an interactive web interface and application such as the Map Browser. Users can also upload their own 2D gels, extract core information associated with the proteins and 2D gel results from different experiments and consequently generate new knowledge and hypotheses for further studies. EcoProDB database system is accessible at http://eecoli.kaist.ac.kr.

  14. FREQUENCY AND DISTRIBUTION OF DIARRHOEAGENIC ESCHERICHIA COLI STRAINS ISOLATED FROM PEDIATRIC PATIENTS WITH DIARRHOEA IN BOSNIA AND HERZEGOVINA

    OpenAIRE

    Dedeić-Ljubović, AmeLa; Hukić, Mirsada; Bekić, DaRia; Zvizdić, AmrA

    2009-01-01

    Diarrhoeal disease is a major cause of illness and death among infants and young children worldwide. Among the Escherichia coli (E. coli) causing intestinal diseases, there are six well-described categories: enteroaggregative E. coli (EAEC), diffusely adherent E. coli (DAEC), enteroinvasive E. coli (EIEC), entero-pathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC) and enterotoxigenic E. coli (ETEC).

  15. Overproduction in Escherichia coli and purification of Epstein-Barr virus EBNA-1.

    Science.gov (United States)

    Duellman, Sarah J; Burgess, Richard R

    2006-06-01

    Epstein-Barr virus nuclear antigen 1 (EBNA-1) is a multi-functional protein of the Epstein-Barr virus (EBV). Due to its low abundance in EBV-transformed cells, overproduction in a foreign host is preferred to obtain purified EBNA-1 protein. The EBNA-1 gene possesses a large number of Escherichia coli rare codons (23%). By using E. coli BL21(DE3)Rosetta2 cells that augment the low-abundance tRNA genes, the expression level of EBNA-1 in E. coli was greatly enhanced. EBNA-1 was then purified by applying the whole cell extract soluble fraction to a Ni-NTA Superflow column and eluting with an imidazole gradient. The improved overexpression in E. coli followed by a one-step Ni-NTA purification resulted in a sufficient amount of pure EBNA-1 protein to test DNA binding activity, and prepare and test EBNA-1-specific monoclonal antibodies (mAbs).

  16. The Need and New Tools for Surveillance of Escherichia coli Pathogens

    Directory of Open Access Journals (Sweden)

    Asalapuram R. Pavankumar

    2008-01-01

    Full Text Available Among foodborne pathogens, diarrhoeagenic Escherichia coli is of major concern because of its commensal status, abundance in the natural environment, and ability to acquire virulence determinants by horizontal gene transfer from other microbes. From enterotoxigenic E. coli (ETEC strains to the more virulent enterohemorrhagic E. coli (EHEC, the mechanisms of pathogenicity within this species are intriguing. Recent advances in molecular diagnostics are providing novel tools for improved rapid detection and quantification of this and other pathogenic bacteria from clinical, food, and environmental specimens. These include simple and inexpensive colorimetric and immunological methods to more elaborate nucleic acid-based assays that combine extreme specificity to unparalleled sensitivity and high sample throughput. This review summarizes the current state of E. coli pathogenesis with emphasis on the need for incorporating detection and surveillance tools as part of pre- and post-harvest food safety ideals.

  17. Specific patterns of gyrA mutations determine the resistance difference to ciprofloxacin and levofloxacin in Klebsiella pneumoniae and Escherichia coli

    Science.gov (United States)

    2013-01-01

    Background Wide use of ciprofloxacin and levofloxacin has often led to increased resistance. The resistance rate to these two agents varies in different clinical isolates of Enterobacteriaceae. Mutations of GyrA within the quinolone resistance-determining regions have been found to be the main mechanism for quinolone resistance in Enterobacteriaceae. It has been shown that only some of the mutations in the gyrA gene identified from clinical sources were involved in fluoroquinolone resistance. Whether different patterns of gyrA mutation are related to antimicrobial resistance against ciprofloxacin and levofloxacin is unclear. Methods The minimum inhibitory concentration (MIC) of ciprofloxacin and levofloxacin were determined by the agar dilution method followed by PCR amplification and sequencing of the quinolone resistance determining region of gyrA to identify all the mutation types. The correlation between fluoroquinolone resistance and the individual mutation type was analyzed. Results Resistance differences between ciprofloxacin and levofloxacin were found in 327 isolates of K. pneumoniae and E. coli in Harbin, China and in the isolates reported in PubMed publications. GyrA mutations were found in both susceptible and resistant isolates. For the isolates with QRDR mutations, the resistance rates to ciprofloxacin and levofloxacin were also statistically different. Among the 14 patterns of alterations, two single mutations (Ser83Tyr and Ser83Ile), and three double mutations (Ser83Leu+Asp87Asn, Ser83Leu+Asp87Tyr and Ser83Phe+Asp87Asn) were associated with both ciprofloxacin and levofloxacin resistance. Two single mutations (Ser83Phe and Ser83Leu) were related with ciprofloxacin resistance but not to levofloxacin. Resistance difference between ciprofloxacin and levofloxacin in isolates harboring mutation Ser83Leu+Asp87Asn were of statistical significance among all Enterobacteriaceae (Plevofloxacin were statistically different among clinical isolates of

  18. Immunomagnetic separation of Escherichia coli O157:H7 from ...

    African Journals Online (AJOL)

    Standard immunoassay kits specific for the O157 and H7 antigen and a biochemical indole test were used for further E. coli O157:H7 confirmation. Three colonies from one sewage sample (1.1 % of all sewage samples) agglutinated with anti-E. coli O157 and H7 antiserum and contained the genes coding for Stx2, eaeA ...

  19. Inhibition of Escherichia coli in cultivated cattle manure.

    Science.gov (United States)

    Weinberg, Z G; Szakacs, G; Chen, Y; Pinto, R; Bernstein, S; Konya, B; Sela Saldinger, S

    2014-05-01

    A common practice on Israeli dairy barns comprises daily cultivation of the manure. Cultivation is a mechanical process used to break up and till the manure bedding and it results in a drier and aerated bedding and cleaner cows, which consequently reduces the incidence of mastitis. Cultivation was associated with a shorter survival of Escherichia coli in cultivated manure as compared with noncultivated manure. The objective of the current study was to elucidate the mechanism responsible for the shorter survival duration of E. coli in the cultivated manure. We hypothesized that microorganisms that are antagonistic to E. coli, developing in the cultivated manure, are responsible for this phenomenon. A cow manure derived E. coli strain expressing the green fluorescence protein and antibiotic resistance markers was used to inoculate cow manure in 1.5-L jars. Manure treatments included cultivated and noncultivated manure. Half the jars of each cultivation treatment were autoclave sterilized at 121°C for 1 h on 3 successive days to eliminate from the manure antagonistic microorganisms. Each cultivation-sterilization treatment was performed in triplicate jars. Following sterilization, E. coli numbers in the cultivated and noncultivated manure were comparable, while in the nonsterilized manure the numbers were lower in the cultivated compared with the noncultivated manure. Several fungi isolated from the cultivated manure samples displayed inhibition effect on the tagged E. coli. Antagonistic fungi were also isolated from large-scale cultivated manure samples collected on several dairy farms in Israel. These findings support the notion that manure cultivation might facilitate the development of microorganisms that are antagonistic to E. coli, thus contributing to the general hygiene of the cattle. Identifying the mechanisms by which the antagonistic fungi affect the survival of E. coli in manure could be exploited for improvement of the animal health and for limiting the

  20. Jumlah Bakteri Coliform dan Deteksi Escherichia Coli pada Daging Ayam di Pekanbaru

    OpenAIRE

    Juwita, Usna; Haryani, Yuli; Jose, Christine

    2014-01-01

    Coliform bacteria are often referred as indicator organisms to indicate the potential presence of disease-causing bacteria. Escherichia coli is a type of Coliform bacteria. Most Escherichia coli are harmless and commonly found in the intestines of humans and animals. However, some strains can cause illness. Coliform bacteria and Escherichia coli contamination in chicken could be detected using Most Probable Number (MPN) multi-step assay which consists of presumptive, confirmed, and completed ...

  1. Fusion of pyruvate decarboxylase and alcohol dehydrogenase increases ethanol production in Escherichia coli.

    Science.gov (United States)

    Lewicka, Aleksandra J; Lyczakowski, Jan J; Blackhurst, Gavin; Pashkuleva, Christiana; Rothschild-Mancinelli, Kyle; Tautvaišas, Dainius; Thornton, Harry; Villanueva, Hugo; Xiao, Weike; Slikas, Justinas; Horsfall, Louise; Elfick, Alistair; French, Christopher

    2014-12-19

    Ethanol is an important biofuel. Heterologous expression of Zymomonas mobilis pyruvate decarboxylase (Pdc) and alcohol dehydrogenase (AdhB) increases ethanol production in Escherichia coli. A fusion of PDC and ADH was generated and expressed in E. coli. The fusion enzyme was demonstrated to possess both activities. AdhB activity was significantly lower when fused to PDC than when the two enzymes were expressed separately. However, cells expressing the fusion protein generated ethanol more rapidly and to higher levels than cells coexpressing Pdc and AdhB, suggesting a specific rate enhancement due to the fusion of the two enzymes.

  2. bTSSfinder: a novel tool for the prediction of promoters in cyanobacteria and Escherichia coli

    OpenAIRE

    Shahmuradov, Ilham Ayub; Mohamad Razali, Rozaimi; Bougouffa, Salim; Radovanovic, Aleksandar; Bajic, Vladimir B.

    2016-01-01

    Abstract Motivation: The computational search for promoters in prokaryotes remains an attractive problem in bioinformatics. Despite the attention it has received for many years, the problem has not been addressed satisfactorily. In any bacterial genome, the transcription start site is chosen mostly by the sigma (?) factor proteins, which control the gene activation. The majority of published bacterial promoter prediction tools target ?70 promoters in Escherichia coli. Moreover, no ?-specific ...

  3. Bromelain protects piglets from diarrhoea caused by oral challenge with K88 positive enterotoxigenic Escherichia coli

    OpenAIRE

    Chandler, D; Mynott, T

    1998-01-01

    Background—K88 positive enterotoxigenic Escherichia coli (K88+ ETEC) is an important cause of diarrhoea in young piglets. K88+ ETEC pathogenesis relies on attachment to specific glycoprotein receptors located on the intestinal mucosa. Proteolytic treatment of these receptors in vitro and in vivo prevents attachment of K88+ ETEC to piglet small intestines and may be of clinical use to prevent K88+ ETEC pathogenesis. 
Aims—To determine whether bromelain, a proteolytic ex...

  4. Genetic Basis of Evolutionary Adaptation by Escherichia coli to Stressful Cycles of Freezing, Thawing and Growth

    OpenAIRE

    Sleight, Sean C.; Orlic, Christian; Schneider, Dominique; Lenski, Richard E.

    2008-01-01

    Microbial evolution experiments offer a powerful approach for coupling changes in complex phenotypes, including fitness and its components, with specific mutations. Here we investigate mutations substituted in 15 lines of Escherichia coli that evolved for 1000 generations under freeze–thaw–growth (FTG) conditions. To investigate the genetic basis of their improvements, we screened many of the lines for mutations involving insertion sequence (IS) elements and identified two genes where multipl...

  5. Recombinant expression, refolding, purification and characterization of Pseudomonas aeruginosa protease IV in Escherichia coli.

    Science.gov (United States)

    Zhao, Mingzhi; Cai, Man; Wu, Feilin; Zhang, Yao; Xiong, Zhi; Xu, Ping

    2016-10-01

    Several protease IV enzymes are widely used in proteomic research. Specifically, protease IV from Pseudomonas aeruginosa has lysyl endopeptidase activity. Here, we report the recombinant expression, refolding, activation, and purification of this protease in Escherichia coli. Proteolytic instability of the activated intermediate, a major obstacle for efficient production, is controlled through ammonium sulfate precipitation. The purified protease IV exhibits superior lysyl endopeptidase activity compared to a commercial product. Copyright © 2016. Published by Elsevier Inc.

  6. The Origin of Bacterial Resistance to Proflavine: 5. Transformation of Proflavine Resistance in Escherichia coli

    National Research Council Canada - National Science Library

    SINAI, JEHUDITH; YUDKIN, J

    1959-01-01

    ...: We attempted to transform proflavine-sensitive strains of Escherichia coli to proflavine resistance by growth in the presence of deoxyribonucleic acid-containing extracts from resistant organisms...

  7. THE WIDESPREAD OCCURRENCE OF THE ENTEROHEMOLYSIN GENE EHLYA AMONG ENVIRONMENTAL STRAINS OF ESCHERICHIA COLI

    Science.gov (United States)

    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 ...

  8. Escherichia coli β-Lactamases: What Really Matters

    Science.gov (United States)

    Bajaj, Priyanka; Singh, Nambram S.; Virdi, Jugsharan S.

    2016-01-01

    Escherichia coli strains belonging to diverse pathotypes have increasingly been recognized as a major public health concern. The β-lactam antibiotics have been used successfully to treat infections caused by pathogenic E. coli. However, currently, the utility of β-lactams is being challenged severely by a large number of hydrolytic enzymes – the β-lactamases expressed by bacteria. The menace is further compounded by the highly flexible genome of E. coli, and propensity of resistance dissemination through horizontal gene transfer and clonal spread. Successful management of infections caused by such resistant strains requires an understanding of the diversity of β-lactamases, their unambiguous detection, and molecular mechanisms underlying their expression and spread with regard to the most relevant information about individual bacterial species. Thus, this review comprises first such effort in this direction for E. coli, a bacterial species known to be associated with production of diverse classes of β-lactamases. The review also highlights the role of commensal E. coli as a potential but under-estimated reservoir of β-lactamases-encoding genes. PMID:27065978

  9. Escherichia coli ST131, an intriguing clonal group.

    Science.gov (United States)

    Nicolas-Chanoine, Marie-Hélène; Bertrand, Xavier; Madec, Jean-Yves

    2014-07-01

    In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum β-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  10. Escherichia coli ST131, an Intriguing Clonal Group

    Science.gov (United States)

    Bertrand, Xavier; Madec, Jean-Yves

    2014-01-01

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

  11. Recent Advances in Understanding Enteric Pathogenic Escherichia coli

    Science.gov (United States)

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

    2013-01-01

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

  12. Verotoxigenic Escherichia coli (VTEC isolated from cow milk

    Directory of Open Access Journals (Sweden)

    Widodo Suwito

    2016-01-01

    Full Text Available Verotoxigenic Escherichia coli (VTEC strains are responsible for serious human illnesses. These strains are commonly found in milk. The aim of this study was to determine the occurrence of verotoxigenic E. coli in milk. A total of 351 milk samples, were collected from dairy farms in Bogor, Sukabumi and Cianjur. These samples were analyzed for VTEC using biochemical, serological and vero cell cytotoxicity assays. VTEC O157:H7 isolates were found in milk collected from dairy herds in Bogor and Sukabumi at rates 0.47% of 214 samples, 1.10% of 91 samples respectively, and none in Cianjur. Hemolytic E. coli isolates were found in 0.94% of 214 milk samples from Bogor, 2.2% of 91 milk samples from Sukabumi and none from Cianjur. From E. coli isolates, 53 isolates (67.95% were verotoxigenic, consisted of: two E. coli O157:H7 isolates and 51 non O157:H7 isolates.Therefore this study showed the occurrence of VTEC in milk samples from dairy farms in Bogor, Sukabumi and Cianjur.

  13. Serotypes of Escherichia coli in sudden infant death syndrome.

    Science.gov (United States)

    Pearce, J L; Bettelheim, K A; Luke, R K J; Goldwater, P N

    2010-02-01

    To examine the diversity of Escherichia coli serotypes found in the intestinal contents of infants who died of Sudden Infant Death Syndrome (SIDS) compared with that in comparison infants. Over the 3-year period, 1989-1991, in South Australia and Victoria (Australia), a total of 687 E. coli isolates from 231 patients with SIDS (348 isolates), 98 infants who had died from other causes (144 isolates) and 160 healthy infants (195 isolates) were studied. The isolates from patients with SIDS were found to represent 119 different serotypes; the isolates from 'other cause' infants represent 97 different serotypes; and the isolates from healthy infants represent 117 different serotypes. The seven common serotypes isolated most frequently from infants with SIDS belonged to those associated with extra-intestinal infections in humans. Compared to healthy infants (6%), these were found in significantly higher proportions among infants who died of other causes (13%, P < 0.05) or infants with SIDS (18.7%, P = 0.0002). Despite these sources yielding a wide variety of serotypes of E. coli, a pattern of certain potential pathotypes of E. coli being associated with SIDS is apparent. While SIDS remains one of the most important diagnoses of postneonatal death, its causes are still unexplained. If E. coli has a role in the pathogenesis of SIDS (as suggested by the pathotypes identified on the basis of serotype), further studies may reveal novel virulence factors that may clarify the role of this bacterium in SIDS.

  14. Molybdopterin dinucleotide biosynthesis in Escherichia coli: identification of amino acid residues of molybdopterin dinucleotide transferases that determine specificity for binding of guanine or cytosine nucleotides.

    Science.gov (United States)

    Neumann, Meina; Seduk, Farida; Iobbi-Nivol, Chantal; Leimkühler, Silke

    2011-01-14

    The molybdenum cofactor is modified by the addition of GMP or CMP to the C4' phosphate of molybdopterin forming the molybdopterin guanine dinucleotide or molybdopterin cytosine dinucleotide cofactor, respectively. The two reactions are catalyzed by specific enzymes as follows: the GTP:molybdopterin guanylyltransferase MobA and the CTP:molybdopterin cytidylyltransferase MocA. Both enzymes show 22% amino acid sequence identity and are specific for their respective nucleotides. Crystal structure analysis of MobA revealed two conserved motifs in the N-terminal domain of the protein involved in binding of the guanine base. Based on these motifs, we performed site-directed mutagenesis studies to exchange the amino acids to the sequence found in the paralogue MocA. Using a fully defined in vitro system, we showed that the exchange of five amino acids was enough to obtain activity with both GTP and CTP in either MocA or MobA. Exchange of the complete N-terminal domain of each protein resulted in the total inversion of nucleotide specificity activity, showing that the N-terminal domain determines nucleotide recognition and binding. Analysis of protein-protein interactions showed that the C-terminal domain of either MocA or MobA determines the specific binding to the respective acceptor protein.

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

    Science.gov (United States)

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

    2017-11-01

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

  16. Escherichia coli mediated urinary tract infections: are there distinct uropathogenic E. coli (UPEC) pathotypes?

    Science.gov (United States)

    Marrs, Carl F; Zhang, Lixin; Foxman, Betsy

    2005-11-15

    A variety of virulence genes are associated with Escherichia coli mediated urinary tract infections. Particular sets of virulence factors shared by bacterial strains directing them through a particular pathogenesis process are called a "pathotype." Comparison of co-occurrence of potential urinary tract infection (UTI) virulence genes among different E. coli isolates from fecal and UTI collections provides evidence for multiple pathotypes of uropathogenic E. coli, but current understanding of critical genetic differences defining the pathotypes is limited. Discovery of additional E. coli genes involved in uropathogenesis and determination of their distribution and co-occurrences will further define UPEC pathotypes and allow for a more detailed analysis of how these pathotypes might differ in how they cause disease.

  17. Detection of Escherichia coli, Salmonella species, and Vibrio cholerae in tap water and bottled drinking water in Isfahan, Iran.

    Science.gov (United States)

    Momtaz, Hassan; Dehkordi, Farhad Safarpoor; Rahimi, Ebrahim; Asgarifar, Amin

    2013-06-07

    The quality of drinking water has an important role in human infection and disease. This study was aimed at comparing polymerase chain reaction and culture in detecting Escherichia coli, Salmonella species and Vibrio cholera in tape water and bottled drinking water in various seasons in Isfahan province, Iran. A total of 448 water samples from tap water and bottled mineral water were taken over 6 months, from July 2010 to December 2010, and after filtration, samples were examined by culture and polymerase chain reaction methods for detection of Escherichia coli, Salmonella species, and Vibrio cholerae. The culture method showed that 34 (7.58%), 4 (0.89%) and 3 (0.66%) of all 448 water samples were positive for Escherichia coli, Salmonella species, and Vibrio cholera, respectively. The uidA gene from Escherichia coli, IpaB gene from Salmonella species, and epsM gene from Vibrio cholera were detected in 38 (26.38%), 5 (3.47%), and 3 (2.08%) of 144 tap-water samples, respectively. Escherichia coli was detected in 8 (2.63%) of 304 samples of bottled drinking water from 5 companies. The water of southern part of Isfahan and company 5 had the highest prevalence of bacteria. The Escherichia coli water contamination was significantly higher (P waters of southern part and tap waters of central part of Isfahan. This study showed that the polymerase chain reaction assays can be an extremely accurate, fast, safe, sensitive and specific approach to monitor drinking water quality from purification facilities and bottled water companies. Also, our study confirmed the presence of Escherichia coli, Salmonella species, and Vibrio cholerae as water-borne pathogens in tap water and bottled drinking water of Isfahan, Iran. The present study showed the important public health problem in Isfahan, Iran.

  18. Viabilidad de Escherichia coli en presencia de diferentes contaminantes

    Directory of Open Access Journals (Sweden)

    Antonio Rivera T

    2006-04-01

    Full Text Available La contaminación en ríos condiciona la presencia de microorganismos adaptados al ecosistema entre ellos a patógenos de importancia en salud pública. Objetivo: Determinar la viabilidad de Escherichia coli en presencia de nitrato de plata, carbonato de amonio, fenol y formaldehído. Materiales y métodos: Se tomaron muestras de agua del río Alseseca, que luego se sembró en medios de cultivo selectivos para enterobacterias, seleccionándose las colonias del género Escherichia, las cuales fueron sembradas en el medio de orientación CHROMagar ECC. Las muestras de E. coli se evaluaron en presencia de nitrato de plata, carbonato de amonio, fenol y formaldehído. Resultados: El grupo experimental presentó viabilidad en presencia de los cuatro compuestos, el grupo control positivo presentó nula viabilidad, la comparación entre los grupos mostró diferencia significativa (p< 0,05. Conclusión: Los aislamientos de E. coli mostraron viabilidad, implicando riesgos para el ecosistemas y la salud, ya que el río Alseseca atraviesa por el municipio de Puebla donde existen núcleos poblacionales importantes.

  19. Kemampuan Antibakteri Susu Fermentasi terhadap Escherichia coli dan Shigella

    Directory of Open Access Journals (Sweden)

    Zuraida Hanum

    2017-04-01

    ABSTRACT. The study was performed using Lactobacillus plantarum as starter at concentrations of 3%, 4% and 5% and incubated for 48 hours at room temperature. Observation of fermented milk conducted for 8 day. The antibacterial activity test was analyzed to find whether fermented milk able to  inhibit pathogen growth. The antibacterial ability of suppressing of Enterobacteriaceae growth  observed by using Escherichia coli and Shigella flexneri (106 CFU/ml in Nutrient Agar and challenge to fermented milk using 3%, 4% and 5% starter or about (50 µl/well. Further testing of microbial inhibitory activity of fermented milk against pathogenic bacteria conducted by three replications. The data obtained were analyzed statistically using ANOVA. The results showed that the ability of fermented milk as antibacterial on Escherichia coli and Shigella flexneri occurred in the amount of sell as much as (106 CFU / ml when it grown in nutrient agar. As a conclusion,  fermented milk using a 5% starter showed that the highest inhibition zone of 17.42 mm to E. coli on the second day observation. While  inhibition zone of  Shigella flexnerii was 8.88 mm on the third day with the same starter concentration.

  20. Pathophysiology of Escherichia coli ventilator-associated pneumonia: implication of highly virulent extraintestinal pathogenic strains.

    Science.gov (United States)

    Messika, Jonathan; Magdoud, Fatma; Clermont, Olivier; Margetis, Dimitri; Gaudry, Stéphane; Roux, Damien; Branger, Catherine; Dreyfuss, Didier; Denamur, Erick; Ricard, Jean-Damien

    2012-12-01

    To characterize Escherichia coli ventilator-associated pneumonia (VAP) in intensive care unit (ICU) patients by determining antibioresistance and genotypic characteristics of E. coli isolates responsible for VAP or lung colonization, by comparing them with their oropharyngeal and rectal counterparts and by assessing representative isolates' virulence in a pneumonia mouse model. Patients under mechanical ventilation for more than 72 h were screened for simultaneous presence of E. coli in rectal, oropharyngeal, and respiratory samples (colonization or VAP). If present, E. coli isolates were characterized by antimicrobial susceptibility, phylogenetic grouping, and virulence factor (VF) gene content determination. BALB/c mice were challenged intranasally with 3.6 × 10(8) colony-forming units (CFU) of patients' E. coli isolates. Multisite E. coli colonization was observed in 19 % of patients (25 patients, 12 with E. coli VAP). One hundred fifteen distinct E. coli isolates were analyzed. B2 phylogenetic group was predominant, with high VF gene content and low antimicrobial resistance. Antimicrobial resistance diversity was observed in four patients with VAP. E. coli isolates from VAP patients were more frequently B2 isolates, with significantly greater VF gene content than lung colonization isolates. Among screened VF genes, iroN and sfa appeared important for lung infection. A very strong correlation (R (2) = 0.99) was found between VF gene content and mortality in the mouse model. This is the first study establishing antibioresistance and genotypic characteristics of E. coli isolates responsible for VAP in adult ICU patients. These isolates are highly virulent specific extraintestinal pathogenic E. coli strains expressing virulence factors, representing potential targets for new therapies.

  1. Isolation and characterization of lytic bacteriophages against enterohaemorrhagic Escherichia coli.

    Science.gov (United States)

    Viazis, S; Akhtar, M; Feirtag, J; Brabban, A D; Diez-Gonzalez, F

    2011-05-01

     The objective of this study was to isolate, identify and characterize a collection of lytic bacteriophages capable of infecting enterohaemorrhagic Escherichia coli (EHEC) serotypes. Phages were isolated from dairy and cattle feedlot manure using E. coli O157, O26 and O111 strains as hosts. Phages were enriched from faecal slurries by culture in 10× trypticase soy broth at 37°C overnight. Phage plaques were obtained by mixing the filtered culture supernatant with molten tryptone agar containing the phage E. coli host strain, pouring the inoculated agar on top of cooled TS agar and incubating the culture overnight. Phages were purified from plaques and screened against additional E. coli and EHEC strains by the efficiency of plating method (EOP). Phage CEV2, and five other phages previously isolated, were able to lyse all of the 15 O157 strains tested with EOP values consistently above 0·001. Two phages were found to be highly effective against strains of E. coli O157 through EOP tests and against O26 strains through spot tests, but not against the O serogroup 111 strains. A cocktail of eight phage that lyse E. coli O157 strains resulted in >5 log CFU ml(-1) reductions at 37°C. Multiplex-PCR revealed that none of these eight phages carried stx1, stx2, hlyA or eaeA genes. A cocktail of bacteriophages was capable of lysing most strains of two EHEC serotypes. This collection of phages can be combined and potentially used as an antimicrobial cocktail to inactivate E. coli strains from O serogroups 157 and 26 and reduce their incidence in the food chain. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

  2. Spatial Distribution of Escherichia coli in the Mouse Large Intestine Inferred from rRNA In Situ Hybridization

    DEFF Research Database (Denmark)

    Poulsen, Lars Kærgaard; Lan, Fusheng; Sternberg, Claus

    1994-01-01

    Fluorescent oligonucleotide probes targeting rRNA were used to develop an in situ hybridization technique by which the spatial distribution of Escherichia coli in the large intestines of streptomycin-treated mice was determined. Single E. coli cells were identified in thin frozen sections from...... the large intestines by the use of a probe specific for E. coli 23S rRNA. Furthermore, the total bacterial population was visualized with an rRNA probe targeting the domain Bacteria. By this technique, all E. coli cells were seen embedded in the mucosal material overlying the epithelial cells of the large...... intestine, and no direct attachment to the epithelium was observed....

  3. Attaching and effacing Escherichia coli isolates from Danish children: clinical significance and microbiological characteristics

    DEFF Research Database (Denmark)

    Jensen, C; Ethelberg, S; Olesen, B

    2007-01-01

    This study describes the prevalence, clinical manifestations and microbiological characteristics of attaching and effacing Escherichia coli isolates, i.e., enteropathogenic E. coli (EPEC) belonging to the classical EPEC serotypes, non-EPEC attaching and effacing E. coli (A/EEC) and verocytotoxin......-producing E. coli (VTEC), isolated in a case-control study of Danish children aged

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

    Science.gov (United States)

    Vidal, Roberto; Vidal, Maricel; Lagos, Rossana; Levine, Myron; Prado, Valeria

    2004-01-01

    A multiplex PCR for detection of three categories of diarrheagenic Escherichia coli was developed. With this method, enterohemorrhagic E. coli, enteropathogenic E. coli, and enterotoxigenic E. coli were identified in fecal samples from patients with hemorrhagic colitis, watery diarrhea, or hemolytic-uremic syndrome and from food-borne outbreaks. PMID:15071051

  5. Detection of diarrheagenic Escherichia coli by use of melting-curve analysis and real-time multiplex PCR.

    Science.gov (United States)

    Guion, Chase E; Ochoa, Theresa J; Walker, Christopher M; Barletta, Francesca; Cleary, Thomas G

    2008-05-01

    Diarrheagenic Escherichia coli strains are important causes of diarrhea in children from the developing world and are now being recognized as emerging enteropathogens in the developed world. Current methods of detection are too expensive and labor-intensive for routine detection of these organisms to be practical. We developed a real-time fluorescence-based multiplex PCR for the detection of all six of the currently recognized classes of diarrheagenic E. coli. The primers were designed to specifically amplify eight different virulence genes in the same reaction: aggR for enteroaggregative E. coli, stIa/stIb and lt for enterotoxigenic E. coli, eaeA for enteropathogenic E. coli and Shiga toxin-producing E. coli (STEC), stx(1) and stx(2) for STEC, ipaH for enteroinvasive E. coli, and daaD for diffusely adherent E. coli (DAEC). Eighty-nine of ninety diarrheagenic E. coli and 36/36 nonpathogenic E. coli strains were correctly identified using this approach (specificity, 1.00; sensitivity, 0.99). The single false negative was a DAEC strain. The total time between preparation of DNA from E. coli colonies on agar plates and completion of PCR and melting-curve analysis was less than 90 min. The cost of materials was low. Melting-point analysis of real-time multiplex PCR is a rapid, sensitive, specific, and inexpensive method for detection of diarrheagenic E. coli.

  6. Detection of Diarrheagenic Escherichia coli by Use of Melting-Curve Analysis and Real-Time Multiplex PCR ▿

    Science.gov (United States)

    Guion, Chase E.; Ochoa, Theresa J.; Walker, Christopher M.; Barletta, Francesca; Cleary, Thomas G.

    2008-01-01

    Diarrheagenic Escherichia coli strains are important causes of diarrhea in children from the developing world and are now being recognized as emerging enteropathogens in the developed world. Current methods of detection are too expensive and labor-intensive for routine detection of these organisms to be practical. We developed a real-time fluorescence-based multiplex PCR for the detection of all six of the currently recognized classes of diarrheagenic E. coli. The primers were designed to specifically amplify eight different virulence genes in the same reaction: aggR for enteroaggregative E. coli, stIa/stIb and lt for enterotoxigenic E. coli, eaeA for enteropathogenic E. coli and Shiga toxin-producing E. coli (STEC), stx1 and stx2 for STEC, ipaH for enteroinvasive E. coli, and daaD for diffusely adherent E. coli (DAEC). Eighty-nine of ninety diarrheagenic E. coli and 36/36 nonpathogenic E. coli strains were correctly identified using this approach (specificity, 1.00; sensitivity, 0.99). The single false negative was a DAEC strain. The total time between preparation of DNA from E. coli colonies on agar plates and completion of PCR and melting-curve analysis was less than 90 min. The cost of materials was low. Melting-point analysis of real-time multiplex PCR is a rapid, sensitive, specific, and inexpensive method for detection of diarrheagenic E. coli. PMID:18322059

  7. Deuterium incorporation into Escherichia-coli proteins

    DEFF Research Database (Denmark)

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

    1986-01-01

    Neutron small-angle scattering studies of single protein subunits in a protein-DNA complex require the adjustment of the neutron scattering-length densities of protein and DNA, which is attainable by specific deuteration of the protein. The neutron scattering densities of unlabelled DNA and DNA-dependent...

  8. Molybdopterin Dinucleotide Biosynthesis in Escherichia coli

    Science.gov (United States)

    Neumann, Meina; Seduk, Farida; Iobbi-Nivol, Chantal; Leimkühler, Silke

    2011-01-01

    The molybdenum cofactor is modified by the addition of GMP or CMP to the C4′ phosphate of molybdopterin forming the molybdopterin guanine dinucleotide or molybdopterin cytosine dinucleotide cofactor, respectively. The two reactions are catalyzed by specific enzymes as follows: the GTP:molybdopterin guanylyltransferase MobA and the CTP:molybdopterin cytidylyltransferase MocA. Both enzymes show 22% amino acid sequence identity and are specific for their respective nucleotides. Crystal structure analysis of MobA revealed two conserved motifs in the N-terminal domain of the protein involved in binding of the guanine base. Based on these motifs, we performed site-directed mutagenesis studies to exchange the amino acids to the sequence found in the paralogue MocA. Using a fully defined in vitro system, we showed that the exchange of five amino acids was enough to obtain activity with both GTP and CTP in either MocA or MobA. Exchange of the complete N-terminal domain of each protein resulted in the total inversion of nucleotide specificity activity, showing that the N-terminal domain determines nucleotide recognition and binding. Analysis of protein-protein interactions showed that the C-terminal domain of either MocA or MobA determines the specific binding to the respective acceptor protein. PMID:21081498

  9. Specific recognition of rpsO mRNA and 16S rRNA by Escherichia coli ribosomal protein S15 relies on both mimicry and site differentiation.

    Science.gov (United States)

    Mathy, Nathalie; Pellegrini, Olivier; Serganov, Alexander; Patel, Dinshaw J; Ehresmann, Chantal; Portier, Claude

    2004-05-01

    The ribosomal protein S15 binds to 16S rRNA, during ribosome assembly, and to its own mRNA (rpsO mRNA), affecting autocontrol of its expression. In both cases, the RNA binding site is bipartite with a common subsite consisting of a G*U/G-C motif. The second subsite is located in a three-way junction in 16S rRNA and in the distal part of a stem forming a pseudoknot in Escherichia coli rpsO mRNA. To determine the extent of mimicry between these two RNA targets, we determined which amino acids interact with rpsO mRNA. A plasmid carrying rpsO (the S15 gene) was mutagenized and introduced into a strain lacking S15 and harbouring an rpsO-lacZ translational fusion. Analysis of deregulated mutants shows that each subsite of rpsO mRNA is recognized by a set of amino acids known to interact with 16S rRNA. In addition to the G*U/G-C motif, which is recognized by the same amino acids in both targets, the other subsite interacts with amino acids also involved in contacts with helix H22 of 16S rRNA, in the region adjacent to the three-way junction. However, specific S15-rpsO mRNA interactions can also be found, probably with A(-46) in loop L1 of the pseudoknot, demonstrating that mimicry between the two targets is limited.

  10. Deep sequencing reveals as-yet-undiscovered small RNAs in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Hirano Reiko

    2011-08-01

    Full Text Available Abstract Background In Escherichia coli, approximately 100 regulatory small RNAs (sRNAs have been identified experimentally and many more have been predicted by various methods. To provide a comprehensive overview of sRNAs, we analysed the low-molecular-weight RNAs (E. coli with deep sequencing, because the regulatory RNAs in bacteria are usually 50-200 nt in length. Results We discovered 229 novel candidate sRNAs (≥ 50 nt with computational or experimental evidence of transcription initiation. Among them, the expression of seven intergenic sRNAs and three cis-antisense sRNAs was detected by northern blot analysis. Interestingly, five novel sRNAs are expressed from prophage regions and we note that these sRNAs have several specific characteristics. Furthermore, we conducted an evolutionary conservation analysis of the candidate sRNAs and summarised the data among closely related bacterial strains. Conclusions This comprehensive screen for E. coli sRNAs using a deep sequencing approach has shown that many as-yet-undiscovered sRNAs are potentially encoded in the E. coli genome. We constructed the Escherichia coli Small RNA Browser (ECSBrowser; http://rna.iab.keio.ac.jp/, which integrates the data for previously identified sRNAs and the novel sRNAs found in this study.

  11. Iron-binding proteins in milk and resistance to Escherichia coli infection in infants.

    Science.gov (United States)

    Bullen, J J; Rogers, H J; Leigh, L

    1972-01-08

    Human milk contains large quantities of iron-binding protein, of which the greater proportion is lactoferrin, though small amounts of transferrin are also present. Three samples of human milk with unsaturated iron-binding capacities of between 56 and 89% had a powerful bacteriostatic effect on Escherichia coli O111/B4. The bacteriostatic properties of milk were abolished if the iron-binding proteins were saturated with iron. Purified human lactoferrin, in combination with specific E. coli antibody, strongly inhibited the growth of E. coli, and this effect was also abolished by saturating the lactoferrin with iron.Guinea-pig milk also contains lactoferrin and transferrin. Newly born guinea-pigs fed on an artificial diet and dosed with E. coli O111 had higher counts of E. coli O111 in the intestine than suckled animals. The apparent suppressive effect of guinea-pig milk on E. coli in the intestine could be reversed by feeding the iron compound haematin. It seems that iron-binding proteins in milk may play an important part in resistance to infantile enteritis caused by E. coli.

  12. Catabolite and Oxygen Regulation of Enterohemorrhagic Escherichia coli Virulence

    Directory of Open Access Journals (Sweden)

    Kimberly M. Carlson-Banning

    2016-11-01

    Full Text Available The biogeography of the gut is diverse in its longitudinal axis, as well as within specific microenvironments. Differential oxygenation and nutrient composition drive the membership of microbial communities in these habitats. Moreover, enteric pathogens can orchestrate further modifications to gain a competitive advantage toward host colonization. These pathogens are versatile and adept when exploiting the human colon. They expertly navigate complex environmental cues and interkingdom signaling to colonize and infect their hosts. Here we demonstrate how enterohemorrhagic Escherichia coli (EHEC uses three sugar-sensing transcription factors, Cra, KdpE, and FusR, to exquisitely regulate the expression of virulence factors associated with its type III secretion system (T3SS when exposed to various oxygen concentrations. We also explored the effect of mucin-derived nonpreferred carbon sources on EHEC growth and expression of virulence genes. Taken together, the results show that EHEC represses the expression of its T3SS when oxygen is absent, mimicking the largely anaerobic lumen, and activates its T3SS when oxygen is available through Cra. In addition, when EHEC senses mucin-derived sugars heavily present in the O-linked and N-linked glycans of the large intestine, virulence gene expression is initiated. Sugars derived from pectin, a complex plant polysaccharide digested in the large intestine, also increased virulence gene expression. Not only does EHEC sense host- and microbiota-derived interkingdom signals, it also uses oxygen availability and mucin-derived sugars liberated by the microbiota to stimulate expression of the T3SS. This precision in gene regulation allows EHEC to be an efficient pathogen with an extremely low infectious dose.

  13. papA gene of avian pathogenic Escherichia coli.

    Science.gov (United States)

    Kariyawasam, Subhashinie; Nolan, Lisa K

    2011-12-01

    P fimbrial adhesins may be associated with the virulence of avian pathogenic Escherichia coli (APEC). However, most APECs are unable to express P fimbriae even when they are grown under conditions that favor P fimbrial expression. This failure can be explained by the complete absence of the pap operon or the presence of an incomplete pap operon in Pap-negative APEC strains. In the present study, we analyzed the pap operon, specifically the papA gene that encodes the major fimbrial shaft, to better understand the pap gene cluster at the genetic level. First, by PCR, we examined a collection of 500 APEC strains for the presence of 11 genes comprising the pap operon. Except for papA, all the other genes of the operon were present in 38% to 41.2% of APEC, whereas the papA was present only in 10.4% of the APEC tested. Using multiplex PCR to probe for allelic variants of papA, we sought to determine if the low prevalence of papA among APEC was related to genetic heterogeneity of the gene itself. It was determined that the papA of APEC always belongs to the F11 allelic variant. Finally, we sequenced the 'papA region' from two papA-negative strains, both of which contain all the other genes of the pap operon. Interestingly, both strains had an 11,104-bp contig interruptingpapA at the 281-bp position. This contig harbored a streptomycin resistance gene and a classic Tn10 transposon containing the genes that confer tetracycline resistance. However, we noted that the papA gene of every papA-negative APEC strain was not interrupted by an 11,104-bp contig. It is likely that transposons bearing antibiotic resistance genes have inserted within pap gene cluster of some APEC strains, and such genetic events may have been selected for by antibiotic use.

  14. Development of functionalised polyelectrolyte capsules using filamentous Escherichia coli cells

    Directory of Open Access Journals (Sweden)

    Lederer Franziska L

    2012-12-01

    Full Text Available Abstract Background Escherichia coli is one of the best studied microorganisms and finds multiple applications especially as tool in the heterologous production of interesting proteins of other organisms. The heterologous expression of special surface (S- layer proteins caused the formation of extremely long E. coli cells which leave transparent tubes when they divide into single E. coli cells. Such natural structures are of high value as bio-templates for the development of bio-inorganic composites for many applications. In this study we used genetically modified filamentous Escherichia coli cells as template for the design of polyelectrolyte tubes that can be used as carrier for functional molecules or particles. Diversity of structures of biogenic materials has the potential to be used to construct inorganic or polymeric superior hybrid materials that reflect the form of the bio-template. Such bio-inspired materials are of great interest in diverse scientific fields like Biology, Chemistry and Material Science and can find application for the construction of functional materials or the bio-inspired synthesis of inorganic nanoparticles. Results Genetically modified filamentous E. coli cells were fixed in 2% glutaraldehyde and coated with alternating six layers of the polyanion polyelectrolyte poly(sodium-4styrenesulfonate (PSS and polycation polyelectrolyte poly(allylamine-hydrochloride (PAH. Afterwards we dissolved the E. coli cells with 1.2% sodium hypochlorite, thus obtaining hollow polyelectrolyte tubes of 0.7 μm in diameter and 5–50 μm in length. For functionalisation the polyelectrolyte tubes were coated with S-layer protein polymers followed by metallisation with Pd(0 particles. These assemblies were analysed with light microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Conclusion The thus constructed new material offers possibilities for diverse applications like

  15. Resistencia a biocidas de diferentes cepas de escherichia coli

    OpenAIRE

    López Aguayo, M. Carmen; Lucas López, R.; Grande Burgos, M. José; Gálvez-del-Postigo-Ruiz, Antonio

    2010-01-01

    Los biocidas son herramientas de gran importancia para controlar la transmisión de microorganismos patógenos a través de la cadena alimentaria. En el presente estudio se ha determinado la resistencia a siete biocidas en una colección de nueve cepas de Escherichia coli, incluyendo cepas verotoxigénicas y cepas portadoras de resistencia a beta-lactámicos. Los biocidas más eficaces fueron triclosan, hexadecilpiridinio y cetrimida, seguido del cloruro de benzalconio. No se encon...

  16. Regulation of the L-arabinose operon of Escherichia coli.

    Science.gov (United States)

    Schleif, R

    2000-12-01

    Over forty years of research on the L-arabinose operon of Escherichia coli have provided insights into the mechanism of positive regulation of gene activity. This research also discovered DNA looping and the mechanism by which the regulatory protein changes its DNA-binding properties in response to the presence of arabinose. As is frequently seen in focused research on biological subjects, the initial studies were primarily genetic. Subsequently, the genetic approaches were augmented by physiological and then biochemical studies. Now biophysical studies are being conducted at the atomic level, but genetics still has a crucial role in the study of this system.

  17. Modeling the pressure inactivation dynamics of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Yamamoto K.

    2005-01-01

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

  18. Proton-linked L-fucose transport in Escherichia coli.

    OpenAIRE

    Bradley, S A; Tinsley, C R; Muiry, J A; Henderson, P J

    1987-01-01

    1. Addition of L-fucose to energy-depleted anaerobic suspensions of Escherichia coli elicited an uncoupler-sensitive alkaline pH change diagnostic of L-fucose/H+ symport activity. 2. L-Galactose or D-arabinose were also substrates, but not inducers, for the L-fucose/H+ symporter. 3. L-Fucose transport into subcellular vesicles was dependent upon respiration, displayed a pH optimum of about 5.5, and was inhibited by protonophores and ionophores. 4. These results showed that L-fucose transport ...

  19. Genome-scale genetic engineering in Escherichia coli.

    Science.gov (United States)

    Jeong, Jaehwan; Cho, Namjin; Jung, Daehee; Bang, Duhee

    2013-11-01

    Genome engineering has been developed to create useful strains for biological studies and industrial uses. However, a continuous challenge remained in the field: technical limitations in high-throughput screening and precise manipulation of strains. Today, technical improvements have made genome engineering more rapid and efficient. This review introduces recent advances in genome engineering technologies applied to Escherichia coli as well as multiplex automated genome engineering (MAGE), a recent technique proposed as a powerful toolkit due to its straightforward process, rapid experimental procedures, and highly efficient properties. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. DNA-damaging activity of patulin in Escherichia coli.

    OpenAIRE

    Lee, K S; Röschenthaler, R J

    1986-01-01

    At a concentration of 10 micrograms/ml, patulin caused single-strand DNA breaks in living cells of Escherichia coli. At 50 micrograms/ml, double-strand breaks were observed also. Single-strand breaks were repaired in the presence of 10 micrograms of patulin per ml within 90 min when the cells were incubated at 37 degrees C in M9-salts solution without a carbon source. The same concentration also induced temperature-sensitive lambda prophage and a prophage of Bacillus megaterium. When an in vi...

  1. Two classes of region III flagellar genes in Escherichia coli.

    OpenAIRE

    Kondoh, H; Ozeki, H.

    1981-01-01

    We infected various nonflagellated mutants of Escherichia coli with fla-transducing phages and followed the kinetics of the appearance of motility. Our analysis revealed two distinct classes of region III fla genes. Class II fla genes (hag, flaD) functioned 15 min later than class I fla genes (flaN, flaB, flaC, flaO, flaA, flbD, flaQ, flaP) in flagellar morphogenesis. We suggest that the two classes of fla genes are involved in two different stages, initiation (class I) and completion (class ...

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

    DEFF Research Database (Denmark)

    Freiesleben, Ulrik Von

    1996-01-01

    Dam methyltransferase deficient Escherichia coli cells containing minichromosomes were constructed. Free plasmid DNA could not be detected in these cells and the minichromosomes were found to be integrated in multiple copies in the origin of replication (oriC) region of the host chromosome...... and functional oriC sequence. The seqA2 mutation was found to overcome the incompatibility phenotype by increasing the cellular oriC copy nnumber 3-fold thereby allowing minichromosomes to coexist with the chromosome. The replication pattern of a wild type strain with multiple integrated minichromosomes...

  3. Intestinal Colonization by Enterotoxigenic ’Escherichia Coli

    Science.gov (United States)

    1976-12-01

    here were: i. to adopt or develop an in vitro system for the study of the adhesive abilities of porcine ETEC strains which lack K88 antigen, and ii. to...Rutter. 1972. Role of the K88 antigen in the pathogenesis of neonatal diarrhea caused by Escherichia coli in piglets . Infect. Immun. 6:918-927. 10. Jones...particular regard to those produced by atypical piglet strains and by calf and lamb strains: The transmissible nature of these enterotoxins and of a K

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

    Science.gov (United States)

    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. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  5. Biosynthesis and assembly of capsular polysaccharides in Escherichia coli.

    Science.gov (United States)

    Whitfield, Chris

    2006-01-01

    Capsules are protective structures on the surfaces of many bacteria. The remarkable structural diversity in capsular polysaccharides is illustrated by almost 80 capsular serotypes in Escherichia coli. Despite this variation, the range of strategies used for capsule biosynthesis and assembly is limited, and E. coli isolates provide critical prototypes for other bacterial species. Related pathways are also used for synthesis and export of other bacterial glycoconjugates and some enzymes/processes have counterparts in eukaryotes. In gram-negative bacteria, it is proposed that biosynthesis and translocation of capsular polysaccharides to the cell surface are temporally and spatially coupled by multiprotein complexes that span the cell envelope. These systems have an impact on both a general understanding of membrane trafficking in bacteria and on bacterial pathogenesis.

  6. Impact of antibiotic restriction on resistance levels of Escherichia coli

    DEFF Research Database (Denmark)

    Boel, Jonas Bredtoft; Andreasen, Viggo; Jarløv, Jens Otto

    2016-01-01

    as a retrospective controlled interrupted time series (ITS) at two university teaching hospitals, intervention and control, with 736 and 552 beds, respectively. The study period was between January 2008 and September 2014. We used ITS analysis to determine significant changes in antibiotic use and resistance levels......% CI -177, -126)] and fluoroquinolones [-44.5 DDDs/1000 bed-days (95% CI -58.9, -30.1)]. Resistance of E. coli showed a significant change in slope for cefuroxime [-0.13 percentage points/month (95% CI -0.21, -0.057)] and ciprofloxacin [-0.15 percentage points/month (95% CI -0.26, -0.038)]. CONCLUSIONS......OBJECTIVES: We evaluated the effect of an antibiotic stewardship programme (ASP) on the use of antibiotics and resistance levels of Escherichia coli using a method that allowed direct comparison between an intervention hospital and a control hospital. METHODS: The study was conducted...

  7. Impact of antibiotic restriction on resistance levels of Escherichia coli

    DEFF Research Database (Denmark)

    Boel, Jonas; Andreasen, Viggo; Jarløv, Jens Otto

    2016-01-01

    OBJECTIVES: We evaluated the effect of an antibiotic stewardship programme (ASP) on the use of antibiotics and resistance levels of Escherichia coli using a method that allowed direct comparison between an intervention hospital and a control hospital. METHODS: The study was conducted...... as a retrospective controlled interrupted time series (ITS) at two university teaching hospitals, intervention and control, with 736 and 552 beds, respectively. The study period was between January 2008 and September 2014. We used ITS analysis to determine significant changes in antibiotic use and resistance levels......% CI -177, -126)] and fluoroquinolones [-44.5 DDDs/1000 bed-days (95% CI -58.9, -30.1)]. Resistance of E. coli showed a significant change in slope for cefuroxime [-0.13 percentage points/month (95% CI -0.21, -0.057)] and ciprofloxacin [-0.15 percentage points/month (95% CI -0.26, -0.038)]. CONCLUSIONS...

  8. Metabolite essentiality elucidates robustness of Escherichia coli metabolism

    CERN Document Server

    Kim, Pan-Jun; Kim, Tae Yong; Lee, Kwang Ho; Jeong, Hawoong; Lee, Sang Yup; Park, Sunwon

    2007-01-01

    Complex biological systems are very robust to genetic and environmental changes at all levels of organization. Many biological functions of Escherichia coli metabolism can be sustained against single-gene or even multiple-gene mutations by using redundant or alternative pathways. Thus, only a limited number of genes have been identified to be lethal to the cell. In this regard, the reaction-centric gene deletion study has a limitation in understanding the metabolic robustness. Here, we report the use of flux-sum, which is the summation of all incoming or outgoing fluxes around a particular metabolite under pseudo-steady state conditions, as a good conserved property for elucidating such robustness of E. coli from the metabolite point of view. The functional behavior, as well as the structural and evolutionary properties of metabolites essential to the cell survival, was investigated by means of a constraints-based flux analysis under perturbed conditions. The essential metabolites are capable of maintaining a...

  9. Enteropathogenic and enterohaemorrhagic Escherichia coli: more subversive elements.

    Science.gov (United States)

    Frankel, G; Phillips, A D; Rosenshine, I; Dougan, G; Kaper, J B; Knutton, S

    1998-12-01

    Enteropathogenic (EPEC) and enterohaemorrhagic Escherichia coli (EHEC) constitute a significant risk to human health worldwide. Both pathogens colonize the intestinal mucosa and, by subverting intestinal epithelial cell function, produce a characteristic histopathological feature known as the 'attaching and effacing' (A/E) lesion. Although EPEC was the first E. coli to be associated with human disease in the 1940s and 1950s, it was not until the late 1980s and early 1990s that the mechanisms and bacterial gene products used to induce this complex brush border membrane lesion and diarrhoeal disease started to be unravelled. During the past few months, there has been a burst of new data that have revolutionized some basic concepts of the molecular basis of bacterial pathogenesis in general and EPEC pathogenesis in particular. Major breakthroughs and developments in the genetic basis of A/E lesion formation, signal transduction, protein translocation, host cell receptors and intestinal colonization are highlighted in this review.

  10. Sedimentation and gravitational instability of Escherichia coli Suspension

    Science.gov (United States)

    Salin, Dominique; Douarche, Carine

    2017-11-01

    The successive runs and tumbles of Escherichia coli bacteria provide an active matter suspension of rod-like particles with a large swimming, Brownian like, diffusion. As opposed to inactive elongated particles, this diffusion prevents clustering of the particles and hence instability in the gravity field. We measure the time dependent E . coli concentration profile during their sedimentation. After some hours, due to the dioxygen consumption, a motile / non-motile front forms leading to a Rayleigh-Taylor type gravitational instability. Analysing both sedimentation and instability in the framework of active particle suspensions, we can measure the relevant bacteria hydrodynamic characteristics such as its single particle sedimentation velocity and its hindrance volume. Comparing these quantities to the ones of equivalent passive particles (ellipsoid, rod) we tentatively infer the effective shape and size of the bacteria involved in its buoyancy induced advection and diffusion. Laboratoire FAST University Paris Saclay France.

  11. Starch based polyhydroxybutyrate production in engineered Escherichia coli.

    Science.gov (United States)

    Bhatia, Shashi Kant; Shim, Young-Ha; Jeon, Jong-Min; Brigham, Christopher J; Kim, Yong-Hyun; Kim, Hyun-Joong; Seo, Hyung-Min; Lee, Ju-Hee; Kim, Jung-Ho; Yi, Da-Hye; Lee, Yoo Kyung; Yang, Yung-Hun

    2015-08-01

    Every year, the amount of chemosynthetic plastic accumulating in the environment is increasing, and significant time is required for decomposition. Bio-based, biodegradable plastic is a promising alternative, but its production is not yet a cost effective process. Decreasing the production cost of polyhydroxyalkanoate by utilizing renewable carbon sources for biosynthesis is an important aspect of commercializing this biodegradable polymer. An Escherichia coli strain that expresses a functional amylase and accumulate polyhydroxybutyrate (PHB), was constructed using different plasmids containing the amylase gene of Panibacillus sp. and PHB synthesis genes from Ralstonia eutropha. This engineered strain can utilize starch as the sole carbon source. The maximum PHB production (1.24 g/L) was obtained with 2% (w/v) starch in M9 media containing 0.15% (w/v) yeast extract and 10 mM glycine betaine. The engineered E. coli SKB99 strain can accumulate intracellular PHB up to 57.4% of cell dry mass.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    The virulence determinants of uropathogenic Escherichia coli have been studied extensively over the years, but relatively little is known about what differentiates isolates causing various types of urinary tract infections. In this study, we compared the genomic profiles of 45 strains from a range...... of different clinical backgrounds, i.e., urosepsis, pyelonephritis, cystitis, and asymptomatic bacteriuria (ABU), using comparative genomic hybridization analysis. A microarray based on 31 complete E. coli sequences was used. It emerged that there is little correlation between the genotypes of the strains...... disease categories were identified. Among these were two genomic islands, namely, pathogenicity island (PAI)-CFT073-serU and PAI-CFT073-pheU, which were significantly more associated with the pyelonephritis and urosepsis isolates than with the ABU and cystitis isolates. These two islands harbor genes...

  13. How Escherichia coli Circumvent Complement-Mediated Killing

    Directory of Open Access Journals (Sweden)

    Angela S. Barbosa

    2017-04-01

    Full Text Available Complement is a crucial arm of the innate immune response against invading bacterial pathogens, and one of its main functions is to recognize and destroy target cells. Similar to other pathogens, Escherichia coli has evolved mechanisms to overcome complement activation. It is well known that capsular polysaccharide may confer resistance to complement-mediated killing and phagocytosis, being one of the strategies adopted by this bacterium to survive in serum. In addition, proteases produced by E. coli have been shown to downregulate the complement system. Pic, an autotransporter secreted by different pathogens in the Enterobacteriaceae family, is able to cleave C2, C3/C3b, and C4/C4b and works synergistically with human Factor I and Factor H (FH, thereby promoting inactivation of C3b. Extracellular serine protease P, a serine protease of enterohemorrhagic E. coli (EHEC, downregulates complement activation by cleaving C3/C3b and C5. StcE, a metalloprotease secreted by EHEC, inhibits the classical complement-mediated cell lysis by potentiating the action of C1 inhibitor, and the periplasmic protease Prc contributes to E. coli complement evasion by interfering with the classical pathway activation and by preventing membrane attack complex deposition. Finally, it has been described that E. coli proteins interact with negative complement regulators to modulate complement activation. The functional consequences resulting from the interaction of outer membrane protein A, new lipoprotein I, outer membrane protein W, and Stx2 with proteins of the FH family and C4b-binding protein (C4BP are discussed in detail. In brief, in this review, we focused on the different mechanisms used by pathogenic E. coli to circumvent complement attack, allowing these bacteria to promote a successful infection.

  14. Pathogenic Escherichia coli in rural household container waters.

    Science.gov (United States)

    Jagals, P; Barnard, T G; Mokoena, M M; Ashbolt, N; Roser, D J

    2013-01-01

    Plastic containers in the range of 5-20 L are widely used - especially in rural African settings - to collect, transport and store water for domestic use, including drinking, bathing and hygiene. The pathogen content of the waters in these containers has not been adequately characterized as yet. This paper presents the primary findings of a synoptic survey of drinking water quality samples from these containers and involved collection of bacterial indicator and pathogenicity gene data. In total, 571 samples of a variety of waters were taken in rural communities in South Africa and the Escherichia coli numbers measured. Of the E. coli positive samples, 46% (n = 148) were screened for the presence of E. coli pathogen gene markers. Though synoptic, the survey provided many insights into the issues that drove the study. Container use markedly degraded water quality as judged by indicator counts, even where improved water supply services were in place. Household container use also appeared to promote regrowth or contamination of containers with pathogenic E. coli strains. Polymerase chain reaction (PCR) analysis also showed that the diversity of potential pathogenic E. coli carrying virulence genes was great. All seven genes screened for (Ial, Stx1, Stx2, EaeA, Eagg, ST, LT) were found in the waters, alone or as mixtures (number of different combinations = 31) including those characteristic of the more dangerous invasive and haemorrhagic E. coli strains. Given the central role of containers in the management of water supply to rural communities, it is clear the microbiology of these waters requires much further characterization.

  15. Longitudinal characterization of Escherichia coli in healthy captive nonhuman primates

    Directory of Open Access Journals (Sweden)

    Jonathan B Clayton

    2014-11-01

    Full Text Available The gastrointestinal (GI tracts of nonhuman primates are well known to harbor Escherichia coli, a known commensal of humans and animals. While E. coli is a normal inhabitant of the mammalian gut, it also exists in a number of pathogenic forms or pathotypes, including those with predisposition for the GI tract, as well the urogenital tract. Diarrhea in captive nonhuman primates (NHPs has long been a problem in both zoo settings and research colonies, including the Como Zoo. It is an animal welfare concern, as well as a public health concern. E. coli has not been extensively studied in correlation with diarrhea in captive primates; therefore, a study was performed during the summer of 2009 in collaboration with a zoo in Saint Paul, MN, which was experiencing an increased incidence and severity of diarrhea among their NHP collection. Fresh fecal samples were collected weekly from each member of the primate collection, between June and August of 2009, and E. coli were isolated. A total of 33 individuals were included in the study, representing eight species. E. coli isolates were examined for their genetic relatedness, phylogenetic relationships, plasmid replicon types, virulence gene profiles, and antimicrobial susceptibility profiles. A number of isolates were identified containing virulence genes commonly found in several different E. coli pathotypes, and there was evidence of clonal transmission of isolates between animals and over time. Overall, the manifestation of chronic diarrhea in the Como Zoo primate collection is a complex problem whose solution will require regular screening for microbial agents and consideration of environmental causes. This study provides some insight towards the sharing of enteric bacteria between such animals.

  16. Deactivation of Escherichia coli by the plasma needle

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-06-07

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

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

    Science.gov (United States)

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

    2012-06-01

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

  18. Persistence of colicinogenic Escherichia coli in the mouse gastrointestinal tract

    Directory of Open Access Journals (Sweden)

    Giladi Itamar

    2009-08-01

    Full Text Available Abstract Background The ability of a bacterial strain to competitively exclude or displace other strains can be attributed to the production of narrow spectrum antimicrobials, the bacteriocins. In an attempt to evaluate the importance of bacteriocin production for Escherichia coli strain residence in the gastrointestinal tract, a murine model experimental evolution study was undertaken. Results Six colicin-producing, yet otherwise isogenic, E. coli strains were administered and established in the large intestine of streptomycin-treated mice. The strains' persistence, population density, and doubling time were monitored over a period of 112 days. Early in the experiment only minor differences in population density between the various colicin-producing and the non-producing control strains were detected. However, over time, the density of the control strains plummeted, while that of the colicin-producing strains remained significantly higher (F(7,66 = 2.317; P Conclusion The data presented here support prior claims that bacteriocin production may play a significant role in the colonization of E. coli in the gastrointestinal tract. Further, this study suggests that the ability to produce bacteriocins may prove to be a critical factor in determining the success of establishing probiotic E. coli in the gastrointestinal tract of humans and animals.

  19. Marine macroalgae as a source for osmoprotection for Escherichia coli.

    Science.gov (United States)

    Ghoul, M; Minet, J; Bernard, T; Dupray, E; Cormier, M

    1995-09-01

    At elevated osmolarity of the mineral medium M63, marine macroalgae constitute important osmoprotectants and nutrients sources for Escherichia coli. Growth of bacterial population (16 strains) was improved by supplementing M63 salts medium with either aqueous or ethanolic algal extracts obtained from Ascophyllum nodosum, Fucus serratus, Enteromorpha ramulosa, Ulva lactuca, and Palmaria palmata. In their presence, growth was still observed even at 1.02 M NaCl. Furthermore, the E. coli ZB400 growth in presence of whole macroalgae thalli in M63/0.85 M NaCI reached its maximum within 24 h (5 × 10(7) - 5 × 10(8) colony-forming units [CFU] per milliliter). In the presence of A. nodosum, bacterial growth was inhibited. In the same experimental conditions, ethanolic extracts improved E. coli growth significantly, because the yield reached 10(11) CFU per milliliter. Ulva lactuca and P. palmata allowed the better growth. The Dragendorff-positive compounds extracted from bacterial cells growing on each ethanolic extract exhibited an osmoprotective effect as proved by a disk-diffusion assay. On the other hand, the -onium compounds (quaternary ammonium [betaines] and tertiary sulphonium) and total free amino acid contents of U. lactuca ethanolic extracts were higher than in others. Fucaceae extracts demonstrated especially high protein content. Algal extracts constitute not only an appreciable osmoprotection source for E. coli but also nutrient sources.

  20. Copper import in Escherichia coli by the yersiniabactin metallophore system.

    Science.gov (United States)

    Koh, Eun-Ik; Robinson, Anne E; Bandara, Nilantha; Rogers, Buck E; Henderson, Jeffrey P

    2017-09-01

    Copper plays a dual role as a nutrient and a toxin during bacterial infections. While uropathogenic Escherichia coli (UPEC) strains can use the copper-binding metallophore yersiniabactin (Ybt) to resist copper toxicity, Ybt also converts bioavailable copper to Cu(II)-Ybt in low-copper conditions. Although E. coli have long been considered to lack a copper import pathway, we observed Ybt-mediated copper import in UPEC using canonical Fe(III)-Ybt transport proteins. UPEC removed copper from Cu(II)-Ybt with subsequent re-export of metal-free Ybt to the extracellular space. Copper released through this process became available to an E. coli cuproenzyme (the amine oxidase TynA), linking this import pathway to a nutrient acquisition function. Ybt-expressing E. coli thus engage in nutritional passivation, a strategy of minimizing a metal ion's toxicity while preserving its nutritional availability. Copper acquisition through this process may contribute to the marked virulence defect of Ybt-transport-deficient UPEC.