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Sample records for bacteriuria escherichia coli

  1. 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...

  2. Escherichia coli bacteriuria in female adults is associated with the development of hypertension

    NARCIS (Netherlands)

    Meiland, Ruby; Geerlings, Suzanne E.; Stolk, Ronald P.; Hoepelman, Andy I.; Peeters, Petra H.; Coenjaerts, Frank E.; Grobbee, Diederik E.

    2010-01-01

    Objective: To investigate whether Escherichia coli bacteriuria is associated with the development of hypertension during a long-term follow-up. Methods: A prospective cohort study was performed among the participants of two population-based studies. Between 1974 and 1986 all women aged 39 to 68 year

  3. Virulence Potential of Escherichia coli Strains Causing Asymptomatic Bacteriuria during Pregnancy ▿

    Science.gov (United States)

    Lavigne, Jean-Philippe; Boutet-Dubois, Adeline; Laouini, Dorsaf; Combescure, Christophe; Bouziges, Nicole; Marès, Pierre; Sotto, Albert

    2011-01-01

    We compared the virulence properties of a collection of asymptomatic bacteriuria (ABU) Escherichia coli strains to urinary tract infection (UTI) strains isolated from pregnant women in a university hospital over 1 year. The in vitro and in vivo studies suggest that ABU strains presented a virulence behavior similar to that of strains isolated from cases of cystitis. PMID:21918033

  4. Virulence potential of Escherichia coli strains causing asymptomatic bacteriuria during pregnancy.

    Science.gov (United States)

    Lavigne, Jean-Philippe; Boutet-Dubois, Adeline; Laouini, Dorsaf; Combescure, Christophe; Bouziges, Nicole; Marès, Pierre; Sotto, Albert

    2011-11-01

    We compared the virulence properties of a collection of asymptomatic bacteriuria (ABU) Escherichia coli strains to urinary tract infection (UTI) strains isolated from pregnant women in a university hospital over 1 year. The in vitro and in vivo studies suggest that ABU strains presented a virulence behavior similar to that of strains isolated from cases of cystitis.

  5. Virulence Potential of Escherichia coli Strains Causing Asymptomatic Bacteriuria during Pregnancy ▿

    OpenAIRE

    Lavigne, Jean-Philippe; Boutet-Dubois, Adeline; Laouini, Dorsaf; Combescure, Christophe; Bouziges, Nicole; Marès, Pierre; Sotto, Albert

    2011-01-01

    We compared the virulence properties of a collection of asymptomatic bacteriuria (ABU) Escherichia coli strains to urinary tract infection (UTI) strains isolated from pregnant women in a university hospital over 1 year. The in vitro and in vivo studies suggest that ABU strains presented a virulence behavior similar to that of strains isolated from cases of cystitis.

  6. Transcriptomics and adaptive genomics of the asymptomatic bacteriuria Escherichia coli strain 83972

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Seshasayee, Aswin S.; Ussery, David

    2008-01-01

    Escherichia coli strains are the major cause of urinary tract infections in humans. Such strains can be divided into virulent, UPEC strains causing symptomatic infections, and asymptomatic, commensal-like strains causing asymptomatic bacteriuria, ABU. The best-characterized ABU strain is strain....... Strain 83972 is a deconstructed pathogen rather than a commensal strain that has acquired fitness properties....

  7. Escherichia coli Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Properties

    DEFF Research Database (Denmark)

    Watts, Rebecca E; Hancock, Viktoria; Ong, Cheryl-lynn Y

    2010-01-01

    Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli being responsible for >80% of all cases. Asymptomatic bacteriuria (ABU) occurs when bacteria colonize the urinary tract without causing clinical symptoms and can affect both catheterized...

  8. 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...

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    The molecular mechanisms that define asymptomatic bacteriuria (ABU) Escherichia coli colonization of the human urinary tract remain to be properly elucidated. Here, we utilize ABU E. coli strain 83972 as a model to dissect the contribution of siderophores to iron acquisition, growth, fitness, and...... receptor mutant was outcompeted by 83972 in human urine and the mouse urinary tract, indicating a role for catecholate receptors in urinary tract colonization....

  10. 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...

  11. Identification of Genes Important for Growth of Asymptomatic Bacteriuria Escherichia coli in Urine

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; de Evgrafov, Mari Cristina Rodriguez; Phan, Minh Duy;

    2012-01-01

    reduced competitive advantage in the bladder and/or kidney during coinoculation experiments with the parent strain, whereas 83972metE and 83972ilvC did not. Taken together, our data have identified several biosynthesis pathways as new important fitness factors associated with the growth of ABU E. coli......Escherichia coli is the most important etiological agent of urinary tract infections (UTIs). Unlike uropathogenic E. coli, which causes symptomatic infections, asymptomatic bacteriuria (ABU) E. coli strains typically lack essential virulence factors and colonize the bladder in the absence...... of symptoms. While ABU E. coli can persist in the bladder for long periods of time, little is known about the genetic determinants required for its growth and fitness in urine. To identify such genes, we have employed a transposon mutagenesis approach using the prototypic ABU E. coli strain 83972...

  12. Global gene expression profiling of the asymptomatic bacteriuria Escherichia coli strain 83972 in the human urinary tract

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Klemm, Per

    2006-01-01

    long-term bladder colonization. The strain has been used for prophylactic purposes in patients prone to more severe and recurrent UTIs. For this study, we used DNA microarrays to monitor the expression profile of strain 83972 in the human urinary tract. Significant differences in expression levels were......Urinary tract infections (UTIs) are an important health problem worldwide, with many million cases each year. Escherichia coli is the most common organism causing UTIs in humans. The asymptomatic bacteriuria E. coli strain 83972 is an excellent colonizer of the human urinary tract, where it causes...

  13. Global gene expression profiling of asymptomatic bacteriuria Escherichia coli during biofilm growth in human urine

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Klemm, Per

    2007-01-01

    asymptomatic bacteriuria (ABU) E. coli strains 83972 and VR50 are significantly better biofilm formers in their natural growth medium, human urine, than the two uropathogenic E. coli isolates CFT073 and 536. We used DNA microarrays to monitor the expression profile during biofilm growth in urine of the two ABU...... strains 83972 and VR50. Significant differences in expression levels were seen between the biofilm expression profiles of the two strains with the corresponding planktonic expression profiles in morpholinepropanesulfonic acid minimal laboratory medium and human urine; 417 and 355 genes were up- and down...... versions of 83972 and VR50; all mutants showed reduced biofilm formation in urine by 18 to 43% compared with the wild type (P profile of strain 83972 in the human urinary tract partially overlaps with the biofilm expression profile....

  14. Biofilm-Exclusion of Uropathogenic Bacteria by Selected Asymptomatic Bacteriuria Escherichia Coli Strains

    DEFF Research Database (Denmark)

    Ferriéres, L.; Hancock, Viktoria; Klemm, Per

    2007-01-01

    . In contrast to uropathogenic E coli (UPEC), which cause symptomatic urinary tract infection, asymptomatic bacteriuria (ABU) strains are associated with essentially symptom-free infections. Here the biofilm-forming capacity on abiotic surfaces of selected E coli ABU strains and UPEC strains in human urine...... was investigated. It was found that there is a strong bias for biofilm formation by the ABU strains. Not only were the ABU strains significantly better biofilm formers than UPEC strains, they were also able to out-compete UPEC strains as well as uropathogenic strains of Klebsiella spp. during biofilm formation....... The results support the notion of bacterial prophylaxis employing selected ABU strains to eliminate UPEC strains and other pathogens in patients prone to recalcitrant infections....

  15. Predictive value of Escherichia coli susceptibility in strains causing asymptomatic bacteriuria for women with recurrent symptomatic urinary tract infections receiving prophylaxis.

    Science.gov (United States)

    Beerepoot, M A J; den Heijer, C D J; Penders, J; Prins, J M; Stobberingh, E E; Geerlings, S E

    2012-04-01

    A significant proportion of women develop a recurrence following an initial urinary tract infection (UTI). In women with recurrent UTI, the predictive value of asymptomatic bacteriuria (ASB) for the development of a subsequent UTI has not yet been established and it is not known whether information from an asymptomatic sample is useful in guiding antimicrobial therapy. To address these questions, we used data that originated from the 'Non-antibiotic prophylaxis for recurrent urinary tract infections' (NAPRUTI) study: two randomized controlled trials on the prevention of recurrent UTI in non-hospitalized premenopausal and postmenopausal women (n=445). During 15months of follow-up, no difference was observed in the time to a subsequent UTI between women with and without ASB at baseline (hazard ratio: 1.07, 95% CI 0.80-1.42). The antimicrobial susceptibility and pulsed-field gel-electrophoresis (PFGE) pattern of 50 Escherichia coli strains causing a UTI were compared with those of the ASB strain isolated 1month previously. The predictive values of the susceptibility pattern of the ASB strain, based on resistance prevalence at baseline, were ≥76%, except in the case of nitrofurantoin- and amoxicillin-clavulanic acid-resistance. Asymptomatic and symptomatic isolates had similar PFGE patterns in 70% (35/50) of the patients. In the present study among women with recurrent UTI receiving prophylaxis, ASB was not predictive for the development of a UTI. However, the susceptibility pattern of E. coli strains isolated in the month before a symptomatic E. coli UTI can be used to make informed choices for empirical antibiotic treatment in this patient population.

  16. Molecular Analysis of Asymptomatic Bacteriuria Escherichia coli Strain VR50 Reveals Adaptation to the Urinary Tract by Gene Acquisition

    DEFF Research Database (Denmark)

    Beatson, Scott A.; Ben Zakour, Nouri L.; Totsika, Makrina;

    2015-01-01

    to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afa and VR50afaE displayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheV mutant. Our study suggests that E. coli VR50 is a commensal-like strain that has acquired...

  17. Genomic analysis of a pathogenicity island in uropathogenic Escherichia coli CFT073: distribution of homologous sequences among isolates from patients with pyelonephritis, cystitis, and Catheter-associated bacteriuria and from fecal samples.

    Science.gov (United States)

    Guyer, D M; Kao, J S; Mobley, H L

    1998-09-01

    Urinary tract infection is the most frequently diagnosed kidney and urologic disease and Escherichia coli is by far the most common etiologic agent. Uropathogenic strains have been shown to contain blocks of DNA termed pathogenicity islands (PAIs) which contribute to their virulence. We have defined one of these regions of DNA within the chromosome of a highly virulent E. coli strain, CFT073, isolated from the blood and urine of a woman with acute pyelonephritis. The 57,988-bp stretch of DNA has characteristics which define PAIs, including a size greater than 30 kb, the presence of insertion sequences, distinct segmentation of K-12 and J96 origin, GC content (42.9%) different from that of total genomic DNA (50.8%), and the presence of virulence genes (hly and pap). Within this region, we have identified 44 open reading frames; of these 44, 10 are homologous to entries in the complete K-12 genome sequence, 4 are nearly identical to the sequences of E. coli J96 encoding the HlyA hemolysin, 11 encode P fimbriae, and 19 show no homology to J96 or K-12 entries. To determine whether sequences found within the junctions of the PAI of CFT073 were common to other uropathogenic strains of E. coli, 11 probes were isolated along the length of the PAI and were hybridized to dot blots of genomic DNA isolated from clinical isolates (67 from patients with acute pyelonephritis, 38 from patients with cystitis, 49 from patients with catheter-associated bacteriuria, and 27 from fecal samples). These sequences were found significantly more often in strains associated with the clinical syndromes of acute pyelonephritis (79%) and cystitis (82%) than in those associated with catheter-associated bacteriuria (58%) and in fecal strains (22%) (P < 0.001). From these regions, we have identified a putative iron transport system and genes other than hly and pap that may contribute to the virulent phenotype of uropathogenic E. coli strains.

  18. 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…

  19. Asymptomatic bacteriuria Escherichia coli strain 83972 carries mutations in the foc locus and is unable to express F1C fimbriae

    DEFF Research Database (Denmark)

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

    2006-01-01

    this adhesin. The data imply that E. coli 83972 has lost its ability to express this important colonization factor as a result of host-driven evolution. The ancestor of the strain seems to have been a pyelonephritis strain of phylogenetic group B2. Strain 83972 therefore represents an example of bacterial...

  20. BACTERIURIA IN PREGNANCY: A REVIEW OF LITERATURE

    Directory of Open Access Journals (Sweden)

    S. L. B. Souza

    2015-06-01

    Full Text Available The alteration Structural and functional of the urinary system appear as a predisposing factor from pregnant population to urinary tract infections. The bacteriuria in pregnancy still be one of the principal factor of morbidity and mortality, maternal and perinatal. Thus, proposing to analyze the bibliographic production around bacteriuria in pregnancy has developed this study. Proceded to the investigation of 06 national articles, published from 2003 to 2013, on the LILACS database. Were used as descriptors: Bacteriuria and Pregnancy. Defined as bacteriuria from quantitative colony forming units per mililiter of urine (CFU / ml equal to or higher than 105. With etiology is observed Escherichia coli as a major etiologic agent and urine culture the most efficient diagnostic method. The results also attach the treatment of bacteriuria during pregnancy independently of the occurrence of symptoms and tracking of the bacteriuria from the first trimester of pregnancy to prevent maternal and fetal complications.

  1. Asymptomatic bacteriuria among pregnant women

    Directory of Open Access Journals (Sweden)

    Paul Erhunmwunse Imade

    2010-06-01

    Full Text Available Background: Asymptomatic bacteriuria is the significant presence of bacteria in the urine of an individual without symptoms. In pregnancy, the apparent reduction in immunity of pregnant women tends to encourage the growth of pathogens. Aim: This study was carried out to determine the prevalence of asymptomatic bacteriuria in pregnant women attending a primary health centre in Benin City, Nigeria. Materials and Methods: A total of 1,228 pregnant women were recruited for this study. All subjects were clinically identified to have no signs and symptoms of UTI. Clean catch midstream urine sample was collected from each patient into sterile universal container. The urine samples were examined microscopically and by cultural method. Identification of isolates was by standard microbiological technique. Result: A total of 556 (45.3% were positive for significant bacteriuria. There was a significant difference in the prevalence of asymptomatic bacteriuria with respect to age (P < 0.0001. Trimester did not show any significant difference (P = 0.2006 in the prevalence of asymptomatic bacteriuria. Escherichia coli was the most predominant organism followed closely by Staphylococcus aureus. Ciprofloxacin, Ceftriaxone and Augmentin were found to be the most effective antibiotics against the urinary isolates. Conclusion: Asymptomatic bacteriuria is not uncommon among antenatal patients in the population studied. Routine urine cultural test should be carried out on all antenatal patients in order to identify any unsuspecting infection. This measure will go a long way in reducing maternal and obstetric complications associated with pregnancy.

  2. Asymptomatic bacteriuria among pregnant women

    Directory of Open Access Journals (Sweden)

    Paul Erhunmwunse Imade

    2010-01-01

    Full Text Available Background: Asymptomatic bacteriuria is the significant presence of bacteria in the urine of an individual without symptoms. In pregnancy, the apparent reduction in immunity of pregnant women tends to encourage the growth of pathogens. Aim : This study was carried out to determine the prevalence of asymptomatic bacteriuria in pregnant women attending a primary health centre in Benin City, Nigeria. Materials and Methods: A total of 1,228 pregnant women were recruited for this study. All subjects were clinically identified to have no signs and symptoms of UTI. Clean catch midstream urine sample was collected from each patient into sterile universal container. The urine samples were examined microscopically and by cultural method. Identification of isolates was by standard microbiological technique. Result: A total of 556 (45.3% were positive for significant bacteriuria. There was a significant difference in the prevalence of asymptomatic bacteriuria with respect to age (P < 0.0001. Trimester did not show any significant difference (P = 0.2006 in the prevalence of asymptomatic bacteriuria. Escherichia coli was the most predominant organism followed closely by Staphylococcus aureus. Ciprofloxacin, Ceftriaxone and Augmentin were found to be the most effective antibiotics against the urinary isolates. Conclusion : Asymptomatic bacteriuria is not uncommon among antenatal patients in the population studied. Routine urine cultural test should be carried out on all antenatal patients in order to identify any unsuspecting infection. This measure will go a long way in reducing maternal and obstetric complications associated with pregnancy.

  3. PATHOGENIC ESCHERICHIA COLI

    Science.gov (United States)

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

  4. 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.

  5. Zoonotic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Wasteson Yngvild

    2002-03-01

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

  6. PART I. ESCHERICHIA COLI

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    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. 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...

  8. Taxonomy Icon Data: Escherichia coli [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available cherichia_coli_S.png Escherichia_coli_NS.png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Escherichia+co...li&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Escherichia+coli&t=NL http://biosciencedbc.jp/taxonomy..._icon/icon.cgi?i=Escherichia+coli&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Escherichia+coli&t=NS ...

  9. Characterization of adhesion associated surface properties of uropathogenic Escherichia coli.

    Science.gov (United States)

    Bartková, G; Ciznár, I; Lehotská, V; Kernová, T

    1994-01-01

    Escherichia coli was isolated from the urine of patients with pyelonephritis, with urinary tract infections other than pyelonephritis and with asymptomatic bacteriuria. Surface properties of the strains were analyzed by the salting-out aggregation test (SAT), hydrophobic interaction chromatography (HIC), Congo red binding (Crb), agglutination of erythrocytes (MRHA) and latex particles covered by digalactoside (PF) and by adherence to tissue culture cells. In addition, a DNA probe for the pap gene was used. The DNA probe detected the highest proportion of strains with pap gene in the group of patients with pyelonephritis, lower in the urinary tract infections other than pyelonephritis and the lowest in the group with asymptomatic bacteriuria. Tests for P-fimbriae (PF, MRHA) showed a similar distribution. Hydrophobicity measured by SAT and by HIC did not show differences among the tested groups of strains. The results suggest that factors other than the P-fimbriae and hydrophobicity may contribute to the persistence of E. coli in the urinary tract.

  10. ASYMPTOMATIC BACTERIURIA AND PYURIA IN PREGNANCY

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    M Rahimkhani

    2008-11-01

    Full Text Available "nPregnant women are at increased risk for urinary tract infection (UTI but in many cases infection is asymptomatic. This study was performed to determine the incidence of asymptomatic bacteriuria and pyuria in pregnant women. A total of 86 pregnant women during first trimester and 56 nonpregnant women were evaluated. All subjects were clinically identified to have no signs and symptoms of UTI. Clean catch midstream urine samples were collected for both groups. Urine samples were examined microscopically and were cultured. Bacteriological examination revealed asymptomatic bacteriuria in 25 (29.1% and 3 (5.4% of the study group and controls, respectively (P < 0.05. Microscopic analysis of urine revealed pyuria in 18 (20.9% and 3 (5.4% of the study group and controls, respectively (P < 0.05. In study group, Escherichia coli were found in 20%, Staphylococcus epidermidis in 36%, Staphylococcus haemolyticus in 12%, streptococcus group D in 12%, Staphylococcus saprophyticus in 12% and Proteus mirabilis in 8%. In control group, E. coli were found in 33.3% and S. epidermidis in 66.7%. Our results show that the incidence of asymptomatic bacteriuria is significantly higher in pregnant women than nonpregnant women. The main finding in the present study was that 29.1% of the pregnant women who were in first trimester had asymptomatic bacteriuria which is much higher than figures reported from other countries. The use of microscopic urinanalysis was not an effective method of detecting asymptomatic bacteriuria and urine culture is necessary for screening these pregnant women.

  11. Biofilm formation by asymptomatic and virulent urinary tract infectious Escherichia coli strains

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Ferrieres, Lionel; Klemm, Per

    2007-01-01

    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. In contrast to uropathogenic E. coli (UPEC) that cause symptomatic urinary tract infection, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we...... have investigated the biofilm-forming capacity on abiotic surfaces of groups of ABU strains and UPEC strains in human urine. We found that there is a strong bias; ABU strains were significantly better biofilm formers than UPEC strains. Our data suggest that biofilm formation in urinary tract infectious...

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

    Science.gov (United States)

    Shih, Cheng-Min; Chang, Chia-Ling; Hsu, Min-Yen; Lin, Jyun-Yu; Kuan, Chen-Meng; Wang, Hsi-Kai; Huang, Chun-Te; Chung, Mu-Chi; Huang, Kui-Chou; Hsu, Cheng-En; Wang, Chun-Yuan; Shen, Ying-Cheng; Cheng, Chao-Min

    2015-12-01

    Escherichia coli is a generic indicator of fecal contamination, and certain serotypes cause food- and water-borne illness such as O157:H7. In the clinic, detection of bacteriuria, which is often due to E. coli, is critical before certain surgical procedures or in cases of nosocomial infection to prevent further adverse events such as postoperative infection or sepsis. In low- and middle-income countries, where insufficient equipment and facilities preclude modern methods of detection, a simple, low-cost diagnostic device to detect E. coli in water and in the clinic will have significant impact. We have developed a simple paper-based colorimetric platform to detect E. coli contamination in 5h. On this platform, the mean color intensity for samples with 10(5)cells/mL is 0.118±0.002 (n=4), and 0.0145±0.003 (Ppaper-based ELISA is an innovative point-of-care diagnostic tool to rapidly detect E. coli, and possibly other pathogens when customized as appropriate, especially in areas that lack advanced clinical equipment.

  13. Shiga Toxin Producing Escherichia coli.

    Science.gov (United States)

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

    2015-06-01

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

  14. Megalocytic interstitial nephritis following acute pyelonephritis with Escherichia coli bacteremia: a case report.

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    Kwon, Hee Jin; Yoo, Kwai Han; Kim, In Young; Lee, Seulkee; Jang, Hye Ryoun; Kwon, Ghee Young

    2015-01-01

    Megalocytic interstitial nephritis is a rare form of kidney disease caused by chronic inflammation. We report a case of megalocytic interstitial nephritis occurring in a 45-yrold woman who presented with oliguric acute kidney injury and acute pyelonephritis accompanied by Escherichia coli bacteremia. Her renal function was not recovered despite adequate duration of susceptible antibiotic treatment, accompanied by negative conversion of bacteremia and bacteriuria. Kidney biopsy revealed an infiltration of numerous histiocytes without Michaelis-Gutmann bodies. The patient's renal function was markedly improved after short-term treatment with high-dose steroid.

  15. Clinical isolates of uropathogenic Escherichia coli ST131 producing NDM-7 metallo-β-lactamase in China.

    Science.gov (United States)

    Wang, Lian-Hui; Liu, Pan-Pan; Wei, Dan-Dan; Liu, Yang; Wan, La-Gen; Xiang, Tian-Xin; Zhang, Yu-Juan

    2016-07-01

    Here we report five cases of NDM-7-producing Escherichia coli from patients with bacteriuria in a teaching hospital in mainland China. Two isolates belonged to sequence type 131 (ST131), simultaneously carrying blaCTX-M-15, blaSHV-11, blaTEM-1 and qnrS1. The blaNDM-7 gene was located on a conjugative IncX3-type plasmid bearing blaTEM-1 and qnrS1. These findings indicate the spread of NDM-7 metallo-β-lactamase in a highly resistant and virulent E. coli sequence type in China.

  16. Asymptomatic bacteriuria among pregnant women

    Directory of Open Access Journals (Sweden)

    Sudha Biradar Kerure

    2013-04-01

    Full Text Available Background: Urinary tract infections (UTIs are the most common bacterial infections during pregnancy. Asymptomatic bacteriuria (ASB is a major risk factor for the development of urinary tract infections during pregnancy and with further risk of preterm birth & pyelonephritis if untreated. Aims & Objectives: This study was carried out to determine the prevalence of asymptomatic bacteriuria (ASB in pregnant women & to isolate, identify and establish antimicrobial susceptibility of pathogens. Methods: A total of 500 pregnant women were studied over a period of one year. Clean catch midstream urine sample was collected into a sterile container & then subjected to culture method. Results: Significant bacteriuria was noted in 45 patients (9%. 3% patients had insignificant bacteriuria. Growth of contaminants was noted in 8%. 80% samples were sterile with no growth. E. coli was the most common etiological agent, followed by Staphylococcus aureus. Conclusions: Asymptomatic bacteriuria is not uncommon in antenatal patients. All pregnant women should be screened by urine culture to detect asymptomatic bacteriuria at their first visit to prevent overt UTI & other complications in both mother & fetus. [Int J Reprod Contracept Obstet Gynecol 2013; 2(2.000: 213-216

  17. ASYMPTOMATIC BACTERIURIA AMONG PREGNANT WOMEN ATTENDING THE OUTPATIENT CLINIC OF CHITWAN MEDICAL COLLEGE TEACHING HOSPITAL, CHITWAN, NEPAL

    Directory of Open Access Journals (Sweden)

    Mamata Sharma Neupane

    2012-11-01

    Full Text Available Urinary Tract Infection (UTI refers to both microbial colonization of the urine and tissue invasion of any structure of the urinary tract. Pregnancy enhances the progression from asymptomatic to symptomatic bacteriuria which could lead to pyelonephritis and adverse obstetric outcomes such as prematurity, low-birth weight, and higher fetal mortality rates. This study was undertaken to determine the prevalence of asymptomatic bacteriuria in pregnancy; its causative agents and their antimicrobial susceptibility pattern, and also to determine the relationship between asymptomatic bacteriuria and pyuria. The total number of participants who finished the study was 392. The mean age of the participants was 29.76 ± 6.71(range, 21-37 years. Of the 392 urine specimens processed, 102 (26.0% showed significant bacteriuria. The commonest organism causing bacteriuria was Escherichia coli. The sensitivity pattern of the isolated organisms revealed that all were sensitive to ciprofloxacin and gentamicin at very high percentage. 200 (51.5% women had more than 5 pus cells in urine specimens from which 50 (12.75% had positive cultures. Women with higher number of pus cells in urine specimen had significantly higher asymptomatic bacteriuria (p < 0.0001.In conclusion, screening of bacteriuria in pregnancy and proper treatment must be considered as an essential part of antenatal care in Nepalese community. To prevent asymptomatic bacteriuria complications, all pregnant women should be screened at the first antenatal visit. A negative test for pyuria is not a reliable indicator of the absence of asymptomatic bacteriuria in pregnant women.

  18. Intestinal population dynamics of UTI-causing Escherichia coli within heterosexual couples.

    Science.gov (United States)

    Manges, Amee R; Johnson, James R; Riley, Lee W

    2004-09-01

    From October 1999 to July 2001, a prospective cohort study was conducted to assess the intestinal Escherichia coli population dynamics of 23 sexually active couples. We tested the hypothesis that intestinal persistence and predominance of specific E. coli strains, co-colonization of sex partners with the same E. coli strain, and the intestinal diversity of fecal E. coli, contribute to recurrent urinary tract infection (UTI). E. coli isolates causing UTI, asymptomatic bacteriuria (ABU), or intestinal co-colonization were evaluated by ERIC2 PCR and compared with strains recovered exclusively from stool samples with respect to intestinal persistence, predominance, and diversity. Contrary to our hypothesis, UTI-causing strains exhibited similar levels of intestinal persistence and predominance as did fecal strains, and UTI episodes were not associated with shifts in fecal E. coli diversity. In contrast, intestinal co-colonization strains exhibited greater persistence and predominance than did fecal strains and were more likely to cause ABU, and co-colonization episodes were associated with significantly increased fecal E. coli diversity. Nonetheless, intestinal co-colonization strains were not associated with UTI. These findings suggest that E. coli strains involved in co-colonization may be more important contributors to intestinal E. coli dynamics than to UTI pathogenesis.

  19. Structure of Escherichia coli tryptophanase.

    Science.gov (United States)

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

    2006-07-01

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

  20. Structure of Escherichia Coli Tryptophanase

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-01-01

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

  1. Escherichia coli transcriptional regulatory network

    Directory of Open Access Journals (Sweden)

    Agustino Martinez-Antonio

    2011-06-01

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

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. Strategies for Protein Overproduction in Escherichia coli.

    Science.gov (United States)

    Mott, John E.

    1984-01-01

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

  8. 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...

  9. Fosfomycin Resistance in Escherichia coli, Pennsylvania, USA.

    Science.gov (United States)

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

    2015-11-01

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

  10. 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.

  11. 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...

  12. Asymptomatic bacteriuria in children with sickle cell anemia at The University of Nigeria teaching hospital, Enugu, South East, Nigeria

    Directory of Open Access Journals (Sweden)

    Ikefuna Anthony N

    2011-09-01

    Full Text Available Abstract Background Urinary tract infection (UTI is a common cause of childhood morbidity and mortality in the tropics. Children with sickle cell anemia (SCA may have compromised kidney function arising from repeated vaso-occlusive episodes and recurrent symptomatic or asymptomatic UTI. Objectives This study aims at determining the prevalence of asymptomatic bacteriuria and sensitivity pattern in children with homozygous sickle haemoglobin compared to children with normal haemoglobin. Methods One hundred children with SCA in stable state and 100 children with normal haemoglobin aged 2-12 years were screened for asymptomatic bacteriuria using midstream urine samples. The samples were incubated aerobically at 37°C for 24 hours within one hour of collection. Children whose urine samples yielded significant bacteriuria (≥105cfu/ml on two consecutive cultures were regarded as having asymptomatic bacteriuria. Results Asymptomatic bacteriuria was noted in 6% of children with SCA and occurred more in females than males (F: M = 5:1 when compared to 2% in children with normal haemoglobin. Escherichia coli was the commonest organism isolated (33.3%. All the organisms were resistant to co-trimoxazole and ampicillin while most were sensitive to gentamicin, ceftriaxone and the quinolones. Conclusion The risk of asymptomatic bacteriuria is three times more common in children with sickle cell anemia than in children with normal haemoglobin. It is therefore important to screen SCA patients, especially the females for UTI and should be treated according to the sensitivity result of the cultured organisms.

  13. PREVALENCE OF ASYMPTOMATIC BACTERIURIA IN PREGNANCY AT A TEACHING HOSPITAL

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    Indira Guntoory

    2016-07-01

    Full Text Available BACKGROUND UTI is the most frequent medical complication. It may be asymptomatic or symptomatic. Asymptomatic bacteriuria if left untreated might result in symptomatic UTI and adverse pregnancy outcomes. AIM This prospective study was aimed to determine the prevalence of Asymptomatic bacteriuria of pregnancy among antenatal women attending the antenatal clinic in the Department of Obstetrics and Gynaecology, Maharajah’s Institute of Medical Sciences, Nellimarla, Vizianagaram District, Andhra Pradesh. MATERIAL AND METHODS After taking approval from Institutional Ethics Committee and informed written consent from patients, urine samples were collected from antenatal women in their first antenatal visit. A clean catch midstream specimen of urine was collected and inoculated on blood agar and MacConkey’s agar. It was incubated aerobically at 37 degrees centigrade overnight. Isolates were identified up to species level using standard protocol and sensitivity to different antibiotics is tested. Results were analysed statistically and a P value of less than 0.05 was taken as significant. RESULTS A total of 173 samples were screened; 154 women showed no growth on culture; 19 women had significant bacteriuria with a prevalence rate of 10.98%; 15 women in the age group of 18-25 years and 4 women in the age group of 26-35 years had significant bacteriuria; 83 women were multiparous and 11 (57.89% women in this group had significant bacteriuria, while only 8 (42.1% out of 90 women in the nulliparous group had significant bacteriuria. With respect to trimester, 10 (52.63% out of 19 culture positive cases were in second trimester. In our study, the organisms isolated were Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. The bacteria grown were most sensitive to Ampicillin+Sulbactam (68%, Nitrofurantoin (73%, Amikacin (84% and Meropenem (100%. CONCLUSION It is therefore essential to screen every antenatal women for asymptomatic

  14. Asymptomatic bacteriuria in antenatal women

    Directory of Open Access Journals (Sweden)

    Lavanya S

    2002-01-01

    Full Text Available A total of 500 antenatal women in their first or second trimesters were screened over a period of 2 years for asymptomatic bacteriuria. Out of them, 8.4% (42 were culture positive. A control group of 100 non-pregnant women, both married and unmarried, was also simultaneously screened. The control group yielded an overall culture positivity of 3% (4% in the married non-pregnant women and 2% in the unmarried women. Primigravida had highest percent culture positivity of 66.6%. The incidence was higher in less than 20 years age group i.e. 71.42%. Of the screening tests, Gram stained smear when compared with the standard loop method, showed the highest sensitivity of 95.2%. The specificity of the screening tests was high [Gram stained smear (98.6%, catalase test (97.1% and pus cell count(96.5%]. Escherichia coli was the most common organism isolated in the test and control groups. The organisms were sensitive to cephalexin, nitrofurantoin, amoxycillin and norfloxacin in decreasing order. Incidence of prematurity was 75% and that of low birth weight was 50% in untreated patients.

  15. Native valve Escherichia coli endocarditis following urosepsis.

    Science.gov (United States)

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

    2013-05-01

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

  16. 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,...

  17. 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...

  18. 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...

  19. 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.…

  20. 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...

  1. 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...

  2. 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....

  3. Compaction of isolated Escherichia coli nucleoids

    NARCIS (Netherlands)

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

    2016-01-01

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

  4. Escherichia coli in Europe: An Overview

    Directory of Open Access Journals (Sweden)

    Nerino Allocati

    2013-11-01

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

  5. Pathogenomics of uropathogenic Escherichia coli

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    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.

  6. Survival of Escherichia coli in stormwater biofilters.

    Science.gov (United States)

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

    2014-04-01

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

  7. The evolution of the Escherichia coli phylogeny.

    Science.gov (United States)

    Chaudhuri, Roy R; Henderson, Ian R

    2012-03-01

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

  8. Comparison of the serum sensitivity of uropathogenic strains of Escherichia coli isolated from different diagnostic groups

    Directory of Open Access Journals (Sweden)

    J. Vraneš,

    2005-02-01

    Full Text Available The bactericidal activity of serum caused by complement system is an important defence mechanism protecting the host organism against infection. The capacity to resist bactericidal activity of normal human serum contributes to the virulence of many gram-negative pathogens. Serum resistance in bacteria has been attributed to their surface components, but exact mechanism of resistance which most likely involves multiple factors is not well understood. In this study, the capacity of Escherichia coli to resist the bactericidal action of serum was examined in 85 clinical isolates obtained from patients with acute pyelonephritis (n=23, acute cystitis (n=22, chronic pyelonephritis (n=22 and asymptomatic bacteriuria (n=18. Serum sensitivity was also examined in relation to the serogroup specificity and expression of the different adhesins of the strains.Bacterial susceptibility to serum killing was measured by assessing regrowth after incubation in serum according to Schiller and Hatch method. The adhesins of E. coli were determined by hemagglutination and inhibition of hemagglutiation, and serotyping was performed on glass slides and confirmed using a mechanized microtechnique.The significant correlation between serum resistance of uropathogenic strains of E. coli and expression of P-fimbriae and O6 serogroup was observed.Theincidence of serum-resistant E. coli strains was significantly higher in strains isolated from urine of patients with acute pyelonephritis, as compared to strains isolated in other diagnostic groups, which is in accordance with higher virulence and invasive potential of these strains.

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

    Directory of Open Access Journals (Sweden)

    Ancuta Mihaela Rotar

    2013-11-01

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

  10. Automatic tracking of Escherichia coli bacteria.

    Science.gov (United States)

    Xie, Jun; Khan, Shahid; Shah, Mubarak

    2008-01-01

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

  11. Homology requirements for recombination in Escherichia coli.

    OpenAIRE

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

    1985-01-01

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

  12. Escherichia coli necrotizing fasciitis in Hirschsprung's disease

    Directory of Open Access Journals (Sweden)

    Manal A. Alsaif

    2015-04-01

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

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

    OpenAIRE

    2003-01-01

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

  14. Siderophore production by uropathogenic Escherichia coli

    Directory of Open Access Journals (Sweden)

    Vagrali Manjula

    2009-01-01

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

  15. Interaction between Escherichia coli and lunar fines

    Science.gov (United States)

    Johansson, K. R.

    1983-01-01

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

  16. 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.

  17. 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...

  18. 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.

  19. Enteropathogenic Escherichia coli: foe or innocent bystander?

    Science.gov (United States)

    Hu, J; Torres, A G

    2015-08-01

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

  20. Escherichia coli fliAZY operon.

    OpenAIRE

    Mytelka, D S; Chamberlin, M J

    1996-01-01

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

  1. Escherichia coli growth under modeled reduced gravity

    Science.gov (United States)

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

    2004-01-01

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

  2. Genes under positive selection in Escherichia coli

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  3. Global gene expression in Escherichia coli biofilms

    DEFF Research Database (Denmark)

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

    2003-01-01

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

  4. 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.

  5. Escherichia coli as a bioreporter in ecotoxicology.

    Science.gov (United States)

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

    2010-11-01

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

  6. Escherichia coli O157:H7.

    Science.gov (United States)

    Mead, P S; Griffin, P M

    1998-10-10

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

  7. Escherichia coli O157 infections and unpasteurised milk

    NARCIS (Netherlands)

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

    2001-01-01

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

  8. 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....

  9. Production of glycoprotein vaccines in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Ihssen Julian

    2010-08-01

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

  10. Prevalence of diarrheagenic Escherichia coli in suckling rabbits

    OpenAIRE

    2016-01-01

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

  11. Methane production from kitchen waste using Escherichia coli.

    Science.gov (United States)

    Jayalakshmi, S; Joseph, Kurian; Sukumaran, V

    2007-04-01

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

  12. Long term effects of Escherichia coli mastitis.

    Science.gov (United States)

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

    2014-07-01

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

  13. Cyclomodulins in urosepsis strains of Escherichia coli.

    Science.gov (United States)

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

    2010-06-01

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

  14. 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...

  15. Transport of Escherichia coli in saturated porous media

    NARCIS (Netherlands)

    Foppen, J.W.A.

    2007-01-01

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

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

    OpenAIRE

    2010-01-01

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

  17. The eclipse period of Escherichia coli

    DEFF Research Database (Denmark)

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

    2000-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  19. The crystal structure Escherichia coli Spy.

    Science.gov (United States)

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

    2010-11-01

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

  20. 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.

  1. Escherichia coli biofilms: Accepting the therapeutic challenges

    Directory of Open Access Journals (Sweden)

    Trupti Bajpai

    2016-01-01

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

  2. Expanding ester biosynthesis in Escherichia coli.

    Science.gov (United States)

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

    2014-04-01

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

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

    OpenAIRE

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

    2014-01-01

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

  4. Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  5. Overexpression of vsr in Escherichia coli is mutagenic.

    Science.gov (United States)

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

    1996-01-01

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

  6. 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.

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

    Science.gov (United States)

    FREIFELDER, D; MAALOE, O

    1964-10-01

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

  8. Etiology and resistance of asymptomatic bacteriuria isolates among school going children in Sanadaj-Iran

    Institute of Scientific and Technical Information of China (English)

    Sofei-Majidpur H; Kalantar E; Verdi F; Khaksar N; Shahsavari S; Beiranvand S

    2008-01-01

    Objective:The objective of this study was to determine the etiology and antimicrobial susceptibility patterns of asymptomatic bacteriuria pathogens isolated among school going children in Sanandaj,Iran.Methods:A total of 1 457 urine samples of 5 to 10 years children from forty different schools of Sanandaj city were screened to see asymptomatic bacteriuria during November 2007 to June 2008.Results:Bacterial colony count of over (105)colony forming units CFU /mL were found in 28 (1.90%)of total cases,with 767 (52.64%)girls and 690 (47.35%)boys.The highest class-specific prevalence was found in the fourth standard (2.8%)and the lowest in the first standard (1.0%).The dominant bacterial isolates were E.coli 20 (74.1%),followed by Klebsiella pneumoniae 04 (14.8%)and Staphylococcus aureus 04 (14.8%).Cefotaxime,Cefixime,Kana-mycin,Co-trimoxazole,nalidicxic acid,nitrofurantoin and Amoxicillin,resistance rates were above 90.0%. Ceftriaxone expressed the highest susceptibility among E.coli isolates.Surprisingly,S.aureus showed 100. 0% resistance to oxacillin.Conclusion:In the present study in which Escherichia coli is the most frequently incriminated as the causative agents.The results show a very serious antibiotic resistance of E.coli isolated. Surveillance and monitoring studies will be essential in preventing of renal scarring or other abnormalities.

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-01-01

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

  11. 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...

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

    Science.gov (United States)

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

  13. {sup 99m}Technetium labelled Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Matthew Stratton

    2015-01-01

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

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

    OpenAIRE

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

    2004-01-01

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

  16. 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.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  18. Free RNA polymerase in Escherichia coli.

    Science.gov (United States)

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

    2015-12-01

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

  19. 77 FR 31975 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Science.gov (United States)

    2012-05-31

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

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

    Directory of Open Access Journals (Sweden)

    C. P. Sousa

    2006-01-01

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

  1. 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.

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

    Institute of Scientific and Technical Information of China (English)

    XI Haiyan; CAI Qiang; HE Miao; SHI Hanchang

    2007-01-01

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

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

    OpenAIRE

    1985-01-01

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

  4. Prevalence and outcome of asymptomatic bacteriuria in early pregnancy

    Directory of Open Access Journals (Sweden)

    Sreekumary Radha

    2016-12-01

    Full Text Available Background: Bacteriuria is a major risk factor for developing symptomatic urinary tract infection which is associated with significant maternal and fetal risks. Various studies have put a prevalence of asymptomatic bacteriuria between 2-10% in pregnancy. Maternal and fetal complications like gestational hypertension, anaemia, premature delivery, IUGR, and low birth weight are commonly associated with pyelonephritis which occurs as a result of undiagnosed or inadequately treated infections of the urinary tract. The primary objective was to find out the prevalence of asymptomatic bacteriuria in pregnancies less than 28 weeks gestation in our hospital and to study the various adverse pregnancy outcomes in the study group. Methods: This was a cross sectional study done over a period of 12 months at this tertiary care centre in Government sector in Trivandrum, Kerala. A sample size was calculated statistically and 400 women with gestational age less than 28 weeks attending the outpatient department were included in this study. A structured proforma, urine microscopy and urine culture and sensitivity were the study tools. Results: Prevalence of asymptomatic bacteriuria in our study population was 8.25%. Commonest pathogen isolated was E.coli in 57.14% cases. Maternal morbidity was higher in women with asymptomatic bacteriuria (24.2% than those without (12.5%. Fetal morbidity in women with asymptomatic bacteriuria was 24% whereas it was 12.5% in those without it. Preterm labour, preeclampsia and prematurity were the common morbidities noted. Conclusions: Since pregnant women with asymptomatic bacteriuria were at an increased risk of adverse maternal and fetal outcome, routine screening for asymptomatic bacteriuria preferably in the first trimester is highly recommended.

  5. Recurrent Hemolytic and Uremic Syndrome Induced by Escherichia Coli

    Science.gov (United States)

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

    2016-01-01

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

  6. 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.

  7. Engineered biosynthesis of bacterial aromatic polyketides in Escherichia coli

    OpenAIRE

    Zhang, Wenjun; Li, Yanran; Tang, Yi

    2008-01-01

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

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

    OpenAIRE

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

    1992-01-01

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

  9. Role of granulocytes and monocytes in experimental Escherichia coli endocarditis.

    OpenAIRE

    Meddens, M J; Thompson, J.; Bauer, W C; Furth, R. van

    1984-01-01

    The role of granulocytes and monocytes during the induction and course of Escherichia coli endocarditis was investigated in rabbits by selectively depleting monocytes from the circulation with the drug VP16-213 and granulocytes and monocytes with nitrogen mustard. For induction, the number of E. coli needed to infect the vegetations in 50% of the rabbits was significantly lower in rabbits with combined granulocytopenia and monocytopenia than in those with selective monocytopenia or in control...

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

    OpenAIRE

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

    1998-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Farhad Safarpourdehkourdi

    2014-03-01

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

  12. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Science.gov (United States)

    2011-11-23

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

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

    Directory of Open Access Journals (Sweden)

    Ivens Gomes Guimarães

    2002-05-01

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

  14. 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.

  15. YeeO from Escherichia coli exports flavins.

    Science.gov (United States)

    McAnulty, Michael J; Wood, Thomas K

    2014-01-01

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

  16. Frequency of pap and pil operons in Escherichia coli strains associated with urinary infections.

    Science.gov (United States)

    Perugini, M R; Vidotto, M C

    1996-03-01

    Strains of E. coli isolated from patients with urinary tract infection were examined for P and type 1 adhesin production by colony hybridization with pap and pil operons. The P pili probe detected 45 (46.4%) of the total of 97 strains studied and the type 1 pili probe detected 83 (85.6%). The pap operon was detected in 39 (53.4%) of 73 strains isolated from urine of patients with urinary disease and in 6 (25.0%) of 24 strains isolated from feces of healthy individuals employed as controls (P = 0.029), and the pil operon was detected in 67 (91.8%) of the urinary strains and in 16 (66.6%) of the fecal strains (P = 0.007). Our data did not show significant differences in frequency of P pili among isolates from pyelonephritis (78.5%), cystitis (45.8%) and asymptomatic bacteriuria (54.5%). Type 1 pili were not associated with the different types of infection; the frequency of these pili was 100% in pyelonephritis and in asymptomatic bacteriuria, and 87.5% in cystitis. The incidence of pap operon in strains isolated from pyelonephritis and from asymptomatic bacteriuria was higher in 11- to 40-year old women. These data show a high frequency of pap and pil operons among uropathogenic strains of E. coli, which seems to be an important factor in the development of urinary infection.

  17. 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...

  18. 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...

  19. 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

    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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. Sickness behavior in dairy cows during Escherichia coli mastitis

    DEFF Research Database (Denmark)

    Fogsgaard, Katrine Kop; Røntved, Christine Maria; Sørensen, Peter

    2012-01-01

    d before (d −2 and −1) to 3 d (d 0, 1, and 2) after experimental intramammary challenge with Escherichia coli. Effects of experimentally induced mastitis on behavior were examined in 20 primiparous Danish Holstein-Friesian cows, all 3 to 6 wk after calving and kept in tie stalls. After evening...

  6. 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...

  7. 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...

  8. 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...

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

    DEFF Research Database (Denmark)

    Willemoës, Martin; Hove-Jensen, Bjarne

    1997-01-01

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

  10. 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...

  11. Transport of Escherichia coli in saturated porous media

    NARCIS (Netherlands)

    Foppen, J.W.A.

    2007-01-01

    When wastewater infiltrates into the soil, groundwater may be contaminated. If the distance from source of pollution to point of groundwater abstraction is small, there is a real chance of abstracting pathogenic microorganisms. In this book, the transport of Escherichia coli in aquifers under satura

  12. A rapid differentiation method for enteroinvasive Escherichia coli.

    Science.gov (United States)

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

    2014-03-01

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

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

    NARCIS (Netherlands)

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

    2012-01-01

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

  16. Characterization of Escherichia coli nucleoids released by osmotic shock

    NARCIS (Netherlands)

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

    2012-01-01

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

  17. 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.

  18. armA and Aminoglycoside Resistance in Escherichia coli

    OpenAIRE

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

    2005-01-01

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

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

    OpenAIRE

    Michael S Donnenberg; Finlay, B. Brett

    2013-01-01

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

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  1. 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...

  2. Stringent control of FLP recombinase in Escherichia coli.

    Science.gov (United States)

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

    2017-02-01

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

  3. 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

  4. 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

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

    Science.gov (United States)

    Freifelder, D

    1976-11-01

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

  6. 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...

  7. Plasmid cloning vehicle for Haemophilus influenzae and Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-09-01

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

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

    Science.gov (United States)

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

    1998-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Fernanda Morcatti Coura

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Padmaja

    2012-10-01

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

  11. Asymptomatic bacteriuria among antenatal women attending a tertiary care hospital in Kanchipuram: evaluation of screening tests and antibiotic susceptibility pattern

    Directory of Open Access Journals (Sweden)

    Abirami Lakshmy Jayachandran

    2016-02-01

    Results: Out of the 120 samples 14 (11.66% were positive for asymptomatic bacteriuria. The Gram staining showed specificity and negative predictive value of 95.2% and 98.1% respectively. Pus cell count showed a specificity and negative predictive value of 96.29% and 98.11% respectively. Escherichia coli were the predominant species isolated 5 (35.7%. Among the gram negative bacteria, amikacin and nitrofurantoin showed a susceptibility of 90% and 80% each. All the staphylococcus aureus isolates showed 100% sensitivity for nitrofurantoin. Two Klebsiella spp and one Escherichia coli isolate were identified as ESBL producers. Among the S. aureus isolates 3 were identified as Methicillin resistant (MRSA. Conclusions: Urine culture should be performed for all pregnant women irrespective of the symptoms and should be treated promptly to prevent the complications arising out of ASB. [Int J Res Med Sci 2016; 4(2.000: 540-544

  12. 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.

  13. Deuterium incorporation into Escherichia-coli proteins

    DEFF Research Database (Denmark)

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

    1986-01-01

    Neutron small-angle scattering studies of single protein subunits in a protein-DNA complex require the adjustment of the neutron scattering-length densities of protein and DNA, which is attainable by specific deuteration of the protein. The neutron scattering densities of unlabelled DNA and DNA...... of the degree of deuteration and match point of any E. coli protein from the D2O content of the growth medium, taking the 2H incorporation into RNA polymerase amino acids to be representative for all amino acids in E. coli proteins. The small-angle scattering results, on which the calculation of the degree...

  14. 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...

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

    Science.gov (United States)

    Manges, Amee R; Johnson, James R

    2012-09-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

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

    Science.gov (United States)

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

    2007-12-01

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

  18. 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.

  19. Alterations induced in Escherichia Coli cells by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

    Modifications occurred in Escherichia coli cells exposed to gamma radiation ({sup 60}Co source) were investigated. The irradiations were done at the LIN-COPPE laboratory of the UFRJ and the analysis at the Biology Department of the UTFPR. The E. coli cells were irradiated with 30, 60, 90, 120, 150, 180, 210, 240, 300, 480, 600 e 750 Gy doses. The samples were analyzed with Gram-stain, biochemical tests in EPM, MIO and Lysine Broth, Simmons Cytrate Medium and Rhamnose Broth, antibiogram and isolation of auxotrophic mutants. It was observed that for the received doses the E. coli did not show morphological alterations in the tests. Some E. Coli cells showed to be able to deaminade the L-tryptophan or they changed their sensibility for amoxillin and cephaloonine after the irradiation. The existence of aauxotrophic mutants after irradiation was also verified. (author)

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

    Science.gov (United States)

    2014-01-01

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

  1. Viabilidad de Escherichia coli en presencia De diferentes contaminantes

    OpenAIRE

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

    2006-01-01

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

  2. Sedimentation and gravitational instability of Escherichia coli Suspension

    Science.gov (United States)

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

    2016-11-01

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

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

    Science.gov (United States)

    Demple, B; Halbrook, J

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

  4. Enteropathogenic Escherichia coli Serotypes and Endemic Diarrhea in Infants

    OpenAIRE

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

    1983-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1977-09-01

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

  6. ESCHERICHIA COLI: AN IMPORTANT PATHOGEN IN PATIENTS WITH HEMATOLOGIC MALIGNANCIES

    Directory of Open Access Journals (Sweden)

    Daniel Olson

    2014-08-01

    Full Text Available Abstract Background Escherichia coli (E. coli is a pathogen of great concern in immunosuppressed patients.  While antimicrobial prophylactic therapy has become the standard, the emergence of resistant pathogens has some questioning its use.  This study describes our experience with E.coli as a pathogen in neutropenic patients with a hematologic malignancy, and addresses future directions of treatment for this patient population. Methods A retrospective chart review of 245 E.coli bacteremia patients at Moffitt Cancer Center from 05/18/02 – 05/15/12 was conducted. Patients were identified via microbiology laboratory computerized records. Results The included patients experienced clinically significant E.coli bacteremia resulting in a median hospital stay of 14.7 days.  Several patients developed severe sepsis requiring the use of pressor and ventilator therapy. Conclusions E.coli is a major pathogen in these patient populations resulting in extended hospital stays and specialized treatment to overcome their E.coli bacteremia. The data supports the use of fluoroquinolone prophylactic therapy, however, earlier detection and treatment of neutropenic infection is needed.

  7. Comparison of 61 Sequenced Escherichia coli Genomes

    DEFF Research Database (Denmark)

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

    2010-01-01

    MLST was performed, many of the various strains appear jumbled and less well resolved. The predicted pan-genome comprises 15,741 gene families, and only 993 (6%) of the families are represented in every genome, comprising the core genome. The variable or 'accessory' genes thus make up more than 90......% of the pan-genome and about 80% of a typical genome; some of these variable genes tend to be co-localized on genomic islands. The diversity within the species E. coli, and the overlap in gene content between this and related species, suggests a continuum rather than sharp species borders in this group...

  8. Detection by molecular hybridization of pap, afa, and sfa adherence systems in Escherichia coli strains associated with urinary and enteral infections.

    Science.gov (United States)

    Archambaud, M; Courcoux, P; Labigne-Roussel, A

    1988-01-01

    The genetic determinants responsible for the adherence of Escherichia coli to uroepithelial cells have been identified in recent years by genetic and molecular methods. Specific DNA probes for each of the three operons which have been cloned so far (pap, afa, sfa/foc operons) have been used in colony hybridization experiments to detect the presence of each of these operons in the chromosomal DNA of 443 strains of E. coli; 186 strains were from patients with urinary tract infections (pyelonephritis, 106 strains; cystitis, 59; asymptomatic bacteriuria, 21) and 257 were strains from the stools of healthy subjects (61) or from patients with various enteral infections (196). E. coli strains harbouring the pap operon were found more frequently in the urine of patients with pyelonephritis (p less than 0.001) and cystitis (p less than 0.01) than in control stools. The presence of two operons (pap + afa) or (pap + sfa/foc) was only observed in uropathogenic strains (p less than 0.02). Pap and sfa/foc operons were never found in strains causing enteral infection; however, the afa operon was found in 7.6% of the enteropathogenic E. coli.

  9. 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.

  10. Biogenesis of inner membrane proteins in Escherichia coli.

    Science.gov (United States)

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

    2012-06-01

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

  11. Mechanobiology of Antimicrobial Resistant Escherichia coli and Listeria innocua.

    Science.gov (United States)

    Tajkarimi, Mehrdad; Harrison, Scott H; Hung, Albert M; Graves, Joseph L

    2016-01-01

    A majority of antibiotic-resistant bacterial infections in the United States are associated with biofilms. Nanoscale biophysical measures are increasingly revealing that adhesive and viscoelastic properties of bacteria play essential roles across multiple stages of biofilm development. Atomic Force Microscopy (AFM) applied to strains with variation in antimicrobial resistance enables new opportunities for investigating the function of adhesive forces (stickiness) in biofilm formation. AFM force spectroscopy analysis of a field strain of Listeria innocua and the strain Escherichia coli K-12 MG1655 revealed differing adhesive forces between antimicrobial resistant and nonresistant strains. Significant increases in stickiness were found at the nanonewton level for strains of Listeria innocua and Escherichia coli in association with benzalkonium chloride and silver nanoparticle resistance respectively. This advancement in the usage of AFM provides for a fast and reliable avenue for analyzing antimicrobial resistant cells and the molecular dynamics of biofilm formation as a protective mechanism.

  12. Plasmolysis during the division cycle of Escherichia coli.

    OpenAIRE

    Olijhoek, A J; Eden, C G; Trueba, F J; Pas, E; Nanninga, N

    1982-01-01

    Cells of Escherichia coli were plasmolyzed with sucrose. They were classified according to length by way of electron micrographs taken from samples prepared by agar filtration. The percentage of plasmolyzed cells increased about two- and threefold between mean cell sizes of newborn and separating cells. However, dividing cells were less frequently plasmolyzed than nondividing cells of the same length class. Analysis of cell halves (prospective daughters) in dividing cells showed that they beh...

  13. DNA microarray analysis of fim mutations in Escherichia coli

    DEFF Research Database (Denmark)

    Schembri, Mark; Ussery, David; Workman, Christopher

    2002-01-01

    Bacterial adhesion is often mediated by complex polymeric surface structures referred to as fimbriae. Type I fimbriae of Escherichia coli represent the archetypical and best characterised fimbrial system. These adhesive organelles mediate binding to D-mannose and are directly associated with viru...... the number of fimbriae expressed on the cell surface. The use of high-resolution oligonucleotide arrays for defining points of transcription initiation and termination is also demonstrated....

  14. Current perspectivesin pathogenesis and antimicrobial resistance of enteroaggregative Escherichia coli.

    Science.gov (United States)

    Kong, Haishen; Hong, Xiaoping; Li, Xuefen

    2015-08-01

    Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes acute and persistent diarrhea in children and adults. While the pathogenic mechanisms of EAEC intestinal colonization have been uncovered (including bacterial adhesion, enterotoxin and cytotoxin secretion, and stimulation of mucosal inflammation), those of severe extraintestinal infections remain largely unknown. The recent emergence of multidrug resistant EAEC represents an alarming public health threat and clinical challenge, and research on the molecular mechanisms of resistance is urgently needed.

  15. Complementation analysis of eleven tryptophanase mutations in Escherichia coli.

    Science.gov (United States)

    White, M K; Yudkin, M D

    1979-10-01

    Nine independent mutants deficient in tryptophanase activity were isolated. Each mutation was transferred to a specialized transducing phage that carries the tryptophanase region of the Escherichia coli chromosome. The nine phages thus produced, and a tenth carrying a previously characterized tryptophanase mutation, were used to lysogenize a bacterial strain harbouring a mutation in the tryptophanase structural gene and also a suppressor of polarity. In no case was complementation observed; we conclude that there is no closely linked positive regulatory gene for tryptophanase.

  16. Characterization of Aspergillus oryzae aspartyl aminopeptidase expressed in Escherichia coli.

    Science.gov (United States)

    Watanabe, Jun; Tanaka, Hisaki; Akagawa, Takumi; Mogi, Yoshinobu; Yamazaki, Tatsuo

    2007-10-01

    To characterize aspartyl aminopeptidase from Aspergillus oryzae, the recombinant enzyme was expressed in Escherichia coli. The enzyme cleaves N-terminal acidic amino acids. About 30% activity was retained in 20% NaCl. Digestion of defatted soybean by the enzyme resulted in an increase in the glutamic acid content, suggesting that the enzyme is potentially responsible for the release of glutamic acid in soy sauce mash.

  17. Effect of cobalt on Escherichia coli metabolism and metalloporphyrin formation

    OpenAIRE

    Majtan, Tomas; Frerman, Frank E.; Kraus, Jan P.

    2010-01-01

    Toxicity in Escherichia coli resulting from high concentrations of cobalt has been explained by competition of cobalt with iron in various metabolic processes including Fe–S cluster assembly, sulfur assimilation, production of free radicals and reduction of free thiol pool. Here we present another aspect of increased cobalt concentrations in the culture medium resulting in the production of cobalt protoporphyrin IX (CoPPIX), which was incorporated into heme proteins including membrane-bound c...

  18. Role for the female in bacterial conjugation in Escherichia coli.

    Science.gov (United States)

    Freifelder, D

    1967-08-01

    Hfr and F' Lac male strains of Escherichia coli were mated with purine-requiring females which had been starved for purine. These females formed mating pairs with the males. However, a mating in the absence of purine markedly reduced the yield of recombinants. Transfer of F' Lac or of lambda prophage also occurred infrequently. It was concluded that deoxyribonucleic acid transfer from male to female requires some, as yet unknown, function of the female.

  19. Maturation of the Escherichia coli divisome occurs in two steps.

    NARCIS (Netherlands)

    Aarsman, M.E.G.; Piette, A.; Fraipont, C.; Vinkenvleugel, T.M.F.; Nguyen-Distèche, M.; den Blaauwen, T.

    2005-01-01

    Cell division proteins FtsZ (FtsA, ZipA, ZapA), FtsE/X, FtsK, FtsQ, FtsL/B, FtsW, PBP3, FtsN and AmiC localize at mid cell in Escherichia coli in an interdependent order as listed. To investigate whether this reflects a time dependent maturation of the divisome, the average cell age at which FtsZ, F

  20. Multiple defects in Escherichia coli mutants lacking HU protein.

    OpenAIRE

    Huisman, O; Faelen, M; Girard, D; Jaffé, A; Toussaint, A; Rouvière-Yaniv, J

    1989-01-01

    The HU protein isolated from Escherichia coli, composed of two partially homologous subunits, alpha and beta, shares some of the properties of eucaryotic histones and is a major constituent of the bacterial nucleoid. We report here the construction of double mutants totally lacking both subunits of HU protein. These mutants exhibited poor growth and a perturbation of cell division, resulting in the formation of anucleate cells. In the absence of HU, phage Mu was unable to grow, to lysogenize,...

  1. 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.

  2. Examination of uropathogenic Escherichia coli strains conferring large plasmids

    Directory of Open Access Journals (Sweden)

    SUHARTONO

    2010-04-01

    Full Text Available Suhartono (2010 Examination of uropathogenic Escherichia coli strains conferring large plasmids. Biodiversitas 11: 59-64. Of major uropathogens, Escherichia coli has been widely known as a main pathogen of UTIs globally and has considerable medical and financial consequences. A strain of UPEC, namely E. coli ST131, confers a large plasmid encoding cephalosporinases (class C β-lactamase or AmpC that may be disseminated through horizontal transfer among bacterial populations. Therefore, it is worth examining such large plasmids by isolating, purifying, and digesting the plasmid with restriction enzymes. The examination of the large plasmids was conducted by isolating plasmid DNA visualized by agarose gel electrophoresis as well as by PFGE. The relationship of plasmids among isolates was carried out by HpaI restriction enzyme digestion. Of 36 isolates of E. coli ST 131, eight isolates possessed large plasmids, namely isolates 3, 9, 10, 12, 17, 18, 26 and 30 with the largest molecular size confirmed by agarose gel electrophoresis and PFGE was ~42kb and ~118kb respectively. Restriction enzyme analysis revealed that isolates 9, 10, 12, 17 and 18 have the common restriction patterns and those isolates might be closely related.

  3. Biochemical characteristic of biofilm of uropathogenic Escherichia coli Dr(+) strains.

    Science.gov (United States)

    Zalewska-Piątek, Beata; Wilkanowicz, Sabina; Bruździak, Piotr; Piątek, Rafał; Kur, Józef

    2013-07-19

    Urinary tract infections caused by Escherichia coli are very common health problem in the developed countries. The virulence of the uropathogenic E. coli Dr(+) IH11128 is determined by Dr fimbriae, which are homopolymeric structures composed of DraE subunits with the DraD protein capping the fiber. In this study, we have analyzed the structural and biochemical properties of biofilms developed by E. coli strains expressing Dr fimbriae with or without the DraD tip subunit and the surface-exposed DraD protein. We have also demonstrated that these E. coli strains form biofilms on an abiotic surface in a nutrient-dependent fashion. We present evidence that Dr fimbriae are necessary during the first stage of bacterial interaction with the abiotic surface. In addition, we reveal that the DraD alone is also sufficient for the initial surface attachment at an even higher level than Dr fimbriae and that chloramphenicol is able to reduce the normal attachment of the analyzed E. coli. The action of chloramphenicol also shows that protein synthesis is required for the early events of biofilm formation. Additionally, we have identified reduced exopolysaccharide coverage in E. coli that express only Dr fimbrial polyadhesins at the cell surface with or without the DraD capping subunit.

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

    Science.gov (United States)

    Mobley, Harry L. T.

    2016-01-01

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

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

    Science.gov (United States)

    Moberg, L J

    1985-12-01

    An assay procedure to screen for Escherichia coli in foods by using 4-methylumbelliferyl-beta-D-glucuronide (MUG) incorporated into lauryl tryptose (LST) broth was evaluated. The beta-glucuronidase produced by E. coli cleaves the MUG substrate to yield a fluorescent end product. E. coli-negative samples can be identified by lack of fluorescence in LST-MUG within 24 h. MUG was not inhibitory to coliforms and E. coli. Over 1,400 food and dairy samples were tested to compare the standard three-tube most-probable-number procedure with the MUG-containing or non-MUG-containing LST procedure. LST-MUG testing detected a greater number of E. coli, with a lower false-positive rate (1.4%) and in a shorter time, than did the standard procedure. All false-positive results in the LST-MUG testing were attributable to beta-glucuronidase-producing staphylococci. No false-negative result was encountered. Use of MUG in LST broth obviates the EC broth step, allowing a 2.5-day procedure to a completed E. coli test versus the present 4- to 6-day standard most-probable-number method.

  6. Production of isopropanol by metabolically engineered Escherichia coli.

    Science.gov (United States)

    Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki

    2008-01-01

    A genetically engineered strain of Escherichia coli JM109 harboring the isopropanol-producing pathway consisting of five genes encoding four enzymes, thiolase, coenzyme A (CoA) transferase, acetoacetate decarboxylase from Clostridium acetobutylicum ATCC 824, and primary-secondary alcohol dehydrogenase from C. beijerinckii NRRL B593, produced up to 227 mM of isopropanol from glucose under aerobic fed-batch culture conditions. Acetate production by the engineered strain was approximately one sixth that produced by a control E. coli strain bearing an expression vector without the clostridial genes. These results demonstrate a functional isopropanol-producing pathway in E. coli and consequently carbon flux from acetyl-CoA directed to isopropanol instead of acetate. This is the first report on isopropanol production by genetically engineered microorganism under aerobic culture conditions.

  7. Protein abundance profiling of the Escherichia coli cytosol

    DEFF Research Database (Denmark)

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

    2008-01-01

    PAI approach which takes into account the number of sequenced peptides per protein. The values of abundance are within a broad range and accurately reflect independently measured copy numbers per cell. As expected, the most abundant proteins were those involved in protein synthesis, most notably ribosomal...... sample. Using a combination of LC-MS/MS approaches with protein and peptide fractionation steps we identified 1103 proteins from the cytosolic fraction of the Escherichia coli strain MC4100. A measure of abundance is presented for each of the identified proteins, based on the recently developed em...... protein and mRNA abundance in E. coli cells. Conclusion: Abundance measurements for more than 1000 E. coli proteins presented in this work represent the most complete study of protein abundance in a bacterial cell so far. We show significant associations between the abundance of a protein and its...

  8. 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.

  9. Escherichia coli portador de betalactamasas de espectro extendido: resistencia

    Directory of Open Access Journals (Sweden)

    Mª C. Miranda García

    2013-12-01

    Full Text Available Introducción: Escherichia coli es el microorganismo que con más frecuencia se encuentra implicado en infecciones nosocomiales y comunitarias, patógeno responsable en la etiología de infecciones de vías respiratorias altas, infecciones del tracto urinario, heridas quirúrgicas, sangre o gastroenteritis. En los últimos años ha experimentado importantes cambios encontrándose un aumento de infecciones por cepas de éstos microorganismos productores de betalactamasas de espectro extendido. Objetivos: Se decide hacer este estudio retrospectivo de las muestras procesadas en el Laboratorio de Microbiología del Hospital Básico de la Defensa San Carlos (San Fernando, para conocer la frecuencia y el patrón de sensibilidad en nuestra población por gérmenes productores de betalactamasas de espectro extendido en este caso por Escherichia coli, dada la importancia de las infecciones causadas por esta bacteria y la repercusión que tiene por todo el mundo los mecanismos de resistencia. Material y Método: Se recogieron los datos de resultados obtenidos en las muestras procesadas en el Laboratorio de Microbiología durante 36 meses (Enero 2009 a Diciembre 2011, en las que se hubieran identificado cepas de Escherichia coli y de éstas las productoras de betalactamasas de espectro extendido. Resultados: Se aislaron 34 cepas de Escherichia coli productoras de betalactamasas de espectro extendido lo que supone una tasa del 5,10%. Se encontró una frecuencia mayor en el año 2010 (6,9% que en el 2009 (2,61%, pero similar al 2011 (5,98%. Conclusión: La frecuencia de cepas Escherichia coli con betalactamasas de espectro extendido encontrada es similar a la de otros estudios realizados en España, pero la tasa de resistencia de algunos antimicrobianos como Amoxicilina/clavulánico, Cotrimoxazol y Fluorquinolonas en nuestra población es elevada.

  10. Evaluation of Five Jet Fuels in the Salmonella-Escherichia coli / Microsome Plate Incorporation Assay

    Science.gov (United States)

    2010-09-01

    AFRL-RH-WP-TR-2010-0138 Evaluation of Five Jet Fuels in the Salmonella-Escherichia coli / Microsome Plate Incorporation Assay Edward S...31 Jul 2010 4. TITLE AND SUBTITLE Evaluation of Five Jet Fuels in the Salmonella-Escherichia coli / Microsome Plate Incorporation Assay 5a...the Salmonella typhimurium-Escherichia coli/ microsome plate incorporation assay. The assay was performed using the plate incorporation procedure

  11. Unusual "flesh-eating" strains of Escherichia coli.

    Science.gov (United States)

    Shaked, Hila; Samra, Zmira; Paul, Michal; Madar-Shapiro, Liora; Cohen, Jonathan; Pitlik, Silvio; Bishara, Jihad

    2012-12-01

    Monomicrobial necrotizing fasciitis (type II) is typically caused by group A streptococcus alone or in combination with Staphylococcus aureus. Escherichia coli has been isolated from polymicrobial or Fournier's gangrene but has rarely been reported in monomicrobial necrotizing fasciitis. We describe the clinical characteristics and outcomes of seven cases of monomicrobial E. coli necrotizing fasciitis and/or severe soft tissue infection diagnosed at a single institution during an 18-month period. Four isolates from three patients and two isolates from two patients with type I polymicrobial severe soft tissue infection (controls) were assayed by the randomly amplified polymorphic DNA (RAPD) analysis for fingerprinting and PCR amplification of primers in order to detect cytotoxic necrotizing factor 1 and 2 (cnf1 and cnf2) genes. All patients had some type of immune suppression. The limb was the most commonly involved organ. In all cases, E. coli was isolated as a monomicrobial pathogen from blood, fascia, or both. All patients died during hospitalization, three within the first 48 h. The RAPD amplification assay showed a high degree of genetic diversity among the "flesh-eating" strains and controls. The cnf1 toxin gene was identified in two out of three cases, but not in the controls. cnf2 was not detected in any of the patients. E. coli may be responsible for life-threatening necrotizing fasciitis. Further research is needed to reveal relevant risk factors, reservoirs, and modes of transmission of cnf1 E. coli.

  12. Multiple antimicrobial resistance among Avian Escherichia coli strains in Albania

    Directory of Open Access Journals (Sweden)

    Antonio Camarda

    2010-01-01

    Full Text Available In this study, 101 Escherichia (E. coli isolates from broilers, laying hens and turkeys which had died from colibacillosis, collected from 37 intensive and rural farms in Albania, were tested for antimicrobial susceptibility toward 12 different molecules. The highest levels of resistance were observed for Erythromycin (E (100% Amoxicillin (AMX (99.1%, Tetracycline (TE 30 (96.07%, Streptomycin (STR (93.07% and Neomycin (N30 (85.15%. Considerable resistance was also detected for fluoroquinolones. Moreover, 73.33% of E. coli resistant to at least one fluoroquinolone were also resistant to the two other fluoroquinolones checked. No evident differences were found between the E. coli from intensive and from rural farms. Multiple antibiotic resistance was expressed by all the E. coli tested. 23.63% and 17.39% of E. coli isolated from intensive and rural farms, respectively, were resistant towards all the drugs tested. These data would seem to indicate incorrect use of antibiotics on poultry farms in Albania.

  13. Escherichia coli exports cyclic AMP via TolC.

    Science.gov (United States)

    Hantke, Klaus; Winkler, Karin; Schultz, Joachim E

    2011-03-01

    In Escherichia coli more than 180 genes are regulated by the cyclic AMP (cAMP)-cAMP receptor protein (CRP) complex. However, more than 90% of cAMP that is made by intracellular adenylyl cyclases is found in the culture medium. How is cAMP exported from E. coli? In a tolC mutant, 0.03 mM IPTG (isopropyl-β-d-thiogalactopyranoside) was sufficient to induce β-galactosidase compared to 0.1 mM IPTG in the parent strain. In a cya mutant unable to produce cAMP about 1 mM extracellular cAMP was required to induce β-galactosidase, whereas in a cya tolC mutant 0.1 mM cAMP was sufficient. When cAMP in E. coli cya was generated intracellularly by a recombinant, weakly active adenylyl cyclase from Corynebacterium glutamicum, the critical level of cAMP necessary for induction of maltose degradation was only achieved in a tolC mutant and not in the parent strain. Deletion of a putative cAMP phosphodiesterase of E. coli, CpdA, resulted in a slightly similar, yet more diffuse phenotype. The data demonstrate that export of cAMP via TolC is a most efficient way of E. coli to lower high concentrations of cAMP in the cell and maintain its sensitivity in changing metabolic environments.

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

    Directory of Open Access Journals (Sweden)

    Migla Miskinyte

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

  15. Phylogenetic analysis of Escherichia coli strains isolated from human samples

    Directory of Open Access Journals (Sweden)

    Abdollah Derakhshandeh

    2013-12-01

    Full Text Available Escherichia coli (E. coli is a normal inhabitant of the gastrointestinal tract of vertebrates, including humans. Phylogenetic analysis has shown that E. coli is composed of four main phylogenetic groups (A, B1, B2 and D. Group A and B1 are generally associated with commensals, whereas group B2 is associated with extra-intestinal pathotypes. Most enteropathogenic isolates, however, are assigned to group D. In the present study, a total of 102 E. coli strains, isolated from human samples, were used. Phylogenetic grouping was done based on the Clermont triplex PCR method using primers targeted at three genetic markers, chuA, yjaA and TspE4.C2. Group A contained the majority of the collected isolates (69 isolates, 67.64%, followed by group B2 (18 isolates, 17.64% and D (15 isolates, 14.7% and no strains were found to belong to group B1. The distribution of phylogenetic groups in our study suggests that although the majority of strains were commensals, the prevalence of enteropathogenic and extra-intestinal pathotypes was noteworthy. Therefore, the role of E. coli in human infections including diarrhea, urinary tract infections and meningitis should be considered.

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

    Science.gov (United States)

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

    2010-01-01

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

  17. Pulsed-Plasma Disinfection of Water Containing Escherichia coli

    Science.gov (United States)

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

    2007-03-01

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

  18. Nonthermal atmospheric argon plasma jet effects on Escherichia coli biomacromolecules.

    Science.gov (United States)

    Hosseinzadeh Colagar, Abasalt; Memariani, Hamed; Sohbatzadeh, Farshad; Valinataj Omran, Azadeh

    2013-12-01

    Nonthermal atmospheric plasma jet, a promising technology based on ionized gas at low temperatures, can be applied for disinfection of contaminated surfaces. In this study, Escherichia coli cells and their macromolecules were exposed to the nonthermal atmospheric argon plasma jet for different time durations. Total protein, genomic DNA, and malondialdehyde (MDA) levels of E. coli were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining; agarose gel electrophoresis; and measurement of absorbance at 534 nm, respectively. After exposure, the spectroscopic results of liquid samples indicated that the survival reduction of E. coli can reach to 100 % in an exposure time of 600 s. Moreover, inactivation zones of E. coli, DNA degradation, and MDA levels were significantly increased. Additionally, banding patterns of total protein were changed and amino acid concentrations increased following ninhydrin test. The experimental results suggest that the nonthermal plasma could serve as an effective instrument for both sterilizing E. coli and degrading macromolecules from the surface of the objects being sterilized.

  19. Escherichia coli mediated urinary tract infections: are there distinct uropathogenic E. coli (UPEC) pathotypes?

    Science.gov (United States)

    Marrs, Carl F; Zhang, Lixin; Foxman, Betsy

    2005-11-15

    A variety of virulence genes are associated with Escherichia coli mediated urinary tract infections. Particular sets of virulence factors shared by bacterial strains directing them through a particular pathogenesis process are called a "pathotype." Comparison of co-occurrence of potential urinary tract infection (UTI) virulence genes among different E. coli isolates from fecal and UTI collections provides evidence for multiple pathotypes of uropathogenic E. coli, but current understanding of critical genetic differences defining the pathotypes is limited. Discovery of additional E. coli genes involved in uropathogenesis and determination of their distribution and co-occurrences will further define UPEC pathotypes and allow for a more detailed analysis of how these pathotypes might differ in how they cause disease.

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

    Science.gov (United States)

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

    2008-10-01

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

  1. 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.

  2. Overexpression and export of Vibrio anguillarum metalloprotease in Escherichia coli

    Institute of Scientific and Technical Information of China (English)

    Zhang Fengli; Chi Zhenming; Chen Jixiang; Wu Longfei; Liang Likun

    2007-01-01

    Vibrio anguillarum metalloprotease, an extracellular zinc metalloprotease involved in the virulence mechanism of Vibrio anguillarum, is synthesized from the empA gene as a 611-residue precursor and naturally secreted via Sec secretion pathway in Vibrio anguillarum. In this study, heterologous expression of the empA gene encoding metallopmtease and export of the recombinant metalloprotease in Escherichia coliwere examined. The empA gene was subcloned into pBAD24 with arabinose promoter and sequenced. The sequence encoded a polypeptide(611 amino acids)consisting of four domains: a signal peptide, an Nterminal propeptide, a mature region and a C-terminal propeptide. The empA gene inserted in plasmid pBAD24 was overexpressed in TOP10 strain of E. Coli after arabinose induction. The 36kDa polypeptide of the recombinant metalloprotease as the mature protease was further confirmed by SDS-PAGE and immunoblotting. It was found that recombinant metalloprotease with the EmpA activity and antigenicity wasexported into the periplasm of Escherichia coli cells via Sec translocation pathway, whereas it was secreted into extracellular environments in V. Anguillarum. The results imply that the expression, export and processing mechanism of the protein in E. Coli are similar to those in V. Anguillarum.

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

    Science.gov (United States)

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

    2016-10-01

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

  4. Reduction of verotoxigenic Escherichia coli in production of fermented sausages.

    Science.gov (United States)

    Holck, Askild L; Axelsson, Lars; Rode, Tone Mari; Høy, Martin; Måge, Ingrid; Alvseike, Ole; L'abée-Lund, Trine M; Omer, Mohamed K; Granum, Per Einar; Heir, Even

    2011-11-01

    After a number of foodborne outbreaks of verotoxigenic Escherichia coli involving fermented sausages, some countries have imposed regulations on sausage production. For example, the US Food Safety and Inspection Service requires a 5 log(10) reduction of E. coli in fermented products. Such regulations have led to a number of studies on the inactivation of E. coli in fermented sausages by changing processing and post-processing conditions. Several factors influence the survival of E. coli such as pre-treatment of the meat, amount of NaCl, nitrite and lactic acid, water activity, pH, choice of starter cultures and addition of antimicrobial compounds. Also process variables like fermentation temperature and storage time play important roles. Though a large variety of different production processes of sausages exist, generally the reduction of E. coli caused by production is in the range 1-2 log(10). In many cases this may not be enough to ensure microbial food safety. By optimising ingredients and process parameters it is possible to increase E. coli reduction to some extent, but in some cases still other post process treatments may be required. Such treatments may be storage at ambient temperatures, specific heat treatments, high pressure processing or irradiation. HACCP analyses have identified the quality of the raw materials, low temperature in the batter when preparing the sausages and a rapid pH drop during fermentation as critical control points in sausage production. This review summarises the literature on the reduction verotoxigenic E. coli in production of fermented sausages.

  5. Genome Sequence of the Enterohemorrhagic Escherichia coli Bacteriophage UFV-AREG1

    Science.gov (United States)

    Batalha, Laís Silva; Albino, Luiz Augusto A.; Boggione, Delaine Meireles Gouveia; Gontijo, Marco Tulio Pardini; Bazzolli, Denise M. Soares; Mendonca, Regina C. Santos

    2016-01-01

    Here, we present the genome sequence of the Escherichia coli bacteriophage UFV-AREG1. This phage was isolated from cowshed wastewater and showed specificity for enterohemorrhagic E. coli O157:H7 (ATCC 43895), E. coli 0111 (CDC O11ab) and E. coli (ATCC 23229). PMID:27738021

  6. 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

  7. Diarrhea, Urosepsis and Hemolytic Uremic Syndrome Caused by the Same Heteropathogenic Escherichia coli Strain.

    Science.gov (United States)

    Ang, C Wim; Bouts, Antonia H M; Rossen, John W A; Van der Kuip, Martijn; Van Heerde, Marc; Bökenkamp, Arend

    2016-09-01

    We describe an 8-month-old girl with diarrhea, urosepsis and hemolytic uremic syndrome caused by Escherichia coli. Typing of cultured E. coli strains from urine and blood revealed the presence of virulence factors from multiple pathotypes of E. coli. This case exemplifies the genome plasticity of E. coli and the resulting heteropathogenic strains.

  8. Intramacrophage survival of uropathogenic Escherichia coli: Differences between diverse clinical isolates and between mouse and human macrophages

    DEFF Research Database (Denmark)

    Bokil, Nilesh J.; Totsika, Makrina; Carey, Alison J.;

    2011-01-01

    Uropathogenic E. coli (UPEC) are the primary cause of urinary tract infections. Recent studies have demonstrated that UPEC can invade and replicate within epithelial cells, suggesting that this bacterial pathogen may occupy an intracellular niche within the host. Given that many intracellular...... or initial uptake of bacteria. E. coli UTI89 localized to a Lamp1+ vesicular compartment within BMM. In contrast to survival within mouse BMM, intracellular bacterial loads of VR50 were low in both human monocyte-derived macrophages (HMDM) and in human T24 bladder epithelial cells. Collectively, these data......, originally isolated from patients with cystitis and asymptomatic bacteriuria respectively, showed elevated bacterial loads in BMM at 24h post-infection as compared to CFT073 and the asymptomatic bacteriuria strain 83972. These differences did not correlate with differential effects on macrophage survival...

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

    Science.gov (United States)

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

    2015-10-01

    Enterotoxigenic Escherichia coli (ETEC) strains harbor multiple fimbriae and pili to mediate host colonization, including the type IVb pilus, colonization factor antigen III (CFA/III). Not all colonization factors are well characterized or known in toxin positive ETEC isolates, which may have an impact identifying ETEC isolates based on molecular screening of these biomarkers. We describe a novel coli surface antigen (CS) 8 subtype B (CS8B), a family of CFA/III pilus, in a toxin producing ETEC isolate from a Kenyan collection. In highlighting the existence of this putative CS, we provide the sequence and specific primers, which can be used alongside other ETEC primers previously described.

  10. Posttranslational Modifications of Ribosomal Proteins in Escherichia coli.

    Science.gov (United States)

    Nesterchuk, M V; Sergiev, P V; Dontsova, O A

    2011-04-01

    А number of ribosomal proteins inEscherichia coliundergo posttranslational modifications. Six ribosomal proteins are methylated (S11, L3, L11, L7/L12, L16, and L33), three proteins are acetylated (S5, S18, and L7), and protein S12 is methylthiolated. Extra amino acid residues are added to protein S6. С-terminal amino acid residues are partially removed from protein L31. The functional significance of these modifications has remained unclear. These modifications are not vital to the cells, and it is likely that they have regulatory functions. This paper reviews all the known posttranslational modifications of ribosomal proteins inEscherichia coli. Certain enzymes responsible for the modifications and mechanisms of enzymatic reactions are also discussed.

  11. 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...

  12. Modulation of allele leakiness and adaptive mutability in Escherichia coli

    Indian Academy of Sciences (India)

    R. Jayaraman

    2000-08-01

    It is shown that partial phenotypic suppression of two ochre mutations (argE3 and lacZU118) and an amber mutation (in argE) by sublethal concentrations of streptomycin in an rpsL+ (streptomycin-sensitive) derivative of the Escherichia coli strain AB1157 greatly enhances their adaptive mutability under selection. Streptomycin also increases adaptive mutability brought about by the ppm mutation described earlier. Inactivation of recA affects neither phenotypic suppression by streptomycin nor replication-associated mutagenesis but abolishes adaptive mutagenesis. These results indicate a causal relationship between allele leakiness and adaptive mutability.

  13. [Hemolytic uremic syndrome caused by enterohaemorrhagic Escherichia coli].

    Science.gov (United States)

    Ibarra, Cristina; Goldstein, Jorge; Silberstein, Claudia; Zotta, Elsa; Belardo, Marcela; Repetto, Horacio A

    2008-10-01

    Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolytic anemia, plaquetopenia and kidney damage. It is the leading cause of acute renal failure in pediatric age and the second for chronic renal failure. Shiga toxin-producing Escherichia coli (STEC) is the first etiologic agent of HUS being its main reservoir cattle and transmitted via contaminated food. At present, there is no specific treatment to reduce the progression of HUS. The study of the mechanisms by which STEC infects and Shiga toxin induces HUS can help to find new strategies to prevent this disease.

  14. Precursor for elongation factor Tu from Escherichia coli.

    OpenAIRE

    1986-01-01

    The tufA gene, one of two genes in Escherichia coli encoding elongation factor Tu (EF-Tu), was cloned into a ColE1-derived plasmid downstream of the lac promoter-operator. In cells carrying this plasmid, the synthesis of EF-Tu was increased four- to fivefold upon the addition of isopropyl-beta-D-thiogalactopyranoside (an inducer of the lac promoter). This condition led to the synthesis of a novel protein, called pTu, which comigrated with EF-Tu on a sodium dodecyl sulfate-polyacrylamide gel b...

  15. 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...... in restoring redox homeostasis through the concerted activity of isocitrate dehydrogenase and UdhA transhydrogenase. We present a reconciled network of regulation that illustrates the overlapping and distinct aspects of metabolism controlled by NADH and ATP. Our study contributes to the general understanding...

  16. Pengujian Bakteri Escherichia Coli Pada Air Sumur Di Medan Johor

    OpenAIRE

    Mahardhika, Diah

    2013-01-01

    Water is an essential material in life. Water is a means to improve public health. The spread of water borne diseases can be. Water pollution can be caused due to the entry of human and animal waste, but it can also be caused directly or through a leak or where ground soil cracks. This test aims to determine the number most likely Most Probable Number (MPN) Escherichia coli bacteria that contaminate well water located in Medan Johor still meet water quality requirements or not. The samplin...

  17. CRISPR adaptation in Escherichia coli subtypeI-E system.

    Science.gov (United States)

    Kiro, Ruth; Goren, Moran G; Yosef, Ido; Qimron, Udi

    2013-12-01

    The CRISPRs (clustered regularly interspaced short palindromic repeats) and their associated Cas (CRISPR-associated) proteins are a prokaryotic adaptive defence system against foreign nucleic acids. The CRISPR array comprises short repeats flanking short segments, called 'spacers', which are derived from foreign nucleic acids. The process of spacer insertion into the CRISPR array is termed 'adaptation'. Adaptation allows the system to rapidly evolve against emerging threats. In the present article, we review the most recent studies on the adaptation process, and focus primarily on the subtype I-E CRISPR-Cas system of Escherichia coli.

  18. 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.

  19. Interactions between Phage-Shock Proteins in Escherichia coli

    OpenAIRE

    Adams, Hendrik; Teertstra, Wieke; Demmers, Jeroen; Boesten, Rolf; Tommassen, Jan

    2003-01-01

    Expression of the pspABCDE operon of Escherichia coli is induced upon infection by filamentous phage and by many other stress conditions, including defects in protein export. Expression of the operon requires the alternative sigma factor σ54 and the transcriptional activator PspF. In addition, PspA plays a negative regulatory role, and the integral-membrane proteins PspB and PspC play a positive one. In this study, we investigated whether the suggested protein-protein interactions implicated ...

  20. PspA can form large scaffolds in Escherichia coli.

    Science.gov (United States)

    Standar, Kerstin; Mehner, Denise; Osadnik, Hendrik; Berthelmann, Felix; Hause, Gerd; Lünsdorf, Heinrich; Brüser, Thomas

    2008-10-29

    The phage shock protein A (PspA) of Escherichia coli stabilizes the cytoplasmic membrane under stress conditions. Here we demonstrate that PspA can form hollow spherical or prolate spheroidal particles of about 30-40nm diameter with a scaffold-like arrangement of protein subunits at the surface. The 'PspA-scaffold' is the basic structure that is common to all particles. The PspA-scaffold may be of fundamental importance, as it could allow PspA to stabilize the integrity of membranes through numerous contact points over a large surface area.

  1. PspA can form large scaffolds in Escherichia coli.

    OpenAIRE

    Standar, Kerstin; Mehner, Denise; Osadnik, Hendrik; Berthelmann, Felix; Hause, Gerd; Lünsdorf, Heinrich; Brüser, Thomas

    2008-01-01

    The phage shock protein A (PspA) of Escherichia coli stabilizes the cytoplasmic membrane under stress conditions. Here we demonstrate that PspA can form hollow spherical or prolate spheroidal particles of about 30-40nm diameter with a scaffold-like arrangement of protein subunits at the surface. The 'PspA-scaffold' is the basic structure that is common to all particles. The PspA-scaffold may be of fundamental importance, as it could allow PspA to stabilize the integrity of membranes through n...

  2. Composition of cardiolipin molecular species in Escherichia coli.

    OpenAIRE

    Yokota, K; Kanamoto, R.; Kito, M

    1980-01-01

    The composition of the molecular species of acidic phospholipids in Escherichia coli B during the late exponential growth phase at 37 degrees C was determined. Two phosphatidyl groups of cardiolipin, the 3-(3-sn-phosphatidyl) and 1-(3-sn-phosphatidyl) moieties of cardiolipin, were isolated by limited hydrolysis with phospholipase C. No significant difference in the composition of the molecular species was found between the 3-(3-sn-phosphatidyl) and 1-(3-sn-phosphatidyl) moieties. On the other...

  3. 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.

  4. Resistencia a biocidas de diferentes cepas de escherichia coli

    OpenAIRE

    López Aguayo, M. Carmen; Grande Burgos, M. José; Lucas López, R.; Gálvez-del-Postigo-Ruiz, Antonio

    2010-01-01

    Los biocidas son herramientas de gran importancia para controlar la transmisión de microorganismos patógenos a través de la cadena alimentaria. En el presente estudio se ha determinado la resistencia a siete biocidas en una colección de nueve cepas de Escherichia coli, incluyendo cepas verotoxigénicas y cepas portadoras de resistencia a beta-lactámicos. Los biocidas más eficaces fueron triclosan, hexadecilpiridinio y cetrimida, seguido del cloruro de benzalconio. No se encon...

  5. In Vivo study of naturally deformed Escherichia coli bacteria.

    Science.gov (United States)

    Tavaddod, Sharareh; Naderi-Manesh, Hossein

    2016-06-01

    A combination of light-microscopy and image processing has been applied to study naturally deformed Escherichia coli under in vivo condition and at the order of sub-pixel high-resolution accuracy. To classify deflagellated non-dividing E. coli cells to the rod-shape and bent-shape, a geometrical approach has been applied. From the analysis of the geometrical data which were obtained of image processing, we estimated the required effective energy for shaping a rod-shape to a bent-shape with the same size. We evaluated the energy of deformation in the naturally deformed bacteria with minimum cell manipulation, under in vivo condition, and with minimum influence of any external force, torque and pressure. Finally, we have also elaborated on the possible scenario to explain how naturally deformed bacteria are formed from initial to final-stage.

  6. PRODUCTION OF RECOMBINANT PROTEIN CRM197 IN ESCHERICHIA COLI

    Directory of Open Access Journals (Sweden)

    I. V. Dukhovlinov

    2015-01-01

    Full Text Available The CRM197 is a non-toxic mutant of diphtheria toxin having a single amino acid substitution of a glycine for a glutamic acid in position 52. Being naturally nontoxic, CRM197 is a promising adjuvant and ideal carrier protein for conjugate vaccines. Typically, production of diphtheria toxin and some of the non-toxic proteins are carried out by Corynebacterium diphtheriae. Production of recombinant protein CRM197 in Escherichia coli is advantageous. It is simple, cheap and permits production of the target protein in a short time using a non-pathogenic microorganism. In this study patented high-yield-producing E. coli strain was used. As a part of the study the following steps were taken: protocol adjustment for induction of crm197 gene, production and purification of recombinant CRM197 by ion-exchange, hydrophobic and gel-filtration chromatography. The purity of the final preparation reached 97%.

  7. Purification of recombinant ovalbumin from inclusion bodies of Escherichia coli.

    Science.gov (United States)

    Upadhyay, Vaibhav; Singh, Anupam; Panda, Amulya K

    2016-01-01

    Recombinant ovalbumin expressed in bacterial host is essentially free from post-translational modifications and can be useful in understanding the structure-function relationship of the protein. In this study, ovalbumin was expressed in Escherichia coli in the form of inclusion bodies. Ovalbumin inclusion bodies were solubilized using urea and refolded by decreasing the urea concentration by dilution. Refolded protein was purified by anion exchange chromatography. Overall recovery of purified recombinant ovalbumin from inclusion bodies was about 30% with 98% purity. Purified recombinant ovalbumin was characterized by mass spectrometry, circular dichroism and fluorescence spectroscopy. Recombinant ovalbumin was shown to be resistant to trypsin using protease resistance assay. This indicated proper refolding of ovalbumin from inclusion bodies of E. coli. This method provides a simple way of producing ovalbumin free of post-translational modifications.

  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. Engineering Escherichia coli for improved ethanol production from gluconate.

    Science.gov (United States)

    Hildebrand, Amanda; Schlacta, Theresa; Warmack, Rebeccah; Kasuga, Takao; Fan, Zhiliang

    2013-10-10

    We report on engineering Escherichia coli to produce ethanol at high yield from gluconic acid (gluconate). Knocking out genes encoding for the competing pathways (l-lactate dehydrogenase and pyruvate formate lyase A) in E. coli KO11 eliminated lactate production, lowered the carbon flow toward acetate production, and improved the ethanol yield from 87.5% to 97.5% of the theoretical maximum, while the growth rate of the mutant strain was about 70% of the wild type. The corresponding genetic modifications led to a small improvement of ethanol yield from 101.5% to 106.0% on glucose. Deletion of the pyruvate dehydrogenase gene (pdh) alone improved the ethanol yield from 87.5% to 90.4% when gluconate was a substrate. The growth rate of the mutant strain was identical to that of the wild type. The corresponding genetic modification led to no improvements on ethanol yield on glucose.

  10. The action of beta-galactosidase (Escherichia coli) on allolactose.

    Science.gov (United States)

    Huber, R E; Wallenfels, K; Kurz, G

    1975-09-01

    The parameters involved in the action of beta-galactosidase (EC 3.2.1.23) (Escherichia coli) on allolactose, the natural inducer of lac operon in E. coli, were studied. At low allolactose concentrations only galactose and glucose were formed, while at high allolactose concentrations transgalactolytic oligosaccharides were also produced. Detectable amounts of lactose were not formed. The V and Km values (49.6 U/mg and 0.00120 M, respectively) indicated that allolactose is as good if not a better substrate of beta-galactosidase as lactose. The pH optimum with allolactose (7.8-7.9) as well as its activation by K+ (as compared to activation by Na+) were similar to the case with lactose as substrate. The alpha-anomer of allolactose was hydrolyzed about two times as rapidly as was the beta-anomer.

  11. Mutational analysis of UMP kinase from Escherichia coli.

    Science.gov (United States)

    Bucurenci, N; Serina, L; Zaharia, C; Landais, S; Danchin, A; Bârzu, O

    1998-02-01

    UMP kinase from Escherichia coli is one of the four regulatory enzymes involved in the de novo biosynthetic pathway of pyrimidine nucleotides. This homohexamer, with no counterpart in eukarya, might serve as a target for new antibacterial drugs. Although the bacterial enzyme does not show sequence similarity with any other known nucleoside monophosphate kinase, two segments between amino acids 35 to 78 and 145 to 194 exhibit 28% identity with phosphoglycerate kinase and 30% identity with aspartokinase, respectively. Based on these similarities, a number of residues of E. coli UMP kinase were selected for site-directed mutagenesis experiments. Biochemical, kinetic, and spectroscopic analysis of the modified proteins identified residues essential for catalysis (Asp146), binding of UMP (Asp174), and interaction with the allosteric effectors, GTP and UTP (Arg62 and Asp77).

  12. Biosensing Vibrio cholerae with Genetically Engineered Escherichia coli.

    Science.gov (United States)

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

    2016-11-18

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

  13. Assessment of Escherichia coli isolates for In vitro biofilm production

    Directory of Open Access Journals (Sweden)

    A.I. Dadawala

    Full Text Available A total of 14 Escherichia coli isolates were assessed for their ability to produce biofilm in-vitro by slime production on Congo red agar medium (CRA and microtitre plate assay. Out of 14 isolates tested, 12 were slime producing on CRA as indicated by black colonies. The isolates of E.coli varied in their ability to produce biofilm on the surface of microtitre plate ranging from 0.101 to 0.543 ODm. Out of 14 isolates tested, 10 were positive for biofilm production employing criterion of blank corrected ODs9s > 0.1. Two of slime negative isolated were also negative for biofilm production where as the two slime positive isolates were found to be negative for biofilm production. [Veterinary World 2010; 3(8.000: 364-366

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Rotational tumbling of Escherichia coli aggregates under shear

    CERN Document Server

    Portela, R; Almeida, P L; Sobral, R G; Franco, J M; Leal, C R

    2016-01-01

    Growing living cultures of Escherichia coli bacteria were investigated using real-time in situ rheology and rheo-imaging measurements. In the early stages of growth (lag phase), and when subjected to a constant stationary shear, the viscosity slowly increases with the cell's population. As the bacteria reach the exponential phase of growth, the viscosity increases rapidly, with sudden and temporary abrupt decreases and recoveries. At a certain stage, corresponding grossly to the late phase of growth, when the population stabilises, the viscosity also keeps its maximum constant value, with drops and recoveries, for a long period of time. This complex rheological behaviour, which was observed to be shear strain dependent, is a consequence of two coupled effects: the cell density continuous increase and its changing interacting properties. Particular attention was given to the late phase of growth of E. coli populations under shear. Rheo-imaging measurements revealed, near the static plate, a rotational motion o...

  16. SILVER NANOPARTICLES-DISK DIFFUSION TEST AGAINST Escherichia coli ISOLATES

    Science.gov (United States)

    CUNHA, Francisco Afrânio; MAIA, Kamila Rocha; MALLMAN, Eduardo José Jucá; CUNHA, Maria da Conceição dos Santos Oliveira; MACIEL, Antonio Auberson Martins; de SOUZA, Ieda Pereira; MENEZES, Everardo Albuquerque; FECHINE, Pierre Basílio Almeida

    2016-01-01

    SUMMARY Nanotechnology can be a valuable ally in the treatment of infections. Silver nanoparticles (AgNPs) are structures that have antimicrobial activity. The aim of this study was to produce AgNPs by green methods, characterize these structures, and assess their antimicrobial activity against Escherichia coli associated with the antibiotic ciprofloxacin. AgNPs were characterized by spectroscopic and microscopic techniques. Antimicrobial activity was evaluated by the disk diffusion method against 10 strains of E. coli. The synthesized AgNPs showed a spherical shape and a size of 85.07 ± 12.86 nm (mean ± SD). AgNPs increased the activity of ciprofloxacin by 40% and may represent a new therapeutic option for the treatment of bacterial infections. PMID:27680178

  17. Bleomycin sensitivity in Escherichia coli is medium-dependent.

    Directory of Open Access Journals (Sweden)

    Tao Xu

    Full Text Available Bleomycin (BLM is a glycopeptide antibiotic and anti-tumor agent that targets primarily the furanose rings of DNA and in the presence of ferrous ions produces oxidative damage and DNA strand breaks. Escherichia coli cells growing in broth medium and exposed to low concentrations of BLM contain double-strand breaks and require homologous recombination to survive. To a lesser extent, the cells also require the abasic (AP endonucleases associated with base excision repair, presumably to repair oxidative damage. As expected, there is strong induction of the SOS system in treated cells. In contrast, E. coli cells growing in glucose or glycerol minimal medium are resistant to the lethal action of BLM and do not require either homologous recombination functions or AP-endonucleases for survival. DNA ligase activity, however, is needed for cells growing in minimal medium to resist the lethal effects of BLM. There is weak SOS induction in such treated cells.

  18. Production and purification of active snowdrop lectin in Escherichia coli.

    Science.gov (United States)

    Longstaff, M; Powell, K S; Gatehouse, J A; Raemaekers, R; Newell, C A; Hamilton, W D

    1998-02-15

    Recombinant snowdrop lectin was produced in Escherichia coli from a cDNA clone encoding mature Galanthus nivalis agglutinin. After induction with isopropylthio-beta-D-galactoside, inclusion bodies from E. coli were solubilised and the G. nivalis agglutinin purified by metal-affinity chromatography using a carboxy-terminal hexahistidine tag. The protein was refolded on the metal-affinity column prior to elution. After purification, the recombinant G. nivalis agglutinin agglutinated rabbit erythrocytes to a dilution similar to that determined for 'native' lectin purified from snowdrop, and showed similar specific binding to mannose. The toxicity of the recombinant G. nivalis agglutinin towards rice brown planthopper (Nilaparvata lugens) was shown to be similar to that of 'native' G. nivalis agglutinin when incorporated into an artificial diet. The recombinant G. nivalis agglutinin is thus functionally similar to 'native' snowdrop lectin.

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

    Science.gov (United States)

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

    2015-12-01

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

  20. Streptokinase: cloning, expression, and excretion by Escherichia coli.

    Science.gov (United States)

    Malke, H; Ferretti, J J

    1984-06-01

    Genomic DNA from Streptococcus equisimilis strain H46A was cloned in Escherichia coli by using the bacteriophage lambda replacement vector L47 and an in vitro packaging system. A casein/plasminogen overlay technique was used to screen the phage bank for recombinants carrying the streptokinase gene ( skc ). The gene was present with a frequency of 1 in 836 recombinants, and 10 independent clones containing skc were isolated and physically characterized. One recombinant clone was used to subclone skc in E. coli plasmid vectors. Plasmid pMF2 [10.4 kilobases (kb)] consisting of pACYC184 with a 6.4-kb H46A DNA fragment in the EcoRI site and pMF5 (6.9 kb) carrying a 2.5-kb fragment in the Pst I site of pBR322 were among the recombinant plasmids determining streptokinase production in three different E. coli host strains. Expression of skc was independent of its orientation in either vector, indicating that its own promoter was present and functional in E. coli. However, expression in pBR322 was more efficient in one orientation than in the other, suggesting that one or both of the bla gene promoters contributed to skc expression. Several lines of evidence, including proof obtained by the immunodiffusion technique, established the identity of E. coli streptokinase. Testing cell-free culture supernatant fluids, osmotic shock fluids, and sonicates of osmotically shocked cells for streptokinase activity revealed the substance to be present in all three principal locations, indicating that E. coli cells were capable of releasing substantial amounts of streptokinase into the culture medium.

  1. 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.

  2. 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.

  3. 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.

  4. Curli fimbria: an Escherichia coli adhesin associated with human cystitis.

    Science.gov (United States)

    Cordeiro, Melina Aparecida; Werle, Catierine Hirsch; Milanez, Guilherme Paier; Yano, Tomomasa

    2016-01-01

    Escherichia coli is the major causative agent of human cystitis. In this study, a preliminary molecular analysis carried out by PCR (polymerase chain reaction) demonstrated that 100% of 31 E. coli strains isolated from patients with recurrent UTIs (urinary tract infections) showed the presence of the curli fimbria gene (csgA). Curli fimbria is known to be associated with bacterial biofilm formation but not with the adhesion of human cystitis-associated E. coli. Therefore, this work aimed to study how curli fimbria is associated with uropathogenic E. coli (UPEC) as an adhesion factor. For this purpose, the csgA gene was deleted from strain UPEC-4, which carries three adhesion factor genes (csgA, fimH and ompA). The wild-type UPEC-4 strain and its mutant (ΔcsgA) were analyzed for their adhesion ability over HTB-9 (human bladder carcinoma), Vero (kidney cells of African green monkey) and HUVEC (human umbilical vein) cells in the presence of α-d-mannose. All the wild-type UPEC strains tested (100%) were able to adhere to all three cell types, while the UPEC-4 ΔcsgA mutant lost its adherence to HTB-9 but continued to adhere to the HUVEC and Vero cells. The results suggest that curli fimbria has an important role in the adhesion processes associated with human UPEC-induced cystitis.

  5. Redefining the requisite lipopolysaccharide structure in Escherichia coli.

    Science.gov (United States)

    Meredith, Timothy C; Aggarwal, Parag; Mamat, Uwe; Lindner, Buko; Woodard, Ronald W

    2006-02-17

    Gram-negative bacteria possess an asymmetric lipid bilayer surrounding the cell wall, the outer membrane (OM). The OM inner leaflet is primarily composed of various glycerophospholipids, whereas the outer leaflet predominantly contains the unique amphiphilic macromolecule, lipopolysaccharide (LPS or endotoxin). The majority of all gram-negative bacteria elaborate LPS containing at least one 2-keto 3-deoxy-D-manno-octulosonate (Kdo) molecule. The minimal LPS structure required for growth of Escherichia coli has long been recognized as two Kdo residues attached to lipid A, inextricably linking viability to toxicity. Here we report the construction and characterization of the nonconditional E. coli K-12 suppressor strain KPM22 that lacks Kdo and is viable despite predominantly elaborating the endotoxically inactive LPS precursor lipid IV(A). Our results challenge the established E. coli Kdo2-lipid A dogma, indicating that the previously observed and well-documented dependence of cell viability on the synthesis of Kdo stems from a lethal pleiotropy precipitated after the depletion of the carbohydrate, rather than an inherent need for the Kdo molecule itself as an indispensable structural component of the OM LPS layer. Inclusion of the inner membrane LPS transporter MsbA on a multicopy plasmid partially suppresses the lethal deltaKdo phenotype directly in the auxotrophic parent strain, suggesting increased rates of nonglycosylated lipid A transport can, in part, compensate for Kdo depletion. The unprecedented nature of a lipid IV(A) OM redefines the requisite LPS structure for viability in E. coli.

  6. Combinatorial biosynthesis of flavones and flavonols in Escherichia coli.

    Science.gov (United States)

    Miyahisa, Ikuo; Funa, Nobutaka; Ohnishi, Yasuo; Martens, Stefan; Moriguchi, Takaya; Horinouchi, Sueharu

    2006-06-01

    (2S)-Flavanones (naringenin and pinocembrin) are key intermediates in the flavonoid biosynthetic pathway in plants. Recombinant Escherichia coli cells containing four genes for a phenylalanine ammonia-lyase, cinnamate/coumarate:CoA ligase, chalcone synthase, and chalcone isomerase, in addition to the acetyl-CoA carboxylase, have been established for efficient production of (2S)-naringenin from tyrosine and (2S)-pinocembrin from phenylalanine. Further introduction of the flavone synthase I gene from Petroselinum crispum under the control of the T7 promoter and the synthetic ribosome-binding sequence in pACYCDuet-1 caused the E. coli cells to produce flavones: apigenin (13 mg/l) from tyrosine and chrysin (9.4 mg/l) from phenylalanine. Introduction into the E. coli cells of the flavanone 3beta-hydroxylase and flavonol synthase genes from the plant Citrus species led to production of flavonols: kaempferol (15.1 mg/l) from tyrosine and galangin (1.1 mg/l) from phenylalanine. The combinatorial biosynthesis of the flavones and flavonols in E. coli is promising for the construction of a library of various flavonoid compounds and un-natural flavonoids in bacteria.

  7. Magnetically-Actuated Escherichia coli System for Micro Lithography

    Science.gov (United States)

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

    2015-03-01

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

  8. 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.

  9. Modification of Artificial Oliogosaccharides in Recombinant Escherichia coli Cells

    Directory of Open Access Journals (Sweden)

    Tomohisa Kato

    2008-01-01

    Full Text Available Artificial oligosaccharides were modified using recombinant Escherichia coli cells that overexpress sialidase. Based on the principle of the saccharide primer method by using bacterial cells overexpressing enzymes related to oligosaccharide modification. Problem statement: It is very hard to obtain oligosaccharides, because they have complex and diverse structures with different linkage patterns and monosaccharide components. Approach: It has been known that various oligosaccharides can be synthesized in mammalian cells from saccharide primers. We attempted to modify oligosaccharides by using bacterial cells overexpressing enzymes related to oligosaccharide modification instead of mammalian cells. Results: The glycosphingolipid-like derivative GM3 was absorbed by the cell and desialylated by the expressed sialidase and the desialylated product was then secreted into the medium. The GM3-type oligosaccharides were not detected from the cell fraction of recombinant E. coli cells that overexpress sialidase differently from recombinant E. coli carrying only vector DNA (pET-19b. Conclusion/Recommendations: E. coli as well as mammalian cells may be used as a biocatalyst for oligosaccharide modification and production of artificial functional oligosaccharides.

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

    Science.gov (United States)

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

    2007-09-01

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

  11. Curli fimbria: an Escherichia coli adhesin associated with human cystitis

    Directory of Open Access Journals (Sweden)

    Melina Aparecida Cordeiro

    2016-06-01

    Full Text Available Abstract Escherichia coli is the major causative agent of human cystitis. In this study, a preliminary molecular analysis carried out by PCR (polymerase chain reaction demonstrated that 100% of 31 E. coli strains isolated from patients with recurrent UTIs (urinary tract infections showed the presence of the curli fimbria gene (csgA. Curli fimbria is known to be associated with bacterial biofilm formation but not with the adhesion of human cystitis-associated E. coli. Therefore, this work aimed to study how curli fimbria is associated with uropathogenic E. coli (UPEC as an adhesion factor. For this purpose, the csgA gene was deleted from strain UPEC-4, which carries three adhesion factor genes (csgA, fimH and ompA. The wild-type UPEC-4 strain and its mutant (ΔcsgA were analyzed for their adhesion ability over HTB-9 (human bladder carcinoma, Vero (kidney cells of African green monkey and HUVEC (human umbilical vein cells in the presence of α-D-mannose. All the wild-type UPEC strains tested (100% were able to adhere to all three cell types, while the UPEC-4 ΔcsgA mutant lost its adherence to HTB-9 but continued to adhere to the HUVEC and Vero cells. The results suggest that curli fimbria has an important role in the adhesion processes associated with human UPEC-induced cystitis.

  12. Genomic analysis of extra-intestinal pathogenic Escherichia coli urosepsis.

    Science.gov (United States)

    McNally, A; Alhashash, F; Collins, M; Alqasim, A; Paszckiewicz, K; Weston, V; Diggle, M

    2013-08-01

    Urosepsis is a bacteraemia infection caused by an organism previously causing an infection in the urinary tract of a patient, a diagnosis which has been classically confirmed by culture of the same species of bacteria from both blood and urine samples. Given the new insights afforded by sequencing technologies into the complicated population structures of infectious agents affecting humans, we sought to investigate urosepsis by comparing the genome sequences of blood and urine isolates of Escherichia coli from five patients with urosepsis. The results confirm the classical urosepsis hypothesis in four of the five cases, but also show the complex nature of extra-intestinal E. coli infection in the fifth case, where three distinct strains caused two distinct infections. Additionally, we show there is little to no variation in the bacterial genome as it progressed from urine to blood, and also present a minimal set of virulence genes required for bacteraemia in E. coli based on gene association. These suggest that most E. coli have the genetic propensity to cause bacteraemia.

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

    Science.gov (United States)

    Aydın Tutak, Gülten; Tuğrul, Hamdi Murat

    2015-01-01

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

  14. Atypical Enteropathogenic Escherichia coli Secretes Plasmid Encoded Toxin

    Directory of Open Access Journals (Sweden)

    Rita C. Ruiz

    2014-01-01

    Full Text Available Plasmid encoded toxin (Pet is a serine protease originally described in enteroaggregative Escherichia coli (EAEC prototype strain 042 whose entire characterization was essentially obtained from studies performed with the purified toxin. Here we show that Pet is not exclusive to EAEC. Atypical enteropathogenic Escherichia coli (aEPEC strains, isolated from diarrhea cases, express Pet and its detection in supernatants of infected HEp-2 cells coincides with the appearance of cell damage, which, in turn, were similar to those described with purified Pet. Pet secretion and the cytotoxic effects are time and culture medium dependent. In presence of DMEM supplemented with tryptone cell rounding and detachment were observed after just 5 h of incubation with the bacteria. In the absence of tryptone, the cytotoxic effects were detected only after 24 h of infection. We also show that, in addition to the prototype EAEC, other pet+ EAEC strains, also isolated from diarrhea cases, induce cellular damage in the same degree as the aEPEC. The cytotoxic effects of EAEC and aEPEC strains were significantly reduced in the presence of a serine protease inhibitor or anti-Pet IgG serum. Our results show a common aspect between the aEPEC and EAEC and provide the first evidence pointing to a role of Pet in aEPEC pathogenesis.

  15. Kinetics of Schiff base on Escherichia coli by microcalorimetry

    Institute of Scientific and Technical Information of China (English)

    许名飞; 李新海; 万洪文; 刘义

    2003-01-01

    The influence of four kinds of Schiff bases on a strain of Escherichia coli was studied by microcalorimetry. Differences in their capabilities of suppressing the metabolism of this bacterium were observed. The results show that the extent and duration of the inhibitory effect on the metabolism as judged from the multiplication rate constant, k, varies with different Schiff bases.The multiplication rate constant k, of Escherichia coli (in log phase) in the presence of Mo-salicylioaldehyde-thiadizole, Mo-piperonaldehyde-thiosemicarbazone and Mo-3-methoxy-salicylicaldehyde-thiadizole decreases with the increase of concentrations of compounds c, and the relationships between k and c, maximum heat production rate Pm and c, peak time of growth curves tp and c are of linearity. For Mo-6-nitro-pieronalde-thiosemicarbazone, the multiplication rate constant is constant irrespective of variation in concentration. The sequence of antibiotic activity of Schiff base is: Mo-salicylioaldehyde-thiadizole>Mo-3-methoxy-salicylicaldehyde-thiadizole>Mo-piperonaldehyde-thiosemicarbazone> 6-nitro-pieronalde-thiosemicarbazone.

  16. Localization of the Tat translocon components in Escherichia coli.

    Science.gov (United States)

    Berthelmann, Felix; Brüser, Thomas

    2004-07-02

    The Tat system has the ability to translocate folded proteins across the bacterial cytoplasmic membrane. In Escherichia coli, three functionally different translocon components have been identified, namely TatA, TatB, and TatC. These proteins were fused to the green fluorescent protein (GFP) and their localization was determined by confocal laser scanning fluorescence microscopy. TatA-GFP was distributed in the membrane, often with higher abundance at the poles. TatB-GFP was found in distinct spots at the poles of the cells. The fluorescence of TatC-GFP was very low and required a constitutive expression system to become higher than background, but then appearing polar. All three constructs complemented the chain-formation phenotype of corresponding mutant strains, indicating the functionality of the fusion proteins. TatB-GFP and TatC-GFP also complemented TMAO respiration deficiency and TatA-GFP the SDS-sensitivity of the mutant strains. The localization of the translocon-GFP fusions coincides with the fluorescence pattern of GFP fusions to Tat substrate signal sequences. We suggest that the active translocon complexes are mainly present at polar positions in Escherichia coli.

  17. A Novel Putrescine Exporter SapBCDF of Escherichia coli.

    Science.gov (United States)

    Sugiyama, Yuta; Nakamura, Atsuo; Matsumoto, Mitsuharu; Kanbe, Ayaka; Sakanaka, Mikiyasu; Higashi, Kyohei; Igarashi, Kazuei; Katayama, Takane; Suzuki, Hideyuki; Kurihara, Shin

    2016-12-16

    Recent research has suggested that polyamines (putrescine, spermidine, and spermine) in the intestinal tract impact the health of animals either negatively or positively. The concentration of polyamines in the intestinal tract results from the balance of uptake and export of the intestinal bacteria. However, the mechanism of polyamine export from bacterial cells to the intestinal lumen is still unclear. In Escherichia coli, PotE was previously identified as a transporter responsible for putrescine excretion in an acidic growth environment. We observed putrescine concentration in the culture supernatant was increased from 0 to 50 μm during growth of E. coli under neutral conditions. Screening for the unidentified putrescine exporter was performed using a gene knock-out collection of E. coli, and deletion of sapBCDF significantly decreased putrescine levels in the culture supernatant. Complementation of the deletion mutant with the sapBCDF genes restored putrescine levels in the culture supernatant. Additionally, the ΔsapBCDF strain did not facilitate uptake of putrescine from the culture supernatant. Quantification of stable isotope-labeled putrescine derived from stable isotope-labeled arginine supplemented in the medium revealed that SapBCDF exported putrescine from E. coli cells to the culture supernatant. It was previously reported that SapABCDF of Salmonella enterica sv. typhimurium and Haemophilus influenzae conferred resistance toantimicrobial peptides; however, the E. coli ΔsapBCDF strain did not affect resistance to antimicrobial peptide LL-37. These results strongly suggest that the natural function of the SapBCDF proteins is the export of putrescine.

  18. Brote causado por Escherichia coli en Chalco, México

    Directory of Open Access Journals (Sweden)

    Cortés-Ortiz Iliana Alejandra

    2002-01-01

    Full Text Available Objetivo. Identificar el agente causal del brote de diarrea asociado con el desbordamiento del canal de aguas negras en Chalco. Material y métodos. Estudio retrospectivo y transversal, efectuado en el Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE, de la Secretaría de Salud, con 1 550 hisopos rectales para el aislamiento e identificación bioquímica de V. cholerae y enterobacterias, obtenidos de la población del Valle de Chalco, que presentó diarrea y vómito durante el desastre natural acontecido el 31 de mayo de 2000. El análisis de los resultados se efectuó por la diferencia entre las proporciones de dos poblaciones (prueba de Ji cuadrada. Las cepas de E. coli se hibridaron por "colony blot" para los grupos ETEC, EIEC, EPEC y EHEC. Resultados. El 0.45% correspondió a Salmonella: S. agona, S. infantis, S. enteritidis, S. muenchen, S. typhimurium; 0.06% a Shigella flexneri 3a, y 76.6% a E. coli: 62.2% a ETEC (44.6 % con LT, 11.2% con ST, y 44.1% con ambas sondas, 0.84% a EIEC (sonda ial, 0.84% a EPEC (sonda bundle-forming pilus BFP, 0.08% a E. coli enterohemorrágica no-O157:H7 (sonda pCVD419, y 36.02% no hibridó. No se encontró asociación entre E. coli patógena con la edad y género. Conclusiones. Escherichia coli podría ser responsable del brote de diarrea. Es importante conocer el agente etiológico del brote para encaminar las estrategias en el estudio y control sanitario del mismo.

  19. Redesigning Escherichia coli metabolism for anaerobic production of isobutanol.

    Science.gov (United States)

    Trinh, Cong T; Li, Johnny; Blanch, Harvey W; Clark, Douglas S

    2011-07-01

    Fermentation enables the production of reduced metabolites, such as the biofuels ethanol and butanol, from fermentable sugars. This work demonstrates a general approach for designing and constructing a production host that uses a heterologous pathway as an obligately fermentative pathway to produce reduced metabolites, specifically, the biofuel isobutanol. Elementary mode analysis was applied to design an Escherichia coli strain optimized for isobutanol production under strictly anaerobic conditions. The central metabolism of E. coli was decomposed into 38,219 functional, unique, and elementary modes (EMs). The model predictions revealed that during anaerobic growth E. coli cannot produce isobutanol as the sole fermentative product. By deleting 7 chromosomal genes, the total 38,219 EMs were constrained to 12 EMs, 6 of which can produce high yields of isobutanol in a range from 0.29 to 0.41 g isobutanol/g glucose under anaerobic conditions. The remaining 6 EMs rely primarily on the pyruvate dehydrogenase enzyme complex (PDHC) and are typically inhibited under anaerobic conditions. The redesigned E. coli strain was constrained to employ the anaerobic isobutanol pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and overexpression of 5 genes. Here we present the design, construction, and characterization of an isobutanol-producing E. coli strain to illustrate the approach. The model predictions are evaluated in relation to experimental data and strategies proposed to improve anaerobic isobutanol production. We also show that the endogenous alcohol/aldehyde dehydrogenase AdhE is the key enzyme responsible for the production of isobutanol and ethanol under anaerobic conditions. The glycolytic flux can be controlled to regulate the ratio of isobutanol to ethanol production.

  20. Immobilizing live Escherichia coli for AFM studies of surface dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Lonergan, N.E.; Britt, L.D.; Sullivan, C.J., E-mail: sullivcj@evms.edu

    2014-02-01

    Atomic force microscopy (AFM) is a probe-based technique that permits high resolution imaging of live bacterial cells. However, stably immobilizing cells to withstand the probe-based lateral forces remains an obstacle in AFM mediated studies, especially those of live, rod shaped bacteria in nutrient media. Consequently, AFM has been under-utilized in the research of bacterial surface dynamics. The aim of the current study was to immobilize a less adherent Escherichia coli strain in a method that both facilitates AFM imaging in nutrient broth and preserves overall cell viability. Immobilization reagents and buffers were systematically evaluated and the cell membrane integrity was monitored in all sample preparations. As expected, the biocompatible gelatin coated surfaces facilitated stable cell attachment in lower ionic strength buffers, yet poorly immobilized cells in higher ionic strength buffers. In comparison, poly-L-lysine surfaces bound cells in both low and high ionic strength buffers. The benefit of the poly-L-lysine binding capacity was offset by the compromised membrane integrity exhibited by cells on poly-L-lysine surfaces. However, the addition of divalent cations and glucose to the immobilization buffer was found to mitigate this unfavorable effect. Ultimately, immobilization of E. coli cells on poly-L-lysine surfaces in a lower ionic strength buffer supplemented with Mg{sup 2+} and Ca{sup 2+} was determined to provide optimal cell attachment without compromising the overall cell viability. Cells immobilized in this method were stably imaged in media through multiple division cycles. Furthermore, permeability assays indicated that E. coli cells recover from the hypoosmotic stress caused by immobilization in low ionic strength buffers. Taken together, this data suggests that stable immobilization of viable cells on poly-L-lysine surfaces can be accomplished in lower ionic strength buffers that are supplemented with divalent cations for membrane

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

    Directory of Open Access Journals (Sweden)

    Juan Puño-Sarmiento

    2014-08-01

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

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

    Science.gov (United States)

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

    2015-10-01

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

  3. Rotational tumbling of Escherichia coli aggregates under shear

    Science.gov (United States)

    Portela, R.; Patrício, P.; Almeida, P. L.; Sobral, R. G.; Franco, J. M.; Leal, C. R.

    2016-12-01

    Growing living cultures of Escherichia coli bacteria are investigated using real-time in situ rheology and rheoimaging measurements. In the early stages of growth (lag phase) and when subjected to a constant stationary shear, the viscosity slowly increases with the cell's population. As the bacteria reach the exponential phase of growth, the viscosity increases rapidly, with sudden and temporary abrupt decreases and recoveries. At a certain stage, corresponding grossly to the late phase of growth, when the population stabilizes, the viscosity also keeps its maximum constant value, with drops and recoveries, for a long period of time. This complex rheological behavior, which is observed to be shear strain dependent, is a consequence of two coupled effects: the cell density continuous increase and its changing interacting properties. Particular attention is given to the late phase of growth of E. coli populations under shear. Rheoimaging measurements reveal, near the static plate, a rotational motion of E. coli aggregates, collectively tumbling and flowing in the shear direction. This behavior is interpreted in the light of a simple theoretical approach based on simple rigid body mechanics.

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

    Science.gov (United States)

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

    2016-06-21

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

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

    Directory of Open Access Journals (Sweden)

    Tammy eGonzalez

    2015-10-01

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

  6. Improving alkane synthesis in Escherichia coli via metabolic engineering.

    Science.gov (United States)

    Song, Xuejiao; Yu, Haiying; Zhu, Kun

    2016-01-01

    Concerns about energy security and global petroleum supply have made the production of renewable biofuels an industrial imperative. The ideal biofuels are n-alkanes in that they are chemically and structurally identical to the fossil fuels and can "drop in" to the transportation infrastructure. In this work, an Escherichia coli strain that produces n-alkanes was constructed by heterologous expression of acyl-acyl carrier protein (ACP) reductase (AAR) and aldehyde deformylating oxygenase (ADO) from Synechococcus elongatus PCC7942. The accumulation of alkanes ranged from 3.1 to 24.0 mg/L using different expressing strategies. Deletion of yqhD, an inherent aldehyde reductase in E. coli, or overexpression of fadR, an activator for fatty acid biosynthesis, exhibited a nearly twofold increase in alkane titers, respectively. Combining yqhD deletion and fadR overexpression resulted in a production titer of 255.6 mg/L in E. coli, and heptadecene was the most abundant product.

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

    Science.gov (United States)

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

    2014-08-28

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

  8. Metabolic engineering of Escherichia coli for the production of xylonate.

    Directory of Open Access Journals (Sweden)

    Yujin Cao

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

  9. Recombinant expression of Streptococcus pneumoniae capsular polysaccharides in Escherichia coli.

    Science.gov (United States)

    Kay, Emily J; Yates, Laura E; Terra, Vanessa S; Cuccui, Jon; Wren, Brendan W

    2016-04-01

    Currently, Streptococcus pneumoniae is responsible for over 14 million cases of pneumonia worldwide annually, and over 1 million deaths, the majority of them children. The major determinant for pathogenesis is a polysaccharide capsule that is variable and is used to distinguish strains based on their serotype. The capsule forms the basis of the pneumococcal polysaccharide vaccine (PPV23) that contains purified capsular polysaccharide from 23 serotypes, and the pneumococcal conjugate vaccine (PCV13), containing 13 common serotypes conjugated to CRM197 (mutant diphtheria toxin). Purified capsule from S. pneumoniae is required for pneumococcal conjugate vaccine production, and costs can be prohibitively high, limiting accessibility of the vaccine in low-income countries. In this study, we demonstrate the recombinant expression of the capsule-encoding locus from four different serotypes of S. pneumoniae within Escherichia coli. Furthermore, we attempt to identify the minimum set of genes necessary to reliably and efficiently express these capsules heterologously. These E. coli strains could be used to produce a supply of S. pneumoniae serotype-specific capsules without the need to culture pathogenic bacteria. Additionally, these strains could be applied to synthetic glycobiological applications: recombinant vaccine production using E. coli outer membrane vesicles or coupling to proteins using protein glycan coupling technology.

  10. Escherichia coli Meningitis after Rotavirus Gastroenteritis in an Infant

    Science.gov (United States)

    Vermezoglu, Oznur; Ocal Topcu, Didem; Karbuz, Adem; Hacihamdioglu, Bulent

    2016-01-01

    Although rotavirus gastroenteritis is quite common in the pediatric population, secondary bacterial sepsis following rotavirus infection is a rare clinical entity. Gram-negative bacilli are the fifth most common cause of meningitis in infants but this infection rarely occurs after gastroenteritis. Here, we report a 2.5-month-old infant who developed Escherichia coli (E. coli) meningitis after acute rotavirus gastroenteritis. The 2.5-month-old male infant with fever, vomiting, and watery diarrhea that started 1 day earlier was admitted to the hospital. Rotavirus antigen in stool sample was positive. He was hospitalized, and fever was measured at 39.5°C on the second day. Lumbar puncture was done for suspicion of meningitis, and cerebrospinal fluid (CSF) findings suggested meningitis. Intravenous vancomycin and cefotaxime were started empirically. Since E. coli reproduction was seen in blood culture and CSF culture, treatment was continued with cefotaxime. The patient was discharged with minimal midlevel hydrocephalus findings in cranial ultrasonography and magnetic resonance imaging following 21 days of antibiotics treatment. Septicemia development following rotavirus gastroenteritis is an extremely rare clinical condition. It is vital to start prompt antibiotic treatment as soon as the diagnosis of secondary bacterial infection is made because of high mortality and morbidity rates.

  11. 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.

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

    Science.gov (United States)

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

    1993-09-01

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

  13. Characterization of the YdeO regulon in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Yuki Yamanaka

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

  14. Characterization of the YdeO regulon in Escherichia coli.

    Science.gov (United States)

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

    2014-01-01

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

  15. Multiple Antimicrobial Resistance of Escherichia coli Isolated from Chickens in Iran

    OpenAIRE

    Reza Talebiyan; Mehdi Kheradmand; Faham Khamesipour; Mohammad Rabiee-Faradonbeh

    2014-01-01

    Antimicrobial agents are used extremely in order to reduce the great losses caused by Escherichia coli infections in poultry industry. In this study, 318 pathogenic Escherichia coli (APEC) strains isolated from commercial broiler flocks with coli-septicemia were examined for antimicrobials of both veterinary and human significance by disc diffusion method. Multiple resistances to antimicrobial agents were observed in all the isolates. Resistance to the antibiotics was as follows: Tylosin (88....

  16. Characterization and Virulence Assessment of Two 091:821 Enterohemorrhagic Escherichia Coli Isolates

    Science.gov (United States)

    1993-04-30

    Law, S. B. Richardson, M. petrie, J. L. Brunton, and x. Karaali. 1987. Glycolipid binding of natural and recomninant Escherichi coli produced...HAll AIR FORCE MEDICAL CENTER Title of Dissertation: ·Characterization and Virulence Assessment of Two 091: H21 Enterohemorrhagic Escherichia coli ...the thesis manuscript entitled : of any copyrighted "Characterization and Virulence Assessment of Two 091:H21 Enterohemorrhagic Escherichia coli

  17. Extraintestinal pathogenic Escherichia coli are associated with intestinal inflammation in patients with ulcerative colitis

    DEFF Research Database (Denmark)

    Mirsepasi-Lauridsen, Hengameh C; Halkjaer, Sofie Ingdam; Mortensen, Esben Munk;

    2016-01-01

    E. coli of the phylogenetic group B2 harbouring Extra intestinal Pathogenic Escherichia coli (ExPEC) genes are frequently seen as colonizers of the intestine in patients with active ulcerative colitis (UC). In this study, we describe the influence of E. coli Nissle (EcN) B2 as add-on treatment to...... scores in comparison to patients colonized with E. coli A and D (p treatment of UC patients with E. coli Nissle (B2) does not promote clinical remission and active UC patients colonized with E. coli B2 have an increased intestinal inflammation.......E. coli of the phylogenetic group B2 harbouring Extra intestinal Pathogenic Escherichia coli (ExPEC) genes are frequently seen as colonizers of the intestine in patients with active ulcerative colitis (UC). In this study, we describe the influence of E. coli Nissle (EcN) B2 as add-on treatment...

  18. Azorean wild rabbits as reservoirs of antimicrobial resistant Escherichia coli.

    Science.gov (United States)

    Marinho, Catarina; Igrejas, Gilberto; Gonçalves, Alexandre; Silva, Nuno; Santos, Tiago; Monteiro, Ricardo; Gonçalves, David; Rodrigues, Tiago; Poeta, Patrícia

    2014-12-01

    Antibiotic resistance in bacteria is an increasing problem that is not only constrained to the clinical setting but also to other environments that can lodge antibiotic resistant bacteria and therefore they may serve as reservoirs of genetic determinants of antibiotic resistance. One hundred and thirty-six faecal samples from European wild rabbits (Oryctolagus cuniculus algirus) were collected on São Jorge Island in Azores Archipelago, and analysed for Escherichia coli isolates. Seventy-seven isolates (56.6%) were recovered and studied for antimicrobial resistance, one isolate per positive sample. Thirteen (16.9%), 19 (24.7%), 25 (32.4%) and 20 (26%) isolates were ascribed to A, B1, B2 and D phylogenetic groups, respectively, by specific primer polymerase chain reaction. Different E. coli isolates were found to be resistant to ampicillin (16.9%), tetracycline (1.3%), streptomycin (42.9%), sulfamethoxazole-trimethoprim (1.3%), amikacin (1.3%), tobramycin (2.6%) and nalidixic acid (1.3%). Additionally, the blaTEM, tetA, strA/strB, aadA, sul1, intI, intI2 and qacEΔ+sul1 genes were found in most resistant isolates. This study showed that E. coli from the intestinal tract of wild rabbits from Azores Archipelago are resistant to widely prescribed antibiotics in medicine and they constitute a reservoir of antimicrobial resistant genes, which may play a significant role in the spread of antimicrobial resistance. Therefore, antibiotic resistant E. coli from Azorean wild rabbits may represent an ecological and public health problem.

  19. Application of biotinylated and 32P probes for detection of P-fimbriae in urinary E. coli.

    Science.gov (United States)

    Jusková, E; Ciznár, I

    1993-01-01

    Escherichia coli is the common causative agent of urinary tract infections. Twenty-six strains of Escherichia coli were isolated from children with pyelonephritis, symptomatic urinary tract infections and asymptomatic bacteriuria. Biotinylated and 32P-DNA probes were prepared for detection of P-fimbriae in the isolates. Of the 13 strains isolated from patients with pyelonephritis 11 were positive for the presence of the P gene by both probes. Strains isolated from cases of symptomatic urinary tract infections revealed the presence of P gene only in three samples of the total of nine isolated. None of the isolated E. coli strains from asymptomatic bacteriuria was found positive for the presence of the P gene. The biotinylated probe was simple and easily applicable in standard laboratory conditions and therefore the authors recommend it for use in diagnostic laboratories.

  20. Chemostat modeling of Escherichia coli persistence in conventionalized mono-associated and streptomycin-treated mice

    DEFF Research Database (Denmark)

    Rang, C.; Midtvedt, T.; Molin, Søren;

    2001-01-01

    We have previously shown that Escherichia coli BJ4 has similar doubling time in mice that are mono-associated (having only the inoculated E. coli BJ4) or streptomycin-treated (having mainly gram-positive bacteria plus the inoculated E. coli BJ4). We also showed that when the mice were conventiona...

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

    Science.gov (United States)

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

    2004-01-01

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

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

    Science.gov (United States)

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

  3. A rare presentation of ischemic pseudomembranous colitis due to Escherichia coli O157:H7.

    Science.gov (United States)

    Kendrick, Jessica B; Risbano, Michael; Groshong, Steve D; Frankel, Stephen K

    2007-07-15

    Escherichia coli Ol57:H7 infection ranges from mild diarrheal illness to severe hemorrhagic colitis but may rarely be complicated by pseudomembranous colitis and/or necrosis. Herein, we report a sporadic case of ischemic E. coli Ol57:H7 pseudomembranous colitis in an adult that occurred during a national outbreak of E. coli Ol57:H7 in the United States.

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

    Science.gov (United States)

    Escherichia coli (E. coli) urinary tract infections (UTIs) are becoming a serious problem both for pets and humans (zoonosis) due to the close contact and to the increasing resistance to antibiotics. Canine E. coli represents a good experimental model useful to study this pathology. Moreover, as des...

  5. Control analysis of the dependence of Escherichia coli physiology on the H+ -ATPase

    DEFF Research Database (Denmark)

    Jensen, Peter Ruhdal; Michelsen, Ole; Westerhoff, Hans V.

    1993-01-01

    The H+-ATPase plays a central role in Escherichia coli free-energy transduction and hence in E. coli physiology. We here investigate the extent to which this enzyme also controls the growth rate, growth yield, and respiratory rate of E. coli. We modulate the expression of the atp operon and deter...

  6. The location of the restriction locus for λ·K in Escherichia coli B

    NARCIS (Netherlands)

    Hoekstra, W.P.M.; Haan, P.G. de

    1965-01-01

    Analysis of recombinants from E. coli K 12 Hfr × E. coli B F− crosses showed that one locus on the chromosome of Escherichia coli, controlling restriction and probably also the modification of phage λ, is located between the leading point of the Hfr H chromosome and the locus for threonine synthesis

  7. Construction and shuttling of novel bifunctional vectors for Streptomyces spp. and Escherichia coli.

    OpenAIRE

    Neesen, K; Volckaert, G.

    1989-01-01

    Shuttle vectors for gene transfer between Streptomyces spp. and Escherichia coli have been constructed by fusion of an artificial multicopy E. coli replicon and DNA fragments of pIJ702. Stable transfer to Streptomyces lividans was obtained. Marked differences in transformation efficiency were observed when plasmid DNA isolated from E. coli GM119 was used instead of that from strain HB101.

  8. DIARRHEA, UROSEPSIS AND HEMOLYTIC UREMIC SYNDROME CAUSED BY THE SAME HETEROPATHOGENIC ESCHERICHIA COLI STRAIN

    NARCIS (Netherlands)

    Ang, C. Wim; Bouts, Antonia H. M.; Rossen, John W. A.; Van der Kuip, Martijn; Van Heerde, Marc; Bokenkamp, Arend

    2016-01-01

    We describe an 8-month-old girl with diarrhea, urosepsis and hemolytic uremic syndrome caused by Escherichia coli. Typing of cultured E. coli strains from urine and blood revealed the presence of virulence factors from multiple pathotypes of E. coli. This case exemplifies the genome plasticity of E.

  9. Characterization of pathogenic Escherichia coli isolated from humans in Austria : phenotypes, toxin gene types and epidemiology

    NARCIS (Netherlands)

    Wagner, M; Allerberger, F; Manafi, M; Lindner, G; Friedrich, A W; Sonntag, A-K; Foissy, H

    2004-01-01

    One hundred and ten clinical Escherichia coli isolates of serovar O157 (n = 102) and O26 (n = 8) were characterized for the presence of putative virulence genes by PCR. All but one of these isolates contained the eae gene. The EHEC-hly gene could be detected in all E. coli O157 and in 50% of E. coli

  10. Comparative analysis of antibiotic resistance and phylogenetic group patterns in human and porcine urinary tract infectious Escherichia coli

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Nielsen, E.M.; Krag, L.

    2009-01-01

    to relatively benign asymptomatic bacteriuria strains. Here we analyse a spectrum of porcine and human UTI E. coli strains with respect to their antibiotic resistance patterns and their phylogenetic groups, determined by multiplex PCR. The clonal profiles of the strains differed profoundly; whereas human...... strains predominantly belonged to clonal types B2 and D, these were not seen among the porcine strains, which all belonged to the E. coli clonal groups A and B1. Contrary to the human strains, the majority of the porcine strains were multidrug resistant. The distinct profiles of the porcine strains...... suggest selective pressure due to extensive antibiotic use....

  11. 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

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

    Science.gov (United States)

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

    2015-09-01

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

  13. Alpha-hemolysin from Escherichia coli uses endogenous amplification through P2X receptor activation to induce hemolysis

    DEFF Research Database (Denmark)

    Skals, Marianne; Jørgensen, Niklas Rye; Leipziger, Jens;

    2009-01-01

    Escherichia coli is the dominant facultative bacterium in the normal intestinal flora. E. coli is, however, also responsible for the majority of serious extraintestinal infections. There are distinct serotypical differences between facultative and invasive E. coli strains. Invasive strains...

  14. α-hemolysin from Escherichia coli uses endogenous amplification through P2X receptor activation to induce hemolysis

    DEFF Research Database (Denmark)

    Skals, Marianne Gerberg; Jørgensen, Niklas R; Leipziger, Jens Georg;

    2009-01-01

    Escherichia coli is the dominant facultative bacterium in the normal intestinal flora. E. coli is, however, also responsible for the majority of serious extraintestinal infections. There are distinct serotypical differences between facultative and invasive E. coli strains. Invasive strains...

  15. Plasmolysis during the division cycle of Escherichia coli.

    Science.gov (United States)

    Olijhoek, A J; Van Eden, C G; Trueba, F J; Pas, E; Nanninga, N

    1982-10-01

    Cells of Escherichia coli were plasmolyzed with sucrose. They were classified according to length by way of electron micrographs taken from samples prepared by agar filtration. The percentage of plasmolyzed cells increased about two- and threefold between mean cell sizes of newborn and separating cells. However, dividing cells were less frequently plasmolyzed than nondividing cells of the same length class. Analysis of cell halves (prospective daughters) in dividing cells showed that they behaved as independent cellular units with respect to plasmolysis. The results indicate that compressibility of the protoplast (given a certain plasmolysis space) is inversely related to cell size. That a dividing cell does not react as one osmotic compartment to osmotic stress may suggest that cell size-dependent strength of the cell membrane-cell wall association, rather than variation in turgor, plays a role during the cell division cycle.

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

    Science.gov (United States)

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

    2014-01-01

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

  17. Collective motion in an active suspension of Escherichia coli bacteria

    Science.gov (United States)

    Gachelin, J.; Rousselet, A.; Lindner, A.; Clement, E.

    2014-02-01

    We investigate experimentally the emergence of collective motion in the bulk of an active suspension of Escherichia coli bacteria. When increasing the concentration from a dilute to a semi-dilute regime, we observe a continuous crossover from a dynamical cluster regime to a regime of ‘bio-turbulence’ convection patterns. We measure a length scale characterizing the collective motion as a function of the bacteria concentration. For bacteria fully supplied with oxygen, the increase of the correlation length is almost linear with concentration and at the largest concentrations tested, the correlation length could be as large as 24 bacterial body sizes (or 7-8 when including the flagella bundle). In contrast, under conditions of oxygen shortage the correlation length saturates at a value of around 7 body lengths.

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

    CERN Document Server

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

    2012-01-01

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

  19. SOS response induces persistence to fluoroquinolones in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Tobias Dörr

    2009-12-01

    Full Text Available Bacteria can survive antibiotic treatment without acquiring heritable antibiotic resistance. We investigated persistence to the fluoroquinolone ciprofloxacin in Escherichia coli. Our data show that a majority of persisters to ciprofloxacin were formed upon exposure to the antibiotic, in a manner dependent on the SOS gene network. These findings reveal an active and inducible mechanism of persister formation mediated by the SOS response, challenging the prevailing view that persisters are pre-existing and formed purely by stochastic means. SOS-induced persistence is a novel mechanism by which cells can counteract DNA damage and promote survival to fluoroquinolones. This unique survival mechanism may be an important factor influencing the outcome of antibiotic therapy in vivo.

  20. The folding characteristics of tryptophanase from Escherichia coli.

    Science.gov (United States)

    Mizobata, T; Kawata, Y

    1995-02-01

    The unfolding and refolding characteristics of Escherichia coli tryptophanase (tryptophan indole-lyase) [EC 4.1.99.1] in guanidine hydrochloride were studied. Tryptophanase unfolded by first dissociating its coenzyme, pyridoxal 5'-phosphate, from the active site. This dissociation caused a significant destabilization of structure, and global unfolding of the protein followed. During this global unfolding step, an intermediate was formed which had a strong tendency to aggregate irreversibly, as detected by light scattering experiments. Tryptophanase was unable to refold quantitatively after unfolding in 4 M guanidine hydrochloride. The low refolding yield was due to non-specific aggregation which occurs during refolding. Various conditions which limited this aggregation were probed, and it was found that by initiating the refolding reaction at low temperature, the aggregation of tryptophanase folding intermediates during the reaction could be avoided to a certain extent, and the refolding yield improved.

  1. Antibacterial Coating for Elimination of Pseudomonas aeruginosa and Escherichia coli

    Directory of Open Access Journals (Sweden)

    Zainal Abidin Ali

    2014-01-01

    Full Text Available A polymer antibacterial surface has been successfully developed. The coating system used silane as binder and Ag particles as antibacterial agent. The silver was synthesized using precipitation method. X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, Brunauer-Emmett-Teller (BET tests, energy-dispersive X-ray spectroscopy (EDX, and X-ray photoelectron spectroscopy (XPS were carried out to evaluate the silver particles. Antibacterial properties of the coating system were tested against gram-negative bacteria, namely, Pseudomonas aeruginosa and Escherichia coli. Different amounts of Ag were used in the coating to optimize its usage. The Japanese International Standard, JISZ2801, was used for bacteria test and the surface developed complies with the standard being antibacterial.

  2. Dynamics of Escherichia coli chromosome segregation during multifork replication.

    Science.gov (United States)

    Nielsen, Henrik J; Youngren, Brenda; Hansen, Flemming G; Austin, Stuart

    2007-12-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks.

  3. Dynamics of Escherichia coli Chromosome Segregation during Multifork Replication▿

    Science.gov (United States)

    Nielsen, Henrik J.; Youngren, Brenda; Hansen, Flemming G.; Austin, Stuart

    2007-01-01

    Slowly growing Escherichia coli cells have a simple cell cycle, with replication and progressive segregation of the chromosome completed before cell division. In rapidly growing cells, initiation of replication occurs before the previous replication rounds are complete. At cell division, the chromosomes contain multiple replication forks and must be segregated while this complex pattern of replication is still ongoing. Here, we show that replication and segregation continue in step, starting at the origin and progressing to the replication terminus. Thus, early-replicated markers on the multiple-branched chromosomes continue to separate soon after replication to form separate protonucleoids, even though they are not segregated into different daughter cells until later generations. The segregation pattern follows the pattern of chromosome replication and does not follow the cell division cycle. No extensive cohesion of sister DNA regions was seen at any growth rate. We conclude that segregation is driven by the progression of the replication forks. PMID:17905986

  4. Combinatorial method for overexpression of membrane proteins in Escherichia coli.

    Science.gov (United States)

    Leviatan, Shani; Sawada, Keisuke; Moriyama, Yoshinori; Nelson, Nathan

    2010-07-30

    Membrane proteins constitute 20-30% of all proteins encoded by the genome of various organisms. Large amounts of purified proteins are required for activity and crystallization attempts. Thus, there is an unmet need for a heterologous membrane protein overexpression system for purification, crystallization, and activity determination. We developed a combinatorial method for overexpressing and purifying membrane proteins using Escherichia coli. This method utilizes short hydrophilic bacterial proteins, YaiN and YbeL, fused to the ends of the membrane proteins to serve as facilitating factors for expression and purification. Fourteen prokaryotic and mammalian membrane proteins were expressed using this system. Moderate to high expression was obtained for most proteins, and detergent solubilization combined with a short purification process produced stable, monodispersed membrane proteins. Five of the mammalian membrane proteins, overexpressed using our system, were reconstituted into liposomes and exhibited transport activity comparable with the native transporters.

  5. Combinatorial Method for Overexpression of Membrane Proteins in Escherichia coli*

    Science.gov (United States)

    Leviatan, Shani; Sawada, Keisuke; Moriyama, Yoshinori; Nelson, Nathan

    2010-01-01

    Membrane proteins constitute 20–30% of all proteins encoded by the genome of various organisms. Large amounts of purified proteins are required for activity and crystallization attempts. Thus, there is an unmet need for a heterologous membrane protein overexpression system for purification, crystallization, and activity determination. We developed a combinatorial method for overexpressing and purifying membrane proteins using Escherichia coli. This method utilizes short hydrophilic bacterial proteins, YaiN and YbeL, fused to the ends of the membrane proteins to serve as facilitating factors for expression and purification. Fourteen prokaryotic and mammalian membrane proteins were expressed using this system. Moderate to high expression was obtained for most proteins, and detergent solubilization combined with a short purification process produced stable, monodispersed membrane proteins. Five of the mammalian membrane proteins, overexpressed using our system, were reconstituted into liposomes and exhibited transport activity comparable with the native transporters. PMID:20525689

  6. Uropathogenic Escherichia coli Epigenetically Manipulate Host Cell Death Pathways.

    Science.gov (United States)

    Zhang, Zhengguo; Wang, Ming; Eisel, Florian; Tchatalbachev, Svetlin; Chakraborty, Trinad; Meinhardt, Andreas; Bhushan, Sudhanshu

    2016-04-01

    Urinary tract infections caused by uropathogenic Escherichia coli (UPEC) pathovars belong to the most frequent infections in human. It is well established that UPEC can subvert innate immune responses, but the role of UPEC in interfering with host cell death pathways is not known. Here, we show that UPEC abrogates activation of the host cell prosurvival protein kinase B signaling pathway, which results in the activation of mammalian forkhead box O (FOXO) transcription factors. Although FOXOs were localized in the nucleus and showed increased DNA-binding activity, no change in the expression levels of FOXO target genes were observed. UPEC can suppress BIM expression induced by LY249002, which results in attenuation of caspase 3 activation and blockage of apoptosis. Mechanistically, BIM expression appears to be epigenetically silenced by a decrease in histone 4 acetylation at the BIM promoter site. Taken together, these results suggest that UPEC can epigenetically silence BIM expression, a molecular switch that prevents apoptosis.

  7. Combined ozone and ultraviolet inactivation of Escherichia coli.

    Science.gov (United States)

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

    2006-01-01

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

  8. De novo biosynthesis of Gastrodin in Escherichia coli.

    Science.gov (United States)

    Bai, Yanfen; Yin, Hua; Bi, Huiping; Zhuang, Yibin; Liu, Tao; Ma, Yanhe

    2016-05-01

    Gastrodin, a phenolic glycoside, is the key ingredient of Gastrodia elata, a notable herbal plant that has been used to treat various conditions in oriental countries for centuries. Gastrodin is extensively used clinically for its sedative, hypnotic, anticonvulsive and neuroprotective properties in China. Gastrodin is usually produced by plant extraction or chemical synthesis, which has many disadvantages. Herein, we report unprecedented microbial synthesis of gastrodin via an artificial pathway. A Nocardia carboxylic acid reductase, endogenous alcohol dehydrogenases and a Rhodiola glycosyltransferase UGT73B6 transformed 4-hydroxybenzoic acid, an intermediate of ubiquinone biosynthesis, into gastrodin in Escherichia coli. Pathway genes were overexpressed to enhance metabolic flux toward precursor 4-hydroxybenzyl alcohol. Furthermore, the catalytic properties of the UGT73B6 toward phenolic alcohols were improved through directed evolution. The finally engineered strain produced 545mgl(-1) gastrodin in 48h. This work creates a new route to produce gastrodin, instead of plant extractions and chemical synthesis.

  9. 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...... a protocol for expressing Hbs with low intrinsic solubilities. Since the alpha- and beta-chain Hbs of different species span a broad range of solubilities, experimental protocols that have been optimized for expressing recombinant human HbA may often prove unsuitable for the recombinant expression...... of wildtype and mutant Hbs of other species. METHODOLOGY/PRINCIPAL FINDINGS: As a test case for our expression system, we produced recombinant Hbs of the deer mouse (Peromyscus maniculatus), a species that has been the subject of research on mechanisms of Hb adaptation to hypoxia. By experimentally assessing...

  10. Shaping the landscape of the Escherichia coli chromosome

    DEFF Research Database (Denmark)

    Ivanova, Darja; Taylor, Toni; Smith, Sarah L.;

    2015-01-01

    problematic. Surprisingly, a recent study reported unperturbed cell cycle progression in Escherichia coli cells with an ectopic replication origin in which highly transcribed rrn operons were forced to be replicated opposite to normal. In this study we have re-generated a similar strain and found the doubling......Each cell division requires the unwinding of millions of DNA base pairs to allow chromosome duplication and gene transcription. As DNA replication and transcription share the same template, conflicts between both processes are unavoidable and head-on collisions are thought to be particularly...... time to be twice that of normal cells. Replication profiles of this background revealed significant deviations in comparison to wild-type profiles, particularly in highly transcribed regions and the termination area. These deviations were alleviated by mutations that either inactivate the termination...

  11. Deliberate Establishment of Asymptomatic Bacteriuria-A Novel Strategy to Prevent Recurrent UTI.

    Science.gov (United States)

    Wullt, Björn; Svanborg, Catharina

    2016-07-29

    We have established a novel strategy to reduce the risk for recurrent urinary tract infection (UTI), where rapidly increasing antibiotic resistance poses a major threat. Epidemiologic studies have demonstrated that asymptomatic bacteriuria (ABU) protects the host against symptomatic infections with more virulent strains. To mimic this protective effect, we deliberately establish ABU in UTI-prone patients, who are refractory to conventional therapy. The patients are inoculated with Escherichia coli (E. coli) 83972, now widely used as a prototype ABU strain. Therapeutic efficacy has been demonstrated in a placebo-controlled trial, supporting the feasibility of using E. coli 83972 as a tool to prevent recurrent UTI and, potentially, to outcompete antibiotic-resistant strains from the human urinary tract. In addition, the human inoculation protocol offers unique opportunities to study host-parasite interaction in vivo in the human urinary tract. Here, we review the clinical evidence for protection using this approach as well as some molecular insights into the pathogenesis of UTI that have been gained during these studies.

  12. Role of verocytotoxigenic Escherichia coli in the swine production chain

    Directory of Open Access Journals (Sweden)

    Laura Ercoli

    2015-06-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC can cause severe clinical diseases in humans, such as haemorrhagic colitis (HC and haemolytic-uremic syndrome (HUS. Although ruminants, primarily cattle, have been suggested as typical reservoirs of STEC, many food products of other origins, including pork products, have been confirmed as vehicles for STEC transmission. Only in rare cases, pork consumption is associated with severe clinical symptoms caused by high pathogenic STEC strains. However, in these outbreaks, it is unknown whether the contamination of food products occurs during swine processing or via cross-contamination from foodstuffs of different sources. In swine, STEC plays an important role in the pathogenesis of oedema disease. In particular a Shiga toxin subtype, named stx2e, it is considered as a key factor involved in the damage of swine endothelial cells. On the contrary, stx2e-producing Escherichia coli has rarely been isolated in humans, and usually only from asymptomatic carriers or from patients with mild symptoms, such as uncomplicated diarrhoea. In fact, the presence of gene stx2e, encoding for stx2e, has rarely been reported in STEC strains that cause HUS. Moreover, stx2e-producing STEC isolated from humans and pigs were found to differ in serogroup, their virulence profile and interaction with intestinal epithelial cells. Because of the limited epidemiologic data of STEC in swine and the increasing role of non-O157 STEC in human illnesses, the relationship between swine STEC and human disease needs to be further investigated.

  13. Enteroaggregative Escherichia coli, a heterogenous, underestimated and under-diagnosed E. coli pathotype in Iran.

    Science.gov (United States)

    Jafari, Anis; Aslani, Mohammad Mehdi; Bouzari, Saeid

    2013-01-01

    The main features of enteroaggregative Escherichia coli (EAEC) pathogenesis include attachment of bacteria to the intestinal mucosa, production of various toxins and cytotoxins, and stimulation of mucosal inflammation. 'Virulence' genes encode these features. Comparison of different EAEC isolates has shown that the virulence gene content of these isolates varies considerably. The heterogeneity of EAEC strains was concluded from the results obtained from the volunteer as well as other studies. Although the underlying mechanism behind the apparent increase in O104:H4 virulence is not known, several bacterial factors have been implicated. In this review, the known virulence factors involved in pathogenesis of EAEC pathotype are summarized.

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

    Directory of Open Access Journals (Sweden)

    Jensen Lars

    2008-09-01

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

  15. Virulence of Escherichia coli O139:K82/ Virulência de Escherichia coli O139:K82

    Directory of Open Access Journals (Sweden)

    Ari Bernardes da Silva

    2001-05-01

    Full Text Available In order to evaluate the pathogenicity and antimicrobial resistance pattern of BK 125 Escherichia coli strain, several tests were assessed: serotype, slide agglutination for detection of the fimbriae F18, presence of the gene Stx2e, verotoxin production, hemolytic activity, pathogenicity assessement using piglet inoculation and antimicrobial resistance to drugs. The strain BK125 showed the following profile: F18+, Stx2e+, Hly+, resistance to streptomicin, tetraciclin, sulfonamides. It produced clinical disease and death of infected piglets. Moreover, it was possible to recover the BK125 strain from diarrheic feces and from the gut contents of the piglet, with high rate of recovery of colonies expressing fimbriae F18. The present results suggest that the E. coli BK125 (O139:K82 strain could produce virulence factors and experimentally reproduce oedema disease in pigs.Com o objetivo de identificar a patogenicidade e resistência a antimicrobianos da cepa de Escherichia coli BK125, foram utilizados os seguintes testes: sorotipagem, aglutinação em lâmina para detecção da fímbria F18, PCR para verificar a presença do gene Stx2e e teste de citoxicidade para avaliar a expressão da verotoxina, ensaio para detecção de hemolisinas, patogenicidade em leitões e antibiograma. A cepa BK125 apresentou o seguinte perfil: F18+, Stx2e+, Hly+, resistente a estreptomicina, tetraciclina, sulfonamida e foi capaz de provocar a doença clínica e morte em leitões inoculados. Também foi possível o resgate dessa cepa de fezes diarréicas e do conteúdo intestinal dos leitões revelando assim, alto índice de recuperação de colônias inoculadas. Os resultados permitem concluir que a E. coli BK125 (O139:K82 é produtora de fatores de virulência e reproduz experimentalmente a doença do edema em suínos.

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

    Science.gov (United States)

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

    2016-01-01

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

  17. Enhanced succinate production from glycerol by engineered Escherichia coli strains.

    Science.gov (United States)

    Li, Qing; Wu, Hui; Li, Zhimin; Ye, Qin

    2016-10-01

    In this study, an engineered strain Escherichia coli MLB (ldhA(-)pflB(-)) was constructed for production of succinate from glycerol. The succinate yield was 0.37mol/mol in anaerobic culture, however, the growth and glycerol consumption rates were very slow, resulting in a low succinate level. Two-stage fermentation was performed in flasks, and the succinate yield reached 0.93mol/mol, but the succinate titer was still low. Hence, overexpression of malate dehydrogenase, malic enzyme, phosphoenolpyruvate (PEP) carboxylase and PEP carboxykinase (PCK) from E. coli, and pyruvate carboxylase from Corynebacterium glutamicum in MLB was investigated for improving succinate production. Overexpression of PCK resulted in remarkable enhancement of glycerol consumption and succinate production. In flask experiments, the succinate concentration reached 118.1mM, and in a 1.5-L bioreactor the succinate concentration further increased to 360.2mM. The highest succinate yield achieved 0.93mol/mol, which was 93% of the theoretical yield, in the anaerobic stage.

  18. 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. PMID:28264015

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

    Science.gov (United States)

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

    2010-01-27

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

  20. 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.

  1. Simple method for purification of enterotoxigenic Escherichia coli fimbriae.

    Science.gov (United States)

    Curtis, Brittany; Grassel, Christen; Laufer, Rachel S; Sears, Khandra T; Pasetti, Marcela F; Barry, Eileen M; Simon, Raphael

    2016-03-01

    Enterotoxigenic Escherichia coli (ETEC) are endemic pathogens in the developing world. They frequently cause illness in travelers, and are among the most prevalent causes of diarrheal disease in children. Pathogenic ETEC strains employ fimbriae as adhesion factors to bind the luminal surface of the intestinal epithelium and establish infection. Accordingly, there is marked interest in immunoprophylactic strategies targeting fimbriae to protect against ETEC infections. Multiple strategies have been reported for purification of ETEC fimbriae, however none is ideal. Purification has typically involved the use of highly virulent wild-type strains. We report here a simple and improved method to purify ETEC fimbriae, which was applied to obtain two different Class 5 fimbriae types of clinical relevance (CFA/I and CS4) expressed recombinantly in E. coli production strains. Following removal from cells by shearing, fimbriae proteins were purified by orthogonal purification steps employing ultracentrifugation, precipitation, and ion-exchange membrane chromatography. Purified fimbriae demonstrated the anticipated size and morphology by electron microscopy analysis, contained negligible levels of residual host cell proteins, nucleic acid, and endotoxin, and were recognized by convalescent human anti-sera.

  2. Invariant distribution of promoter activities in Escherichia coli.

    Science.gov (United States)

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

    2009-10-01

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

  3. Invariant distribution of promoter activities in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Alon Zaslaver

    2009-10-01

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

  4. Release factor one is nonessential in Escherichia coli.

    Science.gov (United States)

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

    2012-08-17

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

  5. Improvements In Ethanologenic Escherichia Coli and Klebsiella Oxytoca

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David Nunn

    2010-09-30

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

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

    Science.gov (United States)

    Olson, Patrick D; Hunstad, David A

    2016-01-04

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

  7. Metabolic and transcriptional response to cofactor perturbations in Escherichia coli.

    Science.gov (United States)

    Holm, Anders K; Blank, Lars M; Oldiges, Marco; Schmid, Andreas; Solem, Christian; Jensen, Peter R; Vemuri, Goutham N

    2010-06-04

    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 to lower the level of NADH and ATP, respectively. We used a global interaction network, comprising of protein interactions, transcriptional regulation, and metabolic networks, to integrate data from transcription profiles, metabolic fluxes, and the metabolite levels. We identified high-scoring networks for the two strains. The results revealed a smaller, but denser network for perturbations of ATP level, compared with that of NADH level. The action of many global transcription factors such as ArcA, Fnr, CRP, and IHF commonly involved both NADH and ATP, whereas others responded to either ATP or NADH. Overexpressing NADH oxidase invokes response in widespread aspects of metabolism involving the redox cofactors (NADH and NADPH), whereas ATPase has a more focused response to restore ATP level by enhancing proton translocation mechanisms and repressing biosynthesis. Interestingly, NADPH played a key role in restoring redox homeostasis through the concerted activity of isocitrate dehydrogenase and UdhA transhydrogenase. We present a reconciled network of regulation that illustrates the overlapping and distinct aspects of metabolism controlled by NADH and ATP. Our study contributes to the general understanding of redox and energy metabolism and should help in developing metabolic engineering strategies in E. coli.

  8. [Virulence factors and pathophysiology of extraintestinal pathogenic Escherichia coli].

    Science.gov (United States)

    Bidet, P; Bonarcorsi, S; Bingen, E

    2012-11-01

    Extraintestinal pathogenic Escherichia coli (ExPEC) causing urinary tract infections, bacteraemia or meningitis are characterized by a particular genetic background (phylogenetic group B2 and D) and the presence, within genetic pathogenicity islands (PAI) or plasmids, of genes encoding virulence factors involved in adhesion to epithelia, crossing of the body barriers (digestive, kidney, bloodbrain), iron uptake and resistance to the immune system. Among the many virulence factors described, two are particularly linked with a pathophysiological process: type P pili PapGII adhesin is linked with acute pyelonephritis, in the absence of abnormal flow of urine, and the K1 capsule is linked with neonatal meningitis. However, if the adhesin PapGII appears as the key factor of pyelonephritis, such that its absence in strain causing the infection is predictive of malformation or a vesico-ureteral reflux, the meningeal virulence of E. coli can not be reduced to a single virulence factor, but results from a combination of factors unique to each clone, and an imbalance between the immune defenses of the host and bacterial virulence.

  9. Public Health Microbiology of Shiga Toxin-Producing Escherichia coli.

    Science.gov (United States)

    Caprioli, Alfredo; Scavia, Gaia; Morabito, Stefano

    2014-12-01

    Shiga toxin-producing Escherichia coli (STEC) strains are the only pathogenic group of E. coli that has a definite zoonotic origin, with ruminants and, in particular, cattle being recognized as the major reservoir. Most human STEC infections are food borne, but the routes of transmission include direct contact with animals and a variety of environment-related exposures. Therefore, STEC public health microbiology spans the fields of medical, veterinary, food, water, and environmental microbiology, requiring a "One Health" perspective and laboratory scientists with the ability to work effectively across disciplines. Public health microbiology laboratories play a central role in the surveillance of STEC infections, as well as in the preparedness for responding to outbreaks and in providing scientific evidence for the implementation of prevention and control measures. This article reviews (i) how the integration of surveillance of STEC infections and monitoring of these pathogens in animal reservoirs and potential food vehicles may contribute to their control; (ii) the role of reference laboratories, in both the public health and veterinary and food sectors; and (iii) the public health perspectives, including those related to regulatory issues in both the European Union and the United States.

  10. Outbreaks of virulent diarrheagenic Escherichia coli - are we in control?

    Directory of Open Access Journals (Sweden)

    Werber Dirk

    2012-02-01

    Full Text Available Abstract Shiga toxin-producing Escherichia coli (STEC are the most virulent diarrheagenic E. coli known to date. They can be spread with alarming ease via food as exemplified by a large sprout-borne outbreak of STEC O104:H4 in 2011 that was centered in northern Germany and affected several countries. Effective control of such outbreaks is an important public health task and necessitates early outbreak detection, fast identification of the outbreak vehicle and immediate removal of the suspected food from the market, flanked by consumer advice and measures to prevent secondary spread. In our view, opportunities to improve control of STEC outbreaks lie in early clinical suspicion for STEC infection, timely diagnosis of all STEC at the serotype-level and integrating molecular subtyping information into surveillance systems. Furthermore, conducting analytical studies that supplement patients' imperfect food history recall and performing, as an investigative element, product tracebacks, are pivotal but underutilized tools for successful epidemiologic identification of the suspected vehicle in foodborne outbreaks. As a corollary, these tools are amenable to tailor microbiological testing of suspected food. Please see related article: http://www.biomedcentral.com/1741-7015/10/12

  11. Endogenous ethanol affects biopolyester molecular weight in recombinant Escherichia coli.

    Science.gov (United States)

    Hiroe, Ayaka; Hyakutake, Manami; Thomson, Nicholas M; Sivaniah, Easan; Tsuge, Takeharu

    2013-11-15

    In biopolyester synthesis, polyhydroxyalkanoate (PHA) synthase (PhaC) catalyzes the polymerization of PHA in bacterial cells, followed by a chain transfer (CT) reaction in which the PHA polymer chain is transferred from PhaC to a CT agent. Accordingly, the frequency of CT reaction determines PHA molecular weight. Previous studies have shown that exogenous alcohols are effective CT agents. This study aimed to clarify the effect of endogenous ethanol as a CT agent for poly[(R)-3-hydroxybutyrate] [P(3HB)] synthesis in recombinant Escherichia coli, by comparing with that of exogenous ethanol. Ethanol supplementation to the culture medium reduced P(3HB) molecular weights by up to 56% due to ethanol-induced CT reaction. NMR analysis of P(3HB) polymers purified from the culture supplemented with (13)C-labeled ethanol showed the formation of a covalent bond between ethanol and P(3HB) chain at the carboxyl end. Cultivation without ethanol supplementation resulted in the reduction of P(3HB) molecular weight with increasing host-produced ethanol depending on culture aeration. On the other hand, production in recombinant BW25113(ΔadhE), an alcohol dehydrogenase deletion strain, resulted in a 77% increase in molecular weight. Analysis of five E. coli strains revealed that the estimated number of CT reactions was correlated with ethanol production. These results demonstrate that host-produced ethanol acts as an equally effective CT agent as exogenous ethanol, and the control of ethanol production is important to regulate the PHA molecular weight.

  12. Dynamic organization of chromosomal DNA in Escherichia coli.

    Science.gov (United States)

    Niki, H; Yamaichi, Y; Hiraga, S

    2000-01-15

    We have revealed the subcellular localization of different DNA segments that are located at approximately 230-kb intervals on the Escherichia coli chromosome using fluorescence in situ hybridization (FISH). The series of chromosome segments is localized within the cell in the same order as the chromosome map. The large chromosome region including oriC shows similar localization patterns, which we call the Ori domain. In addition, the localization pattern of the large segment including dif is characteristic of the replication terminus region. The segment also shows similar localization patterns, which we call the Ter domain. In newborn cells, Ori and Ter domains of the chromosome are differentially localized near opposite cell poles. Subsequently, in the B period, the Ori domain moves toward mid-cell before the initiation of replication, and the Ter domain tends to relocate at mid-cell. An inversion mutant, in which the Ter domain is located close to oriC, shows abnormal subcellular localization of ori and dif segments, resulting in frequent production of anucleate cells. These studies thus suggest that the E. coli chromosome is organized to form a compacted ring structure with the Ori and Ter domains; these domains participate in the cell cycle-dependent localization of the chromosome.

  13. Dissecting Escherichia coli outer membrane biogenesis using differential proteomics.

    Directory of Open Access Journals (Sweden)

    Alessandra M Martorana

    Full Text Available The cell envelope of Gram-negative bacteria is a complex multi-layered structure comprising an inner cytoplasmic membrane and an additional asymmetric lipid bilayer, the outer membrane, which functions as a selective permeability barrier and is essential for viability. Lipopolysaccharide, an essential glycolipid located in the outer leaflet of the outer membrane, greatly contributes to the peculiar properties exhibited by the outer membrane. This complex molecule is transported to the cell surface by a molecular machine composed of seven essential proteins LptABCDEFG that form a transenvelope complex and function as a single device. While advances in understanding the mechanisms that govern the biogenesis of the cell envelope have been recently made, only few studies are available on how bacterial cells respond to severe envelope biogenesis defects on a global scale. Here we report the use of differential proteomics based on Multidimensional Protein Identification Technology (MudPIT to investigate how Escherichia coli cells respond to a block of lipopolysaccharide transport to the outer membrane. We analysed the envelope proteome of a lptC conditional mutant grown under permissive and non permissive conditions and identified 123 proteins whose level is modulated upon LptC depletion. Most such proteins belong to pathways implicated in cell envelope biogenesis, peptidoglycan remodelling, cell division and protein folding. Overall these data contribute to our understanding on how E. coli cells respond to LPS transport defects to restore outer membrane functionality.

  14. Presence of Shiga toxin-producing Escherichia coli, Enteroinvasive E. coli, Enteropathogenic E. coli, and Enterotoxigenic E. coli on tomatoes from public markets in Mexico.

    Science.gov (United States)

    Gómez-Aldapa, Carlos A; Torres-Vitela, M Del Refugio; Acevedo-Sandoval, Otilio A; Rangel-Vargas, Esmeralda; Villarruel-López, Angélica; Castro-Rosas, Andjavier

    2013-09-01

    Diarrheagenic Escherichia coli pathotypes (DEP) are important foodborne pathogens in various countries, including Mexico. However, no data exist on the presence of DEP on fresh tomatoes (Solanum lycopericum) from Mexico. The frequency of fecal coliforms (FC), E. coli, and DEP were determined for two tomato varieties. One hundred samples of a saladette tomato variety and 100 samples of a red round tomato variety were collected from public markets in Pachuca, Mexico. Each tomato sample consisted of four whole tomatoes. For the 100 saladette samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 70, 60, and 10% of samples, respectively. For the 100 red round samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 75, 65, and 11% of samples, respectively. Identified DEP included Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). STEC were isolated from 6% of saladette samples and 5% of red round samples. ETEC were isolated from 3% of saladette samples and 4% of red round samples. EPEC were isolated from 2% of saladette samples and 3% of red round samples, and EIEC were isolated from 1% of saladette samples. Both STEC and ETEC were identified in two saladette samples and 1 red round sample. E. coli O157:H7 was not detected in any STEC-positive samples.

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

    Science.gov (United States)

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

    2014-05-27

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

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

    Science.gov (United States)

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

    2015-07-01

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

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

    Science.gov (United States)

    Nieves, Ismael U.

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

  18. Osmolytes contribute to pH homeostasis of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Ryan D Kitko

    Full Text Available BACKGROUND: Cytoplasmic pH homeostasis in Escherichia coli includes numerous mechanisms involving pH-dependent catabolism and ion fluxes. An important contributor is transmembrane K+ flux, but the actual basis of K+ compensation for pH stress remains unclear. Osmoprotection could mediate the pH protection afforded by K+ and other osmolytes. METHODS AND PRINCIPAL FINDINGS: The cytoplasmic pH of E. coli K-12 strains was measured by GFPmut3 fluorimetry. The wild-type strain Frag1 was exposed to rapid external acidification by HCl addition. Recovery of cytoplasmic pH was enhanced equally by supplementation with NaCl, KCl, proline, or sucrose. A triple mutant strain TK2420 defective for the Kdp, Trk and Kup K+ uptake systems requires exogenous K+ for steady-state pH homeostasis and for recovery from sudden acid shift. The K+ requirement however was partly compensated by supplementation with NaCl, choline chloride, proline, or sucrose. Thus, the K+ requirement was mediated in part by osmolarity, possibly by relieving osmotic stress which interacts with pH stress. The rapid addition of KCl to strain TK2420 suspended at external pH 5.6 caused a transient decrease in cytoplasmic pH, followed by slow recovery to an elevated steady-state pH. In the presence of 150 mM KCl, however, rapid addition of another 150 mM KCl caused a transient increase in cytoplasmic pH. These transient effects may arise from secondary K+ fluxes occurring through other transport processes in the TK2420 strain. CONCLUSIONS: Diverse osmolytes including NaCl, KCl, proline, or sucrose contribute to cytoplasmic pH homeostasis in E. coli, and increase the recovery from rapid acid shift. Osmolytes other than K+ restore partial pH homeostasis in a strain deleted for K+ transport.

  19. [Production of coenzyme Q10 by metabolically engineered Escherichia coli].

    Science.gov (United States)

    Dai, Guanping; Miao, Liangtian; Sun, Tao; Li, Qingyan; Xiao, Dongguang; Zhang, Xueli

    2015-02-01

    Coenzyme Q10 (CoQ10) is a lipophilic antioxidant that improves human immunity, delays senility and enhances the vitality of the human body and has wide applications in pharmaceutical and cosmetic industries. Microbial fermentation is a sustainable way to produce CoQ10, and attracts increased interest. In this work, the native CoQ8 synthetic pathway of Escherichia coli was replaced by the CoQ10 synthetic pathway through integrating decaprenyl diphosphate synthase gene (dps) from Rhodobacter sphaeroides into chromosome of E. coli ATCC 8739, followed by deletion of the native octaprenyl diphosphate synthase gene (ispB). The resulting strain GD-14 produced 0.68 mg/L CoQ10 with a yield of 0.54 mg/g DCW. Modulation of dxs and idi genes of the MEP pathway and ubiCA genes in combination led to 2.46-fold increase of CoQ10 production (from 0.54 to 1.87 mg/g DCW). Recruiting glucose facilitator protein of Zymomonas mobilis to replace the native phosphoenolpyruvate: carbohydrate phosphotransferase systems (PTS) further led to a 16% increase of CoQ10 yield. Finally, fed-batch fermentation of the best strain GD-51 was performed, which produced 433 mg/L CoQ10 with a yield of 11.7 mg/g DCW. To the best of our knowledge, this was the highest CoQ10 titer and yield obtained for engineered E. coli.

  20. Relative effects of bacterial and protozoan predators on survival of Escherichia coli in estuarine water samples.

    OpenAIRE

    McCambridge, J; McMeekin, T A

    1980-01-01

    The relative effect of protozoan and bacterial predators on the survival of Escherichia coli in estuarine water samples was examined. Predacious protozoa exerted their major influence on E. coli destruction during the first 2 days of a 10-day-decline period. Inhibition of protozoa after day 2 had little effect on E. coli survival. Bacterial predators also contributed to E. coli destruction but in natural estuarine water samples were maintained at lower levels due to "grazing" by predacious pr...

  1. Genotypic Diversity of Escherichia coli in the Water and Soil of Tropical Watersheds in Hawaii ▿

    OpenAIRE

    Goto, Dustin K.; Yan, Tao

    2011-01-01

    High levels of Escherichia coli were frequently detected in tropical soils in Hawaii, which present important environmental sources of E. coli to water bodies. This study systematically examined E. coli isolates from water and soil of several watersheds in Hawaii and observed high overall genotypic diversity (35.5% unique genotypes). In the Manoa watershed, fewer than 9.3% of the observed E. coli genotypes in water and 6.6% in soil were shared between different sampling sites, suggesting the ...

  2. Effect of Phosphorus on Survival of Escherichia coli in Drinking Water Biofilms▿

    OpenAIRE

    Juhna, Talis; Birzniece, Dagne; Rubulis, Janis

    2007-01-01

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

  3. High frequency of antimicrobial drug resistance of diarrheagenic Escherichia coli in infants in Peru.

    OpenAIRE

    Theresa J. Ochoa; Ruiz, Joaquím; Molina, Margarita; Luis J. Del Valle; Vargas, Martha; Gil, Ana I.; Ecker, Lucie; Barletta, Francesca; Hall, Eric; Cleary, Thomas G.; Lanata, Claudio F.

    2014-01-01

    Abstract. In a prospective passive diarrhea surveillance cohort study of 1,034 infants of low socioeconomic communities in Lima, Peru, we determined the prevalence and antimicrobial drug susceptibility of the diarrheagenic Escherichia coli . The prevalence of diarrheagenic E. coli was 29% (161 of 557) in children with gastroenteritis and 30% (58 of 195) in the control group without diarrhea. The most common E. coli pathogens in diarrhea were enteroaggregative E. coli (EAEC) (14%),...

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

    Directory of Open Access Journals (Sweden)

    Iliana Alejandra Cortés-Ortiz

    2002-07-01

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

  5. Immobilizing live Escherichia coli for AFM studies of surface dynamics.

    Science.gov (United States)

    Lonergan, N E; Britt, L D; Sullivan, C J

    2014-02-01

    Atomic force microscopy (AFM) is a probe-based technique that permits high resolution imaging of live bacterial cells. However, stably immobilizing cells to withstand the probe-based lateral forces remains an obstacle in AFM mediated studies, especially those of live, rod shaped bacteria in nutrient media. Consequently, AFM has been under-utilized in the research of bacterial surface dynamics. The aim of the current study was to immobilize a less adherent Escherichia coli strain in a method that both facilitates AFM imaging in nutrient broth and preserves overall cell viability. Immobilization reagents and buffers were systematically evaluated and the cell membrane integrity was monitored in all sample preparations. As expected, the biocompatible gelatin coated surfaces facilitated stable cell attachment in lower ionic strength buffers, yet poorly immobilized cells in higher ionic strength buffers. In comparison, poly-l-lysine surfaces bound cells in both low and high ionic strength buffers. The benefit of the poly-l-lysine binding capacity was offset by the compromised membrane integrity exhibited by cells on poly-l-lysine surfaces. However, the addition of divalent cations and glucose to the immobilization buffer was found to mitigate this unfavorable effect. Ultimately, immobilization of E. coli cells on poly-l-lysine surfaces in a lower ionic strength buffer supplemented with Mg(2+) and Ca(2+) was determined to provide optimal cell attachment without compromising the overall cell viability. Cells immobilized in this method were stably imaged in media through multiple division cycles. Furthermore, permeability assays indicated that E. coli cells recover from the hypoosmotic stress caused by immobilization in low ionic strength buffers. Taken together, this data suggests that stable immobilization of viable cells on poly-l-lysine surfaces can be accomplished in lower ionic strength buffers that are supplemented with divalent cations for membrane stabilization

  6. Enteroaggregative Escherichia coli in Daycare-A 1-Year Dynamic Cohort Study

    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...

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

    Science.gov (United States)

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

  8. Differential decay of Enterococci and Escherichia coli originating from two fecal pollution sources

    Science.gov (United States)

    Using in situ subtropical aquatic mesocosms, fecal source (cattle manure versus sewage) was shown to be the most important contributor to differential loss in viability of fecal indicator bacteria (FIB), specifically enterococci in freshwater and Escherichia coli in marine habita...

  9. Enantioselective bioconversion using Escherichia coli cells expressing Saccharomyces cerevisiae reductase and Bacillus subtilis glucose dehydrogenase.

    Science.gov (United States)

    Park, Hyun Joo; Jung, Jihye; Choi, Hyejeong; Uhm, Ki-Nam; Kim, Hyung Kwoun

    2010-09-01

    Ethyl (R, S)-4-chloro-3-hydroxybutanoate (ECHB) is a useful chiral building block for the synthesis of L-carnitine and hypercholesterolemia drugs. The yeast reductase, YOL151W (GenBank locus tag), exhibits an enantioselective reduction activity, converting ethyl-4-chlorooxobutanoate (ECOB) exclusively into (R)-ECHB. YOL151W was generated in Escherichia coli cells and purified via Ni- NTA and desalting column chromatography. It evidenced an optimum temperature of 45 degrees C and an optimum pH of 6.5-7.5. Bacillus subtilis glucose dehydrogenase (GDH) was also expressed in Escherichia coli, and was used for the recycling of NADPH, required for the reduction reaction. Thereafter, Escherichia coli cells co-expressing YOL151W and GDH were constructed. After permeablization treatment, the Escherichia coli whole cells were utilized for ECHB synthesis. Through the use of this system, the 30 mM ECOB substrate could be converted to (R)-ECHB.

  10. Chromosome Partitioning in Escherichia coli in the Absence of Dam-Directed Methylation

    OpenAIRE

    1992-01-01

    Escherichia coli dam mutants, lacking the GATC DNA methylase, do not produce anucleate cells at high frequencies, suggesting that hemimethylation of the chromosome origin of replication, oriC, is not essential for correct chromosome partitioning.

  11. Read-through proteins of group 4 RNA bacteriophages TW19 and TW28. [Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Aoi, T.; Kaesberg, P.

    1976-10-01

    Group 4 phages TW19 and TW28 of Escherichia coli possess a read-through (IIb) protein, although group 2 phage GA does not. This may have implications concerning the evolution and classification of RNA phages.

  12. SIMULTANEOUS EFFECTS OF SHAKING AND TEMPERATURE ON VEROTOXIN1 PHAGE INDUCTION FROM VEROTOXIGENIC ESCHERICHIA COLI STRAINS

    Directory of Open Access Journals (Sweden)

    H. Hosain Zadegan, M. Sattari, M. H. Zahir, A. A. Allame

    2006-01-01

    Full Text Available Induction of lambda phage carring verotoxin1 gene from a verotoxigenic strains of Escherichia coli and released verotoxin1 were studied under environmental factors of shaking and termperature. Verotoxin1 phage in Escherichia coli PA 101 and transductants was confirmed by bacteriophage detection assay. Shaking of culture media and increasing temperature until 42 ºC increased phage particles in supernatants of Escherichia coli PA 101. Our results indicate that environmental factors such as shaking movements in natural inhabitates of bacteria such as river or sewage streams and temperature rise in summer season could be factors in induce and release free verotoxin1 – producing phage particles in nature that in turn could be the source of phage spreading to other related bacteria , and responsible for increased outbreaks of food borne diseases with verotoxigenic Escherichia coli in warm monthes of year in tropical areas.

  13. Surface Characteristics and Adhesion Behavior of Escherichia coli O157:H7: Role of Extracellular Macromolecules

    Science.gov (United States)

    Surface macromolecule cleavage experiments were conducted on enterohaemorrhagic Escherichia coli O157:H7 cells to investigate the influence of these macromolecules on cell surface properties. Electrophoretic mobility, hydrophobicity, and titration experiments were carried out on proteinase K treate...

  14. Antibacterial activity of Tribulus terrestris methanol extract against clinical isolates of Escherichia coli

    OpenAIRE

    2016-01-01

    Introduction:Tribulus terrestris L. is traditionally used for treatment of urinary tract infections. Escherichia coli, as the most prominent agent of urinary tract infections, can be sensitive to T. terrestris extract.

  15. Antibacterial activity of Tribulus terrestris methanol extract against clinical isolates of Escherichia coli

    Directory of Open Access Journals (Sweden)

    Batoei Sara

    2016-06-01

    Full Text Available Introduction:Tribulus terrestris L. is traditionally used for treatment of urinary tract infections. Escherichia coli, as the most prominent agent of urinary tract infections, can be sensitive to T. terrestris extract.

  16. Uropathogenic Escherichia coli (UPEC) strains may carry virulence properties of diarrhoeagenic E. coli.

    Science.gov (United States)

    Abe, Cecilia M; Salvador, Fábia A; Falsetti, Ivan N; Vieira, Mônica A M; Blanco, Jorge; Blanco, Jesús E; Blanco, Miguel; Machado, Antônia M O; Elias, Waldir P; Hernandes, Rodrigo T; Gomes, Tânia A T

    2008-04-01

    To analyze whether Escherichia coli strains that cause urinary tract infections (UPEC) share virulence characteristics with the diarrheagenic E. coli (DEC) pathotypes and to recognize their genetic diversity, 225 UPEC strains were examined for the presence of various properties of DEC and UPEC (type of interaction with HeLa cells, serogroups and presence of 30 virulence genes). No correlation between adherence patterns and serogroups was observed. Forty-five serogroups were found, but 64% of the strains belonged to one of the 12 serogroups (O1, O2, O4, O6, O7, O14, O15, O18, O21, O25, O75, and O175) and carried UPEC virulence genes (pap, hly, aer, sfa, cnf). The DEC genes found were: aap, aatA, aggC, agg3C, aggR, astA, eae, ehly, iha, irp2, lpfA(O113), pet, pic, pilS, and shf. Sixteen strains presented aggregative adherence and/or the aatA sequence, which are characteristics of enteroaggregative E. coli (EAEC), one of the DEC pathotypes. In summary, certain UPEC strains may carry DEC virulence properties, mostly associated to the EAEC pathotype. This finding raises the possibility that at least some faecal EAEC strains might represent potential uropathogens. Alternatively, certain UPEC strains may have acquired EAEC properties, becoming a potential cause of diarrhoea.

  17. Quorum Sensing Inhibitory Activity of Giganteone A from Myristica cinnamomea King against Escherichia coli Biosensors.

    Science.gov (United States)

    Sivasothy, Yasodha; Krishnan, Thiba; Chan, Kok-Gan; Abdul Wahab, Siti Mariam; Othman, Muhamad Aqmal; Litaudon, Marc; Awang, Khalijah

    2016-03-21

    Malabaricones A-C (1-3) and giganteone A (4) were isolated from the bark of Myristica cinnamomea King. Their structures were elucidated and characterized by means of NMR and MS spectral analyses. These isolates were evaluated for their anti-quorum sensing activity using quorum sensing biosensors, namely Escherichia coli [pSB401] and Escherichia coli [pSB1075], whereby the potential of giganteone A (4) as a suitable anti-quorum sensing agent was demonstrated.

  18. POTENSI RUMPUT LAUT DI PANTAI BAYAH, KABUPATEN LEBAK, BANTEN SEBAGAI ANTIBAKTERI Escherichia coli

    OpenAIRE

    Triastinurmiatiningsih Triastinurmiatiningsih; Tri Saptari Haryani

    2008-01-01

    Antibacterial potency of some seaweed against Escherichia coli has been known. The aim of this research is to know the species of seaweeds from Bayah beach Lebak Banten which may be used as antibacterial against Escherichia coli. Twenty one seaweed species samples from Bayah Beach Lebak Banten were exstracted by organic solvent of absolute methanol according to Espeche, Fraile, and Mayer (1984) and Darusman, Sayuti, Komar & Pamungkas (1992) methods. The antibacterial activities were examined ...

  19. The green alga, Cladophora, promotes Escherichia coli growth and contamination of recreational waters in Lake Michigan

    Science.gov (United States)

    Heuvel, A.V.; McDermott, C.; Pillsbury, R.; Sandrin, T.; Kinzelman, J.; Ferguson, J.; Sadowsky, M.; Byappanahalli, M.; Whitman, R.; Kleinheinz, G.T.

    2010-01-01

    A linkage between Cladophora mats and exceedances of recreational water quality criteria has been suggested, but not directly studied. Th is study investigates the spatial and temporal association between Escherichia coli concentrations within and near Cladophora mats at two northwestern Lake Michigan beaches in Door County, Wisconsin. Escherichia coli concentrations in water underlying mats were significantly greater than surrounding water (p Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  20. Tellurite enters Escherichia coli mainly through the PitA phosphate transporter

    OpenAIRE

    Elías, Alex O; Abarca, María José; Montes, Rebecca A; Chasteen, Thomas G; Pérez-Donoso, José M.; Vásquez, Claudio C.

    2012-01-01

    Several transporters suspected to be involved in tellurite uptake in Escherichia coli were analyzed. Results showed that the PitA phosphate transporter was related to tellurite uptake. Escherichia coli ΔpitA was approximately four-fold more tolerant to tellurite, and cell viability remained almost unchanged during prolonged exposure to the toxicant as compared with wild type or ΔpitB cells. Notably, reduced thiols (toxicant targets) as well as superoxide dismutase, catalase, and fumarase C ac...

  1. "Emergence of Multidrug Resistant Strains of Escherichia coli Isolated from Urinary Tract Infections"

    OpenAIRE

    R Moniri; Khorshidi, A; H Akbari

    2003-01-01

    The emergence of multidrug resistant strains of Escherichia coli has complicated treatment decision and may lead to treatment failures. From April to November 2001 we prospectively evaluated the prevalence of resistance to trimethoprim-sulfamethoxazole (SXT), gentamicin, cephalothin, ciprofloxacin, and nitrofurantoin in 220 Escherichia coli isolates from patients with urinary tract infections in kashan, Iran. To assess the current breadth of multidrug resistance among urinary isolates of E. c...

  2. Dynamics of Quinolone Resistance in Fecal Escherichia coli of Finishing Pigs after Ciprofloxacin Administration

    OpenAIRE

    Huang, Kang; Xu, Chang-Wen; Zeng, Bo; XIA, Qing-Qing; Zhang, An-Yun; LEI, Chang-Wei; Guan, Zhong-Bin; Cheng, Han; Wang, Hong-ning

    2014-01-01

    ABSTRACT Escherichia coli resistance to quinolones has now become a serious issue in large-scale pig farms of China. It is necessary to study the dynamics of quinolone resistance in fecal Escherichia coli of pigs after antimicrobial administration. Here, we present the hypothesis that the emergence of resistance in pigs requires drug accumulation for 7 days or more. To test this hypothesis, 26 pigs (90 days old, about 30 kg) not fed any antimicrobial after weaning were selected and divided in...

  3. Complete Genome Sequences of Four Novel Escherichia coli Bacteriophages Belonging to New Phage Groups

    DEFF Research Database (Denmark)

    Carstens, Alexander B; Kot, Witold; Hansen, Lars H

    2015-01-01

    Here, we describe the sequencing and genome annotations of a set of four Escherichia coli bacteriophages (phages) belonging to newly discovered groups previously consisting of only a single phage and thus expand our knowledge of these phage groups.......Here, we describe the sequencing and genome annotations of a set of four Escherichia coli bacteriophages (phages) belonging to newly discovered groups previously consisting of only a single phage and thus expand our knowledge of these phage groups....

  4. Genome Sequences of Two Copper-Resistant Escherichia coli Strains Isolated from Copper-Fed Pigs

    DEFF Research Database (Denmark)

    Lüthje, Freja L.; Hasman, Henrik; Aarestrup, Frank Møller;

    2014-01-01

    The draft genome sequences of two copper-resistant Escherichia coli strains were determined. These had been isolated from copper-fed pigs and contained additional putative operons conferring copper and other metal and metalloid resistances.......The draft genome sequences of two copper-resistant Escherichia coli strains were determined. These had been isolated from copper-fed pigs and contained additional putative operons conferring copper and other metal and metalloid resistances....

  5. Quorum Sensing Inhibitory Activity of Giganteone A from Myristica cinnamomea King against Escherichia coli Biosensors

    Directory of Open Access Journals (Sweden)

    Yasodha Sivasothy

    2016-03-01

    Full Text Available Malabaricones A–C (1–3 and giganteone A (4 were isolated from the bark of Myristica cinnamomea King. Their structures were elucidated and characterized by means of NMR and MS spectral analyses. These isolates were evaluated for their anti-quorum sensing activity using quorum sensing biosensors, namely Escherichia coli [pSB401] and Escherichia coli [pSB1075], whereby the potential of giganteone A (4 as a suitable anti-quorum sensing agent was demonstrated.

  6. [Joint cultivation of Bacillus subtilis and Escherichia coli strains promising for obtaining complex probiotic].

    Science.gov (United States)

    Tsaruk'ianova, I G; Osadchaia, A I

    2007-01-01

    The ability of joint cultivation of Bacillus subtilis UCM B-5007 and Escherichia coli M-17 in subsurface conditions has been studied. These strains are available for creation of a new complex probiotic. Symbiotic relationships between these microorganisms were proved. Bacillus subtilis and Escherichia coli strains use different growth "strategy". The most optimum ratio of cultures (1:1) for growth, biomass accumulation, and for antagonism to test-cultures has been chosen.

  7. CRISPR Content Correlates with the Pathogenic Potential of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Enriqueta García-Gutiérrez

    Full Text Available Guide RNA molecules (crRNA produced from clustered regularly interspaced short palindromic repeat (CRISPR arrays, altogether with effector proteins (Cas encoded by cognate cas (CRISPR associated genes, mount an interference mechanism (CRISPR-Cas that limits acquisition of foreign DNA in Bacteria and Archaea. The specificity of this action is provided by the repeat intervening spacer carried in the crRNA, which upon hybridization with complementary sequences enables their degradation by a Cas endonuclease. Moreover, CRISPR arrays are dynamic landscapes that may gain new spacers from infecting elements or lose them for example during genome replication. Thus, the spacer content of a strain determines the diversity of sequences that can be targeted by the corresponding CRISPR-Cas system reflecting its functionality. Most Escherichia coli strains possess either type I-E or I-F CRISPR-Cas systems. To evaluate their impact on the pathogenicity of the species, we inferred the pathotype and pathogenic potential of 126 strains of this and other closely related species and analyzed their repeat content. Our results revealed a negative correlation between the number of I-E CRISPR units in this system and the presence of pathogenicity traits: the median number of repeats was 2.5-fold higher for commensal isolates (with 29.5 units, range 0-53 than for pathogenic ones (12.0, range 0-42. Moreover, the higher the number of virulence factors within a strain, the lower the repeat content. Additionally, pathogenic strains of distinct ecological niches (i.e., intestinal or extraintestinal differ in repeat counts. Altogether, these findings support an evolutionary connection between CRISPR and pathogenicity in E. coli.

  8. Chaperone-assisted refolding of Escherichia coli maltodextrin glucosidase.

    Science.gov (United States)

    Paul, Subhankar; Punam, Shashikala; Chaudhuri, Tapan K

    2007-11-01

    In vitro refolding of maltodextrin glucosidase, a 69 kDa monomeric Escherichia coli protein, was studied in the presence of glycerol, dimethylsulfoxide, trimethylamine-N-oxide, ethylene glycol, trehalose, proline and chaperonins GroEL and GroES. Different osmolytes, namely proline, glycerol, trimethylamine-N-oxide and dimethylsulfoxide, also known as chemical chaperones, assist in protein folding through effective inhibition of the aggregation process. In the present study, it was observed that a few chemical chaperones effectively reduced the aggregation process of maltodextrin glucosidase and hence the in vitro refolding was substantially enhanced, with ethylene glycol being the exception. Although, the highest recovery of active maltodextrin glucosidase was achieved through the ATP-mediated GroEL/GroES-assisted refolding of denatured protein, the yield of correctly folded protein from glycerol- or proline-assisted spontaneous refolding process was closer to the chaperonin-assisted refolding. It was also observed that the combined application of chemical chaperones and molecular chaperone was more productive than their individual contribution towards the in vitro refolding of maltodextrin glucosidase. The chemical chaperones, except ethylene glycol, were found to provide different degrees of protection to maltodextrin glucosidase from thermal denaturation, whereas proline caused the highest protection. The observations from the present studies conclusively demonstrate that chemical or molecular chaperones, or the combination of both chaperones, could be used in the efficient refolding of recombinant E. coli maltodextrin glucosidase, which enhances the possibility of identifying or designing suitable small molecules that can act as chemical chaperones in the efficient refolding of various aggregate-prone proteins of commercial and medical importance.

  9. Isolation of Escherichia coli mutants defective in uptake of molybdate.

    Science.gov (United States)

    Hemschemeier, S; Grund, M; Keuntje, B; Eichenlaub, R

    1991-10-01

    For the study of molybdenum uptake by Escherichia coli, we generated Tn5lac transposition mutants, which were screened for the pleiotropic loss of molybdoenzyme activities. Three mutants A1, A4, and M22 were finally selected for further analysis. Even in the presence of 100 microM molybdate in the growth medium, no active nitrate reductase, formate dehydrogenase, and trimethylamine-N-oxide reductase were detected in these mutants, indicating that the intracellular supply of molybdenum was not sufficient. This was also supported by the observation that introduction of plasmid pWK225 carrying the complete nif regulon of Klebsiella pneumoniae did not lead to a functional expression of nitrogenase. Finally, molybdenum determination by induced coupled plasma mass spectroscopy confirmed a significant reduction of cell-bound molybdenum in the mutants compared with that in wild-type E. coli, even at high molybdate concentrations in the medium. A genomic library established with the plasmid mini-F-derived cop(ts) vector pJE258 allowed the isolation of cosmid pBK229 complementing the molybdate uptake deficiency of the chlD mutant and the Tn5lac-induced mutants. Certain subfragments of pBK229 which do not contain the chlD gene are still able to complement the Tn5lac mutants. Mapping experiments showed that the Tn5lac insertions did not occur within the chromosomal region present in pBK229 but did occur very close to that region. We assume that the Tn5lac insertions have a polar effect, thus preventing the expression of transport genes, or that a positively acting regulatory element was inactivated.

  10. Expression and purification of recombinant hemoglobin in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Chandrasekhar Natarajan

    Full Text Available 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 a protocol for expressing Hbs with low intrinsic solubilities. Since the α- and β-chain Hbs of different species span a broad range of solubilities, experimental protocols that have been optimized for expressing recombinant human HbA may often prove unsuitable for the recombinant expression of wildtype and mutant Hbs of other species. METHODOLOGY/PRINCIPAL FINDINGS: As a test case for our expression system, we produced recombinant Hbs of the deer mouse (Peromyscus maniculatus, a species that has been the subject of research on mechanisms of Hb adaptation to hypoxia. By experimentally assessing the combined effects of induction temperature, induction time and E. coli expression strain on the solubility of recombinant deer mouse Hbs, we identified combinations of expression conditions that greatly enhanced the yield of recombinant protein and which also increased the efficiency of post-translational modifications. CONCLUSION/SIGNIFICANCE: Our protocol should prove useful for the experimental study of recombinant Hbs in many non-human animals. One of the chief advantages of our protocol is that we can express soluble recombinant Hb without co-expressing molecular chaperones, and without the need for additional reconstitution or heme-incorporation steps. Moreover, our plasmid construct contains a combination of unique restriction sites that allows us to produce recombinant Hbs with different α- and β-chain subunit combinations by means of cassette mutagenesis.

  11. Recombinant production of human interleukin 6 in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Henrik Nausch

    Full Text Available In this study, we compared basic expression approaches for the efficient expression of bioactive recombinant human interleukin-6 (IL6, as an example for a difficult-to-express protein. We tested these approaches in a laboratory scale in order to pioneer the commercial production of this protein in Escherichia coli (E. coli. Among the various strategies, which were tested under Research and Development (R&D conditions, aggregation-prone IL6 was solubilized most effectively by co-expressing cytoplasmic chaperones. Expression of a Glutathion-S-Transferase (GST fusion protein was not efficient to increase IL6 solubility. Alteration of the cultivation temperature significantly increased the solubility in both cases, whereas reduced concentrations of IPTG to induce expression of the T7lac-promotor only had a positive effect on chaperone-assisted expression. The biological activity was comparable to that of commercial IL6. Targeting the expressed protein to an oxidizing environment was not effective in the generation of soluble IL6. Taken together, the presence of chaperones and a lowered cultivation temperature seem effective to isolate large quantities of soluble IL6. This approach led to in vivo soluble, functional protein fractions and reduces purification and refolding requirements caused by downstream purification procedures. The final yield of soluble recombinant protein averaged approximately 2.6 mg IL6/liter of cell culture. These findings might be beneficial for the development of the large-scale production of IL6 under the conditions of current good manufacturing practice (cGMP.

  12. Effects of Kasugamycin on the Translatome of Escherichia coli.

    Science.gov (United States)

    Lange, Christian; Lehr, Matthias; Zerulla, Karolin; Ludwig, Petra; Schweitzer, Jens; Polen, Tino; Wendisch, Volker F; Soppa, Jörg

    2017-01-01

    It is long known that Kasugamycin inhibits translation of canonical transcripts containing a 5'-UTR with a Shine Dalgarno (SD) motif, but not that of leaderless transcripts. To gain a global overview of the influence of Kasugamycin on translation efficiencies, the changes of the translatome of Escherichia coli induced by a 10 minutes Kasugamycin treatment were quantified. The effect of Kasugamycin differed widely, 102 transcripts were at least twofold more sensitive to Kasugamycin than average, and 137 transcripts were at least twofold more resistant, and there was a more than 100-fold difference between the most resistant and the most sensitive transcript. The 5'-ends of 19 transcripts were determined from treated and untreated cultures, but Kasugamycin resistance did neither correlate with the presence or absence of a SD motif, nor with differences in 5'-UTR lengths or GC content. RNA Structure Logos were generated for the 102 Kasugamycin-sensitive and for the 137 resistant transcripts. For both groups a short Shine Dalgarno (SD) motif was retrieved, but no specific motifs associated with resistance or sensitivity could be found. Notably, this was also true for the region -3 to -1 upstream of the start codon and the presence of an extended SD motif, which had been proposed to result in Kasugamycin resistance. Comparison of the translatome results with the database RegulonDB showed that the transcript with the highest resistance was leaderless, but no further leaderless transcripts were among the resistant transcripts. Unexpectedly, it was found that translational coupling might be a novel feature that is associated with Kasugamycin resistance. Taken together, Kasugamycin has a profound effect on translational efficiencies of E. coli transcripts, but the mechanism of action is different than previously described.

  13. CRISPR Content Correlates with the Pathogenic Potential of Escherichia coli.

    Science.gov (United States)

    García-Gutiérrez, Enriqueta; Almendros, Cristóbal; Mojica, Francisco J M; Guzmán, Noemí M; García-Martínez, Jesús

    2015-01-01

    Guide RNA molecules (crRNA) produced from clustered regularly interspaced short palindromic repeat (CRISPR) arrays, altogether with effector proteins (Cas) encoded by cognate cas (CRISPR associated) genes, mount an interference mechanism (CRISPR-Cas) that limits acquisition of foreign DNA in Bacteria and Archaea. The specificity of this action is provided by the repeat intervening spacer carried in the crRNA, which upon hybridization with complementary sequences enables their degradation by a Cas endonuclease. Moreover, CRISPR arrays are dynamic landscapes that may gain new spacers from infecting elements or lose them for example during genome replication. Thus, the spacer content of a strain determines the diversity of sequences that can be targeted by the corresponding CRISPR-Cas system reflecting its functionality. Most Escherichia coli strains possess either type I-E or I-F CRISPR-Cas systems. To evaluate their impact on the pathogenicity of the species, we inferred the pathotype and pathogenic potential of 126 strains of this and other closely related species and analyzed their repeat content. Our results revealed a negative correlation between the number of I-E CRISPR units in this system and the presence of pathogenicity traits: the median number of repeats was 2.5-fold higher for commensal isolates (with 29.5 units, range 0-53) than for pathogenic ones (12.0, range 0-42). Moreover, the higher the number of virulence factors within a strain, the lower the repeat content. Additionally, pathogenic strains of distinct ecological niches (i.e., intestinal or extraintestinal) differ in repeat counts. Altogether, these findings support an evolutionary connection between CRISPR and pathogenicity in E. coli.

  14. The upper surface of an Escherichia coli swarm is stationary.

    Science.gov (United States)

    Zhang, Rongjing; Turner, Linda; Berg, Howard C

    2010-01-05

    When grown in a rich medium on agar, many bacteria elongate, produce more flagella, and swim in a thin film of fluid over the agar surface in swirling packs. Cells that spread in this way are said to swarm. The agar is a solid gel, with pores smaller than the bacteria, so the swarm/agar interface is fixed. Here we show, in experiments with Escherichia coli, that the swarm/air interface also is fixed. We deposited MgO smoke particles on the top surface of an E. coli swarm near its advancing edge, where cells move in a single layer, and then followed the motion of the particles by dark-field microscopy and the motion of the underlying cells by phase-contrast microscopy. Remarkably, the smoke particles remained fixed (diffusing only a few micrometers) while the swarming cells streamed past underneath. The diffusion coefficients of the smoke particles were smaller over the virgin agar ahead of the swarm than over the swarm itself. Changes between these two modes of behavior were evident within 10-20 microm of the swarm edge, indicating an increase in depth of the fluid in advance of the swarm. The only plausible way that the swarm/air interface can be fixed is that it is covered by a surfactant monolayer pinned at its edges. When a swarm is exposed to air, such a monolayer can markedly reduce water loss. When cells invade tissue, the ability to move rapidly between closely opposed fixed surfaces is a useful trait.

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

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    Ullmann, Agnes

    2010-09-01

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

  16. Cardiovascular disease after Escherichia coli O157:H7 gastroenteritis

    Science.gov (United States)

    Hizo-Abes, Patricia; Clark, William F.; Sontrop, Jessica M.; Young, Ann; Huang, Anjie; Thiessen-Philbrook, Heather; Austin, Peter C.; Garg, Amit X.

    2013-01-01

    Background: Escherichia coli O157:H7 is one cause of acute bacterial gastroenteritis, which can be devastating in outbreak situations. We studied the risk of cardiovascular disease following such an outbreak in Walkerton, Ontario, in May 2000. Methods: In this community-based cohort study, we linked data from the Walkerton Health Study (2002–2008) to Ontario’s large healthcare databases. We included 4 groups of adults: 3 groups of Walkerton participants (153 with severe gastroenteritis, 414 with mild gastroenteritis, 331 with no gastroenteritis) and a group of 11 263 residents from the surrounding communities that were unaffected by the outbreak. The primary outcome was a composite of death or first major cardiovascular event (admission to hospital for acute myocardial infarction, stroke or congestive heart failure, or evidence of associated procedures). The secondary outcome was first major cardiovascular event censored for death. Adults were followed for an average of 7.4 years. Results: During the study period, 1174 adults (9.7%) died or experienced a major cardiovascular event. Compared with residents of the surrounding communities, the risk of death or cardiovascular event was not elevated among Walkerton participants with severe or mild gastroenteritis (hazard ratio [HR] for severe gastroenteritis 0.74, 95% confidence interval [CI] 0.38–1.43, mild gastroenteritis HR 0.64, 95% CI 0.42–0.98). Compared with Walkerton participants who had no gastroenteritis, risk of death or cardiovascular event was not elevated among participants with severe or mild gastroenteritis. Interpretation: There was no increase in the risk of cardiovascular disease in the decade following acute infection during a major E. coli O157:H7 outbreak. PMID:23166291

  17. Transcriptional effects of CRP* expression in Escherichia coli

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    Ghosh Debashis

    2009-08-01

    Full Text Available Abstract Background Escherichia coli exhibits diauxic growth in sugar mixtures due to CRP-mediated catabolite repression and inducer exclusion related to phosphotransferase system enzyme activity. Replacement of the native crp gene with a catabolite repression mutant (referred to as crp* enables co-utilization of glucose and other sugars in E. coli. While previous studies have examined the effects of expressing CRP* mutants on the expression of specific catabolic genes, little is known about the global transcriptional effects of CRP* expression. In this study, we compare the transcriptome of E. coli W3110 (expressing wild-type CRP to that of mutant strain PC05 (expressing CRP* in the presence and absence of glucose. Results The glucose effect is significantly suppressed in strain PC05 relative to strain W3110. The expression levels of glucose-sensitive genes are generally not altered by glucose to the same extent in strain PCO5 as compared to W3110. Only 23 of the 80 genes showing significant differential expression in the presence of glucose for strain PC05 are present among the 418 genes believed to be directly regulated by CRP. Genes involved in central carbon metabolism (including several TCA cycle genes and amino acid biosynthesis, as well as genes encoding nutrient transport systems are among those whose transcript levels are most significantly affected by CRP* expression. We present a detailed transcription analysis and relate these results to phenotypic differences between strains expressing wild-type CRP and CRP*. Notably, CRP* expression in the presence of glucose results in an elevated intracellular NADPH concentration and reduced NADH concentration relative to wild-type CRP. Meanwhile, a more drastic decrease in the NADPH/NADP+ ratio is observed for the case of CRP* expression in strains engineered to reduce xylose to xylitol via a heterologously expressed, NADPH-dependent xylose reductase. Altered expression levels of

  18. Protein abundance profiling of the Escherichia coli cytosol

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    Mann Matthias

    2008-02-01

    Full Text Available Abstract Background Knowledge about the abundance of molecular components is an important prerequisite for building quantitative predictive models of cellular behavior. Proteins are central components of these models, since they carry out most of the fundamental processes in the cell. Thus far, protein concentrations have been difficult to measure on a large scale, but proteomic technologies have now advanced to a stage where this information becomes readily accessible. Results Here, we describe an experimental scheme to maximize the coverage of proteins identified by mass spectrometry of a complex biological sample. Using a combination of LC-MS/MS approaches with protein and peptide fractionation steps we identified 1103 proteins from the cytosolic fraction of the Escherichia coli strain MC4100. A measure of abundance is presented for each of the identified proteins, based on the recently developed emPAI approach which takes into account the number of sequenced peptides per protein. The values of abundance are within a broad range and accurately reflect independently measured copy numbers per cell. As expected, the most abundant proteins were those involved in protein synthesis, most notably ribosomal proteins. Proteins involved in energy metabolism as well as those with binding function were also found in high copy number while proteins annotated with the terms metabolism, transcription, transport, and cellular organization were rare. The barrel-sandwich fold was found to be the structural fold with the highest abundance. Highly abundant proteins are predicted to be less prone to aggregation based on their length, pI values, and occurrence patterns of hydrophobic stretches. We also find that abundant proteins tend to be predominantly essential. Additionally we observe a significant correlation between protein and mRNA abundance in E. coli cells. Conclusion Abundance measurements for more than 1000 E. coli proteins presented in this work

  19. Overexpression of peanut diacylglycerol acyltransferase 2 in Escherichia coli.

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    Zhenying Peng

    Full Text Available Diacylglycerol acyltransferase (DGAT is the rate-limiting enzyme in triacylglycerol biosynthesis in eukaryotic organisms. Triacylglycerols are important energy-storage oils in plants such as peanuts, soybeans and rape. In this study, Arachis hypogaea type 2 DGAT (AhDGAT2 genes were cloned from the peanut cultivar 'Luhua 14' using a homologous gene sequence method and rapid amplification of cDNA ends. To understand the role of AhDGAT2 in triacylglycerol biosynthesis, two AhDGAT2 nucleotide sequences that differed by three amino acids were expressed as glutathione S-transferase (GST fusion proteins in Escherichia coli Rosetta (DE3. Following IPTG induction, the isozymes (AhDGAT2a and AhDGAT2b were expressed as 64.5 kDa GST fusion proteins. Both AhDGAT2a and AhDGAT2b occurred in the host cell cytoplasm and inclusion bodies, with larger amounts in the inclusion bodies. Overexpression of AhDGATs depressed the host cell growth rates relative to non-transformed cells, but cells harboring empty-vector, AhDGAT2a-GST, or AhDGAT2b-GST exhibited no obvious growth rate differences. Interestingly, induction of AhDGAT2a-GST and AhDGAT2b-GST proteins increased the sizes of the host cells by 2.4-2.5 times that of the controls (post-IPTG induction. The total fatty acid (FA levels of the AhDGAT2a-GST and AhDGAT2a-GST transformants, as well as levels of C12:0, C14:0, C16:0, C16:1, C18:1n9c and C18:3n3 FAs, increased markedly, whereas C15:0 and C21:0 levels were lower than in non-transformed cells or those containing empty-vectors. In addition, the levels of some FAs differed between the two transformant strains, indicating that the two isozymes might have different functions in peanuts. This is the first time that a full-length recombinant peanut DGAT2 has been produced in a bacterial expression system and the first analysis of its effects on the content and composition of fatty acids in E. coli. Our results indicate that AhDGAT2 is a strong candidate gene for

  20. Role of wild birds as carriers of multi-drug resistant Escherichia coli and Escherichia vulneris.

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    Shobrak, Mohammed Y; Abo-Amer, Aly E

    2014-01-01

    Emergence and distribution of multi-drug resistant (MDR) bacteria in environments pose a risk to human and animal health. A total of 82 isolates of Escherichia spp. were recovered from cloacal swabs of migrating and non-migrating wild birds. All bacterial isolates were identified and characterized morphologically and biochemically. 72% and 50% of isolates recovered from non-migrating and migrating birds, respectively, showed positive congo red dye binding (a virulence factor). Also, hemolysin production (a virulence factor) was showed in 8% of isolates recovered from non-migrating birds and 75% of isolates recovered from migrating birds. All isolates recovered from non-migrating birds were found resistant to Oxacillin while all isolates recovered from migrating birds demonstrated resistance to Oxacillin, Chloramphenicol, Oxytetracycline and Lincomycin. Some bacterial isolates recovered from non-migrating birds and migrating birds exhibited MDR phenotype. The MDR isolates were further characterized by API 20E and 16S rRNA as E. coli and E. vulneris. MDR Escherichia isolates contain ~1-5 plasmids of high-molecular weights. Accordingly, wild birds could create a potential threat to human and animal health by transmitting MDR bacteria to water streams and other environmental sources through their faecal residues, and to remote regions by migration.

  1. Depletion of acidic phospholipids influences chromosomal replication in Escherichia coli.

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    Fingland, Nicholas; Flåtten, Ingvild; Downey, Christopher D; Fossum-Raunehaug, Solveig; Skarstad, Kirsten; Crooke, Elliott

    2012-12-01

    In Escherichia coli, coordinated activation and deactivation of DnaA allows for proper timing of the initiation of chromosomal synthesis at the origin of replication (oriC) and assures initiation occurs once per cell cycle. In vitro, acidic phospholipids reactivate DnaA, and in vivo depletion of acidic phospholipids, results in growth arrest. Growth can be restored by the expression of a mutant form of DnaA, DnaA(L366K), or by oriC-independent DNA synthesis, suggesting acidic phospholipids are required for DnaA- and oriC-dependent replication. We observe here that when acidic phospholipids were depleted, replication was inhibited with a concomitant reduction of chromosomal content and cell mass prior to growth arrest. This global shutdown of biosynthetic activity was independent of the stringent response. Restoration of acidic phospholipid synthesis resulted in a resumption of DNA replication prior to restored growth, indicating a possible cell-cycle-specific growth arrest had occurred with the earlier loss of acidic phospholipids. Flow cytometry, thymidine uptake, and quantitative polymerase chain reaction data suggest that a deficiency in acidic phospholipids prolonged the time required to replicate the chromosome. We also observed that regardless of the cellular content of acidic phospholipids, expression of mutant DnaA(L366K) altered the DNA content-to-cell mass ratio.

  2. Swimming patterns and dynamics of simulated Escherichia coli bacteria.

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    Zonia, Laura; Bray, Dennis

    2009-11-06

    A spatially and temporally realistic simulation of Escherichia coli chemotaxis was used to investigate the swimming patterns of wild-type and mutant bacteria within a rectangular arena in response to chemoattractant gradients. Swimming dynamics were analysed during long time series with phase-space trajectories, power spectra and estimations of fractal dimensions (FDs). Cell movement displayed complex trajectories in the phase space owing to interaction of multiple attractors that captured runs and tumbles. Deletion of enzymes responsible for adaptation (CheR and CheB) restricted the pattern of bacterial swimming in the absence of a gradient. In the presence of a gradient, there was a strong increase in trajectories arising from runs and attenuation of those arising from tumbles. Similar dynamics were observed for mutants lacking CheY, which are unable to tumble. The deletion of CheR, CheB and CheY also caused significant shifts in chemotaxis spectral frequencies. Rescaled range analysis and estimation of FD suggest that wild-type bacteria display characteristics of fractional Brownian motion with positive correlation between past and future events. These results reveal an underlying order in bacterial swimming dynamics, which enables a chemotactic search strategy conforming to a fractal walk.

  3. Animal Reservoirs of Shiga Toxin-Producing Escherichia coli.

    Science.gov (United States)

    Persad, Anil K; LeJeune, Jefrey T

    2014-08-01

    Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.

  4. Expanded flux variability analysis on metabolic network of Escherichia coli

    Institute of Scientific and Technical Information of China (English)

    CHEN Tong; XIE ZhengWei; OUYANG Qi

    2009-01-01

    Flux balance analysis,based on the mass conservation law in a cellular organism,has been extensively employed to study the interplay between structures and functions of cellular metabolic networks.Consequently,the phenotypes of the metabolism can be well elucidated.In this paper,we introduce the Expanded Flux Variability Analysis (EFVA) to characterize the intrinsic nature of metabolic reactions,such as flexibility,modularity and essentiality,by exploring the trend of the range,the maximum and the minimum flux of reactions.We took the metabolic network of Escherichia coli as an example and analyzed the variability of reaction fluxes under different growth rate constraints.The average variability of all reactions decreases dramatically when the growth rate increases.Consider the noise effect on the metabolic system,we thus argue that the microorganism may practically grow under a suboptimal state.Besides,under the EFVA framework,the reactions are easily to be grouped into catabolic and anabolic groups.And the anabolic groups can be further assigned to specific biomass constitute.We also discovered the growth rate dependent essentiality of reactions.

  5. Characterization of avian pathogenic Escherichia coli isolated in eastern China.

    Science.gov (United States)

    Dou, Xinhong; Gong, Jiansen; Han, Xiangan; Xu, Ming; Shen, Haiyu; Zhang, Di; Zhuang, Linlin; Liu, Jiasheng; Zou, Jianmin

    2016-01-15

    In order to investigate the biological characteristics of avian pathogenic Escherichia coli (APEC) isolated in eastern China, a total of 243 isolates were isolated from diseased poultry on different farms during the period from 2007 to 2014. These isolates were characterized for serogroups (polymerase chain reaction and agglutination), the presence of virulence-associated genes (fimC, iss, ompA, fyuA, stx2f, iroC, iucD, hlyE, tsh, cvaC, irp2, and papC) and class I integrons (polymerase chain reaction), drug susceptibilities (disk diffusion method) and the biofilm-forming abilities (semi-quantitative method). The results showed that the most predominant serogroups were O78 (87 isolates, 35.8%) and O2 (35 isolates, 14.4%). Gene profiling found that fimC and ompA were frequently distributed among the isolates and that 77.4% of the isolates were positive for class 1 integrons. Overall, isolates displayed resistance to tetracycline (97.5%), nalidixic acid (82.3%), ampicillin (81.1%), sulphafurazole (80.7%), streptomycin (79.0%), trimethoprim (78.2%) and cotrimoxazole (78.2%). Multiple-drug resistance was exhibited in 80.3% of the isolates, and the presence of class 1 integrons is associated with multidrug resistance. Finally, 151 isolates had the ability to form biofilms in vitro, and drug resistance seemed relative to biofilm-forming abilities.

  6. Two Linked Enteroinvasive Escherichia coli Outbreaks, Nottingham, UK, June 2014

    Science.gov (United States)

    MacGregor, Vanessa; Robbins, Vivienne; Bayliss, Laura; Chattaway, Marie Anne; Dallman, Tim; Ready, Derren; Aird, Heather; Puleston, Richard; Hawker, Jeremy

    2016-01-01

    Enteroinvasive Escherichia coli (EIEC) outbreaks are uncommon in Europe. In June 2014, two EIEC outbreaks occurred in Nottingham, UK, within 2 days; outbreak A was linked to a takeaway restaurant and outbreak B to a wedding party. We conducted 2 analytical studies: a case–control study for outbreak A and a cohort study for outbreak B. We tested microbiological and environmental samples, including by using whole-genome sequencing. For both outbreaks combined, we identified 157 probable case-patients; 27 were laboratory-confirmed as EIEC O96:H19–positive. Combined epidemiologic, microbiological, and environmental findings implicated lettuce as the vehicle of infection in outbreak A, but the source of the organism remained unknown. Whole-genome sequencing identified the same organism in cases from both outbreaks, but no epidemiologic link was confirmed. These outbreaks highlight that EIEC has the capacity to cause large and severe gastrointestinal disease outbreaks and should be considered as a potential pathogen in foodborne outbreaks in Europe. PMID:27314432

  7. SOS processing of unique oxidative DNA damages in Escherichia coli.

    Science.gov (United States)

    Laspia, M F; Wallace, S S

    1989-05-05

    phi X174 replicative form (RF) I transfecting DNA containing thymine glycols (5,6-dihydroxy-5,6-dihydrothymine), urea glycosides or apurinic (AP) sites was used to study SOS processing of unique DNA damages in Escherichia coli. All three lesions can be found in DNA damaged by chemical oxidants or radiation and are representative of several common structural modifications of DNA bases. When phi X DNA containing thymine glycols was transfected into host cells that were ultraviolet-irradiated to induce the SOS response, a substantial increase in survival was observed compared to transfection into uninduced hosts. Studies with mutants demonstrated that both the activated form of RecA and UmuDC proteins were required for this reactivation. In contrast, no increase in survival was observed when DNA containing urea glycosides or AP sites was transfected into ultraviolet-induced hosts. These data suggest that SOS-induced reactivation does not reflect a generalized repair system for all replication-blocking, lethal lesions but rather that the efficiency of reactivation is damage dependent. Further, we found that a significant fraction of potentially lethal thymine glycols could be ultraviolet-reactivated in an umuC lexA recA-independent manner, suggesting the existence of an as yet uncharacterized damage-inducible SOS-independent mode of thymine glycol repair.

  8. Noise characteristics of the Escherichia coli rotary motor

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    Clausznitzer Diana

    2011-09-01

    Full Text Available Abstract Background The chemotaxis pathway in the bacterium Escherichia coli allows cells to detect changes in external ligand concentration (e.g. nutrients. The pathway regulates the flagellated rotary motors and hence the cells' swimming behaviour, steering them towards more favourable environments. While the molecular components are well characterised, the motor behaviour measured by tethered cell experiments has been difficult to interpret. Results We study the effects of sensing and signalling noise on the motor behaviour. Specifically, we consider fluctuations stemming from ligand concentration, receptor switching between their signalling states, adaptation, modification of proteins by phosphorylation, and motor switching between its two rotational states. We develop a model which includes all signalling steps in the pathway, and discuss a simplified version, which captures the essential features of the full model. We find that the noise characteristics of the motor contain signatures from all these processes, albeit with varying magnitudes. Conclusions Our analysis allows us to address how cell-to-cell variation affects motor behaviour and the question of optimal pathway design. A similar comprehensive analysis can be applied to other two-component signalling pathways.

  9. rec genes and homologous recombination proteins in Escherichia coli.

    Science.gov (United States)

    Clark, A J

    1991-04-01

    The twenty-five years since the first published report of recA mutants in Escherichia coli has seen the identification of more than 12 other recombination genes. The genes are usually grouped into three pathways named RecBCD, RecE and RecF for prominent genes which function in each. A proposal is made here that there are two RecF pathways, one sensitive and one resistant to exonuclease I, the SbcB enzyme. Five methods of grouping the genes functionally are discussed: 1) by enzyme activity, 2) by common indirect suppressor, 3) by common phenotype, 4) by common regulation and 5) by epistasis. Five classes of enzyme activities implicated in recombination are discussed according to their involvement in presynapsis, synapsis or postsynapsis: 1) nucleases 2) helicases 3) DNA-binding proteins 4) topoisomerases and 5) ligases. Plausible presynaptic steps for the RecBCD, RecF (SbcBS) and RecE pathways show the common feature of generating 3'-terminated single-stranded DNA (ssDNA). On this ssDNA it is proposed that a RecA protein filament is generated discontinuously. This implies the existence of nucleation and possibly measurement and 3' end protection proteins. Specific proposals are made for which recombination genes might encode such products. Finally the generality of the RecA-ssDNA-filament mechanism of synapsis in the cellular biological world is discussed.

  10. Evidence for a human-specific Escherichia coli clone.

    Science.gov (United States)

    Clermont, Olivier; Lescat, Mathilde; O'Brien, Claire L; Gordon, David M; Tenaillon, Olivier; Denamur, Erick

    2008-04-01

    Escherichia coli is a widespread commensal of the vertebrate intestinal tract. Until recently, no strong association between a particular clone and a given host species has been found. However, members of the B2 subgroup VIII clone with an O81 serotype appear to be human host specific. To determine the degree of host specificity exhibited by this clone, a PCR-based assay was used to screen 723 faecal and clinical isolates from humans, and 904 faecal isolates from animals. This clone was not detected among the animal isolates, but was discovered in people living in Africa, Europe and South America. The clone is rarely isolated from people suffering from intestinal or extraintestinal disease and is avirulent in a mouse model of extraintestinal infection. Fine-scale epidemiological analysis suggests that this clone is competitively dominant relative to other members of the B2 phylogenetic group and that it has increased in frequency over the past 20 years. This clone appears to be a good candidate for use as a probiotic, and may be suitable as an indicator of human faecal contamination in microbial source tracking studies.

  11. Chromosome structuring limits genome plasticity in Escherichia coli.

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    Emilie Esnault

    2007-12-01

    Full Text Available Chromosome organizations of related bacterial genera are well conserved despite a very long divergence period. We have assessed the forces limiting bacterial genome plasticity in Escherichia coli by measuring the respective effect of altering different parameters, including DNA replication, compositional skew of replichores, coordination of gene expression with DNA replication, replication-associated gene dosage, and chromosome organization into macrodomains. Chromosomes were rearranged by large inversions. Changes in the compositional skew of replichores, in the coordination of gene expression with DNA replication or in the replication-associated gene dosage have only a moderate effect on cell physiology because large rearrangements inverting the orientation of several hundred genes inside a replichore are only slightly detrimental. By contrast, changing the balance between the two replication arms has a more drastic effect, and the recombinational rescue of replication forks is required for cell viability when one of the chromosome arms is less than half than the other one. Macrodomain organization also appears to be a major factor restricting chromosome plasticity, and two types of inverted configurations severely affect the cell cycle. First, the disruption of the Ter macrodomain with replication forks merging far from the normal replichore junction provoked chromosome segregation defects. The second major problematic configurations resulted from inversions between Ori and Right macrodomains, which perturb nucleoid distribution and early steps of cytokinesis. Consequences for the control of the bacterial cell cycle and for the evolution of bacterial chromosome configuration are discussed.

  12. Isolation and characterization of Escherichia coli mutants lacking inducible cyanase.

    Science.gov (United States)

    Guilloton, M; Karst, F

    1987-03-01

    To determine the physiological role of cyanate aminohydrolase (cyanase, EC 3.5.5.3) in bacteria, mutants of Escherichia coli K12 devoid of this inducible activity were isolated and their properties investigated. Five independent mutations were localized next to lac; three of them lay between lacY and codA. Thus cyanase activity could depend on the integrity of one gene or set of clustered genes; we propose for this locus the symbol cnt. Growth of the mutant stains was more sensitive to cyanate than growth of wild-type strains. This difference was noticeable in synthetic medium in the presence of low concentrations of cyanate (less than or equal to 1 mM). Higher concentrations inhibited growth of both wild-type and mutant strains. Urea in aqueous solutions dissociates slowly into ammonium cyanate. Accordingly wild-type strains were able to grow on a synthetic medium containing 0.5 M-urea whereas mutants lacking cyanase were not. We conclude that cyanase could play a role in destroying exogenous cyanate originating from the dissociation of carbamoyl compounds such as urea; alternatively cyanate might constitute a convenient nitrogen source for bacteria able to synthesize cyanase in an inducible way.

  13. The amino acid sequence of Escherichia coli cyanase.

    Science.gov (United States)

    Chin, C C; Anderson, P M; Wold, F

    1983-01-10

    The amino acid sequence of the enzyme cyanase (cyanate hydrolase) from Escherichia coli has been determined by automatic Edman degradation of the intact protein and of its component peptides. The primary peptides used in the sequencing were produced by cyanogen bromide cleavage at the methionine residues, yielding 4 peptides plus free homoserine from the NH2-terminal methionine, and by trypsin cleavage at the 7 arginine residues after acetylation of the lysines. Secondary peptides required for overlaps and COOH-terminal sequences were produced by chymotrypsin or clostripain cleavage of some of the larger peptides. The complete sequence of the cyanase subunit consists of 156 amino acid residues (Mr 16,350). Based on the observation that the cysteine-containing peptide is obtained as a disulfide-linked dimer, it is proposed that the covalent structure of cyanase is made up of two subunits linked by a disulfide bond between the single cystine residue in each subunit. The native enzyme (Mr 150,000) then appears to be a complex of four or five such subunit dimers.

  14. Shiga toxins decrease enterohaemorrhagic Escherichia coli survival within Acanthamoeba castellanii.

    Science.gov (United States)

    Chekabab, Samuel M; Daigle, France; Charette, Steve J; Dozois, Charles M; Harel, Josée

    2013-07-01

    Enterohaemorrhagic Escherichia coli (EHEC) are zoonotic pathogens transmitted to humans through contaminated water or bovine products. One of the strategies used by pathogenic bacteria to survive in aquatic environments is using free-living amoebae as hosts. Acanthamoeba castellanii is an amoeba known to host several waterborne pathogens. This study investigates the survival of EHEC with A. castellanii, which could contribute to its spread and transmission to humans. We used a gentamicin protection assay as well as fluorescence and electron microscopy to monitor the intra-amoebae survival of EHEC O157:H7 over 24 h. The results showed that EHEC were able to survive within A. castellanii and that this survival was reduced by Shiga toxins (Stx) produced by EHEC. A toxic effect mediated by Stx was demonstrated by amoebae mortality and LDH release during co-culture of EHEC and amoeba. This work describes the ability of EHEC to survive within A. castellanii, and this host-pathogen interaction is partially controlled by the Stx. Thus, this ubiquitous amoeba could represent an environmental niche for EHEC survival and transmission.

  15. Iron induces bimodal population development by Escherichia coli.

    Science.gov (United States)

    DePas, William H; Hufnagel, David A; Lee, John S; Blanco, Luz P; Bernstein, Hans C; Fisher, Steve T; James, Garth A; Stewart, Philip S; Chapman, Matthew R

    2013-02-12

    Bacterial biofilm formation is a complex developmental process involving cellular differentiation and the formation of intricate 3D structures. Here we demonstrate that exposure to ferric chloride triggers rugose biofilm formation by the uropathogenic Escherichia coli strain UTI89 and by enteric bacteria Citrobacter koseri and Salmonella enterica serovar typhimurium. Two unique and separable cellular populations emerge in iron-triggered, rugose biofilms. Bacteria at the air-biofilm interface express high levels of the biofilm regulator csgD, the cellulose activator adrA, and the curli subunit operon csgBAC. Bacteria in the interior of rugose biofilms express low levels of csgD and undetectable levels of matrix components curli and cellulose. Iron activation of rugose biofilms is linked to oxidative stress. Superoxide generation, either through addition of phenazine methosulfate or by deletion of sodA and sodB, stimulates rugose biofilm formation in the absence of high iron. Additionally, overexpression of Mn-superoxide dismutase, which can mitigate iron-derived reactive oxygen stress, decreases biofilm formation in a WT strain upon iron exposure. Not only does reactive oxygen stress promote rugose biofilm formation, but bacteria in the rugose biofilms display increased resistance to H(2)O(2) toxicity. Altogether, we demonstrate that iron and superoxide stress trigger rugose biofilm formation in UTI89. Rugose biofilm development involves the elaboration of two distinct bacterial populations and increased resistance to oxidative stress.

  16. Interaction of enteroaggregative Escherichia coli with salad leaves.

    Science.gov (United States)

    Berger, Cedric N; Shaw, Robert K; Ruiz-Perez, Fernando; Nataro, James P; Henderson, Ian R; Pallen, Mark J; Frankel, Gad

    2009-08-01

    Enteroaggregative Escherichia coli (EAEC) are important human pathogens. However, their environmental reservoir is unknown. As fresh salad leaves are increasingly recognized as an important environmental vector for human pathogens, we investigated leaf attachment capability of EAEC strains. We found that binding of clinical EAEC isolates to leaves from Eruca vesicaria (commonly known as rocket or arugula) can be divided into high, moderate and low adherent phenotypes. Using the prototype EAEC strain 042 to investigate the underlining mechanisms involved in leaf attachment, we found small attached bacterial aggregates over the entire leaf surface and dense bacterial attachment to the guard cell of the stomata. An aaf 042 mutant lost the ability to bind the epidermis while retaining stomatal adherence. In contrast, a fliC 042 mutant retained the ability to bind the epidermis but lost stomatal tropism. These results show that multiple adherence factors are involved in the interaction of EAEC with leaves, that EAEC uses similar colonization factors to bind mucosal and leaf surfaces and that fresh produce might be an important reservoir of EAEC strains.

  17. Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Po-Han Chan

    Full Text Available Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs. The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm. The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6 cells/mL.

  18. Photoluminescent gold nanoclusters as sensing probes for uropathogenic Escherichia coli.

    Science.gov (United States)

    Chan, Po-Han; Ghosh, Bhaswati; Lai, Hong-Zheng; Peng, Hwei-Ling; Mong, Kwok Kong Tony; Chen, Yu-Chie

    2013-01-01

    Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs). The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann) were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH) was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.95±0.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ~630 nm (λexcitation = 375 nm). The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ~2×10(6) cells/mL.

  19. An Integrated System for Precise Genome Modification in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Huseyin Tas

    Full Text Available We describe an optimized system for the easy, effective, and precise modification of the Escherichia coli genome. Genome changes are introduced first through the integration of a 1.3 kbp Landing Pad consisting of a gene conferring resistance to tetracycline (tetA or the ability to metabolize the sugar galactose (galK. The Landing Pad is then excised as a result of double-strand breaks by the homing endonuclease I-SceI, and replaced with DNA fragments bearing the desired change via λ-Red mediated homologous recombination. Repair of the double strand breaks and counterselection against the Landing Pad (using NiCl2 for tetA or 2-deoxy-galactose for galK allows the isolation of modified bacteria without the use of additional antibiotic selection. We demonstrate the power of this method to make a variety of genome modifications: the exact integration, without any extraneous sequence, of the lac operon (~6.5 kbp to any desired location in the genome and without the integration of antibiotic markers; the scarless deletion of ribosomal rrn operons (~6 kbp through either intrachromosomal or oligonucleotide recombination; and the in situ fusion of native genes to fluorescent reporter genes without additional perturbation.

  20. Characterization of urinary Escherichia coli O75 strains.

    Science.gov (United States)

    Nimmich, W; Voigt, W; Seltmann, G

    1997-01-01

    Forty-four Escherichia coli O75 strains from patients with urinary tract infections were characterized by a variety of methods to obtain evidence of their clonal distribution and uropathogenic properties. By K and H antigen typing, the strains were divided into the following serotypes: O75:K5:H- (18 strains), O75:K95:H- (10 strains), O75:K95:H5 (7 strains), O75:K100:H5 (4 strains), and O75:K-:H55 (5 strains). Generally, biotyping proved to be of no discriminative value. With two exceptions the strains were found to be sensitive to the bactericidal effect of normal human serum. As shown by multilocus enzyme electrophoresis, the whole-cell protein profile (WCPP), and the patterns of the outer membrane proteins and lipopolysaccharides, all but the five O75:H55 strains were genetically closely related to each other and could be classified into one clonal group. The O75:K-:H55 strains proved to be quite different and lacked type 1 fimbriae. All 17 K95 (H-, H5) strains produced hemolysin and P fimbriae. Five of the O75:K5:H- strains were different from the other K5 strains by showing hemagglutinating properties, on the basis of the presence of the OX adhesin. The last two groups are suggested to be uropathogenic and are proposed to represent separate clonal groups or subgroups. PMID:9114391

  1. Metabolic engineering of Escherichia coli to improve recombinant protein production.

    Science.gov (United States)

    Liu, Min; Feng, Xinjun; Ding, Yamei; Zhao, Guang; Liu, Huizhou; Xian, Mo

    2015-12-01

    Escherichia coli is one of the most widely used strains for recombinant protein production. However, obstacles also exist in both academic researches and industrial applications, such as the metabolic burden, the carbon source waste, and the cells' physiological deterioration. This article reviews recent approaches for improving recombinant protein production in metabolic engineering, including workhorse selection, stress factor application, and carbon flux regulation. Selecting a suitable host is the first key point for recombinant protein production. In general, it all depends on characteristics of the strains and the target proteins. It will be triggered cells physiological deterioration when the medium is significantly different from the cell's natural environment. Coexpression of stress factors can help proteins to fold into their native conformation. Carbon flux regulation is a direct approach for redirecting more carbon flux toward the desirable pathways and products. However, some undesirable consequences are usually found in metabolic engineering, such as glucose transport inhibition, cell growth retardation, and useless metabolite accumulation. More efficient regulators and platform cell factories should be explored to meet a variety of production demands.

  2. Improving heterologous polyketide production in Escherichia coli by transporter engineering.

    Science.gov (United States)

    Yang, Jingya; Xiong, Zhi-Qiang; Song, Shu-Jie; Wang, Jian-Feng; Lv, Hua-Jun; Wang, Yong

    2015-10-01

    Expelling heterologous compounds out of hosts by transporters is a potential strategy to enhance product titers in microbial cell factories. In this work, to increase heterologous polyketide 6-deoxyerythronolide B (6dEB, erythromycin precursor) production, tripartite multidrug efflux pumps MacAB-TolC, AcrAB-TolC, MdtEF-TolC, and MexAB-OprM were modulated in a 6dEB production strain. Compared with the control, overexpression of a single component of efflux pumps (except oprM) repressed 6dEB production, but modulation of two components MacA and MacB or the complete pumps MacAB-TolC and MdtEF-TolC significantly improved 6dEB titer by 100 ± 11, 118 ± 54, and 98 ± 12 %, respectively. In addition, to avoid the challenging fine-tuning components of pumps, the transcriptional regulators of efflux pumps were modulated to improve the 6dEB production. Overexpression of RpoH (activator of MdtEF-TolC) and EvgA (activator of EmrKY-TolC and AcrAD-TolC) strongly increased 6dEB titer by 152 ± 54 and 142 ± 85 %, respectively. This is the first report of transporter engineering for improving heterologous polyketide production in Escherichia coli. Our results provide an effective strategy for improving the yield of the heterologous products in chassis cell.

  3. Recombination Phenotypes of Escherichia coli greA Mutants

    Directory of Open Access Journals (Sweden)

    Poteete Anthony R

    2011-03-01

    Full Text Available Abstract Background The elongation factor GreA binds to RNA polymerase and modulates transcriptional pausing. Some recent research suggests that the primary role of GreA may not be to regulate gene expression, but rather, to promote the progression of replication forks which collide with RNA polymerase, and which might otherwise collapse. Replication fork collapse is known to generate dsDNA breaks, which can be recombinogenic. It follows that GreA malfunction could have consequences affecting homologous recombination. Results Escherichia coli mutants bearing substitutions of the active site acidic residues of the transcription elongation factor GreA, D41N and E44K, were isolated as suppressors of growth inhibition by a toxic variant of the bacteriophage lambda Red-beta recombination protein. These mutants, as well as a D41A greA mutant and a greA deletion, were tested for proficiency in recombination events. The mutations were found to increase the efficiency of RecA-RecBCD-mediated and RecA-Red-mediated recombination, which are replication-independent, and to decrease the efficiency of replication-dependent Red-mediated recombination. Conclusion These observations provide new evidence for a role of GreA in resolving conflicts between replication and transcription.

  4. Identification of Uropathogenic Escherichia coli Surface Proteins by Shotgun Proteomics

    Science.gov (United States)

    Walters, Matthew S.; Mobley, Harry L.T.

    2009-01-01

    Uropathogenic Escherichia coli (UPEC) cause the majority of uncomplicated urinary tract infections in humans. In the process of identifying candidate antigens for a vaccine, two methods for the identification of the UPEC surface proteome during growth in human urine were investigated. The first approach utilized a protease to ‘shave’ surface-exposed peptides from the bacterial cell surface and identify them by mass spectrometry. Although this approach has been successfully applied to a Gram-positive pathogen, the adaptation to Gram-negative UPEC resulted in cytoplasmic protein contamination. In a more direct approach, whole-cell bacteria were labeled with a biotin tag to indicate surface-exposed peptides and two-dimensional liquid chromatography-tandem mass spectrometry (2-DLC-MS/MS) was used to identify proteins isolated from the outer membrane. This method discovered 25 predicted outer membrane proteins expressed by UPEC while growing in human urine. Nine of the 25 predicted outer membrane proteins were part of iron transport systems or putative iron-regulated virulence proteins, indicating the importance of iron acquisition during growth in urine. One of the iron transport proteins identified, Hma, appears to be a promising vaccine candidate is being further investigated. The method described here presents a system to rapidly identify the outer membrane proteome of bacteria, which may prove valuable in vaccine development. PMID:19426766

  5. Fast, multiphase volume adaptation to hyperosmotic shock by Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Teuta Pilizota

    Full Text Available All living cells employ an array of different mechanisms to help them survive changes in extra cellular osmotic pressure. The difference in the concentration of chemicals in a bacterium's cytoplasm and the external environment generates an osmotic pressure that inflates the cell. It is thought that the bacterium Escherichia coli use a number of interconnected systems to adapt to changes in external pressure, allowing them to maintain turgor and live in surroundings that range more than two-hundred-fold in external osmolality. Here, we use fluorescence imaging to make the first measurements of cell volume changes over time during hyperosmotic shock and subsequent adaptation on a single cell level in vivo with a time resolution on the order of seconds. We directly observe two previously unseen phases of the cytoplasmic water efflux upon hyperosmotic shock. Furthermore, we monitor cell volume changes during the post-shock recovery and observe a two-phase response that depends on the shock magnitude. The initial phase of recovery is fast, on the order of 15-20 min and shows little cell-to-cell variation. For large sucrose shocks, a secondary phase that lasts several hours adds to the recovery. We find that cells are able to recover fully from shocks as high as 1 Osmol/kg using existing systems, but that for larger shocks, protein synthesis is required for full recovery.

  6. Ferritinophagy drives uropathogenic Escherichia coli persistence in bladder epithelial cells.

    Science.gov (United States)

    Bauckman, Kyle A; Mysorekar, Indira U

    2016-05-01

    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.

  7. Virulence and Fitness Determinants of Uropathogenic Escherichia coli.

    Science.gov (United States)

    Subashchandrabose, Sargurunathan; Mobley, Harry L T

    2015-08-01

    Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) is a major global public health concern. Increasing antibiotic resistance found in clinical UPEC isolates underscores the immediate need for development of novel therapeutics against this pathogen. Better understanding of the fitness and virulence mechanisms that are integral to the pathogenesis of UTI will facilitate identification of novel strategies to prevent and treat infection with UPEC. Working towards that goal, the global UPEC research community has made great strides at unraveling various virulence and fitness genes. Here, we summarize major findings on virulence and fitness determinants that enable UPEC to successfully survive and colonize the urinary tract of mammalian hosts. Major sections of this chapter are devoted to the role of iron acquisition systems, metabolic pathways, fimbriae, flagella, toxins, biofilm formation, capsule, and strain-specific genes in the initiation and progression of UTIs. Transcriptomes of UPEC during experimental UTI in a murine model and naturally occurring UTI in women are compared to elucidate virulence mechanisms specifically involved in human UTI. Capitalizing on the advances in molecular pathogenesis research by translating these findings will help develop better clinical strategies for prevention and management of UTIs.

  8. Mutators and hypermutability in bacteria: the Escherichia coli paradigm

    Indian Academy of Sciences (India)

    R. Jayaraman

    2009-12-01

    Mutators (also called hypermutators) are mutants which show higher than normal spontaneous mutation frequencies, ranging from 10–20 fold to 100–1000 fold higher, or sometimes even more, than wild-type cells. Being a mutator is advantageous to the organism when adapting to environmental changes or stressful situations, such as moving from one habitat to another, one host to another, exposure to antibiotics etc. However, this advantage is only a short-term benefit. In the long run, hypermutability leads to a fitness disadvantage due to accumulation of deleterious mutations or antagonistic pleiotropy or both. Contrary to intuitive expectations, hypermutability is commonly encountered in natural bacterial populations, especially among clinical isolates. It is believed to be involved in the emergence of antibiotic resistance and a hindrance to the treatment of infectious diseases. Here, I review the state of knowledge on the common mechanisms of hypermutability such as errors/defects in DNA replication, proof reading, mismatch repair, oxidative DNA damage, mistranslation etc., as well as phenomena associated with these processes, using Escherichia coli as a paradigmatic organism.

  9. Ensemble modeling for aromatic production in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Matthew L Rizk

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

  10. Isoprenoid Pathway Optimization for Taxol Precursor Overproduction in Escherichia coli

    Science.gov (United States)

    Ajikumar, Parayil Kumaran; Xiao, Wen-Hai; Tyo, Keith E. J.; Wang, Yong; Simeon, Fritz; Leonard, Effendi; Mucha, Oliver; Phon, Too Heng; Pfeifer, Blaine; Stephanopoulos, Gregory

    2011-01-01

    Taxol (paclitaxel) is a potent anticancer drug first isolated from the Taxus brevifolia Pacific yew tree. Currently, cost-efficient production of Taxol and its analogs remains limited. Here, we report a multivariate-modular approach to metabolic-pathway engineering that succeeded in increasing titers of taxadiene—the first committed Taxol intermediate—approximately 1 gram per liter (~15,000-fold) in an engineered Escherichia coli strain. Our approach partitioned the taxadiene metabolic pathway into two modules: a native upstream methylerythritol-phosphate (MEP) pathway forming isopentenyl pyrophosphate and a heterologous downstream terpenoid–forming pathway. Systematic multivariate search identified conditions that optimally balance the two pathway modules so as to maximize the taxadiene production with minimal accumulation of indole, which is an inhibitory compound found here. We also engineered the next step in Taxol biosynthesis, a P450-mediated 5α-oxidation of taxadiene to taxadien-5α-ol. More broadly, the modular pathway engineering approach helped to unlock the potential of the MEP pathway for the engineered production of terpenoid natural products. PMID:20929806

  11. Inhibiting translation elongation can aid genome duplication in Escherichia coli.

    Science.gov (United States)

    Myka, Kamila K; Hawkins, Michelle; Syeda, Aisha H; Gupta, Milind K; Meharg, Caroline; Dillingham, Mark S; Savery, Nigel J; Lloyd, Robert G; McGlynn, Peter

    2016-12-11

    Conflicts between replication and transcription challenge chromosome duplication. Escherichia coli replisome movement along transcribed DNA is promoted by Rep and UvrD accessory helicases with Δrep ΔuvrD cells being inviable under rapid growth conditions. We have discovered that mutations in a tRNA gene, aspT, in an aminoacyl tRNA synthetase, AspRS, and in a translation factor needed for efficient proline-proline bond formation, EF-P, suppress Δrep ΔuvrD lethality. Thus replication-transcription conflicts can be alleviated by the partial sacrifice of a mechanism that reduces replicative barriers, namely translating ribosomes that reduce RNA polymerase backtracking. Suppression depends on RelA-directed synthesis of (p)ppGpp, a signalling molecule that reduces replication-transcription conflicts, with RelA activation requiring ribosomal pausing. Levels of (p)ppGpp in these suppressors also correlate inversely with the need for Rho activity, an RNA translocase that can bind to emerging transcripts and displace transcription complexes. These data illustrate the fine balance between different mechanisms in facilitating gene expression and genome duplication and demonstrate that accessory helicases are a major determinant of this balance. This balance is also critical for other aspects of bacterial survival: the mutations identified here increase persistence indicating that similar mutations could arise in naturally occurring bacterial populations facing antibiotic challenge.

  12. Forced resurgence and targeting of intracellular uropathogenic Escherichia coli reservoirs.

    Directory of Open Access Journals (Sweden)

    Matthew G Blango

    Full Text Available Intracellular quiescent reservoirs of uropathogenic Escherichia coli (UPEC, which can seed the bladder mucosa during the acute phase of a urinary tract infection (UTI, are protected from antibiotic treatments and are extremely difficult to eliminate. These reservoirs are a potential source for recurrent UTIs that affect millions annually. Here, using murine infection models and the bladder cell exfoliant chitosan, we demonstrate that intracellular UPEC populations shift within the stratified layers of the urothelium during the course of a UTI. Following invasion of the terminally differentiated superficial layer of epithelial cells that line the bladder lumen, UPEC can multiply and disseminate, eventually establishing reservoirs within underlying immature host cells. If given access, UPEC can invade the superficial and immature bladder cells equally well. As infected immature host cells differentiate and migrate towards the apical surface of the bladder, UPEC can reinitiate growth and discharge into the bladder lumen. By inducing the exfoliation of the superficial layers of the urothelium, chitosan stimulates rapid regenerative processes and the reactivation and efflux of quiescent intracellular UPEC reservoirs. When combined with antibiotics, chitosan treatment significantly reduces bacterial loads within the bladder and may therefore be of therapeutic value to individuals with chronic, recurrent UTIs.

  13. Immunochemical analysis of Taenia taeniaeformis antigens expressed in Escherichia coli.

    Science.gov (United States)

    Bowtell, D D; Saint, R B; Rickard, M D; Mitchell, G F

    1986-12-01

    Previously we reported the isolation of several Escherichia coli clones expressing fragments of Taenia taeniaeformis antigens as beta-galactosidase fused proteins (Bowtell, Saint, Rickard & Mitchell, 1984). Here we describe the isolation of additional antigen-expressing clones from a larval cDNA library and the assignment of these clones to 7 antigen families. These were isolated with a polyspecific rabbit antiserum raised to the oncosphere. Since this serum was capable of reacting with a large number of antigens, it was important to develop techniques for rapidly determining the identity of the native T. taeniaeformis molecule corresponding to a cloned antigen gene. These included active immunization of rabbits with fused proteins and several techniques involving affinity purification on immobilized fused proteins. The reactivity of the antigen-positive clones with sera from humans infected with related parasites was also assessed. Finally, immunization of mice with several fused proteins failed to protect against subsequent infection, although antigens previously identified as candidate host-protective antigens (Bowtell, Mitchell, Anders, Lightowlers & Rickard, 1983) have yet to be identified in the expression library.

  14. Enteropathogenic Escherichia coli infection triggers host phospholipid metabolism perturbations.

    Science.gov (United States)

    Wu, Y; Lau, B; Smith, S; Troyan, K; Barnett Foster, D E

    2004-12-01

    Enteropathogenic Escherichia coli (EPEC) specifically recognizes phosphatidylethanolamine (PE) on the outer leaflet of host epithelial cells. EPEC also induces apoptosis in epithelial cells, which results in increased levels of outer leaflet PE and increased bacterial binding. Consequently, it is of interest to investigate whether EPEC infection perturbs host cell phospholipid metabolism and whether the changes play a role in the apoptotic signaling. Our findings indicate that EPEC infection results in a significant increase in the epithelial cell PE level and a corresponding decrease in the phosphatidylcholine (PC) level. PE synthesis via both the de novo pathway and the serine decarboxylation pathway was enhanced, and de novo synthesis of phosphatidylcholine via CDP-choline was reduced. The changes were transitory, and the maximum change was noted after 4 to 5 h of infection. Addition of exogenous PC or CDP-choline to epithelial cells prior to infection abrogated EPEC-induced apoptosis, suggesting that EPEC infection inhibits the CTP-phosphocholine cytidylyltransferase step in PC synthesis, which is reportedly inhibited during nonmicrobially induced apoptosis. On the other hand, incorporation of exogenous PE by the host cells enhanced EPEC-induced apoptosis and necrosis without increasing bacterial adhesion. This is the first report that pathogen-induced apoptosis is associated with significant changes in PE and PC metabolism, and the results suggest that EPEC adhesion to a host membrane phospholipid plays a role in disruption of host phospholipid metabolism.

  15. Mechanisms of Escherichia coli inactivation by several disinfectants.

    Science.gov (United States)

    Cho, Min; Kim, Jaeeun; Kim, Jee Yeon; Yoon, Jeyong; Kim, Jae-Hong

    2010-06-01

    The objective of this study was to elucidate dominant mechanisms of inactivation, i.e. surface attack versus intracellular attack, during application of common water disinfectants such as ozone, chlorine dioxide, free chlorine and UV irradiation. Escherichia coli was used as a representative microorganism. During cell inactivation, protein release, lipid peroxidation, cell permeability change, damage in intracellular enzyme and morphological change were comparatively examined. For the same level of cell inactivation by chemical disinfectants, cell surface damage was more pronounced with strong oxidant such as ozone while damage in inner cell components was more apparent with weaker oxidant such as free chlorine. Chlorine dioxide showed the inactivation mechanism between these two disinfectants. The results suggest that the mechanism of cell inactivation is primarily related to the reactivity of chemical disinfectant. In contrast to chemical disinfectants, cell inactivation by UV occurred without any changes measurable with the methods employed. Understanding the differences in inactivation mechanisms presented herein is critical to identify rate-limiting steps involved in the inactivation process as well as to develop more effective disinfection strategies.

  16. Engineering modular ester fermentative pathways in Escherichia coli.

    Science.gov (United States)

    Layton, Donovan S; Trinh, Cong T

    2014-11-01

    Sensation profiles are observed all around us and are made up of many different molecules, such as esters. These profiles can be mimicked in everyday items for their uses in foods, beverages, cosmetics, perfumes, solvents, and biofuels. Here, we developed a systematic 'natural' way to derive these products via fermentative biosynthesis. Each ester fermentative pathway was designed as an exchangeable ester production module for generating two precursors- alcohols and acyl-CoAs that were condensed by an alcohol acyltransferase to produce a combinatorial library of unique esters. As a proof-of-principle, we coupled these ester modules with an engineered, modular, Escherichia coli chassis in a plug-and-play fashion to create microbial cell factories for enhanced anaerobic production of a butyrate ester library. We demonstrated tight coupling between the modular chassis and ester modules for enhanced product biosynthesis, an engineered phenotype useful for directed metabolic pathway evolution. Compared to the wildtype, the engineered cell factories yielded up to 48 fold increase in butyrate ester production from glucose.

  17. Production of salidroside in metabolically engineered Escherichia coli.

    Science.gov (United States)

    Bai, Yanfen; Bi, Huiping; Zhuang, Yibin; Liu, Chang; Cai, Tao; Liu, Xiaonan; Zhang, Xueli; Liu, Tao; Ma, Yanhe

    2014-01-01

    Salidroside (1) is the most important bioactive component of Rhodiola (also called as "Tibetan Ginseng"), which is a valuable medicinal herb exhibiting several adaptogenic properties. Due to the inefficiency of plant extraction and chemical synthesis, the supply of salidroside (1) is currently limited. Herein, we achieved unprecedented biosynthesis of salidroside (1) from glucose in a microorganism. First, the pyruvate decarboxylase ARO10 and endogenous alcohol dehydrogenases were recruited to convert 4-hydroxyphenylpyruvate (2), an intermediate of L-tyrosine pathway, to tyrosol (3) in Escherichia coli. Subsequently, tyrosol production was improved by overexpressing the pathway genes, and by eliminating competing pathways and feedback inhibition. Finally, by introducing Rhodiola-derived glycosyltransferase UGT73B6 into the above-mentioned recombinant strain, salidroside (1) was produced with a titer of 56.9 mg/L. Interestingly, the Rhodiola-derived glycosyltransferase, UGT73B6, also catalyzed the attachment of glucose to the phenol position of tyrosol (3) to form icariside D2 (4), which was not reported in any previous literatures.

  18. Engineering Escherichia coli for renewable benzyl alcohol production

    Directory of Open Access Journals (Sweden)

    Shawn Pugh

    2015-12-01

    Full Text Available Benzyl alcohol is an aromatic hydrocarbon used as a solvent and an intermediate chemical in the pharmaceutical, cosmetics, and flavor/fragrance industries. The de novo biosynthesis of benzyl alcohol directly from renewable glucose was herein explored using a non-natural pathway engineered in Escherichia coli. Benzaldehyde was first produced from endogenous phenylpyruvate via three heterologous steps, including hydroxymandelate synthase (encoded by hmaS from Amycolatopsis orientalis, followed by (S-mandelate dehydrogenase (encoded by mdlB and phenylglyoxylate decarboxylase (encoded by mdlC from Pseudomonas putida ATCC 12633. The subsequent rapid and efficient reduction of benzaldehyde to benzyl alcohol occurred by the combined activity and native regulation of multiple endogenous alcohol dehydrogenases and/or aldo-keto reductases. Through systematic deletion of competing aromatic amino acid biosynthesis pathways to promote endogenous phenylpyruvate availability, final benzyl alcohol titers as high as 114±1 mg/L were realized, representing a yield of 7.6±0.1 mg/g on glucose and a ~5-fold improvement over initial strains.

  19. Enteroaggregative Escherichia coli: An Emerging Enteric Food Borne Pathogen

    Directory of Open Access Journals (Sweden)

    P. Kaur

    2010-01-01

    Full Text Available Enteroaggregative Escherichia coli (EAEC are quite heterogeneous category of an emerging enteric pathogen associated with cases of acute or persistent diarrhea worldwide in children and adults, and over the past decade has received increasing attention as a cause of watery diarrhea, which is often persistent. EAEC infection is an important cause of diarrhea in outbreak and non-outbreak settings in developing and developed countries. Recently, EAEC has been implicated in the development of irritable bowel syndrome, but this remains to be confirmed. EAEC is defined as a diarrheal pathogen based on its characteristic aggregative adherence (AA to HEp-2 cells in culture and its biofilm formation on the intestinal mucosa with a “stacked-brick” adherence phenotype, which is related to the presence of a 60 MDa plasmid (pAA. At the molecular level, strains demonstrating the aggregative phenotype are quite heterogeneous; several virulence factors are detected by polymerase chain reaction; however, none exhibited 100% specificity. Although several studies have identified specific virulence factor(s unique to EAEC, the mechanism by which EAEC exerts its pathogenesis is, thus, far unknown. The present review updates the current knowledge on the epidemiology, chronic complications, detection, virulence factors, and treatment of EAEC, an emerging enteric food borne pathogen.

  20. Biosynthesis of novel thermoplastic polythioesters by engineered Escherichia coli

    Science.gov (United States)

    Lütke-Eversloh, Tina; Fischer, Andreas; Remminghorst, Uwe; Kawada, Jumpei; Marchessault, Robert H.; Bögershausen, Ansgar; Kalwei, Martin; Eckert, Hellmut; Reichelt, Rudolf; Liu, Shuang-Jiang; Steinbüchel, Alexander

    2002-12-01

    The development of non-petrochemical sources for the plastics industry continues to progress as large multinationals focus on renewable resources to replace fossil carbon. Many bacteria are known to accumulate polyoxoesters as water-insoluble granules in the cytoplasm. The thermoplastic and/or elastomeric behaviour of these biodegradable polymers holds promise for the development of various technological applications. Here, we report the synthesis and characterization of microbial polythioesters (PTEs), a novel class of biopolymers of general technological relevance. Biosynthesis of PTE homopolymers was achieved using a recombinant strain of Escherichia coli that expressed a non-natural pathway consisting of a butyrate kinase, a phosphotransbutyrylase, and a PHA synthase. Different homopolymers were produced, consisting of either 3-mercaptopropionate, 3-mercaptobutyrate, or 3-mercaptovalerate repeating units, if the respective mercaptoalkanoic acids were provided as precursor substrates to the fermentative process. The PTEs contributed up to 30% (w/w) of the cellular dry weight and were identified as hydrophobic inclusions in the cytoplasm. The chemical and stereochemical homogeneity of the purified PTEs were identified by different methods, and the estimated physical properties were compared to the oxypolyester equivalents, revealing low crystalline order and, for the poly(3-mercaptopropionate) improved thermal stability. The ability to produce PTEs through a biosynthetic route opens up new avenues in the field of biomaterials.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Urinary tract infections (UTIs) are primarily caused by Escherichia coli with the patient's own faecal flora acting as a reservoir for the infecting E. coli. Here we sought to characterize the E. coli faecal flora of UTI patients and healthy controls who had never had a UTI. Up to 20 E. coli...

  2. Draft Genome Sequences of Five Novel Polyketide Synthetase-Containing Mouse Escherichia coli Strains

    Science.gov (United States)

    Mannion, Anthony; Shen, Zeli; Feng, Yan; Garcia, Alexis

    2016-01-01

    We report herein the draft genomes of five novel Escherichia coli strains isolated from surveillance and experimental mice housed at MIT and the Whitehead Institute and describe their genomic characteristics in context with the polyketide synthetase (PKS)-containing pathogenic E. coli strains NC101, IHE3034, and A192PP.

  3. Antigen-43-mediated autoaggregation of Escherichia coli is blocked by fimbriation

    DEFF Research Database (Denmark)

    Hasman, Henrik; Chakraborty, Trinad; Klemm, Per

    1999-01-01

    Antigen 43 (Ag43), the product of the flu gene, is a surface-displayed autotransporter protein of Escherichia coli. Ag43 is responsible for the autoaggregation and flocculation of static liquid cultures of many E. coli strains. The expression of Ag43 has been reported to be phase variable...

  4. Proteomic analysis reveals protein expression differences in Escherichia coli strains associated with persistent versus transient mastitis

    Science.gov (United States)

    Escherichia coli is a leading cause of bacterial mastitis in dairy cattle. Typically this infection is transient in nature, causing an infection that lasts 2-3 days. However, in a minority of cases, E. coli has been shown to cause a persistent intramammary infection. The mechanisms that allow for...

  5. TiO2 Photocatalysis Damages Lipids and Proteins in Escherichia coli

    NARCIS (Netherlands)

    Carre, Gaelle; Hamon, Erwann; Ennahar, Said; Estner, Maxime; Lett, Marie-Claire; Horvatovich, Peter; Gies, Jean-Pierre; Keller, Valerie; Keller, Nicolas; Andre, Philippe

    2014-01-01

    This study investigates the mechanisms of UV-A (315 to 400 nm) photocatalysis with titanium dioxide (TiO2) applied to the degradation of Escherichia coli and their effects on two key cellular components: lipids and proteins. The impact of TiO2 photocatalysis on E. coli survival was monitored by coun

  6. Molecular cloning of the Salmonella typhimurium lep gene in Escherichia coli

    NARCIS (Netherlands)

    van Dijl, J M; van den Bergh, R; Reversma, T; Smith, H; Bron, S; Venema, G

    1990-01-01

    A system is described which enabled the selection of a heterologous lep gene, encoding signal peptidase I, in Escherichia coli. It is based on complementation of an E. coli mutant, in which the synthesis of signal peptidase I can be regulated. With this system the lep gene of Salmonella typhimurium

  7. Antimicrobial resistance in commensal Escherichia coli in veal calves is associated with antimicrobial drug use

    NARCIS (Netherlands)

    Bosman, A.B.; Wagenaar, J.A.; Stegeman, J.A.; Vernooij, J.C.M.; Mevius, D.J.

    2014-01-01

    The aim of this study was to determine the association between farm management factors, including antimicrobial drug usage, and resistance in commensal Escherichia coli isolates from the faeces of white veal calves. Ninety E. coli isolates from one pooled sample per farm (n = 48) were tested for the

  8. DETECTION OF ESCHERICHIA COLI IN WATER USING A COLORIMETRIC GENE PROBE ASSAY

    Science.gov (United States)

    A commercially available DNA hydribization assay (Gene-trak , Framingham, MA. USA) was compared with the EC-MUG procedure for the detection of Escherichia coli in water. The gene probe gave positive responses for pure cultures of E. coli 0157:H7, E. fergusonii, Shigella sonnei, S...

  9. Efficacy of supercritical carbon dioxide for nonthermal inactivation of Escherichia coli K12 in apple cider

    Science.gov (United States)

    This study evaluated the efficacy of a supercritical carbon dioxide (SCCO2) system with a gas-liquid porous metal contactor for eliminating Escherichia coli K12 in apple cider. Pasteurized, preservative-free apple cider was inoculated with E. coli K12 and processed using the SCCO2 system at CO2 conc...

  10. Mechanisms of Reduced Susceptibility to Ciprofloxacin in Escherichia coli Isolates from Canadian Hospitals

    Directory of Open Access Journals (Sweden)

    Patricia J Baudry-Simner

    2012-01-01

    Full Text Available OBJECTIVE: To determine whether plasmid-mediated quinolone resistance (PMQR determinants play a role in the increasing resistance to fluoroquinolones among Escherichia coli isolates in Canadian hospitals, and to determine the mechanisms of reduced susceptibility to ciprofloxacin in a recent collection of 190 clinical E coli isolates.

  11. Identieke resistentiegenen en plasmiden in Escherichia coli van Nederlandse patiënten, pluimvee en kippenvlees

    NARCIS (Netherlands)

    Leverstein-van Hall, M.A.; Dierikx, C.M.; Cohen Stuart, J.; Voets, G.M.; Munckhof, Van den T.P.; Platteel, T.N.; Fluit, A.C.; Sande-Bruinsma, Van de N.; Bonten, M.J.M.; Mevius, D.J.

    2011-01-01

    Doel Bepalen welke ‘extended’-spectrum-bètalactamase(ESBL)-genen en plasmiden aanwezig zijn in Escherichia coli in vleeskuikens en vers kippenvlees uit Nederland en tevens in een voor Nederland representatieve collectie van klinische E. coli isolaten van patiënten. Opzet Beschrijvend. Methoden ESBL-

  12. Principles of some novel rapid dipstick methods for detection and characterization of verotoxigenic Escherichia coli

    NARCIS (Netherlands)

    Aldus, C.F.; Amerongen, van A.; Ariens, R.M.C.; Peck, M.W.; Wichers, J.H.; Wyatt, G.M.

    2003-01-01

    Aims: The verotoxigenic Escherichia coli (VTEC) serotype most commonly associated with verotoxin (VT) production is O157:H7, but other serotypes have also been implicated in food-borne illness. These serotypes exhibit much greater genetic and biochemical diversity than E. coli O157:H7, making screen

  13. Shuttle vectors for cloning recombinant DNA in Escherichia coli and Streptomyces griseofuscus C581.

    OpenAIRE

    Larson, J L; Hershberger, C L

    1984-01-01

    The replicon of the Streptomyces plasmid SCP2 was located on a 5.9-kilobase EcoRI-SalI restriction fragment. The SCP2 replicon was combined with Escherichia coli plasmid pBR322 and genes specifying neomycin resistance and thiostrepton resistance in streptomycetes to construct shuttle vectors that are useful for cloning in E. coli and streptomycetes.

  14. Prevalence and molecular characterization of clinical isolates of Escherichia coli expressing an AmpC phenotype

    DEFF Research Database (Denmark)

    Jørgensen, Rikke Lind; Nielsen, Jesper Boye; Friis-Møller, Alice

    2010-01-01

    OBJECTIVES: To establish the prevalence of the AmpC beta-lactamase phenotype in clinical isolates of Escherichia coli and characterize the genetic resistance mechanisms causing the observed phenotype. METHODS: Clinical E. coli (n = 74) with reduced susceptibility to third-generation cephalosporin...

  15. Characteristics of Escherichia coli causing persistence or relapse of urinary tract infections

    DEFF Research Database (Denmark)

    Ejrnæs, Karen; Stegger, Marc; Reisner, Andreas

    2011-01-01

    Recurrent urinary tract infections (RUTIs) pose a major problem but little is known about characteristics of Escherichia coli associated with RUTI. This study includes E. coli from 155 women with community-acquired lower urinary tract infections (UTIs) randomized to one of three dosing regiments...

  16. Establishing streptomycin epidemiological cut-off values for Salmonella and Escherichia coli. Microbial Drug Resistance

    NARCIS (Netherlands)

    Garcia-Migura, L.; Sunde, M.; Karlsmose, S.; Veldman, K.T.; Schroeter, A.; Guerra, B.; Granier, S.A.; Perrin-Guyomard, A.; Gicquel-Bruneau, M.; Franco, A.; Englund, S.; Teale, C.; Heiska, H.; Clemente, L.; Boerlin, P.; Moreno, M.A.; Daignault, D.; Mevius, D.J.; Hendriksen, R.S.; Aarestrup, F.M.

    2012-01-01

    This study was conducted to elucidate the accuracy of the current streptomycin epidemiological cut-off value (ECOFF) for Escherichia coli and Salmonella spp. A total of 236 Salmonella enterica and 208 E. coli isolates exhibiting MICs between 4 and 32¿mg/L were selected from 12 countries. Isolates we

  17. Non-functional expression of Escherichia coli signal peptidase I in Bacillus subtilis

    NARCIS (Netherlands)

    van Dijl, J M; de Jong, A; Smith, H; Bron, S; Venema, G

    1991-01-01

    The Escherichia coli lep gene, encoding signal peptidase I (SPase I) was provided with Bacillus subtilis transcription/translation signals and expressed in this organism. When present on a low-copy-number plasmid, the amount of E. coli SPase I produced (per mg cell protein) in B. subtilis was half t

  18. Proliferation of Escherichia coli O157:H7 in soil and hydroponic microgreen production systems

    Science.gov (United States)

    Radish (Raphanus sativus var. longipinnatus) microgreens were produced from seeds inoculated with Escherichia coli O157: H7 using soil substitute and hydroponic production systems. E. coli populations on the edible and inedible parts of harvested microgreen plants and in growth medium were examined....

  19. Evaluation of Eight Different Cephalosporins for Detection of Cephalosporin Resistance in Salmonella enterica and Escherichia coli

    NARCIS (Netherlands)

    Aarestrup, F.M.; Hasman, H.; Veldman, K.T.; Mevius, D.J.

    2010-01-01

    This study evaluates the efficacy of eight different cephalosporins for detection of cephalosporin resistance mediated by extended spectrum beta-lactamases (ESBL) and plasmidic AmpC beta-lactamases in Salmonella and Escherichia coli. A total of 138 E. coli and 86 Salmonella isolates with known beta-

  20. Evaluation of Select Sensors for Real-Time Monitoring of Escherichia coli in Water Distribution Systems▿

    OpenAIRE

    Miles, Syreeta L.; Sinclair, Ryan G.; Riley, Mark R; Pepper, Ian L

    2011-01-01

    This study evaluated real-time sensing of Escherichia coli as a microbial contaminant in water distribution systems. Most sensors responded to increased E. coli concentrations, showing that select sensors can detect microbial water quality changes and be utilized as part of a contaminant warning system.

  1. Survival of Escherichia coli in the environment : fundamental and public health aspects

    NARCIS (Netherlands)

    van Elsas, Jan Dirk; Semenov, Alexander V.; Costa, Rodrigo; Trevors, Jack T.

    2011-01-01

    In this review, our current understanding of the species Escherichia coli and its persistence in the open environment is examined. E. coli consists of six different subgroups, which are separable by genomic analyses. Strains within each subgroup occupy various ecological niches, and can be broadly c

  2. Characteristics of Cefotaxime-Resistant Escherichia coli from Wild Birds in The Netherlands

    NARCIS (Netherlands)

    Veldman, K.T.; Tulden, P.; Kant, A.; Testerink, J.J.; Mevius, D.J.

    2013-01-01

    Cloacal swabs from carcasses of Dutch wild birds obtained in 2010 and 2011 were selectively cultured on media with cefotaxime to screen for the presence of extended-spectrum beta-lactamase (ESBL)/AmpC-producing Escherichia coli. Subsequently, all cefotaxime-resistant E. coli isolates were tested by

  3. NONFUNCTIONAL EXPRESSION OF ESCHERICHIA-COLI SIGNAL PEPTIDASE-I IN BACILLUS-SUBTILIS

    NARCIS (Netherlands)

    VANDIJL, JM; DEJONG, A; SMITH, H; BRON, S; VENEMA, G; van Dijl, Jan Maarten

    1991-01-01

    The Escherichia coli lep gene, encoding signal peptidase I (SPase I) was provided with Bacillus subtilis transcription/translation signals and expressed in this organism. When present on a low-copy-number plasmid, the amount of E. coli SPase I produced (per mg cell protein) in B. subtilis was half t

  4. Identification of uropathogenic Escherichia coli clonal group A (CgA in hospitalised patients

    Directory of Open Access Journals (Sweden)

    Rubens CS Dias

    2009-08-01

    Full Text Available This study provides the first description of healthcare-associated infections with Escherichia coli clonal group A (CgA isolates in Latin America. Isolates were typed by enterobacterial repetitive intergenic consensus-PCR, pulsed-field gel electrophoresis, E. coli phylogenetic grouping, multilocus sequence typing and fimH single nucleotide polymorphism analysis. Out of 42 E. coli hospital isolates studied, three belonged to E. coli phylogenetic group D and ST69 and had fimH sequences identical to that of the CgA reference strain ATCC BAA-457. E. coli CgA is another potential source of resistant infections in hospitals.

  5. Replication of Vibrio cholerae chromosome I in Escherichia coli: dependence on dam methylation

    DEFF Research Database (Denmark)

    Koch, Birgit; Ma, Xiaofang; Løbner-Olesen, Anders

    2010-01-01

    We successfully substituted Escherichia coli's origin of replication oriC with the origin region of Vibrio cholerae chromosome I (oriCIVc). Replication from oriCIVc initiated at a similar or slightly reduced cell mass compared to that of normal E. coli oriC. With respect to sequestration....... cholerae chromosome I replication, which similar to what is observed for E. coli. No hda homologue has been identified in V. cholerae yet. In V. cholerae, dam is essential for viability, whereas in E. coli, dam mutants are viable. Replacement of E. coli oriC with oriCIVc allowed us to specifically address...

  6. Dissociation of outer membrane for Escherichia coli cell caused by cerium nitrate

    Institute of Scientific and Technical Information of China (English)

    陈爱美; 施庆珊; 冯劲; 欧阳友生; 陈仪本; 谭绍早

    2010-01-01

    The biological effect of cerium nitrate on the outer membrane(OM) of Escherichia coli(E.coli) cell was studied,and the antim-icrobial mechanism of rare earth elements was explored.The antimicrobial effect of cerium nitrate on E.coli cell was valued by plate count method,and the morphology change of E.coli cell was observed with scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results showed that the E.coli cell suspension was flocculated when the concentration of Ce(NO3)3?6H2O...

  7. Advances in genoserotyping and subtyping of Escherichia coli

    Science.gov (United States)

    E. coli plays an important role as a member of the gut microbiota; however, pathogenic strains also exist, including various diarrheagenic E. coli pathotypes and extraintestinal pathogenic E. coli that cause illness outside of the GI-tract. E. coli have traditionally been serotyped using antisera a...

  8. Expression of Clostridium acetobutylicum ATCC 824 Genes in Escherichia coli for Acetone Production and Acetate Detoxification

    OpenAIRE

    Bermejo, Lourdes L.; Welker, Neil E.; Papoutsakis, Eleftherios T.

    1998-01-01

    A synthetic acetone operon (ace4) composed of four Clostridium acetobutylicum ATCC 824 genes (adc, ctfAB, and thl, coding for the acetoacetate decarboxylase, coenzyme A transferase, and thiolase, respectively) under the control of the thl promoter was constructed and was introduced into Escherichia coli on vector pACT. Acetone production demonstrated that ace4 is expressed in E. coli and resulted in the reduction of acetic acid levels in the fermentation broth. Since different E. coli strains...

  9. Spread of avian pathogenic Escherichia coli ST117 O78:H4 in Nordic broiler production

    DEFF Research Database (Denmark)

    Ronco, Troels; Stegger, Marc; Olsen, Rikke Heidemann;

    2017-01-01

    Escherichia coli infections known as colibacillosis constitute a considerable challenge to poultry farmers worldwide, in terms of decreased animal welfare and production economy. Colibacillosis is caused by avian pathogenic E. coli (APEC). APEC strains are extraintestinal pathogenic E. coli...... nucleotide polymorphisms. In general, the characterized poultry isolates constituted a genetically diverse population. However, the phylogenetic analyses revealed a major clade of 47 closely related ST117 O78:H4 isolates. The isolates in this clade were collected from broiler chickens and breeders...

  10. Prevalence and risk factor analysis of resistant Escherichia coli urinary tract infections in the emergency department.

    OpenAIRE

    Bailey AM; Weant KA; Baker SN

    2013-01-01

    Background: Escherichia coli (E. coli) is a frequent uropathogen in urinary tract infections (UTI). Widespread resistance to sulfamethoxazole-trimethoprim (SMX-TMP) and increasing resistance to fluoroquinolones amongst these isolates has been recognized. There are limited data demonstrating risk factors for resistance to both SMX-TMP and fluoroquinolones.Objectives: This study was conducted to assess for the prevalence of community resistance amongst E. coli isolates to SMX-TMP and levofloxac...

  11. Is Shiga Toxin-Negative Escherichia coli O157 : H7 Enteropathogenic or Enterohemorrhagic Escherichia coli? Comprehensive Molecular Analysis Using Whole-Genome Sequencing

    NARCIS (Netherlands)

    Ferdous, Mithila; Zhou, Kai; Mellmann, Alexander; Morabito, Stefano; Croughs, Peter D.; de Boer, Richard F.; Kooistra-Smid, Anna M. D.; Rossen, John W. A.; Friedrich, Alexander W.

    2015-01-01

    The ability of Escherichia coli O157:H7 to induce cellular damage leading to disease in humans is related to numerous virulence factors, most notably the stx gene, encoding Shiga toxin (Stx) and carried by a bacteriophage. Loss of the Stx-encoding bacteriophage may occur during infection or culturin

  12. Antimicrobial activity of aqueous extract of hypericum perforatum against clinical isolates of Escherichia coli( ESBLs.

    Directory of Open Access Journals (Sweden)

    Saman Shalibeik

    2016-09-01

    Full Text Available Objectives: The aim of study was to investigate the effect of aqueous hypericum perforatum extract on the morphological properties of Escherichia coli bacteria ESBLs (extended-spectrum beta-lactamases. Methods: 40 strains of Escherichia coli bacteria ESBLS from clinical purified samples were taken from Arak medical university microbial research center infectious diseases and E. coli ATCC25922. Antibiogram and Biochemical tests were taken in order to verify Escherichia coli bacteria. The hypericum perforatum plant is prepared freshly from farm herb. Before drying plant in a traditional way, it should be washed with water for several times, hypericum perforatum aqueous extracts were excavated by means of reflux device with distillation and investigating the antibacterial effects of hypericum by disk diffusion method, minimal inhibitory concentration (MIC and minimal bactericidal concentration (MBC. its morphological investigation, taken by the use of electronic microscope and light microscope. Results: Obtained result showed that hypericum perforatum extract to Escherichia coli bacteria ESBLS in the concentrations of 8, 4 and 2 mg/ml, 57.5 percentages of bacteria out of %100 have halo and 42.5 percentages of bacteria out of %100 are non-halo. In these concentrations 1, .5, .25, .125, .0625, .0312, .0156 mg/ml, the percentage of sensitive bacteria (having halo is decreased and the percentage of resistant bacteria ( non-halo increased. Minimum Inhibitory Concentration (MIC against Escherichia coli Bacteria taken in different concentrations, which concentration 0.0078mg/ml was lowest among them.

  13. Investigating the Antibacterial Effects of Plant Extracts on Pseudomonas aeruginosa and Escherichia coli

    Directory of Open Access Journals (Sweden)

    Jahani

    2016-04-01

    Full Text Available Background Scientists are seeking an appropriate alternative method for curing infections caused by resistant bacteria, since drug resistance is continually increasing. Objectives This research aims to discover the function of some medicine plants on pestiferous Pseudomonas aeruginosa and Escherichia coli in humans. Materials and Methods Bacterial strains were obtained from a standard laboratory. The strains of Pseudomonas aeruginosa ATCC27853 and E.coli ATCC25922 bacteria were used for antimicrobial testing of the extractions. Results Our results showed that Teucrium polium extracts have the minimum density of inhibitory for Escherichia coli, 25 ppm, whereas the maximum of this is for Peganum harmala and Prangos ferulaceae with 100 ppm. The lowest minimum concentration inhibitory value of extracts P. harmala, T. polium, T. pratensis and Rumex was found in 25 ppm against P.aeruginosa. Conclusions The results of our study showed that plant extracts have good antibacterial properties against Pseudomonas aeruginosa and Escherichia coli.

  14. Antibiotic Resistance Patterns in Enteric and Uropathogenic Strains of Escherichia Coli in Children

    Directory of Open Access Journals (Sweden)

    This paper should be cited as: Sedighi I, Alikhani MY, Nakhaee S, Karami P . [ Antibiotic Resistance Patterns in Enteric and Uropathogenic Strains of Escherichia Coli in Children ]. mlj goums . 201 4 ; 8 ( Suppl 4 : 42 - 48 [Article in Per sian] Sedi ghi, I. (MD

    2014-11-01

    Full Text Available Background and Objective: Escherichia coli is the most common cause of urinary tract infections in children and the leading cause of intra-abdominal infections (peritonitis and abscess followed intestinal injuries. Urinary tract infection, including cystitis and pyelonephritis, is a common childhood infection. E. coli causes more than 90 percent of the community acquired and 50% of hospital acquired urinary tract infections; therefore, the determination of E. coli antibiotic susceptibility is a paramount importance to clinical and epidemiological purposes. Material and Methods: In this cross-sectional study, 50 E. coli strains isolated from urine samples of children less than 7 years of age with urinary tract infections. They were compared for drug susceptibility testing by disc diffusion method with 50 strains of Escherichia coli isolated from stool samples of healthy children with the same age and sex pattern. Results: The actual amount of drug sensitivity of uropathogenic and intestinal Escherichia coli strains to amikacin was 94 and 100%, nitrofurantoin 90 and 88%, gentamicin 66 and 94%, cefixime 56 and 60%, nalidixic acid 38 and 44% and to cotrimoxazole 28 and 32%, respectively. Conclusion: the rate of resistance to gentamicin, Cefixime and nalidixic acid in urinary tract infection isolates were more than intestinal strains. The highest rate of drug resistance in urinary Escherichia coli isolates was associated with cotrimoxazole and the lowest one with amikacin.

  15. Selenite Protection of Tellurite Toxicity towards Escherichia coli

    Directory of Open Access Journals (Sweden)

    Helen A. Vrionis

    2015-12-01

    Full Text Available In this work the influence of selenite on metal resistance in Escherichia coli was examined. Both synergistic and antagonistic resistance and toxicities were found upon co exposure with selenite. In wild type cells co-exposure to selenite had little effect on arsenic resistance, decreased resistance to cadmium and mercury but led to a dramatic increased resistance to tellurite of 32 fold. Due to the potential importance of thiol chemistry in metal biochemistry, deletion strains in γ-glutamylcysteine synthetase (key step in glutathione biosynthesis, encoded by gshA, thioredoxin (trxA, glutaredoxin (grxA, glutathione oxidoreductase (gor, and the periplasmic glutathione transporter (cydD were also evaluated for resistance to various metals in the presence of selenite. The protective effect of selenite on tellurite toxicity was seen in several of the mutants and was pronounced in the gshA mutant were resistance to tellurite was increased up to 1000 fold relative to growth in the absence of selenite. Thiol oxidation studies revealed a faster rate of loss of reduced thiol content in the cell with selenite than with tellurite, indicating differential thiol reactivity. Selenite addition resulted in reactive oxygen species (ROS production equivalent to levels associated with H2O2 addition. Tellurite addition resulted in considerably lower ROS generation while vanadate and chromate treatment did not increase ROS production above that of background. This work shows increased resistance towards most oxyanions in mutants of thiol redox suggesting that metalloid reaction with thiol components such as glutathione actually enhances toxicity of some metalloids.

  16. In vitro evolution of an archetypal enteropathogenic Escherichia coli strain.

    Science.gov (United States)

    Nisa, Shahista; Hazen, Tracy H; Assatourian, Lillian; Nougayrède, Jean-Philippe; Rasko, David A; Donnenberg, Michael S

    2013-10-01

    Enteropathogenic Escherichia coli (EPEC) is a leading cause of infantile diarrhea in developing countries. EPEC strain E2348/69 is used worldwide as a prototype to study EPEC genetics and disease. However, isolates of E2348/69 differ phenotypically, reflecting a history of in vitro selection. To identify the genomic and phenotypic changes in the prototype strain, we sequenced the genome of the nalidixic acid-resistant (Nal(r)) E2348/69 clone. We also sequenced a recent nleF mutant derived by one-step PCR mutagenesis from the Nal(r) strain. The sequencing results revealed no unintended changes between the mutant and the parent strain. However, loss of the pE2348-2 plasmid and 3 nonsynonymous mutations were found in comparison to the published streptomycin-resistant (Str(r)) E2348/69 reference genome. One mutation is a conservative amino acid substitution in ftsK. Another, in gyrA, is a mutation known to result in resistance to nalidixic acid. The third mutation converts a stop codon to a tryptophan, predicted to result in the fusion of hflD, the lysogenization regulator, to purB. The purB gene encodes an adenylosuccinate lyase involved in purine biosynthesis. The Nal(r) clone has a lower growth rate than the Str(r) isolate when cultured in minimal media, a difference which is corrected upon addition of adenine or by genetic complementation with purB. Addition of adenine or genetic complementation also restored the invasion efficiency of the Nal(r) clone. This report reconciles longstanding inconsistencies in phenotypic properties of an archetypal strain and provides both reassurance and cautions regarding intentional and unintentional evolution in vitro.

  17. Mechanism of catabolite repression of tryptophanase synthesis in Escherichia coli.

    Science.gov (United States)

    Isaacs, H; Chao, D; Yanofsky, C; Saier, M H

    1994-08-01

    Repression of tryptophanase (tryptophan indole-lyase) by glucose and its non-metabolizable analogue methyl alpha-glucoside has been studied employing a series of isogenic strains of Escherichia coli lacking cyclic AMP phosphodiesterase and altered for two of the proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), Enzyme I and Enzyme IIAGlc. Basal activity of tryptophanase was depressed mildly by inclusion of glucose in the growth medium, but inducible tryptophanase synthesis was subject to strong glucose repression in the parental strain, which exhibited normal PTS enzyme activities. Methyl alpha-glucoside was without effect in this strain. Loss of Enzyme I decreased sensitivity to repression by glucose but enhanced sensitivity to repression by methyl alpha-glucoside. Loss of Enzyme IIAGlc activity largely abolished repression by methyl alpha-glucoside but had a less severe effect on glucose repression. The repressive effects of both sugars were fully reversed by inclusion of cyclic AMP in the growth medium. Tryptophan uptake under the same conditions was inhibited weakly by glucose and more strongly by methyl alpha-glucoside in the parental strain. Inhibition by both sugars was alleviated by partial loss of Enzyme I. Inhibition by methyl alpha-glucoside appeared to be largely due to energy competition and was not responsible for repression of tryptophanase synthesis. Measurement of net production of cyclic AMP as well as intracellular concentrations of cyclic AMP revealed a good correlation with intensity of repression. The results suggest that while basal tryptophanase synthesis is relatively insensitive to catabolite repression, inducible synthesis is subject to strong repression by two distinct mechanisms, one dependent on enzyme IIAGlc of the PTS and the other independent of this protein. Both mechanisms are attributable to depressed rates of cyclic AMP synthesis. No evidence for a cyclic-AMP-independent mechanism of catabolite

  18. Experimental evolution of silver nanoparticle resistance in Escherichia coli

    Science.gov (United States)

    Tajkarimi, Mehrdad

    The recent exponential increase in the use of engineered nanoparticles (eNPs) means both greater intentional and unintentional exposure of eNPs to microbes. Intentional use includes the use of eNPs as biocides; unintentional exposure results from the fact that eNPs are included in a variety of commercial products (paints, sunscreens, cosmetics.) Many of these eNPs include heavy metals or metal oxides such as titanium dioxide, silver, gold, zinc and zinc oxide. The fact that early studies of the impact of metallic nanoparticles achieved approximately 90% lethality to Ag, Cu eNPs, suggests that genetic variants are already circulating in bacteria that can be co-opted to provide heavy metal eNP resistance. This project has utilized laboratory experimental evolution to evolve eNP resistance in the bacterium Escherichia coli (K12 MG1655 strain.). This is currently being validated by demonstrating the greater fitness of evolved strains versus ancestral strains in the presence of different sized and coated silver nanoparticles (10nm, 40nm, citrate-coated, PVP-coated) as well as phenotypic changes in the bacterial cell wall (as measured by Atomic Force Microscopy, AFM.). Finally, the bacterial genomes of the evolved and ancestral strains were resequenced. The genomic basis of this complex phenotype was determined. The practical application of such knowledge cannot be underestimated since nature is already evolving nanoparticle resistant bacteria. Thus knowledge of the nature of the physiological, morphological, and genomic mechanisms of resistance will be essential to deploy sustainable use of NPs as biocides, and to prevent unintentional environmental damage.

  19. Lanthanide accumulation in the periplasmic space of Escherichia coli B.

    Science.gov (United States)

    Bayer, M E; Bayer, M H

    1991-01-01

    Treatment of growing Escherichia coli B with lanthanide ions [lanthanum(III), terbium(III), and europium(III)] and subsequent aldehyde-OsO4 fixation caused areas of high contrast to appear within the periplasm (the space between inner and outer membrane of the cell envelope). X-ray microanalysis of ultrathin sections of Epon-embedded or acrylic resin-embedded cells revealed the presence of the lanthanide and of phosphorus in the areas, whose contrast greatly exceeded that of other stained structures. Comparatively small amounts of the lanthanide were also present in the outer membrane and in the cytoplasm. The distribution of the periplasmic areas of high contrast was found to be random and not clustered at areas of current or future septum formation. Irregular cell shapes were observed after lanthanide treatment before onset of fixation. In contrast to glutaraldehyde-OsO4 fixation, glutaraldehyde used as the sole fixer caused a scattered distribution of the lanthanide. Cryofixation (slam-freezing) and freeze substitution revealed a lanthanum stain at both the periplasm and the outer part of the outer membrane. Deenergization of the cell membrane by either phage T4 or carbonyl cyanide m-chlorophenylhydrazone abolished the metal accumulation. Furthermore, addition of excess calcium, administered together with the lanthanide solution, diminished the quantity and size of areas of high contrast. Cells grown in media of high NaCl concentration revealed strongly stained areas of periplasmic precipitates, whereas cells grown under low-salt conditions showed very few high-contrast patches in the periplasm. Terbium treatment (during fixation) enhanced the visibility of the sites of inner-outer membrane contact (the membrane adhesion sites) in plasmolized cells, possibly as the result of an accumulation of the metal at the adhesion domains. The data suggest a rapid interaction of the lanthanides with components of the cell envelope, the periplasm, and the energized inner

  20. The stringent response and cell cycle arrest in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Daniel J Ferullo

    2008-12-01

    Full Text Available The bacterial stringent response, triggered by nutritional deprivation, causes an accumulation of the signaling nucleotides pppGpp and ppGpp. We characterize the replication arrest that occurs during the stringent response in Escherichia coli. Wild type cells undergo a RelA-dependent arrest after treatment with serine hydroxamate to contain an integer number of chromosomes and a replication origin-to-terminus ratio of 1. The growth rate prior to starvation determines the number of chromosomes upon arrest. Nucleoids of these cells are decondensed; in the absence of the ability to synthesize ppGpp, nucleoids become highly condensed, similar to that seen after treatment with the translational inhibitor chloramphenicol. After induction of the stringent response, while regions corresponding to the origins of replication segregate, the termini remain colocalized in wild-type cells. In contrast, cells arrested by rifampicin and cephalexin do not show colocalized termini, suggesting that the stringent response arrests chromosome segregation at a specific point. Release from starvation causes rapid nucleoid reorganization, chromosome segregation, and resumption of replication. Arrest of replication and inhibition of colony formation by ppGpp accumulation is relieved in seqA and dam mutants, although other aspects of the stringent response appear to be intact. We propose that DNA methylation and SeqA binding to non-origin loci is necessary to enforce a full stringent arrest, affecting both initiation of replication and chromosome segregation. This is the first indication that bacterial chromosome segregation, whose mechanism is not understood, is a step that may be regulated in response to environmental conditions.

  1. Characterization of the cyn operon in Escherichia coli K12.

    Science.gov (United States)

    Sung, Y C; Fuchs, J A

    1988-10-15

    Escherichia coli can overcome the toxicity of environmental cyanate by hydrolysis of cyanate to ammonia and bicarbonate. This reaction is catalyzed by the enzyme cyanase, encoded by the cynS gene. The nucleotide sequence of cynS has been reported (Sung, Y.-c., Anderson, P. M., and Fuchs, J. A. (1987) J. Bacteriol. 169, 5224-5230). The nucleotide sequence of the complete cyn operon has now been determined. The cyn operon is approximately 2600 base pairs and includes cynT, cynS, and cynX, which encode cyanate permease, cyanase, and a protein of unknown function, respectively. Two cyanate-inducible transcripts of 1500 and 2500 nucleotides, respectively, were detected by Northern blot analysis. S1 nuclease mapping experiments indicated that two different cyn mRNAs have a common 5'-end and two different 3'-ends. One 3'-end was located within the coding region of cynX, whereas the other 3'-end includes the entire DNA sequence of cynX. The longer transcript contained 98 nucleotides complementary to lac mRNA produced by the predominant lac transcription termination sequence. Termination vectors were used to show that both 3'-ends were generated by sequences that caused transcriptional termination in vivo. Expression vectors were used to demonstrate that a protein corresponding to the expected size was synthesized from the DNA fragment containing the open reading frame designated cynX. The predicted amino acid sequence of cynX indicates that it is a very hydrophobic protein. The level of cynX expression was significantly less than that of cynT or cynS expression.

  2. 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.

  3. Tetrahydrobiopterin corrects Escherichia coli endotoxin-induced endothelial dysfunction.

    Science.gov (United States)

    Mittermayer, Friedrich; Pleiner, Johannes; Schaller, Georg; Zorn, Stefan; Namiranian, Khodadad; Kapiotis, Stylianos; Bartel, Gregor; Wolfrum, Mathias; Brügel, Mathias; Thiery, Joachim; Macallister, Raymond J; Wolzt, Michael

    2005-10-01

    Acute inflammation causes endothelial dysfunction, which is partly mediated by oxidant stress and inactivation of nitric oxide. The contribution of depletion of tetrahydrobiopterin (BH(4)), the cofactor required for nitric oxide generation, is unclear. In this randomized, double-blind, three-way crossover study, forearm blood flow (FBF) responses to ACh and glyceryltrinitrate (GTN) were measured before and 3.5 h after infusion of Escherichia coli endotoxin (LPS, 20 IU/kg iv) in eight healthy men. The effect of intra-arterial BH(4) (500 microg/min), placebo, or vitamin C (24 mg/min) was studied on separate days 3.5 h after LPS infusion. In addition, human umbilical vein endothelial cells were incubated for 24 h with vitamin C and LPS. ACh and GTN caused dose-dependent forearm vasodilation. The FBF response to ACh, which was decreased by 23 +/- 17% (P < 0.05) by LPS infusion, was restored to baseline reactivity by BH(4) and vitamin C. FBF responses to GTN were not affected by BH(4) or vitamin C. LPS increased leukocyte count, high-sensitivity C-reactive protein, IL-6, IL-1beta, IFN-gamma, monocyte chemoattractant protein-1, pulse rate, and body temperature and decreased platelet count and vitamin C concentration. Vitamin C increased forearm plasma concentration of BH(4) by 32% (P < 0.02). Incubation with LPS and vitamin C, but not LPS alone, increased intracellular BH(4) concentration in human umbilical vein endothelial cells. Impaired endothelial function during acute inflammation can be restored by BH(4) or vitamin C. Vitamin C may exert some of its salutary effects by increasing BH(4) concentration.

  4. Timing of Z-ring localization in Escherichia coli

    Science.gov (United States)

    Tsukanov, R.; Reshes, G.; Carmon, G.; Fischer-Friedrich, E.; Gov, N. S.; Fishov, I.; Feingold, M.

    2011-12-01

    Bacterial cell division takes place in three phases: Z-ring formation at midcell, followed by divisome assembly and building of the septum per se. Using time-lapse microscopy of live bacteria and a high-precision cell edge detection method, we have previously found the true time for the onset of septation, τc, and the time between consecutive divisions, τg. Here, we combine the above method with measuring the dynamics of the FtsZ-GFP distribution in individual Escherichia coli cells to determine the Z-ring positioning time, τz. To analyze the FtsZ-GFP distribution along the cell, we used the integral fluorescence profile (IFP), which was obtained by integrating the fluorescence intensity across the cell width. We showed that the IFP may be approximated by an exponential peak and followed the peak evolution throughout the cell cycle, to find a quantitative criterion for the positioning of the Z-ring and hence the value of τz. We defined τz as the transition from oscillatory to stable behavior of the mean IFP position. This criterion was corroborated by comparison of the experimental results to a theoretical model for the FtsZ dynamics, driven by Min oscillations. We found that τz cells that were analyzed. Moreover, our data suggested that τz is independent of τc, τg and the cell length at birth, L0. These results are consistent with the current understanding of the Z-ring positioning and cell septation processes.

  5. Survival and viability of Escherichia coli in a thermally altered reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Gorden, R.W.; Fliermans, C.B.

    1977-01-01

    Escherichia coli survived and grew in a warm, monomictic reservoir receiving thermal effluent from a nuclear production reactor, which suggests that the presence of E. coli in these aquatic systems is not an indication of recent fecal contamination. Known populations of Escherichia coli were placed in sterile diffusion chambers and suspended at various depths throughout the water column. Experiments were conducted during both ambient water conditions (reactor not operating) and thermally altered water conditions (reactor operating). E. coli populations were observed for changes in density by using optical density and direct and indirect counting methods. Data show that E. coli survives and grows for extended periods of time while it is in diffusion chambers in both aerobic and anaerobic portions of the water column.

  6. Urease genes in non-O157 Shiga toxin-producing Escherichia coli : mostly silent but valuable markers for pathogenicity

    NARCIS (Netherlands)

    Friedrich, A W; Lukas, R; Mellmann, A; Köck, R; Zhang, W; Mathys, W; Bielaszewska, M; Karch, H

    2006-01-01

    The distribution of ureC was investigated among 294 Escherichia coli isolates, comprising 72 strains from the E. coli standard reference collection (ECOR), 62 strains from the diarrhoeagenic E. coli (DEC) collection, and 160 clinical isolates of Shiga toxin-producing E. coli (STEC). The ureC gene wa

  7. Interaction of Escherichia coli K1 and K5 with Acanthamoeba castellanii trophozoites and cysts.

    Science.gov (United States)

    Matin, Abdul; Jung, Suk-Yul

    2011-12-01

    The existence of symbiotic relationships between Acanthamoeba and a variety of bacteria is well-documented. However, the ability of Acanthamoeba interacting with host bacterial pathogens has gained particular attention. Here, to understand the interactions of Escherichia coli K1 and E. coli K5 strains with Acanthamoeba castellanii trophozoites and cysts, association assay, invasion assay, survival assay, and the measurement of bacterial numbers from cysts were performed, and nonpathogenic E. coli K12 was also applied. The association ratio of E. coli K1 with A. castellanii was 4.3 cfu per amoeba for 1 hr but E. coli K5 with A. castellanii was 1 cfu per amoeba for 1 hr. By invasion and survival assays, E. coli K5 was recovered less than E. coli K1 but still alive inside A. castellanii. E. coli K1 and K5 survived and multiplied intracellularly in A. castellanii. The survival assay was performed under a favourable condition for 22 hr and 43 hr with the encystment of A. castellanii. Under the favourable condition for the transformation of trophozoites into cysts, E. coli K5 multiplied significantly. Moreover, the pathogenic potential of E. coli K1 from A. castellanii cysts exhibited no changes as compared with E. coli K1 from A. castellanii trophozoites. E. coli K5 was multiplied in A. castellanii trophozoites and survived in A. castellanii cysts. Therefore, this study suggests that E. coli K5 can use A. castellanii as a reservoir host or a vector for the bacterial transmission.

  8. Behavior of non-O157 Shiga toxin-producing Escherichia coli, enteroinvasive E. coli, enteropathogenic E. coli, and enterotoxigenic E. coli strains on alfalfa sprouts.

    Science.gov (United States)

    Gómez-Aldapa, Carlos A; Rangel-Vargas, Esmeralda; Torres-Vitela, M Del Refugio; Villarruel-López, Angélica; Castro-Rosas, Javier

    2013-08-01

    Data about the behavior of non-O157 Shiga toxin-producing Escherichia coli (non-O157 STEC), enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC), and enteropathogenic E. coli (EPEC) on seeds and alfalfa sprouts are not available. The behavior of STEC, EIEC, ETEC, and EPEC was determined during germination and sprouting of alfalfa seeds at 20 ± 2°C and 30 ± 2°C and on alfalfa sprouts at 3 ± 2°C. When alfalfa seeds were inoculated with STEC, EIEC, ETEC, or EPEC strains, all these diarrheagenic E. coli pathotypes (DEPs) grew during germination and sprouting of seeds, reaching counts of approximately 5 and 6 log CFU/g after 1 day at 20 ± 2°C and 30 ± 2°C, respectively. However, when the sprouts were inoculated after 1 day of seed germination and stored at 20 ± 2°C or 30 ± 2°C, no growth was observed for any DEP during sprouting at 20 ± 2°C or 30 ± 2°C for 9 days. Refrigeration reduced significantly (P < 0.0.5) the number of viable DEPs on sprouts after 20 days in storage; nevertheless, these decreases have no practical significance for the safety of the sprouts.

  9. ANALISIS KANDUNGAN BORAKS DAN Escherichia coli PADA JAJANAN BAKSO SAPI YANG DIPERDAGANGKAN DI KOTA BANJARBARU

    Directory of Open Access Journals (Sweden)

    Nur Rahmi

    2016-09-01

    Full Text Available This study aims to determine how the content of borax and Escherichia coli on meatballs snacks and the factors that affect the food security of meatballs snacks by using Easy Method of Borax Test and Method of Most Probable Number (MPN for Escherichia coli bacteria contamination. This research was conducted in Banjarbaru on 5 villages, and sampling technique used is stratified sampling. The results of the study showed that from 32 samples taken from five village location, it was not identified any borax based on PERMENKES No. 033 of 2012, while for the examination of Escherichia coli, there are 14 samples of meatballs (43.75% which were eligible, and 18 samples of meatballs (56.25% which containEscherichia coli ranges from 3.6 to 62 CFU /g or not meeting the criteria of ISO 7388: 2009. The factor that might not trigger the addition of borax is that the traders have a good knowledge and attitude toward borax which regarded as a toxic substance and can be harmful to health. Factors that cause microbial contamination of Escherichia coli on meatballs snacks is the lack of food hygiene and sanitation in the food processing, cooked food storage, transport, serving, sanitation facilities, and personnel handlers compared with the good supply of foodstuffs and food ingredients storage.

  10. Sterilization by Cooling in Isochoric Conditions: The Case of Escherichia coli.

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    Samuel Salinas-Almaguer

    Full Text Available High hydrostatic pressure (HHP affects the structure, metabolism and survival of micro-organisms including bacteria. For this reason HHP is a promising treatment in the food industry. The aim of this work is to evaluate the effect of high pressure, under isochoric cooling conditions, on Escherichia coli, where such high pressure develops due to the fact water cannot expand. We combine survival curves obtained by spectrophotometry and images of atomic force microscopy in this study. Our results show that cooling at -20 and -30°C leads to a partial destruction of a Escherichia coli population. However, cooling at -15°C causes a total extermination of bacteria. This intriguing result is explained by the phase diagram of water. In the first case, the simultaneous formation of ice III and ice Ih crystals provides a safe environment for bacteria. In the second case (-15°C Escherichia coli remains in a metastable and amorphous free-of-crystals liquid subjected to high pressure. Our work is the first experimental study carried out to inactivate Escherichia coli under isochoric cooling conditions. Unlike HHP, which is based on the application of an external load to augment the pressure, this technique only requires cooling. The method could be used for annihilation of other Escherichia coli strains and perhaps other micro-organisms.

  11. Enumeration of Escherichia coli O157:H7 in Outbreak-Associated Beef Patties.

    Science.gov (United States)

    Gill, Alexander; Huszczynski, George

    2016-07-01

    An outbreak of five cases of Escherichia coli O157 infection that occurred in Canada in 2012 was linked to frozen beef patties seasoned with garlic and peppercorn. Unopened retail packs of beef patties from the implicated production lot were recovered and analyzed to enumerate E. coli O157, other E. coli strains, and total coliforms. E. coli O157 was not recovered by direct enumeration on selective agar media. E. coli O157 in the samples was estimated at 3.1 most probable number per 140 g of beef patty, other E. coli was 11 CFU/g, and coliforms were 120 CFU/g. These results indicate that the presence of E. coli O157 in ground beef at levels below 0.1 CFU/g may cause outbreaks. However, the roles of temperature abuse, undercooking, and crosscontamination in amplifying the risk are unknown.

  12. Interactions between microsatellite instability and human gut colonization by Escherichia coli in colorectal cancer.

    Science.gov (United States)

    Gagnière, Johan; Bonnin, Virginie; Jarrousse, Anne-Sophie; Cardamone, Emilie; Agus, Allison; Uhrhammer, Nancy; Sauvanet, Pierre; Déchelotte, Pierre; Barnich, Nicolas; Bonnet, Richard; Pezet, Denis; Bonnet, Mathilde

    2017-01-16

    Recent studies suggest that colonization of colonic mucosa by pathogenic Escherichia coli (E. coli) could be involved in the development of colorectal cancer (CRC), especially through the production of genotoxins such as colibactin and/or by interfering with the DNA mismatch repair (MMR) pathway which leads to microsatellite instability (MSI). This work, performed on 88 CRC patients, revealed a significant increase in E. coli colonization in the MSI CRC phenotype. In the same way, E. coli persistence and internalization were increased in vitro in MMR-deficient cells. Moreover, we demonstrated that colibactin-producing E. coli induce inhibition of the MLH1 MMR proteins, which could lead to genomic instability. However, colibactin-producing E. coli were more frequently identified in microsatellite stable (MSS) CRC. This work suggests differences in the involvement of colibactin-producing E. coli in colorectal carcinogenesis according to the CRC phenotype. Further host/pathogens interactions studies should take into account CRC phenotypes.

  13. Radiosensitization of Escherichia coli and Salmonella typhi in presence of active compounds

    Science.gov (United States)

    Lacroix, M.; Chiasson, F.; Borsa, J.; Ouattara, B.

    2004-09-01

    The radiosensitization of Escherichia coli and Salmonella typhi in ground beef was evaluated in the presence of 18 active compounds. Medium fat ground beef (23% fat) was inoculated with E. coli or S. typhi and each active compound was added separately at various concentrations. For E. coli, the most efficient compounds were trans-cinnamaldehyde, thymol and thyme. For S. typhi, the most efficient compounds was trans-cinnamaldehyde, carvacrol and thymol. The addition of tetrasodium pyrophosphate, carvacrol and ascorbic acid had no effect on the irradiation sensitivity of E. coli. For S. typhi, only ascorbic acid had no effect.

  14. Radiosensitization of Escherichia coli and Salmonella typhi in presence of active compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lacroix, M. E-mail: monique.lacroix@inrs-iaf.uquebec.ca; Chiasson, F.; Borsa, J.; Ouattara, B

    2004-10-01

    The radiosensitization of Escherichia coli and Salmonella typhi in ground beef was evaluated in the presence of 18 active compounds. Medium fat ground beef (23% fat) was inoculated with E. coli or S. typhi and each active compound was added separately at various concentrations. For E. coli, the most efficient compounds were trans-cinnamaldehyde, thymol and thyme. For S. typhi, the most efficient compounds was trans-cinnamaldehyde, carvacrol and thymol. The addition of tetrasodium pyrophosphate, carvacrol and ascorbic acid had no effect on the irradiation sensitivity of E. coli. For S. typhi, only ascorbic acid had no effect.

  15. Human Health Hazards from Antimicrobial-Resistant Escherichia coli of Animal Origin

    DEFF Research Database (Denmark)

    Hammerum, A. M.; Heuer, Ole Eske

    2009-01-01

    Because of the intensive use of antimicrobial agents in food animal production, meat is frequently contaminated with antimicrobial-resistant Escherichia coli. Humans can be colonized with E. coli of animal origin, and because of resistance to commonly used antimicrobial agents, these bacteria may...... cause infections for which limited therapeutic options are available. This may lead to treatment failure and can have serious consequences for the patient. Furthermore, E. coli of animal origin may act as a donor of antimicrobial resistance genes for other pathogenic E. coli. Thus, the intensive use...

  16. Different effects of ppGpp on Escherichia coli DNA replication in vivo and in vitro.

    Science.gov (United States)

    Maciąg-Dorszyńska, Monika; Szalewska-Pałasz, Agnieszka; Węgrzyn, Grzegorz

    2013-01-01

    Inhibition of Escherichia coli DNA replication by guanosine tetraphosphate (ppGpp) is demonstrated in vitro. This finding is compatible with impairment of the DnaG primase activity by this nucleotide. However, in agreement to previous reports, we were not able to detect a rapid inhibition of DNA synthesis in E. coli cells under the stringent control conditions, when intracellular ppGpp levels increase dramatically. We suggest that the process of ppGpp-mediated inhibition of DnaG activity may be masked in E. coli cells, which could provide a rationale for explanation of differences between ppGpp effects on DNA replication in E. coli and Bacillus subtilis.

  17. Escherichia coli O157:H7 - An Emerging Pathogen in foods of Animal Origin

    Directory of Open Access Journals (Sweden)

    Ch. Bindu Kiranmayi

    Full Text Available Escherichia coli O157:H7 is an emerging public health concern in most countries of the world. E. coli O157:H7 was known to be a human pathogen for nearly 24 years. EHEC O157 infection is estimated to be the fourth most costly food borne disease in Canada and USA, not counting the cost of possible litigation. E. coli O157:H7 and Salmonella are the leading causes of produce related outbreaks, accounting for 20 and 30% respectively. The authority of the Federal Meat Inspection Act, FSIS (Food Safety and Inspection Service declared Escherichia coli O157:H7, an adulterant in raw ground beef and enforced “zero tolerance” (USDA-FSIS, 17 December 1998. Because of the severity of these illnesses and the apparent low infective dose (less than 10 cells, Escherichia coli O157:H7 is considered one of the most serious of known food borne pathogens. Escherichia coli O157:H7 is mainly pathogenic to human but in cattle and other animals, it did not induce any clinical disease except diarrhea. So, these animals act as carriers to Escherichia coli O157:H7. The majority transmission is through eating of undercooked contaminated ground meat and consumption of raw milk, raw vegetables, fruits contaminated by water, cheese, curd and also through consumption of sprouts, lettuce and juice. The conventional isolation procedure includes growth in enrichment broth like modified EC (E. coli broth or modified tryptic soy broth (mTSB Since the infection primarily occurs via faeco-oral route, the preventive measures include food hygiene measures like proper cooking of meat, consumption of pasteurized milk, washing fruits and vegetables especially those to be eaten raw and drinking chlorine treated water and personnel hygiene measures like washing hands after toilet visits. [Veterinary World 2010; 3(8.000: 382-389

  18. Pseudomonas aeruginosa promotes Escherichia coli biofilm formation in nutrient-limited medium.

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    Alessandro Culotti

    Full Text Available Biofilms have been implicated as an important reservoir for pathogens and commensal enteric bacteria such as Escherichia coli in natural and engineered water systems. However, the processes that regulate the survival of E. coli in aquatic biofilms have not been thoroughly studied. We examined the effects of hydrodynamic shear and nutrient concentrations on E. coli colonization of pre-established Pseudomonas aeruginosa biofilms, co-inoculation of E. coli and P. aeruginosa biofilms, and P. aeruginosa colonization of pre-established E. coli biofilms. In nutritionally-limited R2A medium, E. coli dominated biofilms when co-inoculated with P. aeruginosa, and successfully colonized and overgrew pre-established P. aeruginosa biofilms. In more enriched media, P. aeruginosa formed larger clusters, but E. coli still extensively overgrew and colonized the interior of P. aeruginosa clusters. In mono-culture, E. coli formed sparse and discontinuous biofilms. After P. aeruginosa was introduced to these biofilms, E. coli growth increased substantially, resulting in patterns of biofilm colonization similar to those observed under other sequences of organism introduction, i.e., E. coli overgrew P. aeruginosa and colonized the interior of P. aeruginosa clusters. These results demonstrate that E. coli not only persists in aquatic biofilms under depleted nutritional conditions, but interactions with P. aeruginosa can greatly increase E. coli growth in biofilms under these experimental conditions.

  19. Quality control of inclusion bodies in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Schweder Thomas

    2010-05-01

    Full Text Available Abstract Background Bacterial inclusion bodies (IBs are key intermediates for protein production. Their quality affects the refolding yield and further purification. Recent functional and structural studies have revealed that IBs are not dead-end aggregates but undergo dynamic changes, including aggregation, refunctionalization of the protein and proteolysis. Both, aggregation of the folding intermediates and turnover of IBs are influenced by the cellular situation and a number of well-studied chaperones and proteases are included. IBs mostly contain only minor impurities and are relatively homogenous. Results IBs of α-glucosidase of Saccharomyces cerevisiae after overproduction in Escherichia coli contain a large amount of (at least 12 different major product fragments, as revealed by two-dimensional polyacrylamide gel electrophoresis (2D PAGE. Matrix-Assisted-Laser-Desorption/Ionization-Time-Of-Flight Mass-Spectrometry (MALDI-ToF MS identification showed that these fragments contain either the N- or the C-terminus of the protein, therefore indicate that these IBs are at least partially created by proteolytic action. Expression of α-glucosidase in single knockout mutants for the major proteases ClpP, Lon, OmpT and FtsH which are known to be involved in the heat shock like response to production of recombinant proteins or to the degradation of IB proteins, clpP, lon, ompT, and ftsH did not influence the fragment pattern or the composition of the IBs. The quality of the IBs was also not influenced by the sampling time, cultivation medium (complex and mineral salt medium, production strategy (shake flask, fed-batch fermentation process, production strength (T5-lac or T7 promoter, strain background (K-12 or BL21, or addition of different protease inhibitors during IB preparation. Conclusions α-glucosidase is fragmented before aggregation, but neither by proteolytic action on the IBs by the common major proteases, nor during downstream IB

  20. Development of a Vaccine against Escherichia coli Urinary Tract Infections

    Science.gov (United States)

    Mobley, Harry L. T.; Alteri, Christopher J.

    2015-01-01

    Urinary tract infection (UTI) is the second most common infection in humans after those involving the respiratory tract. This results not only in huge annual economic costs, but in decreased workforce productivity and high patient morbidity. Most infections are caused by uropathogenic Escherichia coli (UPEC). Antibiotic treatment is generally effective for eradication of the infecting strain; however, documentation of increasing antibiotic resistance, allergic reaction to certain pharmaceuticals, alteration of normal gut flora, and failure to prevent recurrent infections represent significant barriers to treatment. As a result, approaches to prevent UTI such as vaccination represent a gap that must be addressed. Our laboratory has made progress toward development of a preventive vaccine against UPEC. The long-term research goal is to prevent UTIs in women with recurrent UTIs. Our objective has been to identify the optimal combination of protective antigens for inclusion in an effective UTI vaccine, optimal adjuvant, optimal dose, and optimal route of delivery. We hypothesized that a multi-subunit vaccine elicits antibody that protects against experimental challenge with UPEC strains. We have systematically identified four antigens that can individually protect experimentally infected mice from colonization of the bladder and/or kidneys by UPEC when administered intranasally with cholera toxin (CT) as an adjuvant. To advance the vaccine for utility in humans, we will group the individual antigens, all associated with iron acquisition (IreA, Hma, IutA, FyuA), into an effective combination to establish a multi-subunit vaccine. We demonstrated for all four vaccine antigens that antigen-specific serum IgG represents a strong correlate of protection in vaccinated mice. High antibody titers correlate with low colony forming units (CFUs) of UPEC following transurethral challenge of vaccinated mice. However, the contribution of cell-mediated immunity cannot be ruled out and