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1

Photodynamic inactivation of recombinant bioluminescent Escherichia coli by cationic porphyrins under artificial and solar irradiation  

Microsoft Academic Search

A faster and simpler method to monitor the photoinactivation process of Escherichia coli involving the use of recombinant bioluminescent bacteria is described here. Escherichia coli cells were transformed with luxCDABE genes from the marine bioluminescent bacterium Vibrio fischeri and the recombinant bioluminescent indicator strain was used to assess, in real time, the effect of three cationic meso-substituted porphyrin derivatives on

Eliana Alves; Carla M. B. Carvalho; João P. C. Tomé; Maria A. F. Faustino; Maria G. P. M. S. Neves; Augusto C. Tomé; José A. S. Cavaleiro; Ângela Cunha; Sónia Mendo; Adelaide Almeida

2008-01-01

2

Antioxidant assay using genetically engineered bioluminescent Escherichia coli  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

3

In vivo bioluminescence imaging for the study of intestinal colonization by Escherichia coli in mice.  

PubMed

Bioluminescence imaging (BLI) is emerging as a powerful tool for real-time monitoring of infections in living animals. However, since luciferases are oxygenases, it has been suggested that the requirement for oxygen may limit the use of BLI in anaerobic environments, such as the lumen of the gut. Strains of Escherichia coli harboring the genes for either the bacterial luciferase from Photorhabdus luminescens or the PpyRE-TS and PpyGR-TS firefly luciferase mutants of Photinus pyralis (red and green thermostable P. pyralis luciferase mutants, respectively) have been engineered and used to monitor intestinal colonization in the streptomycin-treated mouse model. There was excellent correlation between the bioluminescence signal measured in the feces (R2=0.98) or transcutaneously in the abdominal region of whole animals (R2=0.99) and the CFU counts in the feces of bacteria harboring the luxABCDE operon. Stability in vivo of the bioluminescence signal was achieved by constructing plasmid pAT881(pGB2OmegaPamiluxABCDE), which allowed long-term monitoring of intestinal colonization without the need for antibiotic selection for plasmid maintenance. Levels of intestinal colonization by various strains of E. coli could be compared directly by simple recording of the bioluminescence signal in living animals. The difference in spectra of light emission of the PpyRE-TS and PpyGR-TS firefly luciferase mutants and dual bioluminescence detection allowed direct in vitro and in vivo quantification of two bacterial populations by measurement of red and green emitted signals and thus monitoring of the two populations simultaneously. This system offers a simple and direct method to study in vitro and in vivo competition between mutants and the parental strain. BLI is a useful tool to study intestinal colonization. PMID:19880653

Foucault, M-L; Thomas, L; Goussard, S; Branchini, B R; Grillot-Courvalin, C

2010-01-01

4

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

SciTech Connect

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

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

1987-11-01

5

Activation of bioluminescence of sensor Escherichia coli srains used to detect N -acyl-homoserine lactones in presence of nitrofurans and NO generators  

Microsoft Academic Search

Nitrofurans (nitrofurazone, nitrofurantoin, furazidin, nifuroxazide) and nitric oxide generators (sodium nitroprusside and\\u000a isosorbide mononitrate) in subinhibitory concentrations were shown to significantly increase the bioluminescence of the sensor\\u000a Escherichia coli strains used to detect N-acyl-homoserine lactones, which are signal molecules of quorum sensing (QS) regulatory systems. The highest activation of\\u000a bioluminescence (up to 250–400-fold) was observed in the presence of the

Yu. V. Zaitseva; V. G. Granik; A. S. Belik; O. A. Koksharova; I. A. Khmel

2010-01-01

6

LuxCDABE—Transformed Constitutively Bioluminescent Escherichia coli for Toxicity Screening: Comparison with Naturally Luminous Vibrio fischeri  

PubMed Central

We show that in vitro toxicity assay based on inhibition of the bioluminescence of recombinant Escherichia coli encoding thermostable luciferase from Photorhabdus luminescens is a versatile alternative to Vibrio fischeri Microtox™ test. Performance of two luxCDABE-transformed E. coli MC1061 constructs (pDNlux) and (pSLlux) otherwise identical, but having 100-fold different background luminescence was compared with the performance of V. fischeri. The microplate luminometer and a kinetic Flash-Assay test format was used that differently from Microtox test is also applicable for high throughput analysis. Toxic effects (30-s till 30-min EC50) of four heavy metals (Zn, Cd, Hg, Cu) and three organic chemicals (aniline, 3,5-dichloroaniline and 3,5-dichlorophenol) were studied. Both E. coli strains had comparable sensitivity and the respective 30-min EC50 values highly correlated (log-log R2 = 0.99; p < 0.01) showing that the sensitivity of the recombinant bacteria towards chemicals analyzed did not depend on the bioluminescence level of the recombinant cells. The most toxic chemical for all used bacterial strains (E. coli, V. fischeri) was mercury whereas the lowest EC50 values for Hg (0.04–0.05 mg/L) and highest EC50 values for aniline (1,300–1,700 mg/L) were observed for E. coli strains. Despite of that, toxicity results obtained with both E. coli strains (pSLlux and pDNlux) significantly correlated with V. fischeri results (log-log R2 = 0.70/0.75; p < 0.05/0.01). The use of amino acids (0.25%) and glucose (0.05%)-supplemented M9 medium instead of leucine-supplemented saline significantly (p < 0.05) reduced the apparent toxicity of heavy metals to both E. coli strains up to three orders of magnitude, but had little or no complexing effect on organic compounds. Thus, P. luminescens luxCDABE-transformed E. coli strains can be successfully used for the acute toxicity screening of various types of organic chemicals and heavy metals and can replace V. fischeri in certain cases where the thermostability of luciferase >30 °C is crucial. The kinetic Flash Assay test format of the bioluminescence inhibition assay facilitates high throughput analysis. The assay medium, especially in case of testing heavy metals should be a compromise: optimal for the viability/luminescence of the recombinant test strain and of minimum complexing potential.

Kurvet, Imbi; Ivask, Angela; Bondarenko, Olesja; Sihtmae, Mariliis; Kahru, Anne

2011-01-01

7

Bioluminescent Escherichia coli strains for the quantitative detection of phosphate and ammonia in coastal and suburban watersheds.  

PubMed

Accumulation of phosphate and ammonia in estuarine systems and subsequent dinoflagellate and algal blooms has been implicated in fish kills and in health risks for fishermen. Analytic chemistry kits are used to measure phosphate and ammonia levels in water samples, but their sensitivity is limited due to specificity for inorganic forms of these moieties. An Escherichia coli bioluminescent reporter system measured the bioavailability of inorganic nutrients through fusion of E. coli promoters (phoA or glnAp2) to the luxCDABE operon of Vibrio fischeri carried either on the chromosome or on a multicopy plasmid vector, resulting in emission of light in response to phosphate or ammonia starvation. Responses were shown to be under the control of expected physiological regulators, phoB and glnFG, respectively. Standard curves were used to determine the phosphate and ammonia levels in water samples from diverse watersheds located in the northeastern United States. Bioluminescence produced in response to nutrient starvation correlated with concentrations of phosphate (1-24 ppm) and ammonia (0.1-1.6 ppm). While the ammonia biosensor measured nutrient concentrations in tested water samples that were comparable to the amounts reported by a commercial kit, the phosphate biosensor reported higher levels of phosphate in Chesapeake water samples than did the kit. PMID:20491581

Cardemil, Cristina V; Smulski, Dana R; Larossa, Robert A; Vollmer, Amy Cheng

2010-09-01

8

Use of bioluminescent Escherichia coli to determine retention during the life cycle of the housefly, Musca domestica (Diptera: Muscidae, L).  

PubMed

Researchers have documented that the housefly (Musca domestica) can serve as a vector for the spread of foodborne pathogens to livestock, food, and humans. Most studies have investigated Musca domestica as a vector only after the fly comes into contact or consumes the pathogen as an adult. The objective of this study was to determine whether the larvae of Musca domestica could ingest Escherichia coli from bovine manure and whether the E. coli could survive the metamorphosis process and be transmitted. Larvae (n=960) were incubated in sterilized bovine manure inoculated with 0, 3, 5, and 8 log10 colony-forming units (CFU)/mL of bioluminescent E. coli for 24 (larvae stage), 48 (larvae stage), 120 (pupae stage), and 192?h (adult stage). Larvae incubated for 24?h in bovine manure possessed 0.0, 2.7, 2.9, and 3.5 log(10) CFU/mL of E. coli, from inoculated with 0, 3, 5, and 8 log(10) CFU/mL of E. coli, respectively. Concentrations of E. coli within the pupae were 0.0, 1.7, 1.9, and 2.2 log(10) CFU/mL for each inoculation concentration, respectively. Flies that emerged from the pupae stage contained 0.0, 1.3, 2.2, and 1.7 log(10) CFU/mL of E. coli from larvae incubated in manure inoculated with concentrations of E. coli, respectively. These results suggest the housefly can emerge with quantities of E. coli. While this was an enteropathogenic E. coli (EPEC), these data may suggest that if the fly is capable of retaining similar concentrations of an enterohemorrhagic E. coli (EHEC), these concentrations may be capable of initiating illness in humans. Furthermore, the E. coli concentration within and on adult flies is related to environmental exposure. It must be noted that larvae were incubated in sterilized bovine manure, and there was no other bacterial competition for the E. coli. Thus, the rate of positive flies and concentrations present when flies emerged may vary under more realistic conditions. PMID:23536983

Schuster, Greta L; Donaldson, Janet R; Buntyn, Joe O; Duoss, Heather A; Callaway, Todd R; Carroll, Jeff A; Falkenberg, Shollie M; Schmidt, Ty B

2013-05-01

9

[Activation of the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones in the presence of nitrofurans and NO generators].  

PubMed

Nitrofurans (nitrofurazone, nitrofurantoin, furazidin, nifuroxazide), and nitric oxide generators (sodium nitroprusside and isosorbide mononitrate) in subinhibitory concentrations were shown to significantly increase the bioluminescence of the sensor Escherichia coli strains used for detecting N-acyl-homoserine lactones, signaling molecules of Quorum Sensing (QS) regulatory systems. The highest activation of bioluminescence (up to 250-400 fold) was observed in the presence of nitrofurazone on E. coli DH5alpha biosensors containing lux-reporter plasmids pSB401 or pSB536. However, this activation was not specifically associated with the functioning of QS systems. We suggest that the effect observed results from a direct action of nitrofurans and NO donors on the process of bioluminescence. The data indicate the necessity of using the biosensors that make it possible to detect specific effects of substances tested on QS regulation. PMID:20540359

Za?tseva, Iu V; Granik, V G; Belik, A S; Koksharova, O A; Khmel', I A

2010-01-01

10

Validation of a Noninvasive, Real-Time Imaging Technology Using Bioluminescent Escherichia coli in the Neutropenic Mouse Thigh Model of Infection  

Microsoft Academic Search

A noninvasive, real-time detection technology was validated for qualitative and quantitative antimicrobial treatment applications. The lux gene cluster of Photorhabdus luminescens was introduced into an Escherichia coli clinical isolate, EC14, on a multicopy plasmid. This bioluminescent reporter bacterium was used to study antimicrobial effects in vitro and in vivo, using the neutropenic-mouse thigh model of infection. Biolumines- cence was monitored

H. L. Rocchetta; C. J. Boylan; J. W. Foley; P. W. Iversen; D. L. LeTourneau; C. L. McMillian; P. R. Contag; D. E. Jenkins; T. R. Parr

2001-01-01

11

Expression of bioluminescence by Escherichia coli containing recombinant Vibrio harveyi DNA.  

PubMed Central

When isogenic strains of Escherichia coli, RR1 (rec+) and HB101 (recA), were transformed with mapped recombinant plasmids known to contain Vibrio harveyi luciferase genes and large regions of DNA flanking on both sides, a small percentage (0.005%) of the colonies expressed high levels of luminescence (up to 10(12) quanta s-1 ml-1) in the absence of added aldehyde. The altered ability to express light was found to be due to a mutation in the host and not to an alteration in the recombinant DNA. When these bright colonies were cured of plasmid, they could be retransformed with cloned V. harveyi gene fragments in cis and in trans to yield luminescent colonies at 100% frequency. The maximum length of V. harveyi DNA required to produce light-emitting E. coli was shorter (6.3 kilobase pairs) than that required for expression of the V. fischeri system in E. coli. Cell extracts from bright clones contained wild-type levels of activity for the heteropolymeric (alpha beta) luciferase; fatty acid labeling revealed the presence of the three acylated polypeptides of the fatty acid reductase system which is involved in aldehyde biosynthesis for the luminescence reaction. The increased light emission in the mutant bacteria appeared to arise in part from production of higher levels of polycistronic mRNAs coding for luciferase. Images

Miyamoto, C; Byers, D; Graham, A F; Meighen, E A

1987-01-01

12

Cell-based galactosemia diagnosis system based on a galactose assay using a bioluminescent Escherichia coli array.  

PubMed

A new cell-based galactose assay system, which is comprised of two bioluminescent Escherichia coli strains immobilized within an agarose gel arrayed on a well plate, has been developed. For this purpose, a galT knockout strain [galT(-) cell] of E. coli was genetically constructed so that cell growth is not promoted by galactose but rather by glucose present in a sample. Another E. coli W strain (normal cell), which grows normally in the presence of either glucose or galactose, was employed. A luminescent reporter gene, which produces luminescence as cells grow, was inserted into both of the E. coli strains, so that cell growth could be monitored in a facile manner. The two strains were separately grown for 4 h on gel arrays to which test samples were individually supplied. The relative luminescence unit (RLU) values caused by cell growth were determined for each array, one of which is resulted by glucose only and the other of which is resulted by both glucose and galactose present in the sample. By employing this protocol, galactose concentrations present in the test sample are reflected in the differences between the RLU values for each array. The practical utility of the new assay system was demonstrated by its use in determining galactose levels in clinical blood spot specimens coming from newborn babies. Because it can be employed to diagnosis of galactosemia in newborn babies in a more rapid, convenient, and cost-effective manner, this cell-based solid-phase galactose assay system should become a powerful alternative to conventional methods, which require labor-intensive and time-consuming procedures and/or complicated and expensive equipment. PMID:24143930

Woo, Min-Ah; Kim, Moon Il; Cho, Daeyeon; Park, Hyun Gyu

2013-11-19

13

Escherichia Coli  

ERIC Educational Resources Information Center

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…

Goodsell, David S.

2009-01-01

14

Pathogenic Escherichia coli  

Microsoft Academic Search

Few microorganisms are as versatile as Escherichia coli. An important member of the normal intestinal microflora of humans and other mammals, E. coli has also been widely exploited as a cloning host in recombinant DNA technology. But E. coli is more than just a laboratory workhorse or harmless intestinal inhabitant; it can also be a highly versatile, and frequently deadly,

James P. Nataro; Harry L. T. Mobley; James B. Kaper

2004-01-01

15

PATHOGENIC ESCHERICHIA COLI  

EPA Science Inventory

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

16

Escherichia coli biofilms  

PubMed Central

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

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

2008-01-01

17

Recurrent Escherichia coli bacteremia.  

PubMed Central

Escherichia coli is the most common gram-negative organism associated with bacteremia. While recurrent E. coli urinary tract infections are well-described, recurrent E. coli bacteremia appears to be uncommon, with no episodes noted in multiple series of patients with gram-negative bacteremias. We report on 5 patients with recurrent bloodstream infections identified from a series of 163 patients with E. coli bacteremia. For each patient, the isolates from each episode were analyzed by pulsed-field gel electrophoresis (PFGE) and ribotyping and for the presence of E. coli virulence factors. For each of four patients, the index and recurrent episodes of bacteremia represented the same strain as defined by PFGE, and the strains were found to carry one or more virulence factors. The remaining patient, with two episodes of bloodstream infection separated by a 4-year interval, was infected with two isolates that did not carry any virulence factors and that were clonally related by ribotype analysis but differed by PFGE. All five patients had either a local host defense defect (three patients) or impaired systemic defenses (one patient) or both (one patient). Thus, recurrent E. coli bacteremia is likely to represent a multifactorial process that occurs in patients with impaired host defenses who are infected with virulent isolates. Images

Maslow, J N; Mulligan, M E; Arbeit, R D

1994-01-01

18

Bioluminescence  

NSDL National Science Digital Library

This Bioluminescence webpage is an entry in Kimball's online biology textbook. It discusses the ability of living things to emit light, the various molecules involved, how fireflies control their flashing, and bioluminescence in marine organisms.

Kimball, John W.; Pages, Kimball'S B.

19

Bioluminescence.  

ERIC Educational Resources Information Center

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

Jones, M. Gail

1993-01-01

20

Enteropathogenic Escherichia coli: unravelling pathogenesis  

Microsoft Academic Search

Enteropathogenic Escherichia coli (EPEC) is a gram-negative bacterial pathogen that adheres to intestinal epithelial cells, causing diarrhoea. It constitutes a significant risk to human health and remains an important cause of infant mortality in developing countries. Although EPEC was the first E. coli strain to be implicated in human disease in the 1940s and 1950s, the mechanisms by which this

Huiwen Deborah Chen; Gad Frankel

2005-01-01

21

Escherichia coli bactofection using Lipofectamine.  

PubMed

Successful gene delivery into mammalian cells using bactofection requires entry of the bacterial vector via cell surface integrin receptors followed by release of plasmid DNA into the cellular environment. We show, for the first time, that addition of the DNA transfection reagent Lipofectamine improves entry of invasive Escherichia coli into HeLa cells and enhances up to 2.8-fold green fluorescent protein (GFP) expression from a reporter plasmid. The addition of Lipofectamine may be applicable to other bacterial vectors to increase their DNA delivery efficiency into mammalian cells. PMID:23608053

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

2013-08-15

22

ENZYME BIOSYNTHESIS IN ESCHERICHIA COLI  

PubMed Central

Escherichia coli B synthesized ?-galactosidase and an enzyme system for D-xylose when exposed to lactose and xylose respectively in nitrogen-free media. The amount of ?-galactosidase formed in the absence of external nitrogen depended upon the nature of the medium in which the cells had originally been grown. Half as much of this enzyme was synthesized without exogenous nitrogen by cells taken from a nitrogen-rich medium as was formed by cells under favorable conditions with an external supply of nitrogen. Escherichia coli B contained a pool of nitrogen compounds soluble in 80 per cent ethanol and made up of several ninhydrin-positive components. One of these was identified chromatographically as glycine using an authentic radioactive sample. Another substance behaved like serine on the chromatograms. The internal pool of amino acids and peptides was large enough to account for the ?-galactosidase synthesized by cells exposed to lactose in a medium free of nitrogen. Some degree of interaction of the syntheses of the ?-galactosidase and xylose enzyme systems was observed in nitrogen-free media. This interaction produced a greater effect on the formation of ?-galactosidase and was attributed to a limiting factor(s) in the internal nitrogenous pool or to a limiting intermediate in enzyme synthesis.

Weinbaum, George; Mallette, M. F.

1959-01-01

23

Methionineless Death in Escherichia coli  

PubMed Central

Methionine auxotrophs of strains derived from Escherichia coli 15 lose their colony-forming ability when deprived of this amino acid. Late addition of methionine to liquid cultures did not restore plating efficiency but permitted growth of surviving cells. This phenomenon, termed methionineless death (mld), was not observed with methionine auxotrophs of E. coli strains B, W, or K12, nor was a similar amino acidless death observed with corresponding auxotrophs of E. coli 15 for arginine, tryptophan, proline, isoleucine, and leucine. Mld was not dependent upon the genetic site determining methionine auxotrophy, nor did it affect the decarboxylation of methionine or the stability of methionyl-transfer ribonucleic acid synthetase activity of starved cells. Death was not altered by the presence of spermine or spermidine but was abolished by the methionine analogue, ?-methylmethionine. Simultaneous starvation of another amino acid in a multiple auxotroph also significantly reduced mld, suggesting a possible role of protein synthesis. The onset of mld is correlated with a lower net increase of deoxyribonucleic acid.

Breitman, T. R.; Finkleman, A.; Rabinovitz, M.

1971-01-01

24

In Vivo Bioluminescence Imaging of the Murine Pathogen Citrobacter rodentium  

Microsoft Academic Search

Citrobacter rodentium is a natural mouse pathogen related to enteropathogenic and enterohemorrhagic Escherichia coli. We have previously utilized bioluminescence imaging (BLI) to determine the in vivo coloni- zation dynamics of C. rodentium. However, due to the oxygen requirement of the bioluminescence system and the colonic localization of C. rodentium, in vivo localization studies were performed using harvested organs. Here, we

Siouxsie Wiles; Karen M. Pickard; Katian Peng; Thomas T. MacDonald; Gad Frankel

2006-01-01

25

Escherichia coli - Marauding masquerading microbe  

PubMed Central

Background Escherichia coli is a rare cause of monoarticular septic arthritis, but is an even rarer cause of polyarticular septic arthritis. Case description We report an unusual case of polyarticular septic arthritis with an atypical presentation caused by E. coli, the source of which was a left pyelonephritis. Our patient developed E coli sepsis resulting in polyarticular septic arthritis (PASA) in the absence of typical risk factors except for pre-existing osteoarthritis. The joints involved were the hip, ankle, sternoclavicular and L5/S1 joints. Of interest, ankle pain was not reported or evident until correlated with nuclear medicine scans. Furthermore, sternoclavicular joint involvement presented as left shoulder pain, resulting in an initial misdiagnosis of left shoulder septic arthritis. The patient was treated with surgical washout and antibiotic therapy. He was subsequently discharged from rehabilitation having returned to his baseline level of mobility. Future consideration will be given to total hip arthroplasty. Literature review There are no reported cases of E. coli PASA involving more than three joints in the absence of any recognized risk factors for septic arthritis. Purpose and clinical relevance Asymptomatic involvement of joints can occur in polyarticular septic arthritis and should be considered in all cases of monoarticular septic arthritis (MASA). We believe that clinical suspicion is the key to early and comprehensive diagnosis of polyarticular septic arthritis particularly when presenting in an atypical fashion with an atypical pathogen. Strong consideration should be given to performing nuclear imaging in cases of monoarticular septic arthritis where polyarticular involvement cannot be definitively ruled out.

Lee, Amy; Coleman, Patrick

2013-01-01

26

Construction of a sodA::luxCDABE fusion Escherichia coli : comparison with a katG fusion strain through their responses to oxidative stresses  

Microsoft Academic Search

A recombinant bioluminescent Escherichia coli strain, EBHJ, (sodA::luxCDABE), containing the promoter for the manganese superoxide dismutase (sodA) gene fused to the Vibrio fischeri luxCDABE operon, was successfully constructed and characterized. Redox-cycling agents, such as paraquat and chromium, strongly induced a sodA- regulated response in dose-dependent manners, resulting in an increase of the bioluminescence. In a comparison with an existing oxidative

H. J. Lee; M. B. Gu

2003-01-01

27

Size Fractionation of Exponentially Growing Escherichia coli  

Microsoft Academic Search

A new method for differentiating between bacteria of different sizes in a single population is used to show that the rate of synthesis of RNA in a population of Escherichia coli varies linearly with the size of the cell.

Haim Manor; Robert Haselkorn

1967-01-01

28

Maltoheptaose Promotes Nanoparticle Internalization by Escherichia coli  

PubMed Central

Nanoparticles conjugated with D-maltoheptaose (G7) showed a striking increase in the internalization by Escherichia coli. This applies to strains with and without the maltodextrin transport channel and particles ranging from a few to a hundred nanometers.

Jayawardena, Surangi; Jayawardana, Kalana; Chen, Xuan

2013-01-01

29

Escherichia coli O157 Cluster Evaluation  

PubMed Central

We investigated a multistate cluster of Escherichia coli O157:H7 isolates; pulsed-field gel electrophoresis subtyping, using a single enzyme, suggested an epidemiologic association. An investigation and additional subtyping, however, did not support the association. Confirmating E. coli O157 clusters with two or more restriction endonucleases is necessary before public health resources are allocated to follow-up investigations.

Hunter, Susan B.; Bidol, Sally A.; Dietrich, Stephen; Kincaid, Jennifer; Salehi, Ellen; Nicholson, Lisa; Genese, Carol Ann; Todd-Weinstein, Sarah; Marengo, Lisa; Kimura, Akiko C.; Brooks, John T.

2004-01-01

30

Genetics of Virulence in Enteroinvasive Escherichia coli.  

National Technical Information Service (NTIS)

The term enteroinvasive Escherichia coli (EIEC) is used to differentiate a small number of E. coli bioserotypes which can invade the intestinal mucosa and cause a dysenterylike syndrome similar to shigellosis. As shown in Table 1, the EIEC biotype is usua...

P. J. Sansonetti T. L. Hale E. V. Oaks

1985-01-01

31

The population genetics of commensal Escherichia coli  

Microsoft Academic Search

The primary habitat of Escherichia coli is the vertebrate gut, where it is the predominant aerobic organism, living in symbiosis with its host. Despite the occurrence of recombination events, the population structure is predominantly clonal, allowing the delineation of major phylogenetic groups. The genetic structure of commensal E. coli is shaped by multiple host and environmental factors, and the determinants

Olivier Tenaillon; David Skurnik; Bertrand Picard; Erick Denamur

2010-01-01

32

Firefly luciferase as the reporter for transcriptional response to the environment in Escherichia coli.  

PubMed

We demonstrate that firefly luciferase is a good reporter in Escherichia coli for transcription dynamics in response to the environment. E. coli strains, carrying a fusion of the promoter of the ycgZ gene and the coding region of the luciferase gene, showed transient bioluminescence on receiving blue light. This response was compromised in mutants lacking known regulators in manners consistent with each regulator's function. We also show that relA, a gene encoding a (p)ppGpp synthetase, affects ycgZ dynamics when nullified. Moreover, two unstable luciferase variants showed improved response dynamics and should be useful to study quick changes of gene expression. PMID:24012794

Ryo, Masashi; Oshikoshi, Yuta; Doi, Shosei; Motoki, Shogo; Niimi, Atsuko; Aoki, Setsuyuki

2013-12-15

33

Succinate production in Escherichia coli  

PubMed Central

Succinate has been recognized as an important platform chemical that can be produced from biomass. While a number of organisms are capable of succinate production naturally, this review focuses on the engineering of Escherichia coli for production of the four-carbon dicarboxylic acid. Important features of a succinate production system are to achieve optimal balance of reducing equivalents generated by consumption of the feedstock, while maximizing the amount of carbon that is channeled to the product. Aerobic and anaerobic production strains have been developed and applied to production from glucose as well as other abundant carbon sources. Metabolic engineering methods and strain evolution have been used and supplemented by the recent application of systems biology and in silico modeling tools to construct optimal production strains. The metabolic capacity of the production strain, as well as the requirement for efficient recovery of succinate and the reliability of the performance under scale-up are important in the overall process. The costs of the overall biorefinery compatible process will determine the economical commercialization of succinate and its impact in larger chemical markets.

Thakker, Chandresh; Martinez, Irene; San, Ka-Yiu; Bennett, George N.

2012-01-01

34

Clinical Implications of Enteroadherent Escherichia coli  

PubMed Central

Pathogenic Escherichia coli that colonize the small intestine primarily cause gastrointestinal illness in infants and travelers. The main categories of pathogenic E. coli that colonize the epithelial lining of the small intestine are enterotoxigenic E. coli enteropathogenic E. coli and enteroaggregative E. coli. These organisms accomplish their pathogenic process by a complex, coordinated multistage strategy, including non-intimate adherence mediated by various adhesins. These so called “enteroadherent E. coli ” categories subsequently produced toxins or effector proteins that are either secreted to the milieu or injected to the host cell. Finally, destruction of the intestinal microvilli results from the intimate adherence or the toxic effect exerted over the epithelia, resulting in water secretion and diarrhea. In this review, we summarize the current state of knowledge regarding these enteroadherent E. coli strains and the present clinical understanding of how these organisms colonize the human intestine and cause disease.

Arenas-Hernandez, Margarita M.P.; Martinez-Laguna, Ygnacio; Torres, Alfredo G.

2012-01-01

35

Infection strategies of enteric pathogenic Escherichia coli  

PubMed Central

Enteric Escherichia coli (E. coli) are both natural flora of humans and important pathogens causing significant morbidity and mortality worldwide. Traditionally enteric E. coli have been divided into 6 pathotypes, with further pathotypes often proposed. In this review we suggest expansion of the enteric E. coli into 8 pathotypes to include the emerging pathotypes of adherent invasive E. coli (AIEC) and Shiga-toxin producing enteroaggregative E. coli (STEAEC). The molecular mechanisms that allow enteric E. coli to colonize and cause disease in the human host are examined and for two of the pathotypes that express a type 3 secretion system (T3SS) we discuss the complex interplay between translocated effectors and manipulation of host cell signaling pathways that occurs during infection.

Clements, Abigail; Young, Joanna C.; Constantinou, Nicholas; Frankel, Gad

2012-01-01

36

Stability of Ribosomes from Streptomycin-Exposed Escherichia Coli.  

National Technical Information Service (NTIS)

Exposure of Escherichia coli to streptomycin resulted in a marked stabilization of their ribosomes to heat; ribosomes of streptomycin-resistant Escherichia coli were only stabilized slightly. Phenotypic expression of bacterial sensitivity or resistance to...

A. D. Wolfe F. E. Hahn

1968-01-01

37

Membrane filter method for enumerating Escherichia coli.  

PubMed Central

A membrane filter procedure for enumerating Escherichia coli was developed and evaluated. The method quantifies E. coli within 24 h without requiring subculture and identification of isolates. It incorporates a primary selective-differential medium for gram-negative, lactose-fermenting bacteria; resuscitation of weakened organisms by incubation for 2 h at 35 degrees C before incubation at 44.5 degrees C for 18 to 22 h; and an in situ urease test to differentiate E. coli from other thermotolerant, lactose-positive organisms. The recovery of E. coli from marine, estuarine, and freshwater samples exceeded 90%. Of the presumptively positive colonies, 91% were verified as E. coli. Less than 1% of all of the verified E. coli colonies failed to react typically.

Dufour, A P; Strickland, E R; Cabelli, V J

1981-01-01

38

Post-irradiation Recovery of Escherichia coli  

Microsoft Academic Search

RADIATION sensitivity of Escherichia coli strains is influenced by conditions for growth prior to and after radiation exposure. Stapleton and Engel1 have shown that E. coli B\\/r (CSH) grown in a buffered-peptone medium developed higher X-ray resistance. The cells grown in rich medium, however, might have become more exacting in their nutritional requirements and their recovery was limited on basal

J. S. Lee; R. O. Sinnhuber

1965-01-01

39

Molecular Archaeology of the Escherichia coli Genome  

Microsoft Academic Search

The availability of the complete sequence of Escherichia coli strain MG1655 provides the first opportunity to assess the overall impact of horizontal genetic transfer on the evolution of bacterial genomes. We found that 755 of 4,288 ORFs (547.8 kb) have been introduced into the E. coli genome in at least 234 lateral transfer events since this species diverged from the

Jeffrey G. Lawrence; Howard Ochman

1998-01-01

40

Endogenous endophthalmitis caused by Escherichia coli.  

PubMed

Endophthalmitis is a rare complication of Escherichia coli-induced septicemia. Nine cases of endogenous endophthalmitis caused by E. coli have been reported previously, all except one in patients with diabetes. The most common primary site of infection is the urinary tract. The course of illness is rapidly progressive with a poor visual prognosis. Concurrent systemic morbidity, including body abscesses and endocarditis, is high. We report an additional case of endogenous endophthalmitis from E. coli in a diabetic woman. Enucleation was required despite aggressive topical and systemic treatment. The pertinent literature is reviewed. PMID:8460886

Park, S B; Searl, S S; Aquavella, J V; Erdey, R A

1993-03-01

41

Beta-alanine synthesis in Escherichia coli.  

PubMed Central

The enzyme, aspartate 1-decarboxylase (L-aspartate 1-carboxy-lyase; EC 4.1.1.15), that catalyzes the reaction aspartate leads to beta-alanine + CO2 was found in extracts of Escherichia coli. panD mutants of E. coli are defective in beta-alanine biosynthesis and lack aspartate 1-decarboxylase. Therefore, the enzyme functions in the biosynthesis of the beta-alanine moiety of pantothenate. The genetic lesion in these mutants is closely linked to the other pantothenate (pan) loci of E. coli K-12. Images

Cronan, J E

1980-01-01

42

Regulation of Alcohol Fermentation by Escherichia Coli.  

National Technical Information Service (NTIS)

The purpose of this project is to elucidate the way in which the fermentative synthesis of ethanol is regulated in the facultative anaerobe Escherichia coli. Focus is on the two final steps in alcohol synthesis, which are catalyzed by alcohol dehydrogenas...

D. P. Clark

1986-01-01

43

Enterotoxigenic Escherichia coli in veterinary medicine  

Microsoft Academic Search

Enterotoxigenic Escherichia coli (ETEC) infection is the most common type of colibacillosis of young animals (primarily pigs and calves), and it is a significant cause of diarrhoea among travellers and children in the developing world. The main virulence attributes of ETEC are adhesins and enterotoxins, which are mostly regulated on large plasmids. Almost all ETEC bacteria are known to adhere

Béla Nagy; Péter Zs. Fekete

2005-01-01

44

Leaner and meaner genomes in Escherichia coli  

PubMed Central

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.

Ussery, David W

2006-01-01

45

Engineering ethanologenic Escherichia coli for levoglucosan utilization  

Microsoft Academic Search

Levoglucosan is a major product of biomass pyrolysis. While this pyrolyzed biomass, also known as bio-oil, contains sugars that are an attractive fermentation substrate, commonly-used biocatalysts, such as Escherichia coli, lack the ability to metabolize this anhydrosugar. It has previously been shown that recombinant expression of the levoglucosan kinase enzyme enables use of levoglucosan as carbon and energy source. Here,

Donovan S. Layton; Avanthi Ajjarapu; Dong Won Choi; Laura R. Jarboe

2011-01-01

46

A possible osmodependent protease in Escherichia coli.  

PubMed

When a strain of Escherichia coli, expressing a hybrid protein GalK-beta-Gal, is shifted to high osmolarity, the beta-galactosidase activity strongly decreases within 20 min of shock. The loss of beta-galactosidase activity results from degradation of the hybrid protein under osmotic stress. The results raise the possibility that osmotic stress induces a specific osmodependent protease. PMID:8181701

Meury, J

1994-03-01

47

Investigation of 'Escherichia coli' Enterotoxins.  

National Technical Information Service (NTIS)

The results of the present investigation indicate a new approach to the development of a single vaccine formula which may ultimately be used to confer protection against both cholera and E. coli diarrheal disease in man and domestic animals. Fundamentally...

R. Rappaport

1978-01-01

48

Ecology of Intestinal Escherichia coli in Pigs  

PubMed Central

The coliflora of three groups of young pigs was shown to be dominated by a small number of Escherichia coli types, as determined by their O antigen, that maintained a tenure of several days or weeks. The pattern of successive waves of E. coli was similar in littermates but, in general, each pig harboured a unique sequence of E. coli types. The E. coli flora from a litter was also shown to be dominated by a small number of E. coli types whose tenure averaged several weeks. A limited amount of information indicated that an enteropathogenic strain of E. coli may occur in this sequence of events and thus appears to be influenced by the same factors as other E. coli strains. The coliflora of two sows appeared to be more complex than those of their progeny and did not seem to follow the same pattern of population change. The coliflora of young pigs differed from the coliflora of man in that there appeared to be no E. coli strains in pigs fitting the description of resident strains. Forty-two percent of all isolates were found to produce colicins and it appeared that this property was more commonly encountered in dominant strains of E. coli

Craven, J. A.; Barnum, D. A.

1971-01-01

49

Survival of Escherichia coli in stormwater biofilters.  

PubMed

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. PMID:24371007

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

2014-04-01

50

The Effects of Regulatory Proteins RcsA and RcsB on the Expression of the Vibrio fischeri lux Operon in Escherichia coli  

Microsoft Academic Search

A study was made of the effect of RcsA and RcsB on the Vibrio fischeri lux expression in Escherichia coli. RcsA suppressed the LuxR activity and thereby inhibited expression of the lux genes coding for luciferase and reductase. In osmotic shock, RcsA–RcsB activated lux expression and, consequently, the bioluminescence of E. coli cells in the early log phase.

G. B. Zavilgelsky; V. Yu. Kotova; I. V. Manukhov

2003-01-01

51

Serological Cross-Reactions between 'Escherichia coli' O157 and other Species of the Genus 'Escherichia'.  

National Technical Information Service (NTIS)

The antigenic relatedness of Escherichia coli O157 and four sorbitol-negative species of the genus Escherichia was examined. Isolates of Escherichia hermannii, E. fergusonii, E. vulneris, and E. blattae were tested in the tube agglutination assay by using...

E. W. Rice, E. G. Sowers, C. H. Johnson, M. E. Dunnigan, N. A. Strockbine

1992-01-01

52

FTIR nanobiosensors for Escherichia coli detection  

PubMed Central

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

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

2012-01-01

53

Studies of Escherichia coli Infection in Chickens  

PubMed Central

The pathogenesis of infection with Escherichia coli was studied in chickens using live O78:K80 cells and a heat-labile chick lethal toxin. The results obtained were compared with those observed in field outbreaks. The common histological findings of subepicardial edema and congestion, focal necrosis in the spleen and focal necrosis, congestion, edema and accumulation of fibrin in the liver support an active role for chick lethal toxin in the pathogenesis of E. coli disease. ImagesFig. 3.Fig. 4.Fig. 5.Fig. 6.Fig. 7.

Truscott, R. B.; Lopez-Alvarez, J.; Pettit, J. R.

1974-01-01

54

Shiga toxin-producing Escherichia coli (STEC).  

PubMed

Shiga toxin-producing Escherichia coli (STEC) are important enteric pathogens worldwide, causing diarrhea with or without blood visibly present and hemolytic uremic syndrome. STEC are unique among diarrheogenic E coli in producing Shiga toxin type 1 and type 2, the virulence factors responsible for bloody diarrhea and hemolytic uremic syndrome. Cattle and other ruminants are the natural reservoir of STEC as their normal intestinal flora. Humans become infected by consumption of foods contaminated with cattle feces. Early diagnosis of STEC infection is important because of the contraindication for treating STEC using antimicrobial agents, and the intense supportive care needed if renal failure occurs. PMID:20513540

Hunt, John M

2010-03-01

55

Hydrogen production by recombinant Escherichia coli strains  

PubMed Central

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

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

2012-01-01

56

Quorum sensing in Escherichia coli and Salmonella  

Microsoft Academic Search

Quorum sensing in Escherichia coli and Salmonella has been an elusive topic for a long time. However, in the past 8 years, several research groups have demonstrated that these bacteria use several quorum-sensing systems, such as: the luxS\\/AI-2, AI-3\\/epinephrine\\/norepinephrine, indole, and the LuxR homolog SdiA to achieve intercellular signaling. The majority of these signaling systems are involved in interspecies communication,

Matthew Walters; Vanessa Sperandio

2006-01-01

57

Atypical SARS and Escherichia coli Bacteremia  

PubMed Central

We describe a patient with severe acute respiratory syndrome (SARS) whose clinical symptoms were masked by Escherichia coli bacteremia. SARS developed in a cluster of healthcare workers who had contact with this patient. SARS was diagnosed when a chest infiltrate developed and when the patient’s brother was hospitalized with acute respiratory failure. We highlight problems in atypical cases and offer infection control suggestions.

Tan, Ban Hock; Kurup, Asok; Oon, Lynette Lin Ean; Heng, Derrick; Thoe, Su Yun Se; Bai, Xin Lai; Chan, Kwai Peng; Ling, Ai Ee

2004-01-01

58

ppGpp cycle in Escherichia coli  

Microsoft Academic Search

Kinetics of accumulation and degradation of ppGpp and pppGpp were analysed in spoT+ and spoT strains of Escherichia coli. The experimental data in this paper indicate that on degradation ppGpp is not converted to pppGpp but instead is converted to GDP which is in turn phosphorylated to GTP. In addition the data are consistent with the idea the pppGpp is

Csaba Kari; István Török; Andrew Travers

1977-01-01

59

Frequency-Dependent Escherichia coli Chemotaxis Behavior  

NASA Astrophysics Data System (ADS)

We study Escherichia coli chemotaxis behavior in environments with spatially and temporally varying attractant sources by developing a unique microfluidic system. Our measurements reveal a frequency-dependent chemotaxis behavior. At low frequency, the E. coli population oscillates in synchrony with the attractant. In contrast, in fast-changing environments, the population response becomes smaller and out of phase with the attractant waveform. These observations are inconsistent with the well-known Keller-Segel chemotaxis equation. A new continuum model is proposed to describe the population level behavior of E. coli chemotaxis based on the underlying pathway dynamics. With the inclusion of a finite adaptation time and an attractant consumption rate, our model successfully explains the microfluidic experiments at different stimulus frequencies.

Zhu, Xuejun; Si, Guangwei; Deng, Nianpei; Ouyang, Qi; Wu, Tailin; He, Zhuoran; Jiang, Lili; Luo, Chunxiong; Tu, Yuhai

2012-03-01

60

Cloning of Beneckea genes in Escherichia coli.  

PubMed

Genes from Beneckea harveyi, a luminescent marine bacterium, were cloned in Escherichia coli. This was done by producing randomly sheared fragments of Beneckea DNA and inserting them into the EcoRI site of plasmid pMB9 by the adenine-thymine joining procedure. The hybrid plasmids were used to transform E. coli C600 SF8. Among the transformants selected for tetracycline resistance, one clone that appeared to complement a leucine tb mutation was identified. The transformants were screened for the presence of Beneckea 5S genes. Four of these clones were analyzed in detail by hybridization with 16S, 23S, and 4S Beneckea RNA. The observations suggest that the ribosomal genes in Beneckea are linked, but are present in a different order than those in E. coli. PMID:338587

Lamfrom, H; Sarabhai, A; Abelson, J

1978-01-01

61

Thymineless Death in Escherichia coli: Strain Specificity  

PubMed Central

Thymineless death of various ultraviolet (UV)-sensitive strains of Escherichia coli B and K-12 was investigated. It was found that E. coli B, Bs?12, K-12 rec-21, and possibly K-12 Lon?, all sensitive to UV, were also sensitive to thymine starvation. However, other UV-sensitive strains of E. coli were found to display the typical resistant-type kinetics of thymineless death. The correlation of these results with various other cellular processes suggested that the filament-forming ability of the bacteria might be involved in the mechanism of thymineless death. It was apparent from the present results that capacity for host-cell reactivation, recombination ability, thymine dimer excision, and probably induction of a defective prophage had little to do with determining sensitivity to thymine deprivation. Images

Cummings, Donald J.; Mondale, Lee

1967-01-01

62

Invasive Disease Caused by Ciprofloxacin-Resistant Uropathogenic Escherichia coli  

Microsoft Academic Search

To evaluate the invasiveness of ciprofloxacin-resistant Escherichia coli isolated from the urinary tract, the susceptibility to ciprofloxacin of Escherichia coli strains from patients with invasive urinary tract infection was compared with that of isolates from patients with noninvasive\\u000a disease. In a 14-month period, 2054 different isolates of Escherichia coli were analyzed, of which 554 (27%) were resistant to ciprofloxacin. One

R. Blázquez; A. Menasalvas; I. Carpena; C. Ramírez; C. Guerrero; S. Moreno

1999-01-01

63

Biodegradation of Aromatic Compounds by Escherichia coli  

PubMed Central

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

Diaz, Eduardo; Ferrandez, Abel; Prieto, Maria A.; Garcia, Jose L.

2001-01-01

64

ENERGY OF MAINTENANCE IN ESCHERICHIA COLI  

PubMed Central

McGrew, Sarah B. (Pennsylvania State University, University Park) and M. F. Mallette. Energy of maintenance in Escherichia coli. J. Bacteriol. 83:844–850. 1962.—Relatively dense populations of Escherichia coli B in log phase were used to detect utilization of exogenous glucose for maintenance without growth. Turbidity at 400 m? was used as the measure of growth, since it should reflect changes in either cell number or size. A threshold level of glucose was observed below which turbidity did not change during short-time experiments. Repeated additions of glucose during prolonged incubation at 37 C either increased the turbidity slowly or maintained it, depending on the amount of glucose. Plate counts to follow viability showed slow decreases for 10 days, while the unfed controls lost viability quite rapidly. From these results it was concluded that E. coli specifically utilized exogenous glucose for maintenance, without growth. The conflict of this opinion with that of earlier workers is discussed and some implications suggested.

McGrew, Sarah B.; Mallette, M. F.

1962-01-01

65

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

EPA Science Inventory

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

66

Acid tolerance of enterohemorrhagic Escherichia coli.  

PubMed Central

Enterohemorrhagic Escherichia coli (EHEC) strains were tested for their ability to survive in acid pH at 37 degrees C. No loss of viability was observed in an O157:H7 EHEC strain (ATCC 43895) at pH levels of 3.0 and 2.5 for at least 5 h. The level of acid tolerance of most EHEC isolates was very high, similar to that of Shigella flexneri strains. The acid tolerance was dependent on the growth phase and pH of the growth medium.

Benjamin, M M; Datta, A R

1995-01-01

67

S-Nitrosylation Signaling in Escherichia coli  

NSDL National Science Digital Library

Most bacteria generate nitric oxide (NO) either aerobically by NO synthases or anaerobically from nitrite. Far from being a mere by-product of nitrate respiration, bacterial NO has diverse physiological roles. Many proteins undergo NO-mediated posttranslational modification (S-nitrosylation) in anaerobically grown Escherichia coli. The regulation of one such protein, OxyR, represents a redox signaling paradigm in which the same transcription factor controls different protective genes depending on its S-nitrosylation versus S-oxidation status. We discuss a structural model that may explain the remarkable stability and specificity of OxyR S-nitrosylation.

Ivan Gusarov (New York University School of Medicine;Department of Biochemistry and Molecular Pharmacology REV); Evgeny Nudler (New York University School of Medicine;Department of Biochemistry and Molecular Pharmacology REV)

2012-06-12

68

Engineering ethanologenic Escherichia coli for levoglucosan utilization.  

PubMed

Levoglucosan is a major product of biomass pyrolysis. While this pyrolyzed biomass, also known as bio-oil, contains sugars that are an attractive fermentation substrate, commonly-used biocatalysts, such as Escherichia coli, lack the ability to metabolize this anhydrosugar. It has previously been shown that recombinant expression of the levoglucosan kinase enzyme enables use of levoglucosan as carbon and energy source. Here, ethanologenic E. coli KO11 was engineered for levoglucosan utilization by recombinant expression of levoglucosan kinase from Lipomyces starkeyi. Our engineering strategy uses a codon-optimized gene that has been chromosomally integrated within the pyruvate to ethanol (PET) operon and does not require additional antibiotics or inducers. Not only does this engineered strain use levoglucosan as sole carbon source, but it also ferments levoglucosan to ethanol. This work demonstrates that existing biocatalysts can be easily modified for levoglucosan utilization. PMID:21719279

Layton, Donovan S; Ajjarapu, Avanthi; Choi, Dong Won; Jarboe, Laura R

2011-09-01

69

Engineering the Escherichia coli Fermentative Metabolism  

NASA Astrophysics Data System (ADS)

Fermentative metabolism constitutes a fundamental cellular capacity for industrial biocatalysis. Escherichia coli is an important microorganism in the field of metabolic engineering for its well-known molecular characteristics and its rapid growth. It can adapt to different growth conditions and is able to grow in the presence or absence of oxygen. Through the use of metabolic pathway engineering and bioprocessing techniques, it is possible to explore the fundamental cellular properties and to exploit its capacity to be applied as industrial biocatalysts to produce a wide array of chemicals. The objective of this chapter is to review the metabolic engineering efforts carried out with E. coli by manipulating the central carbon metabolism and fermentative pathways to obtain strains that produce metabolites with high titers, such as ethanol, alanine, lactate and succinate.

Orencio-Trejo, M.; Utrilla, J.; Fernández-Sandoval, M. T.; Huerta-Beristain, G.; Gosset, G.; Martinez, A.

70

Pathogenesis of adherent-invasive Escherichia coli.  

PubMed

The etiology of Crohn's disease (CD) is complex and involves both host susceptibility factors (i.e., the presence of particular genetic alleles) and environmental factors, including bacteria. In this regard, adherent-invasive Escherichia coli (AIEC), have recently emerged as an exciting potential etiological agent of CD. AIEC are distinguished from commensal strains of E. coli through their ability to adhere to and invade epithelial cells and replicate in macrophages. Recent molecular analyses have identified genes required for both invasion of epithelial cells and replication in the macrophage. However, these genetic studies, in combination with recent genome sequencing projects, have revealed that the pathogenesis of this group of bacteria cannot be explained by the presence of AIEC-specific genes. In this article, we review the role of AIEC as a pathobiont in the pathology of CD. We also describe the emerging link between AIEC and autophagy, and we propose a model for AIEC pathogenesis. PMID:24059919

Smith, Emma J; Thompson, Aoife P; O'Driscoll, Adam; Clarke, David J

2013-10-01

71

Escherichia coli growth under modeled reduced gravity  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

72

Pandemic lineages of extraintestinal pathogenic Escherichia coli.  

PubMed

Pathogenic Escherichia coli strains cause a wide variety of intestinal and extraintestinal infections. The widespread geographical clonal dissemination of intestinal pathogenic E. coli strains, such as E. coli O157:H7, is well recognized, and its spread is most often attributed to contaminated food products. On the other hand, the clonal dissemination of extraintestinal pathogenic E. coli (ExPEC) strains is also recognized, but the mechanism of their spread is not well explained. Here, I describe major pandemic clonal lineages of ExPEC based on multilocus sequence typing (MLST), and discuss possible reasons for their global dissemination. These lineages include sequence type (ST)131, ST393, ST69, ST95, and ST73, which are all associated with both community-onset and healthcare-associated infections, in particular urinary tract infections and bloodstream infections. As with many other types of drug-resistant Gram-negative and Gram-positive bacterial infections, drug-resistant ExPEC infections are recognized to be caused by a limited set of clonal lineages. However, reported observations on these major pandemic lineages suggest that the resistance phenotype is not necessarily the determinant of their clonal dissemination. Both epidemiological factors and their intrinsic biological 'fitness' are likely to contribute. An important public health and clinical concern is that pandemicity itself may be a determinant of progressive drug resistance acquisition by clonal lineages. New research is urgently needed to better understand the epidemiological and biological causes of ExPEC pandemicity. PMID:24766445

Riley, L W

2014-05-01

73

Escherichia coli mutants defective in dipeptidyl carboxypeptidase.  

PubMed Central

Two independent mutants of Escherichia coli deficient in dipeptidyl carboxypeptidase activity (Dep-) were isolated after mutagenesis with ethyl methanesulfonate. Mating experiments and introduction of specific episomes indicated that the responsible gene was located at approximately 27--31 min on the E. coli chromosome. The Dep- mutants differed from the parental strain in their inability to grow with N-acetylalanylalanylalanine as the sole nitrogen source. Revertants selected for growth on this substrate of the enzyme were found to have reacquired the activity. Enzyme activity was highly sensitive to inhibition by 1-(D-3-mercapto-2-methylpropanoyl)-L-proline (SQ 14225), a potent inhibitor of mammalian dipeptidyl carboxypeptidase (angiotensin-converting enzyme, peptidyl dipeptidase, EC 3.4.15.1). This compound also reduced the rate of growth of the wild type with N-acetylalanylalanylalanine but not with ammonium sulfate. A fraction of the enzyme was released into the medium by osmotic shock, indicating that its presence in the periplasmic space may account for growth with N-acetylated peptides that cannot be taken up by E. coli. In addition to providing information about the specific role of this exopeptidase in E. coli, the Dep- mutants may prove useful for delineating the regulation and cellular function of dipeptidyl carboxypeptidases in higher organisms.

Deutch, C E; Soffer, R L

1978-01-01

74

Diffuse adherence of enteropathogenic Escherichia coli strains.  

PubMed

For the identification and characterization of the factor(s) responsible for the diffuse adherence (DA) pattern of enteropathogenic Escherichia coli strains, E. coli strain 2787 isolated from a case of infantile diarrhoea was employed. A plasmid-derived 11-kb fragment was cloned into pBR322. The recombinant plasmid pIB6 was shown to confer the diffuse adherence phenotype on different E. coli K12 strains as well as pIB4, a plasmid with a 9.2-kb insert. The DNA fragment necessary for the expression of the DA phenotype could be reduced to 6.0 kb. Antiserum obtained against pIB4-encoded proteins recognized a surface-associated protein of about 100 kDa in Western blotting. The isolated 100-kDa protein was found to bind to HeLa cells. The antiserum against C600(pIB4) inhibits adherence of E. coli 2787 and C600(pIB6) to HeLa cells. For this reason, the protein is called adhesin involved in diffuse adherence (AIDA-I). PMID:2101469

Benz, I; Schmidt, M A

1990-01-01

75

Cell Shape Dynamics in Escherichia coli  

PubMed Central

Bacteria are the simplest living organisms. In particular, Escherichia coli has been extensively studied and it has become one of the standard model systems in microbiology. However, optical microscopy studies of single E. coli have been limited by its small size, ?1 × 3 ?m, not much larger than the optical resolution, ?0.25 ?m. As a result, not enough quantitative dynamical information on the life cycle of single E. coli is presently available. We suggest that, by careful analysis of images from phase contrast and fluorescence time-lapse microscopy, this limitation can be bypassed. For example, we show that applying this approach to monitoring morphogenesis in individual E. coli leads to a simple, quantitative description of this process. First, we find the time when the formation of the septum starts, ?c. It occurs much earlier than the time when the constriction can be directly observed by phase contrast. Second, we find that the growth law of single cells is more likely bilinear/trilinear than exponential. This is further supported by the relations that hold between the corresponding growth rates. These methods could be further extended to study the dynamics of cell components, e.g., the nucleoid and the Z-ring.

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

2008-01-01

76

DNA probe for detection of serogroup 0157 enterohemorrhagic Escherichia coli  

Microsoft Academic Search

To develop a probe for the detection of serogroup O157 enterohemorrhagic Escherichia coli (EHEC), plasmid DNA extracts from 16 E. coli strains that hybridized with the CVD419 probe were screened for restriction fragments present in plasmids of serogroup O157 E. coli strains, but not in plasmids of non-O157 E. coli strains. Using a single O157:H7 E. coli strain (6391), 10

Leslie G. Huck; C. Richard Dorn; Elisabeth J. Angrick

1995-01-01

77

In vivo bioluminescence imaging of the murine pathogen Citrobacter rodentium.  

PubMed

Citrobacter rodentium is a natural mouse pathogen related to enteropathogenic and enterohemorrhagic Escherichia coli. We have previously utilized bioluminescence imaging (BLI) to determine the in vivo colonization dynamics of C. rodentium. However, due to the oxygen requirement of the bioluminescence system and the colonic localization of C. rodentium, in vivo localization studies were performed using harvested organs. Here, we report the detection of bioluminescent C. rodentium and commensal E. coli during colonization of the gastrointestinal tract in intact living animals. Bioluminescence was dependent on intact blood circulation, suggesting that the colonic environment is not anaerobic but nanaerobic. In addition, BLI revealed that C. rodentium colonizes the rectum, a site previously unreported for this pathogen. PMID:16926434

Wiles, Siouxsie; Pickard, Karen M; Peng, Katian; MacDonald, Thomas T; Frankel, Gad

2006-09-01

78

Production of glycoprotein vaccines in Escherichia coli  

PubMed Central

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 towards cost-effective in vivo production of conjugate vaccines, which in future may be used for combating severe infectious diseases, particularly in developing countries.

2010-01-01

79

Regulation of alcohol fermentation by Escherichia coli  

SciTech Connect

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

Clark, D.P.

1990-01-01

80

Long term effects of Escherichia coli mastitis.  

PubMed

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 until return to normal (n?=?5), and 'long 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 1500?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. PMID:24906501

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

2014-07-01

81

Characterization of enteroaggregative Escherichia coli isolates.  

PubMed

Forty enteraggregative Escherichia coli (EAggEC) previously characterized by their ability to adhere to HEp-2 cells or/and their hybridization with the 1-kb EAggEC DNA probe were investigated for the presence of adherence factors and heat-stable enterotoxin (EAST1)-encoding genes. Only 45% of the isolates harbored the EAST1-encoding genes as detected by polymerase chain reaction. None of them hybridized with an AAF/II-encoding gene specific DNA probe and 35% (14/40) were positive in a PCR assay using primers specific for aggC, an accessory gene of the AAF/I-encoding operon. Cloning and sequence analysis of the aggA variant from one isolate, EAggEC 457, revealed 68.9% identity between its deduced amino acid sequence and those of the aggA product from the AAF/I-producing reference strain, E. coli 17.2. No major protein subunit was detected at the surface of EAggEC 457 compared to the bacterial surface extract of E. coli 17.2. PMID:10220881

Rich, C; Favre-Bonte, S; Sapena, F; Joly, B; Forestier, C

1999-04-01

82

STUDIES ON THE LACTASE OF ESCHERICHIA COLI  

PubMed Central

A "lactase solution" was prepared from Escherichia coli. The mechanism of its action has been studied and changes in the rate of hydrolysis under various conditions investigated. The hydrolysis of lactose by the enzyme approximates the course of reaction of the integrated Michaelis-Menten equation. One molecule of enzyme combines with one molecule of substrate. E. coli lactase is readily inactivated at pH 5.0, and its optimal activity at 36°C. is reached between pH 7.0 and pH 7.5. The optimal temperature for its action was found to be 46°C. when determinations were carried out after an incubation period of 30 minutes. Its inactivation by heat follows the course of a first order reaction, and the critical thermal increment between the temperatures of 45°C. and 53°C. was calculated to be 56,400 calories per mol. The enzyme is activated by potassium cyanide, sodium sulfide, and cysteine, and irreversibly inactivated by mercuric chloride, silver nitrate, and iodine. After inactivation with copper sulfate partial reactivation is possible, while the slight inhibition brought about by hydrogen peroxide is completely reversible. The possible structure of the active groups of E. coli lactase as compared with other enzymes has been discussed.

Knopfmacher, H. P.; Salle, A. J.

1941-01-01

83

Molecular Evolutionary Relationships of Enteroinvasive Escherichia coli and Shigella spp  

Microsoft Academic Search

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

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

2004-01-01

84

Differentiation in virulence patterns of Escherichia coli possessing eae genes  

Microsoft Academic Search

In this study 98 Escherichia coli strains which belonged to traditional enteropathogenic (EPEC) serotypes and 82 enterohemorrhagic E. coli (EHEC) strains were screened by polymerase chain reaction (PCR) for the presence of E. coli -attaching and -effacing (eae) genes. These strains were also hybridized with the enteropathogenic adherence factor (EAF) probe and examined in the fluorescence actin staining (FAS) test.

Herbert Schmidt; Barbara Plaschke; Sylvia Franke; Holger Riissmann; Andreas Schwarzkopf; Jiirgen Heesemann; Helge Karch

1994-01-01

85

Antimicrobial activity of Nutmeg against Escherichia coli O157  

Microsoft Academic Search

We examined the difference between Escherichia coli O157 and non-pathogenic E. coli in their tolerance to spices. Various spices (5 g each) were homogenized at 25°C for 10 min with 5 ml of 70% ethyl alcohol, and the supernatant solutions obtained by centrifugation were used as spice extracts. When the E. coli strains were incubated with each spice extract at

Akiko Takikawa; Keiko Abe; Makiko Yamamoto; Shoko Ishimaru; Mari Yasui; Yoko Okubo; Kumio Yokoigawa

2002-01-01

86

Changing faecal population of escherichia coli in hospital medical patients  

PubMed Central

Specimens of faeces were obtained at weekly intervals for one year from patients in a female medical ward and Escherichia coli present were typed. The faecal E. coli population of the patients was constantly changing. No serotypes of E. coli were dominant, but on 31 occasions during the year small clusters of patients carried the same type.

Cooke, E. Mary; Ewins, Susan; Shooter, R. A.

1969-01-01

87

Vibrio parahaemolyticus, enterotoxigenic Escherichia coli, enterohemorrhagic Escherichia coli and Vibrio cholerae  

PubMed Central

This review highlighted the following: (i) pathogenic mechanism of the thermostable direct hemolysin produced by Vibrio parahaemolyticus, especially on its cardiotoxicity, (ii) heat-labile and heat-stable enterotoxins produced by enterotoxigenic Escherichia coli, especially structure–activity relationship of heat-stable enterotoxin, (iii) RNA N-glycosidase activity of Vero toxins (VT1 and VT2) produced by enterohemorrhagic Escherichia coli O157:H7, (iv) discovery of Vibrio cholerae O139, (v) isolation of new variant of Vibrio cholerae O1 El Tor that carries classical ctxB, and production of high concentration of cholera toxin by these strains, and (vi) conversion of viable but nonculturable (VBNC) Vibrio cholerae to culturable state by co-culture with eukaryotic cells.

TAKEDA, Yoshifumi

2011-01-01

88

Escherichia coli malate dehydrogenase, a novel solubility enhancer for heterologous proteins synthesized in Escherichia coli  

Microsoft Academic Search

Using 2-dimensional gel electrophoresis, the Escherichia coli proteome response to a heat-shock stress was analyzed and a 1.6-fold increase of malate dehydrogenase was observed even under\\u000a the heat-shock condition where the total number of soluble proteins decreased by about 5%. We subsequently demonstrated that,\\u000a as an N-terminus fusion expression partner, malate dehydrogenase facilitated the folding of, and dramatically increased the

Jin-Seung Park; Kyung-Yeon Han; Jong-Am Song; Keum-Young Ahn; Hyuk-Seong Seo; Jeewon Lee

2007-01-01

89

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

PubMed

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

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

2014-08-01

90

Deg phenotype of Escherichia coli lon mutants.  

PubMed Central

Deg. one of the Escherichia coli systems for degrading abnormal polypeptides (e.g., nonsense fragments), is also involved in the degradation of some classes of missense proteins. Both missense proteins of beta-galactosidase and temperature-sensitive phage products appear to be degraded by the Deg system. Mutations in the Deg system are indistinguishable from mutations classically called lon or capR; all map near proC, all are mucoid, defective in protein degradation, sensitive to radiomimetic agents, and defective in P1 lysogenization. All are able to propagate temperature-sensitive phage better than lon+ parental strains. Mutations that suppress the radiation sensitivity of these strains (sul) also suppress the P1 lysogenization defect, but do not affect mucoidy or the degradation defect.

Gottesman, S; Zipser, D

1978-01-01

91

Escherichia coli evolution during stationary phase.  

PubMed

The process of evolution by natural selection has been known for a century and a half, yet the mechanics of selection are still poorly understood. In most cases where natural selection has been studied, the genetic and physiological bases of fitness variation that result in population changes were not identified, leaving only a partial understanding of selection. Starved cultures of the bacterium Escherichia coli present a model system with which to address the genetic and physiological bases of natural selection. This is a model system that also reflects the prevalent state of bacteria in the natural world; due to intense competition for nutrients, microorganisms spend the majority of their lives under starvation conditions. Genetic analyses of a single survivor of starvation identified four adaptive mutations(1). Investigation of these mutations has revealed insights into the molecular and physiological bases of evolution during prolonged starvation stress. PMID:15207864

Zinser, Erik R; Kolter, Roberto

2004-06-01

92

Escherichia coli fliAZY operon.  

PubMed Central

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 are not required for motility but may regulate sigma F activity, perhaps in response to a putative cell density signal that may be detected by FliY, a member of the bacterial extracellular solute-binding protein family 3.

Mytelka, D S; Chamberlin, M J

1996-01-01

93

Eco Cyc: encyclopedia of Escherichia coli genes and metabolism  

Microsoft Academic Search

The encyclopedia of Escherichia coli genes andmetabolism (EcoCyc) is a database that combinesinformation about the genome and the intermediarymetabolism of E.coli. The database describes 3030genes of E.coli, 695 enzymes encoded by a subset ofthese genes, 595 metabolic reactions that occur inE.coli, and the organization of these reactions into 123metabolic pathways. The EcoCyc graphical user interfaceallows scientists to query and explore

Peter D. Karp; Monica Riley; Suzanne M. Paley; Alida Pellegrini-toole; Markus Krummenacker

1999-01-01

94

EcoCyc: Encyclopedia of Escherichia coli genes and metabolism  

Microsoft Academic Search

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

Peter D. Karp; Monica Riley; Suzanne M. Paley; Alida Pellegrini-toole; Markus Krummenacker

1998-01-01

95

Surface expression of ?-transaminase in Escherichia coli.  

PubMed

Chiral amines are important for the chemical and pharmaceutical industries, and there is rapidly growing interest to use transaminases for their synthesis. Since the cost of the enzyme is an important factor for process economy, the use of whole-cell biocatalysts is attractive, since expensive purification and immobilization steps can be avoided. Display of the protein on the cell surface provides a possible way to reduce the mass transfer limitations of such biocatalysts. However, transaminases need to dimerize in order to become active, and furthermore, they require the cofactor pyridoxal phosphate; consequently, successful transaminase surface expression has not been reported thus far. In this work, we produced an Arthrobacter citreus ?-transaminase in Escherichia coli using a surface display vector based on the autotransporter adhesin involved in diffuse adherence (AIDA-I), which has previously been used for display of dimeric proteins. The correct localization of the transaminase in the E. coli outer membrane and its orientation toward the cell exterior were verified. Furthermore, transaminase activity was detected exclusively in the outer membrane protein fraction, showing that successful dimerization had occurred. The transaminase was found to be present in both full-length and proteolytically degraded forms. The removal of this proteolysis is considered to be the main obstacle to achieving sufficient whole-cell transaminase activity. PMID:24487538

Gustavsson, Martin; Muraleedharan, Madhu Nair; Larsson, Gen

2014-04-01

96

Rates of transposition in Escherichia coli.  

PubMed

The evolutionary role of transposable elements (TEs) is still highly controversial. Two key parameters, the transposition rate (u and w, for replicative and non-replicative transposition) and the excision rate (e) are fundamental to understanding their evolution and maintenance in populations. We have estimated u, w and e for six families of TEs (including eight members: IS1, IS2, IS3, IS4, IS5, IS30, IS150 and IS186) in Escherichia coli, using a mutation accumulation (MA) experiment. In this experiment, mutations accumulate essentially at the rate at which they appear, during a period of 80 500 (1610 generations × 50 lines) generations, and spontaneous transposition events can be detected. This differs from other experiments in which insertions accumulated under strong selective pressure or over a limited genomic target. We therefore provide new estimates for the spontaneous rates of transposition and excision in E. coli. We observed 25 transposition and three excision events in 50 MA lines, leading to overall rate estimates of u ? 1.15 × 10(-5), w ? 4 × 10(-8) and e ? 1.08 × 10(-6) (per element, per generation). Furthermore, extensive variation between elements was found, consistent with previous knowledge of the mechanisms and regulation of transposition for the different elements. PMID:24307531

Sousa, Ana; Bourgard, Catarina; Wahl, Lindi M; Gordo, Isabel

2013-12-23

97

Isobutanol production from cellobiose in Escherichia coli.  

PubMed

Converting lignocellulosics into biofuels remains a promising route for biofuel production. To facilitate strain development for specificity and productivity of cellulosic biofuel production, a user friendly Escherichia coli host was engineered to produce isobutanol, a drop-in biofuel candidate, from cellobiose. A beta-glucosidase was expressed extracellularly by either excretion into the media, or anchoring to the cell membrane. The excretion system allowed for E. coli to grow with cellobiose as a sole carbon source at rates comparable to those with glucose. The system was then combined with isobutanol production genes in three different configurations to determine whether gene arrangement affected isobutanol production. The most productive strain converted cellobiose to isobutanol in titers of 7.64?±?0.19 g/L with a productivity of 0.16 g/L/h. These results demonstrate that efficient cellobiose degradation and isobutanol production can be achieved by a single organism, and provide insight for optimization of strains for future use in a consolidated bioprocessing system for renewable production of isobutanol. PMID:24430208

Desai, Shuchi H; Rabinovitch-Deere, Christine A; Tashiro, Yohei; Atsumi, Shota

2014-04-01

98

Expanding ester biosynthesis in Escherichia coli.  

PubMed

To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l(-1)). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters. PMID:24609358

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

2014-04-01

99

Selection of recently isolated colicinogenic Escherichia coli strains inhibitory to Escherichia coli O157:H7.  

PubMed

Escherichia coli strains were screened for their ability to inhibit E. coli O157:H7. An initial evaluation of 18 strains carrying previously characterized colicins determined that only colicin E7 inhibited all of the E. coli O157:H7 strains tested. A total of 540 strains that had recently been isolated from humans and nine different animal species (cats, cattle, chickens, deer, dogs, ducks, horses, pigs, and sheep) were tested by a flip-plating technique. Approximately 38% of these strains were found to inhibit noncolicinogenic E. coli K12 strains. The percentage of potentially colicinogenic E. coli per animal species ranged from 14% for horse isolates to 64% for sheep strains. Those isolates that inhibited E. coli K12 were screened against E. coli O157:H7, and 42 strains were found to be capable of inhibiting all 22 pathogenic strains tested. None of these 42 strains produced bacteriophages, and only 24 isolates inhibited serotype O157:H7 in liquid culture. The inhibitory activity of these strains was completely eliminated by treatment with proteinase K. When mixtures of these 24 colicinogenic strains were grown in anaerobic continuous culture, the four-strain E. coli O157:H7 population was reduced at a rate of 0.25 log10 cells per ml per h, which was fivefold faster than the washout rate. Two strains originally isolated from cat feces (F16) and human feces (H30) were identified by repetitive sequences polymerase chain reaction as the predominant isolates in continuous cultures. The results of this work indicate that animal species other than cattle can be sources of anti-O157 colicinogenic strains, and these results also lead to the identification of at least two isolates that could potentially be used in preharvest control strategies. PMID:12233846

Schamberger, Gerry P; Diez-Gonzalez, Francisco

2002-09-01

100

Electron Microscopy of Chloramphenicol-Treated Escherichia Coli.  

National Technical Information Service (NTIS)

Thin sections of Escherichia coli were examined by electron microscopy at sequential intervals after addition and then removal of chloramphenicol. The first changes, occurring at 1 hr after exposure to the drug, were disappearance of the ribosomes and agg...

C. Morgan H. S. Rosenkranz H. S. Carr H. M. Rose

1967-01-01

101

TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI  

EPA Science Inventory

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

102

Prevention of Death in Escherichia Coli (ld100) Shock.  

National Technical Information Service (NTIS)

This study was designed to determine the efficacy of maintenance infusions of methylprednisolone sodium succinate and gentamicin sulfate in live Escherichia coli organism shock. Twenty-three conditioned dogs were anesthetized, instrumented aseptically, in...

L. B. Hinshaw B. K. Beller L. T. Archer D. J. Flournoy G. L. White

1979-01-01

103

Susceptibilities of Escherichia coli and Staphylococcus aureus to Aloe barbadensis.  

PubMed

The in vitro susceptibilities of Escherichia coli and Staphylococcus aureus were evaluated and the two organisms were susceptible to the inner gel of aloe barbadensis, though it was more effective against Staphylococcus aureus than Escherichia coli. The reduction for Aloe Vera (AV) needed to suppress the growth of the gram-positive bacterium was attributed to the structural differences between the two organisms. PMID:20085127

Shilpakala, S R; Prathiba, J; Malathi, R

2009-01-01

104

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

SciTech Connect

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

Guzzo, A.; Diorio, C.; DuBow, M.S. (McGill Univ., Montreal, Quebec (Canada))

1991-08-01

105

Distribution of the Escherichia coli Common Pilus among Diverse Strains of Human Enterotoxigenic E. coli  

Microsoft Academic Search

The Escherichia coli common pilus (ECP) is produced by commensal and pathogenic E. coli strains. This pilus is unrelated to any of the known colonization factors (CFs) of enterotoxigenic E. coli (ETEC). In this study, we investigated the distribution and production of ECP among a collection of 136 human CF-positive and CF-negative ETEC strains of different geographic origins. The major

Dana Blackburn; Amanda Husband; Zeus Saldana; Rania A. Nada; John Klena; Firdausi Qadri; Jorge A. Giron

2009-01-01

106

The Modular Organization of Protein Interactions in Escherichia coli  

Microsoft Academic Search

Escherichia coli serves as an excellent model for the study of fundamental cellular processes such as metabolism, signalling and gene expression. Understanding the function and organization of proteins within these processes is an important step towards a ‘systems’ view of E. coli. Integrating experimental and computational interaction data, we present a reliable network of 3,989 functional interactions between 1,941 E.

José M. Peregrín-Alvarez; Xuejian Xiong; Chong Su; John Parkinson

2009-01-01

107

Directed Evolution of Ionizing Radiation Resistance in Escherichia coli  

Microsoft Academic Search

We have generated extreme ionizing radiation resistance in a relatively sensitive bacterial species, Esche- richia coli, by directed evolution. Four populations of Escherichia coli K-12 were derived independently from strain MG1655, with each specifically adapted to survive exposure to high doses of ionizing radiation. D37 values for strains isolated from two of the populations approached that exhibited by Deinococcus radiodurans.

Dennis R. Harris; Steve V. Pollock; Elizabeth A. Wood; Reece J. Goiffon; Audrey J. Klingele; Eric L. Cabot; Wendy Schackwitz; Joel Martin; Julie Eggington; Timothy J. Durfee; Christina M. Middle; Jason E. Norton; Michael C. Popelars; Hao Li; Sarit A. Klugman; Lindsay L. Hamilton; Lukas B. Bane; Len A. Pennacchio; Thomas J. Albert; Nicole T. Perna; Michael M. Cox; John R. Battista

2009-01-01

108

Infant diarrhoea due to Escherichia coli 091 K? H7  

Microsoft Academic Search

A small outbreak of infective diarrhoea occurred among babies in hospital at Winchester, England. The causal agent was found to be a strain of Escherichia coli 091 K? H7 which was resistant to several antibiotics. Epidemic diarrhoea due to E. coli 091 has previously been reported from south Germany.

M. H. Hughes; J. L. Greaves; K. A. Bettelheim

1968-01-01

109

Existence of ?-methylnorleucine in recombinant hirudin produced by Escherichia coli  

Microsoft Academic Search

A gene encoding for hirudin, a potent thrombin inhibitor, was expressed in Escherichia coli, which is the most widely used host. When the recombinant hirudin analog, CX-397, was overproduced by E. coli (600 mg l?1) in the absence of nutrient amino acids in the culture medium, the presence of two derivatives in the final product was observed with extremely increased

Ryo Muramatsu; Toru Negishi; Tsutomu Mimoto; Akira Miura; Satoru Misawa; Hideya Hayashi

2002-01-01

110

New locus for exopolysaccharide overproduction in Escherichia coli K-12.  

PubMed Central

A new locus for exopolysaccharide overproduction in Escherichia coli K-12 was mapped by insertion mutagenesis. A 66% linkage to serA, which is located at 62 min on the E. coli K-12 linkage map, was shown by P1 transduction. The polysaccharide produced by the mutant was isolated and was shown to be similar to colanic acid.

Zinkewich-Peotti, K; Fraser, J M

1988-01-01

111

Pathotyping Escherichia coli by Using Miniaturized DNA Microarrays? †  

PubMed Central

The detection of virulence determinants harbored by pathogenic Escherichia coli is important for establishing the pathotype responsible for infection. A sensitive and specific miniaturized virulence microarray containing 60 oligonucleotide probes was developed. It detected six E. coli pathotypes and will be suitable in the future for high-throughput use.

Anjum, Muna F.; Mafura, Muriel; Slickers, Peter; Ballmer, Karin; Kuhnert, Peter; Woodward, Martin J.; Ehricht, Ralf

2007-01-01

112

Rapid glutamate decarboxylase assay for detection of Escherichia coli.  

PubMed Central

A rapid test procedure for the enzyme glutamate decarboxylase was developed for detection of Escherichia coli. The assay procedure was able to confirm the presence of E. coli in enteric broth cultures with 95% specificity for both pure cultures and environmental samples. The procedure was capable of detecting survivors among chlorine-exposed cells.

Rice, E W; Johnson, C H; Dunnigan, M E; Reasoner, D J

1993-01-01

113

Glucuronidase Activity Of Escherichia Coli Isolated From Chicken Carcasses  

PubMed Central

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

Martins Perin, Luana; Keizo Yamazi, Anderson; Mendonca Moraes, Paula; Coutinho Cossi, Marcus Vinicius; Sergio de Arruda Pinto, Paulo; Augusto Nero*, Luis

2010-01-01

114

Genes Involved in Copper Homeostasis in Escherichia coli  

PubMed Central

Recently, genes for two copper-responsive regulatory systems were identified in the Escherichia coli chromosome. In this report, data are presented that support a hypothesis that the putative multicopper oxidase CueO and the transenvelope transporter CusCFBA are involved in copper tolerance in E. coli.

Grass, Gregor; Rensing, Christopher

2001-01-01

115

Biocontrol of Escherichia coli O157  

PubMed Central

The effect of a bacteriophage cocktail (EcoShield™) that is specific against Escherichia coli O157:H7 was evaluated against a nalidixic acid-resistant enterohemorrhagic E. coli O157:H7 RM4407 (EHEC) strain on leafy greens stored under either (1) ambient air or (2) modified atmosphere (MA; 5% O2/35% CO2/60% N2). Pieces (~2 × 2 cm2) of leafy greens (lettuce and spinach) inoculated with 4.5 log CFU/cm2 EHEC were sprayed with EcoShield™ (6.5 log PFU/cm2). Samples were stored at 4 or 10°C for up to 15 d. On spinach, the level of EHEC declined by 2.38 and 2.49 log CFU/cm2 at 4 and 10°C, respectively, 30 min after phage application (p ? 0.05). EcoShield™ was also effective in reducing EHEC on the surface of green leaf lettuce stored at 4°C by 2.49 and 3.28 log units in 30 min and 2 h, respectively (p ? 0.05). At 4°C under atmospheric air, the phage cocktail significantly (p ? 0.05) lowered the EHEC counts in one day by 1.19, 3.21 and 3.25 log CFU/cm2 on spinach, green leaf and romaine lettuce, respectively compared with control (no bacteriophage) treatments. When stored under MA at 4°C, phages reduced (p ? 0.05) EHEC populations by 2.18, 3.50 and 3.13 log CFU/cm2, on spinach, green leaf and romaine lettuce. At 10°C, EHEC reductions under atmospheric air storage were 1.99, 3.90 and 3.99 log CFU/cm2 (p ? 0.05), while population reductions under MA were 3.08, 3.89 and 4.34 logs on spinach, green leaf and romaine lettuce, respectively, compared with controls (p ? 0.05). The results of this study showed that bacteriophages were effective in reducing the levels of E. coli O157:H7 on fresh leafy produce, and that the reduction was further improved when produce was stored under the MA conditions.

Boyacioglu, Olcay; Sharma, Manan; Sulakvelidze, Alexander; Goktepe, Ipek

2013-01-01

116

Characterization of pili associated with Escherichia coli O18ac.  

PubMed Central

A strain of Escherichia coli O18ac isolated from the stool sample of a patient with diarrhea was found to agglutinate human erythrocytes. From the results presented it is suggested that this hemagglutination is mediated by pili. Isolated pilus preparations agglutinated human erythrocytes, whereas pilus-negative mutants did not. The serological and chemical analyses indicate that the pili associated with E. coli O18ac are distinct from other types found with E. coli. Images Fig. 1 Fig. 2 Fig. 3

Wevers, P; Picken, R; Schmidt, G; Jann, B; Jann, K; Golecki, J R; Kist, M

1980-01-01

117

Dehydrogenation of Conjugated Cholic Acid by Escherichia coli  

Microsoft Academic Search

7?-Dehydrogenation of taurocholic acid and glycocholic acid by Escherichia coli (E. coli) was examined in aerobic and anaerobic culture conditions. Bile acids in the culture medium of E. coli were extracted, separated into free, glycine-conjugate and taurine- conjugate fractions by piperidinohydroxypropyl dextran gel column chromatography, hydrolyzed in alkali and analyzed by gas-liquid chromatography. Both conjugated cholic acids were dehydrogenated to

Rie Katayama; Yoshio Ogura; Nobuo Yamaga; Koji Kimura; Kiyohisa Uchida

2004-01-01

118

Detection of DNA damage by use of Escherichia coli carrying recA'::lux, uvrA'::lux, or alkA'::lux reporter plasmids.  

PubMed Central

Plasmids were constructed in which DNA damage-inducible promoters recA, uvrA, and alkA from Escherichia coli were fused to the Vibrio fischeri luxCDABE operon. Introduction of these plasmids into E. coli allowed the detection of a dose-dependent response to DNA-damaging agents, such as mitomycin and UV irradiation. Bioluminescence was measured in real time over extended periods. The fusion of the recA promoter to luxCDABE showed the most dramatic and sensitive responses. lexA dependence of the bioluminescent SOS response was demonstrated, confirming that this biosensor's reports were transmitted by the expected regulatory circuitry. Comparisons were made between luxCDABE and lacZ fusions to each promoter. It is suggested that the lux biosensors may have use in monitoring chemical, physical, and genotoxic agents as well as in further characterizing the mechanisms of DNA repair.

Vollmer, A C; Belkin, S; Smulski, D R; Van Dyk, T K; LaRossa, R A

1997-01-01

119

Energetics of glycylglycine transport in Escherichia coli.  

PubMed

The transport system for glycylglycine in Escherichia coli behaves like a shock-sensitive transport system. The initial rate of transport is reduced 85% by subjecting whole cells to osmotic shock, and glycylglycine is not transported by membrane vesicles. The energetics of transport was studied with strain ML 308-225 and its mutant DL-54, which is deficient in Ca(2+)- and Mg(2+)-stimulated adenosine 5'-triphosphatase (EC 3.6.1.3) activity. It is concluded that active transport of glycylglycine, like other shock-sensitive transport systems, has an obligatory requirement for phosphate bond energy, but not for respiration or the energized state of the membrane. The major evidence for this conclusion is as follows. (i) Uptake of glycylglycine is severely inhibited by arsenate. (ii) Oxidizable energy sources such as d-lactate, succinate, and ascorbate, which is mediated by N-methylphenazinium methylsulfate, cannot serve as energy sources for the transport of glycylglycine in DL-54, which lacks oxidative phosphorylation. (iii) When energy is supplied only from adenosine-5'-triphosphate produced by glycolysis (anaerobic transport assays with glucose as the energy source in DL-54), substantial uptake of glycylglycine is observed. (iv) When the Ca(2+)-Mg(2+)-adenosine triphosphatase activity is absent but substrate-level phosphorylations and electron transport are operating (glucose as the energy source in DL-54), transport of glycylglycine shows significant resistance to the uncouplers, dinitrophenol and carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. PMID:4278690

Cowell, J L

1974-10-01

120

Regulation of alcohol fermentation by Escherichia coli  

SciTech Connect

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

Clark, D.P.

1986-03-01

121

Purification and crystallization of Escherichia coli oligoribonuclease.  

PubMed

Oligoribonuclease (Orn) is an essential 3'-to-5' hydrolytic exoribonuclease which degrades short oligoribonucleotides to 5' mononucleotides. Escherichia coli Orn has been crystallized under several different conditions using ammonium sulfate, sodium citrate and sodium acetate as precipitants. Both native and selenomethionine-labeled oligoribonuclease (SeMet-Orn) can be crystallized at room temperature in 1.4-1.55 M sodium citrate. The SeMet-Orn crystals diffract to 2.2 A resolution and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 70.43, b = 72.87, c = 147.76 A, and two dimers in the asymmetric unit. When grown in the presence of manganese, a second crystal form (Mn-SeMet-Orn) was obtained containing a single dimer per asymmetric unit (P2(1)2(1)2(1); a = 63.74, b = 74.31, c = 74.19 A). Finally, a hexagonal crystal form was obtained using sodium acetate as a precipitant (a = 91.5, b = 91.5, c = 111.1 A). This crystal (Zn-ApUp-Orn) belongs to the P6(5) space group and has three oligoribonuclease molecules per asymmetric unit. PMID:15039570

Fiedler, Tristan J; Vincent, Helen A; Zuo, Yuhong; Gavrialov, Orit; Malhotra, Arun

2004-04-01

122

Mutagenesis in Escherichia coli lacking catalase.  

PubMed

Escherichia coli K-12 strains completely lacking catalase activity due to mutations in katG, katE, and katF genes were constructed in order to assess the role of hydrogen peroxide in mutagenesis. Mutagenesis was monitored by selecting forward mutations to L-arabinose resistance. Lethality was measured at experimental conditions equivalent to those of the mutant yield by using a mixed culture of pairs of isogenic strains distinguished by their differential nutritional requirements. Deficiency in katG, katE, and katF genes leads to an enhanced spontaneous mutation rate as well as an enhanced sensitivity to both the lethal and mutagenic effects of hydrogen peroxide or an H2O2-generating mixture of compounds, such as coffee. To compare further the responses of the catalase-deficient bacteria to those of catalase-proficient counterparts, other genotoxins were analyzed. Both catalase-deficient and catalase-proficient strains were equally mutated by MMS, 4-NQO, and ultraviolet light. It is concluded that the bacterial strains and the mutagenicity tests described in the paper represent a useful tool to study the role of H2O2 in mutagenesis. PMID:2192882

Abril, N; Pueyo, C

1990-01-01

123

Oligosaccharide Binding in Escherichia coli Glycogen Synthase  

SciTech Connect

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

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

2010-11-17

124

Control ofPyridoxine Biosynthesis inEscherichia coli  

Microsoft Academic Search

DEMPSEY,WALTERB.(Uniiversity ofFlorida, Gainesville). Controlofpyridoxine biosynthesis inEscherichia coli. J.Bacteriol. 90:431-437. 1965.-The total pyridoxine in a culture ofexponentially growing Escherichia coli was 3.6X 10-10 molespermg ofdry cells. One-fourth ofthistotal was present inthemedium, andwas atleast 90%pyridoxal 5'-phosphate. Bothpyridoxol andpyridoxal, whenpresent initially at6X 10-7M, substituted entirely fordenovo synthesis ofpyridoxine. Theotherfourformsofthe pyridoxine group were ineffective atthisconcentration. Pyridoxine biosynthesis in exponentially growing cultures ofE.coli was immediately

WALTER B. DEMPSEY

1965-01-01

125

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

Federal Register 2010, 2011, 2012, 2013

...STEC) Escherichia coli (E. coli). The document also...steaks and roasts, for E. coli serogroups O26, O45...entering commerce. Like E. coli O157:H7, these serogroups...for Disease Control and Prevention also identifies...

2011-11-23

126

The function of ubiquinone in Escherichia coli  

PubMed Central

1. The function of ubiquinone in Escherichia coli was studied by using whole cells and membrane preparations of normal E. coli and of a mutant lacking ubiquinone. 2. The mutant lacking ubiquinone, strain AN59 (Ubi?), when grown under aerobic conditions, gave an anaerobic type of growth yield and produced large quantities of lactic acid, indicating that ubiquinone plays a vital role in electron transport. 3. NADH and lactate oxidase activities in membranes from strain AN59 (Ubi?) were greatly impaired and activity was restored by the addition of ubiquinone (Q-1). 4. Comparison of the percentage reduction of flavin, cytochrome b1 and cytochrome a2 in the aerobic steady state in membranes from the normal strain (AN62) and strain AN59 (Ubi?) and the effect of respiratory inhibitors on these percentages in membranes from strain AN62 suggest that ubiquinone functions at more than one site in the electron-transport chain. 5. Membranes from strain AN62, in the absence of substrate, showed an electron-spin-resonance signal attributed to ubisemiquinone. The amount of reduced ubiquinone (50%) found after rapid solvent extraction is consistent with the existence of ubiquinone in membranes as a stabilized ubisemiquinone. 6. The effects of piericidin A on membranes from strain AN62 suggest that this inhibitor acts at the ubiquinone sites: thus inhibition of electron transport is reversed by ubiquinone (Q-1); the aerobic steady-state oxidation–reduction levels of flavins and cytochrome b1 in the presence of the inhibitor are raised to values approximating those found in the membranes of strain AN59 (Ubi?); the inhibitor rapidly eliminates the electron-spin-resonance signal attributed to ubisemiquinone and allows slow oxidation of endogenous ubiquinol in the absence of substrate and prevents reduction of ubiquinone in the presence of substrate. It is concluded that piericidin A separates ubiquinone from the remainder of the electron-transport chain. 7. A scheme is proposed in which ubisemiquinone, complexed to an electron carrier, functions in at least two positions in the electron-transport sequence.

Cox, G. B.; Newton, N. A.; Gibson, F.; Snoswell, A. M.; Hamilton, J. A.

1970-01-01

127

Very slow growth of Escherichia coli.  

PubMed Central

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

Chesbro, W; Evans, T; Eifert, R

1979-01-01

128

Rapid Sterilization of Escherichia coli by Solution Plasma Process  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

129

A rapid procedure to purify Escherichia coli DNA topoisomerase I.  

PubMed

On the basis of the asymmetrical charge distribution of Escherichia coli DNA topoisomerase I, we developed a new procedure to purify E. coli DNA topoisomerase I in the milligram range. The new procedure includes using both cation- and anion-exchange columns, i.e., SP-Sepharose FF and Q-Sepharose FF columns. The E. coli DNA topoisomerase I purified here is free of DNase contamination. The kinetic constants of the DNA relaxation reaction of E. coli DNA topoisomerase I were also determined. PMID:21310243

Xu, Xiaozhou; Leng, Fenfei

2011-06-01

130

Intestinal Colonization by Enterotoxigenic Escherichia coli.  

National Technical Information Service (NTIS)

Intestinal colonization and adhesion by enterotoxigenic E. coli is mediated by specific types of pili. These pili are antigenic and can be used in diagnosing enterotoxigenic E. coli infections. They are also good protective antigens. When pregnant dams ar...

H. W . Moon

1980-01-01

131

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

SciTech Connect

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

Ben-Israel, O.; Ben-Israel, H.; Ulitzur, S. [Technion--Israel Inst. of Tech., Haifa (Israel). Dept. of Food Engineering and Biotechnology

1998-11-01

132

Intestinal Colonization by Enterotoxigenic 'Escherichia coli.'.  

National Technical Information Service (NTIS)

Growth of enterotoxigenic E. coli in porcine small intestine selects for piliated forms which adhere to the intestinal epithelium. Surface antigen K99 on enterotoxigenic E. coli is a pilus. Antigen K99 occurs on porcine enterotoxigenic E. coli strains and...

H. W. Moon

1976-01-01

133

Diarrheagenic Escherichia coli in Children from Costa Rica  

PubMed Central

More than 5,000 diarrheal cases per year receive medical care at the National Children's Hospital of Costa Rica, and nearly 5% of them require hospitalization. A total of 173 Escherichia coli strains isolated from children with diarrhea were characterized at the molecular, serologic, and phenotypic level. Multiplex and duplex polymerase chain reactions were used to detect the six categories of diarrheagenic E. coli. Thirty percent (n = 52) of the strains were positive, indicating a high prevalence among the pediatric population. Enteropathogenic E. coli and enteroinvasive E. coli pathotypes were the most prevalent (21% and 19%, respectively). Pathogenic strains were distributed among the four E. coli phylogenetic groups A, B1, B2, and D, with groups A and B1 the most commonly found. This study used molecular typing to evaluate the prevalence of diarrheagenic E. coli reported in Costa Rica and demonstrated the importance of these pathotypes in the pediatric population.

Perez, Cristian; Gomez-Duarte, Oscar G.; Arias, Maria L.

2010-01-01

134

Infection by verocytotoxin-producing Escherichia coli.  

PubMed Central

Verocytotoxin (VT)-producing Escherichia coli (VTEC) are a newly recognized group of enteric pathogens which are increasingly being recognized as common causes of diarrhea in some geographic settings. Outbreak studies indicate that most patients with VTEC infection develop mild uncomplicated diarrhea. However, a significant risk of two serious and potentially life-threatening complications, hemorrhagic colitis and the hemolytic uremic syndrome, makes VTEC infection a public health problem of serious concern. The main reservoirs of VTEC appear to be the intestinal tracts of animals, and foods of animal (especially bovine) origin are probably the principal sources for human infection. The term VT refers to a family of subunit exotoxins with high biological activity. Individual VTEC strains elaborate one or both of at least two serologically distinct, bacteriophage-mediated VTs (VT1 and VT2) which are closely related to Shiga toxin and are thus also referred to as Shiga-like toxins. The holotoxins bind to cells, via their B subunits, to a specific receptor which is probably the glycolipid, globotriosyl ceramide (Gb3). Binding is followed by internalization of the A subunit, which, after it is proteolytically nicked and reduced to the A1 fragment, inhibits protein synthesis in mammalian cells by inactivating 60S ribosomal subunits through selective structural modification of 28S ribosomal ribonucleic acid. The mechanism of VTEC diarrhea is still controversial, and the relative roles of locally acting VT and "attaching and effacing adherence" of VTEC to the mucosa have yet to be resolved. There is increasing evidence that hemolytic uremic syndrome and possibly hemorrhagic colitis result from the systemic action of VT on vascular endothelial cells. The role of antitoxic immunity in preventing the systemic complications of VTEC infection is being explored. Antibiotics appear to be contraindicated in the treatment of VTEC infection. The most common VTEC serotype associated with human disease is O157:H7, but over 50 different VT-positive O:H serotypes have now been identified. The best strategies for diagnosing human VTEC infection include testing for the presence of free VT in fecal filtrates and examining fecal cultures for VTEC by means of deoxyribonucleic acid probes that specify genes encoding VT1 and VT2. Both methods are currently confined to specialized laboratories and await commercial development for wider use. In the meantime, most laboratories should continue to screen for the most common human VTEC serotype, O157:H7, using a sorbitol-containing MacConkey medium. Images

Karmali, M A

1989-01-01

135

Pathogenomics of the Virulence Plasmids of Escherichia coli  

PubMed Central

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

Johnson, Timothy J.; Nolan, Lisa K.

2009-01-01

136

The Complete Genome Sequence of Escherichia coli K-12  

Microsoft Academic Search

The 4,639,221- base pair sequence of Escherichia coli K-12 is presented. Of 4288 protein-coding genes annotated, 38 percent have no attributed function. Comparison with five other sequenced microbes reveals ubiquitous as well as narrowly distributed gene families; many families of similar genes within E. coli are also evident. The largest family of paralogous proteins contains 80 ABC transporters. The genome

Frederick R. Blattner; Guy Plunkett III; Craig A. Bloch; Nicole T. Perna; Valerie Burland; Monica Riley; Julio Collado-Vides; Jeremy D. Glasner; Christopher K. Rode; George F. Mayhew; Jason Gregor; Nelson Wayne Davis; Heather A. Kirkpatrick; Michael A. Goeden; Debra J. Rose; Bob Mau; Ying Shao

2007-01-01

137

Azo dye decolorization with a mutant Escherichia coli strain  

Microsoft Academic Search

A recombinant Escherichia coli strain (E. coli NO3) containing genomic DNA fragments from azo-reducing wild-type Pseudomonas luteola strain decolorized a reactive azo dye (C.I. Reactive Red 22) at approx. 17 mg dye h-1 g cell. The ability to decolorize the azo dye probably did not originate from the plasmid DNA. Acclimation in azo-dye-containing media gave a nearly 10% increase in the decolorization rate of

Jo-Shu Chang; Tai-Shin Kuo; Yun-Peng Chao; Jin-Yen Ho; Ping-Jei Lin

2000-01-01

138

Major virulence factors of enterotoxigenic Escherichia coli in pigs  

Microsoft Academic Search

Enterotoxigenic Escherichia coli (ETEC) infection is the most common type of colibacillosis of young animals, and it is also a significant cause of food-\\u000a and waterborne E. coli-mediated human diarrhea worldwide. ETEC is a pathotype characterized by the production of adhesins that mediate bacterial\\u000a adherence to the intestinal epithelium and enterotoxins that interact with the intestine to cause diarrhea. In

Qiangde Duan; Fenghua Yao; Guoqiang Zhu

139

Indole Can Act as an Extracellular Signal in Escherichia coli  

Microsoft Academic Search

Previous work has shown that lacZ fusions to the cysK, astD, tnaB, and gabT genes in Escherichia coli are activated by self-produced extracellular signals. Using a combination of ethyl acetate extraction, reversed- phase C18 chromatography, and thin-layer chromatography, we have purified an extracellular activating signal from E. coli supernatants. Mass spectrometry revealed a molecule with an m\\/z peak of 117,

DANDAN WANG; XUEDONG DING

2001-01-01

140

Recombinational Construction in Escherichia coli of Infectious Adenoviral Genomes  

Microsoft Academic Search

A two-step gene replacement procedure was developed that generates infectious adenoviral genomes through homologous recombination in Escherichia coli. As a prerequisite, a human adenovirus serotype 5 (Ad5)-derived genome was first introduced as a PacI restriction fragment into an incP-derived replicon which, in contrast to ColE1-derivatives (e.g., pBR322 or pUC plasmids), is functional in a polA mutant of E. coli. Any

Joel Crouzet; Laurent Naudin; Cecile Orsini; Emmanuelle Vigne; Lucy Ferrero; Aude Le Roux; Patrick Benoit; Martine Latta; Christophe Torrent; Didier Branellec; Patrice Denefle; Jean-Francois Mayaux; Michel Perricaudet; Patrice Yeh

1997-01-01

141

DEFINITION OF ADDITIONAL FLAGELLAR GENES IN ESCHERICHIA COLI K12  

Microsoft Academic Search

Twentynine flagellar genes in Escherichia coli K12 have previously been assigned to three regions of the genome. Flagellar region I is located between pyrC and ptsG, region I1 between aroD and uvrC, and region I11 between uvrC and his. In this study, flagellar mutants in EscherLchia coli K12 were obtained by selection for resistance to the flagellotropic phage, x. They

YOSHIBUMI KOMEDA; KAZUHIRO KUTSUKAKE; TETSUO IINO

142

Characterization of a Second Lysine Decarboxylase Isolated from Escherichia coli  

Microsoft Academic Search

We report here on the existence of a new gene for lysine decarboxylase in Escherichia coli K-12. The hybridization experiments with a cadA probe at low stringency showed that the homologous region of cadA was located in l Kohara phage clone 6F5 at 4.7 min on the E. coli chromosome. We cloned the 5.0-kb HindIII fragment of this phage clone

YOSHIMI KIKUCHI; HIROYUKI KOJIMA; TAKASHI TANAKA; YUMIKO TAKATSUKA; YOSHIYUKI KAMIO

1997-01-01

143

Assembly of a Functional Immunoglobulin Fv Fragment in Escherichia coli  

Microsoft Academic Search

An expression system was developed that allows the production of a completely functional antigen-binding fragment of an antibody in Escherichia coli. The variable domains of the phosphorylcholine-binding antibody McPC603 were secreted together into the periplasmic space, where protein folding as well as heterodimer association occurred correctly. Thus, the assembly pathway for the Fv fragment in E. coli is similar to

Arne Skerra; Andreas Pluckthun

1988-01-01

144

Enhanced expression of CYP1B1 in Escherichia coli  

Microsoft Academic Search

Conditions for the optimal expression of the human CYP1B1 hemoprotein in Escherichia coli have been investigated. CYP1B1 cDNA was prepared from a retinal cDNA template and used to generate cDNA fragments with modified 5?-sequences reported to allow enhanced expression in E. coli DH5?. Plasmids were constructed, using the pCWori+ expression vector and were used to examine necessity for thiamine, ?-aminolevulinic

Ingela Jansson; Ivaylo Stoilov; Mansoor Sarfarazi; John B Schenkman

2000-01-01

145

In vitro antibacterial effect of yogurt on Escherichia coli  

Microsoft Academic Search

We investigated the bactericidal and bacteriostatic effects of yogurt on three strains ofEscherichia coli: human toxigenic (078:H11), rabbit pathogenic (RDEC-1) and rabbit nonpathogenic [015:K14(L):H4]. Approximately 106 organisms were incubated in yogurt, milk, broth, and modifications of these materials. Aliquots were removed at various intervals and plated on MacConkey's agar for enumeration ofE. coli. Yogurt was bactericidal (at least 5 log10

Catherine M. Kotz; Lance R. Peterson; Julia A. Moody; Dennis A. Savaiano; Michael D. Levitt

1990-01-01

146

A functional update of the Escherichia coli K-12 genome  

Microsoft Academic Search

BACKGROUND: Since the genome of Escherichia coli K-12 was initially annotated in 1997, additional functional information based on biological characterization and functions of sequence-similar proteins has become available. On the basis of this new information, an updated version of the annotated chromosome has been generated. RESULTS: The E. coli K-12 chromosome is currently represented by 4,401 genes encoding 116 RNAs

Margrethe H Serres; Shuba Gopal; Laila A Nahum; Ping Liang; Terry Gaasterland; Monica Riley

2001-01-01

147

Actividad antimicrobiana de mieles del sudeste de la provincia de Buenos Aires frente a Escherichia coli  

Microsoft Academic Search

Antimicrobial activity of honey against Escherichia coli. This study assessed the susceptibility of Escherichia coli to the antimicrobial activity of honeys by different techniques. Honeys used were from the southeast region of Buenos Aires province. In order to evaluate antimicrobial activity against Escherichia coli ATCC 25922, solutions containing 0, 1, 5, 10, 25 and 50% (w\\/v) of honey were prepared.

M. F. FANGIO; M. O. IURLINA; R. FRITZ

2007-01-01

148

Use of EC-MUG Media to Confirm Escherichia coli Contamination in Water Samples Protocol  

NSDL National Science Digital Library

Escherichia coli broth and Escherichia coli agar media with 4-methylumbelliferyl-Ã-D-glucuronide are used to confirm the presence of Escherichia coli in water samples. In this protocol, the history, procedure, and interpretation of results of this useful technique are discussed in detail.

American Society For Microbiology;

2010-08-23

149

Cloning, expression and bioinformatics analysis of ATP sulfurylase from Acidithiobacillus ferrooxidans ATCC 23270 in Escherichia coli  

PubMed Central

Molecular studies of enzymes involved in sulfite oxidation in Acidithiobacillus ferrooxidans have not yet been developed, especially in the ATP sulfurylase (ATPS) of these acidophilus tiobacilli that have importance in biomining. This enzyme synthesizes ATP and sulfate from adenosine phosphosulfate (APS) and pyrophosphate (PPi), final stage of the sulfite oxidation by these organisms in order to obtain energy. The atpS gene (1674 bp) encoding the ATPS from Acidithiobacillus ferrooxidans ATCC 23270 was amplified using PCR, cloned in the pET101-TOPO plasmid, sequenced and expressed in Escherichia coli obtaining a 63.5 kDa ATPS recombinant protein according to SDS-PAGE analysis. The bioinformatics and phylogenetic analyses determined that the ATPS from A. ferrooxidans presents ATP sulfurylase (ATS) and APS kinase (ASK) domains similar to ATPS of Aquifex aeolicus, probably of a more ancestral origin. Enzyme activity towards ATP formation was determined by quantification of ATP formed from E. coli cell extracts, using a bioluminescence assay based on light emission by the luciferase enzyme. Our results demonstrate that the recombinant ATP sulfurylase from A. ferrooxidans presents an enzymatic activity for the formation of ATP and sulfate, and possibly is a bifunctional enzyme due to its high homology to the ASK domain from A. aeolicus and true kinases.

Jaramillo, Michael L; Abanto, Michel; Quispe, Ruth L; Calderon, Julio; del Valle, Luis J; Talledo, Miguel; Ramirez, Pablo

2012-01-01

150

A combination of assays reveals biomass differences in biofilms formed by Escherichia coli mutants  

PubMed Central

Aims The aim of this study was to develop an assay system that can quantify the amount of biomass in biofilms formed by different isogenic mutants of an Escherichia coli K-12 strain. Methods and Results The reported assay, which is based on the BacTiter-Glo™ assay from Promega, uses bioluminescence to detect the intracellular concentration of ATP, which correlates with viable bacterial cell numbers. The quantitative data obtained with this ATP assay were compared to those obtained with the conventional crystal violet assay. As a qualitative control, scanning electron microscopy was performed. Conclusions The ATP assay, the crystal violet assay, and scanning electron microscopy yielded similar results for six of the eight strains tested. For the remaining two strains, the images from the scanning electron microscopy confirmed the results from the ATP assay. Significance and Impact of Study The ATP assay, in combination with other quantitative and qualitative assays, will allow us to perform genetic studies on the regulatory network that underlies the early steps in E. coli biofilm formation.

Sule, Preeti; Wadhawan, Tanush; Carr, Nathan J.; Horne, Shelley M.; Wolfe, Alan J.; Pru?, Birgit M.

2010-01-01

151

Sources of Escherichia coli in a coastal subtropical environment.  

PubMed

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

Solo-Gabriele, H M; Wolfert, M A; Desmarais, T R; Palmer, C J

2000-01-01

152

Sources of Escherichia coli in a Coastal Subtropical Environment  

PubMed Central

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

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

2000-01-01

153

Genetic engineering of ethanol production in Escherichia coli  

SciTech Connect

The genes encoding essential enzymes of the fermentative pathway for ethanol production in Zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into Escherichia coli under the control of a common promoter. Alcohol dehydrogenase II and pyruvate decarboxylase from Z. mobilis were expressed at high levels in E. coli, resulting in increased cell growth and the production of ethanol as the principal fermentation product from glucose. These results demonstrate that it is possible to change the fermentation products of an organism, such as E. coli, by the addition of genes encoding appropriate enzymes which form an alternative system for the regeneration of NAD/sup +/.

Ingram, L.O.; Conway, T.; Clark, D.P.; Sewell, G.W.; Preston, J.F.

1987-10-01

154

An integrated database to support research on Escherichia coli  

SciTech Connect

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

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

1992-01-01

155

Method 1103.1: Escherichia coli (E. coli) in Water by Membrane Filtration Using membrane-Thermotolerant Escherichia coli Agar (mTEC), April 2005.  

National Technical Information Service (NTIS)

Method 1103.1 describes a membrane filter (MF) procedure for the detection and enumeration of Escherichia coli bacteria in ambient water. E. coli is a common inhabitant of the intestinal tract of warm-blooded animals, and its presence in water samples is ...

2005-01-01

156

Genome Sequence of Enterotoxigenic Escherichia coli Strain B2C.  

PubMed

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

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

2014-01-01

157

Induction of radioresistance in Escherichia coli. [X radiation, uv radiation  

Microsoft Academic Search

The effect of prior treatment by inducing agents on the radioresistance of cells of Escherichia coli has been studied. In order to separate the induction process from the radiation-damage process, cells were first treated with inducing agents such as ultraviolet light, ionizing radiation, or nalidixic acid, allowed to become induced by incubation for 50 min and then given rifampin to

E. C. Pollard; P. M. Achey

1975-01-01

158

Growth Moderation in Slow-growing Mutants of Escherichia coli  

Microsoft Academic Search

SUMMARY Mutants of Escherichia coli were induced by U.V. light and selected by the criterion that they formed small colonies on a nutrient agar at normal temperature. Nine slow-growing mutant strains were isolated. These mutants were characterized and compared during exponential growth in a nutrient medium with respect to doubling time, average cell mass, and DNA and RNA contents. The

C. N. NEWMAN; R. C. BOCK RATH

1974-01-01

159

Transmembrane glutathione cycling in growing Escherichia coli cells  

Microsoft Academic Search

Glutathione (GSH) plays an important role in bacterial cells, participating in maintenance of redox balance in the cytoplasm and in defense against many toxic compounds and stresses. In this study we demonstrate that in aerobic, exponentially growing Escherichia coli culture endogenous reduced glutathione undergoes continuous transmembrane cycling between the cells and medium. As a result of an establishment of a

Galina Smirnova; Nadezda Muzyka; Oleg Oktyabrsky

160

Anaerobic Growth Yields of Aerobacter cloacae and Escherichia coli  

PubMed Central

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

Hernandez, Eovaldo; Johnson, Marvin J.

1967-01-01

161

TRIMETHOPRIM-SULFAMETHOXAZOLE RESISTANCE IN SEWAGE ISOLATES OF ESCHERICHIA COLI  

EPA Science Inventory

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

162

Escherichia coli O104:H4 Infections and International Travel  

PubMed Central

We analyzed travel-associated clinical isolates of Escherichia coli O104:H4, including 1 from the 2011 German outbreak and 1 from a patient who returned from the Philippines in 2010, by genome sequencing and optical mapping. Despite extensive genomic similarity between these strains, key differences included the distribution of toxin and antimicrobial drug–resistance determinants.

Alexander, David C.; Hao, Weilong; Gilmour, Matthew W.; Zittermann, Sandra; Sarabia, Alicia; Melano, Roberto G.; Peralta, Analyn; Lombos, Marina; Warren, Keisha; Amatnieks, Yuri; Virey, Evangeline; Ma, Jennifer H.; Jamieson, Frances B.; Low, Donald E.

2012-01-01

163

The acetolactate synthase isoenzymes of Escherichia coli K-12  

Microsoft Academic Search

Strains of Escherichia coli K-12 possessing only one of the three genes coding for acetolactate synthetase activity present either in the wild type or in its ilv0603 derivative were prepared and analyzed. Extracts prepared from these strains show different values of acetolactate synthase specific activity and different sensitivity to valine inhibition. These strains show a unique pattern of growth inhibition

John Guardiola; Maurilio De Felice; Alessandro Lamberti; Maurizio Iaccarino

1977-01-01

164

Model for Bacteriophage T4 Development in Escherichia coli  

Microsoft Academic Search

Mathematical relations for the number of mature T4 bacteriophages, both inside and after lysis of an Escherichia coli cell, as a function of time after infection by a single phage were obtained, with the following five parameters: delay time until the first T4 is completed inside the bacterium (eclipse period, n) and its standard deviation (s), the rate at which

AVINOAM RABINOVITCH; HILLA HADAS; MONICA EINAV; ZEEV MELAMED

1999-01-01

165

Septicaemia caused by cysteine-requiring isolates of Escherichia coli  

Microsoft Academic Search

Summary. The clinical and bacteriological findings in five cases of septicaemia with cysteine-requiring isolates of Escherichia coli are reported. Infections with these nutritionally-dependent organisms have been found previously in the urinary tract only, associated usually with chronic rather than acute conditions. The urinary tract was considered to be the source of the septicaemia in our patients and that site should

J. W. TAPSALL; C. J. McIVER

1986-01-01

166

Enteropathogenic Escherichia coli and life threatening chronic diarrhoea  

Microsoft Academic Search

Enteropathogenic Escherichia coli (EPEC) infection is not generally thought to cause severe diarrhoea after the neonatal period. Patients admitted to Queen Elizabeth Hospital for Children over the three years (1984-7) with diarrhoea and EPEC infection were reviewed. Clinical details, features of small intestinal mucosa, and treatment were recorded in those who developed chronic diarrhoea with failure to thrive. Twenty six

S M Hill; A D Phillips; J A Walker-Smith

1991-01-01

167

The Kinetics of the Mating Process in Escherichia coli  

Microsoft Academic Search

SUMMARY: When broth cultures of donor (HfrH) and recipient (F-) strains of Escherichia coli K-12 are mixed, zygotes are formed by the transfer of part of the donor chromosome to the recipient cell. The donor parent thus becomes dispensable as soon as transfer is accomplished. The kinetics of zygote formation can therefore be studied by treating samples, removed at intervals

W. HAYES

1957-01-01

168

Colonization factors of human enterotoxigenic Escherichia coli (ETEC)  

Microsoft Academic Search

Enterotoxigenic Escherichia coli (ETEC) is the most common cause of childhood and traveller's diarrhoea. The ability of ETEC to adhere to the intestinal epithelium of the host is an important virulence determinant, and adhesion is mediated by proteinaceous surface appendages called colonization factors.

Wim Gaastra; Ann-Mari Svennerholm

1996-01-01

169

rRNA transcription rate in Escherichia coli.  

PubMed Central

The rate of in vivo transcription elongation for Escherichia coli rRNA operons was determined by electron microscopy following addition of rifampin to log-phase cultures. Direct observation of RNA polymerase positions along rRNA operons 30, 40, and 70 s after inhibition of transcription initiation yielded a transcription elongation rate of 42 nucleotides per s. Images FIG. 1

Gotta, S L; Miller, O L; French, S L

1991-01-01

170

Enteropathogenic and Enterohemorrhagic Escherichia coli Infections: Translocation, Translocation, Translocation  

Microsoft Academic Search

Escherichia coli is the most abundant facultative anaerobic gram-negative bacterium of the intestinal microflora, naturally colonizing the mucous layer of the colon. A conserved core genomic structure is common to both commensal and patho- genic strains, providing the microorganisms with mechanisms required for survival under the competitive conditions in the gut, as well as the ability to spread among hosts

Junkal Garmendia; Gad Frankel; Valerie F. Crepin

2005-01-01

171

Catabolite repression in Escherichia coli mutants lacking cyclic AMP  

Microsoft Academic Search

The regulation of catabolite repression of ß-galactosidase has been studied in Escherichia coli mutants deleted for the adenyl cyclase gene (cya?), and thus unable to synthesize cyclic AMP. It has been found that, provided a second mutation occurs either in the crp gene coding for the catabolite gene activator protein (CAP) or in the Lactose region, these mutants exhibit catabolite

Alain Dessein; Maxime Schwartz; Agnès Ullmann

1978-01-01

172

Expression of active, human lysyl oxidase in Escherichia coli  

Microsoft Academic Search

Lysyl oxidase (LO) is a copper amine oxidase of the extracellular matrix which initiates covalent cross-linking in collagens and elastin. Human LO was expressed in Escherichia coli. At 37°C, large amounts of protein were obtained, but in the form of insoluble aggregates. Lowering the growth temperature, and reducing the amount of inducer, resulted in the production of soluble LO, which

M. Ouzzine; A. Boyd; D. J. S. Hulmes

1996-01-01

173

Pyrroloquinoline quinone, a chemotactic attractant for Escherichia coli.  

PubMed Central

Escherichia coli is attracted by pyrroloquinoline quinone (PQQ), and chemotaxis toward glucose is enhanced by the presence of PQQ. A ptsI mutant showed no chemotactic response to either glucose or PQQ alone but did show a chemotactic response to a mixture of glucose and PQQ. A strain lacking the methylated chemotaxis receptor protein Tar showed no response to PQQ.

de Jonge, R; Teixeira de Mattos, M J; Stock, J B; Neijssel, O M

1996-01-01

174

Virulence of Escherichia Coli Strains for Chick Embryos.  

National Technical Information Service (NTIS)

Fifty-three strains of Escherichia coli, freshly isolated from patients at Children's Hospital, Washington, D. C., were tested for virulence for 13-day chick embryos by allantoic inoculation of serial dilutions of viable cell suspensions. No clear-cut rel...

C. J. Powell R. A. Finkelstein

1965-01-01

175

Molecular basis of base substitution hotspots in Escherichia coli  

Microsoft Academic Search

In the lacI gene of Escherichia coli spontaneous base substitution hotspots occur at 5-methylcytosine residues. The hotspots disappear when the respective cytosines are not methylated. We suggest that the hotspots may result from the spontaneous deamination of 5-methylcytosine to thymine, which is not excised by the enzyme DNA-uracil glycosidase.

Christine Coulondre; Jeffrey H. Miller; Philip J. Farabaugh; Walter Gilbert

1978-01-01

176

In search of the minimal Escherichia coli genome  

Microsoft Academic Search

Recent plans announced for the systematic cataloging of the minimal Escherichia coli gene set, the pheno- types of all mutations, the expression levels of every transcript and gene product, and the interactions of all genetic loci or their gene products point the way towards a new frontier in the biology of model organ- isms. Powerful tools for this endeavor are

Darren J. Smalley; Marvin Whiteley; Tyrrell Conway

2002-01-01

177

Persistence of colicinogenic Escherichia coli in the mouse gastrointestinal tract  

Microsoft Academic Search

BACKGROUND: The ability of a bacterial strain to competitively exclude or displace other strains can be attributed to the production of narrow spectrum antimicrobials, the bacteriocins. In an attempt to evaluate the importance of bacteriocin production for Escherichia coli strain residence in the gastrointestinal tract, a murine model experimental evolution study was undertaken. RESULTS: Six colicin-producing, yet otherwise isogenic, E.

Osnat Gillor; Itamar Giladi; Margaret A Riley

2009-01-01

178

Alteration of Escherichia coli Topoisomerase IV to Novobiocin Resistance  

Microsoft Academic Search

DNA gyrase and topoisomerase IV (topo IV) are the two essential type II topoisomerases of Escherichia coli. Gyrase is responsible for maintaining negative supercoiling of the bacterial chromosome, whereas topo IV's primary role is in disentangling daughter chromosomes following DNA replication. Coumarins, such as novobiocin, are wide-spectrum antimicrobial agents that primarily interfere with DNA gyrase. In this work we designed

Christine D. Hardy; Nicholas R. Cozzarelli

2003-01-01

179

Enterotoxigenic Escherichia-coli-associated diarrheal disease in Apache children.  

PubMed

A search for intestinal enterotoxigenic Escherichia coli was made in 59 Apache children hospitalized with 64 episodes of acute diarrhea. Esch. coli isolates from acute-phase and convalescent-phase specimens of small-bowel fluid and stool were tested in three currently recognized models: the adult-rabbit ileal loop; infant rabbit; and the adrenal-cell assay. Enterotoxigenic strains were isolated from 10 children during acute diarrheal episodes (16 per cent); none were isolated from convalescent-phase specimens. None of 64 "enteropathogenic" serotypes of Esch. coli from 43 children with diarrhea, however, caused fluid production in the ileal-loop model. These results suggest that enterotoxigenic Esch. coli may be the cause of considerable diarrhea in this population and that the term "enteropathogenic" as applied to serotypes of Esch. coli needs to be redefined. PMID:1091855

Sack, R B; Hirschhorn, N; Brownlee, I; Cash, R A; Woodward, W E; Sack, D A

1975-05-15

180

Sex and virulence in Escherichia coli: an evolutionary perspective.  

PubMed

Pathogenic Escherichia coli cause over 160 million cases of dysentery and one million deaths per year, whereas non-pathogenic E. coli constitute part of the normal intestinal flora of healthy mammals and birds. The evolutionary pathways underlying this dichotomy in bacterial lifestyle were investigated by multilocus sequence typing of a global collection of isolates. Specific pathogen types [enterohaemorrhagic E. coli, enteropathogenic E. coli, enteroinvasive E. coli, K1 and Shigella] have arisen independently and repeatedly in several lineages, whereas other lineages contain only few pathogens. Rates of evolution have accelerated in pathogenic lineages, culminating in highly virulent organisms whose genomic contents are altered frequently by increased rates of homologous recombination; thus, the evolution of virulence is linked to bacterial sex. This long-term pattern of evolution was observed in genes distributed throughout the genome, and thereby is the likely result of episodic selection for strains that can escape the host immune response. PMID:16689791

Wirth, Thierry; Falush, Daniel; Lan, Ruiting; Colles, Frances; Mensa, Patience; Wieler, Lothar H; Karch, Helge; Reeves, Peter R; Maiden, Martin C J; Ochman, Howard; Achtman, Mark

2006-06-01

181

Degradation of Abnormal Proteins in 'Escherichia coli'.  

National Technical Information Service (NTIS)

Evidence is presented that E. coli contains a mechanism for selective degradation of abnormal proteins. Unfinished polypeptides containing puromycin, proteins containing frequent errors in translation, such as those synthesized by strains containing a ram...

A. L. Goldberg

1971-01-01

182

Use of DNA Probes and HEp-2 Cell Adherence Assay to Detect Diarrheagenic Escherichia coli. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Four major categories of Escherichia coli are recognized as causes of diarrheal disease, including enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroinvasive E. coli (EIEC), and enterohemorrhagic E. coli (EHEC); each category comprise...

M. M. Levine V. Prado R. Robins-Browne H. Lior J. B. Kaper

1988-01-01

183

Experimental Escherichia coli O157:H7 carriage in calves.  

PubMed Central

Nine weaned calves (6 to 8 weeks of age) were given 10(10) CFU of a five-strain mixture of enterohemorrhagic Escherichia coli O157:H7 by oral-gastric intubation. After an initial brief period of pyrexia in three calves and transient mild diarrhea in five calves, calves were clinically normal throughout the 13- to 27-day study. The population of E. coli O157:H7 in the faces decreased dramatically in all calves during the first 2 weeks after inoculation. Thereafter, small populations of E. coli O157:H7 persisted in all calves, where they were detected intermittently in the feces and rumen contents. While withholding food increased fecal shedding of E. coli O157:H7 by 1 to 2 log10/g in three of four calves previously shedding small populations of E. coli O157:H7, the effect of fasting on fecal shedding of E. coli O157:H7 was variable in calves shedding larger populations. At necropsy, E. coli O157:H7 was not isolated from sites outside the alimentary tract. E. coli O157:H7 was isolated from the forestomach or colon of all calves at necropsy. Greater numbers of E. coli O157:H7 were present in the gastrointestinal contents than in the corresponding mucosal sections, and there was no histologic or immunohistochemical evidence of E. coli O157:H7 adhering to the mucosa. In conclusion, under these experimental conditions, E. coli O157:H7 is not pathogenic in weaned calves, and while it does not appear to colonize mucosal surfaces for extended periods, E. coli O157:H7 persists in the contents of the rumen and colon as a source for fecal shedding.

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

1997-01-01

184

Lytic bacteriophages reduce Escherichia coli O157  

PubMed Central

The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm2) following exposure to 50 ?g/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm2). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p < 0.05) reduced E. coli O157:H7 populations after 24 h when stored at 4°C compared with controls. Immersion of lettuce in suspensions containing high concentrations of EcoShield™ (9.8 log PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm2) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm2) on day 0 compared with control treatments (4.10 log CFU/cm2). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce.

Ferguson, Sean; Roberts, Cheryl; Handy, Eric; Sharma, Manan

2013-01-01

185

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

Microsoft Academic Search

To explore new approaches of phage-based bio-process of specifically pathogenic Escherichia coli bacteria in food products within a short period. One hundred and forty highly lytic designed coliphages were used. Escherichia coli naturally contaminated and Enterohemorrhagic Escherichia coli experimentally inoculated samples of lettuce, cabbage, meat, and egg were used. In addition, experimentally produced biofilms\\u000a of E. coli were tested. A

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

186

Analysis of river water by bioluminescent biotests.  

PubMed

The bacterial bioluminescence has high sensitivity to the action of various inhibitors of biological activity. The lyophilized luminous bacteria Photobacterium phosphoreum (Microbiosensor B17 677F) and luminous strain Escherichia coli (Microbiosensor EC) from the Culture Collection IBSO were used to create bioluminescent biotests. They have been applied in ecological monitoring to determine the overall toxicity of the Yenisei and Angara Rivers and some water sources of Altai Territory. As a rule the heaviest pollution of water in studied rivers was registered near cities and settlements. The luminous bacteria biotests are simple and convenient in work, standardized and quantitative, have rapid response to actions of different substances and high sensitivity to environmental pollutants. It takes less than 30 min to do the biotest (the other biotests take 48--96 h). PMID:10512990

Kuznetsov, A M; Rodicheva, E K; Medvedeva, S E

1999-01-01

187

Multidimensional annotation of the Escherichia coli K-12 genome  

PubMed Central

The annotation of the Escherichia coli K-12 genome in the EcoCyc database is one of the most accurate, complete and multidimensional genome annotations. Of the 4460 E. coli genes, EcoCyc assigns biochemical functions to 76%, and 66% of all genes had their functions determined experimentally. EcoCyc assigns E. coli genes to Gene Ontology and to MultiFun. Seventy-five percent of gene products contain reviews authored by the EcoCyc project that summarize the experimental literature about the gene product. EcoCyc information was derived from 15 000 publications. The database contains extensive descriptions of E. coli cellular networks, describing its metabolic, transport and transcriptional regulatory processes. A comparison to genome annotations for other model organisms shows that the E. coli genome contains the most experimentally determined gene functions in both relative and absolute terms: 2941 (66%) for E. coli, 2319 (37%) for Saccharomyces cerevisiae, 1816 (5%) for Arabidopsis thaliana, 1456 (4%) for Mus musculus and 614 (4%) for Drosophila melanogaster. Database queries to EcoCyc survey the global properties of E. coli cellular networks and illuminate the extent of information gaps for E. coli, such as dead-end metabolites. EcoCyc provides a genome browser with novel properties, and a novel interactive display of transcriptional regulatory networks.

Karp, Peter D.; Keseler, Ingrid M.; Shearer, Alexander; Latendresse, Mario; Krummenacker, Markus; Paley, Suzanne M.; Paulsen, Ian; Collado-Vides, Julio; Gama-Castro, Socorro; Peralta-Gil, Martin; Santos-Zavaleta, Alberto; Penaloza-Spinola, Monica I.; Bonavides-Martinez, Cesar; Ingraham, John

2007-01-01

188

Food Reservoir for Escherichia coli Causing Urinary Tract Infections  

PubMed Central

Closely related strains of Escherichia coli have been shown to cause extraintestinal infections in unrelated persons. This study tests whether a food reservoir may exist for these E. coli. Isolates from 3 sources over the same time period (2005–2007) and geographic area were compared. The sources comprised prospectively collected E. coli isolates from women with urinary tract infection (UTI) (n = 353); retail meat (n = 417); and restaurant/ready-to-eat foods (n = 74). E. coli were evaluated for antimicrobial drug susceptibility and O:H serotype and compared by using 4 different genotyping methods. We identified 17 clonal groups that contained E. coli isolates (n = 72) from >1 source. E. coli from retail chicken (O25:H4-ST131 and O114:H4-ST117) and honeydew melon (O2:H7-ST95) were indistinguishable from or closely related to E. coli from human UTIs. This study provides strong support for the role of food reservoirs or foodborne transmission in the dissemination of E. coli causing common community-acquired UTIs.

Vincent, Caroline; Boerlin, Patrick; Daignault, Danielle; Dozois, Charles M.; Dutil, Lucie; Galanakis, Chrissi; Reid-Smith, Richard J.; Tellier, Pierre-Paul; Tellis, Patricia A.; Ziebell, Kim

2010-01-01

189

EcoCyc: Enyclopedia of Escherichia coli Genes and Metabolism.  

PubMed Central

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.

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

1997-01-01

190

EcoCyc: Enyclopedia of Escherichia coli Genes and Metabolism.  

PubMed

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. PMID:9016502

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

1997-01-01

191

Eco Cyc: encyclopedia of Escherichia coli genes and metabolism.  

PubMed

The EcoCyc database describes the genome and gene products of Escherichia coli, its metabolic and signal-transduction pathways, and its tRNAs. The database describes 4391 genes of E.coli, 695 enzymes encoded by a subset of these genes, 904 metabolic reactions that occur in E.coli, and the organization of these reactions into 129 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 has many references to the primary literature, and is a (qualitative) computational model of E. coli metabolism. EcoCyc is available at URL http://ecocyc. PangeaSystems.com/ecocyc/ PMID:9847140

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

1999-01-01

192

Inhibition of Escherichia coli-Induced Meningitis by Carboxyfullerence  

PubMed Central

The effect of a water-soluble malonic acid derivative of carboxyfullerence (C60) against Escherichia coli-induced meningitis was tested. C60 can protect the mice from E. coli-induced death in a dose-dependent manner. C60 administered intraperitoneally as late as 9 h after E. coli injection was still protective. The C60-treated mice had less tumor necrosis factor alpha and interleukin-1? production by staining of brain tissue compared to the levels of production for nontreated mice. The E. coli-induced increases in blood-brain barrier permeability and inflammatory neutrophilic infiltration were also inhibited. These data suggest that C60 is a potentially therapeutic agent for bacterial meningitis.

Tsao, Nina; Kanakamma, Puthuparampil P.; Luh, Tien-Yau; Chou, Chen-Kung; Lei, Huan-Yao

1999-01-01

193

Production of 5-Methlthioribose by 'Escherichia coli.'.  

National Technical Information Service (NTIS)

A study of sulfur metabolism in micro-organisms led to the isolation and identification of 5-methylthioribose (MTR) from E. coli B. MTR labeled with 35S was excreted by the bacterium during incubation in glucose-salts medium supplemented with 35SO4(-2). I...

M. F. Mallette

1972-01-01

194

Evaluation of Multiplex PCRs for Diagnosis of Infection with Diarrheagenic Escherichia coli and Shigella spp  

Microsoft Academic Search

Received 13 January 2004\\/Returned for modification 3 March 2004\\/Accepted 3 August 2004 We have developed two multiplex PCR assays that detect typical and atypical enteropathogenic Escherichia coli (EPEC) isolates, enteroaggregative E. coli (EAEC) isolates, enterotoxigenic E. coli (ETEC) isolates, enteroinvasive E. coli (EIEC) isolates, Shiga toxin-producing E. coli (STEC) isolates, and Shigella spp. The targets selected for each group were

K. R. S. Aranda; U. Fagundes-Neto; I. C. A. Scaletsky

2004-01-01

195

Effect of Escherichia coli enterotoxins on macromolecular absorption.  

PubMed Central

Macromolecular absorption of gliadin, a wheat protein and alpha lactalbumin, a milk protein was evaluated in control and Escherichia coli enterotoxin (heat-stable, heat-labile, and both heat-stable and heat-labile enterotoxin) treated mice. The peak concentration of gliadin and lactalbumin was two hours and three hours after their ingestion, respectively. There was also a significant increase (p < 0.01) in the absorption of both the proteins in all the three toxin treated groups compared with the control group. These results suggest that intestinal permeability and macromolecular absorption changes after E coli infection.

Verma, M; Majumdar, S; Ganguly, N K; Walia, B N

1994-01-01

196

Sodium-Stimulated Transport of Glutamate in Escherichia coli  

PubMed Central

Wild-type Escherichia coli B grew poorly on glutamate as the sole carbon source, except at very high concentrations of the amino acid. The addition of sodium ion markedly stimulated the growth. It had the same effect in a mutant of E. coli B selected for the ability to grow at low glutamate concentrations. Sodium ion also potentiated growth inhibition by analogues of glutamate. The uptake of glutamate by nongrowing cells of the mutant was markedly stimulated by sodium ion in the presence of an energy source, chloramphenicol, and arsenite, which retarded glutamate degradation.

Frank, Leonard; Hopkins, Irene

1969-01-01

197

Recombinant protein expression in Escherichia coli: advances and challenges  

PubMed Central

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

Rosano, German L.; Ceccarelli, Eduardo A.

2014-01-01

198

Accelerated glycerol fermentation in Escherichia coli using methanogenic formate consumption.  

PubMed

Escherichia coli can ferment glycerol anaerobically only under very defined restrictive conditions. Hence, it was the aim of this study to overcome this limitation via a co-cultivation approach. Anaerobic glycerol fermentation by a pure E. coli culture was compared to a co-culture that also contained the formate-oxidizing methanogen Methanobacterium formicicum. Co-cultivation of the two strains led to a more than 11-fold increased glycerol consumption. Furthermore, it supported a constantly neutral pH and a shift from ethanol to succinate production. Moreover, M. formicicum was analyzed for its ability to grow on different standard media and a surprising versatility could be demonstrated. PMID:24785787

Richter, Katrin; Gescher, Johannes

2014-06-01

199

A signal transducer for aerotaxis in Escherichia coli.  

PubMed Central

The newly discovered aer locus of Escherichia coli encodes a 506-residue protein with an N terminus that resembles the NifL aerosensor and a C terminus that resembles the flagellar signaling domain of methyl-accepting chemoreceptors. Deletion mutants lacking a functional Aer protein failed to congregate around air bubbles or follow oxygen gradients in soft agar plates. Membranes with overexpressed Aer protein also contained high levels of noncovalently associated flavin adenine dinucleotide (FAD). We propose that Aer is a flavoprotein that mediates positive aerotactic responses in E. coli. Aer may use its FAD prosthetic group as a cellular redox sensor to monitor environmental oxygen levels.

Bibikov, S I; Biran, R; Rudd, K E; Parkinson, J S

1997-01-01

200

Catalase-negative Escherichia coli isolated from blood.  

PubMed Central

A catalase-negative variant of Escherichia coli was isolated from the blood of a patient with acute leukemia who had been treated with various antibiotics and gentamicin. This small-colony variant grew almost as actively under anaerobic conditions as its large-colony revertant or E. coli NIHJ JC-2. The variant was resistant to gentamicin, in contrast with the revertant. Streptomycin and hemin stimulated growth of the variant slightly. With repeated subculturing the variant tended to increase slightly in colony size with coincident recovery of weak catalase production. The possibility that such a variant may have been induced by gentamicin was indicated. Images

Funada, H; Hattori, K I; Kosakai, N

1978-01-01

201

Acs is essential for propionate utilization in Escherichia coli.  

PubMed

Bacteria like Escherichia coli can use propionate as sole carbon and energy source. All pathways for degradation of propionate start with propionyl-CoA. However, pathways of propionyl-CoA synthesis from propionate and their regulation mechanisms have not been carefully examined in E. coli. In this study, roles of the acetyl-CoA synthetase encoding gene acs and the NAD(+)-dependent protein deacetylase encoding gene cobB on propionate utilization in E. coli were investigated. Results from biochemical analysis showed that, reversible acetylation also modulates the propionyl-CoA synthetase activity of Acs. Subsequent genetic analysis revealed that, deletion of acs in E. coli results in blockage of propionate utilization, suggesting that acs is essential for propionate utilization in E. coli. Besides, deletion of cobB in E. coli also results in growth defect, but only under lower concentrations of propionate (5mM and 10mM propionate), suggesting the existence of other propionyl-CoA synthesis pathways. In combination with previous observations, our data implies that, for propionate utilization in E. coli, a primary amount of propionyl-CoA seems to be required, which is synthesized by Acs. PMID:24835953

Liu, Fengying; Gu, Jing; Wang, Xude; Zhang, Xian-En; Deng, Jiaoyu

2014-07-01

202

Erosion and Subsequent Transport State of Escherichia coli from Cowpats  

PubMed Central

Processes by which fecal bacteria enter overland flow and their transportation state to surface waters are poorly understood, making the effectiveness of measures designed to intercept this pathway, such as vegetated buffer strips, difficult to predict. Freshly made and aged (up to 30 days) cowpats were exposed to simulated rainfall, and samples of the cowpat material and runoff were collected. Escherichia coli in the runoff samples were separated into attached (to particles) and unattached fractions, and the unattached fraction was analyzed to determine if the cells were clumped. Within cowpats, E. coli grew for 6 to 14 days, rather than following a typical logarithmic die-off curve. E. coli numbers in the runoff correlated with numbers inside the cowpat. Most of the E. coli organisms eroded from the cowpats were transported as single cells, and only a small percentage (about 8%) attached to particles. The erosion of E. coli from cowpats and the state in which the cells were transported did not vary with time within a single rainfall event or over time as the cowpats aged and dried out. These findings indicate that cowpats can remain a significant source of E. coli in overland flow for more than 30 days. As well, most of the E. coli organisms eroded from cowpats will occur as readily transportable single cells.

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

2005-01-01

203

Pathotyping blaCTX-M Escherichia coli from Nigeria  

PubMed Central

Background: Escherichia coli have become the enterobacteriaceae species most affected by extended-spectrum ?-lactamases (ESBLs) in view of the emergence of CTX-M-type ESBLs. These CTX-M-positive E. coli have been reported in numerous regions worldwide. Virulence determinants of already reported CTX-M-positive E. coli were investigated. Methodology: To gain insights into the mechanism underlying this phenomenon, we assessed serogroup, susceptibility pattern and diversity of virulence profiles within a collection of nine blaCTX-M-positive E. coli strains and their virulent determinant using miniaturized DNA microarray techniques. The nine ESBL-positive E. coli isolates were from eight male and one female patient(s) selected for study based on previous work. Virulence potential was inferred by detection of 63 virulence factor (VF) genes. Results: Four (44.4%) of the 9 E. coli isolates exhibited the same set of core characteristics: serotype O8:Hnt, while all were positive for OXA-1, ciprofloxacin resistance. Five of the isolates exhibited highly similar (91% to 100%) VF profiles. Conclusion: The findings describe a broadly disseminated, blaCTX-M-positive and virulent E. coli serogroup with highly homogeneous virulence genotypes, suggesting recent emergence in this zone. Understanding how this clone has emerged and successfully disseminated within the hospital and community, including across national boundaries, should be a public health priority.

Olowe, Olugbenga Adekunle; Choudhary, Suman; Schierack, Peter; Wieler, Lothar H.; Olayemi, Albert B.; Anjum, Muna

2013-01-01

204

Compilation of DNA sequences of Escherichia coli  

PubMed Central

We have compiled the DNA sequence data for E.coli K12 available from the GENBANK and EMBO databases and over a period of several years independently from the literature. We have introduced all available genetic map data and have arranged the sequences accordingly. As far as possible the overlaps are deleted and a total of 940,449 individual bp is found to be determined till the beginning of 1989. This corresponds to a total of 19.92% of the entire E.coli chromosome consisting of about 4,720 kbp. This number may actually be higher by some extra 2% derived from the sequence of lysogenic bacteriophage lambda and the various insertion sequences. This compilation may be available in machine readable form from one of the international databanks in some future.

Kroger, Manfred

1989-01-01

205

Enteropathogenic Escherichia coli Prevalence in Laboratory Rabbits  

PubMed Central

Rabbit-origin enteropathogenic E. coli (EPEC) causes substantial diarrhea-associated morbidity and has zoonotic potential. A culture-based survey was undertaken to ascertain its prevalence. EPEC was isolated from 6/141 (4.3%) commercially-acquired laboratory rabbits. Three of these did not have diarrhea or EPEC-typical intestinal lesions; they instead had background plasmacytic intestinal inflammation. Asymptomatically infected rabbits may function as EPEC reservoirs.

Swennes, Alton G.; Buckley, Ellen M.; Madden, Carolyn M.; Byrd, Charles P.; Donocoff, Rachel S.; Rodriguez, Loretta; Parry, Nicola M. A.; Fox, James G.

2013-01-01

206

Use of Genetically Engineered Escherichia coli to Monitor Ingestion, Loss, and Transfer of Bacteria in Termites  

Microsoft Academic Search

Escherichia coli was transformed with a recombinant plasmid (pEGFP) containing the genes for ampicillin resistance and Green Fluorescent Protein (GFP). Escherichia coli expressing GFP ( E. coli\\/GFP+) was then fed to workers of the termite Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). The transformed bacteria in the termite guts were detected by growing the gut flora under selective conditions and then checking

C. Husseneder; J. K. Grace; D. E. Oishi

2005-01-01

207

Demonstration of enterotoxigenic Escherichia coli in diarrheic broiler chicks.  

PubMed

An investigation was made to survey the possible presence of enterotoxigenic Escherichia coli (ETEC) in the stools of diarrheal chicks. We analyzed two outbreaks of diarrhea in broiler chicks at two independent farms in the Philippines, from which no pathogens other than Escherichia coli were found. In one outbreak at Farm #1, all 42 isolates produced heat-labile enterotoxin (LT), with 3 of these isolates also producing heat-stable enterotoxin (ST). The O serotypes of 15 strains tested randomly could not be identified as any known serotype (0-antigen; 1-170). In another outbreak at Farm #2, 7 out of 52 isolates produced only LT, their subtypes being identified as O-149 or O-8, common serotypes in pig ETEC. Strains from Farm #1 did not produce any pili usually found in human ETEC. We believe this to be the first isolation of ETEC from diarrheal chicks. PMID:2188851

Joya, J E; Tsuji, T; Jacalne, A V; Arita, M; Tsukamoto, T; Honda, T; Miwatani, T

1990-03-01

208

Enterotoxigenic Escherichia coli infection in captive black-footed ferrets.  

PubMed

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

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

2001-07-01

209

Growth of uropathogenic Escherichia coli strains at solid surfaces  

Microsoft Academic Search

The adhesion and growth of two catheter-associated (O2K2 and O83K?) and two non catheter-associated (O111K58 and 0157K-) uropathogenic Escherichia coli strains on glass, poly(methyl methacrylate) (PMMA), a negatively charged copolymer of MMA and methacrylic acid (MAA) and a positively charged copolymer of MMA and trimethylaminoethyl methacrylate chloride (TMAEMA-Cl) were studied. The solid surfaces were placed in a parallel plate perfusion

G. Harkes; J. Dankert; J. Feijen

1992-01-01

210

Regulatory network of acid resistance genes in Escherichia coli  

Microsoft Academic Search

Summary Overexpression of the response regulator EvgA con- fers an acid-resistant phenotype to exponentially growing Escherichia coli . This acid resistance is par- tially abolished by deletion of ydeP , yhiE or ydeO , genes induced by EvgA overexpression. Microarray analysis identified two classes of operons (genes). The first class contains seven operons induced by EvgA overexpression in the absence

Nobuhisa Masuda; George M. Church

2003-01-01

211

Hydrogen Peroxide Fluxes and Compartmentalization inside Growing Escherichia coli  

Microsoft Academic Search

Escherichia coli generates about 14 M hydrogen peroxide (H2O2) per s when it grows exponentially in glucose medium. The steady-state intracellular concentration of H2O2 depends on the rates at which this H2O2 is dissipated by scavenging enzymes and by efflux from the cell. The rates of H2O2 degradation by the two major scavenging enzymes, alkyl hydroperoxide reductase and catalase, were

LAUREN COSTA SEAVER; JAMES A. IMLAY

2001-01-01

212

Endonuclease IV of Escherichia coli is Induced by Paraquat  

Microsoft Academic Search

The addition of paraquat (methyl viologen) to a growing culture of Escherichia coli K-12 led within 1 hr to a 10- to 20-fold increase in the level of endonuclease IV, a DNase for apurinic\\/apyrimidinic sites. The induction was blocked by chloramphenicol. Increases of 3-fold or more were also seen with plumbagin, menadione, and phenazine methosulfate. H2O2 produced no more than

Emily Chan; Bernard Weiss

1987-01-01

213

Mechanisms Accounting for Fluoroquinolone Resistance in Escherichia coli Clinical Isolates  

Microsoft Academic Search

Fluoroquinolone MICs are increased through the acquisition of chromosomal mutations in the genes encoding gyrase (gyrA and gyrB) and topoisomerase IV (parC and parE), increased levels of the multidrug efflux pump AcrAB, and the plasmid-borne genes aac(6)-Ib-cr and the qnr variants in Escherichia coli .I n the accompanying report, we found that ciprofloxacin, gatifloxacin, levofloxacin, and norfloxacin MICs for fluo-

Sonia K. Morgan-Linnell; Lauren Becnel Boyd; David Steffen; Lynn Zechiedrich

2009-01-01

214

Genetic Background of Escherichia coli and Extended spectrum ? ?-Lactamase Type  

Microsoft Academic Search

To assess the implication of the genetic background of Escherichia coli strains in the emergence of extended- spectrum ?-lactamases (ESBL), 55 TEM-, 52 CTX-M-, and 22 SHV-type ESBL-producing clinical isolates involved in various extraintestinal infections or colonization were stud- ied in terms of phylogenetic group, virulence factor (VF) content (pap, sfa\\/foc, hly, and aer genes), and fluoro- quinolone resistance. A

Catherine Branger; Oana Zamfir; Sabine Geoffroy; Geneviève Laurans; Guillaume Arlet; Hoang Vu Thien; Stéphanie Gouriou; Bertrand Picard; Erick Denamur

215

Directed Mutation in Escherichia Coli : Theory and Mechanisms  

Microsoft Academic Search

\\u000a For a haploid unicellular organism, such as Escherichia coli, that reproduces asexually by binary fission, the concept of “self”, or more appropriately, “individual”, may be indistinguishable\\u000a from the concept of organism. Controversy has arisen in the past about whether and how such creatures maintain themselves\\u000a as a species since every new mutant that appears could, theoretically, give rise to a

Patricia L. Foster

216

Escherichia coli and Salmonella 2000: the view from here.  

PubMed

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

Schaechter, M

2001-03-01

217

Characterization of intestinal cnf1 + Escherichia coli from weaned pigs  

Microsoft Academic Search

Escherichia coli isolated from 204 cases of porcine postweaning diarrhoea were tested by PCR for the genes of cytotoxic necrotic factors (CNF) and of cytolethal dystending toxin (CDT). selected strains were also examined by PCR for the presence of papC-, sfa-, f17-, f18- , and afa -specific sequences encoding P, S, F17, F18 fimbriae and afimbrial adhesins. A 5.9% (12\\/204)

István Tóth; Eric Oswald; Jacques G. Mainil; Mohamed Awad-Masalmeh; Béla Nagy

2000-01-01

218

Bacteroides fragilis concealed in an infant with Escherichia coli meningitis.  

PubMed

Anaerobic meningitis in infants is rare, therefore a high index of clinical suspicion is essential as routine methods for processing cerebrospinal fluid (CSF) do not detect anaerobes and specific antimicrobial therapy is required. We present an infant with Escherichia coli meningitis where treatment-resistance developed in association with culture negative purulent CSF. These features should have alerted us to the presence of anaerobes, prompting a search for the causes of polymicrobial meningitis in infants. PMID:24118618

Ganeshalingham, Anusha; Buckley, David; Shaw, Ian; Freeman, Joshua T; Wilson, Francessa; Best, Emma

2014-01-01

219

Energetics of calcium efflux from cells of Escherichia coli.  

PubMed Central

Intact cells of a H+-translocating ATPase-deficient strain of Escherichia coli were starved of endogenous energy reserves and passively loaded with 45CaCl2. Energy-dependent efflux of calcium was observed upon addition of glucose or respiratory substrates. Addition of cyanide or uncouplers prevented efflux. It is concluded that calcium efflux in intact cells is coupled to the proton motive force via secondary calcium-proton exchange.

Tsujibo, H; Rosen, B P

1983-01-01

220

Effects of Chromosome Underreplication on Cell Division in Escherichia coli  

Microsoft Academic Search

The key processes of the bacterial cell cycle are controlled and coordinated to match cellular mass growth. We have studied the coordination between replication and cell division by using a temperature-controlled Escherichia coli intR1 strain. In this strain, the initiation time for chromosome replication can be displaced to later (underreplication) or earlier (overreplication) times in the cell cycle. We used

EMILIA BOTELLO; KURT NORDSTROM

1998-01-01

221

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7  

Microsoft Academic Search

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the

Nicole T. Perna; Guy Plunkett; Valerie Burland; Bob Mau; Jeremy D. Glasner; Debra J. Rose; George F. Mayhew; Peter S. Evans; Jason Gregor; Heather A. Kirkpatrick; György Pósfai; Jeremiah Hackett; Sara Klink; Adam Boutin; Ying Shao; Leslie Miller; Erik J. Grotbeck; N. Wayne Davis; Alex Lim; Eileen T. Dimalanta; Konstantinos D. Potamousis; Jennifer Apodaca; Thomas S. Anantharaman; Jieyi Lin; Galex Yen; David C. Schwartz; Rodney A. Welch; Frederick R. Blattner

2001-01-01

222

Diffusion of Glycerol through Escherichia coli Aquaglyceroporin GlpF  

Microsoft Academic Search

The glycerol uptake facilitator, GlpF, a major intrinsic protein found in Escherichia coli, selectively conducts water and glycerol across the inner membrane. The free energy landscape characterizing the assisted transport of glycerol by this homotetrameric aquaglyceroporin has been explored by means of equilibrium molecular dynamics over a timescale spanning 0.12?s. To overcome the free energy barriers of the conduction pathway,

Jérôme Hénin; Emad Tajkhorshid; Klaus Schulten; Christophe Chipot

2008-01-01

223

Electric field induced bacterial flocculation of enteroaggregative Escherichia coli 042  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

224

AICAR is not an endogenous mutagen in Escherichia coli  

Microsoft Academic Search

A number of observations in the Escherichia coli and Salmonella typhimurium literature could be explained by the hypothesis that a particular purine ribonucleotide precursor can be converted to the corresponding deoxyribonucleotide triphosphate, thereby becoming a base-analogue mutagen. The metabolite in question, AICAR (5-amino-4-carboxamide imidazole riboside 5'-phosphate), is also a by-product of histidine biosynthesis, and its (ribo)triphosphate derivative, ZTP, has been

Maurice Fox; Niels Frandsen; Richard D'Ari

1993-01-01

225

Mucosal Immune Responses Against Enterotoxigenic Escherichia coli [ETEC] in Humans  

Microsoft Academic Search

Enterotoxigenic Escherichia coli [ETEC] is among the most important causes of diarrhoea morbidity and mortality, particularly\\u000a in children below 5 years of age in developing countries. The bacteria are also a common cause of diarrhoea outbreaks as well\\u000a as of diarrhoeal disease in travellers to Africa, Asia and Latin America. ETEC is a classical non-invasive mucosal pathogen\\u000a that colonizes the

Ann-Mari Svennerholm; Firdausi Qadri

226

Escherichia coli RNA Polymerase Activity Observed Using Atomic Force Microscopy †  

Microsoft Academic Search

Fluid tapping-mode atomic force microscopy (AFM) was used to observe Escherichia coli RNA polymerase (RNAP) transcribing two different linear double-stranded (ds) DNA templates. The transcription process was detected by observing the translocation of the DNA template by RNAP on addition of ribonucleoside 5'-triphosphates (NTPs) in sequential AFM images. Stalled ternary complexes of RNAP, dsDNA and nascent RNA were adsorbed onto

Sandor Kasas; Neil H. Thomson; Bettye L. Smith; Helen G. Hansma; Xingshu Zhu; Martin Guthold; Carlos Bustamante; Eric T. Kool; Mikhail Kashlev; Paul K. Hansma

1997-01-01

227

Role of threonine dehydrogenase in Escherichia coli threonine degradation.  

PubMed Central

Threonine was used as nitrogen source by Escherichia coli K-12 through a pathway beginning with the enzyme threonine dehydrogenase. The 2-amino-3-ketobutyrate formed was converted to glycine, and the glycine was converted to serine, which acted as the actual nitrogen donor. The enzyme formed under anaerobic conditions and known as threonine deaminase (biodegradative) is less widespread than threonine dehydrogenase and may be involved in energy metabolism rather than in threonine degradation per se.

Potter, R; Kapoor, V; Newman, E B

1977-01-01

228

Ocular lesions in chickens inoculated with Escherichia coli.  

PubMed Central

Specific-pathogen-free chickens (two, four and ten weeks of age) which were inoculated via the air sac with Escherichia coli developed ocular lesions. Histologically, the main ocular lesions consisted of hyphema, hemorrhages of the iris, hypopyon, keratitis and uveitis. Hyphema was associated with hemorrhages of the iris, and hypopyon with keratitis and uveitis. Cyclophosphamide treatment enhanced the incidence and severity of hyphema and hemorrhages of the iris in the chickens. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4.

Nakamura, K; Abe, F

1987-01-01

229

Efficient Expression of Escherichia coli Galactokinase Gene in Mammalian Cells  

Microsoft Academic Search

The Escherichia coli galactokinase gene (galK) was inserted into a modified early region transcription unit of simian virus 40 (SV40) contained on a bacterial plasmid. Introduction of this pSVK vector into monkey, mouse, and hamster cell lines by transfection resulted in efficient expression of the bacterial galK gene. This expression was shown to be dependent upon fusion of the galK

Daniel Schumperli; Bruce H. Howard; Martin Rosenberg

1982-01-01

230

Growth-phase regulation of the Escherichia coli thioredoxin gene  

Microsoft Academic Search

The two promoters of Escherichia coli trxA gene were separately cloned into pKO100 as well as pJEL170. Galactokinase expression in cells containing the pKO100 derivatives was found to be negatively correlated with growth rate and was 6- to 20-fold higher in stationary cultures than in exponential cultures. The expression of trxA-galK was induced by amino acid starvation in a RelA+

Chang-Jin Lim; Tom Daws; Maryam Gerami-Nejad; James A. Fuchs

2000-01-01

231

Transcriptional analysis of the pst operon of Escherichia coli  

Microsoft Academic Search

The pst operon of Escherichia coli, which encodes the phosphate-specific transport system, is composed of five genes, pstS, pstC, pstA, pstB and phoU, whose transcription is induced by phosphate starvation. A phosphate-regulated promoter located upstream of the most proximal gene (pstS) controls the transcription of the entire operon. Though the full-length pst mRNA could be detected by an improved RT-PCR

M. Aguena; E. Yagil; B. Spira

2002-01-01

232

Induction of the Escherichia coli UVM response by oxidative stress  

Microsoft Academic Search

UVM (ultravioletmodulation of mutagenesis) is a recently describedrecA-independent, inducible mutagenic phenomenon in which prior UV irradiation ofEscherichia coli cells strongly enhances mutation fixation at a site-specific 3-N4-ethenocytosine (?C) lesion borne on a transfected single-stranded M13 DNA vector. Subsequent studies demonstrated that UVM is also induced by alkylating agents, and is distinct from both the SOS response and the adaptive response

G. Wang; M. Z. Humayun

1996-01-01

233

Discrimination of Escherichia coli strains using glycan cantilever array sensors.  

PubMed

Carbohydrate-based sensors, that specifically detect sugar binding molecules or cells, are increasingly important in medical diagnostic and drug screening. Here we demonstrate that cantilever arrays functionalized with different mannosides allow the real-time detection of several Escherichia coli strains in solution. Cantilever deflection is thereby dependent on the bacterial strain studied and the glycan used as the sensing molecule. The cantilevers exhibit specific and reproducible deflection with a sensitivity range over four orders of magnitude. PMID:22136522

Mader, Andreas; Gruber, Kathrin; Castelli, Riccardo; Hermann, Bianca A; Seeberger, Peter H; Rädler, Joachim O; Leisner, Madeleine

2012-01-11

234

A model system for pathogen detection using a two-component bacteriophage\\/bioluminescent signal amplification assay  

Microsoft Academic Search

Microbial contamination has become a mounting concern the last decade due to an increased emphasis of minimally processed food products specifically produce, and the recognition of foodborne pathogens such as Campylobacter jejuni, Escherichia coli O157:H7, and Listeria monocytogenes. This research investigates a detection approach utilizing bacteriophage pathogen specificity coupled with a bacterial bioluminescent bioreporter utilizing the quorum sensing molecule from

Nathan G. Bright; Richard J. Carroll; Bruce M. Applegate

2004-01-01

235

Fluorogenic assays for immediate confirmation of Escherichia coli.  

PubMed Central

Rapid assays for Escherichia coli were developed by using the compound 4-methylumbelliferone glucuronide (MUG), which is hydrolyzed by glucuronidase to yield a fluorogenic product. The production of glucuronidase was limited to strains of E. coli and some Salmonella and Shigella strains in the family Enterobacteriaceae. For immediate confirmation of the presence of E. coli in most-probable-number tubes, MUG was incorporated into lauryl tryptose broth at a final concentration of 100 micrograms/ml. Results of both the presumptive test (gas production) and the confirmed test (fluorescence) for E. coli were obtained from a variety of food, water, and milk samples after incubation for only 24 h at 35 degrees C. Approximately 90% of the tubes showing both gas production and fluorescence contained fecal coliforms (they were positive in EC broth incubated at 45 degrees C). Few false-positive reactions were observed. The lauryl tryptose broth-MUG-most-probable-number assay was superior to violet red bile agar for the detection of heat- and chlorine-injured E. coli cells. Anaerogenic strains produced positive reactions, and small numbers of E. coli could be detected in the presence of large numbers of competing bacteria. The fluorogenic assay was sensitive and rapid; the presence of one viable cell was detected within 20 h. E. coli colonies could be distinguished from other coliforms on membrane filters and plates of violet red bile agar if MUG was incorporated into the culture media. A rapid confirmatory test for E. coli that is amenable to automation was developed by using microtitration plates filled with a nonselective medium containing MUG. Pure or mixed cultures containing E. coli produced fluorescence within 4 h (most strains) to 24 h (a few weakly positive strains). Images

Feng, P C; Hartman, P A

1982-01-01

236

Escherichia coli sequence type 131: epidemiology and challenges in treatment.  

PubMed

Escherichia coli ST131 has emerged as a global epidemic, multidrug-resistant clone of E. coli causing extra-intestinal infections. It is now highly prevalent among fluoroquinolone-resistant and CTX-M ESBL-producing E. coli isolates worldwide. Humans are likely the primary reservoir of ST131. Factors associated with its acquisition include residence in long-term care facilities and recent receipt of antimicrobial agents. E. coli ST131 causes a wide array of infections ranging from cystitis to life-threatening sepsis. Fluoroquinolones and trimethoprim-sulfamethoxazole are no longer adequate options for empiric therapy when E. coli ST131 is suspected from risk factors and local epidemiology. Expanded-spectrum cephalosporins, piperacillin-tazobactam and carbapenems are options to treat serious non-ESBL-producing E. coli ST131 infections, while carbapenems are indicated for ESBL-producing infections. There is a growing interest in reevaluating oral agents including fosfomycin and pivmecillinam for less serious infections such as uncomplicated cystitis. PMID:24694052

Qureshi, Zubair A; Doi, Yohei

2014-05-01

237

Bacteriophage cocktail significantly reduces Escherichia coli O157  

PubMed Central

Foods contaminated with Escherichia coli O157:H7 cause more than 63,000 foodborne illnesses in the United States every year, resulting in a significant economic impact on medical costs and product liabilities. Efforts to reduce contamination with E. coli O157:H7 have largely focused on washing, application of various antibacterial chemicals, and gamma-irradiation, each of which has practical and environmental drawbacks. A relatively recent, environmentally-friendly approach proposed for eliminating or significantly reducing E. coli O157:H7 contamination of foods is the use of lytic bacteriophages as biocontrol agents. We found that EcoShield™, a commercially available preparation composed of three lytic bacteriophages specific for E. coli O157:H7, significantly (p < 0.05) reduced the levels of the bacterium in experimentally contaminated beef by ? 94% and in lettuce by 87% after a five minute contact time. The reduced levels of bacteria were maintained for at least one week at refrigerated temperatures. However, the one-time application of EcoShield™ did not protect the foods from recontamination with E. coli O157:H7. Our results demonstrate that EcoShield™ is effective in significantly reducing contamination of beef and lettuce with E. coli O157:H7, but does not protect against potential later contamination due to, for example, unsanitary handling of the foods post processing.

Carter, Chandi D.; Parks, Adam; Abuladze, Tamar; Li, Manrong; Woolston, Joelle; Magnone, Joshua; Senecal, Andre; Kropinski, Andrew M.; Sulakvelidze, Alexander

2012-01-01

238

Phylogenetic Analysis of Enteroaggregative and Diffusely Adherent Escherichia coli  

PubMed Central

The phylogenetics of the various pathotypes of diarrheagenic Escherichia coli are not completely understood. In this study, we identified several plasmid and chromosomal genes in the pathogenic enteroaggregative E. coli (EAEC) prototype strain 042 and determined the prevalence of these loci among EAEC and diffusely adherent E. coli strains. The distribution of these genes is analyzed within an evolutionary framework provided by the characterization of allelic variation in housekeeping genes via multilocus enzyme electrophoresis. Our data reveal that EAEC strains are heterogeneous with respect to chromosomal and plasmid-borne genes but that the majority harbor a member of a conserved family of virulence plasmids. Comparison of plasmid and chromosomal relatedness of strains suggests clonality of chromosomal markers and a limited transfer model of plasmid distribution.

Czeczulin, John R.; Whittam, Thomas S.; Henderson, Ian R.; Navarro-Garcia, Fernando; Nataro, James P.

1999-01-01

239

Curli fibers mediate internalization of Escherichia coli by eukaryotic cells.  

PubMed

Curli fibers are adhesive surface fibers expressed by Escherichia coli and Salmonella enterica that bind several host extracellular matrix and contact phase proteins and were assumed to have a role in pathogenesis. The results presented here suggest that one such role is internalization into host cells. An E. coli K-12 strain transformed with a low-copy vector containing the gene cluster encoding curli fibers (csg operon) was internalized by several lines of eukaryotic cells. The internalization could be correlated with a high level of curli fiber expression and was abolished by disruption of the csg operon. The ability to be internalized by eukaryotic cells could be conferred even by the curli fiber gene cluster of a noninvasive K-12 strain, but the homologous csg cluster from a virulent septicemic E. coli isolate mediated a higher level of internalization. The finding that curli fibers promote bacterial internalization indicates a new role for curli fibers in pathogenesis. PMID:11254632

Gophna, U; Barlev, M; Seijffers, R; Oelschlager, T A; Hacker, J; Ron, E Z

2001-04-01

240

Curli Fibers Mediate Internalization of Escherichia coli by Eukaryotic Cells  

PubMed Central

Curli fibers are adhesive surface fibers expressed by Escherichia coli and Salmonella enterica that bind several host extracellular matrix and contact phase proteins and were assumed to have a role in pathogenesis. The results presented here suggest that one such role is internalization into host cells. An E. coli K-12 strain transformed with a low-copy vector containing the gene cluster encoding curli fibers (csg operon) was internalized by several lines of eukaryotic cells. The internalization could be correlated with a high level of curli fiber expression and was abolished by disruption of the csg operon. The ability to be internalized by eukaryotic cells could be conferred even by the curli fiber gene cluster of a noninvasive K-12 strain, but the homologous csg cluster from a virulent septicemic E. coli isolate mediated a higher level of internalization. The finding that curli fibers promote bacterial internalization indicates a new role for curli fibers in pathogenesis.

Gophna, U.; Barlev, M.; Seijffers, R.; Oelschlager, T. A.; Hacker, J.; Ron, E. Z.

2001-01-01

241

Pulsed ultra-violet inactivation spectrum of Escherichia coli.  

PubMed

Inactivation of Escherichia coli is examined using ultra-violet (UV) radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV content. The flashlamp provides high-energy UV output using a small number of short-duration pulses (30 micros). The flashlamp is used with a monochromator to investigate the wavelength sensitivity of E. coli to inactivation by the pulsed UV light. Using 8 nm wide pulses of UV radiation, the most efficient inactivation is found to occur at around 270 nm and no inactivation is observed above 300 nm. A pyroelectric detector allows the energy dose to be determined at each wavelength, and a peak value for E. coli population reduction of 0.43 log per mJ/cm(2) is measured at 270 nm. The results are compared with the published data available for continuous UV light sources. PMID:15993922

Wang, T; Macgregor, S J; Anderson, J G; Woolsey, G A

2005-08-01

242

Biofilm Modifies Expression of Ribonucleotide Reductase Genes in Escherichia coli  

PubMed Central

Ribonucleotide reductase (RNR) is an essential enzyme for all living organisms since is the responsible for the last step in the synthesis of the four deoxyribonucleotides (dNTPs) necessary for DNA replication and repair. In this work, we have investigated the expression of the three-RNR classes (Ia, Ib and III) during Escherichia coli biofilm formation. We show the temporal and spatial importance of class Ib and III RNRs during this process in two different E. coli wild-type strains, the commensal MG1655 and the enteropathogenic and virulent E2348/69, the prototype for the enteropathogenic E. coli (EPEC). We have established that class Ib RNR, so far considered cryptic, play and important role during biofilm formation. The implication of this RNR class under the specific growth conditions of biofilm formation is discussed.

Cendra, Maria del Mar; Juarez, Antonio; Torrents, Eduard

2012-01-01

243

Escherichia coli kgtP encodes an. alpha. -ketoglutarate transporter  

SciTech Connect

The witA gene located between pss and rrnG on the Escherichia coli chromosome encodes a 432-amino acid protein. It is homologous to a human hepatoma glucose transporter and to E. coli membrane proteins that transport citrate (CitA), arabinose (AraE), and xylose (XylE), and, like these carrier proteins, WitA also contains 12 highly hydrophobic putative membrane-spanning regions. Gene disruption mutants constructed in two E. coli strains grew slowly or not at all, depending on genetic background, in M9 minimal medium containing {alpha}-ketoglutarate and uptake of {alpha}-({sup 14}C)ketoglutarate were restored by transformation with plasmids containing witA. These complementation studies indicate that WitA is an {alpha}-ketoglutarate transporter and should be renamed kgtP({alpha}-ketoglutarate permease).

Seol, Wongi; Shatkin, A.J. (Center for Advanced Biotechnology and Medicine, Piscataway, NJ (United States))

1991-05-01

244

Engineering Escherichia coli K12 MG1655 to use starch  

PubMed Central

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

2014-01-01

245

Incidence of Escherichia coli in Black Walnut Meats  

PubMed Central

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

Meyer, Melvin T.; Vaughn, Reese H.

1969-01-01

246

Proteomic analysis of uropathogenic Escherichia coli.  

PubMed

Urinary tract infections (UTIs) are among the most common of bacterial infections in humans. Although a number of Gram-negative bacteria can cause UTIs, most cases are due to infection by uropathogenic E. coli (UPEC). Genomic studies have shown that UPEC encode a number of specialized activities that allow the bacteria to initiate and maintain infections in the environment of the urinary tract. Proteomic analyses have complemented the genomic data and have documented differential patterns of protein synthesis for bacteria growing ex vivo in human urine or recovered directly from the urinary tracts of infected mice. These studies provide valuable insights into the molecular basis of UPEC pathogenesis and have aided the identification of putative vaccine targets. Despite the substantial progress that has been achieved, many future challenges remain in the application of proteomics to provide a comprehensive view of bacterial pathogenesis in both acute and chronic UTIs. PMID:24393038

Cash, Phillip

2014-02-01

247

Anaerobic Transport in Escherichia coli Membrane Vesicles*  

PubMed Central

Anaerobic ?-galactoside transport in whole cells and membrane vesicles from E. coli ML 308-225 is coupled to the oxidation of ?-glycerol-P or D-lactate with fumarate as an electron acceptor. Alternatively, anaerobic ?-galactoside transport may be coupled to the oxidation of formate utilizing nitrate as electron acceptor. Both anaerobic electron-transfer systems are induced by growth of the organisms under appropriate conditions. Components of both systems are loosely bound to the membrane, necessitating the use of a modified procedure for vesicle preparation in order to demonstrate anaerobic transport in vitro. Addition of ATP or an ATP-generating system to vesicles prepared from anaerobically-grown cells or inclusion of ATP or the ATP-generating system during preparation of vesicles does not stimulate transport. The results support the conclusion that active transport under anaerobic conditions is coupled primarily to electron flow. Images

Konings, Wilhelmus N.; Kaback, H. Ronald

1973-01-01

248

Temporal Stimulation of Chemotaxis in Escherichia coli  

PubMed Central

We used the tracking microscope to study the chemotactic responses of E. coli to temporal gradients of L-glutamate generated in isotropic solutions by the action of the enzyme alanine aminotransferase. Positive gradients suppress directional changes which occur spontaneously in the absence of a stimulus. Negative gradients have little effect. The data can be fit with a model in which the suppression is proportional to the time rate of change of the fractional amount of chemoreceptor bound. The model accounts for the behavior of individual cells and populations of cells in spatial gradients. A computer simulation of the motion in spatial gradients indicates that if the bacteria have a “memory,” its decay time cannot be much longer than a few seconds. The relationship between the responses observed in these experiments and in experiments in which solutions of an attractant at different concentrations are mixed is discussed.

Brown, Douglas A.; Berg, Howard C.

1974-01-01

249

Effective medicinal plants against enterohaemorrhagic Escherichia coli O157:H7.  

PubMed

The stimulating effect of subinhibitory concentrations of antibiotics on the production of verocytotoxin (VT) by enterohaemorrhagic Escherichia coli (EHEC) O157:H7 has been claimed. The purpose of this study was to find an alternative, but bioactive medicine for the treatment of this organism. Fifty-eight preparations of aqueous and ethanolic extracts of 38 medicinal plant species commonly used in Thailand to cure gastrointestinal infections were tested for their antibacterial activity against different strains of Escherichia coli, including 6 strains of Escherichia coli O157:H7, Escherichia coli O26:H11, Escherichia coli O111:NM, Escherichia coli O22; 5 strains of Escherichia coli isolated from bovine; and Escherichia coli ATCC 25922. Inhibition of growth was primarily tested by the paper disc agar diffusion method. Among the medicinal plants tested, only 8 species (21.05%) exhibited antimicrobial activity against Escherichia coli O157:H7. Acacia catechu, Holarrhena antidysenterica, Peltophorum pterocarpum, Psidium guajava, Punica granatum, Quercus infectoria, Uncaria gambir, and Walsura robusta demonstrated antibacterial activity with inhibition zones ranging from 7 to 17 mm. The greatest inhibition zone against Escherichia coli O157:H7 (RIMD 05091083) was produced from the ethanolic extract of Quercus infectoria. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined by the agar microdilution method and agar dilution method in petri dishes with millipore filter. Both aqueous and ethanolic extracts of Quercus infectoria and aqueous extract of Punica granatum were highly effective against Escherichia coli O157:H7 with the best MIC and MBC values of 0.09, 0.78, and 0.19, 0.39 mg/ml, respectively. These plant species may provide alternative but bioactive medicines for the treatment of Escherichia coli O157:H7 infection. PMID:15261962

Voravuthikunchai, Supayang; Lortheeranuwat, Amornrat; Jeeju, Wanpen; Sririrak, Trechada; Phongpaichit, Souwalak; Supawita, Thanomjit

2004-09-01

250

Cancerous patients and outbreak of Escherichia coli: an important issue in oncology  

PubMed Central

The widespread of the Escherichia coli outbreak in Europe becomes an important public concern at global level. The infection can be serious and might result in death. The retrospective literature review on this specific topic is performed. In this specific brief article, the author presented and discussed on the problem of Escherichia coli infection in the cancerous patients. This is an actual important issue in medical oncology for the scenario of Escherichia coli epidemic.

Joob, Beuy; Wiwanitkit, Viroj

2014-01-01

251

Global dissemination of a multidrug resistant Escherichia coli clone.  

PubMed

Escherichia coli sequence type 131 (ST131) is a globally disseminated, multidrug resistant (MDR) clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with several factors, including resistance to fluoroquinolones, high virulence gene content, the possession of the type 1 fimbriae FimH30 allele, and the production of the CTX-M-15 extended spectrum ?-lactamase (ESBL). Here, we used genome sequencing to examine the molecular epidemiology of a collection of E. coli ST131 strains isolated from six distinct geographical locations across the world spanning 2000-2011. The global phylogeny of E. coli ST131, determined from whole-genome sequence data, revealed a single lineage of E. coli ST131 distinct from other extraintestinal E. coli strains within the B2 phylogroup. Three closely related E. coli ST131 sublineages were identified, with little association to geographic origin. The majority of single-nucleotide variants associated with each of the sublineages were due to recombination in regions adjacent to mobile genetic elements (MGEs). The most prevalent sublineage of ST131 strains was characterized by fluoroquinolone resistance, and a distinct virulence factor and MGE profile. Four different variants of the CTX-M ESBL-resistance gene were identified in our ST131 strains, with acquisition of CTX-M-15 representing a defining feature of a discrete but geographically dispersed ST131 sublineage. This study confirms the global dispersal of a single E. coli ST131 clone and demonstrates the role of MGEs and recombination in the evolution of this important MDR pathogen. PMID:24706808

Petty, Nicola K; Ben Zakour, Nouri L; Stanton-Cook, Mitchell; Skippington, Elizabeth; Totsika, Makrina; Forde, Brian M; Phan, Minh-Duy; Gomes Moriel, Danilo; Peters, Kate M; Davies, Mark; Rogers, Benjamin A; Dougan, Gordon; Rodriguez-Baño, Jesús; Pascual, Alvaro; Pitout, Johann D D; Upton, Mathew; Paterson, David L; Walsh, Timothy R; Schembri, Mark A; Beatson, Scott A

2014-04-15

252

Inhibition of Escherichia coli in cultivated cattle manure.  

PubMed

A common practice on Israeli dairy barns comprises daily cultivation of the manure. Cultivation is a mechanical process used to break up and till the manure bedding and it results in a drier and aerated bedding and cleaner cows, which consequently reduces the incidence of mastitis. Cultivation was associated with a shorter survival of Escherichia coli in cultivated manure as compared with noncultivated manure. The objective of the current study was to elucidate the mechanism responsible for the shorter survival duration of E. coli in the cultivated manure. We hypothesized that microorganisms that are antagonistic to E. coli, developing in the cultivated manure, are responsible for this phenomenon. A cow manure derived E. coli strain expressing the green fluorescence protein and antibiotic resistance markers was used to inoculate cow manure in 1.5-L jars. Manure treatments included cultivated and noncultivated manure. Half the jars of each cultivation treatment were autoclave sterilized at 121°C for 1 h on 3 successive days to eliminate from the manure antagonistic microorganisms. Each cultivation-sterilization treatment was performed in triplicate jars. Following sterilization, E. coli numbers in the cultivated and noncultivated manure were comparable, while in the nonsterilized manure the numbers were lower in the cultivated compared with the noncultivated manure. Several fungi isolated from the cultivated manure samples displayed inhibition effect on the tagged E. coli. Antagonistic fungi were also isolated from large-scale cultivated manure samples collected on several dairy farms in Israel. These findings support the notion that manure cultivation might facilitate the development of microorganisms that are antagonistic to E. coli, thus contributing to the general hygiene of the cattle. Identifying the mechanisms by which the antagonistic fungi affect the survival of E. coli in manure could be exploited for improvement of the animal health and for limiting the transmission of zoonotic pathogens to food and water. PMID:24663194

Weinberg, Z G; Szakacs, G; Chen, Y; Pinto, R; Bernstein, S; Konya, B; Sela Saldinger, S

2014-05-01

253

Global dissemination of a multidrug resistant Escherichia coli clone  

PubMed Central

Escherichia coli sequence type 131 (ST131) is a globally disseminated, multidrug resistant (MDR) clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with several factors, including resistance to fluoroquinolones, high virulence gene content, the possession of the type 1 fimbriae FimH30 allele, and the production of the CTX-M-15 extended spectrum ?-lactamase (ESBL). Here, we used genome sequencing to examine the molecular epidemiology of a collection of E. coli ST131 strains isolated from six distinct geographical locations across the world spanning 2000–2011. The global phylogeny of E. coli ST131, determined from whole-genome sequence data, revealed a single lineage of E. coli ST131 distinct from other extraintestinal E. coli strains within the B2 phylogroup. Three closely related E. coli ST131 sublineages were identified, with little association to geographic origin. The majority of single-nucleotide variants associated with each of the sublineages were due to recombination in regions adjacent to mobile genetic elements (MGEs). The most prevalent sublineage of ST131 strains was characterized by fluoroquinolone resistance, and a distinct virulence factor and MGE profile. Four different variants of the CTX-M ESBL–resistance gene were identified in our ST131 strains, with acquisition of CTX-M-15 representing a defining feature of a discrete but geographically dispersed ST131 sublineage. This study confirms the global dispersal of a single E. coli ST131 clone and demonstrates the role of MGEs and recombination in the evolution of this important MDR pathogen.

Petty, Nicola K.; Ben Zakour, Nouri L.; Stanton-Cook, Mitchell; Skippington, Elizabeth; Totsika, Makrina; Forde, Brian M.; Phan, Minh-Duy; Gomes Moriel, Danilo; Peters, Kate M.; Davies, Mark; Rogers, Benjamin A.; Dougan, Gordon; Rodriguez-Bano, Jesus; Pascual, Alvaro; Pitout, Johann D. D.; Upton, Mathew; Paterson, David L.; Walsh, Timothy R.; Schembri, Mark A.; Beatson, Scott A.

2014-01-01

254

Genome Analysis of Bovine-Mastitis-Associated Escherichia coli O32:H37 Strain P4  

PubMed Central

Escherichia coli is a major pathogen of bovine intramammary infections. Here we report the first draft of the genome sequence of the E. coli O32:H37 P4 strain, which is widely used in experimental bovine mastitis studies.

Sela, Noa; Heller, Elimelech D.; Sela, Shlomo; Leitner, Gabriel

2012-01-01

255

Identification by DNA Hybridization of Enterotoxigenic Escherichia coli in a Longitudinal Study of Villages in Thailand.  

National Technical Information Service (NTIS)

Radiolabeled genes for enterotoxins were used to study the epidemiology of enterotoxigenic Escherichia coli (ETEC) infections in Thai villages. When E. coli isolated from 674 specimens were fixed on nitrocellulose paper, and examined for hybridization wit...

P. Echeverria J. Seriwatana D. N. Taylor C. Tirapat W. Chaicumpa

1985-01-01

256

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

PubMed

Feedlot pen soil is a source for transmission of Escherichia coli O157:H7, and therefore a target for preharvest strategies to reduce this pathogen in cattle. The objective of this study was to determine the ability of soil solarization to reduce E. coli O157:H7 in feedlot surface material (FSM). A feedlot pen was identified in which naturally occurring E. coli O157:H7 was prevalent and evenly distributed in the FSM. Forty plots 3 by 3 m were randomly assigned such that five plots of each of the solarization times of 0, 1, 2, 3, 4, 6, 8, and 10 weeks were examined. Temperature loggers were placed 7.5 cm below the surface of each plot, and plots to be solarized were covered with clear 6-mil polyethylene. At each sampling time, five FSM samples were collected from each of five solarized and five unsolarized plots. E. coli concentrations and E. coli O157:H7 presence by immunomagnetic separation and plating were determined for each FSM sample. Initial percentages of E. coli O157:H7-positive samples in control and solarized FSM were 84 and 80%, respectively, and did not differ (P > 0.05). E. coli O157:H7 was no longer detectable by 8 weeks of solarization, but was still detected in unsolarized FSM at 10 weeks. The average initial concentration of E. coli in FSM was 5.56 log CFU/g and did not differ between treatments (P > 0.05). There was a 2.0-log decrease of E. coli after 1 week of solarization, and a >3.0-log reduction of E. coli by week 6 of solarization (P, 0.05). E. coli levels remained unchanged in unsolarized FSM (P > 0.05). Daily peak FSM temperatures were on average 8.7°C higher for solarized FSM compared with unsolarized FSM, and reached temperatures as high as 57°C. Because soil solarization reduces E. coli O157:H7, this technique may be useful for reduction of persistence and transmission of this pathogen in cattle production, in addition to remediation of E. coli O157:H7-contaminated soil used to grow food crops. PMID:22221349

Berry, Elaine D; Wells, James E

2012-01-01

257

Tobramycin uptake in Escherichia coli is driven by either electrical potential or ATP.  

PubMed Central

Aminoglycoside antibiotics such as streptomycin and tobramycin must traverse the bacterial cytoplasmic membrane prior to initiating lethal effects. Previous data on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis have demonstrated that transport of aminoglycosides is regulated by delta psi, the electrical component of the proton motive force. However, several laboratories have observed that growth of bacterial cells can occur in the apparent absence of delta psi, and we wished to confirm these studies with E. coli and further investigate whether transport of aminoglycosides could occur in the absence of a membrane potential. Treatment of acrA strain CL2 with the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) dissipated delta psi, decreased intracellular ATP levels, and resulted in cessation of growth; after a variable period of time (3 to 7 h), growth resumed, ultimately achieving growth rates comparable to those of untreated cells. Absence of delta psi in these cells was confirmed by absence of [3H]tetraphenyl phosphonium+ uptake as measured by membrane filtration, lack of flagellar motion, and inability of these cells to transport proline (but not methionine). Regrowth was associated with restoration of normal intracellular ATP as measured by luciferin-luciferase bioluminescence assay. Unlike unacclimatized CL2 cells treated with CCCP, these cells transported [3H]tobramycin similarly to untreated cells; aminoglycoside-induced killing was seen in association with transport. These studies suggest that under certain circumstances aminoglycoside transport can be driven by ATP (or other high-energy activated phosphate donors) alone, in the absence of a measurable delta psi. delta uncBC mutants of CL2 incapable of interconverting delta psi and ATP were treated with CCCP, resulting in dissipation of delta psi but no alteration in ATP content. Despite maintenance of normal ATP, there was no transport of [3H] bramycin, confirming that under normal growth conditions ATP has no role in the transport of aminoglycosides.

Fraimow, H S; Greenman, J B; Leviton, I M; Dougherty, T J; Miller, M H

1991-01-01

258

Method 1603: 'Escherichia coli' (E. coli) in Water by Membrane Filtration Using Modified membrane-Thermotolerant 'Escherichia coli' Agar (mTEC).  

National Technical Information Service (NTIS)

The method describes a revised Escherichia coli membrane filter (MF) procedure, a single-step method that uses one medium, modified mTEC Agar, and does not require the transfer of the membrane filter to another medium or other substrate. The modified medi...

2002-01-01

259

Method 1603: Escherichia coli (E. coli) in Water by Membrane Filtration Using Modified membrane-Thermotolerant Escherichia coli Agar (Modified mTEC), April 2005.  

National Technical Information Service (NTIS)

Method 1603 describes a membrane filter (MF) procedure for the detection and enumeration of Escherichia coli bacteria in ambient waters and disinfected wastewaters. This method is a single-step modification of EPA Method 1103.1 ( mTEC). Unlike the mTEC me...

2005-01-01

260

Method 1103.1: 'Escherichia coli' (E. coli) in Water by Membrane Filtration Using membrane-Thermotolerant 'Escherichia coli' Agar (mTEC).  

National Technical Information Service (NTIS)

This method describes a membrane filter (MF) procedure for the detection and enumeration of Escherichia coli. Because the bacterium is a natural inhabitant only of the intestinal tract of warm-blooded animals, its presence in water samples is an indicatio...

2002-01-01

261

Use of tellurite for the selection of verocytotoxigenic Escherichia coli O157  

Microsoft Academic Search

Summary. Potassium tellurite was assessed for the selection of verocytotoxigenic (VT+) Escherichia coli 01 57. MICs were higher for VT+ E. coli 01 57 than for other strains of E. coli and for Aeromonas spp. MacConkey medium containing sorbitol, tellurite and cefixime (TC- SMAC) permitted the growth of VT+ E. coli 0157 and Shigella sonnei but partially or completely inhibited

P. M. Zadik; P. A. Chapman; C. A. Siddons

1993-01-01

262

Environmental Escherichia coli occur as natural plant growth-promoting soil bacterium  

Microsoft Academic Search

Currently, it is presumed that Escherichia coli is not a normal inhabitant of the soil. Soilborne E. coli strains were isolated from broad range of 7 geoclimatic zones of India, indicating that E. coli can survive and thrive under different extreme soil conditions. Diversity among E. coli strains from widely separated geographic regions using enterobacterial repetitive intergenic consensus (ERIC)-PCR did

Chandra Shekhar Nautiyal; Ateequr Rehman; Puneet Singh Chauhan

2010-01-01

263

Nonthermal atmospheric argon plasma jet effects on Escherichia coli biomacromolecules.  

PubMed

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. PMID:23982422

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

2013-12-01

264

Role of peripheral pooling in porcine Escherichia coli sepsis  

SciTech Connect

In anesthesized pigs the effects of E. coli (2 X 10(8)/kg) on hemodynamics and red cell distribution were studied. After injection of 99m-Tc red cells (15 mCi), regional radioactivity was followed during 3 hours. Gated bloodpool studies were performed to measure end-diastolic volumes (EDV). Escherichia coli E. coli was infused in 14 pigs, while 7 animals served as controls. E. coli resulted in an early increase in pulmonary arterial pressure. Systemic arterial pressure decreased gradually, while cardiac output did not change significantly. The gated studies revealed that especially left ventricular end-diastolic volume (LVEDV) declined, to 50% of the basal value. Regional radioactivity did not change over lungs, liver and abdomen. Splenic activity declined markedly. Over the hindlimb a significant increase (29 +/- 8%) was observed. It is concluded that E. coli infusion in pigs induces a hemodynamic pattern similar to human sepsis. The decrease in LVEDV is probably related to peripheral pooling and a change in right ventricle (RV) performance.

Teule, G.J.; von Lingen, A.; Verwey von Vught, M.A.; Kester, A.D.; Mackaay, R.C.; Bezemer, P.D.; Heidenal, G.A.; Thijs, L.G.

1984-01-01

265

Influence of individual bile acids in Escherichia coli peritonitis.  

PubMed

Previous studies have shown that intraperitoneal bile increases bacterial growth and mortality in Escherichia coli peritonitis in the rat. The purpose of the present study was to determine a) the influence of bile acids (cholic, deoxycholic, or chenodeoxycholic) and bilirubin on survival, bacterial growth, and superoxide release by peritoneal phagocytes in this model, and b) the effect of bile acids on bacterial growth and endotoxin release when incubated with E. coli in vitro. Each of the bile acids aggravated the E. coli peritonitis, with increased bacterial counts in the peritoneal cavity and in blood and increased mortality. Deoxycholic acid was the most deleterious of the bile acids, causing suppression of superoxide release by peritoneal phagocytes, like whole bile. In vitro, bile acids did not seem to affect growth of E. coli, but cholic and deoxycholic acid seemed to enhance the release of endotoxin. It is concluded that the bile acids are responsible for the noxious effect of bile in E. coli peritonitis. It is suggested that the detergent properties of bile acids aggravate the peritonitis by solubilizing the cell membranes of both bacteria and phagocytes. PMID:2177218

Andersson, R; Tranberg, K G; Lillienau, J; Schalén, C; Srinivas, U; Larsson, L; Sonesson, A; Bengmark, S

1990-11-01

266

Comparative Genomic Indexing Reveals the Phylogenomics of Escherichia coli Pathogens  

PubMed Central

The Escherichia coli O26 serogroup includes important food-borne pathogens associated with human and animal diarrheal disease. Current typing methods have revealed great genetic heterogeneity within the O26 group; the data are often inconsistent and focus only on verotoxin (VT)-positive O26 isolates. To improve current understanding of diversity within this serogroup, the genomic relatedness of VT-positive and -negative O26 strains was assessed by comparative genomic indexing. Our results clearly demonstrate that irrespective of virulence characteristics and pathotype designation, the O26 strains show greater genomic similarity to each other than to any other strain included in this study. Our data suggest that enteropathogenic and VT-expressing E. coli O26 strains represent the same clonal lineage and that VT-expressing E. coli O26 strains have gained additional virulence characteristics. Using this approach, we established the core genes which are central to the E. coli species and identified regions of variation from the E. coli K-12 chromosomal backbone.

Anjum, Muna F.; Lucchini, Sacha; Thompson, Arthur; Hinton, Jay C. D.; Woodward, Martin J.

2003-01-01

267

Quinolone accumulation in Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus.  

PubMed Central

The accumulation of quinolones by Escherichia coli JF568, Pseudomonas aeruginosa PAO1, and Staphylococcus aureus ATCC 29213 was measured by a modified fluorometric assay (J. S. Chapman and N. H. Georgopapadakou, Antimicrob. Agents Chemother. 33:27-29, 1989). The quinolones examined were fleroxacin, pefloxacin, norfloxacin, difloxacin, A56620, ciprofloxacin, ofloxacin, and Ro 09-1168. In all three organisms, uptake was complete in less than 5 min and was proportional to extracellular quinolone concentrations between 2 and 50 micrograms/ml, which is consistent with simple diffusion. Washing cells with quinolone-free buffer decreased accumulation by up to 70% in E. coli and P. aeruginosa but not in S. aureus. Similarly, incubation with the uncouplers 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone increased accumulation up to fourfold in E. coli and P. aeruginosa, though not in S. aureus, suggesting endogenous, energy-dependent efflux. High quinolone hydrophobicity was generally associated with decreased accumulation in E. coli and P. aeruginosa (except in the case of pefloxacin) but was associated with increased accumulation in S. aureus (except in the case of difloxacin). Ciprofloxacin had the highest accumulation in E. coli and P. aeruginosa, while pefloxacin had the highest accumulation in S. aureus.

McCaffrey, C; Bertasso, A; Pace, J; Georgopapadakou, N H

1992-01-01

268

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

PubMed Central

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

Han, Mee-Jung; Lee, Sang Yup

2006-01-01

269

Antibiotic Resistance of Escherichia coli Serotypes from Cochin Estuary  

PubMed Central

This study aimed at detecting the prevalence of antibiotic-resistant serotypes of Escherichia coli in Cochin estuary, India. E. coli strains were isolated during the period January 2010–December 2011 from five different stations set at Cochin estuary. Water samples from five different stations in Cochin estuary were collected on a monthly basis for a period of two years. Isolates were serotyped, antibiogram-phenotyped for twelve antimicrobial agents, and genotyped by polymerase chain reaction for uid gene that codes for ?-D-glucuronidase. These E. coli strains from Cochin estuary were tested against twelve antibiotics to determine the prevalence of multiple antibiotic resistance among them. The results revealed that more than 53.33% of the isolates were multiple antibiotic resistant. Thirteen isolates showed resistance to sulphonamides and two of them contained the sul 1 gene. Class 1 integrons were detected in two E. coli strains which were resistant to more than seven antibiotics. In the present study, O serotyping, antibiotic sensitivity, and polymerase chain reaction were employed with the purpose of establishing the present distribution of multiple antibiotic-resistant serotypes, associated with E. coli isolated from different parts of Cochin estuary.

Sukumaran, Divya P.; Durairaj, Srinivasan; Abdulla, Mohamed Hatha

2012-01-01

270

Effect of seawater on Escherichia coli beta-galactosidase activity.  

PubMed

An investigation of beta-galactosidase activity of Escherichia coli strain H10407, under different physiological and environmental conditions, e.g. induced and uninduced osmotic stress, light, etc., was undertaken. In this study E. coli was employed as a model for faecal coliforms in waste water. beta-Galactosidase activity was induced by isopropyl-beta-D-thiogalactoside (IPTG). Enzyme activity (U cell-1)/cell for sewage bacteria and for induced E. coli was similar, i.e. log U cell-1 = -8.5 whereas uninduced E. coli yielded log U cell-1 = -12.1. Initial enzyme activity was not dependent on phase of growth of the cell (exponential vs stationary phase) or whether marine or fresh water at the time of initial dilution. However, osmotic change resulted in a decrease in culturable cells, even though enzyme activity remained constant. A significant decrease in the number of culturable bacteria, followed by a decrease in beta-galactosidase activity, was observed after exposure of cells to visible light radiation. It is concluded that beta-galactosidase enzyme is retained in viable but non-culturable E. coli. Furthermore, beta-galactosidase appears to offer a useful and rapid (25 min) measure of the viability of faecal coliforms, and therefore, of the water quality of bathing and shellfishing areas. PMID:8760326

Pommepuy, M; Fiksdal, L; Gourmelon, M; Melikechi, H; Caprais, M P; Cormier, M; Colwell, R R

1996-08-01

271

The Pangenome Structure of Escherichia coli: Comparative Genomic Analysis of E. coli Commensal and Pathogenic Isolates? †  

PubMed Central

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 ?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.

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

2008-01-01

272

Glucosylation of isoflavonoids in engineered escherichia coli.  

PubMed

A glycosyltransferase, YjiC, from Bacillus licheniformis has been used for the modification of the commercially available isoflavonoids genistein, daidzein, biochanin A and formononetin. The in vitro glycosylation reaction, using UDP-?-D-glucose as a donor for the glucose moiety and aforementioned four acceptor molecules, showed the prominent glycosylation at 4' and 7 hydroxyl groups, but not at the 5(th) hydroxyl group of the A-ring, resulting in the production of genistein 4'-O-?-D-glucoside, genistein 7-O-?-D-glucoside (genistin), genistein 4',7-O-?-D-diglucoside, biochanin A-7-O-?-D-glucoside (sissotrin), daidzein 4'-O-?-D-glucoside, daidzein 7-O-?-D-glucoside (daidzin), daidzein 4', 7-O-?-D-diglucoside, and formononetin 7-O-?-D-glucoside (ononin). The structures of all the products were elucidated using high performance liquid chromatography-photo diode array and high resolution quadrupole time-of-flight electrospray ionization mass spectrometry (HR QTOFESI/MS) analysis, and were compared with commercially available standard compounds. Significantly higher bioconversion rates of all four isoflavonoids was observed in both in vitro as well as in vivo bioconversion reactions. The in vivo fermentation of the isoflavonoids by applying engineered E. coli BL21(DE3)/?pgi?zwf?ushA overexpressing phosphoglucomutase (pgm) and glucose 1-phosphate uridyltransferase (galU), along with YjiC, found more than 60% average conversion of 200 ?M of supplemented isoflavonoids, without any additional UDP-?-D-glucose added in fermentation medium, which could be very beneficial to large scale industrial production of isoflavonoid glucosides. PMID:24599002

Pandey, Ramesh Prasad; Parajuli, Prakash; Koirala, Niranjan; Lee, Joo Ho; Park, Yong Il; Sohng, Jae Kyung

2014-02-01

273

Virulence and antibiotic resistance of Escherichia coli isolated from rooks.  

PubMed

With regard to antibiotic resistance studies in various model animals in the urban environment, the presented study focused on the rook, many behavioural and ecological aspects of which are important from an epidemiological point of view. A total of 130 Escherichia coli strains isolated from rook faeces during a two-year period (2011-2012) were investigated for antibiotic resistance and virulence. Resistance to ampicillin (60%) and streptomycin (40%) were the most frequent, followed by resistance to fluoroquinolones (ciprofloxacin-22% and enrofloxacin-24%), tetracycline (18%), cotrimoxazol (17%) and florfenicol (14%). Ceftiofur resistance occured in 10.7% of strains and cefquinom resistance in 1.5% of strains. Twenty-five E.coli strains with a higher level of MICs of cephalosporins (over 2mg/L of ceftazidime and ceftriaxon) and fluoroquinolones were selected for detection of betalactamase genes (CTX-M, CMY), plasmid-mediated quinolone resistance qnrS, integrase 1, and for APEC (avian pathogenic E.coli) virulence factors (iutA, cvaC, iss, tsh, ibeA, papC, kpsII). Genes of CTX-M1, CMY-2, integrase 1, papC, cvaC, iutA were detected in one strain of E.coli, and qnrS, integrase 1, iss, cvaC, tsh were detected in another E.coli. DNA microarray revealed the absence of verotoxin and enterotoxin genes and pathogenicity islands. The results show that rooks can serve as a reservoir of antibiotic-resistant E. coli with avian pathogenic virulence factors for the human population, and potentially transmit such E.coli over long distances. PMID:23772573

Kmet, Vladimir; Drugdova, Zuzana; Kmetova, Marta; Stanko, Michal

2013-01-01

274

Widespread antibiotic resistance of diarrheagenic Escherichia coli and Shigella species  

PubMed Central

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

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

2014-01-01

275

Strategies for the production of recombinant protein in Escherichia coli.  

PubMed

In the recent past years, a large number of proteins have been expressed in Escherichia coli with high productivity due to rapid development of genetic engineering technologies. There are many hosts used for the production of recombinant protein but the preferred choice is E. coli due to its easier culture, short life cycle, well-known genetics, and easy genetic manipulation. We often face a problem in the expression of foreign genes in E. coli. Soluble recombinant protein is a prerequisite for structural, functional and biochemical studies of a protein. Researchers often face problems producing soluble recombinant proteins for over-expression, mainly the expression and solubility of heterologous proteins. There is no universal strategy to solve these problems but there are a few methods that can improve the level of expression, non-expression, or less expression of the gene of interest in E. coli. This review addresses these issues properly. Five levels of strategies can be used to increase the expression and solubility of over-expressed protein; (1) changing the vector, (2) changing the host, (3) changing the culture parameters of the recombinant host strain, (4) co-expression of other genes and (5) changing the gene sequences, which may help increase expression and the proper folding of desired protein. Here we present the resources available for the expression of a gene in E. coli to get a substantial amount of good quality recombinant protein. The resources include different strains of E. coli, different E. coli expression vectors, different physical and chemical agents and the co expression of chaperone interacting proteins. Perhaps it would be the solutions to such problems that will finally lead to the maturity of the application of recombinant proteins. The proposed solutions to such problems will finally lead to the maturity of the application of recombinant proteins. PMID:23897421

Gopal, Gopal Jee; Kumar, Awanish

2013-08-01

276

Attaching-effacing Escherichia coli infections in cattle.  

PubMed

Diarrheagenic Escherichia coli are now broadly placed into 6 classes based on virulence mechanisms. One of these classes, enterotoxigenic E coli, is the most common cause of diarrhea in beef and dairy calves in the first 4 days of life. Two other diarrheagenic classes, enterohemorrhagic E coli (EHEC) and enteropathogenic E coli (EPEC), are important causes of disease in human beings, but less well substantiated causes of diarrhea in calves. E coli strains that cause hemorrhagic colitis and hemolytic uremic syndrome in humans, express high levels of Shiga toxin, cause attaching-effacing (A/E) lesions in intestinal epithelial cells, and possess a specific 60-MDa EHEC plasmid are known as EHEC. One feature EHEC and EPEC have in common is the causation of intestinal epithelial lesions known as attaching and effacing (A/E). Attaching-effacing E coli (AEEC) is a designation for those E coli strains known to cause A/E lesions or at least carry the genes for this trait, and therefore include organisms that fall into either the EHEC or EPEC classes. Because cattle are carriers of many different serotypes of EHEC, much emphasis has been placed on the public health and food safety concerns associated with the fecal shedding of these organisms. However, much less emphasis has been given to their roles as diarrheagenic pathogens of cattle. The goal of this article is to address the question of pathogenicity, with a review that focuses on the results of studies of natural and experimental infections with these organisms. The authors conclude that there is overwhelming evidence that many different serogroups of AEEC are diarrheagenic pathogens of calves. PMID:20117541

Moxley, Rodney A; Smith, David R

2010-03-01

277

Phenotypic and molecular characterization of clinically isolated Escherichia coli.  

PubMed

All diarrheagenic Escherichia coli carry at least one virulence-related property. Stool samples from 244 patients having acute or persistent diarrhea received after the exclusion of routine enteropathogens were investigated. Purely or predominantly isolated E. coli (n = 100) were subjected to serotyping, of which only 25 were typable. They belonged to 14 different O-serogroups comprising 5 O153, 4 O102, 3 O25, 2 each of O130 and O169, and 1 each of O1, O8, O15, O37, O86, O101, O127, O143, and O160. The typable E. coli isolates along with 5 other untypable isolates were investigated for molecular markers, such as intimin (eae), enterohemolysin (EhlyA), a-hemolysin, heat-labile enterotoxins (LT), heat-stable enterotoxins (STa), verotoxins (VT1 and VT2), invasivity (ial), enteroaggregative E. coli (EAEC) gene (EAGG), and enterotoxin (EAST). Two of the isolates (O153 and O86) were positive for enterohemolysin phenotypically and 5 for beta-hemolysin both phenotypically and genotypically. Interestingly, 16.6% of the randomly isolated E. coli were O153, a serogroup common in cattle, and 10% belonged to EAEC pathotype of which two-thirds had the EAST gene, which is quite frequent in these strains. Additionally, there was one strain (O153) that was positive for EAST only. Between the two 0130:H6 strains isolated, one belonged to EAEC serogroup. None of the E. coli isolated were positive for verotoxins, eae, LT1, STa, and ial. Data obtained emphasize the need for additional research into the role of eae gene and other putative factors affecting the virulence of diarrheagenic E. coli in India. PMID:20699512

Vaishnavi, Chetana; Kaur, Sukhminderjit; Beutin, Lothar; Krueger, Ulrike

2010-01-01

278

Role of Enteroaggregative Escherichia coli Virulence Factors in Uropathogenesis  

PubMed Central

A multiresistant clonal Escherichia coli O78:H10 strain qualifying molecularly as enteroaggregative Escherichia coli (EAEC) was recently shown to be the cause of a community-acquired outbreak of urinary tract infection (UTI) in greater Copenhagen, Denmark, in 1991. This marks the first time EAEC has been associated with an extraintestinal disease outbreak. Importantly, the outbreak isolates were recovered from the urine of patients with symptomatic UTI, strongly implying urovirulence. Here, we sought to determine the uropathogenic properties of the Copenhagen outbreak strain and whether these properties are conferred by the EAEC-specific virulence factors. We demonstrated that through expression of aggregative adherence fimbriae, the principal adhesins of EAEC, the outbreak strain exhibited pronouncedly increased adherence to human bladder epithelial cells compared to prototype uropathogenic strains. Moreover, the strain was able to produce distinct biofilms on abiotic surfaces, including urethral catheters. These findings suggest that EAEC-specific virulence factors increase uropathogenicity and may have played a significant role in the ability of the strain to cause a community-acquired outbreak of UTI. Thus, inclusion of EAEC-specific virulence factors is warranted in future detection and characterization of uropathogenic E. coli.

Boll, Erik J.; Struve, Carsten; Boisen, Nadia; Olesen, Bente; Stahlhut, Steen G.

2013-01-01

279

Mutants of Escherichia coli Variably Resistant to Bacteriophage T11  

PubMed Central

Carta, Guy R. (Rutgers, The State University, New Brunswick, N.J.), and Vernon Bryson. Mutants of Escherichia coli variably resistant to bacteriophage T1. J. Bacteriol. 92:1055–1061. 1966.—Mutants resistant to bacteriophage T1 were isolated from ultraviolet (UV)-irradiated cultures of Escherichia coli B/r, a UV-resistant variant. Bacterial populations derived from some of these mutants were partially but not completely resistant to the bacteriophage. Such mutants, designated variably resistant (B/r/1v), could not be obtained from E. coli B. Phage-free mutant populations taken from different stages in growth consisted of significantly different proportions of T1-resistant and T1-sensitive cells. The growth stage-dependent range of variation exceeded 1,000-fold. In broth cultures, the highest proportion of resistant cells consistently appeared at mid-log phase, and the highest proportion of sensitive cells at lag and stationary phases. Comparable evidence for environmentally dependent changes in host-cell phenotype was obtained by efficiency of plating and cloning efficiency analysis tests. Micromanipulation showed that, in clones growing in the presence of phage T1, sensitive bacteria appeared with high frequency and underwent lysis. Images

Carta, Guy R.; Bryson, Vernon

1966-01-01

280

Production and Characteristics of Hemolysins of Escherichia coli  

PubMed Central

Snyder, Irvin S. (University of Iowa, Iowa City), and Nancy A. Koch. Production and characteristics of hemolysins of Escherichia coli. J. Bacteriol. 91:763–767. 1996.—Filterable and nonfilterable hemolysins were produced by Escherichia coli in beef-heart infusion, casein hydrolysate, and chemically defined media. Differences were found among the three media in the time of appearance and in the relationship between production of these two hemolysins. The nonfilterable hemolysin produced in the three media, as well as the filterable hemolysin produced in the beef-heart infusion medium, were destroyed in 1 hr at 56 C. The filterable hemolysin produced in the casein hydrolysate and chemically defined media was unaffected by exposure to 56 C for 1 hr. Formalin inactivated the hemolysins produced in all three media. The optimal pH for activity of the nonfilterable hemolysin varied with time of production, whereas the optimal pH for the filterable hemolysin was constant. Certain carbohydrates were required for the production of filterable hemolysin by E. coli grown in casein hydrolysate and chemically defined media.

Snyder, Irvin S.; Koch, Nancy A.

1966-01-01

281

Posttranslational Modifications of Ribosomal Proteins in Escherichia coli  

PubMed Central

? 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. ?-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.

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

2011-01-01

282

Characterization of UrinaryEscherichia coliO75 Strains  

Microsoft Academic Search

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:H2(18 strains), O75:K95:H2(10 strains), O75:K95:H5 (7 strains), O75:K100:H5 (4 strains), and O75:K2:H55 (5 strains). Generally, biotyping proved to

WOLFGANG NIMMICH; WOLFGANG VOIGT; ANDGUNTRAM SELTMANN

283

Rapid and Simple Determination of the Escherichia coli Phylogenetic Group  

PubMed Central

Phylogenetic analysis has shown that Escherichia coli is composed of four main phylogenetic groups (A, B1, B2, and D) and that virulent extra-intestinal strains mainly belong to groups B2 and D. Actually, phylogenetic groups can be determined by multilocus enzyme electrophoresis or ribotyping, both of which are complex, time-consuming techniques. We describe a simple and rapid phylogenetic grouping technique based on triplex PCR. The method, which uses a combination of two genes (chuA and yjaA) and an anonymous DNA fragment, was tested with 230 strains and showed excellent correlation with reference methods.

Clermont, Olivier; Bonacorsi, Stephane; Bingen, Edouard

2000-01-01

284

Construction of synthetic gene circuits in the Escherichia coli genome.  

PubMed

The construction of stable and functional synthetic circuits in bacteria is necessary in the areas of systems and synthetic biology. The common approach using plasmids to carry foreign genetic circuits offers convenience in genetic construction but is poor in genetic stability (e.g., variation in copy number). Genome recombination provides the stable genetic maintenance of synthetic circuits, but is often labor intensive and time consuming when the genetic circuits are complex and the DNA fragments become larger. The method introduced here is modified from that reported by Wanner's group and is available for integration of complex genetic circuits into the Escherichia coli chromosome. PMID:23996446

Ying, Bei-Wen; Akeno, Yuya; Yomo, Tetsuya

2013-01-01

285

Unique and overlapping pollutant stress proteins of Escherichia coli  

SciTech Connect

Exposure of growing batch cultures of Escherichia coli to nine different model micropollutants' (benzene, cadmium chloride, chlorpyrivos, 2,4-dichloroaniline, dioctylphthalate, hexachlorobenzene, pentachlorophenol, trichloroethylene, and tetrapropylbenzosulfonate) led to the induction of 13 to 39 proteins, as analyzed by two-dimensional gel electrophoresis. Some of these proteins overlapped with heat shock and carbon starvation proteins, but at least 50% were unique to a given chemical. The stress protein induction showed a temporal pattern, indicating sequential gene expression. Chemical stress protein synthesis occurred even at concentrations that had no effect on growth. Thus, the synthesis of these proteins can be a sensitive index of stress and the nature of environmental pollution.

Blom, A.; Harder, W. (TNO Inst. of Environmental Sciences, Delft (Netherlands)); Matin, A. (Stanford Univ., CA (United States))

1992-01-01

286

Bacteriophage Mu DNA circularizes following infection of Escherichia coli.  

PubMed Central

Mu DNA, isolated from infected cells or minicells, has been shown to be held by proteins in twisted and open circular forms. Circularization does not require protein synthesis in the infected cells. A 64,000-dalton polypeptide is injected into the infected cell with Mu DNA and co-sediments with Mu DNA through sucrose gradients. Circularization of the infecting Mu DNA does not require removal of the Escherichia coli DNA sequences which are attached to both ends of the Mu genome in the viral particle. Images Fig. 3. Fig. 4.

Puspurs, A H; Trun, N J; Reeve, J N

1983-01-01

287

Microcin 25, a novel antimicrobial peptide produced by Escherichia coli.  

PubMed Central

Microcin 25, a peptide antibiotic excreted by an Escherichia coli strain isolated from human feces, was purified to homogeneity and characterized. Composition analysis and data from gel filtration indicated that microcin 25 may contain 20 amino acid residues. It has a blocked amino-terminal end. Microcin synthesis and immunity are plasmid determined, and the antibiotic was produced in minimal medium when the cultures entered the stationary phase of growth. The peptide appears to interfere with cell division, since susceptible cells filamented when exposed to it. This response does not seem to be mediated by the SOS system. Images

Salomon, R A; Farias, R N

1992-01-01

288

Production of human prolyl 4-hydroxylase in Escherichia coli  

Microsoft Academic Search

Abstract Prolyl 4-hydroxylase (P4H) catalyzes the post-translational hydroxylationof proline residues in collagen strands. The enzyme,is an,22tetramer,in which the,subunits,contain the catalytic active sites and the,subunits,(protein disulWde isomerase) maintain the,subunits,in a soluble and active conformation. Heterologous,production,of the native,22tetramer,is challenging and had not been reported previously in a prokaryotic system. Here, we describe the production of active human P4H tetramer in Escherichia coli

Elizabeth A. Kersteen; Joshua J. Higgin; Ronald T. Raines

289

Multiple defects in Escherichia coli mutants lacking HU protein.  

PubMed Central

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, or to carry out transposition. Images

Huisman, O; Faelen, M; Girard, D; Jaffe, A; Toussaint, A; Rouviere-Yaniv, J

1989-01-01

290

Studies on the substrate specificity of Escherichia coli galactokinase.  

PubMed

In vitro glycorandomization (IVG) technology is dependent upon the ability to rapidly synthesize sugar phosphates. Compared with chemical synthesis, enzymatic (kinase) routes to sugar phosphates would be attractive for this application. This work focuses upon the development of a high-throughput colorimetric galactokinase (GalK) assay and its application toward probing the substrate specificity and kinetic parameters of Escherichia coli GalK. The demonstrated dinitrosalicylic assay should also be generally applicable to a variety of sugar-processing enzymes. [reaction: see text] PMID:12816414

Yang, Jie; Fu, Xun; Jia, Qiang; Shen, Jie; Biggins, John B; Jiang, Jiqing; Zhao, Jingjing; Schmidt, Joshua J; Wang, Peng G; Thorson, Jon S

2003-06-26

291

Escherichia coli membrane proteins with an affinity for deoxyribonucleic acid.  

PubMed Central

From the membrane fraction of Escherichia coli K-12 strain, four protein fractions (peaks I, IIa, IIb, and III) which have affinity for deoxyribonucleic acid (DNA) have been isolated. The molecular weights of these proteins are between 12,000 and 8,000. Only the peak III fraction contains a protein that binds preferentially to single-stranded DNA, whereas the others contain proteins that bind also to double-stranded DNA. The binding activity of the peak IIb protein is inhibited in the presence of polyuridylic acid. Peak I and peak IIa protein fractions behave like hydrophobic proteins.

Kohiyama, M; Kollek, R; Goebel, W; Kepes, A

1977-01-01

292

Transcription factor distribution in Escherichia coli: studies with FNR protein  

PubMed Central

Using chromatin immunoprecipitation (ChIP) and high-density microarrays, we have measured the distribution of the global transcription regulator protein, FNR, across the entire Escherichia coli chromosome in exponentially growing cells. Sixty-three binding targets, each located at the 5? end of a gene, were identified. Some targets are adjacent to poorly transcribed genes where FNR has little impact on transcription. In stationary phase, the distribution of FNR was largely unchanged. Control experiments showed that, like FNR, the distribution of the nucleoid-associated protein, IHF, is little altered when cells enter stationary phase, whilst RNA polymerase undergoes a complete redistribution.

Grainger, David C.; Aiba, Hirofumi; Hurd, Douglas; Browning, Douglas F.; Busby, Stephen J. W.

2007-01-01

293

Metabolic Engineering for Advanced Biofuels Production from Escherichia coli  

PubMed Central

Summary Global energy and environmental problems have stimulated increasing efforts towards synthesizing liquid biofuels as transportation energy. Compared to the traditional biofuel, ethanol, advanced biofuels should offer advantages such as higher energy density, lower hygroscopicity, lower vapor pressure, and compatibility with existing transportation infrastructure. However, these fuels are not synthesized economically using native organisms. Metabolic engineering offers an alternative approach in which synthetic pathways are engineered into user friendly hosts for the production of these fuel molecules. These hosts could be readily manipulated to improve the production efficiency. This review summarizes recent progress in the engineering of Escherichia coli to produce advanced biofuels.

Atsumi, Shota; Liao, James C.

2008-01-01

294

L Tyrosine production by deregulated strains of Escherichia coli  

Microsoft Academic Search

The excretion of the aromatic amino acid l-tyrosine was achieved by manipulating three gene targets in the wild-type Escherichia coli K12: The feedback-inhibition-resistant (fbr) derivatives of aroG and tyrA were expressed on a low-copy-number vector, and the TyrR-mediated regulation of the aromatic amino acid biosynthesis was\\u000a eliminated by deleting the tyrR gene. The generation of this l-tyrosine producer, strain T1,

Tina Lütke-Eversloh; Gregory Stephanopoulos

2007-01-01

295

Characterization of genes associated with internalization of enteroaggregative Escherichia coli.  

PubMed

On animal models enteroaggregative Escherichia coli (EAEC) can cause mild, but significant mucosal damage, suggesting the invasive capability of these strains. In the study we investigated the ability of typical, aggR-positive and atypical, aggR-negative EAEC isolates to enter intestinal epithelial Int407 cells in relation to the distribution of genes encoding the putative invasins described among pathogenic E. coli categories. The results demonstrated that regardless of origin and affiliation to typical and atypical EAEC, most isolates examined were internalized by the epithelial cells to different extent. Although as many as 50 (84.3%) EAEC demonstrated a variety of combinations of the aggB, afaD, ipaH and tia genes determined, there was no correlation between the invasion efficiency of these strains and the presence of any particular gene involved in invasion. Most of EAEC examined belonged to phylogenetic group B2 and D. PMID:21241791

Sobieszcza?ska, Beata; Duda, Anna Krystyna; Turniak, Micha?; Duda-Madej, Anna; Franiczek, Roman; Kasprzykowska, Urszula

2011-01-01

296

Global Analysis of Extracytoplasmic Stress Signaling in Escherichia coli  

PubMed Central

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

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

2009-01-01

297

Primary structure of the Escherichia coli ribonucleoside diphosphate reductase operon.  

PubMed Central

The nucleotide sequence of the Escherichia coli K-12 DNA comprising the operon for the structural genes of the subunits of ribonucleotide diphosphate reductase has been determined. The DNA sequenced maps at 48.5 minutes on the E. coli chromosome and includes a total length of 8557 nucleotides. An open reading frame between nucleotides 3506 and 5834, encoding a 776-amino acid polypeptide chain with a molecular weight of 87,532, has been identified as the nrdA gene. An open reading frame between nucleotides 6012 and 7139, encoding a 375-amino acid polypeptide with a molecular weight of 43,466, has been identified as the nrdB gene. The sequences reveal not only the primary structures for both subunits, but also some interesting aspects of potential regulatory sites.

Carlson, J; Fuchs, J A; Messing, J

1984-01-01

298

The structure and domain organization of Escherichia coli isocitrate lyase.  

PubMed

Enzymes of the glyoxylate-bypass pathway are potential targets for the control of many human diseases caused by such pathogens as Mycobacteria and Leishmania. Isocitrate lyase catalyses the first committed step in this pathway and the structure of this tetrameric enzyme from Escherichia coli has been determined at 2.1 A resolution. E. coli isocitrate lyase, like the enzyme from other prokaryotes, is located in the cytoplasm, whereas in plants, protozoa, algae and fungi this enzyme is found localized in glyoxysomes. Comparison of the structure of the prokaryotic isocitrate lyase with that from the eukaryote Aspergillus nidulans reveals a different domain structure following the deletion of approximately 100 residues from the larger eukaryotic enzyme. Despite this, the active sites of the prokaryotic and eukaryotic enzymes are very closely related, including the apparent disorder of two equivalent segments of the protein that are known to be involved in a conformational change as part of the enzyme's catalytic cycle. PMID:11526312

Britton, K L; Abeysinghe, I S; Baker, P J; Barynin, V; Diehl, P; Langridge, S J; McFadden, B A; Sedelnikova, S E; Stillman, T J; Weeradechapon, K; Rice, D W

2001-09-01

299

Impact of cranberry on Escherichia coli cellular surface characteristics.  

PubMed

The anti-adhesive effects of cranberry have been attributed to both interactions of its components with the surface of bacterial cells and to inhibition of p-fimbriae expression. Previous reports also suggested that the presence of cranberry juice changed the Gram stain characteristics of Escherichia coli. Here, we show that the morphology of E. coli is changed when grown in the presence of juice or extract from Vaccinium macrocarpon (cranberry). Gene expression analysis indicates the down regulation of flagellar basal body rod and motor proteins. Consistent with this finding and previous reports, the SEM images indicate a decrease in the visible p-fimbriae. The iodine used in Gram-staining protocols was found to interact differently with the bacterial membrane when cells were cultured in spiked media. Slight alterations in the Gram stain protocol demonstrated that culturing in the presence of cranberry juice does not change the Gram stain characteristics contradicting other reports. PMID:18957286

Johnson, Brandy J; Lin, Baochuan; Dinderman, Michael A; Rubin, Robert A; Malanoski, Anthony P; Ligler, Frances S

2008-12-19

300

Impact of cranberry on Escherichia coli cellular surface characteristics  

SciTech Connect

The anti-adhesive effects of cranberry have been attributed to both interactions of its components with the surface of bacterial cells and to inhibition of p-fimbriae expression. Previous reports also suggested that the presence of cranberry juice changed the Gram stain characteristics of Escherichia coli. Here, we show that the morphology of E. coli is changed when grown in the presence of juice or extract from Vaccinium macrocarpon (cranberry). Gene expression analysis indicates the down regulation of flagellar basal body rod and motor proteins. Consistent with this finding and previous reports, the SEM images indicate a decrease in the visible p-fimbriae. The iodine used in Gram-staining protocols was found to interact differently with the bacterial membrane when cells were cultured in spiked media. Slight alterations in the Gram stain protocol demonstrated that culturing in the presence of cranberry juice does not change the Gram stain characteristics contradicting other reports.

Johnson, Brandy J. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Code 6900, Washington, DC 20375 (United States)], E-mail: brandy.white@nrl.navy.mil; Lin Baochuan; Dinderman, Michael A. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Code 6900, Washington, DC 20375 (United States); Rubin, Robert A. [Independent Researcher, 8620 Portafino Place, Whittier, CA 90603 (United States); Malanoski, Anthony P.; Ligler, Frances S. [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Ave SW, Code 6900, Washington, DC 20375 (United States)

2008-12-19

301

Biocatalytically active silCoat-composites entrapping viable Escherichia coli.  

PubMed

Application of whole cells in industrial processes requires high catalytic activity, manageability, and viability under technical conditions, which can in principle be accomplished by appropriate immobilization. Here, we report the identification of carrier material allowing exceptionally efficient adsorptive binding of Escherichia coli whole cells hosting catalytically active carbonyl reductase from Candida parapsilosis (CPCR2). With the immobilizates, composite formation with both hydrophobic and hydrophilized silicone was achieved, yielding advanced silCoat-material and HYsilCoat-material, respectively. HYsilCoat-whole cells were viable preparations with a cell loading up to 400 mg(E. coli)?·?g(-1)(carrier) and considerably lower leaching than native immobilizates. SilCoat-whole cells performed particularly well in neat substrate exhibiting distinctly increased catalytic activity. PMID:24257838

Findeisen, A; Thum, O; Ansorge-Schumacher, M B

2014-02-01

302

Action of low-intensity laser radiation on Escherichia coli  

SciTech Connect

The review deals with quantitative laws of monochromatic visible light action on the cellular level, as well as with the primary photoacceptors and possible light signal transduction chains in bacterial cell Escherichia coli WP2 trp-. Experiments described in this paper are a part of experimental work performed for explaining the molecular mechanism of low-intensity laser therapy. The existence of certain parameters of light (dose, intensity, pulse repetition rate, monochromaticity within the absorbtion bandwidth of biomolecules) for stimulation of E. coli WP2 metabolism has been established. The necessity for a certain physiological state of bacteria cells sensitive to irradiation has been shown. The sensitivity of bacteria to irradiation with monochromatic visible light has been proposed to be a delta pH-dependent genetic process. 115 refs.

Tiphlova, O.; Karu, T. (Laser Technology Center of U.S.S.R. Academy of Sciences, Moscow (USSR))

1991-01-01

303

Expression of a proline-enriched protein in Escherichia coli  

SciTech Connect

The feasibility of expressing repeated synthetic codons in bacterial cells was demonstrated by showing that repeated codons for proline were expressed in Escherichia coli. Recombinant DNA technology was used to clone synthetic polydeoxyguanylate: polydeoxycytidylate into the PstI site of plasmid pBR322. Recombinant plasmid pGC139 was shown by means of HaeIII restriction digestion to contain approximately 41 cloned base pairs; the cloned sequence was expressed as a fusion to an ampicillinase protein. The resulting protein, enriched in proline, was expressed from plasmid in pGC139 in E. coli maxicells. Extension of this technology could lead to improvement in the production of amino acids and to nutritional enrichment of single-cell protein. (Refs. 12).

Kangas, T.T.; Cooney, C.L.; Gomez, R.F.

1982-03-01

304

Reconstitution of the Mycobacterium tuberculosis pupylation pathway in Escherichia coli  

PubMed Central

Prokaryotic ubiquitin-like protein (Pup) is a post-translational modifier that attaches to more than 50 proteins in Mycobacteria. Proteasome accessory factor A (PafA) is responsible for Pup conjugation to substrates, but the manner in which proteins are selected for pupylation is unknown. To address this issue, we reconstituted the pupylation of model Mycobacterium proteasome substrates in Escherichia coli, which does not encode Pup or PafA. Surprisingly, Pup and PafA were sufficient to pupylate at least 51 E. coli proteins in addition to the mycobacterial proteins. These data suggest that pupylation signals are intrinsic to targeted proteins and might not require Mycobacterium-specific cofactors for substrate recognition by PafA in vivo.

Cerda-Maira, Francisca A; McAllister, Fiona; Bode, Nadine J; Burns, Kristin E; Gygi, Steven P; Darwin, K Heran

2011-01-01

305

Mutational Analysis of UMP Kinase from Escherichia coli  

PubMed Central

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).

Bucurenci, Nadia; Serina, Lidia; Zaharia, Cristina; Landais, Stephanie; Danchin, Antoine; Barzu, Octavian

1998-01-01

306

Purification and Characterization of Escherichia coli MreB Protein*  

PubMed Central

The actin homolog MreB is required in rod-shaped bacteria for maintenance of cell shape and is intimately connected to the holoenzyme that synthesizes the peptidoglycan layer. The protein has been reported variously to exist in helical loops under the cell surface, to rotate, and to move in patches in both directions around the cell surface. Studies of the Escherichia coli protein in vitro have been hampered by its tendency to aggregate. Here we report the purification and characterization of native E. coli MreB. The protein requires ATP hydrolysis for polymerization, forms bundles with a left-hand twist that can be as long as 4 ?m, forms sheets in the presence of calcium, and has a critical concentration for polymerization of 1.5 ?m.

Nurse, Pearl; Marians, Kenneth J.

2013-01-01

307

Primary structure of the Escherichia coli ribonucleotide diphosphate reductase operon  

SciTech Connect

The nucleotide sequence of the Escherichia coli K-12 DNA comprising the operon for the structural genes of the subunits of ribonucleotide diphosphate reductase has been determined. The DNA sequenced maps at 48.5 minutes on the E. coli chromosome and includes a total length of 8557 nucleotides. An open reading frame between nucleotides 3506 and 5834, encoding a 776-amino acid polypeptide chain with a molecular weight of 87,532, has been identified as the nrdA gene. An open reading frame between nucleotides 6012 and 7139, encoding a 375-amino acid polypeptide with a molecular weight of 43,466, has been identified as the nrdB gene. The sequences reveal not only the primary structures for both subunits, but also some interesting aspects of potential regulatory sites. 25 references, 2 figures, 1 table.

Carlson, J.; Fuchs, J.A.; Messing, J.

1984-07-01

308

Primary structure of the Escherichia coli ribonucleoside diphosphate reductase operon  

SciTech Connect

The nucleotide sequence of the Escherichia coli K-12 DNA comprising the operon for the structural genes of the subunits of ribonucleotide diphosphate reductase has been determined. The DNA sequenced maps at 48.5 minutes on the E. coli chromosome and includes a total length of 8557 nucleotides. An open reading frame between nucleotides 3506 and 5834, encoding a 776-amino acid polypeptide chain with a molecular weight of 87,532, has been identified as the nrdA gene. An open reading frame between nucleotides 6012 and 7139, encoding a 375-amino acid polypeptide with a molecular weight of 43,466, has been identified as the nrdB gene. The sequences reveal not only the primary structures for both subunits, but also some interesting aspects of potential regulatory sites. 25 references, 2 figures, 1 table.

Carlson, J.; Fuchs, J.A.; Messing, J.

1984-07-01

309

[Overproduction of noncanonical amino acids by Escherichia coli cells].  

PubMed

Overproduction of noncanonical amino acids norvaline and norleucine by Escherichia coli with inactivated acetohydroxy acid synthases was demonstrated. The cultivation conditions for the overproduction of noncanonical amino acids were studied. The effect of the restoration of acetohydroxy acid synthase activity, increased expression of the leuABCD operon, and inactivation of the biosynthetic threonine deaminase on norvaline and norleucine synthesis was studied. When grown under valine limitation, E. coli cells with inactivated acetohydroxy acid synthases and an elevated level of expression of the valine operon were shown to accumulate norvaline and norleucine (up to 0.8 and 4 g/l, respectively). These results confirm the existing hypothesis of norvaline and norleucine formation from 2-ketobutyrate by leucine biosynthesis enzymes. PMID:18297871

Sycheva, E V; Iampol'skaia, T A; Preobrazhenskaia, E S; Novikova, A E; Matrosov, N G; Sto?nova, N V

2007-01-01

310

Examining the feasibility of bulk commodity production in Escherichia coli.  

PubMed

Escherichia coli is currently used by many research institutions and companies around the world as a platform organism for the development of bio-based production processes for bulk biochemicals. A given bulk biochemical bioprocess must be economically competitive with current production routes. Ideally the viability of each bioprocess should be evaluated prior to commencing research, both by metabolic network analysis (to determine the maximum theoretical yield of a given biocatalyst) and by techno-economic analysis (TEA; to determine the conditions required to make the bioprocess cost-competitive). However, these steps are rarely performed. Here we examine theoretical yields and review available TEA for bulk biochemical production in E. coli. In addition, we examine fermentation feedstocks and review recent strain engineering approaches to achieve industrially-relevant production, using examples for which TEA has been performed: ethanol, poly-3-hydroxybutyrate, and 1,3-propanediol. PMID:22160295

Vickers, Claudia E; Klein-Marcuschamer, Daniel; Krömer, Jens O

2012-04-01

311

Escherichia coli Mutants that Synthesize Dephosphorylated Lipid A Molecules  

PubMed Central

The lipid A moiety of Escherichia coli lipopolysaccharide is a hexa-acylated disaccharide of glucosamine that is phosphorylated at the 1 and 4? positions. Expression of the Francisella novicida lipid A 1-phosphatase FnLpxE in E. coli results in dephosphorylation of the lipid A proximal unit. Co-expression of FnLpxE and the Rhizobium leguminosarum lipid A oxidase RlLpxQ in E. coli converts much of the proximal glucosamine to 2-amino-2-deoxy-gluconate. Expression of the F. novicida lipid A 4?-phosphatase FnLpxF in wild-type E. coli has no effect because FnLpxF cannot dephosphorylate hexa-acylated lipid A. However, expression of FnLpxF in E. coli lpxM mutants, which synthesize penta-acylated lipid A lacking the secondary 3?-myristate chain, causes extensive 4?-dephosphorylation. Co-expression of FnLpxE and FnLpxF in lpxM mutants results in massive accumulation of lipid A species lacking both phosphate groups, and introduction of RlLpxQ generates phosphate-free lipid A variants containing 2-amino-2-deoxy-gluconate. The proposed lipid A structures were confirmed by electrospray ionization mass spectrometry. Strains with 4?-dephosphorylated lipid A display increased polymyxin resistance. Heptose-deficient mutants of E. coli lacking both the 1- and 4?-phosphate moieties are viable on plates but sensitive to CaCl2. Our methods for re-engineering lipid A structure may be useful for generating novel vaccines and adjuvants.

Ingram, Brian O.; Masoudi, Ali; Raetz, Christian R. H.

2010-01-01

312

Effect of various nonionic surfactants on growth of Escherichia coli.  

PubMed

Rose, Michael J., Jr. (Veterans Administration Hospital, Washington, D.C.), Stephen A. Aron, and Bernard W. Janicki. Effect of various nonionic surfactants on growth of Escherichia coli. J. Bacteriol. 91:1863-1868. 1966.-Escherichia coli cultivated in media containing 0.5, 1.0, 2.0, or 4.0% concentrations of surface-active polyoxyethylene derivatives of formaldehyde polymers of octyl phenol (Triton WR-1339; Macrocyclon) or of sorbitan mono-fatty acid esters (Tween 20, 40, 60, and 80) exhibited significantly retarded growth only at the highest concentration. To determine the mechanism of bacteriostasis, certain derivatives and compounds related to the surfactants were investigated. Experiments with compounds related to the Triton-type agents demonstrated that incorporation of monomeric substances (Triton X-205, X-305, Igepal CA-730, or Dowfax 9N20) into the medium at a concentration of 4.0% did not inhibit the growth of E. coli. It was concluded that the formaldehyde polymer was essential for growth inhibition by the polyoxyethylene derivatives of octyl phenol. The inhibitory activity of the Tween compounds, in contrast, appeared to result from the unesterified fatty acids which contaminate the commercial preparations. Polyol (60), the sorbitan polyoxyethylene derivative of Tween 60 and the basic structural unit of all the Tween-type compounds, and a Tween 80 preparation which was purified by extraction of the unesterified oleic acid, were not inhibitory. Moreover, the amount of free oleic acid present as a contaminant of Tween 80 was found to be sufficient to cause significant growth inhibition. These results and the observation that E. coli does not appear to hydrolyze the esterified fatty acid of Tween 80 led to the conclusion that growth inhibition obtained with various Tween compounds probaby is a function of their respective fatty acid contaminants. PMID:5327909

Rose, M J; Aron, S A; Janicki, B W

1966-05-01

313

Characterization of human interleukin 2 derived from Escherichia coli.  

PubMed Central

Interleukin 2 isolated from Escherichia coli cells expressing the human interleukin gene has been characterized. The observed properties of the protein have been compared with those properties which can be deduced from the DNA sequence alone and the published properties of natural human interleukin 2. The purified E. coli-derived interleukin 2 is a monomeric protein of Mr 15 000 with a sedimentation velocity of 1.86S. The amino acid composition of the protein and isoelectric point (7.7) are consistent with that part of the translated DNA sequence of the gene corresponding to the mature protein. A single disulphide bridge was identified between Cys-58 and Cys-105. C.d. suggested that interleukin 2 is predominantly alpha-helical in secondary structure. The E. coli-derived protein differed from natural interleukin 2 in the presence of N-terminal methionine and also in the absence of a carbohydrate moiety. Removal of the coding region for the first three amino acids of the natural interleukin 2 protein sequence (Ala-Pro-Thr) by site-specific mutagenesis resulted in a protein with N-terminal serine. The possibility that the specificity of the E. coli ribosomal methionine aminopeptidase may not recognize the sequence NH2-Met-Xaa-Pro is discussed (where Xaa is any amino acid residue). Images Fig. 1.

Liang, S M; Allet, B; Rose, K; Hirschi, M; Liang, C M; Thatcher, D R

1985-01-01

314

envM genes of Salmonella typhimurium and Escherichia coli.  

PubMed Central

Conjugation and bacteriophage P1 transduction experiments in Escherichia coli showed that resistance to the antibacterial compound diazaborine is caused by an allelic form of the envM gene. The envM gene from Salmonella typhimurium was cloned and sequenced. It codes for a 27,765-dalton protein. The plasmids carrying this DNA complemented a conditionally lethal envM mutant of E. coli. Recombinant plasmids containing gene envM from a diazaborine-resistant S. typhimurium strain conferred the drug resistance phenotype to susceptible E. coli cells. A guanine-to-adenine exchange in the envM gene changing a Gly codon to a Ser codon was shown to be responsible for the resistance character. Upstream of envM a small gene coding for a 10,445-dalton protein was identified. Incubating a temperature-sensitive E. coli envM mutant at the nonpermissive temperature caused effects on the cells similar to those caused by treatment with diazaborine, i.e., inhibition of fatty acid, phospholipid, and lipopolysaccharide biosynthesis, induction of a 28,000-dalton inner membrane protein, and change in the ratio of the porins OmpC and OmpF. Images

Turnowsky, F; Fuchs, K; Jeschek, C; Hogenauer, G

1989-01-01

315

envM genes of Salmonella typhimurium and Escherichia coli.  

PubMed

Conjugation and bacteriophage P1 transduction experiments in Escherichia coli showed that resistance to the antibacterial compound diazaborine is caused by an allelic form of the envM gene. The envM gene from Salmonella typhimurium was cloned and sequenced. It codes for a 27,765-dalton protein. The plasmids carrying this DNA complemented a conditionally lethal envM mutant of E. coli. Recombinant plasmids containing gene envM from a diazaborine-resistant S. typhimurium strain conferred the drug resistance phenotype to susceptible E. coli cells. A guanine-to-adenine exchange in the envM gene changing a Gly codon to a Ser codon was shown to be responsible for the resistance character. Upstream of envM a small gene coding for a 10,445-dalton protein was identified. Incubating a temperature-sensitive E. coli envM mutant at the nonpermissive temperature caused effects on the cells similar to those caused by treatment with diazaborine, i.e., inhibition of fatty acid, phospholipid, and lipopolysaccharide biosynthesis, induction of a 28,000-dalton inner membrane protein, and change in the ratio of the porins OmpC and OmpF. PMID:2687243

Turnowsky, F; Fuchs, K; Jeschek, C; Högenauer, G

1989-12-01

316

CRISPR-Cas Functional Module Exchange in Escherichia coli  

PubMed Central

ABSTRACT Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (cas) genes constitute the CRISPR-Cas systems found in the Bacteria and Archaea domains. At least in some strains they provide an efficient barrier against transmissible genetic elements such as plasmids and viruses. Two CRISPR-Cas systems have been identified in Escherichia coli, pertaining to subtypes I-E (cas-E genes) and I-F (cas-F genes), respectively. In order to unveil the evolutionary dynamics of such systems, we analyzed the sequence variations in the CRISPR-Cas loci of a collection of 131 E. coli strains. Our results show that the strain grouping inferred from these CRISPR data slightly differs from the phylogeny of the species, suggesting the occurrence of recombinational events between CRISPR arrays. Moreover, we determined that the primary cas-E genes of E. coli were altogether replaced with a substantially different variant in a minor group of strains that include K-12. Insertion elements play an important role in this variability. This result underlines the interchange capacity of CRISPR-Cas constituents and hints that at least some functional aspects documented for the K-12 system may not apply to the vast majority of E. coli strains.

Almendros, Cristobal; Mojica, Francisco J. M.; Diez-Villasenor, Cesar; Guzman, Noemi M.; Garcia-Martinez, Jesus

2014-01-01

317

Structural analysis of full-length Hfq from Escherichia coli  

PubMed Central

The structure of full-length host factor Q? (Hfq) from Escherichia coli obtained from a crystal belonging to space group P1, with unit-cell parameters a = 61.91, b = 62.15, c = 81.26?Å, ? = 78.6, ? = 86.2, ? = 59.9°, was solved by molecular replacement to a resolution of 2.85?Å and refined to R work and R free values of 20.7% and 25.0%, respectively. Hfq from E. coli has previously been crystallized and the structure has been solved for the N-terminal 72 amino acids, which cover ?65% of the full-length sequence. Here, the purification, crystallization and structural data of the full 102-amino-acid protein are presented. These data revealed that the presence of the C-terminus changes the crystal packing of E. coli Hfq. The crystal structure is discussed in the context of the recently published solution structure of Hfq from E. coli.

Beich-Frandsen, Mads; Vecerek, Branislav; Sjoblom, Bjorn; Blasi, Udo; Djinovic-Carugo, Kristina

2011-01-01

318

Bacterial adherence in mastitis caused by Escherichia coli.  

PubMed

The possible role of bacterial adherence in the pathogenesis of experimental mastitis in the mouse was examined with four strains of Escherichia coli. Two of these strains had a known adhesion antigen (K88) and two did not. The K88 antigen did not play a significant role in the virulence or infectivity of E. coli either in the murine or bovine mammary gland. Two E. coli strains, W1 (K88+) and J2 (K88-) were virulent in the mouse but did not adhere to epithelial cells. Both these strains produced clinical mastitis in the cow. A third strain, D282 (K88-), produced mild disease in the mouse but was avirulent in the cow. The fourth strain, 233/ID (K88+), was avirulent in both the mouse and the cow. Strains D282 and 233/1D were killed rapidly by bovine serum whilst J2 and W1 were more resistant. All strains were more sensitive than the control resistant strain E. coli P4, which is known to be highly virulent for the lactating udder. PMID:337635

Anderson, J C; Burrows, M R; Bramley, A J

1977-11-01

319

Uptake of AMP, ADP, and ATP in Escherichia coli W.  

PubMed

The uptake activity ratio for AMP, ADP, and ATP in mutant (T-1) cells of Escherichia coli W, deficient in de novo purine biosynthesis at a point between IMP and 5-aminoimidazole-4-carboxiamide-1-?-D-ribofuranoside (AICAR), was 1:0.43:0.19. This ratio was approximately equal to the 5'-nucleotidase activity ratio in E. coli W cells. The order of inhibitory effect on [2-³H]ADP uptake by T-1 cells was adenine > adenosine > AMP > ATP. About 2-fold more radioactive purine bases than purine nucleosides were detected in the cytoplasm after 5 min in an experiment with [8-¹?C]AMP and T-1 cells. Uptake of [2-³H]adenosine in T-1 cells was inhibited by inosine, but not in mutant (Ad-3) cells of E. coli W, which lacked adenosine deaminase and adenylosuccinate lyase. These experiments suggest that AMP, ADP, and ATP are converted mainly to adenine and hypoxanthine via adenosine and inosine before uptake into the cytoplasm by E. coli W cells. PMID:21228488

Watanabe, Kimiko; Tomioka, Satsuki; Tanimura, Kiyoko; Oku, Hisae; Isoi, Koichiro

2011-01-01

320

Enzootic Enteropathogenic Escherichia coli Infection in Laboratory Rabbits  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) is the most important cause of persistent diarrhea in children, particularly in developing countries. Animals serve as pathogenic E. coli reservoirs, and compelling evidence for cross-species EPEC transmission exists. In this report, enzootic EPEC infection associated with up to 10.5% diarrhea-associated morbidity in a large laboratory Dutch Belted rabbit colony was investigated. These rabbits were obtained from a commercial vendor and had acute diarrhea following shipment. Fecal culture of 20 rabbits yielded 48 E. coli isolates, 83% of which were eae positive. Repetitive sequence-based PCR (REP-PCR) and serologic analysis identified a single disease-associated EPEC O145:H2 strain. In sampled rabbits, EPEC-positive culture and the presence of diarrhea were significantly associated. This strain displayed a localized adherence-like HEp-2 cell adherence pattern, as seen in diarrheic human infant EPEC isolates. Treatment was instituted with the fluoroquinolone antibiotic enrofloxacin, to which all isolates were susceptible. Preshipment parenteral enrofloxacin administration reduced diarrhea-associated morbidity 22-fold and mortality 12-fold in subsequent deliveries. This report emphasizes the zoonotic potential of animal EPEC strains and the need for virulence determinant-based screening of E. coli isolates from diarrheic animals.

Buckley, Ellen M.; Parry, Nicola M. A.; Madden, Carolyn M.; Garcia, Alexis; Morgan, Peter B.; Astrofsky, Keith M.; Fox, James G.

2012-01-01

321

Escherichia coli from clinical mastitis: serotypes and virulence factors.  

PubMed

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

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

2011-11-01

322

Aspects of genome plasticity in pathogenic Escherichia coli.  

PubMed

The species Escherichia coli comprises not only non-pathogenic or commensal variants that belong to the normal intestinal flora of most mammals, but also various pathogenic strains causing diverse intestinal and extraintestinal infections in man and animals. Virulence factors and mechanisms involved in pathogenesis have been successfully analyzed for many years resulting in a wealth of knowledge about many E. coli pathotypes. However, our knowledge on the genome content, diversity and variability between pathogenic and also non-pathogenic subtypes is only slowly accumulating. Pathotypes have been largely defined by the presence or absence of particular DNA segments that in most cases appear to have been acquired via horizontal gene transfer events. As these regions are frequently subjected to excisions, rearrangements, and transfers they contribute to the previously unexpected and underestimated rapid evolution of E. coli variants resulting in the development of novel strains and even pathotypes. In these studies various novel aspects of genome diversity and plasticity in extraintestinal and intestinal pathogenic E. coli pathotypes have been addressed and the results have been directly applied for the improvement of diagnostic methods. PMID:17462951

Bielaszewska, Martina; Dobrindt, Ulrich; Gärtner, Julia; Gallitz, Inka; Hacker, Jörg; Karch, Helge; Müller, Daniel; Schubert, Sören; Alexander Schmidt, M; Sorsa, Liisa Johanna; Zdziarski, Jaroslaw

2007-11-01

323

A stochastic killing system for biological containment of Escherichia coli.  

PubMed Central

Bacteria with a stochastic conditional lethal containment system have been constructed. The invertible switch promoter located upstream of the fimA gene from Escherichia coli was inserted as expression cassette in front of the lethal gef gene deleted of its own natural promoter. The resulting fusion was placed on a plasmid and transformed to E. coli. The phenotype connected with the presence of such a plasmid was to reduce the population growth rate with increasing significance as the cell growth rate was reduced. In very fast growing cells, there was no measurable effect on growth rate. When a culture of E. coli harboring the plasmid comprising the containment system is left as stationary cells in suspension without nutrients, viability drops exponentially over a period of several days, in contrast to the control cells, which maintain viability nearly unaffected during the same period of time. Similar results were obtained with a strain in which the killing cassette was inserted in the chromosome. In competition with noncontained cells during growth, the contained cells are always outcompeted. Stochastic killing obtained by the fim-gef fusion is at present relevant only as a containment approach for E. coli, but the model may be mimicked in other organisms by using species-specific stochastic expression systems.

Klemm, P; Jensen, L B; Molin, S

1995-01-01

324

Molecular Epidemiology of Escherichia coli Producing Extended-Spectrum -Lactamases Isolated in Rome, Italy  

Microsoft Academic Search

Escherichia coli strains producing extended-spectrum -lactamases (ESBLs) are a major problem in many different hospitals worldwide, causing outbreaks as well as sporadic infections. The prevalence of Escherichia coli ESBL producers was analyzed in a surveillance study performed on the population attending the Poli- clinico Umberto I, the largest university hospital in Rome, Italy. We also investigated genotypes, pathogenicity islands, and

Alessandra Carattoli; Aurora Garcõ ´ a-Fernandez; Paola Varesi; Daniela Fortini; Serena Gerardi; Adriano Penni; Carlo Mancini; Alessandra Giordano

325

Directed Evaluation of Enterotoxigenic Escherichia coli Autotransporter Proteins as Putative Vaccine Candidates  

Microsoft Academic Search

BackgroundEnterotoxigenic Escherichia coli (ETEC) is a major diarrheal pathogen in developing countries, where it accounts for millions of infections and hundreds of thousands of deaths annually. While vaccine development to prevent diarrheal illness due to ETEC is feasible, extensive effort is needed to identify conserved antigenic targets. Pathogenic Escherichia coli, including ETEC, use the autotransporter (AT) secretion mechanism to export

Jessica A. Harris; Koushik Roy; Virginia Woo-Rasberry; David J. Hamilton; Rita Kansal; Firdausi Qadri; James M. Fleckenstein

2011-01-01

326

Epidemiology of Escherichia coli O157:H7 Outbreaks, United States, 1982-2002  

Microsoft Academic Search

Escherichia coli O157:H7 causes 73,000 illnesses in the United States annually. We reviewed E. coli O157 out- breaks reported to Centers for Disease Control and Prevention (CDC) to better understand the epidemiology of E. coli O157. E. coli O157 outbreaks (>2 cases of E. coli O157 infection with a common epidemiologic exposure) reported to CDC from 1982 to 2002 were

Josefa M. Rangel; Phyllis H. Sparling; Collen Crowe; Patricia M. Griffin; David L. Swerdlow

2005-01-01

327

Fate of a genetically engineered escherichia coli bearing a plasmid in a paddy field microcosm  

Microsoft Academic Search

Escherichia coli DH5 a pBluescript II SK, bearing a plasmid which has a resistant gene to ampicillin as a genetically engineered bacteria (g?E. coli) and its parent E. coli DH5 a (p?E. coli), were introduced into a paddy field microcosm on the initial, 0.5th, 5th and 20th days after the microcosm was cultured. The population densities of both g?E. coli

Zen'Ichiro Kawabata; Kazuaki Matsui; Nobuyoshi Ishi

1997-01-01

328

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

329

Directed Evolution of Ionizing Radiation Resistance in Escherichia coli? †  

PubMed Central

We have generated extreme ionizing radiation resistance in a relatively sensitive bacterial species, Escherichia coli, by directed evolution. Four populations of Escherichia coli K-12 were derived independently from strain MG1655, with each specifically adapted to survive exposure to high doses of ionizing radiation. D37 values for strains isolated from two of the populations approached that exhibited by Deinococcus radiodurans. Complete genomic sequencing was carried out on nine purified strains derived from these populations. Clear mutational patterns were observed that both pointed to key underlying mechanisms and guided further characterization of the strains. In these evolved populations, passive genomic protection is not in evidence. Instead, enhanced recombinational DNA repair makes a prominent but probably not exclusive contribution to genome reconstitution. Multiple genes, multiple alleles of some genes, multiple mechanisms, and multiple evolutionary pathways all play a role in the evolutionary acquisition of extreme radiation resistance. Several mutations in the recA gene and a deletion of the e14 prophage both demonstrably contribute to and partially explain the new phenotype. Mutations in additional components of the bacterial recombinational repair system and the replication restart primosome are also prominent, as are mutations in genes involved in cell division, protein turnover, and glutamate transport. At least some evolutionary pathways to extreme radiation resistance are constrained by the temporally ordered appearance of specific alleles.

Harris, Dennis R.; Pollock, Steve V.; Wood, Elizabeth A.; Goiffon, Reece J.; Klingele, Audrey J.; Cabot, Eric L.; Schackwitz, Wendy; Martin, Joel; Eggington, Julie; Durfee, Timothy J.; Middle, Christina M.; Norton, Jason E.; Popelars, Michael C.; Li, Hao; Klugman, Sarit A.; Hamilton, Lindsay L.; Bane, Lukas B.; Pennacchio, Len A.; Albert, Thomas J.; Perna, Nicole T.; Cox, Michael M.; Battista, John R.

2009-01-01

330

Cleaving yeast and Escherichia coli genomes at a single site  

SciTech Connect

The 15-megabase pair Saccharomyces cerevisiae and the 4.7-megabase pair Escherichia coli genomes were completely cleaved at a single predetermined site by means of the Achilles' heel cleavage (AC) procedure. The symmetric lac operator (lacO{sub s}) was introduced into the circular Escherichia coli genome and into one of the 16 yeast chromosomes. Intact chromosomes from the resulting strains were prepared in agarose microbeads and methylated with Hha I (5{prime}-GCGC) methyltransferase (M{center dot}Hha I) in the presence of lac repressor (LacI). All Hae II sites ({prime}-{sub G}{sup A}GCGC{sub C}{sup T}) with the exception of the one in lacO{sub s}, which was protected by LacI, were modified and thus no longer recognized by Hae II. After inactivation of M{center dot}Hha I and LacI, Hae II was used to completely cleave the chromosomes specifically at the inserted lacO{sub s}. These experiments demonstrate the feasibility of using the AC approach to efficiently extend the specificity of naturally occurring restriction enzymes and create new tools for the mapping and precise molecular dissection of multimegabase genomes.

Koob, M.; Szybalski, W. (Univ. of Wisconsin, Madison (USA))

1990-10-12

331

Atypical Enteropathogenic Escherichia coli Secretes Plasmid Encoded Toxin  

PubMed Central

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.

Ruiz, Rita C.; Melo, Keyde C. M.; Rossato, Sarita S.; Barbosa, Camila M.; Correa, Livia M.; Elias, Waldir P.; Piazza, Roxane M. F.

2014-01-01

332

TURBIDITY CHANGE DURING GLUCOSE PERMEATION IN ESCHERICHIA COLI1  

PubMed Central

Rogers, Dexter (Utah State University, Logan) and Shon-Hua Yu. Turbidity change during glucose permeation in Escherichia coli. J. Bacteriol. 85:1141–1149. 1963.—In contrast to the normal turbidity decrease, which was observed at pH 5.5, the turbidity of suspensions of Escherichia coli strain A (Weigle) increased during uptake of glucose permease substrates when uptake was studied at pH 6.5. Although the turbidity increase at pH 6.5 was the reverse of the expected change, it correlated with the uptake of substrate. During the later phase of permeation at pH 6.5, both uptake of substrate and turbidity change were reversed. We suggest that the observed turbidity response indicated the accumulation of substrate at the cell membrane when the mechanism for releasing substrate to the cytoplasm was inhibited at pH 6.5. Under this condition, uptake of substrate did not cause swelling because the substrate was osmotically inactive, since it may have been bound to the membrane. Permeability was observed to be susceptible to modification by prior treatment with substrate, by aging in the presence of chloramphenicol, and by treatment with dinitrophenol. Permeation and turbidity change are discussed in terms of a proposed phosphorylative mechanism of glucose transport.

Rogers, Dexter; Yu, Shon-Hua

1963-01-01

333

A functional update of the Escherichia coli K-12 genome  

PubMed Central

Background Since the genome of Escherichia coli K-12 was initially annotated in 1997, additional functional information based on biological characterization and functions of sequence-similar proteins has become available. On the basis of this new information, an updated version of the annotated chromosome has been generated. Results The E. coli K-12 chromosome is currently represented by 4,401 genes encoding 116 RNAs and 4,285 proteins. The boundaries of the genes identified in the GenBank Accession U00096 were used. Some protein-coding sequences are compound and encode multimodular proteins. The coding sequences (CDSs) are represented by modules (protein elements of at least 100 amino acids with biological activity and independent evolutionary history). There are 4,616 identified modules in the 4,285 proteins. Of these, 48.9% have been characterized, 29.5% have an imputed function, 2.1% have a phenotype and 19.5% have no function assignment. Only 7% of the modules appear unique to E. coli, and this number is expected to be reduced as more genome data becomes available. The imputed functions were assigned on the basis of manual evaluation of functions predicted by BLAST and DARWIN analyses and by the MAGPIE genome annotation system. Conclusions Much knowledge has been gained about functions encoded by the E. coli K-12 genome since the 1997 annotation was published. The data presented here should be useful for analysis of E. coli gene products as well as gene products encoded by other genomes.

Serres, Margrethe H; Gopal, Shuba; Nahum, Laila A; Liang, Ping; Gaasterland, Terry; Riley, Monica

2001-01-01

334

Redesigning Escherichia coli Metabolism for Anaerobic Production of Isobutanol?†  

PubMed Central

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.

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

2011-01-01

335

Autodisplay of functional CYP106A2 in Escherichia coli.  

PubMed

Cytochrome P450 enzymes catalyse a wide variety of reactions, including the hydroxylation and epoxidation of CC bonds, and dealkylation reactions. There is high interest in these reactions for biotechnology and pharmaceutical processes. Many P450s require membrane surroundings and have substrates that do not cross biological membranes. To circumvent these obstacles, CYP106A2 from Bacillus megaterium was expressed on the outer membrane of Escherichia coli cells by Autodisplay. Exposure on the surface was confirmed by a protease accessibility test and flow cytometry after immunolabelling. HPLC assays showed that 0.5 ml of cells displaying the enzyme (OD??? = 6) converted 9.13 ?mol of deoxycorticosterone to 15?-OH-deoxycorticosterone within 1h. Imipramine and abietic acid were also accepted as substrates. The number of active enzyme molecules per cell was calculated to be 20,000. Surprisingly, surface-exposed CYP106A2 was active in E. coli BL21 without the external addition of the heme group. However, when CYP106A2 was expressed on the surface of an E. coli strain lacking the TolC channel protein (JW5503), enzymatic activity was almost completely abolished. The activity of CYP106A2 on the surface of E. coli JW5503 could be restored by the external addition of the heme group. This suggests, as has been reported before, that E. coli uses a TolC-dependent mechanism to export heme into the growth media, where it can be scavenged by a surface-displayed apoenzyme. Our results indicate that Autodisplay enables the functional surface display of P450 enzymes and provides a new platform to access their synthetic potential. PMID:22426093

Schumacher, Stephanie D; Hannemann, Frank; Teese, Mark George; Bernhardt, Rita; Jose, Joachim

2012-10-15

336

Biocontrol of Escherichia coli O157 with O157Specific Bacteriophages  

Microsoft Academic Search

Escherichia coli O157 antigen-specific bacteriophages were isolated and tested to determine their ability to lyse laboratory cultures of Escherichia coli O157:H7. A total of 53 bovine or ovine fecal samples were enriched for phage, and 5 of these samples were found to contain lytic phages that grow on E. coli O157:H7. Three bacteriophages, designated KH1, KH4, and KH5, were evaluated.

INDIRA T. KUDVA; SRDJAN JELACIC; PHILLIP I. TARR; PHILIP YOUDERIAN; CAROLYN J. HOVDE

1999-01-01

337

Antibacterial Action of Selenium-Enriched Probiotics Against Pathogenic Escherichia coli  

Microsoft Academic Search

The purpose of this study was to evaluate the inhibitory activity of selenium-enriched probiotics against pathogenic Escherichia coli (E. coli) in vitro and in vivo. Escherichia coli was co-cultured in vitro with each probiotic strain individually, and a mixture of the four strains and its population was\\u000a counted at various time points. We also collected a cell-free culture supernatant (CFCS) of each probiotic

Jiajun Yang; Kehe Huang; Shunyi Qin; Xianshi Wu; Zhiping Zhao; Fu Chen

2009-01-01

338

Preharvest Evaluation of Coliforms, Escherichia coli, Salmonella, and Escherichia coli O157:H7 in Organic and Conventional Produce Grown by Minnesota Farmers  

Microsoft Academic Search

Microbiological analyses of fresh fruits and vegetables produced by organic and conventional farmers in Minnesota were conducted to determine the coliform count and the prevalence of Escherichia coli, Salmonella, and E. coli O157:H7. A total of 476 and 129 produce samples were collected from 32 organic and 8 conventional farms, respectively. The samples included tomatoes, leafy greens, lettuce, green peppers,

AVIK MUKHERJEE; DORINDA SPEH; ELIZABETH DYCK; FRANCISCO DIEZ-GONZALEZ

339

Harvest active recombinant Rho kinase from Escherichia coli.  

PubMed

Rho kinase (ROCK) inhibitors are effective candidates for treating nerve or myocardial injury, erectile dysfunction, and other cardiovascular diseases. Purified ROCK is a foundation for ROCK inhibitors screening and for its function research in vitro. This article established an easy way to harvest active recombinant ROCK catalytic domain (ROCK-CD) of rat in Escherichia coli (E. coli). The cDNA of ROCK-CD was amplified by RT-PCR, and subcloned to pET28a(+) vector to express the protein in E. coli BL(21) as inclusion bodies. The protein was purified by HiTrap chelating column, and its refolding was achieved by gradient dilution from guanidine hydrochloride solution, and desalinated by ultrafiltration. The result of DNA sequencing and protein sequence analysis indicate there were three amino acid residua of mutation, but the activity was not significantly affected. The activity of the recombinant protein was confirmed by ROCK II activity fluorescence polarization kit. Therefore, this is an easy and rapid procedure to harvest a large quantity of activity recombinant ROCK-CD at low cost. PMID:16394506

Duan, Weigang; Wang, Shanzhi; Chen, Min; Wang, Cuifen; Zhang, Luyong; Liu, Jun; Sun, Lixin; Yan, Ming

2006-01-01

340

Virulence factors in Escherichia coli urinary tract infection.  

PubMed Central

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

Johnson, J R

1991-01-01

341

Direct and rapid quantum dots labelling of Escherichia coli cells.  

PubMed

Here, we supplied a direct and rapid quantum dots labelling method of bacterial cells in food, water and environmental contaminations. Outer layers of Escherichia coli cells prevent cells from direct interactions with molecules and objects such as quantum dots. Permeabilization treatment of E. coli cells may facilitate macromolecules penetrate cell walls and improve internal bacterial quantum dots (QDs) labelling. In this work, we investigated direct internal QDs labelling of E. coli cells permeabilized using three methods including chloroform-SDS treatment, lysozyme-EDTA treatment and osmotic shock treatment. Effects of permeabilization were analysed by scanning electronic microscopy and measuring activity of alkaline phosphatase (PhoA) released from periplasm. Internal bacterial QDs labelling was monitored by flow cytometry and fluorescent microscopy. After chloroform-SDS or lysozyme-EDTA treatment, cells could be directly labelled with QDs. No interaction was observed between osmotic shock treated cells and QDs. The mechanism of cell permeabilization explaining different labelling efficiency has been established. The QDs labelling approach presented in this work provides a simple, rapid and sensitive detection method for multiple purpose bacterial analysis in combination with biological techniques. PMID:23149105

Yang, Cheng; Xie, Hao; Li, Yu; Zhang, Jian-Kun; Su, Bao-Lian

2013-03-01

342

Properties of the two terminal oxidases of Escherichia coli  

SciTech Connect

Proton translocation coupled to oxidation of ubiquinol by O{sub 2} was studied in spheroplasts of two mutant strains of Escherichia coli, one of which expresses cytochrome d, but not cytochrome bo, and the other expressing only the latter. O{sub 2} pulse experiments revealed that cytochrome d catalyzes separation of the protons and electrons of ubiquinol oxidation but is not a proton pump. In contrast, cytochrome bo functions as a proton pump in addition to separating the charges of quinol oxidation. E. coli membranes and isolated cytochrome bo lack the Cu{sub A} center typical of cytochrome c oxidase, and the isolated enzyme contains only 1Cu/2Fe. Optical spectra indicate that high-spin heme o contributes < 10% to the reduced minus oxidized 560-nm band of the enzyme. Pyridine hemochrome spectra suggest that the hemes of cytochrome bo are not protohemes. Proteoliposomes with cytochrome bo exhibited good respiratory control, but H{sup +}/e{sup {minus}} during quinol oxidation was only 0.3-0.7. This was attributed to an inside out orientation of a significant fraction of the enzyme. Possible metabolic benefits of expressing both cytochromes bo and d in E. coli are discussed.

Puustinen, A.; Finel, M.; Haltia, T.; Gennis, R.B.; Wikstrom, M. (Univ. of Helsinki (Finland))

1991-04-23

343

Lactobacillus prophylaxis for diarrhea due to enterotoxigenic Escherichia coli.  

PubMed

In vitro and animal experiments indicated that lactobacilli might prevent Escherichia coli from colonizing the intestine and may produce substances counteracting enterotoxin. Lactinex, a commercial preparation of dried Lactobacillus acidophilus and L. bulgaricus, is marketed for uncomplicated diarrhea. Preliminary experiments in nonfasting volunteers indicated that lactobacilli in this preparation colonized the small intestine for up to 6 h. To evaluate the protective efficacy of Lactinex, a double-blind randomized study was carried out in which 48 volunteers (23 receiving Lactinex and 25 receiving placebos) were challenged with E. coli strains that produced heat-stable or heat-labile enterotoxins or both. No significant differences between the two groups were noted with respect to attack rate, incubation period, duration of diarrhea, volume and number of liquid stools, and coproculture yields. These data suggest that this lactobacillus preparations does not prevent or alter the course of enterotoxigenic E. coli diarrhea in adults. Lack of efficacy occurred despite efforts to maximize small bowel colonization, including administration of Lactinex in milk and in a 6-hour-interval regimen during 36 h before and 96 h after challenge. PMID:6792978

Clements, M L; Levine, M M; Black, R E; Robins-Browne, R M; Cisneros, L A; Drusano, G L; Lanata, C F; Saah, A J

1981-07-01

344

Fitness, Stress Resistance, and Extraintestinal Virulence in Escherichia coli  

PubMed Central

The extraintestinal virulence of Escherichia coli is dependent on numerous virulence genes. However, there is growing evidence for a role of the metabolic properties and stress responses of strains in pathogenesis. We assessed the respective roles of these factors in strain virulence by developing phenotypic assays for measuring in vitro individual and competitive fitness and the general stress response, which we applied to 82 commensal and extraintestinal pathogenic E. coli strains previously tested in a mouse model of sepsis. Individual fitness properties, in terms of maximum growth rates in various media (Luria-Bertani broth with and without iron chelator, minimal medium supplemented with gluconate, and human urine) and competitive fitness properties, estimated as the mean relative growth rate per generation in mixed cultures with a reference fluorescent E. coli strain, were highly diverse between strains. The activity of the main general stress response regulator, RpoS, as determined by iodine staining of the colonies, H2O2 resistance, and rpoS sequencing, was also highly variable. No correlation between strain fitness and stress resistance and virulence in the mouse model was found, except that the maximum growth rate in urine was higher for virulent strains. Multivariate analysis showed that the number of virulence factors was the only independent factor explaining the virulence in mice. At the species level, growth capacity and stress resistance are heterogeneous properties that do not contribute significantly to the intrinsic virulence of the strains.

Bleibtreu, Alexandre; Gros, Pierre-Alexis; Laouenan, Cedric; Clermont, Olivier; Le Nagard, Herve; Picard, Bertrand; Tenaillon, Olivier

2013-01-01

345

Escherichia coli outer membrane protein K is a porin.  

PubMed Central

Protein K is an outer membrane protein found in pathogenic encapsulated strains of Escherichia coli. We present evidence here that protein K is structurally and functionally related to the E. coli K-12 porin proteins (OmpF, OmpC, and PhoE). Protein K was found to cross-react with antibody to OmpF protein and to share 8 out of 17 peptides in common with the OmpF protein. Strains that are OmpC porin- and OmpF porin- and contain protein K as their major outer membrane protein have increased rates of uptake of nutrients and a faster growth rate relative to the parental porin- strain. The protein K-containing strains are at least 1,000-fold more sensitive to colicins E2 and E3 than is the porin -deficient strain. These data suggest that protein K is a functional porin in E. coli. The porin function of protein K was also demonstrated in vitro, using black lipid membranes. Protein K increased the conductance in these membranes in discrete, uniform steps characteristic of channels with a size of about 2 nS. Images

Sutcliffe, J; Blumenthal, R; Walter, A; Foulds, J

1983-01-01

346

Rapid microarray-based DNA genoserotyping of Escherichia coli.  

PubMed

In this study, an improvement in the oligonucleotide-based DNA microarray for the genoserotyping of Escherichia coli is presented. Primer and probes for additional 70 O antigen groups were developed. The microarray was transferred to a new platform, the ArrayStrip format, which allows high through-put tests in 96-well formats and fully automated microarray analysis. Thus, starting from a single colony, it is possible to determine within a few hours and a single experiment, 94 of the over 180 known O antigen groups as well as 47 of the 53 different H antigens. The microarray was initially validated with a set of defined reference strains that had previously been serotyped by conventional agglutination in various reference centers. For further validation of the microarray, 180 clinical E. coli isolates of human origin (from urine samples, blood cultures, bronchial secretions, and wound swabs) and 53 E. coli isolates from cattle, pigs, and poultry were used. A high degree of concordance between the results of classical antibody-based serotyping and DNA-based genoserotyping was demonstrated during validation of the new 70 O antigen groups as well as for the field strains of human and animal origin. Therefore, this oligonucleotide array is a diagnostic tool that is user-friendly and more efficient than classical serotyping by agglutination. Furthermore, the tests can be performed in almost every routine lab and are easily expanded and standardized. PMID:24298918

Geue, Lutz; Monecke, Stefan; Engelmann, Ines; Braun, Sascha; Slickers, Peter; Ehricht, Ralf

2014-02-01

347

Pet, an Autotransporter Enterotoxin from Enteroaggregative Escherichia coli  

PubMed Central

Enteroaggregative Escherichia coli (EAEC) is an emerging cause of diarrheal illness. Clinical data suggest that diarrhea caused by EAEC is predominantly secretory in nature, but the responsible enterotoxin has not been described. Work from our laboratories has implicated a ca. 108-kDa protein as a heat-labile enterotoxin and cytotoxin, as evidenced by rises in short-circuit current and falls in tissue resistance in rat jejunal tissue mounted in an Ussing chamber. Here we report the genetic cloning, sequencing, and characterization of this high-molecular-weight heat-labile toxin. The toxin (designated the plasmid-encoded toxin [Pet]) is encoded on the 65-MDa adherence-related plasmid of EAEC strain 042. Nucleotide sequence analysis suggests that the toxin is a member of the autotransporter class of proteins, characterized by the presence of a conserved C-terminal domain which forms a ?-barrel pore in the bacterial outer membrane and through which the mature protein is transported. The Pet toxin is highly homologous to the EspP protease of enterohemorrhagic E. coli and to EspC of enteropathogenic E. coli, an as yet cryptic protein. In addition to its potential role in EAEC infection, Pet represents the first enterotoxin within the autotransporter class of secreted proteins. We hypothesize that other closely related members of this class may also produce enterotoxic effects.

Eslava, Carlos; Navarro-Garcia, Fernando; Czeczulin, John R.; Henderson, Ian R.; Cravioto, Alejandro; Nataro, James P.

1998-01-01

348

Metabolic engineering of Escherichia coli for the production of xylonate.  

PubMed

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

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

2013-01-01

349

Rapid Method for Escherichia coli in the Cuyahoga River  

USGS Publications Warehouse

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

Brady, Amie M. G.

2007-01-01

350

Purification of Escherichia coli chromosomal segments without cloning.  

PubMed

Pairs of genomic insertions made with elements carrying any one of several frequently used rare restriction sites allow physical purification of insertion delimited genes. However, native rare restriction sites can, either by causing (i) fragmentation of targeted intervals or (ii) generation of additional fragments that overlap electrophoretically with targeted ones, place severe limitations on this approach. We present a series of Escherichia coli mini-Tn10 insertions containing the rare-cutting polylinker 2 (RCP2) of rare restriction sites, which includes the 18-base-pair I-SceI site (absent from native E. coli sequences). Pulsed-field gel purification from RCP2 double insertion mutants of both an I-SceI fragment from strain K-12 (containing approximately 90-95 min) and an allelic I-SceI fragment from a pathogenic strain is demonstrated. The complete series of RCP2 insertions, containing different antibiotic resistances at intervals of approximately 35 kb in prototype K-12 strain MG1655, allows rapid purification of the genes from any E. coli chromosomal interval as an isolated I-SceI fragment. PMID:8660353

Bloch, C A; Rode, C K; Obreque, V H; Mahillon, J

1996-06-01

351

Production of 2-methyl-1-butanol in engineered Escherichia coli.  

PubMed

Recent progress has been made in the production of higher alcohols by harnessing the power of natural amino acid biosynthetic pathways. Here, we describe the first strain of Escherichia coli developed to produce the higher alcohol and potential new biofuel 2-methyl-1-butanol (2MB). To accomplish this, we explored the biodiversity of enzymes catalyzing key parts of the isoleucine biosynthetic pathway, finding that AHAS II (ilvGM) from Salmonella typhimurium and threonine deaminase (ilvA) from Corynebacterium glutamicum improve 2MB production the most. Overexpression of the native threonine biosynthetic operon (thrABC) on plasmid without the native transcription regulation also improved 2MB production in E. coli. Finally, we knocked out competing pathways upstream of threonine production (DeltametA, Deltatdh) to increase its availability for further improvement of 2MB production. This work led to a strain of E. coli that produces 1.25 g/L 2MB in 24 h, a total alcohol content of 3 g/L, and with yields of up to 0.17 g 2MB/g glucose. PMID:18758769

Cann, Anthony F; Liao, James C

2008-11-01

352

Properties of a Clostridium thermocellum Endoglucanase Produced in Escherichia coli.  

PubMed

A cellulase gene of Clostridium thermocellum was transferred to Escherichia coli by molecular cloning with bacteriophage lambda and plasmid vectors and shown to be indentical with the celA gene. The celA gene product was purified from extracts of plasmid-bearing E. coli cells by heat treatment and chromatography on DEAE-Trisacryl. It was characterized as a thermophilic endo-beta-1,4-glucanase, the properties of which closely resemble those of endoglucanase A previously isolated from C. thermocellum supernatants. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis the enzyme purified from E. coli exhibited two protein bands with molecular weights of 49,000 and 52,000. It had a temperature optimum at 75 degrees C and was stable for several hours at 60 degrees C. Endoglucanase activity was optimal between pH 5.5 and 6.5. The enzyme was insensitive against end product inhibition by glucose and cellobiose and remarkably resistant to the denaturing effects of detergents and organic solvents. It was capable of degrading, in addition to cellulosic substrates, glucans with alternating beta-1,4 and beta-1,3 linkages such as barley beta-glucan and lichenan. PMID:16347088

Schwarz, W H; Gräbnitz, F; Staudenbauer, W L

1986-06-01

353

Functional expression of plant acetolactate synthase genes in Escherichia coli  

PubMed Central

Acetolactate synthase (ALS; EC 4.1.3.18) is the first common enzyme in the biosynthetic pathways leading to leucine, isoleucine, and valine. It is the target enzyme for three classes of structurally unrelated herbicides, the sulfonylureas, the imidazolinones, and the triazolopyrimidines. A cloned ALS gene from the small cruciferous plant Arabidopsis thaliana has been fused to bacterial transcription/translation signals and the resulting plasmid has been used to transform Escherichia coli. The cloned plant gene, which includes sequences encoding the chloroplast transit peptide, is functionally expressed in the bacteria. It is able to complement genetically a strain of E. coli that lacks endogenous ALS activity. An ALS gene cloned from a line of Arabidopsis previously shown to be resistant to sulfonylurea herbicides has been similarly expressed in E. coli. The herbicide-resistance phenotype is expressed in the bacteria, as assayed by both enzyme activity and the ability to grow in the presence of herbicides. This system has been useful for purifying substantial amounts of the plant enzyme, for studying the sequence parameters involved in subcellular protein localization, and for characterizing the interactions that occur between ALS and its various inhibitors. Images

Smith, Julie K.; Schloss, John V.; Mazur, Barbara J.

1989-01-01

354

The D-allose operon of Escherichia coli K-12.  

PubMed

Escherichia coli K-12 can utilize D-allose, an all-cis hexose, as a sole carbon source. The operon responsible for D-allose metabolism was localized at 92.8 min of the E. coli linkage map. It consists of six genes, alsRBACEK, which are inducible by D-allose and are under the control of the repressor gene alsR. This operon is also subject to catabolite repression. Three genes, alsB, alsA, and alsC, appear to be necessary for transport of D-allose. D-Allose-binding protein, encoded by alsB, is a periplasmic protein that has an affinity for D-allose, with a Kd of 0.33 microM. As was found for other binding-protein-mediated ABC transporters, the allose transport system includes an ATP-binding component (AlsA) and a transmembrane protein (AlsC). It was found that AlsE (a putative D-allulose-6-phosphate 3-epimerase), but not AlsK (a putative D-allose kinase), is necessary for allose metabolism. During this study, we observed that the D-allose transporter is partially responsible for the low-affinity transport of D-ribose and that strain W3110, an E. coli prototroph, has a defect in the transport of D-allose mediated by the allose permease. PMID:9401019

Kim, C; Song, S; Park, C

1997-12-01

355

Thermal impulse response and the temperature preference of Escherichia coli  

NASA Astrophysics Data System (ADS)

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

Ryu, William

2010-03-01

356

Nascentome analysis uncovers futile protein synthesis in Escherichia coli.  

PubMed

Although co-translational biological processes attract much attention, no general and easy method has been available to detect cellular nascent polypeptide chains, which we propose to call collectively a "nascentome." We developed a method to selectively detect polypeptide portions of cellular polypeptidyl-tRNAs and used it to study the generality of the quality control reactions that rescue dead-end translation complexes. To detect nascent polypeptides, having their growing ends covalently attached to a tRNA, cellular extracts are separated by SDS-PAGE in two dimensions, first with the peptidyl-tRNA ester bonds preserved and subsequently after their in-gel cleavage. Pulse-labeled nascent polypeptides of Escherichia coli form a characteristic line below the main diagonal line, because each of them had contained a tRNA of nearly uniform size in the first-dimension electrophoresis but not in the second-dimension. The detection of nascent polypeptides, separately from any translation-completed polypeptides or degradation products thereof, allows us to follow their fates to gain deeper insights into protein biogenesis and quality control pathways. It was revealed that polypeptidyl-tRNAs were significantly stabilized in E. coli upon dysfunction of the tmRNA-ArfA ribosome-rescuing system, whose function had only been studied previously using model constructs. Our results suggest that E. coli cells are intrinsically producing aberrant translation products, which are normally eliminated by the ribosome-rescuing mechanisms. PMID:22162769

Ito, Koreaki; Chadani, Yuhei; Nakamori, Kenta; Chiba, Shinobu; Akiyama, Yoshinori; Abo, Tatsuhiko

2011-01-01

357

The binary protein-protein interaction landscape of Escherichia coli.  

PubMed

Efforts to map the Escherichia coli interactome have identified several hundred macromolecular complexes, but direct binary protein-protein interactions (PPIs) have not been surveyed on a large scale. Here we performed yeast two-hybrid screens of 3,305 baits against 3,606 preys (?70% of the E. coli proteome) in duplicate to generate a map of 2,234 interactions, which approximately doubles the number of known binary PPIs in E. coli. Integration of binary PPI and genetic-interaction data revealed functional dependencies among components involved in cellular processes, including envelope integrity, flagellum assembly and protein quality control. Many of the binary interactions that we could map in multiprotein complexes were informative regarding internal topology of complexes and indicated that interactions in complexes are substantially more conserved than those interactions connecting different complexes. This resource will be useful for inferring bacterial gene function and provides a draft reference of the basic physical wiring network of this evolutionarily important model microbe. PMID:24561554

Rajagopala, Seesandra V; Sikorski, Patricia; Kumar, Ashwani; Mosca, Roberto; Vlasblom, James; Arnold, Roland; Franca-Koh, Jonathan; Pakala, Suman B; Phanse, Sadhna; Ceol, Arnaud; Häuser, Roman; Siszler, Gabriella; Wuchty, Stefan; Emili, Andrew; Babu, Mohan; Aloy, Patrick; Pieper, Rembert; Uetz, Peter

2014-03-01

358

Recombination in Escherichia coli and the definition of biological species.  

PubMed Central

The DNA sequence of part of the gnd (6-phosphogluconate dehydrogenase) gene was determined for eight wild strains of Escherichia coli and for Salmonella typhimurium. Since a region of the trp (tryptophan) operon and the phoA (alkaline phosphatase) gene have been sequenced from the same strains, the gene trees for these three regions were determined and compared. Gene trees are different from species or strain trees in that a gene tree is derived from a particular segment of DNA, whereas a species or strain tree should be derived from many such segments and is the tree that best represents the phylogenetic relationship of the species or strains. If there were no recombination in E. coli, the gene trees for different genes would not be statistically different from the strain tree or from each other. But, if the gene trees are significantly different, there must have been recombination. Methods are proposed that show these gene trees to be statistically different. Since the gene trees are different, we conclude that recombination is important in natural populations of E. coli. Finally, we suggest that gene trees can be used to create an operational means of defining bacterial species by using the biological species definition.

Dykhuizen, D E; Green, L

1991-01-01

359

Methods for enumerating Escherichia coli in subtropical waters.  

PubMed Central

The standard membrane filtration method of the UK has been modified in order to improve its specificity for enumerating Escherichia coli in the subtropical waters of Hong Kong. This involves incorporating into the membrane lauryl sulphate (mLS) method either an in situ urease test (the mLS-UA method), or an in situ beta-glucuronidase test (the mLS-GUD method). The false-positive errors of the mLS-UA and mLS-GUD methods are low, ranging from 3-5%. A comparison between the membrane filtration (mLS-UA) method and the multiple tube technique in testing E. coli in subtropical beach-waters has demonstrated that the former can give much more precise counts, and is the method of choice for such a purpose. The mLS-GUD method, for which automated counting of E. coli colonies is possible, is a good alternative to mLS-UA in routine enumeration of this bacterial indicator in environmental waters.

Cheung, W. H.; Ha, D. K.; Yeung, K. Y.; Hung, R. P.

1991-01-01

360

Characterization of Pyruvate Uptake in Escherichia coli K-12  

PubMed Central

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.

Kreth, Jens; Lengeler, Joseph W.; Jahreis, Knut

2013-01-01

361

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

362

Cellular Responses and Proteomic Analysis of Escherichia coli Exposed to Green Tea Polyphenols  

Microsoft Academic Search

The purpose of this study was to characterize the cellular response and proteomic analysis of Escherichia coli exposed to tea polyphenols (TPP) extracted from Korean green tea (Camellia sinensis L). TPP showed a dose-dependent bactericidal effect on E. coli. Analysis of cell-membrane fatty acids of E. coli cultures treated with TPP identified unique changes in saturated and unsaturated fatty acids,

Y. S. Cho; N. L. Schiller; H. Y. Kahng; K. H. Oh

2007-01-01

363

High Rates of Escherichia coli Transmission between Livestock and Humans in Rural Uganda  

Microsoft Academic Search

Escherichia coli is a zoonotic bacterium that is important to both public health and livestock economics. To date, most studies of zoonotic E. coli transmission have been conducted in developed nations with industrial- ized agricultural economies. In this study, E. coli bacteria were collected from people and livestock in two communities in rural western Uganda in order to investigate patterns

Innocent B. Rwego; Thomas R. Gillespie; Gilbert Isabirye-Basuta; Tony L. Goldberg

2008-01-01

364

Rapid Identification of Escherichia coli Pathotypes by Virulence Gene Detection with DNA Microarrays  

Microsoft Academic Search

One approach to the accurate determination of the pathogenic potential (pathotype) of isolated Escherichia coli strains would be through a complete assessment of each strain for the presence of all known E. coli virulence factors. To accomplish this, an E. coli virulence factor DNA microarray composed of 105 DNA PCR amplicons printed on glass slides and arranged in eight subarrays

Sadjia Bekal; Roland Brousseau; Luke Masson; Gabrielle Prefontaine; John Fairbrother; Josee Harel

365

Molecular analysis of florfenicol-resistant Escherichia coli isolates from pigs  

Microsoft Academic Search

Objectives: The aim of this study was to analyse florfenicol-resistant Escherichia coli isolates from pigs for the genetic basis of florfenicol resistance, and to compare these data with those previously determined for E. coli isolates from cattle and poultry. Methods: Fourteen porcine E. coli isolates were included in this study and subjected to serotyping, plasmid profiling and macrorestriction analysis. MICs

Maren Blickwede; Stefan Schwarz

366

ERIC-PCR identification of the spread of airborne Escherichia coli in pig houses  

Microsoft Academic Search

To understand the spread of microbial aerosols in pig houses, with Escherichia coli (E. coli) as indicator, the airborne E. coli in 4 pig houses and their surroundings at different points 10, 50m upwind and 10, 50, 100, 200 and 400m downwind respectively from the pig houses were collected, and the concentrations were calculated at each sampling point. Furthermore, the

W. Yuan; T. J. Chai; Z. M. Miao

2010-01-01

367

Organised Genome Dynamics in the Escherichia coli Species Results in Highly Diverse Adaptive Paths  

Microsoft Academic Search

The Escherichia coli species represents one of the best-studied model organisms, but also encompasses a variety of commensal and pathogenic strains that diversify by high rates of genetic change. We uniformly (re-) annotated the genomes of 20 commensal and pathogenic E. coli strains and one strain of E. fergusonii (the closest E. coli related species), including seven that we sequenced

Marie Touchon; Claire Hoede; Olivier Tenaillon; Valérie Barbe; Simon Baeriswyl; Philippe Bidet; Edouard Bingen; Stéphane Bonacorsi; Christiane Bouchier; Odile Bouvet; Alexandra Calteau; Hélène Chiapello; Olivier Clermont; Stéphane Cruveiller; Antoine Danchin; Médéric Diard; Carole Dossat; Meriem El Karoui; Eric Frapy; Louis Garry; Jean Marc Ghigo; Anne Marie Gilles; James Johnson; Chantal Le Bouguénec; Mathilde Lescat; Sophie Mangenot; Vanessa Martinez-Jéhanne; Ivan Matic; Xavier Nassif; Sophie Oztas; Marie Agnès Petit; Christophe Pichon; Zoé Rouy; Claude Saint Ruf; Dominique Schneider; Jérôme Tourret; Benoit Vacherie; David Vallenet; Claudine Médigue; Eduardo P. C. Rocha; Erick Denamur

2009-01-01

368

Effect of Phosphorus on Survival of Escherichia coli in Drinking Water Biofilms  

Microsoft Academic Search

The effect of phosphorus addition on survival of Escherichia coli in an experimental drinking water distri- bution 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

Talis Juhna; Dagne Birzniece; Janis Rubulis

2007-01-01

369

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

EPA Science Inventory

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

370

[Advance on Escherichia coli alpha-hemolysin secretion pathway---a review].  

PubMed

In recent years, with the development of biotechnology, the molecular mechanism of the secretion pathways in Escherichia coli is clearer and clearer, and it becomes one of the most effective methods to use E. coli expression system for extracellular production of recombinant proteins. This review discusses recent advances in the secretion mechanism and application of E. coli alpha-hemolysin secretion pathway. PMID:24409755

Su, Lingqia; Chen, Sheng; Wu, Jing

2013-10-01

371

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

PubMed Central

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. Images

Neesen, K; Volckaert, G

1989-01-01

372

Colonization with Extraintestinal Pathogenic Escherichia coli among Nursing Home Residents and Its Relationship to Fluoroquinolone Resistance  

PubMed Central

In a cross-sectional fecal prevalence survey involving 49 residents of a Veterans Affairs nursing home, 59% of subjects were colonized with extraintestinal pathogenic Escherichia coli (ExPEC), 22% were colonized with adhesin-positive E. coli, and 51% were colonized with fluoroquinolone-resistant E. coli. Among 80 unique isolates, adhesins correlated negatively and aerobactin correlated positively with fluoroquinolone resistance.

Maslow, Joel N.; Lautenbach, Ebbing; Glaze, Thomas; Bilker, Warren; Johnson, James R.

2004-01-01

373

High Rates of Escherichia coli Transmission between Livestock and Humans in Rural Uganda  

Microsoft Academic Search

Escherichia coli is a zoonotic bacterium that is important to both public health and livestock economics. To date, most studies of zoonotic E. coli transmission have been conducted in developed nations with industrial- ized agricultural economies. In this study, E. coli bacteria were collected from people and livestock in two communities in rural western Uganda in order to investigate patterns

Innocent B. Rwego; Thomas R. Gillespie; Gilbert Isabirye-Basuta; Tony L. Goldberg

374

Isolation and Characterization of Intestinal Escherichia coli Clones from Wild Boars in Germany  

Microsoft Academic Search

Our understanding of the composition of Escherichia coli populations in wild boars is very limited. In order to obtain insight into the E. coli microflora of wild boars, we studied E. coli isolates from the jejunums, ileums, and colons of 21 wild boars hunted in five geographic locations in Germany. Ten isolates per section were subjected to clonal determination using

Peter Schierack; Antje Romer; Jorg Jores; Heike Kaspar; Sebastian Guenther; Matthias Filter; Jurgen Eichberg; Lothar H. Wieler

2009-01-01

375

Different kinetic of antibody responses following infection of newly weaned pigs with an F4 enterotoxigenic Escherichia coli strain or an F18 verotoxigenic Escherichia coli strain  

Microsoft Academic Search

To develop a vaccine against Escherichia coli-induced post-weaning diarrhea and edema disease, insights in the induction of the protective immune response following infection with these pathogenic E. coli is needed. Therefore, the fimbriae-specific antibody response of newly weaned pigs following infection with the Shiga-like toxin type II variant (SLT-IIv) producing F18+ verotoxigenic E. coli (VTEC) (strain 107\\/86) was compared with

F Verdonck; E Cox; K van Gog; Y Van der Stede; L Duchateau; P Deprez; B. M Goddeeris

2002-01-01

376

Survival and Implantation of Escherichia coli in the Intestinal Tract  

PubMed Central

Preliminary experiments established that a 0.5-ml inoculum that is introduced directly into the stomach of mice was cleared rapidly into the small intestine. Bicarbonate buffer, but not skim milk, protected such an inoculum from stomach acid until at least 90% of it had entered the small intestine. Passage and survival of various Escherichia coli strains through the mouse gut were tested by introducing a buffered bacterial inoculum directly into the stomach, together with the following two intestinal tracers: Cr51Cl3 and spores of a thermophilic Bacillus sp. Quantitative recovery of excreted bacteria was accomplished by collecting the feces overnight in a refrigerated cage pan. The data show that wild-type E. coli strains and E. coli K-12 are excreted rapidly (98 to 100% within 18 h) in the feces without overall multiplication or death. E. coli ?1776 and DP50supF, i.e., strains certified for recombinant DNA experiments underwent rapid death in vivo, such that their excretion in the feces was reduced to approximately 1.1 and 4.7% of the inoculum, respectively. The acidity of the stomach had little bactericidal effect on the E. coli K-12 strain tested, but significantly reduced the survival of more acidsensitive bacteria (Vibrio cholerae) under these conditions. Long-term implantation of E. coli strains into continuous-flow cultures of mouse cecal flora or into conventional mice was difficult to accomplish. In contrast, when the E. coli strain was first inoculated into sterile continuous-flow cultures or into germfree mice, which were subsequently associated with conventional mouse cecal flora, the E. coli strains persisted in a large proportion of the animals at levels resembling E. coli populations in conventional mice. Metabolic adaptation contributed only partially to the success of an E. coli inoculum that was introduced first. A mathematical model is described which explains this phenomenon on the basis of competition for adhesion sites in which an advantage accrues to the bacterium which occupies those sites first. The mathematical model predicts that two or more bacterial strains that compete in the gut for the same limiting nutrient can coexist, if the metabolically less efficient strains have specific adhesion sites available. The specific rate constant of E. coli growth in monoassociated gnotobiotic mice was 2.0 h?1, whereas the excretion rate in conventional animals was ?0.23 h?1. Consequently, limitation of growth must be regarded as the primary mechanism controlling bacterial populations in the large intestine. The beginnings of a general hypothesis of the ecology of the large intestine are proposed, in which the effects of the competitive metabolic interactions described earlier are modified by the effects of bacterial association with the intestinal wall.

Freter, Rolf; Brickner, Howard; Fekete, Janet; Vickerman, Mary M.; Carey, Kristen E.

1983-01-01

377

[Sensitivity to drugs of Escherichia coli strains isolated from poultry with coli septicemia].  

PubMed

Investigations were carried out into the susceptibility of a total of 223 strains of Escherichia coli to therapeutic agents with the employment of the disk diffusion method. The organisms were isolated from internal organs and bone marrow of birds died of coli septicaemia. The serologic classification of the strains was defined with the use of 88 anti-group OK-agglutinating sera obtained through hyperimmunization of rabbits with the following Escherichia coli serotypes: 01-063, 068, 071, 073, 075, 078, 086, 0101, 0103, 0111-0114, 0119, 0124, 0129, 0135-0141, 0146, 0147, and 0149. It was found that serologically the strains referred as follows: 01-41 strains, 02-70 strains, 04-2 strains, 08-3 strains, 026-1 strain, 078-70 strains, 0111-2 strains, 0103-1 strain, 0141-1 strain. The number of untypable strains amounted to 32. Highest number of strains proved sensitive to colistin--96.06%, the remaining drugs following in a descending order: flumequine--95.65%, apramycin - 95.5%, gentamycin--93.72%, amoxicillin--93,8%, amikacin--88.57%, carbenicillin--86.88%, furazolidone--83,13%, and kanamycin--79.36%. High was the percent of strains resistant to tetracycline--66.17%, spectinomycin--61.67%, ampicillin--51.12%, chloramphenicol--50.23%, and streptomycin--44.84%. PMID:3898559

Giurov, B

1985-01-01

378

Regiospecific modifications of naringenin for astragalin production in Escherichia coli.  

PubMed

We report the production of astragalin (AST) from regiospecific modifications of naringenin (NRN) in Escherichia coli BL21(DE3). The exogenously supplied NRN was converted into dihydrokaempferol (DHK) and then kaempferol (KMF) in the presence of flavanone-3-hydroxylase (f3h) and flavonone synthase (fls1) from Arabidopsis thaliana, respectively. KMF was further modified to produce AST by 3-O-glucosylation utilizing the endogeneous UDP-glucose in presence of UGT78K1 from Glycine max. To increase the intracellular UDP-glucose concentration by channeling the carbon flux toward UDP-glucose at the branch point of glucose-6-phosphate (G6P), the chromosomal glucose phosphate isomerase (pgi) and D-glucose-6-phosphate dehydrogenase (zwf) were knocked-out in E. coli BL21(DE3). The two enzymes directly involved in the synthesis of UDP-glucose from G6P, phosphoglucomutase (nfa44530) from Nocardia farcinia and glucose-1-phosphate uridylyltransferase (galU) from E. coli K12 were overexpressed, which successfully diverted the carbon flow from glycolysis to the synthesis of UDP-glucose. Furthermore, to prevent the dissociation of UDP-glucose into UDP and glucose, the UDP-glucose hydrolase (ushA) was deleted. The E. coli ?pgi?zwf?ushA mutant harboring the UDP-glucose biosynthetic pathway and the aforementioned genes for the regiospecific glucosylation produced 109.3?mg/L (244?µM) of AST representing 48.8% conversion from 500?µM of NRN in 60?h without any supplementation of extracellular UDP-glucose. PMID:23568509

Malla, Sailesh; Pandey, Ramesh Prasad; Kim, Byung-Gee; Sohng, Jae Kyung

2013-09-01

379

Source and regulation of flux variability in Escherichia coli  

PubMed Central

Background Metabolic responses are essential for the adaptation of microorganisms to changing environmental conditions. The repertoire of flux responses that the metabolic network can display in different external conditions may be quantified applying flux variability analysis to genome-scale metabolic reconstructions. Results A procedure is developed to classify and quantify the sources of flux variability. We apply the procedure to the latest Escherichia coli metabolic reconstruction, in glucose minimal medium, with an additional constraint to account for the mechanism coordinating carbon and nitrogen utilization mediated by ?-ketoglutarate. Flux variability can be decomposed into three components: internal, external and growth variability. Unexpectedly, growth variability is the only significant component of flux variability in the physiological ranges of glucose, oxygen and ammonia uptake rates. To obtain substantial increases in metabolic flexibility, E. coli must decrease growth rate to suboptimal values. This growth-flexibility trade-off gives a straightforward interpretation to recent work showing that most overall cell-to-cell flux variability in a population of E. coli can be attained sampling a small number of enzymes most likely to constrain cell growth. Importantly, it provides an explanation for the global reorganization occurring in metabolic networks during adaptations to environmental challenges. The calculations were repeated with a pathogenic strain and an old reconstruction of the commensal strain, having less than 50% of the reactions of the latest reconstruction, obtaining the same general conclusions. Conclusions In E. coli growing on glucose, growth variability is the only significant component of flux variability for all physiological conditions explored. Increasing flux variability requires reducing growth to suboptimal values. The growth-flexibility trade-off operates in physiological and evolutionary adaptations, and provides an explanation for the global reorganization occurring during adaptations to environmental challenges. The results obtained do not rely on the knowledge of kinetic and regulatory details of the system and are highly robust to incomplete or incorrect knowledge of the reaction network.

2014-01-01

380

Characterization of fimbriae produced by enteropathogenic Escherichia coli.  

PubMed Central

Enteropathogenic Escherichia coli (EPEC) express rope-like bundles of filaments, termed bundle-forming pili (BFP) (J. A. Girón, A. S. Y. Ho, and G. K. Schoolnik, Science 254:710-713, 1991). Expression of BFP is associated with localized adherence to HEp-2 cells and the presence of the EPEC adherence factor plasmid. In this study, we describe the identification of rod-like fimbriae and fibrillae expressed simultaneously on the bacterial surface of three prototype EPEC strains. Upon fimbrial extraction from EPEC B171 (O111:NM), three fimbrial subunits with masses of 16.5, 15.5, and 14.7 kDa were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Their N-terminal amino acid sequence showed homology with F9 and F7(2) fimbriae of uropathogenic E. coli and F1845 of diffuse-adhering E. coli, respectively. The mixture of fimbrial subunits (called FB171) exhibited mannose-resistant agglutination of human erythrocytes only, and this activity was not inhibited by alpha-D-Gal(1-4)-beta-Gal disaccharide or any other described receptor analogs for P, S, F, M, G, and Dr hemagglutinins of uropathogenic E. coli, which suggests a different receptor specificity. Hemagglutination was inhibited by extracellular matrix glycoproteins, i.e., collagen type IV, laminin, and fibronectin, and to a lesser extent by gangliosides, fetuin, and asialofetuin. Scanning electron microscopic studies performed on clusters of bacteria adhering to HEp-2 cells revealed the presence of structures resembling BFP and rod-like fimbriae linking bacteria to bacteria and bacteria to the eukaryotic cell membrane. We suggest a role of these surface appendages in the interaction of EPEC with eukaryotic cells as well as in the overall pathogenesis of intestinal disease caused by EPEC. Images

Giron, J A; Ho, A S; Schoolnik, G K

1993-01-01

381

The prevalence of Listeria, Salmonella, Escherichia coli and E. coli O157:H7 on bison carcasses during processing  

Microsoft Academic Search

Bison meat is a relatively new, emerging meat species gaining increased popularity in the US and European meat markets, but little is known of its microflora or pathogens that may be present. This study was carried out to determine the incidence of the foodborne pathogens Listeria, Salmonella, Escherichia coli\\/E. coli O157:H7 on slaughtered bison and to evaluate the bison slaughter

Qiongzhen Li; Julie S. Sherwood; Catherine M. Logue

2004-01-01

382

Isobutyraldehyde production from Escherichia coli by removing aldehyde reductase activity  

PubMed Central

Background Increasing global demand and reliance on petroleum-derived chemicals will necessitate alternative sources for chemical feedstocks. Currently, 99% of chemical feedstocks are derived from petroleum and natural gas. Renewable methods for producing important chemical feedstocks largely remain unaddressed. Synthetic biology enables the renewable production of various chemicals from microorganisms by constructing unique metabolic pathways. Here, we engineer Escherichia coli for the production of isobutyraldehyde, which can be readily converted to various hydrocarbons currently derived from petroleum such as isobutyric acid, acetal, oxime and imine using existing chemical catalysis. Isobutyraldehyde can be readily stripped from cultures during production, which reduces toxic effects of isobutyraldehyde. Results We adopted the isobutanol pathway previously constructed in E. coli, neglecting the last step in the pathway where isobutyraldehyde is converted to isobutanol. However, this strain still overwhelmingly produced isobutanol (1.5?g/L/OD600 (isobutanol) vs 0.14?g/L/OD600 (isobutyraldehyde)). Next, we deleted yqhD which encodes a broad-substrate range aldehyde reductase known to be active toward isobutyraldehyde. This strain produced isobutanol and isobutyraldehyde at a near 1:1 ratio, indicating further native isobutyraldehyde reductase (IBR) activity in E. coli. To further eliminate isobutanol formation, we set out to identify and remove the remaining IBRs from the E. coli genome. We identified 7 annotated genes coding for IBRs that could be active toward isobutyraldehyde: adhP, eutG, yiaY, yjgB, betA, fucO, eutE. Individual deletions of the genes yielded only marginal improvements. Therefore, we sequentially deleted all seven of the genes and assessed production. The combined deletions greatly increased isobutyraldehyde production (1.5?g/L/OD600) and decreased isobutanol production (0.4?g/L/OD600). By assessing production by overexpression of each candidate IBR, we reveal that AdhP, EutG, YjgB, and FucO are active toward isobutyraldehyde. Finally, we assessed long-term isobutyraldehyde production of our best strain containing a total of 15 gene deletions using a gas stripping system with in situ product removal, resulting in a final titer of 35?g/L after 5?days. Conclusions In this work, we optimized E. coli for the production of the important chemical feedstock isobutyraldehyde by the removal of IBRs. Long-term production yielded industrially relevant titers of isobutyraldehyde with in situ product removal. The mutational load imparted on E. coli in this work demonstrates the versatility of metabolic engineering for strain improvements.

2012-01-01

383

Analysis of resynthesis tracts in repaired Escherichia coli deoxyribonucleic acid.  

PubMed Central

Excision repair of ultraviolet radiation-induced damage in a wild-type strain of Escherichia coli has been examined, using two methods for characterizing the resynthesis step of the repair process. Comparison of data obtained after both isopycnic analysis of repaired deoxyribonucleic acid and sedimentation velocity analysis of deoxyribonucleic acid after selective photolysis of bromouracil-containing repaired regions has shown that the repaired deoxyribonucleic acid molecules contain a semicontinuous distribution of sizes of repair tracts. Further analysis of our data suggests two major classes of repair patches, one abut 20 to 40 nucleotides in length, and the other containing 1,600 to 2,000 nucleotides. Under the conditions employed, approximately 2 to 10% of the fully repaired regions are long repair patches.

Kuemmerle, N; Ley, R; Masker, W

1981-01-01

384

Evidence of histidine phosphorylation in isocitrate lyase from Escherichia coli  

SciTech Connect

Escherichia coli isocitrate lyase can be phosphorylated in vitro in an ATP-dependent reaction. Partially purified extracts were incubated with ..gamma..-/sup 32/P-ATP and analyzed by two-dimensional polyacrylamide gel electrophoresis followed by a Western blot and autoradiography. Radioactivity was associated with the lyase only when blotting was performed under alkaline conditions. This suggests that phosphate groups are attached to the lyase via an acid-labile P-N bond rather than a more stable P-O bond. Treatment of the lyase with diethyl pyrocarbonate, a histidine modifying agent, blocks incorporation of /sup 32/P-phosphate. Treatment with phosphoramidate, a histidine phosphorylating agent, alters the isoelectric point of the lyase suggesting that the enzyme can be phosphorylated at histidine residues. Loss of catalytic activity after treatment with potato acid phosphatase indicates that isocitrate lyase activity may be modulated by phosphorylation.

Roberston, E.F.; Hoyt, J.C.; Reeves, H.C.

1987-05-01

385

Phenotypic bistability in Escherichia coli's central carbon metabolism.  

PubMed

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

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

2014-01-01

386

Mechanisms of replication fork restart in Escherichia coli.  

PubMed Central

Replication of the genome is crucial for the accurate transmission of genetic information. It has become clear over the last decade that the orderly progression of replication forks in both prokaryotes and eukaryotes is disrupted with high frequency by encounters with various obstacles either on or in the template strands. Survival of the organism then becomes dependent on both removal of the obstruction and resumption of replication. This latter point is particularly important in bacteria, where the number of replication forks per genome is nominally only two. Replication restart in Escherichia coli is accomplished by the action of the restart primosomal proteins, which use both recombination intermediates and stalled replication forks as substrates for loading new replication forks. These reactions have been reconstituted with purified recombination and replication proteins.

Marians, Kenneth J

2004-01-01

387

Photoreactivation in phr mutants of Escherichia coli K-12.  

PubMed Central

We have investigated the genetics of photoreactivation in Escherichia coli K-12. We found that strains with point mutations or deletions in the phr gene showed a significant residual level of photoreactivation after exposure to large fluences of photoreactivating light. It had been previously proposed that a gene in the gal-att lambda interval is also involved in photoreactivation and that the residual photoreactivating activity might be due to this so-called phrA gene located at this interval. We found that deletions of the gal-att lambda region had no effect on either the rate or the final extent of photoreactivation observed in phr+ cells or phr mutants; however strains carrying the delta (gal-att lambda) deletions displayed increased sensitivity to near-UV radiation.

Husain, I; Sancar, A

1987-01-01

388

A domino effect in antifolate drug action in Escherichia coli  

PubMed Central

Mass spectrometry technologies for measurement of cellular metabolism are opening new avenues to explore drug activity. Trimethoprim is an antibiotic that inhibits bacterial dihydrofolate reductase (DHFR). Kinetic flux profiling with 15N-labeled ammonia in Escherichia coli reveals that trimethoprim leads to blockade not only of DHFR but also of another critical enzyme of folate metabolism: folylpoly-?-glutamate synthetase (FP-?-GS). Inhibition of FP-?-GS is not directly due to trimethoprim. Instead, it arises from accumulation of DHFR’s substrate dihydrofolate, which we show is a potent FP-?-GS inhibitor. Thus, owing to the inherent connectivity of the metabolic network, falling DHFR activity leads to falling FP-?-GS activity in a domino-like cascade. This cascade results in complex folate dynamics, and its incorporation in a computational model of folate metabolism recapitulates the dynamics observed experimentally. These results highlight the potential for quantitative analysis of cellular metabolism to reveal mechanisms of drug action.

Kwon, Yun Kyung; Lu, Wenyun; Melamud, Eugene; Khanam, Nurussaba; Bognar, Andrew; Rabinowitz, Joshua D

2009-01-01

389

Porins of Escherichia coli: unidirectional gating by pressure.  

PubMed Central

OmpC and PhoE porins of Escherichia coli were examined by the patch-clamp technique following reconstitution in liposomes, and were observed primarily in the open (conducting) state. With application of negative voltage and positive hydrostatic pressure, OmpC exhibited marked gating towards a more closed state whereas PhoE remained largely unaffected by pressure application. Hybrid chimeric OmpC-PhoE proteins showed an increased tendency for pressure-dependent gating as the OmpC proportion in the chimeric molecule increased. In addition, several PhoE mutants with amino acid substitutions and insertions in either the L3 or L4 loop of the monomer exhibited pressure sensitivity comparable with the wild-type OmpC porin. Our data support the structural plasticity model of porins and are consistent with the 'charge-screening-unscreening' hypothesis that describes how these proteins may exist in distinct conformations. Images

Le Dain, A C; Hase, C C; Tommassen, J; Martinac, B

1996-01-01

390

Enterotoxigenic Escherichia coli infection induces intestinal epithelial cell autophagy.  

PubMed

The morbidity and mortality in piglets caused by enterotoxigenic Escherichia coli (ETEC) results in large economic losses to the swine industry, but the precise pathogenesis of ETEC-associated diseases remains unknown. Intestinal epithelial cell autophagy serves as a host defense against pathogens. We found that ETEC induced autophagy, as measured by both the increased punctae distribution of GFP-LC3 and the enhanced conversion of LC3-I to LC3-II. Inhibiting autophagy resulted in decreased survival of IPEC-1 cells infected with ETEC. ETEC triggered autophagy in IPEC-1 cells through a pathway involving the mammalian target of rapamycin (mTOR), the extracellular signal-regulated kinases 1/2 (ERK1/2), and the AMP-activated protein kinase (AMPK). PMID:24742948

Tang, Yulong; Li, Fengna; Tan, Bie; Liu, Gang; Kong, Xiangfeng; Hardwidge, Philip R; Yin, Yulong

2014-06-25

391

Clocking Out: Modeling Phage-Induced Lysis of Escherichia coli?  

PubMed Central

Phage ? lyses the host Escherichia coli at a precisely scheduled time after induction. Lysis timing is determined by the action of phage holins, which are small proteins that induce hole formation in the bacterium's cytoplasmic membrane. We present a two-stage nucleation model of lysis timing, with the nucleation of condensed holin rafts on the inner membrane followed by the nucleation of a hole within those rafts. The nucleation of holin rafts accounts for most of the delay of lysis after induction. Our simulations of this model recover the accurate lysis timing seen experimentally and show that the timing accuracy is optimal. An enhanced holin-holin interaction is needed in our model to recover experimental lysis delays after the application of membrane poison, and such early triggering of lysis is possible only after the inner membrane is supersaturated with holin. Antiholin reduces the delay between membrane depolarization and lysis and leads to an earlier time after which triggered lysis is possible.

Ryan, Gillian L.; Rutenberg, Andrew D.

2007-01-01

392

Ribosome Biogenesis and the Translation Process in Escherichia coli  

PubMed Central

Summary: Translation, the decoding of mRNA into protein, is the third and final element of the central dogma. The ribosome, a nucleoprotein particle, is responsible and essential for this process. The bacterial ribosome consists of three rRNA molecules and approximately 55 proteins, components that are put together in an intricate and tightly regulated way. When finally matured, the quality of the particle, as well as the amount of active ribosomes, must be checked. The focus of this review is ribosome biogenesis in Escherichia coli and its cross-talk with the ongoing protein synthesis. We discuss how the ribosomal components are produced and how their synthesis is regulated according to growth rate and the nutritional contents of the medium. We also present the many accessory factors important for the correct assembly process, the list of which has grown substantially during the last few years, even though the precise mechanisms and roles of most of the proteins are not understood.

Kaczanowska, Magdalena; Ryden-Aulin, Monica

2007-01-01

393

Production of lycopene by metabolically-engineered Escherichia coli.  

PubMed

Escherichia coli strain CAR001 that produces ?-carotene was genetically engineered to produce lycopene by deleting genes encoding zeaxanthin glucosyltransferase (crtX) and lycopene ?-cyclase (crtY) from the crtEXYIB operon. The resulting strain, LYC001, produced 10.5 mg lycopene/l (6.5 mg/g dry cell weight, DCW). Modulating expression of genes encoding ?-ketoglutarate dehydrogenase, succinate dehydrogenase and transaldolase B within central metabolic modules increased NADPH and ATP supplies, leading to a 76 % increase of lycopene yield. Ribosome binding site libraries were further used to modulate expression of genes encoding 1-deoxy-D-xylulose-5-phosphate synthase (dxs) and isopentenyl diphosphate isomerase (idi) and the crt gene operon, which improved the lycopene yield by 32 %. The optimal strain LYC010 produced 3.52 g lycopene/l (50.6 mg/g DCW) in fed-batch fermentation. PMID:24806808

Sun, Tao; Miao, Liangtian; Li, Qingyan; Dai, Guanping; Lu, Fuping; Liu, Tao; Zhang, Xueli; Ma, Yanhe

2014-07-01

394

The multisubunit active site of fumarase C from escherichia coli.  

SciTech Connect

The crystal structure of the tetrameric enzyme, fumarase C from Escherichia coli, has been determined to a resolution of 2.0 Angstroms. A tungstate derivative used in the X-ray analysis is a competitive inhibitor and places the active site of fumarase in a region which includes atoms from three of the four subunits. The polypeptide conformation is similar to that of {delta}-crystallin and is comprised of three domains. The central domain, D2, is a unique five-helix bundle. The association of the D2 domains results in a tetramer which has a core of 20 {alpha}-helices. The other two domains, D1 and D3, cap the helical bundle on opposite ends giving both the single subunit and the tetramer a dumbbell-like appearance. Fumarase C has sequence homology to the eukaryotic fumarases, aspartase, arginosuccinate lyase, adenylosuccinate lyase and {delta}-crystallin.

Weaver, T. M.; Levitt, D. G.; Donnelly, M. I.; Wilkins-Stevens, P.; Banaszak, L. J.; Univ. of Minnesota

1995-08-01

395

Chromatographic Analysis of the Escherichia coli Polysialic Acid Capsule  

PubMed Central

Summary Polysialic acid capsules are the major virulence factors in Escherichia coli K1, K92, and groups B and C meningococci. The sialic acid monomers (2-keto-3-deoxy-5-acetamido-7,8,9-d-glycero-d-galacto-nonulosonic acids) comprising these homopolymeric polysaccharide chains can be selectively modified with 1,2-diamino-4,5-methylenedioxy-benzene to produce highly fluorescent quinoxalinone derivatives distinguished by their elution times during reverse phase chromatography. Here, we describe methods to release the constituent capsular polysialic acid monomers, detect, and quantify them by sensitive fluorometry. There are relatively few 2-keto acids in bacteria, making it possible to rapidly analyze samples even without prior purification of capsular polysaccharides.

Steenbergen, Susan M.; Vimr, Eric R.

2014-01-01

396

Some Effects of Visible Light on Escherichia coli1  

PubMed Central

Light above 400 nm had selective effects on Escherichia coli ML-308: several processes or enzymes were strongly inhibited, whereas others were relatively unaffected. There was a correlation between the inhibition of respiration and the inhibition of active uptake of glycine. However, phenylalanine uptake did not show such a correlation. The decrease in adenosine 5?-triphosphate level during the first few minutes of illumination resembled the inactivation kinetics of phenylalanine uptake. The results suggest that phenylalanine uptake may not depend greatly on oxidative energy and may depend on the adenosine 5?-triphosphate level. The results for glycine suggest either that its active uptake and respiration involve a common photosensitive component or alternately, that only the respiratory chain contains the photosensitive component, and that glycine uptake is coupled almost exclusively to respiration. The critical photochemical lesion does not involve d-lactate dehydrogenase, succinate dehydrogenase, or l-?-glycerophosphate dehydrogenase since their inactivation rate is markedly lower than that for respiration. Images

D'Aoust, Jean Y.; Giroux, J.; Barran, L. R.; Schneider, Henry; Martin, W. G.

1974-01-01

397

Tandem adaptation with a common design in Escherichia coli chemotaxis.  

PubMed

We analyze a model for motor-level adaptation in Escherichia coli based upon the premise that clockwise (CW) and counter-clockwise (CCW) states have different preferred numbers of FliM subunits. We show that this model provides a simple mechanism for the recently observed motor-level adaptation, and it also explains the long-lasting puzzle on the thresholds observed when tethered cells are used to monitor responses to temporal ramps. We note that the motor-level adaptation has the same negative-feedback network design as the upstream receptor-level adaptation, and the tandem architecture of one control circuit followed by the other mitigates the effects of cell-to-cell variation and broadens the range of stimuli over which cells optimally respond. PMID:22922485

Tu, Yuhai; Berg, Howard C

2012-11-01

398

pH Stability of penicillin acylase from Escherichia coli.  

PubMed

The inactivation kinetics of penicillin acylase from Escherichia coli have been investigated over a wide pH range at 25 and 50 degrees C. The enzyme was very stable in neutral solutions and quickly lost its catalytic activity in acidic and alkaline solutions. In all cases, the inactivation proceeded according to first order reaction kinetics. Analysis of the pH dependence of enzyme stability provides evidence that stable penicillin acylase conformation is maintained by salt bridges. Destruction of the salt bridges due to protonation/deprotonation of the amino acid residues forming these ion pairs causes inactivation by formation of the unstable "acidic" EH(4)(3+), EH(3)(2+), EH(2)(+) and "alkaline" E(-) enzyme forms. At temperatures above 35 degrees C penicillin acylase apparently undergoes a conformational change that is accompanied by destruction of one of these salt bridges and change in the catalytic properties. PMID:15627395

Guranda, D T; Volovik, T S; Svedas, V K

2004-12-01

399

Cervical epidural abscess following an Escherichia coli urinary tract infection.  

PubMed

A previously healthy 64-year-old man developed an Escherichia coli spinal epidural abscess (SEA) isolated to the cervical vertebrae posturinary tract infection 9 days previously. He subsequently underwent emergent surgical decompression followed by a prolonged course of intravenous antibiotics. He is symptom free at 1-year follow-up. SEA is an uncommon condition. Even with modern surgical techniques and antimicrobial agents, the mortality remains significant. Intravenous drug use, spinal procedures and medical conditions such as diabetes, Crohn's disease and chronic renal failure are all known risk factors for SEA and the majority of cases are associated with at least one of these risk factors. The case report highlights the importance of maintaining a high index of suspicion for this condition even in patients without established risk factors who present with red flag symptoms: back pain, fever and neurological deficit, as the consequences of a delayed diagnosis can be severe. PMID:24473426

O'Neill, Shane C; Baker, Joseph F; Ellanti, Prasad; Synnott, Keith

2014-01-01

400

Structure and mechanism of Escherichia coli type I signal peptidase.  

PubMed

Type I signal peptidase is the enzyme responsible for cleaving off the amino-terminal signal peptide from proteins that are secreted across the bacterial cytoplasmic membrane. It is an essential membrane bound enzyme whose serine/lysine catalytic dyad resides on the exo-cytoplasmic surface of the bacterial membrane. This review discusses the progress that has been made in the structural and mechanistic characterization of Escherichia coli type I signal peptidase (SPase I) as well as efforts to develop a novel class of antibiotics based on SPase I inhibition. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24333859

Paetzel, Mark

2014-08-01

401

Expression of active, human lysyl oxidase in Escherichia coli.  

PubMed

Lysyl oxidase (LO) is a copper amine oxidase of the extracellular matrix which initiates covalent cross-linking in collagens and elastin. Human LO was expressed in Escherichia coli. At 37 degrees C, large amounts of protein were obtained, but in the form of insoluble aggregates. Lowering the growth temperature, and reducing the amount of inducer, resulted in the production of soluble LO, which was active on a degrees [3H]lysine-labeled elastin substrate. LO was also targeted to the periplasm as a fusion protein with the pelb signal peptide. The periplasmic enzyme was soluble, active and inhibited by beta-aminopropionitrile. Production of the carbonyl co-factor is therefore not a limitation in the expression of active LO in bacteria. PMID:8985148

Ouzzine, M; Boyd, A; Hulmes, D J

1996-12-16

402

Growth-phase regulation of the Escherichia coli thioredoxin gene.  

PubMed

The two promoters of Escherichia coli trxA gene were separately cloned into pKO100 as well as pJEL170. Galactokinase expression in cells containing the pKO100 derivatives was found to be negatively correlated with growth rate and was 6- to 20-fold higher in stationary cultures than in exponential cultures. The expression of trxA-galK was induced by amino acid starvation in a RelA(+) strain but not in an isogenic Rel(-) strain indicating that the control involves guanosine 3',5'-bispyrophosphate (ppGpp). RpoS, which appears to be essential for expression of most stationary phase expressed genes, is not required for trxA expression. Increased expression of relA, which increases ppGpp concentration, increases trxA expression. PMID:10760563

Lim, C J; Daws, T; Gerami-Nejad, M; Fuchs, J A

2000-04-25

403

Metabolic control of persister formation in Escherichia coli.  

PubMed

Bacterial persisters are phenotypic variants that form from the action of stress response pathways triggering toxin-mediated antibiotic tolerance. Although persisters form during normal growth from native stresses, the pathways responsible for this phenomenon remain elusive. Here we have discovered that carbon source transitions stimulate the formation of fluoroquinolone persisters in Escherichia coli. Further, through a combination of genetic, biochemical, and flow cytometric assays in conjunction with a mathematical model, we have reconstructed a molecular-level persister formation pathway from initial stress (glucose exhaustion) to the activation of a metabolic toxin-antitoxin (TA) module (the ppGpp biochemical network) resulting in inhibition of DNA gyrase activity, the primary target of fluoroquinolones. This pathway spans from initial stress to antibiotic target and demonstrates that TA behavior can be exhibited by a metabolite-enzyme interaction (ppGpp-SpoT), in contrast to classical TA systems that involve only protein and/or RNA. PMID:23665232

Amato, Stephanie M; Orman, Mehmet A; Brynildsen, Mark P

2013-05-23

404

A synthetic Escherichia coli predator-prey ecosystem  

PubMed Central

We have constructed a synthetic ecosystem consisting of two Escherichia coli populations, which communicate bi-directionally through quorum sensing and regulate each other's gene expression and survival via engineered gene circuits. Our synthetic ecosystem resembles canonical predator–prey systems in terms of logic and dynamics. The predator cells kill the prey by inducing expression of a killer protein in the prey, while the prey rescue the predators by eliciting expression of an antidote protein in the predator. Extinction, coexistence and oscillatory dynamics of the predator and prey populations are possible depending on the operating conditions as experimentally validated by long-term culturing of the system in microchemostats. A simple mathematical model is developed to capture these system dynamics. Coherent interplay between experiments and mathematical analysis enables exploration of the dynamics of interacting populations in a predictable manner.

Balagadde, Frederick K; Song, Hao; Ozaki, Jun; Collins, Cynthia H; Barnet, Matthew; Arnold, Frances H; Quake, Stephen R; You, Lingchong

2008-01-01

405

Bloody coli: a Gene Cocktail in Escherichia coli O104:H4  

PubMed Central

ABSTRACT A recent study published in mBio [Y. H. Grad et al., mBio 4(1):e00452-12, 2013] indicates that a rapid introgressive evolution has occurred in Escherichia coli O104:H4 by sequential acquisition of foreign genetic material involving pathogenicity traits. O104 genetic promiscuity cannot be readily explained by high population sizes. However, extensive interactions leading to cumulative assemblies of pathogenicity genes might be assured by small K-strategist populations exploiting particular intestinal niches. Next-generation sequencing technologies will be critical to detect particular “gene cocktails” as potentially pathogenic ensembles and to predict the risk of future outbreaks.

Baquero, Fernando; Tobes, Raquel

2013-01-01

406

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

PubMed Central

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.

Jafari, Anis; Aslani, Mohammad Mehdi

2013-01-01

407

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

PubMed

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. PMID:23992508

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

408

Sequences of the envMgene and of two mutated alleles in Escherichia coli  

Microsoft Academic Search

~~ ~ The nucleotide sequence of the Escherichia coli envM gene was determined. It codes for a protein of 262 amino acids. The sequences of the E coli and Salmonella typhimurium EnvM proteins are 98 yo identical. Gene envM is preceded in E. coli by a 43-nucleotide-long structural element, termed 'box C', which occurs in several E. coli operons between

HELMUT BERGLER; GREGOR HOGENAUER; FRIEDERIKE TURNOWSKY

1992-01-01

409

Differentiation of pathogenic Escherichia coli strains in Brazilian children by PCR.  

PubMed Central

A PCR technique to differentiate pathogenic enteric Escherichia coli strains in a field setting was evaluated. Among 76 children with acute diarrhea, this technique identified 12 children (16%) with enterotoxigenic E. coli, 6 (8%) with enteropathogenic E. coli, and 1 (1%) with enteroinvasive E. coli infection. Compared with the conventional assays, the PCR method proved to be simpler, more rapid, and inexpensive and therefore suitable for application in a developing-country field setting.

Tornieporth, N G; John, J; Salgado, K; de Jesus, P; Latham, E; Melo, M C; Gunzburg, S T; Riley, L W

1995-01-01

410

Antimicrobial resistance of Escherichia coli O26 and O111 isolates from cattle and their characteristics  

Microsoft Academic Search

The present study was to investigate antimicrobial resistance profiles of Escherichia coli O26 and O111 from cattle and to characterize the virulence genes of the resistant isolates. This paper reports the high prevalence of antimicrobial resistant E. coli O26 and O111 from cattle. Among 37 E. coli O26 and 25 E. coli O111 isolates from the fecal specimens obtained from

John Hwa Lee

2009-01-01

411

Differentiation of pathogenic Escherichia coli strains in Brazilian children by PCR.  

PubMed

A PCR technique to differentiate pathogenic enteric Escherichia coli strains in a field setting was evaluated. Among 76 children with acute diarrhea, this technique identified 12 children (16%) with enterotoxigenic E. coli, 6 (8%) with enteropathogenic E. coli, and 1 (1%) with enteroinvasive E. coli infection. Compared with the conventional assays, the PCR method proved to be simpler, more rapid, and inexpensive and therefore suitable for application in a developing-country field setting. PMID:7615758

Tornieporth, N G; John, J; Salgado, K; de Jesus, P; Latham, E; Melo, M C; Gunzburg, S T; Riley, L W

1995-05-01

412

Bacteriophages with the Ability to Degrade Uropathogenic Escherichia Coli Biofilms  

PubMed Central

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.

Chibeu, Andrew; Lingohr, Erika J.; Masson, Luke; Manges, Amee; Harel, Josee; Ackermann, Hans-W.; Kropinski, Andrew M.; Boerlin, Patrick

2012-01-01

413

Cytochemical Localization of Certain Phosphatases in Escherichia coli  

PubMed Central

Cytochemical studies of Escherichia coli at the light and electron microscopic levels have revealed alkaline phosphatase, hexose monophosphatase, and cyclic phosphodiesterase reaction products in the periplasmic space and at the cell surface. In preparations for both light and electron microscopy, reaction product filled polar caplike enlargements of the periplasmic space, such as those described in plasmolyzed cells, indicating significant terminal concentrations of these enzymes; dense substance was often seen within these polar caps in morphological specimens. Staining of the bacterial surface was commonly encountered, but could represent artifactual accumulation of precipitate along the cell wall. Alkaline phosphatase was demonstrated with several substrates (ethanolamine phosphate, glycerophosphate, p-nitrophenylphosphate, and glucose-6-phosphate) over a wide pH range in a bacterial strain (C-90) known to be constitutive for this enzyme, whereas strains deficient in this enzyme (U-7, repressed K-37), showed no activity with these substrates. Hexose monophosphatase and cyclic phosphodiesterase activities were characterized by reaction-product deposition with specific substrates at acid or neutral, but not at alkaline, pH in strains of E. coli lacking alkaline phosphatase (U-7 and repressed K-37). Fixation in Formalin or the use of calcium as a capture reagent seemed to interfere with periplasmic staining in cells prepared for electron microscopy. Formalin fixation had little effect on biochemical assays of the phosphatase activity of intact cells in suspension, but partially reduced the activity evident in sonically treated extracts or in suspensions of dispersed cryostat sections. Glutaraldehyde treatment impaired enzyme activity more drastically. Images

Wetzel, Bruce K.; Spicer, S. S.; Dvorak, Harold F.; Heppel, Leon A.

1970-01-01

414

Structure of CFA/I fimbriae from enterotoxigenic Escherichia coli  

SciTech Connect

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

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

2009-10-21

415

Buoyant density constancy during the cell cycle of Escherichia coli  

SciTech Connect

Cell buoyant densities were determined in exponentially growing cultures of Escherichia coli B/r NC32 and E. coli K-12 PAT84 by equilibrium centrifugation in Percoll gradients. Distributions within density bands were measured as viable cells or total numbers of cells. At all growth rates, buoyant densities had narrow normal distributions with essentially the same value for the coefficient of variation, 0.15%. When the density distributions were determined in Ficoll gradients, they were more than twice as broad, but this increased variability was associated with the binding of Ficoll to the bacteria. Mean cell volumes and cell lengths were independent of cell densities in Percoll bands, within experimental errors, both in slowly and in rapidly growing cultures. Buoyant densities of cells separated by size, and therefore by age, in sucrose gradients also were observed to be independent of age. The results make unlikely any stepwise change in mean buoyant density of 0.1% or more during the cycle. These results also make it unlikely that signaling functions for cell division or for other cell cycle events are provided by density variations. 10 references, 3 figures, 3 tables.

Kubitschek, H.E.; Baldwin, W.W.; Graetzer, R.

1983-09-01

416

Structure and Biochemical Activities of Escherichia coli MgsA  

SciTech Connect

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

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

2012-02-27

417

[Production of D-mannitol by metabolically engineered Escherichia coli].  

PubMed

D-Mannitol has wide applications in food, pharmaceutical, and chemical industries. In this study, we constructed a genetically stable Escherichia coli strain for D-mannitol production by integrating mannitol dehydrogenase (mdh) and fructose permease (fupL) genes of Leuconostoc pseudomesenteroides ATCC 12291 into chromosome of E. coli ATCC 8739 and inactivating other fermentation pathways (including pyruvate formate-lyase, lactate dehydrogenase, fumarate reductase, alcohol dehydrogenase, methylglyoxal synthase and pyruvate oxidase). Using mineral salts medium with glucose and fructose as carbon sources, the engineered strain could produce 1.2 mmol/L D-mannitol after anaerobic fermentation for 6 days. Based on the coupling of cell growth and D-mannitol production, metabolic evolution was used to improve D-mannitol production. After evolution for 80 generations, D-mannitol titer increased 2.6-fold and mannitol dehydrogenase activity increased 2.8-fold. Genetically stable strains constructed in this work could ferment sugars to produce D-mannitol without the addition of antibiotics, inducers and formate, which was favorable for industrial production. PMID:24432660

Wang, Xiaofang; Chen, Jing; Liu, Pingping; Xu, Hongtao; Yu, Peng; Zhang, Xueli

2013-10-01

418

Dissecting Escherichia coli Outer Membrane Biogenesis Using Differential Proteomics  

PubMed Central

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.

Martorana, Alessandra M.; Motta, Sara; Di Silvestre, Dario; Falchi, Federica; Deho, Gianni; Mauri, Pierluigi; Sperandeo, Paola; Polissi, Alessandra

2014-01-01

419

Rapid turnover of mannitol-1-phosphate in Escherichia coli.  

PubMed Central

The phosphate moiety of D-mannitol-1-phosphate in Escherichia coli is subject to rapid turnover and is in close equilibrium with Pi and the phosphorus of fructose-1,6-bisphosphate. These three compounds account for the bulk of 32P label found in cells after several minutes of uptake of 32Pi and mannitol-1-phosphate represents some 30% of this label. Mannitol-1-phosphate occurs in E. coli grown on a variety of carbon sources, in the absence of D-mannitol, and is synthesized de novo even in mutants lacking mannitol-1-phosphate dehydrogenase. The mannitol moiety of mannitol-1-phosphate was not affected during the total chase of the P moiety, which exchanged with a half-life of about 30 s. These findings suggest that the rapid equilibration of the phosphorus is a function of an enzyme, possibly a component of the phosphotransferase system, capable of forming a complex that allows the exchange of the phosphate without the equilibration of the mannitol moiety with free mannitol.

Rosenberg, H; Pearce, S M; Hardy, C M; Jacomb, P A

1984-01-01

420

Rational design of Escherichia coli for L-isoleucine production.  

PubMed

Metabolic engineering of Escherichia coli was performed to construct a 100% rationally engineered strain capable of overproducing L-isoleucine, an important branched-chain amino acid. The thrABC (encoding L-threonine biosynthetic enzymes), ilvA (encoding feedback-resistant threonine dehydratase), ilvIH (encoding feedback-resistant acetohydroxy acid synthase III), and ygaZH (encoding branched-chain amino acid exporter) genes were amplified by plasmid-based overexpression. The ilvCED (encoding L-isoleucine biosynthetic enzymes) and lrp (encoding global regulator Lrp) genes were also amplified by chromosomal promoter replacement in order to further increase the flux toward L-isoleucine. The final engineered E. coli strain was able to produce 9.46 g/L of L-isoleucine with a yield of 0.14 g/g of glucose by fed-batch culture. The overall design principles described here for the production of highly regulated product should be useful in designing strains for the production of other similar bioproducts. PMID:23656230

Park, Jin Hwan; Oh, Jae Eun; Lee, Kwang Ho; Kim, Ji Young; Lee, Sang Yup

2012-11-16

421

Hemolysin from Escherichia coli induces oxidative stress in blood.  

PubMed

Hemolysin (HlyA) produced by some stains of Escherichia coli is considered to be an important virulence factor of those bacteria. On the other hand, reactive oxygen species (ROS) have been reported to be involved in the pathogenesis of different diseases via oxidative stress generation. The purpose of this study was to analyze the capacity of HlyA to induce oxidative stress in whole blood cultures (WBCs). To this end, ROS production, the damage induced in lipids and proteins, and the antioxidant defense system was evaluated in blood cultures exposed to low concentrations of HlyA. We found that HlyA increased the level of free radicals detected by chemiluminescence assay. Moreover, lipid peroxidation and protein damage was significantly increased in cultures treated with HlyA in comparation with those found in control cultures. On the other hand, a decrease in total antioxidant capacity of plasma and in the activity of superoxide dismutase (SOD) was observed in plasma from blood treated with HlyA. Collectively, our data demonstrate that low concentrations of E. coli hemolysin induced oxidative stress in WBCs with the induction of different oxidative damage biomarkers. PMID:23567037

Baronetti, José Luis; Villegas, Natalia Angel; Aiassa, Virginia; Paraje, María Gabriela; Albesa, Inés

2013-08-01

422

Population Diversity of ORFan Genes in Escherichia coli  

PubMed Central

The origin and evolution of “ORFans” (suspected genes without known relatives) remain unclear. Here, we take advantage of a unique opportunity to examine the population diversity of thousands of ORFans, based on a collection of 35 complete genomes of isolates of Escherichia coli and Shigella (which is included phylogenetically within E. coli). As expected from previous studies, ORFans are shorter and AT-richer in sequence than non-ORFans. We find that ORFans often are very narrowly distributed: the most common pattern is for an ORFan to be found in only one genome. We compared within-species population diversity of ORFan genes with those of two control groups of non-ORFan genes. Patterns of population variation suggest that most ORFans are not artifacts, but encode real genes whose protein-coding capacity is conserved, reflecting selection against nonsynonymous mutations. Nevertheless, nonsynonymous nucleotide diversity is higher than for non-ORFans, whereas synonymous diversity is roughly the same. In particular, there is a several-fold excess of ORFans in the highest decile of diversity relative to controls, which might be due to weaker purifying selection, positive selection, or a subclass of ORFans that are decaying.

Yu, Guoqin; Stoltzfus, Arlin

2012-01-01

423

Control of methionine biosynthesis in Escherichia coli by proteolysis.  

PubMed

Most bacterial proteins are stable, with half-lives considerably longer than the generation time. In Escherichia coli, the few exceptions are unstable regulatory proteins. The results presented here indicate that the first enzyme in methionine biosynthesis - homoserine trans-succinylase (HTS) - is unstable and subject to energy-dependent proteolysis. The enzyme is stable in triple mutants defective in Lon-, HslVU- and ClpP-dependent proteases. The instability of the protein is determined by the amino-terminal part of the protein, and its removal or substitution by the N-terminal part of beta-galactosidase confers stability. The effect of the amino-terminal segment is not caused by the N-end rule, as substitution of the first amino acid does not affect the stability of the protein. HTS is the first biosynthetic E. coli enzyme shown to have a short half-life and may represent a group of biosynthetic enzymes whose expression is controlled by proteolysis. Alternatively, the proteolytic processing of HTS may be unique to this enzyme and could reflect its central role in regulating bacterial growth, especially at elevated temperatures. PMID:10998174

Biran, D; Gur, E; Gollan, L; Ron, E Z

2000-09-01

424

Expression and purification of soluble monomeric streptavidin in Escherichia coli.  

PubMed

We recently reported the engineering of monomeric streptavidin (mSA) for use in monomeric detection of biotinylated ligands. Although mSA can be expressed functionally on the surface of mammalian cells and yeast, the molecule does not fold correctly when expressed in Escherichia coli. Refolding from inclusion bodies is cumbersome and yields a limited amount of purified protein. Improving the final yield should facilitate its use in biotechnology. We tested the expression and purification of mSA fused to GST, MBP, thioredoxin, and sumo tags to simplify its purification and improve the yield. The fusion proteins can be expressed solubly in E. coli and increase the yield by more than 20-fold. Unmodified mSA can be obtained by proteolytically removing the fusion tag. Purified mSA can be immobilized on a solid matrix to purify biotinylated ligands. Together, expressing mSA as a fusion with a solubilization tag vastly simplifies its preparation and increases its usability in biotechnology. PMID:24691867

Demonte, Daniel; Dundas, Christopher M; Park, Sheldon

2014-07-01

425

Expression, purification and characterization of galectin-1 in Escherichia coli.  

PubMed

As a member of beta-galactoside-binding proteins family, Galectin-1 (Gal-1) contains a single carbohydrate recognition domain, by means of which it can bind glycans both as a monomer and as a homodimer. Gal-1 is implicated in modulating cell-cell and cell-matrix interactions and may act as an autocrine negative growth factor that regulates cell proliferation. Besides, it can also suppress TH1 and TH17 cells by regulating dendritic cell differentiation or suppress inflammation via IL-10 and IL-27. In the present study, Gal-1 monomer and concatemer (Gal-1?), which can resemble Gal-1 homodimer, were expressed in Escherichia coli and their bioactivities were analyzed. The results of this indicate that both Gal-1 and Gal-1? were expressed in E. coli in soluble forms with a purity of over 95% after purifying with ion-exchange chromatography. Clearly, both Gal-1 and Gal-1? can effectively promote erythrocyte agglutination in hemagglutinating activity assays and inhibit Jurkat cell proliferation in MTT assays. All these data demonstrate that bacterially-expressed Gal-1 and Gal-1? have activities similar to those of wild type human Gal-1 whereas the bioactivity of concatemer Gal-1? was stronger than those of the bacterially-expressed and wild type human Gal. PMID:24718258

Shu, Zhen; Li, Jing; Mu, Nan; Gao, Yuan; Huang, Tonglie; Zhang, Ying; Wang, Zenglu; Li, Meng; Hao, Qiang; Li, Weina; He, Liqing; Zhang, Cun; Zhang, Wei; Xue, Xiaochang; Zhang, Yingqi

2014-07-01

426

Metabolic engineering of Escherichia coli using synthetic small regulatory RNAs.  

PubMed

Small regulatory RNAs (sRNAs) regulate gene expression in bacteria. We designed synthetic sRNAs to identify and modulate the expression of target genes for metabolic engineering in Escherichia coli. Using synthetic sRNAs for the combinatorial knockdown of four candidate genes in 14 different strains, we isolated an engineered E. coli strain (tyrR- and csrA-repressed S17-1) capable of producing 2 g per liter of tyrosine. Using a library of 130 synthetic sRNAs, we also identified chromosomal gene targets that enabled substantial increases in cadaverine production. Repression of murE led to a 55% increase in cadaverine production compared to the reported engineered strain (XQ56 harboring the plasmid p15CadA). The design principles and the engineering strategy using synthetic sRNAs reported here are generalizable to other bacteria and applicable in developing superior producer strains. The ability to fine-tune target genes with designed sRNAs provides substantial advantages over gene-knockout strategies and other large-scale target identification strategies owing to its easy implementation, ability to modulate chromosomal gene expression without modifying those genes and because it does not require construction of strain libraries. PMID:23334451

Na, Dokyun; Yoo, Seung Min; Chung, Hannah; Park, Hyegwon; Park, Jin Hwan; Lee, Sang Yup

2013-02-01

427

A Role for Topoisomerase III in Escherichia coli Chromosome Segregation  

PubMed Central

Summary The cellular function of Escherichia coli topoisomerase III remains elusive. We show that rescue of temperature-sensitive mutants in parE and parC (encoding the subunits of the chromosomal decatenase topoisomerase IV) at restrictive temperatures by high-copy suppressors is strictly dependent on topB (encoding topoisomerase III). Double mutants of parE?topB and parC?topB were barely viable, grew slowly, and were defective in chromosome segregation at permissive temperatures. The topB mutant phenotype did not result from accumulation of toxic recombination intermediates, because it was not relieved by mutations in either recQ or recA. In addition, in an otherwise wild-type genetic background, ?topB cells treated with the type II topoisomerase inhibitor novobiocin displayed aberrant chromosome segregation. This novobiocin sensitivity was attributable to an increased demand for topoisomerase IV and is unlikely to define a new role for topoiosmerase III; therefore, these results suggest that topoisomerase III participates in orderly and efficient chromosome segregation in E. coli.

Perez-Cheeks, Brenda A.; Lee, Chong; Hayama, Ryo; Marians, Kenneth J.

2012-01-01

428

Nutrient dependence of RNase E essentiality in Escherichia coli.  

PubMed

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

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

2013-03-01

429

Porin activity in the osmotic shock fluid of Escherichia coli.  

PubMed Central

Osmotic shock fluid of Escherichia coli exhibited pore-forming activity. This activity could be followed by an in vitro assay based on the conductivity increase for ions due to the presence of pores in black lipid membranes. The histogram (the distribution of conductivity increments in a single pore experiment) obtained with osmotic shock fluid from E. coli was identical to the histogram obtained by detergent-solubilized porin isolated from the outer membrane. The osmotic shock fluid from porin-negative mutants also exhibited pore activity, although the histogram and ion specificity were different from those of porin. Antibodies raised against detergent-solubilized porin were able to form precipitin lines by the Ouchterlony immunodiffusion technique when shock fluids, but not detergent-solubilized porin, were used. These antibodies prevented the formation of pores when shock fluids contained porin but not when shock fluids obtained from porin-negative mutants were used. Macroscopic membrane conductivity of shock fluids due to porin exhibited a concentration dependence, in contrast to detergent-solubilized porin. These results indicate that the hydrodynamic properties of periplasmic or "soluble" porin are different from those of the detergent-solubilized porin of the outer membrane. Periplasmic porin comprises about 0.7% of total protein in the osmotic shock fluid. Images

Benz, R; Boehler-Kohler, B A; Dieterle, R; Boos, W

1978-01-01

430

Kinetics of ethanol production by recombinant Escherichia coli KO11  

SciTech Connect

The fermentation kinetics for separate as well as simultaneous glucose and xylose fermentation with recombinant ethanologenic Escherichia coli KO11 are presented. Glucose and xylose were consumed simultaneously and exhibited mutual inhibition. The glucose exhibited 15 times stronger inhibition in xylose fermentation than vice versa. The fermentation of condensate from steam-pretreated willow (Salix) was investigated. The kinetics were studied in detoxified as well as in nondetoxified condensate. The fermentation of the condensate followed two phases: first the glucose and some of the pentoses (xylose in addition to small amounts of arabinose) were fermented simultaneously, and then the remaining part of the pentoses were fermented. The rate of the first phase was independent of the detoxification method used, whereas the rate of the second phase was found to be strongly dependent. When the condensate was detoxified with overliming in combination with sulfite, which was the best detoxification method investigated, the sugars in the condensate, 9 g/L, were fermented in 11 h. The same fermentation took 150 h in nondetoxified condensate. The experimental data were used to develop an empirical model, describing the batch fermentation of recombinant E. coli KO11 in the condensate. The model is based on Monod kinetics including substrate and product inhibition and the sum of the inhibition exerted by the rest of the inhibitors, lumped together.

Olsson, L.; Hahn-Haegerdal, B. (Univ. of Lund (Sweden) Lund Inst. of Tech. (Sweden))

1995-02-20

431

GATC sequence and mismatch repair in Escherichia coli.  

PubMed

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

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

1986-08-01

432

Nutrient Dependence of RNase E Essentiality in Escherichia coli  

PubMed Central

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

Tamura, Masaru; Moore, Christopher J.

2013-01-01

433

Recombinational Repair of DNA Damage in Escherichia coli and Bacteriophage ?  

PubMed Central

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

Kuzminov, Andrei

1999-01-01

434

Determining straining of Escherichia coli from breakthrough curves  

NASA Astrophysics Data System (ADS)

Though coliform bacteria are used world wide as an indication of faecal pollution, the parameters determining the transport of Escherichia coli in aquifers are relatively unknown, especially for the period after the clean bed collision phase brought about by prolonged infiltration of waste water. In this research, the breakthrough curves of E. coli after total flushing of 50-200 pore volumes were studied for various influent concentrations in various sediments at different pore water flow velocities. The results indicated that straining in Dead End Pores (DEPs) was an important process that dominated bacteria breakthrough in fine-grained sediment (0.06-0.2 mm). The filling of the DEP space with bacteria took 5-65 pore volumes and was dependent on concentration. Column breakthrough curves were modelled and from this the DEP volumes were determined. These volumes (0.21-0.35% of total column volume) corresponded well with values calculated with a formula based on purely geometrical considerations and also with values calculated with a pore size density function. For this function the so-called Van Genuchten parameters of the sediments used in the experiments were determined. The results indicate that straining might be a dominant process affecting colloid transport in the natural environment and therefore it is concluded that proper knowledge of the pore size distribution is crucial to an understanding of the retention of bacteria.

Foppen, J. W. A.; Mporokoso, A.; Schijven, J. F.

2005-02-01

435

Production of acetol from glycerol using engineered Escherichia coli.  

PubMed

Escherichia coli Lin43 is a strain which has some mutations in glycerol kinase (GlpK) and the repressor for the glycerol 3-phosphate regulon (GlpR). When exposed to glycerol, it quickly accumulates lethal levels of methylglyoxal, which is a precursor of acetol; acetol is important for the manufacture of polyols, acrolein, dyes, and skin tanning agents. This work reports the engineering of E. coli Lin 43 for the conversion of glycerol into acetol. First, the glyoxalase system was interrupted by deleting the gloA gene, which increased the acetol yield by 32%. In addition, the aldehyde reductase YqhD was overexpressed which led to an increase of acetol production by 11.4-fold. Acetol production was optimized by varying the cell density, glycerol concentration, supplemental carbon source, pH and temperature. Under the optimal conditions (OD600=20, 20 g/L glycerol, 2g/L succinate, pH 7.0, and 28°C), we obtained 5.4 g/L acetol in 21 h. PMID:24113547

Zhu, Hongliang; Yi, Xianyang; Liu, Yi; Hu, Hongbo; Wood, Thomas K; Zhang, Xuehong

2013-12-01

436

Production of human prolyl 4-hydroxylase in Escherichia coli.  

PubMed

Prolyl 4-hydroxylase (P4H) catalyzes the post-translational hydroxylation of proline residues in collagen strands. The enzyme is an alpha2beta2 tetramer in which the alpha subunits contain the catalytic active sites and the beta subunits (protein disulfide isomerase) maintain the alpha subunits in a soluble and active conformation. Heterologous production of the native alpha2beta2 tetramer is challenging and had not been reported previously in a prokaryotic system. Here, we describe the production of active human P4H tetramer in Escherichia coli from a single bicistronic vector. P4H production requires the relatively oxidizing cytosol of Origami B(DE3) cells. Induction of the wild-type alpha(I) cDNA in these cells leads to the production of a truncated alpha subunit (residues 235-534), which assembles with the beta subunit. This truncated P4H is an active enzyme, but has a high Km value for long substrates. Replacing the Met235 codon with one for leucine removes an alternative start codon and enables production of full-length alpha subunit and assembly of the native alpha2beta2 tetramer in E. coli cells to yield 2 mg of purified P4H per liter of culture (0.2 mg/g of cell paste). We also report a direct, automated assay of proline hydroxylation using high-performance liquid chromatography. We anticipate that these advances will facilitate structure-function analyses of P4H. PMID:15555944

Kersteen, Elizabeth A; Higgin, Joshua J; Raines, Ronald T

2004-12-01

437

Dissecting the roles of Escherichia coli hydrogenases in biohydrogen production.  

PubMed

Escherichia coli can perform at least two modes of anaerobic hydrogen metabolism and expresses at least two types of hydrogenase activity. Respiratory hydrogen oxidation is catalysed by two 'uptake' hydrogenase isoenzymes, hydrogenase -1 and -2 (Hyd-1 and -2), and fermentative hydrogen production is catalysed by Hyd-3. Harnessing and enhancing the metabolic capability of E. coli to perform anaerobic mixed-acid fermentation is therefore an attractive approach for bio-hydrogen production from sugars. In this work, the effects of genetic modification of the genes encoding the uptake hydrogenases, as well as the importance of preculture conditions, on hydrogen production and fermentation balance were examined. In suspensions of resting cells pregrown aerobically with formate, deletions in Hyd-3 abolished hydrogen production, whereas the deletion of both uptake hydrogenases improved hydrogen production by 37% over the parent strain. Under fermentative conditions, respiratory H2 uptake activity was absent in strains lacking Hyd-2. The effect of a deletion in hycA on H2 production was found to be dependent upon environmental conditions, but H2 uptake was not significantly affected by this mutation. PMID:17995952

Redwood, Mark D; Mikheenko, Iryna P; Sargent, Frank; Macaskie, Lynne E

2008-01-01

438

Recombinant Production of Human Interleukin 6 in Escherichia coli  

PubMed Central

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).

Nausch, Henrik; Huckauf, Jana; Koslowski, Roswitha; Meyer, Udo; Broer, Inge; Mikschofsky, Heike

2013-01-01

439

Determining straining of Escherichia coli from breakthrough curves.  

PubMed

Though coliform bacteria are used world wide as an indication of faecal pollution, the parameters determining the transport of Escherichia coli in aquifers are relatively unknown, especially for the period after the clean bed collision phase brought about by prolonged infiltration of waste water. In this research, the breakthrough curves of E. coli after total flushing of 50-200 pore volumes were studied for various influent concentrations in various sediments at different pore water flow velocities. The results indicated that straining in Dead End Pores (DEPs) was an important process that dominated bacteria breakthrough in fine-grained sediment (0.06-0.2 mm). The filling of the DEP space with bacteria took 5-65 pore volumes and was dependent on concentration. Column breakthrough curves were modelled and from this the DEP volumes were determined. These volumes (0.21-0.35% of total column volume) corresponded well with values calculated with a formula based on purely geometrical considerations and also with values calculated with a pore size density function. For this function the so-called Van Genuchten parameters of the sediments used in the experiments were determined. The results indicate that straining might be a dominant process affecting colloid transport in the natural environment and therefore it is concluded that proper knowledge of the pore size distribution is crucial to an understanding of the retention of bacteria. PMID:15683880

Foppen, J W A; Mporokoso, A; Schijven, J F

2005-02-01

440

Biosynthesis of fluorescent cyanobacterial allophycocyanin trimer in Escherichia coli.  

PubMed

Allophycocyanin (APC), a cyanobacterial photosynthetic phycobiliprotein, functions in energy transfer as a light-harvesting protein. One of the prominent spectroscopic characteristics of APC is a strong red-shift in the absorption and emission maxima when monomers are assembled into a trimer. Previously, holo-APC alpha and beta subunits (holo-ApcA and ApcB) were successfully synthesized in Escherichia coli. In this study, both holo-subunits from Synechocystis sp. PCC 6803 were co-expressed in E. coli, and found to self-assemble into trimers. The recombinant APC trimer was purified by metal affinity and size-exclusion chromatography, and had a native structure identical to native APC, as determined by characteristic spectroscopic measurements, fluorescence quantum yield, tryptic digestion analysis, and molecular weight measurements. Combined with results from a study in which only the monomer was formed, our results indicate that bilin synthesis and the subsequent attachment to apo-subunits are important for the successful assembly of APC trimers. This is the first study to report on the assembly of recombinant ApcA and ApcB into a trimer with native structure. Our study provides a promising method for producing better fluorescent tags, as well as a method to facilitate the genetic analysis of APC trimer assembly and biological function. PMID:20607408

Liu, Shaofang; Chen, Yingjie; Lu, Yandu; Chen, Huaxin; Li, Fuchao; Qin, Song

2010-08-01

441

Population diversity of ORFan genes in Escherichia coli.  

PubMed

The origin and evolution of "ORFans" (suspected genes without known relatives) remain unclear. Here, we take advantage of a unique opportunity to examine the population diversity of thousands of ORFans, based on a collection of 35 complete genomes of isolates of Escherichia coli and Shigella (which is included phylogenetically within E. coli). As expected from previous studies, ORFans are shorter and AT-richer in sequence than non-ORFans. We find that ORFans often are very narrowly distributed: the most common pattern is for an ORFan to be found in only one genome. We compared within-species population diversity of ORFan genes with those of two control groups of non-ORFan genes. Patterns of population variation suggest that most ORFans are not artifacts, but encode real genes whose protein-coding capacity is conserved, reflecting selection against nonsynonymous mutations. Nevertheless, nonsynonymous nucleotide diversity i